PREPARATION AND APPLICATION OF SULFONATED

CARBON CATALYST FOR BIODIESEL PRODUCTION

FROM WASTE COOKING OIL AND FURFURAL

PRODUCTION FROM XYLOSE

BY

MISS TRAN THI TUONG VI

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF

THE REQUIREMENTS FOR DEGREE OF

MASTER OF SCIENCE (CHEMISTRY)

DEPARTMENT OF CHEMISTRY

FACULTY OF SCIENCE AND TECHNOLOGY

THAMMASAT UNIVERSITY

ACADEMIC YEAR 2016

COPYRIGHT OF THAMMASAT UNIVERSITY

PREPARATION AND APPLICATION OF SULFONATED

CARBON CATALYST FOR BIODIESEL PRODUCTION

FROM WASTE COOKING OIL AND FURFURAL

PRODUCTION FROM XYLOSE

BY

MISS TRAN THI TUONG VI

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF

THE REQUIREMENTS FOR DEGREE OF

MASTER OF SCIENCE (CHEMISTRY)

DEPARTMENT OF CHEMISTRY

FACULTY OF SCIENCE AND TECHNOLOGY

THAMMASAT UNIVERSITY

ACADEMIC YEAR 2016

COPYRIGHT OF THAMMASAT UNIVERSITY

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Thesis Tittle PREPARATION AND APPLICATION OF

SULFONATED CARBON CATALYST FOR

BIODIESEL PRODUCTION FROM WASTE

COOKING OIL AND FURFURAL

PRODUCTION FROM XYLOSE

Author Miss Tran Thi Tuong Vi

Degree Master of Science

Major Field/Faculty/University Department of Chemistry,

Faculty of Science and Technology,

Thammasat University

Thesis Advisor Assistant Professor Chanatip Samart, D.Eng.

Thesis Co-advisor Associate Professor Prasert Reubroycharoen, D.Eng.

Academic Years 2016

ABSTRACT

This research investigated the preparation and utilization of carbon solid

acid catalyst (CM-SO3H) in both biodiesel production from waste cooking oil and

furfural production from xylose. The carbon solid acid catalyst was prepared by

sequential xylose hydrothermal carbonization and sulfonation. The CM-SO3H catalyst

was characterized the physicochemical properties and morphology by Scanning

Electron Microscope (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-

Emmett-Teller (BET) and Fourier Transform Infrared spectroscopy (FT-IR). The acid

capacity of CM-SO3H catalyst was determined by both titration with 0.1N sodium

hydroxide and temperature-programmed desorption of ammonia (NH3-TPD). The

surface area and acidity of the catalyst were 86 m2/g and 1.38 mmol/g, respectively.

The different experimental parameters were studied including catalyst loading (wt.%),

reaction time (h), reaction temperature (C) and molar ratio of feedstock. The optimized

condition of biodiesel production was 110C for 2 h to obtain 89.6% yield. Whereas

the optimized reaction condition of xylose dehydration was 155C for 2h. From this

study, this catalyst was not only approach green chemistry concept as waste utilization,

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less chemical, safe and environmentally friendly but it also performed the good catalytic

activity nearly conventional acid catalyst.

Keywords: Carbon microsphere, Carbon solid acid catalyst, Biodiesel,

Furfural, Xylose dehydration.

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ACKNOWLEDGEMENTS

During the time to study at Thammasat University as a student of master

degree, I am deeply thankful for everyone who shared the knowledge, the experience,

and the advice throughout to complete my thesis.

First of all, I would like to express my special thanks of gratitude to my

advisor, Asst. Prof. Dr. Chanatip Samart for his valuable advice, motivation,

encouragement and kindly support. His immense knowledge, enthusiasm and whole-

heartedness would give me the opportunity for my future career. I came to know about

so many new things. My thankfulness is also expressed to my co-advisor, Assoc. Prof.

Dr. Prasert Reubroycharoen, for his encouragement and sound guidance.

In addition, I would like to acknowledge Asst. Prof. Dr. Suwadee

Kongparakul Asst. Prof. Dr. Thongthai Wittoon attending as chairman and member of

my thesis committee, respectively, as well as for their helpful discussion, insightful

comments, and suggestions. Dr. Narong Chanlek from the Thailand Synchrotron Light

Research Institute for assistance in XPS analysis.

I would also like to present acknowledgment to Faculty of Science and

Technology, Thammasat University for grant support to study Master of Science

program in Chemistry (Thammasat University's Scholarship for AEC Scholarship). The

financial support provided by The Thailand Research Fund and National University

project, Thammasat University. The Central Scientific Instrument Center, Faculty of

Science and Technology, Thammasat University. I thank all my labmates and my

friends for their friendly, helpful and kindness to help directly and indirectly to

complete my thesis.

Finally, I would like to express my deepest gratitude to my parents for

encouraging, understanding, loving and supporting me spiritually throughout my life.

Much love!

Miss Tran Thi Tuong Vi

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TABLE OF CONTENTS

ABSTRACT (1)

ACKNOWLEDGEMENTS (3)

LIST OF TABLES (7)

LIST OF FIGURES (8)

CHAPTER 1 INTRODUCTION 1

1.1 Thesis motivation 1

1.2 Objectives of the research 3

1.3 Scope of the research 4

CHAPTER 2 REVIEW OF LITERATURE 5

2.1 Renewable resources 5

2.2.1 Biomass 6

2.2.1.1 Lignocellulose biomass 7

2.2.1.2 Xylose 9

2.2 Biodiesel 12

2.2.1 Transesterification and Esterification 14

2.2.2 Transesterification process mechanism 15

2.3 Furfural 17

2.4 Catalyst 19

2.4.1 Homogeneous catalyst 20

2.4.2 Heterogenous catalyst 20

2.5 Carbon solid acid catalyst (CM-SO3H) 21

2.6 Literature reviews 23

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CHAPTER 3 RESEARCH METHODOLOGY 31

3.1 Materials 31

3.1.1 Chemicals 31

3.1.2 Equipments 32

3.2 Methods 32

3.2.1 Preparation of carbon solid acid catalyst (CM-SO3H) 32

3.2.2 Characterization of catalyst 34

3.2.2.1 Study the morphology of catalyst 34

3.2.2.2 Study the textural analysis 34

3.2.2.3 Study the functional group 34

3.2.2.4 Study the properties of acid sites 34

3.2.3 Catalytic activity in biodiesel production from waste cooking oil 35

3.2.3.1 Biodiesel production 35

3.2.3.2 FAME analysis 35

3.2.3.3 Catalyst reusability 36

3.2.4 Catalytic activity in furfural production via xylose dehydration 36

3.2.4.1 Dehydration of xylose 36

3.2.4.2 Product analysis 37

CHAPTER 4 RESULTS AND DISCUSSION 38

4.1 Characterization of the carbon catalyst 38

4.1.1 N2 sorption analysis 38

4.1.2 The morphology of catalyst 40

4.1.3 The properties of acid sites 41

4.1.4 The functional group 43

4.2 Catalytic activity in biodiesel production from waste cooking oil 45

4.2.1 Effect of reaction temperature 46

4.2.2 Effect of reaction time 47

4.2.3 Effect of catalyst loading 48

4.2.4 Reusability 49

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4.3 Catalytic activity in furfural production via xylose dehydration 53

4.3.1 Effect of reaction temperature 53

4.3.2 Effect of reaction time 54

4.3.3 Effect of catalyst loading 55

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 58

5.1 Conclusions 58

5.2 Recommendations 59

REFERENCES 60

APPENDICES 67

APPENDIX A 68

Carbon microsphere characterization 68

APPENDIX B 72

Standard calibration curve preparation 72

APPENDIX C 75

By-products of xylose dehydration 75

BIOGRAPHY 80

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LIST OF TABLES

Tables Page

Table 2.1 The chemical composition and types of lignocellulosic biomass [2] 8

Table 2.2 Comparison of fuel properties of petroleum-diesel fuel and B100 biodiesel

fuel [30] 13

Table 2.3 Physical properties of furfural [37] 18

Table 2.4 Comparison of homogeneous and heterogeneous catalyst [38] 20

Table 2.5 Comparison of reaction conditions, product yields for thermochemical

conversion processes to carbon solid. [41] 21

Table 3.1 List of the chemicals used in this research 31

Table 3.2 List of the instrument used in this research 32

Table 3.3 The program of column temperature 36

Table 4.1 Textural properties and acidity of carbon microspheres, and catalysts. 40

Table 4.2 The chemical composition and physicochemical properties of waste

cooking oil 45

Table A1. Physical properties of carbon microspheres at 190C – 50wt.% (xylose

concentration) with different reaction time. 71

Table C1. Yield of by-products under xylose dehydration with CM-SO3H catalyst at

different reaction temperature for 2 h and 50 wt.% catalyst loading 75

Table C2. Yield of by-products under xylose dehydration with CM-SO3H catalyst at

different reaction time, 155C and 50 wt.% catalyst loading 76

Table C3. Yield of by-products under xylose dehydration with CM-SO3H catalyst at

155C for 2h and diffent catalyst loading 76

Table C4. Yield of by-products under xylose dehydration with P-C-SO3H catalyst at

155C for 2h and 25 wt.% catalyst loading 77

Table C5. Chemical structure of by-products 78

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LIST OF FIGURES

Figures Page

Figure 1.1 The main components and structure of lignocellulose [2] 2

Figure 2.1 Comparison between renewable energy and non-renewable energy 5

Figure 2.2 The conversion technology of biomass [19] 6

Figure 2.3 The structure and main components of lignocellulose biomass [20] 8

Figure 2.4 Mechanism of furfural production from xylose dehydration (a) via

enolization, (b) β-elimination, (c) via cyclic intermediates [24] 11

Figure 2.5 Mechanism of the formation of carbon microsphere prepared

hydrothermal from xylose [8] 12

Figure 2.6 Esterification reaction of free fatty acid with alcohol [31] 14

Figure 2.7 Transesterification reaction of triglycerides with alcohol [31] 14

Figure 2.8 Mechanism of base catalysed transesterification process [35] 16

Figure 2.9 Mechanism of acid catalysed transesterification process [35, 36] 17

Figure 2.10 Chemical structure of furfural 17

Figure 2.11 Chemicals derived from furfural [37] 19

Figure 2.12 Formation of CM-SO3H structure 23

Figure 2.13 The overall paths to produce furfural from xylose in the presence of a

single bronsted acid catalyst and of both lewis and bronsted acid catalysts [60] 28

Figure 3.1 Schematic diagram of synthesized CM-SO3H catalyst 33

Figure 4.1. Nitrogen sorption isotherms of (a) carbon microsphere (CM): overlay 40

units; (b) solid acid catalyst (CM-SO3H): overlay 80 units and (c) porous carbon

solid acid catalyst (P-C-SO3H) 39

Figure 4.2 Pore size distribution of (a) carbon microsphere; (b) carbon solid acid

catalyst (CM-SO3H) and (c) porous carbon solid acid catalyst (P-C-SO3H) 40

Figure 4.3 SEM microphotograph of (a) carbon microsphere; (b) carbon solid acid

catalyst (CM-SO3H). 41

Figure 4.4 NH3-TPD profile of (a) carbon solid acid catalyst (CM-SO3H) and (b)

porous carbon solid acid catalyts (P-C-SO3H) 42

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Figure 4.5 FTIR spectral of (a) carbon microsphere, (b) CM-SO3H and (c) P-C-SO3H

44

Figure 4.6 XPS spectra of CM-SO3H 45

Figure 4.7 FAME yield with different reaction temperatures at reaction time 6 h,

molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%. 47

Figure 4.8 FAME yield with different reaction times at reaction temperature 110C,

molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%. 48

Figure 4.9 FAME yields with different catalyst loading at reaction temperature

110 C for 2 h; molar ratio of oil/methanol is 1:9.35. 49

Figure 4.10 FAME yield with spent catalyst at reaction temperature 110 C for 2 h

and 10 wt. % catalyst loading 50

Figure 4.11 (a) N2 sorption isotherm and (b) pore size distribution of spent sulfonated

carbon catalyst after 3 cycles of reused 51

Figure 4.12 SEM microphotograph of spent sulfonated carbon catalyst of biodiesel

production. 52

Figure 4.13 NH3-TPD profile of spent sulfonated carbon catalyst after 3 cycles of

reused 53

Figure 4.14 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity with different reaction temperature at reaction time 2h and 50

wt.% catalyst loading 54

Figure 4.15 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity with different reaction times at reaction temperature 155C and

50 wt.% catalyst loading. 55

Figure 4.16 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity with different catalyst loading at reaction temperature 155C for

2h. 56

Figure 4.17 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity between CM-SO3H and P-C-SO3H catalysts at reaction

temperature 155C for 2 h and 25 wt.% catalyst loading. 57

Figure A1. Yield of carbon microsphere obtained from different conditions of

hydrothermal. 68

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Figure A2. SEM micrograph of carbon microsphere at 190C – 50wt.% (xylose

concentration) with different reaction time. 69

Figure A4. N2 sorption of carbon microsphere at 190C – 50wt.% (xylose

concentration) with different reaction time. 70

Figure A5. Van Krevelen diagram of carbon microsphere from different conditions

of hydrothermal. 71

Figure B1. Standard calibration curve for furfural production (HPLC) 72

Figure B2. Standard calibration curve for xylose conversion (HS-GC-MS) 73

1

CHAPTER 1

INTRODUCTION

1.1 Thesis motivation

Nowadays, research in chemistry will be tendency to explore and

development toward green chemistry that is mean environmental friendly, safe for

human health and supply for people the suitable products, less toxic and completely

recyclability. In the issue of future energy, fossil fuels are running out, we may face an

ecological destroy of exceptional scale due to the degradation of natural capital and loss

in ecosystem services such as air pollution, water pollution, etc. From these reasons

alternative and clean fuels has been interested to replace the fossil fuel. The scientists

have the most important responsibility find new energy resources. [1] There are

abundant and large quantities renewable resources every year such as agricultural crops

and residues, sewage, urban solid waste, animal residues, industrial residues, forestry

crops and residues, etc. It is a very complicated energy system with a multitude of

variations, also suitable for agricultural countries such as Viet Nam, Thailand, and

Malaysia, etc. They can replace those derived from petrochemical resources is very

significant to improve economic benefits and reduce environmental pollution. One of

the most important renewable energy sources is a lignocellulose biomass. [2, 3]

Lignocellulose biomass contained different structures of natural

macromolecule mainly of cellulose, hemicellulose and lignin were shown in Figure

1.1. It has been projected as an abundant carbon-neutral renewable source.

Lignocellulose feedstocks have important advantages over other feedstocks supplies in

this research because they are the non-edible portion of the plant therefore, they are a

non-food resource. [3] The heteropolymer as hemicellulose is composed of different 5-

and 6-carbon monosaccharide units: pentoses (xylose, arabinose), hexoses (mannose,

glucose, galactose) and acetylated sugars. [4] The major monomer of hemicellulose is

a xylose could be converted to a diversified of products such as microsphere structure

of carbon polymer or carbon microsphere, ethanol, furfural, furan, bio-ethanol, xylitol

and furfuryl alcohol, etc. Among these derivatives, carbon microsphere is the important

2

material and is interested from scientists. It has been applied in many applications such

as catalyst support, carbon fixation, CO2 sequestration, adsorbent, electrode, sensors,

and capacitor, etc. [5, 6] The process allows not only concentrating the energy content

from biomass into a solid biofuel but also generating liquid residue that could be used

as fertilizer on agricultural plantations. [1]

Figure 1.1 The main components and structure of lignocellulose [2]

In recent years, there have been numerous of articles reported application

as well as the method to synthesized the carbon-based catalysts via hydrothermal

carbonization (HTC). [7, 8] Hydrothermal carbonization is also known as thermal

treatment of organic substance under water media at high temperature and high

pressure. During the reaction, organic components of the biomass degraded and re-

polymerize into carbon solid. [9] HTC is one of a method has been interested over the

3

last several years because they do not only produce value-added products at high carbon

material yields with low cost but also facile preparation, high stability, non-toxicity and

green method.

The carbon solid acid catalyst, which is heterogeneous acid catalyst was

selected to catalyze for biodiesel production from waste cooking oil and xylose

dehydration to furfural with outstanding in stability, less toxicity, large specific surface

area, high dispersal ability, easily to synthesize, strong acidity and low cost. This

catalyst can be easily reused after reaction. Moreover, acid catalyst plays an important

role in biomass conversion processes for producing chemicals and fuels. [1] Compared

with homogeneous acid catalyst (H2SO4, HCl, CH3COOH), the homogeneous catalyst

has several disadvantages such as toxic, corrosive to equipment, produce more waste

water, difficult to separate and reuse, etc. [10]

Therefore, carbon solid acid catalyst containing sulfonic acid (SO3H) group

would be prepared by hydrothermal carbonization and sufonation from xylose. Carbon

solid acid catalysts (CM-SO3H) would act as a catalyst for simultaneously esterification

and transesterification to produce biodiesel from waste cooking oil and synthesis the

furfural through dehydration reaction of xylose. The optimization condition of biodiesel

and furfural production were also studied with vary parameters including reaction

temperature (C), reaction time (h), catalyst loading (wt.%). In this concept, we would

like to propose the principles of green carbon science and application of green

chemistry to acid heterogeneous catalyst.

1.2 Objectives of the research

1. To study formation of carbon microsphere by hydrothermal

carbonization of xylose.

2. To study sulfonation of carbon for acid catalyst.

3. To apply the sulfonated carbon catalyst for biodiesel production from

waste cooking oil and furfural production from xylose.

4

1.3 Scope of the research

1. Study the synthesis carbon microsphere by hydrothermal carbonization

of xylose.

2. Study the sulfonation condition to form sulfonated carbon catalyst (CM-

SO3H)

3. Study experimental condition of biodiesel production from waste

cooking oil with methanol by CM-SO3H catalyst using autoclave system such as

catalyst loading, methanol to oil ratio, reaction temperature and reaction time.

4. Study experimental condition of xylose dehydration by CM-SO3H

catalyst such as catalyst loading wt.%, reaction temperature and reaction time.

5

CHAPTER 2

REVIEW OF LITERATURE

2.1 Renewable resources

Renewable resources are one that will not run out of it; could be protected

the environment from toxic pollutions, which in turn keep people healthier. The energy

of life cycles of renewable and non renewable energy were shown in Figure 2.1.

Renewable energy does not produce greenhouse gases, carbon emissions, radioactive

waste, or acid rain. Renewable resources are also cheaper, stabilize and more

economically than other sources of non-renewable resources. [11-13] Renewable

energy could be categorized based on origin such as solar energy, wind energy,

hydropower energy, geothermal energy and biomass energy. It has been developed and

commercially well investigated in the latest year. [11, 14-16] Therefore, there are

several studies have focused on renewables energy. One of the most interested in is

biomass energy source.

Figure 2.1 Comparison between renewable energy and non-renewable energy

6

2.2.1 Biomass

Biomass is derived by a natural organic material based on carbon,

hydrogen, and oxygen. Biomass sources are available in countrified and urban areas of

all countries. The compositions and structure of biomass are very diversified and are

affected by origin, age, climatic conditions, and location. [17] Biomass is an alternative

resource, play an important role in producing of carbon-neutral fuels as well as

providing feedstocks for the production of biofuels and another chemicals. The

advantages of biomass have the potential solved many environmental issues, especially

global warming and greenhouse gases emissions. It recovers CO2 from air emissions in

the fuel combustion engine, then the process of photosynthesis to give clean energy and

reduce the CO2 level in the atmosphere is called close carbon dioxide cycles. For this

reason, it is recognized that biomass is an important and abundant energy source could

be replaced to solve the problem of depleted of fossil fuels. [18]

The conversion of biomass can be accomplished by different methods

which are divided into: thermal, thermochemical, chemical, and biochemical methods

were summarised in Figure 2.2.

Figure 2.2 The conversion technology of biomass [19]

7

2.2.1.1 Lignocellulose biomass

Lignocellulose biomass is a generic terminology for describing the plants

biomass. It is the most abundant biomass resource contained mainly of the

polysaccharides cellulose, hemicellulose and lignin (Figure 2.3).

The major component of lignocellulose biomass is cellulose that is a homo-

polysaccharides with same monomer (Glucose). Its crystalline structure consist of

intramolecular and intermolecular hydrogen bonding, which possessing high chemical

stability with binds the glucose units. Hemicellulose is the second abundant renewable

biomass after cellulose, which is a random and amorphous structure. It is a hetro-

polysaccharides with different sugar monomers composed of different 5- and 6-carbon

monosaccharide units (xylose, glucose, mannose, galactose, uronic acid). The third

component, lignin is an amorphous heteropolymer with three-dimensional aromatic

polymer of phenyl propane units. [2], [20], [21]

Cellulose, hemicellulose and lignin are not uniformly distributed in the

plant cell. Normally, lignocellulosic biomass consists of 35–50% cellulose, 20–35%

hemicellulose, and 10–25% lignin. There are also other fractions such as proteins, oils,

and ash. [2]

8

Figure 2.3 The structure and main components of lignocellulose biomass [20]

The lignocellulose biomass can be classified in four particular types as

follow: Hardwood, Softwood, Agricultural waste, Grasses was shown as Table 2.1.

Table 2.1 The chemical composition and types of lignocellulosic biomass [2]

Lignocellulose biomass Cellulose (%) Hemicellulose

(%)

Lignin

(%)

Hard wood Poplar 50.8–53.3 26.2–28.7 15.5–16.3

Oak 40.4 35.9 24.1

Eucalyptus 54.1 18.4 21.5

Softwood Pine 42.0–50.0 24.0–27.0 20.0

Douglas fir 44.0 11.0 27.0

Spruce 45.5 22.9 27.9

9

Agricultural

waste Wheat Straw 35.0–39.0 23.0–30.0 12.0–16.0

Barley Hull 34.0 36.0 13.8-19.0

Barley Straw 36.0-43.0 24.0-33.0 6.3-9.8

Rice Straw 29.2–34.7 23.0–25.9 17.0–19.0

Rice Husks 28.7–35.6 12.0–29.3 15.4–20.0

Oat Straw 31.0–35.0 20.0–26.0 10.0–15.0

Ray Straw 36.2–47.0 19.0–24.5 9.9–24.0

Corn Cobs 33.7–41.2 31.9–36.0 6.1–15.9

Corn Stalks 35.0–39.6 16.8–35.0 7.0–18.4

Sugarcane

Bagasse 25.0–45.0 28.0–32.0 15.0–25.0

Sorghum

Straw 32.0–35.0 24.0–27.0 15.0–21.0

Grasses Grasses 25.0–40.0 25.0–50.0 10.0–30.0

Switchgrass 35.0–40.0 25.0–30.0 15.0–20.0

Lignocellulose biomass is an important component of the major food crops,

it is the non-edible portion of the plant, which is plentiful feedstock to fuels, polymers

and chemicals. It has an advantage over other biomass because it can be produced

quickly, lower cost than food crops and used as a raw material for the production of

alternative fuels without impacting in the world's food supply chain. Therefore,

lignocellulose is one of the most interested biomass resources in nature. [2], [20]

2.2.1.2 Xylose

Xylose, one of carbohydrate is sugar that categorized as a monosaccharide

of the aldopentose type, contained five carbon atoms and included a formyl functional

group. It is a first separated from wood and derived from hemicellulose, one of the main

components of biomass. Like most sugars, it can adopt several structures depending on

conditions. With its free carbonyl group, it is a reducing sugar. [22] D-Xylose is widely

10

applied industries include pharmaceutical (as intermediate: in medicine

manufacturing); food production (as sweetener in beverage and food); cosmetics (as

humectant: in cleanser, beauty creams and lotions to maintain the moisture); human

consumption; agriculture/animal feed, etc. [23] Moreover, xylose is a forerunner to

synthetic polymers, a solvent in industry and various chemicals such as carbon

microsphere, ethanol, furfural, furan, bio-ethanol, xylitol and furfuryl alcohol, etc.

There are many conversion methods of xylose into a variety of products such as xylose

fermentation to ethanol, xylose dehydration to furfural, electrochemical reduction of

xylose to xylitol, hydrothermal carbonization.

Xylose and other five carbon sugars undergo dehydration, losing three

water molecules to become furfural under simultaneous of heat and acid catalyst. More

than one reaction mechanism of furfural production from xylose dehydration has been

proposed in different studies based on different techniques, and reaction conditions

could be classified in three kinds as shown in Figure 2.4 [22, 24]

- Start from the acyclic form of the pentoses, either via a 1,2-enediol

intermediate 2 and next dehydration. (Figure 2.4 a)

- Or directly via a 2,3-(α,β-) unsaturated aldehyde 4 (Figure 2.4 b)

- Start from the pyranose form of the pentoses, the acid catalyst covert

xylose to the 2,5-anhydroxylose furanose intermediate and then

dehydrated to furfural (Figure 2.4 c)

11

Figure 2.4 Mechanism of furfural production from xylose dehydration (a) via

enolization, (b) β-elimination, (c) via cyclic intermediates [24]

Mechanism of xylose under hydrothermal carbonization process to carbon

microsphere was studied as shown in Figure 2.5. According to a current study on

hydrothermal carbonization of polysaccharides by Sevilla and Fuertes [25], the carbon

microsphere was formed follow four steps:

(1) Dehydration and fragmentation of sugars;

12

(2) Undergoes polymerization or condensation reactions of the dehydrated

and fragmented products;

(3) Aromatization of the polymers (by intermolecular dehydration);

(4) Nucleation growth by diffusion and linkage of species from the solution

to the nuclei surface. Besides that, xylose was decomposed to a various organic product

such as lactic acid, formic acid, acetic acid, fructose, HMF, furfural, etc. [26]

Figure 2.5 Mechanism of the formation of carbon microsphere prepared

hydrothermal from xylose [8]

2.2 Biodiesel

Biodiesel (fatty acid methyl or ethyl esters) is a kind of renewable fuel to

replace petroleum diesel. It is biodegradable, non-toxic, less harmful emissions,

13

environmentally friendly, safe to handle and high cetane number (a measurement of the

combustion quality of diesel fuel during compression ignition). Biodiesel production

could be derived from either edible plant oils including animal fats (biodiesel first

generation); non-edible plant oils (biodiesel second generation) such as leaves and

stems of plants, biomass derived from waste, and oils seeds; microalgae (biodiesel third

generation) or used edible oils (normally called Waste Cooking Oil; WCO). The

production of biodiesel from WCO is one of the solution for solving the simultaneous

problems of environment pollution and energy scarcity. Moreover, to reduce the cost

of biodiesel production, WCO would be a good choice as a raw material because of it

is cheaper than edible plant oils and other feedstocks. [27], [28], [29] Besides, the

properties of biodiesel is similar to petroleum diesel (Table 2.2)

Table 2.2 Comparison of fuel properties of petroleum-diesel fuel and B100 biodiesel

fuel [30]

Property Diesel Biodiesel Unit

Fuel Standard ASTM D975 ASTM D6751 -

Lower Heating Value 12905 11817 Btu/gal

Kinematic Viscosity@40C 1.3 – 4.1 1.9 – 6.0 mm2/s

Specific Gravity@60C 0.85 0.88 kg/l

Density 7.079 7.328 lb./gal

Water and Sediment 0.05 max 0.05 max % Vol.

Carbon 87 77 wt.%

Hydrogen 13 12 wt.%

Oxygen 0 11 -

Sulfur 0.0015 0.0 – 0.0024 wt. %

Boiling Point 180 – 340 315 – 350 C

Flash Point 60 – 80 130 – 170 C

Cloud Point (-15) – 5 (-3) – 12 C

14

Pour Point (-35) – (-15) (-15) – 10 C

Cetane Number 40 – 55 47 – 65 -

Lubricity SLBOCLE 2000 – 5000 > 7000 grams

Lubricity HFRR 300 – 600 < 300 microns

2.2.1 Esterification and Transesterification

Esterification is the process use to convert these free fatty acid and alcohols

to form alkyl ester and water (Figure 2.6). The esterification reaction is both slow and

reversible.

Figure 2.6 Esterification reaction of free fatty acid with alcohol [31]

Transesterification or also called alcoholysis is the process use to convert

these triglycerides to form biodiesel and glycerol (Figure 2.7). The suitable alcohols

use for this process are methanol, ethanol, propanol, butanol, and amyl alcohol.

Methanol and ethanol are utilized most usually, especially methanol because of its low

cost and its physical and chemical advantages.

Figure 2.7 Transesterification reaction of triglycerides with alcohol [31]

15

2.2.2 Transesterification process mechanism

Transesterification process could be divided into two groups:

Supercritical transesterification or non-catalytic transesterification process

is the reaction produce biodiesel without catalytic under high temperature, high

pressure and requires high alcohol to oil molar ratio. Therefore, high cost, low reaction

conversion because the degradation of the fatty acid esters formed, the glycerol formed

react with other components at high temperature. [32], [33]

Catalytic transesterification process is the reaction produce biodiesel using

a catalyst (alkaline, acid or enzymatic catalyst). [34], [35], [36]

- Alkaline catalyst (NaOH, KOH, CH3ONa) has been interested in by many

researchers because it's cheap and available. However, this catalyst suitable for oils

containing not over than 3% of free fatty acid and water content. High water content

can produce saponification causes reductions of ester yield, an increment in viscosity,

difficult separation of glycerol from methyl ester and the formation of emulsion. The

mechanism of alkaline catalyst using to transfer biodiesel production was shown as

Figure 2.8. Normally, the mechanism of alkaline catalysed transesterification process

could be divided in four steps: [35]

(1) The react of the base with the alcohol, producing an alkoxide and the

protonated catalyst.

(2) Then, form a tetrahedral intermediate by nucleophilic attack of the

alkoxide at the carbonyl group of the triglyceride

(3) After that, a form of the corresponding anion of diglyceride and the

alkyl ester.

(4) Finally, the deprotonates the catalyst to form hydroxyl and reacts with

another alcohol for new cycle. Diglycerides and monoglycerides will be converted by

the same mechanism.

16

Figure 2.8 Mechanism of base catalysed transesterification process [35]

- Acid catalyst (H2SO4, HNO3, H3PO4, HCl) has been used in the

transesterification process. This catalyst suitable for oils containing high free fatty acid.

However, acid can produce a large number of salt interaction that causes of corrosion

and toxic. The mechanism of acid catalyst using to transfer biodiesel production was

shown as Figure 2.9. Firstly, the acid has protonated the oxygen on the carbonyl group

of the ester to form the carbocation (2). Then, to produces the tetrahedral intermediate

by the nucleophilic attack of the alcohol (3). After that, eliminates glycerol to form the

new ester (4) and to regenerate the catalyst H+. Diglycerides and monoglycerides will

be converted by the same mechanism. [36]

17

Figure 2.9 Mechanism of acid catalysed transesterification process [35, 36]

- Enzymatic catalyst (immobilized lipase) such as Rhizomucor miehei,

Pseudomonas cepacia, Candida rugosa, Rhizopus oryzae. This catalyst use at lower

operating temperature, no byproduct, reusability without any separation and wash.

However, it is very expensive, enzyme activity losses may occur due to waste water

and alcohol effects.

2.3 Furfural

Furfural, 2-furancarbonal, 2-furaldehyde or furfuraldehyde (C5H4O2) is a

cyclic aldehyde as shown in Figure 2.10 derived from variety agricultural byproducts

(corncobs, bagasse, oat hulls, almond hucks, cottonseed hulls, rice hulls, etc). The

furfural is an alternative non-petroleum based chemical feedstock. It is viscous,

colorless liquid that has an aromatic odor reminiscent of almonds which quickly

darkens or black color when exposed to air. [37] The physical properties of furfural was

shown in Table 2.3.

Figure 2.10 Chemical structure of furfural

18

Table 2.3 Physical properties of furfural [37]

Property

Molar mass (g/mol.) 96.08

Boiling point at 101.3 kPa (C) 161.7

Flash point, tag closed cup (C) 61.7

at 20C (g/cm3) 1.1598

Vapor density (Air = 1) 3.3

Critical pressure Pc (MPa) 5.502

Viscosity, 25C (mPa.s) 1.49

Critical temperature Tc (C) 397

Solubility, in water, wt.% (25C) 8.3

Ethyl alcohol, diethyl ether

Spectroscopic polarity (ETN) 0.426

Dielectric constant at 20C 41.9

Heat of vaporization (liquid) (kJ/mol) 42.8

Heat capacity (liquid, 20 – 100C) (Jg-1K-1) 11.74

Heat of combustion (liquid) (kJ/mol) 2344

Hf (l), (kJ/mol) -201.65

Hf (g), (kJ/mol) -151.05

Explosion limits (in air), (vol.%) 2.1 - 19.3

Surface tension at 29.9C (mN/m) 40.7

Furfural undergoes reactions typical for aldehydes like alkylation

(arylation), acetalization and acylation, aldol and condensations. Furfural is diverse

derivatives and widespread applications in the industry are given in Figure 2.11. It can

be used to make other furan chemicals, such as furoic acid. Furfural is also an important

19

chemical solvent. Of the world production of furfural 60 – 70% is converted to furfuryl

alcohol. The remaining part was used as:

Extractant for aromatics from lubricating oils

Purification solvent for C4 and C5 hydrocarbons

Reactive solvent and wetting agent

Chemical feedstock for other furan derivatives

Nematode control agent

Therefore, furfural has been suggested as a platform chemical for biofuels

and biochemicals production. [37]

Figure 2.11 Chemicals derived from furfural [37]

2.4 Catalyst

Catalysis is the process that increases the rate of a chemical reaction. The

reactions happen faster and lower activation energy. Normally, catalysts have been

divided as a homogeneous and heterogeneous catalyst. Depending on the purpose we

can select the suitable catalyst.

20

2.4.1 Homogeneous catalyst

The homogeneous catalyst is operated in the same phase where the reaction

occurs. In principle, there is no limitation on the phase to be considered, the reaction

occurs as a gaseous or liquid phase.

The great variety of homogeneous catalyst is known, ranging from

Bronsted and Lewis acids widely used in organic synthesis, metal complexes, metals

ions, organometallic complexes, organic molecules up to biocatalysts (Enzymes,

artificial enzymes, etc.) However, it is difficult to separate after reaction and corrosive

equipment. [38]

2.4.2 Heterogenous catalyst

The heterogeneous catalyst is operated in the different phases where the

reaction occurs. The catalyst usually in a solid form and the reaction occurs either in

the liquid or gaseous phase. A heterogeneous catalytic reaction affects the adsorption

of reactants from a liquid phase onto a solid surface, the surface reaction of adsorbed

and desorption of products into the liquid phase. The advanced of this catalyst is simple

to separate and recycle from the reactants and products. That is one of the main points

to show the low cost and environmental friendly. Moreover, the heterogenous catalyst

gives noncorrosive in reactor and less toxic. The solid catalysts requires a high active

surface area and small size distribution effect to the conversion and selectivity of

products. The main comparison of homogeneous and heterogenous catalyst can be

summarized in Table 2.4

Table 2.4 Comparison of homogeneous and heterogeneous catalyst [38]

Property Homogeneous Heterogeneous

Catalyst recovery Difficult and expensive Easy and cheap

Thermal stability Poor Good

Selectivity Good

Single active site

Poor

Multiple active sites

21

2.5 Carbon solid acid catalyst (CM-SO3H)

A several of solid acid catalysts are developed, including immobilized

liquid acid (e.g. HF/AlCl3), zeolite molecular sieve (e.g. H-ZSM-5), metal oxide (e.g.

A12O3), metal sulfide (e.g. CdS), heteropoly acid (e.g. H3PW12O40), natural clay (e.g.

bentonite), cation exchange resin (e.g. Nafion-H), and solid superacid (SO42-/ZrO2) etc.

However, the limitation due to restricted reaction rates and harmful side reactions,

deactivates due to sulfate, formation of carbonaceous deposits on Brønsted acid sites,

low acid site concentrations and high cost. [39] Therefore, many researchers would like

to improve the high acid capacity of the catalyst and cheap.

Currently, carbon material has been interested and developed rapidly. The

carbon material is stable and insoluble in most acidic or basic conditions as well as

organic solvents. It has been obtained by carbonization of biomass or biomass derived

products. The carbonization methods include pyrolysis, gasification, flash

carbonization, and hydrothermal carbonization, etc. Hydrothermal carbonization is a

thermochemical process obtained the physical and chemical dewatering or dehydration

under high pressure and low temperature (180 – 250C) of biomass. The chemical

dehydration affects the elimination of water molecules from hydroxyl groups. The

physical dewatering step is facilitated by the lower viscosity of water and fewer

hydrophilic functional groups at HTC pressures and temperatures. [40] The advantage

of HTC method is could convert the wet material into carbon solid with high yields

(yield product is mass ratio of product formed to initial feedstock based on dry weight)

and relatively low energy during the process were compared in Table 2.5. Hence, the

raw material used to convert carbon solid more abundant. So the hydrothermal process

has become an important technique and more popular.[40] In this research, we also

focus on preparation of the carbon solid acid catalyst combine between hydrothermal

carbonization and sulfonation methods.

Table 2.5 Comparison of reaction conditions, product yields for thermochemical

conversion processes to carbon solid. [41]

22

Process Reaction

temperature (C)

Product distribution (weight %)

Char Liquid Gas

Pyrolysis: Slow ~ 400C 35 30 35

Pyrolysis:

Intermediate ~ 500C 20 50 30

Pyrolysis: Fast ~ 500C 12 75 13

Gasification ~ 800C 10 5 85

HTC 180 – 250C 50 - 80 5 – 20% 2 - 5

CM-SO3H is the carbonaceous solid sulfonic acid functionalized was

shown in Figure 2.12, one of the interest catalyst support because it can easily to

synthesized and controled acid capacity, mean size distribution, also pore structure. The

structure of carbon solid acid catalyst from biomass derived is often amorphous and

owns aromatic structure, contain of -SO3H, -OH and -COOH groups. Inside that -SO3H

groups are considered as the key active acidic site, the existence of -OH and -COOH

groups would provide hydrophilic reactants accessing to the -SO3H groups so it would

be in favor of effective catalytic performance. [39] CM-SO3H is a strong acid catalyst,

stability, and low cost.

23

Figure 2.12 Formation of CM-SO3H structure

2.6 Literature reviews

Recently, the renewable resource has been interested in solve the scarcity

of feedstock from fossil and environmental issues. Biodiesel from waste cooking oil

and furfural production from xylose have received more and more attention for their

potential substitute. However, the problem from synthesis the biodiesel and furfural

production such as high use cost, low product yields due to the catalyst (low acidity,

toxic, corrosive, the amount of catalyst, etc), also a high temperature, long time.

Therefore, many researcher were developed with this problem.

Biodiesel production

Vyas et al., [42] studied synthesis of biodiesel from Jatropha oil and

methanol using homogeneous alkali catalyst (KOH) at reaction temperature 50 – 70C

for 1.5 h and stirred at 700 – 750 rpm. Product mix was allowed in a separating funnel

24

for 8 h after completion of reaction. The molar ratio 1:3 of the Jatropha oil to methanol.

The results show that the yield of the biodiesel was 86.0 %.

Vicente et al., [43] studied synthesis of biodiesel from Sunflower oil and

methanol using different basic catalysts (sodium methoxide, potassium methoxide,

sodium hydroxide and potassium hydroxide). All the experiments were carried out

under the same reaction conditions at 65C for 4 h, the molar ratio 1:6 of Sunflower oil

to methanol, catalyst loading 1.0 wt.% and stirred at 600 rpm. The results show that the

high yield of the biodiesel using NaOH, KOH, CH3KO, CH3NaO were 86.33%,

91.67%, 98.33%, 99.17%, respectively.

Wang et al., [44] studied synthesis of biodiesel from waste cooking oil and

methanol via two-step catalyzed process, which has large amounts of acid value (75.92

0.036 mg KOH/g). In the first step was esterified the free fatty acids of WCO with

methanol in the presence ferric sulfate (Fe2(SO4)3) at 95C for 4 h, the molar ratio 1:10

of WCO to methanol, catalyst loading 2.0 wt.%. The second step, the triglycerides

(TGs) in WCO were transesterified with methanol using KOH catalyst at 65C for 1 h,

the molar ratio 1:6 of WCO to methanol. The results show that the conversion of Free

Fatty Acid (FFA) and the yield of biodiesel were 97.22% and 97.02%, respectively.

Su, Chia-Hung [45] studied synthesis of biodiesel from Soybean oil and

methanol using several homogeneous acid catalysts (HNO3, H2SO4, HCl). There is only

HCl could be recovered and reused catalyst because it can be completely retained in the

separated methanol phase. The reaction condition of biodiesel production with HCl

catalyst: reaction temperature 76.67C for 103.57 min. The molar ratio 1:7.92 of FFA

to methanol, catalyst concentration 0.54M. The results show that the conversion of FFA

was 98.16%. The catalyst could be reused at least five times and the conversion was

97.0%.

The application of homogeneous catalysts was successfully for biodiesel

production due to low reaction temperature, low cost and high yield. However, many

disadvantaged such as toxicity, corrosive, could not recycle and produce the

25

saponification. Hence, a heterogenous catalyst has been interesting with many

researchers for biodiesel production.

Sirisomboonchai et al., [46] studied synthesis of biodiesel from waste

cooking oil and methanol using calcined scallop shell as a catalyst. The catalyst loading

5.0 wt.%, the molar ratio of WCO to methanol was (1: 3, 1:6, 1:12) and stirred at 500

rpm. The results show that the FAME yield over 86.0% at 65C for 2 h was obtained

in the presence of small amount of water. The CSS catalyst was reused for 4 times as

FAME yield decreased 20% due to the formation of Ca-glyceroxide on its surface.

Maneerung et al., [47] studied synthesis of biodiesel from waste cooking

oil and methanol using CaO catalyst prepared from chicken manure. The optimum

reaction conditions were reaction temperature at 65°C for 3 h, the molar ratio 1:15 of

oil to methanol, the catalyst loading 7.5 wt.% and stirred at 1400 rpm. The results show

that the obtained CaO catalyst presented high catalytic performance biodiesel

production up to 90.0% FAME yield was achieved.

Vieira et al., [48] studied synthesis of biodiesel from Oleic acid and

methanol using heterogeneous catalyst (Lanthanum (La3+) and HZSM-5 based

catalysts) at 100C for 1 – 7 h, the catalyst loading 10.0 wt.%. The mass ratio of oleic

acid to methanol were 1:5 and 1:20 for (lanthanum oxide – LO, Sulfated lanthanum –

SLO, SLO/HZSM-5) and HZSM-5, respectively. The results show that the conversion

oleic acid were 67.0% an 96.0% for LO and SLO, respectively. And for HZSM-5 and

SLO/HZSM-5 were 80.0% and 100%, respectively. All of there catalysts deactivated

after the first use, but the deactivation of SLO/HZSM-5 was smaller.

Karnjanakom et al., [49] studied synthesis of biodiesel from Hevea

brasiliensis oil (para rubber seed oil) and methanol using SO3H-MCM-41 catalyst. The

optimum reaction conditions were reaction temperature at 153°C for 2 h, the catalyst

loading 5.06 wt.%, 0.266 of MPMDS molar composition and stirred at 500 rpm. The

results show that the yield of biodiesel production was 95.5%. This catalyst could be

reused up to 4 times without significant loss yield of product.

26

Talebian-Kiakalaieh et al., [50] studied synthesis of biodiesel from waste

cooking oil and methanol using heterogeneous heteropoly acid (HPA) catalyst. The

optimum reaction conditions were reaction temperature at 65C for 14 h, the molar ratio

1:70 of oil to methanol and the catalyst loading 10 wt.%. The results show that highest

conversion was 88.6%. The response surface methodology (R2 = 0.9987) and the

reaction followed first-order kinetics with the calculated activation energy, Ea = 53.99

kJ/mol.

Shu et al., [51] studied synthesis of biodiesel from cottonseed oil and

methanol using a carbon-based solid acid catalyst at reaction temperature 260C for 3

h. The resulting showed the conversion of cottonseed oil 89.93% was obtained when

the methanol/cottonseed oil molar ratio was 18.2 and catalyst loading 0.20 wt% of oil.

The asphalt-based catalyst shows higher activity for the production of biodiesel, which

was resulted by high acid site density, its loose irregular network and providing large

pores.

Shu et al., [52] studied synthesis of biodiesel from waste vegetable oil with

large amount of free fatty acid using a carbon-based solid acid catalyst at temperature

range 180 – 220C range for 4.5 h. The results show conversion of triglyceride and FFA

reached 80.5 wt.% and 94.8 wt.%, respectively using a 16.8 molar ratio of methanol to

oil and 0.2 wt% of catalyst loading.

Li et al., [53] studied synthesis of biodiesel from waste cooking oil and

methanol using a heterogeneous catalyst from pyrolyzed rice husk. A solid acid catalyst

was prepared by sulfonating pyrolyzed rice husk with concentrated sulfuric acid. The

result show that the conversion of free fatty acid (FFA) reached 98.17% after 3 h at

110C, and the fatty acid methyl ester (FAME) yield reached 87.57% at 110C after

15h.

Dawodu et al., [54] studied effective conversion of non-edible oil with

sulfonated carbon catalyst. At the optimized conditions, high conversion (99%) was

achieved. Increasing the temperature also increased FAME yield and FAME yield

27

finally reached 99.0% over the two catalytic systems at temperature of 180C for 1 – 5

h at ratio of FFA to methanol 1:30 and the range of 1.5–7.5 wt.% of catalyst to oil.

Fu et al., [55] synthesized the carbon solid acid catalyst from β-cyclodextrin

for biodiesel production. This catalyts was prepared by incomplete hydrothermal

carbonization of β-cyclodextrin and sulfonation with sulfuric acid (98.0%). The highest

FAME yield of high FFA (55.2%) containing oils reached 79.98 % after 12 h, catalyst

loading 5.0 wt.% and the molar ratio 1:10 of oleic acid to methanol. The catalyst can

be regenerated within 6 cycles after washed with methanol or sulfuric acid.

Ngaosuwan et al., [56] studied synthesis of biodiesel from caprylic acid

(HCp) and methanol using sulfonated carbon-based catalyst derived from coffee

residue. The catalyst was synthesized under a carbonization temperature of 600C for

4 h and sulfonation temperature of 200C for 18 h. The reaction conditions were 60C

for 4 h, the molar ratio 1:3 of caprylic acid to methanol, the catalyst loading 5 wt.% and

stirred at 600 rpm. The highest conversion of caprylic acid was 71.5%. This catalyst are

not comparable on a mass to the homogeneous H2SO4 catalyst. However, it is in the

ease of handling, recyclability, and being environmentally friendly.

Furfural production

Long Li et al., [57] investigated as a water-tolerant tantalum based catalyst

for the dehydration of D-xylose to furfural by using a biphasic system containing water

and 1-butanol. The highest furfural yield was 59.0%, the conversion of D-xylose was

96.0% at 180C for 3 h in the continuous process.

Rong et al., [58] studied the dehydration of xylose to furfural at atmospheric

pressure using sulfuric acid and inorganic salts (NaCl or FeCl3) and a biphasic

containing toluene and water. The results show that the highest yield of furfural was

83.0% under reaction conditions: 10 wt.% H2SO4, 10wt.% of the xylose to the mixture

(150 mL of toluene and 10 mL of water), 2.4 g NaCl and heating for 5 h. FeCl3 was

shown to be more efficient than NaCl.

28

Zhang et al., [59] studied the dehydration of xylan, D-xylose and

lignocellulosic biomass into furfural using AlCl3 as catalyst in ionic liquid (1-butyl-3-

methylimidazolium chloride). The highest yield of furfural was 84.8% at 170C for 10

s. The conversion of D-xylose and untreated lignocellulosic biomass was also

investigated. The furfural yield of corncob, grass and pine wood were in the range of

16.0–33.0%.

Choudhary et al., [60] investigated the conversion of xylose to furfural

using Lewis (CrCl3) and Brønsted acid (HCl) catalysts in water were shown as Figure

2.13. The highest furfural yield and conversion of xylose were 76.3% and 95.8%,

respectively under following the reaction conditions: initial xylose 1.0 wt. % in

biphasic systems (2.0 mL of aqueous solution), toluene (2.0 mL) as the extracting

solvent, at reaction temperature 140C for 2 h and mixture of CrCl3 (6.0 mM), HCl

(0.1 M). Using the combination of Lewis and Brønsted acids, a furfural yield (39.0%)

higher than using HCl alone (29.0%) at reaction temperature (∼145C) in a single

aqueous phase.

Figure 2.13 The overall paths to produce furfural from xylose in the presence of a

single bronsted acid catalyst and of both lewis and bronsted acid catalysts [60]

Sádaba et al., [61] prepared the vanadium phosphates (VPO) as catalysts

for xylose dehydration. The orthorhombic vanadyl pyrophosphate catalyst (VO)2P2O7

was prepared by calcination of VOHPO4.5H2O at 550C for 2 h. The results show that

the yield of furfural was 56% at 170C for 6h, catalyst loading 1.5 wt.% (the

29

concentration of (VO)2P2O7 as low as 5.0 mM) and 1.0 mL water–toluene solvent

mixture (3:7 volume ratio).

Hua et al., [62] prepared the reaction kinetics of xylose dehydration to

furfural using Organosulfonic acid-functionalized mesoporous silica (SO3H-SBA-15).

The results show that the best of furfural yield was 75.0% at 200C for 3 h in the mixture

(ethyl butyrate (17.5 mL) and water (7.5 mL)). The reaction kinetics of xylose

dehydration to furfural was investigated and the activation energy was 68.5 kJ/mol, the

reaction order was 0.50.

Zhang et al., [63] studied conversion of D-xylose to furfural with

mesoporous molecular sieve MCM-41 as catalyst and 1-butanol as the extraction

solvent. At the optimized conditions, the volume ratio 1.5 of 1-butanol to water,

reaction temperature at 170C for 3 h, furfural yield and xylose conversion were

obtained more than 96.85% and 44.05%, respectively.

Doiseau et al., [64] studied effect between solid acid catalysts and

concentrated carboxylic acids solutions for efficient furfural production from xylose.

The presence of solid acid catalysts in aqueous acetic acid solution had influence in the

transformation of xylose to furfural. Furfural yield and furfural selectivity of this system

were higher than the catalytic performances obtained in pure water at 150C.

Kaiprommarat et al., [65] investigated the sulfonic acid-functionalized

MCM-41 (SO3H-MCM-41) and methyl propyl sulfonic acid-functionalized MCM-41

(MPrSO3H-MCM-41) catalysts for xylose dehydration to furfural. The MPrSO3H-

MCM-41 catalyst was improved the furfural product to obtain a high turn-over

frequency. The furfural yield, furfural selectivity and xylose conversion were 93.0%,

98.0% and 95.0%, respectively at the optimum conditions 155C for 2 h, biphasic

mixture contains water and toluene. This research suggested that the pore diameter of

catalyst (3 – 6 nm) could provide a furfural selectivity higher than 93.0%.

Zhang et al., [66] synthesized carbon solid acid catalyst by sulfonation of

carbonaceous material which was prepared from sucrose using 4-BDS as a sulfonating

agent. The mixture of xylose or corn stalk (0.4 g), carbon catalyst (0.2 g), -

30

valerolactone (16.5 ml) were put into the reactor. The highest furfural yields derived

from xylose was 78.5% at 170C for 30 min and corn stalk in this study was 60.6% at

200C for 200 min. This catalyst could be reused for 5 times without the loss of furfural

yields.

Khatri et al., [67] studied a sulfonated polymer impregnated carbon

composite as a solid acid catalyst for dehydration of xylose to furfural. In this research,

the cabon solid acid catalyst (C-SO3H) and polymer impregnated carbon solid acid

catalyst (P-C-SO3H) were prepared by combination of pyrolyzed and sulfonated

method. The optimun reaction condition: 150C for 3 h, 0.50 g xylose, and 0.10 g

catalyst and 25.0 mL DMSO was used as a extraction solvent. The P–C–SO3H catalyst

showed higher conversion (98.0%) and selective (100%) than C–SO3H (xylose

conversion: 45.0%, furfural selectivity: 98.0%). P-C-SO3H was easily recovered and

reused without significant loss in its activity.

For these reason, CM-SO3H catalyst would be prepared by hydrothermal

carbonization from xylose and sulfonation method and applied for biodiesel, furfural

production.

31

CHAPTER 3

RESEARCH METHODOLOGY

3.1 Materials

All chemicals and equipments used in this research were shown in Table

3.1 and Table 3.2, respectively.

3.1.1 Chemicals

Table 3.1 List of the chemicals used in this research

Chemicals Manufacturer Country

Acetone, Comercial grade RCI Labscan USA

Acetonitrile, HPLC grade RCI Labscan USA

Commercial grade xylose N/A Thailand

D-Xylose Sigma-Aldrich USA

Heptane, AR grade QReC New Zealand

Methanol, AR grade QReC New Zealand

Methanol, HPLC grade RCI Labscan USA

Methyl heptadecanote, AR grade Fluka USA

Potassium hydroxide Ajax Finechem Australia

Toluene, AR grade RCI Labscan USA

Sodium carbonate (Na2CO3) Ajax Finechem Australia

Sodium sulfate anhydrous (Na2SO4) Ajax Finechem Australia

Sulfuric acid, 98% QReC New Zealand

Mixed Waste cooking oil (WCO) TU Canteen Thailand

32

3.1.2 Equipments

Table 3.2 List of the instrument used in this research

Instrument Brand

Autoclave reactor, 50ml Parr, USA

Autoclave reactor, 400 ml Amar Equipment, India

Centrifugation Labquip, England.

Fourier Transform Infrared spectroscopy

(FT-IR)

Perkin Elmer, Spectrum 100 FT-IR

spectrometer

Gas Chromatography-Flame Ionization

Detector (GC-FID)

Shimadzu, Japan, GC-17A

Gas Chromatography-Mass Spectrometry

(GC-MS)

Shimadzu, Japan, GCMS-QP

2010

High Performance Liquid Chromatograph

(HPLC)

Shimadzu, Japan, LC-20AT

(pump), SPD-20A (UV dectector)

N2 sorption Quantachrome, USA

Oven Memmert UF 110

Scanning Electron Microscope (SEM) JEOL, Japan, JSM-6510LV

Temperature Programed Desorption

of ammonia (NH3-TPD)

Thermo Electron Instrument,

USA, TPD/R/O1100

X-ray photoelectron Spectroscopy (XPS) ULVAC-PHI, Japan, PHI 500

VersaProbe II

3.2 Methods

3.2.1 Preparation of carbon solid acid catalyst (CM-SO3H)

The carbon solid acid catalyst was prepared by sequential

hydrothermal carbonization and sulfonation of xylose.

33

First of all, 20.0 mL of 50 wt.% xylose solution was transferred to 50.0

mL an autoclave, heated to temperature of 190C and maintained at this temperature

for 24 h. The resulting solid product was recovered by centrifugation at 4000 rpm for

15 minutes and washed with DI water. Then, the carbon solid was dried at 90C for 4h.

For sulfonation, the mixture of carbon 1.0 g and 20.0 mL H2SO4 (98%)

was placed in an autoclave and heated at 150C for 15 h. Then, the carbon solid catalyst

was collected by centrifugation at 5000 rpm for 15 min and washed repeatedly with

abundant DI water until pH 7.0. Finally, the product was dried at 90C for 4 h. The

synthesis of CM-SO3H catalyst could be summarized in Figure 3.1.

In addition, a porous carbon solid acid catalyst (P-C-SO3H) was

derived by activation of carbon microsphere with potassium hydroxide to improve their

porous properties. The mixture of 2.0 g of carbon microsphere and 8.0 g of KOH (25

wt.%) were transferred to crucible, heated at 700C for 2 h with 3C/min. Then, the

carbon solid was collected by vacuum filtration and washed with abundant DI water

until pH 7.0. Next, the porous carbon was dried at 90C for 4 h. Finally, the P-C-

SO3H was sulfonated by same method with CM-SO3H.

Figure 3.1 Schematic diagram of synthesized CM-SO3H catalyst

34

3.2.2 Characterization of catalyst

3.2.2.1 Study the morphology of catalyst

The surface morphology and particle size distribution of hydrothermal

carbon, CM-SO3H, and reused CM-SO3H were determined by a scanning electron

microscope (SEM, JEOL JSM-6510LV). All of sample were dried at 70C, overnight

for removed moisture and then put up on a SEM stub, coated with thin layer of gold

under vacuum and observed at 20 kV.

3.2.2.2 Study the textural analysis

The porous structure and surface area of hydrothermal carbon, CM-SO3H,

and reused CM-SO3H were analyzed by N2-sorption using an Autosorb-iQ instrument

(USA). The surface area was identified from Brunauer Emmett Teller (BET) equation

using standard data from isotherm on nonporous carbon and the pore size, pore volume

was identified from Barrett Joiner Halender model (BJH).

3.2.2.3 Study the functional group

The presence of functional groups on the hydrothermal carbon, CM-SO3H,

and reused CM-SO3H surface were characterized by Attenuated Total Reflectance

Fourier transform infrared spectroscopy (ATR-FTIR). All of sample were dried at

70C, overnight for removed moisture and then put onto a sample holder. After that,

the infrared spectra were recorded wavelength number from 4000 to 500 cm-1 with 32

scans.

The elemental composition and functional group (-SO3H) were

characterized by X-ray photoelectron spectroscopy (XPS) using Al-Kα radiation (hν =

117.40 eV).

3.2.2.4 Study the properties of acid sites

The acid strength of catalyst was investigated by Temperature Programed

Desorption of ammonia (NH3-TPD) using Thermo Electron Instrument, TPD/R/O1100.

35

And the amount of –SO3H and –COOH groups on the catalyst surface was calculated

by titration method and used phenolphthalein as an indicator. The amount of acid

groups on catalyst surface was determinized by amount of spent NaOH 0.1N.

3.2.3 Catalytic activity in biodiesel production from waste cooking oil

3.2.3.1 Biodiesel production

Waste cooking oil (WCO) was provided by a restaurant in Thailand used

as the raw material for the production of biodiesel. The reaction was carried out by two

steps process for overcoming the chemical equilibrium. Each step was done as this

procedure. The mixture of WCO, methanol and CM-SO3H was transferred to 400 mL

an autoclave (Amar Equipments, India) and heated to desired temperature and time

under stirring rate at 500 rpm. The effect of reaction factors were investigated such as:

weight percent of catalyst/oil (5.0 to 15.0 wt.%), molar ratio of methanol/oil (5.64:1,

9.35:1, 14.87:1), reaction temperature (90 - 150°C) and reaction time (0.5 - 6.0 h). After

the reaction, the reactor was cooled down and then the mixture of the product was

centrifuged at 5000 rpm for 15 min to separate the catalyst. Next, the product was

poured into a separatory funnel and allowed to phase separate for 8 h. After separation,

the above layer was washed with hot deionized water until pH value in the aqueous

phase reached 7.0. After that, the methyl ester phase, upper phase, was dried at 105°C

for 45 min for remove remained of methanol and water. The fatty acid methyl ester

(FAME) yield was analyzed by gas chromatography follow standard method EN 14103.

The second step biodiesel production was carried out by repeating the first step with

biodiesel fraction of the first step.

3.2.3.2 FAME analysis

The fatty acid methyl ester (FAME) yield was determined by gas

chromatography (Shimadzu GC-17A, flame ionization detector). The capillary column

was DB-WAX (30.0 m length, 0.25 mm internal diameter and 0.25 mm film thickness).

The column temperature were shown in Table 3.3. And 1.0 µL of prepared sample

would be injected at GC injection port by using a syringe for GC. Standard sample was

36

used to calculate the FAME yield by integration of the peak areas using internal

standard method by Equation 3.1.

Table 3.3 The program of column temperature

Column temperature program

Initial temperature: 150C hold at 5 min

Rate 1: 3C/min to 190C hold at 5 min

Rate 2: 3C/min to 220C hold at 10 min

EI EI EIyield

EI

( A) A C x V%FAME x x100

A m

(3.1)

A is the total peak area of methyl ester peak from C14 to C24:1

AEI is the peak area of internal standard (methyl heptadecanoate, C17)

CEI is the concentration of the internal standard (mg/mL)

VEI is the volume of the internal standard solution (mL)

m is the mass of the sample (mg)

3.2.3.3 Catalyst reusability

For the catalyst reusability, the used catalyst was washed with acetone and

dried at 70C, overnight. The catalytic activity was then tested under the same as

previous procedure done by fresh catalyst.

3.2.4 Catalytic activity in furfural production via xylose dehydration

3.2.4.1 Dehydration of xylose

The xylose dehydration was carried out in an 400 mL autoclave (Amar

Equipments, India) containing the mixture of xylose solution (0.50 g xylose dissolved

with 12.5 mL DI water), 12.5 mL toluene and CM-SO3H catalysts. The reactor was

heated to desired reaction temperature (120, 140, 155 and 170°C) at stirring rate of 450

rpm for suspected reaction time (1–3 h). After the reaction finish, the mixture was

cooled down, the product was washed from the reactor by 12.5 mL DI water and 12.5

37

mL toluene. Then filtered to separate the catalyst and washed product with 25.0 mL DI

water and 25.0 mL toluene to obtain the liquid product with two layers in separatory

funnel: toluene phase and aqueous phase. The upper layer was separated and dried over

anhydrous sodium sulfate. Two liquid phases were filtered before analysis. Then,

furfural was determined by high-performance liquid chromatography (HPLC)

connected with UV detector and Agilent Eclipse XDB-C18 column. [59] Xylose

content was determined by gas chromatography-mass spectroscopy with headspace

technique using HP-5 which was reported by Kaiprommarat, et.al and Li, et.al. [65, 68]

3.2.4.2 Product analysis

The furfural yield both 2 phases (toluene and aqueous phase) were

analyzed by high-performance liquid chromatography (Shimadzu, Japan) with Agilent

Eclipse XDB-C18 column (4.6 mm ID x 250 mm), the mobile phase at flow 1.0 mL/min

with volume ratio of acetonitrile/DI water (v/v) is 15/85, and 20.0 µL of sample would

be injected. The xylose conversion was determinized by headspace gas

chromatography-mass spectrometry (GCMS-QP2010, Shimadzu, Japan) with HP-5

column (0.25 mm ID, 30 m length, 0.25 mm film thickness). The injection temperature

at 105°C. The column oven temperature was started at 70°C and heat up to 90°C with

2°C/min. [65]

The furfural yield, furfural selectivity and xylose conversion were

calculated by equation 3.2, 3.3 and 3.4, respectively. [65, 69]

Moles of furfural producedFurfural yield = x100

Moles of starting xylose(3.2)

Moles of furfural producedFurfural selectivity = x100

Moles of xylose reacted(3.3)

Moles of xylose reactedXylose conversion = x100

Moles of starting xylose(3.4)

38

CHAPTER 4

RESULTS AND DISCUSSION

4.1 Characterization of the carbon catalyst

Carbon microsphere was prepared by hydrothermal carbonization of xylose

and functionalized with sulfonic acid. This catalyst was designated as CM-SO3H

catalyst. In addition, a porous carbon solid acid catalyst (P-C-SO3H) was synthesized

by activation of carbon microsphere with potassium hydroxide and functionalized with

sulfuric acid.

4.1.1 N2 sorption analysis

The textural properties of carbon microsphere, CM-SO3H and P-C-SO3H

were studied by nitrogen absorption and desorption which the isotherms are presented

in Figure 4.1. The isotherm of both carbon microsphere and CM-SO3H conformed to

type II isotherm with a hysteresis loops of H3 to imply non-porous structures and

according to slit-shaped pores agglomerated due to changing of particle sizes after

functionalized from 0.8 m to 2.7 m. The isotherm of P-C-SO3H was the type IV

isotherm with a hysteresis loops of H4, which refers to a mesoporous strucutre with

narrow slit shape pore.

39

Figure 4.1. Nitrogen sorption isotherms of (a) carbon microsphere (CM): overlay 40

units; (b) solid acid catalyst (CM-SO3H): overlay 80 units and (c) porous carbon solid

acid catalyst (P-C-SO3H)

The pore size distribution and textural properties such as BET surface area,

BJH pore size, and pore volume are presented in Figure 4.2 and Table 4.1, respectively.

The surface areas were calculated with the Brunauer–Emmett–Teller (BET) equation

using standard data for N2 adsorption on nonporous carbon. The carbon microsphere

has a high surface area (SBET = 95.5 m2/g) which was higher than the sulfonated carbon

microsphere (SBET = 86.3 m2/g) and porous carbon solid acid catalyst (SBET = 74.4 m2/g)

due to agglomeration of carbon particle after sulfonation. In addition, pore size of CM-

SO3H was increased from 3.4 nm to 6.6 nm that effect from the formation of SO3H

group on carbon microsphere surface. Because, most of the pores are formed by the

agglomeration of particles. Therefore, the uniform particle size caused the uniformity

of the pore sizes. Moreover, the larger particles formed larger interparticle pores. [29,

70]. This results could be suggested by the particle size distribution of hydrothermal

carbon and CM-SO3H, which could be observed by SEM.

0

40

80

120

160

200

240

280

320

0 0.2 0.4 0.6 0.8 1

Volu

me

@ S

TP

[cc

/g]

Relative Pressure (P/P0)

(a)

(b)

(c)

(a)

(b)

(c)

40

Figure 4.2 Pore size distribution of (a) carbon microsphere; (b) carbon solid acid

catalyst (CM-SO3H) and (c) porous carbon solid acid catalyst (P-C-SO3H)

Table 4.1 Textural properties and acidity of carbon microspheres, and catalysts.

BET surface

area (m2/g)

Pore size

(nm)

Pore volume

(cc/g)

Acidity

(NH3-TPD)

Carbon microsphere 95.5 3.4 0.094 0.049

CM-SO3H 86.3 6.6 0.09 1.38

P-C-SO3H 74.4 3.8 0.54 1.28

3rd reused CM-SO3H 10.4 3.4 0.01 0.59

4.1.2 The morphology of catalyst

The morphology of carbon microsphere and carbon solid acid catalyst

(CM-SO3H), are shown in Figure 4.3. Both carbon microsphere, CM-SO3H were

spherical shape with average particle diameter as 0.8 m, 2.7 m, respectively.

According to SEM micrograph, carbon microsphere presented uniform particle size

whereas, the CM-SO3H particle was wide distribution because adding sulfuric acid to

the carbon microsphere not only functionalized the sulfonic group (-SO3H) on carbon

microsphere but also the presence of sulfuric acid in sulfonation step catalyzed

dehydration of xylose to furan compounds which were important intermediates for

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

1 10 100

dV

(lo

gd

) (c

c/g)

Pore diameter (nm)

(b)

(a)

(c)

41

carbonization. However, the excess of furan compounds promoted fast polymerization

rate to grow carbon particle without uniformity. Qi. Xinhua et al. [70] reported that

catalyst growth by swell, diffusion and linkage from the –SO3H group to the surface.

Figure 4.3 SEM microphotograph of (a) carbon microsphere; (b) carbon solid acid

catalyst (CM-SO3H).

4.1.3 The properties of acid sites

The acid properties including acidity and acid strength of CM-SO3H and P-

C-SO3H catalyst were investigated by NH3-TPD analysis. The NH3-TPD profile of

catalysts presented two acid sites as shown in Figure 4.4 and Table 4.1. The low and

high desorption temperature corresponded to weak and strong acid sites, respectively

[51, 52]. The major peak as weak acid site was observed at the temperature 170°C to

represent desorption of ammonia from carboxylic group. The carboxylic was derived

from oxidation of aldehyde functional group containg in aldose sugar under

hydrothermally condition. The second peak at temperature 250°C was generated by

42

ammonia desorption from sulfonic acid site. The total acidity of CM-SO3H and P-C-

SO3H catalyst were 1.38 mmol/g and 1.28 mmol/g, respectively. According to NH3-

TPD graph of acid sites, the carboxylic group and sulfonic group were different between

two catalysts. Because, after activation of carbon microsphere with potassium

hydroxide decarbonylation removed C=O to decrease number of carboxylic acid.

Figure 4.4 NH3-TPD profile of (a) carbon solid acid catalyst (CM-SO3H) and (b)

porous carbon solid acid catalyts (P-C-SO3H)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 100 200 300 400

Sig

nal

(mV

)

Temperature (C)

(a)

-COOH

-SO3H

0 100 200 300 400

Sig

na

l (m

V)

Temperature (C)

-COOH

-SO3H

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 100 200 300 400

Sig

na

l (m

V)

Temperature (C)

(a)-COOH

-SO3H

(b)

43

4.1.4 The functional group

The presence of functional group on the surface of carbon microsphere,

CM-SO3H and P-C-SO3H were identified by FTIR and XPS spectral, as shown in

Figure 4.5 and Figure 4.6, respectively. Both hydrothermal carbon, sulfonated carbon

microsphere and porous carbon solid acid catalyst displayed major characteristic peaks

of hydrothemally carbon including C=O group (carbonyl, quinone, ester, or carboxyl)

at 1701 cm-1, C=C group (alkenyl) at 1602 cm-1, C–O group (ether, hydroxyl or ester)

at 1020 cm-1, and C-H group (aromatic) at 875–750 cm-1 [25, 71]. After sulfonation,

the distinct absorption peak at 1032 cm-1 and weak absorption peak at 1171 cm-1 were

appeared according to O=S=O and -SO3H, respectively. [71] In the region of 3390 cm-

1, the broad peak of a –OH group, which could be in the form of –SO2OH or –COOH,

was also appeared. [72] These results confirm the presence of the -SO3H group on the

CM-SO3H and P-C-SO3H catalyst surface. Much stronger absorption peaks around

1032 cm-1 and 1171 cm-1 in P–C–SO3H to compared with CM–SO3H are assigned

higher amount of S=O and –SO3H, respectively, which clearly suggested the higher

loading of the sulfonic acid functional group in the P–C–SO3H than CM–SO3H was

obtained.

44

Figure 4.5 FTIR spectral of (a) carbon microsphere, (b) CM-SO3H and (c) P-C-SO3H

In addition, the XPS spectra of CM-SO3H showed peaks of S 2p, C 1s, and

O 1s. The peak of S 2p at 169 eV corresponds to sulfonic acid (-SO3H), to confirm the

existence of sulfonic acid groups (-SO3H) on the carbon microsphere surface. The C 1s

peak at 285 eV, 286 eV, and 289.3 eV were corresponds to C-C bonding, C-O, and –

COO functional groups, respectively. [73, 74] Therefore, the CM-SO3H exhibited two

different acid sites for the catalysis of biodiesel production, carboxylic acid, and

sulfonic acid.

5001000150020002500300035004000

Tra

nsm

itta

nce

(a

.u)

Wavenumber (cm-1)

C-O

stretching

C-H

aromatic

O-H

C=O C=C

-SO3H

S=O

(a)

(b)

(c)

O-H

45

Figure 4.6 XPS spectra of CM-SO3H

4.2 Catalytic activity in biodiesel production from waste cooking oil

The chemical composition and physicochemical properties of waste

cooking oil are shown in Table 4.2.

Table 4.2 The chemical composition and physicochemical properties of waste cooking

oil

Properties WCO Biodiesel**

Heptanal (C7H14O) (%) 11.85 N/A

Palmitic acid (C16:0) (%) 22.68 N/A

Oleic acid (C18:1) (%) 19.12 N/A

Nonadecylic acid (C19:0) (%) 46.35 N/A

Mean molecular wt. (g mol-1)* 787.36 N/A

Acid value (mg KOH g−1) (ASTM-D664) 2.7 0.72

0

3000

6000

9000

12000

15000

0 100 200 300 400 500 600

Ch

emic

al

Sta

te

Binding Energy (eV)

C 1sC-O

C-C

-COO

-SO3H

O 1s

S 2p

46

% FFA 1.54 0.36

Kinematic viscosity (at 40˚C cSt) (ASTM-D445) 60.10 6.41

Water and sediment (v/v %) (ASTM-D2709) 0.03 0.005

Flash point (˚C) (ASTM-D92) >370 167

Pour point (˚C) (ASTM-D97) -22 -7.5

Ash content (%) (ASTM-D482-13) 0.16 0.057

Remark:

(*) Mean molecular weight (mol/g) = 3 x (Percent of fatty acid x molar

mass of fatty acid).

(**) The biodiesel production was prepared at 110C for 2 h, ratio of

oil/methanol is 1:9.35 and 10 wt.% of catalyst loading.

4.2.1 Effect of reaction temperature

The effect of reaction temperature on the biodiesel yield was investigated

at four different temperatures, as shown in Figure 4.7. The effect of reaction

temperature performed endothermic reaction behavior that increasing FAME yield was

obtained by raising reaction temperature. However, the increasing reaction temperature

over boiling point of methanol decreased the FAME yield owning to the evaporation of

methanol to reduce the stoichiometric ratio between oil and methanol. In addition, less

acitve site in catalyst would be obtained because at high reaction temperature –SO3H

functional group would be decomposed [50, 75]. The highest FAME yield was 82.5

wt.% at 110°C for 6 h.

47

Figure 4.7 FAME yield with different reaction temperatures at reaction time 6 h,

molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%.

4.2.2 Effect of reaction time

The effect of reaction time on FAME yield was studied at 110C, it can be

seen that the reaction reached to equilibrium within 2 h to obtain highest FAME yield

of 89.6% as shown in Figure 4.8. The increasing of biodiesel yield was derived by

increasing reaction time. Moreover, the longer reaction time (over than 2 h) did not

significantly provide higher FAME yield due to deactivated the acid site (–SO3H)

which was binding with the polar molecules from reaction such as methanol and water

[76].

#REF!

#REF!

0

20

40

60

80

100

90 110 130 150

68.04

82.5

72.469.7

%Y

ield

of

bio

die

sel

Reaction temperature (C)

First step

Second step

48

Figure 4.8 FAME yield with different reaction times at reaction temperature 110C,

molar ratio of oil/methanol 1:9.35, and catalyst loading 10 wt.%.

4.2.3 Effect of catalyst loading

The amount of catalyst affected to the conversion of waste cooking oil as

shown in Figure 4.9. The different catalyst loading including 5 wt.%, 10 wt.%, 15 wt.%

were investigated. When the increasing of catalyst loading from 5 to 15 wt.% performed

increasing the percentage of FAME yield. However, high catalyst loading induced non-

uniform mixing and increased the viscosity of the reaction mixture causing a reduction

in the efficiency of reactant transport to obtain lower the biodiesel yields [50].

Moreover, in the case of less catalyst loading, the acid capacity of the catalyst was not

enough for active in the interface of two-phases (methanol and oil) to convert oil to

FAME [50, 51, 72]. Therefore, 10 wt.% loading of the carbon solid acid catalyst was

selected as the optimal amount.

#REF!

#REF!

0

20

40

60

80

100

0.5 1 2 3 6

64.96

72.95

89.6 88.182.5

%Y

ield

of

bio

die

sel

Reaction time (h)

First step

Second step

49

Figure 4.9 FAME yields with different catalyst loading at reaction temperature

110 C for 2 h; molar ratio of oil/methanol is 1:9.35.

4.2.4 Reusability

The stability of the sulfonated carbon microsphere catalyst was also

investigated. The spent of catalyst was tested reusability up to 3rd cycles at the optimum

condition (reaction temperature 110C for 2 h, molar ratio of oil/methanol is 1:9.35, 10

wt.% of catalyst loading). The reusability of catalyst is shown in Figure 4.10. The

biodiesel yield was decreased by 21% after 3 cycles. The reduction of the catalytic

activity was caused by the deactivation of catalyst within reaction process. [54, 72] The

acidity of spent catalyst after 3 cycles of reuse was 0.59 mmol/g. The characterizations

of spent catalyst were investigated by N2 sorption, SEM micrograph, and NH3-TPD as

shown in Figure 4.11, 4.12 and 4.13, respectively. However, the reusability of CM-

SO3H catalyst would be suggested for application of biodiesel production from WCO.

First step

Second step

0

20

40

60

80

100

5 10 15

77.5

89.680.8

%Y

ield

of

bio

die

sel

Catalyst loading (wt.%)

First step

Second step

50

Figure 4.10 FAME yield with spent catalyst at reaction temperature 110 C for 2 h

and 10 wt. % catalyst loading

Remark:

(*) The WCO was treated by sequential reacting with DI water, H3PO4, and

NaOH, respectively. First, 100ml of WCO was mixed with 5ml of DI water and stirred

at 80C for 15 min. Then the WCO was collected by centrifuged at 3500 rpm for 20

min. Next, 25g of WCO after water degumming was mixed with 0.025g (0.1 wt.% of

oil ) of H3PO4 (14%, QREC) and stirred at 80C for 5 min. After the short reaction time

the acid in partially neutralized with 0.075g (0.3 wt.% of oil ) NaOH (20% water

solution) and stirred at 80C for 5 min. The treatment WCO was collected by

centrifuged at 3500 rpm for 20 min. [77]

The structures of carbon catalyst after 3 cycles of reused was identified by

the characteristic N2 isotherms, as shown in Figure 4.11 (a). This catalyst presented

hysteresis type 1 (H1) with small adsorption volume because the pore was blocked by

reaction compounds to hinder the penetration of gas through inside the pore.

0

20

40

60

80

100

Fresh

catalyst

Fresh

catalyst

1st cycle 2nd cycle 3rd cycle

96.6

89.6

80.7

73.4 70.2

%Y

ield

of

bio

die

sel

Fresh catalyst 1st cycle 2rd cycle 3nd cycle3nd cycle2rd cycle 3nd cycle1st cycleFresh catalyst

First step

Second step

With treatment WCO (*) Without treatment WCO

51

The pore size distribution and textural properties such as BET surface area,

BJH pore size, and pore volume are reported in Figure 4.11 (b) and Table 4.1,

respectively. The decrease in the surface area carbon catalyst after 3 cycles of reused

increased the particle size, which could be observed by SEM. In addition, the surface

area of reused sulfonated carbon microsphere decreased dramatically owning to loss of

internal surface area (area inside the pore).

Figure 4.11 (a) N2 sorption isotherm and (b) pore size distribution of spent sulfonated

carbon catalyst after 3 cycles of reused

0

2

4

6

8

10

12

0 0.2 0.4 0.6 0.8 1

Volu

me

@ S

TP

[cc

/g]

Relative Pressure (P/P0)

(a)

0

0.01

0.02

0.03

1 10 100

dV

(logd

) (c

c/g)

Pore diameter (nm)

(b)

52

The morphology and particle size distribution of carbon catalyst after 3

cycles of reused are shown in a scanning electron micrograph Figure 4.12. The reused

CM-SO3H was increased the average particle diameter from 2.7 m to 3.2 m and 3.9

m for fresh catalyst, 1st reused CM-SO3H and 3rd reused CM-SO3H, respectively. Due

to the SEM micrographs of reused CM-SO3H discovered the agglomeration of the CM-

SO3H particles. Moreover, the surface of CM-SO3H was covered by reaction

compounds.

Figure 4.12 SEM microphotograph of spent sulfonated carbon catalyst of biodiesel

production.

The total acidity of reused CM-SO3H decreased from 1.38 to 0.59 mmol/g

after reused for 3 cycles which was resulted by the leaching of sulfonic acid and the

coverage of reaction compounds. The leaching of sulfonic acid was confirmed by the

decreasing of the NH3 desorption peak area of sulfonic at 250C as shown in Figure

4.13.

0

20

40

60

80

100

1 2 3 4 5

Fre

qu

en

cy

(%

)

Microsphere Size (m)

Reuse -1st cycle

Mean size (m) 3.22

Median (m) 2.56

Mode (m) 3.51

Std.Dev. 1.14

0

20

40

60

80

100

1 2 3 4 5

Fre

qu

en

cy

(%

)

Microsphere Size (m)

Reuse - 3rd cycle

Mean size (m) 3.86

Median (m) 3.24

Mode (m) 4.23

Std.Dev. 1.91

5m 5m

Reuse – 3rd cycleReuse – 1st cycle

53

Figure 4.13 NH3-TPD profile of spent sulfonated carbon catalyst after 3 cycles of

reused

4.3 Catalytic activity in furfural production via xylose dehydration

4.3.1 Effect of reaction temperature

To optimize the reaction conditions by studying the effects of reaction

temperature, reaction time and catalyst loading on xylose conversion and furfural yield,

furfural selectivity. Initially, the reaction temperature was varied from 120C to 170C.

The xylose conversion, furfural selectivity and furfural yield increased with increasing

reaction temperature as shown in Figure 4.14. However, the furfural yield and furfural

selectivity were decreased at high reaction temperature since D-xylose convert to

carbonize and degrade of catalyst which will affect the activity of the catalyst. [63, 78]

Therefore, the suitable reaction temperature 155C was shown the highest furfural yield

(22.8%) and furfural selectivity (23.9%).

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 100 200 300 400

Sig

nal

(mV

)

Temperature (C)

-COOH

-SO3H

54

Figure 4.14 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity with different reaction temperature at reaction time 2h and 50

wt.% catalyst loading

4.3.2 Effect of reaction time

The effect of reaction time is shown in Figure 4.15. The reaction time did

not significantly affected xylose conversion because the chemical equilibrium was fast

approached [65]. On the other hand, furfural yield and furfural selectivity decreased as

longer reaction time due to side reaction including polymerization and oligomerization

of furfural to furanic resins, a solid residue and formation of soluble degradation

products. [78]

0

20

40

60

80

100

120 140 155 170

(%)

Reaction temperature (C)

Conversion (%) Selectivity (%) Yield (%)

55

Figure 4.15 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity with different reaction times at reaction temperature 155C and 50

wt.% catalyst loading.

4.3.3 Effect of catalyst loading

The amount of catalyst was also studied from 10 wt.% to 50 wt.%. High

furfural yield and furfural selectivity would be obtained at the amount of catalyst less

than 50 wt.% as shown in Figure 4.16. According, the higher amount of catalyst

contained higher number of free active sites available for the reactant to give a higher

yield of furfural and selectivity of furfural. However, an excess amount of catalyst is

not essential for this reaction due to reduction of furfural yield and furfural selectivity.

Therefore, the suitable catalyst loading was 25 wt.% to produce 94.1%, 44.5% and

33.9% of xylose conversion, furfural selectivity, and furfural yield, respectively. [79]

0

20

40

60

80

100

1 2 3

(%)

Reaction time (h)

Conversion (%) Selectivity (%) Yield (%)

56

Figure 4.16 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity with different catalyst loading at reaction temperature 155C for

2h.

To improved the furfural yield and furfural selectivity of CM-SO3H

catalyst, the P-C-SO3H containing porous structure was prepared to reduce the pore

diameter of the CM-SO3H catalyst from 6.6 nm to 3.8 nm. The catalytic activity of the

P–C–SO3H and CM–SO3H catalysts was benchmarked in dehydration of xylose to

produce furfural at reaction temperature 155C for 2 h as shown in Figure 4.17. The P-

C-SO3H catalyst could increase the furfural selectivity and furfural yield to 68.4% and

65.1% , respectively. The greater catalytic activity of P–C–SO3H as compared to CM–

SO3H could be explained on the basis of suitable pore size and pore volume of catalyst.

Because a pore diameter in the range of 3–6 nm could provide the selective in furfural

which was reported by Kaipromarat S. et al. [65]

The reusability of the catalyst was investigated over three reaction cycles.

The selectivity of furfural decreased from 72% to 30% after 3rd cycle. The significantly

decrease in furfural selectivity resulted due to the leaching of sulfonic acid groups from

spent catalyst.

0

20

40

60

80

100

10 25 50

(%)

Catalyst loading (wt.%)

Conversion (%) Selectivity (%) Yield (%)

57

Figure 4.17 Catalytic performance including xylose conversion, furfural yield and

furfural selectivity between CM-SO3H and P-C-SO3H catalysts at reaction

temperature 155C for 2 h and 25 wt.% catalyst loading.

0

20

40

60

80

100

CM-SO3H P-C-SO3H 1st cycle 2nd cycle 3rd cycle

(%)

Conversion (%) Selectivity (%) Yield (%)

CM-SO3H P-C-SO3H 1st cycle 2nd cycle 3rd cycleCM-SO3H P-C-SO3H 1st cycle

Fresh catalyst Used catalyst of P-C-SO3H

58

CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions

Carbon microsphere could be prepared by hydrothermal carbonization of

xylose and functionalized with sulfonic acid. In addition, a porous carbon solid acid

catalyst (P-C-SO3H) was also synthesized by activation of carbon microsphere with

potassium hydroxide to improve their porous properties.

The structure, morphology and pore volume of carbon microsphere, CM-

SO3H catalyst and P-C-SO3H catalyst were investigated. The catalysts presented large

surface area. The CM-SO3H catalyst contained the pore structure as microporous

structures. Meanwhile, the P-C-SO3H represented that disorder slit-shaped pore

tructures. Beside that SEM micrograph was shown the spherical shape with smooth

surface area and non-uniform of carbon catalyst owning with interaction of –SO3H

group on catalyst surface. The FT-IR spectral of CM-SO3H and P-C-SO3H were shown

the absorption band at 1032 cm-1 and 1171 cm-1 appeared according to O=S=O and -

SO3H, respectively. In the region of (3000 – 3390) cm-1, the absorption band of a –OH

group, which could be in the form of -SO2OH or –COOH, also appeared. In addition,

the –SO3H group was confirmed by S 2p peak of XPS spectra at 169 eV. The acidity

and acid strengh of carbon catalyst were investigated by NH3-TPD analysis. The total

acidity of CM-SO3H and P-C-SO3H were 1.38mmol/g and 1.28 mmol/g, respectively.

The optimized condition of biodiesel production from waste cooking oil

was reaction temperature 110C for 2 h, molar ratio of oil/methanol is 1:9.35 and 10

wt.% of catalyst loading. The catalyst performed good catalytic activity with 89.6%

yield of biodiesel without any treatment of waste cooking oil. The reusability of catalyst

was also investigated at the optimum condition. The biodiesel yield decreased by 21.0

% after 3 cycles.

In addition, the catalyst was tested the catalytic perforance in dehydration

of xylose to produce furfural. The highest furfural yield, furfural selectivity, and xylose

59

conversion were 39.3 %, 44.5 % and 94.1 %, respectively with CM-SO3H catalyst.

However, furfural yield and furfural selectivity could be improved by P-C-SO3H

catalyst. The P-C-SO3H catalyst contained smaller pore than CM-SO3H catalyst to

selective with furfural. The P-C-SO3H catalyst could be increase furfural yield, furfural

selectivity to 65.1 % and 68.4 % , respectively at the xylose conversion of 95.2 %.

In conclusion, the sulfonated carbon microsphere catalyst can be a

candidate the acid catalyst to perform the good performace in biodiesel production and

xylose dehydration, moreover the sulfonated carbon could be proposed the material for

environmentally benign, low-cost.

5.2 Recommendations

The thermal stability and acid strength of carbon catalyst should be

developed to improve the reusability of catalyst for both biodiesel production and

furfural production. In addition, the pore size and pore volume of catalyst still need to

be modified for improve the furfural yield and furfural selectivity.

60

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67

APPENDICES

68

APPENDIX A

Carbon microsphere characterization

The carbon microsphere was studied the effect of reaction temperature (170

– 190C), reaction time (12 h – 24 h) and weight ratio of xylose to water (10 wt.% - 50

wt.%). The yield (%) of carbon microsphere was calculated by Equation (A1).

Figure A1. Yield of carbon microsphere obtained from different conditions of

hydrothermal.

carbon microsphere

Weight of carbon produced (g)Yield (%) = x100

Weight of starting xylose (g) (A1)

The physicochemical properties of carbon microsphere were studied the

morphology and physical structure characteristic by Scanning Electron Microscope

(SEM). Confirmation of functional group by Fourier Transform Infrared spectroscopy

(FT-IR). Analysis the surface area and particle size by N2 sorption and study and

confirmation elemental carbon, hydrogen, nitrogen by CHN analyzer.

0

10

20

30

40

50

170°C 190°C 170°C 190°C 170°C 190°C 190°C

12h 16h 20h 24h

Yie

ld (

%)

10wt% 25wt% 50wt%

69

Figure A2. SEM micrograph of carbon microsphere at 190C – 50wt.% (xylose

concentration) with different reaction time.

70

Figure A3. FT-IR spectra of carbon microsphere at 190C – 50wt.% (xylose

concentration) with different reaction time.

Figure A4. N2 sorption of carbon microsphere at 190C – 50wt.% (xylose

concentration) with different reaction time.

0

10

20

30

40

50

60

70

0 0.2 0.4 0.6 0.8 1

Volu

me

@ S

TP

[cc

/g]

Relative Pressure (P/P0)

12h 16h 20h 24h

71

Demethanation Dehydration Decarboxylation

Figure A5. Van Krevelen diagram of carbon microsphere from different conditions of

hydrothermal.

Table A1. Physical properties of carbon microspheres at 190C – 50wt.% (xylose

concentration) with different reaction time.

Reaction

time (h)

BET surface area

(m2/g)

Pore size

(nm)

Pore volume

(cc/g)

12 16.1 7.8 0.032

16 31.1 4.9 0.06

20 67.0 4.5 0.07

24 95.5 3.4 0.094

72

APPENDIX B

Standard calibration curve preparation

1. Standard calibration curve for furfural production (HPLC)

First, a furfural solution was prepared by 0.01g of furfural (AR grade, 99%,

Sigma-Aldrich) was dissolved in Toluene and titrated in 10 mL volumetric flasks. Then

using that solution to prepare several standard solution in 10 mL volumetric flasks (0.2,

0.4, 0.6, 0.8 and 1.0 mM) follow by Equation (B1).

C1V1 = C2V2 (B1)

C1: Initial concentration of furfural solution ( 10.05 mM)

V1: Amount of initial furfural solution (mL)

C2: Desire concentration of furfural solution (0.2 – 1 mM)

V2: Amount of desire furfural solution (10 mL)

The linear equation of this curve is y = 9 x 106X and R2 = 0.9992 was shown

in Figure B1. This curve was used to calculated furfural yield and furfural selectivity

follow by Equation (1), (2) in Chapter 3.

Figure B1. Standard calibration curve for furfural production (HPLC)

y = 9E+06x

R² = 0.9992

0

2000000

4000000

6000000

8000000

10000000

0 0.2 0.4 0.6 0.8 1

Pea

k A

rea

Concentration (mM)

73

2. Standard calibration curve for xylose converstion (HS-GC-MS)

Xylose solution was prepared with xylose concentration (5 – 30 ppm). First,

the mixture of 1.0 mL xylose solution and 5.0 mL H2SO4 (98%, QRecC) were

transferred to the bottle. After that, the bottle was put in the water batch at 70C for 15

min. Finally, 100 L of this product was pipetted into headspace vials that contained

Na2CO3 anhydrous for analysis with HS-GC-MS. [65, 68]

The linear equation of this curve is y = 107 X and R2 = 0.9945 was shown in

Figure B2. This calibration curve was used to calculate an amount of furfural in the

sample. It also refer to the amount of xylose conversion follow Equation (3) in Chapter

3.

Figure B2. Standard calibration curve for xylose conversion (HS-GC-MS)

y = 1E+07x

R² = 0.9945

0

100000000

200000000

300000000

400000000

500000000

0 5 10 15 20 25 30

Pea

k A

rea

Concentration of xylose (ppm)

74

3. Acidity calculation

The acidity was prepared by titration method. The mixture of 0.1 g carbon

catalyst, 0.1 g NaCl and 10.0 mL DI water were stirred at room temprature for 16 h.

Then filtered and titrated with NaOH solution 0.1N. Finally, the acidity was calculated

using Equation B2.

C1V1 = C2V2 (B2)

C1: Concentration of NaOH solution (0.1M)

V1: Amount of NaOH solution was used for titration (mL)

C2: Concentration of acid catalyst (M)

V2: Amount of catalyst solution (10 mL)

After calculated concentration of carbon catalyst (M), we should change

the unit to mmol/g.

75

APPENDIX C

By-products of xylose dehydration

The by-products of xylose dehydration was determined by using toluene

phase and analysis with GC-MS.

Table C1. Yield of by-products under xylose dehydration with CM-SO3H catalyst at

different reaction temperature for 2 h and 50 wt.% catalyst loading

By-products Reaction temperature (C)

120 140 155 170

Air 0.05 0.04 0.05 0.05

Acetone (CH3)2CO 0.31 0.45 0.34 0.43

Benzene (C6H6) 0.18 0.17 0.12 0.17

Heptane (C7H14) 0.07 0.07 0.08 0.10

Norbornane (C7H12) 0.02 0.02 0.01 0.02

1,3,5-cycloheptatriene (C7H8) 80.55 86.94 74.32 73.65

1,2-dimethylcyclohexane (C8H6) 2.95 0 0 0

1,3-dimethylcyclohexane (C8H16) 2.61 0.19 0.19 0.22

Isopropylcyclopentane (C8H16) 2.45 0.19 0.21 0.21

1-Methylcycloheptene (C8H14) 1.81 0.15 0.16 0.11

Pentyl cyclopentane (C10H20) 1.79 0.68 0 0

Ethylcyclohexane (C8H16) 2.50 0.48 0.60 0.62

Benzyloxy-phenol

(C6H5CH2OC6H4OH) 0.03 0 0 0

Butylcyclopentane (C9H18) 0 0 1.05 0

76

Table C2. Yield of by-products under xylose dehydration with CM-SO3H catalyst at

different reaction time, 155C and 50 wt.% catalyst loading

By-products Reaction time (h)

1 2 3

Air 0.04 0.05 0.04

Acetone (CH3)2CO 0.28 0.34 0.21

Benzene (C6H6) 0.15 0.12 0.14

Heptane (C7H14) 0.10 0.08 0.10

Norbornane (C7H12) 0.01 0.01 0.01

1,3,5-cycloheptatriene (C7H8) 77.98 74.32 73.8

1,2-dimethylcyclohexane (C8H6) 0 0 3.00

1,3-dimethylcyclohexane (C8H16) 0.22 0.19 2.56

Isopropylcyclopentane (C8H16) 0.22 0.21 2.57

1-Methylcycloheptene (C8H14) 0.14 0.16 2.02

Pentyl cyclopentane (C10H20) 0 0.68 0

Ethylcyclohexane (C8H16) 0.62 0.63 3.42

Butylcyclopentane (C9H18) 0 0 1.05

Table C3. Yield of by-products under xylose dehydration with CM-SO3H catalyst at

155C for 2h and diffent catalyst loading

By-products Catalyst loading (wt.%)

10 25 50

Air 0.05 0.05 0.05

Acetone (CH3)2CO 0.05 0.27 0.34

Benzene (C6H6) 0 0.01 0.12

77

Heptane (C7H14) 0.06 0.16 0.08

Norbornane (C7H12) 0.02 0.02 0.01

1,3,5-cycloheptatriene (C7H8) 86.54 62.96 74.32

1,3-dimethylcyclohexane (C8H16) 2.61 0.19 0.19

Isopropylcyclopentane (C8H16) 2.45 0.19 0.21

1-Methylcycloheptene (C8H14) 0 0 0.16

Undecane (CH3(CH2)9CH3) 0 0.11 0

Dodecan (CH3(CH2)10CH3) 0.10 0 0

Ethylbenzene 0.03 0.02 0.63

Benzophenone (C13H10O) 0.64 0.66 0

Table C4. Yield of by-products under xylose dehydration with P-C-SO3H catalyst at

155C for 2h and 25 wt.% catalyst loading

By-products Reusability of P-C-SO3H catalyst

Fresh 1st cycle 2nd cycle 3rd cycle

Air 0.05 0.05 0.05 0.04

Acetone (CH3)2CO 0.01 0 0.04 0.04

Benzene (C6H6) 0.01 0.01 0.01 0.01

Heptane (C7H14) 0.09 0 0.48 0.53

1,3,5-cycloheptatriene (C7H8) 26.77 42.01 65.97 69.76

1,2,4-Trimethylcyclopentane

(C8H16) 0.02 0.06 0.06 0.06

Dodecane (CH3(CH2)10CH3) 0.10 0 0.10 0.10

Ethylbenzene 0.03 0.64 0.64 0.03

Benzophenone (C13H10O) 0.66 0.01 0 0.64

78

Table C5. Chemical structure of by-products

By-products Molecular structure

Formic acid

Acetone (CH3)2CO

Benzene (C6H6)

Heptane (C7H14)

Norbornane (C7H12)

1,3,5-cycloheptatriene (C7H8)

1,2-dimethylcyclohexane (C8H16)

1,3-dimethylcyclohexane (C8H16)

1,2,4-Trimethylcyclopentane (C8H16)

Isopropylcyclopentane (C8H16)

1-Methylcycloheptene (C8H14)

Pentylcyclopentane (C10H20)

79

Ethylcyclohexane (C8H16)

Benzyloxy-phenol (C6H5CH2OC6H4OH)

Butylcyclopentane (C9H18)

Undecane (CH3(CH2)9CH3)

Dodecan (CH3(CH2)10CH3)

Ethylbenzene (C8H10)

Benzophenone (C13H10O)

80

BIOGRAPHY

Name Miss Thi Tuong Vi Tran

Date of Birth March 3rd, 1992

Citizenship: Vietnamese

Educational Attainment 2010 - 2014: Bachelor’s degree of Petrochemistry

Technology in Industrial University of HCM

City.

2014 - 2016: Master’s degree of Science and

Technology in Thammasat University.

Scholarship 2010: Industrial University of HCMC

2014-2016: AEC Scholarship from Thammasat

University.

Publications/ certifications

Tran, T. T. V.; Kaiprommarat, S.; Kongparakul, S.; Reubroycharoen, P.;

Guan, G.; Nguyen, M. H.; Samart, C., Green biodiesel production from waste cooking

oil using an environmentally benign acid catalyst. Waste Management (2016), 52, 367-

374.

ACS/CST BOOST Skills Workshop for Young Thai Scientists and

Engineers.

Quality Assurance and Accreditation ISC/IEC 17025 and ISO/IEC 17020

Awards

Best Student Paper Award for Oral Presentation in the 3rd Asian Conference

on Biomass Science (ACBS) on January 19th, 2016, Niigata, Japan.

Conferences proceedings

81

Poster presentation in topic: “Green Production of Carbon Microsphere by

Hydrothermal Carbonization of Xylose” in Paccon Conference 2015, January, 2015

Bangkok, Thailand.

Oral presentation in topic: “Green Production of Carbon Microsphere by

Hydrothermal Carbonization of Xylose” in Biotechnology International Congress (BIC

2015), September, 2015, BITEC, Bangkok, Thailand.

Oral presentation in topic: “Sulfonated Carbon Microsphere Catalyst for

Biodiesel Production from Waste Cooking Oil” in The AUN/SEED-NET Regional

Conference on Materials Engineering (RCME 2015), October, 2015 Bangkok,

Thailand.

Oral presentation in topic: “Cleaner Biodiesel Production from Waste

Cooking Oil using a Carbon Solid Acid Catalyst” in the 5th International Conference on

Green and Sustainable Innovation (ICGSI 2015), November, 2015, Pattaya, Thailand.

Oral presentation in topic: “Development Sulfonated Carbon Microsphere

for the Catalyst of Biodiesel Production” in The 3rd Asian Conference on Biomass

Science (ACBS 2016), January, 2016, Niigata, Japan.

Work experiences

Computer: AutoCAD, ChemOffice, CorelDraw (2D), ImageJ, Microsoft

Office, Peakfit, Visio.