Improvement of Furfural Production From Concentrated

Pre-Hydrolysis Liquor (PHL) of a Kraft-Based Hardwood

Dissolving Pulp Production Process

M. Sarwar Jahan

Pulp and Paper Research Division, BCSIR

Laboratories, Dhaka1

2

Kraft-based dissolving pulp process

Cooking

Chemicals

Dissolvin

g pulp

(Cellulose

)

Cooking

chemical

recovery

Dissolved

hemicelluloses,

lignin

Dissolved

organics +

Inorganics

Pre-

hydrolysis

Kraft

pulpingBleaching

Wood

chips

PHL (PRE-HYDROLYSIS LIQUOR)

- Lignin: 1 wt%

- Acetic acid: 1 wt%

- Sugars: 5 wt% (mostly C-5 sugars)

3

BIOREFINERY CONCEPT

4

In addition to dissolving pulp (cellulose), other

products including lignin, acetic acid, sugars and

their derivatives can be produced.

Therefore, the pre-hydrolysis kraft-based

dissolving pulp production process fit well into

the forest biorefinery concept.

PHL: a potential feedstock for furfural production

Xylose/xylan is the dominant hemicelluloses in the

PHL of the hardwood dissolving pulp mill, but the

concentration of sugars are low.

Nanofiltration (NF) can be used to concentrate the

sugars in the PHL to be used for furfural production.

Presence of acetic acid in the PHL can be a source of

catalyst for furfural production.

Turning wastes to useful products, another revenue

source for the dissolving pulp mill 5

Furfural

6

Nylon 6.6

Resin

Pharmaceutical

industryPetroleum

industry

Traditional furfural production

Catalysts: H2SO4 , HCl

Feedstocks: solid agricultural, forest wastes

Corncobs Saw dust straw

7

Temperature (℃)residence

time

Xylose

concentration in

PHL (%)

Furfural

yield (%)

150 20 10.69 2.51

190 20 10.69 7.75

150 100 10.69 7.87

190 100 10.69 1.38

150 60 3.52 1.11

190 60 3.52 28.56

150 60 17.5 2.19

190 60 17.5 0.501

170 20 3.52 15.05

170 100 3.52 32.81

170 20 17.5 2.61

170 100 17.5 2.20

170 60 10.69 10.95

Optimization of furfural production from PHL

An increase in xylose concentration in the PHL decrease in

furfural yield

8

Addition of H2SO4 increased furfural yield.

Temperatu

re (℃)

residence

time (min)

C-5 sugars

concentration

in PHL (%)

H2SO4

added

(%)

Furfural

yield (%)

Sugar

conversion

(%)

Acetic acid

concentration

(g/L)

170 100 3.5 / 32.8 77.0 15.4

170 100 3.5 0.4 48.4 86.2 14.2

170 100 10.7 / 6.4 95.5 28.5

170 100 10.7 0.4 7.8 93.3 28.4

170 100 17.5 / 2.2 95.2 45.6

170 100 17.5 0.4 2.3 92.9 43.9

190 100 17.5 / 1.6 99.9 36.8

190 60 10.7 0.4 5.5 99.7 40.1

190 60 10.7 1 6.6 99.7 31.3

Addition of sulfuric acid to improve furfural

formation

9

X F D

Side

reactions

r1 r2

r3

Kinetics

Parallel kinetic model explains the furfural

formation process well for the PHL system10

11

Furfural yield and C-5 sugar conversion

PHL (11.1%) vs Xylose (10.7%)

Furfural yield from PHL is much lower than that from xylose

0

20

40

60

80

100

120

0 50 100 150 200

Fu

rfu

ral

yie

ld (

%)/

C-5

su

gar

co

nvers

ion

(%

)

Time (min)

Furfural-Xylose

Furfural-PHL

Sugar-Xylose

Sugar-PHL

Side reactions: with lignin.

Side reactions: with furfural, e. g. resinification.

Condensation: furfural with sugars or degradation products.

degradation

products

Possible side reactions associated with furfural in the PHL

system (H. Liu, et al., Bior, Techn., 2013,131:315-320.)

Side reactions

12

DECREASING SIDE REACTIONS AT A HIGH CONC. PHL

13

Continuous

removal as

generated

Removal by

resin

Removal by AC

(activated carbon)lignin

HAc

furfural

reduces side reactions (condensation et al.)

improves the performance of the

subsequent nano- filtration

recovers acetic acid

reduces side reactions

improves furfural yield

INTEGRATED PROCESS OF ACTIVATED CARBON(AC)

ADSORPTION, RESIN TREATMENT, AND SUGAR

CONCENTRATION/UTILIZATION

14

furfural or

xylitol

PHLAC

treated

PHL

Filter

cake

Regenerated AC

Filter

cake

Acetic acid

AC/ Resin-

treated PHL

Lignin

AC adsorption IER treatment filtration

Sugar

concentration/

membranefiltration

Regenerated

resin

Regeneration

of AC

Resin

Regeneration

CHARACTERIZATION OF PHL AND AC/RESIN

TREATED PHL

15

Compositions PHL

AC/ resin treated

PHL

Total sugar, % 4.91 4.14

Pentose % 3.52 2.91

Hexose % 1.39 1.23

Lignin, % 0.87 0.13

Acetic acid, % 1.04 0.46

Furfural, % 0.15 0.06

NANOFILTRATION FOR CONCENTRATING SUGARS OF

PHL

16

2.2

2.3

2.3

2.4

2.4

2.5

2.5

2.6

Monomeric sugarOligomeric sugar Total sugar

C/C

0

Fig. The C/C0 value of Concentration of sugars in concentrate and feedstock PHL (VRF

is 2.53, pressure is 600 psi)

The oligomeric sugars concentration was 2.52 times to that of the

feedstock PHL, while the monomeric sugars concentration was 2.34.

The concentration of total sugars after NF was 11.2%.

P

1. Autoclave 2. Blender 3. Liquid bleed valve 4. Pressure gage

5. Control box 6. Vapor bleed valve 7. Thermocouple

8. condenser 9. Cylinder

1

5

2

34

6

7

8

9

Steam Stripping for FurfuralProduction

17

FURFURAL, ACETIC ACID AND FORMIC ACID FROM

TREATED PHL (WITH CONTINUOUS PRODUCT REMOVAL)

18

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0 10 20 30 40 50

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0 furfural yield

furfural concentration

acetic acid concentration

formic acid concentration

conc

entr

atio

n (g

/L)

time (min)

furfural yield (%)

Development of the furfural, acetic acid and formic acid conc. in the

condensate and furfural yield (180 ºC, 11.2% sugar PHL)

CONCLUSIONS

The integrated process of activated carbon adsorption,

IER adsorption and membrane filtration is a good

example of recovering lignin, acetic acid, and utilizing

sugars in the PHL

The lower furfural yield in a concentrated PHL was due

to side reactions (carbonization, condensation with

lignin/sugar, resinification, et al.)

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CONCLUSIONS

20

Removal of lignin by AC adsorption and

continuous removal of generated furfural can

minimize the side reactions. A furfural yield of

41.8% was obtained for the concentrated PHL.

ACKNOWLEDGEMENT

21

THANK YOU

22