Post on 28-Aug-2020
Alexey Kirilin
Aqueous-phase reforming − a pathway to
chemicals and fuels
Laboratory of Industrial Chemistry and Reaction Engineering Process Chemistry Centre
Åbo Akademi
POKE meeting, 14-th of August, 2014
Agenda
Short Introduction, biomass, what is APR?
Main tasks of the doctoral research
Experimental methods
Choice of catalytic systems
Catalytic results
Summary
2
POKE meeting, 14-th of August, 2014
Introduction - Biomass
POKE meeting, 14-th of August, 2014
3
Cellulose
Hemicellulose
Aldoses
Sugar alcohols
Hydrogenation
Fuels
Lubricants
Esterification Chemicals
Hydrolysis Oxidation
Sugar acids
Oligomers
Hydrolysis Catalytic transformation of biomass
Aqueous reforming
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POKE meeting, 14-th of August, 2014
Aqueous phase reforming (APR)
Biomass
RR=11/5
5
POKE meeting, 14-th of August, 2014
Biomass
RR=11/5
Aqueous phase reforming (APR) 5
POKE meeting, 14-th of August, 2014
• Task 1. Investigation of reaction products and intermediates
• Task 2. Synthesis and characterization of catalysts
• Task 3. Catalyst stability studies
• Task 4. Investigation of reactant structure on process properties
• Task 5. Influence of a second metal (Re)
• Task 6. Modelling of reaction kinetics
The main tasks of the research 6
POKE meeting, 14-th of August, 2014
Reaction conditions:
• 0.5 g of a catalyst
• 225°C
• 30 bar
• Carrier gas N2 (30 ml/min)
Experimental setup
Continuous fixed-bed reactor
10 wt.% of xylitol used as a feed
Reagents in the liquid phase
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POKE meeting, 14-th of August, 2014
N2 (1% He)
mass flow controller furnace
sampling
GC
P effluent
pressure controller
safety valve
MFC
catalyst
MFC
MFC
collector
HPLC pump
H2 (for reduction)
Reactor’s scheme 8
POKE meeting, 14-th of August, 2014
APR of Polyols
Gas phase Liquid phase
Micro-GC HPLC TOC
TOC – total organic carbon analysis
Mass balance – 95-100% (by carbon analysis)
On-line sampling
Product analysis
Volatile compounds were identified by means of Solid-phase microextraction (SPME) + GC-MS
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POKE meeting, 14-th of August, 2014
G
L
H2, CO2, alkanes
Oxygenates
100%
• Catalyst activity, stability and selectivity to H2
• Product distribution between phases
• Ratio H2/CO2
Important parameters in APR
Selectivity to H2 (%) = %100/1)(
)( 2 RRCv
Hv
gasin
RR – reforming H2/CO2 ratio
(11/5 fo xylitol)
POKE meeting, 14-th of August, 2014
10
Ni
Ru
Pd
Pt
Al2O3
TiO2
C
MgO
Based on catalytic activity in the APR of ethylene glycol
Choice of active metal and support 11
POKE meeting, 14-th of August, 2014
Pt/Al2O3, Pt/TiO2, Pt/C and bimetallic catalyst PtRe/TiO2
Ni
Ru
Pd
Pt
Al2O3
TiO2
C
MgO
Based on catalytic activity in the APR of ethylene glycol
Choice of active metal and support
C-C cleavage
WGS activity
11
POKE meeting, 14-th of August, 2014
0 30 60 90 120
1.0
1.2
1.4
1.6
1.8
Bil
dnin
gsh
asti
ghet
[x104],
mol/
min
Time on stream, h
Time. h CO2[104]. mol ∑(X∙CxHy)[10
5]. mol ∑CxHy/CO2
7 1.7 6.9 0.4
123 1.6 6.4 0.4
Catalyst showed stable performance within more than 120 h time on stream
Catalyst stability
Fo
rma
tio
n r
ate
[x1
04],
mo
l/m
in
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POKE meeting, 14-th of August, 2014
0.5 1.0 1.5 2.0 2.5 3.0
0
20
40
60
80
100Liquid
Car
bo
n c
on
ten
t, %
MVKV, t-1
Gas
G
L
H2, CO2, alkanes
Oxygenates
100%
Distribution of carbon
WHSV, h-1 WHSV – weight hourly space velocity
gsubs/gcat/hour [h–1]
benchmark catalyst – Pt/Al2O3
13
POKE meeting, 14-th of August, 2014
0.5 1.0 1.5 2.0 2.5 3.0
0
20
40
60
80
100Liquid
Car
bo
n c
on
ten
t, %
WHSV, h-1
Gas
G
L
H2, CO2, alkanes
Oxygenates
100%
Distribution of carbon
WHSV, h-1 WHSV – weight hourly space velocity
gsubs/gcat/hour [h–1]
benchmark catalyst – Pt/Al2O3
13
POKE meeting, 14-th of August, 2014
0.5 1.0 1.5 2.0 2.5 3.0
0
20
40
60
80
100Liquid
Car
bo
n c
on
ten
t, %
WHSV, h-1
Gas
WHSV – weight hourly space velocity
gsubs/gcat/hour [h–1]
G
L
H2, CO2, alkanes
Oxygenates
100%
Distribution of carbon
WHSV, h-1 WHSV, h-1
benchmark catalyst – Pt/Al2O3
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POKE meeting, 14-th of August, 2014
0 1 2 30
15
30
45
60
CO2
H2
Yie
ld, %
WHSV, h-1
0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0propane
MKMV, t-1
Yie
ld, %
СО
n-butane
etane
0.5 1.0 1.5 2.0 2.5 3.00.00
0.05
0.10
0.15
0.20
0.25
WHSV, h-1
iso-butanen-hexaneY
ield
, %
n-pentane
Gas phase composition
Studied by micro-GC and GC-MS, benchmark catalyst – Pt/Al2O3
WHSV, h-1 WHSV, h-1
WHSV, h-1
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POKE meeting, 14-th of August, 2014
Carbon in liquid. %
Product distribution. % Total amount
detected. % Alcohols Diols
Triols
Ketons
Acids
Other
24.4 17.3 49.9 4.2 5.0 4.9 18.7 90.6
изосорбид isosorbid
Liquid phase Studied by HPLC and SPME
benchmark catalyst – Pt/Al2O3
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POKE meeting, 14-th of August, 2014
Higher selectivity to alkanes at lower
space velocities
Higher yields of hydrogen for xylitol – substrate
with shorter carbon chain
Conditions: 225°С, 30 atm., N2 30 ml/min, 10 wt.% solution, Pt/Al2O3
Influence of reactant structure
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
5
10
15
20
25
30
WHSV, h-1
Reforming of sorbitol
Alk
ane
sele
ctiv
ity, %
Reforming of xyltiol
1.0 1.5 2.0 2.5 3.0 3.5 4.0
10
15
20
25
30
Reforming of sorbitol
Yie
ld o
f H
2,
%
WHSV, h-1
Reforming of xyltiol
16
POKE meeting, 14-th of August, 2014
Higher selectivity to alkanes at lower
space velocities
Higher yields of hydrogen for xylitol – substrate
with shorter carbon chain
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
5
10
15
20
25
30
WHSV, h-1
Reforming of sorbitol
Alk
ane
sele
ctiv
ity, %
Reforming of xyltiol
1.0 1.5 2.0 2.5 3.0 3.5 4.0
10
15
20
25
30
Reforming of sorbitol
Yie
ld o
f H
2,
%
WHSV, h-1
Reforming of xyltiol
Influence of reactant structure
Conditions: 225°С, 30 atm., N2 30 ml/min, 10 wt.% solution, Pt/Al2O3
16
POKE meeting, 14-th of August, 2014
Higher selectivity to alkanes at lower
space velocities
Higher yields of hydrogen for xylitol – substrate
with shorter carbon chain
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
5
10
15
20
25
30
WHSV, h-1
Reforming of sorbitol
Alk
ane
sele
ctiv
ity, %
Reforming of xyltiol
1.0 1.5 2.0 2.5 3.0 3.5 4.0
10
15
20
25
30
Reforming of sorbitol
Yie
ld o
f H
2,
%
WHSV, h-1
Reforming of xyltiol
Influence of reactant structure
Conditions: 225°С, 30 atm., N2 30 ml/min, 10 wt.% solution, Pt/Al2O3
16
POKE meeting, 14-th of August, 2014
xylitol
xylitol
Catalysts
one commercial Pt/C (Degussa) four prepared and characterized materials
5% Pt/C (Degussa)
2.5% Pt/TiC-CDC (CDC – carbide-derived carbon)
5% Pt/Sibunit from (NH3)4 Pt (HCO3)2
5% Pt/Sibunit H2PtCl6
5% Pt/BAC (Birch active carbon)
Pt/TiO2,
Pt-Re/TiO2
Re/TiO2
2. Effect of a support material and support structure
1. Effect of a second metal: series
Prepared by incipient wetness impregnation, from
HReO4 and or (NH3)4Pt(NO3)2
17
POKE meeting, 14-th of August, 2014
Catalysts
one commercial Pt/C (Degussa) four prepared and characterized materials
5% Pt/C (Degussa)
2.5% Pt/TiC-CDC (CDC – carbide-derived carbon)
5% Pt/Sibunit from (NH3)4 Pt (HCO3)2
5% Pt/Sibunit H2PtCl6
5% Pt/BAC (Birch active carbon)
Pt/TiO2,
Pt-Re/TiO2
Re/TiO2
2. Effect of a support material and support structure
1. Effect of a second metal: series
To enhance selectivity to hydrocarbons
17
POKE meeting, 14-th of August, 2014
Higher selectivity to alkanes in the
presence of bimetallic Pt-Re catalyst
Higher yields of hydrogen
for monometallic Pt catalyst
1 2 3 4 5 6
5
10
15
20
25
30
35
Pt/TiO2
Yie
ld o
f H
2, %
WHSV, h-1
Pt-Re/TiO2
Pt/Al2O
3
In cooperation with prof. C. Hardacre from Queen’s University, Belfast
Conditions: 225°С, 30 atm., N2 30 ml/min, 10 wt.% solution
Example: APR of xylitol over Pt-Re/TiO2 18
POKE meeting, 14-th of August, 2014
Slightly higher selectivity to alkanes in the
presence of bimetallic Pt-Re catalyst
Higher yields of hydrogen
for monometallic Pt catalyst
1 2 3 4 5 6
5
10
15
20
25
30
35
Pt/TiO2
Yie
ld o
f H
2, %
WHSV, h-1
Pt-Re/TiO2
Pt/Al2O
3
1 2 3 4 5 6
5
10
15
20
25
30
35
Pt/TiO2
Sele
cti
vit
y t
o a
lkan
es,
%
WHSV, h-1
Pt/Al2O
3
Pt-Re/TiO2
Example: APR of xylitol over Pt-Re/TiO2
In cooperation with prof. C. Hardacre from Queen’s University, Belfast
19
Conditions: 225°С, 30 atm., N2 30 ml/min, 10 wt.% solution
POKE meeting, 14-th of August, 2014
2 4 6 8 10 12 14 16
0
5
10
15
20
Pt/BAC
d, nm
Fre
que
ncy, %
Transmission electron microscopy
300 350 400 450 500
0.0
0.1
0.2
0.3
0.4
0.5
0.6
379 K
386 K
370 K
358 K
20 Kmin-1
15 Kmin-1
5 Kmin-1
10 Kmin-1
3 Kmin-1
349 K
Conce
ntr
atio
n o
f N
H3, %
Temperature, K
0 50 100 150 200 250 300 350 400 450
180°C
350°C
Upta
ke o
f H
2, a.u
.
Temperature, °C
75°C
Particle size distribution
Temperature programmed reduction (H2) Temperature programmed desorption (NH3)
~2 nm
20 nm
Pt/Al2O3 Pt/Al2O3
Pt/BAC
Characterization 20
POKE meeting, 14-th of August, 2014
Effect of acidity
APR of xylitol over Pt/C
In cooperation with prof. B. Etzold from University of Erlangen-Nürnberg
0 20 40 60 80 100 120 140 160
0.4
0.6
0.8
1.0
1.2
1.4
1.6
NH3 desorbed, molg
Rate
of
alk
an
es
fo
rma
tio
n [
x10
5],
mo
lm
in-1
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
H2/C
O2
Supervised visiting PhD student Benjamine Hasse for 2 months
21
POKE meeting, 14-th of August, 2014
Effect of acidity
APR of xylitol over Pt/C
In cooperation with prof. B. Etzold from University of Erlangen-Nürnberg
0 20 40 60 80 100 120 140 160
0.4
0.6
0.8
1.0
1.2
1.4
1.6
NH3 desorbed, molg
Rate
of
alk
an
es
fo
rma
tio
n [
x10
5],
mo
lm
in-1
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
H2/C
O2
Supervised visiting PhD student Benjamine Hasse for 2 months
21
POKE meeting, 14-th of August, 2014
Effect of acidity
APR of xylitol over Pt/C
In cooperation with prof. B. Etzold from University of Erlangen-Nürnberg
0 20 40 60 80 100 120 140 160
0.4
0.6
0.8
1.0
1.2
1.4
1.6
NH3 desorbed, molg
Rate
of
alk
an
es
fo
rma
tio
n [
x10
5],
mo
lm
in-1
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
H2/C
O2
Supervised visiting PhD student Benjamine Hasse for 2 months
21
POKE meeting, 14-th of August, 2014
Reaction pathways Based on experimental data 22
POKE meeting, 14-th of August, 2014
Reaction pathways Based on experimental data
Pathway to hydrogen
22
POKE meeting, 14-th of August, 2014
Pathway to hydrogen
Reaction pathways Based on experimental data 22
POKE meeting, 14-th of August, 2014
Pathway to alkanes
Reaction pathways Based on experimental data 22
POKE meeting, 14-th of August, 2014
Reaction pathways Based on experimental data
Pathway to alkanes
22
POKE meeting, 14-th of August, 2014
Reaction pathways Based on experimental data
Pathway to hydrogen
Pathway to alkanes
A.V. Kirilin, J. Wärnå, T. Salmi, D. Yu. Murzin, “Kinetic Modeling of Sorbitol Aqueous-Phase
Reforming over Pt/Al2O3”, Ind. Eng. Chem. Res., 2014, 53, 4580–4588
Modelling of kinetics was performed at ÅA
22
Modeling
Two main pathways are selected
23
Modeling 24
eff
obs
cD
Rr 2
Weisz-Prater modulus for 1-st order reaction Φ < 1,
for 0 order reaction Φ < 6
for 2 order reaction Φ < 0.3
robs — maximal initial reaction rate
R — mean radius of the catalyst particle
c —substrate concentration.
In our case R = 1.25×10-4 m (125 µm)
DDef 6.0
)(
218 )(104.7
AbB
BAB
o
V
TMD
effective diffusion coefficient (Deff) of substrate
(sorbitol) in water
porosity (0.3-0.6)
tortuosity (2-5)
Wilke-Chang:
[cm2/s]
= 2.6 (water), MB is molecular weight of solvent, B = 0.11888 cP is solvent
dynamic viscosity, T (K) = 498K, P=30 bar), Vb(A) = 122.15 cm3×mol-1 is liquid molar
volume at solute’s normal boiling point.
Assuming / = 1/10 the diffusion coefficient of sorbitol is calculated to be Def
=1.1810-9 m2/s (498 K and 30 bar).
The concentration of the substrate in the solvent is equal to 0.515 mol×l-1.
rmax= 1.93×10-4 mol×l-1×s-1 at 2.7 h-1
Φ=0.005 substrate diffusion inside the catalyst pores does not affect the reaction
rate
Modeling 25
N(1)
: COHHOCHOC 212551466
N(2)
: COHHOCHOC 210441255
N(3)
: COHHOCHOC 28331044
N(4)
: COHHOCHOC 2622833
N(5)
: 222 HCOOHCO
N(6)
: OHHCHHOC 210421044 44
N(7)
: OHHCHHOC 2832833 33
N(8)
: OHHCHHOC 2622622 22
Reaction pathways
P=S+W-I, where S is the number of steps, W is the number of balance (link)
equations, and I is the number of intermediates
P=17+2-11=8 basic routes (no intermediates are there)
D. Murzin & J. Wärnå
26
VHOCHOC CK 14661466 1 VHOCHOC CK
12551255 3 and so on for each component
''10441044 12 VHOCHOC CK
on metal sites:
on acid sites:
OHHOCHOCHOCHOCHOC
VCKCKCKCKCKCK
2622833104412551466 10975311
1
6228331044 1614121
1'
HOCHOCHOC
VCKCKCK
OHHOCHOCHOCHOCHOC
HOC
VHOCHOC
CKCKCKCKCKCK
CKk
CKkkr
2622833104412551466
1466
14661466
1097531
12
122
)1(
1
)1(1466 rd
dC HOC
Total coverage:
Rate for basic route 1:
Generation rate for compound:
D. Murzin & J. Wärnå
27
OHHOCHOCHOCHOCHOC
HOC
VHOCHOC
CKCKCKCKCKCK
CKk
CKkkr
2622833104412551466
1466
14661466
1097531
12
122
)1(
1
1466
'
2
)1(
HOCCkr
Simplification of the model because
of overparametrization
83318
)9( ' HOCCkr
)9()1(1466 rrd
dC HOC
...
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.40
0.5
1
1.5
2
2.5
3
3.5x 10
-4
WHSVh
C6O
H
Modeling
D. Murzin & J. Wärnå
97%
28
Summary
1. Aqueous-phase reforming of two most abundant polyols has been studied over stable catalysts
2. Effect of reactants structure on selectivity to main product formation reveals that higher
selectivities to hydrogen can be achieved in APR of xyltiol compared to sorbitol (up to 85%)
3. Addition of Re as a second metal component leads to enhanced alkane formation
4. Advanced reaction scheme was proposed on the basis of experimental data
5. For the first time reaction sensitivity in APR of xylitol was studied over Pt/C
6. The reaction kinetics was modeled based on kinetic data and mechanistic considerations for
sorbitol transformation during APR.
29
POKE meeting, 14-th of August, 2014
APR is a powerfull method for hydrogen production from renewables
Kinetic model proposed can be further developed and applied to description of APR data for
other substrates as well as for APD/H process
Financial support
Graduate School in Chemical Engineering (GSCE, 2010-2013)
Fortum Foundation (2009-2011)
Academy of Finland in cooperation with North European Innovative Energy Research Programme (N-Inner, 2010-2013)
Haldor Topsøe Scholarship Programme (2010-2012)
COST–Action CM0903 (UbioChem, 2010-2013)
30
POKE meeting, 14-th of August, 2014
Alexey Kirilin
Aqueous-phase reforming − a pathway to
chemicals and fuels
Laboratory of Industrial Chemistry and Reaction Engineering Process Chemistry Centre
Åbo Akademi
POKE meeting, 14-th of August, 2014