in mild conditions
Els D’Hondt
COK, KULeuven, Belgium
Poitiers, March 13, 2008
?Introduction
–Use of 1,2-propanediol
–Results with better literature catalysts
–Bifunctional mechanism
?New bifunctional catalyst
–Reaction conditions & Results
–Overall conversion results
–Stability 1,2-propanediol
–Hydrogenation of hydroxy acetone
–Effect of gaseous products: CO
2and H
2
–Origin of acidity in bifunctional pathway
?Reaction pathways with new bifunctional catalyst –Extended scheme for the bifunctional mechanism
–Suggested reforming mechanism
?Conclusions
?Introduction
–Use of 1,2-propanediol
–Results with better literature catalysts
–Bifunctional mechanism
?New bifunctional catalyst
–Reaction conditions & Results
–Overall conversion results
–Stability 1,2-propanediol
–Hydrogenation of hydroxy acetone
–Effect of gaseous products: CO
2and H
2
–Origin of acidity in bifunctional pathway
?Reaction pathways with new bifunctional catalyst –Extended scheme for the bifunctional mechanism
–Suggested reforming mechanism
?Conclusions
Introduction:
Use of 1,2-propanediol
OH
OH
1,2-Propanediol = bulk intermediate
–direct use as moistering or softening agent, as anti-freeze, solvent or conservative
–monomer for polyesters, polyurethanes and alkyd resins
–preparation of cyclic ethers and 1,3-dioxanes used in organic synthesis as solvents or intermediates
Introduction: Results with better
literature heterogeneous catalysts ?One step processes
Catalyst T (°C)p H2 (bar)Results Reference
CuCr270200Y = 85 %Adkins et al., Journal of the American Chemical Society, 54: 1138-1145, (1932) Cu/ZnO18080S = 100 %, X = 19 %Gallezot et al., Green Chemistry, 6: 359-361, (2004)
Raney Cu24030Y = 57 %Montassier et al., Heterogeneous Catalysis and Fine Chemicals: 165-170, (1988) CuZnO/Al2O3270100Y = 84 %Casale et al., US Patent 5 214 219, (1993)
CoCuMnMo + H3PO4230250Y = 96 % Schuster et al., US Patent 5 616 817, (1997)
Ru/C21060Y = 75 %Montassier et al., Journal of Molecular Catalysis, 70 (1), 99-110, (1991)
RuS/C240130Y = 75 %Casale et al., US patent 5 276 181, (1994)
Y = yield, S = selectivity, X = conversion
?Multiple step processes
–Three step proces [1]
?γ-Al2O3 at 300 °C + acid resin+ Ni/Al2O3/SiO2at 140 °C and 40 bar H2
Y = 60 %
–Two step proces [2]
?CuCr at 220 °C + CuCr at 300 °C and 14 bar H2
Y = 62 %
Introduction:
Bifunctional mechanism
Glycerol conversion scheme via dual function catalyst *
OH
iso-propanol
O
propanal
OH
n-propanol
OH
OH
1,2-propanediol O
acetone
O
H OH
OH
glycerol
OH
O
hydroxy acetone
acid
dehydration
hydrogenation
11
dehydration
acid
2
hydrogenation 2
propane
hydrogenation
propene
3
3acid dehydration
or
or
+ H 2
+ H 2
+ H 2
Content ?Introduction
–Use of 1,2-propanediol
–Results with better literature catalysts
–Bifunctional mechanism
?New bifunctional catalyst
–Reaction conditions & Results
–Overall conversion results
–Stability 1,2-propanediol
–Hydrogenation of hydroxy acetone
–Effect of gaseous products: CO
2and H
2
–Origin of acidity in bifunctional pathway
?Reaction pathways with new bifunctional catalyst –Extended scheme for the bifunctional mechanism
–Suggested reforming mechanism
?Conclusions
Reaction conditions & Results
?Mild conditions, no additives, heterogeneous catalyst, inert atmosphere
–100 ml batch reactor –230 °C, 15 h
–40 ml 20 wt% glycerol in H 2O –
4 wt% catalyst
S 1,2-propanediol = 64 %X glycerol = 85 %Y 1,2-propanediol = 55 %MB liquid C =
89 %
O
H O H
O H
+ 3 H 2O
8
O H O H
7
+ 3 CO 2
new catalyst
glycerol
1,2-propanediol
in situ H 2production
S = selectivity, X = conversion, Y = yield, MB = carbon mass balance of liquid products
Overall conversion results
100 ml batch reactor, 230 °C, 24 h, 40 ml 20 wt% gl ycerol in H2O, 4 wt% catalyst, X = conversion, S = selectivity, mb = mass balance of liquid products, EtOH = ethanol, n-propOL = n-propanol, OH-AcON = hydroxy acetone
100 ml batch reactor, 230 °C, 15 h, 40 ml 20 wt% gl ycerol
in H 2O, 4 wt% catalyst, Yield based on mol/L
Selectivities and
MB liquid products rather constant
after initial period
P roduct
C arbon S electivity (%)
Y ield (%)methanol
0,9
2,4ethanol
9,512,2acetone + propanal 1,00,9iso-propanol 1,41,2n-propanol 7,56,4ethylene glycol 2,12,6hydroxy-acetone 3,02,61,2-propanediol 64,054,6
conversion (%)
85,4carbon mass balance of liquid products (%)
89,4
05
10
15
20
5
10
15
20
25
t (h)
S s i d e p r o d u c t s (%)
S E tOH
S n-propOL
S OH-A cON ±Plateau S
0204060801000
5
10
15
2025
t (h)X , S P D O , m b (%) .X
S 1,2-propanediol
mb
Stability of 1,2-propanediol
0510*******
5
10
15
20
25
t (h)c o n v e r s i o n , S s i d e p r o d u c t s (%)S ethanol
S n-propanol S hydroxy acetone conversion
?Via bifunctional pathway to n-propanol
?Via dehydrogenation and cracking to ethanol and CO
OH OH
O
OH
H +-H 2O
redox + H 2
redox OH
O
O
OH
OH + CO
OH OH
redox
-H 2
P roduct
C arbon S electivity (%)
ethanol
40,5
acetone + propanal 1,3iso-propanol 5,7n-propanol
18,6hydroxy-acetone 4,7conversion (%)
24,7carbon mass balance of liquid products (%)
70,7
Hydrogenation of hydroxy acetone
?
Equimolar amount of H 2
and hydroxy acetone
–Fast hydrogenation
–Low selectivity for CO, CO 2and CH 4–Enhanced selectivity for propane
no H 242 bar H 2methanol 0,00,0ethanol
5,01,4acetone + propanal 2,60,4iso-propanol 0,31,0n-propanol 2,01,8ethylene glycol 0,00,01,2-propanediol 65,691,3conversion (%)
77,998,7C arbon S electivity (%)P roduct carbon mass balance of liquid products (%)
75,4
95,9
OH
O
O
OH
OH + CO
redox
OH OH
O
O
or
OH or
OH
H +-H 2O
redox + H 2
redox + H 2
H +
-H 2O
Fast hydrogenation
or
cracking into ethanol and CO
Effect of gaseous products
P roduct no H2
24 h
5 bar C O2
24 h
20 bar C O2
24 h
5 bar H2
24 h
42 bar H2
72 h
methanol0,90,80,70,91,2 ethanol10,612,212,39,66,7 acetone + propanal0,91,02,20,50,2 iso-propanol1,91,90,01,31,4 n-propanol8,98,210,57,18,0 ethylene glycol1,00,80,42,02,0 hydroxy-acetone2,02,42,42,01,0 1,2-propanediol45,843,734,450,776,8 conversion (%)100,099,799,296,3100,0
carbon mass balance of liquid products (%)72,071,062,974,097,4
C arbon S electivity (%)
Effect of gaseous products
P roduct no H2
24 h
5 bar C O2
24 h
20 bar C O2
24 h
5 bar H2
24 h
42 bar H2
72 h
methanol0,90,80,70,91,2 ethanol10,612,212,39,66,7 acetone + propanal0,91,02,20,50,2 iso-propanol1,91,90,01,31,4 n-propanol8,98,210,57,18,0 ethylene glycol1,00,80,42,02,0 hydroxy-acetone2,02,42,42,01,0 1,2-propanediol45,843,734,450,776,8 conversion (%)100,099,799,296,3100,0
carbon mass balance of liquid products (%)72,071,062,974,097,4
C arbon S electivity (%)
?Equimolar amount of H
2
and glycerol –Decreased activity
72 h for full conversion Inhibition reforming
Increased S
1,2-propanediol 77 %
Increased MB
liquid C
97 %
Effect of gaseous products
? 5 bar CO 2: No effect
?
20 bar CO 2: Increased activity
–Decreased 1,2-propanediol selectivity
–Decreased carbon mass balance liquid products
P roduct
no H 2 24 h 5 bar C O 2 24 h 20 bar C O 2 24 h 5 bar H 2 24 h 42 bar H 2 72 h methanol 0,90,80,70,91,2ethanol
10,612,212,39,66,7acetone + propanal 0,91,02,20,50,2iso-propanol 1,91,90,01,31,4n-propanol 8,98,210,57,18,0ethylene glycol 1,00,80,42,02,0hydroxy-acetone 2,02,42,42,01,01,2-propanediol 45,843,734,450,776,8conversion (%)
100,099,799,296,3100,0carbon mass balance of liquid products (%)
72,0
71,0
62,9
74,0
97,4
C arbon S electivity (%)
Consecutive reactions
CO 2+ H 2O H 2CO 3
Origin of acidity in bifunctional mechanism
?
20 bar CO 2as acid catalyst, no catalyst
?Only the metal as catalyst, no carrier
010*********
1
2345678
t (h)X , S e t h a n o l , S h y r o x y a c e t o n e (%)
S ethanol S hydroxy acetone X
100 ml batch reactor, 230 °C, 7 h, 40 ml 20 wt% gly cerol
in H 2O, 20 bars CO 2 , X = conversion, S = selectivity
20
40608010005101520
25t (h)X , S , Y , m b (%)X no carrie r S P D O no carrie r mb no carrie r X
S P D O
mb
0510152025303540450
5
10
15
20
25
t (h)S s i d e p r o d u c t s (%)S n-propO L no carrie r
S O H -A cO N no carrie r
S n-propO L
S O H -A cO N
100 ml batch reactor, 230 °C, 24 h, 40 ml 20 wt% gl ycerol in H 2O, 0,26 mmol metal (…) or patented catalyst (―),X = conversion, S = selectivity, Y = yield, mb = carbon mass balance of liquid products, PDO = 1,2-propanediol, n-propOL = n-propanol, OH-AcON = hydroxy acetone
–Low conversion –Higher S side products –High MB liquids
CO 2as
acid catalyst
–Hydroxy acetone is formed in presence of 20 bar CO 2
–Versus thermostability of glycerol (X = 0 %) without catalyst
Content ?Introduction
–Use of 1,2-propanediol
–Results with better literature catalysts
–Bifunctional mechanism
?New bifunctional catalyst
–Reaction conditions & Results
–Overall conversion results
–Stability 1,2-propanediol
–Hydrogenation of hydroxy acetone
–Effect of gaseous products: CO
2and H
2
–Origin of acidity in bifunctional pathway
?Reaction pathways with new bifunctional catalyst –Extended scheme for the bifunctional mechanism
–Suggested reforming mechanism
?Conclusions
Bifunctional mechanism:
Extended scheme
propane
OH
iso-propanol
O
propanal OH
n-propanol
OH
ethanol OH OH
1,2-propanediol O
acetone
O
H OH
OH
glycerol OH
O
hydroxy acetone
O
OH
2-hydroxy propanal acid dehydration
isomerisation
ethane
+ CO
isomerisation
isomerisation
ethene
hydrogenation
hydrogenation
hydrogenation
propene
acid
dehydration
dehydration
acid
dehydration
acid
hydrogenation
C-CO cracking
1
1
22
3
3
Suggested reforming mechanism:
Based on experimental data
O
H OH
ethylene glycol
O
H OH
OH
glycerol
methanol
H
H
OH
H
O
OH
O
H glyceraldehyde O H OH
O
dihydroxy acetone
O
H H
O
hydroxy ethanal H
H
O formaldehyde
+ CO + H 2
+ H 2H 2+
+ CO + H 2
CO + H 2
(de)hydrogenation
redox
(de)hydrogenation
(de)hydrogenation
redox
redox
Equilibrated via water gas shift reaction:CO + H 2O CO 2+ H 2
Content ?Introduction
–Use of 1,2-propanediol
–Results with better literature catalysts
–Bifunctional mechanism
?New bifunctional catalyst
–Reaction conditions & Results
–Overall conversion results
–Stability 1,2-propanediol
–Hydrogenation of hydroxy acetone
–Effect of gaseous products: CO
2and H
2
–Origin of acidity in bifunctional pathway
?Reaction pathways with new bifunctional catalyst –Extended scheme for the bifunctional mechanism
–Suggested reforming mechanism
?Conclusions
Conclusions
C 3H 8O 3 3 CO + 4 H 2
8 C 3H 8O 3+ 3 H 2O 7 C 3H 8O 2+ 3 CO 2
3 CO + 3 H 2O 3 CO 2+ 3 H 27 C 3H 8O 3+ 7 H 2 7 C 3H 8O 2
X glycerol = 85 %
S 1,2-propanediol = 64 %MB liquid C = 89 %
?
Characteristics of the proces
–in situ H 2production: reforming + water gas shift reaction
Inhibition reforming by biogenic H 2 pressure
?Specific carrier
–Good stability of 1,2-propanediol Affinity glycerol > affinity 1,2-propanediol
–Fine tuned acidity
Minor consecutive reactions
–Quenching carbon acid acidity –Isomerisation
Provides more substrates for reforming