Renewable Chemicals: Dehydroxylation
of Glycerol and Polyols
DOI 10.1002/cssc.201100162
Arundhathi RACHA
Department of Materials Engineering Science,
Graduate School of Engineering Science,
Toyonaka, Osaka University- Osaka 560-8531,
Japan
Renewable Chemicals: Dehydroxylation of Glycerol and Polyols
(Jeroen ten Dam and Ulf Hanefeld)
(ChemSusChem 2011,4,1017-1034; DOI 10.1002/cssc.201100162)
 Renewable chemicals from natural
resources e.g, sugars, cellulose and
hemicellulose in a sustainable way.
 Dehydroxylation, a fundamentally
different approach of defunctioanlize
of hydroxyl groups to yield
renewable chemicals.
Defunctionalizing of biomass vs. functionalizing of oil
 Design of catalysts that can selectively remove some of the functionalities .
 Selective conversion of polyols, i.e dehydration and hydrogenation.
Selective dehydroxylation of Biomass
Six approaches for deoxgenation
1. Dehydration of vicinal diols and hydrogenation of carbonyl groups
2. Dehydration of alcohols and hydrogenation of carbon–carbon double bonds
3. Condensation of alcohols and hydrogenolysis of the resulting cyclic ethers
4. Hydrogenolysis of ethers
5. Ketonization of carboxylic acids
6. Hydrogenation of carboxylic acids
Selective dehydroxylation of polyols
Acid-catalyzed E1 mechanism
Base-catalyzed E2 mechanism
Hydrogenolysis
 Sequential elimination (dehydration) and hydrogenation process.
 Endothermic (dehydration) versus exothermic (hydrogenation) –product
selectivity.
 Need for design the catalyst which directs the overall process to occur via one
specific dehydration pathway.
Dehydration -Hydrogenation
Dehydration selectivity determining the value-added chemicals from
glycerol
 Bronsted acid assist in eliminating secondary hydroxyl group
 Lewis acid assist in eliminating primary hydroxyl group
Dehydration of alcohols and hydrogenation of carbon–carbon double
bonds
Condensation of alcohols and hydrogenolysis of the resulting cyclic
ethers
The reaction sequence is not applicable to glycerol, since the condensation of
alcohols in order to form cyclic ethers is limited to five-membered (or larger) ring
systems.
Glycerol to 1,2-propanediol
 Under alkaline conditions, 12PD is being formed via glyceraldehyde
Under acidic conditions, acetol is generally is the key intermediate
!,2-propanediol from Glycerol
Glycerol to 1,3-propanediol
 Selective production of 13PD is more challenging than 12PD
 Active catalyst for 12PD production, selective catalyst for 13PD production
The factors that are important to influence 13PD formation are slowly being
unraveled
Effect of impregnated metals and solvent on WO3/ZrO2
support for 13-PD selectivity
 Protic solvent improves the reaction towards 13PD by facilitating proton
transfer from solid acid to secondary alcohol by stabilizing a charged
intermediate.
Additives improving the conversion and selctivity towards 13PD
Pt/WO3/ZrO2 facilitates the homolytic cleavage of hydrogen on platinum and
subsequent spillover
Tungsten additive for the improving Gly Conv and Selc towards 13PD
Fixed bed reactor
Pt/WO3/ZrO2
403 K
70% Conv.; 46% Selec.
(Quin et al.)
Pt/WO3/TiO2
(Gong et al.)
7.5% Conv.; 44% Selec.
Pt/WO3/TiO2/SiO2
(Gong et al.)
15% Conv.; 51% Selec.
Cu-STA/SiO2
70% Conv.; 46% Selec.
(Huang et al.)
Rhenium additive for the improving Gly Conv. and Selc. towards 13PD
Rh/SiO2
14.3% Conv.; 9.8% Selec.
(Furikado et al.)
Rh-ReOx/SiO2
79% Conv.; 14% Selec.
(Furikado et al.)
Ir-ReOx/SiO2
50% Conv.; 49% Selec.
(Furikado et al.)
Pt-Re/C
20% Conv.; 34% Selec.
(Daniel et al.)
Pt-Re/C
(Tomishige et al.)
45% Conv.; 29% Selec.
Glycerol to acrolein
Glycerol to Lactic acid
Glycerol to Acrylonitrile
Glycerol to Epichlorohydrin
Glycerol to Ethylene glycol
Longer Chain polyols
5-Hydroxymethylfurfural (HMF formation form D-Glucose)
Conclusions
1. The smallest polyol Glycerol can be deoxygenated into a range of useful
chemicals .
2. Major deoxygenation products from Glycerol are 12PD, 13PD and acrolein.
3. The catalyst for acrolein formation might be a good lead for new catalyst
development for 13Pd, as both share the same intermediate.
4. The process can also be applied for long chain polyols for the production of
important derivative like 5-HMF.
References:
Please refer to
Renewable chemicals: Dehydroxylation of Glycerol and Polyols
Jeroen ten Dam and Ulf Hanefeld
ChemSusChem 2011, 4, 1017-1034; DOI: 10.1002/cssc.201100162