Direct Hydrogenolysis of Highly Concentrated Glycerol Solutions Over Supported Ru, Pd and Pt Catalyst Systems
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Direct Hydrogenolysis of Highly Concentrated Glycerol Solutions Over Supported Ru, Pd and Pt Catalyst Systems Esti van Ryneveld • Abdul S. Mahomed • Pieter S. van Heerden • Holger B. Friedrich
Received: 18 February 2011 / Accepted: 26 April 2011 / Published online: 24 May 2011 Ó Springer Science+Business Media, LLC 2011
Abstract The evaluation of supported precious metal catalysts, in combination with and without solid acids, for the hydrogenolysis of highly concentrated glycerol solutions, with the aim to produce lower alcohols, in particular 1-propanol was studied. GCMS analysis of the product mixtures obtained has shed some light on the possible mechanism leading to unwanted condensation products, as well as the composition of these compounds. Keywords Supported precious metal catalysts Solid acids Glycerol 1-propanol
1 Introduction Glycerol is a recognised renewable feedstock and the ability to use it as a starting material for chemical transformations is very appealing. It is a by-product from the production of biodiesel from vegetable oils. From an industrial perspective a number of potential glycerol valueadding transformations have been reported in literature.
E. van Ryneveld H. B. Friedrich (&) School of Chemistry, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa e-mail: [email protected] E. van Ryneveld e-mail: [email protected] A. S. Mahomed P. S. van Heerden R&D Division, Sasol Technology, 1 Klasie Havenga Street, Sasolburg 1947, South Africa e-mail: [email protected] P. S. van Heerden e-mail: [email protected]
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The most promising transformations include hydrogenolysis to 1,2-propanediol (1,2-PDO) and 1,3-propanediol (1,3-PDO) [1, 2], dehydration to acrolein [3] and reforming into synthesis gas (CO/H2) [4]. Other interesting transformations reported are the production of alcohols, such as 1-propanol (1-PO) and 2-propanol (2-PO) [5], and ethylene glycol (EG) [6] from glycerol, albeit yields reported often have been disappointingly low. Tomishige and co-workers [1] reported that various noble metals (Ru/C, Rh/C, Pt/C and Pd/C) and acid catalysts (H2SO4, HCl and Amberlyst 15) combined, were effective for the hydrogenolysis of glycerol under mild conditions. The promoting effect of adding Amberlyst 15 to the Ru/C reaction mixture was quite significant with an increase in glycerol conversion from 3.5 to 12.9%. Tomishige and co-workers [7] also investigated the difference between Amberlyst 15 and Amberlyst 70 in the hydrogenolysis of glycerol to 1,2-PDO. A combination of Ru/C ? Amberlyst 70 gave the highest glycerol conversion (26%) which was related to the heat resistance of the resin. The promoting effect of other solid acids in combination with Ru/C was also studied [8]. H2WO4 was effective in enhancing glycerol conversion, while the Rh/ C ? H2WO4 system showed higher activity to 1,3-propanediol. Other zeolites and solid acid catalysts, such as MFI (SiO2/Al2O3 = 22), BEA (SiO2/Al2O3 = 25), USY (SiO2/Al2O3 = 6.3) and SO42-
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