OP-II-3

PP-III-32CONVERSION OF GLYCEROL TO VALUE-ADDED CHEMICALSOVER POLYOXOMETALATE CATALYSTSKozhevnikov I.V., Alhanash A., Kozhevnikova E.F.Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, UKE-mail: kozhev@liverpool.ac.ukThe production of chemicals by catalytic transformation of bio-resources is aglobal challenge. Recent development of biodiesel production by transesterificationof plant oils and animal fat has made a large amount of glycerol available as arenewable feedstock for the synthesis of value-added chemicals. One of the mostimportant directions for the utilisation of glycerol is its dehydration to acrolein. Wefound that caesium 12-tungstophosphate, Cs 2.5 H 0.5 PW 12 O 40 (CsPW), possessingstrong Brønsted acid sites is an active catalyst for the dehydration of glycerol toacrolein in the gas-phase at 275°C and 1 bar pressure [1]. The initial glycerolconversion amounts to 100% at 98% acrolein selectivity, however, decreasessignificantly with the time on stream (~40% after 6 h) due to catalyst coking, withoutimpairing acrolein selectivity. Doping CsPW with platinum group metals (PGM)together with co-feeding hydrogen improve catalyst stability to deactivation, whilemaintaining high selectivity to acrolein. The enhancing effect of PGM was found toincrease in the order: Ru ~ Pt < Pd. The catalyst 0.5%Pd/CsPW gives 96% acroleinselectivity at 79% glycerol conversion, with a specific rate of acrolein production of23 mmol h –1 g –1 cat at 275°C and 5 h time on stream, exceeding that reportedpreviously for supported heteropoly acids (5 – 11 mmol h –1 g –1 cat per total catalystmass). Evidence is presented regarding the nature of acid sites required for thedehydration of glycerol to acrolein, supporting the importance of strong Brønstedsites for this reaction (Scheme 1).OHHO OH + OH+OH 2HO OHO+-OH 2+HO OH HO OH + H 3 O +HO OH O OH-H 2 OOO -+ H 3 O + OH+ H 2 OScheme 1. Mechanism of glycerol dehydration on Brønsted acid sites.498