Valorisation of glycerol by condensation with acetone over silica-included heteropolyacids

Abstract

The acetalisation of glycerolwasstudied using heteropolyacids, immobilized in silica, as catalysts, at 70 ◦C. The main product of glycerol acetalisation was solketal. The tungstophosphoric (PW), molybdophosphoric (PMo), tungstosilisic (SiW) and molybdosilisic (SiMo) acids were immobilized in silica by sol–gel method. It was observed that the catalytic activity decreases in the series: PW-S > SiW-S >PMo-S > SiMo-S. All catalysts exhibited good values of selectivity to solketal (about 98% near complete conversion). The effect of different parameters, such as catalyst loading, molar ratio of glycerol to acetone and temperature on the glycerol acetalisation, over PW-S catalyst, was studied. Catalytic stability of the PW-S, SiW-S, PMo-S and SiMo-S catalysts was evaluated by performing consecutive batch runs with the same catalyst sample. After the third batch, it was observed a stabilisation of the initial activity.