Gas-Phase Dehydration of Glycerol into Acrolein in the Presence of Polyoxometalates

The activity of catalytic systems based on polyoxometalates in the gas-phase dehydration of glycerol into acrolein has been investigated. The catalysts synthesized have been characterized using FTIR spectroscopy, X-ray phase analysis, scanning electron microscopy, and low-temperature nitrogen adsorption/desorption (BET method). It has been shown that the nature of the surface acid sites of catalysts has a significant effect on the direction of glycerol transformation. An increase in the fraction of Bronsted acid sites in the catalyst leads to an increase in the yield of acrolein. At the same time, an increase in the fraction of Lewis acid sites in the catalyst leads to an increase to the yield of acetol, which is formed through a competing route. Among the catalytic systems considered, the best results have been obtained with the silicomolybdic acid anion supported onto alumina (SiMo/A). The main patterns of the gas-phase glycerol dehydration have been studied using SiMo/A as a catalyst, and the conditions responsible for the highest yield of acrolein have been determined.