Highly Efficient Production of Acrylic Acid by Sequential Dehydration and Oxidation of Glycerol

Abstract

The selective dehydration–oxidation of glycerol to acrylic acid is a very attractive approach for glycerol utilization. In this work, we demonstrated an efficient two-bed system for this process. The dehydration catalyst was Cs2.5H0.5PW12O40 supported on Nb2O5 (CsPW-Nb), and the oxidation catalyst was vanadium–molybdenum mixed oxides supported on silicon carbide (VMo–SiC). The experimental results showed that the optimum reaction temperature and oxygen ratio for these two catalysts were very similar. This made the two-bed system simple and efficient. Compared with the single-bed system, the two-bed system with the dehydration catalyst and oxidation catalyst loaded separately was more favorable to avoid the overoxidation reaction of glycerol. A high yield of acrylic acid was achieved at optimized conditions in the two-bed system. The Bronsted acid sites on the dehydration catalysts were the active sites for acrolein formation. The byproducts produced on Lewis acid sites in the dehydration step and the wate...