Sequential Dehydration and Oxidation of Biodiesel-derived Crude Glycerol into Acrylic Acid

With the fast development of the biodiesel industry, the byproduced crude glycerol becomes excessive due to the limited demand for refined glycerol. This article provides a green and efficient route to produce acrylic acid from crude glycerol, which is a promising alternative and complement to the petroleum-based production of acrylic acid due to its economic and environmental benefits. Among all the impurities, only the alkaline metal ions in crude glycerol significantly decreased the yield of acrylic acid. After desalination of the plant crude glycerol with ion-exchange resin to remove the critical impurities, the sequential dehydration and oxidation system gave 86% acrylic acid yield, which was as high as that with pure glycerol. In addition, the system showed good thermal stability and regeneration ability after the reaction with desalted crude glycerol. Both the HPW/Cs–Nb and VMo–SiC catalysts were stable for at least 70 h. The activity and selectivity were well recovered after regeneration at the coke burning temperature of 500°C.