Coke promoters improve acrolein selectivity in the gas-phase dehydration of glycerol to acrolein

摘要

Commercial processes partially oxidize propylene to acrolein but glycerol can replace the petroleum derived feeds as a bio-feedstock for this large volume specialty chemical. Metal oxides, particularly acid catalysts, dehydrate glycerol at elevated temperature. Dehydration of glycerol to acrolein is usually performed in traditional fixed-bed reactors. We tested phosphotungstic acid (HPW) loaded on titania catalysts (a weight fraction of 10, 20 and 30%) at 280 degrees C in a fluidized-bed reactor. With time-on-stream, the acrolein selectivity increased and the coke selectivity decreased. As much as 85% of the glycerol formed coke in the first hour and less than 20% acrolein. We developed a new method to spray the liquid feed directly on the catalyst bed and the reaction occurred in the gas phase.