Conversion of Biodiesel-Derived Crude Glycerol into Useful Chemicals over a Zirconia–Iron Oxide Catalyst

Abstract

In this study, catalytic conversion of crude glycerol was performed over ZrO2–FeOx catalysts for the production of useful chemicals. A crude glycerol solution obtained from biodiesel production was used as a feedstock, and a catalytic reaction was carried out in a fixed-bed flow reactor at 623 K under atmospheric pressure. The reaction was found to involve a series of consecutive reactions in which allyl alcohol, propylene, hydroxyacetone, carboxylic acids, acrolein, and ketones are included as intermediate and terminated products. Although the crude glycerol contained methanol, free-fatty acids, and potassium as impurities, using a ZrO2–FeOx catalyst, the glycerol in the feedstock converted into these useful chemicals, the composition of which were identical regardless of the crude glycerol concentration. Moreover, an increase in the W/F (weight ratio of catalyst to feedstock) value allowed the consecutive reactions to progress, and the products were summed up in 24 mol % C of propylene and 25 mol % C of ketones.