The catalytic conversion of glycerol was performed with iron oxide-based catalysts for production of allyl alcohol using a fixed-bed flow reactor at 623 K under atmospheric pressure.The glycerol dehydration proceeds on acid sites of catalysts while the allyl alcohol production is assumed to be catalyzed by non-acidic sites of catalysts through a hydrogen transfer mechanism.Different alkali metals, including Na, K, Rb, and Cs were supported on ZrO 2 -FeO X and all of them gave impressively higher allyl alcohol yield and suppressed glycerol dehydration due to the reduced catalyst acidic property. K-supported ZrO 2 -FeO X (K/ZrO 2 -FeO X ) was chosen for further studies, and allyl alcohol yield remarkably increased up to 27 mol%-C at the K content of 3-5 mol%. Since no external hydrogen gas is supplied to the system, the hydrogen transfer mechanism should take place between the reaction of glycerol and either hydrogen atoms derived from formic acid forming during the reaction, or active hydrogen species produced from the decomposition of H 2 O by ZrO 2 .Addition of Al 2 O 3 to K/ZrO 2 -FeO X (K/Al 2 O 3 -ZrO 2 -FeO X ) was examined in order to improve structure stability during the glycerol conversion. Al 2 O 3 addition to the catalyst was effective to achieve higher structure stability, leading to high glycerol conversion with stable allyl alcohol yield of above 25 mol%-C. Moreover, K/Al 2 O 3 -ZrO 2 -FeO X can be applicable to the conversion of crude glycerol which is the waste solution obtained from biodiesel production.3

Conversion of glycerol to useful chemicals was examined using a zirconia-iron oxide catalyst. An aqueous glycerol solution was used as feedstock, and the catalytic reaction was carried out in a fixed-bed flow reactor at 623 K under atmospheric pressure. Useful chemicals, for example propylene, allyl alcohol, carboxylic acids, and ketones, were obtained from the aqueous glycerol solution. The reaction was found to involve a series of consecutive reactions, with allyl alcohol and carboxylic acids as reaction intermediates which were converted to propylene and ketones, respectively. Moreover, the catalyst had high and stable activity in the reaction of a 50 wt% glycerol solution.

In this study, catalytic conversion of crude glycerol was performed over ZrO2–FeO x 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–FeO x 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.