Glycerol Selective Oxidation: A Reaction Engineering Study

Increase in the production of biodiesel has resulted in an oversupply of glycerol, the primary byproduct which forms in a 1:10 ratio with biodiesel.  An effective utilization of glycerol (currently ~$0.02/lb) by conversion to the higher value chemical dihydroxyacetone (DHA; currently ~$20/lb) will enhance the economics of biodiesel production.  Towards this end, we have developed a Pt-Bi/C catalyst capable of selective oxidation of the secondary hydroxyl group of glycerol to produce DHA.  The catalyst and operating conditions were optimized in a semi-batch reactor to achieve a high yield of DHA (>40%) [1]. A kinetic model for the full 10-step glycerol oxidation network and a simplified kinetic model were also developed [2]. To increase production, a continuous-flow trickle-bed reactor can be utilized. In this direction, the hydrodynamics of trickle-bed reactors have been characterized, particularly with respect to the material attributes of the activated carbon support for our optimal Pt-Bi catalyst. Detailed catalyst, kinetic, and reactor characterization provide a fundamental basis for the development of a continuous-flow process for selective conversion of glycerol to DHA, which in turn will increase the economic viability of biodiesel production.

[1] Hu, W., Knight, D., Lowry, B., Varma, A. Selective oxidation of glycerol to dihydroxyacetone over Pt-Bi/C catalyst:  Optimization of catalyst and reaction conditions. Ind. Eng. Chem. Res. 2010, 49 (21), 10876-10882. 

[2]  Hu, W., Lowry, B., Varma, A.  Kinetic study of glycerol oxidation over Pt-Bi/C catalyst.  Appl. Catal. B: Environmental 2011, 106 (1-2), 123-132.