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A detailed model of glycerol hydrogenolysis in a trickle-bed reactor is presented that includes a mechanistically based kinetic rate expression, energy transport, mass transport across the gas-liquid and liquid-solid interfaces, intraparticle catalyst mass transfer, and partial wetting of the bed. Optimal kinetic parameters for the glycerol hydrogenolysis rate expression were determined via nonlinear regression analysis on the basis of experiments conducted in a laboratory-scale trickle-bed reactor over a broad range of operating conditions. Model predictions agree well with experimental data and accurately predict trends in reactor performance with liquid flow rate, temperature, hydrogen pressure, and base promoter concentration. The model is thus a useful tool for predicting laboratory reactor performance and for design of commercial-scale trickle-bed systems. IntroductionGlycerol (1,2,3-propanetriol, herein GO) has become an attractive feedstock for chemicals production because it is readily available as the major byproduct from biodiesel production. 1 In particular, GO hydrogenolysis to propylene glycol (PG) has received attention in both patent and open literature, because PG is a thousand kilo-tonne commodity with applications as a polymer building block, emollient in consumer products, and nontoxic replacement for ethylene glycol (EG). Among numerous patents describing GO conversion to PG, Casale et al. 1 used sulfide-modified ruthenium to achieve 75% PG yield; Schuster et al. 2 used a mixed metal (Cu/Co/Mn/Mo) catalyst with heteropolyacids that gave 96% PG yield, and Werpy et al. 3 demonstrated >80% selectivity to PG over a Ni/ Re catalyst. The open literature contains several studies of catalysts for PG formation from GO, including bimetallic Pt/Ru and Au/Ru catalysts at neutral and elevated pH, 4 carbon-supported Ru and

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