Kinetic Modeling of Aqueous-Phase Glycerol Hydrogenolysis in a Batch Slurry Reactor

The kinetics of the aqueous-phase hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO) was studied using a bimetallic Ru-Re/C catalyst in a slurry reactor in a temperature range of 493-513 K and a hydrogen pressure of 2.4-9.6 MPa. Glycerol hydrogenolysis to produce 1,2-PDO via C-O cleavage (i) proceeds with parallel C C cleavage, reforming, water-gas shift, and Fischer-Tropsch reactions, (ii) results in a very complex reaction network with several gaseous- and liquid-phase products, and (iii) poses a challenge to design selective catalysts. It is observed that Ru-Re bimetallic catalyst shows higher hydrogenolysis activity (glycerol conversion of X = 57.7%) and 1,2-PDO selectivity (S = 36.6%), compared to the monometallic Ru catalyst (X = 52.1%; S = 18.9%) but the monometallic Re catalyst showed no catalytic activity for the reaction. Stirred-batch reactor data on the transient concentrations of reactants and products in both the gas and liquid phases were obtained using a bimetallic Ru-Re/C catalyst under different conditions to understand the reaction pathways, selectivity behavior, and intrinsic kinetics of the different reaction steps. For kinetic modeling, several experiments were performed at different initial pressures of hydrogen, catalyst concentration, and temperatures. The proposed rate equations, along with the regressed kinetic and activation energy parameters, were found to represent the experimental data for the multistep hydrogenolysis reaction very satisfactorily.