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

Abstract

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.

Nanostructured Metal Catalysts for Selective Hydrogenation and Oxidation of Cellulosic Biomass to Chemicals

“…Possible reaction pathways for glycerol conversion . Extensive experimental studies have described the possible reaction pathways of hydrogenolysis of glycerol, the overall scheme for which is summarized in Scheme . It is generally established that glycerol conversion is initiated with (metal catalyzed) dehydrogenation or (acid/base catalyzed) dehydration on catalyst surface.…”

“…With sulfur/Ru ratios increasing from 0 to 0.4, the activation energy for glycerol decomposition was enhanced from 44 to 88 kJ/mol. Torres et al . investigated effect of several parameters including temperature, hydrogen pressure, catalyst loading and glycerol concentration on reaction rates.…”

Glycerol transformation to value added C3 diols: reaction mechanism, kinetic, and engineering aspects

“…Possible reaction network over a Ru–Re/C catalyst proposed by Torres et al, Reproduced by permission of American Chemical Society from Ref [].…”

“…A detailed kinetic analysis of glycerol reaction in aqueous-phase and a batch reactor was reported by Torres et al over a Ru-Re/C catalyst. 75 Experimental data were obtained at a temperature range of 493-513 K and a hydrogen pressure of 2.4-9.6 MPa. The mechanistic steps proposed include both liquid and gas phase product formation.…”

Recent advancements in catalytic conversion of glycerol into propylene glycol: A review

“…(23,24). To overcome some of these issues and to enhance the PG production, Torres et al, studied the hydrogenolysis of glycerol in a batch-slurry reactor using a bimetallic Ru-Re catalyst over carbon support (25). The reactor system was made up of a parallel array of six autoclave reactors that could be operated simultaneously at different temperatures and pressures using computer control.…”