Hydrogenation of Glucose on a Carbon-Supported Ru Catalyst: Optimization of the Reaction Conditions

Abstract

The catalytic hydrogenation of D-glucose over a 3 wt% Ru/C catalyst wasstudied varying the operating conditions in mild conditions range to optimizethe obtention of D-sorbitol. The stirring speed, temperature, pressure, andinitial glucose concentration were varied between 250 - 700 rpm, 343 - 383 K,0.5 - 2 MPa, and 0.033 - 0.133 M, respectively. To verify the absence of masstransport limitations, the diffusion of reagents in the gas-liquid interface, theliquid-solid interface, and the internal diffusion in the particles were evaluated.Under the operating conditions studied, the reaction rate showed anorder with respect to H2 of 0.586 and with respect to glucose of 0.406. The kineticdata were adjusted using 3 general models and 19 different sub-modelsbased on Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetics. Model3a was the best one interpreting the aqueous phase hydrogenation of glucose(both reagents competitively adsorbed on the catalyst). The H2 adsorption isdissociative and the rate-limiting step is the surface chemical reaction.