Experimental and Modeling Study of Catalytic Hydrogenation of Glucose to Sorbitol in a Continuously Operating Packed-Bed Reactor

Sorbitol is an alternative sweetener and a platform chemical for a wide variety of compounds. Selective hydrogenation of glucose to sorbitol over a commercial Ru/C catalyst was studied both experimentally and with the aid of detailed mathematical modeling. The experiments were conducted in a laboratory scale trickle bed and in a semibatch stirred tank reactor. Sorbitol was obtained from the packed-bed reactor as the main product, typically with similar to 90% selectivity within the studied temperature range (90-130 degrees C), while the side product was mannitol. The factors of interest were the temperature- and concentration-dependent reaction kinetics, deactivation, internal diffusion and heat conduction within particles, radial heat conduction and mass dispersion in the selected reactor section, liquid holdup, gas liquid mass transfer, pressure drop, and axial dispersion. A mass-balance-based axial dispersion model (using temperature dependent kinetics and deactivation modeled using the final activity concept) was capable of explaining the observed continuous packed bed behavior rather well The stirred tank reactor behavior could be described by a mass-balance-based model Parameter estimation revealed that the main difference between semibatch and continuous operations arose from the more severe deactivation in the packed bed. Simultaneous solution of heat and mass transfer for the top most reactor section and for a catalyst particle revealed that heat transfer limitations were not severe.