Selective hydrogenation of D-glucose to D-sorbitol over Ru/ZSM-5 catalysts

Ru particles were introduced into the zeolite ZSM-5 (MFI) by either a conventional impregnation method or a one-step template-free process. The resultant materials were characterized by X-ray diffraction, N 2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy, NH 3 and CO 2 temperature-programmed desorption. The results indicated that the Ru species in ZSM-5 catalysts prepared via the latter approach (designated as Ru/ZSM-5-TF) were highly dispersed in the ZSM-5 framework structure and this material exhibited high catalytic performance during the hydrogenation of D-glucose to D-sorbitol. The conversion of D-glucose was as high as 99.6% with D-sorbitol selectivity reaching 99.2%, exceeding the performance of Ru/ZSM-5 catalysts prepared by the conventional impregnation method with microporous or desilicated ZSM-5 supports. More importantly, this catalyst showed high stability against leaching and poisoning and could be reused several times. The extensive dispersion of the Ru species, strong interaction between the Ru species and the ZSM-5, and the suitable surface acidity-basicity balance of the Ru/ZSM-5-TF were all critical factors leading to excellent catalytic behavior and stability.