Liquid phase glucose hydrogenation to -glucitol over an ultrafine Ru-B amorphous alloy catalyst

A Ru-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of RuCl₃ with borohydride in aqueous solution, whose amorphous structure was confirmed by XRD, DSC, and SAED. Heating pretreatment resulted in the rapid crystallization and the deep decomposition of the Ru-B amorphous alloy as well as the abrupt decrease in the surface area due to the gathering of small particles at high temperature. XPS spectra revealed that partial electrons transferred from the alloying B to the metallic Ru in the as-prepared Ru-B sample. In comparison with other catalysts, the as-prepared Ru-B amorphous catalyst exhibited excellent activity and perfect selectivity to -glucitol as well as superior lifetime during the liquid phase glucose hydrogenation, showing its potential application in industrial process. The higher activity of the Ru-based catalysts than that of other metal catalysts, such as Co-B and Ni-B amorphous catalysts as well as Raney Ni catalysts, demonstrated that the metallic Ru was more active than both metallic Ni and Co for the glucose hydrogenation. Meanwhile, the Ru-B amorphous catalyst exhibited higher activity than its corresponding crystallized Ru-B and pure Ru powder catalysts, showing the promoting effects of both the amorphous structure and the electronic interaction between the metallic Ru and the alloying B, which was briefly discussed based on the kinetic studies and various characterizations.