Influence of Zeolite Support Topology on Ru Catalyst Performance in Hydrodeoxygenation of Biomass-Derived Guaiacol.

To investigate the influence of the topological structure of zeolite supports on the selectivity of hydrodeoxygenation of guaiacol to cyclohexanol, four various zeolites, β, ITQ-1, S-1, and MCM-41, were synthesized for the preparation of Ru-supported catalysts. Microporous and mesoporous structures were observed in the dealuminated β, ITQ-1, and S-1 zeolites, with the dealuminated β zeolite exhibiting a larger surface area and the ITQ-1 and S-1 zeolites showing a larger external surface area. MCM-41 zeolite possessed only a mesoporous structure and displayed the largest surface area. The Ru/S-1 and Ru/MCM-41 catalysts had higher Ru4+ content and lower Ru0 content compared to Ru/β and Ru/ITQ-1 catalysts. Moreover, the particle sizes of Ru on Ru/β, Ru/ITQ-1, and Ru/S-1 catalysts were similar and smaller than those on Ru/MCM-41 catalyst. Selective hydrodeoxygenation results revealed that the Ru/S-1 and Ru/MCM-41 catalysts achieved the highest guaiacol conversion after prolonged reaction time, although the Ru/β catalyst exhibited higher intrinsic hydrodeoxygenation activity. The Ru/S-1 catalyst exhibited the highest selectivity toward cyclohexanol among all of the catalysts. Considering both guaiacol conversion and cyclohexanol selectivity, the Ru/S-1 catalyst displayed superior selectivity hydrodeoxygenation activity of guaiacol to cyclohexanol, this is attributed to its suitable topological structure, higher Ru4+ content, and larger external surface area, which collectively facilitated the selective adsorption and promoted the hydrodeoxygenation reaction.