Glucose-Assisted Preparation of a Nickel–Molybdenum Carbide Bimetallic Catalyst for Chemoselective Hydrogenation of Nitroaromatics and Hydrodeoxygenation of m-Cresol

Developing a safe, facile, clean, low-cost, and scalable new method to replace the conventional methane reductive carburization process for preparing carbon-nanotube, coverage-free, highly dispersed, metal carbide based bimetallic catalysts without a sacrificial metal loading is of great significance but remains a challenge. In this work, we develop a facile and robust strategy for successfully preparing a highly dispersed supported nickel–molybdenum carbide (NiMo2C) bimetallic catalyst on mesoporous silica [NiMo2C/SBA-15(Glu.)], in which the renewable glucose is employed to serve as an assisting agent for high metal dispersion within the mesoporous channels of SBA-15 in the impregnation process and as a carbon source to replace flammable methane for metal carbide formation through a reductive carburization process. From diverse characterization results, the as-prepared NiMo2C/SBA-15(Glu.) catalyst demonstrates a much higher metal dispersion (ca. 4.1 nm in this work vs ca. 80 nm aggregates by the conventional method, as proven by transmission electron microscopy, X-ray diffraction, CO chemosorption, etc.) and promoted synergy effect between Ni and Mo2C than the NiMo2C/SBA-15(Ref.) prepared by a conventional impregnation method, followed by methane reductive carburization (as proven by X-ray photoelectron spectroscopy and H2 temperature-programmed reduction); besides, the growth of carbon nanotubes is eliminated. As a consequence, the NiMo2C/SBA-15(Glu.) catalyst shows unexpectedly 18 times higher catalytic specific activity for chemoselective hydrogenation of nitrobenzene and 12 times higher for the hydrodeoxygenation of m-cresol than conventional NiMo2C/SBA-15(Ref.). Moreover, NiMo2C/SBA-15(Glu.) shows a notably different product distribution for the hydrodeoxygenation of m-cresol owing to the bifunctional effect of Mo2C. The as-prepared supported NiMo2C catalyst can be extended to other transformations, and also the developed method in this work can be extended for the preparation of other metal carbide catalysts toward diverse applications.