Atomically-ordered active sites in NiMo intermetallic compound toward low-pressure hydrodeoxygenation of furfural

Abstract

Activation of oxygen-containing functional groups plays a key role in sustainable biomass upgrading and conversion. In this work, a NiMo intermetallic compound (IMC) catalyst was prepared based on layered double hydroxides (LDHs) precursors, which displayed prominent catalytic performance for furfural hydrodeoxygenation (HDO) to 2-methylfuran (2-MF) (yield: 99 %) at a rather low hydrogen pressure (0.1 MPa), significantly superior to NiMo alloy, monometallic Ni and other Ni-based catalysts ever reported. CO-IR, STEM, EXAFS and XANES give direct evidences that the atomically-ordered Ni/Mo sites in NiMo IMC determine the uniform bridging-type adsorption mode of CO bond in furfural whilst adsorption of furan ring is extremely suppressed. In situ FT-IR and DFT calculation further substantiate that ordered Ni-Mo bimetallic sites of IMC, in contrast to the random atomic sequence in NiMo alloy, facilitate the activation and cleavage of COH bond in the intermediate (furfuryl alcohol, FOL), accounting for the production of 2-MF. This work demonstrates the decisive effect of atomically-ordered active sites in IMC catalyst on activation of oxygen-containing functional groups and product selectivity, which can be extended to catalytic upgrading of biomass-derived platform molecules.