Synergistic Effects of Ni Particle Size and Spatial Location for Selective Hydrodeoxygenation of Guaiacol to Arenes Over Ni/S-1 Catalysts

Abstract The growing demand for renewable energy and chemicals has driven intensive research into renewable pathways for arene production from lignin-derived phenolic compounds. The development of high-activity catalysts for hydrodeoxygenation (HDO) of phenolics into arenes has always been the key to achieving this pathway. While Ni-based systems are cost-effective, their selectivity remains challenging. We constructed a series of Ni/S-1-(x) catalysts with precise control over both Ni species size and their specific spatial enrichment sites on the external surface over the zeolite to study the effect of structural sensitivity on guaiacol HDO into arene. The result shows that the Ni/S-1-(1) catalyst with Ni particles of 9.4 nm situated at the interfacial region between micropore entrances and the external surface exhibits high arene-forming catalytic activity, achieving a maximum arene selectivity of 56.5% and a high turnover frequency of 121.3 h–1. This enhanced activity can be attributed to the highly appropriate size of the Ni nanoparticles, which facilitates the generation of active hydrogen species essential for efficient cleavage of the CAR–O bonds. Additionally, the effect of Ni species located at the interfacial region connecting micropore entrances and the external surface promotes a vertical adsorption orientation of the reactant molecule, which selectively inhibits undesirable hydrogenation of the aromatic ring. This work provides a strategy for the accurate design of high-performance Ni-based catalysts aimed at upgrading lignin-derived phenolics into valuable arenes.