Site-Selective Pt Anchoring on Oxygen Vacancies by Atomic Layer Deposition Promotes Metal–Acid Synergy for Enhanced Guaiacol Hydrodeoxygenation
Abstract
For metal-acid bifunctional catalysts, accurately tuning the spatial distribution of catalytic sites and enhancing the metal-acid synergy remain a challenge. To this end, we combine oxygen vacancy (Ov) engineering with atomic layer deposition (ALD) on Nb2O5·nH2O to simultaneously achieve highly dispersed Pt, enhanced Brønsted acid site (BAS) concentration, and optimized metal-acid synergy. Specifically, for the Pt/Ov-Nb2O5·nH2O catalyst, the abundant Ovs formed in the Ov-Nb2O5·nH2O via H2 heat treatment guide more ALD Pt selective anchoring, thus forming smaller Pt clusters. Additionally, Pt species on the Ovs intensify local NbO6 distortion, inducing more BASs. These acid sites are in close proximity to Pt species, enhancing metal-acid synergistic catalysis. By contrast, Pt/Nb2O5·nH2O, prepared by directly depositing Pt on Nb2O5·nH2O, exhibits a larger Pt cluster size and lower BAS concentration. Consequently, Pt/Ov-Nb2O5·nH2O exhibits efficient guaiacol conversion and higher cyclohexane selectivity than Pt/Nb2O5·nH2O in guaiacol hydrodeoxygenation (HDO). This endeavor offers guidelines for the rational design of metal-acid bifunctional catalysts.