Surface Brønsted acid local enrichment induced by hydrogen spillover for improved biomass selective hydrodeoxygenation performance

The development of highly efficient and selective metal-acid bifunctional catalysts with excellent synergy is essential for obtaining target products and reducing carbon loss in biomass upgrades. Here, a strategy of surface Brønsted acid local enrichment induced by hydrogen spillover is proposed to optimize the metal-acid synergy. The Ni/10TiO2/ZSM-22 catalyst, which features Ni nanoparticles and ZSM-22 separated by a sub-nanometric TiO2 porous film, was prepared using atomic layer deposition to improve the palmitic acid hydrodeoxygenation performance. The TiO2 film facilitates hydrogen spillover, improving the hydrogenation activity of metal sites. Approximately 75% of the original surface Brønsted acid sites (BASs) on ZSM-22 are covered by the porous TiO2, and the surface BAS concentration of Ni/10TiO2/ZSM-22 is increased due to the facilitated hydrogen spillover, i.e., the surface BASs are enriched locally in the zone of TiO2 pores. Thanks to the surface BAS local enrichment, the formation of byproduct pentadecane is inhibited, and the intermediate 1-hexadecanol is rapidly converted, obtaining notable hexadecane selectivity. This strategy is also effective for the Pt/10TiO2/ZSM-22 catalyst, resulting in nearly 100% hexadecane yield (99.6%). This research provides valuable insights into designing highly efficient bifunctional catalysts for energy conversion.