MoOx-Decorated ZrO2 Nanostructures Supporting Ru Nanoclusters for Selective Hydrodeoxygenation of Anisole to Benzene

Currently, the hydrodeoxygenation (HDO) process of biomass-derived phenolics is regarded as one of the most promising methods of upgrading to produce various high-value-added chemical raw feeds (e.g., benzene, toluene, and xylene) as well as potentially applied bio-oils with less oxygen content. In this work, a series of surface MoO3-decorated nanosized tetragonal zirconia (t-ZrO2) supports were utilized to immobilize Ru nanoclusters for the aqueous-phase HDO of anisole. Structural characterizations revealed the presence of uniformly dispersed Ru nanoclusters and defective MoOx clusters on the t-ZrO2, thereby forming strong Ru-MoOx interactions and thus the generation of abundant interfacial Ru delta+ species and oxygen vacancies. As-fabricated supported Ru nanoclusters as the catalyst could achieve a much higher benzene selectivity of similar to 84.7% than the Mo-free supported Ru one (25.1%) in the HDO of anisole under mild reaction conditions, despite a lowered anisole conversion, which was associated with the cooperative effect between active Ru-0 nanoclusters and favorable interfacial Ru delta+-O-v-Mo5+ sites (O-v = oxygen vacancy), thereby enhancing the adsorption of the methoxy group in anisole and the further demethoxylation to form benzene. Our present findings provide a promising way to regulate the selectivity of deoxygenated products in the HDO of biomass-derived phenolics via finely tuning active metal-support interfacial sites.

Automated summary

In this study, surface MoO3-decorated nanosized tetragonal zirconia (t-ZrO2) supports were utilized to immobilize Ru nanoclusters for the aqueous-phase HDO of anisole, achieving higher benzene selectivity. The presence of uniformly dispersed Ru nanoclusters and defective MoOx clusters on the t-ZrO2, forming strong Ru-MoOx interactions, led to the generation of abundant interfacial Ru delta+ species and oxygen vacancies, enhancing the adsorption of the methoxy group in anisole and the further demethoxylation to form benzene.