Highly Active Pd Clusters Enabled With Controllable Oxygen Vacancy for the Synergistic Decarbonylation of Furfural to Furan.

Precisely regulated metal clusters are crucial for maximizing the utilization efficiency of active metal atoms. In this study, we controllably introduced oxygen vacancy (Ov) into TiO2 via H2 reduction to regulate the assembly of Pd atoms for furfural decarbonylation. The optimized Pd/TiO2 catalyst with smaller Pd clusters and a suitable oxygen vacancy concentration achieved a 99.9% furfural conversion and a 92.4% furan selectivity at 200 °C and 0.3 MPa N2 pressure, showing high catalytic performance under relatively mild conditions. Structural characterizations revealed that oxygen vacancies acted as anchoring sites for Pd species, and an appropriate vacancy concentration favored the formation of highly dispersed Pd clusters rather than larger Pd nanoparticles. Comprehensive structural and electronic analyses revealed strong interactions between Pd species and oxygen-vacant TiO2, leading to the formation of Pd2+-Ov-Ti interfacial sites. These interfacial sites promote carbonyl activation and CO elimination, while adjacent Pd0 sites facilitated H transfer to produce furan. This work not only develops a highly efficient and tunable Pd-based catalyst for the furfural decarbonylation, but also provides a versatile strategy for optimizing catalytic interface via oxygen vacancies.