Unveiling the in-situ formation of single-atomically dispersed Pd-Fe bimetallic catalytic sites during anisole hydrodeoxygenation

Abstract

Hydrodeoxygenation (HDO) is a promising route to convert biomass molecules into biofuels, which is usually promoted by supported noble metal catalysts. It is still one of the key issues to reduce the usage of noble metal for improving the atomic efficiency of the catalyst. As a type of emerging catalytic materials, single-atomically dispersed bimetallic catalyst (SDBM) is a promising candidate for this purpose. Herein, we investigated a single-atomically dispersed Pd/Fe2O3 catalyst with the exceptional HDO activity. At 573 K, anisole conversion is 99% while the selectivity to HDO products is 84%. The turnover rate per Pd atom is 182.2 h−1, which is remarkably greater than that of supported Pd nanoparticles. Additionally, it exhibits good stability for more than 110 h of continuously operation. The authentic catalytic sites during reaction was studied by comprehensive techniques. The presence of the Pd atoms on Fe2O3 changes the surface chemistries of the catalyst surface, then boosts the HDO activity consequently. As unveiled by in-situ X-ray absorption spectroscopy, the Pd atoms are coordinated with 2.76 nearby Fe atoms in average via metallic Pd-Fe bonds. Under HDO reaction conditions, single atomically dispersed Pd1Fe3 bimetallic sites are generated in-situ and act as the authentic catalytic sites.