Tuning electron density of Pd species by Na + ions in Silicalite‐1 zeolite for enhanced the hydrodehalogenation reaction

ABSTRACT Hydrodehalogenation is an important transformation in chemical synthesis and environmental protection. Current synthesis strategies are involved in the use of various additives and expensive hydrogen sources in both homogeneous and heterogenous catalysis system. Na‐modified Silicalite‐1 zeolite supported Pd catalyst (Pd/Na 3 S‐1) successfully mediated the dehalogenation reaction using water as a hydrogen source without any additives, outperforming its counterparts on Na‐free Silicalite‐1 (Pd/S‐1) and Beta (Pd/Beta) zeolites in activity. This is because excess Na + ions in S‐1 zeolite led to the generation of numerous highly active, electron‐deficient Pd δ+ (0 < δ < 2) and Pd 4+ sites in the Pd/Na‐S‐1 catalyst, due to the electron transfer from Pd species to nearby Na ion or framework O atom. While Pd/S‐1 exhibited a predominance of low‐active Pd 2+ species, and Pd/Beta catalyst contained Pd 0 species that was primarily responsible for the generation of dehalogenation‐coupling product.