Catalytic epoxidation of allylic alcohol (E)-2-Hexen-l-ol over vanadium supported on unsulfated and sulfated titanium pillared montmorillonite catalysts: Effect of sulfate groups and vanadium loading

摘要

Vanadium supported on unsulfated and sulfated Titanium pillared montmorillonite with different vanadium loading was prepared and characterized. The catalytic activity of the synthesized materials in the epoxidation of the allylic alcohol (E)-2-Hexen-1-ol was evaluated. The results showed that the textural, structural, acidic and redox properties of the catalysts investigated were influenced by the presence of both vanadium and sulfate. It was found that the Ti-pillared materials used as support for vanadium are inactive in the epoxidation of the allylic alcohol (E)-2-Hexen-1 -ol using a molar ratio of TBHP/alcohol = 1. The presence of different vanadium amount increased the catalytic activity of all samples investigated due to the creation of active redox sites on the support. When both vanadium and sulfate existed simultaneously on the catalyst surface, the interaction between sulfate groups and vanadium species enhanced significantly the reactivity of the redox sites leading to more active catalysts in the epoxidation of (E)-2-Hexen-1-ol. It was also shown that only 1 wt.% of vanadium was strongly retained by the Ti-pillared montmorillonite that promotes the epoxidation of (E)-2-Hexen-1-ol without vanadium leaching, leading to heterogeneous catalysis.