Construction of WOx@HTS-1 Nanoparticles for Efficient Catalysis of 1-Hexene Epoxidation

Abstract

1-Hexene epoxidation is difficult to achieve for the low electron cloud density of long-chain terminal olefin double bonds structure; the development of efficient and stable catalysts is the key to achieving the highly efficient epoxidation of 1-hexene. The titanosilicate/H₂O₂ system has been the most promising and environmentally friendly epoxidation route in recent research, and the WO_x@HTS-1 nanoparticles were successfully prepared by an etching–impregnation–recrystallization strategy in this work. Unique structures of the WO_x@HTS-1 nanoparticles could achieve the effects of “killing three birds with one stone” for 1-hexene epoxidation. I. Hierarchical structure and “hollow nests” could significantly enhance the accessibility of the active sites, shorten the transmission path, and improve the diffusion efficiency of the reactants and products. II. Titanium active centers and metal oxide active sites had significant and efficient synergistic catalytic effects on 1-hexene epoxidation. III. Fine WO_x particles were highly dispersed on the hollow nests of WO_x@HTS-1 nanoparticles, which prevented the sintering and poisoning of WO_x clusters during the reaction process and ensured excellent stability of the catalysts by the restricted-domain effect. Attractively, 1-hexene conversion and 1,2-epoxyhexane selectivity were more than 90 and 96% with WO_x@HTS-1 nanoparticles and H₂O₂, respectively, which provided many opportunities for the directional design of nanoparticles and their application in emerging catalytic fields.