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 WOx@HTS-1 nanoparticles were successfully prepared by an etching–impregnation–recrystallization strategy in this work. Unique structures of the WOx@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 WOx particles were highly dispersed on the hollow nests of WOx@HTS-1 nanoparticles, which prevented the sintering and poisoning of WOx 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 WOx@HTS-1 nanoparticles and H2O2, respectively, which provided many opportunities for the directional design of nanoparticles and their application in emerging catalytic fields.
Hierarchically porous TS-1 (HTS-1) zeolite with nanocrystal aggregate structure has been successfully synthesized by hydrothermal and steam-assisted crystallization (SAC) method with the aid of polyvinyl alcohol (PVA). It has been found that the formation of mesoporous aggregates was attributed to the construction of PVA three-dimensional network. The mesoporous aggregate structure could be well maintained by SAC method, resulting in HTS-1 with either surface titanium enrichment or highly interconnected mesopores and high external surface. Both could contribute to the excellent catalytic performance of HTS-1 in oxidative desulfurization of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The TOF numbers of HTS-1 reached a very high value to 114.9 h −1 and 53.2 h −1 in the oxidation of DBT and 4,6-DMDBT, respectively. Moreover, the HTS-1 showed good stability and remained ∼90% of its initial activity even after 3 times cycle. The high catalytic activity and good stability suggest that HTS-1 is a promising catalyst for deep oxidative desulfurization.
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