The study of design and performance improvement of catalysts for the stepwise production of bicyclohexane from benzene and cyclohexene

Abstract

Bicyclohexane is a hydrogen storage reagent with high hydrogen density and low boiling point. Compared with the hydrogenation of biphenyl, the alkylation of benzene and cyclohexene to cyclohexylbenzene and hydrogenation is a promising way to prepare cyclohexane on a large scale. The research and development of high-efficiency cyclohexyl benzene hydrogenation catalyst should be further developed based on mature alkylation technology. This paper used an acidified USY molecular sieve to catalyze the alkylation of benzene and cyclohexene to cyclohexylbenzene, which achieved 100% conversion and selectivity. Furthermore, Pt/TiO₂/γ-Al₂O₃ catalyst is prepared by pre-deposition TiO₂ film of different thicknesses on γ-Al₂O₃ surface and then supported with platinum particles by Atomic layer deposition (ALD). The role of TiO₂ film in improving the cyclohexylbenzene hydrogenation performance of the catalyst is studied. TEM, CO pulse chemisorption, CO-DRIFTs, quasi-in situ XPS, H-D exchange, and H₂-TPR characterization show that compared with Pt/γ-Al₂O₃, TiO₂ thin films on Pt/TiO₂/γ-Al₂O₃ do not change the dispersion of Pt particles, but can form new Pt-TiO₂ interactions. The hydrogenation performance of cyclohexylbenzene was improved by increasing the electron density and the proportion of planar active sites on the surface of platinum and reducing the energy barrier of hydrogen spillover. The research provides theoretical support for further bicyclohexane organic liquid hydrogen storage reagent development. The relevant metal-support interaction regulation strategy can be applied to the development of efficient catalysts for other aromatic molecules hydrogenation.