Micropore-enriched CuO-based silica catalyst directly prepared by anionic template-induced method and its boosting catalytic activity in olefins epoxidation

Micropore can efficiently tailor the diffused rate of reactant molecule in heterogeneous catalysis and enhance collision frequency with catalytic active sites, hence increasing catalytic properties. In this study, boosting catalytic activity for olefins epoxidation was obtained using micropore-enriched CuO-based silica catalyst. This special catalyst incorporated with highly-dispersed copper oxides was directly fabricated with anionic surfactant chelating Cu²⁺ as the template. Dispersed CuO species were in situ produced and encapsulated in the channels of mesoporous silica, avoiding the repeated calcination in the conventional modification process. Meanwhile, massive micropores (ca. 1.6 nm) were directly formed. In addition, to receive optimal catalytic performance, controllable amounts of Cu²⁺ were employed for modifying anionic micelles. This obtained catalyst exhibited obviously stronger reducibility and better dispersity of CuO in comparison with the post-impregnated sample, more interestingly, the introduction of Cu²⁺ in the assemble process improved structural properties of silica. In addition, a proper loading (Cu/Si = 4.34%) of CuO was found to be preferable in the catalytic process. Finally, catalytic results revealed that the micropore-enriched catalyst exhibited obviously higher catalytic activity as compared to the mesoporous catalyst, and its further applications in various olefins epoxidation were preferable.