Selectively catalytic epoxidation of styrene with dry air over the composite catalysts of Co-ZSM-5 coordinated with ligands

The catalytic activity of composite catalysts of Co-ZSM-5 coordinated with ligands for the selective epoxidation of styrene with dry air was studied in the temperature range of 50–100 °C under atmospheric pressure. The catalyst Co-ZSM-5(L2) containing vanillic aldehyde salicylhydrazone (L2) exhibited the best activity and selectivity for the epoxidation; e.g. 96.9 mol% of styrene conversion with an epoxide selectivity of 94.0% as well as a low benzaldehyde selectivity of 3.1% was attained when the concentration of styrene in solvent was 0.2 mmol/g. Over the composite catalysts of Co-ZSM-5 coordinated with ligands, the overall selectivity of the epoxide (styrene oxide) plus the corresponding isomer (phenylacetaldehyde) was higher than 90%. It is noteworthy that the use of TBHP in small amounts efficiently initiated the reaction, and the lack of TBHP led to a low conversion and selectivity.

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