Selective oxidation of styrene to 1,2-epoxyethylbenzene by hydrogen peroxide over heterogeneous phosphomolybdic acid supported on ionic liquid modified MCM-41

• The solvent-free heterogeneous oxidation system is environmentally friendly.
• PMo/ILMCM-41 prepared by grafting shows outstanding reusability in reaction.
• Heterogeneous catalyst can easily separate by centrifugation after reaction.
• PMo/ILMCM-41 possesses hydrophilic and hydrophobic properties.
• PMo/ILMCM-41 can adsorb H2O2 and styrene simultaneously to improve the oxidation.

Styrene was selectively oxidized to 1,2-epoxyethylbenzene catalyzed by phosphomolybdic acid supported on ionic liquid modified MCM-41 using hydrogen peroxide as oxidant. The synthesized catalyst was characterized by XRD, FT-IR, and N2 adsorption–desorption analyses, and the results indicate that the sample retained mesoporous structure after ionic liquid-modified and immobilization of phosphomolybdic acid. Maximum activity was observed at a loading of 30 wt.% phosphomolybdic acid on ionic liquid modified MCM-41. Reaction conditions such as reaction time, temperature, amount of catalyst, and H2O2/styrene molar ratio were systematically optimized to obtain a maximum styrene conversion of 95.4%. 1,2-Epoxyethylbenzene selectivity of 90.2% when the reaction conditions were set to 3 h reaction time, 50 °C, 100 mg catalyst, and a H2O2/styrene molar ratio of 1.2. The heterogeneous catalyst is easily separated by centrifugation and was reused without deactivation after six runs.

The heterogeneous catalyst PMo/ILMCM-41 prepared by the grafting method shows outstanding reusability in the selective oxidation of styrene to 1,2-epoxyethylbenzene catalyzed by PMo/ILMCM-41 using H2O2 as oxidant. The amphiphilic catalyst can adsorb H2O2 and styrene from aqueous and organic phase simultaneously to solve the disadvantage of mass interface transfer limitation.Figure optionsDownload as PowerPoint slide