Preparation and catalytic activity of P4VP–Cu(II) complex supported on silica gel

Micron-sized silica gel particles were chemically modified on their surfaces with the coupling agent, γ-methacryloxypropyl trimethoxysilane (MPS), double bond was introduced onto the surfaces of silica gel particles, and the modified particles MPS–SiO2 were obtained. Then, poly(4-vinylpyridine) (P4VP) was grafted from the silica gel surfaces, and grafting particles P4VP/SiO2 was prepared. Finally, the coordination between grafted P4VP and cupric ions Cu2+ was performed, and the supported complex Cu(II)–P4VP/SiO2 was obtained. The grafting particles P4VP/SiO2 and the supported complex Cu(II)–P4VP/SiO2 were characterized with infrared spectra (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Cu(II)–P4VP/SiO2 was used as a catalyst for the oxidation of ethyl benzene into acetophenone with molecular oxygen under ordinary pressure. The experimental results show that the supported complex Cu(II)–P4VP/SiO2 can be successfully prepared via grafting polymerization of 4VP and coordination between the grafted P4VP and cupric ions Cu2+. In oxidation of ethyl benzene into acetophenone by molecular oxygen under ordinary pressure, the supported complex Cu(II)–P4VP/SiO2 displayed high catalytic activity and excellent catalytic selectivity up to more than 98% for the transformation of ethyl benzene to acetophenone.

Graphical abstractThe catalyst Cu(II)–P4VP/SiO2 was used in the catalytic oxidation of ethyl benzene to acetophenone by molecular oxygen. The yield of acetophenone is rapidly enhanced with the increase of the used amount of catalyst Cu(II)–P4VP/SiO2, indicating its high catalytic activity.Figure optionsDownload full-size imageDownload as PowerPoint slide