Tetraazamacrocycle complexes of Cu(II) and VO(IV) exchanged in the interlayers of montmorillonite clay: Heterogeneous catalysts for the aerobic oxidation of styrene

A series of new heterogeneous catalysts were obtained by direct incorporation of tetraazamacrocycle metal [copper(II) and oxovanadium(IV)] complexes into the interlayer of a montmorillonite through the exchange method, which were characterized by XRD, FT-IR, diffusion reflection UV–visible, ICP-AES, SEM, TG, and XPS. Characterizations suggest that tetraazamacrocycle metal complexes were introduced into K10-montmorillonite matrix. The synthesized heterogeneous catalysts exhibited great activity and good epoxidative selectivity in epoxidation of styrene when using air as oxidant. Furthermore, the catalyst was conveniently separated from the reaction system and could be reused at least two times with evident loss of activity and selectivity. However, it could be reused for the third time without significant loss of activity and selectivity.

Graphical abstractA series of new heterogeneous catalysts [M{Me4(Et)2[14]tetraneN4}-MT (M = V(IV) and Cu(II))] were successfully prepared. Heterogeneous catalysts were active and showed good epoxidative selectivity for the epoxidation of styrene, using acetonitrile as solvent and air as oxidant.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of new heterogeneous catalysts [M{Me4(Et)2[14]tetraneN4}-MT (M = V(IV) and Cu(II))] were successfully synthesized. ► Characterized by XRD, FT-IR, UV–vis, ICP-AES, SEM, TG, and XPS. ► The heterogeneous catalysts were active and showed good epoxidative selectivity.