Abstract: In order to investigate the effect of different mesoporous supports on the catalytic performance of heterogeneous complexes, three representative siliceous mesoporous materials (SiO2, MCM-41, and SBA-15) were selected as supports to immobilize the same chromium salen Schiff base complex. The coordination structure and textural properties of the heterogeneous complexes were characterized by various physico-chemical measurements such as FT-IR, UV-Vis, XRD, N2 adsorption, and elemental analysis. The heterogeneous complexes were effective catalysts for the selective oxidation of benzyl alcohol to benzaldehyde using 30%H2O2 as the oxidant, and they all exhibited much better catalytic performance than their homogeneous analogues. Simultaneously, the catalytic performance of the heterogeneous complexes was also closely related to the used supports, and the complex Cr(salen)/MCM-41 exhibited the best catalytic performance. Under the optimal reaction conditions, the conversion of benzyl alcohol could reach 52.5% with 100% of selectivity for benzaldehyde. In addition, the catalytic performance was remained after being reused 4 times.

Key words: chromium, N, N-bis(salicylideneamino)ethane (salen) ligand, mesoporous support, heterogeneous complex, Schiff base, benzyl alcohol, selective oxidation, benzaldehyde