Synthesis, characterization of Cr-HMS and the application in catalytic oxidation

A series of chromium containing mesoporous molecular sieves Cr-HMS with various chromium content were synthesized and characterized, It was found that the incorporation of chromium into HMS leads to the decrease of their structural order as well as the uniformity of their mesopores. The catalysts exhibit good activities for both the oxidation of cyclohexane and the hydroxylation of benzene, The conversions of benzene and cyclohexane versus the chromium content in the catalysts show typical volcano shapes. In the case of the oxidation of cyclohexane which is easier to be oxidized, pretreating Cr-HMS by reduction in H-2 can not only retain its relatively high activity, but also acquire a relatively high stability.