Direct synthesis of Mn-Ti-SBA-15 catalyst for the oxidation of ethylbenzene

摘要

Bimetallic Mn-Ti-SBA-15 materials were prepared by direct hydrothermal method with appropriate pH adjustment. The materials were characterized by low and wide angle XRD, N2 sorption studies, DRSUV-Vis, XPS, ESR, SEM and TEM. The XRD and BET results clearly demonstrated the incorporation of manganese and titanium species in the SBA-15 framework without affecting the mesoscopic nature of the material. The oxidation state and coordination environment of the active sites were confirmed by DRSUV-Vis, XPS and ESR. The results revealed that Mn~(2+) is in octahedral geometry whereas Mn~(3+) and Ti~(4+) are in tetrahedral coordination in the SBA-15 framework. The O1s XPS spectrum well established the framework incorporation of manganese and titanium species. The catalytic activity of Mn-Ti-SBA-15 materials was evaluated in the oxidation of ethylbenzene with TBHP as the oxidant under optimized reaction condition. It was found that Mn-Ti-SBA-15(50) catalyst showed high catalytic activity with a rate constant of 7.155 x 10~(-3) min~(-1). The synergetic effect of Mn~(2+)/Mn~(3+) and Ti~(4+) sites in Mn-Ti-SBA-15 is a promising catalyst for the oxidation of ethylbenzene and other alkylbenzenes.