Oxidative Desulfurization over Molybdenum-containing MCM-41

Two series of molybdenum-containing MCM-41 catalysts were prepared for oxidative desulfurization of dibenzothiophene (DBT) using t-butylhydroperoxide (TBHP) as the oxidant. The electronic properties, pore dimension and hydrophilic properties of the catalysts were studied by XRD, BET, and IR spectrometry. The Mo-Al2O3 catalyst and TiMCM-3% were also studied for comparison. The two series of MCM-41 zeolite with MoO3 in the framework or impregnated on the surface exhibited considerable activities at low MoO3 content and both were far better than the Mo-Al2O3 catalyst, but had lower activities as compared to the TiMCM-3% catalyst. The catalysts with the highest activity were evaluated in a fixed-bed reactor. The concentration of DBT in model diesel upon oxidative desulfurization was successfully reduced from 5000 ppm to less than 150 ppm, but the catalysts were deactivated very last. The probable reason was the high affinity of DBTO2 to the MCM-41 skeleton, especially to MoO3. The catalysts could restore most of its original activity by treating with alcohol.