Hydrodesulfurization Studies on SBA-16 Supported Molybdenum Hydrotreating Catalysts

Abstract

Well ordered SBA-16 mesoporous silica with characteristic pore structure and spherical cavities was synthesized by established procedures. Mo, Co–Mo, and Ni–Mo catalysts were supported on SBA-16 mesoporous silica. The support and catalysts were characterized by low angle as well as wide angle X-ray diffraction (XRD), transmission electron microscopy (TEM), and pore size distribution measurements. The XRD, TEM, and pore size distribution indicated that an ordered mesopore structure with spherical cavities was obtained in the support and the same structure is retained after addition of Mo and Co or Ni. The wide angle XRD measurements indicated that molybdenum is well dispersed up to 8 wt % Mo loading in the oxide precursors. Surface area analysis indicated that Mo is dispersed as a monolayer both in the oxide and sulfided states, whereas oxygen chemisorption measurements confirmed these high dispersions. The temperature programmed reduction (TPR) profiles displayed a two peak pattern and indicated that MoO3 is not completely reduced at all the Mo loadings studies. However, the promoter increased the reducibility of molybdenum oxide. Thiophene hydrodesulfurization and cyclohexene hydrogenation activities showed a maximum at 8 wt % Mo and 3 wt % Co or Ni loading. The oxygen chemisorption correlated well with the two catalytic functionalities. SBA-16 supported Mo and Co–Mo catalysts showed superior activities compared to SBA-15 and γ–Al2O3 supported analogues of comparable composition.