Supported molybdenum-sulfur cluster compounds as precursors for HDS catalysts

The catalytic activity in the hydrodesulfurization (HDS) of thiophene at 370°C was investigated on ex complex catalysts made from the ammonium and sodium, cobalt, and nickel salts of the [Mo3S13]2- cluster anion supported on ¿-Al2O3 or SiO2 and compared with that of a classic NiMo/Al2O3 catalyst. Samples were characterized by infrared (IR), Raman, UV/VIS, and thermogravimetric measurements. The samples were activated in He at 110 or 400°C, and H2S/H2 (10% of H2S in H2) was introduced at room temperature, 110 or 400°C. Furthermore, the NiMo/Al2O3 catalyst was activated directly from room temperature to 400°C in H2S/H2. The initial sulfidation temperature (400°C or room temperature) did not influence the activity of the ex complex catalysts, whereas the classic NiMo/Al2O3 catalyst was very sensitive to the initial temperature of the sulfidation. The sample treated at 400°C and sulfided starting at room temperature exhibited a much higher activity than the sample to which H2S/H2 was added at 400°C. Thermal treatment of the catalyst in He at 110°C as opposed to 400°C led to a lower activity of the ex complex catalysts and to a higher activity of the NiMo/Al2O3 catalyst. Catalyst samples made from Na2[Mo3S13]·5H2O/Al2O3 were slightly less active than the samples obtained from (NH4)2[Mo3S13]·H2O/Al2O3