Carbon The performance of sonochemical catalysts CoMoC(s) and CoMoAl(s), was investigated for hydrodesulphurization (HDS), using thiophene as a model compound. HDS experiments were carried out in a batch magnetically stirred reactor at atmospheric pressure and 163oC. The activity of these catalysts was compared with impregnation catalysts CoMoC(i) and CoMoAl(i). The activity increases with increasing molybdenum percent in CoMoC(s), CoMoAl(s) and CoMoC(i) but CoMoAl(i) shows an optimum thiophene removal percent in 12wt% molybdenum. The activity of CoMoC(s), CoMoAl(s) and CoMoC(i) reaches a saturation level when the amounts of cobalt larger than 3 wt% but in CoMoAl(i), a maximum around 3 wt% cobalt was seen. The sonochemically synthesized catalysts exhibit an HDS activity about two-fold higher than that of catalysts prepared by a conventional impregnation method over a wide range of molybdenum and cobalt loadings. The enhanced HDS activity of the sonochemically synthesized catalysts can be attributed to the improved dispersion of catalytically active species on the support, which is preserved up to high Mo loadings. The HDS selectivity of butane on sonosynthesized catalysts was found to be at least 5 times greater than that for impregnation synthesized catalysts.

The HDS selectivity of butane increases with increasing molybdene loading for all of the catalysts but reaches a saturation level at 3wt% in the case of increasing cobalt. As catalyst loading increases, an optimum thiophene degradation percent was achieved at 0.2gr catalyst content. In the case of 0.2gr catalyst loading, 24% molybdene and 4.5% cobalt content, the activity of CoMoC(s) is about 1.3 times greater than the activity of CoMoAl(s) and CoMoC(i) can eliminate thiophene about 1.5 times greater than the CoMoAl(i). The above reaction results, obtained using different catalysts, can be explained based on the surface properties of the catalysts, as characterized by XRD, SEM and TG-DTA analysis.