Hydrocracking of asphaltene with metal catalysts supported on SBA-15 Original Research Article

Hydrocracking of petroleum asphaltene with Fe and Ni catalysts loaded on SBA-15 supports has been carried out with a stainless autoclave at 573 K in pressurized H2. Asphaltene conversion with 10 wt.% Fe catalysts with average pore diameters of 4.5–15 nm increases with increasing pore diameter up to 12 nm and reaches about 70%, but levels off beyond this value. Maltene yield shows the same dependency on the diameter and the highest value of 40% at 12–15 nm. When metal loading in the Fe catalyst with the pore diameter of 12 nm is varied between 4 and 30 wt.%, asphaltene conversion and maltene yield are the largest at 4 and 10% Fe, respectively, indicating the presence of the optimum Fe loading for maltene formation. The use of the 10% Ni catalyst in place of the 10% Fe catalyst lowers the conversion slightly but improves selectivity to maltene greatly. This means that the Ni is suitable for selective conversion of asphaltene to maltene, probably because of higher hydrogenation ability. The X-ray diffraction (XRD) measurements of toluene-insoluble (TI) fractions recovered after hydrocracking and the analyses of SO2 evolved during the temperature-programmed oxidation (TPO) reveal the formation of Fe–S and Ni–S phases as surface species. The catalysis of asphaltene conversion by the sulfided forms is discussed.