The silica-alumina catalysts for cracking of petroleum were prepared by various methods, such as co-precipitation, stepped precipitation, mixing of gels, impregnation and others, to investigate the relations between activities and preparing conditions of catalysts. Among these methods, the most active catalyst was prepared by means of stepped precipitation. The co-precipitated catalyst varies exceedingly its activity with pH of mixed solution, and the mixed-gel catalyst has poor selectivity in spite of its high activity.
In addition, the authors mentioned some considerations on the reaction mecha-nisms of catalytic cracking of petroleum.
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