| 摘要 |
A process for the preparation of a clay cracking catalyst comprises the steps of sequentially (1) treating a calcined clay with mineral acid, thereby dissolving at least part of the alumina in the clay, (2) adding to the acid-treated clay an amount of alkali metal silicate or silica gel sufficient to provide 20-95% of silica based on the dry weight of the clay, (3) adding a base in amount sufficient to reprecipitate the alumina dissolved by the acid in step (1), (4) separating the solid from the resulting mass, and (5) removing alkali metal ion from the separated solid by base exchange. Preferably the starting material is kaolin or halleysite which contain not more than 0,5% Fe2O3. Specified mineral acids are HCl, HNO3 and H2SO4. The base added to reprecipitate Al2O3 is normally NH4OH. Examples are given. |
