Preparation method for modified molecular sieve and modified molecular sieve-containing catalytic cracking catalyst

A preparation method of a modified molecular sieve, wherein the preparation method comprises:

• mixing a molecular sieve slurry, a compound solution containing Group IIIB metal ion of the periodic table, an organic complexing agent, a dispersant and a precipitating agent to obtain a mixed slurry containing the precipitate of Group IIIB element of the periodic table and the molecular sieve, followed by drying and optionally calcining, to obtain the Group IIIB element-modified molecular sieve, wherein the weight ratio of the Group IIIB element in terms of oxide to the molecular sieve on dry basis is 0.3 to 10:
• 100, the molar ratio of the organic complexing agent to the Group IIIB metal ion is 0.3 to 10:
• 1, and the molar ratio of the dispersant to the Group IIIB metal ion is 0.2 to 16:
• 1;
• wherein the mixing of the molecular sieve slurry, the compound solution containing the Group IIIB metal ion of the periodic table, the organic complexing agent, the dispersant and the precipitating agent is carried out by uniformly mixing the compound solution containing the Group IIIB metal ion of the periodic table, the organic complexing agent, the dispersant with the molecular sieve slurry, adding the precipitating agent and stirring for at least 10 minutes.