Hierarchical pore SBA-15 molecular sieve and preparation method thereof

The invention provides a hierarchical pore SBA-15 molecular sieve and a preparation method thereof, and the preparation method comprises the following steps: dissolving P123, a pore-enlarging agent and inorganic acid in water to obtain a mixed solution, adding a silicon source, and hydrolyzing in the mixed solution to obtain a hydrolysate and a mother solution; repeating the following operations: performing ethanol removal treatment on the mother liquor obtained in the previous step, then supplementing P123, a pore-enlarging agent and inorganic acid, dissolving, adding a silicon source, and hydrolyzing again to obtain a solid and mother liquor again; and S3, combining the hydrolysates obtained in S1 and S2, adding a mother solution, carrying out hydrothermal crystallization on the combined solid product, drying and roasting the crystallized product to obtain the hierarchical porous SBA-15 molecular sieve. The preparation method disclosed by the invention is high in synthesis efficiency, low in cost and less i