Characterization and catalytic activity of the AlMCM-41 prepared by a method of gel equilibrium adjustment

Abstract

Aluminum-containing MCM-41 (AlMCM-41) was prepared by a method of gel equilibrium adjustment, in which the pH of the gel was adjusted to 11 or 10 using acetic acid during the synthesis in order to shift the equilibrium into the formation of mesoporous materials, and its structure, solid acidity, and catalytic activity were measured. The material thus obtained had a clear hexagonal array of mesopores with a Si/Al₂ molar ratio of 17 to 16; the maximum concentration of aluminum. More than 70% of aluminum atoms had a tetrahedral configuration. Test reaction for the acidity, TPD of ammonia and IR of adsorbed pyridine showed that it had an acidity almost similar to usual silica-alumina. The AlMCM-41 showed a high and durable activity in the isopropylation of 2-isopropylnaphthalene, which was not observed in the HY zeolite and the usual silica-alumina, but no shape-selectivity for the product formation was observed.