Hierarchically Porous (Alumino)Silicates Prepared by an Imidazole-Based Surfactant and Their Application in Acid-Catalyzed Reactions.

Abstract

In this work, we developed a novel strategy to synthesize porous (alumino)silicate materials using a single structure-directing agent composed of an imidazole unit with a hydrophobic tail, namely, 1,2-dimethyl-3-hexadecyl-1H-imidazol-3-ium bromide (C16dMImz). A wide range of products such as ordered mesoporous silicas, layered silica–alumina, and hierarchically porous mordenite zeolite were obtained by varying synthesis parameters such as temperature and aluminum concentration. By changing crystallization temperature, we could control the degree of silica condensation and tune the textural and morphological properties of the final materials. By varying the aluminum concentration in the gel, we can obtain mesoporous amorphous silica–alumina or crystalline mordenite zeolite with, respectively, weak and strong Brønsted acid sites. Obtained acidic silica–alumina materials displayed promising performance in catalytic reactions of linear paraffin hydroisomerization and Friedel–Crafts alkylation of benzene with benzyl alcohol.