Mesoporous Al-incorporated silica-pillared clay interlayer materials for catalytic hydroxyalkylation of phenol to bisphenol F

Abstract

A series of mesoporous, Al-incorporated, silica-pillared clay (Al-SPCs) interlayer materials with different Al content were prepared in the presence of cationic surfactant by a structure-directing method. The catalysts' structure, texture, and acidic properties were determined using XRD, BET, SEM, TEM, FT-IR, NH₃-TPD and Py-IR, respectively. Characterization results showed that these materials possess mesoporous structures with large specific surface areas. The incorporated Al leads to the increase and redistribution of Brönsted and Lewis acid sites on SPC (silica-pillared clay). The Al-SPCs were used as catalysts for hydroxyalkylation of phenol to bisphenol F and gave a high product yield (95.4%) and selectivity (98.2%) to bisphenol F. Catalytic performance of the catalysts and characterization results proved that the catalytic activity of these catalysts depend on moderate acidity and the textural properties (specific surface areas), and the synergy of Brönsted and Lewis acids is key for the hydroxyalkylation of phenol to bisphenol F. The reusability of the catalysts was studied, and they can be easily recovered and reused at least six times without significant loss of their catalytic activities. Finally, a plausible mechanistic pathway was proposed.