Non-crystalline mesoporous aluminosilicates catalysts: Synthesis, characterization and catalytic applications

Non-crystalline mesoporous aluminosilicate materials were synthesized using citric acid as a pore-forming agent. The amount of Al incorporated in the mesoporous framework could be controlled by adjusting the addition of citric acid. The analytical techniques of N2 adsorption/desorption and transmission electron micrographs (TEM) had been applied to characterize the textural properties of the new mesoporous materials. 27Al nuclear magnetic resonance (27Al MAS NMR) and temperature-programmed desorption (NH3-TPD) of ammonia techniques suggested that most of the Al was present in tetrahedral coordination and imparted acid sites. Tert-butylation of phenol was carried out to evaluate the catalytic activity of the novel mesoporous aluminosilicate catalysts. In addition, the influence of various reaction parameters such as reaction time, reaction temperature, and reactant ratio and weight hourly space velocity were also studied. At the reaction temperature of 418 K, phenol conversion of 92.3% and 2,4-di-tert-butyl phenol selectivity of 45.7% over the optimum novel catalyst (CA-32) were observed, which was much higher than those over the conventional mesoporous Al-MCM-41 catalyst.