A mesoporous aluminosilicate prepared by simply coating fibrous γ-AlOOH on the external surface of SBA-15 for catalytic hydrocarbon cracking

Abstract

A binary SiO₂/Al₂O₃ composite with fibrous γ-alumina coating on the external surface of SBA-15 has been synthesized by simply mixing SBA-15 with fibrous boehmite sol, followed by aging and calcination. The textural and acidic properties of the resultant material were characterized by various techniques, i.e. powder X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared (IR) spectroscopy, N₂ adsorption/desorption, nuclear magnetic resonance (NMR) spectroscopy, and temperature programmed desorption of ammonia and ethanol (NH₃-TPD and EtOH-TPD). Coating fibrous γ-alumina stabilized the SBA-15 structure against collapse under critical steaming conditions (800 °C and 4 h) allowing for the facile synthesis of mesoporous aluminosilicate. The migration of aluminum and silicon between the alumina and SBA-15 zones led to the formation of Al–OH–Si with weak acidity which served as the active sites with excellent catalytic performance in the cracking of 1,3,5-triisopropyl benzene (TIPB).