Synthesis, characterization and catalytic activity of AlSBA-3 mesoporous catalyst having variable silicon-to-aluminum ratios

Abstract

AlSBA-3 mesoporous catalytic materials with different Si/Al ratios were synthesized; Al was incorporated in the mesoporous structure using the post-synthesis method. The catalysts were characterized using different techniques and methods, such as: XRD, BET, ICP, SEM microcopy, TEM microscopy and 27Al MAS NMR. Acidic properties were estimated by adsorption-desorption using pyridine as probe molecule followed by FTIR spectroscopy. FTIR studies showed the acidic properties with aluminum incorporation; lower Si/Al ratios increase the number of acid sites. Temperature-programmed desorption of pyridine showed that AlSBA-3 has a higher number of strong acid sites compared to other mesoporous materials such as Al-MCM-41, Al-SBA-15 and Al-SBA-16. It has been observed by 27Al MAS NMR spectroscopy, that the materials exhibit peaks with shifts of 50 ± 2 ppm and weak signal at 0 ± 2 ppm. The AlSBA-3 materials used as a catalyst showed high performance in the acid-catalyzed dehydration of isopropanol.