Characterization and Catalytic Performance of Al-SBA-15 Catalyst Fabricated Using Ionic Liquids with High Aluminum Content

Abstract

This study involved the fabrication of a set of aluminum ion-grafted SBA-15 utilizing ethylenediamine and trimethylamine ionic liquids. The primary objective was to examine the impact of the fabrication environment on the physicochemical characteristics of the catalysts. Comprehensive characterization of the Al-SBA-15 catalysts was conducted using various techniques, including XRD, FTIR, surface area, pyridine FTIR, 27Al-NMR, TGA, HRTEM, and FESEM, to analyze their physicochemical characteristics. Furthermore, the acidic characteristics were examined by conducting potentiometric titration in a nonaqueous solvent and employing FTIR spectroscopy to analyze the chemisorbed pyridine. The effectiveness of the fabricated acid materials was evaluated by testing their performance in acetic acid esterification with butanol. The findings obtained reveal that mesostructured SBA-15 remains intact following the successful inclusion of Al3+ ions into the silica frameworks. Additionally, a remarkable enhancement in the existence of both Bronsted and Lewis acid centers was noted due to the grafting process of Al3+ ions. At temperatures of 80 °C and 100 °C, the reaction in Al-SBA-15(T-120) proceeds swiftly, reaching approximately 32% and 38% conversion, respectively, within a span of 110 min. The excellent catalytic performance observed in the esterification reaction can be attributed to two factors: the homogeneous distribution of Al3+ ions within the SBA-15 frameworks and the acidic character of Al-SBA-15. The findings further indicate that the grafting process for incorporating Al3+ ions into the silica matrix is more efficient.