Development of functionalized heterogeneous catalyst in the synthesis of isobutyl acetate by esterification reactions

In this study, functionalized silica catalysts performances, as an alternative to the commercial Amberlyst-16 catalyst, evaluated in isobutyl acetate synthesis reaction. The catalysts functionalized with sulfuric acid, (3-Mercaptopropyl)trimethoxysilane (MPTMS) and Trimethylchlorosilane (TMCS) were characterized using FT-IR, N2 adsorption/desorption and XRD techniques. Surface area, pore size and pore volume of the catalysts were determined by N2 adsorption/desorption method. The presence of chemicals used in functionalization with FT-IR analyzes was proved by examining the bond structures. XRD analysis results showed that the crystal structure of the initial silica did not change after functionalization. Heterogeneous catalysts were used in the esterification reaction between acetic acid and isobutyl alcohol in stable reaction conditions (90 ºC temperature, 2 hours reaction time, 750 rpm stirring speed, 1:1 mole ratio). The reaction solutions were analyzed by gas chromatography and the conversion values were calculated and compared. Heterogeneous catalysts functionalized with in-situ and grafting methods. The highest acetic acid conversion was obtained with silica catalysts which functionalized with grafting method by using 2M sulfuric acid (66.9%) and which functionalized with in-situ method by using TMCS (64.8%). While sulfuric acid increases the acidity by adding sulfate ions to the catalyst, TMCS imparts hydrophobic properties to the catalyst.