Kinetic modeling of benzoic acid esterification using functionalized silica gel

ABSTRACT

In our study, we synthesized two types of solid acid catalysts. Silica gel with a particle size of 0.063–0.2 mm was silanized first at reflux (S1) and second at room temperature (S3) using (3-mecaptopropyl)trimethoxysilane in toluene, and further oxidized with H₂O₂, and methanesulfonic acid. Characterization of the synthesized catalysts was performed using adsorption/desorption of nitrogen (BET), Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Both catalysts were used in esterification reactions of benzoic acid with methanol. All reactions were performed in a batch reactor at temperatures, ϑ = 55, 60, and 64.5°C, stirrer speed, f_s = 400 min⁻¹, and catalyst loading, m = 5, 10, and 15 g. The concentration of produced methylbenzoate was determined by HPLC. The study was supplemented with a kinetic study of the reaction. First-order kinetics was confirmed for this esterification reaction. Using catalyst S1, higher conversion was reached, while catalyst S3 is much more suitable for reuse.

KEYWORDS:

• Benzoic acid
• catalyst characterization
• esterification
• heterogeneous catalysis
• kinetics