Characterization and Catalytic Performance of Modified SBA-16 in Liquid Phase Reaction

Abstract

A new mesoporous silica SBA-16 (called SP-16) was prepared by the direct hydrothermal method using Pluronic F127 (triblock copolymer; EO106PO70EO106) as surfactant and TEOS (tetraethyl orthosilicate) as silica source. The catalyst property of the SBA-16 was attained by loading the STA (Silicotungstic acid) active compound. The loading contents of STA were determined between 5 % and 40 % based on weight ratio of W and Si (W/Si). Catalytic activities and sustainability of SP-16 (10-20 %, W/Si) catalysts were determined by esterification (liquid phase reaction methanol and acetic acid) reactions at 343-353K, under autogenic pressure, 1/1-1/2 feed molar ratios (methanol/acetic acid) and in the presence of 0.4 g catalyst in the semi-batch reactor for 6 - 24h. Acetic acid conversion values of 10 and 20 % catalysts with 1/1 molar ratio at the end of 24h were obtained as 32-52.9 % and 47-60 %, respectively. On the other hand, when 1/2 molar ratio at 353K was used, 20 % catalyst showed 82.2 % conversion. Moreover, a second reaction experiment of 10 % catalyst was also carried out in identical conditions in the presence of catalyst recovered after the first methyl acetate reaction. The first and second reaction results of 10 % catalyst indicated that catalytic activity and sustainability were preserved for both 6 and 24h analyses. The physical properties of the materials obtained were investigated by Nitrogen sorption at 77K (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy(FT-IR), Multiple Internal Reflection (DRIFT), Thermo-gravimetry/Differential thermal analysis(TG/DTA), Scanning electron microscope (SEM) and MAPPING analysis methods.