Abstract
Abstract A series of active and selective MCM-41 supported catalysts have been successfully prepared and used for bioderived glycerol esterification with acetic acid to produce fuel additives. In the synthesis of MCM-41, an acidic hydrothermal synthesis route was used, and silicotungstic acid (STA) and zirconia (ZrO2) were added to the catalyst structure by wet impregnation. X-ray diffraction, nitrogen adsorption-desorption methods, scanning electron microscopy with energy-dispersive spectroscopy, and inductively coupled plasma-mass spectrometry analysis were used for characterizations of the catalysts. Diffuse reflectance infrared Fourier transform spectroscopy analyses of pyridine-adsorbed catalysts owns Lewis and Brønsted acidity hosting in one, which promotes the esterification reaction of glycerol into glycerol esters with high selectivity. Esterification of glycerol reactions were performed at temperature intervals of 105°C–200°C, with an amount of catalyst equal to 0.5 g, and glycerol/acetic acid molar ratio of 1:6 in a stirred autoclave reactor operated batchwise. STA and ZrO2-impregnated MCM-41 catalysts showed better performance with a complete glycerol conversion and high selectivity to triacetin.
Highlights
Biodiesel is a renewable clean energy produced by the transesterification of vegetable oils with methanol or ethanol in the presence of alkaline catalyst [1]
The X-ray diffraction (XRD) patterns of ZrO2 and silicotungstic acid (STA) impregnated catalysts showed much wider d(100) values than the corresponding peak observed for pure MCM-41
Liquid phase esterification reaction of glycerol with acetic acid has been studied in the presence of STA and ZrO2 incorporated mesoporous MCM 41 catalysts
Summary
Biodiesel is a renewable clean energy produced by the transesterification of vegetable oils with methanol or ethanol in the presence of alkaline catalyst [1]. One of the Esterification reactions can be performed in the presence of both homogenous and heterogeneous acid catalysts. There are only a few studies dealing with the esterification of glycerol with acetic acid. A variety of catalysts such as heteropolyacids (HPA) immobilized zeolites, ion exchange resins, and niobic acid have been used in esterification reactions [10,11,12,13,14,15]. Our previous study was about the esterification of glycerol with acetic acid over ion exchange resins: Amberlyst-15, Amberlyst-16, Amberlyst-36, Amberlite IR-120, and Relite EXC8D [11]. Previous studies showed that the change in product selectivity is attributed to reaction temperature, reaction time, and glycerol to acetic acid molar ratio [11]. Oktar: Value-added chemicals from esterification of waste glycerol 129
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