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Cs2.5H0.5PW12O40 supported on palygorskite (CsHPW/Pa) were synthesized and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. CsHPW inside CsHPW/Pa was retained intact Keggin anion and highly and uniformly supported on the fiber of Pa, which performed stable catalytic activity for esterification of oleic acid with ethanol. Under optimum conditions, the following amounts were reached: 20%CsHPW/Pa catalyst, 80°C, 8 h, molar ratio (ethanol to oleic acid) 10:1, catalyst amount 8 wt% (in relation to the oleic acid mass), removal water agents amount 50 g/mol (basis on the oleic acid molar), and the conversion of oleic acid reached 73%. [ABSTRACT FROM PUBLISHER]

Esterification of oleic acid with methanol was investigated using tungstophosphoric acid (H3PW12O40) immobilized on the 3-aminopropyltriethoxysilane (H2N(CH2)3Si(OC2H5)3) functionalized palygorskite. Among different loading catalysts, 15% (w/w) H3PW12O40 immobilized onto functionalized palygorskite showed stable and substantially high activity with about 90% oleic acid conversion. Immobilized catalysts were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and temperature programmed desorption of NH3 for their surface element compositions and chemical states, crystallization, and acid strength, respectively. Characterization results indicated that H3PW12O40 was chemically and uniformly dispersed on modified palygorskite. [ABSTRACT FROM PUBLISHER]