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Abstract
Zirconium sulfate supported on SBA-15 (pore diameter about 6 nm) mesoporous molecular sieve was synthesized. Various techniques, such as nitrogen adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, and temperature-programmed desorption, were used to characterize the prepared catalysts. It was shown that the catalyst exhibited straight, parallel, and uniform channels, zirconium sulfate had been finely dispersed on the surface of SBA-15, and most of the zirconium sulfate species were located inside the pore channels. The catalyst contained two kinds of acid sites with different strengths. Zirconium sulfate supported on SBA-15 was used to catalyze the esterification of stearic acid with triethanolamine and recycling was used. The composition of esteramine was analyzed by reversed-phase high-performance liquid chromatography. The analytic results showed that the catalytic activity and selectivity of zirconium sulfate supported on SBA-15 in the esterification of stearic acid and triethanolamine was better than that of phosphorous acid, zirconium sulfate supported on MCM-41, and zirconium sulfate supported on SBA-15.
Keywords Zirconium sulfate * Mesoporous molecular sieve * SBA-15 * Stearic acid * Triethanolamine
Introduction
Esterquats have been known for a long time, and the earliest mentions in the open literature date back to die 1930s [I]. Esterquats, which are quaternary ammonium compounds with two long (C 16-Cl 8) fatty acid chains with two weak ester linkages, represent a new generation of fabric-softening agents, having replaced die dialkyldimethylammonium salts (e.g., DTDMAC and DSDMAC). This new generation of fabric-softening agents combines a good environmental profile with the structural features required for an effective fabric conditioner [2]. Most often, the esterquats are prepared by reacting triethanolamine (TEA) with fatty acids, followed by reaction with an alkylating agent to the corresponding quaternary. The esteramine is the mixture of mono-, di-, and tri-esteramine, but the ultimate performance of esterquats is related to die content of mono- and di-esterquat. Therefore, the synthesis of esteramine is the key step in the preparation of esterquats; in this step, the mono- and di-esteramine content should be increased.
The present paper centered on the study of the esterificatíon of stearic acid with TEA to prepare esteramine. Esterifícation of fatty acid with TEA has been performed by using homogeneous catalysts such as phosphorous acid, sodium methoxide, para-toluene sulfonic acid, sulfuric acid, and so on. But these...