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[摘要]：Transesterification is a widely used reaction in the chemical industry. Currently, industrial-scale transesterification is primarily performed via homogeneous catalysts. Because of downstream separation issues, there is a need for effective heterogeneous catalysts. However, heterogeneous catalysts introduce the drawback of mass-transfer limitations into the reaction system. The substrates associated with transesterification form a three-phase system that is inherently immiscible in each other with liquid/liquid/solid (L/L/S) interfaces. This study was conducted to ascertain the behavior of a solid catalyst that has amphiphilic properties in the transesterification system. It was hypothesized that the amphiphilic catalyst, depending upon its degree of polymerization, would orient itself at the interface of the two immiscible liquids, forming an emulsion. The catalytic active site, in the mean time, would catalyze the transesterification reaction. In this study, the catalytic aspects of the titanium-isopropoxide-based inorganic dendritic polymers were investigated. Titanium isopropoxide catalysts with varying degrees of polymerization were developed by sol-gel water condensation. The degree of was controlled by the amount of water addition. Five forms of catalysts with varying degrees of polymerization were subjected to transesterification at varying temperatures and time intervals. In this experiment, soybean oil was used as the triglyceride. Isopropanol and titanium isopropoxide were used as the catalyst precursors. The highest yield of 41.56% of propyl esters was obtained at 200 degrees C after 3 h with 1% (w/w) of the monomeric form of the catalyst. The behavior of the dimeric and higher forms was highly correlated with reaction temperatures and residence times. |
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