The traditional process uses concentrated sulfuric acid and solid acid SA as a catalyst to synthesize methyl laurate. Although the conversion rate reaches 98%, the concentrated sulfuric acid corrodes the equipment and pollutes the environment. However, the preparation process of SA catalyst is complicated, the cost is high, and the industrial application is difficult. The sulfonated DNW-1 resin is used to catalyze the synthesis of methyl laurate, but the sulfonated DNW-1 resin catalyst is used to catalyze the synthesis of methyl laurate with a large amount of catalyst and a long reaction time, and the resin is easily carbonized after the reaction, resulting in deactivation. Synthesis of methyl laurate with functionalized silica gel supported zinc acetate catalyst, the esterification rate is low, which is not conducive to industrial production. In this paper, cerium phosphotungstate was used as catalyst, and the influence of catalyst dosage, reaction time and catalyst recycling on the esterification reaction was studied under the condition of reaction temperature 67℃ and acid-alcohol molar ratio 1:15.
Reagents and instruments
Anhydrous methanol, analytically pure, Tianjin Fengchuan Chemical Reagent Technology Co., Ltd.; lauric acid, analytically pure, Tianjin Damao Chemical Reagent Factory; phosphotungstic acid, analytically pure, Langfang Greety Chemical Co., Ltd.; cerium chloride, Analytical pure, Baotou Jingrui New Material Co., Ltd. SpectrumGX Fourier transform infrared spectrometer; X-ray diffractometer; DF-101S collector type constant temperature heating magnetic stirrer, Zhengzhou Dufu Instrument Factory; SHB-3 circulating water multi-purpose vacuum pump, Zhengzhou Dufu Instrument Factory.
Preparation of cerium phosphotungstate catalyst
Accurately weigh the solid phosphotungstic acid and cerium chloride solution according to the ratio of 1:1, add a certain amount of ethanol, control the pH of the solution <1, stir, heat to reflux, react for 2 hours, distill under normal pressure, age and crystallize, Filtration gave crystalline CePW12O40·nH2O catalyst.
Esterification reaction
Put lauric acid and anhydrous methanol into the flask according to the ratio of substances of 1:15, add cerium phosphotungstate with 7% of the mass of lauric acid as a catalyst, and react for 4 hours at a reaction temperature of 67°C. After the reaction, the unreacted methanol was dried and filtered to obtain anhydrous methanol as a reagent for the next reaction; the methyl laurate in the flask was separated from the solid cerium phosphotungstate catalyst by passing through, the upper layer was methyl laurate, the lower layer It is solid cerium phosphotungstate as a catalyst for the next reaction.
