Recyclable Cerium Phosphotungstate Catalyst

A method for the synthesis of methyl laurate by cyclic use of cerous phosphotungstate catalyst is proposed. This method does not produce acid waste water and solid waste. It is a green synthesis process. The steps of synthesis are as follows:

The ratio of lauric acid and anhydrous methanol was put into the reactor at 1:15. The catalyst was added to the lauric acid mass of 7-7.5% of the cerium phosphotungstate. The reflux reaction was 4 for 6 hours, and the methanol was recovered by vacuum distillation. The methyl laurate and the solid phosphotungstate catalyst were separated to get the methyl laurate product. The lower layer is cerium phosphotungstate catalyst, the lower layer solid phosphotungstate catalyst is dissolved in deionized water, the mass ratio of cerium phosphotungstate and deionized water is 1:1.5, the pH value <1 of hydrochloric acid mixing solution is added, and the filtration is removed from the hydrochloric acid, and the cerium tungstate water solution is obtained. The cerium phosphotungate solution is concentrated and crystallized, solid phosphotungstate as the catalyst for the next reaction, the conversion rate of lauric acid is over 97% each time using cerium phosphotungstate as a catalyst for the reaction of lauric acid and anhydrous methanol according to the above method.

In the reaction process, a small amount of carbon deposits are formed to cover the surface of the cerium tungstate catalyst and reduce the activity of the cerium tungstate catalyst, after each reaction, cerium phosphotungstate is used directly as the catalyst for the next reaction and the conversion rate decreases. The solid phosphotungstate was dissolved in deionized water, and the pH value of the solution was mixed with hydrochloric acid to remove the carbon product suspended in the cerium phosphotungstate solution. The cerium phosphotungstate solution was obtained by concentration and crystallization, and the solid phosphotungstate was directly connected as a catalyst for esterification. In the reaction of methyl laurate, the conversion rate of lauric acid is 97%, which is easy to realize industrial production.

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