New process for producing methyl carbamate by urea low-pressure homogeneous catalysis method

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New process for producing methyl carbamate using urea low-pressure homogeneous catalytic method Methyl carbamate (MC) is an intermediate for pesticide synthesis, and its derivatives are increasingly used as herbicides and insecticides. At present, the existing MC synthesis methods at home and abroad mainly include methyl chloroformate method, isocyanic acid method, electrolytic formamide method and urea method, etc. However, the first three methods have the problems of high cost and large equipment investment, and some raw materials and solvents are highly toxic. Domestic companies have used the urea alcoholysis method to produce MC, but they were forced to stop because the urea conversion rate was too low, the process conditions were harsh, the reaction time was too long, and the cost was too high compared with the phosgene method. It is reported that the urea low-pressure homogeneous catalytic method for the production of methyl carbamate pilot project jointly developed by China University of Petroleum and Shandong Dongying Kangrui Petrochemical Co., Ltd. has recently passed the technical appraisal organized by the Shandong Provincial Department of Science and Technology. Compared with the traditional MC production process, the raw materials used in the new process are non-toxic, low-corrosion, simple equipment, and low production costs. At present, the homogeneous catalytic method production MC unit built by Kangrui Petrochemical Company using this new process has been running smoothly for one year. The production reaction conditions of this process are mild, which effectively solves the problem of high temperature decomposition of urea that has not yet been solved in the world, and the product yield is high. ； The product is purified by vacuum stripping distillation, with a high extraction rate and a purity of over 99%. In response to the problems existing in the urea alcoholysis process, China University of Petroleum has researched and developed a new production process for the production of methyl carbamate using urea's low-pressure homogeneous catalytic method. It uses soluble neutral catalysts and high-boiling point solvents, and adopts a homogeneous catalytic system. * * Increases the reaction rate of MC produced by the reaction between urea and methanol, and prevents MC from continuing to undergo alcoholysis to produce dimethyl carbonate as a by-product. ； The addition of an effective solvent not only inhibits the decomposition of urea, but also effectively squeezes out the generated NH3 from the reaction system, shortens the reaction time, and improves the conversion rate.