The Development Of Highly Efficient Production Process Of 1,3-dimethy1-2-imidazolidinone

1,3-dimethy1-2-imidazolidinone(DMI)as a polar aprotic specialty solvent has outstanding solvency to both organic compounds(including some macromolecular polymers)and inorganic compounds,and has excellent properties such as low toxicity,acid and alkali resistance.Therefore,it is widely used in the production and processing of various chemical products and other industrial products.The synthesis processes of DMI reported at home and abroad have many deficiencies,such as expensive raw materials,high toxicity,harsh reaction conditions,and serious environmental pollution.Therefore,the development of an efficient,low-cost,relatively mild process conditions and clean and environmental friendly production process is of great significance to its industrial production.In this paper,the two main industrial processes used by "formic acid method" and"hydrogenation method" are optimized based on the requirements and conditions of industrial production.First of all,in combination with previous related research work of my research group,the key intermediate 2-imidazolidinone was successfully prepared with dimethyl carbonate and ethylenediamine as the main raw materials,and the yield was higher than 94%.Secondly,in the process route for the preparation of DMI by formic acid method,the process route was investigated and optimized through three aspects of reaction conditions,material ratios,and post-processing,and the optimum process conditions for the preparation of DMI by the formic acid process were determined as follows:MI,formic acid,and formaldehyde as raw materials,the reaction temperature is 120 ?,the reaction time is 12 h,and the post-treatment process is purified by ether extraction.Under these conditions,the yield of 1,3-dimethyl-2-imidazolidone can reach more than 89%.Thirdly,in the process of preparing DMI by hydrogenation process,the production process using MI,formaldehyde,and hydrogen as raw materials is optimized.Firstly,the catalyst needed for the reaction was screened and the preparation process was optimized(focusing on the solid acid catalyst).It was determined that the Gamma-Al2O3 loaded with sulfuric acid as the solid acid catalyst can obtain the target product with a higher yield(above 80%).The catalyst was characterized and tested.Based on this research,this process route was in-depthly explored and optimized through many aspects such as reaction conditions and material ratios,and the better process conditions were determined.The better process conditions were as follows:MI,formaldehyde aqueous solution,hydrogen as raw material,Pd/C and Gamma-Al2O3 with sulfuric acid as acid catalyst,reaction temperature is 145 ?,reaction time is 4 h.Under this process condition,the yield of DMI can reach more than 89%.The catalyst regeneration process is simple and the cycle utilization rate is high,and the original catalytic activity can still be retained after repeated application(more than 20 times).Through experimental exploration,it was found that using industrial activated clay(a new type of green and highly efficient solid acid catalyst without further modification)and Pd/C as the catalysts of preparation of DMI by hydrogenation method can also get target products with high yield(yield greater than 86%).Finally,this paper designs two industrial schemes of the production of 500 tons of 1,3-dimethyl-2-imidazolidinone per year(formic acid process and hydrogenation process respectively)and discuss the industrialization scheme.First of all,the process flow of two production processes was determined and the process flow chart was drawn.Then the material balance,energy balance and the process calculation of the important equipment were calculated.Finally,the cost accounting of the proposed production process was carried out to provide a basis for the industrial production of DMI.