Study On The Process And The Catalysts For Synthesis Of Dimethyl Carbonate From Urea

To investigate the process for synthesizing dimethyl carbonate (DMC) from urea and study the catalysts which were active for the reaction of methyl carbamate (MC) with methanol to produce DMC, following experiments were carried out:â… . Investigation on the method to separate and determine the final products of MC synthesis from urea and methanol.Since MC has a relatively high boiling point and urea is not stable at high temperature. It is not an easy job to analyze the products by gas chromatography (GC). Based on our study, it was found that RP-HPLC was effective and simple method to analyse urea, MC and other impurities in the reaction mixture. In this work, we proposed that two C₁₈ columns connected in series instead of single one should be used and the simple methanol-water system be used as carrier.â…¡. Study on reaction conditions of batch process and semicontinuous process for the synthesis of MC from urea and methanol.The batch process for synthesis MC from urea and methanol, particularly the effects of reaction temperature, reaction time, stirring speed and mole ratio of methanol to urea et al. on the reaction result were systematically studied. The optimum operating conditions were as follows: reaction temperature of 160 ℃, reaction time of 5 h, stirring speed of 600 turns/min, and mole ratio of methanol to urea 5:1. The yield of MC reached 75.1%.As for the semicontinuous process, the influences of reaction temperature, reaction time, flow rate of nitrogen, stirring speed and mole ratio of methanol to methyl urea were evaluated as well. The optimum operating conditions as follow had been obtained: reaction temperature of 160 ℃, reaction time of 5 h, nitrogen flow rate of 40 ml/min, stirring speed of 600 turns/min, and mole ratio of methanol to urea 5:1. The yield of MC reached 95%. This study provides reliable and precious experience for the process of DMC synthesis from urea and methanol.â…¢. Study on the reaction conditions of batch process and continuous process for the synthesis of DMC from MC and methanol via catalysts.When dibuthyl tin oxide was used as catalyst, the effects of reaction temperature, reaction time, mole ratio of methanol to MC, mass ratio of dibuthyl tin oxide to MC and the stirring speed on the production of the batch process were intensively investigated. The following optimum operating conditions were determined: reaction temperature of 180℃ , reaction time of 3.5 h, mole ratio of methanol to MC 4:1, mass ratio of dibuthyl tin oxide to MC 1:10, and stirring speed of 600 turns/min. The yield of DMC was 13.5%. This study offers reliable reference for the continuous process of DMC...