The Process Design And Optimization Of Synthesising Of Dimethyl Carbonate By Liquid Phase Oxidative Carbonylation Of Methanol

In recent years,the demand of dimethyl carbonate（DMC）is continuously increasing as the electrolyte of lithium-ion battery and the raw material of polycarbonate.The synthesis of DMC by liquid phase oxidative carbonylation of methanol is considered as simple and thermodynamically advantageous.Our research group has developed a technology for chlorine-free Cu/AC catalyst applied in synthesis of DMC by liquid phase oxidative carbonylation of methanol,which fundamentally avoid of the deactivation of catalyst and the corrosion of equipment induced by the leaching of chlorine.It can speed up the industrialization process that the design and optimization of technology by process simulation technology.Until now,only the purification of CO₂,the separation of the mixture for DMC-methanol and methanol-water have been reported,respectively.However,the whole flowsheet design and optimization analysis of this process have not been reported yet.Therefore,the whole DMC production flowsheet including three sub-processes（the synthesis of DMC,the removal of CO₂ from circulating gas,the purifying of DMC）was designed.This design was on the basis of the experimental results of chlorine-free Cu/AC catalyst for the synthesis of DMC and the combination of the characteristics of each component of product and the advantages of separation engineering technologies.The key operating parameters of this process were optimized in this thesis,and the main obtained conclusions are as follows:（1）The thermodynamic parameters of reaction process were calculated accurately by the modified PSRK model on the basis of literature report and calculation analysis.The UNIQUAC model corrected by literature data was suitable for the simulation of DMC purification process.（2）DMC with high-quality can be obtained through the designed process flow in this thesis.The production of 1 ton of DMC with high-quality consumed 0.5755 ton of CO,0.3214 ton of O₂ and 0.7609 ton of methanol.The mass fraction of the recovered methanol was above 99.5%.The mass fraction of organic matter in the wastewater of T-2-104 was only about 0.03%,and the volume fraction of CO₂ in the circulating gas after purification by MDEA absorption was below 2.0%.（3）Compared with the four-column process,two more sets of equipment were added in six-column process,and therefore the one-time investment cost of the latter was higher than the former.However,the six-column process was obviously advantageous in energy saving than that of four-column process.After heat exchange process,the purification process of six-column required total cooling load of 37.4119 GJ and heating load of 32.5705 GJ to produce 1ton of DMC,which were 22.35%and 22.46%lower than that of four-column process,respectively.In addition,the total cooling and heating load for purification DMC by six-column process accounted for 83.6%and 98.7%of the whole process.（4）The rough product with 10.0%,14.4%,20.0%and 25.0%DMC were purified by six-column distillation process under the same separation requirements.The energy consumption of the whole process decreased significantly with the increase of mass fraction of DMC in liquid product.The total energy consumption decreased by 58.4%with mass fraction of DMC increased from 10.0%to 25.0%.It can effectively reduce the production cost of DMC that improvement of the mass fraction of DMC in reaction products by the optimization of catalyst and reaction process.