Life Cycle Assessment Of PC Preparation Process By Interface Polycondensation Based On Material Flow Analysis

Polycarbonate(PC)is a high-performance engineering plastic widely used in fields such as automobiles,healthcare,and aerospace.Interface polycondensation,as the mainstream industrial production method for PC,uses phosgene and bisphenol A as raw materials.Its advantages are mature technology and excellent product performance,but the process is complex,energy consumption is high,and involves many pollution emissions issues.In order to explore the main environmental impact factors in the process of interface polycondensation PC preparation and seek technical improvement directions,this study established a full process model for PC preparation,and used material flow analysis and life cycle assessment methods to study various production processes.Based on the results,the improvement direction of the interface polycondensation PC preparation process was proposed.The specific content of this study is as follows:Firstly,a full process model of the interface polycondensation method PC preparation process was established using Polymer Plus.By analyzing the characteristics of components in the production system,Poly NRTL was determined as the global physical property method.Subsequently,steady-state simulations were conducted on the production process of bisphenol salt prefabrication,interfacial condensation reaction,phase separation and washing,solvent removal,and solvent recovery,obtaining material and energy balance results for the entire process.By analyzing the process simulation results and combining them with actual production data,an inventory of resource consumption and pollutant emissions for the interface polycondensation method PC production process was established.Secondly,the material flow analysis method was used to analyze the energy resource consumption and pollutant emission characteristics of PC production enterprises.The results showed that the direct material input and ecological burden in the PC production process accounted for 31.33% and 68.67% of the total material demand,respectively.Ecological burden,especially the ecological burden of energy,had the greatest impact on the environment.Reducing energy consumption is the key to reducing environmental pollution.Once again,the environmental impact of producing 1000 kg polycarbonate was analyzed using the life cycle assessment(LCA)method.The results showed that the total environmental impact potential of producing 1000 kg polycarbonate was 4.10E-08,with MAP accounting for 84.86% of the main type of impact,and the bisphenol salt prefabrication process accounting for 58.29% of the main process causing environmental impact.The analysis of contribution factors shows that the bisphenol salt prefabrication process has the greatest contribution to the environmental impact types outside of ODP,mainly from the bisphenol A production process;the background process of phosgene production contributes significantly to ADP,ODP,MAP,TEP,EP,and electricity production contributes significantly to GWP,MAP,TEP,and AP.Sensitivity analysis shows that ODP and TEP are the most sensitive to changes in sodium hydroxide and electricity consumption,respectively,while other impact types are the most sensitive to changes in bisphenol A consumption.Based on the LCA results,improvement suggestions were proposed to improve the utilization rate of raw materials,improve the production process of raw materials,reduce energy consumption in the production process,and control the direct emission of pollutants.Finally,referring to LCA recommendations,the effectiveness of replacing direct evaporation with vapor and water separation in solvent removal processes was investigated.Three simulation processes were established and life cycle comparative evaluations were conducted on the environmental impacts caused by energy resource consumption of the three methods.The results showed that the standardized total environmental impact potentials of direct evaporation,steam separation,and water separation methods were 4.85E-09,3.73E-09,and 2.54E-09,respectively.Compared to direct evaporation,the environmental impacts of steam separation and water separation methods were reduced by 23.13% and 47.59%,respectively,the water separation method is the method with the least environmental impact.In summary,this study comprehensively analyzed and evaluated the preparation process of interface polycondensation method PC through process simulation,material flow analysis,and life cycle assessment,and provided improvement directions and suggestions,providing a basis for optimizing the preparation process of interface polycondensation method PC.