Industrialization and Expansion of Green Sustainable Chemical Process: A Review of Non-phosgene Polycarbonate from CO2

The world's first non-phosgene polycarbonate process from CO2 has been developed and industrialized by Asahi Kasei Corporation (Japan). Hitherto, all polycarbonates (PCs) have been produced using CO as a raw material. Among them, most PCs have been produced by so-called the "phosgene process" using highly toxic phosgene (COCl2) and large amounts of solvents (probable human carcinogen CH2Cl2 and water). The phosgene process has many environmental and safety problems. However, technological barriers have hindered realizing the non-phosgene PC process. The Asahi Kasei Process has not only solved the problems of the phosgene process but also contributed to sustainability (reduction of CO2 emission, materials saving, and energy saving). High-quality PC and high-purity monoethylene glycol (MEG) are produced in high yields, respectively, without waste and wastewater, starting from CO2, ethylene oxide (EO), and bisphenol A (BPA). In the monomer (diphenyl carbonate: DPC) production process, innovative reactive distillation process, and in the melt polymerization process, a gravity-utilized non-agitation reactor had been developed, respectively. The Asahi Kasei Process has been expanding worldwide, and 1.07 million tons of PC will be produced in 2019. The Green Sustainable Chemical Process has been changing the PC production world. In this review, the Asahi Kasei Process and perspective of the present PC production processes together with discriminating and detailed comparisons are described.