Optimization of green development for methylene diphenyl diisocyanate industry based on synergistic benefit

The methylene diphenyl diisocyanate (MDI), as an important platform for polyurethane, its embodied environmental impact (EI), especially the embodied carbon is important for the development of green and low-carbon building materials. In this study, green and low carbon roadmap for MDI production is tentatively designed after the relative strengths and weaknesses of different technology routes are identified. The results show that, to some extent, the advantages and disadvantages of technology routes depend on the selection of target-oriented indicators. The steam reuse, HCL recycled, benzene from coking and hydrogen from chlor-alkali process are effective routes with synergistic benefit. If these technologies are prioritized to be applied in the near term, 36 %-49 % carbon reduction could be attained simultaneously with considerable economic benefit. If near-zero low-carbon MDI requested, more deep green technologies are needed, 93 % carbon reduction potential could be achieved, but the sacrifice of economic cost is unacceptable. All in all, this work results can provide ideas for the green and low-carbon transformation of MDI industry and other industries. Meanwhile, this study unequivocally shows that industrial transformation hinges on a balanced consideration of various benefits to identify the optimal technological path. • The choice of technology routes depends on the target-oriented indicators. • The steam reuse, HCL recycled, benzene from coking and hydrogen from chlor-alkali process are effective routes with synergistic benefit. • Near-zero low-carbon MDI could be achieved with the sacrifice of economic cost.