Opportunities for converting waste plastics into petrochemicals: Process design, multi-objective optimization, and omnidirectional techno-economic-society-environment assessment

Waste plastics catalytic cracking, a carbon-negative process from the life cycle perspective, is a forceful executable configuration for cyclic utilization in the ecology. However, industrializing this emerging process requires to prevail a series of challenges, including time-consuming and massive pilot tests, process strengthening, and parameter optimization. To accelerate industrialization, we developed a fraction-structure lumps reaction model that significantly improves efficiency and accuracy. Moreover, multi-objective optimization and multi-dimensional evaluation were further done by implementing this process model. Together, a subsequent assessment of society and the environment was carried out. Compared with the non-optimized process, the optimized waste plastic catalytic cracking process exhibits superior economic, social, and environmental performance. The final optimization results of the reaction temperature and catalyst/oil ratio are 564.27 and 25.95, respectively. Quantitative results of this study indicate that catalytic cracking of waste plastics can effectively reduce the emissions of 1.86 t CO2 eq/t feedstocks. For the 200,000-ton scale waste plastic catalytic cracking process constructed, it can effectively reduce 372,000 tons of carbon dioxide equivalent emissions annually. From the view of life cycle society-environment behavior, it can be intuitively seen that the primary energy consumption of the WPCC-Pro process optimized based on the same functional units (considering social and environmental factors) is better than that of the WPCC process.