Techno-Economic and Life Cycle Assessment of Integrated CO2-to-Olefins Routes: Leveraging Industrial Symbiosis to Enhance Economic and Environmental Resilience

Abstract

The industrialization of sustainable CO2 conversion for light olefin production is governed by the synergistic integration of carbon capture, hydrogen sourcing, and catalytic efficiency. This study presents a comprehensive techno-economic (TEA) and life cycle environmental (LCA) assessment of four integrated pathways at a 700 kTA scale, comparing a one-step CO2-Fischer-Tropsch-to-olefin (CFTO) route against methanol-mediated (CMTO) and two-step (RWGS-FTO) benchmarks. Leveraging industrial symbiosis, fossil-derived byproduct hydrogen from propane dehydrogenation (PDH) serves as a transitional bridge, complemented by renewable-powered electrolysis. Upstream optimization of the carbon capture unit via a blended MEA + MDEA absorbent coupled with heat pump integration reduces the regeneration energy from 3.83 to 2.64 GJ/t CO2. Results reveal that the PDH-CFTO route achieves an exceptional target carbon utilization ratio of 79.9% and an energy efficiency of 35.1%, significantly outperforming the PDH-RWGS-FTO route (31.4%) and maintaining parity with the CMTO route. Economically, PDH-CFTO demonstrates high resilience with an MSP of 1594.2 USD/t, surpassing CMTO when carbon taxes exceed 80 USD/t. Environmental assessments confirm that the CFTO route achieves the lowest greenhouse gas footprint (1.88 t CO2-eq/t) among fossil-integrated pathways. While the renewable-hydrogen pathways minimize the emissions to 0.50 t CO2 eq/t, their MSP remains prohibitively high. Sensitivity analysis reveals a path-dependent impact of capture optimization, and catalyst selectivity remains the dominant economic driver. A 40% selectivity threshold is sufficient for CFTO to systematically outperform CMTO in economic viability, while reaching a 70% selectivity would trigger a 20.5% reduction in MSP and a 36.94% decrease in carbon footprint. These findings underscore that the synergy between high-selectivity catalysis, advanced carbon capture, and industrial byproduct integration provides a pragmatic and data-driven roadmap for sustainable olefin production.