Economic and Environmental Evaluation of Ethylene Production via Syngas-Derived Ethanol Dehydration

The urgency of achieving oil independence and mitigating climate change accelerates the development of ethylene production from coal and biomass sources. In this context, two innovative integrated pathways have been proposed, one involving coal-derived syngas and the other utilizing bioderived syngas, both followed by the catalytic conversion of syngas into ethanol and ethanol dehydration processes. These are referred to as CSEDH and BSEDH, respectively. Assessing the comprehensive competitiveness of the proposed pathways in comparison to the conventional method is essential for advancing the sustainable development of ethylene production. However, there is a notable scarcity of relevant scientific data. A process–economy–energy–climate evaluation was performed using process flow modeling, techno-economic analysis, and life cycle assessment, considering the two proposed pathways as well as their counterparts, coal-derived methanol-to-olefins (CMTO) and biofermented ethanol dehydration. The results indicate that the minimum selling prices of ethylene in the CSEDH and CMTO pathways are 33–46% lower than those of bioderived pathways under the assumed scenario. Additionally, the economic performance of the CSEDH pathway declines with rising coal prices and increasing plant size, shifting its competitiveness from favorable to unattractive compared to that of the CMTO pathway. This result is attributed to the lower total capital investment but higher utility consumption associated with the CSEDH pathway, highlighting the necessity for improved energy efficiency in future research. The BSEDH pathway demonstrates the lowest life cycle primary fossil energy depletion and greenhouse gas emissions, potentially leading to cost advantages if the carbon tax exceeds 320 CNY·t–1CO2eq. The study underscores the opportunities and challenges posed by each pathway for developing low-carbon and high-efficiency ethylene production.