(423e) Cradle-to-Gate LCA of Sustainable Ethylene Synthesis Using Oxidative Coupling of Methane

This study conducts a cradle-to-gate life cycle assessment (LCA) of ethylene production via oxidative coupling of methane (OCM), evaluating its environmental sustainability compared to conventional steam cracking. The analysis encompasses the entire production chain, including methane feedstock sourcing (from both natural gas and biogas), OCM reactor operation at 800°C using a Na-LaMnO₃-δ catalyst, and downstream ethylene purification through amine scrubbing and cryogenic distillation, with a functional unit of 1 kg ethylene. Using SimaPro with Ecoinvent v3.8 databases and ReCiPe 2016 Midpoint (H) methodology, the study quantifies global warming potential (GWP), fossil depletion, and energy demand. Results indicate that OCM emits 3.2 kg CO₂-eq/kg ethylene, which is similar to steam cracking's 3.210 to 3.731 kg CO₂-eq/kg, but achieves a 40% reduction in emissions when biogas-derived methane is utilized. The process demands 35 MJ/kg ethylene, primarily for reactor heating (62%) and CO₂ removal (23%), with key hotspots identified in catalyst synthesis (12% of GWP), methane leakage (9%), and cryogenic distillation for ethylene purification (18%). Despite its current higher carbon footprint, OCM offers significant potential for carbon circularity when integrated with CH₄ and CO₂ capture technologies. Challenges such as high thermal energy requirements and catalyst deactivation highlight the need for further optimization. Future prospects include coupling OCM with green hydrogen for CO₂ hydrogenation, adopting chemical looping to slash energy use by 30–50%, and leveraging policy incentives to promote methane-to-chemicals pathways under carbon pricing schemes. This LCA positions OCM as a promising, albeit niche, alternative for sustainable ethylene production in a decarbonizing chemical industry, contingent on advancements in renewable energy integration and process efficiency.