Ex-ante enviro-economic assessment of chemical production routes: computational tools and case studies to enable olefins circularity
File(s)
Author(s)
Lyons, Benjamin
Type
Thesis
Abstract
Olefins are used in over 70% of all downstream chemical products, making them vital to the chemical industry. However, their current fossil fuel production follows a linear economy model that increasingly conflicts with sustainability goals. A circular economy model proposes replacing fossil fuels with renewable feedstocks, but choosing optimal routes through environmental and economic assessments is complicated and time-consuming. This thesis introduces a computational tool that streamlines enviro-economic assessments for chemical processes modelled in Aspen HYSYS. The tool performs equipment sizing and costing, heat exchange network synthesis, techno-economic assessments, and integrates with existing life cycle assessment software. The tool's capabilities are leveraged in three case studies investigating routes towards circular ethylene production. The first considers municipal solid waste gasification for producing methanol, ethanol and light olefins. When paired with carbon capture and storage, the gasification route matches incineration costs and benefits from substantially reduced environmental impacts by combining waste management with chemical manufacture. The second case study assessed a novel CO2-to-ethanol catalyst by designing and modelling a scaled-up process. Whilst the catalyst at its current performance cannot compete with other state-of-the-art CCU routes, addition of a pre-reactor significantly improved performance. Conversion and selectivity targets were determined to direct catalyst development. Finally, the potential for valorising methane side streams in fuel-switched chemical plants was assessed through methanol or ethylene manufacture. Whilst capital costs inhibit potential at lower methane flowrates, profitability is achievable at larger scales with low renewable electricity prices. Environmental benefits are substantial due to utilising waste streams as feedstock for chemical manufacture. Overall, the developed tool can aid research and development prioritisation efforts in the circular chemical economy.
Version
Open Access
Date Issued
2025-10-03
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Chachuat, Benoit
Publisher Department
Department of Chemical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)