Plastic-to-DME via integrated gasification: modeling, energy bottlenecks, and techno-economic analysis

• Integrated plastic-to-DME novel pathway validated using Aspen Plus. • Efficiency of 76.7% with 0.32 kg DME per kg plastic. • Carbon intensity reduced to 0.58 kg CO 2 /kg DME with capture. • Acid-gas removal contributes ∼54.8% of total energy use. • Production cost of $0.87/kg and a 4.6-year payback at $1.2/kg DME. The accumulation of waste plastic is a major challenge to the environment and its conversion to valuable chemicals is one of the promising ways to achieve sustainability. Dimethyl ether (DME) is considered as a clean fuel and a useful chemical intermediate based on various commercial and industrial applications. Recent developments in catalytic DME synthesis via direct and indirect routes have been explored but a fully integrated process to transform plastic waste into DME has not been proposed. In this study, we propose a complete process scheme for the utilization of waste plastic for the DME production via oxygen-blown bubbling fluidized bed gasification developed in Aspen Plus V14 and compared to experimental data. The process combines waste plastic gasification, acid gas cleanup with amine scrubbing and single step production of DME using a Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model reactor. Results show that under base conditions (with gasifier at 887°C, 1 bar, and DME reactor with 240°C, 35 bar), the process is characterized by an overall efficiency of 76.7%, and the production cost of the DME is competitive at $0.87/kg. The present techno-economic analysis shows a net present value (NPV) of 43.3 million dollars and a payback period of 4.6 years. Sensitivity analyses have been performed to gain insight into the critical impact of both feedstock and product prices on the overall economic performance of the process. These findings indicate that waste plastic valorization into DME is technically and economically feasible and provides a way to achieve circular economy and clean fuels. The study forms a basis of future optimization and experimental verification of integrated waste-to-fuel technologies.