Hydrogen recovery from end-of-life tire pyrolysis gas via H2S splitting

Waste tire pyrolysis is one of the most intriguing and economically appeal-ing treatments currently available for converting End-of-Life (EoL) tires into valuable products. However, the high sulfur content in the waste (approximately 2 wt% of the feed) leads to the formation of undesirable toxic and hazardous byproducts (e.g., H2S) during the pyrolysis process. A desulfurization treatment is essential both to improve the quality of the produced oil and to abate H2S emissions. However, these processes are typically energy-intensive and require significant amounts of hydrogen. In addition, the integration of innovative technologies and operational conditions to achieve a self-sustaining process in terms of hydrogen consumption strongly aligns with circular economy principles. This project focuses on simulating a dedicated unit for H2S decomposition into H2 and S2, and its integration with a specific hydrotreating unit for oil upgrading. The goal is to exploit the hy-drogen content of the hydrogen sulfide to establish a self-sustaining hydrogen loop. Simulations are performed using Aspen Plus V.11, while, for unconventional units requiring detailed kinetic schemes DSmoke is used. Preliminary evaluations on hydrogen recovery are conducted, showing promising results regarding the feasibility of a self-sustaining hydrogen process for end-of-life (EoL) tire recycling and oil upgrading. Initial results show that over 50.0% of the total hydrogen required for oil upgrading can be recovered.