Chemical recycling of EPDM waste through pyrolysis: Exploring the feasibility of a circular economy model.

Ethylene propylene diene monomer rubber (EPDM) is widely used in many industrial sectors. EPDM's physical and chemical properties make it highly durable, flexible and resistant, while posing significant recycling challenges. The development of a circular economy for rubber compounds is a remarkable challenge for the sustainability of this industry, and pyrolysis offers interesting characteristics for the recovery of value-added raw materials from waste EPDM. This process converts EPDM rubber into raw recovered carbon black (RRCB), pyrolysis gas (PyG) and pyrolysis oil (PyO). This work studies the pyrolysis of EPDM in a lab-scale plant with two reactors in series in order to tune the yield and properties of the products to potentiate their value. While the first reactor controls the temperature effect for high quality RRCB production, the second reactor serves to thermally crack the volatiles released. The results show that the RRCB produced has a potential use as substitute for virgin carbon black (CB). Likewise, the PyO can be cracked from linear, cyclic, and heterocyclic hydrocarbon compounds to aromatic ones. In addition, PyG with high C and C gas content is highly promoted at higher cracking temperatures. This composition of PyG is seen as very promising in promoting circularity within the EPDM industry, as ethylene and propylene are the main basic chemicals for EPDM production. The developed process may serve as a promising approach to sustainable chemical recycling, balancing cost-efficiency with environmental responsibility, notably by reducing the carbon footprint through the use of RRCB as a replacement of conventional CB.