We propose and demonstrate an integrated electrified plasma-assisted chemical looping (PACL) process that yields supra-equilibrium CO 2 conversions unattainable with conventional catalysis at temperatures ≪3000 K. CO 2 is first dissociated inside plasma into CO/O at supra-equilibrium conversions (up to 60%) at a bulk gas temperature of 773 K and a 403 kJ/mol energy cost. Supra-equilibrium CO 2 conversions (29% on average) are achieved at the reactor outlet by placing a nanostructured CeO 2 /Fe 2 O 3 oxygen scavenger, prereduced by H 2 plasma, downstream of the plasma zone, to capture produced oxygen species and suppress CO/O recombination. Without plasma-material synergy, such an average CO 2 conversion can only be attained at temperatures ≥ 2775 K, according to chemical equilibrium calculations. This concept of plasma-assisted chemical looping allows reaching 3-fold higher conversions than state-of-the-art plasma technologies.

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Ambitions towards a circular economy are increasingly vocalised across academia, policymaking and industry. The endeavour of realising these ambitions provides major opportunities and challenges in chemical engineering, and requires a tremendous roll-out of new technologies. This perspective highlights the suitability of chemical looping as a technology platform to contribute to the valorisation of material streams that are currently not used to their full potential, termed low-grade resources. Such material streams offer significant opportunities to minimise CO2 emissions and accelerate towards a circular materials economy. Apart from defining and identifying low-grade streams, both calorific and non-calorific, a non-exhaustive overview of such streams is provided. Based on a selection of case studies focusing on steel mill gases, bauxite residue, pyrite cinder, calcium carbide slag and automotive shredder residue, it is posited that the characteristics and flexibility of the chemical looping approach offer ample possibilities to efficiently reuse low-grade streams and minimise their environmental impact. Finally, an outlook on chemical looping as a technology platform and its possible role in the drive towards circularity is given, with attention for the roles of industrial, academic and governmental stakeholders. In order to assess the suitability of a chemical looping process for valorising low-grade resources, the importance of holistic technology investigations is stressed, taking into account technical, economic, ecological and societal considerations.