On the use of plastic precursors for preparation of activated carbons and their evaluation in CO2 capture for biogas upgrading: a review

•One task for pyrolysis of plastic waste is non-existent markets for solid products.•Revision of CO2 capture by activated carbons prepared from plastics was provided.•KOH is the most used agent for the activation with better CO2 adsorption results.•PET plastic waste is a suitable precursor to produce efficient CO2 adsorbents.•No studies were done with these activated carbons using a usual biogas composition. In circular economy, useful plastic materials are kept in circulation as opposed to being landfilled, incinerated, or leaked into the natural environment. Pyrolysis is a chemical recycling technique useful for unrecyclable plastic wastes that produce gas, liquid (oil), and solid (char) products. Although the pyrolysis technique has been extensively studied and there are several installations applying it on the industrial scale, no commercial applications for the solid product have been found yet. In this scenario, the use of plastic-based char for the biogas upgrading may be a sustainable way to transform the solid product of pyrolysis into a particularly beneficial material. This paper reviews the preparation and main parameters of the processes affecting the final textural properties of the plastic-based activated carbons. Moreover, the application of those materials for the CO2 capture in the processes of biogas upgrading is largely discussed.