Solving two environmental problems simultaneously: Scalable production of carbon microsheets from structured packing peanuts with tailored microporosity for efficient CO2 capture

Abstract

Highly porous carbon microsheets (CMS) were prepared by the bulk carbonization and activation of waste packing peanuts, and applied to CO2 capture and release. Two different activation methods, physical activation using CO2 and chemical activation using KOH, were used for the preparation of porous CMS, and the effects of different activation methods were compared. Chemical activation functioned better than the physical activation, successfully producing highly microporous carbon structures with higher carbon yield. Textural properties such as specific surface area and total pore volume increased proportionally to the mass ratio of KOH/carbon because of the development of the porous structure and enlargement of pore size through KOH activation. Among the samples prepared, the highest CO2 adsorption capacities of 6.51 mol kg–1 at 0 °C and 4.07 mol kg–1 at 25 °C were obtained at 1 bar in the packing-peanut-derived CMS prepared with a KOH/carbon ratio of 3 (CMS-K3). A partition coefficient concept was also introduced as an alternative metric for adsorbent screening and the same trends between partition coefficient and CO2 adsorption capacity were observed in this study. It is noteworthy that the CO2 adsorption uptake was significantly dependent on the volume of narrow micropores of pore sizes less than 0.8 nm rather than the specific surface area or total pore volume. CMS-K3 also exhibited excellent cyclic stability, good CO2/N2 selectivity, fast adsorption kinetics, and low heat of adsorption, being regarded as a promising adsorbent for CO2 capture.