Sustainable porous carbons from tannic acid based KOH activated as high-performance CO2 capture sorbents

Abstract

A potentially viable strategy for the fabrication of efficient sorbents for CO₂ capture is the use of porous carbons obtained from biomass, which have a large surface area and delicately organized porous structural framework. Herein, a series of porous carbons having enormous surface areas (as high as 2553 m² g⁻¹) and high micropore volumes (up to 0.8605 cm³ g⁻¹) were fabricated from a renewable precursor, tannic acid. At a pressure of 1 bar, the porous carbons performed better at absorbing CO₂; the respective maximal capacity was 7.03 and 4.29 mmol g⁻¹ at 0 and 25 °C. The existence of a large number of narrow micropores with a pore width less than 0.86 nm and 0.70 nm plays a critical role in the CO₂ uptake, respectively. Additionally, when tested against a mixture of CO₂ and N₂, TCKP-2-600 showed a good degree of selectivity for CO₂ uptake as well as good recyclability. Additionally, the Langmuir, Freundlich, Toth isotherm and Redlich–Peterson models were employed to process and fit the experimental equilibrium values for the adsorption of CO₂. All models accurately reflected the experimental data based on the standard deviation Δq (%) and regression coefficient (R²). This bioinspired precursor-synthesis technique is capable of generating porous carbons that are practically utilizable for a wide range of practical uses including CO₂ absorption.