Volume 52

Optimizing Hydroxide-Functionalized Carbon Dioxide Adsorbents: Impact of Pore Structure on Adsorption Performance Shengyan Wang, Zichu Wang, Yaowei Huang, Shuai Deng, Meng Lin

Abstract

In the development of adsorbents for direct air capture of carbon dioxide, a novel charged-sorbents, enabled by electrochemically inserting hydroxide ions into activated carbon electrodes, has demonstrated enhanced carbon dioxide uptake at low pressures due to chemisorption to form (bi)carbonates. However, the further application of charged-sorbents is limited due to a lack of quantitative studies to material properties of absorption performance, particularly those prepared from inexpensive and readily available commercial activated carbon cloth. In this work, we employed a combined experimental and numerical method to investigate how the carbon dioxide adsorption performance of charged-sorbents is related to structural properties of carbon-based porous absorbent, i.e., charge capacity per unit mass, average pore size, pore volume, and specific surface area. We identified that the average pore size and the mass charging capacity are the two most influential factors. Higher mass charging capacity and smaller pore sizes, in general, lead to higher sorption performance. We observed that a commercial carbon cloth (AC-10-300) with a charing capacity of 1173 C/g and an average pore size of 0.933 nm showed an excellent sorption performance of 0.213 mmol/g with 400 ppm CO2. Our study provides valuable insights into the development and optimization of hydroxide-functionalized adsorbents for direct air capture using commercial activated carbon cloth substrates.

Keywords direct air capture, activated carbon cloth, pore structure, hydroxide-functionalized adsorbents