Critical assessment of the performance of next-generation carbon-based adsorbents for CO2 capture focused on their structural properties

Abstract

Carbon dioxide emissions and their sharply rising effect on global warming have encouraged research efforts to develop efficient technologies and materials for CO₂ capture. Post-combustion CO₂ capture by adsorption using solid materials is considered an attractive technology to achieve this goal. Templated materials, such as Zeolite Templated-Carbons and MOF-Derived Carbons, are considered as the next-generation carbon adsorbent materials, owing to their outstanding textural properties (high surface areas of ca. 4000 m² g^-1 and micropore volumes of ca. 1.7 cm³ g^-1) and their versatility for surface functionalization. These materials have demonstrated remarkable CO₂ adsorption capacities and CO₂/N₂ selectivities up to ca. 5 mmol g^-1 and 100, respectively, at 298 K and 1 bar, and low isosteric heat of adsorption at zero coverage of ca. 12 kJ mol^-1. Herein, a review of the advances in preparation of ZTCs and MDCs for CO₂ capture is presented, followed by a critical analysis of the effects of textural properties and surface functionality on CO₂ adsorption, including CO₂ uptake, CO₂/N₂ selectivity, and isosteric heat of adsorption. This analysis led to the introduction of a V_microx N-content factor to evaluate the interplay between N-content and textural properties to maximize the CO₂ uptake. Despite their promising performance in CO₂ uptake, further testing using mixtures and impurities, and studies on adsorbent regeneration, and cyclic operation are desirable to demonstrate the stability of the MDCs and ZTCs for large scale processes. In addition, advances in scale-up syntheses and their economics are needed.

Keywords: 3D framework; CO(2) capture; Chemical functionalization; MOF-derived carbon; Structural properties; Zeolite-templated carbon.