Chemically modified carbonaceous adsorbents for enhanced CO2 capture: A review

The rapidly-increasing concentration of atmospheric carbon dioxide (CO2) gas has become one of the most pressing environmental concerns in recent years. CO2 capture has become a vital technical solution to minimize environmental CO2 emissions from various sources. The development of advanced adsorbents for effective CO2 adsorption is a growing area that has gained significant attention in the materials science field. Hence, in this review we systematically discuss carbonaceous materials including carbon allotropes (carbon nanotubes (CNTs) and graphene oxide (GO)), carbon aerogels (CAs), biochar, polymer-derived carbons, microporous carbons, and mesoporous carbons that are extensively utilized for CO2 uptakes. The functionalization of carbon materials that have also been reviewed here involved physical/chemical activations using activating agents (KOH, NaOH, K2CO3, and ZnCl2), doping (N, O, and S), amine modification, carboxylation (-COOH), hybrid/composites formation, and metal oxide impregnation. Studies demonstrated that these all modifications play a very essential role in enhancing the CO2 adsorption performance as compared to pristine carbons. It is well-acknowledged that the existence of extremely microporous network with ultra-high specific surface area exhibits a dominant role in enhanced CO2 capture. Among various functionalized carbon-based adsorbents, modified porous activated carbons proved an excellent adsorbent for efficient CO2 uptakes because of their brilliant textural properties and economical nature. Additionally, modified carbonaceous adsorbents possessed feasible isosteric heat of adsorption, excellent regeneration ability, and shows efficient selective CO2 adsorption over N-2. Besides, these studies also summarize future challenges and prospective research pathway that could be commenced for developing effectual adsorbent for an efficient CO2 storage application by considering various factors. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This article reviews the application of carbonaceous materials in CO2 adsorption, discusses the impact and role of various modification methods, and summarizes future research challenges and prospects.