Study on CO2 Capture using Nanostructure Carbon Adsorbents

Abstract

The increasing trend of CO2 concentration in the atmosphere is the main cause for the enhancement in global warming which is known as the biggest environmental problem. The combustion of fossil fuels by humans raises the concentration of CO2 in the atmosphere day by day. Increase in the fossil fuels burning leads to enhance the CO2 emissions in the atmosphere which increases the greenhouse effect. Among the various mitigation pathways, Carbon capture and storage (CCS) is the most significant technology to reduce the CO2 concentration in the environment by capturing it from the large point sources. The CCS has three techniques i.e. post-combustion, pre-combustion and oxy-combustion capture, among which post-combustion capture is known to be effective in the reduction of greenhouse gas (GHG) emissions. It includes several methods like absorption, cryogenics, adsorption, membrane, and other techniques. Among them, adsorption via solid materials is one of the effective techniques in CO2 capture practical applications due to its cost-effectiveness, high CO2 uptake, and low energy necessities. Porous carbons are known to be most efficient adsorbents because of their high surface area and large pore volume. These adsorbents can be developed from various low cost sources using different methods like carbonization of low-cost precursors, sol-gel method, nanocasting technique, chemical activation method, etc. Nanocasting and chemical activation methods are known to be effective methods for the development of high surface area carbon adsorbents. In the nanocasting technique, generation of porous structure and tuning of their surface area can be easily done in the preparation of carbon adsorbents. This method consists of three major steps: synthesis of the template, precursor impregnation and then template removal. On the other side, chemical activation method consists of the impregnation of carbon precursor with the chemical activating agents followed by the carbonization process (inert atmosphere) and then acid washing.