International and domestic policies and legislation require industrial plants with significant CO2 emissions to install carbon capture and storage technologies to immobilize carbon dioxide from the input and output/flue gases (International Atomic Energy Agency, 2008). Carbon dioxide can be captured before and after the combustion of the fossil fuels. The first step is to separate CO2 from the other gases in the mixture (called flue gases) using several techniques (Figure 1). The basis of the techniques is to trap or immobilize carbon dioxide on special surfaces or by dissolution in special solvents. The immobilized CO2 is then concentrated and/or contained, followed by transport through pipelines to storage facilities, mostly deep geologic formations (Metz, Davidson, de Coninck, Loos, & Meyer, 2007).
In fossil fuel plants, the most common technique used is the absorption of carbon dioxide using chemical and physical means. Other methods are adsorption on solid surfaces, use of low temperatures (cryogenics), membranes and microbial systems. Adsorption is gaining users as new innovations become available.
In industrial plants, adsorption is commonly used to remove impurities from gas mixture streams as in hydrogen-rich gases resulting from gasification and steam reforming during ammonia synthesis (John Mathey Catalysts, 2010). In the adsorption process, the gas mixture is introduced or passed through a bed of solids that selectively adsorbs CO2, allowing the other gases to just pass through. When the adsorbent bed is fully saturated with CO2, the feed gas is redirected to a clean adsorption bed, while the loaded bed is regenerated to remove the CO2. This is the basic adsorption process.
After the adsorbing process, the adsorbed compounds should undergo desorption, or the process of removing the compounds from the adsorbing surface. The process of desorption should also regenerate the adsorbent material. For regeneration of the ...