Title : Ammoxidation of palm shell based activated carbon to promote CO2 adsorption
Abstract:
It is widely accepted that carbon dioxide (CO2) is the most important greenhouse gas with the largest impact on climate change. The increase in the atmospheric level of CO2, has led to the search for technologies designed to capture CO2 from point source emissions and stabilize its concentration in the atmosphere. Adsorption is considered as one of the most viable options that can be applied to carry out the separation of CO2. Among all adsorbents activated carbons are being proposed as suitable candidates for CO2 capture: they do not require any moisture removal, pre-sent a high CO2 adsorption capacity at ambient pressure and, moreover, they are easy to regenerate. Accordingly, in this study, a commercial granular activated carbon (GAC) was subjected to thermal treatment with ammonia for obtaining efficient carbon dioxide adsorbent. In general, CO2 adsorption capacity of activated carbon can be in-creased by introduction of basic nitrogen functionalities into the carbon surface. In order to ascertain if the presence of oxygen surface groups before introduction of basic nitrogen functionalities on to the carbon surface could improve in some way the CO2 adsorption capacity, two different approaches were studied: ammonia treatment without preliminary oxidation and ammoxidation of samples. Modified carbons were characterized by elemental analysis to study the impact of changes in surface chemistry on adsorption properties. It was found that in both modification techniques, the presence of nitrogen functionalities on carbon surface increased CO2 adsorption capacity. The result indicated that high temperature ammoxidation (800 °C) exhibits a relatively softer slope of temperature-programmed CO2 adsorption curve reaching maximum uptake of up to 30.04 (mg CO2/g adsorbent) at 105 °C.
