Role of oxygen functional groups and pore structure in CO 2 adsorption from oxygen-blowing and nitrogen calcination processes using a precursor of coal-based activated carbon

Abstract

Functional groups on the surface chemical and pore structure are the main properties in the performance of activated carbon adsorption. Coal-based activated carbon product is used as a precursor to clarify that the oxygen-blowing into precursor structure can form new site oxygen-containing on the surface. Oxygen functional groups are verified through calcination under a nitrogen atmosphere. The process of oxygen-blowing is conducted at different temperatures of 100, 200, 300, 400, and 500°C and calcination at 900°C under a nitrogen atmosphere. The oxygen-containing tended to increase at a temperature of 500°C and encountered the decomposition of functional groups from the hydroxyl to carboxyl groups. The high temperature of 900°C in the calcination process formed new sites of nitrogen-carboxyl groups bonded, which improved micropore volume and CO2 adsorption—breakthrough time exhibited the more extended time duration for the calcination samples. This study proved that oxygen-blowing and calcination on coal-based activated carbon products can generate the enhancement of functional groups and pore structure. The increase in adsorption capacity is relatively minor as the volatile matter of activated carbon is very low.