Cokes  reacted with CO2  in the temperature range of 800-900 °C. During the reaction, the compositional change of product gases were measured by quadruple mass spectrometry (QMS) for evaluating the gasification rate. Image analysis was carried out to measure the porosity according to the distance from the coke surface.

The reverse Boudouard reaction C+CO2  = 2CO

This C(O) becomes stable with the furnace conditions gradually and starts to inhibit the reaction by blocking active sites of the carbon species,

C(O) = C-O [reversible process];

There is also a proposition that C(O) may be decomposed by leaving the surface of the carbon species as CO:

C(O) = CO.

This process of 'gasification' develops porosity by removing carbon atoms. The purpose of using CO2 during activation is to extract carbon atoms from the structure of the carbon species/compounds being produced/experimented

This is one of the methods to produce active carbon. It is active because it can adsorb a lot due to its great surface area (say, from 100 to 2000 m2/g). This process is named ACTIVATION. You can also do it with other oxidizing agents such as H2O or O2 too. Tensile strength of cokes was strongly affected by their porosity distribution. The porosity at the surface of coke gasified with CO2 indicated low values due to its low reactivity, which resulted in the intraparticle reaction to diffuse into the pores at low temperatures while the coke gasified with H2O showed the tendency to react with the coke at the surface.