Method for Characterization and Analysis of Pores in Coke

In order to establish a reliable analytical method which can reflect the specific surface area and pore structure of coke, N₂, Ar and CO₂ were used as adsorbates to determine the adsorption isotherm of Huainan coke, and the models of BET, BJH and NLDFT were used to calculate the specific surface area and pore structure. The results indicate that Huainan coke possesses continuous micropores and mesopores which consist of large quantity of blind holes and split holes. Due to the effect of quadrupole moment in N₂ molecule, a larger adsorption quantity, specific surface area and pore volume are obtained using N₂ as adsorbate compared with Ar adsorption. The BET model is mainly used for mesoporous materials, while the BET specific surface area will be small when it is used for microporous material. To characterize the porous carbon materials, especially those with complex and disordered pore structures like coke, a suitable method was established. At first, the specific surface area and pore volume of mesopores were calculated by NLDFT model, based on the results of the shape and pore size distribution of mesopores in coke derived from the Ar adsorption. Then the experiment of CO₂ adsorption was carried out to obtain the parameters such as specific surface area and pore structure of micropores using NLDFT model.