Determination of carbon porosity from low-temperature nitrogen adsorption data. A comparison of the most frequently used methods

摘要

This paper compares the most frequently used procedures for carbon porosity determination, i.e. the Dubinin-Radushkevich, Dubinin-Izotova, t and α_s plot, Horvath-Kawazoe (HK) and micropore analysis methods. The correlations between the obtained results are presented, and the importance of the choice of reference material for t and/or α_s plot construction is displayed. It is concluded that only the HK method predicts smaller pore sizes. Our results show also that nitric acid oxidation of carbon and desorption in a flow of He in the temperature range 493-573 K leads to considerable changes in its porosity. However, for carbon previously oxidized and desorbed at 573 K, a pore-blocking effect occurs which probably results from the production of anhydrides in the carbon micropores.