Additivity of pore structural parameters of granular activated carbons derived from different coals and their blends

A series of granular activated carbons (GACs) were prepared by briquetting method from Chinese coals of different ranks and their blends, with coal pitch as the binder. Pore structural parameters including BET specific surface area (SBET), total pore volume (VT) and average pore diameter (da) were measured and calculated as well as process parameters such as yield of char (CY) and burn-off (B). The relationship between the pore structural parameters of the GAC from coal blend (BC-GAC) and the ones of the GACs from corresponding single coals (SC-GACs) was analyzed, in which an index, the relative error (δ), was presented to define the bias between fitted values and experimental values of these parameters of the BC-GACs. The results show that the BC-GAC keeps qualitatively the pore structural features of the SC-GACs; as concerned as the quantitative relationship, the pore structural parameters of the BC-GAC from coal blend consisting of non-caking coals can be obtained by adding proportionally the pore structural parameters of the SC-GACs with δ less than 10%. Meanwhile, for the BC-GAC from coal blend containing weak caking bituminous coal, the δ increases up to 25% and the experimental pore size distribution differs greatly from the fitted one.