Development of microporosity in carbons derived from alkali digested coal Original Research Article

A series of high surface area carbons were produced from a brown coal digestion with KOH and NaOH followed by carbonisation. High resolution nitrogen adsorption isotherms determined over the relative pressure range 10−6 to 1 at 77 K of these carbons revealed that the pore sizes in the micropore and mesopore regions can be controlled by changing the stoichiometric ratio of alkali to oxygen functionalities of coal. Comparison of micropore surface areas determined from nitrogen at 77 K and carbon dioxide at 273 K showed that complete exchange of carboxyl groups with K+ facilitates nitrogen accessibility to entire micropore space.