Determination of the pore size distribution of mesoporous silicas by means of quasi-equilibrated thermodesorption of n-nonane

Temperature programmed desorption profiles of n-nonane were measured for MCM-41, SBA-15 and HMS mesoporous silicas under quasi-equilibrium conditions using standard TPD setup with a chromatographic detector, utilizing He + 0.4% n-C9H20 mixture as a carrier gas. A method for determination of the pore size distributions according to a modified BJH scheme, based on the Kelvin equation for the fluid core radius and the BET-type function for the adsorbed film thickness, was proposed. The resulting pore size distributions are in good agreement with those obtained by standard BJH analysis of the N2 desorption isotherms.