Pore-volume and surface area in microporous-mesoporous solids

To show the correct evaluation of pore-volume and surface area in microporous-mesoporous samples a series of mechanical mixtures of microporous zeolite NaY and mesoporous gamma-alumina was prepared. The nitrogen adsorption isotherms (77 K) were analyzed by the modified (three parameters) BET equation and compared with the independent textural information obtained (a) from t-plots (with the standard isotherm of nonporous alpha-alumina and the standard isotherms of Lecloux-Pirard); and (b) by subtracting the isotherm of the parent NaY from mixed sample isotherms. For illustration, the failure of the classic (two-parameter) BET equation for samples of that type was demonstrated. (c) 2008 Elsevier Inc. All rights reserved.