An Adsorption-Based Method for the Characterization of Pore Networks Containing Both Mesopores and Macropores

Abstract

Nitrogen sorption is a commonly used experimental technique for the characterization of solids that are primarily mesoporous. The standard nitrogen adsorption experiment can also detect pores at the lower end of the macropore range, up to perhaps 3000 or 4000 Å. However, some solids of industrial importance contain macropores beyond the size range probed by the standard nitrogen adsorption experiment. In this work, a modified experimental method is used to obtain a more complete characterization of the solid. The experiment involves the bulk condensation of nitrogen in the sample tube after completing the adsorption isotherm and before measurement of the desorption isotherm. Modifications to existing pore size distribution and connectivity analyses are proposed to incorporate data from the experimental desorption isotherms. These modified analyses enable an improved estimate for the pore size distribution and a lower bound on the mean coordination number of the pore network to be obtained for these samples.