Determination of the connectivity of porous solids from nitrogen sorption measurements

A method is proposed for the determination of the connectivity of porous solids, such as adsorbents and catalyst supports, from the analysis of nitrogen sorption measurements. The new method is based on the use of percolation theory to analyse sorption hysteresis. For solids giving hysteresis loops of the International Union of Pure and Applied Chemistry (IUPAC) types H1 and H2, the mean coordination number of the pore network is determined by detecting and quantifying a percolation transition in the desorption isotherm. For type H3 hysteresis loops, an upper bound is obtained for the mean coordination number, although for some solids this bound is too high to be useful. No connectivity information can be obtained from the type H4 hysteresis loop. The analysis method is robust and can be applied routinely.