Determination of the percolation properties and pore connectivity for mesoporous solids using NMR cryodiffusometry

Using a model disordered mesoporous solid with a spatial arrangement of pore sizes analogous to a macroscopic ‘ink-bottle’, it has been shown that the hysteresis observed in NMR cryoporometry can be deconvoluted into separate single pore and pore-blocking contributions. The suggestion of pore-blocking effects has been confirmed using PFG NMR. Hence, percolation theory has been used, for the first time with cryoporometry, to analyse the pore-blocking contribution to the hysteresis to determine the accessibility function and pore connectivity of the void space of a mesoporous sol–gel silica catalyst support pellet. This work demonstrates that NMR cryoporometry can be used to obtain a full range of void space descriptors, and thus offers a full, and potentially better understood, complementary pore structure characterisation method to gas sorption and mercury porosimetry.