Interpretation of integrated gas sorption and mercury porosimetry studies of adsorption in disordered networks using mean-field DFT

The presence of co-operative adsorption behaviour, operating between neighbouring pores within a disordered, void-space network, such as advanced adsorption effects, can significantly complicate the interpretation of gas adsorption data for complex porous solids, such as coked heterogeneous catalysts. The novel integrated gas sorption and mercury porosimetry method can be used to abstract the specific adsorption and desorption behaviour for particular, small sub-sets of similarly-sized pores contained within the complex network of a disordered porous solid. It will be shown in this work how, for ink-bottle geometries, the integrated experiments also allow the deconvolution of the gas sorption behaviour in pore necks, as well as pore bodies, and therefore enable the mechanism of desorption from the pore bodies to be determined. However, proper interpretation of the adsorption data from integrated experiments can be problematic using classical adsorption theories. In this work, it has been demonstrated that the experimental observations can be better understood in the light of mean-field DFT simulations of adsorption in representative pore models. Hence, a better description of the particular physical mechanisms underlying adsorption isotherms in disordered porous solids has been obtained. In addition, the new method allows more detail of the void space geometry to be obtained, such as the ratio of pore neck length relative to pore body length.