Pore-size distributions from nitrogen adsorption revisited:Models comparison with controlled-pore glasses

摘要

For the comparative study focused on comparison of models for evaluation of pore-size distributions (PSD) from nitrogen physical adsorption isotherms (at 77 K) a series of controlled-pore glasses (CPG10) with wide range of nominal pore sizes was used.The absence of micropores in CPG10 samples was proved by comparing adsorption isotherms at low relative pressures,x.This permitted construction of the dependence of adsorbed film thickness,t,on x [t(x)] commonly used in evaluation of textural properties of porous samples.Fifteen models for cylindrical pore geometry based on the Barret,Joyner and Halenda (BJH) and Broekhoff and deBoer (BdB) approaches with different t(x) dependencies and two evaluation algorithms were compared.Additionally a model which is based on modified non-local density functional theory with density-dependent weights and Tarazona prescription (NLDFT) was applied.It appears that the BdB model,which uses the t(x) dependence obtained for CPG10,produces PSD's from adsorption and desorption isotherm branches located at the same pore radius.