title: Improving sensitivity and accuracy of pore structural characterisation using scanning curves in integrated gas sorption and mercury porosimetry experiments.
abstract: Gas sorption scanning curves are increasingly used as a means to supplement the pore structural information implicit in boundary adsorption and desorption isotherms to obtain more detailed pore space descriptors for disordered solids. However, co-operative adsorption phenomena set fundamental limits to the level of information that conventional scanning curve experiments can deliver. In this work, we use the novel integrated gas sorption and mercury porosimetry technique to show that crossing scanning curves are obtained for some through ink-bottle pores within a disordered solid, thence demonstrating that their shielded pore bodies are undetectable using conventional scanning experiments. While gas sorption alone was not sensitive enough to detect these pore features, the integrated technique was, and, thence, this synergistic method is more powerful than the two individual techniques applied separately. The integrated method also showed how the appropriate filling mechanism equation (e.g. meniscus geometry for capillary condensation equations), to use to convert filling pressure to pore size, varied with position along the adsorption branch, thereby enabling avoidance of the further systematic error introduced into PSDs by assuming a single filling mechanism for disordered solids.
authors.affiliation: Johnson Matthey Technology Centre, Blount's Court, Sonning Common, Reading RG4 9NH, UK. Electronic address: Iain.Hitchcock@Dunelm.org.uk.
authors.forename: Iain
authors.initials: I
authors.lastname: Hitchcock
authors.affiliation: Centre for Formulation Engineering, Department of Chemical Engineering, School of Engineering, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Marie
authors.initials: M
authors.lastname: Lunel
authors.affiliation: Centre for Formulation Engineering, Department of Chemical Engineering, School of Engineering, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Serafim
authors.initials: S
authors.lastname: Bakalis
authors.affiliation: Johnson Matthey Technology Centre, P.O. Box 1, Belasis Avenue, Billingham, Cleveland TS23 1LB, UK.
authors.forename: Robin S
authors.initials: RS
authors.lastname: Fletcher
authors.affiliation: Johnson Matthey Technology Centre, P.O. Box 1, Belasis Avenue, Billingham, Cleveland TS23 1LB, UK.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Holt
authors.affiliation: Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK. Electronic address: Sean.Rigby@Nottingham.ac.uk.
authors.forename: Sean P
authors.initials: SP
authors.lastname: Rigby
keywords: Adsorption; Advanced adsorption; Catalyst; Hysteresis; Mercury porosimetry; Pore size distribution; Scanning curve; X-ray imaging