Characterisation of heterogeneous solid surfaces by multiple probe, temperature-programmed inverse gas chromatography (IGC). A feasibility study

Abstract

A method is described for the characterisation of the surfaces of powdered solids by temperature programmed, multiple-probe, inverse gas chromatography. This modification of "traditional" inverse gas chromatography (IGC) allows rapid screening of solid surfaces to compare the adsorptive behaviour of pairs or sets of surfaces. This feasibility study examined the criteria for selection of a suitable probe set and approaches to the analysis and interpretation of the data generated. The technique was used to compare carbon black samples, chosen for their surface heterogeneity and the difficulty of surface characterisation using other techniques. The choice of a low surface area, methylated silica solid diluent and the elimination of its influence on the measurements is discussed. The probe set selected readily distinguished the carbon black samples and allowed tentative conclusions to be drawn regarding steric and electronic influences on probe-solid interactions.

Surface activity studies on carbon-silica dual phase fillers using flow microcalorimetry and multiple probe temperature programmed inverse gas chromatography

“…CB3 and CB1 show little or no retention of the latter alkene and alkane probes but somewhat stronger retention of pinacolone and benzene. These data are entirely consistent with an earlier MPTPIGC study [10] and indicate that CB2 has surface features that are able to make intimate contact with hydrocarbon molecules in their Figure 5. Normalised absolute retention temperature MPTPIGC data represented as radar graphs (the graph for S3 is not shown as it is similar to that for S2 but with half as much pinacolone retention).…”

“…Removal of all heteroatoms (mainly oxygen and sulphur) by graphitisation drastically reduces the adsorption activity. The radar graphs for CB1 and CB2 (also analysed in a previous work [10,16]), however, indicate that adsorption of the hydrocarbon probes is not merely related to heteroatom content. CB2 is a much purer carbon black than CB1; this is reflected in the FMC adsorption activity with polar probes reported previously [16].…”

“…McMahon of the MMU research group has developed a high throughput IGC method where a cocktail of probes is injected onto a temperature programmed column of filler [10]. Retention temperature is therefore utilised as the relative measure of probe-filler interaction.…”