Abstracts of 10th IGC Symposium 2021

Inverse Gas Chromatography applied in the analysis of heterogeneous catalysts used in the synthesis of fine chemicals

Jan Schütz, Senior Scientist, DSM, Switzerland

DSM Nutritional Products is active in the field of nutraceuticals. Most of the vitamins and several carotenoids are manufactured by DSM. The processes require in many cases heterogeneous catalysts and often continuous set-ups are used. In one of such processes a silica based catalyst is used in a fixed bed reactor. The spent (and fresh) catalyst was studied with regard to its surface by IGC and the results were correlated to the activity of catalyst samples from different positions in the reactor. This approach allowed to understand better the deactivation mechanism of the catalyst in the reactor over time, leading to process improvements in the plant reactor.

Study of the Permeability of Low Molecular Weight Alcohols in Hydroxylpropyl Xylan Films Using Inverse Gas Chromatography

Philip YK Choi, Professor, University of Alberta, Canada

Inverse gas chromatography (IGC) was used to study the effect of humidity on the permeability of selected low molecular weight alcohols (methanol, ethanol, propanol and butanol) through films made up of a hydrophilic polymer hydroxypropyl xylan (HPX).  The thin films used consisted of a neat HPX film and a HPX film with sorbitol, a commonly used food grade plasticizer, (HPX/Sorbitol) and a HPX film with sorbitol and cellulose nanocrystal (CNC) (HPX/Sorbitol/CNC).  Diffusivity and solubility of the alcohols at infinite dilution were measured at relative humidity (RH) values of 0%, 30%, 50% and 70% of the carrier gas (helium).  Permeability was then calculated using the measured diffusivity and solubility.  Diffusion coefficients of the alcohols showed a maximum at about 50% RH in all films.  And solubility coefficients of the alcohols were more or less insensitive to the RH.  Permeability coefficients of the alcohols exhibited a maximum at around 50% RH as well suggesting that diffusion, not dissolution, dominated the permeability behaviour.  The RH dependence of diffusion, thereby permeability, was attributed to the combined effects of plasticizing, swelling, water clustering and alcohol-water clustering.  The measured weight-fraction-based Henry’s constants suggested that water contents in the films were relatively low, suggesting that water clustering might only take place in the neat HPX film at 70% RH.

Surface Interaction Parameters via IGC – A Next Generation Concept

Steven Abbott, Consultant, Ipswich, UK

Abstract: Suppose we could routinely measure infinite dilution retention times with a diverse collection of solvent probes at different temperatures rather than a set that emphasises alkane interactions. This might allow us to provide objective measures of the dispersive, polar and H-bonding properties of the surface, using Surface Interaction Parameters, SIPs, as SD, SP, SH, along with a 4th parameter, SR to capture surface (nano)roughness. The talk outlines the basic science of the proposal, provides an initial worked example, and invites participants to give their views about whether it’s a good or bad idea.