Investigating the Determination of Diffusion Coefficients of Butane in Hydrogen, by Reversed-Flow Inverse Gas Chromatography

Reversed-flow inverse gas chromatography (RF-IGC) combined with a flame ionization detector (FID) was used to determine diffusion coefficients of butane in hydrogen over a wide temperature range 287.7–518.2 K, at atmospheric pressure. These results provide the first experimental diffusivities for C4H10 in H2. Hydrogen served both as carrier gas and as FID fuel gas, which required modification of the flow arrangement. Digitization of the chromatographic signal allowed two mathematical models, based on short-time and long-time analysis of the concentration–time response, to be applied and compared. The accuracy of the short-time and long-time methods was 99.3% and 99.4%, respectively. The short-time diffusivities deviated slightly from the Fuller–Schettler–Giddings (FSG), Gilliland and Huang et al. equations by 6.2%, 4.6% and 6.1%, respectively. The long-time analysis provides smaller diffusivities, from 6.1 to 13 %, than those determined by long time model, with bigger deviations of 16%, 15% and 13% from the FSG, Huang et al. and Gilliland equations, respectively. The temperature exponents were: 1.72 ± 0.02 for the short-time analysis and 1.59 ± 0.03 for the long-time analysis models, respectively. Long-time analysis model is simpler, slightly more accurate at higher temperatures, but in the case of the studied C4H10 in H2 system provides smaller diffusivities and more deviating from the predicted values than those determined in the case of short-time model, which is accurate but more complicated in terms of estimations procedure.