Extending Reversed-Flow Chromatographic Methods for the Measurement of Diffusion Coefficients to Higher Temperatures
William S. McGivern, Jeffrey A. Manion
A reversed-flow chromatographic apparatus for the measurement of binary diffusion coefficients is described and utilized to measure the binary diffusion coefficients for several systems at temperatures from (300723) K. Hydrocarbons are detected using flame ionization detection, and inert species can be detected by thermal conductivity. Such an apparatus has been used previously for determining diffusion coefficients near room temperature, but the present apparatus is capable of measuring coefficients to much higher temperatures. Characterization of the new apparatus was accomplished by comparing measured binary diffusion coefficients of dilute argon in helium to established reference values. Further diffusion coefficients for dilute helium in argon as well as nitrogen in helium were measured using a thermal conductivity detector. Dilute methane in helium diffusion coefficients were measured using flame ionization detection and found to be in excellent agreement with literature values. The measurement of these well-established diffusion coefficients has demonstrated that specific experimental conditions are required for accurate diffusion measurements using this technique, particularly at higher temperatures. Numerical simulations of the diffusion experiments have shown that these nonidealities are an artifact of the analysis procedure ysuitable measurement conditions, particularly at higher temperatures.
and Manion, J.
Extending Reversed-Flow Chromatographic Methods for the Measurement of Diffusion Coefficients to Higher Temperatures, Journal of Chromatography A, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=908674
(Accessed December 8, 2023)