Improved method for determining binary adsorption isotherms by using concentration pulse chromatography: adsorption of C
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Improved method for determining binary adsorption isotherms by using concentration pulse chromatography: adsorption of CO2 and N2 by silicalite at different pressures Dean Kennedy • F. Handan Tezel
Received: 20 January 2013 / Accepted: 19 July 2013 / Published online: 20 August 2013 Ó Springer Science+Business Media New York 2013
Abstract Adsorption separation of carbon dioxide from nitrogen at different system total pressures with silicalite as the adsorbent was studied by using concentration pulse chromatography. Improving the methodology for determining binary adsorption isotherms by concentration pulse method (CPM) was also the goal of this study. Binary adsorption isotherms, x–y phase diagrams and separation factor plots have been determined at 26 °C to look at the influence of pressure on the separation using concentration pulse chromatography. Available methods for determining binary adsorption isotherms using CPM have been reviewed and shown to be incapable of interpreting this particular binary system. An improved novel model has been proposed to interpret the data in this study. It has been referred to as the Kennedy-Tezel concentration pulse method (KT-CPM) and has been shown to be superior to other methods used in the literature. Results using this data were found to be consistent with the previous results in the literature. The binary isotherms for the CO2–N2 system show a decrease in CO2 selectivity as total system pressure increases. The optimal separation factor for silicalite was found to increase with decreasing system pressure and decreasing mole fraction of CO2 in the feed mixture.
Nomenclature A, B, C Parameters used in Eqs. (4) through (10) (mmol/g/atm) K Dimensionless constant (dimensionless) Dimensional constant (mmol/g/atm) Kp L Length of the column (m) na Amount of gas adsorbed for pure systems (mmol/g) P Pressure (atm) q Amount adsorbed (mmol/g) R Universal gas constant (L atm/mole/K) t Time (s) T Temperature (K) x Mole fraction in the adsorbed phase (dimensionless) y Mole fraction in the gas phase (dimensionless)
Keywords Mixture adsorption Binary adsorption isotherms CO2 N2 Concentration pulse chromatography Silicalite
Greek symbols a Adsorption separation factor (dimensionless) c Parameter in Eq. (4) through (10) e Bed porosity (dimensionless) h Parameter in Eqs. (4) through (10) l Mean retention time (s) m Interstitial velocity (cm/s)
D. Kennedy F. Handan Tezel (&) Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur, Ottawa, ON K1 N 6N5, Canada e-mail: [email protected]
Abbreviations CPM Concentration pulse method GC Gas chromatograph
Subscripts A Component A B Component B i Index max Maximum min Minimum total Total
123
190
GHG HT-CPM KT-CPM MFC MTT-CPM MVV-CPM SSR TCD
Adsorption (2014) 20:189–199
Green house gases Harlick and Tezel-concentration pulse method Kennedy and Tezel-concentration pulse method Mass flow controller Modified Tiebe and Tezel-concentration pulse method Modified Van der Vlist and Van der Meijden
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