Comparative study of the dynamic gravimetric and pulse chromatographic methods for the determination of Henry constants of adsorption for VOC–zeolite systems

Abstract

In this paper, we propose a comparative study between a gravimetric apparatus operating under dynamic conditions and a pulse chromatographic device developed for the determination of Henry constants of adsorption for VOC–zeolite systems. In both cases, we provide a description of the experimental set-up and procedure, as well as a complete report on the treatment of the rough experimental data. The experimental errors are also discussed. The comparison work is based on the study of the adsorption of toluene on a NaY zeolite (Si/Al 2.43) for temperatures ranging from 503 to 623 K. The maximal discrepancy found between the experimental Henry constants was 15.0%. The pulse chromatographic method is only dedicated to high-temperature measurements. For low-temperature experiments, the rough data cannot be treated in an efficient way, and it is not possible to obtain reliable Henry constant values. The dynamic gravimetric method is not temperature limited. It is however time-consuming, especially when low-temperature measurements (not presented in this paper) are concerned. Both methods are complementary if the determination of Henry constants is required in a wide temperature range.

Adsorption of Alkanes and Aromatic Compounds on Various Faujasites in the Henry Domain. 2. Composition Effect in X and Y Zeolites

“…For toluene, the shape is slightly different and gives a deviation around 12 kJ·mol -1 for Δ U . Other previous works ,, on the comparison of the toluene Henry constant show a good agreement at high temperature between the two experimental techniques (chromatography and gravimetry), as in the range (230 to 350) °C, the maximum deviation on the Henry constant is 15 % and the average deviation is 7.5 %.…”

Adsorption of Alkanes and Aromatic Compounds on Various Faujasites in the Henry Domain. 1. Compensating Cation Effect on Zeolites Y

“…The details of the experimental procedure can be found in our previous work. 18 Treatment of the Chromatographic Measurements. At the end of the experimental run, the following measurements were provided.…”

“…[4][5][6]12,13,19 with ) i + p (1i ) and where µ is the retention time (s); V column is the column volume (m 3 ); V d is the dead volume between the injector and the detector (m 3 ); Q T is the total volume flow (m 3 ‚s -1 ); T is the bed temperature (K); R is the ideal gas constant (J‚K -1 ‚mol -1 ); is the total porosity; i is the interstitial bed porosity; p is the pellet macroporosity; F c is the crystal density (kg‚m -3 ); and K′ is the Henry constant (mol‚kg -1 ‚Pa -1 ). Equation 1 may be written 18 where m pellets is the pellet mass in the column. µ was determined by the appropriate statistical treatment of c(t).…”

“…The maximum relative error in K is 8 % according to the error analysis. 18 K 0 is the pre-exponential dimensionless constant, and ∆U is the adsorption energy (J‚mol -1 ). The isosteric heat of adsorption at zero coverage, ∆H (J‚mol -1 ), is calculated by Column Characteristics.…”

Equilibrium and kinetic analysis of CO2–N2 adsorption separation by concentration pulse chromatography

“…This method, which indirectly measures the adsorption parameters, has been shown to agree well with gravimetric and volumetric data. Concentration pulse chromatographic technique was found to be simpler and quicker for the determination of binary adsorption isotherms, as well [4,[12][13][14][15][16].…”