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.