A theoretical analysis on the separation of mixtures by extractive adsorption

Abstract

A new approach to the separation of chemical mixtures by way of extractive adsorption is proposed. The approach relies on the use of adsorbents with single file pores, for which clusters of aligned dipoles can result in a 1D ferroelectric phase. To study this class of separations, a new theory is developed for the adsorption of polar species in single file pores based on a 1D approximation of classical density functional theory (CDFT). The theory is applied to pure, binary and ternary mixtures composed of hydrogen cyanide, formaldehyde and ethylene. It is demonstrated that adsorbing polar molecules in single file channels do undergo ferroelectric transitions, under certain conditions. These transitions result in step like isotherms with wide hysteresis loops. It is then shown that inclusion of the adsorbate solvent hydrogen cyanide, can extract formaldehyde from a hydrogen cyanide, formaldehyde, ethylene mixture.