Utilization of Pisat temperature-dependency in modelling adsorption on zeolites

In this study, the feasibility of utilizing pure component saturated vapour pressure Pisat in representing the temperature-dependency of physisorption of vapours on zeolites is examined. Adsorption data of water, alcohols and aromatic compounds both on hydrophilic on and hydrophobic zeolites has been collected from the literature and represented as a function of P/Pisat. It is found that the temperature-dependency of adsorption of a component can be described by the saturated vapour pressure, especially for water adsorption on zeolites. For systems where chemisorption also plays an important role, such as aromatics adsorption on zeolites, Pisat alone is not capable of predicting the temperature-dependency accurately enough. It is also observed that contrary to common practice, the maximum adsorption loading qisat on zeolite should be considered independent of temperature. The proposed approach can be used in the modelling and design of industrial processes exploiting adsorption, such as in zeolite membrane systems, where separation is based on both adsorption and diffusion phenomena.

► Pisat alone is able to cover temperature-dependency of physisorption on zeolites. ► A systematic approach to model adsorption on zeolites is introduced. ► The proposed approach is not bound to any particular isotherm formulation. ► Adsorption on zeolites can be predicted based on data at only one temperature. ► The saturation loading on zeolites should be considered independent of temperature.