Modeling of multi-temperature Type I and II benzene/ammonia adsorption isotherms: Dual LF model and linearized DR model

Abstract

Adsorption isotherm is basic data for evaluating the porous adsorbent adsorption capacity and explaining gas–solid adsorption behavior. Adsorption equilibrium modeling is a simple method to describe isotherm data in application. In this paper, taking C6H6 and NH3 as an example, multi-temperature Type I or Type II adsorption isotherms on AC, ASZMT, and 13X were investigated and fitted. Results show that C6H6 and NH3 adsorption behaviors on 13X both existed in chemisorption. At certain adsorbed capacity, the isosteric heats are higher than 50 kJ·mol−1. Type I and Type II C6H6 or NH3 adsorption isotherms could be successfully described using the extended Dual LF model·NH3 temperature-independent characteristic curves on AC and ASZMT were obtained using the Linearized DR model and successfully used to predict NH3 adsorption data at any pressure within the whole room temperature. Further, the Dual LF model was extended to describe other adsorption isotherms including IUPAC Type III, IV, and V. The R2 between the model and data were higher than 0.98, proving that it has universal applicability than other classical models such as Langmuir, Freundlich, Toth, and so on. It has the potential to be used as a general equilibrium model for adsorption process simulation in the future.