Prediction of adsorption isotherms of C3H6/C3H8 on hierarchical porous HP–Cu–BTC

Abstract

The isotherms of C3H6 and C3H8 on three distinct HP–Cu–BTCs were determined using the static volumetric capacity technique across the pressure range 0–100 kPa, and the resulting experimental data set was regressed using the dual–site sips (DSS) model. The kinetics and thermodynamics of C3H6 and C3H8 on HP–Cu–BTCs were studied. The results show that the adsorption kinetics of the three samples conform to the pseudo–first–order kinetic model, indicating that the adsorption process of the HP–Cu–BTCs samples is the adsorption process with physical adsorption as the control step. The thermodynamic analysis results show that the adsorption of propylene and propane on the surface of HP–Cu–BTCs are a spontaneous exothermic process, because the transition of propylene and propane from three–dimensional motion to two–dimensional motion leads to a decrease in the system entropy. In addition, the isosteric heat of adsorption (Qst) was used to predict the isotherms of C3H6 and C3H8 at 298 and 303 K, respectively. When the predicted and experimental values are compared, the predicted isotherms are shown to be fully associated with the experimental values, with mean relative errors (MRE%) of less than 2%. Additionally, the C3H6 and C3H8 adsorption isotherms and selectivity for C3H6 adsorption were predicted using a combination of the DSS model and ideal adsorbed solution theory (IAST). The findings suggest that the overall adsorption capacity of the mixes rose as the mole fraction of C3H6 increased, but the adsorption capacity of the equimolar C3H6 and C3H8 in the three HP–Cu–BTC combinations was smaller than the pure component. Additionally, an undetectable shift in C3H6/C3H8 selectivity was seen when the molar percentage of C3H6 increased.