Propane-propylene binary adsorption on zeolite 4A

In this work we report new experimental data of pure and binary adsorption equilibrium of propane and propylene on zeolite 4A at 423 and 473 K. The pressure range studied was 0-500 kPa, which is the entire pressure range used in PSA-VSA (Pressure-Vacuum Swing Adsorption) units. The amount adsorbed of propane is much higher than that reported in previous literature. Propane diffusivity was estimated from uptake curves in the linear isotherm region. Adsorption of propane was extremely slow and equilibrium was established only after three days of adsorbate-adsorbent contact. The IAST (Ideal Adsorbed Solution Theory) using the Generalized Dubinin model to describe the pure propylene equilibrium and the Langmuir model for propane predicted with acceptable accuracy the binary adsorption data. Alternatively, the multisite model of Nitta was used to fit pure component isotherms and used in the IAST. Predictions were worse than those with the other strategy.