Adsorption Equilibria of Propylene and Propane on Zeolites and Prediction of Their Binary Adsorption with the Ideal Adsorbed Solution Theory

Abstract

Adsorption equilibrium isotherms of propane (C3H8) and propylene (C3H6) on commercial zeolite 5A (UOP), zeolite 13X (Z10-04, Zeochem), and laboratory synthesized titanosilicate Na-ETS-10 were measured using a gravimetric microbalance at 298, 323, 343, 373, and 423 K and over 0 to 300 kPa. The isotherm data were fitted to different isotherm models. A Microsoft Excel based code for solving Ideal Adsorbed Solution Theory (IAST) was validated against literature reported multicomponent isotherm data. The binary adsorption selectivity of propylene over propane was predicted with this IAST solver for two feed compositions, namely, equimolar propane/propylene mixture and 85 mol % propylene with balance propane representing steam cracker and fluid catalytic cracker (FCC) off gas, respectively. High selectivity values in excess of 25 are obtained for Z10-04. Propylene to propane selectivity for Z10-04 and Na-ETS-10 decreases with an increase in temperature, and for zeolite 5A (UOP) the selectivity improves with an increase in temperature.