Adsorption of Alkanes in Zeolites LTA and FAU: Quasi-Equilibrated Thermodesorption Supported by Molecular Simulations

Adsorption of n-alkanes from pentane to decane (C5–C10) in zeolites LTA (ITQ-29 and 5A) and FAU (dealuminated high-silica Na-FAU, NaY, and NaX) as well as branched hexane isomers in FAU was investigated by means of experimental quasi-equilibrated temperature programmed desorption and adsorption (QE-TPDA) and theoretical Monte Carlo molecular simulations. A novel QE-TPDA method of studying porosity provided high quality desorption-adsorption profiles and adsorption isobars of hydrocarbons. A unique two-step adsorption of long-chain alkanes in LTA zeolites was observed and explained in detail based on the results of the theoretical calculations. Although adsorption of n-alkanes in FAU is one-step process, it also does not occur in uniform manner due to strong lateral interactions at high loadings. We also investigated the influence of cation content on adsorption equilibrium and energetics for the studied adsorbent–adsorbate systems finding non-linear relation between heat of adsorption and content of catio...