C2-Hydrocarbon Adsorption in Nano-porous Faujasite: A DFT Study

The shape, interaction and stability of adsorbed C2-hydrocarbon, ethane and ethylene, molecule in a nano-porous cages of zeolite molecular sieves, e.g. Faujsite, were studied by cluster based Density Functional Theory (DFT). The interactions of ethylene and ethane on nano-porous Faujasite with varying size of extra-framework cations, e.g. Li < Na < K < Rb < Cs, have been investigated using generalized gradient approximation (GGA) with PW91 correlation functional. A cluster model was taken from the single crystal data of Faujasite to investigate the interaction between nano-porous zeolite and C2-hydrcarbon. Additionally, ethane and ethylene with naked monovalent cations were optimized using the same PW91 level theory. DFT were employed to get the geometries, Mulliken partial charges and adsorption binding energies for zeolite cluster with varying size of cations. These geometric and energetic data were analyzed with respect to the size of cation. DFT results suggest that if smaller the size of the extra-framework cations stronger will be the hydrocarbon interaction in nano-porous Faujasite even if there would specific interaction.