MOLECULAR DYNAMICS SIMULATION OF ETHENE ADSORPTION, POLARIZATION AND DIFFUSION IN THREE KINDS OF ZEOLITES

Molecular dynamics (MD) simulation was performed to study ethene adsorption, polarization and diffusion in orthorhombic and monoclinic MFI and H[Al]ZSM-5 at 300 K. The results show that the interaction between ethene molecule and orthorhombic MFI is the strongest. Ethene molecules possess relatively low energy in the lattice of orthorhombic MFI. The existence of Al and Bronsted H atoms in the framework of H[Al]ZSM-5 can lower the energy of adsorbed ethene molecules. At the edges of intersections of channels, especially those near Al sites, ethene molecules are polarized most. Ethene molecules prefer the locations at the centers of channel intersections. The diffusion coefficients of ethene in the lattices of orthorhombic, monoclinic MFI and H[AI]ZSM-5 are 2.7 × 10-9, 2.1 × 1.6 × 10-9 m2·-1, respectively. The infrared spectrum of ethene in the framework of H[Al]ZSM-5 shows five vibration peaks (v10, v7, v12, v11, and v9), which is consistent with the experimental result.