STRUCTURAL INVESTIGATIONS ON MFI NAPHTHAL ENE SYSTEMS BY X-RAY-POWDERDIFFRACTION - INFLUENCE OF FRAMEWORK A1 OR B-ATOMS ON THE UNIT-CELL PARAMETERS AND THE LOCALIZATION OF THE NAPHTHALENE MOLECULE

Interpretation of X-ray powder diffraction profiles corresponding to z eolitic MFI.nNPH (naphthalene) complexes for several framework composi tions, shows that the sorbate molecule is located at the channel-inter sections and that naphthalene adsorption provokes an important ellipti cal deformation of the straight-channels of the MFI topology. For 0 < n < 2 and for all the framework compositions, the MFI/nNPH system is d iphased (bare MFI + MFI.2NPH), whereas for 2 < n < 4 the investigated MFI.nNPH complexes correspond to a solid solution presenting the ortho rhombic Pnma symmetry. In all cases the saturation of the microporous zeolitic material corresponds to 4 molecules/unit-cell.