The study of porous metal-organic framework (MOF) materials has attracted considerable attention. We seek to develop new stable MOFs for practical separation of light hydrocarbons and request 3 days on WISH to study the preferred binding sites of adsorbed gas molecules (C2D2, C2D4, C2D6, C3D6 and C3D8) within a MOF (MFM-520). MFM-520 has shown excellent separation property of light hydrocarbons via dynamic breakthrough experiments under ambient conditions. The high resolution, low background and large d-spacing capabilities of WISH make it ideal for analysing the precise locations of gas molecules within these porous MOFs and to define the preferred orientations of molecules with respect to the binding sites on the pore surface. This study will reveal key structural insights into the exciting gas separation of this MOF.