FIGURE 1 (a) 3D framework of MIL-120Al; (b, c) molecular size of CH4 and N2; (d) illustration of the different kinetic effects of CH4 and N2through the window of MIL-120Al. Color code: C, gray; H, white; O, red; Al, cyan; N, blue.
The structure of MIL-120Al was constructed using infinite rod building blocks and BTEC ligands, which exhibits a novel three-dimensional open-framework. Figure 1a shows the rhombic open 1D channels of MIL-120Al were formed along the c-axis and the pore walls were formed by the aromatic ring parallel to the c-axis. The pore diameter was measured to be 5.4 × 4.7 Å.40 Obviously, the pore size was slightly larger than the dynamic diameter of CH4 and N2 (Figures 1b, 1c), suggesting its potential application for the kinetic separation of CH4/N2 (Figure 1d).