Synthesis and characterization of an amino functionalized MIL-101(Al): Separation and catalytic properties

A new MIL-101 material based on aluminum and containing amine functional groups has been synthesized. The pure phase NH₂-MIL-101(Al) can only be formed in very specific synthesis conditions, where both the metal source and the solvent used play a key role. The resulting porous solid shows a high thermal and chemical stability, decomposing at temperatures above 650 K in air. The NH2-MIL-101(Al) framework offers an excellent trade off for separation of CO₂: the combination of high stability, acceptable capacity at low adsorbate partial pressures, high selectivity, and fast regenerability makes this new material a very attractive candidate for applications like natural gas or biogas upgrading. CO₂ capacities up to 62 wt % are obtained at room temperature and 3 MPa. In addition to an excellent separation performance, the NH2- MIL-101(Al) shows a high activity in the basic catalyzed Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate at 313 K even in an as apolar a solvent as toluene (turn over frequency, TOF = 1.8 h¹).