(472f) Continuous Flow Synthesis of the Metal-Organic Framework HKUST-1 in a Millifluidic Reactor

Metal-organic frameworks (MOFs) are a class of crystalline and porous adsorbents, with wide-ranging applications in gas separations, membrane materials as well as sensors. The basic unit of a MOF consists of metal ions coordinated to organic ligands, which form a coordination polymer with well-defined lattice positions in the crystalline unit cell. The properties of a particular MOF can be finely tuned for a given application through the use of multiple ligands, metal ions and modulators for tuning particle sizes. Conventional lab-scale synthesis procedures for MOFs are autoclave batch reactions with residence times of a day or more. These procedures entail solvothermal synthesis, with expensive and often toxic solvents and starting materials. This explains the reason for a few of them being sold on commercial chemical vendor outlets at exorbitant rates. Thus, given their multifarious applications, economically viable synthesis of MOFs at the industrial scale is the need of the hour.

In this study, we have developed a continuous, droplet-based synthesis procedure of the MOF HKUST-1 in a millifluidic reactor. The droplets consist of aqueous solutions of copper ions, trimesic acid, and various solvent mixtures. Millifluidic reactor comprised of a custom made heating unit including machined metal block and 3D printed parts. Various reaction chemistries for synthesis of HKUST-1 via continuous and batch operation were investigated. We present an ultra-low residence time continuous synthesis of HKUST-1 and compare the physical characteristics and yield with batch synthesis of the same.