Continuous microfluidic synthesis of zirconium-based UiO-67 using a coiled flow invertor reactor

Abstract

Metal-organic frameworks (MOFs), particularly Zirconium based, have a wide variety of potential applications, such as catalysis and separation. However, these are held back by traditionally only being synthesised in long batch reactions, which causes the process to be expensive and limit the amount of reaction control available, leading to potential batch to batch variation in the products, such as particle size distributions. Microfluidics allows for batch reactions to be performed with enhanced mass/heat transfer, with the coiled flow inverter reactor (CFIR) setup narrowing the residence time distribution, which is key in controlling the particle size and crystallinity. In this work, a Zirconium based MOF, UiO-67, has been synthesised continuously using a microfluidic CFIR, which has allowed for the product to be formed in 30 min, a fraction of the traditional batch heating time of 24 h. The microfluidicially synthesised UiO-67 is also smaller product with a narrower particle size distribution (≈200 nm to ≈400 nm) than its batch counterpart (~500 nm to over 3 µm).

Recent advances in continuous flow synthesis of metal–organic frameworks and their composites

“…73,75 This is exemplified by the synthesis of UiO-67 in a microfluidic reactor, which produces the material in 30 minutes -a fraction of the traditional batch heating time of 24 hours. 76 The flow-synthesized UiO-67 is also smaller with a narrower particle size distribution compared to its batch counterpart. Recently, a team of researchers employed a continuous flow reactor to study the crystallization kinetics of MOF-808 using time-resolved techniques.…”

Flow Chemistry: A Sustainable Voyage Through the Chemical Universe en Route to Smart Manufacturing

“…Therefore, the performance of inorganic materials, often based on optical, electronic, and catalytic properties, can be controlled through tuning microfluidic process parameters such as temperature, mixing time, and residence (reaction) time. The precise control over synthesis parameters microfluidic reactors afford has led to the synthesis of high-performing inorganic nanomaterials, including noble metal and metal oxide nanoparticles (87,88), metal-organic frameworks (89,90), silica nanoparticles (91), and various quantum-confined nanostructures (92). In addition, microfluidic synthesis methods enable scalable production of process-sensitive materials.…”

Droplet‐Based Millifluidic Synthesis of a Proton-Conducting Sulfonate Metal–Organic Framework

“…The droplets are isolated from the reaction channel walls by using a second phase as an inert 'carrier', which can eliminate reactor fouling due to the precipitation of reactants or products, providing a stable reaction environment during continuous synthesis [47]. The development of continuous syntheses for a number of carboxylate and imidazolate MOFs [48][49][50][51][52][53] now prompts the exploration of such techniques for the distinct coordination chemistry of sulfonate MOFs.…”