What are MOFs?
Metal-Organic Frameworks (MOFs) are crystalline, hybrid materials containing metal ions and organic molecules; components that together forms a three-dimensional structure. The material is known for its high porosity and large surfaces and its components allow for various combinations of organic and inorganic blocks. These blocks give rise to millions of different possible structures.
The unique features of MOFs, such as their large surface-areas and diversity of structures, makes the them suitable to a broad range of industrial processes. MOFs are, for instance, very well suited for storing and transportation of gases, separation of gases, water absorption, catalysis or even adsorption cooling and drug delivery. MOFs have the highest surface-area of any known materials, they are very light, porous, and their structure can be designed for a wide variety of purposes. The MOF-structure can, for instance, be designed to capture specific gases and chemicals, while other substances pass through. MOFs are therefore well suited for efficient separation processes. Increased efficiency of gas storage is another notable application. The large surface-area of MOFs enables them to adsorb large amounts of gas, making possible greater storage capacities.
The latest developed MOFs, are a relatively new class of hybrid materials, these MOFs have been the subject of immense interest in recent years. Their increased stability, makes them so unique that they most certainly will play an important role in future industrial processes.
How is it produced?
There are several methods used to synthesize highly functionalized MOFs. However, the most common process is called solvothermal batch reaction, a method that requires high temperatures (160-250°C), long reaction times, and the use of dangerous solvents such as N,N-Dimethylformamide. Although the production of MOFs has previously been highly dependent on this method, it has been criticized for both environmental and economic reasons. However, ProfMOF has proven an alternative method in recent years synthesizing MOFs using water as solvent. This method for advanced sustainable and environmental-friendly synthesis represents a shift towards green chemistry.
The stability of MOFs is largely determined by its structure and the nature of the chemical bonds formed between metals and organic molecules. A major concern regards industrial application of MOFs has been the poor stability of most MOFs. This issue has been resolved thorough the development of MOFs with exceptional thermal, chemical, and mechanical stability. The most widely known type of ultrastable MOFs was developed by scientists at The University of Oslo (UiO) and is called UiO-66. The MOFs in the UiO-66 family of materials are comprised of the Zr₆(O)₄(OH)₄ building blocks. The UiO-66 MOFs are stable up to 400 degrees and can have large surface-areas from 800 to 7000 m²/g.