|Example of mechanochemical production of a MOF. Pichon et al. Click to enlarge.|
Chemists at Queen’s University Belfast (Ireland) have devised a novel environmentally friendly technique which allows the rapid production of metal-organic frameworks (MOFs). The technology is to be commercialized by a spin-out from the University, MOF Technologies. One of the first areas expected to benefit from the technology is storage tanks for natural gas vehicles (NGVs), according to the company.
MOF manufacturing techniques have been limited as they are costly, slow and require large quantities of solvents, which can be toxic and harmful to the environment. Professor Stuart James in Queen’s School of Chemistry and Chemical Engineering patented a novel technique for the synthesis of MOFs without using any solvents, even water, and on greatly reduced timescales, by making use of mechanochemistry.
By simply grinding together two cheap precursors in a basic milling machine, the MOF material is produced in a matter of minutes, in a powder form, ready for applications without further treatment, and without generating solvent waste.—Prof. James
Granting of the patent enabled the formation of MOF Technologies from Queen’s spin-out arm QUBIS. Seed funding has been provided by both QUBIS and NetScientific, which specializes in commercializing technologies developed within university laboratories. MOF Technologies also was recently awarded the NISP (Northern Ireland Science Park) Connect £25K Award which is designed to identify, qualify, prepare and present the intellectual property with the most commercial potential from NI’s publicly funded research base.
NGV applications. MOFs are crystalline, sponge-like materials composed of two components: metal ions and organic molecules (linkers). The choice of metal and linker has significant effects on the structure and properties of a particular MOF. MOFs have the highest surface-areas of any known materials; this incredibly high surface area means that MOFs are very good at storing gases. There are an abundance of sites where gas molecules can adsorb to the material.
Becoming increasingly attractive due to a number of advantages over conventional, gasoline-fueled vehicles, NGVs still have issues around storage and refueling. Typically, natural gas is stored at very high pressures—up to 300 atmospheres (4,400 psi) requiring heavy, cylindrical storage tanks These must be filled at special refueling stations using large compressors. MOFs could enable higher storage capacities at much lower pressures.
By enabling higher storage capacities at much lower pressures, storage tanks don’t need to be as strong, so they can be much lighter and may even be shaped to fit the free space available. The lower storage pressure also means that new, costly refueling infrastructure such as specialized filling stations is no longer required and opens up the possibility of refueling vehicles in the home, from domestic gas supplies. The same gas supplies that power our central heating and gas ovens.—Prof. James
MOF Technologies is also hoping to exploit opportunities in global carbon capture, hazardous gas storage, natural gas processing and hydrocarbon separations.
Anne Pichon, Ana Lazuen-Garay and Stuart L. James (2006) Solvent-free synthesis of a microporous metal–organic framework. CrystEngComm, 8, 211-214 doi: 10.1039/B513750K