Solvents are omnipresent in the chemical industry, and are a major environmental and safety concern. Therefore the large interest in mechanochemistry: an energy-efficient alternative that avoids using bulk solvents and uses high-frequency milling to drive reactions. Milling is achieved by the intense impact of steel balls in a rapidly moving jar, which hinders the direct observation of underlying chemistry. Scientists have now for the first time studied a milling reaction in real time, using highly penetrating X-rays to observe the surprisingly rapid transformations as the mill mixes, grinds and transforms simple ingredients into a complex product. This study opens new opportunities in Green Chemistry and environmentally-friendly synthesis. The results are published in Nature Chemistry dated 2 December 2012.
The international team of scientists was led by Tomislav Friščić of McGill University (Canada) in collaboration with Ivan Halasz from the University of Zagreb (Croatia), scientists from the University of Cambridge (UK), Max-Planck-Institute for Solid State Research in Stuttgart (Germany) and the European Synchrotron Radiation Facility (ESRF) in Grenoble (France).
Everybody remembering their chemistry lessons will recall mixing ingredients into a solvent. This was sometimes water, but more often a solvent such as ether (flammable), chloroform (toxic) or benzene (cancerogenic). Bulk solvents used in industry pose a serious threat to human health and the environment, and their responsible management has a considerable cost. Although it is well known that mechanical action can break chemical bonds, for example in tear and wear of textile fibres, it is much less known that mechanical force can also be used to synthesize new chemical compounds and materials. In recent years, ball milling has become increasingly popular in the production of highly complex chemical structures. In such synthesis, steel balls are shaken with the reactants and catalysts in a rapidly vibrating jar. Chemical transformations take place at the sites of ball collision, where impact causes instant "hot spots" of localized heat and pressure. This is difficult to model and, without access to real time reaction monitoring, mechanochemistry remained poorly understood. "When we set out to study these reactions, the challenge was to observe the entire reaction without disturbing it, in particular the short-lived intermediates that appear and disappear under continuous impact in less than a minute", says Tomislav Friščić, a Professor at McGill University in Montreal.
The team of scientists chose to study mechanochemical production of the metal-organic framework ZIF-8 (sold as Basolite Z1200) from the simplest and non-toxic components. Materials such as ZIF-8 are rapidly gaining popularity for capturing large amounts of CO2 and, if manufactured cheaply and sustainably, could become widely used for carbon capture, catalysis and even hydrogen storage. "The team came to the ESRF because of our high-energy X-rays capable of penetrating 3 mm thick walls of a rapidly moving reaction jar made of steel, aluminium or plastic. The X-ray beam must get inside the jar to probe the mechanochemical formation of ZIF-8, and then out again to detect the changes as they happened", says Simon Kimber, a scientist at the European Synchrotron Radiation Facility (ESRF) in Grenoble, who is a member of the team. This unprecedented methodology enabled the real-time observation of reaction kinetics, reaction intermediates and the development of their respective nanoparticles.
This technique is not limited to ZIF-8. In principle, all types of chemical reactions in a ball mill can now be studied and optimized for industrial processing. 'These results hold promise for improving the fundamental understanding of processes central to pharmaceutical, metallurgical, cement and mineral industries and should enable a more efficient use of energy, reduction in solvent and optimize the use of often expensive catalysts. This translates into good news for the environment, the industry and the consumers who will have to pay less", concludes Tomislav Friščić.
European Synchrotron Radiation Facility: http://www.esrf.fr
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
Apeel Sciences hopes its products, which use natural methods to fend off pests and oxidization, can markedly reduce the amount of produce wasted because of spoilage.
Francis Halzen’s amazing experiment heralds the beginning of a new era in astronomy
First direct detection of dark matter, thought to make up most of the matter in the universe, would be a historic breakthrough
Geologists, climate scientists, ecologists and a lawyer gather in Berlin for talks on whether to rename age of human lifeHumanitys terrifying impact on Earth justifies new Anthropocene epoch
This month in Italy, three judges have a chance to undo the Kafkaesque nightmare that has ensnared some of the country’s top scientists for almost five years. So far it looks doubtful they will. In 2012, seven scientists and engineers were convicted of manslaughter for things they said and did not say in the days
Turkey's eternal fires have remained burning for thousands of years but now the source of the methane that fuels them has been found
Lockheed Martin Corp said on Wednesday it had made a technological breakthrough in developing a power source based on nuclear fusion, and the first reactors, small enough to fit on the back of a truck, could be ready for use in a decade.
But the hotspot predates the use of hydraulic fracking in the region, putting renewed attention on how older forms of natural gas production contribute to global climate change
A complicated technique used on LHC data for the first time has revealed two new particles, one of which has a combination of properties never seen before
Traditional method of insect harvesting is revived as cochineal insects are once-again valued for their brilliant red pigment