Chemistry Article Summary

Golds magic number\n20 August 2008\nA unfermented specie throttle develop by UK chemists can catalyse hydrocarbon oxidation, victimization O2 as the but oxidant. But gun mote size is critical - to a higher place 2nm diameter, the catalyst loses all activity.\nThe catalyst was developed by Richard cubic decimeter and colleagues at the University of Cambridge, who used styrene oxidation as a test reaction. The team up assemble that the reaction didnt require any(prenominal) assetal oxidants such as peroxides. Oxygen subatomic particles adsorbed to the gold particles, and whence dissociated to give single oxygen atoms that initiated the styrene oxidation. Styrene is a truly good test molecule which can be handled easily, says Marc Armbrüster, who withal works at the University of Cambridge and collaborates with the group. Oxygenated hydrocarbons be withal valuable intermediates for industry.\nThe luck of selective oxidation using molecular oxygen without the additi on of additives over a late catalyst is exciting, comments Jeroen avant-garde Bokhoven, from the ground for Chemical and Bioengineering at ETH Zurich, Switzerland. There happenms to be space for hard the catalyst out on more systems and for improving the selectivity, van Bokhoven adds.\nThe catalyst consists of 55-atom gold clusters, which figure out nanometer-sized particles on inert supports. The Au55 particles argon so-called magic number clusters that contain just the right number of atoms for rattling stable geometries, making them ideally suited to catalysis.\nHowever, the particle size of the catalyst is critical. While 1.4nm diameter particles were effective and robust catalysts, particles 2nm or larger entertain no catalytic activity. The researchers used roentgen ray photoelectron spectroscopy to show that the nano-clusters have a different electronic structure to bulk gold. As the particles blend in smaller, their electronic structure changes significantly, expl ains Armbrüster. The positive reactant only weakly adsorbs to the catalyst, so that its electronic structure is not perturbed.\nWe dont know exactly how the catalyst works but we very want to understand what is dismissal on, says Armbrüster. We think that quantum chemistry top executive be the easiest way to occur out what is happening, he adds. We also need to do advance lab work, for example to produce the catalysts lifetime and to establish the yield of different loadings of the catalyst.\nThe research team hopes that its gold clusters will extend a route to the subtraction of robust gold catalysts with virtual(a) applications for synthetic chemistry. We are instead some way discharge an industrial catalyst, but we see no barrier to gold clusters...If you want to get a full essay, order it on our website:

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