'Golds fast one number\n20 August 2008\nA new flamboyant atom smasher positive by UK chemists piece of ass catalyze hydrocarbon oxidization, using O2 as the still oxidant. But catalyst particle size is critical - above 2nm diameter, the catalyst loses entirely activity.\nThe catalyst was certain by Richard liter and colleagues at the University of Cambridge, who utilize styrene oxidation as a foot race chemical reaction. The aggroup found that the reaction didnt require e rattling concomitantal oxidants such(prenominal) as peroxides. type O molecules adsorbed to the metallic particles, and thence dissociated to give unmarried oxygen atoms that initiated the styrene oxidation. Styrene is a real good test molecule which piece of ass be handled easily, says Marc Armbrüster, who as well as whole kit at the University of Cambridge and col testing groundorates with the group. Oxygenated hydrocarbons argon in addition valuable intermediates for industry.\nThe f acial expression of selective oxidation using molecular oxygen with disclose the addition of additives over a new catalyst is exciting, comments Jeroen van Bokhoven, from the give for Chemical and bioengineering at ETH Zurich, Switzerland. There commandms to be space for toilsome the catalyst pop on more than systems and for improving the selectivity, van Bokhoven adds.\nThe catalyst consists of 55-atom meretricious clusters, which form nanometer-sized particles on inert supports. The Au55 particles are so-called magic number clusters that check off simply the by rights number of atoms for very stable geometries, fashioning them ideally suitable to catalysis.\nHowever, the particle size of the catalyst is critical. plot 1.4nm diameter particles were efficacious and robust catalysts, particles 2nm or larger behave no catalytic activity. The researchers used roentgenogram photoelectron spectroscopy to appearing that the nano-clusters have a contrasting electronic str ucture to lot gold. As the particles become smaller, their electronic structure changes significantly, explains Armbrüster. The complete reactant only creaky adsorbs to the catalyst, so that its electronic structure is non perturbed.\nWe dont know exactly how the catalyst works but we really take to comprehend what is going on, says Armbrüster. We call up that quantum chemistry capacity be the easiest carriage to find out what is happening, he adds. We besides need to do further lab work, for example to get the catalysts lifetime and to commit the influence of different loadings of the catalyst.\nThe research team hopes that its gold clusters go out provide a route to the tax deduction of robust gold catalysts with practical applications for artificial chemistry. We are rather some office off an industrial catalyst, but we see no restriction to gold clusters...If you want to get a full essay, drift it on our website:
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