Reactivity of Copper Nanopowders in a Model Reaction of Isopropylbenzene Oxidation

Abstract

The reactivity of copper nanopowders produced by an electric explosion of a conductor or mechanochemically was studied. Oxidation of isopropylbenzene was used as a model reaction. The dependence of the oxygen uptake rate on the specific surface area of a copper nanopowder and on the method used for its production is discussed. A possible mechanism of isopropylbenzene oxidation in the presence of copper nanopowders is suggested.The intermediate position occupied by nanoparticles in passing from a bulk metal to a separate atom predetermines the deviation of their physicochemical properties from those of bulk metals, on the one hand, and from the properties of isolated atoms, on the other. This deviation is manifested in electronic, magnetic, optical, and other properties of nanoparticles with a characteristic size of several tens of nanometers to several nanometers [1]. Numerous summarizing papers concerning methods for preparation and stabilization of nanoparticles and their optical and other properties have already appeared, whereas studies of chemical transformations involving nanoparticles are only in their initial stage [2].It is known [3] that nanosize powders (NPs) of metals show an increased reactivity, compared to compact metals. For example, reactions that do not occur in the presence of some metals or require severe conditions readily proceed in the presence of metal nanopowders. In particular, synthesis of complex compounds (phthalocyanines and tetraphenylporphyrins) with the use of copper and indium NP [4,5] is performed under milder conditions (room temperature and atmospheric pressure) than the conventional synthesis with metal salts. Use of metal NPs as catalysts for oxidation of organic compounds is known. It was shown in [6] that the uptake of oxygen in oxidation of isopropylbenzene (IPB) in the presence of NPs of copper and cobalt proceeds at a sufficiently high rate even at 30oC without any initiator.In this study we examined the reactivity of copper NP, obtained by an electric explosion of a conductor (EEC) or mechanochemically, in a model reaction of IPB oxidation. EXPERIMENTALAs objects of study served copper NP obtained by an electric explosion of a conductor in the atmosphere of nitrogen, argon, and xenon, as well as copper NP produced mechanochemically on an AGO-2 installation in the presence of organic and inorganic additives. 1 The additives were used to raise the specific surface area of the mechanochemically produced NP [7]. Copper nanopowders were produced by mechanical treatment (MT) in AGO-2 planetary-centrifugal high-energy-intensity mills in the presence of an organic surfactant (2,2,3,3,4,4,5,5-octafluorovaleramide) in an amount of 10% for 10 (Cu I), 20 (Cu II), and 30 min (Cu III). Copper powders were also prepared by mechanical treatment in the presence of 15 wt % CuCl 2 (CuCl 2 was washed out with ethanol after MT) on an AGO-2 installation for 10 (Cu 1), 20 (Cu 2), and 30 min (Cu 3). The physicochemical parameters and the preparation conditions of copper NPs used in this stu...

An Investigation of the Possibility of Using Nickel-Activated, Multilayer Carbon Nanotubes in Catalyst Development

“…The process of low-temperature oxidation of cumene was carried out in a bubbling glass reactor on a gasometric unit at a temperature of 60°C and atmospheric pressure [15].…”