We find that nearly monodisperse copper oxide nanoparticles prepared via the thermal decomposition of a Cu(I) precursor exhibit exceptional activity toward CO oxidation in CO/O 2 /N 2 mixtures. Greater than 99.5% conversion of CO to CO 2 could be achieved at temperatures less than 250°C for over 12 h. In addition, the phase diagram and pathway for CO oxidation on Cu 2 O (100) is computed by ab initio methods and found to be in qualitative agreement with the experimental findings.Nanoparticles offer a larger surface-to-volume ratio and a higher concentration of partially coordinated surface sites than the corresponding bulk materials. The unique properties of nanoparticles are due to a strong interplay between elastic, geometric, and electronic parameters, as well as the effects of interactions with the support. The result of these features is often improved physical and chemical properties compared to the bulk material. It is for these reasons that heterogeneous catalysis at nanoparticle surfaces is currently under intense investigation in the catalysis community at large. 1,2 Conventional supported catalysts are generally produced by impregnation of a support medium with the desired metal ions followed by thermal treatments that result in small and dispersed active catalytic sites. 3,4 Many traditional catalysts based on the impregnation method 5,6 rely on the noble metals, in particular platinum, as the source for high activity. Such metals are recognized as a scarce resource as well as a limiting step in the development of viable energy alternatives to petroleum. Automotive exhaust catalysts (the three way catalyst) and fuel cells are examples of this tenet. 5,6 Any new system that overcomes these limitations will be invaluable.There are several important processes in heterogeneous catalysis where removal of carbon monoxide is either desired or absolutely necessary, such as in the postprocessing of Syngas 7 to produce hydrogen as an energy source for use in fuel cells. 8,9 A byproduct of this reaction is CO; however, trace amounts of CO (>10 ppm) can poison a fuel cell electrode, drastically reducing its efficiency. [10][11][12] The CuCu 2 O-CuO system has been known to facilitate oxidation reactions in the bulk, suggesting it has potential as a costeffective substitute for noble metals in various catalytic systems. [13][14][15] Here we describe a cheap, effective method of using copper oxide nanoparticles loaded onto silica gel as an exceptional catalyst toward CO oxidation at relatively low temperatures. Over sustained periods of time, conversions of 99.5% of CO to CO 2 are routinely observed and the catalyst structure is retained during the reaction. For example, during a 50 h period with the same ∼10 mg sample of copper oxide nanoparticles, over 30 L of CO is converted to CO 2 with an average conversion of 98 ( 1%.With recent developments in nanoparticle synthesis leading to the ability to control size, reproducibility, and structural complexity, it becomes urgent to define specific target structu...

Fe, Co and Ni particles were prepared in water/polyoxyethylene-4-laurylether/n-hexane and water/polyoxyethylene-4-laurylether/decahydronaphthalene microemulsions by reduction of metal nitrates dissolved in the water pools of the reversed micelles. The particles were mostly monodispersed with average diameters in the range 8 to 23 nm, as determined by dynamic light scattering (DLS). However, significantly smaller size estimates were obtained using transmission electron microscopy (TEM). The average DLS particle diameters increased with increased average diameter of the reversed micelles, and the diameter of the reversed micelles increased with an increase in the microemulsion water: surfactant ratio and metal ion concentration. The diameter of the reversed micelles was also dependent upon the metal dissolved in the water pool, increasing in the order Ni < Co < Fe. These trends are explained in terms of changes that occur to the microemulsion hydrophilic-lipophilic balance. Preparation of nickel and cobalt sulfides by sulfidation of the metal salt with H,S at low temperature, yielded much larger diameter particles (average diameter 75 nm). Measurement of the activity of the sulfided catalysts showed that the Co catalyst was more active than the Ni catalyst for the hydrocracking of diphenylmethane, and Co was more effective than Fe in reducing coke yield during Cold Lake residue hydroprocessing.Des particules de Fe, Co et Ni ont ete preparees dans des microemulsions d'eadpolyoxyethylene-4-lauryletherlnhexane et d'eadpolyoxyethylene-4-laurylCther/decahydronaphthalene par reduction de nitrates metalliques dissous dans les poches d'eau des micelles inverses. Les particules etaient principalement monodisperses avec des diametres moyens compris entre 8 et 23 mm, tels qu'ils ont ete determines par diffusion de lumiere dynamique (DLS). Cependant, des estimations de tailles beaucoup plus petites ont ete obtenues au moyen de la microscopie electronique par transmission (TEM). Les diametres de particules DLS moyens augmentent avec le diametre moyen des micelles inverses, et le diametre des micelles inverses augmente avec le rapport eadsurfactant de la microemulsion et de la concentration en ions metalliques. De meme, le diametre des micelles inverses est dependant du metal dissous dans la poche d'eau, augmentant dans I'ordre Ni < Co < Fe. On explique ces tendances par le changement dans I'equilibre hydrophiliquelipophilique de la microemulsion. La preparation de sulfures de nickel et de cobalt par sulfuration du sel metallique avec du H,S a faible temperature, donne des particules aux diametres beaucoup plus larges (diametre moyen de 75 nm). La mesure de I'activite des catalyseurs sulfures montre que le catalyseur de Co est plus actif que le catalyseur de Ni pour I'hydrocraquage du diphenylmethane, et le Co est plus efficace que le Fe pour reduire le rendement en coke lors de I'hydrotraitement des residus de Cold Lake.

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