Copper oxide surfaces

Poulston, S., Rowbotham, E., Stone, P., Parlett, P. and Bowker, M. (1998) Temperature-programmed desorption studies of methanol and formic add decomposition on copper oxide surfaces. Catal. Lett., 52, 63-67. 

Implications for the Copper-Catalyzed Oxidation of Polyolefins. Correlation of Contributing Mechanisms. The susceptibility of a polyolefin/copper composite to enhanced oxidation rates will depend critically on the rate of dissolution of copper ions from the copper (oxide) surface and the subsequent rates at which catalytically active concentrations of copper ions can be established within significantly large regions of the polymer matrix. Dissolution of copper with formation of interfacial salt layers appears to occur at very early times (4) (during the induction period) and can be described by overall reactions such as Equation 7 ... 

The use of an intennediate barrier layer to vary the penetration depth in an ATR experiment was used in probing concentration profiles away from the interface. Application of this technique in the study of PMMA/ PDMS graft copolymers deposited onto a copper oxide surface indicated a preferential presence of the siloxane component at the oxide interface a concentration gradient was observed to decrease with increasing distance into the bulk of the sample film (275). 

There has been only one report describing SI-NMP from a metal oxide other than those of titanium and iron, namely from a copper oxide surface [44]. In this study, poly(ionic liquid) was grafted onto micro/nanoscale CuO/Cu surfaces by bimolecular-initiated polymerization with TEMPO nitroxide. For this purpose, the peroxide groups were first introduced onto micro/nanoscale CuO surfaces by reaction of 3-chloropropyltrimethoxysilane (immobilized on the CuO surface) with... 

Hoque, E., DeRose, J. A., Houriet, R., Hoffmann P. Mathieu, H. J. (2007). Stable Perfluorosilane Self-Assembled Monolayers on Copper Oxide Surfaces Evidence of Siloxy-Copper Bond Formation. Chemistry of Materials, 19, 798-804. 

One other very important attribute of photoemitted electrons is the dependence of their kinetic energy on chemical environment of the atom from which they originate. This feature of the photoemission process is called the chemical shift of and is the basis for chemical information about the sample. In fact, this feature of the xps experiment, first observed by Siegbahn in 1958 for a copper oxide ovedayer on a copper surface, led to his original nomenclature for this technique of electron spectroscopy for chemical analysis or esca. 

Oxidation. Carbon monoxide can be oxidized without a catalyst or at a controlled rate with a catalyst (eq. 4) (26). Carbon monoxide oxidation proceeds explosively if the gases are mixed stoichiometticaHy and then ignited. Surface burning will continue at temperatures above 1173 K, but the reaction is slow below 923 K without a catalyst. HopcaUte, a mixture of manganese and copper oxides, catalyzes carbon monoxide oxidation at room temperature it was used in gas masks during World War I to destroy low levels of carbon monoxide. Catalysts prepared from platinum and palladium are particularly effective for carbon monoxide oxidation at 323 K and at space velocities of 50 to 10, 000 h . Such catalysts are used in catalytic converters on automobiles (27) (see Exhaust CONTHOL, automotive). 

A routine inspection of the tube bundle during a plant outage revealed fine cracks of the type shown in Fig. 9.11. Scattered longitudinal cracks were observed along the lengths of most tubes. The external surface was covered with a thin film of black copper oxide and deposits. The bundle had been exposed to ammonia levels that produced 14 ppm of ammonia in the accumulated condensate. 

Close examination revealed that the cracks originate on the external surface. Exposure of the fracture surface revealed a rough contour covered with dark copper oxide. Close examination of the internal surface revealed fewer, tighter fissures corresponding to the locations of cracks on the external surface. 

The second category was concerned with adhesion to porous or microfibrous surfaces on metals. Aluminium may be anodised to form an oxide surface comprising pores of diameter of tens of nanometers. Electroforming and chemical oxidation can be used to produce microfibrous or needle-like coatings on metals, including copper, steel and titanium. The substrate topography was demonstrated to play an vital part in adhesion to these surfaces [45-48]. 

The concentration dependence of CO oxidation over Pt at (02) (CO) l differs from the concentration dependence of CO oxidation over copper chromite at (02)°-2(C0). This can be explained by the fact that after the departure of a C02 molecule, the reoxidation of platinum surfaces is slow but the reoxidation of base metal oxide surfaces is fast. On the other hand,... 

There is little data available to quantify these factors. The loss of catalyst surface area with high temperatures is well-known (136). One hundred hours of dry heat at 900°C are usually sufficient to reduce alumina surface area from 120 to 40 m2/g. Platinum crystallites can grow from 30 A to 600 A in diameter, and metal surface area declines from 20 m2/g to 1 m2/g. Crystal growth and microstructure changes are thermodynamically favored (137). Alumina can react with copper oxide and nickel oxide to form aluminates, with great loss of surface area and catalytic activity. The loss of metals by carbonyl formation and the loss of ruthenium by oxide formation have been mentioned before. 

Copper oxide, oxidation of CO over, 86 Coupled heterogeneous catalytic reactions, kinetics of, 1-49, see also Kinetics coupling through catalytic surface, 9-13 experimental studies, 22-49 apparatus and procedure, 25, 26 catalysts, 26-28... 

In addition, the development of porous deposits on boiler surfaces often is enhanced by the presence of small amounts of iron or copper oxides (usually originating from contaminated condensate). This increased rate of deposition may then lead to even more serious problems of overheating. 

Spectroscopic studies (XPS and HREELS) established first in 1980 that the activity of oxygen states in the oxidation of ammonia at copper-O surfaces was... 

The oxidative dehydrogenation of ethanolamine to sodium glycinate in 6.2 M NaOH was investigated using unpromoted and chromia promoted skeletal copper catalysts at 433 K and 0.9 MPa. The reaction was first order in ethanolamine concentration and was independent of caustic concentration, stirrer speed and particle size. Unpromoted skeletal copper lost surface area and activity with repeated cycles but a small amount of chromia (ca. 0.4 wt%) resulted in enhanced activity and stability. 

Copper metal surface area was determined by nitrous oxide decomposition. A sample of catalyst (0.2 g) was reduced by heating to 563 K under a flow of 10 % H2/N2 (50 cm min"1) at a heating rate of 3 deg.min 1. The catalyst was then held at this temperature for 1 h before the gas flow was switched to helium. After 0.5 h the catalyst was cooled in to 333 K and a flow of 5 %N20/He (50 cm3mirr ) passed over the sample for 0.25 h to surface oxidise the copper. At the end of this period the flow was switched to 10 % H2/N2 (50 entitlin 1) and the sample heated at a heating rate of 3 deg.min"1. The hydrogen up-take was quantified, from this a... 

FIGURE 40 Patina. Patina is a colored (usually green) layer of corrosion products that frequently develops naturally on the surface of copper and copper alloys exposed to the environment. Since it is sometimes appreciated aesthetically and as a proof of age, patina is also developed artificially, by chemical means, as a simulated product of aging. Copper patina generally includes such compounds as copper oxides, carbonates, and chlorides. In bronze and brass patinas, these compounds are mixed with the oxides of tin and lead resulting from the corrosion of the other components of the alloys. In any particular patina there may be many layers, not necessarily in the order shown in the illustration. 

As the assemblage is further heated and reaches a temperature of about 850°C, the carbon reacts with copper oxide on the surface of the alloy, reducing the copper to metallic copper, while the carbon is oxidized to carbon monoxide (it should be noted that practically all exposed copper surfaces acquire a thin layer of copper oxide formed by the oxidation of the metal when exposed to oxygen in the atmosphere) ... 

Park PW, Ledford JS (1998) The influence of surface structure on the catalytic activity of cerium promoted copper oxide catalysts on alumina oxidation of carbon monoxide and methane. Catal Lett 50(1—2) 41 48... 

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