Supported Copper Oxide

Copper-oxide supported on Ti02 nanotubes was also investigated for selective NO reduction with The nanotubes were found to be more... 

Figure 2.14 DR UV-Vis spectra of copper oxide supported or not on AI2O3 in the fresh state (a) bulk copper oxide diluted into AI2O3 (b) 2.1 wt% CUO/AI2O3 (c) 4.8wt% CuO/AljOj (d) 9.2 wt% CUO/AI2O3. Reprinted from ref. [116], with permission from the Royal Society of Chemistry.

M C Manon, E Garbowski, and M Pnmet, Catalytic properties of copper oxide supported on zinc aluminate in methane combustion, J Chem Soc. Faraday Trans 87 1795 (1991)... 

When comparing the TPR profiles with the light-off curves from the ethanol oxidation experiments, we have foimd an indication of a correlation between activity and reducibility of the catalyst. Copper oxide supported on titania is the most active towards ethanol oxidation among the copper oxides tested. It is also the catalyst in which the reduction starts at the lowest temperature. The results obtained in the TPR experiments strengthen the hypothesis that there is a considerable interaction between the support and the active material. 

Taking as a reference the activity of the catalyst of copper oxide supported on sepiolite washed with an acid solution, SLCu, the influence of the introduction of a second metal, Co or Ni, maintaining the Cu M ratio at 9 1 wt% was studied. 

Fig. 29. Susceptibility isotherms for copper oxide supported on alumina.

This reaction equilibrium is favored at low temperatures, and most of the carbon monoxide is converted to carbon dioxide in a high-temperature shift furnace (HTS) operating at 350 to 450°C. This step is followed by low-temperature conversion of the remaining carbon monoxide to carbon dioxide in a low-temperature shift converter (LTS) after cooling. The usual catalyst for the low-temperature shift converter is copper oxide supported on zinc oxide and alumina. 

Guilhaume, N. and Primet, M. Catalytic combustion of methane—Copper oxide supported on high specific area spinels synthesized by a sol-gel process. J. Chem. Soc., Faraday Trans. 1 1994, 90, 1541-1545. 

The effect of the aluminum oxide layer is also known to reduce the propagation of thermite reactions since alumina is an effective absorber of thermal energy. A study by Weismiller et al. of a 49 % active aluminum nanopowder in a thermite with copper oxide supports the idea that too much oxide can actually reduce thermite performance. Table 13.4 shows Weismiller s data which indicates the negative effect of a thick oxide layer on aluminum nanoparticles. 

Reduction. Acetaldehyde is readily reduced to ethanol (qv). Suitable catalysts for vapor-phase hydrogenation of acetaldehyde are supported nickel (42) and copper oxide (43). The kinetics of the hydrogenation of acetaldehyde over a commercial nickel catalyst have been studied (44). 

The predominant process for manufacture of aniline is the catalytic reduction of nitroben2ene [98-95-3] ixh. hydrogen. The reduction is carried out in the vapor phase (50—55) or Hquid phase (56—60). A fixed-bed reactor is commonly used for the vapor-phase process and the reactor is operated under pressure. A number of catalysts have been cited and include copper, copper on siHca, copper oxide, sulfides of nickel, molybdenum, tungsten, and palladium—vanadium on alumina or Htbium—aluminum spinels. Catalysts cited for the Hquid-phase processes include nickel, copper or cobalt supported on a suitable inert carrier, and palladium or platinum or their mixtures supported on carbon. 

The raw materials needed to supply about ten million new automobiles a year do not impose a difficult problem except in the case of the noble metals. Present technology indicates that each car may need up to ten pounds of pellets, two pounds of monoliths, or two pounds of metal alloys. The refractory oxide support materials are usually a mixture of silica, alumina, magnesia, lithium oxide, and zirconium oxide. Fifty thousand tons of such materials a year do not raise serious problems (47). The base metal oxides requirement per car may be 0.1 to 1 lb per car, or up to five thousand tons a year. The current U.S. annual consumption of copper, manganese, and chromium is above a million tons per year, and the consumption of nickel and tungsten above a hundred thousand tons per year. The only important metals used at the low rate of five thousand tons per year are cobalt, vanadium, and the rare earths. 

NOTE Denting is a phenomenon affecting tubes and tube supports. It is caused by the buildup of voluminous metallic oxides (such as copper oxide from FW heaters and iron oxide from carbon steel components), plus chloride ions. The deposit buildup distorts equipment and causes dents. 

A wide range of catalytic materials have been investigated for the selective catalytic reduction of NOx. For stationary emissions, NH3-SCR using vanadium-tungsten oxides supported on titania is the most used method however, when there is a simultaneous emission of NO and NOz (in tail gas from nitric acid plants), copper-based zeolites or analogous systems have been proven to be preferable [31b], In fact, there are two main reactions for NH3-SCR ... 

Other metal oxide catalysts studied for the SCR-NH3 reaction include iron, copper, chromium and manganese oxides supported on various oxides, introduced into zeolite cavities or added to pillared-type clays. Copper catalysts and copper-nickel catalysts, in particular, show some advantages when NO—N02 mixtures are present in the feed and S02 is absent [31b], such as in the case of nitric acid plant tail emissions. The mechanism of NO reduction over copper- and manganese-based catalysts is different from that over vanadia—titania based catalysts. Scheme 1.1 reports the proposed mechanism of SCR-NH3 over Cu-alumina catalysts [31b],... 

Palladium catalysts, 10 42 14 49 16 250 Palladium-catalyzed carbonylation, 13 656 Palladium chloride/copper chloride, supported catalyst, 5 329 Palladium compounds, 19 650-654 synthesis of, 19 652 uses for, 19 653-654 Palladium films, 19 654 Palladium membranes, 15 813 Palladium monoxide, 19 651 Palladium oxide, 19 601... 

Cu(NH3)2BTC2/3 and finally copper hydroxide in the presence of water. The formation of the BTC salts was supported by the collapse of the structure after interaction of ammonia with unsaturated copper centers. The release of BTC and copper oxide centers provides sites for reactive adsorption of ammonia during the course of the breakthrough experiments. Interestingly, even though the structure collapses, some evidence of the structural breathing of the resulting materials caused by reactions with ammonia was found, based on the ammonia adsorption at equilibrium and the analysis of the heat of interactions [51]. 

Immobilizing DENs within a sol-gel matrix is another potential method for preparing new supported catalysts. PAMAM and PPI dendrimers can be added to sol-gel preparations of silicas " and zinc arsenates to template mesopores. In one early report, the dendrimer bound Cu + ions were added to sol-gel silica and calcined to yield supported copper oxide nanoparticles. Sol-gel chemistry can also be used to prepare titania supported Pd, Au, and Pd-Au nanoparticle catalysts. Aqueous solutions of Pd and Au DENs were added to titanium isopropoxide to coprecipitate the DENs with Ti02. Activation at 500°C resulted in particles approximately 4 nm in diameter. In this preparation, the PAMAM dendrimers served two roles, templating both nanoparticles and the pores of the titania support. 

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