Copper/Zirconia

The above example illustrates how important the knowledge of the solid-state reactions and segregational phenomena is for successful preparation of efficient catalysts from glassy precursors. The occurrence of the copper segregation upon hydrogen exposure at elevated temperature was found to be crucial for successful preparation of copper/zirconia catalysts from Cu-Zr precursors this segregation depends on various factors such as the structure of the precursor material, the oxygen content, and the chemical composition of the alloy. 

For illustration, we may consider the preparation of a palladium/zirconia catalyst highly active for the oxidation of CO [4.47,71], the preparation of a copper/zirconia catalyst for the hydrogenation of C02 [4.23], and the preparation of iron/zirconia for ammonia synthesis [4.44]. 

EFFECT OF PREPARATION VARIABLES ON CATALYTIC BEHAVIOUR OF COPPER/ZIRCONIA CATALYSTS FOR THE SYNTHESIS OF METHANOL FROM CARBON DIOXIDE... 

A series of copper-zirconia catalysts have been prepared by methods of sequential precipitation, coprecipitation and deposition precipitation. The influence of various pretreatments and of the copper zirconia ratio on the structural and chemical properties of these samples are examined. High activity and selectivity of the catalysts is shown to be correlated to the presence of amorphous zirconia which is stabilized by copper ions. The results indicate that the structural and chemical properties of the support and particularly the interface copper/zirconia are most decisive in governing the catalytic properties of these methanol synthesis catalysts. 

The crystallization of the amorphous zirconia is likely to result in a drastic decrease of the copper/zirconia interfacial area which certainly contributes to the loss of activity observed upon crystallization. Our investigations provide further support for the crucial role of the interfacial area in copper/zirconia catalysts. Further work focusing on the structural and chemical properties of this interphase and its role in methanol synthesis is presently undertaken. 

Properties of the deposits Almost any material which can be melted is suitable for plasma spraying, giving a vast range of possible coatings of single or mixed metallic or non-metallic substances. It is often possible to produce types of coatings which are not obtainable in any other way. Typical of the materials which are plasma sprayed are copper, nickel, tantalum, molybdenum. Stellites, alumina, zirconia, tungsten and boron carbides, and stainless steels. 

Centi, G., Cerrato, G., D Angelo, S. et al. (1996) Catalytic behavior and nature of active sites in copper-on-zirconia catalysts for the decomposition of N20, Catal. Today 27, 265. 

E. J. Walter, S. P. Lewis, and A. M. Rappe, Eirst-principles study of carbon monoxide adsorption on zirconia-supported copper. Surf. Sci. 495, 44-50 (2001). 

N. Kiratzis, P Holtappels, C. E. Hatchwell, M. Mogensen, and J. T. S. Irvine, Preparation and characterization of copper/yttria titania zirconia cermets for use as possible solid oxide fuel cell anodes, Fuel Cells 1,211-218 (2001). 

Although the decomposition of ozone to dioxygen is a thermodynamically favoured process,126 it is thermally stable up to 523 K and catalysts are needed to decompose it at ambient temperature in ventilation systems, in the presence of water vapour and at high space velocity. A limited number of catalysts have been evaluated and active components are mainly metals such as platinum, palladium and rhodium, and metal oxides including those of manganese, cobalt, copper, iron, nickel and silver. Supports that have been used include 7-alumina, silica, zirconia, titania and activated carbon.125,170... 

Raudaskoski R, et al. Catalytic activation of CO2 use of secondary CO2 for the production of synthesis gas and for methanol synthesis over copper-based zirconia-containing catalysts. Catal Today. 2009 144(3 4) 318-23. 

Probes for measuring oxygen potential in liquid copper have been successfully developed and used in laboratory scale Abraham, 1967). Many industrial copper smelting and refining units in Europe have been successfully using magnesia-stabilised zirconia probes using air as the reference electrode. 

The ultrafiltration zirconia membrane system described above removes about 92% of the total suspended solids (TSS), 47% of the total dissolved solids (TDS), 12% of chromium and 13% of copper. However, the membrane also rejects some alkaline salts (about 9%) and consequently make-up with fresh cleaner is required. 

Note 20 mg/1 of copper feirocyanide and 10 mg/1 of zirconia phosphate are added to the wastes [Gumming and Turner, 1988]... 

Blackwell and Carr investigated the ligand exchange chromatography of free amino acids on copper-loaded zirconia. It was shown that the use of Lewis base buffers in this system improved the operating efficiency. Acetate, sulfate, fluoride, and phosphate are the effective competing ions. 

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