Palladium alloys rhodium

In 1824 del Rio published an analysis of a gold-rhodium alloy from the smelting house in Mexico which was similar to the gold-palladium ingot previously reported by Joseph Cloud, director of the Philadelphia Mint (21). Three years later he published a translation of Berzelius s New mineral system (22). He served for some time on a committee appointed to inspect the money and improve working conditions at the Mint. 

When you see Dr. Wollaston give him a thousand compliments from me and then ask him if it would be possible to have a little malleable platinum, not separated from its natural alloy with palladium, rhodium, etc, to make a crucible. The crucibles I have bought recently from Cary are of a metal noticeably purer than those which I formerly had, and for that very reason infinitely more susceptible to attack by other substances (5). 

Platinum is one member of a family of six elements, called the platinum metals, which almost always occur together, Before the discovery of the sister elements, the term platinum was applied to an alloy with Pt as the dominant metal, a practice that persists to some degree even today. The major properties of the platinum metals are given in Table 1 See also Iridium Osmium Palladium Rhodium and Ruthenium. 

Some of the materials that have been examined as catalysts include Pure Platinum, Platinum-Iridium Alloys, Various Compositions of Platinum-Rhodium Alloys, Platinum-Palladium Alloys, Platinum-Ruthenium Alloys, Platinum-Rhenium Alloys, Platinum-Tungsten Alloys, FejOj-M CVI Oj (Braun Oxide), CoO-Bi20j, CoO with AI2O3, Thorium, Cerium, Zinc and Cadmium. 

It should also be emphasized the ecological aspects inherent to biofuel cells that contrarily to fuel cells, require no metal catalysts (platinum, nickel, palladium, rhodium, iridium, etc.). Indeed, materials, fuels, and products used in the design of all biofuel cells are biodegradable. Consequently, these biofuel cells are not subjected to major economic issues related to metal catalyst. Indeed, the increasing demand for strategic metals and metal alloys by high-tech industries, aerospace or automotive industry causes a process of depletion of these materials. 

Common palladium alloys include Pd-Ag with 1-60% Pd this material is tarnish resistant at greater than 50% Pd. The alloys are attacked by HNO3 and cyanide but are resistant to HCl except in the presence of oxidizing agents Pd-Ag-Cu, Pd-Ag-Au, and Pd-Au alloys also show good corrosion resistance and Pd-Cu, Pd-Ni, and Pd-Ru alloys are harder than palladium. Rhodium and ruthenium are often used together with palladium as with... 

Preferential oxidation catalysts usually consist of precious metals such as platinum, ruthenium, palladium, rhodium, gold and alloys of platinum with tin, ruthenium [164] or rhodium. Typical carrier materials are alumina and zeolites [164], such as zeolite A, mordenite and zeolite X. Other possible carriers are cobalt oxide, ceria, tin oxide, zirconia, titania and iron oxide [214]. A high precious metal loading usually improves catalyst performance [164]. 

The carrier is a monolith with a shape similar to a honeycomb. The mineral cordierite (Mg, Fe)2Al Si50jg is used as the carrier material. Because of its system of chaimels, the carrier has an active surface of 30 000 m. The channels of the monolith are covered by a wash-coat of y-Al Oj. An alternative wash-coat carrier is a special stainless steel with 5% A1 and micro-alloyed with yttrium and cerium. By a carefully controlled heat treatment in an oxidizing environment AljO, whiskers are formed. On the wash-coat a layer of platinum metals is applied, which is responsible for the catalytic function. Platinum with 20% rhodium dominated earlier but nowadays palladium-rich alloys or pure palladium are mainly used. In 2001, the automobile industry accounted for nearly 72% of the total palladium demand. 

One reason for recent increases in the prices of metals such as platinum, rhodium and palladium is that they are used in catalytic converters in vehicles and as catalysts in some industrial processes. For example, a platinum—rhodium alloy can be used in the Contact process (Chapter 7). 

The authors wish to acknowledge J E Wagner and T A Belter for work on the zirconium palladium and zirconium rhodium systems and R J Furlan for work on the titanium copper system In addition we wish to acknowledge A J Maeland for the titanium copper alloys and hydrides and to L Hazelton, K Samwer, W L Johnson and W Tadlock for the zirconium palladium and zirconium rhodium alloys and hydrides ... 

Alloys suitable for castings that ate to be bonded to porcelain must have expansion coefficients matching those of porcelain as well as soHdus temperatures above that at which the ceramic is fired. These ate composed of gold and palladium and small quantities of other constituents silver, calcium, iron, indium, tin, iridium, rhenium, and rhodium. The readily oxidi2able components increase the bond strength with the porcelain by chemical interaction of the oxidi2ed species with the oxide system of the enamel (see Dental materials). 

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