Platinum/palladium catalyst

In 2000, the aniline production in the United States was about 1.9 billion lb. Almost 98 percent of nitrobenzene is used for the production of aniline. Consequently many nitrobenzene plants are integrated with facilities for aniline production. The hydrogenation of nitrobenzene can be done in either the vapor over a copper-silica catalyst or in liquid phase over platinum-palladium catalyst. One of the smaller uses for nitrobenzene is the production of the pain reliever, acetaminophen. 

Hydrogenation Fats and oils Propane, CO2 Supported platinum, palladium catalysts... 

Certain factors are analyzed to determine their effects on automotive catalyst activity. At operating gas velocities, spherical catalysts were more active than monolithic catalysts at comparable catalyst volumes and metals loadings. Palladium was the most active catalyst metal. Platinum in a mixed platinum palladium catalyst stabilizes against the effects of lead poisoning. An optimum activity particulate catalyst would contain about 0.05 wt % total metals on a gamma-alumina base with a platinum content of 0.03-0.04 wt % and a palladium content of 0.01-0.02 wt %. A somewhat thick shell of metals located near the outer surface of the particle provides better catalyst activity than a shell type distribution of metals. 

The effects of increasing VOC concentration has been considered by Tichenor and Palazzolo [5] for a bi-metallic platinum-palladium catalyst in the combustion of a mixture of hydrocarbons at total concentrations of 1,200 and 6,000 vppm. The higher concentration resulted in a higher destruction efficiency, a result which was more evident at lower temperatures (305°C) than at higher temperatures (400°C). However, this effect may well be due to the heat liberated during the reaction. As the reactor is essentially adiabatic, this would explain the higher conversions experienced for the higher VOC concentrations. 

Cordonna et al. made similar observations for the oxidation of a number of hydrocarbons over bi-metallic platinum-palladium catalysts. Catalytic activity was found to increase markedly with increased platinum content, the most active catalyst had a Pt/Pd ratio of 4/1, in accordance with previous work by Skoglundh [34]. 

Different catalysts are used for AFCs. For the hydrogen oxidation reaction, carbon-supported platinum and platinum-palladium catalysts (e.g., noble metal catalysts) are suitable. However, one of the advantages of the AFC compared with acid electrolyte fuel cells, including the phosphoric acid fuel cell (PAFC) and the... 

Other molecules present in the gas mixtures like alcohols or ketones may have a moderate effect on aromatic oxidation but the reverse (inhibition of alcohol oxidation by aromatics) is most often observed. Different supports of Pt were used for toluene oxidation Al203, Al203/Al, Zn0/Al203, Ti02, mesoporous fibrous silica or monoliths. Zeolites, generally promoted by platinum, were shown to give excellent catalysts for aromatic oxidation. Basic zeolites showed excellent performances in oxidation of m-xylene even in the absence of platinum. Palladium catalysts, either supported on alumina or ceria-alumina, were also investigated for oxidation of benzene and several alkylbenzenes. ... 

A suspension of palladized charcoal in a freshly prepared soln. of dry HCl in acetic acid equilibrated with Hg, a soln. of ethyl a-(N-acetylphenylhydra-zono)-/ -oxobutyrate in acetic acid added, and hydrogenated 1 hr. ethyl a-amino-/ -oxobutyrate hydrochloride (Y 83%) and acetanilide (Y 94%).— With a platinum-palladium catalyst, also reduction of the keto to a sec. alcohol group occurs. W. G. Laver, A. Neuberger, and J. J. Scott, Soc. 1959, 1474. 

In 1989,1 billion lb of aniline was produced in the United States. The most common route involves the hydrogenation of nitrobenzene in either the liquid or the vapor phase, over a copper-silica, nickel, or platinum-palladium catalyst. A typical aniline plant is illustrated in Fig. 22.43. 

Vielstich [224] proposed a platinum - palladium catalyst for oxidation of methanol - formate mixture in alkaline solutions, and this has found practical application. 

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