Platinum-aluminum oxide catalyst

The reaction is carried out by thermal decomposition of fluoroformates at temperatures in the range of 300-500 C in the presence of a catalyst. Suitable catalysts are platinum gauze,136,137 140, y-aluminum oxide, or platinum group metal impregnated alumina, where platinum shows the best results.141,142 Moreover iron, steel or oxides and halides of chromium. 

HIE) Liao, P. C., Wolf, E. E. Self-Sustained Oscillations During Carbon Monoxide Oxidation 1982 on a Platinum/y-Aluminum Oxide Catalyst. Chem. Eng. Commun. 13(4-6), 315-326... 

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. 

Starting with a ceramic and depositing an aluminum oxide coating. The aluminum oxide makes the ceramic, which is fairly smooth, have a number of bumps. On those bumps a noble metal catalyst, such as platinum, palladium, or rubidium, is deposited. The active site, wherever the noble metal is deposited, is where the conversion will actually take place. An alternate to the ceramic substrate is a metallic substrate. In this process, the aluminum oxide is deposited on the metallic substrate to give the wavy contour. The precious metal is then deposited onto the aluminum oxide. Both forms of catalyst are called monoliths. 

The catalytic system used in the Pacol process is either platinum or platinum/ rhenium-doped aluminum oxide which is partially poisoned with tin or sulfur and alkalinized with an alkali base. The latter modification of the catalyst system hinders the formation of large quantities of diolefins and aromatics. The activities of the UOP in the area of catalyst development led to the documentation of 29 patents between 1970 and 1987 (Table 6). Contact DeH-5, used between 1970 and 1982, already produced good results. The reaction product consisted of about 90% /z-monoolefins. On account of the not inconsiderable content of byproducts (4% diolefins and 3% aromatics) and the relatively short lifetime, the economics of the contact had to be improved. Each diolefin molecule binds in the alkylation two benzene molecules to form di-phenylalkanes or rearranges with the benzene to indane and tetralin derivatives the aromatics, formed during the dehydrogenation, also rearrange to form undesirable byproducts. 

The importance of catalysts in chemical reactions cannot be overestimated. In the destruction of ozone previously mentioned, chlorine serves as a catalyst. Because of its detrimental effect to the environment, CFCs and other chlorine compounds have been banned internationally. Nearly every industrial chemical process is associated with numerous catalysts. These catalysts make the reactions commercially feasible, and chemists are continually searching for new catalysts. Some examples of important catalysts include iron, potassium oxide, and aluminum oxide in the Haber process to manufacture ammonia platinum and rhodium in the Ostwald synthesis of nitric... 

The redistribution reaction in lead compounds is straightforward and there are no appreciable side reactions. It is normally carried out commercially in the liquid phase at substantially room temperature. However, a catalyst is required to effect the reaction with lead compounds. A number of catalysts have been patented, but the exact procedure as practiced commercially has never been revealed. Among the effective catalysts are activated alumina and other activated metal oxides, triethyllead chloride, triethyllead iodide, phosphorus trichloride, arsenic trichloride, bismuth trichloride, iron(III)chloride, zirconium(IV)-chloride, tin(IV)chloride, zinc chloride, zinc fluoride, mercury(II)chloride, boron trifluoride, aluminum chloride, aluminum bromide, dimethyl-aluminum chloride, and platinum(IV)chloride 43,70-72,79,80,97,117, 131,31s) A separate catalyst compound is not required for the exchange between R.jPb and R3PbX compounds however, this type of uncatalyzed exchange is rather slow. Again, the products are practically a random mixture. 

Olefinic alcohols react smoothly with hydrogen over platinum oxide catalyst at room temperature. The procedure is illustrated by the preparation of dihydrocholesterol from cholesterol. Cinnamyl alcohol. CjH5CH = CHCH20H, is reduced to dihydrocinnamyl alcohol by lithium aluminum hydride. The reduction of allyl alcohol to n-propyl alcohol by the reagent, however, is unsatisfactory, ... 

Olefinic acids have been reduced to saturated acids in excellent yields by a variety of methods. Catalytic hydrogenation at room temperature over platinum oxide catalyst is described for 4-phenyl-3-pentenoic acid (98%). Behenic and undecanoic acids are prepared from the naturally occurring erucic and undecylenic acids with this catalyst. New and "aged platinum oxide catalysts have been compared, Reduction by nickel-aluminum alloy has been preferred to catalytic hydrogenation over platinum catalyst in the preparation of y-isopropylvaleric acid. ... 

Unsymmetrical secondary amines are readily prepared in good yields by the catalytic reduction of Schiff bases at moderate temperatures in high-or low-pressure equipment. Many examples have been cited. The intermediate imines are prepared from primary amines and aldehydes—very seldom from ketones—and may be used without isolation (cf. method 431). For the preparation of aliphatic amines, e.g., ethyl-w-propylamine and n-butylisoamylamine, a prereduced platinum oxide catalyst is preferred with alcohol as the solvent. Schiff bases from the condensation of aromatic aldehydes with either aromatic or aliphatic amines are more readily prepared and are reduced over a nickel catalyst. In this manner, a large number of N-alkylbenzylamines having halo, hydroxyl, or methoxyl groups on the nucleus have been made. Reductions by means of sodium and alcohol and lithium aluminum hydride have also been described,... 

Under suitable conditions it is possible to isolate the A-substituted hydroxylamines that are formed as intermediates in the reduction of nitro compounds. For this purpose it is essential in the reduction of aromatic nitro compounds to work with neutral or nearly neutral solutions suitable reducing agents are hydrogen and platinum oxide catalysts in glacial acetic acid,82,83 zinc dust in ammonium chloride solution,84 aluminum amalgam,85 and ammonium sulfide.86 Aliphatic nitro compounds may be reduced as their alkali salts (nitronates) by diborane in tetrahydrofuran, then giving A-alkylhydroxyl-amines 87 for instance, A-cyclohexylhydroxylamine is thus obtained from nitrocyclohexane in 53% yield. However, aliphatic nitro compounds are converted into A-alkylhydroxylamines more simply by catalytic hydrogenation in the presence of palladium-barium sulfate unlike aromatic nitro compounds, aliphatic nitro compounds require an acid medium for reduction to hydroxylamines an oxalic acid medium has proved the most suitable. 

Dehydration of cyclopentanemethanol over aluminum oxide at 320° tgave an olefin mixture whence hydrogenation afforded a mixture (94%) of [14C]methylcyclopentane with about 34% of [14C]cyclohexane. The mixed cycloalkanes were transformed into [14C]cyclo-hexane by Nenitzescu and Cantuniari s method,154 and dehydrogenation on a platinum-charcoal catalyst at 360° then yielded [14C1]benzene. 

The work presented in this paper is the first part of a project aiming at the development of tailor-made oxidation catalysts for diesel engines fuelled by alcohol fuels, ethanol or methanol. The investigation is focused on the influence of support material on the low temperature oxidation of ethanol and acetaldehyde. The study presents results from an experimental investigation with precious metal catalysts applied on monolithic cordierite substrates. Platinum or palladium were applied onto a support consisting of either aluminum oxide, cerium dioxide, silicon dioxide or titanium dioxide. 

In the presence of a platinum oxide catalyst tomatidine absorbs one mole of hydrogen in this reaction a cyclic ether is split. The same hydrogenolysis can be achieved with lithium aluminum hydride whereby... 

The studies of platinum supported aluminum oxide modified with optically active alkaloids of the cinchona group are considered in Chapter 5, where more than 200 communications on this topic are summarized. The studies of Pt-alumina catalysts modified with cinchonidine allowed for the preparation of a number of very important chiral synthons and medicines. These publications give substantial information for better understanding of the mechanism of heterogeneous catalysts and of the stmcture of intermediate complexes in enantioselective hydrogenation reactions. 

Because the accelerating effect of the solid catalyst comes from the surface atoms, it is desirable to have the largest surface possible, meaning a high degree of dispersion of the substance in question. In most cases, very small particles of catalytically active material such as platinum or rhodium are applied for stability to highly porous carrier materials with specific surfaces of several hundred square meters per gram. Aluminum oxide, silicon dioxide, activated carbon, as well as zeolites (crystalline aluminosilicates with numerous submicroscopic pores and canals) are all suitable for this purpose. Examples of such supported catalysts are... 

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