Catalysts containing platinum

Ghaffai, T, and Parkins, A.W. (1995) A new homogeneous platinum containing catalyst for the hydrolysis of nitriles. Tetrahedron Lett., 36, 8657-8660. 

The dehydrocyclization of alkylaromatics was first described more than four decades ago. In 1936 Moldavskii and Kamusher reported the formation of naphthalene from u-butylbenzene on chromia at 475°C (7, 2). In 1945 Herington and Rideal reported the formation of indene from w-propyl-benzene over chromia-alumina (3). Platinum-containing catalysts were first used for these reactions in 1956 by Kazanskii and co-workers 4-6). 

Cyclization of alkylbenzenes is much slower over silica-alumina than over the platinum-containing catalysts. To clarify the successive steps of cyclization, Csicsery performed a set of experiments with 4-phenyl-1-butene, a dehydrogenation product of -butylbenzene (28). 

Platforming a reforming process using a platinum-containing catalyst on an alumina base. 

The first step requires a platinum containing catalyst. 

In naphtha reforming, hydrotreatment is always applied to protect the platinum-containing catalyst against sulphur poisoning. The specification of sulphur content for the feed for the reforming unit is less than 1 ppm. 

All sol-gel derived catalysts were stable under reaction conditions, except the rhodium and iridium catalysts, whose colour changed significantly during reaction. The catalysts could easily be separated from the reaction mixture by simple filtration. The filtrated liquid product, that flew out colourless, exhibited no further catalytic activity. GC analysis of the liquid phase indicated the production of dmf with 100% selectivity in all cases, except for the platinum containing catalyst (Table 1). 

The commercial processes available for use can be broadly classified as the moving-bed, fluid-bed, and fixed-bed types. The fluid- and moving-bed processes use mixed nonprecious metal oxide catalysts in units equipped with separate regeneration facilities. Fixed-bed processes use predominantly platinum-containing catalysts in units equipped for cycle, occasional, or no regeneration. 

M. Yu. Gol tsev, Complex Organosilicon Platinum-Containing Catalyst for Fast-Curing Compositions, Author s abstract of his Thesis, Moscow (2001). 

G. Lietz, J, Voeltcr, M. Dobrovolszky and Z. Paal, Initial changes of the catalytic properties of platinum containing catalysts. I. Transfonnations of mono- a bimetalic platinutn/ umina ca ysts by carbonaceous deposits, Appl. Caial. 13(1) (1984) 77-87. 

About 50% NO c conversion is obtained both with a platinum-based catalyst at temperatures below about 570 K, and with a copper-based catalyst at temperatures above about 570 K. These temperatures coincide with the temperature range in which these two catalysts convert hydrocarbons. However, whereas the platinum-containing catalyst is able to convert carbon monoxide efficiently, the copper-containing catalyst generates carbon monoxide, probably by the incomplete oxidation of the added hydrocarbons [71]. 

The best catalytic system for oxidation of sorbose in terms of activity and selectivity were platinum containing catalysts, e.g. 1TPS-Pt2. For this catalyst a long induction period was noted (Figure 6). 

E.E.Davies, J.S.Elkins, R.C.Pitkethly, Improvements relating to platinum-containing catalysts and their use, GB Patent No 1332361 (1973). V.K.Dyplyakin, V.P.Doronin, T.V.Tsymbal, L.Ya.Alt, A.S.Belyi, Dokl. Akad. Nauk SSSR, 281 (1985) 89 (in Russian). 

Platinum catalysts are superior for hydrocarbon oxidation [350]. Platinum is usually present as metaDic platinum at temperatures exceeding 400 °C [351]. Besides alumina, zirconia, molecular sieves and metal oxides are applied as supports, amongst others. However, an inhibition effect of oxygen was observed over platinum/alumina for light hydrocarbons [350,352] and other platinum-containing catalysts for methane [353] and propane oxidation [354]. This effect becomes problematic, in particular because full hydrocarbon conversion is usually required for a catalytic burner. The temperature control of catalytic burners also becomes difficult, because this is frequently carried out by regulation of the air feed flow rate to suprastoichiometric values. 

A.K. (2001) Hydroconversion of cyclohexene using platinum-containing catalysts promoted with other noble metals and chlorine or fluorine. Appl. Catal A- Gem, 208 (1-2), 55-61. 

Toward the end of the twentieth century, research workers were attracted by a new type of electrode consisting of a film of conducting polymer (such as polyaniline) into which a metal catalyst is inserted by chemical or electrochemical deposition. The specific catalytic activity (per unit of working surface area) exhibited by platinum crystallites in polyaniline toward methanol oxidation was higher than that of ordinary disperse platinum (Mikhailova et al., 2001). This may be due both to special structural features of platinum crystallites formed in the polymer matrix and to their placement in a three-dimensional matrix, facilitating reactant access. The activity of the catalyst in polyaniline strongly depends on the deposition conditions. A similar situation is found for platinum crystallites incorporated into fihns of poly(vinylpyridine) (Maksimov et al., 1998). It was pointed out by Nappom et al. (1996) that the properties of platinum-containing catalysts dispersed within a polymer matrix decisively depend on their method of preparation. 

Platinum-containing catalyst for ammonia synthesis. (Chevron Research Co.). US 3653831 (1972). 

Problon 5-4 (Level 1) The oxidation ofcaibon monoxide on a heterogeneous, platinum-containing catalyst is believed to proceed according to the sequence of elementary reactions... 

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