Platinum catalyst preparation

The results presented here correspond to a series of tin-modified platinum catalysts prepared by SOMC/M techniques, which have the characteristics shown in entries 1, 6, 7 and 13 in Table 6.4. Figure 6.10 shows the variation of crotonaldehyde conversion as a function of time for two successive reaction cycles. A characteristic of these catalytic systems is their stability-only a slight flattening is observed for the Pt/Si02 catalyst. The presence of tin seems to improve this stability. Completely reproducible behavior is observed for both cycles, which is an important result mainly for the PtSn-OM system, which contains butyl groups anchored to the surface. 

Table 3. Light-Induced Hydrogen Production by Platinum Catalysts Prepared in the Presence of Various Polymers...

Platinum catalyst preparation a mixture of 1 g of chloroplatinic acid hexahydrate, 12.4 mL (22 equiv) of 1,3-divinyltetramethyldisiloxane (an excess), and... 

The particle size effect in the case of supported platinum catalysts prepared from chloroplatinic acid was questioned by Dautzenberg and Platteeuw (131), who claimed that the difference of behavior between the 0.2% and the... 

This contribution describes some physical properties of reverse w/o microemulsions, physical-chemical properties of platinum catalysts prepared by classical impregnation from water solutions of HaPtCle and from reverse w/o microemulsions comprising chloroplatinic acid and their activity in combustion of volatile organic compounds (VOC). In our study we concentrated on TweenSO (polyoxlethylen(20)sorbitan monoleate), as the surfactant does not comprise any potentially harmful ions (like sodium in AOT or bromide in CTAB) that could affect the activity of platinum in catalytic combustion. 

We may start by considering the results obtained with platinum catalysts the reactions of the -butenes with hydrogen and or deuterium have been studied using Pt/AbOs, on catalysts prepared from reverse micelles (Section 2.32), and on platinum foil and various single crystal surfaces. There are a number of common features (i) orders of reaction, where measured, are either accurately or close to first in hydrogen and zero in the butene (ii) activation energies for the macroscopic forms are between 33 and 43 kJ moD for both 1-butene and Z-2-butene, but lower for the latter on Pt/AlaOs (21 kJ mol ) (iii) rates of reactant removal for each butene appear to be structure-insensitive and all three isomers react at about the same rate. A notable characteristic of platinum catalysts prepared conventionally or in macroscopic form is the slow rate of... 

Shelimov, B.N., Lambert, J.-F., Che, M., Didillon, B. (1999). Initial Steps of the Alumina-Supported Platinum Catalyst Preparation a Molecular Study by i spt NMR, UV-Visible, EXAFS and Raman Spectroscopy. Journal of Catalysis, Vol.185, No.2, (July 1999), pp. 462-478, ISSN 0021-9517... 

Job N, Pereira M F R, Lambert S et al (2006) Highly dispersed platinum catalysts prepared by impregnation of texture-tailored carbon xerogels. Journal of Catalysis 240 160-171... 

The present work was undertaken to examine this possibility by trying a new method of low-temperature catalyst preparation. The method studied involves the adsorption of metal precursors on supports and the reduction by sodium tetrahydroborate solution for the preparation of supported platinum catalysts. The adsorption and reduction of platinum precursors are carried out at room temperature and the highest temperature during the preparation is 390 K for the removal of solvent. The activities of the catalysts prepared were examined for liquid-phase hydrogenation of cinnamaldehyde under mild conditions. Our attention was directed to not only total activity but also selectivity to cinnamyl alcohol, since it is difficult for platinum to hydrogenate the C=0 bond of this a, -unsaturated aldehyde compared to the C=C bond [2]. We examined the dependence of the catalytic activity and selectivity on preparation variables including metal precursor species, support materials and reduction conditions. In addition, the prepared catalysts were characterized by several techniques to clarify their catalytic features. The activity of the alumina-supported platinum catalyst prepared by the present method was briefly reported in a recent communication [3]. 

The platinum catalyst prepared in this experiment may be pyrophoric and combust spontaneously in air. Do nof allow it to become dry ... 

Chen J, Wang M, Liu B et al (2006) Platinum catalysts prepared with functional carbon nanotube defects and its improved catalytic performance for methanol oxidation. J Phys Chem B 110 11775-11779... 

Adams platinum, obtained by reduction of platinum dioxide [203, 204], has been used in a number of papers [203, 204, 210] on electrochemical oxidation. In [203] a platinum catalyst, prepared by dejmsition and subsequent reduction of oxidized forms of platinum on a carbon substrate, was used. Adams platinum is an active form of the catalyst, which is stable towards heat treatment and the action of contaminants [208]. 

The authors are collaborating in an extensive joint study in which the preparation, characterisation and function of a range of supported platinum catalysts is being evaluated. In part, this study will compare platinum catalysts prepared using conventional supports (e.g. silica, alumina) with those using less conventional supports (e.g. molybdena) or those prepared by less conventional methods (e.g. metal vapour deposition). The restricted object of the present paper is to compare the conventional Pt/silica prepared within this programme with the standard reference silica-supported Pt codenamed EUROPT-1 for which full preparation and characterisation details have been published (refs. 1-5). 

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