Carbon monoxide on platinum metals

H. P. Kaukonen, R. M. Nieminen. Computer simulations studies of the catalytic oxidation of carbon monoxide on platinum metals. J Chem Phys 97 4380- 386, 1989. 

Korzeniewski C, Pons S, Schmidt PP, Severson MW. 1986. A theoretical analysis of the vibrational spectrum of carbon monoxide on platinum metal electrodes. J Chem Phys 85 4153-4160. 

Elementary Steps in the Catalytic Oxidation of Carbon Monoxide on Platinum Metals T. Engel and G. Ertl... 

Elementary Steps in the Catalytic Oxidation of Carbon Monoxide on Platinum Metals T. Engel and G. Ertl The Binding and Activation of Carbon Monoxide, Carbon Dioxide, and Nitric Oxide and Their Homogeneously Catalyzed Reactions... 

On the surface of metal electrodes, one also hnds almost always some kind or other of adsorbed oxygen or phase oxide layer produced by interaction with the surrounding air (air-oxidized electrodes). The adsorption of foreign matter on an electrode surface as a rule leads to a lower catalytic activity. In some cases this effect may be very pronounced. For instance, the adsorption of mercury ions, arsenic compounds, or carbon monoxide on platinum electrodes leads to a strong decrease (and sometimes total suppression) of their catalytic activity toward many reactions. These substances then are spoken of as catalyst poisons. The reasons for retardation of a reaction by such poisons most often reside in an adsorptive displacement of the reaction components from the electrode surface by adsorption of the foreign species. 

Large platinum carbonyl clusters have been investigated as models for the adsorption of carbon monoxide on platinum surfaces and on platinum electrodes. An issue is how large the clusters must be before they adopt the properties of the bulk metal. Teo et al. have investigated the magnetic properties of the clusters [Pt6(CO)12]2+, [Pt9(CO)18]2+, [Pt y(CO)22f+, and... 

Since the early work of Langmuir (1), the chemisorption of carbon monoxide on platinum surfaces has been the subject of numerous investigations. Besides its scientific interest, an understanding of CO chemisorption on Pt is of considerable practical importance for example, the catalytic reaction of CO over noble metals (such as Pt) is an essential part of automobile emission control. 

Wong YT, Hoffmann R (1991) Chemisorption of carbon monoxide on three metal surfaces nickel (111), palladium(l 11), and platinum(l 11) a comparative study. J Phys Chem 95 859-867... 

Lanova B (2009) Oxidation of methanol and carbon monoxide on platinum surfaces. The influence of foreign metals. Ph.D., Rheinische Friedrich-Wilhelms Universitat Bonn, Germany... 

Engel, T. and Ertl, G. (1979). Elementary steps on catalytic oxidation of carbon monoxide over platinum metals, Adv. Catal., 28, pp. 1-78. 

However, although the determination of the heat of adsorption of carbon monoxide on platinum have been reported in the literature (Table 12.2), the possible use of adsorption microcalorimetry as an available technique for giving valuable information in PEM fuel cells smdies has not been reported. In what follows, recent results from our work in the field of microcalorimetry of CO adsorption on Pt/C catalysts are presented [65-67]. The catalysts used in these studies were different commercial carbon-supported platinum, with high Pt loading, aimed to be used in PEMFCs applications. Particular emphasis on the sample history (preparation method, the support material, the metal loading) and the pre-treatment of the catalysts on the CO poisoning effect on supported platinum is paid. 

The first example concerns the adsorption of hydrogen on platinum in acid media. The second deals with the comparative adsorption of carbon monoxide on noble metals in aqueous medium, with a special emphasis on platinum and palladium. The third example is a discussion of the contribution of in situ reflectance spectroscopy to solving certain problems encountered in electrocatalysis. Finally, the last example concerns nonaqueous solvents in particular and the detection of species in the double layer. 

Compensation effects have been reported for the oxidation of ethylene on Pd-Ru and on Pd-Ag alloys (207, 254, 255) discussion of the activity patterns for these catalysts includes consideration of the influence of hydrogen dissolved in the metal on the occupancy of energy bands. Arrhenius parameters reported (208) for ethylene oxidation on Pd-Au alloys were an appreciable distance from the line calculated for oxidation reactions on palladium and platinum metals (Table III, H). Oxidation of carbon monoxide on Pd-Au alloys also exhibits a compensation effect (256). 

Galwey AK, Bettany DG, Mortimer M (2006) Kinetic compensation effects observed during oxidation of carbon monoxide on y-alumina supported palladium, platinum, and rhodium metal catalysts toward a mechanistic explanation. Int J Chem Kin 38 689... 

The influence of the support is undoubted and spillover was further confirmed by the excess of hydrogen chemisorbed by a mechanical mixture of unsupported alloy and TJ-A1203 above that calculated from the known values for the separate components. It was also observed that the chemisorption was slower on the supported than on the unsupported metal and that the greater part of the adsorbate was held reversibly no comment could be made on the possible mediation by traces of water. On the other hand, spillover from platinum-rhenium onto alumina appears to be inhibited for ratios Re/(Pt Re) > 0.6. In an infrared investigation of isocyanate complexes formed between nitric oxide and carbon monoxide, on the surface of rhodium-titania and rhodium-silica catalysts, it seems that the number of complexes exceeded the number of rhodium surface atoms.The supports have a pronounced effect on the location of the isocyanate bond and on the stability of the complexes, with some suggestion of spillover. 

Carbon monoxide-metal systems have also been used to demonstrate the effect of carrier material on properties of supported metal catalysts. Eischens and Plisken (1) found that the ratio of concentrations of linear to bridged species was much larger when platinum was supported on silica than when it was supported on alumina. Carbon monoxide on the alumina-supported samples was much more difficult to oxidize than on silica-supported ones. These observations were interpreted as an enhancement of platinum s ability to donate electrons to the metal-CO bond when alumina is the support. However, the mechanism by which... 

Now, theoretical calculation methods of sufficient accuracy may fill the lack of quantitative information concerning so elusive species. On the other hand, the use of a monocoordinated complex as being the simplest molecular model to simulate a chemisorption phenomenon on a metallic surface, for instance the chimisorption of carbon monoxide on iron or nickel [16,17,18] enables to predict the shifts of the CO stretching vibration of the adsorbed species. Similar effects observed with cyanide anions CN on a cathode of platinum, silver or gold, using non-linear optics techniques can be rationalized by computing the CN vibration mode of the corresponding triatomic systems [19,20,21]. 

Heiz U, Sanchez A, Abbet S, Schneider W-D (1999) Catalytic oxidation of carbon monoxide on monodispersed platinum clusters each atom counts. J Am Chem Soc 121 3214—3217 Henglein A (1989) SmaU-particle research physicochemical properties of extremely small colloidal metal and semiconductor particles. Chem Rev 89 1861-1873... 

Metals such as Fe, Ni, Ru and Rh react directly with carbon monoxide, but platinum together with palladium [2] is not able to react directly with carbon monoxide. As shown in eqs. (21.19H21.20), platinum compounds are able to react with carbon monoxide in the presence of phosphine via phosphine complexes [32]. On the other hand, a phosphine complex reacts with carbon monoxide in the presence of alcohol to afford an ester as shown in eq. (21.21) [33]. 

The anodic oxidation of fuels in low temperature cells, mainly on platinum metals, platinum metal alloys and alloys of platinum metals with other metals, is the subject of this chapter. Most oxidation studies were made on these metals because the efficiency of other electrocatalysts is too low. The mechanism for the oxidation of carbon monoxide, nlixtures of hydrogen and carbon monoxide, formic acid, methanol, higher alcohols, hydrocarbons, and hydrazine is discussed in separate sections. 

Abstract To date, microcalorimetry of CO adsorption onto supported metal catalysts was mainly used to study the effects induced by the nature and the particle size of supported metallic clusters, the conditions of pretreatment and the support materials on the surface properties of the supported metallic particles. The present chapter focuses on the employ of adsorption microcalorimetry for studying the interaction of carbon monoxide with platinum-based catalyst aimed to be used in proton exchange membrane fuel cells (PEMFCs) applications. 

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