Carbon monoxide over platinum

Cutlip, M. B., Hawkins, C. J., Mukesh, D., Morton, W. and Kenney, C. N., 1983, Modelling of forced periodic oscillations of carbon monoxide over platinum catalyst. Chem. Eng. Commun. 22, 329-344. 

Carbonyl Platinum Dibromide, PtBr2. CO, was prepared by Pullinger1 by passing a slow stream of dry carbon monoxide over platinum dibromide gradually heated to about 180° C. 

In 1891, Pullinger reported that passing a mixture of dichlorine and carbon monoxide over platinum sponge at 250 C produced a yellow solid, which was formulated (upon very... 

The oxidation of carbon monoxide over platinum was studied as a model reaction to evaluate the performance of the new Multitrack system. Multitrack, developed in our laboratories, is an advanced version of a TAP (Temporal Analysis of Products) apparatus [1]. The advantages of using this reaction as a model reaction are that the reaction is fast, the only possible reported by-product is carbon, and that the reaction has been studied using conventional TAP systems [2,3]. 

The well-known adsorption mechanism for the oxidation of carbon monoxide over platinum at constant partial pressures of oxygen and carbon monoxide,... 

The group of Wicke (Beusch et al., 1972a Beusch et al., 1972b) was the first to observe kinetic self-sustained oscillations in solid-catalyzed reactions, when studying the oxidation of carbon monoxide over platinum-based catalysts. At certain conditions, oscillations were observed in the production rate of carbon dioxide. Based on these experimental data,... 

Zheng X, Schidtze M, Mantzaras J, Bombach R, Boulouchos K Effects of hydrogen addition on the catalytic oxidation of carbon monoxide over platinum at power generation relevant temperatures, Proc Combust Inst 34 3343—3350, 2013b. 

Gosavi, P.V. and Biniwale, R.B. (2013) Catalytic preferential oxidation of carbon monoxide over platinum supported on... 

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

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. 

Dynamic reactor studies are not new, but they have not been widely used in spite of the fact that they can provide a wealth of information regarding reaction mechanisms. In this research, oxidation of carbon monoxide over supported cobalt oxide (C03O4) was studied by both dynamic and conventional steady state methods. Among metal oxides, cobalt oxide is known to be one of the most active catalysts for CO and hydrocarbon oxidation, its activity being comparable to that of noble metals such as palladium or platinum. 

Carbonyl compounds are formed with platinous derivatives, as, for example, by passing carbon monoxide over platinous chloride at 250°. Under these conditions there is obtained a mixture of PtCl - 2 CO, and 2 PtClj 3 CO, which on further heating gives PtClj CO. Other platinous compounds yield similar derivatives. Carbonyl compounds may also be prepared by passing an equimolecular mixture of carbon monoxide and chlorine over platinum sponge or foil at 240°-250°. This reaction is sometimes used to detect the presence of small amounts of rhodium or certain base metals in platinum. ... 

In a jump model of the surface diffusion process, this process is considered to proceed by jumplike substance exchange between different locations on the surface. Gorban et al. (1980) used this model for modeling of the oxidation of carbon monoxide over a platinum catalyst. One step of this reaction involves the reversible exchange of an adsorbed carbon monoxide molecule with the neighboring empty site ... 

Cant, N., Hicks, P. and Lennon, B. (1978). Steady state oxidation of carbon monoxide over supported noble metal catalysts with particular reference to platinum, J. Catal., 54, pp. 372-383. Taylor, K. (1984). Catalysis, Science and Technology, J. Anderson and M. Boudart (eds), Vol. 5. Springer Verlag, Berlin, p. 119. 

Ceint NW, Hicks PC, Lennon BS (1978) Steady-state oxidation of carbon monoxide over supported noble metals with particular reference to platinum. J Catal 54 372-383... 

One of the objectives of this book is to demonstrate how the overall reaction rate of a catalytic reaction can be predicted once the rate constants and equilibrium constants of the elementary reaction steps are known. Such data can be obtained from model experiments, often in surface science, or from theoretical calculations. The ammonia synthesis was among the first catalytic reactions for which the rate was predicted under high pressure conditions. This was a remarkable success, as the calculation involved an extrapolation of data obtained under vacuum over a pressure interval of ten orders of magnitude. Here the effective rate constant of a less complex reaction is derived, the oxidation of carbon monoxide on platinum. We will use the reaction mechanism of Scheme (6.1) and label rate and equilibrium constants according to the number of the elementary steps in (6.1). 

In one patent (31), a filtered, heated mixture of air, methane, and ammonia ia a volume ratio of 5 1 1 was passed over a 90% platinum—10% rhodium gauze catalyst at 200 kPa (2 atm). The unreacted ammonia was absorbed from the off-gas ia a phosphate solution that was subsequently stripped and refined to 90% ammonia—10% water and recycled to the converter. The yield of hydrogen cyanide from ammonia was about 80%. On the basis of these data, the converter off-gas mol % composition can be estimated nitrogen, 49.9% water, 21.7% hydrogen, 13.5% hydrogen cyanide, 8.1% carbon monoxide, 3.7% carbon dioxide, 0.2% methane, 0.6% and ammonia, 2.3%. 

A sophisticated quantitative analysis of experimental data was performed by Voltz et al. (96). Their experiment was performed over commercially available platinum catalysts on pellets and monoliths, with temperatures and gaseous compositions simulating exhaust gases. They found that carbon monoxide, propylene, and nitric oxide all exhibit strong poisoning effects on all kinetic rates. Their data can be fitted by equations of the form ... 

Fig. 18. Inhibition effect of carbon monoxide on carbon monoxide conversion at 400°F over platinum. 100 ppm CaH8> 4.5% 02, 100 ppm NO.

Houdry s solution to the problem was the first catalytic converter ever designed for an automotive vehicle. The catalytic converters found on almost all cars and trucks in use today are still strikingly similar to his invention. Exhaust gases passed into the converter and over a bed of platinum catalyst, then exited with a greatly reduced concentration of carbon monoxide, nitrogen oxides, and unburned hydrocarbons. Houdry obtained a patent for his device in 1956 and founded a company, Oxy-Catalyst, to manufacture and sell the new product. 

However, the analysis of the data was carried out in such a way as to cast doubt on the validity of these conclusions (Vayenas54). Okamoto, Kawamura and Kudo48 went on to use the e.m.f. interpretation from the above work49 to further investigate the mechanism of CO oxidation over platinum by using the cell as a probe of the surface coverage of carbon monoxide. 

Metcalfe and Sundaresan15 went on to confirm that e.m.f. s obtained in the case of CO oxidation over platinum cannot be explained if reaction (3.3) is the only electrochemical reaction to occur. Even under oxygen rich conditions, carbon monoxide was involved in the electrochemical reactions, the dominant electrochemical reactions being,15... 

Potentiometric techniques have been used to study autonomous reaction rate oscillations over catalysts and carbon monoxide oxidation on platinum has received a considerable amount of attention43,48,58 Possible explanations for reaction rate oscillations over platinum for carbon monoxide oxidation include, (i) strong dependence of activation energy or heat of adsorption on coverage, (ii) surface temperature oscillations, (iii) shift between multiple steady states due to adsorption or desorption of inert species, (iv) periodic oxidation or reduction of the surface. The work of Sales, Turner and Maple has indicated that the most... 

Carbon Monosulphide, CS.—This sulphur analogue of carbon monoxide is described as resulting8 on passing carbon disulphide vapour over spongy platinum, pumice stone or red-hot charcoal. It is also formed by the action of the silent electric discharge 7 on carbon disulphide or on a mixture of the latter with either hydrogen or carbon monoxide, thus ... 

---