Carbon monoxide oxidation— oxygen effect

There is little information of the chemisorption of water on gold surfaces, although its presence has a marked acceleratory effect on the rate of carbon monoxide oxidation over Au/Si02 132 since the support is not expected to be involved in the reaction, it was considered that it might help the adsorption of oxygen on gold panicles. Water occupies oxygen vacancies on... 

The catalysts were evaluated by exposure to a simulated automobile exhaust gas stream composed of 0.2% isopentane, 2% carbon monoxide, 4% oxygen and a balance of nitrogen. The temperature required to oxidize the isopentane and carbon monoxide was used to compare catalyst performance. The chromium-promoted catalyst oxidized isopentane at the lowest temperature, and a mixed chromium/copper-promoted catalyst proved the most efficient for oxidizing carbon monoxide and isopentane. It is interesting to note that the test rig used a stationary engine with 21 pounds of catalyst. Although the catalyst was very effective it is difficult to envisage uranium oxide catalysts employed for emission control of mobile sources. 

CO, but it appeared that the oxygen could have changed the nature of the vessel surface, which was coated with boric acid. They finally concluded that the addition of CO, O2 or N2 had little effect on the initial oxidation rate. On the other hand, Hoare and Walsh [357] found an increase in the oxidation rate when the concentration of either the carbon monoxide or oxygen was raised. The contrasting results on the effect of oxygen are shown in Fig. 63 and 64. 

EniChem set up a project aimed at the development of a nonphosgene synthesis of DMC for large volume usage as a result, a new industrial process was established, based on a liquid-phase methanol oxidative carbonylation in the presence of copper chlorides as catalysts. This catalytic system was highly effective in DMC production the reaction was carried out by feeding at the same time methanol, carbon monoxide, and oxygen to the suspension of the catalyst in a mixture of water, methanol, and DMC and recovering DMC by distillation after the catalyst separation. Besides, the process... 

Other subjects recently discussed include the photocoabsorption of carbon monoxide and oxygen on ZnO,664 the relative photoabsorption of oxygen and methane over ZnO,665 the photocatalytic properties of ZnO and MgO,66 the effect of irradiation on the dielectric properties of Ti02,667 the photoluminescence of an oxide layer on aluminium,668 the singlet-triplet splitting of the free A-exciton in ZnO,659 the properties of the photosensitive film of copper in iodine solution,580 and the photosensitivity of layers of CuCla and [Fe(ox)8]3-.681... 

CO2, which must be removed from the product gas. The oxidative carbonyl-ation route uses carbon monoxide and oxygen in the presence of an alcohol to form intermediates that are converted to urethanes. This uses carbon monoxide feedstock more effectively and shows more promising economics. 

Mukesh, D., Cutlip, M.C., Goodman, M., Kenney, C.N., Morton, W., 1982. The stability and oscillations of carbon monoxide oxidation over platinum supported catalyst. Effect of butene. Chem. Eng. Sci. 37, 1807-1810. Mukesh, D., Kenney, C.N., Morton, W., 1983. Concentration oscillations of carbon monoxide, oxygen and 1-butene over a platinum supported catalyst. Chem. Eng. Sci. 38, 69-77. 

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. 

Tethwisch, D.G. and Dumesic, J.A. (1986) Effect of metal-oxygen bond strength on properties of oxides. 1. Infrared spectroscopy of adsorbed carbon monoxide and carbon dioxide, Langmuir, 2, 73. 

The ionization probabilities It vary over some five decades across the elements in the periodic table. In addition, they vary also with the chemical environment of the element. This effect, usually referred to as the matrix effect, makes quantitation of SIMS spectra extremely difficult. As illustrated in Table 4.1, positive secondary ion yields from metal oxides are typically two orders of magnitude higher than those of the corresponding metals. A similar increase in yields from metals is observed after adsorption of gases such as oxygen or carbon monoxide. 

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