Disproportionation, of carbon monoxide

The gained hydrogen from the water shift reaction reduces the hydrogen demand for FTS. Water gas shift proceeds at about the same rate as the FT reaction. Studies of the overall water shift reaction in FT synthesis have been reviewed by Rofer Deporter. Another side reaction also occurring in FTS reactors is the disproportionation of carbon monoxide to carbon dioxide and carbon ... 

H. J. Dai, A. G. Rinzler, P. Nikolaev, A. Thess, D. T. Colbert, and R. E. Smalley, Single-wall nanotubes produced by metal-catalyzed disproportionation of carbon monoxide, Chem. Phys. Lett. 260, 471 75 (1996). 

The difficulty in detecting surface hydride formation is that hydrogen is nearly always contained in the bulk structure of the carbons. Hydrogen is not easily determined with sufficient accuracy if only small concentrations are present. Precise analytic methods should be used in the measurement of the hydrogen uptake of carbons that were prepared with rigorous exclusion of hydrogen-containing contaminants. Carbon formed by the disproportionation of carbon monoxide... 

The most common synthetic method (Fe, Ru, Os) is via pyrolysis of noncarbide metal carbonyl derivatives. It seems probable that the high temperature (140°-260°C) is not only responsible for formation of coor-dinatively unsaturated species and related condensations but also for the necessary disproportionation of carbon monoxide (58) ... 

Carbon nanotubes and nested fullerenes were also prepared by reductive carbonization of CO2 with magnesium metal. Motiei et al. [104] reported on the production of nanotubes in ca. 0% yield and nested fullerenes in ca. 12% yield at 1000°C by the reaction of dry ice and magnesium. The reductive carbonization of CO2 is reminiscent of the HiPco process [105, 106], based on disproportionation of carbon monoxide (the Boudouard reaction) ... 

Fig. 3 shows a series of TPSR curves for reaction of the carbon deposits with H2 as a function of deposition temperature. Results obtained from Kg.3 confirm that two forms of carbon, a relatively active and a relatively inactive form based on their reactivity toward H2, arc deposited on the surface of 10 wt% Co/y-Al203 during the disproportionation of carbon monoxide. The two peaks at 19G 10°C and 43G 10°C are close to those for atomic carbon (Ca) and polymeric carbon (Cp) respectively, designated on Ni/Al203 by McCarty and Wise (7). 

The disproportionation of carbon monoxide according to the Bell reaction... 

A. W. Ritchie Shell Development Company, Emeryville, California) In studying the adsorption of carbon monoxide on evaporated metal films, it was observed that carbon, formed by this disproportionation of carbon monoxide at 200°, diffused from this surface into the bulk metal. Thus, in Cunningham s experiments with carbon monoxide and with ethylene, the absence of carbon on any one plane may signify great activity of the plane for the diffusion process, rather than inactivity for the decomposition reaction. 

Quite a number of years ago we carried out some experiments on films evaporated from Alloy 99 wire. We observed that films evaporated from this wire exhibited quite different properties than those evaporated from Nickel A or Hoskins 651. The films prepared from Alloy 99 showed (211) preferential orientation and were highly resistant to sintering as measured by the hydrogen adsorption. The activity of these films for carbon monoxide oxidation was 15 times greater than the activity of films prepared from the other nickel wires. For the disproportionation of carbon monoxide, 50-60% more CO2 was found than was theoretically possible. When the wire was heated in hydrogen a large decrease in hydrogen pressure with subsequent water formation was observed. 

Another reaction that appears to play an important role in the synthesis of hydrocarbons from CO and H2 is the disproportionation of carbon monoxide ... 

OXIDATION AND DISPROPORTIONATION OF CARBON MONOXIDE OVER Pd/ZrOi CATALYSTS PREPARED FROM GLASSY Pd-Zr ALLOY AND BY COPRECIPITATION... 

Dai. H. Rinzler. A. Nikolaev. P. Thess. A. Colbert, D. Smalley, R. Single-Wall Nanotubes Produced by Metal-Catalyzed Disproportionation of Carbon Monoxide. 

In a hypothetical CCVD process similar to CoMoCAT, SWNT are produced in a fluidized bed reactor by disproportionation of carbon monoxide (2CO C + CO2). Fresh catalyst is added at a continuous rate (CTl) of 10 kg/h. Before puri-Acation, the black sand product (CT2) contains 30 wt% carbon, while the rest of... 

A very successful method for synthesizing interstitial carbide dusters is based on the metal assisted disproportionation of carbon monoxide into a carbide atom and carbon dioxide, which is related to the Bouduard reaction. Thus, most of the Re, Fe, Ru, and Os carbide dusters have been obtained from the thermal decomposition of a carbonyl precursor and the evolution of CO2 has been confirmed in one case. [95]... 

For an oxidized reactor, the exit flow rate was significantly lower than the inlet rate for about 6-12 hours Indicating significant disproportionation of carbon monoxide (and formation of coke). Even after 12 hours of operation, a small amount of carbon dioxide was often being formed in many runs. 

Similar reactions can be written out for other hydrocarbons. Higher hydrocarbons tend to decompose more easily than methane and therefore the risk of carbon formation is higher with vaporised liquid petroleum fuels than with natural gas. Another source of carbon formation is from the disproportionation of carbon monoxide via the so-called Boudouard reaction ... 

The strong inhibiting effect of water during the reduction of well-dispersed iron oxide phases on alumina surfaces is also apparent from the infrared spectrum of carbon monoxide adsorbed onto the reduced catalyst prepared from complex iron cyanides according to the above procedure of Boellaard and co-workers Despite the support, the size of the iron particles, and the loading of iron on the support all being essentially the same, the infrared spectrum of the adsorbed carbon monoxide is completely different. The absorption band at 2155 cm is not seen, which indicates that Fe(II) is not present at the alumina surface when reduced in the presence of low partial pressures of water vapor. Rather than bands with frequencies above about 2000 cm bands at 1806, 1884, and 1984 cm are observed (Fig. 5.9). Even at room temperature, disproportionation of carbon monoxide to carbon dioxide and carbon occurs, which is demonstrated by the presence of carbon dioxide adsorbed onto the alumina support. The infrared bands peaking at 1348 and 1598 cm arise from carbon dioxide adsorbed on alumina. 

TPR indicated that nickel was not completely converted to the metallic state X-ray powder diffraction provided evidence for nickel carbide and, possibly, for nickel oxide, besides for the expected nickel metal and magnesium oxide. Nickel carbide may have originated from disproportionation of carbon monoxide to carbon dioxide and carbon at the nickel metal surface. Since the main diffraction maxima of the four components coincide, neither their relative amounts nor their particle sizes, to be obtained from line broadening, can be properly estimated. 

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