Nickelous oxide catalyst

Na.tura.1 Ga.s Reforma.tion. In the United States, most hydrogen is presently produced by natural gas reformation or methane—steam reforming. In this process, methane mixed with steam is typically passed over a nickel oxide catalyst at an elevated temperature. The reforming reaction is... 

In the Sabatier reaction, methane and water are formed over a nickel— nickel oxide catalyst at 250°C. The methane is recovered and cracked to carbon and hydrogen, which is then recycled ... 

It should be observed that curve C (Fig. 31) which characterizes the steady activity of the catalyst surface may be directly compared to activity curves obtained by other techniques. The evolutions of heat as a function of time produced by the reaction of doses of reaction mixture at the surface of four different nickel oxide catalysts are, for instance, plotted on Fig. 32. These curves are very similar indeed to the kinetic curves obtained with the same catalysts in a classical static reactor (Fig. 33) (8). 

Butanol, reaction over reduced nickel oxide catalysts, 35 357-359 effect of ammonia, 35 343 effect of hydrogen, 35 345 effect of pyridine, 35 344 effect of sodium, 35 342, 351 effect of temperature, 35 339 over nickel-Kieselguhr, 35 348 over supported nickel catalysts, 35 350 Butanone, hydrogenation of, 25 103 Butene, 33 22, 104-128, 131, 135 adsorption on zinc oxide, 22 42-45 by butyl alcohol dehydration, 41 348 chemisorption, 27 285 dehydrogenation, 27 191 isomerization, 27 124, 31 122-123, 32 305-308, 311-313, 41 187, 188 isomerization of, 22 45, 46 isomers... 

Cyclohexanol oxidation, 41 299-300 reactions over reduced nickel oxide catalyst, 35 355-357 Cyclohexanone... 

Propanol, reactions on reduced nickel oxide catalyst, 35 357 Propene, see Propylene Propionaldehyde... 

Before leaving the nickel experiments, it may be well to refer to the experiments on hydrogen adsorption variously reported in the literature. As an example, the work of Maxted and Hassid (13) had as its main objective the measurement of the slow activated adsorption of hydrogen on reduced nickel oxide catalysts. It has been proved by the foregoing that the slow adsorption is actually absorption. When plotting their data as isobars, as was done in Fig. 9, the similarity between these isobars and those obtained with sintered nickel films is evident. 

Lensveld DJ, Mesu JG, van Dillen AJ, de Jong KP (2001) Synthesis and characterization of MCM-41 supported nickel oxide catalysts. Microporous Mesoporous Mat 44-45 401-407... 

VI. Carbon Monoxide Oxidation on Modified Nickel Oxide Catalysts.. 68... 

The method outlined above in the case of zinc oxide will now be applied to the carbon monoxide oxidation on nickel oxide catalysts modified in both ways. If it is assumed, as before, that semiconductivity trends in the bulk and in the surface layer are qualitatively the same, a correlation between semiconduetivity and catalysis will be established if cationic impurities of valences lower and higher than 2 are found to affect the catalytic rate in opposite directions. 

If further work confirms our explanations which connect catalytic inversion with the inversion of physical properties of the modified nickel oxide catalysts, the correlation between semiconductivity and oxidation catalysis found in the Princeton work and in Schwab s studies will appear quite convincing. To sum up, the activation energy of the carbon monoxide oxidation has been found to decrease with increasing semiconductivity on both sides of the inversion point of physical properties of nickel oxide catalysts. 

Fig. 10. Percentage decomposition of N2O on a nickel oxide catalyst, with various additions of Li2O and InjOs, as a function of the temperature, according to Hauffe, Glang, and EngeU. (Composition of the reacting gas 15% N2O and 86% air flow rate 1200 cm. /hour.)...

Tile partially purilied synthesis gas leaves the C02 absorber containing approximately 0.1% CO2 and 0.5% CO. This gas is preheated at the methanator inlet by heat exchange with the synthesis-gas compressor interstage cooler and the primary-shift converter effluent and reacted over a nickel oxide catalyst bed in the methanator. The methanation reactions are highly exothermic and are equilibrium favored by low temperatures and high pressures. 

The best example of a study of this type of intermediate is found in the oxidation of CO over a nickel-nickel oxide catalyst 24). The latter term is used because there is doubt as to the specific nature of the catalyst surface. The spectrum in Fig. 14 was obtained during the oxidation of CO over nickel-nickel oxide at 35° C. The band at 4.56 u is tentatively attributed to an intermediate complex having the structure Ni- 0 C rr.O. The bands at 6.5 and 7.2 u are due to C02 chemisorbed on the catalyst surface. This C02 is considered to be adsorbed product rather than as a reaction intermediate because these bands remain after the reaction is completed. The 4.56- u band in Fig. 14 is attributed to the asymmetrical 0—C—0 vibration rather than to the C—O vibration of chemisorbed CO. This interpretation implies that there should be a second band due to the symmetrical vibration. The symmetrical 0—C—O vibration of C02 produces a Raman band at 7.2 ju. The symmetrical 0—C—0 vibration of Ni - -O—C=0 would be expected to produce an infrared band near 6 or 7 u- Thus far this band has not been observed. This failure is not considered a serious obstacle to the structure assignment,... 

Coke Deposition on a Commercial Nickel Oxide Catalyst During the Steam Reforming of Methane... 

The steam reforming of methane cycle suffers from the problem of coke deposition on the catalyst bed. The primary objective of this project was to study the stability of a commercial nickel oxide catalyst for the steam reforming of methane. The theoretical minimum ratios of steam to methane that are required to avoid deposition of coke on the catalyst at various temperatures were calculated, based on equilibrium considerations. Coking experiments were conducted in a tubular reactor at atmospheric pressure in the range of 740-915°C. 

Thermodynamically, the reforming reaction. Equation 3.5.1, shows that the reformer should be operated at die lowest pressure and highest temperature possible. The reforming reaction occurs on a nickel-oxide catalyst at 880 C (1620 "F) and 20 bar, which results in a 25 "C approach to the equihbrium temperature [25,29]. Methane conversion increases by reducing the pressure, but natural gas is available at a high pressure. It would be costly to reduce the reformer pressure and then recompress the synthesis gas later to 100 bar (98.7 atm) for the converter. The steam to carbon monoxide ratio is normally in the range of 2.5 to 3.0 [30]. The ratio favors both the conversion of methane to carbon monoxide and the carbon monoxide to carbon dioxide as indicated by Equations 3.5.1 and 3.5.3. If the ratio is decreased, the methane concentration increases in the reformed gas, but if the ratio is set at three, the unreacted methane is small. The methane is a diluent in the synthesis reaction given by Equation 3.5.2. 

B. The Oxidation of Carbon Monoxide over Doped Nickel Oxide Catalysts.. 36... 

Introduction. When a saturated hydrocarbon like ethane, CH3CH3, is passed over a nickel oxide catalyst heated to 800°, hydrogen is removed (dehydrogenation) and ethene, CH2CH2, is one of the products ... 

It should be noted here that acid sites were proved to exist in the nickel oxide catalyst which was supported on silica gel and further that these sites promoted dimerization of ethylene, accompanied by isomerization of the 1-butene produced 13). 

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