Hydrogen-carbon monoxide ratio, effect

The thermodynamics of the above reactions are illustrated in Figures 5.6 and 5.7174. Both figures assume a steam-to-methane ratio of 1.0. Figure 5.6 illustrates how the feed and product gases interact when the product gas has a hydrogen-to-carbon monoxide ratio of 3.0. Figure 5.7 illustrates the effects of temperature and pressure on the reactions. As pressure increases, lower conversion can be expected and more methane will not be converted and will be found in the reformer discharge stream. 

Hydroformylation of linear olefins in a conventional cobalt oxo process (see Section 5.3) produces increasing linear-to-branched aldehyde ratios as the carbon monoxide ratio in the gas stream is increased up to 5 MPa (50 atm), but there is little further effect if the reaction mixture is saturated with carbon monoxide. An increasing partial pressure of hydrogen also increases this ratio up to a hydrogen pressure of 10 MPa. As the reaction temperature is increased, the linear-to-branched aldehyde ratios decreases. Solvents in conventional cobalt-catalyzed hydroformylation affect the isomer distribution. In propylene... 

In the various laboratory studies when the outlet gas composition was not at equilibrium, it was observed that the steam-to-gas ratio (S/G) significantly affected the hydrogen leakage while the carbon monoxide still remained low. On the assumption that various reactions will proceed at different rates, a study was made to determine the effect of S/G on the reaction rate. The conditions for this test are presented in Table VII the findings are tabulated in Table VIII. 

From the results of other authors should be mentioned the observation of a similar effect, e.g. in the oxidation of olefins on nickel oxide (118), where the retardation of the reaction of 1-butene by cis-2-butene was greater than the effect of 1-butene on the reaction of m-2-butene the ratio of the adsorption coefficients Kcia h/Kwas 1.45. In a study on hydrogenation over C03O4 it was reported (109) that the reactivities of ethylene and propylene were nearly the same (1.17 in favor of propylene), when measured separately, whereas the ratio of adsorption coefficients was 8.4 in favor of ethylene. This led in the competitive arrangement to preferential hydrogenation of ethylene. A similar phenomenon occurs in the catalytic reduction of nitric oxide and sulfur dioxide by carbon monoxide (120a). 

The effects of tin/palladium ratio, temperatnre, pressnre, and recycling were studied and correlated with catalyst characterization. The catalysts were characterized by chemisorption titrations, in situ X-Ray Diffraction (XRD), and Electron Spectroscopy for Chemical Analysis (ESCA). Chemisorption studies with hydrogen sulfide show lack of adsorption at higher Sn/Pd ratios. Carbon monoxide chemisorption indicates an increase in adsorption with increasing palladium concentration. One form of palladium is transformed to a new phase at 140°C by measurement of in situ variable temperature XRD. ESCA studies of the catalysts show that the presence of tin concentration increases the surface palladium concentration. ESCA data also indicates that recycled catalysts show no palladium sulfide formation at the surface but palladium cyanide is present. 

In order to further assess the effect of parametrical changes to the Rh-3-SlLP hydroformylation system, the ratio between the partial pressures of hydrogen and carbon monoxide (pH2 pco ratio) has been varied between 0.25 and 4 (at constant total pressure) in reactions performed at 65 and 100 °C [31]. Increasing the hydrogen partial pressure had a profound effect on the catalyst activity for both temperatures, as depicted in Fig. 5. 

The effect of the hydrogen to carbon monoxide molar ratios in the feed gas to the reaction is significant. Changes in the feed gas ratio will strongly affect the equilibrium of Equation 1 and thus impact the performance and selectivity of the catalyst. A series of bench unit runs were performed and the data is summarized in Table 3. 

The general behavior of rhodium catalysts with respect to stability thus appears to be similar to that seen for cobalt catalysts an inverse relationship between carbon monoxide partial pressure and reaction temperature is apparent. Stability decreases rapidly with increasing temperature, and raising the pressure tends to improve catalyst stability. It is not certain whether the adverse effects of increasing the H2/CO ratio are merely the result of a decreased CO partial pressure, or whether increased hydrogen partial pressure induces catalyst instability. 

The implicit assumption was that hydrogenation of carbon monoxide is the main reaction for the formation of methanol. It was observed, however, that an optimum proportion of carbon dioxide was needed to achieve maximum methanol yield and to prevent catalyst deactivation 369 Klier attributed these effects to the ability of C02 to maintain an adequate concentration of Cu+ species. Later studies indicated that the optimal C02 CO ratio corresponds to 6% C02 in the feed under industrial conditions. 

Abstract In this paper, we discuss the results of a preliminary systematic process simulation study the effect of operating parameters on the product distribution and conversion efficiency of hydrocarbon fuels in a reforming reactor. The ASPEN One HYSYS-2004 simulation software has been utilized for the simulations and calculations of the fuel-processing reactions. It is desired to produce hydrogen rich reformed gas with as low as possible carbon monoxide (CO) formation, which requires different combinations of reformer, steam to carbon and oxygen to carbon ratios. Fuel properties only slightly affect the general trends. 

At about 1 140 °C reaction temperature, full oxygen conversion was always achieved when the CH4/02 ratio was decreased from 2 to 1.5, but methane conversion increased from 45 to 96%. Carbon monoxide selectivity remained almost unchanged at 90%, but hydrogen selectivity increased from 75 to 83%. These effects were assumed to stem from the increased heat generation by enhanced methane combustion leading to a hot-spot at the reactor inlet. 

Under Intrinsic kinetic conditions this ratio Increases with hydrogen concentration In the liquid but Is Independent of carbon monoxide concentration. Hence with significant mass-transfer, this ratio Is governed by the resistance to H2 transfer rather than by the effective H-/CO ratio In the liquid. 

For metals promoting other metals, an interesting case was studied by Hurst and Rideal.2 In the combustion of mixtures of hydrogen and carbon monoxide, using copper as the basic catalyst the ratio of the gases burnt depends on the temperature, and also on the amount of small additions of palladium made to the copper. The proportion of carbon monoxide burnt is increased by addition of palladium, a maximum proportion of carbon monoxide being burnt when 0-2 per cent, of palladium is. present. With further amounts of palladium, the ratio CO H2 burnt falls off slowly until, with 5 per cent, palladium, it is nearly the same as with pure copper. This effect of palladium is ascribed to the introduction of a new type of surface, the line of contact between palladium and copper, though the proof that this is the cause of promotion is perhaps not complete. Mit-tasch and others,3 in elaborate studies of the promotion of various metal catalysts, particularly molybdenum, for the synthesis or decomposition of ammonia, concluded that the formation of intermetallic compounds... 

More industrial polyethylene copolymers were modeled using the same method of ADMET polymerization followed by hydrogenation using catalyst residue. Copolymers of ethylene-styrene, ethylene-vinyl chloride, and ethylene-acrylate were prepared to examine the effect of incorporation of available vinyl monomer feed stocks into polyethylene [81]. Previously prepared ADMET model copolymers include ethylene-co-carbon monoxide, ethylene-co-carbon dioxide, and ethylene-co-vinyl alcohol [82,83]. In most cases,these copolymers are unattainable by traditional chain polymerization chemistry, but a recent report has revealed a highly active Ni catalyst that can successfully copolymerize ethylene with some functionalized monomers [84]. Although catalyst advances are proving more and more useful in novel polymer synthesis, poor structure control and reactivity ratio considerations are still problematic in chain polymerization chemistry. 

A representative comparison of the effect of the catalyst bed geometry on methane conversion and product selectivity over a range of methane/air ratios is shown in Fig 4 Unlike typical supported catalysts, where the catalyst is well-dispersed and submicrometer-sized, the noble-metal catalysts in these methane oxidation reactions were basically films with micrometer-sized surface features (Other tests on both extruded cordiente and alumina foam monoliths with lower catalyst loading resulted in similar carbon monoxide production but lower hydrogen yields than those illustrated in the figure, which provided evidence that the reaction is catalyst-dependent and not initiated by the monoliths or gas... 

According to Natta s law (eq. (7)) the overall reaction rate is independent of the total pressure as long as the ratio of p(CO) to jp(H2) is 1 1 and a minimum carbon monoxide pressure is maintained to stabilize the metal carbonyl species. The influence of the partial pressure of carbon monoxide is depicted in Figure 5 (cf. p. 58). Low p(CO) initially increases the reaction rate whereas at higher partial pressures the rate drops (cf. Section 2.1.1.3.2) [96e, 123]. Raising the hydrogen partial pressure increases the reaction velocity [124] and to some extent the n/i ratio [125]. The latter effect is much less pronounced than for p(CO). Above a p(H2) of 60-80 bar almost no improvement in the n/i ratio is observed. 

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