Degree of methanation

Noble metal catalysts High yields of synthesis gas were reported for the partial oxidation of methane over nearly all noble metal catalysts (Pd, Rh, Ru, Pt, Ir) [110]. The observed performances (degree of methane conversion and yields of CO and H2) vary with the catalyst and the operating conditions but all reported data share these common features (i) no carbon deposition is observed (Claridge and co-workers [135]... 

B Degree of Methanal (HCHO) Substitution per C9 Unit of Lignin by Various Methods ... 

Translational temperature To in the non-equilibrium plasma system was not sufficient for effective methane conversion, whereas vibrational temperature was able to stimulate the process. The conversion degree of methane into acetylene achieved in the plasma system is presented in Fig. 9-5 as a function of the specific energy input at three different pressures 10, 40, and 80 Torr. When the pressure increases from 10 to 80 Torr, the methane-to-acetylene conversion degree rises and reaches a maximum of 80% at = 2.6 eV/mol CH4. The gas-product composition in this regime is H2,73 vol % CH4,5 vol % and C2H2,22 vol %. The concentration of ethylene, ethane, and higher hydrocarbons is less than 1% soot production... 

Figure 9-5. Conversion degree of methane into acetylene as a function of specific energy input at three different pressures (10,40, and 80 Torr).

Kinetic analysis shows that the growth of the partial pressure of the reactants should lead not only to an increase in the methane conversion rate, but also to an enhancement of the role of nonlinear gas-phase radical reactions. A consequence may be an increase in the selectivity of methanol formation. Figure 7.1 and Table 7.1 show the most reliable experimental data on the pressure dependence of the methanol deld. All the experiments were performed imder essentially similar conditions, optimal for achieving a high methanol deld. Only the experiments in which the oxygen conversion was close to 100% were taken into accoimt. Comparison was conducted for the methanol )deld, because it is the most reliable experimentally measured quantity. Due to a low degree of methane conversion, the selectivity of methanol formation is usually measured with great imcertainty, let alone that, in many practice-oriented studies, it was not determined at all. For the works [45] and [67], which report only the selectivity, we estimated the methanol )deld based on the relationship A[CH4]/A[Oi] = 1. This makes it possible to evaluate the methanol yield YmcOH as... 

Figure 4.9 shows a plot of Eq. (4.12). As the purge fraction a is increased, the flow rate of purge increases, but the concentration of methane in the purge and recycle decreases. This variation (along with reactor conversion) is an important degree of freedom in the optimization of reaction and separation systems, as we shall see later. 

An interesting point is that infrared absorptions that are symmetry-forbidden and hence that do not appear in the spectrum of the gaseous molecule may appear when that molecule is adsorbed. Thus Sheppard and Yates [74] found that normally forbidden bands could be detected in the case of methane and hydrogen adsorbed on glass this meant that there was a decrease in molecular symmetry. In the case of the methane, it appeared from the band shapes that some reduction in rotational degrees of freedom had occurred. Figure XVII-16 shows the IR spectrum for a physisorbed H2 system, and Refs. 69 and 75 give the IR spectra for adsorbed N2 (on Ni) and O2 (in a zeolite), respectively. 

Chan et al. (1983) studied flame propagation in an obstructed channel whose degree of confinement could be varied by adjustment of exposure of the perforations in its top. Its dimensions were 1.22 m long and 127 x 203 mm in cross section. Results showed that reducing top confinement greatly reduced flame acceleration. When the channel s top confinement was reduced to 10%, the maximum flame speed produced for methane-air mixtures dropped from 120 m/s to 30 m/s. 

The gases resulting from the irradiation of PDMS have been reported in the literature [395] and consist entirely of hydrogen, methane, and ethane. The yield has been found to be proportional to the degree of cross-linking since double bonds cannot be formed. 

In the search of high-performance SOFC anode, doped ceria have been evaluated as possible anode materials [9,10]. Comparing Ni-samaria-doped ceria (SDC) with Ni-YSZ, the Ni-SDC anode exhibits higher open-circuit voltages and a lower degree of polarization with either methanol as the fuel, as shown in Fig. 5, or methane as the fuel, as shown in Fig. 6. It was found that the depolarization ability of the anode is associated with the catalytic activity, the electrical conductivity, and the oxygen ionic conductivity of the anode materials [9]. It was also found that the anodic polarization and electro-catalytic activity strongly depend on the Ni content in the anode, and the optimum result for the Ni-SDC anode is achieved with 60... 

Methanal (formol) presents an additional degree of freedom the out-of-plane wagging of the oxygen atom. In its singlet ground, X Ai, this molecule is planar. But, in its triplet and singlet lowest exited W A" and tt ), this molecule is pyramidal... 

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