Process parameters methanol yield

Figure 4.15 presents experimental data on the contact time influence on the methane oxidation process. At contact time r = 0.95 s, the maximum methanol yield is observed. Further increase of this parameter reduces methanol yield. 

In equation (6) the quantities A, E, n, m, D, and F are semiempirical parameters. It can be seen that this rate equation predicts that the methanol yield would decrease as the C02 partial pressure is increased and would drop to zero for synthesis gas that contains carbon dioxide only. Hence Eq. (6) describes a process in which carbon dioxide is a retardant but not at all a reactant or a promoter. 

The methanol unit operating regime, process parameters, and sometimes the catalyst may be adjusted to yield a significant co-production of higher mixed alcohols typically ranging from C2 to C6. 

Later, a few small plants were built, the process parameters for which were, apparently, quite different. According to [262], the process occurred without catalyst. In this case, natural gas containing 25% ethane yielded a liquid product containing 35% methanol, 20% formaldehyde, 5% acetaldehyde, and some amounts of acetone and dimethyl acetal. According to [263], 1 m of natural gas containing 60% methane (the rest, propane and butane) was... 

The molar ratio of methanol to fatty acids is also an important parameter that controls the reaction. Figure 6 shows the obtained yields of methyl esters from oleic acid, a model of fatty acids, treated at various molar ratios of methanol to fatty acid. Interestingly, compared with the transesterification reaction shownby the dashed line (13), methyl esterification proceeded more at the lower molar ratio, and it is apparent that at a molar ratio of 3, oleic acid was mostly converted to its methyl ester. This result is important in designing the production process, since a reaction with a low molar ratio requires less energy for the process. 

On the basis of these results new ranges of the parameters for the optimization work (and scope of operation) were set substrate/catalyst ratio (range 1700-2300), temperature (25-45 °C), pressure (4-10 bar), methanol concentration (800-1200 g/ mol 19). The stirring rate was not included for the subsequent statistical design. The vertex centroid plan (quadr. D-opt., 19 runs) recommended by Stavex was used. The goal of the optimization was to refine conditions in order to ensure a robust and technically feasible process, and the measure of performance was the yield of the desired optically active 20. 

Methanol Production. Kinetics Surface Science, and Mechanisms Methanol production from CO, CO2, and H2 is an industrial process that yields about 3 X 10 kg per day. The relevant thermodynamic parameters for the two reactions are [127]... 

Terada et al. (1988) synthesized extremely small particles of Laj. Nd OCl by a liquid phase process. The appropriate ratio of the pure chlorides was dissolved in methanol and NH3(g) added to the solution. The homogeneous mixture of La(OH)3, Nd(OH)3, and NH Cl which resulted upon heating in air yielded particles of a few hundred angstroms in size. Ultimate particle size depended upon the heat-treatment temperature powders treated at 400°C yielded a crystalline X-ray powder diffraction pattern. The hexagonal c lattice parameters vary linearly within the rather large error limits that result from the small particle size. 

In [101], a cylindrical CSTR with an inner Pyrex liner was used (Fig. 3.56). Experiments in this reactor showed that the reaction has a thermal hysteresis, the parameters of which are in qualitative agreement with estimates obtained in [104] within the framework of a nonisother-mal kinetic model of the process. It was demonstrated that the residence time of the mixture in the CSTR after complete oxygen conversion does not affect the selectivity and yield of methanol. As in flow reactors, at a constant rate of reagents consumption, the selectivity and yield of methanol increase with the pressure, in agreement with the simulation results. Generally, the results obtained in CSTRs are consistent with the results obtained in flow reactors. 

The works [158,185—188] investigated the effect of various parameters on the reaction onset temperature and the yield of the products. At pressures of 1 and 5 atm, the increase of the initial concentration of NO to 1% significantly, by 100 °C, decreased the temperature of the process, although the maximum obtainable conversion of methane was almost the same. However, the increase of the NO concentrations to 1.5% produced practically no effect. At these pressures, the selectivity of formation of oxygenates (methanol, formaldehyde, and nitromethane) reached a maximum at an NO concentration of 0.5%, so this concentration was adopted as optimal. The ethane formation selectivity decreased rapidly with increasing NO concentration, nearly to zero. Diluting the mixture with helium, at least up to 60%, had a moderate effect on the process. Even the CH4/O2 ratio, a key parameter of the... 

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