2310. MONTGOMERY, C. W., WEINBERGER, E. B., AND HOFFMAN, D. S. Thermodynamics and Stoichiometry of Synthesis Gas Production by the Partial Oxidation of Methane. Ind. Eng. Chem., vol. 40, 1938, pp. 601-607; Chem. Abs., vol. 42, 1948, p. 4329.
In considering the economics of Fischer-Tropsch synthesis gas production by the partial oxidation of CH4, situations may arise where either the cost of O2 or the cost of CH4 may be of controlling importance. This paper presents a treatment of the thermodynamics of the CH4-H2O-H2-CO-CO2-C system, which has been extended to cover solutions of 2 maximum problems not ordinarily dealt with; namely, determination of the conditions of temperature, pressure, and O2:CH4 ratio for maximum yield of synthesis gas per mol. of O2 and per mol of CH4. The numerical calculations have been made with the assumption of isothermal equilibration so that the results are of more value as standards for comparison with actual synthesis-gas units rather than as a basis for the design of such units. The calculations show that the maximum yield of synthesis gas per mol. of CH4 or O2 is favored at high temperatures and low pressures. In addition, the conditions of temperature, pressure, and O2:CH4 ratio necessary to prevent the formation of unburned C is given. It also is shown that the numerical calculations are much simplified if the H2:CO ratio is taken as the independent variable rather than the O2:CH4 ratio. The calculations serve to illustrate the general desirability of effecting equilibration of the combustion gases at high temperatures and low pressures. Relatively long residence time of the gases in contact with catalytic materials at lower temperatures, such as might be encountered in a reactor having a long dropping temperature gradient might be expected to cause deviations from the theoretical compositions. The magnitude of these deviations from the calculated values may be taken as a measure of the extent of re-equilibration occurring. The calculations also show that the point of maximum yield per mol. of CH4 always requires a higher O2:CH4 ratio than the point of maximum yield per mol. of O2. In the preferred high-temperature-low-pressure range, however, these maxima approach each other. The problem of calculating maximum yield per unit cost of reactants is, thus, very much simplified.
MOORE, G. E. See abs. 1729.