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The paper reports the results of a kinetic and thermodynamic analysis of non-catalytic partial oxidation of methane and C2–C4 hydrocarbon/hydrogen mixtures (C/H = 1 : 4) at 1400–1700 K. The hydrocarbon conversion sequence and the time periods of the major process stages were identified for isothermal conditions. The initial stage of the oxidative conversion of C2+ hydrocarbons consists of their pyrolysis, primarily into ethylene and propylene, followed by oxidation of the pyrolysis products. In this respect, the kinetics of C2+ hydrocarbon oxidative conversion are different from those of methane conversion, marked by the almost simultaneous and significantly slower occurrence of pyrolysis and oxidation. The subsequent stages involve steam and dry reforming of the oxidation products, namely acetylene and methane; these stages continue until the main products (H2, CO, CO2, and H2O) reach an equilibrium distribution for the given temperature. The study findings are important for the optimization of various techniques for high-temperature syngas production via partial oxidation of C2+ hydrocarbons, as well as Moderate or Intense Low-Oxygen Dilution (MILD) combustion processes. [ABSTRACT FROM AUTHOR]

Commercial processes for conversion of carbon-containing gases to syngas and hydrogen are considered. The techno-economic characteristics of the main hydrocarbon gas conversion processes (steam methane reforming, partial oxidation, autothermal reforming) used by world's leading chemical and petrochemical companies and implemented on the commercial or semicommercial scale are presented. The characteristics of these processes are analyzed. The processes of steam conversion, autothermal reforming, and partial oxidation of methane have specific predominant application fields depending on the feed composition and requirements to the composition of the syngas obtained. The steam conversion can ensure the maximal H2/CO molar ratio in the syngas obtained, and the processes of autothermal reforming and partial oxidation of methane do not require external heat supply to the reactor and are simple in implementation. Analysis of the syngas market shows that the main drivers of its progress can be the need for alternative resources and the stable demand of the chemical industry. [ABSTRACT FROM AUTHOR]

The development of noncatalytic procedures for processing hydrocarbon gases is an important way to increase the efficiency of gas-chemical processes and decrease their power consumption. The paper deals with thermodynamic and kinetic modeling of noncatalytic processes of the partial oxidation and steam and carbon dioxide conversion of methane in the temperature interval 1400–1800 K and with analysis of the process for syngas production by matrix conversion of rich methane–oxygen mixtures. Comparison of the kinetic calculations with the experimental data demonstrated the possibility of applying published models to the description of the matrix conversion of methane. The possibility of developing a highly efficient technology based on noncatalytic partial oxidation of hydrocarbons for the syngas production without СО2 emission into the environment is discussed. [ABSTRACT FROM AUTHOR]

The possibility of using coalbed methane to produce methanol is assessed. Methanol can be obtained from methane both by direct partial oxidation and from synthesis gas formed through the oxidative conversion of methane. Thermodynamic analysis of coalbed methane conversion was carried out to determine the conditions for obtaining synthesis gas with the ratio [H2]/[CO] = 2, which is optimal for methanol production. The system consisting of methane, nitrogen, and oxygen, with different contents of oxygen and water vapor, was considered. The fuel-air equivalence ratio varied in the range from 2 to 4. The optimal conditions for obtaining synthesis gas for the production of methanol is the use of a mixture with an equivalence ratio of at least 4. It has also been shown that the addition of water vapor leads to an increase in the [H2]/[CO] ratio. Direct gas-phase oxidation of methane to methanol opens up the possibility of complex use of coal mining waste, including not only coalbed methane but also a large amount of coal waste accumulated during coal mining and beneficiation. [ABSTRACT FROM AUTHOR]

The paper reports the results of a kinetic modeling and thermodynamic analysis of non-catalytic steam reforming (NCSR) of methane and C2–C4 hydrocarbons at 1400–1800 K. The hydrocarbon-to-syngas conversion sequence and the time periods of the major process steps were identified. The initial step consists of hydrocarbon pyrolysis to acetylene and H2 with essentially no involvement of H2O. Noticeable H2O conversion starts at a significantly later point than thermal hydrocarbon conversion, under the effects of radicals formed from the pyrolysis. The H2O conversion results in the generation of OH● radicals, which subsequently react with acetylene to form CO and H2. The key step in the NCSR of C1–C4 hydrocarbons, as well as in their high-temperature interaction with CO2 (carbon-dioxide conversion) is conversion of the acetylene formed from the hydrocarbon pyrolysis. The study findings are important for the optimization of high-temperature syngas production via partial oxidation of hydrocarbons. [ABSTRACT FROM AUTHOR]

Equilibrium distribution of oxidation products was calculated for the system СН4 + ψО2 → products at 0.5 < ψ < 1.0 and temperature of 900-1700 K, with the existence of phase transitions in the system taken into account. Two regions are conditionally distinguished: I, at ψ > 0.6 and temperatures higher than 1000-1200 K (depending on ψ), when there is no Csolid in the system; and II, if this component is present in the system. The range of working temperatures and values of ψ, at which the matrix conversion process occurs, falls within region I. A nearly 100% conversion of oxygen and methane is reached within this region; there is no Csolid; and CO, H2, CO2, and H2O are products of the partial oxidation of methane in equilibrium. The temperature limits within which the system passes into region II and the formation of the synthesis gas is accompanied by the appearance of soot were determined. Formulas describing the dependence of the yield of oxidation products per mole of converted methane at various ratios between the methane and oxygen concentrations were derived. An expression was obtained on the basis of experimental data, which can be used to approximately calculate to within <6% the most important technological parameter of the matrix conversion process, [H2]/[CO] ratio. [ABSTRACT FROM AUTHOR]