Influence of Soot Particles on the Gas-Phase Methane Conversion into Synthesis Gas: The Role of H2O and CO2 Additives

The influence of the formation of microheterogeneous soot particles on the gas-phase conversion of rich mixtures of methane with oxygen into synthesis gas in a temperature range from 1500 to 1800 K under the conditions of an adiabatic reactor was studied by kinetic modeling. The effect of CO₂ and H₂O additives on this process was studied. The appearance of soot particles was observed in rich mixtures, starting from the fuel excess factor ϕ = 3.33. At relatively low temperatures of ~1500 K, a small amount of microheterogeneous soot particles was formed, which did not significantly affect other components of the reacting system. A noticeable effect of soot particles at this temperature was observed at a higher value of ϕ = 8.0. This was most clearly manifested in the temperature profile of the process, in which two maximums were observed at times of about 0.01 and 0.1 s upon the addition of water to the reacting mixture. In the case of CO₂ additions, the second maximum in the temperature profile was almost not pronounced. A complex temperature profile led to the appearance of the second concentration maximum of hydroxyl radicals OH at times of ~0.1 s. The addition of H₂O and CO₂ made it possible to vary the H₂/CO ratio in the synthesis gas over a wide range, which is necessary for the synthesis of various products. Because the added CO₂ under these conditions was actually involved in the chemical process of obtaining synthesis gas, its partial recirculation from the conversion products made it possible to reduce its emission in the production of synthesis gas.