Plug-Flow Reactor Study of the Partial Oxidation of Methane and Natural Gas at Ultra-Rich Conditions

The homogeneous partial oxidation of fuel-rich CH4/O-2, CH4/C2H6/C3H8/O-2 as well as CH4/C2H6/C3H8/H-2/O-2 mixtures is investigated in a plug-flow reactor at intermediate temperatures (473T973K) and a pressure of 6bar. Experiments are carried out at equivalence ratios (phi) of 2, 10, and 20. Product species are analyzed using time-of-flight molecular-beam mass spectrometry. The experimental results are further compared with kinetic simulations. It was found that under the investigated conditions, the onset temperature for CH4 oxidation is above 773K. The highest methane conversion at equivalence ratios of 10 and 20 was between 0-3% for neat methane as fuel and 10-13% for natural gas as fuel. The conversions yield useful chemicals like synthesis gas (H-2/CO), C2H4, C2H6, or C3H6. Higher CH4 conversion in the natural gas mixtures results in much higher yields of all products. The natural gas components ethane and propane do not influence the reaction onset temperature.