TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: Feeding the O2containing gas through the porous or perforated wall orifices comprises applying a pressure differential between the partial oxidation zones and the oxidant inlets. The gas effluent temperature of at least one of the multitude of partial oxidation zones is controlled by measuring the gas effluent temperature of one partial oxidation zone; comparing the measured gas effluent temperature to a desirable gas effluent temperature setpoint of less than or equal to1300degreesC; and adjusting the O2 mass flow of the O2-containing gas to the oxidant gas inlet feeding the partial oxidation zone, such as to deliver an amount of O2 to the partial oxidation zone suitable to obtain a gas effluent temperature that approaches the desirable gas effluent temperature setpoint. Adjusting the O2 mass flow of the O2-containing gas is performed by adjusting the flow rate of the O2-containing gas through the oxidant gas inlet, by adjusting the O2 content of the O2-containing gas, and/or by adjusting the pressure of the O2-containing gas. The measured gas effluent temperature is lower than the desirable gas effluent temperature setpoint, and adjusting the O2 mass flow of the O2-containing gas comprises increasing the amount of O2 fed to the partial oxidation zone. The measured gas effluent temperature is higher than the desirable gas effluent temperature setpoint, and adjusting the O2 mass flow of the oxygen-containing gas comprises decreasing the amount of oxygen fed to the partial oxidation zone.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The catalyst further rare-earth metal oxide. Preferred Composition: The effluent gas from at least one of the multitude of partial oxidation zone has an O2 content less than or equal to1000 ppm.    TECHNOLOGY FOCUS - METALLURGY - Preferred Component: The multitude of partial oxidation zones comprises one or more catalysts comprising at least one metal from Groups 8, 9, or 10 of the periodic table. The catalyst comprises rhodium, iridium, and/or ruthenium. The catalyst further comprises a rare-earth metal comprising samarium, ytterbium, praseodymium, neodymium, and/or lanthanum.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The hydrocarbon gas comprises methane or natural gas. Preferred Composition: The hydrocarbon gas and the O2-containing gas are fed in such as manner so as to obtain a molar ratio of O2-to-carbon lower than 0.5 but greater than 0.1. The hydrocarbon gas when in contact with the O2-containing gas has a molar ratio of O2-to-carbon corresponding to a pre-ignition point, and the hydrocarbon gas and the O2-containing gas are fed in such as manner so as to obtain a molar ratio of O2-to-carbon less than the pre-ignition point. ACTIVITY - MECHANICAL ENGINEERING - Preferred Component: The reactor system further comprises an interbed region between one partial oxidation zone and the partial oxidation zone immediately upstream. The reactor system further comprises a gas distribution system located in the interbed region and the distribution is suitable for distributing an amount of the O2-containing gas. The gas distribution system is further suitable for distributing the effluent gas from the partial oxidation zone immediately upstream. The distribution system comprises at least one nozzle and/or at least one sparger. The multitude of partial oxidation zones comprises one upstream partial oxidation zone and one downstream partial oxidation zone, and the downstream partial oxidation zone has a greater volume than the upstream partial oxidation zone. The multitude of partial oxidation zones comprises a porous or perforated wall. The porous or perforated wall comprises orifices, and the multitude of oxidant inlets comprises the orifices. The multitude of partial oxidation zones comprises a gas phase. The apparatus comprises oxidant gas inlets and oxygen chambers, where each of the oxidant gas inlets is in fluid communication with one oxygen chamber. Preferred Parameter: Each gas effluent has a gas temperature less than 1100degreesC. Each of the partial oxidation zones has a gas temperature less than 1300degreesC.