Methane combustion with oxygen

Methane combusts with oxygen to yield carbon dioxide and water vapor ... 

In a trivial application of this method, one could consider the synthesis of carbon dioxide from methane as a combustion synthesis. This trivial example provides some framework for additional insights into the solid-state case. The balanced reaction for methane reacting with oxygen is... 

The only hydrocarbon produced directly from natural gas (methane) is acetylene (world production 1998 about 120000ta , Talbiersky, 2006). Production is based on partial oxidation where about one-third of natural gas (methane) is converted into acetylene, while the rest is burned to reach a temperature of about 1500 °C. The entire process only takes a few milliseconds. Acetylene is also produced in arc furnaces. Up to the 1960s, acetylene was an important intermediate, but nowadays its relevance is small compared to olefins such as ethylene and propylene. Today, the most important product from acetylene is 1,4-butandiol, which is used for production of polyurethane and polyester plastics. Acetylene is also used for gas welding, as combustion with oxygen produces a flame of over 3000 °C. 

Methane is partially combusted with oxygen according to the following reaction ... 

Reaction with oxygen occurs during combustion in an engine or furnace when the alkane is used as a fuel. Carbon dioxide and water are formed as products, and a large amount of heat is released. For example, methane (natural gas) reacts with oxygen according to the equation... 

Every chemical reaction is accompanied by the transfer of energy as heat. For example, complete reaction with oxygen is called combustion and the combustion of methane, the major component of natural gas, is the following reaction ... 

Let us simplify and look at the combustion of the simplest hydrocarbon, methane. CH4 reacts with oxygen according to... 

The aim of the present work was to design and operate an apparatus in which stationary combustion and flames can be produced and sustained to pressures of 2000 bar and with environmental temperatures up to 500°C. Visual observation of the interior of the reaction vessel should be possible. Arrangements had to be made by which a gas flow of only a few microlitres per second could be fed steadily into the reaction vessel at pressures to two kilobar. A similar provision was necessary to extract small samples for product analysis at constant conditions. The principle of design and operation will be described. First results will be given for experiments with oxygen introduced into supercritical water-methane mixtures. 

The concept behind combustion is straightforward - when a hydrocarbon fuel reacts with oxygen, the organic component is eventually converted to carbon dioxide and water - but the reality is more complicated. For instance, the combustion of methane (Reaction 1) is often used to teach students how to balance reaction equations ... 

Another related problem is associated with over-oxidation of the substrate, in the extreme case resulting in complete combustion. In the case of methane oxidation by FeO", for example, the activation of methane occurs with about 10% of the gas-kinetic collision rate, whereas those of the putative oxygenation products CH3OH, CH2O, and HCOOH occur on every collision [60]. With regard to applied catalysis this would imply that the oxidation products are oxidized faster by about one order of magnitude compared to methane as the initial substrate. In the particular context of heterogeneous oxidation... 

The stoichiometry of the partial combustion of methane with oxygen can be expressed as the sum of four reactions ... 

The first phase described occurs very close to the burner tip, and it has not been possible either to sample the gas accurately or measure the temperature at this point. However, indirect measurements, with well designed burners, have indicated a flame burst temperature in the range of 3200° to 3600° F. with roughly 40% of the methane unconverted when oxygen consumption is complete. With poorly designed burners, the overburning in the first phase can, of course, become intolerable the worst conceivable case is the complete combustion of approximately one fourth of the methane. 

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