Oxygenate reforming reactions

Methane reforming with carbon dioxide proceeds in a complex sequence of reaction steps involving the dissociative adsorption/reaction of methane and COj at metal sites. Hydrogen is generated during methane dissociation In the second set of reactions CO2 dissociates into CO and adsorbed oxygen. The reaction between the surface bound carbon (from methane dissociation) and the adsorbed oxygen (from CO2 dissociation ) yields carbon monoxide. A stable catalyst can only be achieved if the two sets of reactions are balanced. 

Autothermal reforming is a combination of SR and POX, which in theory can be totally heat balanced. When air is used instead of pure oxygen, the reaction can be represented by the following equation ... 

Decreasing the oxygen-to-fuel ratio, x, results in increasing demand for water (water-to-fuel ratio), with commensurate increases in the yield and concentration of hydrogen in the reformate gas. When x = 0, the equation reduces to the strongly endothermic steam reforming reaction. 

The reaction becomes less endothermic with increasing oxygen. It becomes thermoneutral" at X = Xo (0.44 for natural gas). Above this point, the reaction becomes increasingly exothermic. At X = 1, the pure POX reaction, the feed contains sufficient oxygen to convert all of the carbon in the fuel to CO2. No water needs to be added. The equation is a mix of the steam reforming reaction and the POX reaction at values of x between 0 and 1. 

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