As mentioned above, one possibility of operation with a more favorable energetic balance is under autothermal steam reforming conditions, which are produced by introducing oxygen in the reaction mixture. As has occurred for hydrocarbons and methanol feedstock [5,51], research is now under way to develop catalysts that control the oxidation process through the combining of catalytic partial oxidation and steam reforming of ethanol. The oxidizing environment reduces the carbon poisoning of the catalyst and could promote the decomposition of intermediate molecules such as ethylene and acetaldehyde. On the other hand, an excess of oxygen leads to a strong reduction of hydrogen as reaction product. In this respect, studies under partial oxidation conditions could contribute to a better knowledge of autothermal ethanol steam reforming. Some studies on cat­alytic behavior of Ni- [52], Pt — [53] and Ru-based [54] catalysts have recently been reported.

In autothermal conditions, reports concerned the use of Ni and Cu catalysts [38-40,55] and promoted noble metals supported on highly stable carriers, i. e., Pt-CeO2-La2O3/Al2O3 [13], Rh/CeO2 [14], Rh/Al2O3 [56]. The main role of pro­moters is related in this case to metal-promoter interactions [13], which affect the adsorption-decomposition of ethanol to CH4 and CO and their subsequent reforming with steam to produce H2. Most of the results reported point to the need to operate in a narrow range of water/oxygen/ethanol ratios to achieve 100% ethanol conversion, maximum hydrogen yield and minimum methane and carbon monoxide production.