Recent advancements in fuel cell technology have spurred an interest in converting alcohols into hydrogen rich gas streams, on a small scale and up to industrial scale. Such technology enables one to convert a non-toxic liquid to hydrogen to feed fuel cells. There is also an interest in converting alcohol/water mixtures, for example ethanol and water, such as sugar from biomass fermentation, directly into electricity.
Catalytic steam reforming of alcohols is a well-known process for producing a hydrogen rich gas stream. This is particularly useful for providing energy to fuel cells. Reforming is highly endothermic, therefore, requiring significant energy input, by using a portion of the fuel to be converted, to drive the reaction forward. Reforming also requires a relatively long catalyst contact times, on the order of seconds, which requires significant equipment investment.
To produce hydrogen by steam reforming, high temperature heat input is primarily required at two process steps. First, sufficient steam at high temperature and high pressure must be generated for mixing with an alcohol feed gas. Second, the steam reforming of the steam and alcohol mixture must take place at relatively high temperatures and pressures through a bed of solid catalyst. The equipment needed for these two heat transfers at high temperature and high pressure is necessarily quite expensive. The equipment for steam reforming is also costly because it must be adapted to permit the changing of the solid catalyst when the catalyst is spent or poisoned. Heat sources appropriate for the above two process steps are typically provided by fired heaters at high, continuing utility costs, also with high fluegas NOx production consequential to the high temperatures required in the furnace firebox.
The production of hydrogen by partial oxidation, on the other hand, may be considered a desirable alternative to steam reforming, since it overcomes certain problems encountered in the production of hydrogen by steam reforming. Partial oxidation is an exothermic reaction that can be represented by the reaction of, for example, ethanol with oxygen as follows:CH3CH2OH+½O2→2CO+3H2 
As the reaction is exothermic, the expense of providing heat to the reaction is reduced.
However, present limitations to the successful use of partial oxidation of alcohols for the production of hydrogen include the possibilities of flames, carbon formation, excessive or total combustion, and dehydrogenation of the alcohol. Thus, a need exists for a process that overcomes at least some of these problems.
USPTO Backgrounds
USPTO Backgrounds