Deactivation Behaviour of Nickel Catalysts used for Internal Reforming in Molten Carbonate Fuel Cells

The Molten Carbonate Fuel Cell (MCFC) is approaching its commercialization. The MCFC operates at about 923 K and requires hydrogen as fuel; the hydrogen is usually obtained from natural gas or naphtha by steam reforming from a separate unit (external reforming). Another possible source of hydrogen is the reforming of natural gas within the fuel cell (internal reforming). The catalyst particles may then be positioned in the anode gas compartment within the corrugations of the plate separating the anode from the cathode of the next cell of the stack. Internal reforming has attracted considerable attention because it offers several extra advantages in comparison with external reforming. Because the predominating deactivation mechanism under MCFC conditions is still not clear and mechanisms other than reaction of the support with alkali may be more important, it cannot be concluded that nickel catalysts based on supports not having a high resistance to alkalis do not have better stabilities. With the intention of comparing the resistances of several types of nickel catalysts against sintering and thus of obtaining an impression of the catalysts most suitable for internal reforming in the MCFC, the stabilities of different types of nickel catalysts at elevated temperatures in an atmosphere containing alkali hydroxide vapor and steam have been determined. The deactivated catalysts are characterized by several techniques.