An Introduction to Fuel Reforming

Fuel reforming is described in detail in Chapter 8. It will suffice to say at this stage that the production of hydrogen from a hydrocarbon usually involves steam reforming . In the case of methane, the steam reforming reaction may be written as 

However, the same reaction can be applied to any hydrocarbon C fAy, producing hydrogen and carbon monoxide as before. 

The carbon monoxide prodnced with hydrogen in steam reforming is a potential problem. This is becanse it will poison any platinum catalyst, as used in PEMFCs or PAFCs. With these fnel cells, the reformate gas must be further processed by means of the water-gas shift reaction (nsnally abbreviated to the shift reaction)  

This reaction serves to rednce the CO content of the gas by converting it into CO2. As is explained in Section 8.4.9, this process nsnally needs two stages, at different temperatures, to achieve CO levels low enough for PAFC systems. 

A further complication is that fnels snch as natural gas nearly always contain small amonnts of snlphnr or snlphnr componnds that must be removed. Sulphur is a well-known catalyst poison and will also deactivate the electrodes of aU types of fuel cells. Therefore, sulphur has to be removed before the fuel gas is passed to the reformer or stack. Desulphurisation is a well-established process that is required in many situations, not jnst for fnel cells. The process is also described in more detail in Chapter 8. At this stage it is snffident to know that the fuel must be heated to about 350°C before entering the desulphuriser, which can be considered as a black box for the moment. 

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