Return to the process flow of the fuel processing system
Because the cell performance lowered with existence of carbon monoxide (CO), the concentration of CO produced in the reformer has to be reduced.
- Carbon monoxide (CO) and steam (H2O) further reacts on a catalyst (Cu-Zn-based, Fe-Cr-based, or Pt-based)., and hydrogen (H2) and carbon dioxide (CO2) are produced.
CO shift reaction
- The concentration of CO is lowered usually by using two stages, high-temperature shift reactor and a low-temperature shift reactor.
In the first stage, a concentration of tens of percent of carbon monoxide is lowered to a concentration of several percent in a high-temperature shift reactor (350 to 420˚C); in the second stage, the reaction temperature is lowered to about 200˚C to reduce the concentration of CO at the outlet down to 0.5 to 1%.
- By improving heat resistance characterlistics, this catalyst (Cu-Zn-based) can be used across a wide temperature range of 200 to 350˚C.
This makes it possible to reduce CO concentration with a single type of catalyst under various temperature conditions; this enables to make a compact and simple reactor design.