Return to the Table of Contents
9. REMOVAL OF CO FROM GASES
In the preparation of synthesis gas for the ammonia process the hydrogen is obtained from CO-H mixtures by the shift reaction changing the CO + H2O into CO2 + H2 and then removing the CO2 by water absorption as previously described. However some unreacted CO is carried through and remains in the gas. In the ammonia synthesis carbon monoxide is a catalyst poison and it is therefore necessary to purify the gas to remove the last traces of CO.
This is done by subjecting the gas to direct contact in a counter current absorption tower with a refrigerated copper ammonia carbonate or carbonate solution at 1800 to 3500 pounds per square inch, it having been found that in that pressure range carbon monoxide is readily soluble in a cold ammonia copper salt solution.
A second method of eliminating carbon monoxide by converting it to a hydrocarbon in the Fischer-Tropsch process as a detoxification process is covered in another technical report and is not repeated here.