It is a process which reduce hydrogen consumption of the methanation system, as well as the inert gas content of the purified synthesis gas fed to the synthesis loop. After low-temperature shift conversion, the cooled raw gas is mixed with the stoichiometric quantity of air or oxygen needed to convert the carbon monoxide to carbon dioxide. The mixture is then passed through a precious-metal catalyst at 40 - 135 "C to accomplish this selective oxidation. The carbon dioxide formed by the Selectoxo reaction adds only slightly to the load on the downstream
carbon dioxide absorption system.