Homogeneous catalysis of the water gas shift reaction using iron pentacarbonyl

Measurements have been carried out to determine the rate of hydrogen production by the water gas shift reaction (CO + H/sub 2/O ..-->.. CO/sub 2/ + H/sub 2/) operating at temperatures less than 200/sup 0/C with iron pentacarbonyl serving as a catalyst precursor in a basic methanol-water solution. Turnover numbers of 2000 mol H/sub 2//mol Fe(CO)/sub 5/ per day are achieved at 180/sup 0/C with this system. The reaction is shown to be zero order with respect to carbon monoxide. The temperature dependence of this reaction corresponds to an activation energy of 22 kcal/mol. It is shown that a threshold pressure of carbon monoxide exists above which the catalytic reduction of water can be sustained. Below this pressure, the Fe(CO)/sub 5/ is destroyed in a stoichiometric reduction of water. The overall kinetics of this reaction as well as this threshold phenomenon can be explained according to previously published mechanisms.