The Cu-Fe mixed oxide catalysts with different Cu:Fe mass ratios were prepared by a solution technique.
The catalysts were characterized by Ar physisorption, PXRD, TPD-MS, SEM-EDX and were tested for the CO-PROX
reaction. According to PXRD and SEM-EDX microanalysis data, the active Cu-Fe mixed oxide catalysts, where the
Cu:Fe mass ratio ranges from 1:1 to 1:5.67, contain the delafossite CuFeO2 phase, which is formed at the pretreatment
stage in the gas mixture used for the CO-PROX reaction. The Cu-Fe mixed oxide catalyst with the mass ratio of
Cu:Fe = 1:3 showed 100% CO conversion at 408 K and the low H2 conversion (4 %) at this temperature, giving >80 % selectivity
to CO oxidation. The blocking of the active sites at the catalyst surface by water, which is detected with TPDMS,
could explain the high selectivity to CO oxidation.