Modification of the Copper-Manganese Catalyst by Fe, Cr, Ni, and Ga for Low-Temperature CO Oxidation

The effect is studied of modifying dopants M = Fe, Cr, Ni, and Ga on the physicochemical and catalytic properties of copper-manganese catalysts for low-temperature CO oxidation under dry and wet reaction conditions. By means of X-ray diffraction and X-ray photoelectron spectroscopy the phase compositions and structural bulk characteristics of all catalysts before and after tests, as well as their surface compositions and states, are determined and compared. The catalysts are modified at the stage of preparing CuMn1–xMxO2 nanocrystallites of the crednerite structure type with partial substitution at manganese positions. The final catalyst is obtained directly under the reaction conditions by pre-treatment at 350 °C that results in the phase transition of crednerite particles to cubic spinel structure (Cu,Mn,M)3O4. It is found that under dry conditions only nickel and gallium modifications substantially increase the specific rate of low-temperature CO oxidation whereas in the presence of water vapor, all CuMn catalysts studied are deactivated regardless of the nature of the modifying dopant.