A Study of Support Effects for the Water-Gas-Shift Reaction over Cu

The water-gas-shift (WGS) reaction was studied on a series of supported Cu catalysts in which the MgAl2O4 (MAO) support was modified by depositing ZnO, CeO2, Mn2O3 and CoO using Atomic Layer Deposition (ALD). Addition of Cu by one ALD cycle gave rise to catalysts with nominally 1-wt% Cu. A 1.1-wt% Cu/MAO catalyst prepared by ALD exhibited twice the dispersion but ten times the WGS activity of a 1-wt% Cu/MAO catalyst prepared by impregnation, implying that the reaction is structure sensitive. However, Cu catalysts prepared with the ZnO, CeO2, and Mn2O3 films showed negligible differences from that of the Cu/MAO catalyst, implying that these oxides did not promote the reaction. Cu catalysts prepared on the CoO film showed a slightly lower activity, possibly due to alloy formation. The implications of these results for the development of better WGS catalysts is discussed.