Effect of alkali cations on the CuZnOAl2O3 low temperature water gas-shift catalyst

Low temperature water gas-shift catalysts containing 1.0% by weight of alkali elements (Li, K, Rb and Cs) were prepared by impregnation of a ternary Cu/ZnO/Al2O3 (CZA) base catalyst. The calcined precursors were characterized by different physical and chemical techniques such as X-ray diffraction, X-ray fluorescence, N2O chemisorption, N2 adsorption at low temperature and X-ray photoelectron spectroscopy. Then these precursors were activated and tested in the low temperature water gas-shift reaction (LT-WGS). It was shown that the K-containing CZA catalyst exhibited the highest CO conversion level at reaction temperature within the range 450–530 K. In addition, the alkali promoters were found to prevent methanol production at temperatures higher than 480 K.