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.

Figure optionsDownload high-quality image (89 K)Download as PowerPoint slideHighlights
► Alkali promoters were efficient in preventing methanol production at T > 480 K.
► H2 selectivity was higher than 96% in the range of 450–530 K.
► Cu/ZnO/Al2O3-K showed the highest CO conversion within the temperature range.
► Copper metallic area decreased slightly upon incorporation of the alkali promoter.