The effect of the precursor ageing on properties of the Cu/ZnO/Al2O3 catalyst for low temperature water–gas shift (LT-WGS)

• Effect of the CuZnAl hydroxycarbonate precursor ageing time.
• Decreasing surface area and activity as a result of the precursor recrystallization.
• Copper surface area correlates with stable carbonates HT-CO32− content.
• TOF virtually constant, no influence of ageing time.

The effect of the precursor ageing time on the structure, thermal decomposition, specific surface area, active copper surface area as well as on the morphology of the precursors and catalysts oxide forms was investigated. The hydroxycarbonate precursor, with the composition corresponding to industrial catalysts, was prepared via coprecipitation method from the solutions of copper and zinc nitrate with a mixture of sodium aluminate and sodium carbonate at pH = 7.4 and then aged in the mother liquor. The activity of the prepared catalysts in the LT-WGS reaction was compared under conditions similar to those in the industrial process. The results reveal that the precursor ageing influences the precursor phase composition, the active copper surface area and the catalytic activity. The activity decreases with the increasing ageing period but the activity concerned a single surface copper atom (TOF) is constant and independent of the ageing time.

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