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A series of co-precipitated cerium-promoted nickel-aluminum catalysts was prepared. The physicochemical properties of the precursors were analyzed by means of various methods including XRF, HT-XRD, TPR, surface area and thermal decomposition as well as porosity measurements. The activity and selectivity of the NiAlCe catalysts in the hydrogenation reaction of canola oil were investigated and the results compared to those for the cerium-free catalyst. Besides improving some physicochemical properties of the precursors, the addition of cerium significantly improved the cis/trans selectivity, yet at the expense of some loss of the activity in case of larger cerium loadings. Upon addition of a relatively low amount of cerium (0.67 wt%) the content of the C18:1 trans fraction decreased by ca. 35 %. Together with the synergistic effect of the hydrogen pressure a significant decrease of the C18:1 trans fraction by ca. 48 % could be achieved. Furthermore, compared to the cerium-free catalyst, the addition of cerium resulted in a slower drop of the C18:1 cis fraction and a slower increase of the C18:0 fraction in time during the hydrogenation process. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]