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Catalysts containing transition metals like nickel are frequently used in technical hydrogenation reactions. Typically their activity and selectivity are determined via metal dispersion. XRD, H 2 TPD, volumetric chemisorption of H 2 and CO pulse chemisorption were applied to determine the Ni crystallite size of Ni-containing catalysts. The methods were compared with regard to their information content and validity as well as their applicability in quality control during industrial manufacturing of catalysts. Pulse chemisorption of CO showed the best results for utilization in quality control. ProblemNi-containing catalysts are used in various technical hydrogenations such as saturation of aromatics [1 -3], hydrogenation of aldehydes [4,5], hydrogenation of nitroaromatics [6] and hydrogenation of nitriles [7]. The activity and selectivity of these catalysts are mostly determined by the metal dispersion. Therefore, reliable methods for determination of the metal dispersion are required for the development of new catalysts and for quality control of catalysts manufactured in industrial scale. Numerous methods for determining the dispersion of nickel on supports are described in the literature. The most common method is the chemisorption of gases, whereby mainly hydrogen and carbon monoxide are used. The chemisorption can be carried out as a volumetricstatic method [8 -18], as a thermal desorption method [18, 21 -27] or as a pulse-flow method [21, 22, 28 -32] but also gravimetric [33] or calorimetric analyses [34] are applied. Furthermore X-ray diffraction [9 -11, 13 -15, 19, 32, 35, 36], transmission electron microscopy [10 -12, 28] and magnetic methods [37,38] are used for the determination of the Ni dispersion.The aim of this study is to compare different methods with regard to their information content and validity as well as their applicability in quality control during industrial manufacturing of catalysts. These methods are in particular the volumetric-static chemisorption and thermal desorption of H 2 , the pulse chemisorption of CO and the X-ray diffraction on Ni/Al 2 O 3 -, Ni/SiO 2 -and Ni/ZrO 2 /SiO 2 catalysts. Experimental Catalyst PreparationNi/Al 2 O 3 catalysts were prepared by incipient wetness impregnation of extrudated theta-alumina with an aqueous nickel amine carbonate complex solution. After the impregnation the intermediate was dried at 120°C for 12 h and calcined at 330°C for 4 h. For the preparation of Ni/alumina catalyst with Ni content of 17 wt-% a second impregnation of the dried and calcined intermediate has been carried out by using a solution with the same nickel content. The preparation of the catalyst with a Ni content of 24 wt-% was done by carrying out three impregnation steps, while a Ni content of 28 wt-% was reached with four impregnation steps. After the calcination 200 mL of the catalyst precursor were heated up with a rate of 5°C min -1 to 450°C by using H 2 (space velocity of 2000 L gas L cat -1 h -1) followed by a 6-h hold at 450°C. After cooling down to ambient temperat...

Nickel catalysts supported on ZrO2, TiO2 and ZrO2/TiO2 mixtures performed more active, selective and stable than Ni/SiO2 catalysts in the hydrogenation of glucose to sorbitol. This was shown by catalytic testing as well as by determination of Ni crystallite size before and after the test. The reason for the better performance was assumed to be metal‐support interaction in the Ni/ZrO2, Ni/TiO2 and Ni/ZrO2/TiO2 catalysts.

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