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The observation that the tendency towards coking

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Unformatted text preview: process consist the Mg containing catalysts of metallic Ni particles in a MgO matrix and of spinel phases. The catalyst Ni72C900 in contrast consists only of metallic Ni and Al2O3 particles. Therefore any correlation of the catalysts’ properties in terms of basicity, surface area, Ni dispersion (and linked to it the total Ni surface) should be done only for the Ni and Mg containing catalysts as they have the same structural patterns. The catalyst Ni5C900 should be ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp 4. Results and discussion - catalytic partial oxidation of propane 116 ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp excluded as here partial reconstruction of the former HT structure was observed after calcination. The catalysts’ surface area, basicity and both decrease with increasing Ni/Mg ratio of the catalyst, the dispersion of the catalysts Ni10C900, Ni15C900 and Ni30C900 is similar, hence their amount of surface Ni increases with increasing Ni/Mg ratio of the catalyst. As these properties show the same or the reverse trend is impossible to determine the influence of the single properties on the stability, the coke resistance or the catalytic performance. 4.2. Catalytic tests of different configurations 4.2.1. Blank experiments In order to study the influence of the reduced Ni on the performance of the studied catalysts blank experiments were performed using the empty reactor (homogeneous reaction), quartz wool bed only, the Ni free catalyst and Ni10C900 without previous reduction. The same conditions as in the catalytic screening were applied. Ni10C900 was not only chosen because it was the most successful one, but also because it is the catalyst from the first set of catalysts that is most difficult to reduce and therefore least likely to be reduced by the reaction mixture. In the experiments carried out with an empty reactor or SiO2 wool 1000°C was set as the upper temperature limit to avoid damaging the furnace and 600°C as the lower temperature limit as here the conversions were almost zero. Over the catalysts again 800°C was set a...
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