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Unformatted text preview: ifferences between the Ni/Mg ratio of the catalysts and their specific desorption of CO2. In order to see differences in their specific desorption of CO2 prolonged adsorption times and adsorption temperatures up to 200°C were applied. By adsorption at temperatures of at least 150°C the specific desorption of CO2 of the catalysts was found to decrease with increasing Ni/Mg ratio. Transformation of isopropanol and aldol condensation were found to be unsuitable test reactions for the determination of the basicity, due to the dehydrogenation activity of Ni2+ ions in the former and due to the low specific activity of the catalysts at lower temperatures in the latter reaction. The partial oxidation of propane to syngas could be successfully performed at temperatures between 600°C and 900°C over reduced Ni containing catalysts. CO and 5. Conclusions 143 ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp H2 were the main products, H2O, CO2 and CH4 the only considerable side products. The conversion of C3H8 and the yield of syngas increased with increasing reaction temperature. Unreduced Ni exhibited no specific catalytic activity. Of the hydrotalcitetype derived Ni containing catalyst calcined at 900°C, the ones with a low to medium Ni content exhibited better catalytic performance than those with a higher Ni content or the reference catalyst (20 wt% NiO/Al2O3 + 2 wt% K2O). Coking was found to increase with increasing Ni content of the catalysts and to decrease with increasing reaction temperature. As no clear relation was observed between coking and catalyst deactivation it was concluded that different types of coke could be formed over the catalysts of which not all were deactivating. Since several factors characterising the catalysts (BET surface area, Mg content and available Ni surface) follow the same or the opposite trend with the Ni content, so it was impossible to differentiate between these properties and their effect on the catalyst performance or coking. The hydrotalcite-type derived catalyst with...
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