The catalysts at temperature 800c exhibited partial

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Unformatted text preview: , as it was originally planned to compare all catalysts including Ni10C700 at one common reaction temperature while fulfilling the reaction temperature criteria, maximal reaction temperature was by 100°C 4. Results and discussion - catalytic partial oxidation of propane 134 ppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppppp lower than the calcination temperature and catalytic tests were performed at temperatures as low as 600°C. The catalytic tests were performed under the same conditions as the catalytic screening. The reduction temperature was normally 100°C lower than the calcination temperature. The catalyst Ni10C800 used for the catalytic tests at 800°C was reduced at 800°C, in order to avoid possible ongoing reduction during the reaction performed at 800°C. However, due to the exothermal reactions the temperature increased at the start of the reaction by 70°C, a typical value for the reaction at 800°C. Although the temperature rise was immediately counteracted by reducing the heating power of the furnace, it needed some time to cool down to 800°C, therefore one cannot exclude structural changes in the catalyst. Starting the reaction at lower reaction temperature was not attempted as it could influence the coking of the catalyst and therefore its catalytic behaviour. Therefore this particular experiment was not repeated. It is also noteworthy that only when the reaction was performed at 900°C a temperature decrease of about 20°C was observed at the beginning of the reaction. Over the catalysts Ni10C900 and Ni10C1000 very similar results were obtained in their common reaction temperature region (600-800°C), at 700°C almost identical conversions and yields were observed, the difference was ≤ 2%. At all temperatures over these two catalysts the O2 conversion was always almost complete. The C3H8 conversion increased with increasing reaction. At 900°C over Ni10C1000 even complete C3H8 conversion was observed. Somewhat different results were observed over the catalyst Ni10C8...
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This document was uploaded on 10/07/2013.

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