The fact that the yield of ch4 only significantly

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Unformatted text preview: ds of CO and H2 the catalytic partial oxidation is best performed at an O2/C3H8 ratio of 1.25 (25% O2 surplus). The results show that not reacted C3H8 does not lead to higher coke formation under the applied reaction conditions or to the deactivation of the catalyst. Slight excess of O2 does not result in a decrease of the coke formation nor to the oxidation of the catalyst, which would result in its deactivation. 4. Results and discussion - catalytic partial oxidation of propane 129 4.4. Influence of space velocity To investigate the influence of space velocity on the catalytic performance tests were carried out at 800°C at gas hourly space velocity (GHSV) of 600, 900 and 1200 dm3· h-1· g(catalyst)-1 using the same feed composition as in the catalytic screening. Here again almost complete O2 conversion was observed as in all experiments. The conversion of C3H8 were always high ( •   EXW KLJKHVW DW *+69  dm3· h-1· g-1(catalyst) (Fig. 41). CO and H2 were the main products, their yields changed only slightly with GHSV. The yield of CO reflected the trend of the conversion of C3H8, whereas the yield of H2 increased steadily with increasing GHSV. Again the yields of H2 were lower than that of CO. Changes in the GHSV had hardly any influence on the yield of CO2, but at GHSV 600 and 900 higher yields of H2O and CH4 were observed than at GHSV of 1200 dm3· h-1· g(catalyst)-1. Small amounts of alkenes C2H4 and C3H6 were observed only in case of the lowest GHSV with yields below 1% for each. Considerable catalyst deactivation was observed only at the lowest GHSV (Fig. 42). The amount of coke formed was always low and decreased with increasing GHSV. 130 4. Results and discussion - catalytic partial oxidation of propane conversion [%] 110 100 O2 C3H8 100 100 99 95 90 88 90 80 600 100 CO 900 1200 H2 90 yield [%] 86 82 78 80 73 69 60 600 H2O 900 CO2 1200 CH4 20 yield [%] 15 13 10 10 2 3 2 3 3 1 0 600 900 1200 GHSV [dm3·h-1·g-1] Fig. 41 Catalytic performance of Ni10C900 for different GHSVs, 800°C, 25% O 2 surplus, TOS 240min relative deactivation rate / h 131 4. Results and discussion - catalytic partial oxidation of propane relative deactivation rate / h 3 1.94 0.40 0 -0.22 -3 wt% coke / g(catalyst) 20.4 20 14.9 11.2 10 0 600 900 1200 GHSV [dm...
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