Their yield was higher at o2c3h8 ratio 075 than at

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: se conditions the catalyst needed longer time to reach a stable steady state. The tendency for coke formation was in all cases low. 126 4. Results and discussion - catalytic partial oxidation of propane O2 conversion [%] 110 C3H8 100 99 99 100 95 99 90 71 70 58 50 0.75 yield [%] 100 CO 1.00 1.25 H2 1.50 91 90 80 73 64 60 61 57 50 48 40 0.75 yield [%] 40 H2O 1.00 CO2 1.25 1.50 CH4 37 30 20 15 7 10 1 1 3 2 2 2 3 7 1 0 0.75 1.00 1.25 1.50 O2/C3H8 ratio Fig. 39 Catalytic performance of Ni10C900 for different O2/C3H8 ratios (1.00 = stoichiometric ratio), 800°C, 25% O2 surplus, GHSV 900dm3·h-1·g-1, TOS 240 min 127 4. Results and discussion - catalytic partial oxidation of propane relative deactivation rate / h 5 0.1 0 -0.2 -2.3 -5 -3.8 wt% coke / g(catalyst) 15.6 14.9 15 10 13.5 8.3 5 0 0.75 1.00 1.25 1.50 O2/C3H8 ratio Fig. 40 Coking and deactivation of Ni10C900 for different O2/C3H8 ratios (1.00 = stoichiometric ratio), 800°C, GHSV 900dm3·h-1·g-1, TOS 240min 4. Results and discussion - catalytic partial oxidation of propane 128 These results show that under the chosen reaction condition high C3H8 conversion is only possible under O2 excess in the feed stream because part of the O2 leads always to total combustion products, CO 2 and especially H2O. Their amount increases with increasing O2 content of the feed. After total C3H8 conversion is achieved excess O2 leads to a sharp increase in total combustion products, but also almost to the disappearance of CH4 in the product mixture. The observed decrease of the amount of alkenes in the product mixture with increasing O2/C3H8 ratio may be attributed to the higher overall C3H8 conversion or the complete conversion of the formed alkenes at higher O2/C3H8 ratio. The fact that the yield of CH4 only significantly decreases after total C3H8 conversion is reached does not necessarily mean that cracking is significantly influenced by the O2 content of the feed, because excess O2 should lead to an increase in the conversion of formed CH 4. Judging from the yiel...
View Full Document

This document was uploaded on 10/07/2013.

Ask a homework question - tutors are online