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Dynamic and steady state analysis of low temperature ethane oxidative dehydrogenation over chromia and chromia-vanadia catalysts

Karamullaoglu, Gulsun
Doğu, Timur
Oxidative dehydrogenation of ethane to ethylene was investigated over Chromia and Cr-V mixed oxide catalysts synthesized following a complexation procedure. With an O-2/C2H6 feed ratio of 0.17, Chromia exhibited a total conversion value of about 0.20 at 447 degrees C (at a space time of 0.24 s.g/mL) with an ethylene selectivity of 0.82. Chromia catalyst was more active than Cr-V mixed oxide at temperatures as low as 200 degrees C. Pulse-response experiments carried out with ethane pulses injected into O-2-He indicated the presence of at least two different sites for the formation of CO2 and H2O over Chromia catalyst. In the dynamic experiments carried out with the Cr-V mixed oxide catalyst and by injecting O-2 pulses into a gas stream containing a mixture of C2H6 and He, formation of CO rather than C2H4 was favored. Results of the dynamic runs carried out without gas phase oxygen strengthened the conclusion of lattice oxygen participation in the selective oxidation of ethane reaction through a redox mechanism.