Stability of La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3{minus}{delta}} perovskite membranes in reducing and nonreducing environments
- Washington State Univ., Pullman, WA (United States). Dept. of Chemical Engineering
The chemical stability of perovskite La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3{minus}{delta}} (LSCF-6428) has been investigated in connection with its potential use as a catalytic membrane for the oxidative coupling of methane (OCM). Once a steady-state oxygen-defect gradient is established (15--20 h), these membranes are found to be very stable under air/nitrogen gradients at temperatures up to 960 C and they respond instantaneously to temperature changes with an apparent activation energy of 159 kJ/mol. However, serious near-surface etching occurs when one side of the membrane is exposed to 100% CH{sub 4} at 850 C and atmospheric pressure, which resulted in dramatic increases in oxygen flux (a factor of 5). While this also caused an increase in the OCM reaction rate, the selectivity of C{sub 2+} hydrocarbons fell from 40 to 10%. It is also shown that stable operation under OCM conditions is possible if CH{sub 4} pressures are reduced to 0.1 atm but at a cost of C{sub 2+} production rate.
- OSTI ID:
- 624321
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 37, Issue 4; Other Information: PBD: Apr 1998
- Country of Publication:
- United States
- Language:
- English
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