Ceramic membranes for generation of partial-oxidation products from methane
- Argonne National Lab., IL (United States)
The most significant cost associated with partial oxidation of methane to syngas is that of the oxygen plant. In this paper, we offer a technology, based on dense ceramic membranes, that uses air as the oxidant for methane-conversion reactions and eliminates the need for an oxygen plant. Certain ceramic materials exhibit both electronic and ionic conductivities (of particular interest is oxygen-ion conductivity). These materials transport not only oxygen ions (functioning as selective oxygen separators) but also electrons back from the reactor side to the oxygen-reduction interface. As such, no external electrodes are required and if the driving potential of transport is sufficient, the partial oxidation reactions should be spontaneous. Such a system will operate without an externally applied potential. Oxygen is transported across the ceramic material in the form of oxygen anions and not oxygen molecules. Recent reports in the literature suggest that ceramic membranes made of these mixed conductors can successfully separate oxygen and nitrogen at flux rates that could be considered commercially feasible [1--8]. Long tubes of La-Sr-Fe-Co-O (SFC) membrane have been fabricated by plastic extrusion. Thermodynamic stability of the tubes was studied as a function of oxygen partial pressure by high-temperature XRD. Mechanical properties were measured and found to be adequate for a reactor material. Performance of the membrane strongly depended on the stoichiometry of the material. Fracture of certain SFC tubes was the consequence of an oxygen gradient that introduced a volumetric lattice difference between the inner and outer walls. However, tubes made with a particular stoichiometry (SFC-2) provided methane-conversion efficiencies of >99% in a reactor. Some of these reactor tubes have operated for up to {approx}500 h.
- Research Organization:
- Argonne National Lab., IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10165841
- Report Number(s):
- ANL/ET/CP-82796; CONF-940813-13; ON: DE94015075
- Resource Relation:
- Conference: 208. American Chemical Society (ACS) national meeting,Washington, DC (United States),21-26 Aug 1994; Other Information: PBD: May 1994
- Country of Publication:
- United States
- Language:
- English
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