CO 2 reduction and methane partial oxidation on surface catalyzed La 0.9 Ca 0.1 FeO 3-δ oxygen transport membranes

Type
Article

Authors
Wu, Xiao-Yu
Ghoniem, Ahmed F.

Online Publication Date
2018-06-21

Print Publication Date
2018-06

Date
2018-06-21

Abstract
In this paper, we demonstrate CO2 thermochemical reduction to CO in a La0.9Ca0.1FeO3-δ oxygen ion transport membrane reactor. For process intensification, we also show that methane can be used on the sweep side, producing two streams: a CO stream from CO2 reduction on the feed side, and a syngas stream on the other. We show that surface reactions are the rate-limiting steps for fuel-assisted CO2 reduction on a flat LCF-91 membrane. To improve productivity, we study how that adding catalytic porous layers can accelerate these steps and hence, increase the CO2-to-fuel conversion rates. Adding LCF-91 porous layers onto the membrane surface raised the oxygen flux by 1.4X. Secondly, different catalysts (Ce0.5Zr0.5O2 on the feed side and (La0.6Sr0.4)0.95Co0.2Fe0.8O3 on the sweep side) were added onto the porous layers to further accelerate the surface reaction rates. As a result, the oxygen flux was further increased especially at lower temperatures, e.g., at 850°C, oxygen flux was raised by one order of magnitude as compared to the unmodified membrane. Process intensification was tested on the latter membrane configuration, and the syngas produced on the sweep side had a H2:CO ratio very close to 2, ideal for production of fuels. Carbon species balance showed that higher methane concentration on the sweep side could lead to coke formation. Results also show that the selectivity to CO2 near the membrane surface is higher than that at the reactor outlet due to the availability of lattice oxygen and the favorable water-gas shift reactions.

Citation
Wu X-Y, Ghoniem AF (2018) CO 2 reduction and methane partial oxidation on surface catalyzed La 0.9 Ca 0.1 FeO 3-δ oxygen transport membranes. Proceedings of the Combustion Institute. Available: http://dx.doi.org/10.1016/j.proci.2018.05.164.

Acknowledgements
The authors would like to thank Exelon Corporation, Shell and King Abdullah University of Science and Technology (KAUST) for funding the research.

Publisher
Elsevier BV

Journal
Proceedings of the Combustion Institute

DOI
10.1016/j.proci.2018.05.164

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