Superior Hexagonal Materials for Gas Separation and Oxygen Storage

Northern Illinois University
posted on 05/11/2011

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Ceramic materials have been increasingly researched due to their unique properties of reversible oxygen storage/release capacities (OSC) at elevated-temperatures. The formula of this novel ceramic material consists of transition metal elements that are bi-pyramidal-coordinated to oxygen and rare earth ions, when combined behave like an “oxygen sponge”. Just as a sponge can absorb and release water under different pressures, these materials can absorb and release oxygen when exposed to different temperatures or gases. This property enables novel separation of the major components of air in the atmosphere, oxygen and nitrogen, by storing the oxygen in the ceramic materials and leaving nitrogen in the atmosphere.

Oxygen production by thermal swing absorption for oxy-fuel “clean coal” power plants; automotive exhaust catalysts; H2-O2 fuel cells; solar water splitting methods; steel, copper, and plastic production and other industrial production processes which require high-purity oxygen and have large amounts of waste heat. Chemical-looping by oxygen pressure swing absorption for efficient and pollutant-free combustion and fuels reforming.

The novel hexagonal ceramic materials selectively absorb and release oxygen with near 100% selectivity while not absorbing other gases. Unlike other oxygen storage materials, which depend on the creation of oxygen ion vacancies at high-temperatures, this system rely on phase change due to oxygen filling/discharge of the interstitial sites. Material has been shown to have higher OSC than current commercial ceramic materials, while operating at lower temperatures and with a smaller necessary temperature gradient as well as exhibits faster oxygen absorption/desorption rates compared to the prior art. Material is also stable under highly reducing conditions of H2 and CO.