Evaluation of Copper–Aluminum Oxides as Sorbents for High-Temperature Air Separation
2014
Alipour, Mehdi | Nychka, John A. | Gupta, Rajender
Oxygen production in an economic way is critical to oxy-firing combustion, a carbon capture technology. Oxygen-deficient oxides have been used for absorption of oxygen from air and desorption of oxygen in recycled flue gas for oxy-firing combustion. Cuprous/cupric oxide equilibrium with alumina can be used as an alternative for oxygen production and absorption. In this work, the effect of the spinel phase (CuAl₂O₄) content on oxygen sorptive/desorptive properties of CuO–CuAl₂O₄ sorbents has been investigated using thermogravimetric analysis. The desorption rate and oxygen sorption capacity were shown to be dependent upon the amount of alumina addition. The effect of SO₂ and H₂O in flue gas was investigated using FACTSage over a range of conditions. It was found that, at temperatures above 750 °C, CuO is inert to these species, making it a proper choice for oxygen carrier. Cyclic stability was also investigated using the same instrument. The molar CuAl₂O₄ content of 20% was observed to have the most positive cyclic stability effect. A stable morphology was observed in the scanning electron microscopy microstructure of the sorbent with this CuAl₂O₄ content. Sintering at a lower CuAl₂O₄ content and attrition because of second-phase agglomeration can destabilize the sorbents.
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