Abstract
This investigation demonstrates the feasibility to fabricate high quality ceramic-carbonate membranes based on mixed-conducting ceramics. Specifically, it is reported the simultaneous CO2/O2 permeation and stability properties of membranes constituted by a combination of ceramic and carbonate phases, wherein the microstructure of the ceramic part is composed, in turn, of a mixture of fluorite and perovskite phases. These ceramics showed ionic and electronic conduction, and at the operation temperature, the carbonate phase of the membranes is in liquid state, which allows the transport of rm{CO}_3^{2-} and O2− species via different mechanisms. To fabricate the membranes, the ceramic powders were uniaxially pressed in a disk shape. Then, an incipient sintering treatment was carried out in such a way that a highly porous ceramic was obtained. Afterwards, the piece is densified by the infiltration of molten carbonate. Characterization of the membranes was accomplished by SEM, XRD, and gas permeation techniques among others. Thermal and chemical stability under an atmosphere rich in CO2 was evaluated. CO2/O2 permeation and long-term stability measurements were conducted between 850 and 940 °C.The best permeation-separation performance of membranes of about 1 mm thickness, showed a maximum permeance flux of about 4.46×10−7 mol·m−2·s−2·Pa−1 for CO2 and 2.18×10−7 mol·m−2·s−1·Pa−1 for O2 at 940 °C. Membranes exhibited separation factor values of 150–991 and 49–511 for CO2/N2 and O2/N2 respectively in the studied temperature range. Despite long-term stability test showed certain microstructural changes in the membranes, no significant detriment on the permeation properties was observed along 100 h of continuous operation.
Highlights
Greenhouse gas (GHG) emission produced by www.springer.com/journal/40145J Adv Ceram 2020, 9(1): 94–106The use of alternative sources of energy that do not involve the emission of CO2 is a promising way to reduce these pollutant emissions and to contribute to sustainability
This work aims to inquire on the feasibility to process ceramic–carbonate membranes, where the ceramic phase is composed in turn, of a mixture of fluorite and perovskite phases
The powders were chemically synthesized by the so-called one-pot method which is based on the combined ethylene-diamine-tetra acetic acid (EDTA)/citrate complexing method to produce crystalline complex oxides as a final product [23,24,25]
Summary
Greenhouse gas (GHG) emission produced by www.springer.com/journal/40145J Adv Ceram 2020, 9(1): 94–106The use of alternative sources of energy that do not involve the emission of CO2 is a promising way to reduce these pollutant emissions and to contribute to sustainability. Sherman et al [6] proposed, at a conceptual level, a combustion-assisted CO2 capture process, by using a metal–carbonate dual phase membrane, to separate CO2 coming from a power plant flue gas. The design of this process involves the catalytic combustion of syngas on the permeate side of the membrane. Due to the energy cost associated with the operation, the membrane requires substantial improvements in the permeation flux density and stability, under useful operational conditions
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