SABRINA GONCALVES DE MACEDO CARVALHO
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Artigo IPEN-doc 28678 Tape-casting and freeze-drying gadolinia-doped ceria composite membranes for carbon dioxide permeation2022 - CARVALHO, SABRINA G.M.; MUCCILLO, ELIANA N.S.; FONSECA, FABIO C.; MULLER, MICHAEL; SCHULZE-KUPPERS, FALK; BAUMANN, STEFAN; MEULENBERG, WILHELM A.; GUILLON, OLIVIER; MUCCILLO, REGINALDOPorous ceria: 20 mol% gadolinia (20GDC) ceramic membranes were prepared by tape casting (TC) and freeze-drying (FD) techniques, obtaining ceramic matrices with randomly dispersed round pores and with an aligned pore structure, respectively. Samples were sintered at 1450 Ā°C, followed by infiltration of molten eutectic sodium-lithium carbonates (NLC). The pore morphology of 20GDC-TC and 20GDC-FD composite membranes was evaluated by analysis of scanning electron microscopy images. The electrical resistivity was determined by electrochemical impedance spectroscopy in the 1 Hz - 10 MHz frequency range from 300 Ā°C to 700 Ā°C, covering the solid-to-molten NLC temperature range, showing that the aligned pore structure improved the conductivity of the ceramic matrix in addition to facilitating molten carbonate infiltration, improving the total (bulk + interfaces) electrical conductivity of the composite membrane. Permeation experiments showed high CO2 permeation rates reached 5.35 Ć 10ā7 mol mā2 sā1 Paā1 at 800 Ā°C. The infiltration of molten sodium-lithium carbonate in gadolinium-doped ceria prepared by the freeze-drying technique is proposed as an optimized procedure for producing membranes for carbon dioxide separation.