Modified cellulose adsorption method for the synthesis of conducting perovskite powders for membrane application

A modified cellulose adsorption method, i.e., pyrolysis of cellulose-(organic acid)-salt solid composite was applied for the synthesis of conducting perovskite-type La_1-xSr_xBO_3-δ (B=Co, Fe, Mn; x=0.0, 0.1, 0.2) functional oxides. Citric acid is mainly selected as the organic acid. Infrared (IR), scanning electron microscopy-electron diffusion spectroscopy (SEM-EDS) and X-ray diffraction (XRD) results indicated that the citric acid modified cellulose adsorption method could preserve the homogeneity of the solution system to the solid precursor more efficiently than the unmodified one, due to the change of interaction between metal salts and organic substance from weak chemical adsorption to chemical chelation and fixation. Thermal gravimetry and differential thermal analysis (TG-DTA) and IR results demonstrated that the citric acid's addition also changed the pyrolysis behavior of the precursor. Perovskite oxides could be obtained at low temperatures (≤600 °C) without development of other phases; the as-prepared powders had the morphology of cellulose fiber and relatively high Brunauer-Emmet-Teller (BET) surface areas (8-30 m²/g). The resulted oxide powders also demonstrated excellent sinterability, it is suitable for fabrication of dense membranes.