Non isothermal decomposition of lanthanum titanates precursors prepared by sol gel process: A kinetic and thermodynamic study

The single phase La0.8Sr0.2TiO3+δ was prepared via the sol gel process using propionic acid. Kinetics of the thermal decomposition of the precursors has been studied using differential thermogravimetry under non-isothermal conditions in different atmospheres (air and helium). Non isothermal kinetic (A and ΔE) and thermodynamic parameters (ΔH, ΔS and Cp) were determined using different heating rates. La2O3, SrO and TiO2 products crystallized at temperatures of ca. 730, 960 and 470 °C respectively while pure La0.8Sr0.2TiO3+δ phase was obtained at 1200 °C, temperature substantially lower than that used for the preparation of La0.8Sr0.2TiO3+δ by conventional solid state method.Precursors and/or final solids were characterized by thermogravimetric analysis (TG), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, diffuse reflectance ultraviolet–visible spectroscopy (DR-UV–vis) and methane steam reforming under water deficient conditions.

► Metal-propionates is a most promising route for the preparation of La0.8Sr0.2TiO3+δ (LST) at a temperature substantially lower than that used for the preparation of the same solid by traditional methods.
► Activation energy and isothermal thermodynamic parameters calculated for the decomposition process are close to those observed for metal organic compounds.
► Sol gel-prepared LST presented low propensity to coke deposition and high stability with time during the critical long term exposure to methane and steam at high temperatures.