Effect of calcination temperature on the structural characteristics and catalytic activity for propene combustion of sol-gel derived lanthanum chromite perovskite

The perovskite type lanthanum chromite LaCrO3 has been synthesized by a sol-gel method. Its bulk structural and surface characteristics have been examined by X-ray diffraction (XRD), SEM, S-BET measurements, Fourier Transform Infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) as a function of the calcination treatment performed between 200 and 1000 degrees C over the precursor powder and in correlation with information achieved from TG-DTA thermal analysis. The characterization results are employed to rationalize the catalytic behaviour of the system towards propene complete oxidation. It is shown that the catalytic activity becomes optimized when a single perovskite LaCrO3 phase is achieved upon calcination at T > ca. 700 degrees C. In contrast, coexistence of perovskite LaCrO3 and monazite LaCrO4 at lower calcination temperatures appears detrimental to the combustion activity of the system. (c) 2007 Elsevier B.V. All rights reserved.