Synthesis course and surface properties of praseodymium oxide obtained via thermal decomposition of praseodymium acetate: Impacts of the decomposition atmosphere

Abstract

The decomposition course, intermediates and final products of praseodymium acetate monohydrate Pr(CH 3COO) 3·H 2O in different gas atmospheres (O 2, N 2 or H 2) were characterized using thermal analysis, X-ray diffractometry and infrared spectroscopy. Praseodymium acetate decomposes in five mass loss events leading to the formation of the intermediate products Pr(OH)(CH 3COO) 2, PrO(CH 3COO) and Pr 2O 2CO 3. Results obtained indicate that praseodymium acetate decomposes into a number of intermediate products whose chemical structure is independent on the gas atmosphere applied, but the kinetics of their formation and subsequent decomposition is considerably enhanced in O 2 atmosphere. The final product at 700 °C was found to be praseodymium oxide Pr 6O 11 in O 2 and N 2, but mixed with minority Pr 2O 3 in H 2 atmosphere. Surface texture and 2-propanol decomposition activity of the final products at 700 °C were determined by means of N 2 sorptiometry and in situ IR spectroscopy. The final products in O 2 and N 2 were slightly more active catalysts toward 2-propanol decomposition the latter was of higher selectivity toward the alcohol dehydration, which is suggested to be correlated with the evolution of a narrower mesoporous structure on its surface.