La1-xSrxMnO3-δ (x = 0.4, 0.5, and 0.6) catalysts were fabricated hydrothermally from KMnO4, MnCl2 (KMnO4/MnCl2 molar ratio = 3/7), and stoichiometric amounts of lanthanum and strontium nitrates in KOH solution. The physicochemical properties of the materials were characterized by a number of analytical techniques. It was found that the La1-xSrxMnO3-δ samples fabricated at 250 °C are single-crystalline perovskite-type oxides in the form of microcubes. The as-fabricated La1-xSrxMnO3-δ materials display various states of oxygen nonstoichiometry. The total amount of oxygen vacancies and Mn4+ in the catalysts decreases in the order of La0.5Sr0.5MnO3-δ > La0.4Sr0.6MnO3-δ > La0.6Sr0.4MnO3-δ. It has been found that the trends of catalyst reducibility and catalytic performance of the three catalysts follow a similar order. We observed 100% toluene conversion at 255 °C over the La0.5Sr0.5MnO3-δ catalyst, 113 °C lower than that observed over a polycrystalline La0.5Sr0.5MnO3-δ catalyst prepared by calcination at 950 °C. The excellent performance of the former can be related to the high Mn4+/Mn3+ ratio, distinct oxygen nonstoichiometry, and single-crystalline structure of the catalyst.
Scopus Subject Areas
- Process Chemistry and Technology
- Physical and Theoretical Chemistry
- Hydrothermal synthesis
- Single-crystalline perovskite-type oxide
- Toluene oxidation
- Volatile organic compounds