Complex-Oxide Catalysts in Cracking of Propane

The study investigates propane conversion in the presence of rare-earth metal zirconates Ln₂Zr₂O₇ (Ln = La, Gd, and Lu) prepared by high-temperature solid-phase synthesis at 500, 1000, and 1500°C. In the La₂Zr₂O₇ → Gd₂Zr₂O₇ → Lu₂Zr₂O₇ series, the phase transitions were found to follow the pyrochlore → defective fluorite → δ-phase route. This changed the parameters of the crystalline and local structures and, in particular, led to the appearance of oxygen vacancies in pyrochlore-based compounds. As a result of the structural changes, propane dehydrogenation prevailed over propane degradation. Therefore, the Lu₂Zr₂O₇ catalyst exhibited a higher propylene selectivity (up to 65%) than La₂Zr₂O₇, with 100% propane conversion being achieved.