Complex-Oxide Catalysts in Cracking of Propane

The study investigates propane conversion in the presence of rare-earth metal zirconates Ln 2 Zr 2 O 7 (Ln = La, Gd, and Lu) prepared by high-temperature solid-phase synthesis at 500, 1000, and 1500°C. In the La 2 Zr 2 O 7 → Gd 2 Zr 2 O 7 → Lu 2 Zr 2 O 7 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 Lu 2 Zr 2 O 7 catalyst exhibited a higher propylene selectivity (up to 65%) than La 2 Zr 2 O 7 , with 100% propane conversion being achieved.