YBa2Cu3O7−δXσ (X=F and CI): Highly Active and Durable Catalysts for the Selective Oxidation of Ethane to Ethene

The catalytic performance and characterization of YBa2Cu3O7−δ and YBa2Cu3O7−δXσ for the oxidative dehydrogenation of ethane (ODE) to ethene have been investigated. Under the reaction conditions of temperature=680°C, C2H6/O2/N2 molar ratio=2/1/3.7, and contact time=1.67×10−4 h g ml−1, YBa2Cu3O7−0.21F0.16 showed 84.1% C2H6 conversion, 81.8% C2H4 selectivity, and 68.8% C2H4 yield; YBa2Cu3O7−0.18Cl0.13 showed 92.5% C2H6 conversion, 72.0% C2H4 selectivity, and 66.6% C2H4 yield. The sustainable performance during a period of 40 h on-stream reaction at 680°C demonstrated that the F- and Cl-doped catalysts are durable. X-ray powder diffraction results indicated that the undoped YBa2Cu3O7−δ and halide-doped YBa2Cu3O7−δXσ were of triple-layered oxygen-deficient perovskite-type orthorhombic structure. The results of the X-ray photoelectron spectroscopy, thermal treatment, thermogravimetric analysis, and 18O2-pulsing studies indicated that the incorporation of halide ions into the YBa2Cu3O7−δ lattice enhanced the activity of lattice oxygen. According to the O2 temperature-programmed desorption and temperature-programmed reduction results, we conclude that the oxygen species desorbed at 610–710°C are active for the selective oxidation of ethane and those desorbed below 610°C are active for the total oxidation of ethane; a suitable oxygen nonstoichiometry and Cu3+ concentration in YBa2Cu3O7−δXσ are required for the best catalytic performance of the catalysts.