Halogenated La1.6Sr0.4CuO4 catalysts active for ethane selective oxidationto ethene

The catalytic performances and characterization of the catalysts La1.6Sr0.4 CuO3.852, La1.6Sr0.4CuO3.857F0.143, and La1.6Sr0.4 CuO3.856Cl0.126 have bee n investigated for the oxidative dehydrogenation of ethane (ODE) to ethene. X-ray diffraction results indicated that the three catalysts have a single -phase tetragonal K2NiF4-type structure. The incorporation of fluoride or c hloride ions in the La1.6Sr0.4CuO4-delta lattice can significantly enhance C2H6 conversion and C2H4 selectivity. We observed 83.2% C2H6 conversion, 76 .7% C2H4 selectivity, and 63.8% C2H4 yield over La1.6Sr0.4CuO3.857F0.143 an d 79.6% C2H6 conversion, 74.6% C2H4 selectivity, and 59.4% C2H4 yield over La1.6Sr0.4CuO3.856Cl0.126 under the reaction conditions of C2H6/O-2/N-2 mol ar ratio 2/1/3.7, temperature 660 degrees C, and space velocity 6000 ml h(- 1) g(-1). With the rise in space velocity, C2H6 conversion decreased, where as C2H4 selectivity increased. Life studies showed that the two catalysts w ere durable within 60 h of on-stream ODE reaction. Based on the results of X-ray photoelectron spectroscopy, O-2 temperature-programmed desorption, an d C2H6 and C2H6/O-2/N-2 (2/1/3.7 molar ratio) pulse studies, we conclude th at (i) the inclusion of halide ions in the La1.6Sr0.4CuO4-delta lattice cou ld promote lattice oxygen mobility, and (ii) the O- species accommodated in oxygen vacancies and desorbed below 600 degrees C favor ethane complete ox idation whereas the lattice oxygen species desorbed in the 600-700 degrees C range are active for ethane selective oxidation to ethene. By regulating the oxygen vacancy density and Cu3+/Cu ratio in the K2NiF4-type halo-oxide catalyst, one can generate a durable catalyst with good performance for the ODE reaction.