Perovskite-type halo-oxide La{sub 1{minus}x}Sr{sub x}FeO{sub 3{minus}{delta}}X{sub {sigma}} (X=F, Cl) catalysts selective for the oxidation of ethane to ethene
The catalytic performance and characterization of perovskite-type halo-oxide La{sub 1{minus}x}Sr{sub x}FeO{sub 3{minus}{delta}}X{sub {sigma}} (X = F, Cl) as well as La{sub 1{minus}x}Sr{sub x}FeO{sub 3{minus}{delta}} (x = 0--0.8) for the oxidative dehydrogenation of ethane (ODE) to ethene have been investigated. XRD results indicate that the catalysts had oxygen-deficient perovskite structures and TGA results demonstrated that the F- and Cl-doped perovskites were thermally stable. Under the reaction conditions of C{sub 2}H{sub 6}/O{sub 2}/N{sub 2} = 2/1/3.7, temperature = 660 C, and space velocity = 6000 mL/h g, C{sub 2}H{sub 6} conversion, C{sub 2}H{sub 4} selectivity, and C{sub 2}H{sub 4} yield were, respectively, 55.3, 45.1, and 24.9% over La{sub 0.6}Sr{sub 0.4}FeO{sub 3--0.048}; 76.8, 62.1, and 47.7% over La{sub 0.8}Sr{sub 0.2}FeO{sub 3--0.103}F{sub 0.216}; and 84.4, 68.4, and 57.6% over La{sub 0.6}Sr{sub 0.4}FeO{sub 3--0.103}Cl{sub 0.164}. Over the two halo-oxide catalysts, with an increase in space velocity, C{sub 2}H{sub 6} conversion decreased, whereas C{sub 2}H{sub 4} selectivity increased. Both La{sub 0.8}Sr{sub 0.2}FeO{sub 3--0.103}F{sub 0216} and La{sub 0.6}Sr{sub 0.4}FeO{sub 3--0.103}Cl{sub 0.164} were durable within 40 h of onstream ODE reaction. XPS results suggested that the presence of halide ions in the perovskite lattices promotes lattice oxygen mobility. It is apparent that the inclusion of F{sup {minus}} or Cl{sup {minus}} ions in La{sub 1{minus}x}Sr{sub x}FeO{sub 3{minus}{delta}} can reduce the deep oxidation of C{sub 2}H{sub 4} and thus enhance C{sub 2}H{sub 4} selectivity. Based on the results of O{sub 2}-TPD and TPR studies, the authors suggest that the oxygen species that desorbed at temperatures ranging from 590 to 700 C over the La{sub 0.8}Sr{sub 0.2}FeO{sub 3--0.103}F{sub 0.216} and La{sub 0.6}Sr{sub 0.4}FeO{sub 3--0.103}Cl{sub 0.164} catalysts are active for the selective oxidation of ethane to ethene. By regulating the oxygen vacancy density and the oxidation states of B-site cations by implanting halide ions into oxygen vacancies in perovskite-type oxides (ABO{sub 3}), one may obtain catalysts that are durable and selective for the ODE reaction.
- Research Organization:
- Hong Kong Baptist Univ., Kowloon (HK)
- OSTI ID:
- 20014520
- Journal Information:
- Journal of Catalysis, Vol. 189, Issue 1; Other Information: PBD: 1 Jan 2000; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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