Effect of M ion oxidation state in Sr1−xMxTiO3±δ perovskites in methane catalytic flameless combustion

Abstract

Sr 1−x M x TiO 3±δ (x = 0 or 0.1; M = K or Gd) have been compared as catalysts for the flameless combustion of methane. The samples were prepared both by traditional sol-gel (SG) and by flame-hydrolysis (FH) procedure. All the catalysts possessed the perovskite-like structure, with some SrCO 3 as impurity with Sr 0.9 K 0.1 TiO 3±δ prepared by SG procedure. All the samples prepared by FH were better catalysts than those prepared by SG. A further improvement in the catalytic activity was obtained with M = K, but only at temperatures lower than 550 • C. X-band and Q-band EPR spectroscopies provided an explanation of this observation, based on the high mobility of surface O 3 − species on the surface of the (FH) Sr 0.9 K 0.1 TiO 3±δ sample.

Surface Reconstruction under the Exposure of Electric Fields Enhances the Reactivity of Donor-Doped SrTiO3

“…(a) Steady-state conversions obtained for the oxidation reaction of CH 4 over LSTO systems consolidated at different conditions. (b) CH 4 oxidation reaction rates of LSTO systems presented in this work compared with reported values by Oliva et al for donor-doped SrTiO 3 (Sr 0.9 Gd 0.1 TiO 3 ) sintered in oxidizing conditions 75. The values are retrieved at T = 550 °C and normalized by surface area.…”

Perovskites as Substitutes of Noble Metals for Heterogeneous Catalysis: Dream or Reality

“…Double perovskites associating Ni and Cu were prepared by Hu et al, who showed that the activity of La 2 CuNiO 6 for methane oxidation was much higher than that of the single perovskite (LaNiO 3 ) while the physical mixture LaNiO 3 + LaCuO 3 was less active than LaNiO 3 at isospace velocity. Chromites were also investigated by Kaddouri et al, while titanates were studied by the group of Forni − and by Popescu et al , ESR characterization showed the presence of different oxygen species associated to Ti cations, O 3 – /Ti 4+ species having a crucial role in oxidation reactions. Silver seems to be a good substitute for Sr in SrTiO 3 titanates.…”

A review of advances in multifunctional XTiO3 perovskite-type oxides as piezo-photocatalysts for environmental remediation and energy production

“…The high temperature required to dry out and combust the droplets is reached with a torch, which is usually fed with oxygen or air as oxidizing agent while the fuels are methane or hydrogen [77][78][79][80][81] in the flame hydrolysis asset. By contrast, in the flame spray pyrolysis version of the technique, the fuel is constituted by the organic solvent used to dissolve the precursors of the oxide.…”