K. Ploner, T. Götsch, G. Kogler, R. Thalinger, J. Bernardi, Q. Zhao, C. Zhuo, B. Klötzer, S. Penner:
"Structural and Catalytic Properties of Ag- and Co3O4‑Impregnated Strontium Titanium Ferrite SrTi0.7Fe0.3O3−δ in Methanol Steam Reforming";
Industrial & Engineering Chemistry Research,
The catalytic performance of Ag- and Co3O4-impregnated strontium titanium ferrite (SrTi0.7Fe0.3O3−δ, STF) has been assessed in methanol steam reforming as a test reaction and accordingly correlated with spectroscopic and structural characterization after each step of a catalytic cycle including preoxidation and prereduction. After prereduction in hydrogen at 400 °C, metallic silver and oxidized Co in the form of Co3O4 are present. As for catalysis, it was observed that both Ag and Co3O4 strongly promote the methanol chemistry with respect to pure STF already at low temper-atures (230 °C for both materials). As a consequence, the selectivity toward carbon monoxide is strongly enhanced in comparison to pure STF. On Co3O4-STF, the catalytic proﬁle is basically dominated by a temperature-dependent complex interplay between methanol steam reforming, methanol dehydrogenation, and the water gas shift equilibrium. The results also prove that despite the obvious inadequacy of H2-prereduced Ag-STF to act as a highly CO2-selective steam reforming catalyst, a potential use as a low-temperature fuel cell anode material might be envisioned. It is shown that Ag eﬀectively lowers the activation barrier for the total oxidation of methanol to CO2, if the reaction is started from the fully preoxidized catalyst. This is explained by fast and eﬃcient supply of lattice oxygen from STF toward Ag via the perovskite−metal phase boundary, which is expected to prevail if Ag-STF is used as a solid oxide fuel cell anode material with continuous electrochemical supply of lattice oxygen.
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