Composite Structured M/Ce0.75Zr0.25O2/Al2O3/FeCrAl (M = Pt, Rh, and Ru) Catalysts for Propane and n-Butane Reforming to Syngas.

Abstract

Here, we report the preparation, characterization, and performance of reforming propane and n-butane into a syngas of composite structured M/Ce0.75Zr0.25O2/Al2O3/FeCrAl (M = 0.46 wt.% Pt, 0.24 wt.% Rh, and 0.24 wt.% Ru) catalysts. The catalysts are composed of a high-heat-conducting FeCrAl block with preset geometry, with a surface nearly totally covered by θ-Al2O3. Afterwards, a layer of ceria–zirconia mixed oxide was deposited. The formed oxide coating was used as a support for 2–3 nm sized Pt, Rh, or Ru nanoparticles. The performance of the catalysts in propane steam reforming decreased in the order of Rh ≈ Ru > Pt. The reformates obtained in the propane steam reforming over Rh- and Ru/Ce0.75Zr0.25O2/Al2O3/FeCrAl at 600 °C and GHSV = 8300 h−1 contained 65.2 and 62.4 vol.% of H2, respectively, and can be used as a fuel for solid oxide fuel cells. In the oxidative steam reforming of propane at 700 °C and GHSV= 17,000 h−1, the activities of the Rh- and Pt-based catalysts were similar and the compositions of the outlet gas mixtures were quite close to equilibrium in both cases. Increasing the reagent flow rate to 25,600 h−1 showed stability of the Rh/Ce0.75Zr0.25O2/Al2O3/FeCrAl performance, whereas the Pt/Ce0.75Zr0.25O2/Al2O3/FeCrAl activity decreased. A mathematical model considering the velocity field, mass balance, pressure, and temperature distribution, as well as the reaction kinetics, was suggested for the propane steam and oxidative steam reforming over the Pt- and Rh/Ce0.75Zr0.25O2/Al2O3/FeCrAl catalysts. The model well described the experimental results.