Preparation of a Cartridge-Type Pt/Al2O3 Catalyst Using a Sputter Deposition Method for Catalytic Hydrogen Combustion

A Pt/Al2O3 catalyst for catalytic hydrogen combustion was prepared using magnetron sputtering─a physical vapor deposition method. The thus-prepared catalysts were characterized by scanning electron microscopy (SEM) and transmission electron microscopy. Catalysts with three different Pt layer thicknesses were evaluated: 5, 10, and 50 nm. The stabilities and durabilities of the catalysts were assessed during continuous and prolonged (190 h) hydrogen exposure. After 50 h of hydrogen combustion, the combustion temperature decreased in the case of the 5 nm catalyst, whereas the temperature remained relatively stable for the 10 and 50 nm catalysts. SEM analysis revealed that aggregation of the Pt layer occurred on the support (Al2O3) surface in all the tested catalysts; only the 5 nm Pt/Al2O3 catalyst was adversely affected by Pt aggregation. To then mitigate Pt aggregation, the Al2O3 support was calcined at 600 °C before Pt deposition. The best-performing catalyst (in terms of reactivity and stability) was subsequently used to prepare a cartridge-type combustion section. The latter-mentioned best-performing catalyst was tested in a recombiner section testing station. Infrared mapping was used to determine the thermal distribution of the catalyst. Maximum combustion temperatures of 378.7 and 372.6 °C were obtained with a 10 vol % hydrogen/air mixture at 8 and 10 m/s gas flow velocities, respectively. Maximum temperature gradients of 59.0 and 109.6 °C were recorded over 12 cm cartridge lengths for the 7 and 10 vol % hydrogen/air mixtures at 8 and 10 m/s gas flow velocities, respectively.