Development of a low purity aluminum alloy (Al6082) anodization process and its application as a platinum-based catalyst in catalytic hydrogen combustion

Abstract

In this study, we present a process to prepare a Pt/anodized aluminum oxide (AAO) catalyst for catalytic hydrogen combustion applications using low cost and low aluminum (Al) purity Al6082 alloy (97.5% Al) as the substrate. The effects of the anodization temperature, voltage, and time of the second anodization step on the morphological characteristics were investigated using 5 wt% phosphoric acid (H3PO4) as the electrolyte. AAO layers with semi-ordered pore arrangements were obtained by varying the anodization conditions while preserving an Al metallic core. Morphological characterization of the AAO layer was carried out with scanning electron microscopy and characterization of the Pt/AAO catalyst with transmission electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-synthesized AAO layers had pore diameters of 91.0 ± 10.0 nm, interpore distances of 138.7 ± 27.4 nm, pore densities of 68 ± 15 pores/μm2, and 39% porosity. Pt/AAO catalyst had a Pt loading and Pt particle size of 1.01 ± 0.11 wt% and of 4.7 ± 2.0 nm, respectively. During catalytic hydrogen combustion, a stable combustion temperature of 338 ± 11 °C was maintained for 530 h and no Pt aggregation nor support degradation was evident