A Thermally Conductive Pt/AAO Catalyst for Hydrogen Passive Autocatalytic Recombination
| Autor: | Dmitri Bessarabov, Aleksander A. Malakhov, A.E. Kozhukhova, Stephanus P. du Preez |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Materials science
catalytic hydrogen combustion Hydrogen Scanning electron microscope Al6082 Oxide chemistry.chemical_element 02 engineering and technology Activation energy 010402 general chemistry lcsh:Chemical technology 01 natural sciences Catalysis anodized aluminum Autocatalysis lcsh:Chemistry chemistry.chemical_compound lcsh:TP1-1185 Physical and Theoretical Chemistry passive autocatalytic recombiner Anodizing 021001 nanoscience & nanotechnology 0104 chemical sciences Chemical engineering chemistry lcsh:QD1-999 Particle size 0210 nano-technology |
| Zdroj: | Catalysts, Vol 11, Iss 491, p 491 (2021) Catalysts Volume 11 Issue 4 |
| ISSN: | 2073-4344 |
| Popis: | In this study, a Pt/anodized aluminum oxide (AAO) catalyst was prepared by the anodization of an Al alloy (Al6082, 97.5% Al), followed by the incorporation of Pt via an incipient wet impregnation method. Then, the Pt/AAO catalyst was evaluated for autocatalytic hydrogen recombination. The Pt/AAO catalyst’s morphological characteristics were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average Pt particle size was determined to be 3.0 ± 0.6 nm. This Pt/AAO catalyst was tested for the combustion of lean hydrogen (0.5–4 vol% H2 in the air) in a recombiner section testing station. The thermal distribution throughout the catalytic surface was investigated at 3 vol% hydrogen (H2) using an infrared camera. The Al/AAO system had a high thermal conductivity, which prevents the formation of hotspots (areas where localized surface temperature is higher than an average temperature across the entire catalyst surface). In turn, the Pt stability was enhanced during catalytic hydrogen combustion (CHC). A temperature gradient over 70 mm of the Pt/AAO catalyst was 23 °C and 42 °C for catalysts with uniform and nonuniform (worst-case scenario) Pt distributions. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used to compare the experimentally observed and numerically simulated thermal distribution of the Pt/AAO catalyst. The effect of the initial H2 volume fraction on the combustion temperature and conversion of H2 was investigated. The activation energy for CHC on the Pt/AAO catalyst was 19.2 kJ/mol. Prolonged CHC was performed to assess the durability (reactive metal stability and catalytic activity) of the Pt/AAO catalyst. A stable combustion temperature of 162.8 ± 8.0 °C was maintained over 530 h of CHC. To confirm that Pt aggregation was avoided, the Pt particle size and distribution were determined by TEM before and after prolonged CHC. |
| Databáze: | OpenAIRE |
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