Abstract
Iridium modified Ni/Al2O3 catalysts were prepared using Ni-Al hydrotalcite as precursor and tested in the selective decomposition of hydrous hydrazine for H2 generation. Compared to Ni/Al2O3, NiIrx/Al2O3 catalysts exhibited an increase of the reaction rate up to 6-fold and the H2 selectivity from 93% to above 99%. The XRD and EXAFS analysis confirmed that Ir and Ni were present in the form of Ni-Ir alloy; and the H2 differential heat of adsorption is appreciably lowered with increasing the amount of Ir in Ni-Ir alloy. High-temperature reduction, e.g. 700°C, induced the migration of Ir atoms into the Ni bulk and produced a Ni-skin surface. This structural modification is associated with a strongly decrease of activity and selectivity. EXAFS measurements were also performed on different noble metals (NM, Ir, Pt, and Au) modified Ni/Al2O3 catalysts in order to verify the extent of NM-Ni bimetallic bond formation, which was found to correlate with the catalytic performance.
Original language | English |
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Pages (from-to) | 779-788 |
Number of pages | 10 |
Journal | Applied Catalysis B: Environmental |
Volume | 147 |
DOIs | |
Publication status | Published - Apr 5 2014 |
Externally published | Yes |
Keywords
- EXAFS
- Hydrazine
- Hydrogen storage
- Microcalorimeter
- Nickel-iridium alloy
ASJC Scopus subject areas
- Catalysis
- General Environmental Science
- Process Chemistry and Technology