Adjustment of Active Sites in Catalytic Ammonia Synthesis over Metal Alloys and Clusters: A Theoretical Study Full article
| Journal |
Applied Catalysis A: General
ISSN: 0926-860X , E-ISSN: 1873-3875 |
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| Output data | Year: 2018, Volume: 562, Pages: 223-233 Pages count : 11 DOI: 10.1016/j.apcata.2018.06.017 | ||
| Tags | Catalytic ammonia synthesis Active sites Alloys Clusters Synergetic effect | ||
| Authors |
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| Affiliations |
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Funding (2)
| 1 | Federal Agency for Scientific Organizations | 0303-2016-0001 |
| 2 | Russian Foundation for Basic Research | 17-03-00049 |
Abstract:
Earlier, a theoretical model was suggested to discriminate catalytic sites Mn (each consisting of n adjacent atoms M on the metal surface) according to their undercoordination Σ. It has been shown that the maximum activity of a site Mn (M = Pt, Rh, Ir, Fe, Ru, Re; n = 2, 3, 4) in the catalytic synthesis of ammonia requires the “resonant” Σ, whose major part is inaccessible at perfect planes because of steric restrictions. The current study applies this model to binary alloys and clusters to construct an advanced catalytic site by adjustment of real Σ to the resonance. The catalytic activity of a site Mn has been estimated by the Brønsted-Evans-Polanyi relation with respect to the formation of NH species. It was found that on alloy surfaces, sites M3 and M4 demonstrate synergetic behavior. This suggests that the most active catalyst (Ru or Re) can be improved by its alloying with the least active one (Pt or Rh). In the case of the noble metals, the sites M3 and M4 at 4-, 5-, and 11- atomic clusters are ∼10–103 times more active than such sites at perfect planes, whereas the sites of Ru and Re show the opposite behaviour. The model was verified by comparison of the calculated specific catalytic activities of metals, centers Fe-C7 and Ru-B5, and single crystals with the published data. The superior activity of a catalytic site is generally enabled by its optimal thermodynamics, which is affected deeply by the first coordination shell. A correlation between local structure, thermodynamics, and activity of a site is likely valid for other catalytic systems.
Cite:
Cholach A.R.
Adjustment of Active Sites in Catalytic Ammonia Synthesis over Metal Alloys and Clusters: A Theoretical Study
Applied Catalysis A: General. 2018. V.562. P.223-233. DOI: 10.1016/j.apcata.2018.06.017 WOS Scopus РИНЦ ANCAN OpenAlex
Adjustment of Active Sites in Catalytic Ammonia Synthesis over Metal Alloys and Clusters: A Theoretical Study
Applied Catalysis A: General. 2018. V.562. P.223-233. DOI: 10.1016/j.apcata.2018.06.017 WOS Scopus РИНЦ ANCAN OpenAlex
Dates:
| Submitted: | Apr 30, 2018 |
| Accepted: | Jun 9, 2018 |
| Published online: | Jun 15, 2018 |
| Published print: | Jul 1, 2018 |
Identifiers:
| Web of science: | WOS:000443630600024 |
| Scopus: | 2-s2.0-85048616381 |
| Elibrary: | 35717441 |
| Chemical Abstracts: | 2018:1156542 |
| Chemical Abstracts (print): | 169:162982 |
| OpenAlex: | W2808624566 |