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Chlorobenzene hydrodechlorination on bimetallic catalysts prepared by laser electrodispersion of NiPd alloy

Authors
  • Golubina, Elena V.1
  • Rostovshchikova, Tatiana N.1
  • Lokteva, Ekaterina S.1
  • Maslakov, Konstantin I.1
  • Nikolaev, Sergey A.1
  • Egorova, Tolganay B.1
  • Gurevich, Sergey A.2
  • Kozhevin, Vladimir M.2
  • Yavsin, Denis A.2
  • Yermakov, Anatoly Ye.3, 4
  • 1 Lomonosov Moscow State University, Russia , (Russia)
  • 2 Ioffe Physico-Technical Institute of RAS, Russia , (Russia)
  • 3 M. N. Miheev Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences, Russia , (Russia)
  • 4 Ural Federal University named after the first President of Russia B. N. Yeltsin, Russia , (Russia)
Type
Published Article
Journal
Pure and Applied Chemistry
Publisher
Walter de Gruyter GmbH
Publication Date
Aug 18, 2018
Volume
90
Issue
11
Pages
1685–1701
Identifiers
DOI: 10.1515/pac-2018-0207
Source
De Gruyter
Keywords
License
Yellow

Abstract

NiPd bimetallic systems were for the first time synthesized by laser electrodispersion (LED) of the Ni77Pd23 alloy target followed by the deposition of produced bimetallic particles on a TEM copper grid and alumina granules. Selective area energy-dispersive analysis confirms the bimetallic nature of NiPd particles deposited on a TEM copper grid. Their mean size is 1.0 nm according to TEM. XPS data demonstrate that under deposition on alumina granules (total metal content of 0.005 wt.%), nickel in bimetallic particles nearly completely oxidizes to Ni2+ species predominantly in the form of aluminate. At the same time major part of palladium (84%) exists in Pd0 but oxidizes to Pd2+ (80%) during 6 months storage in air. Both metals are deposited on the external surface of alumina granules and localized in the same areas. In situ reduction of both metals by H2 in the catalytic cell of XPS spectrometer is hindered. Nickel is not reduced even at 450°C, confirming the formation of NiAlOx, whereas palladium is reduced at higher temperatures compared to a similar monometallic catalyst. Nevertheless, NiPd/Al2O3 catalyst is more efficient in gas-phase chlorobenzene hydrodechlorination at 150–350°C than Ni/Al2O3 and even Pd/Al2O3, and much more stable. The difference may be caused by the formation of new active sites due to the contact between Pd0 and NiAlOx-modified support, and the protective action of spinel reacting with HCl by-product.

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