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Contribution Poster

Budker INP - 2nd and 3rd floors
X-ray spectroscopy

The structural study of gold catalytic nanosystems by XAFS method

Speakers

  • Dr. Vladimir KRIVENTSOV

Primary authors

Co-authors

Content

E.P. Yakimchuk1, V.V. Kriventsov1, D. A. Bulushev1, B.N. Novgorodov1, D.P. Ivanov1, D.G. Aksenov1, D.A. Zyuzin1, N.S. Smirnova2, S.A. Nikolaev3, A. Simakov4, A.V. Chistyakov5, A.S. Fedotov4, D.O. Antonov5, M.V. Tsodikov5

1) Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia 2) Institute of Hydrocarbons Processing SB RAS, Omsk, Russia. 3) Lomonosov Moscow State University, Department of Chemistry, Moscow, Russia 4) Centro de Nanociencias y Nanotecnologia, UNAM, Ensenada, B.C., Mexico 5) Topchiev Institute of Petrochemical Synthesis, RAS, Moscow, Russia

The structural study of gold catalytic nanosystems by XAFS method This work is devoted to a detailed structural study of the nanosized Au, Au-Me stabilized forms located on oxide supports by XAFS method. It is a well known fact that metallic gold is most inert among the precious metals due to its electronic structure, nevertheless the nanosized Au, Au-Me forms located on oxide supports may be used as very active catalysts for numerous industrially important reactions. These systems are very promising for complex organic synthesis, selective isomerization reactions and for processes of environmental catalysts, such as, CO oxidation and selective conversion of secondary alcohols. Reliable analysis of the nature of gold forms is extremely important for design of new effective gold based catalysts for different industrial applications. Synthesis of low-percentage ~ 0.2-2% Au, Au-Me samples was carried out under varying preparation methods (impregnation, deposition-precipitation with urea, direct ion exchange), calcination temperatures and activation methods. All XAFS spectra (Au-L3 edge) of the studied samples were recorded at SSTRC, Novosibirsk. The state of metal components and the local Au structure arrangements of the prepared catalysts were studied. The Au-O, Au-Au, Au-Me interatomic distances and corresponded coordination numbers were established. All possible structural models were discussed. It was shown that different stabilized gold forms located on oxide supports were formed, most probably depending on a sample prehistory: Au(3+) cations, having octahedral oxygen surrounding and metallic Au-Au, Au-Me nanoparticles ~10-100Å. Some correlations between catalytic activities and structural functional properties of the studied samples were shown. Additionally, samples of catalysts were characterized by the TEM, EDX, XRD, XPS methods. The data obtained by all the methods are in a good agreement.

The work was done using the infrastructure of the Shared-Use Center “Siberian Synchrotron and Terahertz Radiation Center (SSTRC)” based on VEPP-3 of BINP SB RAS. This work was supported by RFBR (140301066, 163350248, 163350249, 163350250, 160301139), SB RAS comprehensive program II.2P (Project 0305-2015-0018).