The Structural Study of Gold Catalytic Nanosystems by XAFS Method
The International Conference "Synchrotron and Free electron laser Radiation: generation and application"
04-07 Jul 2016
|| Yakimchuk Evgeni Petrovich
, Kriventsov Vladimir Vladimirovich
, Bulushev Dmitri Aleksandrovich
, Novgorodov Boris Nikolaevich
, Ivanov Dmitrii Petrovich
, Aksenov Dmitry Grigorʹevich
, Zyuzin Dmitriy Albertovich
, Smirnova Nadezhda Sergeevna
, Nikolaev Sergej Aleksandrovich
, Simakov Andrey Valerʹevich
, Chistyakov Andrej Valerʹevich
, Fedotov Aleksey Stanislavovich
, Antonov Oleg Dmitrievich
, Tsodikov Mark Veniaminovich
Boreskov Institute of Catalysis SB RAS
Lomonosov Moscow State University
A.V. Topchiev Institute of Petrochemical Synthesis RAS
Institute of Hydrocarbons Processing SB RAS
National Autonomous University of Mexico
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).