Application of XAFS for study of nano-dispersed Pd catalysts
V.V. Kriventsov 1), B.N. Novgorodov 1), D.P. Ivanov 1), D.G. Aksenov 1), D.A. Zyuzin 1), N.S. Smirnova 2), V.Z. Radkevich3), O.V. Arapova 4), A.V. Chistyakov 4), S.A. Nikolaev 5), M.V. Tsodikov 4)
1) Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia 2) Institute of Hydrocarbons Processing SB RAS, Omsk, Russia. 3) Institute of Physical Organic Chemistry NAS of Belarus, Minsk, Belarus. 4) Topchiev Institute of Petrochemical Synthesis, RAS, Moscow, Russia 5) Lomonosov Moscow State University, Department of Chemistry, Moscow, Russia
This work is devoted to a study of the state and local structure of original nano-dispersed catalytic low-percentage systems Pd-M, M=Zn, Co, Mn, Ag used for production of alkanes or olefins fractions С4-С12+ which components of biofuels obtained from biomass fermentation products. Nowadays great attention is attracted to development of highly effective approaches of converting renewable biomass into energy resources as biofuels. Some spirit compounds, such as ethanol, butanol, pentanol, glycerine, being biomass fermentation products, may be used as fuel components, both without any treatment and after catalytic converting, that provides production of more effective fuel components. This work is devoted to a study of the state and local structure of original nano-dispersed catalytic low-percentage systems Pd-M, M=Zn, Co, Mn, Ag used for production of alkanes or olefins fractions С4-С12+ which components of biofuels obtained from biomass fermentation products. Initial samples of catalysts were prepared by impregnation and zol-gel methods from original mono- and hetero-metallic precursors located on the oxide supports. All XANES and EXAFS spectra of the studied samples were recorded at Siberian Synhroton and Terahertz Radiation Center (SSTRC, Novosibirsk).Genesis of the local structure of the studied catalytic nanosystems was characterized in detail. The interatomic distances and corresponded coordination numbers were revealed. All possible structural models were discussed. Relations between their catalytic properties, local structure distortions and state of metal components were demonstrated. It was found out that active components of all studied systems were highly dispersed onto the oxide support surface and strong interaction with the support took place, resulting in formation of mixed surface MeOx - support oxides. Additionally, the samples of catalysts were characterized by the HRTEM, EDX, XPS methods. The data obtained by all the methods are in a good agreement. This work was conducted within the framework of the budget project #АААА-А17-117041710078-1 for Boreskov Institute of Catalysis. Vladimir Kriventsov thanks to the Russian Foundation for Basic Research for support of the analysis of the XANES data (projects No. 16-03-01139, 17-33-50198, 18-03-01251).