This report shows the results of XAFS (XANES/EXAFS) research on the state and local structure of metals in the active component of model low-percentage metal-carbon nanocomposite catalysts containing nanoscale forms of Pt, Pd, Ru. It is a well-known fact that low-percentage catalytic nanosystems containing platinoids deposited on various carbon carriers are of great interest to researchers because of their practical significance; possibilities for varying catalytic properties and applications for a wide range of processes (hydrogenation, conversion of industrial substrates, debenzylation of amines, etc.).), low cost of final products, ease of disposal and recovery of expensive components from spent catalysts. Model samples were prepared from precursors of different nature, with varying methods of synthesis and formation of the applied component, recovery and activation modes. XAFS (XANES/EXAFS) spectra (Pt-L3, Pd-K, Ru-K) of studied samples were recorded at SSTRC, Novosibirsk. The lengths of interatomic bonds and the corresponding coordination numbers are established. Additionally XPS, TEM, XRD, XRF methods were applied to study chemical and phase compositions, morphology of the samples. Data obtained by different methods do not contradict each other. Possible variants of structural models are considered in detail. Correlations were found between the structure of the active component and the catalytic properties of the studied samples. The perspective of the proposed approach for the study of nanocomposite model metal-carbon catalysts containing platinoids is shown.
The work was carried out in the framework of the RFBR projects no. 19-05-50046, 18-03-01251. The work was done at the shared research center SSTRC on the basis of the Novosibirsk FEL/VEPP-4-VEPP-2000 complex at BINP SB RAS, using equipment supported by project RFMEFI62119X0022.