Melnychuk O. High-pore nanostructured carbon materials as elements of catalytic systems

High-pore nanostructured carbon materials as elements of catalytic systems Mesoporous carbon material characterized by specific surface area of 1120°m2/g and unique value of maximum adsorption capacity of benzene vapor - 2.12°cm3/g was created by template synthesis using innovative methods. It has been revealed that with additional saturation and subsequent carbonization of the precursor, it is possible to obtain nanoporous carbon material with a compacted framework, which is largely free from micropores. Adsorption, structural and physical-chemical characteristics of the obtained materials are investigated. The influence of the nature of carbon materials on the structure of the oxide layer of materials with different degree of surface oxidation is determined. It is shown that despite the different nature of carbon materials and the nature of their porosity, the formation of oxide layers on the surface is similar. The original method of diagnostics of the porous structure of NVM by the method of adsorption in combination with the methods of low-angle X-ray scattering has been developed. With the help of this technique the peculiarities of transformation of the structure of nanostructured carbon materials into a hierarchical sequence are investigated: initial silica gel - silicate-polymer nanocomposite - silicate-carbon nanocomposite - mesoporic nanostructured carbon material. On the basis of the obtained materials catalytic systems with various concentrations of nickel applied were synthesized. The effective thickness of nickel nanoclusters in the samples is about 0.8°nm and is virtually independent of the metal concentration in the material. It has been established that at a nickel content of 2.5°wt.°% the nature of the spatial arrangement of nanoclusters on the surface of pores of the carbon carrier changes radically and the main elements of the structure are mass-fractal (dendritic) aggregates. The nanoclusters of nickel formed in the form of dendritic formations showed maximum catalytic activity in model reactions of hydrated protons recovery and isopropylbenzene hydrocracking. The use of proton-conducting membranes in isopropylbenzene hydrocracking reaction allowed to reduce temperature and pressure to 290°C and 4 MPa, respectively. The composition of reaction products has changed significantly. It is established that at reaction of interaction of hydrogen with the superfluous oxygen simulating process of operation of a cathode chamber of a fuel cell, the catalyst on the carrier with the condensed carbon skeleton shows catalytic activity in a range of temperatures 130-170 °С and twice above at 190-290 °С.