THEORETICAL INVESTIGATION OF THE HYDROGENATION PROCESS IN SINGLE- AND DOUBLE-LAYERED PYROLIZED ACRYL-NITRIL NANOPOLYMER

The article reports a theoretical quantum chemical study of the adsorption mechanisms in atomic and molecular hydrogen on the surface of an advanced polymeric material – pyrolized polyacrylonitrile (PPAN). Three variants of atomic hydrogen orientation and five variants of molecular hydrogen orientation over one− and two−layer PPAN surface have been considered. The variants differed in the positions of nitrogen atoms in the close vicinity of a selected adsorption center in the polymer. Potential adsorption energy profiles of atomic hydrogen and hydrogen molecules have been constructed and analyzed, and the main power and geometrical characteristics of the processes have been defined. Charge redistributions in the systems have been studied. We show that neither a hydrogen atom, nor a hydrogen molecule can be adsorbed over the hexagon center of single−layer PPAN surfaces, and in other cases chemical adsorption occurs. For adsorption over the surface of two−layer PPAN, any orientation variants of a hydrogen molecule are possible. A negative influence of nitrogen atom of the polymer surface on the efficiency of atomic hydrogen adsorption has been established, whereas its influence on the adsorption of molecular hydrogen is positive.

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