from first principles PP-I-1

PP-III-37Influence of the Electronic Properties of Palladium Particles Deposited onAlumina on the Reaction Mechanism of Hydrogenation of VinylacetyleneIlyasov I.R., Nazarov M.V., Laskin A.I., Mukhambetov I.N., Lamberov A.A.Kazan (Volga) Federal University, Kazan, Russiailildar@yandex.ruThe influence of the structural and electronic characteristics of nonpromoted Pd catalysts ontheir adsorption and catalytic properties is studied. It is shown that the conversion ofvinylacetylene depends on the dispersion of palladium for both types of catalysts synthesizedfrom acetate and acetylacetonate complexes. It is established that the selectivity ofvinylacetylene conversion into 1,3-butadiene on palladium acetate and acetylacetonatecatalysts depends on the state of the 3d-orbitals of surface Pd atoms. The palladium acetatecatalysts are characterized by a higher electron density on the 3d-orbital in comparison withthe acetylacetonate samples, thus producing higher selectivities of vinylacetylene conversioninto 1,3-butadiene.It is shown that the largest number of converted acetylene and diene hydrocarbonshydrogenated to 1-butene. At the same time for the samples synthesized using as the startingcompound of palladium acetylacetonate complex, there is a high selectivity (up to 40.9%)conversion of acetylenic hydrocarbons and 1,3-butadiene in 2-butenes, compared withsamples based on palladium acetate, which is probably due to the presence of palladiumparticles on the surface atoms with lower electron density in the 3d-orbitals valence,stabilizing -allyl intermediates, and catalytic hydrogenation reaction of a 1,4-addition withthe formation of 2-butene. The ratio of tr- and cis-butene increases with 6,3-8,3 to10,3-12,4 up. Increase the concentration of tr-C 4 H 8 due to higher thermodynamic stability ofthe tr-isomer of 1,3-butadiene and the absence of intramolecular transformation of cis- andtr--allyl intermediates.189