from first principles PP-I-1

PP-III-97Synthesis of Olefins from Carbon Oxides and Hydrogenon Iron-Manganese Nanosystems at Atmospheric PressureSerov Y.M., Sheshko T.F.Peoples Friendship University of Russia, Moscow, Russiasheshko@bk.ruAn important task for the creation of an industrial process of olefins synthesis from carbonoxides and hydrogen is the development of high-efficiency and low- carbonation catalyticsystems and to study the mechanism of this reaction. It is known [1-3] that the Fe-Mnbimetallic catalysts deposited on different carriers are very promising for obtaining olefinsfrom CO and H 2 . However, the published data on their use is inconclusive, but the mechanismof the influence of Mn on the formation of olefins is not fully understood. To furthercomplicate the task of optimization of such systems for use in the hydrogenation of mixturesof CO and CO 2 .To solve this problem were carried out two series of experiments. The first - thehydrogenation of CO was carried out on catalytic systems, which are iron nanoparticlesdeposited by plasma-chemical method on the surface of γ-Al 2 O 3 or Mn/Al 2 O 3 . The secondcatalyst systems have a layered structure and consisted of layers of Fe and Mn nanoparticlesin inert supporters and they were separated by an isolation.It was found that the selectivity to olefins increased significantly with the introduction ofmanganese in both types of catalysts. However, for the first series of catalysts, the yield ofproducts decreased significantly. When the Fe nanoparticles are separated by an insulatinglayer from the Mn, the conversion of reactants is comparable with the results obtained in theFe/ZrO 2 и Fe/Al 2 O 3 .The adsorption of hydrogen on iron can be either molecular or dissociative, the manganesehas practically no atomic hydrogen. С * and CH X -radicals formed by dissociative mechanismmay be hydrogenated on iron centers as to olefins and paraffins up. At the same time, some ofCH X - radicals can move through the gas phase to the surface of manganese. Since its surfacehas no atomic hydrogen, the further hydrogenation of CH X -radicals to alkanes does notoccur, and there is a joint recombination of these particles mainly to olefins.References:[1] G. P. Van der Laan and A. A. C. M. Beenackers, Catalysis Reviews. 41(1999), pp. 255–318.[2] Lapidus A.L., Krylova A.J. http://www.chem.msu.su/rus/jvho/2000-1/43.pdf, [in Russian].[3] Qinghong Zhang, Jincan Kang, Ye Wang. ChemCatChem 2010, 2, 1030 – 1058256