Multilayer Adsorption as a Possible Transition State in Heterogeneous Hydrogenation of C=C Double Bonds

Authors: V. Heral

Abstract:

Ideas about the mechanism of heterogeneous catalytic hydrogenation are diverse. The Horiuti-Polanyi mechanism is most often referred to base on the idea of a semi-hydrogenated state. In our opinion, it does not represent a satisfactory explanation of the hydrogenation mechanism because, for example, (1) It neglects the fact that the bond of atomic hydrogen to the metal surface is strongly polarized, (2) It does not explain why a surface deprived of atomic hydrogen (by thermal desorption or by alkyne) loses isomerization capabilities, but hydrogenation capabilities remain preserved, (3) It was observed that during the hydrogenation of 1-alkenes, the reaction can be of the 0th order to hydrogen and to the alkene at the same time, which is excluded during the competitive adsorption of both reactants on the catalyst surface. We offer an alternative mechanism that satisfactorily explains many of the ambiguities: It is the idea of an independent course of olefin isomerization, catalyzed by acidic atomic hydrogen bonded on the surface of the catalyst, in addition to the hydrogenation itself, in which a two-layer complex appears on the surface of the catalyst: olefin bound to the surface and molecular hydrogen bound to it in the second layer. The rate-determining step of hydrogenation is the conversion of this complex into the final product. In our opinion, the Horiuti-Polanyi mechanism is flawed, and we naturally think that our two-layer theory better describes the experimental findings.

Keywords: Acidity of hydrogenation catalyst, Horiuti-Polanyi, hydrogenation, two-layer hydrogenation.

References:

[1] Remy R., Lehrbuch der anorganischen Chemie, Vol. 2, Leipzig 1955
[2] Galwey A.K., Gwathmey A.T., Cunningham R.E., Advances in catalysis 10, 57 (1998)
[3] Iljushenko V.M., Shligin A.J., Izv. AN Kaz.SSR, Ser.Khim. 3,12 (1949)
[4] Parnes Z.N., Bolestova C.I., Kursanov D.N., Izv. AN SSSR Ser.Khhim. 1972, 1987, 1989
[5] Khrush A.P., Shilov A.E., Kinetika i Kataliz 10, 466 (1969)
[6] Hudlický M., Trojánek J., Preparativní reakce v organické chemii I – redukce a oxydace, NČAV Praha 1953
[7] Tuley S.F., Adams R., J.Am.Chem.Soc. 47, 3061 (1925)
[8] Adams R., Garvey B.S., J.Am.Chem.Soc. 48,447 (1926)
[9] Mitsui S., Nagahisa Y., Tomurura G., Shinoya M., Shokubai (Catalyst) 13, 74 (1968) - quoted in Siegel S., Advances in Catalysis 16, 123 (1966)
[10] Loewenthal H.J.E., Tetrahedron 6, 269 (1959) – quoted in Siegel S., Advances in Catalysis 16, 123 (1966)
[11] Siegel S., Smith G.V., J.Am.Chem.Soc. 82, 6082 (1960)
[12] Pierre Brun, Catalyse et catalyseurs en chimie organique, Masson 1970
[13] Tulupov V.A., Zhurnal fizicheskoi khimii 36, 1617 (1962)
[14] Khrush A.P., Shilov A.E., Kinetika i Kataliz 10, 466 (1969)
[15] Halpers J., Canad.J.Chem. 39, 1372 (1961)
[16] Halpers J., Canad.J.Chem. 44, 671 (1966)
[17] Hanzlík J., Chemicke Listy 65, 454 (1971)
[18] Boreskov G.K., Geterogennyi kataliz v khimicheskoi promyshlennosti, Goskhizdat Moskva 1955, p. 7
[19] Gostunskaya I.V., Trinko A.I., Dobroserdova N.S., Kazanskiy S.A., Neftekhimia 11, 326 (1971)
[20] Fasmah A.S., Ishanov Zh.A., Kinetika i Kataliz 8, 66 (1967)
[21] Bond C.C., Wells P.B., Advances in Catalysis 15, 91 (1964)
[22] Sokolskiy D.V., Gidrirovanie v rastvorach, Alma-Ata 1962
[23] Freidlin L.Kh., Kaup Yu.Yu., Litvin E.F., Ilomets T. I., Dokl.AN SSSR 143,883 (1962)
[24] Siegel S., Smith G.V., J.Am.Chem.Soc. 82, 6087 (1960)
[25] Young W.C., Weir R.S., Bollinger H., Kaplan L., Linder S.L., J.Am.Chem.Soc. 69, 2046 (1947)
[26] Taylor T.I., Dibeler V.H., J.Phys.Chem. 55, 1036 (1951)
[27] Burwell R.L.Jr., Chem.Rev. 57, 895 (1957)
[28] Smith V., J., Catalysis 5, 152 (1966)
[29] Loewental H.J.E., Tetrahedron 6, 269 (1958), quoted in Siegel S., Advances in Catalysis 16, 123 (1966)