A quantum-chemical study of hydride transfer in catalytic transformations of paraffins on zeolites. Pathways through adsorbed nonclassical carbonium ions

A quantum-chemical investigation of the hydride transfer reaction in catalytic transformations of hydrocarbons on zeolites has been performed. Ab initio calculations at the MP2/6-31++G**//HF/6-31G* level demonstrated that the activated complexes of hydride transfer reaction in catalytic transformations of paraffins on zeolites very much resemble adsorbed nonclassical carbonium ions. However, these transient species are strongly held at the surface active sites by the Coulomb interaction. The calculated activation energies for reactions involving propane and isobutane are in a reasonable agreement with the experimental data.

[1]  Warren J. Hehre,et al.  AB INITIO Molecular Orbital Theory , 1986 .

[2]  A. Corma,et al.  Ab initio molecular orbital calculations of the protonation reaction of propylene and isobutene by acidic OH groups of isomorphously substituted zeolites , 1993 .

[3]  D. B. Ferguson,et al.  Physical Organic Chemistry of Solid Acids: Lessons from in situ NMR and Theoretical Chemistry , 1996 .

[4]  J. Bornais,et al.  Exchange Reactions of the t-Butyl Cation , 1971 .

[5]  A. Corma,et al.  The Role of Reaction Temperature and Cracking Catalyst Characteristics in Determining the Relative Rates of Protolytic Cracking, Chain Propagation, and Hydrogen Transfer , 1994 .

[6]  M. Allavena,et al.  Calculation of the Reaction of Ethylene, Propene, and Acetylene on Zeolite Models , 1996 .

[7]  V. Kazansky,et al.  Quantum chemical studies of ethylene interaction with zeolite OH-groups , 1991 .

[8]  G. Kramer,et al.  Understanding the acid behaviour of zeolites from theory and experiment , 1993, Nature.

[9]  S. Blaszkowski,et al.  Activation of C-H and C-C Bonds by an Acidic Zeolite: A Density Functional Study , 1996 .

[10]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[11]  A. Jansen,et al.  Density functional theory calculations of the transition states for hydrogen exchange and dehydrogenation of methane by a Brönsted zeolitic proton , 1994 .

[12]  V. B. Kazanskii.  The nature of adsorbed carbenium ions as active intermediates in catalysis by solid acids , 1991 .

[13]  J. Sauer,et al.  Interaction of methanol with Broensted acid sites of zeolite catalysts: an ab initio study , 1995 .

[14]  R. A. Santen,et al.  A quantum-chemical study of adsorbed nonclassical carbonium ions as active intermediates in catalytic transformations of paraffins. I. Protolytic cracking of ethane on high silica zeolites , 1994 .

[15]  J. Dwyer,et al.  Brønsted acid strength in US-Y: FTIR study of CO adsorption , 1994 .

[16]  A. Corma,et al.  Activation of Hydrogen on Zeolites: Kinetics and Mechanism of n-Heptane Cracking on H-ZSM-5 Zeolites Under High Hydrogen Pressure , 1995 .

[17]  S. Blaszkowski,et al.  The mechanism of dimethyl ether formation from methanol catalyzed by zeolitic protons , 1996 .

[18]  Joachim Sauer,et al.  Theoretical Study of van der Waals Complexes at Surface Sites in Comparison with the Experiment , 1994 .

[19]  R. A. Santen,et al.  A quantum-chemical study of adsorbed nonclassical carbonium ions as active intermediates in catalytic transformations of paraffins. II. Protolytic dehydrogenation and hydrogen-deuterium hetero-isotope exchange of paraffins on high-silica zeolites , 1994 .

[20]  J. A. Speed,et al.  Reactions of propene on zeolite HY catalyst studied by in situ variable-temperature solid-state nuclear magnetic resonance spectroscopy , 1989 .

[21]  H. Bernhard Schlegel,et al.  An improved algorithm for reaction path following , 1989 .

[22]  C. Breneman,et al.  Determining atom‐centered monopoles from molecular electrostatic potentials. The need for high sampling density in formamide conformational analysis , 1990 .

[23]  J. Dumesic,et al.  Isobutane Cracking over Y-Zeolites: I. Development of a Kinetic-Model , 1995 .

[24]  V. Kazansky,et al.  Quantum chemical study of the electronic structure and geometry of surface alkoxy groups as probable active intermediates of heterogeneous acidic catalysts: What are the adsorbed carbenium ions? , 1989 .

[25]  L. Curtiss,et al.  Ab initio molecular orbital cluster studies of the zeolite ZSM-5. 1. Proton affinities , 1993 .

[26]  S. J. Collins,et al.  The mechanism of alkane activation over zeolite Brønsted acid sites. A density-functional study , 1995 .

[27]  R. Gorte,et al.  Carbon-13 NMR identification of intermediates formed by 2-methyl-2-propanol adsorption in H-ZSM-5 , 1989 .

[28]  G. Kramer,et al.  Reactivity Theory of Zeolitic Broensted Acidic Sites , 1995 .

[29]  A. Corma,et al.  Catalytic Cracking: Catalysts, Chemistry and Kinetics , 1986 .

[30]  M. Payne,et al.  Methanol Adsorption in ZeolitesA First-Principles Study , 1996 .

[31]  J. Nicholas,et al.  Kinetic NMR and density functional study of benzene H/D exchange in zeolites, the most simple aromatic substitution , 1995 .

[32]  S. Bates,et al.  Ab initio study of methanol sorption and proton transfer on a zeolite acid site model , 1994 .

[33]  M. Boczar,et al.  Heterogeneity of OH groups in NaHZSM-5 zeolite studied by infrared spectroscopy , 1988 .

[34]  V. Kazansky,et al.  Quantumchemical study of the isobutane cracking on zeolites , 1996 .