@article{ISI:000287295300051,

title = {First Principle Kinetic Studies of Zeolite-Catalyzed Methylation 

 Reactions},

author = {Veronique Van Speybroeck and Jeroen Van der Mynsbrugge and Matthias Vandichel and Karen Hemelsoet and David Lesthaeghe and An Ghysels and Guy B Marin and Michel Waroquier},

doi = {10.1021/ja1073992},

issn = {0002-7863},

year  = {2011},

date = {2011-02-01},

journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY},

volume = {133},

number = {4},

pages = {888-899},

abstract = {Methylations of ethene, propene, and butene by methanol over the acidic 

 microporous H-ZSM-5 catalyst are studied by means of state of the art 

 computational techniques, to derive Arrhenius plots and rate constants 

 from first principles that can directly be compared with the 

 experimental data. For these key elementary reactions in the methanol to 

 hydrocarbons (MTH) process, direct kinetic data became available only 

 recently [J. Catal. 2005, 224, 115-123; J. Catal. 2005, 234, 385-400]. 

 At 350 degrees C, apparent activation energies of 103, 69, and 45 kJ/mol 

 and rate constants of 2.6 x 10(-4), 4.5 x 10(-3), and 1.3 x 10(-2) 

 mol/(g h mbar) for ethene, propene, and butene were ;derived, giving 

 following relative ratios for methylation k(ethene)/k(propene)/k(butene) = 1:17:50. In this work, rate constants including pre-exponential 

 factors are calculated which give very good agreement with the 

 experimental data: apparent activation energies of 94, 62, and 37 kJ/mol 

 for ethene, propene, and butene are found, and relative ratios of methylation k(ethene)/k(propene)/k(butene) = 1:23:763. The entropies of 

 gas phase alkenes are underestimated in the harmonic oscillator 

 approximation due to the occurrence of internal rotations. These low 

 vibrational modes were substituted by manually constructed partition 

 functions. Overall, the absolute reaction rates can be calculated with 

 near chemical accuracy, and qualitative trends are very well reproduced. 

 In addition, the proposed scheme is computationally very efficient and 

 constitutes significant progress in kinetic modeling of reactions in 

 heterogeneous catalysis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000285888500026,

title = {Full Theoretical Cycle for both Ethene and Propene Formation during 

 Methanol-to-Olefin Conversion in H-ZSM-5},

author = {David Lesthaeghe and Jeroen Van der Mynsbrugge and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1002/cctc.201000286},

issn = {1867-3880},

year  = {2011},

date = {2011-01-01},

journal = {CHEMCATCHEM},

volume = {3},

number = {1},

pages = {208-212},

abstract = {The methanol-to-olefin (MTO) process, catalyzed by acidic zeolites such 

 as H-ZSM-5, provides an increasingly important alternative to the 

 production of light olefins from crude oil. However, the various 

 mechanistic proposals for methanol-to-olefin conversion have been 

 strongly disputed for the past several decades. This work provides 

 theoretical evidence that the experimentally suggested `alkene cycle', 

 part of a co-catalytic hydrocarbon pool, offers a viable path to the 

 production of both propene and ethene, in stark contrast to the 

 often-proposed direct mechanisms. This specific proposal hinges on 

 repeated methylation reactions of alkenes, starting from propene, which 

 occur easily within the zeolite environment. Subsequent cracking steps 

 regenerate the original propene molecule, while also forming new propene 

 and ethene molecules as primary products. Because the host framework 

 stabilizes intermediate carbenium ions, isomerization and de-protonation 

 reactions are extremely fast. Combined with earlier joint experimental 

 and theoretical work on polymethylbenzenes as active hydrocarbon pool 

 species, it is clear that, in zeolite H-ZSM-5, multiple parallel and 

 interlinked routes operate on a competitive basis.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000277217500008,

title = {Assembly of cyclic hydrocarbons from ethene and propene in acid zeolite 

 catalysis to produce active catalytic sites for MTO conversion},

author = {Matthias Vandichel and David Lesthaeghe and Jeroen Van der Mynsbrugge and Michel Waroquier and Veronique Van Speybroeck},

doi = {10.1016/j.jcat.2010.02.001},

issn = {0021-9517},

year  = {2010},

date = {2010-04-01},

journal = {JOURNAL OF CATALYSIS},

volume = {271},

number = {1},

pages = {67-78},

abstract = {The formation of cyclic hydrocarbons from smaller building blocks such 

 as ethene and propene is investigated in protonated ZSM-5, using a 

 2-layered ONIOM(B3LYP/6-31+g(d):HF/6-31+g(d)) approach and an additional 

 Grimme-type van der Waals dispersion correction term to account for the 

 long-range dispersion interactions. These cyclic species form precursors 

 for active hydrocarbon pool species and play a key role in activating 

 the acidic zeolite host for successful methanol-to-olefin (MTO) 

 conversion. Starting from trace amounts of ethene and propene that are 

 formed during an initial induction period or during the active phase, 

 dimerization reactions allow for rapid chain growth. The products of 

 these reactions can be neutral alkenes, framework-bound alkoxide species 

 or intermediate carbenium ions, depending on the zeolite environment 

 taken into account. On the basis of rate constants for successive 

 reaction steps, a viable route toward cyclization is proposed, which 

 starts from the formation of a framework-bound propoxide from propene, 

 followed by dimerization with an additional propene molecule to form the 

 2-hexyl carbenium ion which finally undergoes ring closure to yield 

 methylcyclopentane. This cyclic species in turn forms a precursor for 

 either an active hydrocarbon pool compound or for deactivating coke 

 deposit. (C) 2010 Elsevier Inc. All rights reserved.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000279565500010,

title = {The remarkable catalytic activity of the saturated metal organic 

 framework V-MIL-47 in the cyclohexene oxidation},

author = {Karen Leus and Ilke Muylaert and Matthias Vandichel and Guy B Marin and Michel Waroquier and Veronique Van Speybroeck and Pascal Van der Voort},

doi = {10.1039/c0cc01506g},

issn = {1359-7345},

year  = {2010},

date = {2010-01-01},

journal = {CHEMICAL COMMUNICATIONS},

volume = {46},

number = {28},

pages = {5085-5087},

abstract = {The remarkable catalytic activity of the saturated metal organic 

 framework MIL-47 in the epoxidation of cyclohexene is elucidated by 

 means of both experimental results and theoretical calculations.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{ISI:000274154100006,

title = {The Effect of Confined Space on the Growth of Naphthalenic Species in a 

 Chabazite-Type Catalyst: A Molecular Modeling Study},

author = {Karen Hemelsoet and Arno Nollet and Matthias Vandichel and David Lesthaeghe and Veronique Van Speybroeck and Michel Waroquier},

doi = {10.1002/cctc.200900208},

issn = {1867-3880},

year  = {2009},

date = {2009-11-01},

journal = {CHEMCATCHEM},

volume = {1},

number = {3},

pages = {373-378},

abstract = {Methylation reactions of naphthalenic species over the acidic 

 microporous zeolite with chabazite topology have been investigated by 

 means of two-layered ab initio computations. Large cluster results 

 combined with van der Waals contributions provide thermodynamic and 

 kinetic results of successive methylation steps. The growth of fused 

 bicyclic species is important as these can act as hydrocarbon pool 

 species within the methanol-to-olefin (MTO) process, but ultimately 

 leads to the deactivation of the catalyst. The influence of the confined 

 space of the zeolite pore on the resulting transition state or product 

 shape selectivity is investigated in detail.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}