Publications
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2013
Liu, Ying-Ya; Couck, Sarah; Vandichel, Matthias; Grzywa, Maciej; Leus, Karen; Biswas, Shyam; Vollmer, Dirk; Gascon, Jorge; Kapteijn, Freek; Denayer, Joeri F M; Waroquier, Michel; Speybroeck, Veronique Van; der Voort, Pascal Van
New V-IV-Based Metal-Organic Framework Having Framework Flexibility and High CO2 Adsorption Capacity Journal Article
In: INORGANIC CHEMISTRY, vol. 52, no. 1, pp. 113-120, 2013, ISSN: 0020-1669.
@article{ISI:000313220500016,
title = {New V-IV-Based Metal-Organic Framework Having Framework Flexibility and
High CO2 Adsorption Capacity},
author = {Ying-Ya Liu and Sarah Couck and Matthias Vandichel and Maciej Grzywa and Karen Leus and Shyam Biswas and Dirk Vollmer and Jorge Gascon and Freek Kapteijn and Joeri F M Denayer and Michel Waroquier and Veronique Van Speybroeck and Pascal Van der Voort},
doi = {10.1021/ic301338a},
issn = {0020-1669},
year = {2013},
date = {2013-01-01},
journal = {INORGANIC CHEMISTRY},
volume = {52},
number = {1},
pages = {113-120},
abstract = {A vanadium based metal organic framework (MOF), VO(BPDC) (BPDC2- =
biphenyl-4,4'-dicarboxylate), adopting an expanded MIL-47 structure
type, has been synthesized via solvothermal and microwave methods. Its
structural and gas/vapor sorption properties have been studied. This
compound displays a distinct breathing effect toward certain adsorptives
at workable temperatures. The sorption isotherms of CO2 and CH4 indicate
a different sorption behavior at specific temperatures. In situ
synchrotron X-ray powder diffraction measurements and molecular
simulations have been utilized to characterize the structural
transition. The experimental measurements clearly suggest the existence
of both narrow pore and large pore forms. A free energy profile along
the pore angle was computationally determined for the empty host
framework. Apart from a regular large pore and a regular narrow pore
form, an overstretched narrow pore form has also been found.
Additionally, a variety of spectroscopic techniques combined with N-2
adsorption/desorption isotherms measured at 77 K demonstrate that the
existence of the mixed oxidation states V-III/V-IV in the titled MOF
structure compared to pure V-IV increases the difficulty in triggering
the flexibility of the framework.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
biphenyl-4,4'-dicarboxylate), adopting an expanded MIL-47 structure
type, has been synthesized via solvothermal and microwave methods. Its
structural and gas/vapor sorption properties have been studied. This
compound displays a distinct breathing effect toward certain adsorptives
at workable temperatures. The sorption isotherms of CO2 and CH4 indicate
a different sorption behavior at specific temperatures. In situ
synchrotron X-ray powder diffraction measurements and molecular
simulations have been utilized to characterize the structural
transition. The experimental measurements clearly suggest the existence
of both narrow pore and large pore forms. A free energy profile along
the pore angle was computationally determined for the empty host
framework. Apart from a regular large pore and a regular narrow pore
form, an overstretched narrow pore form has also been found.
Additionally, a variety of spectroscopic techniques combined with N-2
adsorption/desorption isotherms measured at 77 K demonstrate that the
existence of the mixed oxidation states V-III/V-IV in the titled MOF
structure compared to pure V-IV increases the difficulty in triggering
the flexibility of the framework.
2012
Vandichel, Matthias; Leus, Karen; der Voort, Pascal Van; Waroquier, Michel; Speybroeck, Veronique Van
Mechanistic insight into the cyclohexene epoxidation with VO(acac)(2) and tert-butyl hydroperoxide Journal Article
In: JOURNAL OF CATALYSIS, vol. 294, pp. 1-18, 2012, ISSN: 0021-9517.
@article{ISI:000309314500001,
title = {Mechanistic insight into the cyclohexene epoxidation with VO(acac)(2)
and tert-butyl hydroperoxide},
author = {Matthias Vandichel and Karen Leus and Pascal Van der Voort and Michel Waroquier and Veronique Van Speybroeck},
doi = {10.1016/j.jcat.2012.06.002},
issn = {0021-9517},
year = {2012},
date = {2012-10-01},
journal = {JOURNAL OF CATALYSIS},
volume = {294},
pages = {1-18},
abstract = {The epoxidation reaction of cyclohexene is investigated for the
catalytic system vanadyl acetylacetonate (VO(acac)(2)) with tert-butyl
hydroperoxide (TBHP) as oxidant with the aim to identify the most active
species for epoxidation and to retrieve insight into the most plausible
epoxidation mechanism. The reaction mixture is composed of various
inactive and active complexes in which vanadium may either have
oxidation state +IV or +V. Inactive species are activated with TBHP to
form active complexes. After reaction with cyclohexene, each active
species transforms back into an inactive complex that may be reactivated
again. The reaction mixture is quite complex containing hydroxyl, acetyl
acetonate, acetate, or a tert-butoxide anion as ligands, and thus,
various ligand exchange reactions may occur among active and inactive
complexes. Also, radical decomposition reactions allow transforming V+IV
to V+V species. To obtain insight into the most abundant active
complexes, each of previous transformation steps has been modeled
through thermodynamic equilibrium steps. To unravel the nature of the
most plausible epoxidation mechanism, first principle chemical kinetics
calculations have been performed on all proposed epoxidation pathways.
Our results allow to conclude that the concerted Sharpless mechanism is
the preferred reaction mechanism and that alkylperoxo species
V+IVO(L)(OOtBu) and V+VO(L-1)(L-2)(OOtBu) species are most abundant. At
the onset of the catalytic cycle, vanadium +IV species may play an
active role, but as the reaction proceeds, reaction mechanisms that
involve vanadium +V species are preferred as the acetyl acetonate is
readily oxidized. Additionally, an experimental IR and kinetic study has
been performed to give a qualitative composition of the reaction mixture
and to obtain experimental kinetic data for comparison with our
theoretical values. The agreement between theory and experiment is
satisfactory. (C) 2012 Elsevier Inc. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
catalytic system vanadyl acetylacetonate (VO(acac)(2)) with tert-butyl
hydroperoxide (TBHP) as oxidant with the aim to identify the most active
species for epoxidation and to retrieve insight into the most plausible
epoxidation mechanism. The reaction mixture is composed of various
inactive and active complexes in which vanadium may either have
oxidation state +IV or +V. Inactive species are activated with TBHP to
form active complexes. After reaction with cyclohexene, each active
species transforms back into an inactive complex that may be reactivated
again. The reaction mixture is quite complex containing hydroxyl, acetyl
acetonate, acetate, or a tert-butoxide anion as ligands, and thus,
various ligand exchange reactions may occur among active and inactive
complexes. Also, radical decomposition reactions allow transforming V+IV
to V+V species. To obtain insight into the most abundant active
complexes, each of previous transformation steps has been modeled
through thermodynamic equilibrium steps. To unravel the nature of the
most plausible epoxidation mechanism, first principle chemical kinetics
calculations have been performed on all proposed epoxidation pathways.
Our results allow to conclude that the concerted Sharpless mechanism is
the preferred reaction mechanism and that alkylperoxo species
V+IVO(L)(OOtBu) and V+VO(L-1)(L-2)(OOtBu) species are most abundant. At
the onset of the catalytic cycle, vanadium +IV species may play an
active role, but as the reaction proceeds, reaction mechanisms that
involve vanadium +V species are preferred as the acetyl acetonate is
readily oxidized. Additionally, an experimental IR and kinetic study has
been performed to give a qualitative composition of the reaction mixture
and to obtain experimental kinetic data for comparison with our
theoretical values. The agreement between theory and experiment is
satisfactory. (C) 2012 Elsevier Inc. All rights reserved.
Vanduyfhuys, L; Verstraelen, T; Vandichel, M; Waroquier, M; Speybroeck, V Van
Ab Initio Parametrized Force Field for the Flexible Metal-Organic Framework MIL-53(Al) Journal Article
In: JOURNAL OF CHEMICAL THEORY AND COMPUTATION, vol. 8, no. 9, pp. 3217-3231, 2012, ISSN: 1549-9618.
@article{ISI:000308830700026,
title = {Ab Initio Parametrized Force Field for the Flexible Metal-Organic
Framework MIL-53(Al)},
author = {L Vanduyfhuys and T Verstraelen and M Vandichel and M Waroquier and V Van Speybroeck},
doi = {10.1021/ct300172m},
issn = {1549-9618},
year = {2012},
date = {2012-09-01},
journal = {JOURNAL OF CHEMICAL THEORY AND COMPUTATION},
volume = {8},
number = {9},
pages = {3217-3231},
abstract = {A force field is proposed for the flexible metal-organic framework
MIL-53(Al), which is calibrated using density functional theory
calculations on nonperiodic clusters. The force field has three main
contributions: an electrostatic term based on atomic charges derived
with a modified Hirshfeld-I method, a van der Waals (vdW) term with
parameters taken from the MM3 model, and a valence force field whose
parameters were estimated with a new methodology that uses the gradients
and Hessian matrix elements retrieved from nonperiodic cluster
calculations. The new force field predicts geometries and cell
parameters that compare well with the experimental values both for the
large and narrow pore phases. The energy profile along the breathing
mode of the empty material reveals the existence of two minima, which
confirms the intrinsic bistable behavior of the MIL-53. Even without the
stimulus of external guest molecules, the material may transform from
the large pore (lp) to the narrow pore (np) phase [Liu et al. J. Am.
Chem. Soc. 2008, 120, 11813]. The relative stability of the two phases
critically depends on the vdW parameters, and the MM3 dispersion
interaction has the tendency to overstabilize the np phase.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
MIL-53(Al), which is calibrated using density functional theory
calculations on nonperiodic clusters. The force field has three main
contributions: an electrostatic term based on atomic charges derived
with a modified Hirshfeld-I method, a van der Waals (vdW) term with
parameters taken from the MM3 model, and a valence force field whose
parameters were estimated with a new methodology that uses the gradients
and Hessian matrix elements retrieved from nonperiodic cluster
calculations. The new force field predicts geometries and cell
parameters that compare well with the experimental values both for the
large and narrow pore phases. The energy profile along the breathing
mode of the empty material reveals the existence of two minima, which
confirms the intrinsic bistable behavior of the MIL-53. Even without the
stimulus of external guest molecules, the material may transform from
the large pore (lp) to the narrow pore (np) phase [Liu et al. J. Am.
Chem. Soc. 2008, 120, 11813]. The relative stability of the two phases
critically depends on the vdW parameters, and the MM3 dispersion
interaction has the tendency to overstabilize the np phase.
Ghysels, An; Vandichel, Matthias; Verstraelen, Toon; van der Veen, Monique A; Vos, Dirk E De; Waroquier, Michel; Speybroeck, Veronique Van
Host-guest and guest-guest interactions between xylene isomers confined in the MIL-47(V) pore system Journal Article
In: THEORETICAL CHEMISTRY ACCOUNTS, vol. 131, no. 7, 2012, ISSN: 1432-881X.
@article{ISI:000307274300002,
title = {Host-guest and guest-guest interactions between xylene isomers confined
in the MIL-47(V) pore system},
author = {An Ghysels and Matthias Vandichel and Toon Verstraelen and Monique A van der Veen and Dirk E De Vos and Michel Waroquier and Veronique Van Speybroeck},
doi = {10.1007/s00214-012-1234-7},
issn = {1432-881X},
year = {2012},
date = {2012-07-01},
journal = {THEORETICAL CHEMISTRY ACCOUNTS},
volume = {131},
number = {7},
abstract = {The porous MIL-47 material shows a selective adsorption behavior for
para-, ortho-, and meta-isomers of xylenes, making the material a
serious candidate for separation applications. The origin of the
selectivity lies in the differences in interactions (energetic) and
confining (entropic). This paper investigates the xylene-framework
interactions and the xylene-xylene interactions with quantum mechanical
calculations, using a dispersion-corrected density functional and
periodic boundary conditions to describe the crystal. First, the
strength and geometrical characteristics of the optimal xylene-xylene
interactions are quantified by studying the pure and mixed pairs in gas
phase. An extended set of initial structures is created and optimized to
sample as many relative orientations and distances as possible. Next,
the pairs are brought in the pores of MIL-47. The interaction with the
terephthalic linkers and other xylenes increases the stacking energy in
gas phase (-31.7 kJ/mol per pair) by roughly a factor four in the fully
loaded state (-58.3 kJ/mol per xylene). Our decomposition of the
adsorption energy shows various trends in the contributing xylene-xylene
interactions. The absence of a significant difference in energetics
between the isomers indicates that entropic effects must be mainly
responsible for the separation behavior.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
para-, ortho-, and meta-isomers of xylenes, making the material a
serious candidate for separation applications. The origin of the
selectivity lies in the differences in interactions (energetic) and
confining (entropic). This paper investigates the xylene-framework
interactions and the xylene-xylene interactions with quantum mechanical
calculations, using a dispersion-corrected density functional and
periodic boundary conditions to describe the crystal. First, the
strength and geometrical characteristics of the optimal xylene-xylene
interactions are quantified by studying the pure and mixed pairs in gas
phase. An extended set of initial structures is created and optimized to
sample as many relative orientations and distances as possible. Next,
the pairs are brought in the pores of MIL-47. The interaction with the
terephthalic linkers and other xylenes increases the stacking energy in
gas phase (-31.7 kJ/mol per pair) by roughly a factor four in the fully
loaded state (-58.3 kJ/mol per xylene). Our decomposition of the
adsorption energy shows various trends in the contributing xylene-xylene
interactions. The absence of a significant difference in energetics
between the isomers indicates that entropic effects must be mainly
responsible for the separation behavior.
der Mynsbrugge, Jeroen Van; Hemelsoet, Karen; Vandichel, Matthias; Waroquier, Michel; Speybroeck, Veronique Van
Efficient Approach for the Computational Study of Alcohol and Nitrile Adsorption in H-ZSM-5 Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 116, no. 9, pp. 5499-5508, 2012, ISSN: 1932-7447.
@article{ISI:000301315700028,
title = {Efficient Approach for the Computational Study of Alcohol and Nitrile
Adsorption in H-ZSM-5},
author = {Jeroen Van der Mynsbrugge and Karen Hemelsoet and Matthias Vandichel and Michel Waroquier and Veronique Van Speybroeck},
doi = {10.1021/jp2123828},
issn = {1932-7447},
year = {2012},
date = {2012-03-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {116},
number = {9},
pages = {5499-5508},
abstract = {Since many industrially important processes start with the adsorption of
guest molecules inside the pores of an acidic zeolite catalyst, a proper
estimate of the adsorption enthalpy is of paramount importance. In this
contribution, we report ab initio calculations on the adsorption of
water, alcohols, and nitriles at the bridging Bronsted sites of H-ZSM-5,
using both cluster and periodic models to account for the zeolite
environment. Stabilization of the adsorption complexes results from
hydrogen bonding between the guest molecule and the framework, as well
as from embedding, i.e., van der Waals interactions with the pore walls.
Large-cluster calculations with different DFT methods, in particular
B3LYP(-D), PBE(-D), M062X(-D), and omega B97X-D, are tested for their
ability to reproduce the experimental heats of adsorption available in
the literature (J. Phys. Chem. B 1997, 101, 3811-3817). A proper account
of dispersion interactions is found to be crucial to describe the
experimental trend across a series of adsorbates of increasing size,
i.e., an increase in adsorption enthalpy by 10-15 kJ/mol for each
additional carbon atom. The extended-cluster model is shown to offer an
attractive alternative to periodic simulations on the entire H-ZSM-5
unit cell, resulting in virtually identical final adsorption enthalpies.
Comparing calculated stretch frequencies of the zeolite acid sites and
the adsorbate functional groups with experimental IR data additionally
confirms that the cluster approach provides an appropriate
representation of the adsorption complexes.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
guest molecules inside the pores of an acidic zeolite catalyst, a proper
estimate of the adsorption enthalpy is of paramount importance. In this
contribution, we report ab initio calculations on the adsorption of
water, alcohols, and nitriles at the bridging Bronsted sites of H-ZSM-5,
using both cluster and periodic models to account for the zeolite
environment. Stabilization of the adsorption complexes results from
hydrogen bonding between the guest molecule and the framework, as well
as from embedding, i.e., van der Waals interactions with the pore walls.
Large-cluster calculations with different DFT methods, in particular
B3LYP(-D), PBE(-D), M062X(-D), and omega B97X-D, are tested for their
ability to reproduce the experimental heats of adsorption available in
the literature (J. Phys. Chem. B 1997, 101, 3811-3817). A proper account
of dispersion interactions is found to be crucial to describe the
experimental trend across a series of adsorbates of increasing size,
i.e., an increase in adsorption enthalpy by 10-15 kJ/mol for each
additional carbon atom. The extended-cluster model is shown to offer an
attractive alternative to periodic simulations on the entire H-ZSM-5
unit cell, resulting in virtually identical final adsorption enthalpies.
Comparing calculated stretch frequencies of the zeolite acid sites and
the adsorbate functional groups with experimental IR data additionally
confirms that the cluster approach provides an appropriate
representation of the adsorption complexes.
Vermoortele, Frederik; Vandichel, Matthias; de Voorde, Ben Van; Ameloot, Rob; Waroquier, Michel; Speybroeck, Veronique Van; Vos, Dirk E De
Electronic Effects of Linker Substitution on Lewis Acid Catalysis with Metal-Organic Frameworks Journal Article
In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, vol. 51, no. 20, pp. 4887-4890, 2012, ISSN: 1433-7851.
@article{ISI:000303925200019,
title = {Electronic Effects of Linker Substitution on Lewis Acid Catalysis with
Metal-Organic Frameworks},
author = {Frederik Vermoortele and Matthias Vandichel and Ben Van de Voorde and Rob Ameloot and Michel Waroquier and Veronique Van Speybroeck and Dirk E De Vos},
doi = {10.1002/anie.201108565},
issn = {1433-7851},
year = {2012},
date = {2012-01-01},
journal = {ANGEWANDTE CHEMIE-INTERNATIONAL EDITION},
volume = {51},
number = {20},
pages = {4887-4890},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Leus, Karen; Vandichel, Matthias; Liu, Ying-Ya; Muylaert, Ilke; Musschoot, Jan; Pyl, Steven; Vrielinck, Henk; Callens, Freddy; Marin, Guy B; Detavernier, Christophe; Wiper, Paul V; Khimyak, Yaroslav Z; Waroquier, Michel; Speybroeck, Veronique Van; der Voort, Pascal Van
The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene Journal Article
In: JOURNAL OF CATALYSIS, vol. 285, no. 1, pp. 196-207, 2012, ISSN: 0021-9517.
@article{ISI:000300074300022,
title = {The coordinatively saturated vanadium MIL-47 as a low leaching
heterogeneous catalyst in the oxidation of cyclohexene},
author = {Karen Leus and Matthias Vandichel and Ying-Ya Liu and Ilke Muylaert and Jan Musschoot and Steven Pyl and Henk Vrielinck and Freddy Callens and Guy B Marin and Christophe Detavernier and Paul V Wiper and Yaroslav Z Khimyak and Michel Waroquier and Veronique Van Speybroeck and Pascal Van der Voort},
doi = {10.1016/j.jcat.2011.09.014},
issn = {0021-9517},
year = {2012},
date = {2012-01-01},
journal = {JOURNAL OF CATALYSIS},
volume = {285},
number = {1},
pages = {196-207},
abstract = {A Metal Organic Framework, containing coordinatively saturated sites
linked together by terephthalic linkers (V-MIL-47), is evaluated as a
catalyst in the epoxidation of cyclohexene. Different solvents and
conditions are tested and compared. If the oxidant TBHP is dissolved in
water, a significant leaching of V-species into the solution is
observed, and also radical pathways are prominently operative leading to
the formation of an adduct between the peroxide and cyclohexene. If,
however, the oxidant is dissolved in decane, leaching is negligible and
the structural integrity of the V-MIL-47 is maintained during successive
runs. The selectivity toward the epoxide is very high in these
circumstances. Extensive computational modeling is performed to show
that several reaction cycles are possible. EPR and NMR measurements
confirm that at least two parallel catalytic cycles are co-existing: one
with V+IV sites and one with pre-oxidized V+V sites, and this is in
complete agreement with the theoretical predictions. (C) 2011 Elsevier
Inc. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
linked together by terephthalic linkers (V-MIL-47), is evaluated as a
catalyst in the epoxidation of cyclohexene. Different solvents and
conditions are tested and compared. If the oxidant TBHP is dissolved in
water, a significant leaching of V-species into the solution is
observed, and also radical pathways are prominently operative leading to
the formation of an adduct between the peroxide and cyclohexene. If,
however, the oxidant is dissolved in decane, leaching is negligible and
the structural integrity of the V-MIL-47 is maintained during successive
runs. The selectivity toward the epoxide is very high in these
circumstances. Extensive computational modeling is performed to show
that several reaction cycles are possible. EPR and NMR measurements
confirm that at least two parallel catalytic cycles are co-existing: one
with V+IV sites and one with pre-oxidized V+V sites, and this is in
complete agreement with the theoretical predictions. (C) 2011 Elsevier
Inc. All rights reserved.
Leus, Karen; Couck, Sarah; Vandichel, Matthias; Vanhaelewyn, Gauthier; Liu, Ying-Ya; Marin, Guy B; Driessche, Isabel Van; Depla, Diederik; Waroquier, Michel; Speybroeck, Veronique Van; Denayer, Joeri F M; Voort, Pascal Van Der
Synthesis, characterization and sorption properties of NH2-MIL-47 Journal Article
In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, vol. 14, no. 44, pp. 15562-15570, 2012, ISSN: 1463-9076.
@article{ISI:000310153300037,
title = {Synthesis, characterization and sorption properties of NH2-MIL-47},
author = {Karen Leus and Sarah Couck and Matthias Vandichel and Gauthier Vanhaelewyn and Ying-Ya Liu and Guy B Marin and Isabel Van Driessche and Diederik Depla and Michel Waroquier and Veronique Van Speybroeck and Joeri F M Denayer and Pascal Van Der Voort},
doi = {10.1039/c2cp42137b},
issn = {1463-9076},
year = {2012},
date = {2012-01-01},
journal = {PHYSICAL CHEMISTRY CHEMICAL PHYSICS},
volume = {14},
number = {44},
pages = {15562-15570},
abstract = {An amino functionalized vanadium-containing Metal Organic Framework,
NH2-MIL-47, has been synthesized by a hydrothermal reaction in an
autoclave. Alternatively, a synthesis route via microwave enhanced
irradiation has been optimized to accelerate the synthesis. The
NH2-MIL-47 exhibits the same topology as MIL-47, in which the V center
is octahedrally coordinated. After an exchange procedure in DMF the
V+III center is oxidized to V+IV, which is confirmed by EPR and XPS
measurements. The CO2 and CH4 adsorption properties have been evaluated
and compared to MIL-47, showing that both MOFs have an almost similar
adsorption capacity and affinity for CO2. DFT-based molecular modeling
calculations were performed to obtain more insight into the adsorption
positions for CO2 in NH2-MIL-47. Furthermore our calculated adsorption
enthalpies agree well with the experimental values.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
NH2-MIL-47, has been synthesized by a hydrothermal reaction in an
autoclave. Alternatively, a synthesis route via microwave enhanced
irradiation has been optimized to accelerate the synthesis. The
NH2-MIL-47 exhibits the same topology as MIL-47, in which the V center
is octahedrally coordinated. After an exchange procedure in DMF the
V+III center is oxidized to V+IV, which is confirmed by EPR and XPS
measurements. The CO2 and CH4 adsorption properties have been evaluated
and compared to MIL-47, showing that both MOFs have an almost similar
adsorption capacity and affinity for CO2. DFT-based molecular modeling
calculations were performed to obtain more insight into the adsorption
positions for CO2 in NH2-MIL-47. Furthermore our calculated adsorption
enthalpies agree well with the experimental values.
2011
Speybroeck, Veronique Van; der Mynsbrugge, Jeroen Van; Vandichel, Matthias; Hemelsoet, Karen; Lesthaeghe, David; Ghysels, An; Marin, Guy B; Waroquier, Michel
First Principle Kinetic Studies of Zeolite-Catalyzed Methylation Reactions Journal Article
In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, vol. 133, no. 4, pp. 888-899, 2011, ISSN: 0002-7863.
@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}
}
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.
Lesthaeghe, David; der Mynsbrugge, Jeroen Van; Vandichel, Matthias; Waroquier, Michel; Speybroeck, Veronique Van
Full Theoretical Cycle for both Ethene and Propene Formation during Methanol-to-Olefin Conversion in H-ZSM-5 Journal Article
In: CHEMCATCHEM, vol. 3, no. 1, pp. 208-212, 2011, ISSN: 1867-3880.
@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}
}
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.
2010
Vandichel, Matthias; Lesthaeghe, David; der Mynsbrugge, Jeroen Van; Waroquier, Michel; Speybroeck, Veronique Van
Assembly of cyclic hydrocarbons from ethene and propene in acid zeolite catalysis to produce active catalytic sites for MTO conversion Journal Article
In: JOURNAL OF CATALYSIS, vol. 271, no. 1, pp. 67-78, 2010, ISSN: 0021-9517.
@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}
}
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.
Leus, Karen; Muylaert, Ilke; Vandichel, Matthias; Marin, Guy B; Waroquier, Michel; Speybroeck, Veronique Van; der Voort, Pascal Van
The remarkable catalytic activity of the saturated metal organic framework V-MIL-47 in the cyclohexene oxidation Journal Article
In: CHEMICAL COMMUNICATIONS, vol. 46, no. 28, pp. 5085-5087, 2010, ISSN: 1359-7345.
@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}
}
framework MIL-47 in the epoxidation of cyclohexene is elucidated by
means of both experimental results and theoretical calculations.
2009
Hemelsoet, Karen; Nollet, Arno; Vandichel, Matthias; Lesthaeghe, David; Speybroeck, Veronique Van; Waroquier, Michel
The Effect of Confined Space on the Growth of Naphthalenic Species in a Chabazite-Type Catalyst: A Molecular Modeling Study Journal Article
In: CHEMCATCHEM, vol. 1, no. 3, pp. 373-378, 2009, ISSN: 1867-3880.
@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}
}
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.