Center for Molecular Modeling - BOF-ERC I/00057/02

Metal-organic and covalent organic frameworks as single-site catalysts

sven — Fri, 13 Jan 2017 12:53:35 +0000

S.M.J. Rogge, A. Bavykina, J. Hajek, H. Garcia, A.I. Olivos-Suarez, A. Sepúlveda-Escribano, A. Vimont, G. Clet, P. Bazin, F. Kapteijn, M. Daturi, E.V. Ramos-Fernandez, F.X. Llabres i Xamena, V. Van Speybroeck, J. Gascon

Chemical Society Reviews

46 (11), 3134-3184

2017

Abstract

Heterogeneous single-site catalysts consist of isolated, well-defined, active sites that are spatially separated in a given solid and, ideally, structurally identical. In this review, the potential of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) as platforms for the development of heterogeneous single-site catalysts is reviewed thoroughly. In the first part of this article, synthetic strategies and progress in the implementation of such sites in these two classes of materials are discussed. Because these solids are excellent playgrounds to allow a better understanding of catalytic functions, we highlight the most important recent advances in the modelling and spectroscopic characterization of single-site catalysts based on these materials. Finally, we discuss the potential of MOFs as materials in which several single-site catalytic functions can be combined within one framework along with their potential as powerful enzyme-mimicking materials. The review is wrapped up with our personal vision on future research directions.

Open Access version available at UGent repository

Gold Open Access

DOI

http://dx.doi.org/10.1039/C7CS00033B

Private attachment

Rogge_MOF_2017.pdf

Aliovalent doping of CeO2: DFT study of oxidation state and vacancy effects

danny — Thu, 03 Jul 2014 14:02:03 +0000

D.E.P. Vanpoucke, P. Bultinck, S. Cottenier, V. Van Speybroeck, I. Van Driessche

Journal of Materials Chemistry A

2 (3), 13723-13737

2014

Abstract

The modification of CeO₂ properties by means of aliovalent doping is investigated within the ab initio density functional theory framework. Lattice parameters, dopant atomic radii, bulk moduli and thermal expansion coefficients of fluorite type Ce_1-xM_xO_2-y (with M = Mg, V, Co, Cu, Zn, Nb, Ba, La, Sm, Gd, Yb, and Bi) are presented for 0.00 < x < 0.25. The relative stability of the doped systems is discussed, and the influence of oxygen vacancies is investigated. It is shown that oxygen vacancies tend to increase the lattice parameter, and strongly decrease the bulk modulus. Defect formation energies are correlated with calculated crystal radii and covalent radii of the dopants, and are shown to present no simple trend. The previously observed inverse relationship between the thermal expansion coefficient and the bulk modulus in group IV doped CeO2 [J. Am. Ceram. Soc., 2014, 97(1), 258] is shown to persist independent of the inclusion of charge compensating vacancies.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1039/c4ta02449d

Private attachment

14_JMatChem_2,13723_Vanpoucke.pdf

Flexibility versus rigidity: what determines the stability of zeolite frameworks? A case study

michel — Tue, 29 Apr 2014 19:07:20 +0000

E. Verheyen, L. Joos, C. Martineau, C.J. Dawson, C. Weidenthaler, W. Schmidt, R. Yuan, E. Breynaerts, V. Van Speybroeck, M. Waroquier, F. Taulelle, M.M.J. Treacy, J.A. Martens, C. Kirschhock

Materials Horizons

Vol. 1 , 582 - 587

2014

Abstract

All silica COK-14/-COK-14 with OKO topology is the first case of a zeolite which reversibly transforms from a systematically interrupted to a fully connected state and back. Analysis of the opening/closing behavior allowed the study of entropy and framework flexibility as determinants for the stability of zeolite topologies, which, until now, has been experimentally inaccessible. Interconversion of the all-silica COK-14 zeolite with fully connected OKO topology and its -COK-14 variant with systematic framework interruption was investigated using high-temperature XRD, thermogravimetric analysis, Si-29 MAS NMR, nitrogen adsorption and a range of modelling techniques. Specific framework bonds in the OKO framework can be reversibly hydrolyzed and condensed. Structural silanols of the parent -COK-14, prepared by degermanation of the IM-12 zeolite, were condensed by heating at 923 K, and hydrolyzed again to the initial state by contacting the zeolite with warm water. Molecular modelling revealed an inversion of the relative stabilities for both variants depending on temperature and hydration. Condensation of the structural silanols in -COK-14 to COK-14 is entropy driven, mainly resulting from the release of water molecules. Framework reopening in the presence of water is spontaneous due to the high rigidity of the fully connected OKO framework. Isomorphous substitution was demonstrated as a viable option for stabilization of the fully connected OKO framework as this renders the closed framework flexible.

DOI

http://dr.doi.org/10.1039/c4mh00127c

Private attachment

manuscript mat Hor.pdf

Modeling 1D structures on semiconductor surfaces: synergy of theory and experiment

wim — Thu, 03 Apr 2014 12:37:33 +0000

D.E.P. Vanpoucke

Journal of Physics: Condensed Matter

26 (2014), 133001

2014

Abstract

Atomic scale nanowires attract enormous interest in a wide range of fields. On the one hand, due to their quasi-one-dimensional nature, they can act as an experimental testbed for exotic physics: Peierls instability, charge density waves, and Luttinger liquid behavior. On the other hand, due to their small size, they are of interest not only for future device applications in the micro-electronics industry, but also for applications regarding molecular electronics. This versatile nature makes them interesting systems to produce and study, but their size and growth conditions push both experimental production and theoretical modeling to their limits. In this review, modeling of atomic scale nanowires on semiconductor surfaces is discussed, focusing on the interplay between theory and experiment. The current state of modeling efforts on Pt- and Au-induced nanowires on Ge(001) is presented, indicating their similarities and differences. Recently discovered nanowire systems (Ir, Co, Sr) on the Ge(001) surface are also touched upon. The importance of scanning tunneling microscopy as a tool for direct comparison of theoretical and experimental data is shown, as is the power of density functional theory as an atomistic simulation approach. It becomes clear that complementary strengths of theoretical and experimental investigations are required for successful modeling of the atomistic nanowires, due to their complexity.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1088/0953-8984/26/13/133001

Private attachment

14_J_Phys_Condens_Matter_26_133001_Vanpoucke.pdf

Identification of intermediates in zeolite-catalyzed reactions using in-situ UV/Vis micro-spectroscopy and a complementary set of molecular simulations

michel — Sat, 18 May 2013 20:05:23 +0000

K. Hemelsoet, Q. Qian, T. De Meyer, K. De Wispelaere, B. De Sterck, B.M. Weckhuysen, M. Waroquier, V. Van Speybroeck

Chemistry - A European Journal

19, 49, 16595-16606

2013

Abstract

The optical absorption properties of (poly)aromatic hydrocarbons occluded in a nanoporous environment were investigated by theoretical and experimental methods. The carbonaceous species are an essential part of a working catalyst for the methanol-to-olefins (MTO) process. In situ UV/Vis microscopy measurements on methanol conversion over the acidic solid catalysts H-SAPO-34 and H-SSZ-13 revealed the growth of various broad absorption bands around 400, 480, and 580 nm. The cationic nature of the involved species was determined by interaction of ammonia with the methanol-treated samples. To determine which organic species contribute to the various bands, a systematic series of aromatics was analyzed by means of time-dependent density functional theory (TDDFT) calculations. Static gas-phase simulations revealed the influence of structurally different hydrocarbons on the absorption spectra, whereas the influence of the zeolitic framework was examined by using supramolecular models within a quantum mechanics/molecular mechanics framework. To fully understand the origin of the main absorption peaks, a molecular dynamics (MD) study on the organic species trapped in the inorganic host was essential. During such simulation the flexibility is fully taken into account and the effect on the UV/Vis spectra is determined by performing TDDFT calculations on various snapshots of the MD run. This procedure allows an energy absorption scale to be provided and the various absorption bands determined from in situ UV/Vis spectra to be assigned to structurally different species.

DOI

http://dx.doi.org/10.1002/chem.201301965

Private attachment

13_chem_eur_ j_xxx_Hemelsoet.pdf

Synthesis modulation as a tool to increase the catalytic activity of MOFs: the unique case of UiO-66(Zr)

michel — Sat, 18 May 2013 19:26:34 +0000

F. Vermoortele, B. Bueken, G. Le Bars, B. Van de Voorde, M. Vandichel, K. Houthoofd, A. Vimont, M. Daturi, M. Waroquier, V. Van Speybroeck, C. Kirschhock, D. De Vos

JACS (Journal of the American Chemical Society)

135 (31), 11465–11468

2013

Abstract

The catalytic activity of the zirconium terephthalate UiO-66(Zr) can be drastically increased by using a modulation approach. The combined use of trifluoroacetic acid and HCl during the synthesis results in a highly crystalline material, with partial substitution of terephthalates by trifluoroacetate. Thermal activation of the material leads not only to dehydroxylation of the hexanuclear Zr cluster but also to post-synthetic removal of the trifluoroacetate groups, resulting in a more open framework with a large number of open sites. Consequently, the material is a highly active catalyst for several Lewis acid catalyzed reactions.

DOI

http://dx.doi.org/10.1021/ja405078u

Private attachment

13_jacs_135_11465_Vermoortele.pdf

Catalysis making the world a better place - discussion & satellite meeting

wim — Fri, 12 Jun 2015 06:57:42 +0000

Buckinghamshire, UK

Monday, 8 June, 2015 to Thursday, 11 June, 2015

Participant(s)

V. Van Speybroeck

Project ref.

BOF-ERC I/00057/02

Conference reference

Catalysis making the world a better place

Machine Learning for Many-Particle Systems

wim — Tue, 13 Jan 2015 12:50:04 +0000

Los Angeles, California, USA

Monday, 23 February, 2015 to Friday, 27 February, 2015

Participant(s)

V. Van Speybroeck

Project ref.

BOF-ERC I/00057/02

Conference reference

Machine Learning for Many-Particle Systems

DZA-meeting

wim — Thu, 02 Oct 2014 13:07:26 +0000

Ghent, Belgium

Tuesday, 7 October, 2014

Participant(s)

J. Van der Mynsbrugge, K. De Wispelaere, J. Hajek, M. Vandichel, P. Cnudde, T. Bogaerts, A. Van Yperen-De Deyne, D.E.P. Vanpoucke, K. Hemelsoet

Project ref.

FWO mandaat, FWO MOFs (3G048612) B/12561/*, ERC KINPOR B/10761/*, BOF-ERC I/00057/02

Conference reference

DZA-meeting 2014

FEZA 2014

wim — Mon, 29 Sep 2014 11:48:54 +0000

Leipzig, Germany

Monday, 8 September, 2014 to Thursday, 11 September, 2014

Participant(s)

K. Hemelsoet, T. Bogaerts, P. Cnudde, S.L. Moors

Project ref.

FWO mandaat, BOF-ERC I/00057/02, ERC KINPOR B/10761/*

Conference reference

FEZA 2014