Kristof De Wispelaere

Kristof De Wispelaere
Ghent University | UGhent · Center for Molecular Modeling

Doctor of Chemical Engineering

About

40
Publications
5,386
Reads
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2,027
Citations
Citations since 2017
20 Research Items
1703 Citations
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20172018201920202021202220230100200300
20172018201920202021202220230100200300
Introduction
Current research Application of advanced molecular dynamics techniques to study zeolite-catalyzed reactions Research interests * Ab initio modeling in heterogeneous catalysis * Kinetics of elementary steps in the MTO process * Simulation of IR and UV-Vis spectra to characterize intermediates during methanol conversion * Free energy methods * Molecular Dynamics simulations of the framework flexibility of zeolite and zeotype materials * Diffusion in zeolite or zeotype materials
Additional affiliations
October 2016 - present
Stanford University
Position
  • PostDoc Position
Description
  • Postdoctoral fellowship in the SUNCAT group of Jens Nørskov funed by the Belgian American Educational Foundation (BAEF) and the Research Foundation Flanders (FWO).
October 2016 - October 2017
Stanford University
Position
  • PostDoc Position
February 2016 - present
Ghent University
Position
  • Lecturer
Description
  • Molecular Modeling of Industrial Processes (MSc in Chemical Engineering)
Education
September 2006 - June 2011
Ghent University
Field of study

Publications

Publications (40)
Article
Full-text available
The methanol-to-hydrocarbons reaction refers collectively to a series of important industrial catalytic processes to produce either olefins or gasoline. Mechanistically, methanol conversion proceeds through a ‘pool’ of hydrocarbon species. For the methanol-to-olefins process, these species can be delineated broadly into ‘desired’ lighter olefins an...
Article
The methanol-to-hydrocarbons process is known to proceed autocatalytically in H-ZSM-5 after an induction period where framework methoxy species are formed. In this work, we provide mechanistic insight into the framework methylation within H-ZSM-5, at high methanol loadings and varying acid site density, by means of first principles molecular dynami...
Article
A systematic molecular level and spectroscopic investigation is presented to show the cooperative role of Brønsted acid and Lewis acid sites in zeolites for the conversion of methanol. Extra-framework alkaline- earth metal containing species and aluminum species decrease the number of Brønsted acid sites, as protonated metal clusters are formed. A...
Article
Full-text available
The direct transformation of CO2 into high value-added hydrocarbons (i.e. olefins and aromatics) has the potential to make a decisive impact in our society. However, despite the efforts of the scientific community, no direct synthetic route exists today to synthesize olefins and aromatics from CO2 with high productivities and low undesired CO selec...
Article
The active site in ethene oligomerization catalyzed by Ni-zeolites is proposed to be a mobile Ni(II) complex, based on density functional theory-based molecular dynamics (DFT-MD) simulations corroborated by continuous-flow experiments on Ni-SSZ-24 zeolite. The results of the simulations at operating conditions show that ethene molecules reversibly...
Article
Full-text available
When exposed to steam, zeolite catalysts are irreversibly deactivated by loss of acidity and framework degradation caused by dealumination. Steaming typically occurs at elevated temperatures, making it challenging to investigate the mechanism with most approaches. Herein, we follow the dynamics of zeolite dealumination in situ, in the presence of a...
Article
Catalytic alkene cracking on H-ZSM-5 involves a complex reaction network with many possible reaction routes and often elusive intermediates. Herein, advanced molecular dynamics simulations at 773 K, a typical cracking temperature, are performed to clarify the nature of the intermediates and to elucidate dominant cracking pathways at operating condi...
Article
Full-text available
The combination of well-defined acid sites, shape-selective properties and outstanding stability places zeolites among the most practically relevant heterogeneous catalysts. The development of structure-performance descriptors for processes that they catalyse has been a matter of intense debate, both in industry and academia, and the direct convers...
Article
Full-text available
In the version of this Article originally published, on the right side of Fig. 4b, the 'Aromatic cycle' label was erroneously shifted outside of the central circular arrow into a position on part of the reaction cycle. This has been corrected in the online versions of the Article.
Article
In methanol-to-hydrocarbon chemistry, methanol and dimethyl ether (DME) can act as methylating agents. Therefore, we focus on the different reactivity of methanol and DME towards benzene methylation in H-ZSM-5 at operating conditions by combining first principles microkinetic modeling and experiments. Methylation reactions are known to follow eithe...
Article
Full-text available
The UiO-66 material is a showcase example of an extremely stable Metal-Organic Framework, which maintains its structural integrity during activation processes such as linker exchange, dehydration. The framework can even accommodate a substantial number of defects without compromising its stability. These observations point to an intrinsic dynamic f...
Chapter
Entropy plays a major role in many physical and chemical phenomena, not the least for reactions taking place on surfaces and for catalysis taking place in confinement such as zeolites or metal-organic frameworks. Understanding and quantifying the role of entropy on reaction mechanisms and kinetics in nanoporous materials has proven extremely diffic...
Article
The catalytic conversion of methanol and dimethyl ether (DME) into fuels and chemicals over zeolites (MTH process) is industrially emerging as alternative route to conventional oil-derived processes. After 40 years of research, a detailed mechanistic understanding of the intricate reaction network is still not fully accomplished. The overall reacti...
Chapter
Within the field of catalysis, theoretical modeling has also taken a prominent role. This chapter answers the question whether anno 2016 of a theoretical toolbox for a better catalytic understanding can be disposed. It focuses on heterogeneous catalysis and in particular on catalytic reactions taking place in the pores of a nanoporous material. An...
Article
Full-text available
Catalytic cracking of alkenes takes place at elevated temperatures in the order of 773–833 K. In this work, the nature of the reactive intermediates at typical reaction conditions is studied in H-ZSM-5 using a complementary set of modeling tools. Ab initio static and molecular dynamics simulations are performed on different C4 C5 alkene cracking in...
Article
The Front Cover shows Ca-ZSM-5 as a “super-catalyst” fighting coke – the evil of MTO world.In their Full Paper, I. Yarulina et al. investigated the mechanism of methanol to olefins (MTO) reaction, which is characterized by the presence of two competing cycles – olefinic and aromatic. The latter is responsible for catalyst deactivation since aromati...
Article
The front cover artwork for Issue 19/2016 is provided by researchers from the Catalysis Engineering group at TU Delft (The Netherlands). The image shows that after impregnation with Ca, ZSM-5 becomes a “super-catalyst”, which is able to suppress formation of aromatics thus increasing selectivity to the desired propylene in MTO reaction. See the Ful...
Article
Adsorption of linear pentenes in H-ZSM-5 at 323 K is investigated using contemporary static and molecular dynamics methods. A physisorbed complex corresponding to free pentene, a π-complex and a chemisorbed species may occur. The chemisorbed species can be either a covalently bonded alkoxide or an ion pair, the so-called carbenium ion. Without fini...
Article
Full-text available
Incorporation of Ca in ZSM-5 results in a twofold increase of propylene selectivity (53 %), a total light-olefin selectivity of 90 %, and a nine times longer catalyst lifetime (throughput 792 gMeOH gcatalyst−1) in the methanol-to-olefins (MTO) reaction. Analysis of the product distribution and theoretical calculations reveal that post-synthetic mod...
Article
The role of water in the methanol-to-olefins (MTO) process over H-SAPO-34 has been elucidated by a combined theoretical and experimental approach, encompassing advanced molecular dynamics simulations and in-situ micro-spectroscopy. First principle calculations at the molecular level point out that water competes with methanol and propene for direct...
Article
Zeolites are the workhorses of today’s chemical industry. For decades they have been successfully applied, however many features of zeolite catalysis are only superficially understood and in particular the kinetics and mechanism of individual reaction steps at operating conditions. Herein we use state-of-the-art advanced ab initio molecular dynamic...
Article
The diffusion of olefins through 8-ring solid acid microporous zeolites is investigated using molecular dynamics simulations techniques and using a newly developed flexible force field. Within the context of the Methanol to Olefin (MTO) process and the observed product distribution, knowledge on the diffusion paths is essential to obtain molecular...
Cover Page
The methanol-to-olefin process is a showcase example of complex zeolite-catalyzed chemistry. At real operating conditions, many factors affect the reactivity, such as framework flexibility, adsorption of various guest molecules, and competitive reaction pathways. In this study, the strength of first principle molecular dynamics techniques to captur...
Article
The methanol-to-olefin process is a showcase example of complex zeolite-catalyzed chemistry. At real operating conditions, many factors affect the reactivity, such as framework flexibility, adsorption of various guest molecules, and competitive reaction pathways. In this study, the strength of first principle molecular dynamics techniques to captur...
Article
To optimally design next generation catalysts a thorough understanding of the chemical phenomena at the molecular scale is a prerequisite. Apart from qualitative knowledge on the reaction mechanism, it is also essential to be able to predict accurate rate constants. Molecular modeling has become a ubiquitous tool within the field of heterogeneous c...
Article
Framework-bound methoxides occur as intermediates in the stepwise mechanism for zeolite-catalyzed methylation reactions. Herein, the formation of methoxides from methanol or dimethyl ether in H-ZSM-5 is investigated by a combination of static and dynamic simulations, with particular focus on the effect of additional water and methanol molecules on...
Article
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...
Article
The methylation of arenes is a key step in the production of hydrocarbons from methanol over acidic zeolites. We performed ab initio static and molecular dynamics free energy simulations of benzene methylation in H-ZSM-5 to determine the factors that influence the reaction kinetics. Special emphasis is given to the effect of the surrounding methano...
Article
The methanol to olefins process is an alternative for oil-based production of ethene and propene. However, detailed information on the reaction mechanisms of olefin formation in different zeolite is lacking. Herein a first principle kinetic study allows elucidating the importance of a side-chain mechanism during methanol conversion in H-SAPO-34. St...
Article
The conversion of methanol to olefins (MTO) over a heterogeneous nanoporous catalyst material is a highly complex process involving a cascade of elementary reactions. The elucidation of the reaction mechanisms leading to either the desired production of ethene and/or propene or undesired deactivation has challenged researchers for many decades. Cle...
Article
The formation and nature of active sites for methanol conversion over solid acid catalyst materials are studied by using a unique combined spectroscopic and theoretical approach. A working catalyst for the methanol‐to‐olefin conversion has a hybrid organic–inorganic nature in which a cocatalytic organic species is trapped in zeolite pores. As a cas...
Cover Page
Shiny disco catalysts! The cover picture shows a cationic hydrocarbon pool species of increasing size and methylation degree confined in a zeolitic cage. In their Full Paper on p. 173 ff., V. Van Speybroek, B. M. Weckhuysen et al. explain that these aromatic hydrocarbon species are reaction intermediates, coke precursors, or both, for the methanol-...
Article
Theoretical and experimental IR data are combined to gain insight into the methanol and ethanol conversion over an acidic H-SAPO-34 catalyst. The theoretical simulations use a large finite cluster and the initial physisorption energy of both alcohols is calculated. Dispersive contributions turn out to be vital and ethanol adsorbs stronger than meth...

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