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PhD position in the field of modeling adsorption of C2/C3 species in nanostructured materials for separation

YOUR TASKS

The multidisciplinary Center for Molecular Modeling (CMM, http://molmod.ugent.be) is looking for a highly motivated researcher to perform state-of-the-art research in the context of a PhD in the field of molecular simulations of hybrid membrane technology for more efficient C2 and C3 separations. The prospective PhD student will work in the research unit of Prof. Van Speybroeck and Vanduyfhuys.

The research is situated within the framework of a CO₂ Moonshot project entitled ‘Moonrise’ in collaboration with partners from KULeuven, VUB and an industrial advisory board. The general aim of Moonrise is to create an energy-efficient alternative for cryogenic distillation in the production of C2 and C3 base chemicals by developing membranes for C2 and C3 olefin/paraffin separations. In addition, a membrane-based separation of these olefins from N₂ will be targeted to drastically reduce olefin losses via flaring. Three different membrane types will be developed: polymer-only, mixed matrix membranes (MMMs) and metal-organic frameworks (MOF)-only. Through collaboration within a highly complementary consortium, this project joins various fields of expertise: membrane development, MOF-film preparation, diffusion and sorption studies, and molecular modelling. The CMM participates in the project as modeling partner with various research positions, who will study the modeling of diffusion/sorption properties will steer the material selection and optimization, while additionally helping to fundamentally understand the performances of the prepared membranes.

Molecular simulations have grown to become an indispensable tool for the development of new application-oriented materials. Such simulations start from the inter- and intramolecular interactions and allow to compute thermodynamic equilibrium properties such as the number of adsorbed molecules as well as dynamic properties such as a diffusion constant. Within this PhD research, various simulation techniques such as static geometric optimization, normal mode analysis, grand canonical Monte Carlo and classical density functional theory will be applied to compute adsorption free energies as well as full adsorption isotherms of various guest molecules in MOFs, polymers and the hybrid MOF/membrane materials subject in the Moonrise project under realistic conditions of temperature, loading and pressure. As such, we aim to complement experimental characterization of the adsorption properties of these materials performed by our experimental partners to rationalize why certain materials perform well under a given set of conditions and guide the synthesis of new high-performance materials.

The prospective candidate will join a strongly connected research team and benefit from the experience present in the Center for Molecular Modeling (CMM), specifically on performing advanced molecular simulations for the characterization of adsorption properties of nanoporous materials. He/she will collaborate with national and international academic partners and take an active role in the frequent meetings of the Moonshot project. The CMM, headed by Prof. Van Speybroeck, is a multidisciplinary research center, which groups about 40 researchers of the faculties of Science and Engineering and Architecture with molecular modeling interests. The CMM aims to model molecules, materials and processes at the nanoscale by bringing together physicists, chemists, (bio-)engineers and stimulating collaborations across disciplines. Within the CMM collaborative research between researchers with various backgrounds and from various departments is pursued. This multidisciplinary collaborative mission is the DNA of the CMM and key to achieve scientific excellence in the field of molecular modeling.

WHO WE ARE LOOKING FOR

You are highly motivated to become an independent researcher and to contribute to important societal problems related to e.g. clean energy production, non-fossil based production of chemicals and/or the design of materials for the next generation energy carriers.
You have a strong academic record showing your potential to become a excellent researcher.
You have or will soon obtain a master’s degree of a university or international equivalent in the field of Physics, Physical Engineering or a related field;
We are looking for candidates with a pro-active working style; willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
Experience with molecular simulation software (LAMMPS, DLPOLY, RASPA, Gaussian, VASP, CP2K, …) coding (Python, C, ...) is an advantage. At the very least, the candidate must be willing to learn these skills during the first year of the PhD.
You have excellent communication skills in English and have a strong motivation to collaborate both within the CMM with other researchers and with other researchers of our network.

WHAT WE CAN OFFER YOU

Your contract will start on 1/09/2021 at the earliest.
You will work in a highly motivated and dynamic team, will be actively trained by various researchers of the team that consists of various junior and senior researchers with different backgrounds.
You will have the ability to participate actively in various international conferences, perform international research stays at the most prominent universities worldwide with whom we collaborate to strengthen your skills.
Interested candidates will have the ability to also contribute to education of the CMM by giving exercise classes.
Prof. Van Speybroeck has a very strong track record in coaching PhD students, under her supervision 32 successful PhD candidates were performed. Most of them found jobs afterwards in industry, academia and have built very strong CVs during their time at the CMM.

INTERESTED?

Formal applications should be submitted by August 31, 2021 to cmm.vacancies@ugent.be, according to the guidelines mentioned in the application form. Your application must include the following documents:

The filled out application form
A motivation letter
A curriculum vitae
A transcript of the required degree (if already in your possession). If you have a foreign diploma in a language other than our national languages (Dutch, French or German) or English, please add a translation in one of the mentioned languages.

As Ghent University maintains an equal opportunities and diversity policy, everyone is encouraged to apply for this position.

MORE INFORMATION

For more information about this vacancy, please contact us at cmm.vacancies@ugent.be.

PostDoc position on ab initio and force field modeling of C2/C3 species in nanostructured materials for separation

YOUR TASKS

The multidisciplinary Center for Molecular Modeling (CMM, http://molmod.ugent.be) is looking for a highly motivated post-doctoral researcher to perform state-of-the-art research in the field of advanced molecular simulations of guest-loaded nanoporous materials in the context of hybrid membrane technology for more efficient C2 and C3 separations. The prospective postdoc will work in the research unit of Prof. Van Speybroeck and Vanduyfhuys.

Molecular simulations have become an indispensable tool for the development of new application-oriented materials as they start from the interactions at a molecular scale and allow to efficiently compute thermodynamic equilibrium properties such adsorption isotherms as well as dynamic properties such as diffusion constants. In order to perform such simulations, an appropriate level of theory is required to describe the inter- and intramolecular interactions. On the one hand, a full quantum mechanical description is very accurate but not always feasible for large systems. On the other hand, force fields can provide the desired trade-off between accuracy and computational feasibility, provided they are well parameterized. Within this project both routes will be explored. Various static quantum calculations will be performed using density functional theory, post HF and/or the random phase approximation to get accurate estimates of the adsorption affinity of various sorbates in MOFs and polymer materials. Furthermore, new force fields will be developed to accurately describe the relevant host-sorbate interactions using existing in-house methodologies. As such, we aim to complement experimental characterization performed by our experimental partners to rationalize why certain materials subject in the Moonrise project perform well under a given set of conditions and guide the synthesis of new high-performance materials.

The prospective candidate will join a strongly connected research team and benefit from the experience present in the Center for Molecular Modeling (CMM), specifically on performing high-level quantum mechanical calculations as well as on force field development. He/she will collaborate with national and international academic partners and take an active role in the frequent meetings of the Moonshot project. The candidate can also take an active role in guiding PhD students working within this project. The CMM, headed by Prof. Van Speybroeck, is a multidisciplinary research center, which groups about 40 researchers of the faculties of Science and Engineering and Architecture with molecular modeling interests. The CMM aims to model molecules, materials and processes at the nanoscale by bringing together physicists, chemists, (bio-)engineers and stimulating collaborations across disciplines. Within the CMM collaborative research between researchers with various backgrounds and from various departments is pursued. This multidisciplinary collaborative mission is the DNA of the CMM and key to achieve scientific excellence in the field of molecular modeling.

WHO WE ARE LOOKING FOR

You are highly motivated to be an independent researcher and to contribute to important societal problems related to e.g. clean energy production, non-fossil based production of chemicals and/or the design of materials for the next generation energy carriers.
You have a PhD in the field of computational chemistry/physics or a related field;
We are looking for candidates with a pro-active working style; willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
You have excellent communication skills in English and have a strong motivation to collaborate both within the CMM with other researchers and with other researchers of our network.
You can rely on a CV with a strong track record based on high profile papers, contributions to international conferences,….
The successful candidate is expected to have expertise in the following areas with a proven track record in the following areas :
- You are familiar with performing quantum mechanical calculations such as density functional theory and post-HF. You also have experience with force field calculations. Experience in developing force fields is an advantage.
- You are familiar with molecular simulation techniques including both static techniques (geometry optimization, normal mode analysis, …) as well as dynamic techniques (molecular dynamics, Monte Carlo, …). Experience with enhanced sampling techniques (metadynamics, umbrella sampling, …) is an advantage.
- You have experience with molecular simulation software (Gaussian, VASP, CP2K, LAMMPS, DLPOLY, RASPA, …). Experience with coding (Python, C, ...) is an advantage.

WHAT WE CAN OFFER YOU

Your contract will start on 1/09/2021 at the earliest.
You will work in a highly motivated and dynamic team, with active support from various researchers of the team with different backgrounds.
You will have the ability to participate actively in various international conferences, perform international research stays at the most prominent universities worldwide with whom we collaborate to strengthen your skills.
Interested candidates will have the ability to also contribute to education of the CMM by giving exercise classes.

INTERESTED?

The filled out application form
A motivation letter
A curriculum vitae
A transcript of the required degree (if already in your possession). If you have a foreign diploma in a language other than our national languages (Dutch, French or German) or English, please add a translation in one of the mentioned languages.

As Ghent University maintains an equal opportunities and diversity policy, everyone is encouraged to apply for this position.

MORE INFORMATION

For more information about this vacancy, please contact us at cmm.vacancies@ugent.be.

PhD position on molecular modeling of external zeolite surfaces for catalysis

Ph.D. position available in the field of Modelling catalysis at external surfaces in nanoporous zeolite materials in the research group of prof. V. Van Speybroeck at the Center for Molecular Modeling, Ghent University, Belgium

The research group of prof. Van Speybroeck, embedded within the multidisciplinary Center for Molecular Modeling (CMM, http://molmod.ugent.be), is looking for a highly motivated researcher to perform state-of-the-art research in the field of theoretical modeling of catalysis in nanoporous zeolite materials. We especially welcome candidates with a strong track record who may become eligible to apply for a prestigious Ph.D. fellowship at our national funding agency (FWO).

ABOUT THE PROJECT - YOUR TASK

In contrast to catalysis and chemical transformations in bulk zeolite crystals, much less information is available on the external zeolite surfaces which may contain silanol groups and highly active acid sites. Next to the confinement effects of pore mouth catalysis, the external surface may have an important impact on the diffusion limitations in this respect. A thorough understanding of the impact of external surface sites on the acidity and reactivity is essential to improve the catalyst efficiency and selectivity. Nevertheless, there is still a large gap between the current state-of-the-art in zeolite models and a proper description of the industrially employed catalysts. The current project aims to obtain fundamental understanding on how external surfaces and defects for a varying set of zeolite materials will affect the catalytic reactivity and diffusion behavior.

Computational modeling can prove a powerful method to aid in the characterization of the role of defects, external surface sites and other complexities of zeolite catalysts. In this Ph.D. research, you will investigate several aspects of modeling the physical and chemical properties of real zeolite catalysts using a large set of modeling techniques. You will first develop realistic models to describe the zeolite external surface and zeolite defects. By applying a combination of molecular dynamics (MD) simulations and density functional theory (DFT) calculations, you will then apply these models to investigate the impact of external surface sites on hydrocarbon diffusion limitations and common hydrocarbon transformations in zeolites, such as catalytic alkene cracking or C1 catalysis, taking into account the complex molecular environment and actual reaction conditions. If the models would become too large, machine learning models will be applied to extend to accessible length and time scales of the simulation. The research topic will be conducted in close collaboration with excellent experimental groups to guide the design toward new and promising functional materials.

ABOUT THE CENTER FOR MOLECULAR MODELING

The candidate will join a strongly connected research team and will collaborate with national and international academic partners. He/she will benefit from the experience present in the research group, specifically on performing advanced molecular simulations and the development of general procedures to model chemical transformations in nanoporous materials. The CMM is an interfaculty research unit at Ghent University, grouping about 40 scientists from the Faculty of Science and the Faculty of Engineering and Architecture. The research team consists of various junior and senior researchers with different backgrounds which enables us to provide a proper intellectual environment for the conducted research.

The CMM performs interdisciplinary research at the crossroads between physics, chemistry and materials engineering with the aim to design molecules, materials, and processes at the nanoscale. To this end, the CMM consists of six synergetic research areas: “Nanoporous materials”, “Solid-state physics”, “Bio/organic chemistry”, “Model and software development”, “Spectroscopy”, and “Many-particle physics”. The research of this Ph.D. position will be mainly situate in the area “Nanoporous Materials”, but to enable high-quality research, we strongly stimulate interactions between the various researchers in our team as well as with our vast network of national and international partners. The research of the CMM is internationally regarded to be at the forefront in its field.

WHO WE ARE LOOKING FOR

We are looking for a highly motivated and creative Ph.D. candidate with:

A master’s degree of an international equivalent in the field of Chemistry, Chemical Engineering, Physics, Physical Chemistry or a related field;
Perseverance and an independent, pro-active working style;
The willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
Experience with quantum chemistry software (Gaussian, VASP,…) and coding (Python, C, ...) is an advantage.
Excellent collaboration and communication skills (written and verbally) in English.

WHAT WE CAN OFFER YOU

Your contract will start as from September/October
You will work in a highly motivated and dynamic team, will be actively trained by various researchers of the team that consists of various junior and senior researchers with different backgrounds.
You will have the ability to participate actively in various international conferences, perform international research stays at the most prominent universities worldwide with whom we collaborate to strengthen your skills.
Interested candidates will have the ability to also contribute to education of the CMM by giving exercise classes.
Prof. Van Speybroeck has a very strong track record in coaching PhD students, under her supervision 32 successful PhD candidates were performed. Most of them found jobs afterwards in industry, academia and have built very strong CVs during their time at the CMM.

INTERESTED?

The filled out application form
A motivation letter
A curriculum vitae
A transcript of the required degree (if already in your possession). If you have a foreign diploma in a language other than our national languages (Dutch, French or German) or English, please add a translation in one of the mentioned languages.

As Ghent University maintains an equal opportunities and diversity policy, everyone is encouraged to apply for this position.

MORE INFORMATION

For more information about this vacancy, please contact us at cmm.vacancies@ugent.be.

Shocking news: Oxford-UGent research published in Nature Materials paves the way for a new class of reusable and efficient shock absorbers

An international collaboration between researchers of the Multifunctional Materials & Composites (MMC) Laboratory at the University of Oxford (Yueting Sun, now at the University of Birmingham, Clive R. Siviour, and prof. Jin-Chong Tan) and the Center for Molecular Modeling (CMM) at Ghent University (dr. Sven M.J. Rogge, Aran Lamaire, dr. Steven Vandenbrande, dr. Jelle Wieme, and prof. Veronique Van Speybroeck) demonstrated a new conceptual type of reusable shock absorber. By harnessing the energy of mechanical impacts to force water in the hydrophobic cages of nanoporous materials such as ZIF-8, large shocks can be efficiently absorbed. Thanks to a combined experimental and computational approach, the study also formulated design rules that led to the identification of twenty more promising materials for shock absorption. The work was recently published in Nature Materials and was supported, among others, by 4 FWO (post-)doctoral fellowships and 2 ERC Consolidator grants. News stories about this article appeared on VRT NWS and in New Scientist.

New generation of shock absorbers

Known materials that need to capture large shocks, such as guard rails or helmets, deform strongly to neutralize the mechanical energy of such a shock. In most cases, this means that the materials do not return spontaneously to their original state after the shock has disappeared again. As a result, they lose the ability to absorb further shocks. Research performed at the Center for Molecular Modeling (CMM), led by prof. Van Speybroeck, and the University of Oxford now reveals a new mechanism that makes shock absorbers both reusable and much more efficient.

The experimental impact setup, courtesy of dr. Yueting Sun (University of Birmingham)

The experimental high-rate setup, courtesy of dr. Yueting Sun (University of Birmingham)

These new shock absorbers consist of two elements: on the one hand water, and on the other hand a nanoporous material that consists of interconnected hydrophobic cages. Upon a mechanical impact, the energy of this shock is used to force water in the hydrophobic cages. Moreover, the researchers observed that the higher the impact rate, the more energy the material absorbs. Once the shock disappears, water again extrudes from the cages, and the whole absorption cycle can start over again.

What makes these materials so efficient?

Researchers at the University of Oxford observed this new mechanism first in ZIF-8, a so-called metal-organic framework with a structure that closely resembles that of zeolites. To understand why this nanoporous material can absorb mechanical shocks so efficiently, and especially why it does so more efficiently the higher the impact rate, researchers at the CMM performed several challenging quantum mechanical calculations.

These calculations demonstrated the key role played by the very specific ZIF-8 structure. Because the material consists of interconnected hydrophobic cages, water never introduces spontaneously in these cages. Only when there is sufficient pressure on the material, for instance, because of a mechanical shock, the first water molecules start entering the material’s cages, despite its hydrophobicity. Hydrogen bridges then ensure that the molecules confined in the cages organize in small clusters. As soon as such a cluster becomes sufficiently large – from about five molecules onwards – it becomes much easier to intrude more water molecules in the cages until they finally fill the whole material. This process does take some time. As a result, if the mechanical shock has too high an impact rate, there is insufficient time to form this type of clusters, and even more energy of the mechanical shock is needed to force water inside the cages. This explains the higher efficiency of these materials at high-rate impacts.

What’s next?

Based on these simulations, the researchers derived a set of design rules to develop shock absorbers that harness this specific mechanism. The most important design rule is that such materials need to consist of hydrophobic cages, such that water does not intrude spontaneously. Furthermore, these cages need to be interconnected via apertures that are sufficiently large so that water molecules can move from one cage to the other. Finally, the larger the cages, the more water molecules they can eventually accommodate, and so the more mechanical energy of the shock they can neutralize. Based on these design rules, we discovered about twenty materials in total that are not used as shock absorbers for the moment, but that would be in fact very efficient for this task. Some of those materials we have now also tested, with very promising results.

Technical info

These results were published in Nature Materials.

High-rate nanofluidic energy absorption in porous zeolitic frameworks
Yueting Sun, Sven M. J. Rogge, Aran Lamaire, Steven Vandenbrande, Jelle Wieme, Clive R. Siviour, Veronique Van Speybroeck, and Jin-Chong Tan
Nature Materials, 10.1038/s41563-021-00977-6

Dr. ir. Sven Rogge, ir. Aran Lamaire, prof. dr. ir. Veronique Van Speybroeck
Center for Molecular Modeling
Technologiepark 46, 9052 Zwijnaarde
M +32 (0)478 82 34 19

PhD in quantum and machine learning modeling for nuclear reactors

Job description

At the intersection of the Material Science and Technology research group and the Center for Molecular Modeling, we study in a computational way the properties of molecules and crystals. Emphasis is on predicting properties that cannot be easily obtained by experiments, and on topics where knowledge of these properties can help experimental or applied researchers.

The current position is part of large international effort on developing MYRRHA, a next-generation nuclear fission reactor.

You will examine the stability of polonium-containing molecules in conditions relevant for this reactor. This will be done by a combination of quantum chemistry, density functional theory and machine learning. Method development will be needed to achieve highly accurate predictions for molecules that are too large for allowing the direct use of the most accurate simulation methods.

You will have access to the computing resources of the VSC (Flemish Supercomputing Center, vscentrum.be).

You will interact with the teams that are working on this topic experimentally, to understand which computed information they need in order to analyse their experiments in a more unambiguous way.

Additional information on the scientific context of this topic can be downloaded from http://bit.ly/phd-ghent .

The position is fully funded and you have the same benefits as Ghent University employees. You will be supervised by prof. Stefaan Cottenier and his team.

Job profile

You have a master degree in physics, chemistry, materials engineering, engineering physics, chemical engineering. or related areas
You have some experience about at least one of these three topics: quantum chemistry calculations, density functional theory, machine learning. You have at least an interest and a desire to learn for the other topics on which you do not have experience yet.
A working knowledge of Python is an asset. The same holds for working in a linux environment and for working in a supercomputer environment.
Good oral and written communication skills in English are required.

About 10% of your time is to be spent to supporting teaching activities at Ghent University.

The position start date is as soon as possible after the end of the application period. Given the current covid prevention rules, the details about when and how to start the work will be negotiated with the selected candidate.

How to apply

For informal inquiries, please contact Stefaan Cottenier (stefaan.cottenier@ugent.be).

Your application must include :

1. A letter in which you explain why you are motivated for this position, and why you have the proper skills to bring this research one step further. Please avoid standard motivation letters, tailor it to this specific case.
2. A link to a short video (min 1 minute, max 5 minutes) where you explain your favourite science topic to an imaginary broad audience. Don't worry about the technical quality -- a video shot with your smartphone is fine. Upload it to a cloud drive (Google Drive, Onedrive,...) and share the link in your application, or send it via (for instance) WeTransfer.com together with your application.
3. A standard CV, with emphasis on your performance in the last 2 years of your education and - if applicable - on your work experience. A link to your master thesis (in whatever language it is) is appreciated.
4. The names and contact details of at least 2 referees. Explain why these people are suited to give a balanced opinion about you. No recommendation letters are needed at this stage.

Applications should be sent to Stefaan Cottenier (stefaan.cottenier@ugent.be), with the mandatory subject line 'polonium PhD application'.

Selected candidates will be invited for an online interview. Deadline April 2nd

CMM research on alkene diffusion in zeolites on cover Angewandte Chemie

A new publication, entitled ‘Experimental and Theoretical Evidence for the Promotional Effect of Acid Sites on the Diffusion of Alkenes through Small-Pore Zeolites’ has recently been accepted as a hot paper in the journal Angewandte Chemie and has been promoted on the journal cover. Our study presents new insight into the influence of the acid site distribution of zeolite catalysts on the diffusion rate of small alkenes and alkanes in a confined porous environment. The cover shows that the interaction of ethene with Brønsted acid sites (yellow dots) facilitates the diffusion through the catalyst, leading to a shorter diffusion path for ethene (blue) compared to the diffusion of ethane (orange) which follows a random trajectory. Our findings highlight that the acid distribution in the zeolite catalyst is an important design parameter for diffusion limitations which may open up interesting perspectives for catalysis or separation purposes.

Image: Ella Maru Studio

Designing new zeolite catalysts with a higher selectivity and lifetime remains one of the biggest challenges for the chemical industry. The selectivity for catalytic processes in acid zeolites is not only determined by the chemical reactivity but also by the transport phenomena of the reactants and products, which may become hindered in the confined zeolite environment. The diffusion and residence time of small (un)saturated hydrocarbons through the nanopores of the zeolite is of fundamental importance for many catalytic conversions, resulting in a significant impact on the ultimate product selectivity and separation. In this context, strategies to enhance the diffusion of desired products such as light olefins while limiting the diffusion of undesired products such as paraffins look very promising when tuning the catalyst design. By means of a synergistic theoretical and experimental approach, we showed that the presence of Brønsted acid sites on the catalyst promotes the diffusion of ethene and propene through the pores of H-SAPO-34, whereas the diffusion of ethane and propane is insensitive for the acid site density. The enhanced diffusivity of unsaturated hydrocarbons can be ascribed to the formation of favorable alkene π-H interactions with the acid sites, as confirmed by IR spectroscopy measurements. Our results demonstrate that dedicated acid site distributions in the confined framework may significantly affect the product selectivity, thus leading the way for future developments in the field of zeolite catalysis.

This publication is the result of a joint international collaboration, led by the Center for Molecular Modeling (CMM) at Ghent University, together with the Center for Material Science and Nanotechnology (SMN) at the University of Oslo, the National Institute for Advanced Materials at Nankai University, the Institute of Chemical Technology at the University of Stuttgart and the Department of Chemistry, NIS centre of excellence, at the University of Turin. Read the full article here.

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CMM paper on the cover of ChemPhysChem

For a new publication, titled "Structural and photophysical properties of various polypyridyl ligands: A combined experimental and computational study", in the ChemPhysChem Journal (Impact factor 3.144), the CMM made the cover for the journal issue of November 2020. ChemPhysChem is one of the leading chemistry/physics interdisciplinary journals for physical chemistry and chemical physics. The cover shows the interaction between visible light and the building blocks of covalent triazine frameworks, which are promising heterogeneous catalysts. The manuscript shows, via a combined computational and experimental study, that the position of the main absorption peak in the UV-Vis spectra of the building blocks of covalent triazine frameworks can be shifted significantly to lower energies by adding NH2.

CMM in Nature Catalysis on Molecular Palladium in Zeolites

Shape selective C-H activation using Molecular Palladium in Zeolites

An international collaborative study led by the Centre for Membrane separations, Adsorption, Catalysis and Spectroscopy for Sustainable Solutions (cMACS) at KU Leuven, in collaboration with the Center for Molecular Modeling (CMM) at Ghent University, the Smart Materials Research Institute at the Southern Federal University (Russia) and the National Institute of Chemistry (Slovenia) has shown that cationic palladium hosted in zeolites can catalyse C-H functionalization reactions with unprecedented shape-selectivity. The findings introduce a novel concept to the field of catalysis, in which exceptional control of selectivity can be achieved in transition metal (TM) catalysed arene C-H activation through the spatial confinement of TM sites in zeolite pores.

An ongoing challenge in the fine chemical industry is to design and identify catalytic systems that are both highly recyclable and easy to separate from products, and can exhibit high selectivity and activity towards the target transformation. In this context, TM-exchanged zeolites are promising candidates as they offer the possibility to combine the strengths of homogeneous and heterogeneous catalysis to afford a superior class of catalyst for use in industry. A particular reaction of high interest in industry is the catalytic coupling of aromatics to form biaryl motifs, which are extensively found in fine chemicals. Under traditional cross-coupling conditions the aromatic reagents must be pre-functionalized, therefore leading to extra steps and costs in the synthesis. For this reason, in recent years attention has shifted towards the direct C-H C-H coupling of aromatics. Homogeneous catalysts are now very well-developed for this purpose, but the development of analogous single-site heterogeneous catalysts can offer unique advantages. For example, the microscopic pores and channels present in the zeolite catalyst may direct regioselective activation of specific C-H bonds, while site isolation of the active metals can limit the catalyst deactivation caused by the aggregation of metallic nanoparticles.

Researchers at KU Leuven identified that cationic palladium can dock to zeolite H-Beta in a stable fashion, and effectively catalyse the oxidative homocoupling of toluene to produce bitolyl in high turnover numbers. Moreover, of the 6 possible isomers that could be formed in the reaction, p,p’-bitolyl is produced with an unprecedented 80 % selectivity, while the yield of products featuring at least one para-substituted aryl group reaches a staggering 97 %. Interested in both the mechanism of this Pd-Beta catalysed coupling reaction and the origin of this unprecedented shape-selectivity observed for the oxidative homocoupling of toluene, researchers at the CMM employed a combination of static and dynamic Density Functional Theory (DFT) calculations on the Pd-Beta system to investigate the reaction. The proposed catalytic cycle, supported by advanced experimental characterization techniques, shows how the confinement effects of the framework can induce the exceptional selectivity, thus leading the way to further development in the field of zeolite-supported single-site transition metal catalysts. The findings have been published in the journal Nature Catalysis. Read the article here.

CMM with UCL London in Nature Materials

An international study led by the Chemistry Department at University College London (UCL) in collaboration with the Center for Molecular Modeling (CMM) at Ghent University and the Central Laser Facility (CLF) has made a new and unexpected discovery about industrial catalysts that could help to increase the efficiency of the production of chemical building blocks from non-fossil feedstocks such as methanol. Their findings could lead to a reduction of the cost and environmental impact of the process, making it a viable alternative to fossil fuels.

Methanol conversion towards chemicals of higher energy density is a sustainable alternative to fossil fuels. To spur the chemical reactions needed to turn methanol into complex chains of carbon like gasoline industrial catalysts are used. One of the most popular catalysts are zeolites, which are microporous, crystalline structures made up of silicon, aluminium and oxygen atoms that form a framework of cavities and channels, known as pores. Their structure means they are often referred to as molecular sieves. The stability and efficiency of zeolites is a major concern, as the build-up of carbon deposits tend to block the pores, eventually leading to deactivation of the process. At this point, the zeolite must be replaced or reactivated through an expensive, energy-intensive and environmentally unfriendly industrial process that effectively burns away whatever is hindering the catalytic process. These zeolites are of high value to industry and discovering why zeolites deactivate and precisely when the process starts is of great interest to scientists and to industry.

Researchers at UCL, UGent, and CLF were able to provide answers to these questions by applying Kerr gated Raman spectroscopy in combination with molecular simulations. Raman spectroscopy is one of the most common techniques used to investigate catalysis as it can tell which molecules are present during the reaction. However, it suffers from background fluorescence that easily drowns out the Raman signal of interest. That is where the Kerr gate comes into play. In contrast to Raman fluorescence, which is an instantaneous process, the background fluorescence is delayed by a few picoseconds. The Kerr gate can filter out this unwanted fluorescence leaving scientists with a clear Raman signal to read.

Using Kerr gated Raman spectroscopy the team succeeded to resolve the molecular fingerprints at all stages of the catalytic reaction. To interpret the complex Raman spectra, containing contributions from a lot of different hydrocarbons that were produced during the process, molecular simulations were performed by CMM researchers. The combination of experimental observations and theoretical calculations enabled to pinpoint the presence of important hydrocarbon species during the process. In particular, they were able to identify what sort of hydrocarbon was being formed at the moment the catalyst started to deactivate – like catching a criminal holding a knife at a murder scene, they were able to catch the culprit red handed.

In the past, it had been thought that a species of hydrocarbon called polycyclic aromatics (polyaromatics) were the main deactivating agents, but the new research has shown that this is not the case. In fact, shortly before the polyaromatics are formed, another species called polyenes are formed and, in fact, it is they that are present at the moment the catalyst started to deactivate. This was a completely new and unexpected discovery. ‘I think that this will change the way people think about how these materials deactivate because, as soon as you know who the culprits are, you are able to design a strategy,’ said teamleader Andy Beale of UCL.

There is a huge energy cost, as well as time cost, associated with reactivating catalysts frequently, so anything that can keep catalysts doing their job for longer will save money, energy and reduce the environmental impact – resulting in greener fuels. The study could be significant for industry especially as methanol can be produced from biomass stocks – meaning that gasoline may not have to come from fossil fuel stocks in the future.

The project is an ongoing collaboration between University College London, Ghent University, the Central Laser Facility, and the Catalysis Hub – a consortium created with the aim of establishing a world-leading programme of catalytic science in the UK. The findings have been published in the journal Nature Materials.

Read the article here.

Ph.D. position available in the field of Modelling C1 catalysis in nanoporous zeolite materials at operating conditions to convert new feedstocks

The research group of prof. Van Speybroeck, embedded within the multidisciplinary Center for Molecular Modeling at Ghent University, Belgium (CMM, http://molmod.ugent.be), is looking for a highly motivated researcher to perform state-of-the-art research in the field of theoretical modeling of catalysis in nanoporous zeolite materials. We especially welcome candidates with a strong track record who may become eligible to apply for a prestigious Ph.D. fellowship at our national funding agency (FWO).

More info about the CMM

The CMM groups about 40 researchers of the faculties of Science and Engineering and Architecture with molecular modeling interests and is unique in the university as it clusters researchers with various backgrounds, from various departments and faculties. The CMM aims to model molecules, materials and processes at the nanoscale by bringing together physicists, chemists, (bio-)engineers and stimulating collaborations across disciplines. This multidisciplinary collaborative mission is the DNA of the CMM and key to achieve scientific excellence in the field of molecular modeling.

The CMM focuses on frontier research in six major areas: chemical kinetics in nanoporous materials, computational material research on the nanoscale, spectroscopy, many-particle physics, model development and bio- and organic chemistry. The six areas define the core-business of the main activities, and research in each of them is performed within the frame of a strong network with partners at Ghent University, in Flanders and at an international level. The research of this Ph.D. position is situated in the “Nanoporous Materials” research area, however to pursue excellence we strongly stimulate interactions between the various researchers in our team as well as with our vast network of national and international partners. The research of the CMM is internationally regarded to be at the forefront in its field.

The prospective candidate will join a strongly connected research team and will collaborate with national and international academic partners. He/she will benefit from the experience present in the research group to model chemical transformations at operating conditions. A strong body of expertise was developed in this area in the framework of various ERC grants.

More info about the research topic

This PhD research will focus on modelling C₁ catalysis in nanoporous zeolite materials. C₁ catalysis – the conversion of one-carbon molecules such as CO₂, CO, CH₄, CH₃OH into high-value platform chemicals and liquid fuels – has attracted widespread attention in the quest for reducing anthropogenic greenhouse gas emissions. The conversion of non-fossil feedstocks like biomass as well as to recycle CO₂ into high-value chemicals, requires the design of next generation multifunctional catalysts which are highly selective and also robust in a broad operation window. In general, the activation of thermodynamically stable C₁molecules like CO₂ and their transformation to olefinic and aromatic products, the main building blocks of the chemical industry, is highly challenging. Thanks to their specific porous nature, zeolite materials will play a prominent role in the conversion of C₁ compounds. A thorough understanding of the persistent intermediates and governing reaction mechanisms is essential to improve the catalyst efficiency and selectivity. More specifically, for the conversion of CO₂ into hydrocarbons, the precise mechanism for C-C bond formation and the role of the presence of CO, CO₂, H₂ and H₂O in the reaction environment are so far improperly understood. Nevertheless, such fundamental insight is still lacking. To this end, computational modeling can prove a powerful method to aid in the understanding of the process and the design of next-generation multifunctional catalysts. In this Ph.D. research, you will systematically investigate C-C coupling reactions in the presence of CO, H₂ and H₂O for a variety of process conditions. Various reactions are closely related to the mechanisms found within the Methanol-to-hydrocarbons (MTH) process. Therefore, several aspects of the conversion of CO₂ and CH₃OH species on different zeolite catalysts will be investigated using a large set of modeling techniques. By applying a combination of molecular dynamics (MD) simulations and density functional theory (DFT) calculations, you will perform a mechanistic study on the role of CO₂ in these processes, taking into account the complex molecular environment and actual reaction conditions. The research topic will be conducted in close collaboration with excellent experimental groups to guide the design toward new and promising functional materials. Several collaborative research papers which illustrate our efforts in this area (CO₂-to-hydrocarbons and methanol to hydrocarbons) are cited below.^1–4

(1) Ramirez, A.; Dutta Chowdhury, A.; Dokania, A.; Cnudde, P.; Caglayan, M.; Yarulina, I.; Abou-Hamad, E.; Gevers, L.; Ould-Chikh, S.; De Wispelaere, K.; Van Speybroeck, V.; Gascon, J. Effect of Zeolite Topology and Reactor Configuration on the Direct Conversion of CO2 to Light Olefins and Aromatics. ACS Catal. 2019, 9 (7), 6320–6334.

(2) Yarulina, I.; Wispelaere, K. D.; Bailleul, S.; Goetze, J.; Radersma, M.; Abou-Hamad, E.; Vollmer, I.; Goesten, M.; Mezari, B.; Hensen, E. J. M.; Martínez-Espín, J. S.; Morten, M.; Mitchell, S.; Perez-Ramirez, J.; Olsbye, U.; Weckhuysen, B. M.; Speybroeck, V. V.; Kapteijn, F.; Gascon, J. Structure–Performance Descriptors and the Role of Lewis Acidity in the Methanol-to-Propylene Process. Nat. Chem. 2018, 10 (8), 804.

(3) De Wispelaere, K.; Wondergem, C. S.; Ensing, B.; Hemelsoet, K.; Meijer, E. J.; Weckhuysen, B. M.; Van Speybroeck, V.; Ruiz-Martı́nez, J. Insight into the Effect of Water on the Methanol-to-Olefins Conversion in H-SAPO-34 from Molecular Simulations and in Situ Microspectroscopy. ACS Catal. 2016, 6 (3), 1991–2002.

(4) Westgård Erichsen, M.; De Wispelaere, K.; Hemelsoet, K.; Moors, S. L. C.; Deconinck, T.; Waroquier, M.; Svelle, S.; Van Speybroeck, V.; Olsbye, U. How Zeolitic Acid Strength and Composition Alter the Reactivity of Alkenes and Aromatics towards Methanol. J. Catal. 2015, 328, 186–196.

Who are we looking for?

We are looking for a highly motivated and creative Ph.D. candidate with:

An excellent master’s degree of an international equivalent in the field of Chemistry, Chemical Engineering, Physics, Physical Chemistry or a related field;
A strong interest in molecular modelling;
Excellent research and scientific writing skills;
Perseverance and an independent, pro-active working style;
The willingness to look beyond the borders of his/her own discipline and a strong motivation to work in a multidisciplinary team;
Experience with quantum chemistry software (Gaussian, VASP, CP2K,…) and coding (Python, C, ...) is an advantage.
Excellent collaboration and communication skills (written and verbally) in English

What can we offer you?

The selected candidate will get the ability to strengthen his/her CV within the context of a strongly motivated and multidisciplinary research team and have to ability to contribute to challenging topical research to solve important societal questions. He/she will have the opportunity to attend various international conferences and to include research stays abroad in the most prominent international research teams in this field within the framework of his/her Ph.D. The successful candidate will end up in a University with a strong PhD community that offers a broad range of training possibilities for PhD candidates, both within the research topic and focused on transferrable skills (e.g. time management, presentation skills, leadership, etc.).

How to apply?

It is the intention to fill this position as soon as possible. Students who will obtain their Master degree in June/July are also eligible. For more information on the position or the CMM, candidates can get in touch with Prof. Veronique Van Speybroeck (Veronique.vanspeybroeck@ugent.be).

Interested candidates are requested to prepare the following documents:

The filled out application form (see Application-Form.doc)
A motivation letter
A curriculum vitae
Copies of the relevant diplomas and grade lists

All these documents should be send to cmm.vacancies@ugent.be, according to the guidelines mentioned in the application form.

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