Meso-scale modeling in catalysis

The rational design of next-generation catalysts that will contribute to solving the impending energy and environmental challenges requires accurate description of mesoscale phenomena in catalysis. Current state-of-the-art modelling techniques mostly focus either on the nanoscale description of individual elementary reaction steps or on the macroscale to describe behavior of reactors, usually employing lumped reaction kinetics. In this project, new modelling tools are developed to study emergent phenomena at the mesoscale that lead to evolution of the catalyst structure as a result of changes in the surface adsorbed layer. In detail, we investigate the complex processes occurring in the Fischer-Tropsch reaction, an industrially important reaction for the synthesis of transport fuels and chemicals. In this reaction, many important details remain unclear: the influence of lateral interactions, surface reconstruction under catalytic conditions, migration of adsorbates between different surface facets of nanoparticles and deactivation due to strongly adsorbing reaction intermediates are far from understood. Describing these mesoscale phenomena with sufficient accuracy leads to opportunities to guide the design of novel improved catalysts.

Project leader: Dr. Ivo Filot

Liquid-phase TEM and cryo-TEM of fundamentals of catalyst assembly

Melt infiltration and deposition precipitation of metals or metal precursors will be investigated at the fundamental level for the assembly of solid catalysts for a wide range of conversions. The fundamental study will heavily rely on electron microscopy using novel developments of liquid-phase TEM (UU) and cryo-TEM (TU/e).

Project leader: Prof. Krijn de Jong


Supraparticles for Catalysis

The Soft Condensed Matter group at UU was among the first to investigate both in experiments and simulations the self-assembly (SA) of nanoparticles (NPs) inside the confinement of slowly drying liquid emulsion droplets. The resulting colloidal crystalline ‘supraparticles’ (SPs) have sizes still in the colloidal domain, so that another SA step is possible. It was found that the spherical confinement influences the SA process in intriguing and important ways compared to bulk SA. Here we want to use the experience obtained and optimize binary SPs for C1 catalysis (Fischer-Tropsch FT) using monodisperse Fe-Co-oxide NPs as the main component for the SP synthesis. We will mainly focus on visco-elastic high shear processing to obtain relatively monodisperse droplets. Initially, the NP synthesis, using existing procedures, will need to be optimized for FT catalysis (particles size, composition, stabilizer removal). Secondly, we will focus on binary SPs with structural analogs with a NaCl lattice, but also will explore different binary options. The second component (silica or polymer) can be used to induce extra stability to the catalytic NPs (e.g. against sintering) and/or to optimize the flows of heat and chemicals for FT catalysis.

Project leader: Prof. Alfons van Blaaderen

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Influence of wall corrugation on mass transfer in liquid catalytic reactors

In many catalytic reactors, a liquid flow is used to enhance the mass transfer to and from catalytic sites dotted on solid surfaces. Direct Numerical Simulations can be used to investigate this mass transfer, but the boundaries between the solid and liquid are necessarily treated as smooth on sub-grid length scales. In reality, solid surfaces are usually corrugated on length scales of micrometers. In this project we will perform a fundamental investigation of the coupled convection-diffusion-reaction mechanisms in the boundary layer near corrugated walls. This will lead to correlations for sub-grid-scale corrections to the mass transfer rates.

Project leader: Dr. Johan Padding

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Realistic Systems: multi-component intra-particle transport

Full title: Realistic Systems: multi-component intra-particle transport + catalytic conversion and coupling of multi-component particle model to MC-DNS-boundary Layer effects in catalytic conversion: MC-DNS study of coupled heat and mass transfer with catalytic surface reaction

For the design and operation of many processes in chemical industry it is important to fully understand the reactions that occur and at what rates. Catalytic reactions often take place at surfaces deep inside porous particles. Therefore it is needed to know how reactants are transported inside these particles and how products move out. The transport of substances to and from the so-called catalytic sites inside the porous particle partly determines the rates at which the reactions occur.

In this project the flow of reactants and products around catalytic particles is modeled as well as the transport inside the particles and the reactions that occur there. Using a massive computational model we aim at predicting the performance of a catalytic process by computer simulation. These simulations will give insight in the interplay of transport and reactivity. Using the detailed information the model provides real chemical processes can be improved and in that way technological development is accelerated.

Project leader: Prof. Hans Kuipers

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Kinetics and mechanism syngas chemistry

Synthesis gas is an increasingly important platform for conversion of carbon-containing feedstock to fuels and chemicals, with the Fischer-Tropsch process to convert natural gas to transportation fuels being commercialized by several industrial partners. This reaction is very complex because the mechanism has not been resolved yet. Many proposals exist for it and under industrial conditions hundreds of elementary reactions are involved in obtaining the polymerized products. In this project, we will combine a nanoscale description of the individual reaction steps in the Fischer-Tropsch reaction obtained by quantum-chemical calculations with a reactor engineering model to predict the overall catalyt performance. This holds the promise of identifying how to improve the current generation of catalysts towards optimum performance. The tool that we develop is also applicable to other processes so that we can also make predictions for instance for the production of chemicals from synthesis gas. The project uniquely combines work at the level of reacting molecules, phenomena at the millimeter level in catalyst bodies and at the meter-length scale in chemical reactors.

Project leader: Prof. Emiel Hensen

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Direct conversion of synthesis gas to aromatics

Synthesis gas (CO + H2) is a versatile intermediate to convert carbon-containing feedstocks such as biomass to fuels and chemicals. For the production of olefins and aromatics from synthesis gas currently a multi-step process is needed, that is syngas is first converted to methanol over a copper catalyst and then methanol to hydrocarbons using a zeolite catalyst. We intend to investigate the possibility to convert synthesis gas directly to aromatics using a hybrid catalyst. The design of the catalyst aims at syngas conversion to light hydrocarbons (olefins, paraffins) in combination with a selective acid function for conversion to (specific) aromatics. Fundamental understanding and improvement of catalyst stability and selectivity will a main thrust of this research. UU expertise on catalyst design, characterization and performance will be combined with TU/e expertise on mechanistic, kinetic and reactor modelling.

Project leader: Prof. Krijn de Jong

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