The flow systems in most chemical processes are multiphase flows and not transparent. We will develop a MRI flow imaging tool that can visualize the flow, which we cannot see with optical (camera) techniques. This tool will be used to provide high quality data sets that can be used to validate complex computational flow models of the chemical processes studied within the Gravitation Programme.

Project leader: Prof. Hans Kuipers

The Fischer-Tropsch process is widely applied to convert a variety of resources, such as gas, biomass and coal, to fuels. The reactions in this process are very fast, which makes that transport to the catalyst, which performs the reaction, is often limiting the reaction rate. As a result, the process is not optimally efficient, but even worse, the product composition will deviate. In this project, we will design a new catalytic reactor with a very accessible structured solid foam catalyst, optimizing the transport properties on all length scales, from the nanometer scale of the active site where the reaction occurs up to the meter scale of the reactor itself.

Project leader: Prof. Hans Kuipers

The Fischer-Tropsch process is widely applied to convert a variety of resources, such as gas, biomass and coal, to fuels. The reactions in this process are very fast, which makes that transport to the catalyst, which performs the reaction, is often limiting the reaction rate. As a result, the process is not optimally efficient, but even worse, the product composition will deviate. In this project, we will design a new catalytic reactor with a very accessible structured solid foam catalyst, optimizing the transport properties on all length scales, from the nanometer scale of the active site where the reaction occurs up to the meter scale of the reactor itself.

Project leader: Prof. Jaap Schouten

Particles half-coated with a metal or other material that catalytically decomposes H2O2 are used extensively as a model system of self-propelled particles, albeit almost exclusively in 2D. Because of the catalytic decomposition reaction, which drives the particles far out of equilibrium, many new phenomena of Self-Assembly and pattern formation occur in these systems. As the mechanisms of self-propulsion in this system are still poorly understood, especially in the bubble-propulsion regime, we will study these in detail. We will use a new bulk synthesis method and systematically change the surface polarity of the catalyst. Here we also want to extend the study of this model system to 3D and quantitatively study its behavior on the single particle level as a function of concentration. We will also apply external electric fields to anisotropic self-propelled systems, so that the rotational motion of the particles can be influenced. In addition, we want to explore and optimize this system for (two-phase) catalysis systems, for instance to improve mixing, prevent catalyst-particle clustering, and reduce boundary layers around the catalysts.

Project leader: Prof. Alfons van Blaaderen

A variety of large-scale manufacturing and transport processes encounter dispersed multiphase flows, i.e., flows with dispersed bubbles or particles. These in particular include flows in chemical plants and flows in which catalytic chemical reactions occur, such as in the Fischer-Tropsch method. All these dispersed multiphase flows are not laminar, but turbulent.

The questions we want to address in this project are: How do bubbles affect mixing of reactants (or in general a scalar field) in such bubbly turbulent flows? How do bubbles change the mixing efficiency? What are the optimal parameters for the mixing of reactants?

In the present project, we propose to study the mixing of passive scalar fields such as in reaction products out of a catalytic reaction (on floating microparticles) in a freely rising bubble swarm. In addition, we intend to investigate the effect of turbulence on the mixing, aiming to address the interplay between the bubbles, the catalytic particles, and turbulent fluctuations on the mixing in turbulent multiphase flows.

Project leader: Prof. Detlef Lohse

Slurry bubble column reactors are used for a wide range of reactions in chemical and biochemical industry. In such a reactor, bubbles with a reactant gas is sparged into a suspension of liquid with solid catalyst particles. The slurry bubble column reactor is viewed as one of the most promising methods to produce synthetic fuels through the so-called Fischer-Tropsch process. However, a successful design and scale-up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, and heat and mass transport characteristics. Researchers from Eindhoven University of Technology and University of Twente will use detailed computer simulations to obtain this understanding, combine experiments and computer simulations to understand the role of turbulence on structure formation in the gas and solid distribution, and develop an efficient large-scale simulation method for real large scale applications.

Project leader: Prof. Hans Kuipers