The research focus Separations and Experiments investigates membrane and adsorption based separation processes and serves as a cross-section in terms of experimental work to the other research focuses. We have a vast experience in process development and optimization based on experimental investigations and process simulation. Our process simulation experience covers additional separation unit operations like rectification. Contact persons for this research focus are Christian Jordan (contact information, opens an external URL in a new window), Markus Bösenhofer (contact information, opens an external URL in a new window) or Walter Wukovits (contact information, opens an external URL in a new window).

Gas permeation, pervaporation and nanofiltration are the main membrane-based separation processes that we currently investigate. Gas permeation describes a process, where the variation of permeability through a typically non-porous polymeric membrane is used to separate or enrich gas components in mixtures. Common processes are e. g. the biogas upgrading (removal of carbon dioxide from methane) or the hydrogen extraction from the natural gas grid (to utilize the grid for hydrogen transport and distribution) 

Contrary, pervaporation is a method to remove components from liquid mixtures, where a polymeric or ceramic membrane is used to enhance the separation by evaporation with the selectivity of the transmembranic transport. One typical process is the collection of e. g. solvents (acetone, butanol, ethanol) produced from diluted fermentation broth. An other process utilizes membranes to remove small fractions of water from azeotropic mixtures or from esterification reactors. 

Nanofiltration can also be used in biotechnological production to treat liquid streams with dissolved organic and inorganic components, for example to enrich lactic acid from silage juice, or to collect amino acids. In combination with other separation steps like ultrafiltration or adsorption, nanofiltration can be utilized to remove coloured components from starch hydrolysates or as an energy saving pre-treatment step to concentrate thin juice in sugar industry.

The pressure swing adsorption (PSA) is the main adsorption-based process in our research portfolio for gas separation. PSA is a pseudo-continuous (combination of multiple batch stages) process to remove specific components (adsorptive) from gas streams. The adsorptive is adsorbed to the adsorbent at high pressure, while it is removed at low pressures. 

As for absorption (selective dissolution of gaseous components in washing fluid), a new hydrogen sulfide removal process has been developed and patented with an industrial partner, which relies on using different time scales/dissolution kinetics to remove the trace contamination from a carbon dioxide rich biogas stream in a very compact spray column reactor. This is not only necessary to protect the subsequent membrane stages from damages, but also essential for biogas grid injection to meet the standards. 

Experimental and separations activities are accompanied with modeling and simulation to gain additional insight to process steps and to investigate the behavior and performance in complex process chains. Short cut design methods can be used for benchmarking different process steps with equilibrium calculation and for simple sensitivity analysis based on experimental results. The integration of process steps to an overall process even at an early stage of project will contribute to debottlenecking, push/guide experimental investigation in critical process steps and indicating process routes/parameters that will enhance the sustainability, environmental, and economic performance of a process.

One key application of our separation processes is gas cleaning, e.g., hydrogen separation from natural gas and hydrogen cleaning and purification. Our research group has a long track record of research projects and patents in this field. 

Separation processes are also important in other experimental setups, e.g., membrane reactors. Membrane reactors remove reaction products during the process to increase the yield of equilibrium reactions – as mentioned before by e. g. water removal from esterification reactions. One process development involves the utilization of carbon dioxide as a valuable raw material by producing diethyl carbonate with ethanol for use in industry (as an electrolyte additive for batteries or as e-fuel constituent).  

The experimental investigation of separation processes is one of our core expertise. We have developed and operate various membrane testing and other gas separation equipment. Besides the test facilities, we developed a custom membrane spinning and a custom coating plant for hollow fiber membranes. 

Our second core expertise is in the field of fluid dynamics. We operate a Laser-Doppler-Velocimetry (LDV) and a Particle-Image Velocimetry (PIV) system to investigate fluid dynamic problems and validate our computational fluid dynamics (CFD) models. 

Recently, we got involved in experimental activities in the thermochemical conversion of solids. In cooperation with our project partner K1-MET GmbH, we operate a unique high temperature, elevated pressure, and high heating rate reactor to investigate pulverized solids conversion. 

In general, we have a vast experience in many chemical engineering applications. A non-exhaustive list is given by: 

• Determination of physical and thermodynamic properties (TGA/DSC, VLE, sugar- and lignin solubility) 

• Lignin extraction and precipitation  

• Gas-powder flows 

• Thermochemical conversion of powders 

• Analytical lab-scale burners 

We developed and operated various custom experimental setups for our co-operation partners in the past. On this site, you can find an overview of currently available equipment.