Dr.-Ing. Tobias Kleetz
Curriculum Vitae
| Born | April 5th, 1988 in Datteln (Germany) |
| 1998-2007 | Theodor Heuss Gymnasium, Waltrop (Germany) |
| 2007-2011 | B.Sc. Biochemical Engineering Studies, TU Dortmund University, Bachelor thesis: Start-Up of a Miniplant for the Continuous Processing of Binary Reaction Mixtures by Means of scCO2 |
| 2011-2012 | M.Sc. Biochemical Engineering Studies, TU Dortmund University, Master thesis: Measuring and Modeling the Phase Behavior and Drug Release of Solid Dispersions |
| 01/2013-04/2013 | Process engineer in a pharmaceutical company (Rottendorf Pharma) |
| 2013-2016 | PhD at the Laboratory of Plant and Process Design, TU Dortmund University, Field of research: Development and Scale-Up of gassing crystallization processes |
Field of Research
The application of crystallization in biotechnological processes is limited due to no reliable scale-up methods from laboratory to industrial scale. Especially in case of big molecules and substances with agglomeration tendency there is a lack of transferability. There is no method available to control the process and get a constant product quality. Up-to-date, the method of choice is to control a crystallization process is seeding with difficult produced seed crystals. In order to avoid the risk of contamination due to seed crystals induced nucleation methods like gassing or insonation can be used, but these have not been proved in industrial scale yet.
Objective of the project is the development of a laboratory method that enables a reliable scale-up of crystallization processes. A particular emphasis should be put on the induced nucleation process gassing to ensure constant product quality like crystal form, mean crystal size, crystal size distribution and purity. The scale-up concept is based on the idea to find a key-factor for gassing crystallization, which is suitable to control product quality. A first step will be to characterize the gassing process due to the influence of several gassing parameters (gas flow, gassing period, initial supersaturation, stirrer speed) on the total bubble surface, which is known to act as surface for heterogeneous nucleation. Target values are characteristic diameters (d50, d90), the crystal size distribution (d90-d10) and the cooling profile. With the help of statistical analysis tools, heuristics should be derived to find suitable gassing parameters to ensure constant product quality on different scales.
Publications
Dissertation
- T. Kleetz
A Contribution to Design Gassing Crystallization Processes
TU Dortmund, 2017, Verlag Dr. Hut, München ISBN 978-3-8439-3550-03
Paper
- T. Kleetz, R. Scheel, G. Schembecker, K. Wohlgemuth
Cooling Crystallization: Does Gassing Compete with Seeding?
Crystal Growth & Design (2018), doi.org/10.1021/acs.cgd.7b01781
- T. Kleetz, G. Paetzold, G. Schembecker, K. Wohlgemuth
Gassing Crystallization at Different Scales: Potential to Control Nucleation and Product Properties
Crystal Growth & Design 17 (2017) 1028–1035, doi.org/10.1021/acs.cgd.6b01280
- T. Kleetz, F. Funke, A. Sunderhaus, G. Schembecker, K. Wohlgemuth
Influence of Gassing Crystallization Parameters on Induction Time and Crystal Size Distribution
Crystal Growth & Design 16 (2016) 6797-6803, doi.org/10.1021/acs.cgd.6b00895
- T. Kleetz, F. Braak, N. Wehenkel, G. Schembecker, K. Wohlgemuth
Design of Median Crystal Diameter Using Gassing Crystallization and Different Process Concepts
Crystal Growth & Design 16 (2016) 1320-1328, doi.org/10.1021/acs.cgd.5b01428
Oral presentations
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Nucleation kinetics as measure of the effect of gassing crystallization in various scales
Jahrestreffen der ProcessNet-Fachgruppe Kristallisation, Frankfurt a.M., Germany (2016)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Design of median crystal diameter using innovative gassing crystallization on different scales
Kristallisationssymposium 2015 - A better Route to optimized Crystallization Processes and Product Quality, Frankfurt a.M., Germany (2015)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Design of median crystal diameter using innovative gassing crystallization on different scales
10th European Congress of Chemical Engineering (ECCE10), Nice, France (2015)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Scale-up of gassing crystallization processes with respect to an optimal product quality
Himmelfahrtstagung der DECHEMA (Scale-up and scale-down of bioprocesses), Hamburg, Germany (2015)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Using gassing crystallization for the design of product quality at different scales
Jahrestreffen der ProcessNet-Fachgruppe Kristallisation, Magdeburg, Germany (2015)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Gassing crystallization – A concept for process development and scale-up
Fifth Annual Retreat of the CLIB-Graduate Cluster, Lünen, Germany (2014)
Poster presentations
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Design of mean crystal diameter using gassing crystallization at different scales
Seventh Annual Retreat of the CLIB-Graduate Cluster, Herdecke, Germany (2016)
- G. Schembecker, T. Kleetz, K. Wohlgemuth
Design of median crystal diameter using innovative gassing crystallization on different scales
22nd International Workshop on Industrial Crystallization (BIWIC2015), Daejeon, South Korea (2015)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Design of mean crystal diameter using gassing crystallization at different scales
Sixth Annual Retreat of the CLIB-Graduate Cluster, Wermelskirchen, Germany (2015)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Development and analysis of gassing crystallization processes on lab scale
Fifth Annual Retreat of the CLIB-Graduate Cluster, Lünen, Germany (2014)
- T. Kleetz, K. Wohlgemuth, G. Schembecker
Influence of process parameters from gassing crystallization on process development and product quality
Jahrestreffen der Fachgruppe Kristallisation/Process Net, Münster, Germany (2014)