Analysis of forced periodic operation of chemical reactors considering methanol synthesis as an example

• Applicants: Professor Dr.-Ing. Achim Kienle; Dr.-Ing. Daliborka Nikolic Paunic; Professor Dr.-Ing. Andreas Seidel-Morgenstern
• Subject Area: Chemical and Thermal Process Engineering
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 406561907

The proposed project provides new methods and tools for a rigorous evaluation of forced periodic operation of chemical reactors. In the first period, focus was on methanol synthesis from H2/CO2/CO using an industrial Cu/ZnO/Al2O3 catalyst in a gradientless isothermal reactor. It was shown theoretically that reactor performance can be improved significantly through forced periodic operation. In the second period results will be validated experimentally and the theoretical and experimental analysis will be extended to non-isothermal fixed bed reactors, which are often applied in practice. Heat effects introduce additional constraints but also introduce additional degrees of freedom for forced periodic reactor operation. Besides methanol synthesis also forced periodic operation of methanation will be studied in cooperation with the experts in the SPP.To achieve our goals, the project combines the profound expertise of Dr. Nikolić-Paunić from Belgrade University in nonlinear frequency response analysis with rigorous mathematical optimization and careful experimental validation to be done in Magdeburg and Freiburg. Dr. Nikolić-Paunić has contributed significantly to the project in the first period and will replace Prof. Petkovska, who will retire.In our approach, nonlinear frequency analysis is used for a quick evaluation of the possible improvement for different combinations of input variables. It also provides good initial guess for further optimization. Due to the underlying simplifying assumptions of the nonlinear frequency response analysis, results have to be further refined in a second step using rigorous mathematical optimization to provide suitable conditions for the planned experimental validation. In particular, more detailed kinetic models, additional degrees of freedom and constraints arising from the experimental setup and the operating conditions can be taken rigorously into account. For this purpose the kinetic model developed in the first period will be further refined in cooperation with SPP partners which provide the required expertise in heterogeneous catalysis.In addition, the methodologies for nonlinear frequency analysis, parameter identification and numerical optimization need to be extended significantly to handle systems of partial differential equations arising from the modeling of fixed bed reactors compared to ordinary differential equations, which are used in the first funding period for the description of a gradient free reactor. The finally planned experimental demonstration of forced periodic operation will serve to validate the methods and models and to evaluate the applicability and the potential of this new dynamic reactor operation concept.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2080: Catalysts and reactors under dynamic conditions for energy storage and conversion
• International Connection: Serbia