Integrated design of adsorbents and processes using PC-SAFT and classical density functional theory

• Applicant: Professor Dr.-Ing. Joachim Groß
• Subject Area: Technical Thermodynamics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 496559772

The success of adsorption-based processes in chemical and energy engineering strongly depends on the choice of the material used as the adsorbent. The molecular design space provides a vast number of possible adsorbents, allowing for a tailor-made design of materials for a specific application. However, choosing the right adsorbent for a specific application is challenging as the choice of materials depends directly on the design of the process itself and vice versa. Therefore, the adsorbent has to be designed simultaneously with the process to identify the optimal adsorption-based process.In this project, we develop a novel methodology for an integrated design of adsorbent and process. For this purpose, we explore how the adsorbent can be designed as a degree of freedom within the process optimization. The key of the method is the physically-based thermodynamic model, which describes the interaction between adsorbents and adsorbates in an efficient and thermodynamically consistent way. Here, we use the PC-SAFT equation of state combined with classical density functional theory (DFT) as the thermodynamic model. Our thermodynamic model is continuously enhanced within this project to meet the requirements arising from developing the integrated design methodology. The enhanced thermodynamic model is directly linked to a model of the process. The idea of the integrated design methodology is to circumvent the discrete molecular decision arising from the selection or design of the adsorbent. In contrast, we define a hypothetical adsorbent by treating the parameters representing an adsorbent in the thermodynamic model as continuous design variables. These adsorbent parameters are optimized simultaneously with process degrees of freedom, leading to an optimal, hypothetical target material and the corresponding optimized process. In a subsequent step, the thermodynamic model parameters representing the hypothetical adsorbent are mapped onto a database to identify an existing optimal adsorbent. For this purpose, we develop a database of adsorbents and their respective parameters of the thermodynamic model.In the project, we initially focus on adsorption heat pumps to develop the integrated design methodology. For an efficient integrated design, a shortcut process model for adsorption heat pumps is developed. During the project, the method is extended to adsorption-based chemical separation processes (e.g., CO2 capture). To allow for an accurate and comprehensive process modeling, we extend the thermodynamic model by models for caloric and transport properties for pure as well as mixed adsorbates. Overall, the integrated design methodology developed in this project will allow finding the optimal combination of adsorbent, adsorbate, and process for adsorbent-based processes from chemical and energy engineering.

• DFG Programme: Research Grants
• International Connection: Switzerland
• Partner Organisation: Schweizerischer Nationalfonds (SNF)
• Cooperation Partner: Professor Dr.-Ing. André Bardow