Multiscale kinetic modeling in catalysis ⇒ from microkinetics to computational fluid dynamics and process simulations

Problem statement

We envision multiscale modeling as critical enablers of reaction understanding, catalyst and reactor design, scale-up, and process optimization. The framework includes predicting the molecular reaction mechanism at the molecular level to the process optimization stage. As catalytic processes occur at the multiscale, we address these issues individually and collectively.

At the microkinetic level, our models resolve the rates of the individual elementary steps, rate-determining step (RDS), adsorption, and desorption mechanisms. We use quantum chemical calculations (density functional theory, DFT) to support our assumed kinetic pathways, original parameter estimations, and adsorption-desorption energies.

We incorporate thermodynamic constraints into our models. Once developed, the microkinetic model could guide the catalyst and reactor design. We also have experience developing Langmuir-Hinshelwood and Eley-Rideal types of kinetic models.

At the macrokineitc level, we develop lump-based and empirical models which, in some cases, are very robust and, together with other models, can be used to extract information such as mechanism change, optimize conditions, or for reactor pre-design.

We couple hydrodynamics, heat transfer, and reaction kinetics at the reactor level in computational fluid dynamic (CFD) simulations. Together with optimization algorithms, we aim to improve operating scenarios, develop innovative reactor prototypes, and predict process behaviors at the industrial scale.

Goals

  • Microkinetics I ⇒ key thermodynamic relationships
  • Microkinetics II ⇒ fitting, training, and optimization
  • Microkinetics III ⇒ ab initio kinetic modeling
  • Macrokinetics ⇒ complex reaction networks and population balances
  • CPFD ⇒ reactor modeling and scale-up
  • CFD ⇒ reactor modeling and optimization
  • CFD II ⇒ modeling operando reactors
  • Process system engineering ⇒ gPROMS

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Related Publications

Coupling catalytic bed fluidization with impeller rotation for improved hydrodynamic characterization of Berty reactors

by Cui, Kulkarni, Abu-Naaj, Wagner, Berger-Karin, Weber, Nagy, Castaño
React. Chem. Eng. Year: 2024 DOI: https://doi.org/10.1039/D4RE00074A

Abstract

We developed an integrated modeling framework to capture the gas–solid mixing patterns in internal circulating Berty reactors operating under batch fluidized mode. Our framework combines computational fluid dynamics for the gas phase with impeller rotation and computational particle fluid dynamics for solid fluidization in the catalyst basket. We proposed several key hydrodynamic indicators for the Berty-type reactor and compared the prediction results from the integrated simulation strategy with previous settings without considering the actual bed fluidization. Deviations in bed velocity, gas–solid contact time, and recirculation rate underscored the necessity of employing accurate hydrodynamic characteristics when designing Berty-type reactors. The consistent impeller relationships under various fluidization conditions suggested that the hydrodynamics in internal circulating Berty reactors are predominantly influenced by impeller rotation, irrespective of bed status. In this context, we introduced a fluidized bed expansion correlation to the impeller relationship, offering a more reliable hydrodynamic explanation for the Berty fluidized bed reactor in batch mode. This can also serve as a design foundation for internal recycling reactors.

Keywords

FCC C2C CRE MKM