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

Hydrodynamic Characteristics of an Internal Recycle Berty Catalytic Reactor in Batch/Continuous or Packed/Fluidized Bed Modes

by Cui, Kulkarni, Wagner, Berger-Karin, Nagy, Castaño
ACS Eng. Au Year: 2022 DOI: https://doi.org/10.1021/acsengineeringau.1c00026

Abstract

Berty-type internal recycle reactors offer great opportunities for screening catalysts and reproducing catalytic reacting conditions in multiple processes, thus approaching industrial reactions while amplifying kinetic information. However, the rational design of these reactors requires a deeper understanding of their governing hydrodynamics and equations so that they can be better utilized in batch or continuous mode or as packed or fluidized beds. In this work, by adopting a slice model to represent a three-dimensional symmetric geometry with porous zone settings for catalyst beds, coupled with a species transport model, multiple reference frame, and SST k–ω turbulence model, we developed a computational fluid dynamic simulation strategy of a commercial Berty reactor manufactured by Integrated Lab Solutions (ILS). We conducted experiments to validate the proposed modeling approach under continuous packed bed operations, through which the hydrodynamic behaviors with packed/fluidized beds under the batch mode were also investigated by studying the influences of the transient injection, bed porosities, and rotation rates. As a result, we reported a set of equations to assess the bed velocity and contact time under different porosities, which simplified the performance improvements while replacing the need to perform complex simulations or conduct costly experiments. On the grounds of these hydrodynamic simulations and under various operating conditions, we discussed the pertinence of these instruments for intrinsic kinetic measurements in the batch/continuous or packed/fluidized bed operational modes.

Keywords

C2C FCC MKM CRE