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

Spectro-kinetics of the methanol to hydrocarbons reaction combining online product analysis with UV–vis and FTIR spectroscopies throughout the space time evolution

by Valecillos, Vicente, Gayubo, Aguayo, Castaño
J. Catal. Year: 2022 DOI: https://doi.org/10.1016/j.jcat.2022.02.021

Abstract

The well-studied methanol to hydrocarbons reaction over a ZSM-5 zeolite catalyst has been used to develop a spectro-kinetic approach to obtain an overall reaction mechanism involving both retained species and gas-phase products. We combined two in situ spectroscopic techniques (ultraviolet–visible and Fourier-transform infrared spectroscopies) with online product analysis to obtain the time- and space time-resolved evolution of the entire reaction media. A ZSM-5 zeolite catalyst was tested in two commercial spectroscopic cells at 400 °C using different space times (different inlet flow rates). Specifically, our work focusses on the effect of the space time (key parameter in any kinetic study) and how to tune other parameters such as partial pressure of methanol to resolve, from the spectroscopic and gas-phase points of view, the mechanisms of reaction and deactivation. Our approach reinforces the previous interpretation of these two combined networks in the selected reaction, thus, proving that the spectro-kinetic approach is a robust methodology to simultaneously build overall reaction and deactivation mechanisms.

Keywords

O2H MKM CRE