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

Intrinsic microkinetic effects of spray-drying and SiC co-support on Mn–Na₂WO₄/SiO₂ catalysts used in oxidative coupling of methane

by Lezcano, Kulkarni, Velisoju, Realpe, Castaño
React. Chem. Eng. Year: 2025 DOI: https://doi.org/10.1039/D4RE00403E

Abstract

This paper presents a microkinetic model to evaluate the effects of a silicon carbide (SiC) co-support and the shaping method on Mn–Na2WO4/SiO2 catalysts used for the oxidative coupling of methane. The model considers mass transfer, catalytic, and gas-phase kinetics, and it is trained with experimental values (product composition) of three Mn–Na2WO4 catalysts for calculating the kinetic parameters using catalytic descriptors while maintaining thermodynamic consistency. The catalysts were an SiO2-supported catalyst prepared through impregnation and two SiO2–SiC-supported catalysts (with βSiC and α + βSiC) prepared via spray-drying. Our analysis shows how the type of SiC and preparation method affect the textural properties and result in distinct CH3˙ radical oxidation, HO2˙ quenching, C2H4 oxidation, and COX transformation pathways, eventually leading to CH4 conversion and C2 selectivity. Our approach facilitates the assessment of the effects of the promoter and support on individual and global reaction networks.

Keywords

MKM HCE CHA