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

Designing sulfide catalysts for H2S dissociation to H2 based on reaction descriptors and microkinetics

by Almofleh, Alaithan, Velisoju, Mukhambetov, Lezcano, Aljama, Mohamed, Castaño
Appl. Catal. B: Environ. Year: 2025 DOI: https://doi.org/10.1016/j.apcatb.2024.124605

Abstract

Molybdenum disulfide (MoS2) is a promising catalyst for the challenging transformation of hydrogen sulfide (H2S) into sulfur and hydrogen (H2). However, a detailed understanding of its structure-function correlation still needs to be provided. We used density functional theory calculations to extract relevant reaction indexes (binding energies and free energy barriers) over different MoS2surfaces. We used these indexes as inspiration in developing new catalysts and a microkinetic model to compare the results, extracting insights into the reaction mechanisms and surface coverages. The turnover frequencies obtained experimentally and through microkinetic modeling are analogous, validating our approach. The findings pave the way for developing more efficient H2S decomposition catalysts and establish a descriptor-based design for other metal sulfide catalysts.

Keywords

S2H MKM CRE