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

Kinetic Model for the Conversion of Chloromethane into Hydrocarbons over a HZSM-5 Zeolite Catalyst

by Gamero, Valle, Gayubo, Castaño, Aguayo, Bilbao
Ind. Eng. Chem. Res. Year: 2018

Abstract

The conversion of chloromethane into hydrocarbons over a HZSM-5 zeolite based catalyst is investigated with the aim of establishing a kinetic model suitable for simulating this process for indirect valorization of the methane contained in shale gas. The experimental data were obtained in an isothermal fixed bed reactor under a wide range of operating conditions: temperature, 300–450 °C; space-time, 1–12 gcatalyst h/molCH2; chloromethane partial pressure, 0.375–1.5 atm; and time on stream, up to 255 min. The reaction scheme is composed of eight components and lumps (chloromethane, C2–C4 olefins, C2–C4 paraffins, C5–C10 aliphatics, aromatics BTX, methane, hydrochloric acid, and chlorinated hydrocarbons), which are involved in ten single reactions. The catalyst deactivation by coke deposition has been quantified by an equation, which is dependent on the concentration of chloromethane in the reaction medium. The kinetic model is suitable for predicting accurately the effect that reaction conditions have on products distribution and their evolution with time on stream.

Keywords

MKM O2H