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 Modelling of Hydrotreating for Enhanced Upgrading of Light Cycle Oil (LCO)

by Palos, Gutierrez, Hita, Castaño, Thybaut, Arandes, Bilbao
Ind. Eng. Chem. Res. Year: 2019

Abstract

The hydrotreating of light cycle oil (LCO) into high-quality fuels has been investigated experimentally and kinetically, developing a model that accounts for the main and simultaneous reaction pathways: hydrodesulfurization (HDS), hydrodearomatization (HDA), and hydrocracking (HC). The experiments have been carried out in a fixed-bed reactor, NiMo/SiO2–Al2O3 commercial catalyst, 320–400 °C; 80 bar; space time, 0–0.5 gcat h gLCO–1; and H2/LCO volumetric ratio of 1000 Ncm3 cm–3. The proposed kinetic model contains multiple lumps, species, and pathways, leading to the faithful prediction of hydrotreatment products from different viewpoints. The computed kinetic parameters have allowed for simulating the process and seeking the optimal operating conditions. This way, the maximum values obtained for the conversions of HDS, HDA, and HC have been of 90%, 20%, and 65%, respectively; whereas a good compromise between the different hydrotreating goals has been obtained in the 385–400 °C range for a space time of 0.2 gcat h gLCO–1. Finally, the obtained optimal operating conditions have been compared with those optimized in the literature.

Keywords

HPC W2C MKM