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

Dual Coke Deactivation Pathways during the Catalytic Cracking of Raw Bio-Oil and Vacuum Gasoil in FCC Conditions

by Ibarra, Veloso, Bilbao, Arandes, Castaño
Appl. Catal. B: Environ. Year: 2016

Extra Information

Open Access.

Abstract

Coke deposition pathways have been studied during the fluid catalytic cracking of bio-oil, vacuum gasoil (VGO) and a blend of the previous two (80 wt% VGO and 20 wt% bio-oil), under realistic riser conditions of the fluid catalytic cracking (FCC) unit, using a commercial catalyst at 500 °C and contact times of 1.5–10 s. Amount and composition of soluble and insoluble coke in dichloromethane have been analyzed using a set of techniques (TPO, FTIR, 13C NMR, XPS, Raman, GC–MS and MALDI-TOF MS, among others). The relationship of coke deposition with its composition and the reaction medium has allowed us to set two pathways of coke formation: (i) heavy hydrocarbon pathway tend to form ordered polycondensed aromatic nanostructures; whereas (ii) oxygenate pathway tend to form a lighter fraction of coke containing oxygen, less ordered and more aliphatic coke. A synergy between the two pathways have been verified due to the lower coke deposition of the blend compared to the individual components, and this has been explained in terms of (i) attenuation of the heavy hydrocarbon pathway caused by the steam contained or originated from the bio-oil, and (ii) the hydride transfer from hydrocarbons to the precursors of the oxygenate pathway.

Keywords

O2H FCC W2C MKM