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

Revealing the Pathways of Catalyst Deactivation by Coke During the Hydrodeoxygenation of Raw Bio-Oil

by Cordero-Lanzac, Palos, Hita, Arandes, Rodriguez-Mirasol, Cordero, Bilbao, Castaño
Appl. Catal. B: Environ. Year: 2018

Abstract

Virtually all processes aiming for fuels and chemicals from biomass entail no less than one step for removing oxygen by hydrodeoxygenation (HDO). The bottleneck of HDO is the formation of deactivating carbonaceous species on the catalyst surface. In this work, we have studied the deactivation pathways of catalysts based on noble metal nanoparticles (Pt-Pd) supported on mildly acid supports during the HDO of raw bio-oil. At conditions of accelerated deactivation, monitoring the evolution with time on stream of hydrocarbon and oxygenated compounds in the reaction medium, the intermediates on the catalyst surface and the nature-location of deactivating species, two parallel deactivation routes have been revealed: the deposition of (i) thermal or pyrolytic lignin from alkylmethoxy phenols, on the catalyst mesopores and favored at low temperature, and; of (ii) aromatic coke from polycyclic aromatic hydrocarbons, starting on the catalyst micropores through condensation reactions and promoted by acidic sites and high temperature. Nevertheless, catalyst deactivation can be controlled within limits at harsh temperature conditions (450 °C) due to the preferential HDO of alkyl(methoxy) phenols into aromatics and the formation-hydrocracking steady state of the aromatic precursors of coke.

Keywords

HPC MKM W2C