First-principles kinetic modeling in heterogeneous catalysis: an industrial perspective on best-practice, gaps and needs

Electronic structure calculations have emerged as a key contributor in modern heterogeneous catalysis research, though their application in chemical reaction engineering remains largely limited to academia. This perspective aims at encouraging the judicious use of first-principles kinetic models in industrial settings based on a critical discussion of present-day best practices, identifying existing gaps, and defining where further progress is needed

Dynamics of a three-phase upflow fixed bed catalytic reactor

A dynamic model of an upflow fixed-bed catalytic reactor is developed to examine numerically transient axial temperature and concentration profiles obtained for the consecutive hydrogenation of 1,5,9-cyclododecateriene on a Pd/Al2O3 catalyst. This non-isothermal heterogeneous model includes the resistances to heat and mass transfer at the gas–liquid and liquid–solid interfaces, as well as the heat exchange through the jacket of the reactor. The predictions of the model are compared to experimental data for various gas and liquid flow rates to describe dynamic events, such as the start-up of the reactor and the effects of sudden changes in the operating conditions on the reactor behaviour and its thermal stability. The predicted transient profiles are in good agreement with the experimental measurements. Still, the dynamic model is not able to correctly predict hot spots and runways experimentally observed at very high hydrogen flow rates

Global Strong Solutions for a Class of Heterogeneous Catalysis Models

We consider a mathematical model for heterogeneous catalysis in a finite three-dimensional pore of cylinder-like geometry, with the lateral walls acting as a catalytic surface. The system under consideration consists of a diffusion-advection system inside the bulk phase and a reaction-diffusion-sorption system modeling the processes on the catalytic wall and the exchange between bulk and surface. We assume Fickian diffusion with constant coefficients, sorption kinetics with linear growth bound and a network of chemical reactions which possesses a certain triangular structure. Our main result gives sufficient conditions for the existence of a unique global strong $L^2$-solution to this model, thereby extending by now classical results on reaction-diffusion systems to the more complicated case of heterogeneous catalysis.Comment: 30 page

Structure Sensitivity in Oxide Catalysis: First-Principles Kinetic Monte Carlo Simulations for CO Oxidation at RuO2_2(111)

We present a density-functional theory based kinetic Monte Carlo study of CO oxidation at the (111) facet of RuO$_2$. We compare the detailed insight into elementary processes, steady-state surface coverages and catalytic activity to equivalent published simulation data for the frequently studied RuO$_2$(110) facet. Qualitative differences are identified in virtually every aspect ranging from binding energetics over lateral interactions to the interplay of elementary processes at the different active sites. Nevertheless, particularly at technologically relevant elevated temperatures, near-ambient pressures and near-stoichiometric feeds both facets exhibit almost identical catalytic activity. These findings challenge the traditional definition of structure sensitivity based on macroscopically observable turnover frequencies and allow to scrutinize the applicability of structure sensitivity classifications developed for metals to oxide catalysis.Comment: 15 pages, 5 figure

Reaction engineering of emerging oxidation processes

A review of the recent developments in emerging multiphase catalytic oxidation processes for the manufacture of various key chemicals, and an overview of reaction engineering principles needed for reactor design and interpretation of performance are presented. The utility of combining a knowledge of the catalytic chemistry through fundamental mechanisms and kinetics with transport effects and hydrodynamics using recent advances in experimental methods is also discussed and reviewed with reference to liquid phase oxidation

Kinetic Intersections as a Source of Information on Rate Coefficients

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Biomass Fast Pyrolysis Reactors: a Review of a few Scientific Challenges and of Related Recommended Research Topics

International audienceThe use of biomass as an alternative energy resource requires its prior processing. Many options are possible. The present paper focuses on thermochemical routes and more specifically on fast pyrolysis carried out for the preparation of so called bio-oils. The optimization and scaling up of fast pyrolysis processes for improving bio oils yields and properties come up against several difficulties. The aim of the paper is to show that some of them are related to the lack of several basic scientific knowledges, more specifically at the level of the high temperature fast pyrolysis reactor. The analysis of these challenges (biomass sample thermal decomposition, biomass-reactor interactions, secondary eactions) suggests the development of several research topics