Simulation of a Three-Way Catalyst Using Transient Single and Multi-Channel Models

Aslanjan, Jana; Klauer, Christian; Perlman, Cathleen; Günther, Vivien; Mauß, Fabian

doi:10.4271/2017-01-0966

Cited by 10 publications

(4 citation statements)

References 11 publications

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“…The monolith 1D catalyst model used for the simulations in this work was presented in detail first in [30]. The model was then extended by a multi-channel model in [31] and further applied and described in [32,33]. However, for the sake of readability, this article presents detailed information about the model in this section, with emphasis on the modeling of conservation and flow equations.…”

Section: Model Descriptionmentioning

confidence: 99%

Reaction Mechanism Development for Methane Steam Reforming on a Ni/Al2O3 Catalyst

et al. 2023

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In this work, a reliable kinetic reaction mechanism was revised to accurately reproduce the detailed reaction paths of steam reforming of methane over a Ni/Al2O3 catalyst. A steady-state fixed-bed reactor experiment and a 1D reactor catalyst model were utilized for this task. The distinctive feature of this experiment is the possibility to measure the axially resolved temperature profile of the catalyst bed, which makes the reaction kinetics inside the reactor visible. This allows for understanding the actual influence of the reaction kinetics on the system; while pure gas concentration measurements at the catalytic reactor outlet show near-equilibrium conditions, the inhere presented temperature profile shows that it is insufficient to base a reaction mechanism development on close equilibrium data. The new experimental data allow for achieving much higher quality in the modeling efforts. Additionally, by carefully controlling the available active surface via dilution in the experiment, it was possible to slow down the catalyst conversion rate, which helped during the adjustment of the reaction kinetics. To assess the accuracy of the revised mechanism, a monolith experiment from the literature was simulated. The results show that the fitted reaction mechanism was able to accurately predict the experimental outcomes for various inlet mass flows, temperatures, and steam-to-carbon ratios.

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Section: Model Descriptionmentioning

confidence: 99%

Reaction Mechanism Development for Methane Steam Reforming on a Ni/Al2O3 Catalyst

et al. 2023

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“…The model is based on the single-channel 1D catalyst model and is applicable to the simulation of all standard after-treatment catalytic processes of combustion exhaust gas. The model has been successfully used in past studies [34][35][36]. A detailed investigation of the steam reforming of methane over nickel in a generalised sense has been considered in [32].…”

Section: Model Descriptionmentioning

confidence: 99%

Kinetically consistent detailed surface reaction mechanism for steam reforming of methane over nickel catalyst

Rakhi

Shrestha

Günther³

et al. 2022

Reac Kinet Mech Cat

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A one-dimensional model, LOGEcat is used to develop a detailed surface reaction mechanism for modeling the steam reforming of methane over a nickel-based catalyst. The focus of the paper is to develop a kinetically consistent surface reaction mechanism. The two terms, kinetically and thermodynamically consistent mechanisms, will be used frequently in this article. Note that when the mechanism is thermodynamically consistent then the thermodynamic data or the thermochemistry of the species is not used and all the reactions in the mechanism are forward reactions (no backward reactions included) which need the Arrhenius parameters (pre-exponential factor, $$A_{r}$$ A r ; activation energy, $$E_{r}$$ E r ; temperature exponent, $$\beta _r$$ β r ) explicitly for each reaction. The kinetically consistent mechanisms need Arrhenius parameters only for the forward reactions and does not need these parameters for backward reactions making the backward reactions independent of the kinetics. The rate for the backward reactions is calculated with the help of thermochemistry of the intermediate species involved in the reaction mechanism. Since the thermochemistry of the intermediate species are not easily available, this makes such studies much more complex. The original multi-step reaction mechanism consists of 42 reactions which are thermodynamically consistent. In this study we have modified this reaction mechanism from literature and used only 21 (reversible) direct reactions. This aspect is important because by using only 21 reactions, we use the thermochemistry of the species to achieve thermodynamic equilibrium instead of providing the Arrhenius parameters for forward and backward reactions. We use the same $$A_{r}$$ A r , $$E_{r}$$ E r and $$\beta _r$$ β r values as used in the reference paper for the considered 21 reactions which are in equilibrium. However, the value of $$A_{r}$$ A r , $$E_{r}$$ E r and $$\beta _r$$ β r for the inverse/backward reactions are not given in the mechanism and the reverse rates are calculated by using the equilibrium and forward rate. Therefore, a sensitivity analysis on thermochemistry of the species is performed for a better agreement with the literature data. The method is presented for ensuring kinetic consistency and bringing thermochemistry of species in play while developing a surface reaction mechanism. The applicability of the mechanism is tested for two different simulation set-ups available in literature considering various reactor conditions in terms of parameters given as temperature and steam-to-carbon (S/C) ratio. Several chemical reaction terms, such as, selectivity, conversion and $$\mathrm {H_2}/{\text{CO}}$$ H 2 / CO ratio are shown for different parameters in comparison with the available reference data. The detailed mechanism developed in this study is able to accurately express the steam reforming of methane over the nickel catalyst for complete ranges of temperature for both the set-ups and within acceptable limit for S/C ratio considered for the analysis.

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“…The chemistry integration is embedded in the operator splitting loop to solve the joint PDF (eq ) in the following sequence Inflow of mass. Mixing of the stochastic particles’ gas phase. Heterogeneous reactions and transport. Gas-phase chemistry integration and radiation. Stochastic heat transfer. Outflow of mass. Note that only the gas phase of the stochastic particles are mixed, while solids and their surrounding bulk gases remain in their primary particle. The gas-phase chemistry is solved as described in previous studies, , and the heterogeneous reactions are discussed elsewhere. , In the operator splitting loop, two processes are based on random seed generation: the selection of stochastic particles for mixing and the heat transfer with the wall. Both contribute to keeping the inhomogeneity of an incomplete mixed inflow but also increase inhomogeneity by generating an inhomogeneous temperature field that leads to different progress of reactions in each particle, which again gets mixed.…”

Section: Fuel Bed Modelmentioning

confidence: 99%

“…The gas-phase chemistry is solved as described in previous studies, 53,61 and the heterogeneous reactions are discussed elsewhere. 53,62 In the operator splitting loop, two processes are based on random seed generation: the selection of stochastic particles for mixing and the heat transfer with the wall. Both contribute to keeping the inhomogeneity of an incomplete mixed inflow but also increase inhomogeneity by generating an inhomogeneous temperature field that leads to different progress of reactions in each particle, which again gets mixed.…”

Section: ■ Introductionmentioning

confidence: 99%

Stochastic Reactor-Based Fuel Bed Model for Grate Furnaces

Netzer

Seidel

et al. 2020

Energy Fuels

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Biomass devolatilization and incineration in grate-fired plants are characterized by heterogeneous fuel mixtures, often incompletely mixed, dynamical processes in the fuel bed and on the particle scale, as well as heterogeneous and homogeneous chemistry. This makes modeling using detailed kinetics favorable but computationally expensive. Therefore, a computationally efficient model based on zero-dimensional stochastic reactors and reduced chemistry schemes, consisting of 83 gas-phase species and 18 species for surface reactions, is developed. Each reactor is enabled to account for the three phases: the solid phase, pore gas surrounding the solid, and the bulk gas. The stochastic reactors are connected to build a reactor network that represents the fuel bed in grate-fired furnaces. The use of stochastic reactors allows us to account for incompletely mixed fuel feeds, distributions of local temperature and local equivalence ratio within each reactor and the fuel bed. This allows us to predict the released gases and emission precursors more accurately than if a homogeneous reactor network approach was employed. The model approach is demonstrated by predicting pyrolysis conditions and two fuel beds of grate-fired plants from the literature. The developed approach can predict global operating parameters, such as the fuel bed length, species release to the freeboard, and species distributions within the fuel bed to a high degree of accuracy when compared to experiments.

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Simulation of a Three-Way Catalyst Using Transient Single and Multi-Channel Models

Cited by 10 publications

References 11 publications

Reaction Mechanism Development for Methane Steam Reforming on a Ni/Al2O3 Catalyst

Reaction Mechanism Development for Methane Steam Reforming on a Ni/Al2O3 Catalyst

Kinetically consistent detailed surface reaction mechanism for steam reforming of methane over nickel catalyst

Stochastic Reactor-Based Fuel Bed Model for Grate Furnaces

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