Catalyst effectiveness factor distributions in isothermal packed bed reactors

Schulenburg, D.A. Graf Von Der; Johns, Michael L.

doi:10.1016/j.ces.2011.04.001

Cited by 15 publications

(3 citation statements)

References 24 publications

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“…121,180,181 After morphological analysis, the reconstructions -which need to be sufficiently large to cover a representative volume of the material reflecting its bulk properties 173 -can be used as models in direct simulations of diffusion, flow, and mass transport on the pore scale. 209,224,225 The scope of these simulations can be well extended to include adsorption [226][227][228] and reaction [229][230][231][232] at the solid surface, or to introduce intraparticle (intraskeleton) porosity and transport properties. 27 As a result of such a level of simulations with unusual spatio-temporal and realistic structural details, key information is obtained, e.g.…”

Section: Conclusion and Perspectivementioning

confidence: 99%

Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors

2016

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The targeted optimization of the functional properties of porous materials includes the understanding of their transport properties and thus requires knowledge about the relationship between material synthesis, resulting in three-dimensional material morphology, and relevant transport properties. In this Perspective, we present our views and results on the characterization of microscopic disorder in functional porous materials, which are widely used today as fixed beds in adsorption, separation, and catalysis. This allows us to identify structural parameters that impact their mass transport properties and eventually their overall performance in technological operations. We address this complex topic at the following levels: (i) computer-generation of disordered packings allows the systematic investigation of the bed porosity (packing density) and degree of packing heterogeneity. These studies are complemented by the physical reconstruction of real packed and monolithic beds, which resolves the salient features of the packing process and monolith synthesis that are under the control of the experimentalist. (ii) Once reconstructed packed-bed and monolith morphologies are available, they are analysed by statistical methods to derive structural descriptors for their mass transport properties. Spatial tessellation schemes and chord length distributions are shown to be suitable for that purpose. They lead us to sensitive correlations of the degree of pore-environment heterogeneity and packing-scale disorder with the dynamics of (random) diffusion and (flow-field dependent) hydrodynamic dispersion, respectively. (iii) Direct or pore-scale numerical simulations are implemented on a highperformance computing platform to quantify the relevant transport properties of the materials. This complementary approach highlights the morphological descriptors of mass transport efficiency. They are validated by the simulations and in the future could direct the rational design of materials from their synthesis to targeted applications based on physical reconstruction.

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Section: Conclusion and Perspectivementioning

confidence: 99%

Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors

2016

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“…In order to characterize the pore-scale structures of coal, two kinds of geometrical models, experiment-based and computer-based methods, are generally used. For the experiment-based method, real geometric images of coal are directly obtained by scanning techniques such as computed tomography [15][16][17][18], magnetic resonance imaging [19,20], scanning electron microscopy [21] and synchrotron microscopy [22]. The computer-based method generates and characterizes a porous morphology according to a mathematical function.…”

Section: Introductionmentioning

confidence: 99%

A numerical study on oxygen adsorption in porous media of coal rock based on fractal geometry

Liang

et al. 2020

R. Soc. open sci.

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In order to explore the factors affecting coal spontaneous combustion, the fractal characteristics of coal samples are tested, and a pore-scale model for oxygen adsorption in coal porous media is developed based on self-similar fractal model. The liquid nitrogen adsorption experiments show that the coal samples indicate evident fractal scaling laws at both low-pressure and high-pressure sections, and the fractal dimensions, respectively, represent surface morphology and pore structure of coal rock. The pore-scale model has been validated by comparing with available experimental data and numerical simulation. The present numerical results indicate that the oxygen adsorption depends on both the pore structures and temperature of coal rock. The oxygen adsorption increases with increased porosity, fractal dimension and ratio of minimum to maximum pore sizes. The edge effect can be clearly seen near the cavity/pore, where the oxygen concentration is low. The correlation between the oxygen adsorption and temperature is found to obey Langmuir adsorption theory, and a new formula for oxygen adsorption and porosity is proposed. This study may help understanding the mechanisms of oxygen adsorption and accordingly provide guidelines to lower the risk of spontaneous combustion of coal.

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“…This reduction can be determined via the catalyst effectiveness factor g, with 0 , g ¡ 1. 39 For g = 0 the diffusion limitation inside the porous carrier bead is large and therefore the catalytic efficiency is provided mainly by the outside area of the bead, whereas for g = 1 the pore diffusion can be neglected. The effectiveness factor is calculated via (eqn (2)) g = (1/tanh(3W) 2 1/3W) 40 (2…”

Section: Laccase Immobilization and Activity Testsmentioning

confidence: 99%

Porous ceramic monoliths assembled from microbeads with high specific surface area for effective biocatalysis

et al. 2013

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Catalyst effectiveness factor distributions in isothermal packed bed reactors

Cited by 15 publications

References 24 publications

Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors

Characterization of microscopic disorder in reconstructed porous materials and assessment of mass transport-relevant structural descriptors

A numerical study on oxygen adsorption in porous media of coal rock based on fractal geometry

Porous ceramic monoliths assembled from microbeads with high specific surface area for effective biocatalysis

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