Catalyst effectiveness factor and contacting efficiency in trickle-bed reactors
TL;DR: In this article, the Thiele modulus, incomplete external wetting (B), and fractional pore fill-up (C) were derived to predict catalyst effectiveness.
Abstract: Catalyst effectiveness factor in trickle bed reactors, (e.g., for hydrocarbon hydrodesulfurization) is a function of the Thiele modulus (A), incomplete external wetting (B), and fractional pore fill-up (C). An approximate formula is derived, which accounts for all three variables. This indicates that the evaluation of contacting efficiencies by applying reactor performance equations to reaction studies is prone to numerous errors. To predict catalyst effectiveness factors, some independent means of evaluating B and C have to be used. In general, existing correlations for B are unsatisfactory, and correlations for C are nonexistent. Fractional pore fill-up will depend on catalyst pore structure and physical properties (particularly surface tensions) of the gas-liquid-solid system involved. Failure to recognize that either B or C, depending on the range of A, are the primary variables affecting catalyst effectiveness in trickle bed reactors may explain the difficulties previously encountered in interpreting trickle bed data. Table, graph, and 19 references.
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TL;DR: In this article, a review of relevant experimental observations and modeling of high-pressure trickle-bed reactors, based on recent studies, is presented, and the effects of high pressure operation, which is of industrial relevance, on physicochemical and fluid dynamic parameters are discussed.
Abstract: A concise review of relevant experimental observations and modeling of high-pressure trickle-bed reactors, based on recent studies, is presented. The following topics are considered: flow regime transitions, pressure drop, liquid holdup, gas−liquid interfacial area and mass-transfer coefficient, catalyst wetting efficiency, catalyst dilution with inert fines, and evaluation of trickle-bed models for liquid-limited and gas-limited reactions. The effects of high-pressure operation, which is of industrial relevance, on the physicochemical and fluid dynamic parameters are discussed. Empirical and theoretical models developed to account for the effect of high pressure on the various parameters and phenomena pertinent to the topics discussed are briefly described.
343 citations
TL;DR: In this paper, a phenomenological analysis has been developed to relate the wetting efficiency with operating conditions such as reactor pressure, gas and liquid flow rate, which can be expressed by the following correlation: ƞ CE = 1.104 REL 1/3 1 + [( ΔP Z )/p L g] Ga L 1/9
157 citations
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29 Jan 2013
TL;DR: In this article, the authors present a model for step-growth polymerization based on process and reaction models and reactivity and copolymer composition. But they do not specify specific processes.
Abstract: Modeling of Processes and Reactors for Upgrading of Heavy ... Processes and Reactor Modeling for Step‐Growth Polymerization. 2.1. Types of Reactors and Reactor Modeling. 2.2. Specific Processes. 3. Processes and Reactor Modeling for Chain‐Growth Polymerization. 3.1. Material Balance Equations for Batch, Semi‐Batch, and Continuous Reactors. 3.1.1. Rates of Reaction and Copolymer Composition. 3.1.2.
98 citations
TL;DR: In this paper, a dynamic heterogeneous one-dimensional model of trickle-bed reactors used for catalytic hydrotreating of oil fractions is presented, which considers the main reactions in the hydroreating process.
Abstract: This paper describes a dynamic heterogeneous one-dimensional model of trickle-bed reactors used for catalytic hydrotreating of oil fractions. The model considers the main reactions in the hydrotreating process of oil fractions: hydrodesulfurization, hydrodenitrogenation, and hydrodearomatization. The dynamic model was first validated using experimental data obtained in an isothermal pilot reactor during hydrotreating of vacuum gas oil over a commercial NiMo catalyst. Then, the model was applied to predict the dynamic behavior of a commercial hydrotreating reactor. Changes in concentration, partial pressure, and temperature profiles are obtained and discussed as a function of reactor axial position and time. The simulations obtained with the proposed dynamic model showed good agreement with experimental data.
70 citations
TL;DR: In this article, the authors examined the effect of different particle shapes (sphere, pellet, cylinder, 2-lobe, 3-lobular, and 4-lobal) on the characteristics and behavior of a small HDS reaction.
69 citations