Three-phase catalytic reactors

Ramachandran, P. A. and Chaudhari, R. V., Three Phase Catalytic Reactors, Gordon and Breach Science Publishers. 

A reasonable throughput screening equipment consisting of six parallel reactor tubes was constructed. The system operates continuously and can be used for screening of various catalysts, different particle sizes and temperatures. Gas, gas-sohd and gas-solid-liquid applications are possible. The screening equipment is coupled to gas chromatographic-mass spectrometric analysis. The constraction principles, the equipment as well as the application of the equipment is demonstrated with three-phase catalytic systems. 

The three-phase catalytic hydrogenation of an unsaturated ketone using supercritical carbon dioxide as a solvent was studied in order to simulate the performance of a semi-industrial trickle-bed reactor. It is shown that supercritical CO2 strongly increases the reaction rate (Devetta et al., 1999). 

Ramachandran, P.A., Chaudhari, R.V., Analysis and design of three phase catalytic reactors, in Recent advances in the engineering analysis of chemically reacting systems (ed. L.K. Doraiswamy), Wiley Eastern Limited, India (1984)... 

Tortuosity factors less than unity have often been reported for three-phase catalytic reactors where a reactant gas diffuses in a liquid- (or dense) medium. Many examples are available. A... 

In industrial practice, three-phase catalytic reactors are often used, with gases like such as H2, H2O, NH3 or O2 as reactants. The process can be classified on the basis of these gases as hydrogenation, hydration, amination, oxidation, etc [3]. Among these processes, hydrogenation is by far the most important multiphase catalytic reaction. Recently, liquid- -phase methanol synthesis and the Fischer-Tropsch process were commercialized respectively... 

P.A. Ramachandran, and R.V. Chaudari, Three-Phase Catalytic Reactors, New York, Gordon and Breach Sci. Publ., 1983. 

A second consideration is the operating mode continuous, batch, or semi-continuous. An extensive textbook on theory, design and scale-up of multiphase reactors was published by Gianetto and Silveston in 1986 [22], supplementing "Three-phase catalytic... 

P.A.Ramachandran and R.V.chaudhari, Three phase catalytic reactors, Gordon and Breach, New york, 1983... 

Heat and Mass Transfer in Packed Beds, NWakao S Kaguei Three-Phase Catalytic Reactors, P A Ramachandran R V Chaudari Drying Principles, Applications and Design, by Cz Strumillo T Kudra... 

Volume 2 THREE-PHASE CATALYTIC REACTORS by P.A. Ramachandran and R.V. Chaudhari... 

Figure 25 Aspects controlling the performance of a three-phase catalytic reactor, indicating the flexibility of the use of monolithic catalysts.

Liquid-solid mass transfer is typically not limiting due to the small particle size resulting in large particle surface area/volume of reactor, unless the concentration of the particles is very low, and or larger particles are used. In the latter case, intraparticle mass-transfer limitations would also occur. Ramachandran and Chaudhari (Three-Phase Catalytic Reactors, Gordon and Breach, 1983) present several correlations for liquid-solid mass transfer, typically as a Sherwood number versus particle Reynolds and Schmidt numbers, e.g., the correlation of Levins and Glastonbury [Trans. Inst. Chem. Engrs. 50 132 (1972)] ... 

Additional information on hydrodynamics of bubble columns and slurry bubble columns can be obtained from Deckwer (Bubble Column Reactors, Wiley, 1992), Nigam and Schumpe (Three-Phase Sparged Reactors, Gordon and Breach, 1996), Ramachandran and Chaudhari (Three-Phase Catalytic Reactors, Gordon and Breach, 1983), and Gianetto and Silveston (Multiphase Chemical Reactors, Hemisphere, 1986). Computational fluid mechanics approaches have also been recently used to estimate mixing and mass-transfer parameters [e.g., see Gupta et al., Chem. Eng. Sci. 56(3) 1117-1125 (2001)]. 

Correlations for the dynamic liquid holdup have also been developed as function of various dimensionless numbers including the liquid and gas Reynolds number, and the two-phase pressure drop [see, e.g., Ramachandran and Chaudhari, Three-Phase Catalytic Reactors, Gordon and Rreach, 1983 and Hofmann, Hydrodynamics and Hydrodynamic Models of Fixed Bed Pieactors, in Gianetto and Silveston (eds.), Multiphase Chemical Pieactors, Hemisphere 1986],... 

The various volumetric mass-transfer coefficients are defined in a manner similar to that discussed for gas-liquid and fluid-solid mass transfer in previous sections. There are a large number of correlations obtained from different gas-liquid-solid systems. For more details see Shah (Gas-Liquid-Solid Reactor Design, McGraw-Hill, 1979), Ramachandran and Chaudhari (Three-Phase Catalytic Reactors, Gordon and Breach, 1983), and Shah and Sharma [Gas-Liquid-Solid Reactors in Carberry and Varma (eds.), Chemical Reaction and Reactor Engineering, Marcel Dekker, 1987],... 

Mechanically agitated slurry reactors are widely used in three-phase catalytic and noncatalytic reactions. In aerated slurry reactors, the three regimes outlined in Table V prevail. These regimes are schematically illustrated in Fig. 11. The gas flow rate and stirrer speed where the transition from regimes a to b or b to c with a Rushton turbine stirrer occurs can be estimated from the relationships described in Table VI. 

In this type of three-phase catalytic reactor, centrifugal force is employed to vary the hydrodynamics and transport characteristics of the conventional gas-liquid-solid reactor. Interphase transport of momentum and mass in such a reactor is governed by the centrifugal forces. Dudukovic and co-... 

Reactions involving gas, liquid, and solid are often encountered in the chemical process industry. The most common occurrence of this type of reaction is in hydroprocessing operations, in which a variety of reactions between hydrogen, an oil phase, and a catalyst have been examined. Other common three-phase catalytic reactions are oxidation and hydration reactions. Some three-phase reactions, such as coal liquefaction, involve a solid reactant. These and numerous other similar gas-liquid solid reactions, as well as a large number of gas-liquid reactions, are carried out in a vessel or a reactor which contains all three phases simultaneously. The subject of this monograph is the design of such gas-liquid -solid reactors. 

In the last 15 years, the use of monoliths has been extended to include applications for performing multiphase reactions. Particular interest has been focused on the application of monolith reactors in three-phase catalytic reactions, such as hydrogenations, oxidations, and bioreactions. There is also growing interest in the chemical industries to find new applications for monoliths as catalyst support in three-phase catalytic reactions. 

L. L. Crynes, R.L. Cerro, and M.A. Abraham, Monolith froth reactor Development of a novel three-phase catalytic system, AIChE J. 41(2)331 (1995). 

Ramachandran, P, A., and R. V. Chaudhari, Three-phase Catalytic Reactors. New York Gordon and Breach, 1983. 

Hybrid strategy for real time optimization with feasibility driven for a large scale three-phase catalytic slurry reactor... 

Hybrid Strategy for Real Time Optimization with Feasibility Driven for a Large Scale Three-Phase Catalytic Slurry Reactor... 

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