Reactor heterogeneous

Designed to obtain such fundamental data as chemical rates free of mass transfer resistances or other complications. Some of the heterogeneous reactors of Fig. 23-29, for instance, employ known interfacial areas, thus avoiding one uncertainty. 

Flow Reactors Fast reactions and those in the gas phase are generally done in tubular flow reaclors, just as they are often done on the commercial scale. Some heterogeneous reactors are shown in Fig. 23-29 the item in Fig. 23-29g is suited to liquid/liquid as well as gas/liquid. Stirred tanks, bubble and packed towers, and other commercial types are also used. The operadon of such units can sometimes be predicted from independent data of chemical and mass transfer rates, correlations of interfacial areas, droplet sizes, and other data. 

Chapter 10 begins a more detailed treatment of heterogeneous reactors. This chapter continues the use of pseudohomogeneous models for steady-state, packed-bed reactors, but derives expressions for the reaction rate that reflect the underlying kinetics of surface-catalyzed reactions. The kinetic models are site-competition models that apply to a variety of catalytic systems, including the enzymatic reactions treated in Chapter 12. Here in Chapter 10, the example system is a solid-catalyzed gas reaction that is typical of the traditional chemical industry. A few important examples are listed here ... 

In this chapter, we first cite examples of catalyzed two-phase reactions. We then consider types of reactors from the point of view of modes of operation and general design considerations. Following introduction of general aspects of reactor models, we focus on the simplest of these for pseudohomogeneous and heterogeneous reactor models, and conclude with a brief discussion of one-dimensional and two-dimensional models. 

Costs of energy and raw materials for a reactor as a function of yield and selectivity [Adapted and modified from R LeGoff, The Energetic and Economic Optimization of Heterogeneous Reactors, Chem Eng Sci 35 2089 (1980)]. 

Heterogeneous reaction, 25 728-729 Heterogeneous reactors, 27 568 Heterogeneous stereospecific polymerization, 20 410-411 Heterogeneous vapor-phase fluorination, 22 863... 

The additional problems which arise in heterogeneous reactors, where hot spots may cause permanent damage to the catalyst by sintering, will be examined in Chap. 4. 

As observed above, in order to quench HMF produced in situ, dealuminated H-form mordenites were investigated in a water/MIBK mixture (1/5) [84, 85]. In this case, a maximum conversion of fructose of 54% (along with 90% selectivity to HMF) was obtained over an H-mordenite with a Si/Al ratio of 11. HMF was continuously extracted with a flow of MIBK circulating in a countercurrent way through a catalytic heterogeneous reactor containing the H-mordenite zeolite. On the continuation of their efforts, the same authors then set up a new continuous solid-liquid-liquid reactor where the zeolite was now in suspension in the aqueous phase while the HMF was continuously extracted with MIBK in a countercurrent way to the aqueous phase and catalyst feed. 

A further classification of homogeneous and heterogeneous reactors is based on the nature of the involved reacting phases—... 

Gas Separation by Adsorption Processes Ralph T. Yang Heterogeneous Reactor Design Hong H. Lee Molecular Thermodynamics of Nonideal Fluids Lloyd L. Lee Phase Equilibria in Chemical Engineering Stanley M. Walas Transport Processes in Chemically Reacting Flow Systems Darnel E. Rosner... 

Combination of any two or more of the above processes (example heterogeneous reactors). 

The general forms of rate expressions in heterogeneous systems can have concentration or partial pressure dependences in both numerator and denominator along with various exponents. In heterogeneous reactors, it is not unusual to derive kinetic expressions that are more complicated than just a power-law expression. This, of course, has implications on how the reactor is controlled and the potential for runaway in exothermic systems. In some cases, where kinetics are very fast relative to mass transfer rates, the reactor behavior is governed by mass transfer and the variables that affect it. 

Heterogeneous reactors contain more than one phase. Several heterogeneous reactor types are available due to various combinations of phases. 

The bubble column is a typical gas-liquid heterogeneous reactor with the design also applicable to liquid-liquid systems. The bubbles rise through the liquid in plug flow. The liquid is well mixed by the bubbling gas and seldom follows plug flow assumptions. 

A packed bed reactor is a continuous heterogeneous reactor. The gas or liquid phase obeys plug flow theory. The solids are considered batch, with even long-life catalyst beds losing activity over time. 

All of these roasting furnace reactors operate continuously. They are noncatalytic gas-solid heterogeneous reactors. The multiple hearth has characteristics similar to plug flow operation. The flash roaster approaches CSTR, and the third option is a fluidized bed configuration. 

The rotary kiln is a continuous countercurrent heterogeneous reactor. Solids traveling down the kiln are in plug flow, as are the gases passing upward. 

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