Homogeneous isothermal reactors

This work is centred around the study of the response to periodic forcing of systems that, when autonomous, had a stable limit cycle surrounding an unstable steady state in their phase plane. For the sake of simplicity—and since many of the fundamental phenomena are the same—we studied two-dimensional systems. We chose two examples of isothermal reactor models the first is an autocatalytic homogeneous Brusselator (Glansdorff and Prigog-ine, 1971) ... 

For a steady state, isothermal, homogeneous tubular reactor consider a simple reaction... 

Using the above dimensionless parameters and variables, Eqs. (188)—(198) are written in dimensionless form and spatially averaged over transverse dimensions to obtain the low-dimensional model for non-isothermal homogeneous tubular reactors, which is given to order p by Eqs. (130) (134) with r((c)) being replaced by r((c), (0f and... 

The low-dimensional model for a non-isothermal homogeneous tank reactor with premixed feed is given by... 

In a homogeneous isothermal flow reactor, the rate of change of the species concentrations at a constant volume can simply be represented as... 

Chitra, S. P.. and Govind. R. Synthesis of Optimal Serial Reactor Structures for Homogeneous Reactions. Part I Isothermal Reactors." AlChE J. 31, 177 (1985a). 

In each case of Section 4.3 the reactor models obtained on the basis of the mixing models were left in general form, with specific results for concentration or conversion versus reactor size depending on the type of rate law to be used. In the following we shall derive a number of expressions for particular rate laws which relate conversion, reactor size, and residence time for the particular case of homogeneous, isothermal ideal reactors. 

Chitra, S.P., Govind, R., 1985. Synthesis of optimal serial reactor structures for homogeneous reactions. Part I Isothermal reactors. AIChEJ. 31, 177-184. 

Rate of Homogeneous Reactions in Ideal Isothermal Reactors... 

Model 3 - Pseudo-homogeneous non-isothermal reactor with reaction rate correction... 

As mentioned in the previous chapter, chemical reactors are broadly classified as homogeneous (single phase) reactors and heterogeneous (multiphase) reactors. This chapter outlines various methods for design of homogeneous reactors. Design of ideal, non-ideal and non-isothermal reactors are discussed in detail. 

Although the above simple illustration of the concept for a homogeneous isothermal lumped system is applicable to other more complicated systems, the situation for catalytic reactors is much more involved because of the complexity of the intrinsic kinetics as well as the complex interaction among reactions, heat release (or absorption), and mass and heat diffusion inside the reactor. For example, many catalytic and biocatalytic reactions show nonmonotonic dependence of the rate of reaction on reactant concentrations. For example, the hydrogenation of benzene to cyclohexane over different types of nickel catalyst has an intrinsic rate of reaction of the form... 

Problem 10-6 (Level 2) A homogeneous, liquid-phase reaction A products takes place in a tubular, isothermal reactor packed with spheres of uniform diameter dp. The reactor obeys the Dispersion model. The fractional conversion of A in the reactor effluent is 99%. At these conditions, the Dispersion number is 0.0625. 

Physical Methods that have been Used to Monitor Reaction Kinetics. In this section some physical property measurements of general utility are discussed. One of the oldest and most useful techniques used in kinetics studies involves the measurement of the total pressure in an isothermal constant volume reactor. This technique is primarily used to follow the course of homogeneous gas phase reactions that involve a change in the total number of gaseous molecules present in the reaction vessel (e.g., the hydrogenation of propylene). 

Vocabulary of Terms Used in Reactor Design. There are several terms that will be used extensively throughout the remainder of this text that deserve definition or comment. The concepts involved include steady-state and transient operation, heterogeneous and homogeneous reaction systems, adiabatic and isothermal operation, mean residence time, contacting and holding time, and space time and space velocity. Each of these concepts will be discussed in turn. 

The reactor model adopted for describing the lab-scale experimental setup is an isothermal homogeneous plug-flow model. It is composed of 2NP + 2 ordinary differential equations of the type of Equation 16.11 with the initial condition of Equation 16.12, NP + 3 algebraic equations of the type of Equation 16.13, and the catalytic sites balance (Equation 16.14) ... 

As discussed above, the level of sensitivity of most gas-phase oxidation catalysts is high with regard to the reaction temperature. Therefore, any Stage II-screening tool should operate under isothermal conditions for all active materials, and it is a given prerequisite that thermal equilibrium of the reactor and a homogeneous temperature distribution are essential. 

Stoichacmetry and reaction equilibria. Homogeneous reactions kinetics. Mole balances batch, continuous-shn-ed tank and plug flow reactors. Collection and analysis of rate data. Catalytic reaction kinetics and isothermal catalytic radar desttpi. Diffusion effects. 

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