Multireaction systems

Equilibrium in multiphase and/or multireaction systems. If more than one phase is present in the system, a criterion of phase equilibria has to be satisfied together with the chemical equilibrium criterion. For instance, in a gas-liquid system components are in chemical equilibrium in the phase where the reaction occurs, but vapour-liquid equilibria between the gas and the liquid phases must also be taken into account. To determine the equilibrium composition of a reacting mixture in both phases, chemical equilibrium constants as well as data concerning vapour-liquid equilibria for all components of the reaction mixture should be known. In the equilibrium state ... 

Methods discussed for a one-reaction system can easily be extended to multireaction systems. For all independent reactions, a separate equilibrium constant is defined as ... 

Reaction calorimeter Wide variety of operations Useful for thermal parameters Heat is non-specific source of information for multireaction systems... 

Our treatment of Chemical Reaction Engineering begins in Chapters 1 and 2 and continues in Chapters 11-24. After an introduction (Chapter 11) surveying the field, the next five Chapters (12-16) are devoted to performance and design characteristics of four ideal reactor models (batch, CSTR, plug-flow, and laminar-flow), and to the characteristics of various types of ideal flow involved in continuous-flow reactors. Chapter 17 deals with comparisons and combinations of ideal reactors. Chapter 18 deals with ideal reactors for complex (multireaction) systems. Chapters 19 and 20 treat nonideal flow and reactor considerations taking this into account. Chapters 21-24 provide an introduction to reactors for multiphase systems, including fixed-bed catalytic reactors, fluidized-bed reactors, and reactors for gas-solid and gas-liquid reactions. 

Determining Kinetic Constants in Bireactant and Multireactant Systems. 112... 

Full uncompetitive inhibition (O Figure 4-lIa) occurs as a result of inhibitor binding (only) to the ES complex binding is thus ordered. It occurs rarely in unireactant systems but is a common inhibitory mechaitism in multireactant systems. Since ESI is nonproductive, high inhibitor concentrations can drive... 

Reactive extraction processes involve simultaneous reaction and liquid-liquid phase separation and can be effectively utilized to obtain significant improvements in yields of desired products and selectivities to desired products in multireaction systems, thereby reducing recycle flows and waste formation. The combination of... 

Similar to reactive adsorption, the reactive extraction can be applied primarily in multireaction systems, for improvement in yields and selectivities to desired products. The combination of reaction with liquid-liquid extraction can also be used... 

Equation 5.1-10 applies to a multireaction system. For example, if in addition to reaction 5.1-4, the following reaction occurs ... 

Finally, a multireaction system will also be considered. The example is related to the separation of binaphthol enantiomers, and was reported by Morbidelli, Mazzotti and co-workers in some detail [1]. Separation of the enantiomers is even possible with an achiral stationary phase due to dimerization reactions taking place in the fluid phase. 

In this section, the application of equilibrium theory is illustrated for a fairly complex multireaction system. The problem to be considered is that of the separation of binaphthol enantiomers through using achiral chromatography. This problem was studied by Baciocchi et al. [1] among others, who in particular made the following experimental observations. When a pulse with a racemic composition of enantiomers was injected on to the column, no separation occurred. However in all cases... 

Multireaction systems often have some quasi-equilibrium steps whose forward and reverse rates greatly exceed the net rate TZj at all conditions of interest. For such a reaction, the approximation... 

To describe the state of a reaction in a phase, we need to know the stoichiometric coefficients, j, and the chemical potential, pi, for each species in the reaction. For reaction equilibrium, the quantity AG = E Vi pi = 0 (as is T diS). For a possible, or spontaneous, reaction, AG < 0. For multireaction systems, complete equilibrium corresponds to dG = 0 for the system, that is, the Gibbs energy of the phase is a minimum. The total internal entropy production must vanish for the entire system. Similar consideration apply to multiphase systems. An expression analogous to equation 39 for dE, but for fixed T and p conditions, is ... 

Burghardt, A., Transport Phenomena and Chemical Reactions in Porous Catalysts for Multicomponent and Multireaction Systems, Chem. Eng. Process., 21, 229-244 (1986). 

The condition for chemical equilibrium in this multireaction system is G = minimum or dG = 0 for all variations consistent with the stoichiometry at constant temperature, pressure, and total mass. For the present case this implies... 

The dissolution and ionization of a mixture of electrolytes provides another example of equilibrium in a multireaction system. To be specific, suppose two electrolytes A aBv3 and GuqH ionize in solution as follows ... 

The necessary and sufEcient conditions for reactive azeotropy for the multicomponent, multireaction system can be then expressed in terms of the transformed variables (Ung and Doherty, 1995 ),... 

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