Multiphase reacting systems

The most catalytic or noncatalytic processes involving reactions in multiphase systems. Such processes include heat and mass transfer and other diffusion phenomena. The applications of these processes are diverse and its reactors have their own characteristics, which depends on the type of process. For example, the hydrogenation of vegetable oils is conducted in a liquid phase slurry bed reactor, where the catalyst is in suspension, the flow of gaseous hydrogen keeps the particles in suspension. This type of reaction occurs in the gas-liquid-solid interface. 

As a second example, we have the Fischer-Tropsch synthesis. This process allows producing liquid hydrocarbons of high molecular mass with long carbon-chain molecules (such as gasoline, kerosene, diesel, and lubricant) from synthesis gas (CO-I-H2). This process takes place in slurry bed reactors, where the reactant gases flow through a liquid mixture inert. 

The multiphase reactions are characterized from the following mechanisms  

Rate of mass transfer from a gas phase to liquid phase RA = khah (Q — Cb) 

The rate of mass transfer of gas (A) in the liquid to the solid surface  

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Research on the development of separation methods for the multiphase reacting system led to the development of a three phase (oil, water, and a solid) separation process. A patent was awarded in 1998 in US [53] and subsequently in some other countries... 

A more complex behavior is expected when multiphase reacting systems are examined. As an example, consider the gas-liquid reactor sketched in Fig. 7.1(c), which behaves as a batch reactor with respect to the liquid phase and as a continuous reactor with respect to the gaseous phase. A reactant is transferred from the gaseous to the liquid phase, where it reacts with a substrate. 

Useful insights into the thermodynamics of a multiphase reacting system can be obtained by analyzing the situation when chemical and phase equilibrium (C PE) are achieved simultaneously. The Gibbs rule can be used to find the degrees of freedom F ... 

In discussing states of multiphase, nonreacting systems in 9.1, we presented two ways for identifying an intensive state T and T" specifications. That discussion was extended to reacting systems in 10.3.1. For both reacting and nonreacting systems we found that the difference between T and T" is the number of internal constraints in an T -specification we implicitly rely on internal constraints to complete an identification of state, but in an F -specification we explicitly include the consequences of internal constraints. In multiphase reacting systems, the difference is... 

Phoenix and Heidemann on the other hand, adapted Michelsen s approach " for chemical equilibrium calculation in multiphase reacting systems, applying iterative corrections to ideality with the Soave-Redlich-Kwong equation of state. Phoenix and Heidemann applied this procedure with the Peng-Robinson equation of state to study the phase behaviour of natural gases containing elemental sulfur, which is known to exist as a number of species up to... 

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