Multi-charged reactants

The effect of physical processes on reactor performance is more complex than for two-phase systems because both gas-liquid and liquid-solid interphase transport effects may be coupled with the intrinsic rate. The most common types of three-phase reactors are the slurry and trickle-bed reactors. These have found wide applications in the petroleum industry. A slurry reactor is a multi-phase flow reactor in which the reactant gas is bubbled through a solution containing solid catalyst particles. The reactor may operate continuously as a steady flow system with respect to both gas and liquid phases. Alternatively, a fixed charge of liquid is initially added to the stirred vessel, and the gas is continuously added such that the reactor is batch with respect to the liquid phase. This method is used in some hydrogenation reactions such as hydrogenation of oils in a slurry of nickel catalyst particles. Figure 4-15 shows a slurry-type reactor used for polymerization of ethylene in a sluiTy of solid catalyst particles in a solvent of cyclohexane. 

Redox reactions at the interface between immiscible liquids fall into two classes. The first class includes spontaneous processes that occur in the absence of external electromagnetic fields. This type of redox transformation has been investigated in bioenergetics [2], model membrane systems [20] and at oil/water interfaces [1]. Redox reactions in the second class occur at the interface between immiscible electrolytes when external electrical fields are applied to the interface, and under these conditions interfacial charge transfer reactions take place at controlled interfacial potentials [11, 35, 36]. Such electrochemical interfacial reactions are usually multi-stage processes that proceed through five stages (i) diffusion of reactants to the interface (ii) adsorption of reactants onto the interface (iii) electrochemical reaction at the interface (iv) desorption of products from the interface (v) diffusion of products from the interface. 

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