Electrochemical process flow schemes

In the first section, some fundamentals of electrochemical processes are defined. Common industrially relevant process flow schemes and equipment are described in the second section. The third section discusses the interest of microstructured reactors in electrochemical synthesis and gives an overview of the recent literature in this area. 

The economy of electrolytic processes, especially in the synthesis of organic specialties, is closely related not only to the electrochemical cell, but also to the straightforwardness of product purification [1]. This means that the main objective for the successful development of a new product from organic electrochemistry is closely related to the best process flow scheme, combining the different process steps. 

In the next layer of subjects we list the engineering sciences which are needed in various ways for understanding and further developing the core engineering subjects thermodynamics, chemical kinetics, electrochemical phenomena, and transport phenomena. These engineering sciences, which are themselves interrelated, form the basis for the analytical and numerical description of the chemical reactor and its peripheral equipment. For example, the subject of transport phenomena can be used to analyze difiiision-controlled reactions, separation schemes, transient processes in reactors, thermal processes, flow patterns in reacting systems, corrosion, difiusion in porous media, and other problems connected with reactor engineering. 

The reaction schemes shown in both Figures 3.5 and 3.6 indicate that the overall rate of the formation process not only depends on the rates of the involved elementary chemical and electrochemical reaction rates, but also on the rate of the diffusion ion flows and on the electron conductivity of the solid phases. All of these rates determine the direction in which the electrochemical processes will advance along the plate cross section. 

In an attempt to scavenge pure oxygen directly from seawater, Aquanautics Corp. [26] has developed a process similar to that of Roberts. In the Aquanautics scheme, the solution containing the carrier (in this case, a linear pentadentade polyalkylamine chelate of Fe or Co) flows through both anode and cathode of the electrochemical cell. 

In general terms, coupled mechanistic schemes are described by the letters E (electrochemical) and C (chemical). The order in which they are written denotes the order in which the processes occur. Thus an ECE mechanism describes a process in which an electrochemical step is followed by a chemical step, which is then followed by an electrochemical step. A chemical step is a step where no electron transfer to or from the electrode takes place. Such a step does not by itself produce a charge flow into or out of the electrode and thus is not directly observable by an external measuring circuit. It may, however, influence charge flow because of other steps in the mechanism, which can be detected indirectly. The chemical step is not directly influenced by the electrode potential. An electrochemical step on the other hand involves electron flow to and from the electrode and as such produces a flow of charge that can be monitored by the external measuring circuit. 

In a cell with Li and PA electrodes containing LiC104, on external connection of the electrodes, current flows as a result of the electrochemical reactions shown in Scheme 2. Li liberated at the anode is incorporated into the PA as a counter-ion. These processes have been rationalized in terms of the reduction potentials of PA, in the pristine, oxidized and reduced states, and those of the redox couples relevant for the doping process under consideration. ... 

---