Electrocatalytic membrane reactors

These applications will be briefly treated in this section. As will become evident, the solid electrolyte membrane materials are either stabilized oxides or mixed oxides. Further details of science and technology of electrocatalytic membrane reactors beyond the scope of this chapter can be found in a number of excellent reviews [Ceilings et al., 1988 Stoukides, 1988]. 

Figure 8.7 Schematic diagrams showing two electrocatalytic membrane reactor configurations (a) eicctrochemicai oxygen pumping and (b) solid oxide fuel cell operation.

Electrocatalytic membrane reactors (eCMRs) for fuel cell and other applications... 

Generic fuel cell electrocatalytic membrane reactor... 

The electrocatalytic membrane reactor in the fuel cell or cogeneration modes... 

Figure 15.20 Electrocatalytic membrane reactor (eCMR) for electrochemical hydrogenation (eHyd) of furfural with protons produced from water electrolysis Reprinted with permission from Green et al. (2013).

The electrocatalytic membrane reactor as a unitized regenerative fuel cell... 

The electrochemical process offers the possibilities to produce ammonia with milder working conditions than Haber-Bosch process. Ammonia can be electrochemically synthesised under atmospheric pressure. There is no thermodynamic limitation in the electrochemical process. As mentioned before, the ammonia industry depends very much on natural gas, and consequentiy releases a huge amount of CO2. With the demand for environmentally friendly industry and the depletion of fossil fuels, the use of renewable feedstock and electricity is encouraged. Recently, renewable feedstock such as H2O or H2 from water electrolysis was found to be usable in an electrocatalytic membrane reactor (Lan, Irvine, Tao, 2013). 

In general, a solid-state electrocatalytic membrane reactor consists of the dense membrane electrolyte, porous anode, and porous cathode. The general requirements for the... 

Catalysts play an important role in overcoming the activation barrier in ammonia synthesis. It is weU known that strong N=N triple bond and the low sticking coefficient of the molecule nitrogen limit the choice of catalyst. However, the mechanism of ammonia formation on an electrocatalyst seems to be different from that of the conventional catalyst. The information about the conventional catalyst in the Haber-Bosch process and the electrocatalyst in the electrocatalytic membrane reactor are described in this section. 

In the electrocatalytic membrane reactor, the reactions normally take place at the electrodes. This means that the electrode should act as both electrode and catalyst. As an electrode, high electronic conductivity is required. In general, the electronic conductivity of electrode materials should not be less than 10 S/cm at the operating temperature. As a catalyst, the material must have good catalytic activity for the corresponding reactions. 

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