Electrochemical oxygen pump

M. Stoukides, and C.G. Vayenas, The effect of Electrochemical Oxygen Pumping on the Rate and Selectivity of Ethylene Oxidation on Polycrystalline Silver, J. Catal. 70, 137-146(1981). 

O.A. Mar ina, V.A. Sobyanin, V.D. Belyaev, and V.N. Parmon, The effect of electrochemical oxygen pumping on catalytic properties of Ag and Au electrodes at gas-phase oxidation ofCH4, Catalysis Today 13, 567-570 (1992). 

Zirconia cells similar to the ones employed in the present study, have been used i) by Mason et al (18) to electrochemically remove oxygen from Pt and Au catalysts used for NO decomposition. It was shown that electrochemical oxygen pumping causes a dramatic increase in the rate of NO decomposition (18,19), ii) by Farr and Vayenas to electrochemically oxidize ammonia and cogenerate NO and electrical energy (20,21), iii) by Vayenas et al (11,12,22,23) to study the mechanism of several metal catalyzed oxidations under open circuit (potentiometric) conditions. 

Figure 3. Transient effect of electrochemical oxygen pumping. Conditions RC 2, Pi X 10-2 bar, P0jt = 9.5 X 10 2 bar, and 400°C.

Figure 2 Schematic showing (a) potentiometric operation, (b) fuel cell operation and (c) electrochemical oxygen pumping.

Yttrium stabilized zirconia (Zr02-Y203) as an electrolyte for reduction of molecular oxygen at elevated temperatures (400-800°C) has been already discussed in Section 6.23.4. In fact, both the reduction of oxygen and the oxidation of the oxide ion at the Pt/zirconia interface is reversible and the transport of both species in zirconia is so rapid it is possible to construct an electrochemical oxygen pump, which is the heart of the limiting current oxygen sensor described in this chapter (Saji, 1987). The overall electrochemical reaction that takes place at the porous Pt electrode is... 

High-Temperature Oxygen Sensors Based on Electrochemical Oxygen Pumping... 

Catalytic applications of solid electrolyte membrane reactors using electrochemical oxygen pumping (EOP)... 

In addition, solid electrolyte membranes potentially can be used for electrochemical oxygen pumping and as fuel cells which can produce chemicals while generating electricity. 

Another class of dense inorganic membranes that have been used in membrane reactor applications are solid oxide type membranes. These materials (solid oxide electrolytes) are also finding widespread application in the area of fuel cells and as electrochemical oxygen pumps and sensors. Due to their importance they have received significant attention and their catalytic and electrochemical applications have been widely reviewed [94-98]. Solid materials are known which conduct a variety of cationic/anionic species [14,98]. For the purposes of the application of such materials in catalytic membrane reactor applications, however, only and conducting materials are of direct relevance. 

The association of an electrochemical oxygen pump and an oxygen sensor allows... 

That s why the solid electrolytes in the electrochemical oxygen pumps not only provide regulation of oxygen concentration in the different technological... 

Development of ionic conductors based on stabilized zirconia has reached a level of maturity, where most of the research on such materials concentrates mainly on obtaining incremental empirical improvements in conductivity by better processing control and refinement of the microstructure of the solid electrolyte and SE. Further increases in the conductivity are important in terms of enhancing the efficiency of systems such as O2 sensors, zirconia-based mixed-potential gas sensors, electrochemical oxygen pumps, heating elements, and fuel cells [4-7]. The systematic errors, as have been considered before, are errors with a known determined functional connection with the source of their cause, and the conformity of their appearance can be definitely described. 

This allowed operation of the membranes as electrochemical oxygen pumps, where an applied voltage could be used to increase the transport across the membrane. This earlier work is described by Eng and Stoukides, who also discuss basic principles in greater depth. 

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