Zirconia cell

The wet analysis assumes that the water vapor is present. The maximum theoretical carbon dioxide content is 9.66 per cent. The zirconia cell method of measuring oxygen is on the wet basis. 

Most oxygen trim systems interpose an additional link in the air/gas ratio controller. Others use an additional valve. Most types are based on the zirconia cell installed in the flue, while others use paramagnetic or electrolytic cell methods. The zirconia type has the advantage that there is no time lag in sampling, nor is there a risk of contamination of the sample. 

The development of reliable zirconia cells which can measure the gas analysis in situ without recourse to gas-sampling techniques has led to systems which provide feedback to the air/fuel ratio control system. 

T. Chao, K.J. Walsh, and P.S. Fedkiw, Cyclic voltammetric study of the electrochemical formation of platinum oxide in a Pt/yttria-stabilized zirconia cell, Solid State Ionics 47, 277-285 (1991). 

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. 

High Temperature Ceramic Sensors (Zirconia Cells)... 

Servomex (U.K.) Ltd. Technical Bulletin 7981-5167 (1990). 700 series Zirconia cell—how it works. 

Eza Potential difference across Zirconia cell V ml2t-3a- ... 

Electrochemical pumps have also been successfully used to promote reactions catalytically. If oxygen is pumped through a zirconia cell into a reaction chamber which is, e.g., filled with hydrocarbons, not only the oxygen that is transferred, reacts. The anode itself can act catalytically. It seems that this so-called NEMCA effect ( Nonfaradaic Electrochemical Modification of Catalytic Activity 51) relies on a hindered surface reaction as a consequence of which the applied potential is translated into a concentration polarization, as reflected by the enrichment of a not fully oxidized oxygen species (e.g., O or O2") at the interface.51"53 For this species, redistribution equilibrium may be assumed that... 

Zirconia cells with Pt catalyst-electrodes can also be used to convert ammonia to nitric oxide with simultaneous electrical energy generation (6-7). Other industrially important oxidation reactions have been recently proposed for solid-state electro-... 

C. Tsaofang, K.J. Walsh and P.S. Fedkin, Cyclic Voltammetric Study of the Electrochemical Formation of Platinum Oxide in a Pt/Yttria-Stabilized Zirconia Cell, Solid State Ionics 47 (1991) 277-285. 

Carbonate and zirconia cells can be united to the three-pole arrangement (25-72), with which (on the base of Equations (25-73) and (25-75)) O, and CO, can be measured simultaneously and continuously at the same electrode. Such measurements (Figure 25-36) are of importance if the concentration of two gases with practically the same dynamics shall be recorded. 

A high-pressure probe constructed to allow the study of supercritical xenon as it interacts with different polymers (bisphenol-A polycarbonate or polytetrafluoro-ethylene) was reported by Nagasaka et al The probe, which has a zirconia cell with a Be-Cu flange and indium o-ring can be used in a range of pressure up to 20 MPa, and temperatures from 150 to 400 K (see Fig. 6). Experiments performed up to 10 MPa showed xenon inside the polymer experienced a very different state from that of free xenon, which was attributed to the limitation on xenon cluster size. Essentially no exchange between the supercritical and confined xenon phases occurred on the second timescale. 

N.L. ROBERTSON, J.N. MICHAELS, Oxygen exchange on platinum electrodes in zirconia cells location of electrochemical reaction sites , J. Electrochem. Soc., vol. 137, no. l,p. 129-135,1990. 

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