CO/CO2 ELECTROCHEMISTRY ON ZIRCONIA ELECTROLYTE WITH PLATINUM-ELECTRODES IN RELATION TO AMPEROMETRIC OXYGEN SENSORS

被引:13
作者
COPCUTT, RC [1 ]
MASKELL, WC [1 ]
机构
[1] MIDDLESEX POLYTECH, CTR ENERGY TECHNOL, BOUNDS GREEN RD, LONDON N11 2NQ, ENGLAND
关键词
D O I
10.1016/0167-2738(92)90373-W
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
An amperometric zirconia oxygen sensor operated in the flue of a gas-burning combustion system showed a current linearly related to oxygen partial pressure under excess-air conditions (diffusion-controlled) and a current of the same sign but sensitive to sensor operating temperature (kinetically-controlled) for fuel-rich operation. Hence the sensor did not unambiguously distinguish the two sides of stoichiometry. Electrochemical investigations were carried out in CO/CO2/N2 and CO2/O2/N2 mixtures to help resolve this problem. Electrode conductance values in CO/CO2/N2 Mixtures were sometimes higher when approached from the anodic compared with the cathodic direction suggesting electrode blocking by a reduced and non-reversibly adsorbed species (CO or C). An abrupt decrease of more than an order of magnitude in conductance was observed as the temperature was raised through a critical temperature (near 700-degrees-C). This was thought to be associated with the change in stability of CO at that temperature via the disproportionation reaction (2CO reversible CO2 + C). Results indicated that the problem of distinguishing the two sides of stoichiometry could be ameliorated by constructing an amperometric sensor having a high ratio of cathode to anode 3-phase boundary lengths and operating at relatively low temperatures.
引用
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页码:119 / 125
页数:7
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