HYDROGEN ANALYZER BASED ON COULOMETRIC TI TRATION USING PROTON CONDUCTION SOLID-ELECTROLYTE

Employing the same method of Otsuka's oxygen analyzer (Trans. JIM, 25 (1984) 639), we developed a new type hydrogen analyzer based on coulom etric titration using a proton conductive solid electrolyte. The follo wing electrochemical cell was constructed by utilizing indium doped ca lcium zirconate as the electrolyte and utilizing sintered porous plati num as the electrodes. (-)Pt, Ar+1%H-2/CaZrO3(+10 mol%In2O3)/Ar, Pt(+) The cell was operated at 973 K. The left electrode chamber was expose d to the flowing Ar + 1%H-2 gas, while the right electrode chamber was closed and Ar gas was circulated. On imposing the positive constant v oltage to the cell, the right electrode worked non-reversible and the hydrogen potential of the right electrode chamber was decreased to the very small value specified by the Hebb-Wagner's polarization conditio n state. In the polarization state, the hydrogen to be analyzed was in jected to the right electrode chamber by a micro-syringe and the exces s current due to proton transport from the right to the left electrode was measured in the external circuit. The quantity of electricity cal culated by the integration of the decay curve of the excess current wa s in good agreement with theoretical value evaluated from the amount o f injected hydrogen by Faraday's law. The hydrogen in a commercial pal ladium plate was analyzed successfully by dropping the specimens in th e combustion furnace locate in the circulating path of the right elect rode chamber. The performance and the best analyzing condition were di scussed theoretically in terms of the electrochemical properties of th e electrolyte. This type of hydrogen analyzer doesn't need a standard sample and any calibration for the blank conditions and has high abili ty to detect a small amount of hydrogen as little as 10(-8) mol(H).