ON THE ANALYSIS OF CO2, H-2- AND CO, H2O-MIXTURES BY WATER-GAS POTENTIOMETRY WITH SOLID-ELECTROLYTE CELLS

The potentiometric analysis of CO2, H-2- and CO, H2O-mixtures using ox ide ion-conducting solid electrolytes requires the adjustment of the w ater-gas equilibrium without side reactions in the high-temperature ga lvanic cell. Conventional cell designs suitable for the analysis of H- 2, H2O- and CO, CO2-mixtures are not applicable due to the insufficien t gas residence times in the cells and the insufficient catalytical ac tivity of the platinum electrodes. Solid electrolyte cells have to be modified by integrating of suitable catalysts. Under optimized conditi ons of gas velocity and cell temperature both gas systems can be analy zed only by measuring the cell tension U(= -emf) and temperature in th e favorized temperature range around 813 degrees C. Here systematical errors of the component ratio or the mole fraction were smaller than 6 %. Several fundamental requirements for the application of catalysts i n solid electrolyte cells for the analysis of reactive water-gas mixtu res are pointed out.