1984 Volume 5 Issue Special Pages 241-247
Works of conventional tin oxide gas sensors are often disturbed by a contact with ethanol vapor. In order to remove such a disturbance, it was tried to insensitize the sensor to ethanol by use of oxidation catalysts. Of the twelve different catalysts tested, alumina supported Pt catalyst (Pt(1%)/Al2O3) was found to be the most effective for total oxidation of ethanol vapor; ethanol was completely oxidized above ca. 200°C under the experimental conditions. The effects of Pt(1%)/Al2O3 catalyst in the actual sensing performance were examined by using three types of sensor elements. As a result, the best data were obtained with the coated element which was prepared by coating the conventional sensor element (base element) with Pt(1%)/Al2O3 catalyst. The sensitivity of the base element to ethanol vapor was higher than those to CH4 and C3H8 below 400°C and was still significant at 500°C, The coated element, however, was almost insensitive to ethanol vapor in the temperature range 300-500°C, while it was as sensitive to CH4 and C3H8 as the base element. It was also confirmed that the rate of sensor response was little affected by the catalyst coating.