The Study On Preparation And Gas Sensitivity And Catalytic Characteristic Of CO Gas Sensitive Materials

Nanometer powder of copper oxide and its composite oxide with 10nm in diameter are prepared using nitrate copper by precipitation transformation method and sol-gel method. The effects of concentration of precipitator, concentration of anti-aggregative agent, transformation temperature, pH value and different precipitant on composition of phase of product, conversion rate and the grain size of CuO are studied. The optimum preparing conditions were obtained. Nanometer powders were characterized by XRD, TEM, TG-DTA and quadratic particle size distribution. CuO has been examined for the sensitivity of CO. The effects of preparation method, different carrier, calcination temperature and copper oxide content to the sensitivity of sensing element are examined, too. The results show that there are little difference of CO sensitivity between precipitation transformation method and sol-gel method, the sensitivity of copper oxide loading on zirconium oxide or cerium oxide is better than that of loading on alumina or silicon dioxide, the optimal calcinations temperature is 500 Celsius degree and the optimal copper content loading on cerium oxide is twelve percent. At the same time, the adsorption, desorption and catalytic properties of CuO, CuO/CeO2 of different ratio catalysts were examined by means of TPD method. We calculate the activation energy of desorption (Ed) and the pre-exponential factor (k0). When the loading content of copper oxide varies, the adsorption and desorption characteristic of CuO/CeO2 compared with the sensitivity of CuO/CeO2, The results show that the sensitivity and the catalytic properties of CuO/CeO2 have a parallel relation, that is to say, when the sensitive material has a good sensitivity, it has a good catalytic properties simultaneously. We want to interpret the sensing mechanism of copper oxide by the point of view of catalytic chemisorption theory; the cause of sensitivity of copper oxide was the CO chemisorption on the oxygen active regions. It is an innovation to combine the sensitivity and catalytic characteristic.