| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 91 === The purpose of this study is to investigate the effect of promoters on the sensing behavior of an YSZ type CO sensor with copper catalyst layer. Copper with 15wt% was loaded onto γ-Al2O3 by electroless-plating method and the promoters including Cr, Zn, Ce were then loaded by impregnation method. The promoter content varied from 5wt% to20wt%. The effect of competitive oxidation of H2 with CO on the sensing was also included. XRD, TPR, N2O titration and ESCA were used to characterize the layer and electrode.
From the characterization, it is found that all promoters can improve copper dispersion and increase copper surface area. However, the addition of Ce is better than that of Cr or Zn. It is also found that the addition of Cr would cause the formation of CuCr2O4 which could inhibit Cu reacting with Al2O3, and the addition of Ce can cause CuO reduction at lower temperature.
Sensitivity analyses show that the sensitivity can be improved adding promoter into copper catalyst layer. The sensitivity increases with increasing the addition of Ce or Zn. However, the sensitivity decreases with increasing the addition of Cr. The best sensing element is the one with Cu15Zn20 catalyst layer.
For the competitive oxidation, the experimental shows that the response current of H2 decreases with increasing CO concentration.
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