Catalytic decomposition of N2O over Au/Co3O4 and Au/ZnCo2O4 catalysts
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摘要: 通过调变HAuCl4溶液的pH值和Au负载量,用沉积-沉淀法制备了一系列Au/Co3O4催化剂,并采用AES、BET、XRD、SEM、XPS和H2-TPR等技术对催化剂的结构和组成进行了表征,考察了制备条件对其在有氧气氛中催化N2O分解反应性能的影响规律,得到了催化剂最佳制备条件:HAuCl4溶液pH值为9,Au负载量为0.29%。催化测试结果表明:虽然ZnCo2O4的催化活性优于Co3O4,但0.31%Au/ZnCo2O4的活性和稳定性低于0.29%Au/Co3O4。500℃、在含氧气氛中连续反应10 h, 两者均可完全分解N2O,但在含氧、含水气氛中0.29%Au/Co3O4和0.31%Au/ZnCo2O4上的N2O转化率分别为92%和63%。究其原因,发现Au/Co3O4中Au和Co组分间存在协同效应,而Au/ZnCo2O4中Au和Co组分间则没有协同效应。Abstract: Au/Co3O4 catalysts with different gold loadings were prepared by the deposition-precipitation method using HAuCl4 solution through adjustment of the pH value to 7, 9 or 11. Their catalytic properties for N2O decomposition in the presence of oxygen were investigated. 0.29%Au/Co3O4 catalyst prepared at the pH value of 9 exhibited higher catalytic activity than 0.31%Au/ZnCo2O4 prepared under optimal conditions although ZnCo2O4 was more active than Co3O4. AES, BET, XRD, SEM, XPS and H2-TPR characterization results indicated a synergistic effect existed between gold and cobalt species in Au/Co3O4, which is, however, absent in the Au/ZnCo2O4. Despite that N2O was completely decomposed at 500 ℃ in oxygen atmosphere for both the samples, the N2O conversion was decreased to 92% and 63% after the reaction was carried out for 10 h in the presence of both oxygen and steam over the 0.29%Au/Co3O4 and the 0.31%Au/ZnCo2O4, respectively.
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Key words:
- N2O decomposition /
- Co3O4 /
- ZnCo2O4 /
- gold catalyst
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