N2O在Au/Co3O4和Au/ZnCo2O4催化剂上的分解反应

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。

Catalytic decomposition of N2O over Au/Co3O4 and Au/ZnCo2O4 catalysts

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.