Preparation of Co-Al mixed oxide supported gold catalysts and their catalytic activity for N2O decomposition
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摘要: 分别用离子交换法和共沉淀法制备了钴铝复合氧化物负载金催化剂，用于催化分解N2O。离子交换法制备的催化剂活性优于共沉淀法制备的催化剂。对于离子交换法制备的催化剂，考察了金负载量、HAuCl4溶液的预处理方式、焙烧温度对催化剂活性的影响，用BET、XRD、H2-TPR等技术对催化剂进行了表征，优化出了催化剂的最佳制备参数：金负载量1.1%、预调节HAuCl4溶液的pH值至9.0、300℃焙烧。在钴铝氧化物中加入适量的助剂Na，提高了Co3+的还原性和催化剂的低温活性，在此基础上制备的1.5%Na/1.1%Au/Co-Al催化剂的低温活性优于1.1%Au/Co-Al和1.5%Na/Co-Al。Abstract: Au/Co-Al catalysts were prepared by using the ion-exchanged and co-precipitation methods, and their activities for the catalytic decomposition of N2O were tested. BET, XRD, and H2-TPR techniques were used to characterize the catalysts. The results show that the activity of Au/Co-Al catalyst prepared by using ion-exchanged method is higher than that using co-precipitation method. For the catalysts prepared by ion-exchanged method, the effects of preparation parameters, such as Au loading, pretreatment of HAuCl4 solution, and calcination temperatures, upon N2O conversion were investigated. The optimal preparation parameters of Au/Co-Al catalysts are that 1.1% of Au loading, pH value of HAuCl4 solution adjusted to 9.0, and 300℃ of calcination temperature. It is indicated that the addition of Na species in Co-Al mixed oxide promoted the reduction of Co3+ to Co2+ and enhanced the catalytic activity for N2O decomposition.
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