Cu对Pt/Cu-Mg-Al-O催化剂上NOx储存性能的影响

固定二价与三价阳离子摩尔比为3∶1,采用共沉淀法合成系列Cu-Mg-Al水滑石,经500 ℃焙烧制成复合氧化物Cu-Mg-Al-O（wCuO(％)分别为0、5、10、20,简称w-CMAO, w=0、5、10、20）.通过浸渍法制备Pt/Cu-Mg-Al-O负载型复合氧化物催化剂.XRD结果表明Cu在催化剂及其前驱体中高度分散.采用等温NO_x储存实验研究催化剂对NO_x的储存性能, NO_x-TPD法考察储存的NO_x脱附情况.实验结果表明,尽管Cu取代减少了催化剂中MgO含量,但增强了催化剂的NO氧化活性,有效提高了催化剂的NO_x储存性能.同时TPD结果进一步表明当CuO掺杂量在w=(10～20)％ 时,可以明显降低催化剂上生成的硝酸盐的分解温度.

Influence of Cu on NOx Storage Performance of Pt/Cu-Mg-Al-O Catalysts Derived from Hydrotalcites

A series of Cu-Mg-Al hydrotalcite compounds with M (II) :Al (III) molar ratio of 3 : 1 were prepared by co-precipitation method. Corresponding mixed oxides were obtained after calcination 500 ℃（wCuO(％)= 0, 5, 10, 20, denoted as w-CMAO, w=0, 5, 10, 20）. Pt/Cu-Mg-Al-O catalysts were prepared by impregnation with H2PtCl6 solution. XRD results showed that Cu was well dispersed in the catalysts and their precursors. NO_x storage performance was investigated using NO_x adsorption experiment at constant temperature, and decomposition of stored NO_x was also studied by TPD method. It was shown that although MgO content was decreased due to Cu addition, the activity of NO oxidation was improved, and NO_x storage performance was increased effectively. TPD results further showed that the decomposition temperature of nitrate formed on the catalysts can be reduced sharply when w=10％～20％ of CuO was added.