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yingxingwang银虫 (小有名气)
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3.4. Effect of average oxidation state (AOS) on the activity The AOS of OMS-2 catalyst is usually determined by potentio-metric titration method [34] or by the XPS analysis of Mn 3s [35,36]. Herein, the AOS was calculated from the corresponding formula using the result from the ICP-AES analysis (Table 2). It can be seen from Table 2 that the AOS value of the OMS-2 catalyst (3.91) in our study is in agreement with that (3.9) of the reported OMS-2 [35], suggesting that this method is reasonable. The AOS values of the M-OMS-2 increase after doping with transition metals. The AOS values decrease in the following order: Cu- OMS-2 > Ni-OMS-2 > Co-OMS-2 > Cr-OMS-2 > Fe-OMS-2, which is very similar to the decreasing order of the Rs values. Xia et al.[34] observed that the higher AOS lead to higher CO oxidation rates over the Cu(Co, Ag)-OMS-2 catalysts. Santos et al. [35] also found that the OMS-2 with the highest AOS showed the best catalytic activity for the total oxidation of ethyl acetate. Therefore, it could be concluded that the AOS values of the M-OMS-2 catalysts are in correlation with their catalytic activities of DME combustion. |
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obscure nacissus
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感谢参与，应助指数 +1
yingxingwang: 金币+30 2013-04-08 18:42:56
感谢参与，应助指数 +1
yingxingwang: 金币+30 2013-04-08 18:42:56
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平均氧化度对催化活性的影响 OMS-2催化剂的平均氧化度通常用电位滴定法 [34] 或Mn 3s 的XPS分析法 [35,36]测定。这里，利用ICP - AES分析的结果（表2）经相应公式计算得到AOS值。从表2可以看出，我们研究的OMS-2催化剂的AOS值和已有报道的OMS-2 [35]的值一致，这表明该方法是可靠的。掺杂过渡金属后，M-OMS-2 的AOS值增大。AOS值降低的大小顺序为：Cu-OMS-2 > Ni-OMS-2 > Co-OMS-2 > Cr-OMS-2 > Fe-OMS-2，这和Rs值的降低顺序一致。Xia等注意到AOS越高，使其CO氧化率高于 Cu(Co, Ag)-OMS-2催化剂更多。Santos 等也发现，高AOS值的OMS-2对乙酸乙酯的完全氧化催化活性更强。因此，可以推断，M-OMS-2催化剂的AOS值大小与它们对DME氧化的催化活性高低一致。 |
2楼2013-04-08 16:41:38