Novel Y2O3 Doped MnOx Binary Metal Oxides for NOx Storage at Low Temperature in Lean Burn Condition
Novel Y2O3 Doped MnOx Binary Metal Oxides for NOx Storage at Low Temperature in Lean Burn Condition
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DOI：
10.1007/s10562-009-9877-2
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发表时间：
2009-02
影响因子：
2.8
通讯作者：
Junhua Li;Wei Li;Lisi Wei;R. T. Yang
中科院分区：
文献类型：
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作者：
Junhua Li;Wei Li;Lisi Wei;R. T. Yang
采用恒pH共沉淀法合成了MnOx-Y2O3二元金属氧化物催化剂，考察了其对NOx的储存能力和吸附过程。在静止空气中于500℃焙烧4h的纯MnOxx和Y2O3相均为体心结构，而含Mn和Y的二元金属氧化物主要为非晶相。Y_2O_3的掺杂可以显著提高催化剂的比表面积，这可能是由于提高了催化剂在100℃时的NO储存能力和催化氧化能力。XPS结果表明，在二元氧化物中，Mn和Y都以3+的化学态存在。红外光谱可以用来解释NO在二元金属氧化物上的存储过程：NO可以分别以硝酸盐和亚硝酸盐的形式吸附在MnOx位和Y2O3位上，然后Y2O3位上的亚硝酸盐被转移到Mn2O3位上，然后被氧化成硝酸盐。结果表明，由于Y_2O_3的掺杂，提高了NO的储存能力，最终以硝酸盐形式吸附在Mn2O_3表面。
MnOx-Y2O3binary metal oxide catalysts are synthesized by a constant-pH co-precipitation method, their ability of NOxstorage capacity and absorbing process were investigated. The pure MnOxand Y2O3calcined at 500 °C for 4 h in static air are both of body-centre structure, while the binary metal oxides containing Mn and Y are mainly of amorphous phase. The adulteration of Y2O3can remarkably improve the specific surface areas of the catalysts, which probably result of the enhancement on NO storage capacity and catalytic oxidation ability of NO at 100 °C. The XPS results indicate that both Mn and Y have 3+ chemical states in the binary oxides. FT-IR spectra could be beneficial to explain the NO storage process on the binary metal oxide: NO can be adsorbed on the MnOxand Y2O3sites as nitrates and nitrites, respectively, and then the nitrites on Y2O3site are shifted to Mn2O3site and then is oxidized to nitrates. As a result, the NO storage capacity is enhanced due to the adulteration of Y2O3, finally the NOxare adsorbed on the Mn2O3site as nitrate species.