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The three-way catalysts (TWCs) promoters (Ce-Zr)O2, (Pr-Ce-Zr)O2 and (Pr-Zr)O2 were prepared by solgel like method. They were characterized by XRD, EXAFS and BET surface area determination. The reduction features of the promoters were measured by temperature-programmed reduction (TPR) of He to access the potential for the promoters containing praseodymia as oxygen storage component in three-way catalyst. The (Pr-Zr)O2 cubic solid solution is formed at high temperature up to 800 ℃, which makes it more reducible than the (Ce-Zr)O2 solid solution. For the (Pr-Ce-Zr)O2 samples, the ternary solid solution plays an important role in the reduction process. The performance of the three-way catalysts with fully formulated Pt, Pd and Rh is proceeded by using both light-off temperature under a stoichiometric gas composition and the conversion of CO, C3H6 and NO under changing air/fuel ratio at a constant reaction temperature 400℃. The results indicate that a small amount of praseodymia doping into (Ce-Zr)O2 favors the light-off temperature of C3H6 and NO, and all the catalysts containing praseodymia obviously exhibits enhanced width of S value for NO conversion at lean region (S≥1.00). 相似文献
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本文运用原位电子电导技术,测定了La-Cu-O复合氧化物分别在O_2,CO气氛下的电导瞬间应答曲线。从O_2吸附使电导率升高,CO吸附使电导率降低直至吸附平衡。以及从电导率值,说明在273~573K温度区间为P型半导体。还分别测定了在真空及空气,一氧化碳气氛下的平衡电导率和温度的关系以及不同的O_2,CO进样模式下电导率随温度的变化。发现在预吸附氧后再引入CO的情况下,在403K,443K和533K出现了三次电导率的突降。结合XPS测定中Om结合能的数据,分析了三个突变温度点可能为表面上不同能量的吸附氧所引起,并表明在此温度范围,反应以Eley-Ridcal机理为主。 相似文献
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Promoter of (Ce-Zr)O_2 Solid Solution Modified by Praseodymia in Three-Way Catalysts 总被引:3,自引:2,他引:1
CeO2 ispresentinthemajorityoftheformulationsofthethree waycatalystsduetoitswell knownmulti pleeffectssuchas :(1)stabilizationofthepreciousmetalsdispersionandthealuminasupport[1] ,(2 )pro motionofwatergasshiftreactionandsteamreformingreaction[2 ] andsoon .TheprimaryfunctionofCeO2 intheTWCsistoprovideoxygenstoragecapacity(OSC) ,actingasanefficient“oxygenbuffer”toun dergoeffectivereduction/oxidationcyclesbyshiftingbetweenCeO2 underoxidizingconditions (oxygenstor age)andCe2 O3underreducingco… 相似文献
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非贵金属废气净化三效催化剂的研制 总被引:4,自引:0,他引:4
研制了具有实用性的非贵金属废气净化三效催化剂,它对CO、HC的完全氧化和NO_x还原成N_2均有较高转化率。讨论了不同活性组份,不同制备方法和工艺的影响以及催化剂的热稳定性。 相似文献
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建立了一套具有一定特点的脉冲气固色谱装置。可在接近反应条件下进行实验。(1)利用吸附平衡数据,计算了 CO 及 O_2在载体γ-Al_2O_3上的吸附等温线、微分吸附热及吸附熵变,并分析了随温度变化吸附性能转变的规律。(2)利用不可逆吸附和热脱数据,研究了附载在γ-Al_2O_3上稀土钙钛矿型催化剂的 CO 和 O_2的吸附性能,观察到 CO 氧化的反应活性和 CO 不可逆吸附之间有一定关联;CO 从催化剂表面热脱产物为 CO_2;并发现在表面“吸饱”CO 后,对 O_2没有不可逆吸附。 相似文献
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对钙钛矿型Rh/BaZrO3/γAl2O3催化剂进行了NOx储存量(NSC)及NO氧化-还原性能的测试.结果表明,在400℃无还原剂C3H6贫燃条件下,Rh/BaZrO3/γ-Al2O3的NSC比300℃时高41.2%,这表明NO在较高温度时氧化速率增加.而在含C3H6情况下,无论是在400℃或300℃,NSC值均有所下降,这表明此时C3H6与NOx之间存在竞争氧化.在贫燃-富燃循环中,Rh/BaZrO3/γ-Al2O3的NSC几乎不变,这表明该催化剂对NO具有很好的氧化-还原循环性能.当在循环过程中混入0.01%SO2,对该催化剂的氧化-还原能力几乎无影响,这说明Rh/BaZrO3/γ-Al2O3催化剂还具有较强的抗硫性能. 相似文献