Ordered mesoporous Cu-Ce-O catalysts for CO preferential oxidation in H2-rich gases: Influence of copper content and pretreatment
Ordered mesoporous Cu-Ce-O catalysts for CO preferential oxidation in H2-rich gases: Influence of copper content and pretreatment
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DOI：
10.1016/j.apcatb.2014.01.011
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发表时间：
2014-06-25
影响因子：
22.1
通讯作者：
Schueth, Ferdi
中科院分区：
文献类型：
--
作者：
Gu, Dong;Jia, Chun-Jiang;Schueth, Ferdi
以有序介孔二氧化硅KIT-6为硬模板，合成了不同Cu含量的高有序介孔Cu- ce - o催化剂。负副本的细观结构顺序受Cu与Ce的比值的影响。通过XRD、HR-SEM、TEM和EDX分析发现，随着Cu浓度的增加，模板去除过程中CuO的浸出和高Cu浓度下的相分离导致纳米复合材料的有序介观结构退化。当Cu浓度低于40 mol%时，CeO2结构中的Cu离子可以取代ce离子。然而，最终材料中的铜浓度低于合成中使用的比例。在60000 mL h(-1) g(cat)（-1）的空速下测试了富h -2气体（PROX）中CO优先氧化活性。介孔催化剂的活性随Cu浓度的增加而增加，当Cu浓度大于20 mol%时，催化剂的活性趋于稳定。在160℃下，以Cu0.20Ce0.80O2为催化剂，CO转化率可达100%左右。在此条件下，CO的出口浓度可低至70 ppm。在低温条件下（60-80℃），CO2选择性可达100%。在介孔CeO2表面直接加载CuO会导致较大的CuO晶体和相应的低活性。研究了预处理气氛对活性的影响。氧化-还原-再氧化循环可以提高催化剂的催化活性。(c) 2014 Elsevier B.V.版权所有
Highly ordered mesoporous Cu-Ce-O catalysts with different Cu contents have been synthesized by using ordered mesoporous silica KIT-6 as a hard template. The mesostructural order of the negative replica is influenced by the ratio of Cu to Ce. Using XRD, HR-SEM, TEM and EDX analysis, it was found that the ordered mesostructures of the nanocomposites degenerate with increasing Cu concentration, due to CuO leaching during the template removal process and a phase separation at high Cu concentration. Cu ions can replace Ce-ion in the structure of CeO2 at Cu concentrations below 40 mol%. However, the Cu concentration in the final materials is lower than expected from the ratio used in the synthesis. The activity in preferential oxidation of CO in H-2-rich gases (PROX) was tested at a space velocity of 60,000 mL h(-1) g(cat)(-1). The activity of the mesoporous catalysts increases with the concentration of Cu and becomes stable for Cu concentrations higher than 20 mol%. A CO conversion around 100 % can be attained with Cu0.20Ce0.80O2 as catalyst at 160 degrees C. The exit CO concentration can be as low as 70 ppm under these conditions. The CO2 selectivity can reach 100% at low temperature (60-80 degrees C). Direct loading of CuO on the surface of mesoporous CeO2 leads to large CuO crystals and correspondingly low activity. The influence of the pretreatment atmosphere on activity was also studied. Oxidation-reduction-reoxidation cycling can improve the catalytic activity of the catalysts. (c) 2014 Elsevier B.V. All rights reserved.