Ni基催化剂催化燃油重整耦合选择性催化还原NO_x反应  

Fuel reforming over Ni-based catalysts coupled with selective catalytic reduction of NO_x

作　　者：赵娇娇[1] 余运波[1] 韩雪[1] 贺泓[1] 

机构地区：[1]中国科学院生态环境研究中心,北京100085

出　　处：《催化学报》2013年第7期1407-1417,共11页

基　　金：国家自然科学基金(21177142);国家重点基础研究发展计划(973计划;2010CB732304);国家高技术研究发展计划(863计划;2013AA065301)~~

摘　　要：分别以La2O2CO3,CeO2,ZrO2和Al2O3为载体,采用浸渍法制备了Ni基重整催化剂,并以正十二烷模拟车载燃油进行催化重整反应以同时制备小分子碳氢化合物(HCs)和H2,考察了其在4wt%Ag/Al2O3上选择性催化还原(HC-SCR)氮氧化物(NOx)的性能.采用N2吸附-脱附、X射线粉末衍射、H2程序升温还原和热重等手段对Ni基催化剂进行了表征.结果表明,随着重整催化剂氧化还原性能增强,产物中H2浓度增加,可参与SCR反应的HCs含量减少,从而导致重整-SCR耦合体系上NOx净化活性温度窗口向低温移动,NOx最高转化率降低.Ni/ZrO2+Ag/Al2O3耦合体系中H2/HCs符合SCR反应所需的最优比例,在柴油车典型排气温度范围内表现出良好的NOx净化能力.同时,在Ni/ZrO2+Ag/Al2O3耦合体系上考察了其燃油重整-SCR的活性稳定性.结果显示,重整催化剂的耐久性有待进一步提高.La2O2CO3, CeO2, ZrO2, and Al2O3 supported Ni catalysts were prepared by an impregnation method and employed for reforming of n‐dodecane to simultaneously produce low molecular weight hydrocarbons （HCs） and H2 . These reforming products served as reductants and promoters for the selective catalytic reduction （SCR） of NOx over Ag/Al2O3. N2 adsorption‐desorption, X‐Ray powder diffraction, H2 temperature programmed reduction, and thermogravimetric analysis were performed for Ni‐based catalysts. It was shown that an increase in the redox performance of Ni‐based catalysts enhanced the H2 production from fuel reforming but decreased the amount of HCs available for further SCR reaction. The temperature window for NO x removal using the coupled system shifted to lower temperatures at the expense of the NO x conversion. An optimal ratio of H2/HCs was achieved using a Ni/ZrO2＋Ag/Al2O3 dual catalyst system, which exhibited high activity for NOx conversion at typical diesel exhaust temperatures. Studies on the durability and performance of this Ni/ZrO2＋Ag/Al2O3 coupled system were also performed, and the results showed that the lifetime of the reforming catalyst may limit the system and requires further improvement.

关 键 词：燃油重整 镍基催化剂 氮氧化物 选择性催化还原 银 氧化铝 

分 类 号：O643.32[理学—物理化学]