CAJ | 학술논문

为了验证 NSR 催化剂对柴油机 NOx 排放的存储还原性能，该文采用浸渍法制备了一系列 NSR 催化剂：xCe(25-x)Ba/γ-Al2O3（x为质量分数，且x=8～12）和Pt10Ce15Ba/γ-Al2O3催化剂，并利用X射线衍射、扫描电子显微镜、能谱仪和透射电子显微镜对其性能进行表征；通过台架试验，研究了10Ce15Ba/γ-Al2O3和 Pt10Ce15Ba/γ-Al2O3催化剂对NOx排放的存储还原性能。结果表明，BaO和CeO2的粒径变化范围为5～20 nm。随着x值增加，CeO2晶粒尺寸变大且分散性变差；当x=10时，BaO晶粒尺寸细小且分散性最好。当柴油机负荷低于50%时，10Ce15Ba/γ-Al2O3催化剂对NOx主要以吸附为主，NOx脱除率最高达80%；当柴油机负荷高于50%时，NOx开始脱附并被还原成N2，NOx脱除率最高为60%。与10Ce15Ba/γ-Al2O3催化剂作用相比，Pt10Ce15Ba/γ-Al2O3催化剂对NOx的吸附和脱除性能较好，其中柴油机负荷低于50%时，NOx脱除率接近100%，柴油机负荷高于50%时，NOx脱除率最高为75%。研究结果对NSR催化剂的开发以及在排放后处理领域的应用具有指导意义。
위료험증 NSR 최화제대시유궤 NOx 배방적존저환원성능，해문채용침지법제비료일계렬 NSR 최화제：xCe(25-x)Ba/γ-Al2O3（x위질량분수，차x=8～12）화Pt10Ce15Ba/γ-Al2O3최화제，병이용X사선연사、소묘전자현미경、능보의화투사전자현미경대기성능진행표정；통과태가시험，연구료10Ce15Ba/γ-Al2O3화 Pt10Ce15Ba/γ-Al2O3최화제대NOx배방적존저환원성능。결과표명，BaO화CeO2적립경변화범위위5～20 nm。수착x치증가，CeO2정립척촌변대차분산성변차；당x=10시，BaO정립척촌세소차분산성최호。당시유궤부하저우50%시，10Ce15Ba/γ-Al2O3최화제대NOx주요이흡부위주，NOx탈제솔최고체80%；당시유궤부하고우50%시，NOx개시탈부병피환원성N2，NOx탈제솔최고위60%。여10Ce15Ba/γ-Al2O3최화제작용상비，Pt10Ce15Ba/γ-Al2O3최화제대NOx적흡부화탈제성능교호，기중시유궤부하저우50%시，NOx탈제솔접근100%，시유궤부하고우50%시，NOx탈제솔최고위75%。연구결과대NSR최화제적개발이급재배방후처리영역적응용구유지도의의。
The objective of the present study was to investigate the removal characteristics of NOxfrom the practical diesel engine exhaust over NOx storage and reduction (NSR) catalysts. A series ofxCe(25-x)Ba/γ-Al2O3(x=8%-12%, 25-x=17%-13%) and Pt10Ce15Ba/γ-Al2O3 NSR catalysts were prepared by an incipient wetness method. The effect of metallic Ce and Ba on their microstructure and catalytic properties was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and Transmission Electron Microscope (TEM) analysis. It was found from the catalyst characteristic with thexCe(25-x)Ba/γ-Al2O3catalysts that the size of BaO became smaller and dispersed better when the value of x increasing from 8 to 10, while the size of BaO were larger and the dispersion were getting worse when the value ofx increasing from 10 to 12. The size of BaO was smallest and the dispersivity of BaO was good when the value ofx was 10. TEM characterizations of 10Ce15Ba/γ-Al2O3catalyst indicated that the diameter range of CeO2andBaO was from 5 nm to 20 nm. According to the results of analysis, the 10Ce15Ba/γ-Al2O3and Pt10Ce15Ba/γ-Al2O3 catalysts were chosen to be coated on cordierite honeycomb ceramic device by an incipient wetness method. Then the catalytic activity of the 10Ce15Ba/γ-Al2O3and Pt10Ce15Ba/γ-Al2O3 catalysts for removal of NOx was characterized based on bench tests. In order to facilitate the systematic study of the performance of 10Ce15Ba/γ-Al2O3and Pt10Ce15Ba/γ-Al2O3 catalysts on NOxremoval from diesel engine exhaust, and reduce its impact on the performance of diesel engine and the structure reformation of exhaust system, the experimental research on NOx removal with NSR technology by the bypass way was carried out. The diesel engine was operated at the revolution of 2400 r/min and the engine load was 10%, 25%, 50%, 75% and 100%. The results showed that NOxwas stored as nitrites or nitrates on the storage components of 10Ce15Ba/γ-Al2O3catalyst with engine load less than 50%, and the maximum conversion rate of NOxover 10Ce15Ba/γ-Al2O3catalyst was up to 80%. With the engine load more than 50%, previously adsorbed nitrate species started to decompose and the NOx species were reduced to N2 by CO, HC or other reducing agent from practical diesel engine exhaust on the surface of 10Ce15Ba/γ-Al2O3catalyst, and the maximum conversion rate of NOx over 10Ce15Ba/γ-Al2O3catalyst was up to 60%. The possible reason was that the performance of NOx reduction was improved due to Ceria. In comparison with 10Ce15Ba/γ-Al2O3catalyst, Pt10Ce15Ba/γ-Al2O3catalyst showed better activity for NOx storage and reduction. With the engine load less than 50%, the maximum conversion rate of NOxover Pt10Ce15Ba/γ-Al2O3 catalyst was close to 100%, and the maximum conversion rate of NOx over Pt10Ce15Ba/γ-Al2O3catalyst was up to 75% with engine load more than 50%, which can be included that the NOx storage and reduction performance was greatly improved by adding Pt. The experimental results can provide a reference for optimum design and application of NSR catalyst in the field of diesel exhaust after-treatment system.