燃油种类对汽车尾气净化催化剂性能的影响

 分别对燃用普通汽油和10%乙醇/汽油(E10)混合燃料的CG125型摩托车进行了 10000 km路试,比较了不同种类燃油的排放特性,并采用X射线光电子能谱,扫描电镜和电子探针考察了催化剂的积炭物种与积炭分布. 结果表明,安装催化转化器后,燃用这两种燃料的摩托车尾气排放均能达到欧盟第二阶段排放标准,但催化转化器对E10尾气的净化效果明显低于普通汽油. 燃用这两种燃料的摩托车尾气净化催化剂表面均存在积炭,径向不同部位积炭量顺序为中心层＞过渡层＞边缘层. 燃用普通汽油时,催化剂表面积炭的碳物种主要是CHx,而燃用E10时的碳物种是(CH)xO. 这说明要合理地设计催化转化器才能使尾气均匀地径向分布,而且必须针对燃油种类匹配适宜的催化剂.     

NOx催化的甲烷气相氧化反应

 考察了没有固体催化剂时NOx对甲烷气相氧化的催化作用，并用原位红外光谱研究了CH4－O2－NOx体系随温度的变化．实验结果表明，NOx对甲烷气相氧化有很高的催化活性．在20％CH4－10％O2体系中加入0．05％～0．2％的NO后，反应温度可降低200～300℃，在650～700℃下反应时，CH4转化率和CO选择性可分别达到38％和90％，产物中的n（H2）／n（CO）比为0．4～0．7．反应产物中可观察到有甲醛、甲醇和乙烯等，通过改变反应条件可以控制各组分的相对浓度．     

整体式Pd/La_2O_3-Al_2O_3和Pd/CeO_2-ZrO_2-Y_2O_3催化剂上汽油车尾气净化性能的比较

采用共沉淀法制备了耐高温高比表面积的La2O3-Al2O3(LA)材料和CeO2-ZrO2-Y2O3(CZY)储氧材料,并用浸渍法制备了整体式Pd/LA和Pd/CZY汽油车尾气净化三效催化剂,考察了它们的三效催化性能和空燃比性能,并单独通过水煤气变换和CO氧化反应性能的考察,探讨了两种催化剂空燃比窗口扩大的原因.结果表明,Pd/CZY催化剂三效窗口明显较宽,且催化氧化CO的性能明显更优;对于CO+NO反应,Pd/CZY催化剂的活性较高.当反应中逐步通入O2后,抑制了该反应的进行,但CO氧化的转化率升高,而NO转化率降低,直至CO+NO反应完全被抑制,表明CO氧化反应对于抑制催化剂在NO贫燃方向的窗口具有一定的作用.另外,Pd/CZY催化剂上对于水煤气变换反应性能明显优于Pd/LA催化剂,在一定温度下逐步通入O2后,不会抑制水煤气变换反应的发生;当逐步通入NO时,可以促进水煤气变换反应的进行,表明Pd/CZY催化剂在富燃时对扩展CO转化窗口的性能明显优于Pd/LA催化剂.     

La1-xCexCoO3系钙钛矿型催化剂应用于柴油机尾气净化催化性能的研究

采用低温燃烧法制备了Ce4+部分取代La3+的La1-xCexCoO3系钙钛矿型复合氧化物催化剂，用XRD、TGA、SEM和化学分析等方法对催化剂的组成、结构等进行了表征。利用程序升温反应（TPR）技术，对催化剂应用于柴油机常规排放物中的微粒（PM）、碳氢化合物（THC）、氮氧化合物（NOx）的催化脱除性能进行了研究。结果表明，Ce4+部分取代La3+，催化剂表面氧空位浓度增加，同时形成Co3＋-Co2+共存体系，催化剂对THC、NOx催化活性显著提高,且稳定性良好。但Ce4+的掺杂并没有提高催化剂对PM的催化活性。     

H2O、CO2组分对NOx存储-还原性能的影响

NOx存储-还原技术是控制汽车稀燃NOx排放的重要手段之一,在汽车尾气中H2O、CO2组分含量均相对较高,有必要弄清这些组分对NOx存储-还原特性的影响。论文以MnOx改性Pt/Ba/Al2O3催化剂为研究对象,评价在不同气氛下的NOx存储能力和催化还原性能。结果表明：CO2、H2O组分均抑制催化剂的NOx存储性能,H2O的抑制作用主要表现在低温区,CO2抑制NOx存储的现象在高温区更为显著。CO2对NOx存储速率的抑制作用较H2O更为明显,且其NOx存储速率随着温度的升高表现的差异性更为明显。对于NOx催化还原过程,CO2、H2O或CO2 H2O添加均导致N2选择性降低,其N2选择性按CO2 > H2O > CO2 H2O的顺序降低。     

甲基叔丁基醚裂解制备高纯度异丁烯

制备了一系列用于甲基叔丁基醚（MTBE）裂解制异丁烯反应的硅酸铝催化剂，评价了其反应活性和选择性，用X光衍射（XRD）、物理吸附、傅立叶变换红外（FT-IR）等技术对催化剂结构性质进行表征。结果表明，添加合适的助剂、适宜的温度下焙烧有助于MTBE裂解制异丁烯硅酸铝催化剂的性能改善和活性提高。在催化剂的物化性质中，与活性关系较密切的是催化剂的比表面积、总酸量和B酸与L酸的比值。同时发现，一种添加助剂并经过特殊处理的催化剂WVI，在常压、WHSV为2 h－1条件下，反应温度从220 ℃提高到360 ℃，累计时间达3 840 h时，MTBE转化率可达99.9%，异丁烯选择性可维持在99%。     

La4BaCu5O13+δ的A,B位复合掺杂与三效催化活性研究

运用改进的柠檬酸络合自燃法合成出在LmBaCu5013＋δ的A，B位复合掺杂改性的类钙钛矿化合物La3SrBaCu4CoO13＋δ，考察了柠檬酸与金属硝酸盐的摩尔比和成胶温度等对材料制备的影响，并通过XRD，SEM和BET等测试手段对材料的物相结构、显微形貌和比表面积进行了基本的分析；测试了材料的尾气净化三效催化性能，结果表明，所制备的材料具有良好的尾气净化三效催化活性，在空燃比为14．6时，其对CO，HC和NOx的催化转化效率分别达到了100％，92％和90％。     

用Pr修饰的(Ce-Zr)O2固溶体在三效催化剂中的作用

采用溶胶－凝胶法制备了三效催化剂助剂（Ce-Zr)O2,(Pr-Ce-Zr)O2和（Pr-Zr)O2，并对它们进行了XRD，EXAFS和BET比表面的测定，采用H2的程序升温还原（TPR）表征该类助剂的还原特征，以考察此类含有镨的混合氧化物作为三效催化剂储氧组分的可能性。在≥800℃高温时，（Pr-Zr)O2形成了立方相固溶休，并且变得更容易被还原，含少量Pr的三元固溶体（Pr-Ce-Zr)O2在其还原过程中起着重要的作用，也具有易被还原的重要特性，测量了含有Pt,Pd和Rh的三次催化剂活性，即固定反应气氛组成（S＝1.00）时CO，C3H6和NOx转化的起燃温度。结果表明，在（Ce-Zr)O2固溶体中加入少量的镨可使得C3H6和NOx转化的起燃温度降低，所有含镨的催化剂对NOx转化均表现出较高的活性，并且在富氧区（S≥1.00）具有更大的S值宽度。     

多段微通道负载型钯催化剂上天然气预混催化燃烧的研究

制备了一系列用钡、镧、铈等氧化物进行改性的Pd／RExOγ·γ-Al2O3,堇青石蜂窝催化剂,在自行设计的催化燃烧实验平台上进行了天然气催化燃烧实验。研究了钯含量、催化剂床层数、功率对天然气催化燃烧特性的影响。结果表明,当钯含量为0.5％时催化剂具有最好的催化燃烧性能。在空燃比为12-16范围内,燃烧器尾气中NOx含量低于5×10^-6V/V,CO,Hc排放低于10×10^-6V/V。催化剂床层数对催化燃烧的温度峰值以及尾气中NOx含量影响不大,但明显利于降低HE,CO的排放。     

富氧条件下Ag/Al2O3和Cu/Al2O3组合催化剂催化C3H6选择性还原Nox的性能

 在全自动催化剂活性评价装置上,考察了富氧条件下Ag/Al2O3和Cu/Al2O3两种催化剂上催化丙烯还原NOx的活性. 在实验温度范围(200～650 ℃)内,Ag/Al2O3具有 优异的催化丙烯选择性还原NOx的活性,但同时有大量副产物CO形成. Cu/Al2O3选择性催化丙烯还原NOx的活性不高,却能有效促进CO的氧化. 在无水条件,Ag/Al2O3-Cu/Al2O3组合体系具有与Ag/Al2O3相似的脱除NOx活性,同时使CO在300 ℃以后几乎完全转化. 在10%水蒸气存在的情况下,Ag/Al2O3-Cu/Al2O3组合催化剂脱除NOx的活性下降,但水蒸气对CO转化率的影响不大.     

金属-ZSM-5/堇青石整体式催化剂上稀燃汽车尾气的净化

 在原位合成的ZSM-5/堇青石整体式样品基础上制备了几种金属(Cu, In或Ag)改性的ZSM-5/堇青石催化剂,并将其应用于稀燃发动机尾气的净化. 结果表明, Cu-ZSM-5/堇青石催化性能最好,尾气中的三种主要污染物NOx, CO和HC可以同时得到净化. 用微量(0.02%)贵金属(Pd, Rh或Ir)对Cu-ZSM-5/堇青石进一步改性,所得催化剂对CO的净化能力大大增强,保持高NOx转化率的温度窗口也大大加宽,因而该催化剂在稀燃汽车尾气净化方面具有潜在的应用前景. 微量贵金属对Cu-ZSM-5/堇青石催化剂的改性作用也在文中进行了讨论.     

High resolution gas chromatographic determination of the atmospheric reactivity of engine-out hydrocarbon emissions from a spark-ignited engine

The reactivities of engine-out exhaust hydrocarbon (HC) emissions in photochemical smog formation have been determined for three fuels (isooctane, an aromatic blend, and a gasoline) in a single-cylinder, spark-ignited engine. High resolution capillary GC was used to determine the mole fractions of the exhaust hydrocarbon species. Temperature programmed chromatography on a single capillary column was sufficient to separate the major exhaust species. A library of approximately 160 hydrocarbon species was used to identify typically 90–95 % of the HC species present. GC-MS was used selectively to verify peak assignments. The effect of engine operating parameters (fuel-to-air ratio, spark timing, and speed) on reactivity was examined. Engine operating parameters affect both total emissions [g/mile] and the specific atmospheric reactivity [g ozone/g HC emissions] of these emissions. Changing the operating parameters to control total emissions may not be as effective as expected in controlling the total reactivity [g ozone/mile] of the emissions because the specific reactivity can also change simultaneously. Effects of changes in operating parameters differ significantly as the type of fuel is varied. The ability to measure exhaust hydrocarbon species emissions accurately and quickly will increase in importance as reactivity-based emissions standards come into widespread use.     

A New Spark Plug to Improve the Performances of Combustion Engines: Study and Analysis of Unburned Exhaust Gases

The ignition sparks provided by the conventional spark plug do not always ensure a fast and complete combustion of the hydrocarbon-air mixture. For this reason, we offer a new type of plug with a double spark using two simultaneous discharges generated by a pulsed high voltage-power supply. This work presents the comparison of two spark plugs, a classical one and a double spark plug, by analyzing the unburned hydrocarbon gases from the exhaust pipe of the engine. For a first gasoline engine, we measure the oxygen concentration in the exhaust gases with a lambda probe and the unburned hydrocarbon by the use of GC–MS coupled with SPME extraction technique. We can observe a clear decrease of total unburned hydrocarbon (THC). For a second motor test bench, powered with propane, we complete measures in function of air/fuel ratio of the THC, NO_x, CO₂ and CO. These results confirm that we obtained a better combustion especially for leaner mixtures.     

Method for determination of methyl tert-butyl ether in gasoline by gas chromatography

A simple method for the determination of methyl tert-butyl ether (MTBE) in gasoline has been developed. The separation of MTBE from other analytes was controlled by the use of gas chromatography–mass spectrometry in the full scan mode using the characteristic primary, secondary and tertiary ions m/z 73, 57 and 43. The sample mass spectrum did not show any superimposition of other analytes. The separation from the common gasoline component 2-methylpentane was sufficient for reliable quantitation. An application of the developed conditions using gas chromatography with flame ionization detection was performed by the analysis of regular, euro super, super premium unleaded and ‘Optimax’ gasoline from petrol stations in the area of Frankfurt/Main, Germany. Regular unleaded gasoline shows an average MTBE content of 0.4% (w/w), whereas the MTBE content in euro super gasoline varies between 0.4 and 4.2% (w/w). The blending of MTBE to super premium has increased from 8.2% (w/w) in 1998 to 9.8% (w/w) on average in 1999. The recently introduced gasoline ‘Optimax’ shows an average MTBE content of 11.9% (w/w). The presented method might also be used for the analysis of other ethers, such as ethyl tert-butyl ether, which requires the use of another internal standard.     

液相氧化羰基化合成碳酸二乙酯的新型催化体系CuCl/1,10-菲罗啉/N-甲咪唑

Diethyl carbonate (DEC) is one of the important green chemicals widely used for organic synthesis because of its various functional groups. DEC is a better octane blending fuel, and has more oxygen in the molecule than methyl tert-butyl ether (MTBE), 40.6% versus 18.2%, which reduces emissions from gasoline and diesel engine. For these reasons many studies on the production of DEC have been extensively carried out.     

Method for determination of methyl tert-butyl ether in gasoline by gas chromatography

A simple method for the determination of methyl tert-butyl ether (MTBE) in gasoline has been developed. The separation of MTBE from other analytes was controlled by the use of gas chromatography–mass spectrometry in the full scan mode using the characteristic primary, secondary and tertiary ions m/z 73, 57 and 43. The sample mass spectrum did not show any superimposition of other analytes. The separation from the common gasoline component 2-methylpentane was sufficient for reliable quantitation. An application of the developed conditions using gas chromatography with flame ionization detection was performed by the analysis of regular, euro super, super premium unleaded and ‘Optimax’ gasoline from petrol stations in the area of Frankfurt/Main, Germany. Regular unleaded gasoline shows an average MTBE content of 0.4% (w/w), whereas the MTBE content in euro super gasoline varies between 0.4 and 4.2% (w/w). The blending of MTBE to super premium has increased from 8.2% (w/w) in 1998 to 9.8% (w/w) on average in 1999. The recently introduced gasoline ‘Optimax’ shows an average MTBE content of 11.9% (w/w). The presented method might also be used for the analysis of other ethers, such as ethyl tert-butyl ether, which requires the use of another internal standard.     

Sputtered nano-cobalt on H-USY zeolite for selectively converting syngas to gasoline

Selectively converting CO and H2 to gasoline product(isoparaffin and olefin) in one step still remains a great challenge. We demonstrate effective H-USY zeolite supported nano-cobalt bifunctional catalysts for this catalytic reaction, which are prepared by the novel physical sputtering process. Particles of the sputtered cobalt exist in nano-level and are well-dispersed on acid USY zeolite. Easy activation of the loaded nano-cobalt is also achieved in a low-temperature hydrogen reduction atmosphere. In the tandem catalytic reaction, the sputtered bifunctional Co/USY catalyst exhibits a much higher CO conversion and higher isoparaffin selectivity than the conventional impregnated one. Compared with H-Mor, H-Beta and other zeolites supported catalysts, H-USY zeolite supported cobalt catalyst shows the clearest promotional effect on the activity of FischerTropsch synthesis. The described synthesis herein provides a new pathway to solve the problem caused by the strong metal-support interaction(MSI) in heterogeneous catalysis.     

燃料特性对车用柴油机有害排放的影响

研究了车用柴油机燃用不同品质燃油时,其排气烟度、颗粒PM、氮氧化物NO_x、碳氢HC和一氧化碳的排放特性,采用了五种不同硫含量、芳烃含量和十六烷值的柴油,进行了发动机台架实验和模拟整车NEDC循环实验。结果表明,随着燃油硫含量的减少,柴油机排气烟度、HC、CO、SO₂排放有所下降;模拟整车NEDC循环的PM排放显著降低;NO_x排放的变化幅度很小。随着燃油芳烃含量的降低,柴油机排气烟度、PM、NO_x、HC、CO排放的降幅显著。随着燃油十六烷值的升高,柴油机的排气烟度大都呈持续下降趋势;PM、HC排放显著降低;NO_x、CO排放的变化幅度较小。     

F-T柴油在直喷式柴油机中燃烧与排放特性的研究

煤通过Fischer-Tropsch (F-T)合成可得到十六烷值高、硫和芳香烃质量分数极低的F-T柴油。研究分析了未作改动的单缸直喷式柴油机燃用F-T柴油时的燃烧和排放特性。结果表明,与燃用0号柴油相比,燃用F-T柴油时的滞燃期平均缩短18.7%,预混燃烧放热峰值降低26.8%,扩散燃烧放热峰值较高,燃烧持续期相当。燃用F-T柴油时的最高燃烧压力略低,最大压力升高率显著下降,机械损失和燃烧噪音较小,燃油消耗率和热效率都得到显著改善。燃用F-T柴油可同时降低CO、HC、NOx和炭烟排放,其中NOx和炭烟分别平均降低16.7%和40.3%。研究表明,F-T柴油是柴油机良好的清洁代用燃料。