有机金属化合物降低柴油机炭烟排放及其机理的研究

在直喷式柴油机上按自由加速法进行了柴油机炭烟排放试验，考察了8种有机金属化合物降低炭烟排放的效果，并对其作用机理进行了研究。实验表明，8种有机金属化合物均能有效降低炭烟排放，降烟效果顺序为二壬基萘磺酸钡>二茂铁>环烷酸铁>石油磺酸钡>环烷酸锰>环烷酸铜>环烷酸钡>环烷酸铈。在纯柴油中添加4‰二壬基萘磺酸钡时，降低炭烟排放40.7%；添加1‰二茂铁时，降低炭烟排放35.3%。试验还表明，有机结构影响有机金属化合物的降烟效果，同时影响着它在添加量上的感受性。炭烟的生成，主要与生成的乙炔（C2H2）和多环芳香烃（PAH）有关，而炭烟的氧化则与炭烟周围氧浓度和炭烟颗粒表面积有关。多数有机金属化合物本身携氧，能使燃油迅速分解生成CO，CO的增加使PAH明显减少，从而抑止炭烟的生成。茂型金属有机物能活化CO分子，进而有效抑止炭烟先导物的生成。     

稀土复合型柴油催化助燃剂的研制及应用

采用铈、铂的有机配合物及碳酸酯制备出一种稀土复合型柴油催化助燃剂.通过发动机台架试验,表明添加剂可有效降低碳烟PM和NOz排放,并且发动机热效率有所提高.     

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。     

柴油机尾气净化催化剂的最新研究进展

柴油机尾气排放的污染物已经引起了严重的环境污染问题,催化净化技术是柴油机尾气污染治理必不可少和最有效的处理技术之一,而高效催化剂的研制和开发是催化净化技术的核心.本文以柴油机尾气中最难处理的两种污染物NOx和碳烟颗粒(PM)的催化处理技术为主线,综述了NOx的催化还原(选择性催化还原(SCR)和贮存还原(NSR))催化剂、碳烟的催化燃烧催化剂、NOx和碳烟颗粒同时消除的催化剂及柴油机尾气四效催化剂的最新研究进展,并总结性地提出了目前该研究方向存在的主要问题和发展方向.     

铈基氧化物催化燃烧柴油机炭烟颗粒的性能及机理研究进展

随着环保法规的日益严格和人们环保意识的提高,柴油车尾气污染物中的炭烟颗粒对环境的严重污染引起了人们广泛的关注.利用催化净化技术实现炭烟颗粒的消除是目前最有效的途径之一,其中高活性催化剂的研发是决定该技术广泛应用的关键因素之一.近年来,铈基氧化物催化剂因其良好的氧化还原性能、适当的表面酸性以及较高的储/释氧容量而被广泛用于柴油机尾气炭烟颗粒的催化燃烧领域.研究铈基氧化物催化剂在炭烟催化燃烧反应高活性的本质,有助于了解炭烟颗粒催化燃烧过程的基本原理,为现有催化剂的优化和新型催化剂的设计提供科学指导.本文总结了近年来铈基氧化物催化剂材料在催化柴油机炭烟燃烧中的研究进展,主要包括单一氧化铈催化剂和稀土金属、过渡金属、碱(碱土)金属及贵金属改性的铈基氧化物催化剂.同时,对上述催化剂的反应机理进行了总结.最后,提出了铈基氧化物催化剂在催化柴油机炭烟燃烧中存在的问题并对其发展前景进行了展望.     

柴油机烟碳的微波加热燃烧 Ⅰ．柴油机烟碳的介电性能与微波加热特征

本文讨论了将新颖的微波加热技术应用于柴油机烟碳燃烧的可行性。通过研究柴油机烟碳和商品碳黑的组成和结构与介电性能的关系，以及观察它们在微波场中的加热和燃烧行为，发现柴油机烟碳的介电性和损耗性很适宜于使用微波进行加热燃烧。实验结果表明，在含氧量为１０％的模拟排气条件下，当微波入射功率逐渐增至９００Ｗ时，可使柴油机烟碳的烧却率达５０％。文中亦考察了一次燃烧产物中ＣＯ_２摩尔分率在燃烧过程中的变化。     

柴油机烟碳的微波加热燃烧

本文讨论了将新颖的微波加热技术应用于柴油机烟碳燃烧的可行性。通过研究柴油机烟碳和商品碳黑的组成和结构与介电的关系，以及观察它们在微波场中的加热和燃烧行为，发现柴油机烟碳的介电性和损耗性很适宜于使用微波进行加热燃烧。实验结果表明，在含氧量为１０％的模拟排气条件下，当微波入射功率逐渐增至９００Ｗ时，可使柴油机的烧却率达５０％。文中亦考察了一次燃烧产物中ＣＯ２摩尔分离在燃烧过程中的变化 。     

等离子体在同时去除NOx和碳烟催化反应中的作用

采用程序升温反应(TPR)技术,研究了等离子体辅助同时催化去除富氧柴油机尾气中NO_x和碳烟(soot)的反应特性.研究结果表明,等离子体提高了同时去除NO_x-soot的催化反应活性,降低了碳烟的燃烧温度,使碳烟起燃温度从300 ℃降到280 ℃,燃尽温度从425 ℃降到380 ℃;同时,等离子体辅助提高了NO_x转化为N₂的效率,使催化选择性从1.12％提高到1.53％.本文还分别研究了在NO和O₂的环境中,有或没有等离子体作用下,碳烟在催化作用下的去除特性.等离子体作用使得NO在和O₂共存、只有NO和只有O₂存在的各种条件下,碳烟的催化燃烧活性都有不同程度的提高,促进了N₂的生成.此外,本文也对等离子体辅助同时催化去除NO_x-soot的机理进行了探讨.     

柴油机烟碳的微波加热燃烧Ⅱ.载体陶瓷材料的影响

本文讨论了柴油机滤烟器基体材料堇青石和常用载体涂层材料对柴油机烟碳微波加热燃烧的影响。实验结果表明，陶瓷材料，尤其是滤烟器基体材料对微波的吸收能力远远低于柴油机烟碳。因此，当二者共存时，床层的温升速率主要取决于烟碳的含量。烟碳／载体比越高，燃烧越易起动，但是床层温升也越高。与纯烟碳燃烧相比，陶瓷物质的存在有利于降低燃烧产物中的ＣＯ分率。     

过渡金属-铈基复合氧化物的制备与碳烟燃烧催化性能

采用溶胶凝胶法制备了不同过渡金属TM(Fe,Co,Ni,Mn)-Ce复合氧化物,并经800℃水热处理20 h后得到老化样品。利用XRD,BET对样品结构进行了表征,并采用CO-TPR和TPO分别考察了样品的还原性能和碳烟催化燃烧活性。结果表明,复合氧化物通过过渡金属和铈离子的变价和协同作用,有效地提高了催化剂的碳烟燃烧催化活性。在催化剂-碳烟松散接触条件和含NO+O2气氛下,由于催化剂表面氧的活化和硝酸盐分解释放的NO2,Co-Ce和Mn-Ce具有良好的碳烟燃烧活性。催化剂-碳烟紧密接触和含O2气氛中的活性则与催化剂的比表面积成正比关系,并受活性氧释放能力的影响。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.