锂镍钴复合氧化物锂离子电池正极材料的研究

本文报道了以碱式碳酸镍、碱式碳酸钴和碳酸锂为原料 ,柠檬酸为络合剂的新溶胶凝胶法制备复合锂镍钴氧化物锂离子电池正极材料 .氧气流中制备的LiNi0 .8Co0 .2 O2 具有高的循环容量 (～ 190mAhg 1)     

钙钛矿结构B位掺杂化合物LaCO1-xFexO3的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型LaCo1-xFexO3系列化合物，使用XRD、XPS、红外和紫外等手段对其进行了表征和测定，并测定了其对活性艳红水溶性染料脱色的光催化活性．实验结果表明在B位掺杂Fea 后使LaCoO3光催化活性明显提高，当x=0．05时，即LaCo1-xFexO3的光催化活性最佳。     

ABO3型钙钛矿结构的可见光光催化剂LaCo0.5Ti0.5O3的设计与合成

采用溶胶-凝胶法在较低温度条件下设计合成了新型的具有ABO3型钙钛矿结构的三元金属复合氧化物LaCo0.5Ti0.5O3. 通过TG-DTA, XRD, XPS, UV-Vis DRS等测试技术和可见光光催化活性测试对其进行了表征. 结果表明, 与LaCoO3和La2Ti2O7相比, LaCo0.5Ti0.5O3样品表现出相对较高的可见光光催化活性, 并且合成温度较低. 这是由于原料中的Co2+和Ti4+离子通过电荷补偿作用使产物B位的两种金属均以+3价氧化态分布所致.     

Zn掺杂的LaCoO3钙钛矿用于乙醇水蒸气重整制氢反应

利用一步柠檬酸络合法合成了钙钛矿LaCo1-xZnxO3(x=0,0.05,0.1,0.2,0.3,0.5),并将其用于乙醇水蒸气重整反应.利用X射线衍射、程序升温还原和X射线光电子能谱对催化剂进行了表征.结果表明,Zn的加入不利于形成LaCo1-xZnxO3钙钛矿结构,当x≥0.1时产生了一些分离相.新鲜LaCo0....     

Ce-Zr-O固溶体的制备和表征

采用硝酸盐直接分解法、共沉淀法、苹果酸溶胶 凝胶法和柠檬酸溶胶 凝胶法制备了Ce Zr O复合氧化物并进行了表征。溶胶 凝胶法制得的Ce Zr O为立方的Ce0 .5Zr0 .5O2 复合氧化物 (其中少量具有立方性质的t″相 ) ,而直接分解和共沉淀法制得的是由立方Ce0 .8Zr0 .2 O2 和四方Ce0 .2 Zr0 .8O2 固溶体组成的复合氧化物。不同制备方法制得的样品由于物相组成不同 ,还原性能也有较大差别。差热分析和X射线衍射分析结果表明 ,凝胶在燃烧的同时生成了Ce0 .5Zr0 .5O2 固溶体。     

BaCe0.8Ln0.2O2.9(Ln=Gd, Sm, Eu)固体电解质的低温制备及其燃料电池性质

利用溶胶 凝胶法低温合成了BaCe0 .8Ln0 .2 O2 .9(Ln =Gd ,Sm ,Eu)固体电解质 ,X射线粉末衍射表明 90 0℃即形成正交钙钛矿结构 ,较高温固相反应合成温度降低了约 6 0 0℃ .测定了样品的阻抗谱和电导率 ,研究了其导电机理 ,溶胶 凝胶法合成可减小或消除固体电解质的晶界电阻 ,80 0℃时BaCe0 .8Gd0 .2 O2 .9的σ =7.87× 10 -2S·cm-1,以它为电解质的氢氧燃料电池开路电压接近 1V ,最大输出功率密度为 30mW·cm-2 .     

BaAl12O19:Tb荧光粉的制备及发光性能的研究

以柠檬酸为络合剂,采用溶胶-凝胶法合成BaAl12O19:Tb荧光粉,通过X射线衍射(XRD)和荧光分光光度计对荧光粉的晶体结构和荧光性能进行检测.XRD分析结果表明:采用溶胶-凝胶制备工艺合成BaAl12O19:Tb),在1300℃可以得到BaAl12O19纯相,掺杂浓度在0.5%～5mol%Tb3 均可取代Ba2 得到纯相的Ba1-xAl12O19:Tbx.样品在240 nm波长激发下,有380,415,440,489,543,585和621nm的一系列窄带发射峰,属于Tb3 的5D3-7Fi(i=6,5,4)和5D4-7Fi(j=6,5,4,3)跃迁发射.其中以位于543 nm波长发射峰最强,489nm波长峰次之,其他均较弱.经1300℃晶化2 h,Tb3 的掺杂浓度为2mol%时,得到的荧光粉体发光强度最好.     

大比表面积γ-Al2O3的制备及辅助剂蔗糖的用量对γ-Al2O3 织构的影响

 在由硝酸铝经氨水沉淀制备氧化铝的过程中,用蔗糖作为辅助剂制得了具有大比表面积的γ-Al2O3,并考察了蔗糖加入量对γ-Al2O3织构的影响. 将硝酸铝和蔗糖共溶于水,滴加氨水至Al3+全部沉淀(pH=5.2),所得沉淀连同母液一起在80 ℃水浴中搅拌得到溶胶,将溶胶于110 ℃失水后即得凝胶. 凝胶进一步失水后发生燃烧得到含碳的前体,再经600 ℃焙烧即得到γ-Al2O3(比表面积可达350 m2/g左右). 利用差热-热重分析、元素分析、氮吸附-脱附等温线、X射线粉末衍射和透射电子显微镜对前体及 γ-Al2O3 样品进行了表征. 结果表明,γ-Al2O3不但具有大的比表面积,而且孔径较小,分布较为集中. 通过改变蔗糖的用量,还可在一定程度上对γ-Al2O3的比表面积和孔结构等进行调控.     

Co-Cu/SiO2催化剂的表征

用溶胶-凝胶法制备了Co-Cu/SiO2系列的担载型催化剂,采用SBET、TPR、XRD、O2滴定等技术对该催化剂进行了研究,并考察了催化剂在F-T合成反应中的催化性能.结果表明,样品的SBET较大,Co和Cu组分均很好分散;Cu2+的加入使得Co更易于被氢气还原,Co是经由Co3+→Co2+→Co0的还原过程,Cu的还原为Cu2+→Cu0;Cu2+的引入使得样品中钴的还原度增大,对F-T合成的催化性能有了一定的改善.     

La掺杂钛酸钙光催化剂在可见光下分解水制氢的影响因素

以柠檬酸为络合剂,采用溶胶-凝胶法制备了钙钛矿型光催化剂Ca_{0. 99}La_{0. 01}TiO₃,利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱仪(UV-Vis DRS)等对光催化剂材料进行了表征,并考察了N掺杂对光催化剂催化效果的影响,探究了可见光条件下,Ca_{0. 99}La_{0. 01}TiO_3-xN_x在不同Pt负载量及不同种类牺牲剂中光催化分解水的产氢量,并进行相关荧光猝灭分析.结果表明,在可见光条件下,Pt负载量为1%且掺杂N的钙钛矿光催化剂在Na₂SO₃/Na₂S作为牺牲剂时,光催化分解水的产氢量最高.     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.