含锆、钙熔铁型氨合成催化剂的M?ssbauer谱

含锆催化剂;含钙催化剂;熔铁催化剂;含锆、钙熔铁型氨合成催化剂的M?ssbauer谱     

铁基超细粒子催化剂结构与还原行为的Mossbauer谱研究

铁基超细粒子催化剂具有优良的F －T反应性。本工作利用原位Mossbauer谱辅以XRD技术研究了含有钾助剂的F－T合成铁基超细粒子催化剂的结构与还原行为，考察了催化剂组成和第二金属组分（Mn,Zn,Mg）的影响。“纯”铁超细粒子催化剂在氢气中很容易经Fe3O4还原为零价铁。第二金属组分的引入，一方面了阻碍了催化剂的还原，另一方面稳定了Fe^2 的存在而使其成为还原的主要中间相，这有利于反应条件下形成类晶石结构的活性相。对于Fe-Mn催化剂，上述效应随锰含量的增加而更趋显著。铁基超细粒子催化剂在氢气中还原能力依“纯”Fe>Fe-Zn>Fe-Mn>Fe-Mg的顺序递减，这在一定程度上反映了铁与第二金属组分之间相互作用的强弱。     

水溶性膦配体络合金属催化剂的进展

均相催化剂与多相催化剂相比有许多优点,如在均相催化剂中,全部中心金属原子均参与构成活性种;具有确定均一的结构;催化剂浓度低,具有高活性、高选择性;反应条件温和;不存在扩散问题;传热易于解决等.但是,均相催化剂与产物的分离问题给工业生产带来了困难,特别是对产品沸点高的均相催化过程,显得更为突出,加之所用催化剂大多是贵重金属,因此,均相催化剂的分离回收一直是催化剂研究领域的一个热点.如均相催化多相化的研究,即通过高分子锚定,无机载体固定、双重固载及液相担载等方法,使均相催化剂多     

二甲醚水蒸气重整制氢的ZSM-5和Cu-Zn的复合催化体系（英文）

二甲醚水蒸气重整制氢反应是燃料电池理想的供氢方式之一.探讨了二甲醚水蒸气重整过程中的反应与反应、反应与传热的耦合协同效应.采用二甲醚水解催化剂ZSM-5（硅铝比为25）和甲醇水蒸气重整催化剂（Cu-Zn系列及商用Cu-Zn-Al催化剂）混合制得二甲醚水蒸气重整的复合催化剂.在固定床反应装置中评价了催化剂活性并对催化剂进行了透射电镜、X射线衍射及N2吸附表征.结果表明,复合催化剂的活性除了受催化剂组成和铜含量的影响外,还与Al和Zr的量有关.在Cu：Zn摩尔比为60：30时,Al和Zr的同时加入使催化剂中Cu晶粒分散最好,催化剂具有较高的低温活性,二甲醚在空速为4922ml/（g·h）和260℃下的转化率达到72%.     

高温煤气中氨的脱除：Ⅰ.氨催化分解催化剂的筛选

制备和筛选了１２ 种氨催化分解催化剂,所选催化剂包括Ｃｕ － Ｍｎ 基脱硫剂,Ｚｎ－ Ｔｉ 基脱硫剂,Ｆｅ 基催化剂及Ｎｉ 基催化剂四大类,其中Ｎｉ－２ 催化剂及Ｎｉ－ ３ 催化剂具有较高的转化率。然后对Ｎｉ－３ 催化剂进行了寿命试验,１００ｈ 内其活性基本维持不变;耐硫性实验表明Ｎｉ－３ 催化剂具有一定的耐硫性能,因而它是所选的最优催化剂     

制备条件对Ni在Al_2O_3表面上的分配形态及Ni/Al_2O_3体系催化加氢性能的影响

用比表面和孔体积测定、XRD和程序升温还原(TPR)方法研究了一系列不同制备条件对Ni在Al_2O_3表面上的分配形态及其对CO加氢反应催化性能的影响.实验发现,本文所用制备条件对催化剂的比表面、孔体积及孔径分布无显著的影响.浸渍时间愈长,催化剂上能在较低温度下还原的物种愈少,催化剂上CO的加氢活性愈低;在浸渍前对载体作室温抽空处理后制得的催化剂上,Ni在Al_2O_3表面是高度分散的,这一高度分散物种易于在低温下还原,使该催化剂具有很高的CO加氢活性和生成CH_4选择性;载体的抽空温度及对载体加热均对Ni物种形态及其分配、催化剂性能有明显影响.     

铜基催化剂上乙醇还原Nox的研究

铜基催化剂上乙醇还原Nox的研究;铜基催化剂;乙醇;Nox     

非晶态合金催化剂用于二甲基紫脲酸加氢反应

二甲基紫脲酸加氢反应;nicob/白炭黑催化剂;非晶态合金催化剂     

烯烃聚合钯催化剂研究进展

综述了烯烃聚合钯催化剂的研究进展,烯烃聚合钯催化剂的配体类型有膦配体、氮配体、碳配体、氧配体、氮-氧配体、膦-氧配体、氮-膦配体等。与齐格勒-纳塔催化剂和茂金属催化剂相比,烯烃聚合钯催化剂具有高催化活性、单活性中心和良好的分子剪裁性等优点,可在分子层次上实现烯烃聚合的分子设计与组装;与铁、钴、镍等后过渡金属催化剂相比,烯烃聚合钯催化剂具有反应条件较温和、催化活性和立体选择性较高的优势。     

手性有机分子催化剂在不对称催化中的应用

近三十年来,不对称催化研究获得了迅猛发展[1].按手性催化剂的种类分,一般可分为手性有机金属配合物催化以及路易斯酸、碱等手性有机分子催化.手性有机金属配合物催化剂在不对称还原、不对称氧化等官能团转化反应中的应用,已达到实用阶段;不使用金属的有机分子催化剂由于其对环境友好,也日益被重视,有机合成化学中十分重要的碳-碳键形成反应,如Aldol反应、Diels-Alder反应等,近年来发表了很多使用手性有机分子催化剂的成功的实例.早在1971年Wiechert[2]等人曾以脯氨酸为催化剂,用于分子内不对称醇醛缩合(Aldol)反应,1974年Hajos[3]等…     

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.     

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.     

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.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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.