用可溶性催化剂合成顺式聚丁二烯的研究——Ⅱ.用钴化合物-烷基铝作催化剂

用各种钴化合物与烷基铝组成催化体系聚合丁二烯,研究其催化活性以及对高聚物链结构的影响,试验结果表明: 1.卤化钴呲啶络合物,有机酸钴盐呲啶络合物、乙酰基丙酮合钴等外轨型钴络合物均能与(i-C_4H_9)_2AlCl,(C_2H_5)_2AlCl,(C_2H_5)_2AlBr组成高活性催化体系,聚合所得到的高聚物的链结构,顺式-1,4含量大于92％,但都不能与(C_2H_5)_2AlI组成定向催化剂。 2.用内轨型的钴络合物与(i-C_4H_9)_2AlCl,(C_2H_5)_2AlCl,(C_2H_5)_2AlBr,组合为催化剂时,对高聚物的链结构没有影响,但其活性比外轨型钴络合物差得多。 3.当一卤代二烷基铝上卤素改变时,所得高聚物平均分子量的大小变化的顺序是Cl>Br>I。 4.在适当的水量存在下,(i-C_4H_9)_3Al或C_2H_5AlCl_2始能与CoCl_2·4C_5H_5N组成高活性的定向催化剂。     

聚铝氨烷-铂合物的制备及其催化加氢和氧化性能的研究

近十几年来,已有很多关于高分子金属络合物催化剂的文献报导,但几乎全都是属于有机高分子金属络合物催化剂的研究.在这些催化剂中,配位体的配位原子如氮、硫和磷都是与碳原子直接相连接的.最近,我们研制了一种新的无机高分子催化剂,即二氧化硅为载体的聚铝氨烧-铂络合物.在这个络合物中,配位氮原子是与铝原子相键连的. 二氧化硅为载体的聚铝氨烧-铂络合物(简称为Al-N-Pt)的合成方法如下:     

水/有机两相体系中单萜烯烃的氢甲酰化反应

考察了水溶性铑膦络合物RhCl(CO)(TPPTS)2(TPPTS为间-三苯基膦三磺酸钠)在水/有机两相体系中对不同单萜烯的氢甲酰化反应的催化性能.结果表明,添加表面活性剂对催化活性影响很大.在8.0 MPa,100℃的条件下,该催化体系对萜烯氢甲酰化反应具有较好的催化活性,月桂烯、莰烯和艹宁烯的转化率可分别达到92%,72%和86%.反应完成后,含水溶性铑膦络合物的水溶液与含产物的有机相分离方便,催化剂重复使用8次,其活性和选择性均未明显下降,易于实现催化剂的循环使用.     

高分子金属催化剂的合成和应用

健化剂可分为均相催化剂和非均相催化剂两大类。在工业上所用的催化剂大部分是以无机物为主的非均相催化剂。最近十几年来出现了以有机金属化合物为主的均相催化剂。这种催化剂研究起来较方便,因其活性中心的结构容易搞清楚,而且几乎所有的金属原子都可以用于活性中心,改变配位体可以调节金属活性中心的立体效应或电子环境,因此活性和选择性较高。由于可用于均相催化剂的各种有机金属络合物的出现,过去不能合成的有机化合物,一个接着一个地被合成出来了。同时在工业上对石油化学工业和高分子化学工业起了很大的促进作用。近来在能源     

Fe—Al配位催化环氧丙烷均聚

用于环氧丙烷开环聚合的催化剂为有机金属化合物和稀土络合物等,在对于铁系催化剂催化丁二烯聚合、马来酸酐与苯乙烯共聚和邻苯二甲酸酐与环氧丙烷共聚的研究基础上,我们首次将这一类催化剂用于环氧化物的开环均聚上,发现Fe(acac)3-Al(i-Bu）3催化剂具有良好的催化活性,并进行了产物结构和反应动力学的研究,结构分析表明Fe(acac)3-Al(i-Bu）3催化剂体系具有良好的立体定向性。     

MoS_2-SiO_2-Al_2O_3催化剂的物理性质和催化性质Ⅱ.催化剂的物化性质与硅铝载体中SiO_2/Al_2O_3比的关系

研究了以硅酸铝为载体的 MoS_2催化剂的表面物化性质,以及载体中 SiO_2/Al_2O_3含量比不同时这些物化性质的变化.实验结果表明,组成不同的各硅铝载体载硫化钼后,其表面孔隙结构均有不同程度的变化。这种变化部分是由于承载过程的条件引起的,而主要是由于硫化钼和载体的组成分相互作用而引起.这种相互作用也使载体的表面酸度改变,但这种改变和其裂化活性的变化不是一致的.这种相互作用使载体生成新的粗孔,同时,改变了载体的相组成——形成类似α—SiO_2的新相.根据组成不同的各种硅铝载体在载 MoS_2后所发生的各种表面物化性质的变化,认为硫化钼和硅铝载体各组成分(氧化铝、氧化硅、活性硅铝络合物)形成了新的化合物.     

含氮氧阴离子螯合配体的铑络合物的常压氢甲酰化催化性能

铑膦络合物是最常用的烯烃氢甲酰化反应的催化剂,目前改进这类催化剂的活性和选择性大多从选用新型膦配体着手,而很少研究改变铑络合物本身的配位环境.Rh(acac)(CO)_2等一价铑络合物是人们熟知的氢甲酰化催化剂,而类似结构的Rh(ON)(CO)_2型络合物(ON为氮氧阴离子配体)催化剂则尚未见报道.本文研究了Rh(ON)(CO)_2与膦配体组成的体系在常压下对烯烃氢甲酰化反应的催化作用.所用三种Rh(ON)(CO)_2型络合物的结构如下:     

丁二烯在含有机镁铝络合物稀土催化剂中的聚合

本文研究定向稀土催化剂组份中引入镁铝络合物后对丁二烯聚合的影响。改变镁铝络合物与氯化物的种类和用量,皆明显的影响其聚合活性。当催化剂中含有苯基镁的烷基铝络合物时,聚丁二烯反-1,4链节可达36%。选择适当的催化剂组成和配比时,含镁稀土定向催化剂具有较高的聚合活性。     

CO_2均相催化氢化研究进展

由于近年来可持续发展战略的兴起和对全球变暖问题关注,二氧化碳(CO_2)作为资源用于化学合成已经引起越来越多化学家的兴趣.而在利用CO_2的研究中,催化氢化CO_2是CO_2资源利用的重要手段之一,均相催化反应具有反应条件温和、活性高及催化体系易于调控等优点,使得CO_2均相催化氢化尤其是催化生产甲酸、甲醛、甲醇以及胺类化合物衍生物等方面成为当前CO_2资源合理利用的重要课题,具有广阔的应用前景.对近年来金属有机络合物催化的均相氢化CO_2的研究进展进行了综述,主要介绍了催化生产甲酸、甲醛、甲醇以及作为C1合成子方面中的均相催化剂的种类与结构、活性与选择性以及均相催化氢化CO_2的反应机理等方面的研究.     

金属铁络合物光催化二氧化碳还原

二氧化碳(CO₂)光催化还原技术因兼具解决能源和全球变暖问题的潜力而受到关注。金属铁络合物作为分子型催化剂,具有价格低廉、量子效率高、结构可调控和选择性好等优势,表现出优异的CO₂光催化还原性能,成为CO₂光催化还原领域的研究热点。本文综述了近年来基于金属铁络合物光催化二氧化碳还原研究进展。介绍了铁金属络合物(如:铁卟啉、铁多吡啶、五齿铁配合物)CO₂均相光催化还原体系,总结了体系的构成以及作用机理等,着重关注了体系的催化效率和产物的选择性。此外,综述了以半导体纳米材料/量子点作为光敏剂,金属铁络合物作为催化剂的非均相催化体系的研究进展。最后,对该领域未来的研究方向和所面临的挑战做出展望。     

Impregnated active carbons to control atmospheric emissions. I. Influence of the impregnated species on the porous structure

Impregnated active carbons were prepared to be used as catalysts for complete oxidation, aiming at the reduction of atmospheric emission of volatile organic compounds. Good dispersion of the catalyst is required, as it regulates the conversion efficiency in the pores where pollutants can access to be converted. When impregnation is performed on the raw material or after activation, the influence of impregnated species on the structure and on the catalyst dispersion is already well studied. This paper aims to analyze the influence of impregnated species on the structure and on the catalyst dispersion when the impregnation step is performed after carbonization, as this knowledge is yet very scarce. Olive stones were used as raw material. In order to evaluate the influence of the methodology of impregnation with CoO, Co(3)O(4), and CrO(3), the impregnation step was completed after activation and between carbonization and activation. In the first sequence, the impregnated oxides must be deposited on the internal surface, blocking part of the initial microporous structure. When impregnation is conducted after carbonization, metal species act as catalysts during the activation step. The structure developed strongly depends either on the chemical state of the catalyst or on its distribution in the carbonized material. A well-developed pore structure can appear just where metal species can access, remaining a micropore structure with pores of very small sizes. The better efficiency of Co(3)O(4) as a catalyst of the activation step is conditioned by a worse distribution of the carbonized material, related to the bigger size of its crystals. CrO(3) is the least efficient catalyst for the activation step.     

K对Mn—Co—O的结构及氧化活性的影响

利用XRD,TPD,TFD-MS及催化氧化反应等实验技术,研究了K对Mn-Co-O的结构及氧化活性的影响。XRD结果表明,Mn-Co-O系已形成反尖晶石型的MnCo_2O_4结构;K-Mn-Co-O系中除MnCo_2O_4型结构外,还有新相KMnO_2存在。根据O_2的TPD-MS及吡啶的TPD结果,Mn-Co-O中添加适量的K能提高供氧活性和增加供氧数目,但酸中心数目减少,强度降低。K对Mn-Co—O催化剂氧化活性的影响随反应物分子结构的不同而异,对乙酸乙脂、苯甲酰氯等极性有机物的完全氧化反应,K能提高氧化活性,但对苯、正己烷等非极性有机物的完全氧化反应,K使其活性降低。     

Lithium salts of chiral metallocomplex anions as catalysts for asymmetric trimethylsilylcyanation of aldehydes

A series of the anionic Co^III complexes based on optically active amino acids containing the lithium cation in the external sphere of the complex was synthesized. The synthesized compounds were used as catalysts in the asymmetric addition of trimethylsilyl cyanide to aldehydes. The influence of the temperature, catalyst concentration, and modification of the chiral anion structure on the enantioselectivity of catalysis was studied.     

环氧树脂与氰酸酯共固化反应的研究

应用DSC、FT IR对乙酰丙酮过渡金属络合物催化促进的环氧树酯与氰酸酯共固化反应行为、历程以及固化物的结构特征进行了研究探讨 .结果表明 ,促进剂能够明显的降低固化反应温度 ,缩短固化反应时间 .反应历程首先是氰酸酯发生自聚反应形成二聚体或三聚体 (三嗪环 ) ,然后二聚体可进一步共聚形成三嗪环 ,此过程伴随着环氧基的聚醚反应 ,最后是三嗪环与剩余的环氧基反应形成唑烷酮 .在氰酸酯欠量的条件下 ,固化树脂中主要是唑烷酮和聚醚结构 ,三嗪环结构很少 ;在氰酸脂适量或过量条件下 ,固化树脂主要是三嗪环和唑烷酮结构 ,聚醚结构很少 .     

Anionic composition of precursors of the Co/Al2O3 catalysts for the Fischer-Tropsch synthesis

Cobalt and aluminum hydroxo compounds with the hydrotalcite-type structure containing nitrate, carbonate, and hydroxyl groups are formed due to the deposition by precipitation of cobalt cations from a nitrate solution on ??- and ??-Al₂O₃ under the conditions of urea hydrolysis. The influence of the method of preparation on the anionic composition of the hydroxo compounds (precursors of the Co-Al catalyst) was studied. A correlation between the anionic composition of the precursor compound and the catalytic properties of the catalysts in the Fischer-Tropsch synthesis was established.     

1-Alkyl-4-dialkylaminopyridinium Halides as Phase-Transfer Catalysts in Dichlorocarbene Reactions

 A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated.     

A density functional theory study of the ��mythic�� Lindlar hydrogenation catalyst

A Lindlar catalyst is a popular heterogeneous catalyst that consists of 5?wt.% palladium supported on porous calcium carbonate and treated with various forms of lead and quinoline. The additives strategically deactivate palladium sites. The catalyst is widely used for the partial hydrogenation of acetylenic compounds in organic syntheses. Alkyne reduction is stereoselective, occurring via syn addition to give the cis-alkene. Even if it has been employed for about 60?years, there is a lack of molecular level understanding of the Lindlar catalyst. We have applied density functional theory simulations to understand the structure and the nature of the interplay between the multiple chemical modifiers in the Lindlar catalyst. Indeed, the poisons influence different parameters controlling selectivity to the alkene: Pb modifies the thermodynamic factor and hinders the formation of hydrides, while quinoline isolates Pd sites thus minimizing oligomerization.     

1-Alkyl-4-dialkylaminopyridinium Halides as Phase-Transfer Catalysts in Dichlorocarbene Reactions

Summary.  A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated. Received June 27, 2001. Accepted (revised) September 25, 2001     

重氮化制备钯(0)催化剂及其用于合成芳香胺研究

以2,3-二氨基萘为配体,K_2PdCl_4为金属前驱体,经重氮化制备出一种Pd(0)纳米催化剂(Pd-NPs),其结构经TEM、 XPS、 XRD、 EA和ICP-OES表征,并将催化剂应用于芳香醛类化合物直接还原胺化反应中.在常温常压下以苯甲醛为底物,水为溶剂,H_2为还原剂,探究了胺源、溶剂pH、催化剂用量、反应时间等变量对芳香伯胺产率的影响.实验结果表明芳香伯胺产率高达99%,且该催化剂能多次使用而不失活.     

生物质衍生物γ-戊内酯催化转化制芳烃和2-环戊烯酮的研究

应用浸渍法在ZSM-5沸石分子筛孔道中引入过渡金属Zn物种,制备了具有不同Zn含量的Zn/ZSM-5。考察了反应温度、催化剂用量、催化剂的酸性性质等条件对γ-戊内酯芳构化产物组成(气、液、固产物)及其液体成分含量的影响。实验结果表明,ZSM-5分子筛孔道中引入Zn后,可以有效改变液体产物成分以及影响气体和固体产物收率。当ZSM-5分子筛孔道中引入Zn物种后,能够明显提高液体产物中苯、甲苯、乙苯、萘等芳香类化合物的含量,表明Zn物种能促进γ-戊内酯芳构化反应的进行。