沸石负载的钒络合物催化剂对烷烃氧化反应的催化性能

 将钒氧吡啶甲基络合物VO（pic）2负载于Y及ZSM－5沸石分子筛\r\n中，制备出沸石负载的钒络合物催化剂．用X射线衍射、电子自旋共振\r\n、红外光谱和元素分析等方法对催化剂进行了表征．结果表明，VO（p\r\nic）2络合物确实负载于分子筛孔道内，负载后的络合物仍保持着原来\r\n的结构．考察了催化剂对正己烷和环己烷氧化反应的催化性能，发现沸\r\n石分子筛负载的VO（pic）2络合物催化剂保留有络合物原有的催化性能\r\n，虽然催化活性有所下降，但显示出较好的形状选择性．与未负载的络\r\n合物相比，NaY和ZSM－5沸石负载的VO（pic）2络合物催化剂对正己烷\r\n氧化反应的伯醇选择性分别提高了2～3倍和5～6倍．     

铁络合物/八面沸石催化剂中沸石主体的纳米效应

 采用自由配体法制备了Fephen／nano－X和Fephen／nano－Y两种\r\n不同粒度的Fephen／八面沸石纳米复合材料（简称为Fephen／FAU），\r\n并采用X射线衍射、傅里叶变换红外光谱、漫反射紫外－可见光谱、热\r\n重－差热分析和催化反应等手段对其进行了表征．研究结果发现，采用\r\n纳米沸石作主体是自由配体法制备金属络合物／分子筛复合材料中提高\r\n络合物负载量的有效方法．催化反应结果表明，与普通粒度的Fephen／\r\nY复合材料相比，两种不同粒度的Fephen／nano－X和Fephen／nano－Y\r\n纳米复合材料对环己烷氧化反应的催化活性有很大的提高．由于两种纳\r\n米沸石主体的差异，两种纳米复合材料的催化性能也明显不同，不仅对\r\n环己烷的转化能力不同，对氧化产物的选择性也不同．     

高渗透性能丝光沸石膜的合成及在醇/水分离体系中的应用

 以四乙基溴化铵为模板剂，用原位水热合成法在α－Al2O3陶瓷\r\n管上合成出丝光沸石膜，系统研究了合成母液的组成、晶化时间、老化\r\n时间、硅源和铝源以及氟化钠助剂的添加等因素对丝光沸石膜成膜和表\r\n面形貌的影响．结果表明，老化可使成膜沸石的晶粒从30μm减小到5μ\r\nm；添加氟化钠也能减小晶粒的大小；使用异丙醇铝为铝源能制得高度\r\n定向的丝光沸石膜．提出了丝光沸石膜的成膜机理，认为成核发生在载\r\n体表面，凝胶层的晶化过程是从载体的表面开始,不断转化,充分生长后达到凝胶层的表面. 丝光沸石膜对醇/水混合体系的分离研究表明,水/甲醇、水/乙醇、水/正丙醇和水/异丙醇的分离因子分别可达到1500(323 K,水含量xw=15%),4200(343 K,xw=15%),4200(343 K,xw=50%)和3400(343 K,xw=50%),所合成的丝光沸石膜能选择性地透过水,对醇/水混合物有较高的分离系数.     

改善β沸石水热稳定性的研究

 考察了不同浓度的盐酸、柠檬酸、酒石酸、草酸和磺基水杨酸溶\r\n液对Hβ沸石的脱铝效果．结果表明，酸处理可以明显提高β沸石的硅\r\n铝比，但沸石的相对结晶度显著降低．然而，低浓度柠檬酸溶液处理不\r\n仅可以提高β沸石的硅铝比，而且可以提高沸石的相对结晶度及水热稳\r\n定性．在引入外来硅源的情况下，考察了低浓度柠檬酸溶液对β沸石的\r\n脱铝补硅作用，提出了一种既可有效提高β沸石硅铝比，又可使β沸石\r\n具有较高结晶保留度的脱铝补硅方法．采用该方法改性的催化剂，对丙\r\n烯水合醚化反应连续运转720h，丙烯转化率由56．6％仅降为52％，表\r\n明催化剂稳定性得到明显改善．     

中孔分子筛HMS负载钴催化剂在费-托合成中的应用:载体HMS的孔径对钴基催化剂性能的影响

 用不同链长度的十二胺，十四胺，十六胺和十八胺等伯胺为模板\r\n剂合成了具有不同孔径大小的HMS中孔分子筛．XRD和低温氮吸附测定表\r\n明，HMS具有典型的中孔分子筛特征，且其孔径大小随HMS合成中所用模\r\n板剂链长度的增加而增加．以HMS为载体，采用孔体积浸渍法制备了负\r\n载量为7．5％的钴催化剂，在接近工业试验条件下（n（H2）／n（CO）\r\n＝2．1，GHSV＝500h－1，p＝2．0MPa，θ＝227℃）考察了载体孔径大\r\n小对费－托合成反应性能的影响．结果表明，与常规的SiO2载体相比，\r\nHMS负载钴催化剂具有更高的催化活性和C5＋选择性；而且，CO转化率\r\n，C5＋选择性及产物中的蜡油比均随着HMS载体孔径的增大而升高．以\r\n7．5％Co／HMS－18为催化剂，CO转化率为78．0％，C5＋选择性为80．\r\n8％，蜡油比为11．1．     

不同环大小分子筛对钼基分子筛催化剂上甲烷无氧芳构化反应的影响

 钼基分子筛催化剂，由于不同分子筛的孔道大小及孔道形状不同\r\n，对甲烷芳构化反应表现出不同的催化性能．具有8元环孔道结构的小\r\n孔ERS－7分子筛没有催化活性，说明甲烷的芳构化反应离不开分子筛孔\r\n道的择形作用，较小的孔道中不能生成苯等芳烃．具有10元环孔道结构\r\n的ZSM－5，ZSM－11和ZRP－1三种分子筛具有较好的催化性能，但由于\r\n其孔道大小及孔道形状的差别在催化行为上表现出一定的差异．具有1\r\n0元环和12元环孔道结构的MCM－22分子筛，尤其对苯等轻芳烃而言，催\r\n化性能最佳．具有12元环孔道结构的JQX－1以及中孔分子筛SBA－15，\r\n虽然具有一定的催化性能，但活性较低．研究结果表明，孔道大小与苯\r\n分子动态直径相近或孔道稍大的分子筛是催化甲烷芳构化反应的良好载\r\n体，孔道过大或过小都不利于苯和萘等芳烃的生成．     

钛硅分子筛TS-1催化氯丙烯环氧化反应动力学研究

 摘要：研究了钛硅分子筛催化氯丙烯环氧化反应的条件及动力学行为．\r\n结果表明，以钛硅分子筛为催化剂，氯丙烯可被高选择性地氧化为环氧\r\n氯丙烷．环氧化反应速度与分子筛中骨架钛的含量及分子筛的用量呈正\r\n比关系，是一级反应．对于氧化剂H2O2，只有当c（H2O2）＜0．4mol／\r\nL时，环氧化反应为一级反应；而c（H2O2）＞1．0mol／L时，为零级反\r\n应．对于氯丙烯，随着其浓度的变化，环氧化反应的级数在1和0之间．\r\n然而，只有当氯丙烯浓度很高时，环氧化反应的级数才有明显的降低．\r\n根据实验结果和Eley－Rideal单分子吸附方程，提出了氯丙烯环氧化反\r\n应的动力学模型．\r\n关键词：钛硅分子筛，氯丙烯，过氧化氢，环氧化，环氧氯丙烷，反应\r\n动力学     

β沸石催化邻苯二酚-叔丁醇烷基化反应

 考察了Hβ沸石及改性Hβ／Al2O3对邻苯二酚－叔丁醇烷基化反\r\n应的催化性能，并采用XRD和NH3－TPD方法表征了Hβ沸石及改性Hβ／\r\nAl2O3的酸性和结构特性，讨论了其酸性对催化活性及选择性的影响．\r\n结果表明，Hβ沸石和Co改性的Hβ／Al2O3的催化性能都优于目前文献\r\n报道的最好水平，对催化邻苯二酚－叔丁醇烷基化反应具有良好应用开\r\n发前景．     

HY沸石上2,6-二叔丁基萘的择形合成

 研究了脱铝HY沸石（n（Si）／n（Al）＝3．8）上萘（naph）的\r\n选择性叔丁基化反应．结果表明，八面沸石对该反应过程有较好的择形\r\n催化作用，两种异构化产物（2，6－二叔丁基萘和2，7－二叔丁基萘）\r\n之间存在着热力学平衡，即两种异构化产物可在酸性中心位上相互转化\r\n．在以叔丁醇为烷基化试剂，WHSV＝2h－1，n（t－BuOH）／n（naph）\r\n＝3，反应温度为120℃的反应条件下，萘的转化率可达98．43％，β－\r\n位选择性可高达100％，二叔丁基萘收率可达74．34％，2，6－二叔丁\r\n基萘／2，7－二叔丁基萘质量比为6．24．     

四乙基溴化铵-氟化物复合模板剂合成β沸石 Ⅲ.结晶动力学及其影响因素

 考察了用四乙基溴化铵－氟化钠复合模板剂合成β沸石的结晶动\r\n力学．结果表明：其晶化曲线为典型的S形曲线；成核活化能En＝65．\r\n79kJ／mol，生长活化能Ec＝91．49kJ／mol；与单纯的四乙基溴化铵模\r\n板剂体系相比，本体系成核诱导期较短，生长速率较快；n（NaF）／n\r\n（SiO2）值增大时，晶化诱导期缩短，成核速率加快，但氟化钠量过高\r\n时，成核速率反而降低，n（NaF）／n（SiO2）最佳值为0．10～0．17\r\n；较高的OH－／SiO2比有利于缩短晶化诱导期．     

On the Presumptive Similarity of Kohn–Sham and Brueckner Orbitals

For states of many-electron systems disclosing various degrees of quasidegeneracy, we have carried out comparative studies of Kohn–Sham orbitals (KSO) generated for several xc-potentials, Brueckner orbitals (BO) represented by the Brueckner-coupled cluster orbitals, and Hartree–Fock (HF) orbitals by means of criteria directly related to the orbital structure which are based on relative distance indices for various pairs of equidimensional subspaces defined by the KSO and BO basis sets. We have found that both for weak and strong quasidegeneracy there are systems for which the KSO–BO distances are larger than the BO–HF ones. For strongly quasidegenerate states it is found that the distance indices are the largest for hybrid potentials, and that the subspaces spanned by KSOs are closer to those spanned by HF orbitals than by BOs. Hence, our results do not support the recently formulated expectations concerning the similarity of Brueckner orbitals and Kohn–Sham orbitals, including those corresponding to purely local exchange-correlation potentials.     

Synergetic activation of "silent receptor" sites leading to a new type of inclusion complex: integration of a 64-membered ring comprising K+ and SO4(2-) ions into a molybdenum oxide-based nanoobject

The new type of inclusion species [Mo(VI)114Mo(V)32O429(H2O)50(KSO4)16]30- comprising 16 encapsulated K+ and SO4(2-) ions shows an unusual 64-membered [K(SO4)]16 ring integrated into a wheel-shaped type nanocluster host; it is formed by a synergetically induced functional complementarity and represents a text-book example of a very complex non-biological material.     

The first 1-alkyl-3-perfluoroalkyl-4,5- dimethyl-1,2,4-triazolium salts

Syntheses of quaternary 1-alkyl-3-perfluoroalkyl-4,5-dimethyl-1,2,4-triazolium iodides have led to a variety of new quaternary salts via metathesis reactions. 1,4,5-Trimethyl-3-trifluoro-methyl-1,2,4-triazolium iodide (6) with LiN(SO(2)CF(3))(2), KSO(3)CF(3), AgClO(4), AgBF(4); 1-(3-fluoropropyl)-3-trifluoromethyl-4,5-dimethyl-1,2,4-triazolium iodide (7) with LiN(SO(2)CF(3))(2); and 1,4,5-trimethyl-3-perfluorooctyl-1,2,4-triazolium iodide (8) with LiN(SO(2)CF(3))(2), AgClO(4), AgBF(4) gave excellent yields of new thermally stable and relatively low melting quaternary salts. The structure of 1,4,5-trimethyl-3-perfluorooctyl-1,2,4-triazolium tetrafluoroborate (11c) was confirmed by single-crystal X-ray analysis. Although the molecular weight of 11c (cation) is 3-fold greater than that of the 3-trifluoromethyl derivative 9d, its melting point is 32 degrees C lower.     

In Process Citation

In a systematic study of the sulphonating properties of SO(3)B complexes, we have paid attention to the thiocyanosulphates KSO(3)SCN and NH(4)SO(3)SCN. We have shown conductimetrically that these salts are dissociated and that the ionic salvation is weak in the chosen solvent-sulpholane-which is strongly aprotic in character. We have determined potentiometrically the equilibrium constant K of the reaction MSO(3)SCN measured angle MSCN + SO(3), by means of the electrochemical couple Ag + SO(3)SCN(-) measured angle AgSCN + SO(3) + e(-). The values foun the ammonium and potassium salts are K = 10(-11.5 +/- 0.45) and 10(-9.7 +/- 0.7) respectively. Thiocyanosulphates appear to be stronger than chlorosulphates as sulphonating agents. Therefore SCN(-) is a weaker base than Cl(-) in sulpholane medium.     

Bridged tetraquaternary salts from N,N'-polyfluoroalkyl-4,4'-bipyridine

4,4'-Bipyridine (1) with excess of polyfluoroalkyl bromide or iodides 2a-d at 100-110 degrees C without solvent gave the monoquaternary salts 3a-d in >90% yields. However, 1 with 2.5 equiv of 2a-c in DMF at 110 degrees C resulted in the diquaternary salts 5a-c in >85% yields. In DMF, 5a-c were obtained in comparable yields when a molar excess of 2a-c reacted with 3a-c. 1,4-Dibromobutane with 3a,b in DMF at 100 degrees C led to the tetraquaternary salts 7a,b in approximately 85% yields. In water or acetone/water as a solvent, salts 3a-d and 5a-c were metathesized with LiN(SO(2)CF(3))(2) and KSO(3)CF(3) to produce monoquaternary ionic liquids 4a-h in >88% yields and diquaternary ionic liquids 6a-f in >86% yields, respectively. Tetraquaternary ionic liquids 8a,b were obtained when LiN(SO(2)CF(3))(2) was reacted with salts 7a,b. These compounds were stable to 340 degrees C as determined by DSC. They are the first N-mono-, N,N'-di-, and N,N,N',N'-tetra-4,4'-polyfluoroalkylbipyridinium quaternary salts and ionic liquids.     

Syntheses and reactions of the fluorinated cyclic thionylphosphazene NSO(Ar)[NPF(2)]2(Ar = 4-t-BuC(6)H(4)-) with difunctional reagents

The S-aryl substituted thionylphosphazene (Cl(2)PN)(2)[4-t-BuC(6)H(4)(O)SN] (1) was prepared by Friedel-Craft's reaction of NSOCl(NPCl(2))(2) with tert-butylbenzene. When it reacted with excess KSO(2)F at 110 degrees C, the P-Cl bonds of 1 were fluorinated, yielding the tetrafluorothionylphosphazene, (F(2)PN)(2)[4-t-BuC(6)H(4)(O)SN] (2). An equimolar reaction of 2 with dilithiated 1,3-propanediol in THF at -78 degrees C resulted in the formation of the ansa-substituted compound CH(2)(CH(2)O)(2)[FPN](2)[4-t-BuC(6)H(4)(O)SN] (3). The crystal structures of 2 and 3 were determined. In 3 the ansa ring is trans on the PNS heterocycle with respect to the aryl group. Reaction of 2 with the disiloxane (CF(2)CH(2)OSiMe(3))(2), in the presence of catalytic amounts of CsF in THF at 90 degrees C, resulted in the formation of the dispiro compound [(CF(2)CH(2)O)(2)PN](2)[4-t-BuC(6)H(4)(O)SN] (4). Compounds 1-4 were characterized by IR, NMR ((1)H, (13)C, (19)F, (31)P), mass spectral, and elemental analyses.     

Adsorption and catalytic properties of enzymes on the surface of silicalite-1

Microporous hydrophobic silicalite-1 was used as a carrier for immobilization of different enzymes, such as horseradish peroxidase, calf intestinal alkaline phosphatase and two β-galactosidases of different origin, to create heterogeneous biocatalytic systems. The peculiarities of enzyme adsorption on the surface of silicalite-1, as well as catalytic properties of the obtained systems compared to enzyme activity in solution and on the surface of other carriers, are discussed.     

Sensitive and selective photoinduced-electron-transfer-based sensing of alkylating agents

Photoinduced-electron-transfer (PET)-based chemosensing is a very elegant way of reporting the presence of a guest species in solution. This method was successfully applied for the detection of different ionic species, such as cations, anions, and protons. Herein, we report on the application of the PET chemosensing concept for the efficient and selective detection of different alkylating agents. 2-(2-Dimethylaminoethyl)benzo[de]isoquinoline-1,3-dione (1) was found to be a highly selective and effective PET chemosensor that turns luminescent upon reacting with different alkylating agents. This PET-based system detected even rather weak alkylating agents, such as dichloromethane. A PET-based sensor that consists of 1 as the active component could detect rather low concentrations of alkylating agents in solution and in the gas phase.     

Morphology control of the produced Ag nanoparticles by soft-template technique

The morphology of the produced Ag nanoparticle is controlled successfully by UV irradiating the reaction solution of AgAc/ethyl alcohol/1-octadeconal/1-dodecanethiol. With use of a novel solution such as soft template, Ag nanorods with different sizes and different ratios of length to diameter can be obtained by adjusting the concentrations of the solution compositions.     

Substrate specificity and novel selective inhibitors of TNF-alpha converting enzyme (TACE) from two-dimensional substrate mapping

We report a systematic analysis of the P1' and P2' substrate specificity of TNF-alpha converting enzyme (TACE) using a peptide library and a novel analytical method, and we use the substrate specificity information to design novel reverse hydroxamate inhibitors. Initial truncation studies, using the amino acid sequence around the cleavage site in precursor-TNF-alpha, showed that good turnover was obtained with the peptide DNP-LAQAVRSS-NH2. Based on this result, 1000 different peptide substrates of the form Biotin-LAQA-P1'-P2'-SSK(DNP)-NH2 were prepared, with 50 different natural and unnatural amino acids at P1' in combination with 20 different amino acids at P2'. The peptides were pooled, treated with purified microsomal TACE, and the reaction mixtures were passed over a streptavidin affinity column to remove unreacted substrate and the N-terminal biotinylated product. C-terminal cleavage products not binding to streptavidin were subjected to liquid chromatography/mass spectrometry analysis where individual products were identified and semiquantitated. 25 of the substrates were resynthesized as discrete peptides and assayed with recombinant TACE. The experiments show that recombinant TACE prefers lipophilic amino acids at the P1' position, such as phenylglycine, homophenylalanine, leucine and valine. At the P2' position, TACE can accommodate basic amino acids, such as arginine and lysine, as well as certain non-basic amino acids such as citrulline, methionine sulfoxide and threonine. These substrate preferences were used in the design of novel reverse hydroxamate TACE inhibitors with phenethyl and 5-methyl-thiophene-methyl side-chains at P1', and threonine and nitro-arginine at P2'.