UV LASER INITIATED STEREOSELECTIVE HOMOGENEOUS CATALYSIS POLYMERIZATION OF PHENYLACETYLENE

In this paper, the stereoselective homogeneous catalysis polymerization of phenylacetylene by using two kinds of catalysts W(CO)_5CH_3I and W(CO)_4I_2 produced from UV laser photolysis of W (CO)_6 in CH_3I, I_2—C_6H_6 and CHI_3—C_6H_6 respectively was studied. The effects of laser energy, laser irradiation time and lifetime of catalyst on the polymerization of phenylacetylene were discussed. The photoproducts of W (CO)_6 in CH_3I, I2—C_6H_6 and CHI_3—C_6I_6 were determined by IR spectra. The structures of polyphenylacetylene obtained by W (CO)_5CH_3I and W (CO)_4I_2 catalysts were characterized by IR spectra and ~1H NMR spectra.

Identification of origin of insulating polymer maneuvered photoredox catalysis

Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has not yet been uncovered.In this work,we unleash the root origin of charge transport capability of insulating polymer in photocatalysis.We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides(TMCs),which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics,triggering the generation of defect over TMCs for prolonging carrier lifetime,and acting as hole-trapping mediator for retarding charge recombination.These synergistic roles contribute to the charge transfer of insulating polymer.Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.

Graft Copolymerization of N,N-Dimethylacrylamide to Cellulose in Homogeneous Media Using Atom Transfer Radical Polymerization for Hemocompatibility

In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system, and it reacted with 2-bromoisobutyloyl bromide (BiBBr) to produce macroinitiator (cell-BiB). Then DMA was polymerized to the cellulose backbone in a homogeneous DMSO solution in presence of the cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer with cellulose backbone and PDMA side chains (cell-PDMA) in well-defined structure. The proteins adsorption studies showed that the cellulose membranes modified by the as-prepared cell-PDMA copolymer owns good protein adsorption resistancet.

Synthesis,Crystal Structure and Characterization of a Nickel Complex Based on Phenoxyimine Ligand and Catalysis of the Vinyl Polymerization of Norbornene

The title complex N,O-bis{2-[[（2-benzhydryl-4,6-dimethylphenyl）imino]-methyl]-phenol}-nickel（II）（C56H48N2NiO2） has been synthesized by the reaction of 2-[[（2-benzhydryl-4,6-dimethylphenyl）mino]-methyl]-phenol with Ni（CH3COO）2·4 H2O, and characterized by elemental analysis and IR spectrum. The spatial structure of the complex has been confirmed by single-crystal X-ray diffraction analysis. The compound belongs to the monoclinic system, space group C2/c with a = 39.035（8）, b = 13.276（3）, c = 17.679（4） A°, β = 98.06（3）°, V = 9071（3） A°^3, C56H48N2NiO2, Mr = 839.67, Z = 8, Dc = 1.230 Mg/m^3, μ = 0.472 mm^-1, F（000） = 3536, T = 293（2） K, the final R = 0.0675 and w R = 0.1345（I 〉 2s（I））. The compound showed excellent catalytic activity up to 1.268 × 10^7 g of PNB（mol of Ni）^-1h^-1 for the addition polymerization of norbornene by using methylaluminoxane（MAO） as a cocatalyst.

SIMULTANEOUS POLYMERIZATION AND FORMATION OF POLYPHENYLACETYLENE FILMS BY RARE-EARTH COORDINATION CATALYSIS Ⅳ.KINETICS AND MECHANISM OF POLYMERIZATION

The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)films.The kinetics and mechanism of this polymerization have been investigated by CO_2 quenching and IR,UV analytical methods.The kinetic equation can be expressed as Rp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination of chain propagating.Models for formation of the active complex and polymerization mechanism are proposed.

Synthesis and Characterization of a Palladium Complex Supported by Bidentate Ligand and Catalysis of the Vinyl Polymerization of Norbornene

The title complex N,O-bis{[2-[（2,4-dimethylphenyl）imino]-5-methoxyl]-phenol}-palladium（Ⅱ）（CC_（32）H_（32）N_2O_4Pd） has been synthesized by the reaction of 2-[（2,4-dimethylphenyl）imino]-5-methoxyl-phenol with Pd（CH_3COO）_2,and characterized by elemental analysis,IR spectrum and single-crystal X-ray diffraction analysis.The crystal belongs to the monoclinic system,space group P2_1/c with a = 12.058（2）,b = 8.3624（17）,c = 14.735（3） ？,β = 107.66（3）°,V = 1415.7（5）？~3,C_（32）H_（32）N_2O_4Pd,Mr = 615,Z = 2,D_c = 1.443 Mg/m^3,μ = 0.695 mm^（-1）,F（000） = 632,T = 293（2） K,the final R = 0.0514 and w R = 0.1356（I 〉 2s（I））.Under the co-catalysis of methylaluminoxane（MAO）,the palladium compound exhibited favorable catalytic activity for the polymerization of norbornene（NB）.

POLYMERIZATION MECHANISM OF DIENES WITH HOMOGENEOUS RARE EARTH CATALYSTS

The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η~4-diene (cis-trans-)and η~3-allyl (syn-anti-).

Transesterification Reaction of Waste Cooking Oil and Chicken Fat by Homogeneous Catalysis

In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly performed by transesterification reaction of vegetable oils with methanol and using a homogeneous or heterogeneous catalyst. This work seeks to compare the results produced in transesterification of wasted cooking oil and chicken fat by homogeneous catalysis with NaOH. Due to in each case triglyceride comes from different raw materials, operation conditions differ slightly, which is more evident in the values used for the temperature. For chicken fat was used temperature variations between 35 ℃ and 55 ℃, varying catalyst in percentages between 0.3% and 0.7% with a molar ratio 6：1 in all cases and a reaction time of I h. Likewise, the conditions used in the tmnsesterification process of waste cooking oil were temperature between 50 ℃ and 60 ℃ with a molar ratio 6/1 and 9/1 for alcohol and oil, and catalyst percentage between 0.5% and 0.7% by weight. The yields obtained were between 78% and 94%, or 83% and 95%, for chicken fat and wasted cooking oil, respectively.

低温等离子体耦合Fe^(2+)均相催化降解甲苯和丙酮

本文对比研究了两类典型VOCs(甲苯和丙酮)在单独NTP、NTP+LC/Fe^(2+)和NTP+LC/Fe^(2+)+PCA系统的降解效果.结果表明,甲苯和丙酮的去除率均随放电电压的升高而升高;在相同电压下,甲苯降解效率高于丙酮,但降解过程中O_(3)的产生量相当;当放电电压为22kV时,NTP+LC/Fe^(2+)+PCA系统的甲苯去除效率比单独NTP提高了18.2%,丙酮的去除效率提高了55.5%;NTP+LC/Fe^(2+)+PCA的O_(3)去除率可达100%;EPR和猝灭实验表明,羟基自由基和超氧自由基在LC/Fe^(2+)+PCA反应器中对VOCs去除有重要贡献.最后,结合测定的自由基和中间有机产物,推测了VOCs在NTP+LC/Fe^(2+)体系中的降解途径.

过硫酸盐氧化聚合技术深度处理有机废水研究进展

基于过硫酸盐活化的氧化聚合技术在有机废水定向氧化和深度处理方面受到广泛关注。非均相催化过硫酸盐能使酚类等污染物通过氧化转移反应形成有价值的聚合物,在大幅削减氧化剂用量的同时减少碳排放,有望实现减污降碳和资源回收的双重目标。本文主要概述了矿质和碳质材料耦合过硫酸盐定向氧化有机污染物的性能、构-效关系和影响因素,着重介绍了可能的氧化聚合机理和产物回收分析方法,并对该领域未来的研究方向进行了展望。

Rational design of new in situ reduction of Ni(II)catalytic system for low-cost and large-scale preparation of porous aromatic frameworks

Porous aromatic framework 1(PAF-1)is an extremely representative nanoporous organic framework owing to its high stability and exceptionally high surface area.Currently,the synthesis of PAF-1 is catalyzed by the Ni(COD)2/COD/bpy system,suffering from great instability and high cost.Herein,we developed an in situ reduction of the Ni(II)catalytic system to synthesize PAF-1 in low cost and high yield.The active Ni(0)species produced from the NiCl_(2)/bpy/NaI/Mg catalyst system can effectively catalyze homocoupling of tetrakis(4-bromophenyl)methane at the room temperature to form PAF-1 with high Brunauer-Emmett-Teller(BET)-specific surface area up to 4948 m^(2) g^(−1)(Langmuir surface area,6785 m2 g−1).The possible halogen exchange and dehalogenation coupling mechanisms for this new catalytic process in PAF's synthesis are discussed in detail.The efficiency and universality of this innovative catalyst system have also been demonstrated in other PAFs'synthesis.This work provides a cheap,facile,and efficient method for scalable synthesis of PAFs and explores their application for high-pressure storage of Xe and Kr.

草酸分解工艺研究进展

在乏燃料后处理过程中,草酸常作为钚的沉淀剂,草酸钚滤液因为其中含有部分钚需要返回钚纯化循环,其中的草酸会影响钚的萃取,因此在返回钚纯化循环之前需分解滤液中的草酸。同时在民用化工领域草酸在有机物降解过程中作为中间体积累,威胁水体安全,故在多个领域需要分解草酸。对民用化工领域和核化工领域采用的几种草酸分解工艺的研究进展进行总结,归纳几种草酸分解的工艺方法、应用情况并分析其特点,并根据乏燃料后处理领域的工艺特点和应用需求,分析其在后处理领域的应用前景,重点分析在乏燃料后处理领域得到应用的锰催化分解草酸工艺,并总结锰催化分解草酸的几种反应机理,并根据此提出工程应用存在的问题以及未来的研究方向。

少水/DMSO反应体系制备聚丙烯腈动力学研究

以过硫酸铵(APS)为引发剂,丙烯腈(AN)与衣康酸(IA)为聚合反应单体,采用少量水(不超过10%)和二甲基亚砜(DMSO)作为混合溶剂,进行均相溶液聚合制备聚丙烯腈(PAN)共聚物。研究了AN与IA共聚反应动力学规律,绘制了转化率-时间曲线,建立了聚合反应速率方程,探究了温度对聚合速率的影响。结果表明:随着引发剂浓度和总单体浓度升高,聚合反应转化率增加;随着共聚单体IA含量的增多,聚合反应转化率下降;随水含量的增多,转化率先升高后降低;随温度升高,聚合反应速率常数增大,计算得到反应活化能为127.61kJ/mol;该聚合反应速率方程为:R p∝[APS]^(0.924)[M]^(1.35)。

双金属氰化物催化剂的制备、表征及其催化性能

以丙烯酸-异戊烯醇聚氧乙烯醚梳型共聚物为分散剂,通过分散聚合制备了高活性的双金属氰化物催化剂。元素分析和红外光谱证实了分散剂不仅起分散稳定作用,也参与了催化剂化学结构的形成。X射线衍射谱图和热失重分析说明分散剂与中心金属离子发生了直接络合作用,晶型发生畸变,趋向于无定形态。扫描电镜进一步表明分散法制备的催化剂整体尺寸明显小于直接沉淀法,形貌由紧密的片层状结构转变成更松散的无序堆积。得益于催化剂比表面积增加和单位面积上活性位点的增多,分散法制备的双金属氰化物的催化活性高达66585 g/g催化剂,远高于直接沉淀法(8245 g/g催化剂)。循环实验显示分散法制备的催化剂具有较好的循环能力,在第五次循环时催化活性仍能达56997 g/g催化剂(85.6%),远高于直接沉淀法的1501 g/g催化剂(18.2%)。

Single-atom catalysis: Bridging the homo-and heterogeneous catalysis

Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.

Synthesis of polyurea from 1,6-hexanediamine with CO_2 through a two-step polymerization

Activation and transformation of CO_2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO_2 as a carbonoxygen resource was converted to CO_2-polyurea with 1,6-hexanediamine through a two-step polymerization. The reaction parameters such as temperature, pressure and reaction time were examined; and several kinds of catalysts were screened in the absence and presence of NMP solvent. The formed oligomer and the final polyurea were characterized by FT-IR, VT-DRIFTS, NMR, XRD, AFM and their thermal properties were examined by TGA and DSC. It was confirmed that the final polyurea has a high thermal stability; the melting temperature is 269℃ and the decomposition temperature is above 300℃. It is a brittle polymer with a tensile strength of 18.35 MPa at break length of 1.64%. The polyurea has a stronger solvent resistance due to the ordered hydrogen bond in structure. The average molecular weight should be enhanced in the postpolymerization as the appearance, hydrogen bond intensity, crystallinity, melting point and the thermal stability changed largely compared to the oligomer. The present work provides a new kind of polyurea, it is expected to have a wide application in the field of polymer materials.

Influence of polymer additives on turbulent energy cascading in forced homogeneous isotropic turbulence studied by direct numerical simulations

Direct numerical simulations （DNS） were performed for the forced homogeneous isotropic turbulence （FHIT） with/without polymer additives in order to elaborate the characteristics of the turbulent energy cascading influenced by drag-reducing effects. The finite elastic non-linear extensibility-Peterlin model （FENE-P） was used as the conformation tensor equation for the viscoelastic polymer solution. Detailed analyses of DNS data were carried out in this paper for the turbulence scaling law and the topological dynamics of FHIT as well as the important turbulent parameters, including turbulent kinetic energy spectra, enstrophy and strain, velocity structure function, small-scale intermittency, etc. A natural and straightforward definition for the drag reduction rate was also proposed for the drag-reducing FHIT based on the decrease degree of the turbulent kinetic energy. It was found that the turbulent energy cascading in the FHIT was greatly modified by the drag-reducing polymer additives. The enstrophy and the strain fields in the FH1T of the polymer solution were remarkably weakened as compared with their Newtonian counterparts. The small-scale vortices and the small-scale intermittency were all inhibited by the viscoelastic effects in the FHIT of the polymer solution. However, the scaling law in a fashion of extended self-similarity for the FHIT of the polymer solution, within the presently simulated range of Weissenberg numbers, had no distinct differences compared with that of the Newtonian fluid case.

Syntheses,Structures,Fluorescence and Heterogeneous Catalysis of Coordination Polymers with 4-Benzoimidazol-1-yl-methyl Benzoic Acid and 2,2′-Dipyridine

Two coordination polymers called [Ni（L）2]n（1） and [Ni（2,2？-bpy）22（H2O）]n （2）（HL = 4-benzoimidazol-1-yl-methyl benzoic acid, 2,2？-bpy = 2,2＇-dipyridine） were synthesized by solvothermal reaction simultaneously and characterized by elemental analyses, thermogravimetric analysis, X-ray powder diffraction, IR spectroscopy and single-crystal X-ray diffraction analysis. Complex 1 crystallizes in monoclinic system, space group P21/c with a = 14.673（3）, b = 10.773（2）, c = 16.566（3） ？, V = 2559.2（8） A^3, Z = 4 and F（000） = 1160. 2 also crystallizes in monoclinic system, space group C2/c with a = 15.404（3）, b = 12.652（3）, c = 6.5362（13） ？, V = 1246.2（5） A^3, Z = 4 and F（000） = 712. The bridging L ligand connects the Ni^Ⅱ cations into a 2D network in complex 1, while 2 shows a 1D structure formed through the two O atoms of SO4^（2-） ions connecting the molecule. The catalytic properties indicate that complex 1 shows good catalytic activities for the cyanosilylation of 4-chlorobenzaldehyde. In addition, fluorescence property of complex 1 which quenches the excitation intensity in solid state was investigated at room temperature.

THE INFLUENCE OF SUBSTITUENTS IN METALLOCENE ON PROPYLENE POLYMERIZATION

Two new unbridged zirconocenes, bis(2.4,7-trimethyl indenyl)zirconium dichloride (Met-I) and bis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-II) were prepared in order to investigate the steric effects of substituents on the nature of the catalysts for the: polymerization of propylene. A mixture of methyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)(3)] was used as cocatalyst to activate these catalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted in an increase of both activity and molecular weight as well as the isotacticity.