Marked Enhancement of the Methane Dehydrocondensation Toward Benzene Using Effective Pd Catalytic Membrane Reactor with Mo/ZSM-5

Steady state product formation rates of benzene, hydrogen, naphthalene, toluene in methane dehydrocondensation reaction on 3wt% Mo loaded ZSM-5 catalyst was enhanced 2–10 times by the removal of hydrogen using Pd membrane for 100h at 883K. The amount of permeated hydrogen through the Pd membrane was measured before and during the methane dehydrocondensation reaction. About 50–60% of hydrogen from the total hydrogen produced during the methane dehydrocondensation was selectively removed by the Pd membrane, owing to which the equilibrium of the methane dehydrocondensation was shifted toward the product side.     

Synthesis and Properties of Stannole-Containing Polymers by Reaction of Bis(cyclopentadienyl)titanacyclopentadiene-Containing Polymers and Tin(IV) Chloride

Polymers having bis(cyclopentadienyl)titanacyclopentadiene units in the main chain were prepared by the polymerization of a low-valent bis(cyclopentadienyl)-titanium(II) complex, generated in situ from bis(cyclopentadienyl)titanium dichloride (Cp₂TiCl₂) and n-butyllithium (2 equiv), with internal diynes such as 1,4-bis(1-hexynyl)-benzene and 4,4′-bis(1-hexynyl)biphenyl. The bis(cyclopentadienyl)titanacyclopentadiene-containing polymers were subjected to the reaction with tin(IV) chloride, followed by the treatment with methyllithium to give 1,1-dimethylstannole-containing organometallic polymers in moderate yields. The stannole containing polymers are soluble in organic solvents, whose number-average molecular weight was estimated to be 2,700–2,800 by GPC. Optical and electrochemical properties of the resulting stannole-containing polymers were studied by their UV-vis spectra and cyclic voltammetric analyses, from which they were supposed to have low LUMO energy levels.     

熔融阶梯控温控压法合成聚乳酸

以L-乳酸为原料,探讨了催化剂种类、反应温度、阶梯控温、阶梯控压对熔融缩聚法合成聚乳酸的影响.结果表明,阶梯控温控压能大幅提高聚乳酸的摩尔质量和产率,其最佳反应条件为:氯化亚锡与对甲苯磺酸复合催化剂用量为乳酸单体质量的0.5%,先于1000 Pa下120 ℃反应4 h,再于500 Pa下180 ℃反应8 h.所得聚乳酸摩尔质量达到151 000 g/mol,产率为82.12%.     

Ladder Polyphenylsiloxanes with Single and Double Stranded Fragments in the Chain

Abstract

The reaction of heterofunctional polycondensation (HFC) of ladder polyphenylsiloxanes with hydroxyl groups at the ends with α, ω-dichlorodimethylsiloxanes in a solution in the presence of an acceptor, HCl-pyridine, and with α, ω-bis(dimethylamino)dimethylsiloxanes in a melt in a mole ratio 1:1 and 1:2 of the starting components, respectively, has been studied. Block copolymers completely soluble in organic solvents are synthesized. Thermogravimetric, thermomechanical and X-ray analyses of polymers obtained werre carried out. The thermomechanical and X-ray analyses have made it possible to establish that at certain lengths of the phenylsiloxane and dimethylsiloxane links phase separation is observed, which points to block copolymer formation.     

Stable and Selective Dehydrocondensation of Methane Towards Benzene on Modified Mo/HMCM-22 Catalyst by the Dealumination Treatment

A modified Mo/HMCM-22 catalyst by the dealumination treatment (Mo/HMCM-22-D) exhibited remarkable performance for the catalytic dehydrocondensation of methane with a higher selectivity of benzene and a lower selectivity of coke, in comparison with the same Mo catalyst supported on parent HMCM-22 (Mo/HMCM-22). Excellent catalytic stability as well as a high benzene formation rate of 1500 nmol/(g-cat·s) was obtained on a 6%Mo/HMCM-22-D catalyst at 1023 K, 3 atm and 2700 ml/(g·h) owing to the efficient suppression of coke formation. Dealumination of the HMCM-22 zeolite was characterized by XRD, ²⁷Al and ¹H MAS NMR and NH₃-TPD techniques. It was found that the dealumination treatment of HMCM-22 zeolite resulted in an effective suppression of acid sites, particularly the Brønsted acid sites (proton form in Al--O--Si) owing to the removal of tetrahedral framework aluminum, while the microporous structure and the zeolite framework remained unchanged. It was suggested that the stable and selective dehydrocondensation of methane towards benzene is based on the suppression of coke formation owing to the effective decrease of strong Brønsted acid sites by the dealumination treatment of the HMCM-22 zeolite.     

Synthesis by ATRP and Properties of Liquid Crystalline Three-Armed Star Polymers Containing Azobenzene Chromophores

Atom Transfer Radical Polymerization (ATRP) has been applied to synthesize liquid crystalline methacrylic polymers having three-arms star structure, starting from a central core of C₃ symmetry. By just changing the duration of the polymerization process, macromolecules having distinct average chain lengths with low polydispersity values and well defined end-groups have been obtained. All the obtained star-shaped polymers, characterized by differential scanning calorimetry and polarized optical microscopy, exhibit smectic and nematic liquid-crystalline phases on heating, with transition temperatures strongly dependent on the average polymerization degree, and high clearing points. The comparison of these systems with the analogous linear derivatives pointed out higher glass transition temperature values, although they are characterized by lower average polymerization degree. Such behavior can be attributed to the stiffness of the aromatic core, which limits the free movement of chain ends.     

树枝状-星型聚合物的合成研究进展

介绍了树枝状-星型聚合物的合成方法,重点综述了以树枝状大分子引发剂合成树枝状-星型聚合物的研究进展,对树枝状-星型聚合物的性质和应用等进行了讨论.     

改性硅梯型高耐温绝缘密封胶的研究

以混合甲基氯硅烷为主要原料合成具有线型及梯型混合结构的聚合物．本文探讨了该聚合物的R／si比值对聚合物基本性能的影响，以及聚合物合成过程中反应温度、时间、反应介质等对合成产物的影响．另外，通过红外光谱及热失重分析，研究了该聚合物的基本结构与性能并介绍了聚合物在高耐温绝缘胶中的初步应用情况。     

导电聚合物的合成和应用前景

本文对导电聚合物的性能，一般的合成方法如链聚合法和分步骤合法，特殊的合成方法如电化学合成和光化学聚合作了较详细的评述。介绍了氧化或还原试剂掺合进这些聚合物中，被称为掺杂剂的类型和掺杂方法。最后介绍了这些新材料的某些应用领域以及存在的问题。     

新型超支化聚合物聚氨酯的合成

研究了由丁二酸酐和二乙醇胺为起始原料合成超支化聚合物的方法；采用分步反应合成出了几种聚氨酯类超支化聚合物。考察了反应时间、带水剂、封端剂及其配比对反应结果的影响。试验结果表明，第1步反应时间为3h，第2步缩和脱水反应时间为8h(甲苯为带水剂)，第3步用脱水剂封端脱水为48h；甲苯为较好的带水剂；带水剂、封端剂及其配比对产品粘度、溶解性、颜色等影响不大；产物的比浓对数粘度在0．02dL/g左右。     

Synthesis and Reactions of Organometallic Polymers Containing Titanacyclobutene Units in the Main Chain

A new class of polymers containing titanacyclobutene units in the main chain were prepared by the reaction of organic dihalides (2) with a binuclear titanium propargyl complex (3) generated in situ from bis(pentamethylcyclopentadienyl)titanium chloride (Cp*₂TiCl, 1), SmI₂, and 1,4-bis(3-bromopropynyl)benzene (2a). The dark red colored polymers (4) thus obtained are soluble in organic solvents such as tetrahydrofuran and chloroform, and they are stable at ambient temperature under argon atmosphere. The reaction of the titanium-containing polymers (4) with hydrogen chloride was found to give organic polymers (7) containing unsaturated main chain.     

吡啶衍生物及其催化闭环法合成

介绍吡啶衍生物的分类,并详细总结了烷基吡啶和卤代吡啶的应用及其合成路线。简要分析全球吡啶及其衍生物的生产及市场现状,概述了烷基吡啶和卤代吡啶的合成技术进展及其合成方法,并对吡啶衍生物的催化闭环法合成进行了介绍。最后指出我国的科研工作者应重视开发具有自主知识产权的吡啶新化合物。     

荧光共轭聚合物的结构设计与合成方法研究

荧光共轭聚合物既有机小分子荧光材料优良的光学品质,又具有高分子材料优越的可加工性能,成为了荧光材料的研究热点。因此,荧光共轭聚合物在开发新型化学、生物及爆炸物传感器等方面具有非常广阔的应用前景。本文介绍了几种典型的荧光聚合物,重点介绍了聚合物中荧光发色团的合成,从分子结构设计、应用及优缺点等方面对各种合成方法进行阐述比较。并且展望了今后荧光共轭聚合物的发展前景。     

Synthesis and Characterization of Novel Organoiron Polymers

Synthesis of novel organoiron polymers containing oxygen, sulfur, and/or nitrogen bridges was achieved via nucleophilic aromatic substitution polymerization of cyclopentadienyliron complexes of chloroarenes with a number of aliphatic and aromatic dinucleophiles.     

自膨润型树脂留香剂的制备及应用

以丙烯酸和丙烯酸酯类进行共聚，然后用环氧氯丙烷同时进行共聚分子间及共聚分子与纤维素之间的两种交联，在纤维素上形成单分子层交联丙烯酸酯的网络结构。这种结构对油性香精具有非常好的留香作用，最长保香期为９６天，耐洗４８次。     

Synthesis of Energetic Polymers by the Introduction of Energetic Groups onto Polymeric Primary and Secondary Amines

Energetic polymers have been synthesised by the introduction of picryl groups onto linear polyethylenimine and polyvinylamine. The degree of substitution was 70–97% for polyethylenimine, depending upon the molecular weight of the polymer, and around 70% for polyvinylamine. N‐Picrylation of low molecular weight, model compounds was also studied. The results illustrate the influence of molecular weight on the chemical accessibility of a reaction site and reflect the difficulty of modelling polymer modification reactions using small molecules.     

乙醇胺气固相催化合成乙撑胺

以乙醇胺和液氨为原料,改性H-ZSM-5型分子筛为催化剂,在固定床反应器中气固相催化合成乙撑胺。考察了催化剂组成(金属硝酸盐种类及配比)和制备条件(浸渍温度和时间、干燥温度和时间、焙烧温度和时间)对催化反应的影响,并且考察了催化剂的稳定性。结果表明,催化剂组成和制备的最佳条件是:硝酸钙配比为0.04g/g分子筛、60℃浸渍6h,140℃干燥1h、450℃焙烧6h。在100h内催化剂的稳定性良好。     

有机硅聚合改性氟碳聚合物的研究进展

本文主要介绍有机硅聚合改性有机氟碳聚合物合成方法、用途及其发展前景。     

苯并菲类液晶高分子合成及应用

苯并菲类材料能够组装为柱状相,因此在光电材料、信息存储以及功能分子膜中得以广泛应用。主要是探讨苯并菲类液晶高分子合成及应用,希望能够对相关人员起到参考性价值。     

Synthesis of Some Fluorinated Phenylmethylsiloxane Polymers and Characterization of Their Surface Properties

Conditions have been established for the preparation of three fluorinated phenylmethylsiloxane polymers via syntheses of the appropriate monomers, controlled hydrolyses of these monomers, and polymerization of the resulting oligomers. The polymers thus prepared, in increasing order of fluorine content, were poly(4-fluorophenylmethylsiloxane), poly(3,5-difluorophenylmethylsiloxane), and poly[3,5-bis(trifluoromethyl)phenylmethylsiloxane]. The surface energies of the first two polymers were measured and found to be very similar to those of typical fluorosubstituted polymers that are aliphatic rather than aromatic. This similarity indicates that the bulky phenyl groups do not significantly interfere with migration of the fluorine atoms to the surfaces of these fluorinated phenylmethylsiloxane polymers.