Synthesis and characterization of high molecular weight poly(1,2-propylene carbonate-<Emphasis Type="Italic">co</Emphasis>-1,2-cyclohexylene carbonate) using zinc complex catalyst

Using supported multi-component zinc dicarboxylate catalyst,poly（1,2-propylene carbonate-co-1,2-cyclohexylene carbonate）（PPCHC） was successfully synthesized from carbon dioxide（CO₂） with propylene oxide（PO） and cyclohexene oxide（CHO）.The conversion of epoxides dramatically increased up to 89.7%（yield:384.2 g of polymer per g of Zn） with increasing reaction temperature from 60℃to 80℃.The optimized reaction temperature is 80℃.The chemical structure,the molecular weight,as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively. When CHO feed content（mol%） is lower than 10%,the PPCHC terpolymers have number average molecular weight（M_n） ranging from 102×10³ to 202×10³ and molecular weight distribution（MWD） values ranging from 2.8 to 3.5.In contrast to poly（propylene carbonate）（PPC）,the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0℃to 42.6℃.Similarly,the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO.These improvements in mechanical and thermal properties are of importance for the practical application of PPC.     

Synthesis and catalytic properties of hierarchical TS-1 in the presence of cationic organosilane surfactant

Hierarchical TS-1 has been synthesized in the presence of cationic organosilane surfactant.The material is characterized with XRD,TEM,N₂ adsorption isotherm.The results show that the hierarchical TS-1 aggregates consist of small primary units with sizes of 20-30 nm.The BET surface area increases from 420 to 513 m²/g compared to conventional TS-1 zeolite.The sample is shown to be more active in epoxidation of cyclohexene than conventional TS-1.     

纳米Ru-Mn/ZrO2催化剂上苯选择加氢制环己烯

采用共沉淀法制备了一系列不同Mn含量的纳米Ru-Mn催化剂,考察了纳米ZrO₂作分散剂时它们催化苯选择加氢制环己烯的反应性能,并采用X射线衍射、透射电镜、N₂物理吸附、X射线荧光、原子吸收光谱和俄歇电子能谱等手段对催化剂进行了表征.结果表明,Ru-Mn催化剂上Mn以Mn₃O₄存在于Ru的表面上.在加氢过程中,Mn₃O₄可以与浆液中ZnSO₄发生化学反应生成一种难溶性的(Zn(OH)₂)₃(ZnSO₄)(H₂O)₃盐.该盐易化学吸附在Ru催化剂表面上,从而在提高Ru催化剂上环己烯选择性起关键作用.当催化剂中Mn含量为5.4%时,环己烯收率为61.3%,同时具有良好的稳定性和重复使用性能.     

ZnSO4和La2O3作共修饰剂单金属Ru催化剂上苯选择加氢制环己烯

用沉淀法制备了单金属纳米Ru（0）催化剂,考察了ZnSO₄和La₂O₃作共修饰剂对该催化剂催化苯选择加氢制环己烯性能的影响,并用X射线衍射（XRD）、X射线荧光（XRF）光谱、X射线光电子能谱（XPS）、俄歇电子能谱（AES）、透射电镜（TEM）和N₂物理吸附等手段对加氢前后催化剂进行了表征. 结果表明,在ZnSO₄存在下,随着添加碱性La₂O₃量的增加,ZnSO₄水解生成的（Zn（OH）₂）₃（ZnSO₄）（H₂O）_x（x=1,3）盐量增加,催化剂活性单调降低,环己烯选择性单调升高. 当La₂O₃/Ru 物质的量比为0.075 时,Ru催化剂上苯转化率为77.6%,环己烯选择性和收率分别为75.2%和58.4%. 且该催化体系具有良好的重复使用性能. 传质计算结果表明,苯、环己烯和氢气的液-固扩散限制和孔内扩散限制都可忽略. 因此,高环己烯选择性和收率的获得不能简单归结为物理效应,而与催化剂的结构和催化体系密切相关. 根据实验结果,我们推测在化学吸附有（Zn（OH）₂）₃（ZnSO₄）（H₂O）_x（x=1,3）盐的Ru（0）催化剂有两种活化苯的活性位：Ru⁰和Zn²⁺. 因为Zn²⁺将部分电子转移给了Ru,Zn²⁺活化苯的能力比Ru⁰弱. 同时由于Ru和Zn²⁺的原子半径接近,Zn²⁺可以覆盖一部分Ru⁰活性位,导致解离H₂的Ru⁰活性位减少. 这导致了Zn²⁺上活化的苯只能加氢生成环己烯和Ru（0）催化剂活性的降低. 本文利用双活性位模型来解释Ru基催化剂上的苯加氢反应,并用Hückel分子轨道理论说明了该模型的合理性.     

新型含环己烯结构的甲基二氮杂萘联苯型聚醚酮的合成及表征

合成了一种新型聚合单体 1 甲基 4,5 二 (4 氯代苯甲酰基 )环己烯 ,并与 4 (3 ,5 二甲基 4 羟基苯基 ) 2 ,3 二氮杂萘 1 酮单体经亲核取代反应 ,成功地合成了含环己烯结构的杂环联苯型聚醚酮聚合物 .用FT IR、1H NMR、DSC、X 射线衍射等方法对聚合物进行了表征 ,并研究了聚合物的溶解性能 .结果表明 ,聚合物是一种具有较高的玻璃化温度的可溶性无规共聚物 .聚合物含有不饱和双键结构 ,是一种反应性高分子     

A novel phosphate ligand used for the Rh-catalyzed hydroformylation of cyclohexene in a thermoregulated PEG biphase system

A novel phosphate ligand,tri-(methoxyl polyethylene glycol)-phosphate (TMPGPA),has been synthesized and used in the Rh- catalyzed hydroformylation of cyclohexene in a thermoregulated PEG biphase system.Under the optimized conditions, pressure=5 MPa (H_2:CO=1:1),P/Rh=10 (molar ratio),reaction time=4h and temperature=120℃,the conversion of cyciohexene and the yield of aldehyde are 99%.The catalyst retained in PEG phase can be easily separated from the organic phase containing product by simple phase separation and reused ten times without obvious loss in activity.     

STM studies of cyclohexene hydrogenation/dehydrogenation and its poisoning by carbon monoxide on Pt(1 1 1)

A scanning tunneling microscope that can be operated in ultra high vacuum (<10⁻⁹ Torr) as well as at high pressures (1 − 10³ Torr) has been utilized to study the structures formed by cyclic C₆ hydrocarbons adsorbed on a platinum (1 1 1) crystal surface. Catalytic reactions of cyclohexene were also studied in the presence of hydrogen at pressures (up to 200 mTorr) and 300 K-350 K temperature range. Cyclohexane and cyclohexene produced the same adsorbed structure, which is attributed to the partially dehydrogenated π-allyl (C₆H₉). 1,3-Cyclohexadiene produced structures similar to those produced by benzene. In contrast 1,4-cyclohexadiene forms a structure that we attribute to intact molecular 1,4-cyclohexadiene. During reaction the STM images appear disordered, indicative of rapid diffusion of surface species. Addition of 5 mTorr of CO stops the catalytic activity and forms an ordered structure on the surface.     

Photopolymerization of Cyclohexene Oxide Initiated with Iron-arene Complex

Two iron-arene complex photoinitiators with different substituents in arene ligands were synthesized, their activities in initiating photopolymerization of cyclohexene oxide (CHO) were compared with that of IRGACURE 261, a commercialized photoinitiator from Ciba-Geigy. A higher activity was found when the arene ligand was substituted with a stronger electron donating group. For the system initiated by IRGACURE 261 the concentration of active centers in CHO polymerization was determined and it was found that the concentration is maximum at around 35℃. The post (dark) polymerization was significant, the polymerization yield decreased with the increase of irradiation temperature and increased with the increase of post polymerization temperature. The results are interpreted based on the mechanism proposed by Lohse, et al..     

Epoxidation of cyclohexene on modified Ti-containing mesoporous MCM-41

Ti-MCM-41, B-Ti-MCM-41 and Ti-grafted MCM-41 were synthesized, characterized and studied in the epoxidation of cyclohexene. The synthetic methods and the effect of water in the oxidant are discussed.     

Ti4+修饰阳离子交换树脂催化制备环已烯

在Ti^4 修饰阳离子交换树脂催化剂上进行了环己醇脱水制备环己烯的反应，考察了催化剂吸附毗啶的FT-IR，证实了该催化剂表面具有Bronsted酸和Lewis酸性住是催化环己烯脱水反应的物质基础，实验结果表明：修饰树脂具有较高的热稳定性，Ti^4 交换容量对阳离子交换树脂的催化活性存在着明显的影响，催化剂对环己醇脱水制环己烯反应的活性高，并得到该反应的优化条件如下：环己醇40g，催化剂5g，反应温度175℃，反应时问60min，在此条件下，环己烯的产率达89％。