铼(Ⅶ)催化烯丙醇移位/去对称化串联反应

使用Re_2O_7和手性磷酸为共催化剂,实现了催化不对称的环己二烯酮烯丙醇移位/氧杂-Michael加成串联反应。通过这一反应,可以一步构建带有三个手性中心的环己烯酮骨架结构,为合成带有这一类骨架的天然产物和药物分子提供了高效的合成方法。同时,通过分析条件的优化,找到了合适的手性拆分条件,为光学活性环己烯酮化合物提供了分析方法。     

Ethanolysis of waste cottonseed oil over lithium impregnated calcium oxide: Kinetics and reusability studies

A series of Li/CaO catalysts has been prepared by impregnating 0.5–5.0 wt% Li in CaO by wet chemical method. Prepared Li/CaO catalysts have been characterized by powder X-ray diffraction, scanning electron and transmission electron microscopy and Brunauer–Emmett–Teller (BET) surface area studies, in order to establish the structure and surface morphology of the catalyst. Hammett indicator test study was performed to determine the basic strength of the Li/CaO catalysts. The prepared Li/CaO catalysts have been employed as a heterogeneous catalyst for the transesterification of waste cottonseed oil (having 2.8 wt% free fatty acid contents) with ethanol. Under optimal reaction conditions viz., ethanol/oil molar ratio of 12:1, catalyst to oil weight fraction of 5% and 65 °C reaction temperature, 98% fatty acid ethyl ester yield was obtained in 2.5 h of reaction duration. Under the optimized reaction conditions, the pseudo first order constant and Arrhenius activation energy were found to be 0.03 min⁻¹ and 70.0 kJ mol⁻¹, respectively. Further Li/CaO catalyst was also found to be effective for the ethanolysis and methanolysis of vegetable oils having up to 3.4 wt% free fatty acids. The use of 3-Li/CaO catalyst is advantageous considering that it not only utilizes waste cottonseed oil as a feedstock, but also renewable and nontoxic alcohol, ethanol, for the biodiesel production.     

Chemical structure and catalytic activity of quaternary onium salt‐type triphase catalysts based on CPS microspheres

In this work, diversified quaternary onium salt‐type triphase catalysts (TPC) were prepared based on crosslinked polystyrene (CPS) microspheres, and the relationship between their chemical structures and catalytic activities in liquid‐solid‐liquid reaction system were investigated in depth by using the esterification reaction of benzyl chloride with sodium acetate as a model system. The experimental results indicate that the chemical structures of the TPC affect their catalytic activity greatly and there are four basic points: (1) the quaternary phosphonium‐type TPC have higher activity than quaternary ammonium‐type catalyst; (2) the TPC with more lipophilic substitutes at N atom have higher catalytic activity; (3) the TPC with longer spacer arm, which links quaternary onium salt group to the matrix microsphere, have higher catalytic activity; (4) the bonding density of quaternary onium salt group on the polymeric carrier affects the hydrophilic and hydrophobic property of the TPC, and consequently, influences the catalytic activity significantly. For a given triphase catalysis system, there is an optimal bonding density of quaternary onium salt group on the solid catalysts. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Transesterification of Canola Oil to Biodiesel Using CaO/Talc Nanopowder as a Mixed Oxide Catalyst

A series of heterogeneous catalysts including different molar ratios of CaO/talc was synthesized to study the transesterification reaction of canola oil and methanol under different reaction conditions. Characterization and kinetic results revealed that the activity of this catalyst was enhanced due to the increase of CaO/talc molar ratio value leading to an improvement in the biodiesel production. Moreover, the effect of various parameters on the activity of the undertaken catalysts was studied in order to determine the optimum process conditions. Leaching measurements and the durability of the CaO/talc catalyst under several reaction cycles were evaluated and proved it to be a stable catalyst.     

Preparation and photocatalytic activity of PANI-CdS composites for hydrogen evolution

In this paper, a series of PANI-CdS (PANI is the abbreviation of Polyaniline) composites were synthesized by changing the mass of PANI (molar ratio of PANI and CdS : 0.5, 0.7, 1, 1.5, 2). The PANI-CdS composites were characterized by XRD patterns, IR spectra and elemental analysis. The activities of as-prepared composites were also tested with regard to hydrogen evolution. It was found that PANI-CdS composites showed good activity for hydrogen evolution. With increment of PANI, the activity for hydrogen evolution of PANI-CdS reduced. But compared with pure CdS, PANI-CdS had a much higher activity for hydrogen evolution.     

聚α-烯烃合成油及其加氢工艺的研究进展

聚α-烯烃合成油是所有合成润滑油基础油中性能最优异的一种,具有黏度指数高、低温性能和高温氧化安定性好、抗燃性好及挥发性低等优点,是未来应用广泛的合成基础油,市场需求持续增加。综述聚α-烯烃基础油及其加氢工艺、加氢精制催化剂的研究现状。传统聚α-烯烃合成油生产工艺有乙烯齐聚法和石蜡裂解法等,潞安煤制油工艺和天然气制油工艺等新工艺也开始兴起。加氢精制工艺对提高聚α-烯烃合成油的质量起着至关重要的作用,北京燕化聚华工贸有限公司两段加氢精制工艺和中国石油兰州润滑油厂聚α-烯烃合成油加氢精制处理工艺均极大改善了聚α-烯烃合成油的质量。聚α-烯烃合成油加氢精制效果很大程度取决于加氢精制催化剂性能,要求加氢精制催化剂具有较高的选择性和较好的稳定性。