Ce-SBA-15负载镍催化剂对甲烷二氧化碳重整反应性能研究

通过水热法合成了一系列Ce-SBA-15的介孔材料,并采取满孔浸渍法负载5%Ni(质量百分比),合成了不同的镍基催化剂.用X-射线衍射、透射电镜、N2物理吸附脱附、H2-程序升温还原等方法对其表征,考察了其甲烷二氧化碳重整制合成气的催化活性.结果表明:Ce进入了SBA-15的硅骨架,但Ce的掺入使孔道的孔径发生变化;CeO2的氧循环功能提高了催化剂的抗积碳性能;由于孔道的限域效应,活性金属的分散度随着铈含量的增加而增大,使催化剂活性提高.     

固体碱催化剂上碳酸甲乙酯的洁净合成

制备了氧化镁、氧化钙及镁铝复合金属氧化物3种固体碱催化剂，对不同温度下3种催化剂上碳酸二甲酯与碳酸二乙酯酯交换合成碳酸甲乙酯反应的催化性能进行了考察，并推测了固体碱催化剂上碳酸二甲酯与碳酸二乙酯酯交换合成碳酸甲乙酯的反应机理．结果表明，镁铝复合金属氧化物对该反应具有最优的催化活性，在回流温度下、反应时间为4h、碳酸二甲酯与碳酸二乙酯摩尔比为1：1的条件下，碳酸甲乙酯收率可达45．8％．采用X射线衍射，CO2程序升温脱附对催化剂进行表征．X射线衍射谱图显示镁铝复合金属氧化物中以MgO、Al2O3晶相为主，同时存在少量的MgAl2O4物种．CO2程序升温脱附曲线表明酯交换反应主要在弱碱活性住上进行．     

铁基氧电极催化剂研究进展

燃料电池是一种通过化学反应将燃料所具有的化学能直接转化为电能的装置,因具有系统结构简单、启动快速、寿命长、功率密度和能量密度高等优点而备受关注。但是,燃料电池的氧还原反应动力学过程缓慢,需要高效的催化剂以提高整个体系的运行效率。目前,性能最好、使用最广泛的燃料电池催化剂是铂基催化剂。但铂价格极其昂贵,无法支持大规模商业化应用,此外,铂催化剂易中毒和稳定性差等问题也无法完全解决。近年来的研究表明,铁基催化剂具有良好的氧还原反应催化性能,最有希望替代铂基催化剂。基于此,对近年来各类非贵金属铁基催化剂进行了综述,并在此基础上阐述了各类催化剂目前尚待解决的问题和发展方向。     

有质量手性费米子的势垒隧穿

研究了有质量手性费米子和非手性费米子的势垒隧穿,重点讨论了手性费米子在势垒中的运动特征,对反"Klein隧穿"给出直观解释,并比较了无手性费米子的隧穿行为.     

反相离子对色谱法测定手性生物转化中扁桃酸与苯乙酮酸

建立一种同时测定生物不对称转化发酵液中扁桃酸及苯乙酮酸含量的反相离子对高效液相色谱方法.色谱柱为HypersilC18柱(4.6mm×250mm,5μm),流动相为甲醇-25mmol·L-1磷酸二氢钾缓冲液(内含6mmol·L-1四丁基溴化铵,NaOH调pH至7.0)(体积分数15∶85),流速为1.0mL·min-1,检测波长220nm,柱温为室温.扁桃酸与苯乙酮酸在0.5～20mmol·L-1内,其浓度与峰面积呈现良好的线性关系(r=0.9994,0.9997).二者的加样回收率均为96.5%～100.6%.当信噪比(S/N)为3时,二者的最低检测浓度分别为2.4和8μmol·L-1.该方法简便、准确、灵敏度高,可用于手性生物转化中扁桃酸与苯乙酮酸的定量分析.     

Controllable synthesis of Ni-catalyzed tetragonal tungsten nanowires via chemical vapor deposition

Controllable synthesis of Ni-catalyzed tetragonal tungsten nanowires via chemical vapor deposition     

2,2-二苯环丙烷酸农药中间体的对映体分离研究

利用Pirkle型(S,S)-Whelk-O1手性固定相对2,2-二苯环丙烷羧酸农药中间体进行了对映体分离研究.考察了在流动相正己烷中,异丙醇的浓度变化对手性分离的影响,初步探讨了其手性识别机理,结果表明,(S,S)-Whelk-01上溶质与固定相之间主要是通过吸引作用发生手性识别.     

Development of Olefin Polymerization Catalysts and Their Commercialization

1TheinternationaltrendonpolyolefincatalystR&DandcurrentsituationinChi na　Therapiddevelopmentofpolyolefinindustryhasacloserelationwiththeprogressinpolyolefintechnology.Catalyst,asacoreofthetechnology ,playsaleadingroleintheevolvementoftheindustry .Withthedevelopmentofcatalyst,polyolefinprocessesaresimplified ,productgradesdiversi fied ,andresinperformanceimproved .Theseprogresseshavewidenedtheapplicationscopeofresinsandbettermetthede mandfromsociety .　Initsdevelopment,threekindsofpolyolefin…     

Palladium（ Ⅱ ） and Platinum（ Ⅱ ） Compounds Derived From Potentially Terdentate Ligands

Transition metal complexes derived from potentially terdentate ligands have attracted great interest in the late years. Among all the examples described so far, those containing palladium（ Ⅱ ） or platinum（ Ⅱ ） and ligands holding three heteroatoms with different donor abilities are particularly relevant. In compounds of this kind, the potential hemilability of one of the terminal σ（M-donor atom） bonds, plays an important role in the view of their applications in homogeneous catalysis. On the other hand, it is well-known that in dimetallic complexes the presence of two different metals in a close vicinity may influence their mutual cooperation in a wide variety of processes. Besides that, some examples of the utility of chiral palladium（ Ⅱ ） as well as platinum（ Ⅱ ） complexes as precursors for organic and/or organometallic synthesis, as chiral recognitors or discriminators, or even in Bio-Medicine have also been reported. However, chiral heterodimetallic compounds holding ferrocenyl units and potentially terdentate ligands are scarce.     

Ethylene Oligomerization and Polymerization: Alternative Iron Catalysts beyond 2,6-Bisiminopyridyl Iron Complexes

1Introduction Polyolefin industry arrives the option to transfer from multiple-site systems of the classical Ziegler-Natta catalysts to more sophisticated single-site catalysts. The late-transition metal compounds were traditionally assumed with poor polymerization properties due to the highly competitive chain-termination step, and produced the short-chain oligomers up to 40 carbon atoms (SHOP catalysts). Recently the polyolefins employing latetransition metal complexes as catalysts became a hot research subject with the pioneering works by Brookhart and Gibson. It is promising for nickel catalysts to use solely ethylene as monomer for highly branched polyethylenes, and the designed nickel catalysts were not useful in industry. It is critical time to investigate the relationship of coordination modes of nickel complexes and its catalytic activities and the properties of resultant polyethylenes.