硅氧化合物化学蒸气沉积法精细调变沸石分子筛

本文报告了用化学蒸气沉积法精细调变沸石孔径的结果，着重考察了正硅酸乙酯和六甲基硅醚沉积条件的关系。间二甲苯和均三甲苯的吸附动力学实验表明，用Ｓｉ－（ＯＥｔ）４制得的ＳｉＨβ和ＳｉＨＺＳＭ－５上的吸附速率及吸附量明显下降，证实沸石的孔口得到了调变。正己烷的吸附等温线和异丙醇探针反应，沸石孔容和孔道内酸性未受孔口调变的影响。结果还表明Ｓｉ（ＯＥｔ）４未进入沸石孔道，而六甲基硅醚分子则进入Ｈβ沸石孔道，     

TiO2形态结构与光催化活性关系的研究

本文介绍了TiO₂多相光催化剂的作用机理及其结构特性对光催化活性的影响,并对TiO₂的晶相组成、晶粒尺寸、比表面积、表面形态与光催化活性的关系作了综述。     

β沸石的铝化

β沸石自1988年结构被确定以来受到普遍重视,由干结构上的特殊性,G沸石既具有较强酸性又具有明显的碱性［‘,‘］．但q佛石的高硅铝比使其在化学组成上对碱性的贡献甚微,如果能降低其硅铝比,则有可能获得具有较强碱性的佛石分子筛．直接合成的o佛石,硅铝比一般在10以上．     

TCDD的密度泛函理论研究

用B3LYP/6-311G~(**)方法全优经计算22个四氯二苯并对二（左口右恶）英（ 简称TCDD）分子，得到几何构型、总能量、标准熵、标准焓和标准自由能。将2， 3，7，8－TCDD的计算构型与X射线衍射实验测定值进行了比较。计算结果表明，总 能量、标准焓和标准自由能与氯原子量换位置的相关性很高（r > 0.997）.1,3,6, 8-TCDD的总能量处自由能最低，即最稳定，以此参照，得到异构体的总能量的相对 稳定性顺序和自由能的相对稳定性顺序。1,3,7,9－TCDD的稳定性次之，1,3,7,8- TCDD居第三，将这二个顺序与焚烧炉产生的TCDD异构体和合成的异构体对的生成面 分比进行了比较，说明焚烧炉中产生的TCDD和合成的TCDD对的分布主要受热力学控 制。     

Synthesis, X-ray crystal structures, and gas sorption properties of pillared square grid nets based on paddle-wheel motifs: implications for hydrogen storage in porous materials

A systematic modulation of organic ligands connecting dinuclear paddle-wheel motifs leads to a series of isomorphous metal-organic porous materials that have a three-dimensional connectivity and interconnected pores. Aromatic dicarboxylates such as 1,4-benzenedicarboxylate (1,4-bdc), tetramethylterephthalate (tmbdc), 1,4-naphthalenedicarboxylate (1,4-ndc), tetrafluoroterephthalate (tfbdc), or 2,6-naphthalenedicarboxylate (2,6-ndc) are linear linkers that form two-dimensional layers, and diamine ligands, 4-diazabicyclo[2.2.2]octane (dabco) or 4,4'-dipyridyl (bpy), coordinate at both sides of Zn(2) paddle-wheel units to bridge the layers vertically. The resulting open frameworks [Zn(2)(1,4-bdc)(2)(dabco)] (1), [Zn(2)(1,4-bdc)(tmbdc)(dabco)] (2), [Zn(2)(tmbdc)(2)(dabco)] (3), [Zn(2)(1,4-ndc)(2)(dabco)] (4), [Zn(2)(tfbdc)(2)(dabco)] (5), and [Zn(2)(tmbdc)(2)(bpy)] (8) possess varying size of pores and free apertures originating from the side groups of the 1,4-bdc derivatives. [Zn(2)(1,4-bdc)(2)(bpy)] (6) and [Zn(2)(2,6-ndc)(2)(bpy)] (7) have two- and threefold interpenetrating structures, respectively. The non-interpenetrating frameworks (1-5 and 8) possess surface areas in the range of 1450-2090 m(2)g(-1) and hydrogen sorption capacities of 1.7-2.1 wt % at 78 K and 1 atm. A detailed analysis of the sorption data in conjunction with structural similarities and differences concludes that porous materials with straight channels and large openings do not perform better than those with wavy channels and small openings in terms of hydrogen storage through physisorption.     

A Facile Synthesis of Ethyl 2,4-Dimethoxy-6-perfluoroalkyl-benzoates via Acyclic Precursors

Introduction Polysubstituted arenes are important intermediates in synthetic medicines and dyestuffs, and the fluorinated analogues are more attractive as a result of their lipo-philicity and the increment of activity.1,2 Therefore, to study the convenient and efficient synthesis of polysub-stituted arenes is valuable in organic synthetic method-ology. We have designed a simple synthesis of fluori-nated polysubstituted arenes through the intramolecular Wittig reaction of a new phosphorous ylid…     

溶胶-凝胶法制备铁酸盐超微粒子催化剂

采用溶胶－凝胶法制备了含Zn,Ni,Co的铁酸盐超微粒子催化剂，运用DTA－TG、IR、XRD以及BET比表面测试等手段对所制备的样品进行了表征。同时，考察了铁酸盐对二氧化碳选择性氧化乙苯制苯乙烯的催化性能。结果表明：制备的铁酸盐均为尖晶石型晶体，粒子的比表面积为31．9－36．3m^2/g，晶粒大小约为30－35nm，在由二氧化碳选择性氧化乙苯制苯乙烯的反应中表现出较好的催化活性。     

Ultraviolet photolysis of CH2I2 in methanol: O-H insertion and HI elimination reactions to form a dimethoxymethane product

Ultraviolet photolysis of low concentrations of CH2I2 in methanol solution found that CH2I2 is converted into dimethoxymethane and some H+ and I- products. Picosecond time-resolved resonance Raman (ps-TR3) experiments observed that the isodiiodomethane (CH2I-I) photoproduct decayed faster as the concentration of methanol increases, suggesting that isodiiodomethane is reacting with methanol. Ab initio calculations indicate isodiiodomethane is able to react with methanol via an O-H insertion/HI elimination to form an iodoether (ICH2-O-CH3) and HI products. The iodoether can then further react via another O-H insertion/HI elimination reaction to form the dimethoxymethane (CH3-O-CH2-O-CH3) observed in the photochemistry experiments. A reaction mechanism consistent with these experimental and theoretical observations is proposed.     

Comparison of the dehalogenation of dihalomethanes (CH2XI, where X = Cl, Br, I) following ultraviolet photolysis in aqueous and NaCl saltwater environments

The ultraviolet photolysis of low concentrations of CH(2)XI (X = Cl, Br, I) were investigated in water and saltwater solutions by photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both kinds of solutions formed mostly CH(2)(OH)(2) and HI and HX products. However, photolysis of the CH(2)XI molecules in saltwater resulted in production of some CH(2)XCl products not observed in aqueous solutions without salt present. The appearance of these new products in saltwater solutions is accompanied by a decrease in the amount of CH(2)(OH)(2), HI, and HX products compared to photolysis in aqueous solutions without salt present. The possible implications for photolysis of CH(2)XI and other polyhalomethanes in seawater and other salt aqueous environments compared to nonsaltwater solvated environments is briefly discussed.