Titania membrane preparation with chemical stability for very hash environments applications

The high-quality tubular titania MF membranes are successfully prepared by dip-coating techniques and systematically investigated with regard to their corrosive resistances. The experiments show that dispersants PAA and anatase powder were preferably employed to prepare desired suspensions with solid loading 10–15 wt.% and that suspensions properties significantly affect the final membranes quality. The titania MF membranes with pure water permeability 742.42 l m⁻² h⁻¹ bar⁻¹ and 0.1 μm pore diameter have been obtained using the prepared suspensions. The corrosion resistance of titania membranes exhibits that the anatase layers are more stable than the alumina supports in boiling corrosive medium and that the poor quality titania MF membranes become more deteriorated due to its top layer pore blockages and fouling layer formation, which provides a wide range of practical application fields in very hash environments with reliable data supports.     

Theoretical Study of Weakly Bound Dimers between Hydrogen Fluoride and Some Polar Molecules

Weakly bound linear and bent dimers, FH—X (where X = CO, OC, CNH, NCH, N₂O and ON₂), are investigated using the DFT B3LYP and ab initio MP2 methods with the same basis sets (6–311++G(3df,2pd)). The strengths of the H—C or H—N H‐bonds in dimers FH—CO, FH—CNH, and FH—N₂O are compared with those of the H—O or H—N H‐bonds in dimers FH—OC, FH—NCH, and FH—ON₂. The results obtained for the H‐bond distances, the elongation effect of the HF bond, the red shift of the HF stretching frequency, and the energy difference between the dimer and the charge transfer reveal that the H‐bonds of the first group of dimers are stronger than those of the second. The Gibbs energies calculated for the six dimer formations indicate that the weakly bound dimers are unstable at room temperature (T = 298 K) (FH—X's → FH + X's, ΔG < 0).     

An efficient Stille cross-coupling reaction catalyzed by Pd(OAc)2/DAB-Cy catalytic system

An efficient palladium-catalyzed Stille cross-coupling reaction has been developed. In the presence of 3 mol% of Pd(dba)₂ and 6 mol% of DAB-Cy (1,4-dicyclohexyl-diazabutadiene), various aryl halides (iodides and bromides) were coupled with organotin compounds to afford the corresponding biaryls and alkyne in good to excellent yields. Furthermore, high TONs [turnover numbers, TONs up to 950,000 for the reaction of 1-iodo-4-nitrobenzene and tributyl(phenyl)stannane] for the Stille cross-coupling reaction were observed.     

含氟嵌段共聚物离聚体的合成表征及其性能研究

嵌段共聚物离聚体具有独特的形态和固体及溶液性质 ,在热塑性弹性体、极性材料与非极性材料共混相溶剂和粘度调节剂等领域具有十分广阔的应用前景 ,引起了人们的普遍关注 .文献报道较多的是聚苯乙烯 乙烯 丙烯[1] 、聚苯乙烯 乙烯 丁烯 苯乙烯[2 ] 、聚苯乙烯 异丁烯 苯乙烯[3 ] 等共聚物中 ,聚苯乙烯链段部分磺化后所得离聚体的合成与性质研究 .众所周知 ,含氟聚合物具有低表面能和高表面活性等特性 ,因而将含氟基团引入到嵌段共聚物离聚体中有望开发出一种新型的特殊功能材料 .原子转移自由基聚合 (ATRP)自 1 995年问世以来 ,已成功…     

Synthesis of N—（4—Salicylideneiminoaryl）monoaza Crown Ethers and Dioxygen Affinities of Their Cobalt（Ⅱ）Complexes

The Schiff base‐containing pendant monoaza crown ether HL¹, HL², HL³ and HL⁴ have been synthesized by condensation of salicylaldehyde with N‐(4‐aminoaryl) monoaza crown ethers, which were prepared conveniently from 4‐nitro‐N, N‐di(hydroxyethyl) aniline or 4‐nitrobenzyl chloride via cyclization or condensation and reduction. The structures of HL¹—HL⁴ were verified by ¹H NMR, IR spectra, MS and elemental analysis. Moreover, the oxygenation constants (KO2) and thermodynamic parameters (δH⁰ and δS⁰) of their cobalt(II) complexes were determined in the range of ?5 °C to 25 °C, and the effect of crown ring bonded to a Schiff base on the dioxygen affinities of cobalt(II) complexes was also observed as compared to the uncrowned analogue (CoL).     

青霉素G钾盐在CTAB胶束中的水解及其抑制

以紫外光谱法研究了青霉素G钾盐(Pen-K)在十六烷基三甲基溴化铵（CTAB）胶束体系中的水解反应, 并探讨了水解反应机理.结果表明, CTAB胶束对Pen-K的水解具有抑制作用; Pen-K在CTAB胶束体系水解时,体系pH值的变化与在水中相似, 表明H＋浓度对这种抑制作用影响较小.红外光谱和微极性研究表明,部分Pen-K钾盐定位于CTAB胶束栅栏层中, 增加了其稳定性.     

Unsymmetric-1,3-disubstituted imidazolium salt for palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl bromides

A series of 1-(ferrocenylethyl)-3-substituted-imidazolium salts [3-substitute = 2,6-di(iso-propyl)phenyl (1a), 2,4,6-trimethylphenyl (1b), tert-butyl (1c), 1-Ad (1d), cyclohexyl (1e)] have been synthesized from a racemic ferrocenylethyl acetate and the corresponding N-substituted imidazole in high yields (70–94%). A combination of Pd(OAc)₂ and 1a–d was found to form an excellent catalyst system for the Suzuki–Miyaura cross-coupling reactions of aryl bromides with phenylboronic acid in the presence of Cs₂CO₃.     

Tailoring the optical property by a three-dimensional epitaxial heterostructure: a case of ZnO/SnO2

Epitaxial growth, as a best strategy to attain a heterostructure with a well-defined and clean interface, usually takes place on a planar substrate. In this paper, using a ZnO/SnO2 core-shell heterostructure as an example, we demonstrate the possibility of establishing a three-dimensional epitaxial interface between two materials with different crystal systems for the first time and show possible tailoring optical properties by building the heteroepitaxial crystal interface. The characterization results of element mapping, high-resolution transmission electron microscopy, and selected area electric diffraction reveal that the as-prepared ZnO/SnO2 heterostructure has a tetrapod-like ZnO core and a SnO2 shell with 15-30 nm, and their special epitaxial relation is (010)SnO2//(010)ZnO and [100]SnO2//[0001]ZnO. Such three-dimensional epitaxy between the ZnO core and SnO2 shell is quite different from the usual planar epitaxy or three-dimensional epitaxy between materials having the same crystal structure. A rational model of such complicated epitaxy has been proposed through investigating the certain structural comparability between the wurtzite ZnO and rutile SnO2 crystals. The as-prepared T-ZnO/SnO2 epitaxial heterostructure exhibits unique luminescence properties in contrast with individual tetrapod ZnO and SnO2 nanostructures, in which the epitaxial interface induces new luminescence properties. This result may inspire great interest in exploring other complicated epitaxy systems and their potential applications in laser, gas sensor, solar energy conversion, photo catalysis, and nanodevices in the future.     

富氧条件下Ag/LaMn1-xPdxO3催化剂直接分解NO研究

分别使用柠檬酸络合法和浸渍法制备了钙钛矿型复合氧化物催化剂LaMn1-xPdxO3(x=0,0.01,0.02,0.03,0.04)和不同Ag负载量的Ag/LaMn0.99Pd0.01O3催化剂.使用XRD,BET手段对各催化剂进行了表征,同时在反应条件:NO 0.1%,O2 8%,H2O 0或10%,SO2 0或0.008%,N2为平衡气体,接触时间为0.03g·s·ml-1(GHSV=30000h-1)下对催化剂的活性进行了考察.实验结果发现,当贵金属Pd在B位部分替代Mn时,替代量x=0.01时的催化剂对于催化氧化分解NO反应具有最高活性.另外,在LaMn0.99Pd0.01O3催化剂上负载2%Ag也明显提高了催化剂的活性.而且LaMn0.99Pd0.01O3和2%Ag/LaMn0.99Pd0.01O3催化剂尽管抗水性能不好,但却具有较强的抗SO2性能.     

不可逆电极过程方波伏安法动力学研究 Ⅰ.平行催化体系

本文报道了在不可逆电极过程的强催化体系中，当采用快速方波扫描时，正、逆向电流将出现峰形。依据实验结果，提出了“迁出－进入”的等浓度面理论模型，推导了并讨论了电流方程式。结果表明，文中提出的理论能较好地说明实验结果。