New temperature effect on tunneling reaction in hydrogen, alkane, and ethanol in the solid phase

Rate constants for the tunneling reaction (HD + D → h + D₂) in solid HD increase steeply with increasing temperature above 5 K, while they are almost constant below 4.2 K. The apparent activation energy for the tunneling reaction above 5 K is 95 K, which is consistent with the energy (91–112 K) for vacancy formation in solid hydrogen. The results above 5 K were explained by the model that the tunneling reaction was accelerated by a local motion of hydrogen molecules and hydrogen atoms. The model of the tunneling reaction assisted by the local motion of the reactans and products was applied to the temperature dependence of the proton-transfer tunneling reaction (C₆H₆⁻ + C₂H₅OH → C₆H₇ + C₂H₅O⁻) in solid ethanol, the tunneling elimination of H₂ molecule of H₂ molecule ((CH₃)₂ CHCH(CH₃)₂⁺ → (CH₃)₂ C = C(CH₃)₂⁺ + H₂) in solid 2,3-dimethylbutane, and the selective tunneling reaction of H atoms in solid neo-C₅H₁₂-alkane mixtures.     

Nitrite formation in the radiolysis of aerated aqueous solutions of ammonia

Gamma irradiation of aerated aqueous solutions of ammonia leads to the formation of nitrite as a radiolytic product. Its yield increases with increasing concentration of NH₃ as well as O₂. OH radicals react with NH₃ to give NH₂ radicals, which in the presence of O₂ form NH₂O₂ radicals. These radicals finally lead to the formation of nitrite. G(NO₂⁻) decreases with increasing radiation dose due to secondary reactions. Its initial yield, however, is more than 1/2G_OH, while hydrogen peroxide yield is less than the expected value viz. G(H₂O₂) + 1/2G(e_aq⁻), indicating its participation in reactions with radiation produced free radicals. G(H₂) is 0.35 in aerated aqueous solutions of 10⁻³ mol dm⁻³ NH₃ and 0.23 in the absence of oxygen. Implications of these results to the use of NH₃ in primary coolant water of pressurized water nuclear power reactors of the VVER type are discussed.     

铜(Ⅱ)与2-羰基丙酸水杨酰腙配合物的合成、晶体结构和抑菌活性

以2-羰基丙酸水杨酰腙作为配体与五水硫酸铜进行反应,制得配合物Cu(C₁₀H₈N₂O₄)(H₂O)₂(1)和Cu(C₁₀H₈N₂O₄)(CH₃OH)(H₂O)(2)(C₁₀H₈N₂O₄^2-为2-羰基丙酸水杨酰腙负离子),测试了配合物2的单晶结构.该单晶为墨绿色,属三斜晶系,P1空间群.晶胞参数a=0.7538(2)nm,b=1.1431(2)nm,c=0.7500(2)nm,α=93.26(2)^o,β=94.46(2)^o,γ=94.39(2)^o,V=0.6411(2)nm₃,μ=1.731mm^-1,Z=2,D_c=1.792g/cm³,F(000)=342.00,R=0.035,wR=0.048,GOF=1.78.在配合物2内,2-羰基丙酸水杨酰腙负离子中的2个氧原子和1个氮原子、甲醇中的氧原子以及配位水中的氧原子与铜原子配位,形成四方锥结构,其中来自甲醇的配位氧原子位于锥顶;此晶体为外消旋化合物,晶体中存在对映异构体,两者通过氢键连接,形成二聚体,成对出现在晶胞中.根据元素分析、红外和紫外光谱推测配合物1与2的结构相似;抑菌试验结果表明,配合物1对辣椒疫霉菌和烟草赤星菌分别有100%和66.02%的抑制作用.     

A Gaussian-2 ab initio study of [C2H5S] ions: III. H2 and CH4 eliminations from CH3CHSH and CH3SCH2

Gaussian-2 ab initio calculations were performed to examine the six modes of unimolecular dissociation of cis-CH₃CHSH⁺ (1⁺), trans-CH₃CHSH⁺ (2⁺), and CH₃SCH₂⁺ (3⁺): 1⁺→CH₃⁺+trans-HCSH (1); 1⁺→CH₃+trans-HCSH⁺ (2); 1⁺→CH₄+HCS⁺ (3); 1⁺→H₂+c-CH₂CHS⁺ (4); 2⁺→H₂+CH₃CS⁺ (5); and 3⁺→H₂+c-CH₂CHS⁺ (6). Reactions (1) and (2) have endothermicities of 584 and 496 kJ mol⁻¹, respectively. Loss of CH₄ from 1⁺ (reaction (3)) proceeds through proton transfer from the S atom to the methyl group, followed by cleavage of the C–C bond. The reaction pathway has an energy barrier of 292 kJ mol⁻¹ and a transition state with a wide spectrum of nonclassical structures. Reaction (4) has a critical energy of 296 kJ mol⁻¹ and it also proceeds through the same proton transfer step as reaction (3), followed by elimination of H_2. Formation of CH₃CS⁺ from 2⁺ (reaction (5)) by loss of H₂ proceeds through protonation of the methine (CH) group, followed by dissociation of the H₂ moiety. Its energy barrier is 276 kJ mol⁻¹. On both the MP2/6-31G* and QCISD/6-31G* potential-energy surfaces, the H₂ 1,1-elimination from 3⁺ (reaction (6)) proceeds via a nonclassical intermediate resembling c-CH₃SCH₂⁺ and has a critical energy of 269 kJ mol⁻¹.     

Large heteropolymetalate complexes formed from lanthanide (Y, Ce, Pr, Nd, Sm, Eu, Gd), nickel cations and cryptate [As4W40O140]: synthesis and structure characterization

A new family of heteropolytungstate complexes (NH₄)₂₁[Ln(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·xH₂O(Ln=Y, Ce, Pr, Nd, Sm, Eu, Gd) were prepared by the reaction of Na₂₇[NaAs₄W₄₀O₁₄₀]·60H₂O with NiCl₂·6H₂O and Ln(NO₃)₃·xH₂O at pH≈4.5. The crystal structures of (NH₄)₂₁[Gd(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]·51H₂O was determined by X-ray diffraction analysis and element analysis. The compound crystallizes in the monoclinic space group P2₁/n with a=19.754(3), b=24.298(4), c=39.350(6) Å, β=100.612(3)°, V=18564(5) ų, Z=2, R1(wR₂)=0.0544(0.0691). The central site S1 and two opposite sites S2 of the big cyclic ligand [As₄W₄₀O₁₄₀]²⁸⁻ are occupied by one Ln³⁺and two Ni²⁺, respectively, each site supply four O_d coordinating to metal ion, another one water molecule and other five water molecules coordinate, respectively, to Ni²⁺and Ln³⁺. Polyanion [Ln(H₂O)₅{Ni(H₂O)}₂As₄W₄₀O₁₄₀]²¹⁻ has C_2v symmetry. IR and UV–vis spectra of [NaAs₄W₄₀O₁₄₀]²⁷⁻ of the title compounds are discussed.     

In-Co二元金属氧化物上CO2催化加氢反应的选择性转变:催化反应的机理和构效关系

采用催化加氢的方式将CO₂转化为甲醇,既可以减少CO₂排放,又制备了化学品,该反应具有重要的研究意义.氧化铟(In₂O₃)作为CO2加氢制甲醇催化剂,由于其较高的CO₂活化能力和甲醇选择性,被科研工作者广泛研究.其中,将具有良好解离H2能力的过渡金属元素引入In₂O₃(M/In₂O₃)是有效提高催化剂性能的策略之一,然而,M/In₂O₃体系催化CO₂加氢反应机理及活性位点仍不清楚.本文引入Co制备了In-Co二元金属氧化物催化剂应用于CO2加氢制甲醇,结果表明,相较于In₂O₃,In-Co催化剂性能有很大提升,其中In1-Co₄催化剂上甲醇时空产率(9.7 mmol·g_cat^-1 h^-1)是In₂O₃(2.2 mmol·g_cat^-1 h^-1)的近5倍(反应条件:P=4.0 MPa,T=300℃,GHSV=24000 cm³ _STP g_cat^-1 h^-1,H2/CO₂=3).值得注意的是,尽管Co是金属元素的主体,In-Co催化剂中Co催化CO₂甲烷化的活性受到明显抑制.本文还通过多种技术系统研究了催化剂结构与反应选择性转变间的关系.采用电感耦合等离子体发射光谱、粉末X射线衍射、拉曼光谱、X射线光电子能谱和透射电子显微镜等对催化剂结构以及表面性质进行了表征.结果表明,在H₂还原气氛诱导下,In-Co催化剂表面发生重构,形成以CoO为核,以In₂O₃为壳的核壳结构,其在高压反应后仍能保持稳定;更重要的是,该核壳结构可以显著增强In-Co催化剂吸附及活化CO₂的能力.CO₂加氢反应动力学研究表明,Co催化剂上H₂分压对CO₂加氢为零级反应,而H₂分压在In-Co上的反应级数为正数;In-Co催化剂上,CO₂分压的反应级数接近于零,表明CO₂及其衍生物在In-Co的表面吸附饱和,但在纯Co上,则不会发生这种饱和吸附.通过原位DRIFTS研究了催化反应路径和关键中间物种的吸附及反应行为,发现CO₂加氢在纯Co和In-Co上的催化机理均遵循甲酸盐路径.在该催化路径中,CO₂首先加氢为甲酸盐(*HCOO)物种,随后加氢为甲氧基(*CH₃O).*CH₃O在Co催化剂上进一步加氢生成CH₄,而*CH₃O在In-Co催化剂上则会脱附生成CH₃OH.根据表征结果,本文认为,在还原性气氛下,In-Co发生了重构并生成表面富In₂O₃的核壳状结构,显著提高了催化剂对CO₂和含碳物种的吸附能力.Co和In-Co催化剂对CO₂加氢反应选择性的差异归因于催化剂对CO₂和对*HCOO等含碳中间物种的吸附稳定性不同.CO₂及其衍生的含碳中间物种在In-Co催化剂上的吸附能力比在Co催化剂上强,形成了较合适的催化剂表面C/H比,从而使*CH₃O能够脱附为CH₃OH,而不是进一步加氢为CH₄.综上,本文研究为高活性In-Co催化剂体系在CO₂加氢反应中的催化机理及行为提供了解释,为金属-氧化铟(M-In₂O₃)催化剂体系的设计提供了参考.     

In-Co二元金属氧化物上CO2催化加氢反应的选择性转变:催化反应的机理和构效关系

采用催化加氢的方式将CO₂转化为甲醇,既可以减少CO₂排放,又制备了化学品,该反应具有重要的研究意义.氧化铟(In₂O₃)作为CO2加氢制甲醇催化剂,由于其较高的CO₂活化能力和甲醇选择性,被科研工作者广泛研究.其中,将具有良好解离H2能力的过渡金属元素引入In₂O₃(M/In₂O₃)是有效提高催化剂性能的策略之一,然而,M/In₂O₃体系催化CO₂加氢反应机理及活性位点仍不清楚.本文引入Co制备了In-Co二元金属氧化物催化剂应用于CO2加氢制甲醇,结果表明,相较于In₂O₃,In-Co催化剂性能有很大提升,其中In1-Co₄催化剂上甲醇时空产率(9.7 mmol·g_cat^-1 h^-1)是In₂O₃(2.2 mmol·g_cat^-1 h^-1)的近5倍(反应条件:P=4.0 MPa,T=300℃,GHSV=24000 cm³ _STP g_cat^-1 h^-1,H2/CO₂=3).值得注意的是,尽管Co是金属元素的主体,In-Co催化剂中Co催化CO₂甲烷化的活性受到明显抑制.本文还通过多种技术系统研究了催化剂结构与反应选择性转变间的关系.采用电感耦合等离子体发射光谱、粉末X射线衍射、拉曼光谱、X射线光电子能谱和透射电子显微镜等对催化剂结构以及表面性质进行了表征.结果表明,在H₂还原气氛诱导下,In-Co催化剂表面发生重构,形成以CoO为核,以In₂O₃为壳的核壳结构,其在高压反应后仍能保持稳定;更重要的是,该核壳结构可以显著增强In-Co催化剂吸附及活化CO₂的能力.CO₂加氢反应动力学研究表明,Co催化剂上H₂分压对CO₂加氢为零级反应,而H₂分压在In-Co上的反应级数为正数;In-Co催化剂上,CO₂分压的反应级数接近于零,表明CO₂及其衍生物在In-Co的表面吸附饱和,但在纯Co上,则不会发生这种饱和吸附.通过原位DRIFTS研究了催化反应路径和关键中间物种的吸附及反应行为,发现CO₂加氢在纯Co和In-Co上的催化机理均遵循甲酸盐路径.在该催化路径中,CO₂首先加氢为甲酸盐(*HCOO)物种,随后加氢为甲氧基(*CH₃O).*CH₃O在Co催化剂上进一步加氢生成CH₄,而*CH₃O在In-Co催化剂上则会脱附生成CH₃OH.根据表征结果,本文认为,在还原性气氛下,In-Co发生了重构并生成表面富In₂O₃的核壳状结构,显著提高了催化剂对CO₂和含碳物种的吸附能力.Co和In-Co催化剂对CO₂加氢反应选择性的差异归因于催化剂对CO₂和对*HCOO等含碳中间物种的吸附稳定性不同.CO₂及其衍生的含碳中间物种在In-Co催化剂上的吸附能力比在Co催化剂上强,形成了较合适的催化剂表面C/H比,从而使*CH₃O能够脱附为CH₃OH,而不是进一步加氢为CH₄.综上,本文研究为高活性In-Co催化剂体系在CO₂加氢反应中的催化机理及行为提供了解释,为金属-氧化铟(M-In₂O₃)催化剂体系的设计提供了参考.     

铈(Ⅳ)与焦磷酸盐的配位作用

考察了在焦磷酸盐水溶液中用O₃氧化Ce(Ⅲ),生成的Ce(Ⅳ)与P₂O₇^4-的作用情况,并对不同条件下所得的固体进行了研究。     

Thermal decomposition study on mixed ligand thymine complexes of divalent nickel(II) with dianions of some dicarboxylic acids

Thermal decomposition of mixed ligand thymine (2,4-dihydroxy-5-methylpyrimidine) complexes of divalent Ni(II) with aspartate, glutamate and ADA (N-2-acetamido)iminodiacetate dianions was monitored by TG, DTG and DTA analysis in static atmosphere of air. The decomposition course and steps of complexes [Ni(C₅H₆N₂O₂)(C₄H₅NO₄)²⁻(H₂O)₂]·H₂O, [Ni(C₅H₆N₂O₂)(C₅H₇NO₄)²⁻(H₂O)₂]·H₂O and [Ni(C₅H₆N₂O₂)(C₆H₈N₂O₅)²⁻(H₂O)₂]·1.5H₂O were analyzed. The final decomposition products are found to be the corresponding metal oxides. The kinetic parameters namely, activation energy (E*), enthalpy (ΔH*), entropy (ΔS*) and free energy change of decomposition (ΔG*) are calculated from the TG curves using Coats–Redfern and Horowitz–Metzger equations. The stability order found for these complexes follows the trend aspartate > ADA > glutamate.     

Proton solvates, H·nH2O·mL, formed by diphosphine dioxides with chlorinated cobalt(III) dicarbollide acid

Interaction of hydrated proton, H₅O₂⁺·(H₂O)₄, in dichloroethane solutions with diphosphine dioxides (L) having methyl (Ph₄Me), ethyl (Ph₄Et) and polyoxyethylene chains (Ph₄PEG) linking two diphenyl phosphine oxide groups has been investigated. A bulky counter ion: chlorinated cobalt(III) bis(dicarbollide), [Co(C₂B₉H₈Cl₃)₂]⁻, minimizes perturbation of the cation. At low concentrations, Ph₄Et and Ph₄PEG form anhydrous 1:1 complexes with (P)O–H⁺–O(P) fragment having very strong symmetrical H-bonds. At these conditions Ph₄Me form another compound, H₅O₂⁺·L(H₂O)₂, due to lower PO basicity and optimal geometry of the chelate cycle. At higher concentrations, Ph₄Me and Ph₄Et form isostructural complexes H₅O₂⁺·L₂, whereas Ph₄PEG forms only a 1:1 complex with proton dihydrate, H₃O⁺·H₂O. In excess of free Ph₄Me and Ph₄Et a water molecule is introduced to the first coordination sphere of H₅O₂⁺ and the average molar ratio L/H₅O₂⁺ of the complexes exceeds 2. The composition of these complexes as a function of L and its concentration is discussed.     

铜掺氧化锌多孔纳米棒的水热合成及其光催化性能

通过两步法合成铜掺杂的氧化锌纳米棒,通过X射线衍射（XRD）、扫描电子显微镜（FESEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）和紫外-可见（UV-Vis）分光光谱等技术对系列样品进行了表征,研究并探索了铜掺杂的氧化锌纳米棒光降解染料罗丹明B（RhB）和气体乙醛的催化活性。通过对多孔Cu掺杂ZnO纳米棒光催化分解乙醛进行了评价。多孔Cu掺杂ZnO纳米棒（CZ-5）光催化剂具有最高的催化分解乙醛的能力,比其它多孔Cu掺杂ZnO纳米棒具有很高的催化活性。多孔Cu掺杂ZnO纳米棒光催化剂在室温下在可见光（435 nm）下照射16 h,5.50×10^-4（φ,体积分数）的乙醛气体完全降解为二氧化碳（CO₂）。多孔铜掺杂的氧化锌纳米棒光催化剂的光催化性能的改善主要归因于铜和氧化锌纳米棒之间的协同作用。这种改进的光催化协同作用归因于Cu掺杂ZnO的可见光吸收的延伸和光生电子空穴对的抗重组。     

SO_4~(2-)功能化处理对Fe_2O_3催化剂上氨选择性催化还原NO_x性能的促进机理研究

采用沉淀法制备了Fe(OH)_3和Fe_2O_3。通过硫酸化处理得到SO_4~(2-)/Fe(OH)_3和SO_4~(2-)/Fe_2O_3两种催化剂,并将其应用于氨选择性催化还原NO_x(NH_3-SCR)反应,研究了SO_4~(2-)功能化处理对Fe_2O_3催化剂上NH_3-SCR脱硝性能的促进机理。结果表明,与纯的Fe_2O_3相比,硫酸化处理得到的催化剂上SCR活性得到显著提升;其中,SO_4~(2-)/Fe(OH)_3表现出更加优异的催化性能,在250-450℃时NO_x转化率高于80%,且具有优异的稳定性和抗H_2O+SO_2性能。XRD、Raman、TG、FT-IR、H_2-TPR、NH_3-TPD和in situ DRIFTS等表征结果显示,硫酸功能化处理能抑制Fe_2O_3的晶粒生长,同时SO_4~(2-)与Fe~(3+)结合形成硫酸盐复合物,提高了催化剂表面酸性位点的数量和酸强度,抑制了Fe_2O_3上的氨氧化反应,从而提高了其脱硝催化性能。     

Third-order Optical Nonlinearities of a Series of Compounds Derived from a Keplerate Type Molybdenum-oxide-based Polyoxometalate

Abstract By reacting the unique Keplerate type molybdenum-oxide based polyoxometalate （NH4）42·[MoI320372·（CH3COO）30（H2O）y2]·ca.300H2·ca. 10CH3COONH4（1） with tetramethylammonium bromide, a new derivative （NH4）26[TMA]16{MoI32O372（H2O）72（CH3COO）30}·ca.7NH4CH3COO·ca.189H2O（2, TMA=tetramethylammonium） was prepared. Compound 2 was characterized by Fourier transform infrared spectroscopy（FTIR）, UV-Vis, elemental and thermogravimetric analyses. By the well-established Z-scan technique, investigations on the nonlinear opti- cal（NLO） properties of the series of compounds derived from the Keplerate type molybdenum-oxide-based poly- oxometalate, namely, the newly prepared compound 2, the three previously reported compounds, included compound 1, （NH4hs（TBA）24{Mo132O372（H2O）72（CH3COO）30}·ca.7NH4CH3COO·ca. 173H2O（3, TBA=tetrabutylammonium） and （DODA）40（NH4）2[（H2O）nMo132O372（CH3COO）3o（H20）72]（4, DODA=dimethyldioctadecylammonium）, reveal that the third-order nonlinearity[x（3）] values of compounds 1, 2 and 3 in the DMF/H2O solution and compound 4 in chloro- form are almost the same, which indicates that the counter cations with different length of alkyl chains show ignora- ble impacts on the NLO susceptibility. In other words, the remarkable third-order nonlinearities[x（3）≈10 19 m2/V2] mainly come from the [MoI32O372（CH3COO）30（H2O）72]42 anions. This fact reveals that the applications of the NLO active polyoxometalates in various environments（such as hydrophilic, hydrophobic, polar, apolar, etc.） can be achieved by simply varying cations to meet the demands in the design of diverse devices. Keywords Keplerate type polyoxometalate; Nonlinear optical property; Z-Scan technique; Self-defocusing; Reverse saturable absorption     

气相中CrO2+和H2反应的理论研究

用密度泛函UB3LYP/6-311++G(3df, 3pdpd)//6-311G(2dd, p)方法计算研究了在二重态和四重态两个势能面上的气相反应：CrO₂⁺ + H₂→CrO⁺+ H₂O. 对影响反应机理和反应速率的势能面交叉进行了讨论, 并运用Hammond 假设和Yoshizawa 等的内禀反应坐标(IRC)单点垂直激发计算的方法找出了势能面交叉点(crossing point (CP)). 运用碎片分子轨道(fragment molecular orbital(FMO))理论, 对初始复合物2IM1和4IM1的轨道相关进行了分析, 解释了CrO₂⁺活化H—H σ键及H₂迁移的机理.     

H2O对Cu+/S2O82-/γ-Al2O3催化剂合成碳酸二甲酯性能的影响

反应温度120℃、压力3.0 MPa的条件下,考察了H₂O对浆态床DMC合成催化剂Cu⁺/S₂O₈^2-/γ-Al₂O₃活性的影响。结果表明,外界H₂O的引入加剧了催化剂的失活速率。对引入H₂O后回收催化剂进行了元素分析、XRD、DTG、Py-FT-IR和NH₃-TPD等表征,结果表明,H₂O的引入加速了催化剂中活性组分Cu的流失速率,生成更多没有催化甲醇氧化羰基化活性的Cu₂(OH)₃Cl晶体,加剧了催化剂的失活。     

Structural Characterizations of Spherical Octadecavanadates Encapsulating Na+, K+ or I- and Ellipsoidal Octadecamolybdate Encapsulating two Anions of SO42-

Polyoxoanions of tungsten, molybdenum, and vanadium have been the subject of interest since their wide variety of compositions, structures, and properties give rise to numerous important applications^[1]. From the NH₄VO₃/Na₂S_x (or (NH₄)₂S_x) reaction system we synthesized several spherical octadecavanadates with Na⁺,K⁺, NH₄⁺ or I encapsulated using hydrothermal method. These complexes include (NH₄)₁₁[V₁₈O₄₂(Na)]·(H₂O)₂₀ 1; (NH₄)₁₁[V₁₈O₄₂(K)]·(H₂O)₆, 2; (NH₄)₁₀(Na)[V₁₈O₄₂(Na)]·(H₂O)₂₆, 3; (NH₄)₁₁[V₁₈O₄₂(NH4]·(H₂O)₂₀, 4; and (NH₄)₂₀(I)₇[V₁₈O₄₂(I)]·(H₂O)₁₂, 5, in which the structures of 1, 2, 3, and 5 have been determined by X-ray analyses. In the analogous reaction system of (NH₄)₂MoS₄/(NH₄)₂S_x, we also obtained one ellipsoidal octadecamolybdate, (NH₄)₄[Mo₁₈O₅₄(2SO₄)]·(H₂O)₄, 6 with a standard Wells-Dawson structure^[2]. The Ortep drawings of the two kinds of structures are viewed as follows.     

DRIFT Study on Cr2O3-SO42-/TiO2 Catalyst for Low Temperature Selective Catalytic Reduction of NO with NH3

Chromium oxides supported on TiO2 showed good activity for the selective catalytic reduction of NO by NH3.The catalytic activity of Cr2O3-SO42-/TiO2 catalyst was greatly enhanced by the addition of SO42-into TiO2 support.The catalyst surface properties were characterized with NH3-TPD（temperature programmed desorption） and H2-TPR（temperature programmed reduction）.The sulphate on the catalyst surface could enhance the acidity and redox of the catalyst obviously.The reaction mechanism on this catalyst was researched in detail by in situ diffuse reflectance Fourier transform infrared（FTIR） spectroscope.Eley-Rideal and Langmuir-Hinshelwood mechanism existed simultaneously for selective catalytic reduction（SCR） reaction of NO over Cr2O3-SO42-/TiO2 catalyst.     

溴代烷烃与活性氮的反应发光研究

在流动余辉装置上, 利用N₂空心阴极放电制备活性氮, 研究了活性氮与溴代烷烃(CHBr₃、CH₂Br₂、C₂H₅Br、C₄H₉Br) 反应的化学发光.上述所有反应中, 在550～750 nm波段均观察到了较强的NBr (b¹Σ+→X³Σ^-)跃迁发射谱. 同时在活性氮与CHBr₃和CH₂Br₂的反应中, 在流动管下游还观察到了CN (A²π, B²π→X²Σ⁺)的发射谱. 验证性的实验表明, 激发态NBr (b¹Σ⁺)是由二步过程形成: N(⁴S)与溴代烷烃反应生成NBr (X³Σ^-), 再通过N₂ (A ³Σ_u⁺)分子能量转移到激发态NBr (b¹Σ⁺); 而激发态的CN是通过N(⁴S) + CBr→CN(A, B) + Br过程形成的.     

Fabrication of Fe-POMs as Visible-light-active Heterogeneous Photocatalyst

Visible-light-active Fe-POMs was fabricated via precipitating Fe³⁺ with Keggin type polyoxometalates (H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀ or H₃PMo₁₂O₄₀) under solvothermal condition. The as-prepared Fe-POMs were denoted as FePW, FeSiW and FePMo, respectively. Among the three kinds of Fe-POMs, FePMo displayed the highest visible light absorption, the largest specific surface area, the most sensitive photocurrent response and the smallest charge transfer resistance, which were all beneficial for heterogeneous photocatalysis. The efficiency for Cr(VI) reduction was ca. 88% by FePMo after 50 min visible light irradiation. The estimated rate constant(0.042 min^-1) was ca. 2.5 and 1.8 times that by FePW and FeSiW, respectively. FTIR spectra indicated that the Keggin structure of PMo₁₂O₄₀^3- was maintained in FePMo. Mechanism study indicated that the photogenerated electrons in LUMO and the holes in HOMO were thermodynamically feasible for Cr(VI) reduction and H₂O oxidation, respectively. Using FePMo as an optimized photocatalyst, good stability was also observed after 5 cyclic runs in both photocatalytic performance and XRD structure.     

Two New Borates Built by Different Types of {B9} Cluster Units

Two new belt-like borates Na₄[B₉O₁₄(OH)₃]·0.5H₂O(1) and Na₅[B₉O₁₄(OH)₄](2) have been synthesized under solvothermal conditions. Both compounds contain unprecedented B₉O₁₆(OH)_n^(n+5)-[n=3(1), 4(2)] clusters, which are constructed from four B₃O₃ rings via three BO₄ tetrahedra. Compound 1 exhibits a rare 1D belt with two types of 8-membered ring(MR) windows based on B₉O₁₆(OH)₃^8- clusters. Compound 2 features two different 1D belts built by different B₉O₁₆(OH)₄^9- units, which is first discovered in borate family. UV-Vis diffuse reflectance spectra reveal that compounds 1 and 2 have the cut-off edges below 190 nm, indicating that they may have potential application in deep UV(DUV) region.