Cu/Zn、Cu/Zn/Ni催化剂甲醇部分氧化制氢

研究了甲醇在Cu/Zn及Cu/Zn/Ni催化剂上部分氧化热耦合裂解制氢的反应,系 统地考察了不同O2/CH3OH比及反应温度下催化剂性能.当O2/CH3OH=0.2时,催化剂的性能最 佳.在同样条件下, Cu/Zn催化剂对CO的选择性较Cu/Zn/Ni催化剂低,更具优势. Cu/Zn催化 剂用于甲醇部分氧化反应时,甲醇转化率在150 h寿命实验中基本保持在90％左右. XRD谱图 表明Cu/Zn合金的生成是导致Cu/Zn系催化剂在甲醇裂解反应中快速失活的主要原因,而在部 分氧化反应中, O2的存在可抑制Cu/Zn合金的生成,使Cu/Zn催化剂表现出高度的稳定性.     

Kinetics of Zn/Zn(II) reactions in acidified solutions of potassium chloride

The title subject has been studied using stationary, single-pulse, and chronopotentiometric polarization measurements on the Zn/Zn(II) electrode and equilibrium measurements on the same and the Ag/AgCl electrode in 0.5–4 M chloride solutions at 25°C. The Zn/Zn(II) electrode reactions are found to occur in two consecutive charge-transfer steps with Zn(I) as intermediate. The ion-transfer step Zn/Zn(I) is too fast to exhibit its kinetics. The electron-transfer step Zn(I)/Zn(II) mostly occurs by the couple ZnCl₂(H₂O)_y/ZnCl₂(H₂O)_y, but species with one or no chloride ligand take over as the main electroactive ones at chloride (or salt) concentrations below 1 M. The value of y is not clearly revealed by the data. Some sluggishness in complex equilibration and some, double-layer effects are observed. A convenient scale for single-ion activities is described, used, and recommended.     

EuZn2Si2 and EuZn2Ge2 Grown from Zn or Ga(ln)/Zn Flux

Single crystals of the novel ternary compounds EuZn₂Si₂ and EuZn₂Ge₂ were grown from pure gallium, indium, or zinc metal used as a flux solvent. Crystal properties were characterized using X-ray single-crystal analyses via Gandolfi and Weissenberg film techniques and by four-circle X-ray single-crystal diffractometry. The new compounds crystallize with ternary derivative structures of BaAl₄, i.e., EuZn₂Si₂ with ThCr₂Si₂-type (a=0.42607(2) nm, c=1.03956(5) nm, I4/mmm, R₁=0.038) and EuZn₂Ge₂ with CaBe₂Ge₂-type (a=0.43095(2) nm, c=1.07926(6) nm, P4/nmm, R₁=0.067). XAS and magnetic measurements on EuZn₂Si₂ and EuZn₂Ge₂ revealed in both compounds the presence of Eu²⁺ ions carrying large magnetic moments, which order magnetically at low temperatures. The magnetic phase transition occurs at T_N=16 and 7.5 K for the silicide and the germanide, respectively. In EuZn₂Si₂ there occurs a spin reorientation at 13 K and furthermore some canting of antiferromagnetically ordered moments below about 10 K. In EuZn₂Ge₂ a canted antiferromagnetic structure is formed just at T_N.     

Cu/Zn/Al/Mn催化剂上CO/CO2加氢合成甲醇特性研究

利用共沉淀法制备了四组分的Cu-Zn-Al-Mn和Cu-Zn-Al-Ce催化剂以及三组分的Cu-Zn-Al催化剂。利用组成H2/CO/CO2/N2=66/27/3/4(体积比)的富CO原料气对催化剂进行了活性评价，并研究了温度、压力和空速等反应条件对催化剂活性的影响。结果发现添加适量的锰助剂能显著提高催化剂的活性和热稳定性。利用SEM和XRD方法进行了催化剂的结构和形貌表征，同样表明锰助剂可以起到阻止CuO晶粒长大和促进CuO分散作用。利用富CO2的生物质原料气体积比为H2/CO/CO2/N2=50/25/20/5对Cu-Zn-Al-Mn催化剂进行的评价表明：Cu-Zn-Al-Mn催化剂上CO/CO2加氢合成甲醇的甲醇产率和选择性均有下降，在试验范围内，甲醇产率下降11％～25％，选择性为93％～95％。     

Direct catalytic asymmetric Michael reaction of hydroxyketones: asymmetric Zn catalysis with a Et2Zn/linked-BINOL complex

Full details of our direct Michael addition of unmodified ketones using new asymmetric zinc catalysis are described. Et(2)Zn/(S,S)-linked-BINOL complexes were successfully applied to direct 1,4-addition reactions of hydroxyketones. The first generation Et(2)Zn/(S,S)-linked-BINOL 1 = 2/1 system was effective for 1,4-addition of 2-hydroxy-2'-methoxyacetophenone (3). Using 1 mol % of (S,S)-linked-BINOL 1 and 2 mol % of Et(2)Zn, we found that a 1,4-addition reaction of beta-unsubstituted enone proceeded smoothly at 4 degrees C to afford products in high yield (up to 90%) and enantiomeric excess (up to 95%). In the case of beta-substituted enones, however, the first generation Et(2)Zn/(S,S)-linked-BINOL 1 = 2/1 system was not at all effective. The second generation Et(2)Zn/(S,S)-linked-BINOL 1 = 4/1 with MS 3A system was developed and was effective for various beta-substituted enones to afford products in good dr, yield (up to 99%), and high enantiomeric excess (up to 99% ee). With the Et(2)Zn/1 = 4/1 systems, catalyst loading for beta-unsubstituted enone was reduced to as little as 0.01 mol % (substrate/chiral ligand = 10 000). The new system was also effective for 1,4-addition reactions of 2-hydroxy-2'-methoxypropiophenone (9) to afford chiral tert-alcohol in high enantiomeric excess (up to 96% ee). Mechanistic investigations as well as transformations of the Michael adducts into synthetically versatile intermediates are also described.     

Single-ion activities and Zn/Zn(II) reactions in alkali chloride solutions

The title subject has been studied through equilibrium potential measurements on the Zn/Zn(II) and the Ag/AgCl electrode vs. SCE and galvanostatic single-step and chronopotentiometric polarization measurements on the former electrode, all in acidified (to pH about 3) solutions of 0.005 M ZnCl₂+0.99 M MeCl (for Me=Li, Na, K, and Cs) at 25°C. It is found that the Zn(II) activity decreases together with the alkali-ion activity along the sequence LiCl>NaCl>KCl>CsCl, that the chloride-ion activity essentially is insensitive to mutual substitutions of alkali ions, and that the Zn/Zn(II) reactions exhibit no other than pure activity effects of such substitutions. The results support that the Zn/Zn(II) electrode reacts in two consecutive steps with Zn(I) as intermediate, and that some sluggishness appears in chemical reactions to and from electroactive Zn(II) species.     

不同锌铝比水滑石的合成及吸附脱除水中邻苯二甲酸性能的研究

采用共沉淀法合成一系列具有不同锌铝比的水滑石,并利用X射线衍射（XRD）、扫描电镜（SEM）、热重（TG）、氮气吸脱附及电感耦合等离子体质谱（ICP-MS）等表征手段对其结构与组成进行了测试。将上述水滑石材料用于吸附脱除水中邻苯二甲酸污染物,考察了不同锌铝比水滑石吸附邻苯二甲酸性能的差异。结果表明,在较低锌铝比时,随着水滑石锌铝比的增加,其对邻苯二甲酸的吸附量逐渐增大;当锌铝比较大时（>6）,随着锌铝比的增加,水滑石的吸附量基本保持不变。进一步选取锌铝比为6的水滑石,分别对其吸附邻苯二甲酸的动力学和热力学进行了研究,发现其吸附等温线和吸附动力学数据分别符合Freundlich等温吸附模型和准二级动力学模型,且循环吸附性能较好。     

Die Schmelzdiagramme der Systeme CsN3/Zn(N3)2 und KN3/Zn(N3)2

The phase diagrams of the systems CsN₃/Zn(N₃)₂ and KN₃/Zn(N₃)₂ have been obtained employing the microscopic technique ofL. Kofler andA. Kofler. Within the system CsN₃/Zn(N₃)₂ three eutectics at 148°C, 142°C, and 210°C were found. Besides Cs₂Zn(N₃)₄, melting incongruently in the interval 153°C to 170°C, there exist two further compounds of the most probable composition Cs₃Zn₂(N₃)₇ and CsZn₂(N₃)₅, melting congruently at 170°C and 210°C, resp. In the system KN₃/Zn(N₃)₂ there exist two eutectics at 203°C and 172°C and two compounds, one of them, i.e. K₂Zn(N₃)₄, melting congruently at 206°C, the other one, with composition KZn₃(N₃)₇ or KZn₄(N₃)₉, melting incongruently at 210°C.

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Mit 8 Abbildungen

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Herrn Professor Dr.Heribert Grubitsch zum 70. Geburtstag gewidmet.     

Direct catalytic asymmetric aldol reaction of hydroxyketones: asymmetric Zn catalysis with a Et(2)Zn/linked-BINOL complex

Full details of our newly developed catalyses with asymmetric zinc complexes as mimics of class II zinc-containing aldolase are described. A Et(2)Zn/(S,S)-linked-BINOL complex was developed and successfully applied to direct catalytic asymmetric aldol reactions of hydroxyketones. A Et(2)Zn/(S,S)-linked-BINOL 1 = 2/1 system was initially developed, which efficiently promoted the direct aldol reaction of 2-hydroxy-2'-methoxyacetophenone (7d). Using 1 mol % of (S,S)-linked-BINOL 1 and 2 mol % of Et(2)Zn, we obtained 1,2-dihydroxyketones syn-selectively in high yield (up to 95%), good diastereomeric ratio (up to 97/3), and excellent enantiomeric excess (up to 99%). Mechanistic investigation of Et(2)Zn/(S,S)-linked-BINOL 1, including X-ray analysis, NMR analysis, cold spray ionization mass spectrometry (CSI-MS) analysis, and kinetic studies, provided new insight into the active oligomeric Zn/(S,S)-linked-BINOL 1/ketone 7d active species. On the basis of mechanistic investigations, a modified second generation Et(2)Zn/(S,S)-linked-BINOL 1 = 4/1 with molecular sieves 3A (MS 3A) system was developed as a much more effective catalyst system for the direct aldol reaction. As little as 0.1 mol % of (S,S)-linked-BINOL 1 and 0.4 mol % of Et(2)Zn promoted the direct aldol reaction smoothly, using only 1.1 equiv of 7d as a donor (substrate/ligand = 1000). This is the most efficient, in terms of catalyst loading, asymmetric catalyst for the direct catalytic asymmetric aldol reaction. Moreover, the Et(2)Zn/(S,S)-linked-BINOL 1 = 4/1 system was effective in the direct catalytic asymmetric aldol reaction of 2-hydroxy-2'-methoxypropiophenone (12), which afforded a chiral tetrasubstituted carbon center (tert-alcohol) in good yield (up to 97%) and ee (up to 97%), albeit in modest syn-selectivity. Newly developed (S,S)-sulfur-linked-BINOL 2 was also effective in the direct aldol reaction of 12. The Et(2)Zn/(S,S)-sulfur-linked-BINOL 2 = 4/1 system gave aldol adducts anti-selectively in good ee (up to 93%). Transformations of the aldol adducts into synthetically versatile intermediates were also described.     

Electrical-Conductive/Insulating Bi-Functional Layers for Stable Zn Metal Anode

Zinc-ion batteries are regarded as an extremely promising candidate for large-scale energy storage equipment due to the inexpensive ingredients and high safety. However, dendrite growth and side reactions occur in the Zn anode, which lead to exceedingly low coulombic efficiency (CE) and poor cycling stability. In this work, we propose a strategy of a conductive/insulating bi-functional coating layer (CIBL) for stable Zn metal anodes. Porous Ag nanowires (NWs) coating as a conductive layer effectively reduces the nuclear barrier and contains Zn²⁺ deposition in a certain space. Polyimide (PI) coatings as insulating layer implement a shunting effect on Zn²⁺, which could reduce the differential concentration on the Zn surface and induce uniform deposition of Zn²⁺. Therefore, the CIBL−Zn//CIBL−Zn battery achieves stable plating/stripping of over 1300 h at 1 mA cm⁻². The CE of CIBL−Zn//CIBL−Zn battery maintains at 99.2 % even after 1000 cycles. Moreover, the CIBL−Zn//V₂O₅ battery exhibits a capacity of nearly 289.2 mA h g⁻¹ at 5 A g⁻¹ after 3000 cycles and no sign of capacity degradation is found, which further demonstrate the feasibility of this strategy in practical application.     

Zn(Thr)Ac2•2H2O固态配合物的制备及标准生成焓

在水-丙酮混合溶剂中合成了未见文献报导的Zn(Thr)Ac2•2H2O固态配合物,通过化学分析、元素分析、IR、XRD和TG-DTG等对其组成、结构及热稳定性进行了研究.用微量热法测定了配合物在298.15 K时在纯水中的溶解焓,计算了Zn(Thr)2＋(aq,∞)和Zn(Thr)Ac2•2H2O(s) 的标准摩尔生成焓分别为(955.24±5.70) kJ•mol－1和(-570.92±5.71) kJ•mol－1.     

Stereochemical Study of the Allylation of Aldehydes with Allyl Halides in Cosolvent/Water(Salt)/Zn and in Cosolvent/Water(Salt)/Zn/Haloorganotin Media

The stereochemical course of the allylation and propargylation of several aldehydes with crotyl and propargyl halides using zinc powder as the condensing agent in cosolvent/water(salt) media have been extensively studied. Radical ions of well-defined geometry such as [CH(2)=CHCH(CH(3))Br](*)(-) are thought to be formed through an electron-transfer process, which seems to be accelerated by the high interfacial energy developed by the water. These radicals are trapped by the aldehyde molecules to form isomeric mixtures of threo/erythro-beta-methylhomoallylic alcohols or alpha-allenic/beta-acetylenic alcohols. The stereochemistry seems to be determined by the structure of the radical anions adsorbed on the zinc particles and is independent of the geometry of the organic halides, the cosolvents, or the salts. Reactions performed in the presence of Bu(3)SnCl show no discrimination between the coupling reactions of the allyl bromide with aldehydes and with Bu(3)SnCl, both homoallylic alcohols and allyltributylstannanes being formed. In contrast, in the presence of Bu(2)SnCl(2) only beta-methylhomoallylic alcohols are formed, this being a function of the differential allylstannation of aldehydes and crotyldibutyltin halides, which are intermediate products of the zinc-mediated process. The zinc-mediated method gives satisfactory results with acetals if workup is made under the catalytic mediation of Bu(2)SnCl(2).     

Heterobimetallic molecular cages for the deposition of Cu/Ti and Cu/Zn mixed-metal oxides

Heterobimetallic molecular precursors [Ti4(dmae)6(mu-OH)(mu-O)6Cu6(OAc)9.H2O] (1) and [Zn7(OAc)10(mu-OH)6Cu5(dmae)4Cl4] (2) for the deposition of metal oxide thin films of Cu6Ti4O12 (Cu3TiO4, TiO2) and Cu5Zn7O12 (ZnO, CuO) were prepared by the interaction of Ti(dmae)4 with Cu(OAc)2.2H2O for 1 and tetrameric (N,N-dimethylamino)ethanolatocopper(II) chloride, [(dmae)CuCl]4 [where dmae = (N,N-dimethylamino)ethanolate] with Zn(OAc)2.2H2O (where OAc = acetate) for 2 in dry toluene. Both complexes were characterized by melting point, elemental analysis, Fourier transform IR, fast atom bombardment mass spectrometry, thermal analysis (TGA), and single-crystal X-ray diffraction. TGA and XRD prove that complexes 1 and 2 undergo facile thermal decomposition at 300 and 460 degrees C to form thin films of Cu/Ti and Cu/Zn mixed-metal oxides, respectively. Scanning electron microscopy and XRD of the thin films suggest the formation of impurity-free crystallite mixtures of Cu3TiO4 and TiO2, with average crystallite sizes of 22.2 nm from complex 1 and of ZnO and CuO with average crystallite sizes of 26.1 nm from complex 2.     

Europium substitution into intermetallic phases grown in Ca/Zn flux

Replacement of calcium with europium in the phases Ca₂₁Ni₂Zn₃₆ and CaNi₂Zn₃ was attempted to explore the possibility of substitution in metal flux reactions and potential magnetic interactions between closely spaced Eu²⁺ ions. Limited substitution occurs when Eu is added to the reaction of nickel in a Ca/Zn flux mixture, up to stoichiometries of Eu_5.8(3)Ca_15.2(3)Ni₂Zn₃₆ and Eu_0.42(8)Ca_0.58(8)Ni₂Zn₃. Structural characterization and magnetic susceptibility studies on Eu_xCa_21−xNi₂Zn₃₆ phases indicate that the Eu and Ca ions do not form an even solid solution on their sites, but instead segregate in separate regions of the crystals. The europium-rich regions of the samples order ferromagnetically, with T_C dependent on the size of the clusters. If the concentration of Eu in the flux is raised above 20 mol%, a new compound Eu_1.63(1)Ca_1.37(1)Ni₂Zn₃ (Cmcm, a=4.1150(5) Å, b=16.948(2) Å, c=10.302(1) Å, Z=4, R₁=0.0396) is produced.     

Differences between Zn/HZSM-5 and Zn/HZSM-11 zeolite catalysts in alkylation of benzene with dimethyl ether

HZSM-11 zeolite supported Zn catalysts with different Zn contents （xZn/HZSM-11A） were prepared. In the alkylation of benzene with dimethyl ether （DME） in a fixed bed reactor, the catalyst with Zn content of 6 wt% （6Zn/HZSM-11A） showed appropriate performance. Focus was put on the comparison between 6Zn/HZSM-5 and 6Zn/HZSM-11 with the same crystal size of 600-800 nm, and also with the similar BET surface area, micropore volume, Si/Al2 molar ratio, and acidity. In the alkylation of benzene with DME, the 6Zn/HZSM-11 showed better activity and stability, and especially enhanced the conversion of benzene and selectivities to xylene and trimethylbenzene, compared with the 6Zn/HZSM-5. This was mainly related to the higher adsorption capacity and adsorption-desorption rates to the three adsorbates （benzene, m-xylene and 1,3,5-trimethylbenzene） over the 6Zn/HZSM-11 in comparison with the 6Zn/HZSM-5.     

Effect of Zn2+ Ions on Upconversion Emission of Er3+ in Zn/Er:LiNbO3 Crystal

The effect of Zn2+ ions codoped on the upconversion emission of Er3+ ions in Er:LiNbO3 crystal under different excitation wavelength was reported.The upconversion emission spectra of Zn/Er:LiNbO3 follo...     

Calcium-organic frameworks cathode for high-stable aqueous Zn/organic batteries

Rechargeable aqueous zinc-ion batteries (AZIBs) are attracting tremendous attention because of their intrinsic merits such as high safety and low cost. Cathode plays a critical role in enhancing the electrochemical performance of AZIBs. However, it is difficult to design a robust and high-efficiency cathode material and further implement the commercialization of AZIBs. Metal-organic frameworks (MOFs) electroactive compounds are attractive to serve as the cathode of AZIBs due to their unique porosity and crystal structures, resource renewability and structural diversity. In this work, a calcium-pure terephthalates acid framework (Ca-PTA·3H₂O) was synthesized by facile hydrolysis and cationic exchange method, then explored as a novel cathode for AZIBs. The results highlight a high specific capacity of 431 mAh/g (0.51 mAh/cm²) at a current density of 50 mA/g, and excellent cycle performance with capacity retention of ∼90% after 2700 cycles at 500 mA/g. The following up characterizations investigate the reversible zinc storage mechanism in detail. This experiment made a specific contribution to the exploration of the new MOF as a competitive cathode for AZIBs.     

Zum System Zn/Mo/O. I. Phasenbestand und Eigenschaften der ternären Zinkmolybdate; Struktur von Zn3Mo2O9

On the System Zn/Mo/O. I. Phases and Properties of Ternary Zinc Molybdates; Crystal Structure of Zn₃Mo₂O₉ Several ternary compounds are known in the Zn/Mo/O-system. The phases ZnMoO₄, Zn₂Mo₃O₈ and Zn₃Mo₂O₉ are stable at 900°C. The coexistence ranges are shown in the ternary phase diagram. The structure of Zn₃Mo₂O₉ has been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P2₁/m (a = 7,757(1) Å, b = 7,132(1) Å, c = 8,370(2) Å, β = 117,40(1)º, Z = 2).     

Reductive esterification of aromatic aldehydes using Zn/Ac2O/imidazole or Zn/Yb(OTf)3/(RCO)2O system

Benzaldehydes are reduced by metallic zinc in the presence of Ac₂O and imidazole, giving the corresponding benzyl acetates in good yields. Reductive esterification of aromatic aldehydes is also carried out via gem-diacetoxy compounds. Carbonyl compounds are readily converted to the gem-diacyloxy compounds in excellent yields on treatment with 2 molar amounts of acid anhydride and 10 mol% of Yb(OTf)₃ in MeCN at room temperature. Thus-formed diacyloxy compounds derived from aromatic aldehydes are reduced in situ by metallic zinc to afford the corresponding esters.     

Zn/H-ZSM-5催化剂上的二甲醚芳构化反应

 考察了 H-ZSM-5 和 Zn/H-ZSM-5 催化剂的二甲醚芳构化性能. 结果表明, H-ZSM-5 分子筛催化剂酸性的增强和酸中心的增多有利于二甲醚芳构化. 当在 H-ZSM-5 催化剂中加入 2% Zn 时, 在 360 oC 下反应时总芳烃收率从 50.0% 增加至 66.2%, C8 芳烃收率从 28.6% 增加到 39.0%. 反应温度升高到 480 oC 时, 总芳烃收率增加至 78.0%.