超细ZrO3催化剂的织构和晶相结构对合成甲醇,异丁醇的影响

采用超临界干燥法制备ＺｒＯ２超细催化剂，用于一氧化碳加氢合成甲醇，异丁醇。考察了催化剂的焙烧温度，焙烧时间以及碱金属助剂对合成醇性能的影响，并结合Ｎ２吸附，ＴＥＭ，ＸＲＤ表征，研究催化剂的织构，体相结构与催化活性的关系。发现随着催化剂焙烧温度升高，焙烧时间的延长，ＺｒＯ２由四方晶型向单斜晶型转变；浸渍Ｋ２ＣＯ３在焙烧过程中能够稳定ｔ－ＺｒＯ２，浸渍Ｎａ２ＣＯ３则促进四方晶型向单斜晶型的转变。     

用晶型超细粒子ZrO2制备SO4^2^—／ZrO2超强酸催化剂的研究

用超临界流体干燥法制备了超细粒子晶型ZrO_2,并用稀H_2SO_4溶液对其进行处理,制得了对甲醇转化反应具有高活性的SO_4~(2-)/ZrO_2超强酸催化剂.首次发现,晶型金属氧化物ZrO_2,当它是超细粒子(粒径<0.1μm)时,同样可以用H_2SO_4溶液浸渍的方法制得SO_4~(2-)/ZrO_2固体超强酸.这一事实同时还说明,超细粒子与非超细粒子不仅在某些物理性质上有较大区别,而且在化学性质上也有差别.     

制备参数对ZrO2气凝胶超细粉织构和结构性质的影响 Ⅱ.老化时间…

用超临界流体干燥（ＳＣＦＤ）法制备ＺｒＯ２气凝胶超细粉，详细考察了各个制备参数对其织构和结构性质的影响。结果表明，制备大孔高比表面ＺｒＯ２气凝胶超细粉较适宜的条件为：水凝胶在母液中老化时间尽可能长，锆盐溶液浓度～０．１７ｍｌ／ｌ，醇水交换度达到醇凝胶液相水含量～２．５２Ｗ％，操作温度～２６０℃，操作压力℃７．５ＭＰａ。     

制备参数对ZrO2气凝胶超细粉织构和结构性质的影响 Ⅰ.水凝胶pH值

用超临界流体干燥（ＳＣＦＤ）法制备出大孔高比表面ＺｒＯ２气凝胶超细粉，详细考察了初始水凝胶ｐＨ值对ＺｒＯ２超细粉形貌、晶相组成、颗粒大小与分布、比表面积及孔结构等织构和结构性质的影响。在实验范围内，当水凝胶ｐＨ值为１０．３０时，所制得的ＺｒＯ２超细粉具有最大的比表面积和孔体积，最小的表观堆密度和平均粒径，颗粒分布均匀狭窄，颗粒间连接成三维网络构状态，较好地保持了凝胶原始织构。     

单斜及四方晶相ZrO2催化CO加氢反应性能的比较

研究了以纯单斜（ｍ）和四方（ｔ）晶相ＺｒＯ２为催化剂的ＣＯ加氢反应．尽管两种晶相催化剂均有较高的低碳烯烃的选择性,但是也发现了两者催化性能的显著差别．ｍ－ＺｒＯ２催化剂对异丁烯有突出的选择性,而ｔ－ＺｒＯ２催化剂,则只有乙烯和丙烯,几乎没有Ｃ４烯烃的选择性．室温下ＣＯ吸附的原位ＩＲ谱测试可见,只有在ｔ－ＺｒＯ２催化剂上观测到不可逆含氧吸附物种．吡啶吸附的Ｒａｍａｎ谱显示出它们之间表面性质的差别,ｍ－ＺｒＯ２催化剂表面存在等强度的Ｌｅｗｉｓ和Ｂｒｏｎｓｔｅｄ酸中心,而在ｔ－ＺｒＯ２催化剂表面几乎只有Ｂｒｏｎｓｔｅｄ酸中心．催化过程的一些模型分子电子结构计算也表明了ＺｒＯ２催化剂对低碳烯烃选择性内在的电子结构条件．我们推测ＣＯ在ｍ－ＺｒＯ２催化剂表面的孪式吸附物种可能是导致异丁烯产物的根源     

Fe助剂对Cu/ZrO2甲醇水蒸气重整制氢催化剂的影响

利用XRD、TPR和EXAFS等手段，研究了Fe助剂对Cu/Fe2O3/ZrO3催化剂物化特性的影响，同时研究了对甲醇水蒸气重整反应活性和选择性的影响。结果表明，Fe对Cu/ZrO2催化剂结构有一定的修饰作用。添加Fe助剂后，铜的分散度提高，催化剂的起始还原温度提前，还原温度区间缩短；同时甲醇水蒸气重整制氢反应催化活性上升，氢选择性提高，产物中CO含量降低，但铁铜比应有一最佳值。     

ZrO2及SO^2—4／ZrO2超强酸催化剂的XRD分析

用ＸＲＤ技术从定性和定量上对ＺｒＯ２，特别是ＳＯ＾２－４／ＺｒＯ２超强酸催化剂的物相和四方相ＺｒＯ２的含量进行了详细的考察。结果表明，ＳＯ＾２－４的引入使ＳＯ＾２－４／ＺｒＯ２的晶化温度比ＺｒＯ２大约提高了１００Ｋ，并且使亚稳态四方相ＺｒＯ２得以稳定。亚稳态四方相ＺｒＯ２的含量主要受处理液浓度和焙烧温度的影响。处理液浓度越大，四方相含量越高；焙烧温度越高；四方相含量越低。强酸性的Ｈ２ＳＯ４溶液比弱     

催化剂制备条件对碳纳米管的影响

用柠檬酸络合法制备的Ni-La-Mg型催化剂催化裂解甲烷合成碳纳米管，并通过测定活性镍表面积研究了催化剂制备过程中柠檬酸浓度及活化温度对碳纳米管生成的影响，TEM测定结果表明，经凝胶自燃烧产生的催化剂，可通过改变柠檬酸的浓度来制得不同粒径的催化剂颗粒，从而获得一定管径的碳纳米管，另外，在500－700℃内，活化温度对催化剂活性影响不大，只有在较低或较高温度时对活性才有较大的影响。     

液相沉淀法在有机溶剂中制备ZrO2超细粒子的研究

以氧氯化锆（ＺｒＯＣｌ２·８Ｈ２Ｏ）为原料在有机溶剂中用液相沉淀法制备了ＺｒＯ２超细粒子，运用透射电镜（ＴＥＭ）、Ｘ射线衍射（ＸＲＤ）、差热热重（ＤＴＡＴＧ）等分析手段对粉体ＺｒＯ２进行了表征。结果表明，ＺｒＯ２粒子颗粒均匀、分散性良好，平均粒径为２５ｎｍ。实验还发现，制备过程在有机溶剂中进行，并采用低温热处理的方法可以有效地排除溶胶中水的影响，从而消除了合成粉体中硬团聚体生成的现象。     

Crystal Structure of a New Cembranolide Diterpene

ＩｎｔｒｏｄｕｃｔｉｏｎＳｏｍｅｃｅｍｂｒａｎｏｌｉｄｅｄｉｔｅｒｐｅｎｅｓｗｅｒｅｉｓｏｌａｔｅｄｆｒｏｍＳｉｎｕｌａｒｉａｇｅｎｕｓｅｓ[1— 5] .ＴｈｅａｕｔｈｏｒｓｈａｖｅｉｓｏｌａｔｅｄａｎｅｗｃｅｍｂｒａｎｏｌｉｄｅｄｉｔｅｒｐｅｎｅｆｒｏｍｔｈｅｓｏｆｔｃｏｒａｌＳｉｎｕ ｌａｒｉａｃａｐｉｌｌｏｓａＴｉｘ . Ｄｕｘ .[4 ] .Ａｌｍｏｓｔａｔｔｈｅｓａｍｅｔｉｍｅ ,ｗｅｏｂｔａｉｎｅｄｔｈｉｓｃｏｍｐｏｕｎｄｆｒｏｍａｎｏｔｈｅｒｓｐｅｃｉｅｓｏｆｓｏｆｔｃｏｒａｌ,Ｓｉｎｕｌａｒｉａｔｅ…     

Crystal Structures,Dimorphism and Lithium Mobility of Li7MO6 (M = Bi,Ru, Os)

Li₇MO₆ (M = Bi, Ru, Os) have been synthesized by solid state reaction of Li₂O with Bi₂O₃, or MO₂ (M = Ru, Os) and characterized using powder X‐ray diffraction, differential scanning calorimetry, magnetic susceptibility (for M = Ru, Os), ionic conductivity and ⁶Li solid state NMR (for M = Bi) measurements. All three compounds exhibit a temperature induced triclinic – rhombohedral phase transition. Structures of the new low temperature triclinic phases have been refined by the Rietveld method from powder X‐ray data using atomic parameters of Li₇TaO₆ as a starting model ( Li₇BiO₆ : triclinic, , a = 5.5071(1), b = 6.0425(1), c = 5.5231(1) Å, α = 116.912(1), β = 120.867(1), γ = 62.234(1)°, V = 133.96(1) ų, Z = 1, T = 230 K; Li₇RuO₆ : triclinic, , a = 5.3654(1), b = 5.8584(1), c = 5.3496(1) Å, α = 117.182(1), β = 119.117(1), γ = 62.632(1)°, V = 124.43(1) ų, Z = 1, T = 295 K; Li₇OsO₆ : triclinic, , a = 5.3786(1), b = 5.8725(1), c = 5.3591(1) Å, α = 117.193(1), β = 119.277(1), γ = 62.700(1)°, V = 125.15(1) ų, Z = 1, T = 295 K). Upon cooling, Li₇RuO₆ and Li₇OsO₆ undergo a magnetic transition at 12 and 13 K, respectively, from the paramagnetic to the antiferromagnetic state. The higher ionic conductivity of Li₇BiO₆ at T < 300 °C, as compared to Li₇RuO₆ and Li₇OsO₆, can be ascribed to the undergoing of the triclinic – rhombohedral transition at a much lower temperature. At T > 300 °C, the ionic conductivity of all three compounds increases sharply due to the melting of the lithium sublattice; for Li₇RuO₆ and Li₇OsO₆ the latter effect is superimposed by the phase transitions to the rhombohedral modifications.     

X射线粉末衍射技术在酞菁同质多晶异构体研究中的应用

综述了无金属酞菁的晶体结构的研究状况、晶体类型的划分,并对晶型存在的合理性进行了初步探讨。     

Synthesis,Crystal Structures,and Optical Properties of AM2(OH)(SeO3)2 (A = Na,Rb; M = Mg,Zn)

Sodium magnesium selenite NaMg₂(OH)(SeO₃)₂ and rubidium zinc selenite RbZn₂(OH)(SeO₃)₂ were prepared by hydrothermal reactions. The crystal structures of the title compounds were determined by single‐crystal X‐ray diffraction. NaMg₂(OH)(SeO₃)₂ crystallizes in the orthorhombic space group Pnma (no. 62) with lattice parameters a = 13.1919(10), b = 6.0415(4), c = 8.2182(6) Å, and Z = 4 and RbZn₂(OH)(SeO₃)₂ crystallizes in the triclinic space group P$\bar{1}$ (no. 2) with lattice parameters a = 4.8698(5), b = 7.3446(8), c = 11.7796(12) Å, α = 82.554(3), β = 78.456(2), γ = 71.603(3)°,and Z = 2. The structure of NaMg₂(OH)(SeO₃)₂ is a three‐dimensional framework consisting of edge‐sharing MgO₆ octahedra and trigonal pyramidal SeO₃^2– groups, whereas the structure of RbZn₂(OH)(SeO₃)₂ is a two‐dimensional layers structure consisting of corner‐sharing [Zn₂O₇] dimers linked by trigonal pyramidal SeO₃^2– groups. The compounds were characterized by the solid state UV/Vis/NIR diffuse reflectance, and FT‐IR spectroscopy.     

Crystal Structure Investigations and Thermal Behavior of the Five‐Leg Spin Ladder Compound La8Cu7O19

La₈Cu₇O₁₉ was synthesized by solid state reaction of the oxides La₂O₃ and CuO at 1288 K in air. The crystal structure was determined by a joint Rietveld refinement of X‐ray and neutron powder diffraction data. La₈Cu₇O₁₉ crystallizes in the monoclinic space group C2/c (No. 15) with the lattice parameters a = 13.8310(4)Å, b = 3.75827(9)Å, c = 34.5917(8)Å and β = 99.332(2)°. La₈Cu₇O₁₉ is the n = 3 member of the homologous series La_4+4nCu_8+2nO_14+8n. The Cu—O sub‐structure in La₈Cu₇O₁₉ contains infinite ribbons, which can be described as perovskite type layers with a width of n = 3 Jahn‐Teller‐elongated octahedra, and Cu—O planes of complex geometry. DSC/TG‐measurements in different gas atmospheres show peritectic decomposition of La₈Cu₇O₁₉. The anisotropic thermal expansion of the lattice parameters was investigated using synchrotron radiation. The Madelung part of lattice energy was calculated and compared with the corresponding values of other lanthanum cuprates.     

一种新型间位聚芳醚酮的晶体结构

聚醚醚酮 (PEEK)自英国 ICI公司开发并工业化以来 ,由于其优异的性能已在机械、航天等领域得到广泛应用 .但 PEEK的 Tg 只有 41 6K,影响了使用范围 .因此其它聚芳醚酮类聚合物相继被开发出来 .但这些聚芳醚酮的主链结构大都为全对位连接 ,使其熔点较高以至加工难度增大 .如果在聚合物主链结构中引入间位结构 ,则可在对玻璃化转变温度影响较小的情况下降低熔点来改善加工条件[1,2 ] .新型间位聚醚酮醚酮酮 (PEKEKm K)是其中一种 ,其玻璃化转变温度 Tg 为 41 7K,Tm 为 5 82 K.无论熔体结晶、冷结晶和溶剂诱变结晶 ,PEKEKm K都只出…     

(Ba6O)(ReN3)2: Synthesis,Crystal Structure and Physical Properties

The reaction of a mixture of barium and rhenium (3:1) at 850 °C under flowing nitrogen yielded the nitride‐oxide (Ba₆O)(ReN₃)₂ (R (No. 148); a = 8.1178(2) Å, c = 17.5651(4) Å; V = 1002.43(5) Å³; Z = 6). According to a structure refinement on X‐ray powder diffraction data, this compound is isostructural to a recently described nitride‐oxide of osmium of analogous composition. The structure consists of sheets of trigonal ReN₃ units and trigonal antiprismatic Ba₆O groups. The Ba–O distance of 2.73 Å is close to the sum of the respective ionic radii. The trigonal ReN₃^5– nitride anion displays a Re–N bond length of 1.94 Å, and is planar within the limits of experimental error. The constitution of the anion was confirmed by IR and Raman spectroscopy. The nitride‐oxide is stable up to 1000 °C, semiconducting (σ = 4.57 × 10^–3 Ω^–1 · cm^–1 at RT), and paramagnetic down to 25 K. A Curie–Weiss analysis resulted in a magnetic moment of μ = 0.68 μ_B per rhenium atom.     

雷公藤内酯甲的制备和晶体结构

从雷公藤(TripterygiumwilfordiiHook.F.)根心部分的乙醇提取液中,采用硅胶柱色谱法和TLC方法得到纯的雷公藤内酯甲(WilforlideA).用IR,¹HNMR和元素分析表征,并测定其单晶结构.化合物分子式为C₃₀H₄₆O₃,M_r=454.70,晶体属正交晶系,P2₁2₁2₁空间群,晶胞参数:a=0.732(4)nm,b=1.283(7)nm,c=2.693(6)nm,V=2.5327nm₃,Z=4,D_c=1.192g·cm^-3,μ(MoKα)=0.695cm^-1,F(000)=1107,R=0.039,R_W=0.044,分子为五环三萜γ-内酯.分子中C22-C23为烯键,C11连有羟基,C33_O3为羰基,整个分子呈起伏状,不在同一平面内.从AM1计算结果可以看出,仲羟基中的O1及γ-内酯中的O3原子净电荷大,致使分子极性较大,易在O1和O3部位发生亲核反应和氧化还原反应,显示分子的反应活性     

The Crystal Structures of the High‐temperature Phases of Ag4Mn3O8

Two endothermic, reversible structural phase transitions of first order have been observed in Ag₄Mn₃O₈ by means of in‐situ powder diffraction and by differential scanning calorimetry. At a temperature of T = 477 K, Ag₄Mn₃O₈ undergoes a structural phase transition from the room temperature phase in space group P3₁21 to a phase in space group R32, and at T = 689 K a second phase transition to a structure in space group P4₃32 occurs. Whilst the Mn₃O₈ framework does not change significantly upon heating, rearrangements of the silver atoms, located in the cavities of the framework, were found to be the driving force behind the transitions. The structural changes with increasing temperature proceed along a path of minimal group‐supergroup relations between the respective space groups.