Synthesis, Characterization and Thermochemistry of 2MgO：B2O3：1.5H2O

Introduction　　 2MgO·B2 O3(Mg2 B2 O5)and 2MgO·B2 O3·H2 Omightbepreparedaswhiskermaterials .12MgO·B2 O3·H2 OnamedszaibelyiteisamagnesiumboratemineralwithastructuralformulaofMg2 [B2 O4 (OH) 2 ].2 Itisdifficulttosynthesizethiscompoundinthelaboratory .Recently ,weobtainedasimilarcompound 2MgO·B2 O3·1 5H2 Owhenwetriedtopreparewhiskerof 2MgO·B2 O3·H2 Obythephasetransformationof 2MgO·2B2 O3·MgCl2 ·14H2 OinH3BO3solutionunderhydrothermalcondition .Itishope fultopreparewh…     

Yb2O3对Bi2O3-MoO3催化剂性能的影响

在Bi2O3-MoO3复合氧化物催化剂中加入Yb2O3，可明显提高异丁烯转化率和生成甲基丙烯醛的选择性，用XRD、FT-Raman光谱和SEM技术研究了催化剂的组成和性质，Bi2O3—MoO3催化剂的成分主要是α-Bi2Mo3O12，添加镱后出现了Yb2Mo3O12的吸收峰；且Bi2O3-MoO3-Yb2O3催化剂的FT—Raman光谱图在363cm^-1处出现了Yb—O伸缩振动峰，同时既Bi2O3-MoO3催化剂的铝-氧振动发生红移，表明镱的加入使铝-氧键的振动减弱，使Bi2O3-MoO3-Yb2O3催化剂有较高传递晶格氧给予异丁烯的能力，导致异丁烯转化率和生成甲基丙烯醛的选择性均显著提高。     

V2O5/γ-Al2O3和V2O5/SiO2负载型催化剂对异丁烷的催化脱氢性能

V2O5/γ-Al2O3和V2O5/SiO2负载型催化剂对异丁烷的催化脱氢性能;V2O5/γ-Al2O3; V2O5/SiO2; 异丁烷; 脱氢     

Y2O3包覆LiCo1/3Ni1/3Mn1/3O2的电化学性能

通过在硝酸钇水溶液浸渍并焙烧的简单工艺, 在LiCo1/3Ni1/3Mn1/3O2材料表面包覆了一层Y2O3. 采用X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM), 循环伏安(CV)和恒流充放电对包覆和未包覆的LiCo1/3Ni1/3Mn1/3O2进行了测试分析. 结果表明, Y2O3包覆并没有改变LiCo1/3Ni1/3Mn1/3O2的晶体结构, 只存在于LiCo1/3Ni1/3Mn1/3O2的表面; 与未包覆的材料相比, Y2O3包覆后的材料在高电位下具有更好的容量保持率和放电容量. CV测试表明, 包覆层的存在有效抑制了材料层状结构的转变及电极与电解液的负反应.     

尿素水解法制备球形磁性Al2O3复合材料

利用酸化法在磁性Fe3O4纳米粒子表面包覆SiO2膜,制备了Fe3O4/SiO2复合粒子。然后将该复合粒子超声分散在尿素和铝盐的混合溶液中,利用油中成型法制备出球形纳米磁性Al2O3复合材料,通过水热焙烧等工序处理得γ-Al2O3。实验中采用XRD、TEM、BET、AGM等方法对复合粒子的性能进行了表征,探讨了制备过程对产物晶型的影响、产物的孔结构变化和磁学性能。另外添加的SiO2膜阻止了磁性Fe3O4纳米粒子的进一步团聚,使得Fe3O4纳米粒子保持较小尺寸并均匀分散在产物中,复合材料表现出超顺磁性;同时SiO2膜防止了磁核部分与Al2O3包覆层在高温焙烧时发生反应;还起到加强粘结的作用,使得Al2O3在使用过程中不容易脱落。     

Ce0.67Zr0.33O2对CH4燃烧催化剂Fe2O3/Al2O3的改性作用

固定n（Ce）／n（Zr）比为0．67／0．33,用共沉淀法制得一系列CeO2-ZrO2-Al2O3固溶体,采用这些固溶体作载体,以Fe2O3为活性组分,用浸渍法制备了一系列催化剂,BET结果显示,将适量Ce0.67Zr0．33O2引入到Al2O3载体中有助于催化剂保持较高的比表面积,TPR结果显示,载体中引入适量的Ce0．67Zr0.33O2可以改善催化剂的氧化还原性能,XRD结果表明,Fe2O3在CeO2-ZrO2-Al2O3载体上呈现出良好的分散状况,老化前后催化剂的晶相结构基本无明显变化,特别是当载体中m（Ce0.67Zr0.33O2）：m（Al2O3）的值为1：2时,Fe2O3／CeO2-ZrO2-Al2O3催化剂在甲烷催化燃烧中显示出最佳的催化性能和抗高温老化性能。     

Fe2O3/YSZ-γ-Al2O3催化剂在甲烷催化燃烧中的催化性能研究

以Fe2O3为活性组分，γ-Al2O3，ZrO2-γ—Al2O3及YSZ—γ—Al2O3(YSZ是用Y2O3稳定ZrO2的催化剂载体)为载体，制备了3种甲烷燃烧催化剂．其中以YSZ—γ—Al2O3为载体的催化剂催化性能最好．XPS检测发现．ZrO2和Y2O3的存在可以增加和稳定Fe2O3的表面浓度，同时也可减弱Fe2O3与γ—Al2O3之间的相互作用．Fe2O3质量分数为10％的Fe2O3／YSZ—γ—Al2O3催化剂具有最佳的催化活性．XRD测试结果表明．该催化剂的活性与Fe2O3在载体上的分散状况有关．     

整体式Co3O4/YSZ-Y-Al2O3+CYZ催化剂上的甲烷催化燃烧

用质量比为32的YSZ-γ-Al2O3和CeO2-Y2O3-ZrO2的混合物(以YSZA+CYZ表示)作载体,制备了不同Co3O4含量的整体式甲烷燃烧催化剂,同时制备了分别以YSZA和CYZ为载体的催化剂作为对比,研究了它们老化前后的反应性能,并用BET,XPS,XRD,TPR等研究了催化剂的比表面、表面状态、晶相结构和还原性能.结果表明,YSZ-γ-Al2O3和CeO2-Y2O3-ZrO2混合载体能有效地抑制CoAl2O4的生成,并能充分发挥各自的优点,因此负载一定量的钴后表现出很高的甲烷催化燃烧活性和抗老化性,尤其是含8 wt%Co3O4的样品性能最佳,有望成为实用的甲烷燃烧催化剂之一.     

异丁烷脱氢V2O5/γ-Al2O3催化剂的研究

五氧化二钒;异丁烷脱氢V2O5/γ-Al2O3催化剂的研究     

SnO2+Sb2O3中间层的制备条件对Ti/SnO2+Sb2O3/PbO2阳极性能的影响

二氧化铅;SnO2+Sb2O3中间层的制备条件对Ti/SnO2+Sb2O3/PbO2阳极性能的影响     

Y2O3, La2O3, Sm2O3对氧化铝瓷烧结及力学性能的影响

研究了3种稀土氧化物对氧化铝陶瓷烧结性能和力学性能的影响.结果表明 含Y2O3,La2O3,Sm2O3的添加剂促进了氧化铝瓷的烧结,提高了氧化铝瓷的力学性能.Y2O3和Sm2O3掺量为0.50%,La2O3掺量为0.75%时氧化铝瓷在1600或1620 ℃保温2 h烧结,相对密度达98.9%以上,强度超过439 MPa,断裂韧性达5.15 MPa·m1/2以上.微观结构分析表明,Y2O3,La2O3,Sm2O3抑止氧化铝晶粒生长,细化晶粒,使晶粒尺寸较均匀形成致密化结构.     

Solubility in the systems KClO4-RbClO4-H2O,KBrO3-RbBrO3-H2O,KIO3-CsIO3-H2O,RbClO4-CsClO4-H2O,RbBrO3-CsBrO3-H2O,RbIO3-CsIO3-H2O at 25°

Conclusions The solubility in the systems KClO₄-RbClO₄-H₂O, KBrO₃-RbBrO₃-H₂O, KIO₃-CsIO₃-H₂O, RbClO₄-CsClO₄-H₂O, RbBrO₃-CsBrO₃-H₂O, RbIO₃-CsIO₃-H₂O was studied at 25°. In all cases the formation of continuous series of solid solutions was established.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2631–2634, December, 1971.The authors would like to express their gratitude to A. I. Vulikh for his constant interest in this work and his valuable advice.     

Structural, energetic, electronic, bonding, and vibrational properties of Ga3O, Ga3O2, Ga3O3, Ga2O3, and GaO3 clusters

The results of density functional theory based calculations on Ga3O, Ga3O2, Ga3O3, Ga2O3, and GaO3 clusters are reported here. A preference for planar arrangement of the constituent atoms maximizing the ionic interactions is found in the ground state of the clusters considered. The sequential oxidation of the metal-excess clusters increases the binding energy, but the sequential removal of a metal atom from the oxygen-excess clusters decreases the binding energy. The increase in the oxygen to metal ratio in these clusters is accompanied by increase in both electron affinity and ionization potential. The ionization induced structural distortions in the neutral clusters are relatively small, except those for Ga3O2. In anionic (cationic) clusters, the added (ionized) electron is shared by the Ga atoms, except in the case of GaO3. The vibrational frequencies and charge density analysis reveal the importance of the ionic Ga-O bond in stabilizing the gallium oxide clusters considered in this study.     

Thermodynamics of Cr2O3, FeCr2O4, ZnCr2O4, and CoCr2O4

High-temperature heat capacity measurements were obtained for Cr₂O₃, FeCr₂O₄, ZnCr₂O₄, and CoCr₂O₄ using a differential scanning calorimeter. These data were combined with previously available, overlapping heat capacity data at temperatures up to 400 K and fitted to 5-parameter Maier–Kelley C_p(T) equations. Expressions for molar entropy were then derived by suitable integration of the Maier–Kelley equations in combination with recent S^∘(298) evaluations. Finally, a database of high-temperature equilibrium measurements on the formation of these oxides was constructed and critically evaluated. Gibbs free energies of Cr₂O₃, FeCr₂O₄, and CoCr₂O₄ were referenced by averaging the most reliable results at reference temperatures of (1100, 1400, and 1373) K, respectively, while Gibbs free energies for ZnCr₂O₄ were referenced to the results of Jacob [K.T. Jacob, Thermochim. Acta 15 (1976) 79–87] at T = 1100 K. Thermodynamic extrapolations from the high-temperature reference points to T = 298.15 K by application of the heat capacity correlations gave Δ_fG^∘(298) = (−1049.96, −1339.40, −1428.35, and −1326.75) kJ · mol⁻¹ for Cr₂O₃, FeCr₂O₄, ZnCr₂O₄, and CoCr₂O₄, respectively.     

Deactivation of O2(A3Σ) by O2, O,and Ar

O₂ in the A³Σ_u⁺ state has been prepared in a discharge flow system by recombining oxygen atoms on a nickel surface. The decay of this excited state was followed by observing the emission between 280 and 400 nm. The wall deactivation was observed to approach unit efficiency. Rate constants were determined to be 0.9 × 10^?11, 2.9 × 10^?13, and 8.6 × 10^?16 cm³/molecule sec for the quenching of O₂(A³Σ_u⁺) by O, O₂, and Ar, respectively.     

Surface tension of CaO-Al2O3, CaO-SiO2, and CaO-Al2O3-SiO2 melts

A method for the approximation of the temperature-concentration dependence of the surface tension of CaO-Al₂O₃, CaO-SiO₂, and CaO-Al₂O₃-SiO₂ melts was suggested. The method was based on the statistical-thermodynamic model of associated solutions. A comparison of the calculated surface tensions of the melts with the available literature data showed that the suggested approach allowed the surface tension of liquid slags to be correctly predicted as a function of temperature and composition.     

Stability of O3 + N2, O3 + O2 and O3 + CO2 double hydrates: DFT study

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Density and surface tension of the systems CaO-FeO-Fe2O3-MgO, CaO-FeO-Fe2O3-ZnO and CaO-Fe2O3-Cu2O

The density and surface tension of melts of the systems CaO-FeO-Fe₂O₃ MgO at the temperature 1623 K, CaO-FeO-Fe₂O₃-ZnO at 1573 K, and CaO-Fe₂O₃-Cu₂O at 1573 K were determined using the maximum bubble pressure method. The molar volume, the excess molar volume, and the excess surface tension were calculated on the basis of the obtained data. From these properties information on the interactions of components and possible chemical reactions between them was obtained. Due to the absence of silica and the low concentration of other network-forming oxides, only isolated FeO ₄ ⁵⁻ tetrahedra and the CaO·FeO ionic pairs are formed in these basic melts, the donor of the oxygen atoms being either CaO, FeO, or both CaO+FeO oxides. Even the observed ternary interactions may be attributed to the formation of the anions FeO ₄ ⁵⁻ only.     

Thermal Decomposition of CF3C(O)O2NO2, CClF2C(O)O2NO2, CCl2FC(O)O2NO2, and CCl3C(O)O2NO2

Haloacetyl, peroxynitrates are intermediates in the atmospheric degradation of a number of haloethanes. In this work, thermal decomposition rate constants of CF₃C(O)O₂NO₂, CClF₂C(O)O₂NO₂, CCl₂FC(O)O₂NO₂, and CCl₃C(O)O₂NO₂ have been determined in a temperature controlled 420 l reaction chamber. Peroxynitrates (RO₂NO₂) were prepared in situ by photolysis of RH/Cl₂/O₂/NO₂/N₂ mixtures (R = CF₃CO, CClF₂CO, CCl₂FCO, and CCl₃CO). Thermal decomposition was initiated by addition of NO, and relative RO₂NO₂ concentrations were measured as a function of time by long-path IR absorption using an FTIR spectrometer. First-order decomposition rate constants were determined at atmospheric pressure (M = N₂) as a function of temperature and, in the case of CF₃C(O)O₂NO₂ and CCl₃C(O)O₂NO₂, also as a function of total pressure. Extrapolation of the measured rate constants to the temperatures and pressures of the upper troposphere yields thermal lifetimes of several thousands of years for all of these peroxynitrates. Thus, the chloro(fluoro)acetyl peroxynitrates may play a role as temporary reservoirs of Cl, their lifetimes in the upper troposphere being limited by their (unknown) photolysis rates. Results on the thermal decomposition of CClF₂CH₂O₂NO₂ and CCl₂FCH₂O₂NO₂ are also reported, showing that the atmospheric lifetimes of these peroxynitrates are very short in the lower troposphere and increase to a maximum of several days close to the tropopause. The ratio of the rate constants for the reactions of CF₃C(O)O₂ radicals with NO₂ and NO was determined to be 0.64 ± 0.13 (2σ) at 315 K and a total pressure of 1000 mbar (M = N₂). © 1994 John Wiley & Sons, Inc.