Ce-Zr-O固溶体的制备和表征

采用硝酸盐直接分解法、共沉淀法、苹果酸溶胶 凝胶法和柠檬酸溶胶 凝胶法制备了Ce Zr O复合氧化物并进行了表征。溶胶 凝胶法制得的Ce Zr O为立方的Ce0 .5Zr0 .5O2 复合氧化物 (其中少量具有立方性质的t″相 ) ,而直接分解和共沉淀法制得的是由立方Ce0 .8Zr0 .2 O2 和四方Ce0 .2 Zr0 .8O2 固溶体组成的复合氧化物。不同制备方法制得的样品由于物相组成不同 ,还原性能也有较大差别。差热分析和X射线衍射分析结果表明 ,凝胶在燃烧的同时生成了Ce0 .5Zr0 .5O2 固溶体。     

Preparation of electrolyte membranes for micro tubular solid oxide fuel cells

Yttria-stabilized zirconia (YSZ) micro tubular electrolyte membranes for solid oxide fuel cells (SOFCs) were prepared via the combined wet phase inversion and sintering technique. The as-derived YSZ mi- cro tubes consist of a thin dense skin layer and a thick porous layer that can serve as the electrode of fuel cells. The dense and the porous electrolyte layers have the thickness of 3-5 μm and 70-90 μm, respectively, while the inner surface porosity of the porous layer is higher than 28.1%. The two layers are perfectly integrated together to preclude the crack or flake of electrolyte film from the electrode. The presented method possesses distinct advantages such as technological simplicity, low cost and high reliability, and thus provides a new route for the preparation of micro tubular SOFCs.     

Ce-Zr-O2上CuO分散性对CO氧化活性的影响

采用柠檬酸法制备了Ce-Zr-O₂固溶体, 并负载了过渡金属和贵金属Pt, 其中, 以Cu作为活性组分, 在CO氧化反应中表现出最高的活性, CO完全转化的温度约为120 ℃, 明显高于负载1%Pt(质量分数)催化剂的活性. 掺杂少量Zr到CeO₂(Ce_0.8Zr_0.2O₂)中对Cu基催化剂有非常好的促进作用. 分别采用等体积浸渍法(IW)、 沉淀沉积法(DP)、 水热法(HT)以及柠檬酸法(CA)制备了Cu负载质量分数为20%的Cu/Ce_0.8Zr_0.2O₂催化剂. 结果表明, 由沉淀沉积法制备的Cu/Ce_0.8Zr_0.2O₂催化剂的活性最高, 在100 ℃时, CO可完全转化. TEM结果表明, CuO物种很好地分散在Ce_0.8Zr_0.2O₂上. 吸附实验数据表明, Cu基催化剂上CO与O₂之间较弱的竞争吸附是其活性高于Pt催化剂的主要原因. Cu基催化剂上的氧空位对促进O₂的吸附具有重要作用, 也是影响CO低温氧化的重要因素之一.     

Sintering behavior and ionic conductivity of Ce<Subscript>0.8</Subscript>Gd<Subscript>0.2</Subscript>O<Subscript>1.9</Subscript> with a small amount of MnO<Subscript>2</Subscript> doping

A 20% GdO_1.5 doped ceria solid solution with a small amount of MnO₂ doping (≤5% molar ratio) was prepared via the mixed oxide method from high-purity commercial powders with grain size around 0.2–0.5 μm. X-ray diffraction analysis indicated that all the samples exhibited the fluorite structure, and no new phase was found. The data from dilatometeric measurements and scanning electron microscopy observations revealed that 1% Mn doping reduced the sintering temperature by over 150 °C, and enhanced the densification and grain growth. Mn doping has little effect on grain interior conductivity, but a marked deterioration in grain boundary behavior is observed. This leads to a lower total conductivity in comparison with the undoped Ce_0.8Gd_0.2O_2–δ. Therefore, for solid oxide fuel cells (SOFCs) with Mn-containing compounds as electrodes, optimization of electrode fabrication conditions is needed to prevent the formation of a lower conductivity layer at the electrode/electrolyte interface since Mn will diffuse from the electrode side to the electrolyte during fabrication and operation of SOFCs. Electronic Publication     

磁性纳米复合氧化物固体酸催化剂的制备及酯化性能

固体酸催化剂的无腐蚀、环境友好和可循环使用等特点使其成为无机液体酸的最佳替代物.磁性纳米固体酸具有优于常规固体酸催化剂的催化活性及分离简单的特性.用共沉淀法分别合成了一系列三组分TiO2-Al2O3-Fe3O4(TAF)和CeO2-Al2O3-Fe3O4(CAF)及四组分ZrO2--Al2O3-Fe3O4(ZACF)磁性纳米复合氧化物固体酸催化剂,通过电感耦合等离子体原子发射光谱、比表面积测定、X射线衍射、透射电镜、热重分析和红外光谱等对其进行了表征,并利用酯化反应作为探针反应评价了其催化性能.结果表明,合成的磁性纳米固体酸催化剂在酯化反应中表现出很好的催化活性.     

Diels-Alder reaction volumes in the solid state and solution

The densities of anthracene, tetracyanoethylene, maleic anhydride, N-phenylmaleineimide, trans, trans-1,4-diphenylbuta-1,3-diene, and their Diels-Alder adducts were measured in the solid state and in solution at 25 °C. The reaction volumes in the solid state were calculated from the difference in molar volumes. They turned out to be low, close to each other (–4 to –11 cm³ mol^–1), and slightly different from the reaction volumes (–8±1 cm³ mol^–1) calculated from the van der Waals radii. The reaction volumes in solutions (–15 to –32 cm³ mol^–1) were found from the difference in partial molar volumes of the reactants in dioxane, acetonitrile, and 1,2-dichloroethane, The experimental Diels-Alder reaction volumes in solution are determined not only by the formation of new bonds in an adduct: a considerably higher contribution (to 75%) is made by a change in the volume of intermolecular empty spaces in solution on going from reactants to adducts.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2386–2390, November, 2004.     

Preparation and characterization of ceria‐zirconia composite for enrichment and identification of phosphopeptides

Ceria‐zirconia composites at different molar ratios were synthesized. Several methods were used to characterize these composites, including X‐ray photoelectron spectroscopy, surface area and surface acid‐base property detection. A one‐step method for isolation and identification of phosphopeptides from peptide mixture was created using these ceria‐zirconia composites. Using tryptic digest of standard phosphorylated protein, we have shown that these enrichment and dephosphorylation activities are effective. The adsorption capacity and catalytic property of ceria‐zirconia composites at different molar ratios and calcinated temperatures were studied. In combination with MALDI‐TOF‐based peptide mass finger printing technique, we have established a method to utilize the enrichment/dephosphorylation dual properties of these ceria‐zirconia composites for the analysis of phosphoprotein in nonfat milk successfully.     

Snx.Ti1‐xO2 solid solution catalysts for nitrogen oxide selective catalytic reduction by propene in presence of oxygen

A series of SnO₂‐TiO₂ binary oxide catalysts prepared by co‐current precipitation method was found to be a novel and good system for the selective catalytic reduction of NO by propene in the presence of oxygen with high activity and good selectivity to N₂. The NO conversion to N₂ over SnO₂‐TiO₂ oxide catalysts varied with SnO₂ content and attainted a maximum at 65% over the catalyst with SnO₂ content at 40wt% for a feed with 1186 ppm NO, 948 ppm propene and 2.23% O₂, in He and a space velocity of 15000 h^?1 at 350°C. The SnO₂TiO₂ catalysts could sustain moderate activity in the presence of 10% steam. Because of the identical valence and the similar radius of Sn⁴⁺ and Ti⁴⁺, SnO₂‐TiO₂ binary oxides can form solid solution in three different phases as proved by XRD, electron diffraction and TPR. Sn⁴⁺ is the main active species in the SnO₂‐TiO₂ catalysts, and it is enriched on the solid solution surface as tested by XPS analysis. H₂‐TPR, NH₃‐TPD and BET tests show that SnO₂‐TiO₂ solid solution can dilute SnO₂ and suppress the activity of propene complete oxidation over SnO₂. This may be beneficial to the reactivity enhancement of NO conversion.     

硫酸化剂和制备方法对锆基固体酸催化剂的结构和性能的影响

采用沉淀法制备ZrO2氧化物,用氯磺酸和硫酸对其进行改性制备了Zr基固体酸催化剂,以XRD、BET和NH3-FTIR等手段考察了制备条件对催化剂晶相结构和表面性质的影响,研究了催化剂结构与其对棕榈油酯化反应的催化活性之间的关系.NH3-FTIR表明催化剂表面有B酸和L酸中心的生成.硫酸化剂的种类及其引入顺序都将影响催化剂的晶相结构和孔结构.酸的引入将阻止ZrO2·nH2O在焙烧时直接向单斜相ZrO2转变,氯磺酸将使ZrO2·nH2O转变为四方相ZrO2,而硫酸将导致四方相ZrO2和Zr(SO4)2·5H2O的生成.以氯磺酸改性的四方相和单斜相ZrO2基催化剂均具有很高的催化酯化活性,比硫酸改性的S-Z固体酸催化活性高.CS-ZrO2固体酸催化活性最高,在醇油比6:1、催化剂用量7 wt%、温度338 K和常压下反应2 h,棕榈油的酯化率可达98.9%.     

Three models for chain conformation of block copolymers in solution and in solid state

Solution properties of polystyrene-poly(methyl methacrylate) (PS-PMMA) diblock copolymer, polystyrene-poly(tertiobutyl methacrylate) (PS-PtBuMA) diblock copolymer, and poly(ethylene oxide)-polystyrene-poly(ethylene oxide) (PEO-PS-PEO) triblock copolymer have been measured by viscometry. The PEO-PS-PEO copolymer has been studied also in solid state by differential scanning calorimetry and by optical microscopy. All the block copolymers present a conformational transition in solution at a given temperature region which is relatively narrow. If below this transition temperature a copolymer adopts a segregated conformation (dumb-bell model), above this transition adopts a nonsegregated or pseudo-gaussian conformation, and vice versa. In the transition temperature region the copolymer adopts a compressed segregated conformation (core and shell model). If the passage from the solution to the solid state is performed in a given constant temperature in which the copolymer presents a segregated or nonsegregated conformation the same conformation is observed in the solid state (memory effect). © 1996 John Wiley & Sons, Inc.     

Electrostatic interaction between a charge-regulated particle and a solid surface in electrolyte solution: effect of cationic electrolytes

The effect of cations on the electrostatic interaction between a negative charge-regulated particle and a solid surface of constant negative potential in electrolyte solution is analyzed. Here, we assume that the rate of approach of a particle to a solid surface is faster than that of the dissociation of the ionogenic groups on the surface of particle. In other words, the effect of the time-dependent dissociation of ionogenic groups on the surface of a particle is taken into account. The result of the present study reveals that, although the solid surface is negatively charged, the presence of cations in the suspension medium has a negative effect on the rate of adhesion. The qualitative behaviors in the variation of the interaction force between a particle and a solid surface as a function of separation distance between them predicted by a kinetic model and the corresponding equilibrium model and constant charge density model are entirely different. The rate of approach of a particle to a solid surface is on the order (constant charge density model)>(kinetic model)>(equilibrium model).     

抽放煤层气（CH4-CO2-Air）制合成气的研究——固溶体的形成对NiO/MgO催化剂性能的影响

采用浸渍法制备了NiO/MgO催化剂，用TPR、XRD、BET、H2(O2)化学吸附等技术对催化剂进行了表征，对催化剂在甲烷空气部分氧化与CO2重整耦合制合成气反应中的催化性能进行了评价。结果表明，在800 ℃焙烧的催化剂中，NiO完全与MgO形成NixMg1－xO固溶体。与低温焙烧的NiO/MgO催化剂相比，虽然NixMg1－xO固溶体催化剂的还原度较低，但可以获得较高的金属分散度和较小的金属粒径，能有效抑制积炭的生成，在反应过程中显示出良好的活性稳定性。对于900 ℃焙烧的催化剂，由于形成了更多难还原的体相固溶体，催化剂的初活性较低。     

Al的加入对CeZr固溶体催化剂结构及其乙苯脱氢活性的影响

为进一步提高铈锆固溶体储放氧性能,增强乙苯二氧化碳氧化脱氢反应性能,采用共沉淀法合成出氧化铝质量比为50%的铈锆铝氧化物催化剂。通过现代仪器分析表征技术,研究了Al加入对铈锆固溶体复合氧化物晶体结构、储放氧能力的影响。结果表明,Al的加入可起到"扩散阻碍"作用,且有效抑制铈锆固溶体晶粒长大,使得铈锆铝氧化物催化剂比表面积较铈锆固溶体增加了51.8 m~2/g,储放氧性OSC值提高了69.4μmol/g,将铈锆铝氧化物催化剂用在乙苯氧化脱氢5 h反应中,发现乙苯转化率提高了10%。     

二氧化锆微球表面键合磺化交联聚苯乙烯固相萃取填料的制备及应用

以聚合诱导胶体凝聚法(PICA)制备二氧化锆微球,用钛酸酯偶联剂对其进行表面改性,使其接枝上碳碳双键基团。在溶液体系中,该双键与单体苯乙烯和二乙烯苯在自由基引发下交联聚合,形成的聚合物包覆在二氧化锆微球表面。再通过磺化方法将磺酸基离子连接到苯环上,得到阳离子交换固相萃取填料。通过红外光谱、扫描电镜/X射线能谱等手段对其进行了表征。将装填得到的固相萃取柱与高效液相色谱联用,测定了水中的甲基磺草酮、阿特拉津和乙草胺。3种化合物的色谱峰面积与质量浓度呈良好的线性关系,相关系数(r²)均大于0.99;甲基磺草酮、阿特拉津和乙草胺的检出限分别为5.41、6.72和13.4 μg/L。结果表明,制得的聚合物包覆二氧化锆微球的粒径为6~8 μm,用该填料制成的固相萃取小柱对3种目标物的吸附率高。     

Optimizing zirconia-based solid electrolyte cell operated as oxidizing reactor and chromatographic sensor

A zirconia-based (0.9ZrO₂ · 0.1Y₂O₃) high-temperature electrochemical reactor with three-electrode connection circuit was shown promising if used as a chromatographic sensor for quantitative organic gas detection as well as an organic gas sample preparation device for carbon isotopic analysis. The optimized parameters and working mode of the herein proposed solid electrolyte reactor provided complete organic gas oxidation to stoichiometric oxides without oxygen addition to the carrier gas flow at the temperature of 900 to 950°C. The maximum hydrocarbon gas sample amount was calculated for complete oxidation in the designed reactor. Due to its simple and reliable design, the solid electrolyte reactor can be used instead of a standard oxidizing reactor in an isotopic mass spectrometer.     

固态有机反应新进展

总结了一些典型的固态有机反应。由于固态反应的特性，多数固态有机反应表现出较溶液中更高的反应效率和更好的选择性，在某些情况下，利用光活性主体与反应物形成包结物，可实现对映选择性的不对称固态合成。     

CO oxidation on Ta-Modified SnO2 solid solution catalysts

Co-precipitation method was adopted to prepare Sn–Ta mixed oxide catalysts with different Sn/Ta molar ratios and used for CO oxidation. The catalysts were investigated by N₂-Brunauer–Emmett–Teller (N₂-BET), X-ray diffraction patterns (XRD), H₂-temperature programmed reduction (H₂-TPR), Thermal Gravity Analysis – Differential Scanning Calorimetry (TGA–DSC) techniques. It is revealed that a small amount of Ta cations can be doped into SnO₂ lattice to form solid solution by co-precipitation method, which resulted in samples having higher surface areas, improved thermal stability and more deficient oxygen species on the surface of SnO₂. As a result, those Sn rich Sn–Ta solid solution catalysts with an Sn/Ta molar ratio higher than 4/2 showed significantly enhanced activity as well as good resistance to water deactivation. It is noted here that if tantala disperses onto SnO₂ surface instead of doping into its lattice, it will then have negative effect on its activity.     

Thermodynamics of ionic solid solutions. A new treatment of existing distribution data

Excess amounts of two isomorphous salts, which differ with respect to only one ion (the exchanging ions), added to water and equilibrated produce an aqueous solution of the two salts and a solid solution of one salt in the other. The ratio of the two salts in the liquid phase is, in general, different from that in the coexisting solid. Data for twenty-nine such systems, including pairs of double salts (alums and picromerites), and pairs of simple salts, at or near 25°C, have been reviewed. By making the plausible assumption that the activity coefficients of the exchanging ions in the liquid phase are equal, it has been possible to derive the activity coefficients of the salts in the solid phase in addition to the thermodynamic equilibrium constants for the distributions. The interpretation of the data is compared with that of an earlier paper which drew different conclusions and was based on what is shown to be an erroneous premise. Solid solutions of alums are found, for the most part, to be ideal or nearly so. Of nine picromerite solid solutions containing sulfate as the only anion, seven pairs deviate positively from ideality, one deviates negatively, and one shows both positive and negative deviations. Three other picromerite pairs involving exchange of sulfate, selenate, and chromate ions, show only negative deviations. For the pairs [(NH₄)₂,K₂]SO₄, (NH₄,K)Cl, Ag(Cl,Br), K(Br,Cl), Rb(Br,Cl), (Rb,K)Br, and (Rb,K)Cl the deviations are positive; those for Pb(Cl,Br)₂ are negative, and those for Ba(ClO₃)₂·H₂O are both positive and negative. Independent supporting evidence for some of the conclusions is presented.     

Preparation and Characterization of Al8.31Si1.91Mg3.78O20/Al4.8Si1.2O9.6/Mg2.0Al4.02Si4.98O18 Multiphase Material

A two-step sintering method was used to prepare Al8.31Si1.91Mg3.78O20 (corundum solid solution)/Al4.8Si1.2O9.6 (mullite solid solution)/Mg2.0Al4.02Si4.98O18 (cordierite solid solution) multiphase material, for the purposes of making these three crystal structures have point defects which could help the particles diffuse and transfer at high temperature, accelerate the sintering efficiently and enhance the material strength as well as the bulk density. The impacts of different formulas on the structure and properties of the multiphase material were investigated. With XRD and SEM analyses, for each sample, the crystal structure and microstructure were characterized, the crystalline phase content and cell parameters were determined with Rietveld Quantification software, and the properties were tested. The comparative optimal formula determined was calcinated chamotte of 80wt% and calcinated sludge of 20wt%; and its corresponding bending strength and retention rate of bending strength after a thermal shock were 29.74 MPa and 80.15%, respectively.