莫来石纤维多孔陶瓷负载性能研究

用酸性偏磷酸盐作粘结剂、加压排液法成型制备了孔隙率高达96％的莫来石纤维多孔陶瓷，采用真空浸渍法，对其负载稀土复合金属氧化物La0.8Sr0.2CoO3的性能进行了研究，考察了浸渍时间、浸渍次数对负载量的影响，得出最佳浸渍时间为60min，浸渍次数为2次。通过扫描电镜(SEM)表征了内部架构，最后指出莫来石纤维多孔陶瓷有望成为具有较好效果的新型催化剂载体。     

钴基催化剂F-T合成的产物分布及稳定性研究

采用浸渍法制备了氧化锆改性γ-Al2O3负载Co-Ru双金属催化剂.在固定床反应器中考察了反应温度、压力、空速和合成气H2/CO比对烃产物分布的影响,进行了552 h的稳定性实验.结果表明,较低的反应温度、较高的压力和较低的空速有利于碳链增长,产物中柴油馏分C12～C18和蜡C19 的选择性高;原料气H2 / CO比提高,甲烷、C2～C4、C5～C11的选择性增加,C12～C18和C19 的选择性下降;在原料气H2/CO比1.58～2.0、反应温度453～513 K、压力1.0～2.5 MPa和空速500～1000 h(1催化剂具有较好的合成重质烃反应性能.在原料气H2 / CO比2.0、反应温度493K、压力1.5 MPa和空速800 h(1下,反应552 h,催化剂的稳定性较好,CO的转化率、C5 选择性分别大于80%和83%.运行时间对产物烃的分布影响不大,产物烃主要有烷烃组成,主要集中在C5～C18,选择性的平均值C1为6.94%,C2～C4 6.20%,C5～C11 33.04%,C12～C18 31.55%,C19 22.27%.     

The Calcia–Zirconia Phase Diagram Revisited: Stability of the Ordered Phases φ1 and φ2

Single crystals of CaO-stabilized ZrO₂ containing between 15.3 and 18.9 mol% CaO were heat-treated for 5000 h at 1200°C to study the stability of the ordered defect-fluorite phase, CaZr₄O₉ (φ₁). Subsequent TEM analysis of the equiaxed φ₁ domains in samples richer than approximately 18 mol% in CaO showed a random distribution of φ₁ variants, with no preferred interfacial habit planes. A critical review of the literature, combined with the new data, supports the Stubican-Hellmann-Hannon version of the phase diagram in the region 15 to 26 mol% CaO and 1000° to 1400°C and strongly suggests that φ₁ is a stable phase in the ZrO₂-CaO systems.     

溶胶－凝胶法莫来石被覆SiC复合微粒子的制备

本文采用溶胶－凝胶法以组成为３Ａｌ２Ｏ３２ＳｉＯ２的混合溶胶分别于常压和压力条件下，对ＳｉＣ微细粉进行包覆处理，该涂覆层在低于１０００℃下经１ｈ热处理可结晶成莫来石层，研究了涂覆溶胶浓度、涂覆压力对涂层厚度、结晶化温度等的影响，涂覆后的ＳｉＣ微粉在中高温的表面抗氧化性明显提高     

The influence of sulfur dioxide on propane oxidation activity over supported platinum and palladium

Earlier studies have shown that sulfur dioxide and metal-support interaction can strongly influence propane oxidation over platinum. In particular, oxidation activity is enhanced when platinum is supported on sulfated -alumina or zirconia compared to -alumina. Therefore, it is of interest to compare the performance of palladium under the same experimental conditions. Four model catalysts were examined: Pt/-alumina, Pt/zirconia, Pd/-alumina and Pd/zirconia. The metal loading was kept at or below 0.05 wt% to emphasize changes in activity attributable to metal-support interaction. Reaction rates were measured with and without sulfur dioxide. Surface sulfation was analyzed by measuring acid strength and evaluating spectra obtained by Fourier-transform infrared spectroscopy. In contrast to platinum, sulfation does not promote propane oxidation on Pd/-alumina, and Pd/zirconia is less active than Pd/-alumina.     

Effect of Precursor and Solvent on Morphology of Zirconia Nanoparticles Produced by Combustion Aerosol Synthesis

Zirconia nanoparticles were synthesized using a flame-based system involving spray droplet combustion of different precursor solutions. The characteristics of the feed were varied by varying the precursor compound, precursor concentration, and solvent type, and by using droplets of different mean sizes. When large droplets were used, agglomerated particles were formed when an organometallic precursor was used and large cenospheric particles were produced when an inorganic precursor was used. Reduction of the droplet size to a number-mean droplet diameter of 3.2 μm resulted in the production of solid spherical particles regardless of the precursor type. When an inertial impactor was used to eliminate droplets larger than 2.3 μm, the large particles in the final product were eliminated and uniformly sized solid zirconia particles having a smaller mean size were produced. The final particle size did not vary with the concentration of the precursor, indicating that multiple ceramic particles resulted from each precursor-containing droplet.     

Relationship between Transformation Temperature and Time-Temperature-Transformation Curves of Tetragonal-to-Monoclinic Martensitic Transformation in Zirconia-Yttria System

The tetragonal → monoclinic ( t → m ) martensitic phase transformation in ZrO₂–0.5–4 mol% Y₂O₃ proceeds during isothermal aging at various temperatures from 350 to 800 K; i.e., the transformation increases sigmoidally with aging time. The time-temperature-transformation ( T - T - T ) curves show a typical C shape, with very high rate for lower Y₂O₃-content specimens, and the rate decreases with higher Y₂O₃ content. The transformation temperature ( M _s) of the t → m transformation obtained from dilatation curves during the cooling stage coincides well with C curves above the nose temperature. The t → m transformation should occur isothermally, as suggested by a nucleation and growth mode.     

Molecular design and characterization of catalysts for NO x selective reduction by hydrocarbons in the oxygen excess based upon ultramicroporous zirconia pillared clays

Approaches to design of zirconia pillared clays via control of the properties of pillaring species in solutions were elaborated. Structural features of pillars and Pt + Cu active components fixed at these nanoparticles were shown to determine catalytic properties of pillared clays in NO_x selective reduction by hydrocarbons in the oxygen excess.     

莫来石晶种对反应烧结ZrO2/莫来石复相陶瓷显微结构的影响

通过显微结构观察研究了莫来石晶种对反应烧结ZrO2/莫来石复相陶瓷显微结构的影响。研究结果表明：与不含晶种试样相比，添加Ma(d50=1.87μm)和Mb(d50=0.83μm)晶种试样的显微结构比较均匀，莫来石晶粒多呈等轴状，且大小均一，晶内型ZrO2和封闭气孔较少。添加晶种对莫来石晶粒有明显细化作用。但晶种添加量和晶种颗粒尺寸对反应生成莫来石的晶粒尺寸无明显影响。采用溶胶－凝胶法制备的莫来石晶种（Mc)使试样中长出了一定量的长柱状的莫来石晶粒。     

Acid-Base Properties of Zirconium, Cerium and Lanthanum Oxides by Calorimetric and Catalytic Investigation

The combined use of calorimetric and catalytic methods for the investigation of the acid-base properties of oxide systems is discussed with reference to the authors' work on pure and doped zirconia samples, ceria-zirconia and ceria-lanthana solid solutions. Adsorption microcalorimetry of ammonia and carbon dioxide had been used to characterize the samples, whose chemical and thermal history was taken into account. The catalytic behavior of these samples in the conversion of 4-methylpentan-2-ol, route to 4-methylpent-1-ene (starting product for the manufacture of polymers of superior technological properties), had also been studied. On the basis of the calorimetric data, a rationale for interpreting the data for the transformation of 4-methylpentan-2-ol is formulated, which takes into account the role of the concentration and strength of the sites in governing the competition among the various mechanisms for dehydration and dehydrogenation.