980 nm激发下Er3+/Yb3+共掺杂ZrO2-Al2O3粉末的上转换发光特性

通过固相反应法制备了Er3+/Yb3+共掺杂ZrO2-Al2O3粉末的样品,并对样品在980nm激光激发下的上转换发光特性进行了研究.从发射光谱可以发现,在可见光范围内有3个强的发光带,一个位于654nm附近的红光带和两个分别位于545nm、525nm附近的绿光带,分别对应于Er3+离子的以下辐射跃迁:4F9/2→4I15/2、4S3/2→4I15/2、2H11/2→4I15/2.其中又以Er3+离子的4F9/2→4I15/2跃迁产生的红色荧光辐射最强.对其上转换发光机制进行了分析,发现这三个发光过程都是双光子过程.对样品粉末进行了XRD检测,发现ZrO2主要以立方相为主,并且计算得到了这种立方结构的晶格常数.Al2O3固溶于ZrO2中,Al3+嵌入ZrO2后产生氧空位,导致ZrO2晶体的对称性降低,这种结构变化更有利于提高上转换效率,即上转换发光强度增强.     

碳化钨负载S2O8^2-/ZrO2固体超强酸催化剂上的正戊烷反应研究

首次研究了碳化钨负载S2 O2 -8 ZrO2 (PSZ)固体超强酸催化剂 (WC PSZ)上正戊烷的反应情况及影响催化剂活性的各种因素 ,并用GC MS ,XRD ,BET等手段分析了正戊烷反应产物和催化剂的物理化学性质等 .结果表明 :WC PSZ对正戊烷具有异构化和裂解的双重催化作用 .PSZ在负载适量碳化钨后对正戊烷反应的活性和选择性显著提高 ,显示出优于Pt PSZ催化剂的效果 ,碳化钨的负载量为 2 0 %的效果最佳 .适当的焙烧、活化和反应温度等条件是取得良好反应效果的关键     

共沉淀CuO-ZrO2复合氧化物分散态结构研究

用XRD、EXAFS、XPS表征了共沉淀法制备的CuO-ZrO2复合氧化物的分散态结构. 500 ℃焙烧的样品在一定组成范围内形成大体均匀的无定形态固溶体. CuO含量超过其在ZrO2中溶解度时，多余的CuO以CuO晶体形式存在；当ZrO2含量超过其在CuO中溶解度时，多余的ZrO2以四方相ZrO2晶体形式存在.焙烧温度达到800 ℃时，样品由单斜相ZrO2和CuO晶体组成.     

掺杂ZrO＿2的Pt／Al＿2O＿3表面氧性质及一氧化碳氧化性能研究

用ＴＰＤ－ＭＳ、ＴＰＳＲ－ＭＳ及ＣＯ氧化活性测定等方法研究了Ｐｔ／Ａｌ２Ｏ３和掺杂超细ＺｒＯ２的样品的表面氧脱出－恢复性能、ＣＯ表面氧化性能及催化氧化性能．结果表明，在Ｐｔ／Ａｌ２Ｏ３中掺杂ＺｒＯ２后，样品表面上的氧物种脱出和氧化恢复性能明显提高，脱氧量也明显增大；并发现在ＣＯ－ＴＰＳＲ过程中程脱物ＣＯ２的脱附量大小及峰顶温度次序与对ＣＯ的催化氧化活性也有一致的关系     

CO在Pd／ZrO2—Al2O3催化剂上表面反应性能的研究

用流动反应法和ＴＰＳＲＭＳ等技术研究了ＣＯ在Ｐｄ／γＡｌ２Ｏ３和含有ＺｒＯ２的催化剂上的吸脱附行为、表面反应及催化氧化活性，同时用ＸＲＤ技术测定了催化剂的物相结构。结果表明，在Ｐｄ／γＡｌ２Ｏ３催化剂中用浸渍法添加ＺｒＯ２或掺杂超细ＺｒＯ２后，催化剂的氧化活性均有明显提高；ＣＯＴＰＳＲ的实验结果表明，ＣＯ在氧化态Ｐｄ催化剂上程序升温脱附过程中主要与表面氧发生氧化反应，而在还原态Ｐｄ催化剂上发生歧化反应，并发现ＣＯ２的脱附量及脱附峰温次序与对ＣＯ的氧化活性有一致的对应关系。     

ZrO2对Mn—O／γ—Al2O3催化剂中表面氧性能的影响

用ＴＰＤ－ＭＳ和ＴＰＲ技术研究了Ｍｎ－Ｏ／γ－Ａｌ２Ｏ３和Ｍｎ－Ｏ／ＺｒＯ＋γ－Ａｌ２Ｏ３催化剂中表面氧的脱附、还原性能和再生氧化恢复性能，并用ＸＲＤ对催化剂的固相结构进行了表征。结果表明，Ｍｎ－Ｏ／γ－Ａｌ２Ｏ３或Ｍｎ－Ｏ／ＺｒＯ２＋γ－Ａｌ２Ｏ３催化剂上存在ＭｎＯ２、Ｍｎ２Ｏ３和少量Ｍｎ３Ｏ４物种。ＺｒＯ２的存在不影响Ｍｎ－Ｏ／γ－Ａｌ２Ｏ３的ＴＰＲ的ＴＰＤ的特征峰，但使ＭｎＯ２的量明显增加，     

纳米二氧化锆在甲醇合成催化剂Cu/Ga2O3/ZrO2中的作用

The introduction of mesoporous nanosize zirconia to the catalyst for methanol synthesis dedicates the nanosized catalyst and mesoporous duplicated properties. The catalyst bears the larger surface area, larger mesoporous volume and more uniform diameter, more surface metal atoms and oxygen vacancies than the catalyst prepared with the conventional coprecipitation method. The modification of microstructure and electronic effect could result in the change of the reduced chemical state and decrease of reducuction temperature of copper, donating the higher activity and methanol selectivity to the catalyst. The results of methanol synthesis demonstrate that the Cu^＋ is the optimum active site. Also, the interaction between the copper and zirconia shows the synergistic effect to fulfil the methanol synthesis.     

Direct Electrochemistry of Cytochrome c on EDTA-ZrO2 Organic-inorganic Hybrid Film Modified ElectrodesState Key Laborator3.＂ of Chemo／Biosensing and Chemometrics, Hunan Universit3; Changsha. Hunan 410082. China

A composite film of ethylenediamine tetraacetic acid (EDTA)‐ZrO₂ organic‐inorganic hybrid was prepared based on the chelation between Zr(IV) and EDTA. The direct electrochemical behavior of cytochrome c (cyt. c) at the hybrid film modified glassy carbon electrodes was investigated. The immobilized EDTA can promote the redox of heme in horse heart cyt. c which gives rise to a pair of reversible redox peaks with a formal potential of 40 mV (vs. SCE). The peak current increased linearly with the increase of cyt. c concentration in the range of 1.6 × 10^?6—8.0 × 10^?5 mol·L^?1 with the correlation coefficient of 0.996. Further investigation shows that metal ions can impede the electron transfer of cyt. c. The impediment capability of metal ions depends on their coordination capability with EDTA and their valence number.     

Analysis by DSC of the drying and sintering processes of alkoxide-derived SiO2–ZrO2 gels

The drying and sintering processes of SiO₂–ZrO₂ alkoxide-derived gels have been studied by means of DSC technique. In the drying process, most part of water and alcohols are removed from the gels. For the SiO₂ gel such elimination occurs at the end of the drying process, however for the ZrO₂ gel this elimination occurs during the whole drying time. An intermediate behavior is observed for the binary system SiO₂–ZrO₂ gels. In the sintering process, the DSC technique allows to determine the elimination of water and alcohols retained within the structure (open or close pores) and the well-known hydroxyl condensation of silica gel between 700° and 800°C is also observed. The ZrO₂ gel shows the final hydroxyl condensation at the heating temperature of 600°C. For the binary SiO₂–ZrO₂ gels, the hydroxyl condensation has been associated to the activation energy needed for the dissociation of silica hydroxyls. This energy decreases with the ZrO₂ concentration in the gel resulting in a sintering treatment of 500°C leading to the entire hydroxyl condensation for the gel with 75% ZrO₂–25% SiO₂.

By studying the temperature of the DSC peaks, it is possible to know the temperature at which most part of water and alcohols are leaving the gel, and these results can be used in order to select the corresponding drying or sintering schedules for obtaining a well-fabricated material.     

ZrO2修饰Cu催化剂还原以及反应过程中表面组成的变化

通过热分解法制备Cu模型催化剂,然后经浸渍制备ZrO₂/Cu催化剂,采用SEM、XPS考察了催化剂表面形态和组成,并采用in-situ Raman考察了催化剂在还原和吸附CO和水的过程中随时间的变化。结果表明,还原前Cu催化剂表面主要存在CuO物种,而在ZrO₂/Cu表面,除了CuO物种,还存在着大量的表面羟基物种。ZrO₂/Cu相对Cu更加容易还原为Cu⁰,同时,ZrO₂在催化剂表面聚集形成絮状态,而Cu催化剂还原后主要形成Cu₂O物种。Cu催化剂表面吸附CO后,除了形成Cu-CO外,Cu₂O物种均会迅速消失形成CO₂。Cu催化剂对水的作用比较弱,但是ZrO₂/Cu催化剂和水作用较强,并且通过Cu-OH中间物形成Cu₂O物种。