Ln/TiO2催化剂的制备研究

目前中国广泛采用以三氧化二铝为载体、以金属盐作活性组分制备合成甲基异丙基酮的催化剂.合成甲基异丙基酮的关键是催化剂的制备技术.为了改善催化剂的选择性,提高合成产物的收率,以异丁酸和乙酸为原料、以In/TiO2为催化剂合成甲基异丙基酮.研究了催化剂活性组分、催化合成反应温度、原料异丁酸和乙酸的配比、催化剂的再生等因素对催化合成反应的影响.确定了合成甲基异丙基酮的最佳条件:稀土活性组分的质量分数15.0%,合成温度430～450℃,异丁酸与乙酸的物质的量比1.0:1.5,反应空速0.6～0.7h-1.在此条件下转化率>90%,催化剂选择性>80%.     

组成改性对BaO·Ln2O3·nTiO2介质材料温度稳定性的影响

在Ba4.5Nd9Ti18O54主相中引入Bi2O3,Pr2O3改性添加剂,考察了改性离子对材料温度稳定性的影响,研究表明:随Bi2O3含量的增长,介电常数εr显著提高,谐振频率温度系数τf呈V型变化,这与[TiO6]8-八面体畸变程度和Bi2O3在材料中的固溶限相关:在含Bi2O3的体系中引入适量的Pr2O3,温度稳定性得到较好改善,并提高了介电常数.     

Ln(B1/2Ti1/2)O3型微波介质陶瓷的研究进展

综述了Ln(B1/2Ti1/2)O3 (B=Mg, Zn, Co)型微波介质陶瓷的结构、低温烧结及改性研究现状. 少量烧结助剂可有效降低陶瓷的烧结温度,但有时会恶化品质因数(Q×f). 离子取代可显著提高Q×f值,对谐振频率温度系数(τf)无明显影响;而复合改性则可有效调节τf值至近0. 最后探讨了Ln(B1/2Ti1/2)O3型微波介质陶瓷研究中存在的问题和未来的发展趋势,简化和优化合成工艺、实现低温烧结和调节谐振频率温度系数、加强低温烧结、离子取代和复合改性的机理研究是未来重要的研究方向.     

空气中一次烧成Ln2O3掺杂SrTiO3GBBLC的研究

本文采用空气中一次高温还原烧成、快冷至中温氧化新工艺,系统地研究了稀土氧化物Ln_2O_3(Ln—La、Sm、Dy)掺杂对SrTiO_3半导瓷晶界阻挡层电容器(简称GBBLC)结构和性能的影响。获得了介电常数ε≥50000、介质损耗tgδ≤0.010、绝缘电阻率ρ≥10~(10)Ω·cm、介电常数温度系数(-25℃—85℃)α=±(10—12)％的La_2O_3掺杂SrTiO_3GBBLC_o其综合性能、稳定性、重复性好。实验结果表明:不同种类的La_2为_3掺杂对SrTiO_3显微结构和性能有很大彤响。提出了不同掺杂量时,Ln_2O_3掺杂SrTiO_2的晶粒缺陷机制。用XRD测定了Ln_2O_3掺杂SrTiO3的晶胞常数,SEM分析显示:Dy_2O_3、Sm_2O_3掺杂比La_2O_3掺杂的SrTiO_3晶粒生长缓慢,且Sm_2O_3掺杂的SrTiO_3晶粒生长呈取向分布。研究了非化学计量比对稀土氧化物掺杂SrTiO_2GBBLC的影响:探讨了烧成制度对性能的影响。     

稀土配合物[Ln(C3H7NO2)-x-(C3H4N2)(H2O)](ClO4)3(Ln=La,-x-=3;Ln=Pr,Nd,Sm,-x-=2)的合成、表征与热分析

合成了稀土高氯酸盐与咪唑、DL α 丙氨酸的4种配合物晶体。经傅里叶变换红外光谱(FTIR)、元素分析和化学分析测定后确定其组成为[Ln(C3H7NO2)x(C3H4N2)(H2O)](ClO4)3(Ln=La,x=3;Ln=Pr,Nd,Sm,x=2)。用差示扫描量热法(DSC)测定了4种配合物的热分解数据,4个配合物开始熔化分解的温度分别为502 5K,532 4K,495 7K,516 7K,配合物有较高的热稳定性。     

New hetero-dilanthanide complexes containing Ln1(fod)3 and Ln2(fod)3 fragments (Ln=Pr–Nd; Nd–Sm; Eu–Tb and Ho–Er) linked by bis-diimine bridging ligand

New hetero-dilanthanide β-diketonate complexes of the type [Ln¹Ln²(fod)₆(μ-bpm)] {fod is the anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione; bpm = 2,2′-bipyrimidine; Ln¹ = Pr and Ln² = Nd (1); Ln¹ = Nd and Ln² = Sm (2); Ln¹ = Eu and Ln² = Tb (3) and Ln¹ = Ho and Ln² = Er (4)} have been isolated by reacting sequentially, the coordinatively unsaturated Ln(fod)₃ chelates of two different lanthanides and 2,2′-bipyrimidine bridging ligand in 1:1:1 molar ratio, in ethanol. The purity and hetero-dilanthanide nature of the complexes has been confirmed by NMR, 4f–4f absorption spectroscopies and electrospray mass spectrometry. The oscillator strength of the hypersensitive transitions confirms the presence of the two different lanthanides in the complexes in 1:1 ratio. The complexes 2 and 3 display strong pink and red luminescences, respectively. The intramolecular Tb(III) → Eu(III) energy transfer has been observed in complex 3.     

Upconversion Luminescence in Yb/Ln (Ln = Er,Tm) Doped Oxyhalide Glasses Containing CsPbBr3 Perovskite Nanocrystals

Yb/Ln (Ln=Er, Tm) doped TeO₂-based glasses containing CsPbBr₃ perovskite quantum dots were successfully prepared via in-situ glass crystallization. The nanocomposites yield typical green downshifting luminescence attributing to CsPbBr₃ exciton recombination under UV excitation, and produce Er³⁺ green, Er³⁺ red and Tm³⁺ blue upconversion emissions under 980 nm laser excitation. Impressively, specific Ln³⁺ emissions will be quenched with the precipitation of CsPbBr₃ in glass, enabling to finely tune upconversion emitting color. Spectroscopic characterizations evidence that the luminescence quenching is originated from non-radiative reabsorption effect induced by the precipitation of CsPbBr₃ rather than energy transfers from Ln³⁺ to CsPbBr₃. Finally, these nanocomposites are demonstrated to exhibit superior water resistance due to the effective protecting role of dense structural glass, particularly, about 95% downshifting luminescence of CsPbBr₃ and upconversion luminescence of Er³⁺ related to pristine ones are retained after immersing the products in water up to 30 days.     

四元混配配合物[Ln(x-MBA)2(NO3)(Phen)]2的合成及表征

在酸性介质,乙醇／水混合溶剂中合成得到了三个系列的四元混配配合物[Ln(x-MBA)2(NO3)(Phen)]2(Ln=La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Er;MBA=CH3C6H4COO^-）。用元素分析、IR、UV、DTA－TG和^1H NMR等方法对配合物进行了表征,测量了三个Eu配合物的荧光光谱和三个Gd配合物的ESR谱。     

Ln2O3／X—13分子筛担载型催化剂在合成DOP中的催化活性

介绍了 Ln2 O3 / x- 13分子筛担载型催化剂的制备方法 ,并通过实验说明了 Ln2 O3 / x- 13分子筛在合成DOP(邻苯二甲酸二辛酯 )中的高催化活性     

稀土分子筛固体碱催化剂Ln（PO_2NH）_3的制备及其催化性能

文章报道合成了系列稀土分子筛固体碱催化剂Ln（PO2NH）3,通过XRD,IR,TG对其结构及热稳定性进行表征,并对其Knoevenagel催化性能进行研究。结果表明此催化剂具有二维的孔道结构,热稳定性较高,可在400℃以下保持有机胺碱性基团-NH稳定存在。对苯甲醛和氰基乙酸乙酯的Knoevenagel缩合反应表现出良好的碱催化活性,转化率范围在61%～66%。     

Synthesis,structure, and characterization of polymeric lanthanide 2-aminoterephthalate frameworks [Ln2(atp)3(H2O)2]·dmf·4H2O

X-ray crystallography reveals four isostructural lanthanide polymeric solids, [Ln₂(atp)₃(H₂O)₂]·dmf·4H₂O (atp = 2-aminoterephthalate; dmf = N,N′-dimethylformamide; Ln = La (1), Ce (2), Pr (3) and Nd (4), respectively) that are obtained from the solvothermal synthesis which are crystallized in an interesting 3D polymeric framework with a (4,4,6)-linked {4²·8⁴}{4⁴·6²}₂{4⁸·6⁶·8}₂ fsy net topology. Upon excitation at 350 nm, they all show the solid state ligand-centered luminescences but both 2 and 3 also exhibit the weak lanthanide-based characteristic emissions in the visible region at room temperature. The cyclic voltammetric investigation indicates that 2 exhibits appreciable electrochemical activity for formaldehyde.     

不同共混比Ln—BR／NR的性能

研究了稀土顺丁橡胶（Ｌｎ－ＢＲ）与天然橡胶（ＮＲ）以不同比例共混后生胶、混炼胶和硫化胶的性能，并与相同条件下的镍系顺丁橡胶（Ｎｉ－ＢＲ）／ＮＲ共混胶的性能进行了对比，结果表明，共混胶随Ｌｎ－ＢＲ用量的增大，ＭＬ＾１００℃１＋４降低，工艺行为良好，硫化胶力学性能、磨耗、湿滑指数和生热值下降，并且Ｌｎ－ＢＲ／ＮＲ硫化胶的抗湿滑性和动态疲劳性均优于Ｎｉ－ＢＲ／ＮＲ硫化胶。     

近紫外激发NaGd(WO4)2:Ln3+ (Ln=Tb,Dy, Sm,Eu )荧光粉的微波水热合成及发光性能研究

采用微波水热合成法,在不添加任何表面活性剂或者模版的条件下,快速合成了系列NaGd(WO4)2:Ln3+(Ln=Tb, Dy, Sm, Eu)荧光粉。探讨了pH值、反应温度和反应时间对样品物相结构、微观形貌及发光性能的影响。结果表明：反应体系pH值为8.0,在180 ℃下反应60 min即可合成四方晶系NaGd(WO4)2的纯相,且结晶良好,形貌为规整的四方盘。所合成的NaGd(WO4)2:Ln3+ 系列荧光粉的激发光谱均由两部分组成：200~300 nm的宽激发带归属于W-O、Ln-O之间的电荷转移;300~500 nm的系列尖峰归属于Ln3+的特征f-f跃迁。系列样品均可被近紫外光有效激发,当Ln3+为Tb3+、Dy3+、Sm3+和Eu3+时,分别呈现绿、黄、橙红和红光发射。     

Propane Oxidative Dehydrogenation Over Ln–Mg–Al–O Catalysts (Ln = Ce, Sm, Dy, Yb)

Ln–Mg–Al mixed oxide catalysts (Ln = Ce, Sm, Dy, Yb) were prepared from layered double hydroxide precursors, characterized using XRD, N₂ adsorption, TG-DTG, EDX, H₂-TPR and CO₂-TPD techniques and tested in the oxidative dehydrogenation of propane in the temperature range 450–600 °C. For all the catalysts the conversion increases with increasing the reaction temperature while the propene selectivity decreases to the benefit of carbon oxides for Ce-based system and of cracking products for the others. The best yields in propene were obtained with Dy- and Sm–Mg–Al–O catalysts. No correlation between the reducibility of the rare-earth cation and the catalytic performances was observed. A linear correlation between the catalyst basicity and the propene selectivity was evidenced.     

Ln(Ⅲ)-Zn(Ⅱ)(Ln=Eu,Tb)大环配合物的合成和荧光性质

以锌(Ⅱ)离子为模板分步合成法获得了大环配体单核锌配合物,在此基础上引入稀土离子获得Ln(Ⅲ)—Zn(Ⅱ)(Ln=Eu,Tb)杂核配合物。用IR、UV、ES—MS等手段对配合物进行了表征。Eu(Ⅲ)—Zn(Ⅱ)大环配合物在己腈溶液中检测到Eu(Ⅲ)离子特征荧光发射。     

NaLn(MoO4)2(Ln=La,Nd)纳米粒子的室温形貌控制合成

钼酸稀土钠盐具有吸收峰宽,阀值低,增益效果明显和发光效高等光学特点,因此近年来被广泛的应用于半导体激光泵浦源,发光二极管或固态激光器元件等方面。在本研究中,我们使用微乳液手段和水热手段对钼酸稀土钠盐纳米材料进行了合成,并使用XRD和TEM等测试手段对实验结果进行了表征与分析,通过改变外界反应条件实现了钼酸稀土钠盐的形貌控制合成。     

稀土配合物[Ln_2(sba)_3(phen)_2(H_2O)_2](Ln=Eu,Tb)合成、表征和性质研究

在乙醇和水的混合溶剂中,利用辛二酸[Suberic acid=H2sba]、邻菲罗啉(Phen)合成了标题化合物,通过化学分析、元素分析、红外光谱、热分解等方法对配合物组成进行了分析和表征,并研究了两种配合物的荧光性质。