稀土盐酯化催化剂失活原因的探讨

实验发现，稀土盐作为酯化反应催化剂，重复使用时活性有较大幅度的下降。本文采用Ｘ射线衍射（ＸＲＤ）及程度升温分解（ＴＰＤＥ）等手段，结合四水硫酸铈（Ⅳ）催化合成乙醇单乙醚醋酸酯的反应活性测定，对鹇催化剂和经不同预处理的催化剂进行了研究，讨论了催化剂失活的原因。结果表明，四水硫酸铈（Ⅳ）的催化活性与表面质子酸性质有关。在反应过程中，催化剂发生结晶水的丢失，铈离子价态的降低及晶体结构的变化，使催化剂的质     

Nd(III) and Gd(III) Sorption on Mesoporous Amine-Functionalized Polymer/SiO2 Composite

The strong demand for rare-earth elements (REEs) is driven by their wide use in high-tech devices. New processes have to be developed for valorizing low-grade ores or alternative metal sources (such as wastes and spent materials). The present work contributed to the development of new sorbents for the recovery of rare earth ions from aqueous solutions. Functionalized mesoporous silica composite was synthesized by grafting diethylenetriamine onto composite support. The physical and chemical properties of the new sorbent are characterized using BET, TGA, elemental analysis, titration, FTIR, and XPS spectroscopies to identify the reactive groups (amine groups: 3.25 mmol N g⁻¹ and 3.41 by EA and titration, respectively) and their mode of interaction with Nd(III) and Gd(III). The sorption capacity at the optimum pH (i.e., 4) reaches 0.9 mmol Nd g⁻¹ and 1 mmol Gd g⁻¹. Uptake kinetics are modeled by the pseudo-first-order rate equation (equilibrium time: 30–40 min). At pH close to 4–5, the sorbent shows high selectivity for rare-earth elements against alkali-earth elements. This selectivity is confirmed by the efficient recovery of REEs from acidic leachates of gibbsite ore. After elution (using 0.5 M HCl solutions), selective precipitation (using oxalate solutions), and calcination, pure rare earth oxides were obtained. The sorbent shows promising perspective due to its high and fast sorption properties for REEs, good recycling, and high selectivity.     

微波溶样－ICP－AES法测定人发标准物质中15种超痕量稀土元素的研究

本文采用微波溶样，不经分离富集，直接用标准加入ＩＣＰ－ＭＳ法，测定人发标准物质中１５种超痕量稀土元素。选择了最佳样品预处理条件和测定的最佳仪器参数。检出限为０．００７～０．０２６ｎｇ／ｍＬ。用国家一级土壤标准物质（ＧＢＷ０７４０１和ＧＢＷ０７４０３）作为质控样，１５种痕量稀土元素的测得值与标准值很好地吻合，相对标准偏差（ＲＳＤ）为１．２％～５．４％。国家一级人发标准物质（ＧＢＷ０７６０１）中稀土元素的标准值仅有Ｌａ，Ｃｅ和Ｙ，本法测得值均落在标准值的置信区间内。其余１２个超痕量稀土元素本法也取得了较为满意的结果。     

稀土催化剂本体聚合异戊二烯的生胶性能

本体聚合与溶液聚合相比,具有能耗低,反应平稳,转化率高等特点。杨彩云等用稀土催化剂对异戊二烯(Ip)进行本体聚合,聚合转化率达80%以上,聚合物中无疑胶,且分子量分布较窄(M_w/M?<2)。本文报道和讨论本体聚合放大试验胶样的生胶特性。 异戊二烯胶样(BLn-IR)本所自制。溶液钛催化聚异戊二烯IR-1Q为日本JSR生产。天然橡胶(NR)系海南岛3~#烟片。门尼粘度按GB1232测定。应力-应变性能(23℃),用DL-1000B型电子拉力机测定,拉速500mm/min。玻璃化温度(T_g)用PE DSC-2C型仪测定,升温速率     

稀土金属氧化物对Y分子筛吸附脱硫性能的影响

以Y分子筛为母体,采用浸渍法制备了Y₂O₃/Y、CeO₂/Y和La₂O₃/Y三种吸附剂.以脱除正辛烷中的苯并噻吩为探针反应,考察了稀土金属氧化物负载量、吸附温度、吸附时间和剂油比对吸附剂脱硫性能的影响.结果表明,稀土金属氧化物最佳负载量为5%(质量分数),所得吸附剂在50 ℃、1 h、剂油比1∶30条件下,脱硫率均达到60%以上.甲苯的存在明显降低了吸附剂的脱硫性能.稀土金属氧化物在吸附过程中发生流失,在相同的条件下,三种稀土金属氧化物中,Y₂O₃的流失量最小,而CeO₂的流失量最大,CeO₂的流失量是Y₂O₃的10倍.     

Evaluating Electron-Transfer Reactivity of Complexes of Actinides in +2 and +3 Oxidation States by using EPR Spectroscopy

The possibility that the relative reactivity of complexes of actinide metals in the +2 and +3 oxidation states could be investigated by examining reactions between An^III and An^II species of Th and U with rare-earth metal reagents that provide EPR confirmation of electron transfer reactivity has been explored. Neither Cp’’₃Th^III nor Cp’’₃U^III will reduce Cp’’₃La^III or Cp’₃Y^III (Cp’=C₅H₄SiMe₃, Cp’’=C₅H₃(SiMe₃)₂). However, both [K(2.2.2-cryptand)][Cp’’₃Th^II] and [K(2.2.2-cryptand)][Cp’’₃U^II] reduce Cp’’₃La^III and Cp’₃Y^III to form [Cp’’₃La^II]¹⁻ and [Cp’₃Y^II]¹⁻, respectively, which were identified by EPR spectroscopy. The reverse reactions also occur which indicates that the reduction potentials are similar. [Cp’’₃La^II]¹⁻ reduces Cp’₃Y^III and the reverse Y^II/La^III combination also occurs. In both cases, the reactions generate EPR spectra indicative of multiple species in the mixtures of La^II and Y^II, which is consistent with ligand exchange and demonstrates that numerous heteroleptic complexes of these Ln^II ions exist.     

Preparation and Crystal Structure of a Rare-earth Salt Based on the Decavanadate (V_(10)O_(28)~(6-)): [Y(H_2O)_8]_2[V_(10)O_(28)]·9H_2O

1INTRODUCTION Contemporary interest in polyoxovanadates re-flects not only their attractive magnetic and electro-nic properties[1~3],but also the complex structural chemistry of vanadium with a variety of coordina-tion geometries and oxidation states[4].Decavana-date is a represent of the fully oxidized isopolyva-nadates.A number of compounds have been repo-rted and characterized[5~9],but it is found now that most of these polyvanadate salts coordinated with metal cations are actually eith…     

Rare-Earth Single Erbium Atoms for Enhanced Photocatalytic CO2 Reduction

The solar-driven photocatalytic reduction of CO₂ (CO₂RR) into chemical fuels is a promising route to enrich energy supplies and mitigate CO₂ emissions. However, low catalytic efficiency and poor selectivity, especially in a pure-water system, hinder the development of photocatalytic CO₂RR owing to the lack of effective catalysts. Herein, we report a novel atom-confinement and coordination (ACC) strategy to achieve the synthesis of rare-earth single erbium (Er) atoms supported on carbon nitride nanotubes (Er₁/CN-NT) with a tunable dispersion density of single atoms. Er₁/CN-NT is a highly efficient and robust photocatalyst that exhibits outstanding CO₂RR performance in a pure-water system. Experimental results and density functional theory calculations reveal the crucial role of single Er atoms in promoting photocatalytic CO₂RR.     

Preparation and Crystal Structure of a Rare-earth Salt Based on the Decavanadate (V10O286-):[Y(H2O)8]2[V10O28]·9H2O

The salt, [Y(H2O)8]2[V10O28]·9H2O, contains two discrete water-groups coordinated Y(III) cations, an isopoly complex ion, decavanadate (V10O286-) and nine additional water molecules, which are combined together by static electric forces and hydrogen bonds. The Y3+ is eight-coor- dinated with a square antiprism geometry. The single-crystal X-ray analysis reveals that the crystal crystallizes in triclinic, space group P with a = 9.1454 (18), b = 10.007(2), c = 12.772(3)(A),α = 68.86(3), β = 77.50(3),γ = 89.23(3)°, V = 1061.7(4)(A)3 and Z = 1.     

铅基稀土合金作为正极板栅的阳极膜性能

采用交流阻抗（EIS)、交流伏安（ACV）、循环伏安(CV)、腐蚀失重实验等方法研究了铅-钙-锡-铝-银合金中添加混合镧铈稀土在硫酸溶液中的阳极行为。 实验结果表明,混合镧铈稀土的添加能有效抑制阳极Pb(Ⅱ)膜的生长,降低Pb电极表面生成的Pb(Ⅱ)膜氧化膜电化学反应阻抗,改善阳极膜的导电性。 增强合金的耐腐蚀性能,并且增加析氧的过电位,抑制氧气的析出,降低电池的早期容量损失。 混合镧铈稀土的添加有利于提高电池的深循环寿命。 当镧铈混合稀土质量分数为0.5％时,各方面综合性能更优,效果更好。