双稀土氟氧化物Sm-La-O-F催化剂的AFM研究

双稀土氟氧化物Ｓｍ－Ｌａ－Ｏ－Ｆ具有良好的乙烷氧化脱氢（ＯＤＥ）催化性能，特别是对于Ｓｍ２Ｏ３－ＬａＦ３（１：１摩尔比），在９７３Ｋ，乙烯选择性为８９．７％，乙烯转化率为２２．１％，是目前报道的具有高乙烯选择性的ＯＤＥ反应催化剂之一。比表面 和ＸＲＤ测试表明，Ｓｍ２Ｏ３－ＬａＦ３催化剂体相是由单一相结构的双稀土氟氧化物Ｓｍ２／３Ｌａ１／３ＯＦ组成，比表面积较小，原子力显微镜（ＡＦＭ）研究表明，该催     

负载型Co-Cr氧化物催化剂上CO2氧化乙烷脱氢制乙烯反应的研究

制备了一系列不同Co／Cr比例的Co-Cr／SiO2和Co-Cr／γ-Al2O3催化剂，并应用XRD等技术对所制样品进行了表征．在常压连续流动固定床石英反应器中考察了它们对CO2乙烷氧化脱氢反应的催化性能．实验结果表明，Co-Cr／SiO2和Co-Cr／γ-Al2O对CO2乙烷脱氢制乙烯都有较高的催化活性，其活性都明显高于负载单一组分的催化剂．以γ-Al2O为载体的催化剂活性明显比以SiO2为载体的催化剂活性高．1％Co-5％Cr／γ-Al2O活性最高，973K乙烷的转化率达25．57％，乙烯的选择性和收率分别达94．28％、24．10％．     

稀土单氧化物发射光谱法的研究：Ⅰ.混合稀土浓集物中钐的双波长测定

报道了空气乙炔火争中ＳｍＯ发的发射光谱行为，试验了Ｌａ，Ｎｄ，Ｅｕ，Ｙ地ＳｍＯ发射强度增强作用大量Ｌａ存在下，ＳｍＯ的发射强度与其浓度成正比关系。     

激光促进钼、钒氧化物表面乙烷氧化脱氢反应规律的研究

制备了Ｖ２Ｏ５、ＭoＯ３和Ｖ２Ｏ５．ＭoＯ３复合氧化物催化剂,并进行了ＩＲ表征;对催化剂表面乙烷的吸附性能进行了ＩＲ和ＴＰＤ表征。用激光促进表面反应（ＬＳＳＲ）技术,考察了乙烷氧化脱氢生乙烷的反应规律。结果表明,氧化物表面的Ｖ＝Ｏ和Ｍo＝Ｏ键的吸附能力,在不同的激光激发频率下,ＬＳＳＲ反遵循吸附态激发机理或固体表面键激发机理。温度对ＬＳＳＲ反应有一定的辅助作用。     

阶跃过渡应答技术研究Mo-V/Al2O3催化剂上乙烷氧化脱氢制乙烯反应的暂态动力学Ⅰ.C2H6,O2,C2H4和CO2的催化剂上的吸附行为

用阶跃过渡应答技术研究了乙烷氧化脱氢反应的反应物Ｃ２Ｈ６，Ｏ２，产物Ｃ２Ｈ４和主要副产物ＣＯ２在ＭｏＯ３－Ｖ２Ｏ５／Ａｌ２Ｏ３催化剂上的吸附行为。结果表明：Ｃ２Ｈ６和Ｃ２Ｈ４在该催化剂上不吸附；氧为慢吸附、不可逆吸附；ＣＯ２为可逆吸附，吸附量较小。并发现在无氧的条件下，乙烷能与催化剂表面上的晶格氧反应生成乙烯。这些结果对乙烷氧化脱氢反应机理的探讨有重要意义。     

稀土氧化物固体碱催化剂的表面性质Ⅰ．稀土氧化物表面活性中心的表征

采用ＴＰＤ－ＭＳ，ＩＲ等技术研究了Ｌａ２Ｏ３，Ｙ２Ｏ３，Ｎｄ２Ｏ３，ＣｅＯ２及参照氧化物Ａｌ２Ｏ３，ＺｒＯ２，ＭｇＯ表面的酸碱性，氧活性及表面羟基．结果表明，上述稀土氧化物表面上不仅存在着两种碱中心，还有酸中心存在，且其表面都存在活性氧中心，表面的性质同碱土氧化物ＭｇＯ类似，但与Ａｌ２Ｏ３，ＺｒＯ２等有较大差别     

阶跃过渡应答技术研究Mo-V/Al2O3催化剂上乙烷氧化脱氧制乙烯反应的暂态动力学Ⅱ.乙烷氧化脱氢反应的机理和动力学参数的求取

通过一系列应答实验，证实了氧在ＭｏＯ３－Ｖ２Ｏ５／Ａｌ２Ｏ３催化剂上的吸附和吸附态氧转变为晶格氧的过程是慢过程，是乙烷氧化脱氢反应的速度控制步骤；乙烯的深度氧化是乙烯与催化剂表面上吸附态氧作用的结果，而不是与催化剂上晶格氧作用的结果。结合第Ⅰ部分的实验结果，提出了乙烷氧化脱氢制乙烯反应的机理，并用Ｔｒｅａｎｏｒ法和ＤＦＰ法求取了各基元步骤的速率常数、活化能和指前因子等动力学参数。用计算所得的结果进     

乙烷在钛酸盐复合氧化物上的氧化脱氢Ⅰ.锂掺杂对催化性能的影响

研究了掺杂钛酸盐催化剂用于乙烷氧化脱氢的催化行为，发现适量的Ｌｉ＾＋取代Ｔｉ＾４＋后可明显改善催化剂对乙烯的选择性。催化剂ＣａＴｉ０．９Ｌｉ０．１Ｏ３－δ在８５０℃时乙烷转化率和乙烯选择性分别为８７．８％和７１．７％，乙类的单程收经为６３．０％．催化剂Ｓｒ０．９Ｃａ０．１Ｔｉ０．９Ｌｉ０．１Ｏ３－δ可在极宽的温度范围内保持很高的乙烯选择性。     

稀土氟氧化物在丙烷,异丁烷氧化脱氢中的催化作用

稀土氟氧化物在丙烷、异丁烷氧化脱氢中的催化作用张伟德＊洪碧凤古萍英万惠霖蔡启瑞（厦门大学化学系，固体表面物理化学国家重点实验室，物理化学研究所厦门３６１００５）关键词丙烷，异丁烷，催化氧化脱氢，稀土氟氧化物１９９７－１０－０６收稿，１９９８－０１－０...     

氧化镍/莫来石-刚玉催化剂中添加La2O3的作用

用ＸＲＤ，ＴＰＲ，ＴＧ－ＤＴＡ考察了氧化镍／莫来石－刚玉催化剂添加Ｌａ２Ｏ３对ＮｉＯ性质的影响及两者间的相互作用，Ｌａ２Ｏ３使得催化剂中ＮｉＯ的晶格常数及分散容量增大，而晶相含量减少，还发现，添加Ｌａ２Ｏ３，使一次ＴＰＲ过程中ＮｉＯ还原温度升高，耗氢量增加了Ｌａ２Ｏ３对二次ＴＰＲ中ＮｉＯ还原温度的影响减小，耗氢量不受影响，Ｌａ２Ｏ３的添加方式及含量不同，对ＮｉＯ性质的影响也不相同。     

环氧化物稀土络合催化开环聚合动力学研究

用膨胀计方法研究环氧丙烷、环氧氯丙烷在稀土络合催化剂 Nd(P_(204))_3-Al(i-Bu)_3-H_2O作用下的聚合反应动力学,表明聚合反应速度对催化剂浓度及单体浓度均呈一级关系。环氧丙烷、环氧氯丙烷开环聚合反应活化能分别为61.3kJ/mol和48.9kJ/mol。在同样的聚合反应条件下,环氧氯丙烷聚合反应速度大于环氧丙烷聚合反应速度。 研究还发现,催化剂组成摩尔比Al/Nd及H_2O/Al对聚合反应速度均有一定影响;各种稀土元素络合催化剂催化活性顺序为:Nd>La>Dy>Yb>Eu;稀土络合物中配体对活性的影响为:acac>P_(204)>P_(507)>naph;烷基铝的影响为:Al(i-Bu)_3>AlEt_3。     

Determination of Ce,Pr, Nd and Sm in High Purity La2O3 by Inductively Coupled Plasma Atomic Emission Spectrometry

Abstract

High purity lanthanum oxide was analysed to determine traces of Ce, Pr, Nd, and Sm by employing inductively coupled plasma atomic emission spectrometry (ICP-AES). Lanthanum oxide was dissolved in nitric acid and the solution was nebulized into the plasma generated by a RF generator (56 MHz; 1.5kW). Analytical lines of Ce, Pr, Nd, and Sm, which were free of interference from the spectral lines of both La and the other rare earths, were scanned on a Jobin-Yvon, Model JY-38 THR-1000 1m-Czerny-Turner monochromator. Standards containing the four analytes (Ce, Pr, Nd, and Sm) in the concentration range 0.01–0.2 μg/ml and La at 2 mg/ml were used for calibration. Detection limits ranged between 6 and 16 ng/ml for the four analytes in aqueous solution.     

~(13)C核磁共振研究稀土催化剂聚合双烯的机理

用~(13)C-NMR 方法测定了稀土顺丁二烯和聚异戊二烯链端结构及序列结构,从链端结构推测的聚合活性链端结构与前文是一致的。在聚异戊二烯中存在着“头-头”和“尾-尾”结构,这种结构引起活性链端甲基位置的改变,从而解释了稀土异戊二烯中3,4-链节的形成。测定了不同聚合温度对聚合物中顺、反结构含量的影响,可用活性链端的 anti-syn异构化加以解释。     

La3F3[Si3O9]: Das erste Fluoridsilicat aus dem ternären System LaF3/La2O3/SiO2

La₃F₃[Si₃O₉]: The First Fluoride Silicate in the Ternary System LaF₃/La₂O₃/SiO₂ By reacting La₂O₃ with LaF₃ and SiO₂ (silica gel) using CsCl as a flux (molar ratio 1 : 1 : 3 : 6; 700 °C, 21 d) it was possible to obtain single crystals of La₃F₃[Si₃O₉] (hexagonal, space group: P 6 2c (no. 190); a = 708.32(3), c = 1089.48(6) pm; Z = 2) as colourless, hexagonal platelets. The crystal structure comprises discrete cyclic [Si₃O₉]^6– anions of three corner-linked [SiO₄] tetrahedra along with a graphite-like network of the composition {[LaF_3/3]²⁺}. Shorter reaction times even produced single crystals of tysonite-type LaF₃ (trigonal, space group: P 3 c1 (no. 165); a = 718.80(6), c = 735.94(6) pm; Z = 6) on which a X-ray structure analysis was achieved, too. The structures of both compounds, each of which show an elevenfold anionic coordination (CN = 9 + 2) for the La³⁺ cations, are compared. The influence of the reactivity of the educts and the temperature on the reaction as well as the difficulties in the X-ray differentiation of fluorine and oxygen will be discussed.     

Two Hexagonal Series of Lanthanoid(III) Oxide Fluoride Selenides: M6O2F8Se3 (M = La – Nd) and M2OF2Se (M = Nd,Sm, Gd – Ho)

Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF₃, M₂O₃, M, and Se in sealed niobium tubes at 850 °C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La – Nd) occur with the formula M₆O₂F₈Se₃, whereas with the heavier and smaller ones (M = Nd, Sm, Gd – Ho) their composition is M₂OF₂Se. For both systems single‐crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P6₃/m) with lattice parameters of a = 1394–1331 pm and c = 403–372 pm (Z = 2 for M₆O₂F₈Se₃ and Z = 6 for M₂OF₂Se). The (M1)³⁺ cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2)³⁺ cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se^2– anions are sixfold coordinated as trigonal prisms of M³⁺ cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F^– and O^2– can not be distinguished by X‐ray diffraction, bond‐valence calculations were used to address the problem of their adjunction to the available crystallographic sites.