Relationship between the structure and catalytic activity of La2-xSrxNiO4-lambda(0<=x<=1) mixed oxides for NH3 oxidation

A series of samples having the composition of La2-xSrxNiO4(0 less than or equal to x less than or equal to 1) were prepared and used as catalysts for NH3 oxidation. It was found that the La and oxygen vacancies exist in the La2-xSrxNiO4-lambda(0 less than or equal to x less than or equal to 1). The unit cell volume decreases with the increase of x. For bath c and a parameters there appeared a turning point at x = 0.5. Doping with a lower valence cation Sr2+ in the case of La2NiO4 resulted in an increase of Ni3+, consequently the formation of oxygen vacancies, the increase of reducing ability and the increase of catalytic activity. In the oxygen TPD of La2-xSrxNiO4(0 less than or equal to x less than or equal to 1) appeared three peaks, the alpha' peak at about 400K was attributed to the surplus oxygen desorption, the a peak at 700K which approaches to a maxium at x = 0.6 was attributed to the oxygen adsorbed at oxygen vacancies. The beta peak at about 1000K which depends closely on the x and favors the catalytic activity was attributed to the reduction of Ni3+. The catalytic activity of La-2-x SrxNiO4 mixed oxides in the NH3 oxidation in general could be attributed to the extent of the redox reaction: 2Ni(2+) + O-2 + V-0(..) reversible arrow 2Ni(3+) + 20(-) where V-0(..) representes the oxygen vacancies and O- the oxygen species adsorbed at the vacancies.

Relationship between the dissolution behaviours and current efficiencies of La, Ce, Pr and Nd in their chloride molten salts

The dissolution behaviours of La and Nd in their chloride molten salts were studied by means of the see-through cell, electrochemical weak polarization and quantum chemistry (extended Huckel molecular orbital). The reasons for the low current efficiencies of rare earth metals and the difference between La and Nd in their own chloride electrolytes on the basis of the solubility, rate of dissolution, and existing state of the metals dissolved as well as the structure of the melts, are discussed.

La_(2-x)Sr_xNiO_(4-λ)系列催化剂结构与氨氧化活性的关系

本文报道了La_(2-x)Sr_xNiO_(4-λ)(O≤x≤1)系列复合氧化物的固体结构性质和用于氨的氧化制硝酸的催化性能.La_(2-x)Sr_xNiO_(4-λ)的晶胞体积Ⅴ随x的增大而逐渐减小;c轴在x≤0.5前逐渐增大,在x≥0.5后逐渐减小.a轴在x≤0.5前逐渐减小,在x≥0.5后基本保持恒定.在x≤0.5前,La_(2-x)Sr_xNiO_(4-λ)中存在氧过剩,在x≥0.5后存在氧缺陷.TPD表明,a氧(吸附在氧缺陷上的氧)在x=0.6时出现极大,β氧(晶格氧)随x增大而逐渐增大.La_(2-x)Sr_xNiO_(4-λ)的氧化还原能力,Ni~(3+)的量,氨氧化的NO选择性都随x增大而增加.由此得出,Ni~(3+)是催化剂的活性离子,β氧是氨的氧化的活性氧种,在La_(2-x)Sr_xNiO_(4-λ)上的氨的氧化遵循氧化还原(Redox)机理.

聚（苯乙烯－丙烯酰胺）载体－NdCl_3络合物二元催化剂

聚（苯乙烯－丙烯酰胺）载体－ＮｄＣｌ_３络合物二元催化剂李玉良，郑文治，于广谦，李晓莉（中国科学院长春应用化学研究所，１３００２２）二元催化剂较三元催化剂，具有节省资源、简化工艺流程和有益于提高经济效益的优点。虽然聚［苯乙烯－甲基丙烯酸β（甲基亚硫酰?..

TiO_2-Li_2O-Nb_2O_5∶Eu~(3+)体系的研究

本文研究了 TiO_2-Li_2O-Nb_2O_5:Eu~(3+)体系中固溶体形成的温度与组成的关系。化学通式为 Ti_(1-4x-y)EuLixNb_3xO_2,当 y=0.2,0

LaF_3-KF熔盐的径向分布函数

熔盐结构具有远程无序、近程有序的特点,对其结构的表征要比完全有序的晶体和完全无序的气体困难得多.分布函数理论是迄今为止描述熔盐结构较为成熟的方法,它依据统计理论,从粒子间相互作用势能出发,去求解表征体系结构的径向分布函数.实验上获得径向分布函数主要是通过衍射法.在国内,熔盐径向分布函数的实验工作才刚刚开始.本文报导了采用X-射线衍射方法测定LaF_3-KF熔盐径向分布函数的结果.

L-B膜

L-B膜即 Langmuir-Blodgett单分子膜,它是人为地利用分子间相互作用而建立起来的特殊分子体系。在L-B膜中分子是有序的准晶体排列,其性质有别于固体和晶体,因而有人将其称为物质的第五相。用米制备L-B膜的技术称为L-B技术。

化学蚀刻法在研究共混高聚物结构中应用

共混高聚物是具有优良性能的高分子材料,近些年来这类材料的应用越来越广泛,从而对共混高聚物的研究也逐渐深入。本文将应用化学蚀刻法对丙纶高分子材料结构做以探讨。丙纶是聚丙烯(PP)与聚对苯二甲酚乙二酯(PET)经物理共混而成的,由于PET的加入可以提高丙纶染色效果,因此扩大丙纶应用范围。我们对PP与PET共混物在不同温度不用铬酸液蚀刻不同时间,通过扫描电镜观察其形态结构。实验结果表明,铬酸蚀刻液对高分子材料晶区与无定型部分可以有选择的腐蚀,使晶区与无定型区形态清晰显露,从而达到提高共混物衬差效果,对研究共混高聚物结构具有重要意义。

二(2-乙基己基)膦酸萃取Er(Ⅲ)的动力学和机理

H(DEHP)是HEH(EHP)和HDEHP的同系物,它们的结构分别为:HDEHP,(GO)_2PO(OH);HEH(EHP),(GO)(G)PO(OH);H(DEHP),(G)_2PO(OH)。其中G为2-乙基已基。 希土元素萃取分离工艺化学表明,溶剂萃取希土元素对酸度的依赖关系及相邻希土元素间的分离因素值是选择萃取剂时应优先考虑的因素。HDEHP萃取剂对中、重希士元素反萃酸度高,HEH(EHP)是一个优良萃取剂,但对Er,Tm,Yb,Lu的反萃仍需5mol/l的酸。由于H(DEHP)分子中不含酯氧原子,使得它的pK_a值比HDEHP和HEH(EHP)的高。从而,用H(DEHP)萃取希土元素时需要的水相酸度更低,反萃更容易。而且H(DEHP)

HMDSO和TFM混合气体等离子体聚合膜的结构与性能

在钟罩式内极反应器中进行了六甲基二硅氧烷(HMDSO)和四氟化碳(TFM)混合气体等离子体聚合。用IR、XPS、X射线对聚合膜结构进行了表征。等离子体共聚合膜中含有Si和F,聚合膜中元素组成依赖于起始混合气体单体的比,Si/C元素比随着混合气体中TFM浓度增加而减小,而F/C比增大。测定了复合膜的气体透过性,等离子体共聚合方法是制备气体分离膜的可行方法。同时,还测定了等离子体聚合膜的接触角,并计算了表面能。

Distribution of uranium isotopes in the main channel of Yellow river (Huanghe), China

Uranium isotopes were measured in waters and suspended particulate matters (SPM) of the main channel of Yellow River, China that were sampled during four field trips between August 2005 and July 2006. The results show that the concentration of dissolved U (2.04-7.83 mu g/l) and the activity ratio of U-234/U-238 (1.36-1.67) are much higher than the average U concentrations and activity ratios of global major rivers. Mass balance calculations using the results of simulated experiments and measurement data show that the section of the Yellow River between Lanzhou and Sanmenxia has its dissolved U derived from two sources: suspended sediments (68%) and groundwater/runoff from loess deposits (32%). Both sources are related to the heavy erosion of the Chinese Loess Plateau. (C) 2008 Elsevier Ltd. All rights reserved.

Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127A degrees 04.5'E, 27A degrees 15'N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the Pb-210 radioactivity ratios and Pb-210/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the Pb-210/Pb ratios of hydrothermal sulfide samples (3.99x10(-5)-5.42x10(-5)), their U isotopic composition (U-238 content 1.15-2.53 ppm, U-238 activity 1.07-1.87 dpm/g, U-234 activity 1.15-2.09 dpm/g and U-234/U-238 ratio 1.07-1.14) and their Th-232 and Th-230 contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

Effective AC and DC responses of nonlinear composites at higher concentration

For higher concentration of inclusions, an effective medium approximation (EMA) method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relation of electric displacement and electric field, D-alpha = epsilon E-alpha + chi(alpha)|E|(2) E. As an example of three dimensions, under the external AC and DC electric fields E-app = E-a (1 + sin omega t), we have derived the general effective nonlinear response of composites by the EMA method for higher concentration of spherical inclusions. Furthermore, the effective nonlinear responses at harmonics are predicted.

富营养化环境下的海洋微藻生理生化特性研究

本论文以中肋骨条藻和东海原甲藻为研究对象，研究了富营养化条件下，两种主要赤潮藻的磷酸酶活性变化、主要生化组成特征变化以及光合作用特性变化，分析了营养盐条件与微藻的主要生理生化特性之间的关系。结果表明中肋骨条藻和东海原甲藻均能诱导碱性磷酸酶和酸性磷酸酶，且两种磷酸酶具有相似的变化趋势。外界磷酸盐和胞内磷酸盐浓度越低，酶活性越高。另外两种藻均能吸收利用有机磷化合物（ATP、G-6-P和G-P），生物量明显增加。在试验初期，两种赤潮藻的单位细胞总脂和总碳水化合物含量随着营养盐的消耗而呈下降趋势，在试验后期，环境中营养盐限制时，胞内总脂和总碳水化合物含量呈上升趋势。单位细胞总蛋白含量在整个实验期间也随着营养盐的消耗呈下降趋势，但无上升现象。两种藻在低营养盐浓度处理组的单位细胞光合色素含量分别低于相对应的高营养盐浓度处理组。当P源充足时，低N处理组的藻细胞叶绿素活性较高，光合速率高于高N处理组；N源充足时，低P处理组的光合速率低于高P处理组。对两种藻的主要生理生化特性指标与营养盐浓度进行相关性分析发现，微藻的生理生化指标变化与磷酸盐浓度尤其是胞内磷酸盐浓度呈好的相关关系，而与硝酸盐浓度无显著相关性。