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1.
乳化剂OP存在下乙炔—空气火焰原子吸收法测定人发中锶   总被引:2,自引:0,他引:2  
本文研究了八种表面活性剂对空气乙炔火焰中Sr原子吸收信号的影响,发现乳化剂OP能使Sr原子吸收信号增强55%,同时还有降低和消除共存离子干扰的效果。采用6%乳化剂OP为增敏剂测定了人发中痕量锶,回收率为96-104%,相对标准偏差为2.5%。  相似文献   

2.
CrOx/SiO2催化剂上丙烷在CO2气氛中脱氢反应的研究   总被引:2,自引:0,他引:2  
采用XRD、UV-vis  DRS、ESR和微分吸附量热等技术,考察了铬担载量分别为2.5、5和 10wt%的 CrOx/SiO2催化剂的结构、表面性质和氧化还原性能。结果表明,催化剂表面上存在多种Cr的氧化态和聚集形式。随着Cr担载量从2.5wt%到10wt%的逐渐增大,催化剂表面占主导地位的Cr物种由CrO3单体转为多聚CrO3和Cr2O3晶相。在 CO2气氛中催化剂对丙烷转化率和丙烯选择性的大小顺序为 2. 5wt% CrOx/SiO2 >5wt% CrOx/SiO2>10wt% CrOx/SiO2,反应过程中的原位 ESR和 UV-visDRS测定结果表明,催化剂表面的反应活性中心为Cr5+, Cr5+可由催化剂预处理过程中 Cr3+的氧化及丙烷反应过程中 CrO3单体的还原产生,在反应中 CO2可使Cr3+重新氧化为Cr5+。  相似文献   

3.
在VPO催化剂中添加Pr,用XRD,LRS,XPS,ESR和^31P固体核磁共振考察了催化剂的相组成和钒的氧化态,用NH3-TPD和吡啶吸会原位红外光谱表征了催化剂表面的酸量。将催化剂应用于正丁烷选择氧化生成顺酐的反应中,实验结果表明,当Pr/V原子比=0.05时,活性相(VO)2P2O7的量增加,表面酸性增强,正丁烷转化率和生成顺酐的选择性都有所提高,而Pr/V≥0.10时,(VO)2P2O7的  相似文献   

4.
赵琦  郭新闻 《催化学报》1999,20(1):55-59
采用廉价的四丙基溴化铵(TPABr)的模板剂合成了TS-1分子筛,在晶化过程中,运用XRD,ICP,IR,^29SiMASNMR和UV-Vis光谱等表征手段,系统地研究了钛原子引入分子筛骨架的机制,观察到钛原子随分子筛的形成同步进入骨架的规律,另外,尽管在晶化初期固相中没有TiO2结晶出现,但存在分散态的TiOx物种,随晶化时间的延长,液相中钛物种之间聚合的几率增加,使固相中TiO2晶体不断形成。  相似文献   

5.
电感耦合等离子体光谱和质谱法分析贻贝标准物质   总被引:5,自引:0,他引:5  
采用电感耦合等离子体光谱和质谱法分析了贻贝标准物质,光谱法测定K、Na、Ca、Mg、P、Al、Fe、Zn、Mn和Sr,质谱法测定As、B、Cd、Co、Cr、CuGa、Ge、Mn、Mo、Ni、Pb、Se、Sr、U和V。在优化的工作条件下,测定了来自基体元素K、Na、Ca、P、Cl的C的多原子离子^39K^16O、^39K2、^40Ar^23Na、^43Ca^16O、^42Ca^16O、^31P^16  相似文献   

6.
TS-1分子筛骨架钛原子引入过程的研究   总被引:1,自引:0,他引:1  
采用廉价的四丙基溴化铵(TPABr)为模板剂合成了TS1分子筛.在晶化过程中,运用XRD,ICP,IR,29SiMASNMR和UVVis光谱等表征手段,系统地研究了钛原子引入分子筛骨架的机制,观察到钛原子随分子筛的形成同步进入骨架的规律.另外,尽管在晶化初期固相中没有TiO2结晶出现,但存在分散态的TiOx物种.随晶化时间的延长,液相中钛物种之间聚合的几率增加,使固相中TiO2晶体不断形成.  相似文献   

7.
实验研究结果表明双核金属酞菁类化合物MPc-PcM(M=V、Cr、Mn、Fe、Co、Ni、Cu)是催化H_2S液相氧化反应的良好催化剂,且其催化活性顺序为Co>Ni>V>Fe>Cu>Cr>Mn.采用量子化学理论计算方法(INDO/S)分析了其前线分子轨道的构成特征,结果表明这几种MPc-PcM的LUMO轨道皆为有金属离子参与形成的π轨道,但HOMO轨道间的差异却很大.M=Co、Ni、Cu、Cr时,其HOMO为π轨道;而M=Fe、Mn时,其HOMO却为σ轨道.正是在前线分子轨道的轨道类型、共轭程度及金属轨道贡献三方面因素的协同作用下,才导致MPc-PcM的催化活性顺序并非按中心金属离子价电子层d电子数的递变而呈现出规律性的变化.  相似文献   

8.
氯化三辛基甲基胺萃取原子吸收法测定微量锑的研究   总被引:1,自引:1,他引:0  
杜乃林  王贵领 《分析化学》1994,22(9):945-947
本文在KI-H2SO4体系中,研究了锑的碘络阴离子的萃取行为,并结合火焰原子吸收法测定了微量锑,萃取体积比(V水/V有)为20,线性范围为0-2μg/ml,锑的特征浓度为0.5μg/ml/1%吸收,检出限为0.1μg/ml。  相似文献   

9.
簇合物〔WOS3Cu3(γ-pic)6〕Br(C36H42BrON6S3Cu3W, Mr= 1125.34) 属于三方晶系,空间群为P3,晶胞参数为:a= 12.264(5), c= 15.905(8) , γ= 120.00°, V=2071(2)3, μ(MoKα)= 5.490m m - 1, Z= 2, Dc= 1.804g/cm 3, F(000)= 1104 , R= 0.052 , w R= 0.053. 可观察衍射点1901 (I≥2σ(I))。该簇合物的分子由游离的阴离子Br- 和簇阳离子〔WOS3Cu3(γ-pic)6〕+ 构成。阳离子中的W 原子、S原子和Cu原子构成1 个巢状骨架结构,且该结构中存在一个通过W 和O原子的C3 轴。  相似文献   

10.
应用火焰原子吸收法和石墨炉原子吸收法测定了冠心病患者和对照组血清中Zn,Cu,Fe,Ca,Mg,Cr,Mn和Sr等的含量。对所得数据用反向传播神经网络(B-P法)进行分析,建立了冠心病的神经网络识别系统,预报识别率达100%,可作为该病诊断的一种有效的辅助手段。  相似文献   

11.
12.
在乙二醇溶液中原位法制备纳米SnO2   总被引:4,自引:0,他引:4  
朱传高  徐博  王凤武 《应用化学》2008,25(12):1493-0
乙二醇;锡配合物;溶胶 凝胶;纳米SnO2  相似文献   

13.
Gels have been synthesized in the SiO2-Na2O-ZrO2 system and calcined at various temperatures up to 700°C. They have been studied by infrared absorption spectroscopy. The position of the asymmetric stretching frequency of the SiO4 unit is used as a tracer of the homogeneity. It is shown that sodium increases the solubility of zirconium in the silica matrix as already observed in fused glasses.  相似文献   

14.
纳米ZrO2在O2/H2气中的表面效应   总被引:1,自引:0,他引:1  
用ESR方法研究了一种纳米ZrO2在普通H2气中升温条件下的表面效应.ZrO2上Zr3+的中心量约为1×10-7mol/g.这些Zr3+中心是ZrO2表面一些O2-配位不饱和的Zr原子点位.在普通H2气中,ZrO2上的Zr3+中心数在温度低于400℃时变化很小.但在这一温度范围内从室温升温时,由ZrO2表面羟基的H2还原引起的F中心量随温度的升高而增加.温度高于400℃时,ZrO2表面的Zr3+及F中心可与普通H2气中存在的少量O2气作用产生O2-,并伴随ZrO2表面羟基的脱除而形成新的Zr3+.  相似文献   

15.
Dimethylacetylene dicarboxylate and hexafluoro-2-butyne add to Pd2(dpm)2Cl2 (dpm = Ph2PCH2PPh2) to give crystalline adducts Pd2(dp)2(μ-acetylene)Cl2. An X-ray crystal structure of Pd2(dpm)2(μ-C4F6)Cl2 reveals that the acetylene has inserted into the metalmetal bond and has been transformed into a cis-dimetallated olefin. The central CC bond length of the bridging olefin is 1.338(16) Å. The coordination about each of the two similar palladium ions is planar and involves two trans-phosphines (one from each of the bridging dpm ligands), a terminal chloride, and one carbon of the bridging olefin. Both Pd2(dpm)2Cl2 and Pd2(dpm)2(μ-C2{CO2H3}2)Cl2 catalyze the cyclotrimerization of dimethyl-acetylene dicarboxylate.  相似文献   

16.
We successfully synthesized the copper-based pnictide LiCu(2)P(2), which was reported as a superconductor with T(c) = 3.7 K before. The temperature dependence of resistivity and DC magnetization was measured on both polycrystalline and single-crystalline LiCu(2)P(2). However, our repeatable synthesizing and measurements showed no superconducting transition either in resistivity or DC magnetization above 2 K. A metallic behavior can be seen in resistivity, and a Curie-Weiss behavior was observed in DC magnetization from 2 to 300 K. We have also carried out the Hall effect and MR measurements on the sample, from which we conclude that the LiCu(2)P(2) has a single-band character. We also synthesized the polycrystalline Li(1-x)Cu(2)P(2), LiCu(2-x)P(2), and Li(1+x)Cu(2-x)P(2) with different stoichiometries, and observed no superconductivity in all the samples.  相似文献   

17.
2-hexanoyl-5-(2-hydroxy 2-propyl)furan (HHPF), has been investigated as the principal product of radiolysis of 2-hexanoyl-furan (HF) in 2-propanol. The effect of absorbed dose on the product yields has been examined. Possible mechanisms for the formation of radiolytic products are discussed.  相似文献   

18.
SiO2-TiO2-ZrO2 and 5Na2O·95(SiO2 + TiO2 + ZrO2) gels were synthesized and role of Na2O in gel formation and crystallization behavior of gels were studied. From Si(OC2H5)4, Ti(iso-OC3H7)4, Zr(n-OC3H7)4 and NaOCH3 solutions in EtOH without H2O, transparent and opaque gels were obtained. Opaque bulk gels, rich in TiO2 or ZrO2 composition in Na2O containing SiO2-TiO2-ZrO2 system, contain agglomerated spherical particles of diameter small <10 m, in contrast with opaque gels having large particles <30 m in alkali-free SiO2-TiO2-ZrO2 system. Crystallization temperature (Tc) was measured by DTA on dried gels. Compared with the alkali-free SiO2-TiO2-ZrO2 gels, 5 mol% Na2O containing gels gave lower Tc in SiO2 rich compositions and higher in TiO2 rich or ZrO2 rich compositions.  相似文献   

19.
The infrared spectra of 2-hydroxypyridine (2-OHP), 2-thiopyridine (2-SHP), and 2-aminopyridine (2-NH2P) have been recorded in the solid, liquid and vapor phases in the region 4000-200 cm(-1). To support the work, deuterated forms of these compounds in the functional groups XH and NH with (X=O, S, NH) were recorded for the solid and liquid phases. The results show existence of each compound as an equilibrium mixture of two tautomers in monomeric and cyclic dimeric forms in the solid, liquid and vapor phases. The monomers are predominant in the vapor phase. Enthalpy differences between the monomeric tautomers and activation energies for their inter-conversion were determined in each phase.  相似文献   

20.
Gamma radiolysis of 2-acetylfuran (AF) in 2-propanol, in absence of atmospheric oxygen, has been investigated. The radiation yields of hydrogen, methane at different doses as well as radiolytic products in solution were determined. The radiolytic products were determined by gas chromatography coupled with mass spectrometry. The mechanisms for formation of detected radiolytic products and the effect of (AF) concentration on hydrogen and methane yields are discussed.  相似文献   

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