基态XO~（n＋）（X=Ru,Rh,Pd;n=0,1）的势能函数和第一垂直电离势

运用原子分子反应静力学原理推导出XOn+(X=Ru,Rh,Pd;n=0,1)的基态电子状态及离解极限.运用密度泛函的B3P86方法和LANL2DZ赝势基组及aug-cc-pVTZ全电子基组,对XOn+X=Ru,Rh,Pd;n=0,1)体系进行计算,获得了这些分子及其离子基态的Murrell-Sorbie解析势能函数.同时计算了XOn+(X=Ru,Rh,Pd;n=0,1)的光谱数据,计算了XO(X=Ru,Rh,Pd)中性分子的第一垂直电离势.     

基态XOn+(X=Ru,Rh, Pd|n=0, 1)的势能函数和第一垂直电离势

运用原子分子反应静力学原理推导出XOn+(X=Ru, Rh, Pd; n=0, 1)的基态电子状态及离解极限. 运用密度泛函的B3P86方法和LANL2DZ 赝势基组及aug-cc-pVTZ全电子基组, 对XOn+(X=Ru, Rh, Pd; n=0, 1)体系进行计算, 获得了这些分子及其离子基态的Murrell-Sorbie解析势能函数. 同时计算了XOn+(X=Ru, Rh, Pd; n=0, 1)的光谱数据, 计算了XO(X=Ru, Rh, Pd)中性分子的第一垂直电离势.     

A density functional theory study of the noble metal adsorption on the CeO2(111) surface

利用密度泛函理论系统研究了贵金属原子(Au、Pd、Pt和Rh)在CeO2( 111)表面的吸附行为.结果表明,Au吸附在氧顶位最稳定,Pd、Pt倾向吸附于氧桥位,而Rh在洞位最稳定.当金属原子吸附在氧顶位时,吸附强度依次为Pt ＞Rh＞ Pd＞Au.Pd、Pt与Rh吸附后在Ce 4 f、O2p电子峰间出现掺杂峰;Au未出现掺杂电子峰,其d电子峰与表面O2p峰在-4 -1 eV重叠.态密度分析表明,Au吸附在氧顶位、Pd与Pt吸附在桥位、Rh吸附在洞位时,金属与CeO2(111)表面氧原子作用较强,这与Bader电荷分析结果相一致.     

示踪原子——离子交换法研究铑和铂、钯、铱的分离

本文以~(197)Pt、~(103)Pd和~(192)Ir为示踪原子,用离子交换法研究了常量Rh和小量Pt、Pd、Ir的分离。将Rh和Pt、Pd、Ir的盐酸溶液通过阳离子交换树脂往后,先用1M H Cl淋出Pt、Pd和Ir后,再用6M H Cl淋出Rh使Rh和Pt、Pd、Ir得到定量分离。     

三效催化剂作用下的NO+CO催化反应机理

NO与CO在Pt/Rh/Pd及载体组成的三效催化剂上的氧化还原应用是控制汽车尾气对空气污染的一个关键反应，这一反应随着近年来对环境保护的日益重视而成为国内外研究的热点，本文主要综述了NO及CO在Pt,Rh,Pd上的吸附及反应机理的实验及理论研究现状，总结得出：在三效催化剂对NO CO的催化反应中，Pt,Pd对CO的催化氧化起主要作用，而Rh对NO的解离有很好的活化作用。     

富氧条件下贵金属催化剂上丙烯选择性还原NO研究

用溶胶-凝胶(Sol-gel)法制备了以γ-Al₂O₃为载体,以Pt,Pd和Rh等为活性组分的单组分及双组分催化剂,在稀燃汽油机条件下评价了丙烯对NO的选择性催化还原活性.结果表明,在单组分催化剂中,催化剂的活性及顺序为Rh(73%)>Pt(65%)>Pd(47%),最高活性对应的温度分别为Pt(225℃),Pd(275℃)和Rh(375℃),N₂选择性顺序为Rh,Pd(>80%)>Pt(48%),氧化性顺序为Pt>Rh>Pd.Sol-gel制备的双组分催化剂中的不同贵金属活性位具有一定的协同效应,可明显拓宽活性温度范围,其中以Pt-Rh组合活性最好.Rh/Al₂O₃和Pt/Al₂O₃两种催化剂分层有序填装时,可提高C₃H₆的利用率,在200～450℃范围内,可有效地催化净化NO.     

Synthesis of palladium-rhodium bimetallic nanoparticles for formic acid dehydrogenation

Herein,we report for the first time the synthesis of preformed bimetallic Pd-Rh nanoparticles with different Pd:Rh ratios(nominal molar ratio:80-20,60-40,40-60,20-80) and the corresponding Pd and Rh monometallic ones by sol immobilization using polyvinyl alcohol(PVA) as protecting agent and NaBH4 as reducing agent,using carbon nanofibers with high graphitization degree(HHT) as the desired support.The synthesized catalysts were characterized by means of Transmission Electron Microscopy(TEM) and inductively coupled plasma optical emission spectroscopy(ICP-OES).TEM shows that the average particle size of the Pd-Rh nanoparticles is the range of 3-4 nm,with the presence of few large agglomerated nanoparticles.For bimetallic catalysts,EDX-STEM analysis of individual nanoparticles demonstrated the presence of random-alloyed nanoparticles even in all cases Rh content is lower than the nominal one(calculated Pd:Rh molar ratio:90-10,69-31,49-51,40-60).The catalytic performance of the Pd-Rh catalysts was evaluated in the liquid phase dehydrogenation of formic acid to H2.It was found that Pd-Rh molar ratio strongly influences the catalytic performance.Pd-rich catalysts were more active than Rh-rich ones,with the highest activity observed for Pd90:Rh10(1792 h^-1),whereas Pd69:Rh31(921 h^-1) resulted the most stable during recycling tests.Finally,Pd90:Rh10 was chosen as a representative sample for the liquid-phase hydrogenation of muconic acid using formic acid as hydrogen donor,showing good yield to adipic acid.     

P538萃取法从铂、钯、铑和铱混合物中纯化铑的研究

提出了从PT,Pd,Rh和Ir的混合物中纯化Rh的P538萃取法,首先将Rh(III)转化为水合阳离子,然后用P538的煤油溶液将其萃取到有机相,仍处于阴离子状态的Pt,Pd和Ir则留在水相,一次萃取Rh的直收率可达95%以上,Pt,Pd和Ir的萃取率在1%以下。     

贵金属原子在CeO2(111)表面吸附的密度泛函理论研究

利用密度泛函理论系统研究了贵金属原子(Au、Pd、Pt和Rh)在CeO₂(111)表面的吸附行为。结果表明,Au吸附在氧顶位最稳定,Pd、Pt倾向吸附于氧桥位,而Rh在洞位最稳定。当金属原子吸附在氧顶位时,吸附强度依次为Pt > Rh > Pd > Au。Pd、Pt与Rh吸附后在Ce 4f、O 2p电子峰间出现掺杂峰;Au未出现掺杂电子峰,其d电子峰与表面O 2p峰在-4～-1 eV重叠。态密度分析表明,Au吸附在氧顶位、Pd与Pt吸附在桥位、Rh吸附在洞位时,金属与CeO₂(111)表面氧原子作用较强,这与Bader电荷分析结果相一致。     

CO在Pd/SiO2催化剂上的加氢反应与钾的助催化作用

已经发现担在载体上的Pd,Pt,Ir及Rh都是活泼的合成甲醇催化剂.尽管在这些催化剂上甲醇生成的机理还不够清楚,但已经认识到这些催化剂对于合成甲醇的良好活性是由于其具有很强的加氢性能,同时伴随有活化非分解吸附的CO的能力.近来已有一些研究工作揭示出Pd和Rh催化剂的活性与选择性在很大程度上受载体组成与助催化剂的影响,同时也发现担在某些类型氧化硅或其他碱性载体上的Pd对于甲醇合成具有很高的     

Specificity of noble metals dynamic sorption preconcentration on reversed-phase sorbents

The reversible sorption preconcentration of noble metals (NMs) using different schemes “sorbent–reagent–eluent” was investigated. The extraction of Au, Pd, Pt, Ir, Rh and Ru chlorocomplexes from hydrochloric acid solutions on hyper-crosslinked polysterene MN-200 in the form of ion associates with tributylamine (TBA) and 4-(n-octyl)diethylenetriamine (ODETA) was investigated. It was found that Pd, Pt and Au were quantitatively and reversibly extracted using TBA on hyper-crosslinked polysterene; the appropriate eluent for desorption was 1 M solution of HCl in ethanol. Ir, Rh and Ru under these conditions were not sorbed quantitatively. It was found that sorbent hydrophobicity is not the main characteristic that defines the efficiency of sorption of a particular NM ion associate. Different efficiencies of hyper-crosslinked polysterene MN-200 for sorption of square-planar chlorcomplexes of Pt, Pd and Au and octahedral complexes of Ir, Rh and Ru were found. For the first time, the sorbents with their own N-atoms – StrataX and StrataX-AW – were used for the sorption of Ir, Rh and Ru. Using these sorbents, the sorption of Ir was increased up to 95%, and the sorption of Ru and Rh was increased to about 40%. We can explain these results by nonspecific interaction of chlorcomplexes of Ir, Rh and Ru with ethylenediamine groups of the sorbent. Weak bases with large anions may be applied for desorption of Ir, Rh and Ru. Two schemes of dynamic sorption preconcentration of NMs from hydrochloric acid solutions were proposed – hyper-crosslinked polysterene MN-200 for the determination of Au, Pd, Pt, and StrataX-AW for Ir, Rh and Ru.     

Displacement solid-phase extraction on mercapto-functionalized magnetite microspheres for inductively coupled plasma mass spectrometric determination of trace noble metals

A flow injection online displacement solid-phase extraction (DSPE) via magnetic immobilization of mercapto-functionalized magnetite microspheres onto the inner walls of a knotted reactor (KR) coupled with inductively coupled plasma mass spectrometry was developed for selective preconcentration and determination of trace noble metals (Ru, Rh, Pd, Pt, Ir and Au) in complex matrices. Online DSPE of 2.7 mL aqueous solution gave the enhancement factors of 32-46 for the six noble metals in comparison with direct nebulization of aqueous sample solution, and the detection limits (3 s) of 2.1 ng L(-1) for Ru, 1.9 ng L(-1) for Rh, 2.5 ng L(-1) for Pd, 1.8 ng L(-1) for Ir, 1.9 ng L(-1) for Pt and 1.7 ng L(-1) for Au. The sample throughput of the developed method was about 20 samples h(-1), and the relative standard deviation for eleven replicate determinations of the noble metals at the 30 ng L(-1) level ranged from 1.2% to 2.1%. The recoveries of Ru, Rh, Pd, Pt, Ir and Au still maintained 90% even after successive 140 cycles of DSPE. The developed method was successfully applied to selective determination of trace Ru, Rh, Pd, Pt, Ir and Au in complex matrices.     

Measurement of proton-induced prompt low energy photons by high resolution spectrometry: The analysis of noble metals

Using HPGe detectors, the K X-rays and prompt gamma-rays below 200 keV from Ru, Rh, Pd, Ag, Re, Os, Ir, Pt and Au were measured under bombardment with protons from 1.8 to 5.4 MeV. Excitation functions for analytically important gamma-rays were determined. Interference-free sensitivities were calculated and the method was tested by the analysis of standard dental alloys.     

Palladium monolayer and palladium alloy electrocatalysts for oxygen reduction

We investigated the oxygen-reduction reaction (ORR) on Pd monolayers on various surfaces and on Pd alloys to obtain a substitute for Pt and to elucidate the origin of their activity. The activity of Pd monolayers supported on Ru(0001), Rh(111), Ir(111), Pt(111), and Au(111) increased in the following order: Pd/Ru(0001) < Pd/Ir(111) < Pd/Rh(111) < Pd/Au(111) < Pd/Pt(111). Their activity was correlated with their d-band centers, which were calculated using density functional theory (DFT). We found a volcano-type dependence of activity on the energy of the d-band center of Pd monolayers, with Pd/Pt(111) at the top of the curve. The activity of the non-Pt Pd2Co/C alloy electrocatalyst nanoparticles that we synthesized was comparable to that of commercial Pt-containing catalysts. The kinetics of the ORR on this electrocatalyst predominantly involves a four-electron step reduction with the first electron transfer being the rate-determining step. The downshift of the d-band center of the Pd "skin", which constitutes the alloy surface due to the strong surface segregation of Pd at elevated temperatures, determined its high ORR activity. Additionally, it showed very high methanol tolerance, retaining very high catalytic activity for the ORR at high concentrations of methanol. Provided its stability is satisfactory, this catalyst might possibly replace Pt in fuel-cell cathodes, especially those of direct methanol oxidation fuel cells (DMFCs).     

Ru(Ⅲ)、Rh(Ⅲ)、Pd(Ⅱ)离子与ct-DNA的相互作用研究

本文以中药小檗碱作为分子探针，在0.01mol·L^-1醋酸-醋酸钠缓冲体系中，用紫外-可见吸收及荧光光谱法研究了Ru(Ⅲ)、Rh(Ⅲ)、Pd(Ⅱ)三种贵金属离子与DNA的键合相互作用。实验发现Ru(Ⅲ)离子对小檗碱-DNA二元体系的荧光有较强的猝灭作用;而Rh(Ⅲ)、Pd(Ⅱ)两种离子则对该二元体系产生显著的荧光敏化作用。考察了EDTA对贵金属离子、小檗碱及DNA三元混合体系的荧光光谱的影响，初步探讨了贵金属离子与DNA可能的键合机理。     

Extractive concentration of platinum-group elements and their determination by atomic-absorption spectrophotometry

The extraction of Pt, Pd, Ir, Rh, Ru, Ag, Au, Co, Cu, Ni and Fe with n-octylaniline has been investigated. Noble metals are extracted 10(3)-10(4) times better than Cu, Ni, Co and Fe. A method of determination of Pt, Pd, Ir, Rh and Ru is proposed. They are first separated from Cu, Ni, Co and Fe by means of extraction (and then determined, in either the aqueous or organic phase, by atomic-absorption spectrophotometry. The atomic absorption of platinum metals (with the exception of Pd) is affected by other elements of the platinum group and by non-noble metals. La(NO(3))(3) and Nd(NO(3))(3) lower the limit of detection for Pt, Rh, Ir and Ru and inhibit the effect of Co, Cu, Ni, Fe, Bi, Zn, Na, etc. on their determination. Lanthanum and neodymium chlorides and sulphates produce a similar effect but only on the determination of Pt and Rh. The coefficient of variation of the determination, in both phases, is within 2-6.8%.     

Determination of bismuth, indium and lead in geological samples by electrothermal AAS Part 2. Comparative study of palladium and molybdenum containing chemical modifiers*

A comparative and systematic study has been carried out of the effects of palladium and molybdenum containing chemical modifiers, such as Pd + Rh, Pd + Pt, Pd + Ru, Pd + Rh + Pt, Pd + Rh + Ru, Mo + Pd, Mo + Rh, Mo + Ru and Mo + Pt and additionally tartaric acid (TA) as a reducing agent together with mixed modifiers for the thermal stabilization of Bi, In and Pb in a Zeeman electrothermal atomic absorption spectrometer (ETAAS). The effect of the mass ratios of the mixed modifier components on the maximum pretreatment temperature for the analytes has been determined. The modifier mixtures of Pd + Rh + Pt, Mo + Pd + TA and Mo + Pt + TA were found to be especially powerful for the determination of Bi, In and Pb. These mixed modifiers could increase the ashing temperatures of the analytes up to 1250–1400° C. They were applied to the determination of Bi and Pb in dissolved geological reference samples and accuracy and precision of the method were thereby enhanced. The percent relative error was decreased from 20.0 to 0.4 for Bi and from 10.5 to 0.3 for Pb, depending on the sample type. Received: 9 May 1997 / Revised: 19 August 1997 / Accepted: 20 August 1997     

螯合树脂富集-激光气化等离子体发射光谱测定地质样品中铂族元素和金

采用含N、S功能团的螯合树脂YPA_4富集铂族元素和金。Au、Pt、Pd、Os的吸附率为98％以上,Ir为92％,Ru为90％,Rh为87％。把树脂灰化,用激光将其灰份气化输入等离子体激发,光谱测定。取样5g时,可测定0.2ng/g的Au,0.6ng/g的Os、Ir,0.06ng/g的Pt、Pd、Rh、Ru。标样分析结果与标准植吻合。     

Determination of bismuth, indium and lead in geological samples by electrothermal AAS Part 2. Comparative study of palladium and molybdenum containing chemical modifiers*

A comparative and systematic study has been carried out of the effects of palladium and molybdenum containing chemical modifiers, such as Pd + Rh, Pd + Pt, Pd + Ru, Pd + Rh + Pt, Pd + Rh + Ru, Mo + Pd, Mo + Rh, Mo + Ru and Mo + Pt and additionally tartaric acid (TA) as a reducing agent together with mixed modifiers for the thermal stabilization of Bi, In and Pb in a Zeeman electrothermal atomic absorption spectrometer (ETAAS). The effect of the mass ratios of the mixed modifier components on the maximum pretreatment temperature for the analytes has been determined. The modifier mixtures of Pd + Rh + Pt, Mo + Pd + TA and Mo + Pt + TA were found to be especially powerful for the determination of Bi, In and Pb. These mixed modifiers could increase the ashing temperatures of the analytes up to 1250–1400° C. They were applied to the determination of Bi and Pb in dissolved geological reference samples and accuracy and precision of the method were thereby enhanced. The percent relative error was decreased from 20.0 to 0.4 for Bi and from 10.5 to 0.3 for Pb, depending on the sample type. Received: 9 May 1997 / Revised: 19 August 1997 / Accepted: 20 August 1997