Cooperation between Pt and Ru on RuPt/AC bimetallic catalyst in the hydrogenation of phthalates

RuPt/AC bimetallic catalysts were pre pared by two-step incipient impregnation method and evaluated in the hydrogenation of phthalates.According to the characterization results,well dispersed Ru Pt bimetallic nanoparticles were formed on the catalyst,and the strong interaction between the two metals resulted in the formation of RuPt alloy.It was found that Ru can donate electrons to Pt on RuPt alloy nanoparticles,leading to the formation of electron-deficient Ru which significantly promotes the hydrogenation rate of dioctyl phthalate and improves the selectivity of dioctyl di-2-ethylhexylcyclohexane-1,4-dicarboxylate by accelerating the further hydrogenation of intermediate products.The bimetallic RuPt catalyst also presented excellent stability and versatility in the hydrogenation of phthalates,demonstrating its prospective future in the hydrogenation of aromatic ring contained compounds.     

Preparation, characterization and catalytic behavior of Pt-Cu nanoparticles in methane combustion

Fine and well dispersed Pt-Cu bimetallic nanoparticles stabilized by polyvinyl pyrrolidone (PVP) were synthesized by alkaline polyol method. The molar ratio of Pt to Cu was 1 : 1. Further, the Pt-Cu bimetallic nanoparticles were supported on alumina and their catalytic behavior in methane combustion was investigated. The as-prepared as well as the supported Pt-Cu nanoparticles were characterized by transmission elec-tron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), fractal analysis and X-ray diffraction (XRD). The dependence of methane combustion on the morphology and surface composition of Pt-Cu nanoparticles was analyzed based on the experimental results.     

Electrochemical Sensor for Oxidation of NO Based on Au-Pt Nanoparticles Self-assembly Film

Au-Pt bimetallic nanoparticles film used as an efficient electrochemical sensor was prepared by self-assembled Au-Pt bimetallic nanoparticles on a glassy carbon (GC) substrate using thioglycolic acid as a linker. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that the Au-Pt nanoparticles self-assembly film was dense and uniform. Electrochemical experiments revealed that Au-Pt bimetallic nanoparticles film/GC electrode showed high electrocatalytic activity to the oxidation of nitric oxide.     

Synthesis and characterization of niobium-promoted cobalt/iron catalysts supported on carbon nanotubes for the hydrogenation of carbon monoxide

Bimetallic Co /Fe catalysts supported on carbon nanotubes( CNTs) were prepared,and niobium( Nb) was added as promoter to the 70 Co ∶30Fe /CNT catalyst. The physicochemical properties of the catalysts were characterized,and the catalytic performances were analyzed at the same operation conditions( H_2 ∶CO( volume ratio) = 2 ∶1,p = 1 MPa,and t = 260 ℃) in a tubular fixed-bed microreactor system. The addition of Nb to the bimetallic catalyst decreases the average size of the oxide nanoparticles and improves the reducibility of the bimetallic catalyst. Evaluation of the catalyst performance in a Fischer-Tropsch reaction shows that the catalyst results in high selectivity to methane,and the selectivity to C_(5+) increased slightly in the bimetallic catalyst unlike that in the monometallic catalysts. The addition of 1% Nb to the bimetallic catalyst increases CO conversion and selectivity to C_(5+). Meanwhile,a decrease in methane selectivity is observed.     

Characterization and reactivity of γ-Al_2O_3 supported Pd–Ni bimetallic nanocatalysts for selective hydrogenation of cyclopentadiene

Several g-Al2O3 supported Pd–Ni bimetallic nanocatalysts(Pd–Ni(x:y)/Al2O3; where x and y represent the mass ratio of Pd and Ni, respectively) were prepared by the impregnation method and used for selective hydrogenation of cyclopentadiene to cyclopentene. The Pd–Ni/Al2O3 samples were confirmed to generate Pd–Ni bimetallic nanoparticles by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM). The catalytic activity was assessed in view of the effects of different mass ratios of Pd and Ni, temperature, pressure, etc. Among all the samples, the Pd–Ni(1:1)/Al2O3(PN-1:1) catalyst showed extremely high catalytic ability. The conversion of cyclopentadiene and selectivity for cyclopentene can be simultaneously more than 90%.     

过氧化氢溶液中单和双金属金-银纳米粒子氧化L-亮氨酸的动力学(英文)

The catalytic activity of surfactant stabilized mono-and bimetallic Au and Ag nanoparticles for the oxidation of an amino acid,L-leucine,was studied using hydrogen peroxide as the oxidant.The Au and Ag nanoparticle catalysts exhibited very good catalytic activity and the kinetics of the reaction were found to be pseudo-first order with respect to the amino acid.The effects of several factors,such as oxidant concentration,ionic strength,pH,and catalyst concentration on the reaction,were also investigated.In particular,optimal oxidant and catalyst concentrations were determined.Very high concentrations of the metal nano-catalysts or the oxidant led to a dramatic increase in reaction rate.Moreover,bimetallic Au-Ag catalysts provided higher selectivity than pure Au or Ag.     

Composite surfactants aided solvothermal synthesis and catalytic hydrogenation property of oil soluble bimetallic CoMoS nanoparticles

Oil-soluble bimetallic CoMoS nanoparticles were successfully synthesized by a composite-surfactants-aided-solvothermal process. The surface hydrophilicity and functionality of the products were investigated through transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, and Ultraviolet (UV) spectra analysis. The catalytic performance of hydrogenation on the CoMoS nanoparticles was studied with naphthalene as a model compound. It was found that CoMoS catalysts supported on active carbon (AC) was more active than conventional MoS2/γ-Al2O3. The activity of CoMoS/AC can be tailored through the change of the Co/(Co+Mo) atomic ratio.     

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.     

SYNTHESIS OF POLYMER-STABILIZED PLATINUM/RUTHENIUM BIMETALLIC COLLOIDS AND THEIR CATALYTIC PROPERTIES FOR SELECTIVE HYDROGENATION OF CROTONALDEHYDE

Polymer-stabilized platinum/ruthenium bimetallic colloids （Pt/Ru） were synthesized by polyol reduction with microwave irradiation and characterized by TEM and XPS. The colloidal nanoparticles have small and narrow size distributions. Catalytic performance of the Pt/Ru colloidal catalysts was investigated on the selective hydrogenation of crontonaldehyde （CRAL）. A suitable amount of the added metal ions and base can improve the selectivity of CRAL to crotylalcohol （CROL） remarkably. The catalytic activity and the selectivity are dependent on the compositions of bimetallic colloids. Thereinto, PVP-stabilized 9Pt/1Ru colloid with a molar ratio of metals Pt：Ru = 9：1 shows the highest catalytic selectivity 77.3% to CROL at 333 K under 4.0 MPa of hydrogen.     

纳米核壳式铜-锡双金属粉的制备及性能研究

A kind of novel core-shell Cu-Sn bimetallic nanoparticles has been prepared by a new method (displacement method), in which Sn was made to cover on the surface of Cu nano-core. The preparation method and reaction mechanism have been discussed. This reaction happened under the existence of coordinate agent-(NH₂)₂CS and protective agent PVP. The nanoparticles prepared were with a core-shell structure, granule diameter between 50～100 nm and good dispersing capability. The Cu-Sn nanoparticles proposed has better oxidation-resistant ability than Cu nanoparticles with corresponding granule diameter and can be applied as lubricant additives as well as antibacterial agent. When the additive amount is very low (0.1wt‰～0.5wt‰), it can improve the P_B of the lubricant by 92%～106%, and also enhance its antiwear characteristics and friction-reducing properties. At the concentration of 1 000 ppm, it can reach an antibacterial ratio of 99.99%.     

Preparation and characterization of dendrimer-templated Ag-Cu bimetallic nanoclusters

Ag-Cu bimetallic nanoclusters with different shapes were prepared by a co-complexation method in the presence of PAMAM dendrimers. Small and evenly sized spherical Ag-Cu bimetallic nanoparticles were obtained with N2H4.H2O as the reducing agent, and long rod-shaped bimetallic nanoclusters were prepared with NaBH4 as the reducing agent. The mechanisms of formation of Ag-Cu bimetallic nanolusters with different shapes were discussed. The different shapes of the cluster were likely caused by the differences in the reduction rate of metal ions with NaBH4 and N2H4.H2O. Structure characterization by TEM, UV-vis spectra, EDX, and TGA showed that, in the presence of PAMAM dendrimers, Ag-Cu alloy bimetallic nanorods were obtained with NaBH4 reduction, and Ag-Cu bimetallic nanoparticles were prepared with N2H4.H2O as the reducing agent.     

Composition-controlled synthesis of bimetallic gold-silver nanoparticles

This paper reports findings of an investigation of the synthesis of monolayer-capped binary gold-silver (AuAg) bimetallic nanoparticles that is aimed at understanding the control factors governing the formation of the bimetallic compositions. The synthesis of alkanethiolate-capped AuAg nanoparticles was carried out using two related synthetic protocols using aqueous sodium borohydride as a reducing agent. One involves a two-phase reduction of AuCl(4)(-), which is dissolved in organic solution, and Ag(+), which is dissolved in aqueous solution. The other protocol involves a two-phase reduction of AuCl(4)(-) and AgBr(2)(-), both of which are dissolved in the same organic solution. AuAg nanoparticles of 2-3 nm core sizes with different compositions in the range of 0-100% Au have been synthesized. The two synthetic routes were compared in terms of bimetallic composition and size properties. Our new findings have allowed us to establish the correlation between synthetic feeding of metals and metal compositions in the bimetallic nanoparticles, which have important implications to the exploration of gold-based bimetallic nanoparticles for constructing sensing and catalytic nanomaterials.     

One-pot synthesis of Ag-Au bimetallic nanoparticles with Au shell and their high catalytic activity for aerobic glucose oxidation

PVP-protected Ag(core)/Au(shell) bimetallic nanoparticles of enough small size, i.e., 1.4nm in diameter were synthesized in one-vessel using simultaneous reduction of the corresponding ions with rapid injection of NaBH(4), and characterized by HR-TEM. The Ag(core)/Au(shell) bimetallic nanoparticles show a high and durable catalytic activity for the aerobic glucose oxidation, and the catalyst can be stably kept for more than 2months under ambient conditions. The highest activity (16,890mol-glucoseh(-1)mol-metal(-1)) was observed for the bimetallic nanoparticles with Ag/Au atomic ratio of 2/8, the TOF value of which is several times higher than that of Au nanoparticles with nearly the same particle size. The higher catalytic activity of the prepared bimetallic nanoparticles than the usual Au nanoparticles can be ascribed to: (1) the small average diameter, usually less than 2.0nm, and (2) the electronic charge transfer effect from adjacent Ag atoms and protecting PVP to Au active sites. In contrast, the Ag-Au alloy nanoparticles, synthesized by dropwise addition of NaBH(4) into the starting solution and having the large mean particle size, showed a low catalytic activity.     

尺寸比例可调的Au-Ni双金属纳米颗粒的制备

本文采用贵金属诱导还原法制备了一种Ni端尺寸可调的Au-Ni双金属纳米颗粒.该反应以十八胺为还原剂,硝酸镍和氯金酸为反应物,反应中Au3+首先被还原成Au0,随着温度上升,Ni2+从Au0获得电子而被还原成Ni0,十八胺持续提供电子,得到了雪人状的Au-Ni双金属纳米颗粒.采用I2/KI水溶液和0.5%(质量分数)盐酸分别对Au端和Ni端进行择性蚀刻,通过调节蚀刻时间,连续调控两端尺寸,可以达到完全刻蚀,最终制备了一种两端尺寸比例连续可调的Au-Ni双金属纳米颗粒.蚀刻后得到的新鲜表面为进一步功能复合提供了反应场所.     

Preparation and characterization of Ag(Au) bimetallic core–shell nanoparticles with new seed growth method

Ag(Au) bimetallic core–shell nanoparticles were prepared by a new seed growth method. Ascorbic acid was used to reduce the complex of HAuCl₄ and hexadecyltrimethylammoniumbromide (CTAB). This resulted in the forming of colorless Au(I) (AuCl₂⁻). It was used as the growth solution to prepare these bimetallic core–shell nanoparticles. These nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed these nanoparticles exhibited core–shell shape and there was large amount of Ag in the shell. These nanoparticles could be produced in a few minutes without violent stirring and the method was easy and convenient compared with others. The effect of amount of AuCl₂⁻ on the shape of nanoparticles was also studied. Many small gold nanoparticles were formed on the surface of bimetallic core–shell nanoparticles in the presence of excess AuCl₂⁻. The mechanisms were also proposed to explain the process of colloidal preparation.     

Facile fabrication of Ag-Pd bimetallic nanoparticles in ultrathin TiO(2)-gel films: nanoparticle morphology and catalytic activity

Ag-Pd bimetallic nanoparticles were prepared directly in ultrathin TiO(2)-gel films by a stepwise ion-exchange/reduction approach. Ion-exchange sites were created in ultrathin films using Mg(2+) ions as template. Ag(+) ion was then incorporated by ion exchange, and converted into metallic nanoparticles by low-temperature H(2) plasma, regenerating ion-exchange sites. The same procedure was then carried out for Pd(2+) ion, producing Pd-on-Ag bimetallic nanoparticles, as TEM observation and plasmon resonance absorption indicate. By contrast, reversed metal incorporation procedure appeared to give a mixture of individual Ag and Pd nanoparticles, as confirmed by TEM, absorption spectroscopy and X-ray photoelectron spectroscopy. For hydrogenation of methyl acrylate, the catalytic activity of the Pd-on-Ag nanoparticle is 367 times as large as that of commercial Pd black and 1.6 times as large as that of Pd monometallic nanoparticle. The outstanding catalytic activity was explicable by the large fraction of the surface-exposed Pd atoms. The formation process of the bimetallic nanoparticle and their general morphological feature are discussed.     

Synthesis of Pt/Ru bimetallic nanoparticles in high-temperature and high-pressure fluids

A high-temperature and high-pressure flow-reactor system was applied to the synthesis of monometallic ruthenium (Ru) nanoparticles and platinum/ruthenium (Pt/Ru) bimetallic nanoparticles using the thermal reduction of ruthenium ion (Ru(III)) and the mixture of platinum (Pt(IV)) and ruthenium ions in water and ethanol mixture in the presence of poly(N-vinyl-2-pyrrolidone). Monometallic Ru nanoparticles with an average diameter of ca. 2 nm were synthesized above 200 degrees C at 30 MPa. The monometallic Ru nanoparticles tended to make large aggregates in colloidal dispersions. By the reduction of the mixture solution of Pt(IV) and Ru(III) in water and ethanol above 200 degrees C at 30 MPa, Pt/Ru bimetallic nanoparticles with an average diameter of ca. 2.5 nm were synthesized with relatively small size distribution. The EXAFS spectra for the Pt/Ru bimetallic particles indicated that the particle possesses metallic bonds between Pt and Ru atoms in contrast to the case of the nanoparticles produced by thermal reduction under ambient pressure at 100 degrees C [M. Harada, N. Toshima, K. Yoshida, S. Isoda, J. Colloid Interface Sci. 283 (2005) 64], and that the Pt/Ru bimetallic particle has a Pt-core/Ru-shell structure.     

Antibacterial cotton fabrics with in situ generated silver and copper bimetallic nanoparticles using red sanders powder extract as reducing agent

Using aqueous extraction of red sanders powder as a reducing agent, silver and copper bimetallic nanoparticles were in situ generated in cotton fabrics. Silver and copper nanoparticles were also generated separately for comparison. The resulted nanocomposite cotton fabrics (NCFs) were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and antibacterial tests. SEM analysis indicated the generation of more number of nanoparticles when bimetallic source solutions were used. Further, the size range of the generated bimetallic nanoparticles was found to be lower than when individual metal nanoparticles were generated in NCFs. XRD analysis confirmed the in situ generation of silver and copper nanoparticles when equimolar bimetallic salt source solutions were utilized. The NCFs with bimetallic nanoparticles exhibited higher antibacterial activity against both Gram-negative and Gram-positive bacteria and hence can be considered for applications as antibacterial bed and dressing materials.     

Microemulsion-templated synthesis of carbon nanotube-supported pd and rh nanoparticles for catalytic applications

Palladium, rhodium, and bimetallic Pd/Rh nanoparticles synthesized in a water-in-hexane microemulsion can be deposited directly on surfaces of functionalized multiwalled carbon nanotubes with high yields. The CNT-supported Pd nanoparticles are active catalysts for hydrogenation of olefins, for carbon-carbon bond formation, and for carbon-oxygen bond cleavage reactions. The CNT-supported Rh nanoparticles are active catalysts for hydrogenation of arenes, and the CNT-supported bimetallic Pd/Rh nanoparticles show an unusually high catalytic activity for hydrogenation of anthracene. This simple and novel synthetic technique for making CNT-supported monometallic and bimetallic nanoparticles may have a wide range of catalytic applications for chemical syntheses.