High Pd Concentrations Research Articles

Formation of Pd nanocrystals in titanium-oxide film by rapid thermal annealing of reactively cosputtered TiPdO films

In this article, the authors report a novel method for preparation of Pd nanocrystals embedded in TiO2 film; i.e., the TiPdO films are first deposited by reactively cosputtering Ti and Pd targets in a plasma mixture of O2 and Ar, followed by rapid thermal annealing (RTA). The experimental results indicate that the TiPdO film with a high content of Pd is inclined to produce big nanocrystals. Furthermore, the higher the RTA temperature, the bigger the Pd nanocrystals become. In addition, our analyses of the x-ray photoelectron spectroscopy spectra reveal that PdO, PdO2, Ti2O3, and TiO2 coexist in the as-deposited film, and the RTA at 600 °C leads to decomposition of the entire PdO2 and partial PdO, together with the growth of Pd nanocrystals. At the same time, the released oxygen oxidizes fully Ti2O3 into TiO2 during the decomposition. As the RTA temperature is increased up to 900 °C, more and more PdO is decomposed and the Pd nanocrystals become bigger and bigger.

Platinum group elements in the super-ore series of the Baleiskoe ore field

Single measurements of the concentration of plat� inum group elements (PGEs) in heavy fractions and wastes of goldextracting factory of Baleisk ore (13) demonstrated high concentrations (46.9 ppm) of Ru and Pd against the background of a relatively low Au content. This fact may provide evidence for some "antagonism" between Au and PGE because of the differences in forms of migration, accumulation, and parageneses of these elements in the oreforming sys� tem of the Baleiskoe ore field. Nitrogenand sulfur� bearing carbonaceous materials (CMs) in the solid

Concentrations and modes of occurrence of platinum group elements in the Shengli River oil shale, northern Tibet, China

The Shengli River–Changshe Mountain oil shale zone, located in the North Qiangtang depression, northern Tibet plateau, represents a potentially large marine oil shale resource in China. Twenty-one samples including oil shale, micritic limestone and marl were collected from the Shengli River area to determine the contents, distribution patterns and modes of occurrence of platinum group elements (PGEs) in marine oil shale. Oil shale samples from the Shengli River area have high ash yield (61.86–67.48%) and total organic carbon content (8.02–13.67%) with low total sulfur content (0.76–1.39%) and intermediate shale oil content (3.60–16.30%). The total PGE content in oil shale samples is very low (average 1.749 ng/g), approximately half the mean value of Chinese coals, but higher than that of USA coals. PGEs in oil shale samples from the Shengli River area are characterized by high Pd (average 0.82 ng/g), Os (average 0.15 ng/g) and Pt (average 0.66 ng/g) contents compared with Ru (average 0.05 ng/g), Rh (average 0.05 ng/g) and Ir (average 0.02 ng/g). Distribution patterns of individual PGEs are not uniform in the Shengli River oil shale section. The lower marl layer is characterized by the highest Ru and Rh concentrations, whereas the upper marl layer is characterized by the highest Os and Ir concentrations. The highest Pt and Pd concentrations are found in the lower and upper parts of oil shale seams, respectively. The individual PGEs in the oil shale samples from the Shengli River area exhibit various modes of occurrence. Ru is mainly present in P-bearing minerals and partly associated with the clay and Ca-bearing minerals. Rh is mainly controlled by clay minerals and partly present in the form of apatite. Os occurs mainly in clay minerals and, to a lesser extent, in pyrite and apatite. Pd and Ir are mainly associated with Ca-bearing minerals and apatite. Pt is mainly present in Ca-bearing minerals and partly related to organic matter and apatite.

Native iron (–platinum) ores from the Siberian Platform trap intrusions

Native iron occurs in two forms: terrestrial (telluric) and meteoritic. The former was considered to be poor in trace elements, whereas the latter contains varying amounts of Ni–Fe alloys, including kamacite, tanite and awaruite. In the late 1950s, native iron was discovered in the Siberian Platform trap intrusions, although it is only recently that geologists became interested in native iron from the traps. We provide a brief description of intrusions containing native iron and a detailed description of its occurrence, species, mineralogy and geochemistry of ore-forming and accompanying typomorphic chemical elements. A study of Siberian native iron shows wide variations in composition from Ni-free iron to awaruite and its intergrowth with a number of minerals. Globules of glass with a ‘liquid-in-liquid’ structure were recognised in native iron and analysed. Immiscible liquids have the compositions of ferruginous and high-silicon melts which are similar to that of ferrogabbro and granophyre. Isotopic compositions, such as 4He/3He, δ13CPDB, 87Sr/86Sr, 87Rb/86Sr of native iron and host-rocks suggests participation of continental-crust material in ore formation. Native iron was found to contain high concentrations of Cu, Ni, Co, Pt, Pd, Rh and Ge. The existence of a new Fe (–Pt) type of ore is established for the first time. Native iron and related Fe (–Pt) ores formed in feeder columns as a result of the interaction of tholeiite-basalt melt with fluid reservoirs of sedimentary rocks in the platform cover. Hydrocarbon fluids and organometallic compounds play a leading role in ore formation. The finding of Fe (–Pt) ores open up new possibilities for discovering new types of ores in large igneous provinces, in which hydrocarbons are of major importance.

Primor’ye as a new promising region of Russia with gold-palladium-platinum ore mineralization of a nontraditional type

The following regionally distributed contact-metamorphosed metalliferous sediments occur in association with each other in the lower part (Upper Olenekian‐Ladinian) of the Triassic siliceous formation of the Sikhote-Alin, which is enriched in carbon: manganese‐silicate (metamorphosed siliceous‐rhodochrosite) rocks, “brown cherts” (cherts with pyrophanite and spessartine), tin‐iron ores, “ilmenite‐biotite‐feld spar” (metamorphosed argillous) rocks, and “itabirites” (gold-bearing jaspers). These rocks occur in association with the products of hydrothermal regeneration composing bodies of different morphology and composition, including deposits of manganiferous skarnlike (amphibole‐pyroxene) rocks and skarns [1‐3]. Metalliferous sediments and products of their regeneration contain nickel and cobalt sulfides, arsenides, antimonides, tellurides, sulfoarsenids, sulfoantimonides and sulfotellurides, minerals of rare earth elements, thorium, uranium, barium, vanadium, and other minerals. Furthermore, reduced forms of different metals are common: native elements, solid solutions, intermetallic compounds, phosphides, and silicides. Associations of the reduced forms occur in pores and microsize fissures with organic matter. They were formed during the contact-metamorphic process under high temperatures (according to the admixture concentration level of several elements in native metals) accompanied by hydrocarbon decay and hydrogen reducing of oxidized forms. In view of the degree of the metalliferous rock distribution and the usual presence in it of minerals of Au, Ag, Pt, and Pd (a separate publication devoted to these minerals has been prepared [5]), the question of the concentration level of noble metals in these rocks becomes very important. Analyses performed earlier [1, 3] could not give an unambiguous answer to this question. Although they revealed high concentrations of Au, Pt, and Pd in separate samples, they characterized only manganese‐silicate rocks, their amount was insufficient, and reproducibility was weak. The concentrations of Au and Pt were found to be lower (one order of magnitude or more) than was expected according to the results of the investigation of mineral forms and dissolution of samples in hydrofluoric acid. The following three analytical methods have been used in the present work: fire assay with atomic absorption (AA) finishing, ICP-MS, and AA. The results of the fire assay analysis were found to contradict the data from the microprobe investigation and dissolution of samples in hydrofluoric acid. As was established during the microprobe investigation of the cinder, the losses were connected with

Process of Accumulation of Metal Ions on the Interior Surface of apo-Ferritin: Crystal Structures of a Series of apo-Ferritins Containing Variable Quantities of Pd(II) Ions

Accumulation of metal ions on protein surfaces is an important subject in the field of materials science because these processes are applicable to the preparation of bioinspired inorganic materials. While previous studies related to this subject have focused on the preparation of nanomaterials using protein scaffolds, the detailed processes of metal ion deposition and metal core formation on a protein surface require clarification. Elucidation of the coordination structures of multinuclear metal binding sites on proteins at an early stage as well as intermediate and fully occupied stages of the metal ion deposition will help us to understand the reaction mechanisms so that desirable inorganic materials can be prepared using protein scaffolds. In this Article, we report on the detailed processes of accumulation of Pd(II) ions demonstrated by a series of X-ray crystal structural analyses of apo-ferritin (apo-Fr), an iron storage protein, containing different amounts of Pd(II) ions in the protein cage. We have identified the specific binding sites of Pd(II) ions and analyzed the dynamic changes in the coordination structure by a combination of the crystal structures and ICP quantitative analyses of apo-Fr containing low, intermediate, and high content of Pd(II) ions. Our studies on Pd(II).apo-Frs provide intriguing implications for the preparation of many other inorganic materials using protein surfaces.

Diamine functionalized gel-type resin as a support for palladium catalysts: Preparation, characterization and catalytic properties in hydrogenation of alkynes

Gel-type resin (FCN) obtained as a result of copolymerization of glycidyl methacrylate (20 mol%), styrene (77 mol%) and ethylene glycol dimethacrylate (3 mol%) and functionalized by amine groups is studied as the support for Pd-catalysts (0.5–2 wt% Pd). Pd/FCN catalysts are characterized by number of techniques (FTIR, UV–Vis, XPS, SEM and HRTEM) and tested in the hydrogenation of alkynes, 2-butyne-1,4-diol (B3-D) and phenylacetylene (Phc). Catalysts are prepared by incorporation of palladium to the swollen particles of FCN resin using THF solution of Pd(OAc) 2. In these conditions N and carbonyl groups of FCN polymer are involved in the bonding of Pd 2+ ions. This leads to decrease in swelling ability of polymer mass due to “crosslinking” of the polymer via Pd 2+ ions. Since the polymer-bound Pd species are only partially reduced under hydrazine treatment the reduced Pd/FCN samples swell less than pure FCN. In the reduced Pd/FCN samples, only at the lowest Pd-loading amounted to 0.5 wt% Pd, very well dispersed Pd-nanoclusters appear. At higher Pd content within the range 1–4 wt% Pd, the particles of Pd of size within the range 4–28 nm are formed and in all the samples the particles 8–16 nm in size predominate. In these catalysts, partial aggregation of Pd-nanoparticles proceeds, especially when the loading of Pd is higher than 1 wt%. The activity/selectivity behaviour of Pd/FCN catalysts is determined by the size of Pd-particles and swelling ability of polymer matrix under the catalytic run. In the presence of highly expanded catalysts with low Pd content, 0.5–1 wt% Pd, the alkynes substrates, B3-D or Phc are hydrogenated to alkene with selectivity 91–92% up to high alkynes conversion (90%). The suppression of alkene to alkane hydrogenation in the stage of alkynes is ascribed to high ability of Pd-centers to strong adsorption of alkyne substrate. It may also be related to steric hindrances of polymer in the vicinity of active Pd-centers caused by the swollen polymer network.

Effect of additive metals, Sn, Ga, and In in Ag-Pd-Au-Cu alloys on initial bond strength of 4-META adhesive cement to these alloys

The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au-Cu alloys consisted of 20%, 30% or 40% Pd, and 10%, 15% or 20% Cu, 20% Au, and Ag as balance. Besides, additive metals (Sn, Ga, and In) of 2% and 4% were added to these compositions. The addition of three additives, in general, increased the initial bond strength of the cement in comparison to the mother compositions (0% additives), although the degrees of effectiveness of the three additives were different and varied with their contents. Among these additives, a remarkable increase in bond strength was observed with the addition of In. The increase in Cu content, in many cases, resulted in an increase in bond strength at high Pd contents (30% and 40%), but a decrease at low Pd content (20%) in some cases. The positive effects of the three additives and Cu could be due to the formation of a suitable oxide layer for strong bonding with 4-META.

Increase of platinum group element concentrations in soils and airborne dust in an urban area in Germany

Since 1993, all new cars sold in the European Union had to be fitted with catalytic converters. Undoubtedly, these measures brought about a great progress concerning traffic emission controls. However, this technology also led to new emissions. A rapid accumulation of the catalytic active noble metals Pt, Pd, and Rh in the environment was observed and concern arose about potential environmental and health risks. This work aimed at a contribution to a monitoring of platinum group element (PGE) emission and accumulation by comparing analytical data, all generated in 1999 and in 2005 in an urban area in Germany. Oriented at the 1999 sampling strategy, soil and airborne dust samples were taken in 2005 at the same sampling sites located mainly close to heavily used roads in the region of Braunschweig. For the enrichment of the analytes, conditioned soil samples as well as loaded glass fiber filters from air sampling were transferred to the nickel sulphide fire assay. For analyses, the ICP-MS technique was applied. High Pt, Pd, and Rh concentrations were detected especially in top soil layers (0–2 cm) directly at the roadsides or on center strips. At one road outside the city, where traffic moved with a constant speed of about 80 km/h, maximum concentrations in soil were found to be 50.4 μg/kg for Pt, 43.3 μg/kg for Pd, and 10.7 μg/kg for Rh. PGE concentrations were the highest close to that road and exponentially declined with growing distance. At a second road, where vehicles run with a constant speed of 50 km/h, the highest concentrations were detected in the center strip soil: 88.9 μg/kg (Pt), 77.8 μg/kg (Pd), and 17.6 μg/kg (Rh). At a third crowded street in the centre of Braunschweig with stop and go traffic, the highest soil concentrations were determined, namely 261 μg/kg for Pt, 124 μg/kg for Pd and 38.9 μg/kg for Rh. The sampling of airborne dust at this roadside revealed for Pt 159 pg/m 3 air or 1730 μg/kg dust, for Pd 37.8 pg/m 3 air or 410 μg/kg dust, and for Rh 10.0 pg/m 3 air or 110 μg/kg dust. A comparison of analytical results of 2005 with those of 1999 revealed a distinct increase of PGE concentrations in soils closely along heavy traffic roads by a factor of 2.1 to 8.9; once even a factor of 15 was determined. The findings also document, that especially Pt and Rh concentrations were elevated in airborne dust.

Distribution of platinum group elements in road dust in the Beijing metropolitan area, China

Dust samples collected from the Beijing metropolitan area (China) were evaluated to determine the distribution and the concentration of platinum group elements (PGEs). The dust particles that were smaller than 100 mesh size fraction (150 μm) were analyzed after aqua regia digestion. Concentrations of Pt, Rh, and Pd were found to be between 3.96 and 356.3 ng/g, 2.76 and 97.11 ng/g, and 0.1 and 124.9 ng/g, respectively, in the urban areas of Beijing, whereas for the background samples collected from the suburbs of Beijing, the concentrations of Pt, Pd, and Rh were very low and ranged from 0.1 to 0.9 ng/g, 0.5 to 1.4 ng/g, and 0.8 to 2.2 ng/g, respectively. The distributions of PGEs in road dust were an accurate reflection of the levels of pollution and were found to match with the local traffic conditions. A strong positive correlation was established among all the elements found in road dust. This suggests that emissions of abraded fragments from vehicle exhausts may be the source of the high concentration of Pt, Rh, and Pd in road dust along the main roads of Beijing.

Characterization of Pd−Cu Alloy Nanoparticles on γ-Al2O3-Supported Catalysts

Cu-Pd/Al2O3 bimetallic catalysts have been characterized by XRD, TEM, and EDX techniques. The surface structure has been investigated by FT-IR spectroscopy of low-temperature adsorbed CO in the reduced and in the oxidized state. Evidence has been provided of the formation of Cu-Pd alloy nanoparticles, both of the alpha-phase (disordered fcc) and of the beta-phase (ordered CsCl-type). IR spectra suggest that Cu likely decorates the edges while Pd mostly stays at the main faces. Part of copper disperses as Cu+ on the support even after reduction. The presence of copper seems to modify strongly the sate of oxidized Pd centers in oxidized high-Pd content materials. The redox chemistry of the system, where Pd is reduced more easily than Cu, appears to be very complex.

Metalliferous sediments of the Triassic cherty formation in the Ol’ga ore district of primorye: Tin-noble metal ores of a new genetic type

The Triassic cherty formation of Sikhote Alin [1] hosts metalliferous deposits. They are commonly represented by siliceous‐rhodochrosite rocks and their metamorphosed analogues (primarily, consisting of Mn-silicates and aluminosilicates) with high concentrations of Ga, Au, Pt, Pd, and other metals [3]. In the Ol’ga district, the metalliferous deposits are also represented by chocolate-brown siliceous rocks (hereafter, brown cherts) and tin‐iron ores. The metalliferous deposits occur in the Middle‐ Late Triassic siliceous‐clayey sequence. They make up at least one ore-bearing unit (thickness of 5 m or more) represented by brown cherts with a manganese rock bed near the upper contact. The overlying tin‐iron ore bed varies from tens of centimeters to a few meters in thickness. Judging from locations of native exposures, talus, and alluvial fragments, the ore-bearing unit is developed over an area of no less than 20 km 2 (Fig. 1). The manganese rocks are composed of rhodonite, pyroxmangite, and spessartine with a maximum V 2 O 3 content of 0.20 wt % [2, 4]. The rocks contain kanoite, tephroite, manganactinolite, dannemorite, tirodite, pyrosmalite, pyrophanite, hubnerite, scheelite, native silver, native gold, minerals of the cobaltite‐ gersdorffite series, pentlandite, millerite, violarite, tetradymite, tellurobismuthite, and other minerals. The manganese rocks also include Au (up to 35 g/t), Pt (0.08‐ 0.33 g/t), Zn (up to 5.97 wt %), Cu (up to 0.64 wt %), Ni (up to 0.14 wt %), and Co (up to 0.10 wt %) [3]. Nearly all polished samples contain native silver dissemination up to 20 µ m in diameter. Gold grains ( n mm in size) extracted by the acid treatment of manganese rocks are characterized by a high grade of fineness

Synthesis and structural characteristics of carbon aerogels with a high content of Fe, Co, Ni, Cu, and Pd

High content metal carbon aerogels have been prepared by sol–gel polymerization of formaldehyde with potassium salt of 2,4-dihydroxybenzoic acid, followed by K+-exchange with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Pd(II) ions from an aqueous or acetoneous solution and subsequent supercritical drying with CO2. Carbonization at 1050°C, under an inert atmosphere, transforms the metal ion doped organic aerogels into metal and/or metal oxide nanoparticles-doped carbon aerogels. The resulting materials were characterized by means of elemental analysis, nitrogen adsorption, transmission electron microscopy and X-ray diffraction. The structural properties and metal concentration of the doped carbon aerogel depend on the type and valence of the precursor metal salt. The presence of some graphitic nano-ribbons was evidenced in the case of Fe-, Co-, and Ni-doped carbon aerogels.

The use of concomitant elements to evaluate an Ar–N 2 mixed-gas plasma by electrothermal vaporization inductively coupled plasma orthogonal time-of-flight mass spectrometry

The performance of an Ar–N 2 mixed-gas plasma was compared to an Ar plasma using electrothermal vaporization as a sample introduction source to an inductively coupled plasma orthogonal time-of-flight mass spectrometer. The effect of sample matrices NaNO 3 and Pd(NO 3) 2 on a multi-element solution was investigated in mass amounts ranging from 0.1 to 5 μg of the metal matrix (e.g., Na and Pd). Addition of 2% N 2 to the outer plasma gas of an Ar plasma reduced signal suppressions observed in the presence of high concentrations of Na and Pd at the expense of a large reduction in analyte sensitivity (ca. 83%). Signal profiles indicate that suppression may be caused, in part, by space charge effects that are dependent on the ion density of analyte and matrix ions. By reducing the magnitude of the signal from the N 2-free plasma by repositioning the torch away from the sampling cone, comparable immunity to excess matrix was observed when compared to a plasma with N 2 included in the outer plasma gas.

Surface segregation and homogenization of Pd 70Ag 30 alloy nanoparticles

Pd 70Ag 30 alloy nanoparticles were prepared using three different reducing agents at various pH values. The composition homogeneity inside the alloy nanoparticles was tuned by the reduction conditions. The surface segregation and homogenization during heating was then studied. Alloy nanoparticles with the smallest size and the highest homogeneity were prepared by the strongest reducing agent NaBH 4, and the change of surface composition after heating was the smallest. The surface segregation of Ag was small and the sintering was retarded by the high concentration of surface Pd or by the residual B from the reducing agent. There was significant surface segregation of Ag and sintering after heating for the alloy nanoparticles prepared by HCHO, where a higher concentration gradient existed inside the nanoparticles. The reducing capability of N 2H 4 was in between those of HCHO and NaBH 4 and the behavior of nanoparticles prepared by N 2H 4 also exhibited a behavior between those of the other two samples.

Molecular dynamics simulations of the structural and dynamic properties of graphite-supported bimetallic transition metal clusters

Molecular dynamics simulations were carried out for $\mathrm{Pd}\ensuremath{-}\mathrm{Pt}$, $\mathrm{Pd}\ensuremath{-}\mathrm{Rh}$, and $\mathrm{Pd}\ensuremath{-}\mathrm{Cu}$ nanoclusters supported on a static graphite substrate using the quantum Sutton-Chen potential for the metal-metal interactions. The graphite substrate was represented as layers of fixed carbons sites and modeled with the Lennard-Jones potential model. Metal-graphite interaction potentials obtained by fitting experimental cohesive energies were utilized. Monte Carlo simulations employing the bond order simulation model were used to generate initial configurations. The melting temperatures for bimetallic nanoclusters of varying composition were estimated based on variations in thermodynamic properties such as potential energy and heat capacity. Melting transition temperatures were found to decrease with increasing Cu (for $\mathrm{Pd}\ensuremath{-}\mathrm{Cu}$) and Pd (for $\mathrm{Pd}\ensuremath{-}\mathrm{Pt}$ and $\mathrm{Pd}\ensuremath{-}\mathrm{Rh}$) concentrations and are at least $100\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ higher than those of the same-sized free clusters. Density distributions perpendicular to the surface and components of the velocity autocorrelation functions in the plane of the surface indicate that one of the metals in the bimetallic nanoclusters wets the graphite surface more, and that this weak graphite substrate is able to structure the melted fluid in the first few monolayers. The wetting characteristics are dictated by the delicate balance between metal-metal and metal-graphite interactions. Components of velocity-autocorrelation functions characterizing diffusion of constituent atoms in these bimetallics suggest greater out-of-plane movement, which increases with Cu (for $\mathrm{Pd}\ensuremath{-}\mathrm{Cu}$) and Pd (for $\mathrm{Pd}\ensuremath{-}\mathrm{Rh}$ and $\mathrm{Pd}\ensuremath{-}\mathrm{Pt}$) concentrations. Deformation parameters showed that the core (Pd in $\mathrm{Pd}\ensuremath{-}\mathrm{Cu}$, Rh in $\mathrm{Pd}\ensuremath{-}\mathrm{Rh}$ and Pt in $\mathrm{Pd}\ensuremath{-}\mathrm{Pt}$) atoms diffuse out and the surface-segregated (Cu in $\mathrm{Pd}\ensuremath{-}\mathrm{Cu}$, Pd in $\mathrm{Pd}\ensuremath{-}\mathrm{Rh}$ and $\mathrm{Pd}\ensuremath{-}\mathrm{Pt}$) atoms diffuse into the nanoclusters upon melting. Near linear dependence of melting temperature on composition was found for unsupported clusters in our recent work, which results from the balance between the extent of surface melting and the radius of remaining solid core. Nonlinear dependence was found in these supported clusters, as a result of reduced surface melting at higher Pd concentrations, due to the substrate effect. Shell-based diffusion coefficients for layers perpendicular to the graphite substrate suggest surface melting to start from the cluster surface experiencing least influence of the graphite field. Surface melting was seen in all three nanoclusters, with calculated bond orientational order parameters revealing the order of $\mathrm{Pd}\ensuremath{-}\mathrm{Cu}>\mathrm{Pd}\ensuremath{-}\mathrm{Pt}>\mathrm{Pd}\ensuremath{-}\mathrm{Rh}$, for onset of melting. Cluster snapshots on the graphite substrate and calculated cluster diffusion coefficients indicate these nanoclusters to diffuse as single entities with very high diffusivities, consistent with experimental observations.

Magnetic properties of metallic glasses of the type Fe80−x Pd x B20 and Fe80−x Pt x B20

Amorphous alloys of the type Fe80−xPdxB20 and type Fe80−xPtxB20 for 0≤x≤50 have been investigated by means of 57Fe Mossbauer spectroscopy and magnetisation measurements in temperatures from 4.2 up to 300 K. Curie temperatures and crystallisation temperatures are found by DTMG-DTA method. Mossbauer spectroscopy magnetic field is observed to visible increase for x=1 and 1.5% at room temperature for Pd, while a decrease is observed for higher x values. Curie temperature for Pd alloys has a maximum at x=4 with T C=753 K, which supports enforcing influence of Pd at low concentrations of Pd for magnetic interactions. We discuss different explanations for these measurements and compare with other findings for high Pd concentrations and alloys with Pt instead of Pd.

Influence of Platinum and Palladium on Diffusion in β-NiAl Phase

A new inverse method is applied for the determination of interdiffusion coefficients in b- NiAl(Pt) and b-NiAl(Pd). The results show that substitution of Pt or Pd to b-NiAl accelerates the diffusion of aluminium. Within the studied composition range and for Al-poor aluminides, the cross coefficients are negligible except for high Pd contents

Geology, Petrology, and Controls on PGE Mineralization of the Southern Roby and Twilight Zones, Lac des Iles Mine, Canada

The Lac des Iles Pd mine, with reserves of 88 million metric tons (Mt) containing 1.51 g/t Pd, is hosted by the 2.69 Ga Lac des Iles intrusive complex in the southern Wabigoon subprovince of the Superior province of Canada. The known economic concentration of Pd occurs in the Mine Block intrusion, the central body of the intrusive complex, where gabbroic rocks range from leucogabbro to pyroxenite and show complicated textures, such as breccias, magma mingling, and pods and veins of pegmatite. The ore is characterized by low concentrations of sulfide (typically less than 3 vol %) and exceptionally high Pd contents (Pd/Pt ~10, Pd/Au ~13). Detailed mapping of the southern Roby and Twilight zones shows that early leucocratic rocks are barren and that the bulk of Pd was introduced by late melanocratic magmas. The average concentration of Pd in the melanocratic rocks, excluding the High-Grade zone, is estimated to be ~4 ppm. The concentrations of sulfur correlate positively with those of base metals, platinum group elements (PGE), and Au. Furthermore, sulfide grains commonly show exsolution textures. The evidence suggests a magmatic origin of the PGE mineralization where the PGE were concentrated in an immiscible sulfide melt in the parental magma. Bulk chemical compositions suggest that all mafic igneous rocks in the mineralized zones, except for late clinopyroxenite, are cogenetic. The hypothetical parental magmas have high MgO and low (~15× chondrite), unfractionated rare earth elements (REE) with (Ce/Yb)chondrite 35% of Pd in the deposit) on the eastern margin of the Roby zone have much higher concentrations of Pd than any other rocks and do not show correlations between sulfur and precious and base metals. Furthermore, the rocks are intensely and pervasively altered to actinolite, talc, anthophyllite, hornblende, chlorite, sericite, calcite, and quartz. These observations suggest subsolidus enrichment of Pd and mobility of S. The lack of apparent fluid pathways within the High-Grade zone and the distribution of the zone are consistent with the enrichment of Pd at high temperatures by fluids that originated from the mafic magmas. The textures of the Lac des Iles deposit are similar to those of contact-type PGE deposits, but there are fundamental differences between the two. The Lac des Iles deposit is not localized near the contact between the host intrusion and the country rocks and evidence of the assimilation of the host rocks is lacking. Instead, the mineralization at Lac des Iles has many features in common with layered intrusion-hosted deposits, in which pulses of primitive magma introduced the PGE. Unlike the quiescent magma chambers of most layered deposits, the magmas at Lac des Iles were intruded energetically, forming breccias and magma-mingling textures.

Improved dense catalytically active polymer membranes of different configuration to separate and react organics simultaneously by pervaporation

To form membranes with catalytic effectiveness in hydrogenation nano-sized palladium clusters were incorporated in polymeric membranes made from poly(ether- b-amide) (PEBA) mainly by a solution-casting method. Several configurations of the Pd in the membrane were tested to optimise the catalytic activity: homogeneously distributed in PEBA, homogeneously distributed in PEBA/poly(vinylpyrrolidone) (PVP) blend, homogeneously distributed in PEBA/PVP blend with silica filler, two-layer configuration, and surface coated PEBA-membranes. The membranes were characterised by SEM, XRD and pervaporation flux density. The catalytic activity was tested in the pervaporative membrane reactor by hydrodechlorination of chlorophenol and chlorobenzene in diluted aqueous solution saturated by hydrogen at 30 °C. The produced hydrochloric acid is proportional to the reaction and detected exclusively in the feed. The decrease of the feed-pH was used to monitor the reaction progress of chlorophenol hydrodehalogenation online. Alternatively, the hydrodehalogenation of chlorobenzene was traced by head space gas chromatography. An essential improvement of the homogeneous PEBA-membranes resulted in blending with PVP and adding silica filler. The calculated activity per gram of Pd in the hydrodechlorination of 4-chlorophenol increased about four times and an about two times higher conversion was detected, both at an even lower Pd content. The two-layered membranes at similar overall Pd content demonstrated about two times higher activity and conversion per time to related membranes with homogeneously partitioned Pd-nanoclusters. Surface coated membranes with a porous Pd-layer interconnected to the PEBA-membrane showed only at high Pd content a performance related to simple homogeneous membranes.