ABSTRACTS: January 1982
ABSTRACTS: January 1982
of current literature on the platinum metals and their alloys
Radiation Damage, Its Recovery and Platinum Lattice Location on Pt-Bombarded MgO
h. matzke, a. turos, p. rabette and o. meyer, J. Phys. C., 1981, 14, (23), 3333–3344
MgO single crystals with <100> orientation, implanted with 30keV Pt ions to doses of 9×1015 and 8×1016 ions/cm2 were analysed after bombardment and different annealing treatments. The crystals did not become amorphous, and the lattice disorder reached saturation after implantation with the lower dose. Damage recovery proceeded progressively with increasing temperature. The near-surface Pt gave the unexpected result that the critical angles of the impurity and of the host lattice were different. This was explained by coherent precipitation of Pt.
The Decomposition of Ammonia on the Flat(111) and Stepped(557) Platinum Crystal Surfaces
w. l. guthrie, j. d. sokok and g. a. somorjai, Surf. Sci., 1981, 109, (2), 390–418
NH3 adsorption, desorption, and decomposition to H2 and N2 were studied on flat(111) and stepped(557) single crystal faces of Pt by molecular beam surface scattering. Both surfaces show significant adsorption with sticking coefficients ∼ 1. The stepped surface is 16 times more reactive for NH3 decomposition than the flat surface. Kinetic parameters were determined from NH3 decomposition on Pt(111). The mechanism of NH3 decomposition on (557) was investigated.
The Au-Pt (Gold-Platinum) System
anon, Bull. Alloy Phase Diagrams, 1981, 2, (1), 66–70
Using cited references which give physical properties, the Au-Pt phase diagram has been constructed. Crystal structures for various ordered phases, equilibrium and metastable phase boundaries, lattice parameters, thermodynamics of the Au-Pt system and graphs of the compositional dependence of the lattice parameter of quenched disordered Au-Pt and miscibility gaps are presented. (45 Refs.)
The Phase Diagram of the Eu-Pt System and the Valence Behaviour of Europium and Ytterbium Intermetallics with Platinum
a. iandelli and a. palenzona, J. Less-Common Met., 1981, 80, (2), P71–P82
Differential phase, X-ray and metallographic studies of the binary phase diagram of the Eu-Pt system showed seven intermediate phases: Eu9Pt, Eu5Pt2, Eu3Pt2, Eu5Pt4, EuPt2, Eu2Pt7, and EuPt5. The valance behaviour in these phases together with the phases formed in the Yb-Pt system were studied by magnetic measurements and analysis of lattice dimensions, atomic volumes and ionic radii. The results showed that Eu and Yb can form intermetallic phases with Pt, containing divalent or trivalent ions.
SO2 Adsorption on Rh(110) and Pt(110) Surfaces
r. c. ku and p. wynblatt, Appl. Surf. Sci., 1981, 8, (3), 250–259
SO2 adsorption at low pressures (∼ 6 × 10−8 torr) on Rh(110) and Pt(110) surfaces was performed, and the S and O concentrations on the SO2-saturated surfaces were assessed. Heats of desorption of SO2 (or of its dissociation products on these surfaces) are > ∼ 225kJ/mole, indicating strong adsorption of SO2 on both surfaces. On Rh the O associated with SO2 can be titrated, but only ∼ 1/3 of the O associated with SO2 on Pt is accessible to titration. Differences between the results on the Rh(110) and Pt(110) surfaces are discussed.
Effect of Alloying Platinum on Structure Dislocation and High Temperature Creep
m. p. usikov, g. s. stepanova and e. i. rytvin, Izv. Akad. Nauk SSSR, Met., 1981, (5), 150–152
Studies were made of the effect of alloying Pt with 17 at.% Pd, Rh, Ir and Ru on dislocation structure and rate of creep during plastic deformation. The results showed that alloying Pt with Pd had practically no effect on structure dislocation with no increase in high temperature creep resistance. Alloying Pt with Rh, Ir, Ru (in order of increasing effect) substantially changed the structure dislocation with decrease in the rate of creep.
Successive Martensitic Transformations in Fe-Pd Alloys
r. oshima, Scr. Metall., 1981, 15, (8), 829–833
A study of the relationship between the f.c.t. and b.c.c. martensites in Fe-Pd alloys is presented. Fe-Pd alloys containing 23.6−30.6 at.%Pd were studied, and two successive martensitic transformations were seen in an Fe-29.7 at.%Pd alloy in the temperature range 40 to −196°C. The first was a thermoelastic transition from f.c.c. martensitic to an f.c.t. martensite and the second was a non-thermoelastic type from the f.c.t. martensite to a b.c.t. martensite. The b.c.t. martensite was observed for alloys with 25 and 28.7 at.%Pd quenched from the austenite to room temperature. The b.c.t. morphology suggests that the austenite transformed to martensite, going through a f.c.t. structure.
Stabilization and Strengthening of Pd80Si20 Metallic Glass
j. megusar and n. j. grant, Mater. Sci. Eng., 1981, 49, (3), 275–283
The effect of composition on thermal and mechanical stability of Pd80Si20 glass was studied after adding B and Zr. The addition of B destabilises Pd80Si20. Adding 3 at.%B and 1.5 at.%Zr gives an amorphous structure with increased thermal stability (Tg increases by 73K). Stabilised (Pd80Si20)0.955B3.0Ar1.5 glass behaves substantially elastically, as does Pd80Si20, when tested under identical conditions at 433K and slow strain rates. Controlled decomposition of Pd80Si20 also has an effect on general yielding and fracture strength at elevated temperatures.
Equilibrium Silicides of Palladium
j. a. wysocki and p. e. duwez, Metall. Trans. A, 1981, 12, (8), 1455–1460
The Pd-Si system was examined in the 13−25%Si range by X-ray diffraction, thermal analysis and metallography. The existence of compounds Pd5Si, Pd9Si2 and Pd3Si was confirmed. Pd5Si is monoclinic, while the other two are orthorhombic. These compounds form defect structures with low symmetry and large unit cells. No evidence for the existence of Pd4Si or Pd9Si4 was found.
Observation of the Coexistence of Superconductivity and Long-Range Magnetic Order in TmRh4B4
h. c. hamaker, h. b. mackay, m. s. torikachvili, l. d. woolf, m. b. maple, w. odoni and h. rott, J. Low Temp. Phys., 1981, 44, (5/6), 553–568
The a.c. electrical resistance, heat capacity, static magnetic susceptibility, thermal conductivity and linear thermal expansion coefficient were measured for superconducting TmRh4B4. The results indicate that the Tm3+ magnetic moments order at about 0.4K, while bulk superconductivity, which occurs at 9.8K, persists to temperatures below 60mK, which was the low temperature limit of the apparatus. Possibilities for the magnetic order are examined.
Formation of σ -Aryl Pt(II) Complexes in the Reaction of Aromatic Compounds with Pt(II) Salts and Their Oxidation by H2PtCl6
g. b. shul’pin and g. v. nizova, Kinet. Katal., 1981, 22, (4), 1061–1063
Heating of aromatic compounds (benzene, toluene, etc.,) with Na2PtCl4 in the mixture CF2COOH-H2O resulted in the formation of a σ -aryl Pt(II) complex which could be converted in the presence of H2PtCl6 to the well-known anionic σ -aryl Pt(IV) complex. The discovered σ -formed Pt(II) appears to be the intermediate compound in the H-D bulk of aromatic hydrocarbons catalysed by Pt(II) salts during hydrocarbon oxidation in the presence of H2PtCl6.
Platinum(0) and Palladium(0) Carbenoid Insertion into Mercury Salts of Metal Carbonyls
v. i. sokolov, a. a. musaev, k. v. bashilov and o. a. reutov, Izv. Akad. Nauk SSSR, Ser. Khim., 1981, (10), 2409–2411
The insertion of Pt(0) and Pd(0) into Hg salts of Mn, Re and Co carbonyls produced Pt and Pd compounds containing chains of various metals of the type: Re-Hg-Pt, Mn-Hg-Pd-Mn and Co-Hg-Pd-Co. Pd(IV) products stabilised by two electron-acceptors of metal carbonyl groups were prepared by double oxidative addition of Pd(PPh3)4 to BrHgMn(CO)5.
Interaction of Tin Chloride Platinum Metal Complexes with Triphenylphosphine and Triphenylphosphinoxide
p. g. antonov, iu. n. kukushkin, v. f. shkredov and v. i. anufriev, Khim. Khim. Tekhnol., 1981, 24, (8), 941–945
Studies were made of the compounds prepared by interaction of [M(SnCl3)5Cl]n− where M is Ru(II), Os(II), Rh(III) or Ir(III), with Ph3P and Ph3PO. The reaction with Ph3PO yielded [M(SnCl2OPPh3)5Cl]Cln−1 whereas with Ph3P it yielded (PPh3PH)n[M(SnCl3)5Cl] which changed after heating in air at 460K to [M(SnCl2OPPh3)n(SnCl3)5−nCl]. Spectroscopic and electroconductivity measurements were made.
Electronic Absorption Spectra of Trivalent Rhodium in Chloride Melts
e. p. alexandrov, b. d. vasin, v. a. ivanov and s. p. raspopin, Izv. Vyssh. Uchebn. Zaved., Tsvetn. Metall., 1981, 23, (5), 86–89
Systematic studies of absorption spectra of Rh containing chlorides (RhCl3, Na3[RhCl6], etc.) were performed over a wide temperature range. Octahedral symmetry of and spectroscopic parameters are determined. The use of the spectral method for controlling the Rh(III) concentration in dilute chloride solutions is suggested.
Polymer Films on Electrodes. 5. Electrochemistry and Chemiluminescence at Nafion-Coated Electrodes
i. rubinstein and a. j. bard, J. Am. Chem. Soc., 1981, 103, (17), 5007–5013
The electrochemical behaviour of 10−15 μ m thick films of the cation-exchange Nafion on substrates of Pt-containing (bpy = 2,2′-bipyridine), pyrolytic graphite or glassy C is described. The reaction of electrogenerated with oxalate dissolved in the solution leads to production of and light emission. Information about the mechanism of excited-state production, with evidence for penetration of the polymer film by oxalate, and also possible quenching of by is provided.
Oxidation State Changes of Palladium Oxide Films
j. genesca, m. rius de riepen and l. victori, Extended Abstracts, 160th Electrochemical Society Meeting, 81–2, Denver, Colorado, Fall 1981, 1477–1478
Coloured films, whose thicknesses increased with polarisation time, were made on Pd electrodes by anodic treatment in HClO4 and NaOH at potentials above that for O2 evolution. The films were analysed. Films were golden or dark brown and the colour intensified as polarisation time increased. Under anodic oxidation at high potentials an oxide is formed indistinguishable from PdO2. The reduction of PdO2 was observed when the oxidised electrode underwent a galvanostatic process. The coloured film vanished in air.
Effect of Ruthenium on the Anodic Behaviour of Ductile Chromium in Sulphuric Acid
n. d. tomashov, g. p. chernova and e. n. ustinski, Zashch. Met., 1981, 17, (4), 401–407
Studies of the corrosion and electrochemical behaviour of 0.1−0.4wt.% Ru-Cr alloy were performed in 40% H2SO4 at 65°C. It is shown that Ru inhibits active dissolution of the alloys by two mechanisms: by blockage (Ru is the solid solution) and by screening (Ru accumulates on the surface of the alloy).
Ruthenium-Based Mixed Oxides as Electrocatalysts for Oxygen Evolution in Acid Electrolytes
r. s. yeo, j. orehotsky, w. visscher and s. srinivasan, J. Electrochem. Soc., 1981, 128, (9), 1900–1904
Ru oxide, prepared by thermal decomposition, has the highest known initial electrocatalytic activity for O2 evolution in acid electrolyte. However, the Ru oxide is unstable in the electrolyte and exhibits an increase in O overpotential with time, probably due to a chemical transformation of the oxide from a lower to a higher valence state. The Ru was stabilised by preparing mixed oxides with Ir and/or Ta, by thermal decomposition. Electrocatalytic activities for O evolutions were determined, and were improved for these mixed oxides.
The Increase of the Passivation Ability and Corrosion Resistance of Stainless Steels by Surface Alloying with Palladium
g. p. chernova, t. a. fedoseeva, l. p. kornienko and n. d. tomashov, Zasch. Met., 1981, 17, (5), 513–519
Studies of electrochemical behaviour and corrosion resistance of steels 15X25T and 08X18H10T alloyed with Pd, by electrodeposition of thin layers of Pd from an electrolyte and subsequent diffusion, were performed in 20% H2SO4 at 100°C. It is shown that corrosion resistance of Pd surface alloyed steels was increased by several orders.
Dynamics of Light-Induced Water Cleavage in Colloidal Systems
d. duonghong, e. borgarello and m. grÄtzel, J. Am. Chem. Soc., 1981, 103, (16), 4685–4690
A transparent TiO2 sol (particle radius 200 Å) was produced and then loaded simultaneously with ultrafine Pt and RuO2 deposits. These had extremely high activity as water decomposition catalysts. Bandgap excitation of TiO2 generates H2 with a quantum yield of 30 + 10%, and O2 is produced stoichiometrically. When or rhodamine B was used as sensitiser H2O was decomposed by visible light. Adding MV2+ significantly increases H2 yield.
Photoproduction of I2, Br2 and Cl2 on n-Semiconducting Powder
b. reichman and c. e. byvik, J. Phys. Chem., 1981, 85, (15), 2255–2258
Cl2, Br2 and I2 were photoproduced in O2-saturated aqueous solutions containing halide ions and platinised semiconducting n-TiO2 powder. The platinised TiO2 powders are considered as many short-circuited Pt-semiconductor electrodes on which the photoassisted reactions take place. All oxidation rates were increased or started by using Pt-TiO2 powder and u.v. radiation. These reactions indicate that Pt-TiO2 powders can lead to a net conversion of solar energy to storable chemical energy.
x. hou, w. sibbett and b. weekley, Rev. Sci. Instrum., 1981, 52, (10), 1487–1489
A low surface-resistivity, semitransparent photocathode, consisting of a Pd-Ag-O-Cs layer, has been developed. It has near i.r. response which extends to cut-off wavelengths of ∼ 1.5 μ m. The processing scheme and its effect on the photoemission characteristics of this photocathode are described.
Photo-Oxidation of Water on the Surface of Hectorite Using trans -Diaquabis-(2,2’-bipyridine) ruthenium(2+) as Catalyst
h. nijs, m. cruz, j. fripiat and h. van damme, J. Chem. Soc., Chem. Commun., 1981, (20), 1026–1027
trans - (bpy = 2,2’-bipyridine) was shown to be an efficient redox catalyst for the oxidation of H2O, and enabled a catalytic water photooxidation system within an adsorbed layer to be constructed.
Two-Way Split Generates Hydrogen More Efficiently
New Sci., 1981, 92, (1274), 100
A practical H2 generating system from sun-powered H2O-splitting is based on particles of the semiconductor CdS and the catalyst RuO2. The particles split H2O to give H2 and OH−, forming H2O again and S. The new process could convert the H2S into useful H2 fuel and a marketable S product.
ELECTRODEPOSITION AND SURFACE COATING
Preparation and Surface Characteristics of Platinized Antimony-Doped Tin Oxide Films
g. b. hoflund, f. f. cox and h. a. laitinen, Thin Solid Films, 1981, 83, (2), 261–265
Thin Sb-doped Sn oxide films were platinised electrochemically from a H2PtCl6.6H2O solution. Spectroscopic studies of the surface composition and electron structure showed that Pt appears predominantly as Pt° with a small amount of Pt(OH)2, whereas the Sn was predominantly SnO2 with some SnO present.
Palladium-Nickel: An Alternative to Gold
k. schulze-berge, Galvanotechnik, 1981, 72, (9), 932–936
Pd-Ni alloy electrodeposited coatings were compared to Au electrodeposited coatings. Organic additives have been developed for the Pd-Ni deposits; making them fully bright and only needing to be levelled. Technical properties for Pd-Ni coatings are similar to those for Au.
Electrolytic Rhodium Deposition
m. branik and f. kummer, Galvanotechnik, 1981, 72, (11), 1175–1180
Commercially available Rh electrolytes used for decorative and technical applications have a sulphate or phosphate base. The relationships between deposition parameters and their influence on the Rh deposits are discussed. A new method for measuring the lightness of colour of the Rh deposit used in decorative applications is proposed. Good quality electrolytes have no effect with regard to the lightness of the Rh deposits.
LABORATORY APPARATUS AND TECHNIQUE
Microsampling Technique in Flame Atomic Absorption. Application in Preparation of Platinum-Ruthenium Alumina Catalysts
h. urvain and n. martin, At. Spectrosc., 1981, 2, (4), 127–129
Microsamples of catalysts prepared by impregnating Al2O3 pellets by an active-element species, such as PtCl6H2 or RuCl6H2 in HCl acid media, were drawn from the solution and the decreases in Pt and Ru concentrations were determined as a function of time. The analysis has advantages over continuous sampling methods in that very small samples, 100 μ l, can be withdrawn, several elements can be determined from the same sample, or a wide working range (50–2000 mg/l) can be used with reproducible sensitivities and no memory effects. The tolerance for solutions with high salt content and residual solid particles is improved without clogging.
Platinum on Carbon-Fibre Paper Catalysts for Methanol Electro-Oxidation. Part 2. Role of Platinum Surface Area in Determining Catalytic Activity for Methanol and Formic-Acid Electro-Oxidation
b. d. mcnicol, d. attwood and r. t. short, J. Chem. Soc., Faraday Trans. I, 1981, 77, (9), 2017–2028
The intrinsic catalytic activity of Pt supported on pre-oxidised C-fibre paper depended on the Pt surface area for both methanol and formic acid electro-oxidation. The activity for formic acid oxidation decreases as the Pt surface area decreases, whereas that of methanol initially increases then decreases with decreasing Pt area, thus producing a maximum in the activity/surface area relationship. The effects are explained in terms of the mode of adsorption of the fuels on Pt and their oxidation mechanism.
Deuterium Exchange between Water Mists and Hydrogen Gas in a Hydrophobic Catalyst Bed
y. asakura, h. tsuchiya, h. yusa and s. matsuda, Nucl. Sci. Eng., 1981, 79, (1), 49–55
The deuterium exchange reaction between D-enriched water mist and H2 was studied with a hydrophobic Pt/porous Teflon supported catalyst. The water mists and H2 moved downward co-currently, through the catalyst bed. This new method improved the poor contact efficiency between water and H2 gas in the catalyst bed. The reaction rate increased an order of magnitude over the conventional method where liquid water and H2 react countercurrently. The increased rate was due to the increase of D transfer at the water/gas interface. The reaction rate determining process changed with H2 gas flow.
Effect of Platinum Concentration in Pt/Al2O3 Catalysts on Dehydrogenation Reaction of High Molecular Weight n-Paraffins
e. a. timofeeva, a. p. tiunaev and g. v. isaguliants, Izv. Akad. Nauk. SSSR, Ser. Khim., 1981, (9), 2067–2071
Studies of the effect of concentration of 0.05−1.0% Pt on the dispersity of Pt/Al2O3 catalysts with and without 1% Li were performed during n-dodecane dehydrogenation at 480°C under H2 pressure. The increase in Pt concentration in the catalysts was followed by a decrease in their dispersity. The selectivity of the catalysts was not affected by Pt concentration but depended on the Li present. Catalysts containing 0.25−1.00% Pt had similar specific activity during n-dodecane dehydrogenation. The catalysts containing 0.05% Pt showed higher specific activity than catalysts with higher Pt concentrations.
Influence of Temperature and Thermal Processing Atmosphere on Properties of Platinum Catalysts Used for Complete Oxidation
s. kulak and j. wrzyszcz, Przem. Chem., 1981, 66, (6), 326–328
Pt/Al2O3 catalysts were heated in oxidising and reducing atmospheres, in CO2 and combustion gases at up to 1300K. The heating resulted in a decrease of Pt dispersion in the catalyst, dependant on the atmosphere. An increase of catalyst activity was observed during the complete oxidation of hydrocarbons after heating in combustion gases and CO2, as well as after heating in air or H2.
Studies on the Isomerization of n-Pentane on γ -Al2O3 Supported Pt Catalyst Modified by Adsorbed Bi and Pd
m. hegedus, s. gobolos, s. szabo, d. moger and f. nagy, Magy. Kem. Foly., 1981, 87, (7), 324–328
The isomerisation of n-pentane on Bi-Pt/γ -Al2O3 and Pd-Pt/γ -Al2O3 catalysts was investigated by pulse and continuous flow reactors. The activity of the catalysts was smaller than that of the base Pt/γ -Al2O3 catalyst. The selectivity of Bi-Pt/Al2O3 for isomerisation was higher than that of the other two catalysts investigated. The behaviour of the Bi-Pt catalyst gradually approaches that of the base catalyst. The selectivity and stability for the Pd-Pt catalyst were the smallest, but the extent of cracking on this catalyst was larger than that of the other two.
The Effects of the Nature and the Structure of Platinum Group Catalysts on Their Poisoning and Regeneration
a. a. sutyagina and g. d. vovchenko, Surf. Technol., 1981, 13, (3), 257–264
The poisoning of Pt, Pd, Rh, Os, Ru and Rh-Os alloys by Hg, S and Pb was investigated. The capacity for being poisoned depends not only on the nature of the catalyst, but also on its structure and surface morphology. Chemical compounds are formed when Pt, Pd and Rh catalysts are poisoned, but not for Os and Ru. Different types of interactions and surface distribution of poison were seen for poisoning of Pt and Rh with S and Pb. Electrochemical methods were found for regeneration of the poisoned catalysts.
Hydrogenation of Coal Oil from Coal from the Saar to Petroleum
t. jacobsen and e. gallei, Erdoel Kohle Erdgas Petrochem., 1981, 34, (10), 447–450
Hydrogenation of coal oil by liquefaction of coal is described. The three stages of raffination, hydrocracking and reforming are explained. Because the coal oil has a high N content raffination is operated at higher pressures than refining the petroleum fraction, to achieve the high level of N in the middle oil fraction which is needed for hydrocracking feedstocks (5−10 ppm). Zeolite supported noble metals were used at the hydrocracking stage, Pt-Re is mentioned. For reforming, the catalyst and operating conditions are similar to those for petroleum naphtha reforming. The product is gasoline with premium gasoline quality without Pb additives. It has higher specific gravity than commercial gasoline.
The Effect of SMSI (Strong Metal-Support Interaction) Behavior on CO Adsorption and Hydrogenation on Pd Catalysts. I. IR Spectra of Adsorbed CO Prior to and during Reaction Conditions. II. Kinetic Behavior in the Methanation Reaction
m. a. vannice, s.-y. wang and s. h. moon, J. Catal., 1981, 71, (1), 152–166, 167–174
Infrared spectra and kinetic data were measured under steady-state conditions on Pd/support catalysts. The i.r. spectra of CO adsorbed on Pd/TiO2, Pd/SiO2-Al2O3, Pd/Al2O3 and Pd/SiO2 were obtained. H2 reduced the CO band intensities for Pd/TiO2 (SMSI) catalyst, but under reaction conditions no CO bands were detected, while all other Pd catalysts had observable i.r. bands. Only a small fraction of the Pd surface atoms are active sites and the large CO surface concentrations detected by i.r. are not directly involved in the rate-determining step for methanation. Specific activity of Pd in methanation can show a 200-fold variation depending upon the support used. But CH4 turnover frequencies were independent of Pd crystallite size. Turnover numbers increase Pd/SiO2 ≪ Pd/SiO2-Al2O3, Pd/Al2O3, ≍ Pd/TiO2 < Pd/TiO2 (SMSI).
Kinetics of Hydrogenation of Benzene on Deposited Palladium Catalysts
o. v. baidus, t. n. maslianskii, v. p. gil’chenok and a. c. moshkevich, Neftekhimiya, 1981, 21, (4), 508–514
Studies of benzene hydrogenation were performed on deposited Pd catalysts supported on Al2O3-SiO2, γ -Al2O3 and γ -Al2O3 + A (A is an additive which increases the acidity of the support) at 190−270°C and 2.0−4.0 MPa. The order of the reaction near zero did not depend on the nature of the supports, whereas the order of the reaction in H2 did depend on the nature of the support, changing in the range 1.0 to 1.6. The values for the apparent activation energy are similar and are between 59.6−65.0 kJ/mole.
Effects of Metal-Support Interactions on the Synthesis of Methanol over Palladium
ya. a. ryndin, r. f. hicks, a. t. bell and yu. i. yermakov, J. Catal., 1981, 70, (2), 287–297
The synthesis of methanol and other products from CO and H2 was studied over Pd catalysts prepared by adsorption of Pd(π -C3H5) on various supports and Pd/SiO2 prepared from PdCl2 and Pd black. Both the activity and selectivity of Pd were affected strongly by the support and composition of the Pd precursor. The specific activity for methanol synthesis decreased in order Pd/LaO3 ≫ Pd/SiO2 (derived from PdCl2) > Pd/ZrO2 > PdZnO ≍ Pd/MgO > PdTiO2 > Pd/Al2O3 ≍ Pd/SiO2 (derived from Pd(π -C3H5)2) ≫ Pd black. Pd/TiO2 had highest specific activity for hydrocarbon synthesis, and the order of activity for this and for dimethyl ether production were found.
Supported Liquid Phase Hydroformylation Catalysts Containing Rhodium and Triphenylphosphine. Effects of Additional Solvents and Kinetics
j. hjortkjaer, m. s. scurrell, p. simonsen and h. svendsen, J. Mol. Catal., 1981, 12, (2), 179–195
Catalysts containing HRh(CO)(PPh3)3 and excess PPh3 supported on SiO2 show some modification in behaviour during hydroformylation of propene if additional solvents are present. The effect of PPh3 loading on the kinetic parameters is discussed in terms of an increasing tendency for PPh3 to become highly mobile at sufficiently high loadings.
Improvement of the Catalytic Performance of a Ruthenium Powder in Ammonia Synthesis by the Use of a Cyclic Procedure
g. rambeau and h. amariglio, Appl. Catal., 1981, 1, (5), 291–302
H2 inhibits the catalytic activity of Ru in NH3 synthesis. Lowering the H2 content lowers the temperature at which the reaction is detectable, but does not allow a high NH3 production rate. This is avoided by alternate N2 and H2 feeds. The improvement is higher the larger the catalyst area. With 1 m2 active area the average rate of production is eight times higher than the best steady rate of production, and the increase is ∼ 103 at 200°C, if the average rate is compared with the steady state rate corresponding to the stoichiometric mixture. Ru dispersed catalysts at only 300°C and atmospheric pressure could obtain the same industrial performance as Fe catalysts.
Ammonia Synthesis as a Catalytic Probe of Supported Ruthenium Catalysts: the Role of the Support and the Effect of Chlorine
w. k. shiflett and j. a. dumesic, Ind. Eng. Chem. Fundam., 1981, 20, (3), 246–250
The effects of the support and the presence of Cl− on the properties of highly dispersed Ru/γ -Al2O3 and Ru/SiO2 catalysts were studied during NH3 synthesis. The rate of NH3 synthesis was inhibited by NH3 more strongly on Ru/Al2O3 than on Ru/SiO2. This indicates that the Ru is electron deficient when supported on Al2O3 compared to Ru on SiO2; Cl as an Al2O3 support constituent suppressed the synthesis rate, increasing both the apparent activation energy and the inhibiting effect of NH3 on the reaction rate. The results were consistent with an additional decrease in electron density on the Al2O3-supported Ru induced by the presence of chloride on the support.
Terpene Amine Synthesis via Palladium-Catalyzed Isoprene Telomerization with Ammonia
w. keim and m. rÖper, J. Org. Chem., 1981, 46, (18), 3702–3707
Isoprene and dry NH3 were converted into a mixture of primary, secondary and tertiary terpene amines via homogeneous catalysis with Pd acetylacetonate and tributyl phosphite, which had the best activities and selectivities for telomerisation. Seven amines were isolated and characterised.
Hydrogenation and Isomerization of Olefins on Heterogenized Rhodium Complexes
t. uematsu, t. kawakami, f. saitho, m. miura and h. hashimoto, J. Mol. Catal., 1981, 12, (1), 11–26
The catalytic properties of polymer-bound complexes RhCl(PPh3)3, bound to three types of phosphinated polystyrene, were studied during hydrogenation and isomerisation of olefins in the gas-solid heterogeneous system. The results were compared with those for the complex on SiO2 and those in the homogeneous system. The selectivity for the isomerisation of butene was increased over supported catalysts. Catalytic activity for the hydrogenation was increased by anchoring on the rigid polymer when loading on SiO2, while it decreased remarkably by anchoring on the inner phosphine groups of the copolymer. The results are explained in terms of the availability of the sites, the structure of the actual species, and the carrier effects caused by binding.
Investigation of Unique Metal Complexes Produced with Polystyrene-2,2’-Bipyridine and Several Hydrogenation Catalysts Derived from this Copolymer
r. s. drago, e. d. nyberg and a. g. el a’mma, Inorg. Chem., 1981, 20, (8), 2461–2466
Cleavage reactions between PS-bound pyridine (py) and 2,2’-bipyridine (bpy) ligands and dimers [Rh(X)(CO)Cl2], [P], (X = CO, (C6H5)3P or (tol)3P) were studied. [P]-py cleavages produced products analogous to those found homogeneously and [P]-bpy reactions formed several metal complexes not found in solution. The supported Rh systems [P]-bpy Rh, [P]-bpyPdCl2 and [P]-bpyPtCl2 were investigated as hydrogenation catalysts. The [P]-bpy PtCl2 system is an active catalyst for hydrogenations on substrates.
A Greatly Improved Procedure for Ruthenium Tetraoxide Catalyzed Oxidations for Organic Compounds
p. h. j. carlsen, t. katsuki, v. s. martin and k. b. sharpless, J. Org. Chem., 1981, 46, (19), 3936–3938
The addition of acetonitrile to the traditional CCl4/H2O system for RuO4 catalysed oxidations leads to a greatly improved system. Some applications to olefins, alcohols, aromatic rings and others are described.
Homogeneous Hydrogenation of Carbon Monoxide by Iodide-Promoted Ruthenium Catalysts
b. d. dombek, 182nd Am. Chem. Soc. Natl. Meeting, New York, Aug. 23–28, 1981
A new type of homogeneous Ru catalyst has been developed for hydrogenating CO to methanol, ethanol and free ethylene glycol, where glycol is the major product. The system has basic promoters, such as ionic iodide promoters and polar solvents. Typical promoters include NaI, KI or bis(triphenylphosphine)iminium iodide and typical solvents are N-methylpyrrolidone, sulfolane and 18-crown-6. The new system has activity, substantially higher than known Ru catalysts.
Triphenylphosphine Ruthenium(II) Complex with Tin(II) Trichloride and Its Catalytic Properties
p. g. antonov, n. v. borunova, iu. n. kukushkin and l. kh. friedlin, Khim. Khim. Tekhnol., 1981, 24, (6), 663–665
The prepared complex catalyst [Ru(PPh3)2(SnCl3)Cl] was found to be active during hydrogenation of unsaturated hydrocarbons but was inactive during isomerisation. The rate of olefin and diene hydrogenation was very high. The activity of the catalyst was 4–5 fold higher than that of [Ru(PPh3)3Cl2]. The presence of strongly trans -orientating ligands in the sample increased its catalytic activity and also the stereospecifity of diene hydrogenation.
ELECTRICAL AND ELECTRONIC ENGINEERING
Contact Resistance Measurements of Platinum-Silicide and Chromium Contacts to Highly Doped n and p Silicon
g. boberg, l. stolt, p. a. tove and h. norde, Phys. Scr., 1981, 24, (2), 405–407
A comparison of contact resistivity for Pt silicide contacts and sputtered Cr contacts on heavily doped n− and p-Si was made by a method suitable for contacts of a highly conductive surface layer on a less conductive base material. The results showed less spreading and lower specific contact resistance for PtSi contacts on both n+ and p+-Si, than for Cr contacts which with p+ showed non-ohmic behaviour.
Palladium with a Thin Gold Layer as a Sliding Contact Material
t. sato, y. matsui, m. okada, k. murakawa and z. henmi, IEEE Trans. Components, Hybrids, Manuf. Technol., 1981, CHMT-4, (1), 10–14
Two types of electroplated Pd contacts, one with a thin Au layer, were evaluated as substitutes for Au. The Au deposit properties were as good as acid hard gold deposits. Friction coefficients were 0.4–0.7 for electroplated Pt and 0.15–0.3 for electroplated Au. The multilayer contact had friction properties similar to those of Au contacts, and the Au acted as a lubricant between the harder Pd electroplates. Pd had good results in 1000-hour corrosion tests in an 80%N2−20%O2 atmosphere containing 10 ppm H2S.