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Platinum Metals Rev., 1967, 11, (2), 70

ABSTRACTS: April 1967

of current literature on the platinum metals and their alloys

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PROPERTIES

The Thermal Conductivity and Electrical Resistivity of Polycrystalline Metals of the Platinum Group and of Single Crystals of Ruthenium

r. w. powell, r. p. tye and m. j. woodman, J. Less-Common Metals, 1967, 12, (1), 1–10

Thermal conductivity and electrical resistivity values for Ru, Os, Pd, Rh and Pt at 300−500°K are reported. Similar studies were made at 80−500°K on polycrystalline samples of Ru, Rh, Ir and Pt and on single-crystal Ru rods with crystallographic axes parallel and perpendicular to the axis of the rod. Minima occurred in the thermal conductivity-temperature curves of three Ru samples measured at temperatures below normal. See Platinum Metals Rev., 1966, 10, (4), 132.

The Thermal Conductivity of Platinum between 300 and 1000°K

m. j. laubitz and m. p. van der meer, Canad. J. Phys., 1966, 44, (12), 3173–3184

Thermal conductivity measurements for high-purity Pt at 300−1000°K agree with the work of Bode, and of Martin and Sidles, but disagree with the work of Powell and Tye at higher temperatures. The variation with temperature T implies that, at high temperatures, the electronic Lorenz number of Pt is an increasing function of T, exceeding the Sommerfeld value, which can be explained by assuming a low Fermi energy for Pt.

Influence of Purity on Some Properties of High Melting Metals

e. raub and e. röschel, Metall, 1967, 21, (1), 1–9

A discussion on differences in the mechanical properties of Pt, Pd, Ir and Rh and on the influence of purity on their cold-strengthening, recovery and heat resistance is illustrated by results from tests on the effects of metallic impurities on the properties of Pt. As an electron beam volatilises Pd, Au and Ag, less volatile Rh and Ir raise the recovery temperature of Pt.

The Colours of Some Metals and Alloys

g. e. gardam, Trans. Inst. Met. Finish., 1966, 44, (5), 186–188

The spectral reflectivity curves of a number of perfectly polished metals and electroplated coatings were measured using a simplified spectro-photometer and were used to calculate the chromaticity coefficients, luminance and position of each in the colour triangle. Rh is very near the white point; Pt and Pd are displaced slightly towards the yellow; Cu, Au and their alloys have red/yellow colours heavily diluted with white. Rh, Pt, Pd and Au have luminances of 0.815, 0.671, 0,642 and 0.706, respectively.

The Structure of Thin Platinum Sheet

j. b. hanley and w. i. mitchell, J. Materials Sci., 1966, 1, (4), 412–413

Electron microscopy of 12 μ m Pt foils, prepared by cold rolling at room temperature followed by electropolishing in molten NaCl at 801°C, revealed that pure cast Pt had a fully recovered structure with grain size 2–3 μ m, that pure sintered Pt had spheroidal defects and a finer grain size, and that sintered Pt containing ThO2 had a high dislocation density indicating retarded recovery. The difference in mechanical properties appeared to be due to spheroidal defects resulting in dispersion of porosity.

The Temperature Dependence of the Surface Energy Anisotropy of Platinum

m. mclean and h. mykura, Surface Sci., 1966, 5, (4), 466–481

Measurements of the variation of the surface free energy γ of Pt with crystallographic orientation at 920−1500°C by the twin boundary groove technique showed that anisotropy decreased with increased temperature. Faceting to {111} and {100} was observed over part of this temperature range. Early roughening of complex surfaces is believed to account for discrepancies between theory and experiment. Surface “melting” may begin at ∼1230°C, {100} surfaces “melt” at ∼1350°C and {111} surfaces remain atomically smooth to at least 1600°C and probably to the lattice m.p.

The Electrical Resistance of Platinum at Repeated Quenching. I. The Reversible Change

a. čižek, Czech. J. Phys., 1966, B16, (10), 842–854

Studies by repeated quenching from high temperature of the reversible change in the electrical resistance of Pt wires of three different radii determined the quench temperature at which the concentration of quenched-in vacancies is independent of quenching rate or of wire diameter as 1070±50°K, i.e. (0.53±0.02) Tm, indicating an high stacking fault energy.

The Low-temperature Specific Heat of Some Dilute Platinum-Iridium and Platinum-Gold Alloys

m. dixon, f. e. hoare and t. m. holden, Proc. Phys. Soc., 1967, 90, (1), 253–261

Specific heat measurements at 1.2−4.2 °K are reported for 1.98, 3.89, 5.80, 7.80 and 9.83 at.% Ir-Pt and for 2.00, 3.93, 5.98 and 8.22 at.% Au-Pt. Results were analysed in terms of electronic and lattice specific heat contributions but a constant term of uncertain origin remains.

Thermodynamic Properties of Copper-Platinum Alloys

j. m. mccormack, j. r. myers and r. k. saxer, Trans. Met. Soc. A.I.M.E., 1966, 236, (11), 1635–1638

The Knudsen effusion technique was used to study the chemical activity, a, of Cu-Pt alloys containing 90.0, 74.0, 59.2, 29.9 and 14.7 at.% Cu at 1542−1673 °K. a Cu and a Pt showed negative deviation from Raoult’s Law and a Cu showed increasing ideality with increasing temperature due to ordered phases. The integral free energy has a minimum value of 4.2 kcal/mole at ∼55 at.% Cu, the excess free energy is negative with a minimum at ∼55 at.% Cu and the integral enthalpy is negative with a maximum value of 3.4 kcal/mole. At higher temperatures 64−71% Cu-Pt alloys melt to give two phases resulting in straight line plots for free energy, enthalpy and entropy.

Equiatomic Transition Metal Alloys of Manganese. V. On the Magnetic Properties of the PtMn Phase

a. f. andresen, a. kjekshus, r. møllerud and w. b. pearson, Acta Chem. Scand., 1966, 20, (9), 2529–2534

X-ray, neutron diffraction and magnetic susceptibility studies of Pt45Mn55, Pt50Mn50 and Pt55Mn45 indicate that they are antiferromagnetic with spin quantum numbers 2SMn = 4.0±0.2 and 2SPt < 0.2. Pt35Mn65 is weakly ferromagnetic below ∼250°K and has Néel temperature ∼710°K.

Magnetic Properties of Ordered Pt-Co

p. brissonneau, a. blanchard and h. bartholin, I.E.E.E. Trans. Magnetics, 1966, 2, (3), 479–482

50 at.% Co-Pt may be ordered to a tetragonal CuAu-type structure. An ordered single crystal is a system of tetragonal crystallites with c axes parallel to the Ox, Oy, Oz axes of the disordered matrix. Room temperature studies on an ordered macrocrystal with unequal relative volumes of three types of crystallites indicated magnetisation far less than saturation even in an applied field of 3.104 Oe, i.e. large anistropy energy. Js = 790 emu/cm3 and K = 5.107 ergs/cm3. Results probably account for discrepancies in previous data.

Preparation and X-ray Investigation of Platinum Alloys with the Rare-earth Metals (Pt5Ln and Pt3Ln Phases)

w. bronger, J. Less-Common Metals, 1967, 12, (1), 63–68

Pt5Ln phases were prepared by reacting Pt with the La to Tm series in H2. X-ray studies indicated three related structure types. Lighter rare earths formed Cu5Ga-type structures with Pt; heavier rare earths formed new but similar structures; Pt3Ln with the Ho to Lu series have Cu3Au-type structure.

On the Equilibrium between Monatomic and Diatomic Palladium and the Appearance Potential of Pd2

k. a. gingerich, Naturwissenschaften, 1967, 54, (2), 43

Mass-spectrometric studies showed that the lowest temperature at which diatomic Pd appeared was 1975°K. Appearance potential of Pd+ was 7.7±0.3 eV. Partial pressure ratios Ppd/Ppd2 at 1975, 2025, 2085°K were 3.3 × 105, 2.5 × 105, 1.4 × 105 respectively.

Destruction of Short Range Order in Au-Pd Alloys by Cold Working

t. e. fine and m. e. nicholson, Abs. Bull. Inst. Met. Div., Met. Soc. A.I.M.E., 1966, 1, (2), 77

X-ray studies of the influence of plastic deformation on short range order in 45 and 60 at.% Pd-Au alloys showed that α1, the local order parameter, which was negative for both alloys, decreased logarithmically as the true strain increased. Annealed values of α1, were determined for 23.5, 33.0, 45.0, 60.0, 75.5 and 90.5 at.% Pd-Au and exhibit a roughly parabolic relation to composition, with 45 at.% Pd-Au having the most negative value. The curve calculated from heat of mixing data is similar but absolute values do not agree in the low concentration ranges, presumably due to corrections which compensate for systematic errors.

Magnetic Behaviour of Binary and Ternary Mixed Crystals of Palladium with Rhodium and Silver

e. vogt, e. oehler and w. treutmann, Ann. Physik, 1966, 18, (3–4), 168–177

Results of susceptibility measurements at ∼90−800°K on binary Pd-Rh and Pd-Ag alloys or ternary alloys with Rh:Ag contents 1 at.%−1 at.%, 3 at.%−3 at.%, 5 at.%−5 at.%, 8 at.%−2 at.%, 10 at.%−4 at.%, 12 at.%−6 at.% are discussed within the scope of the rigid-band model. The ternary alloys show weaker paramagnetism than this model leads one to expect. Results can be applied to selecting alloys of required susceptibilities.

Consequences of the Proton Model for Hydrogen Absorption in the β Phase of the Hydrogen-Palladium System

t. b. flanagan and j. w. simons, J. Phys. Chem., 1966, 70, (11), 3750–3751

The equation In for the equilibrium between H2 gas and H absorbed in Pd at contents greater than those of the two-phase region, i.e. contents in the β-phase region, where n = H/Pd, is shown to follow directly from extensions of Lacher’s statistical model where a variable energy of electron donation to the electronic band of Pd is included.

Internal Friction of Palladium Containing Hydrogen

r. r. arons, j. bouman, m. wijzenbeek, p. t. a. klaase, c. tuyn, g. leferink and g. de vries,

Acta Met., 1967, 15, (1), 144–147

After loading electrolytically with H2, 0.3 mm 99.999% Pd wire at 2.7 Hz showed two internal friction peaks: A at 75°K; B at 105°K. The height of A was dependent on concentration of H2 and was attributed to stress induced ordering of H2 pairs in the β phase. B was observed only if H2 and deformations were present and was dependent on purity and annealing conditions, and decreased on addition of C. The activation energies of H2 and D2 in the system differed by 850 cal/mole. Loading with a mixture of H2 and D2 gave a single narrow peak between those obtained with the pure gases.

Thermodynamic Properties of Pd-Cd and of Pd-Sb Alloys

j. b. darby, k. m. myles and j. n. pratt, Abs. Bull. Inst. Met. Div., Met. Soc. A.I.M.E., 1966, 1, (2), 14

Enthalpies of formation of several solid Pd-Cd and Pd-Sb alloys were all exothermic, when determined by liquid-Sn solution calorimetry, and those of the Pd-rich primary solid solutions were larger than those of Pd-rich Pd-Ag alloys. Activities of Pd-Cd alloys were measured by the dew-point method. Pd-Cd alloys were predominantly rich in Pd and were in the α, α prime, and β phase regions. Pd-Sb compositions were in the known single-phase regions.

The Crystal Structure of Pd4.8P

b. sellberg, Acta Chem. Scand., 1966, 20, (8), 2179–2186

A single crystal X-ray diffraction study of Pd4.8P revealed a cell content of 18 Pd atoms in 2(a) positions with space group P2 and unit cell dimensions a = 5.004 Å, b = 7.606 Å, c = 8.416 Å, maximum error of±0.0005 Å; β = 95.63±0.0005 Å and U = 318.8 Å3.

Rare-earth Intermediate Phases. IV. The High-temperature Lattice of Some R.E.Pd3 Phases

i. r. harris, g. v. raynor and c. j. winstanley, J. Less-Common Metals, 1967, 12, (1), 69–74

CePd3 has much greater lattice expansion with increasing temperature than GdPd3, YbPd3 or SmPd3, probably because variable occupancy of 4 f states in Ce causes conduction band → 4 f transitions. Expansion characteristics of YbPd3 and YbIn3 differ, probably due to the valency states of Yb in them.

On the Superconductivity of Hf-Rh Alloys

h. wühl, Z. Physik, 1966, 197, (3), 276–287

Rh strongly increases transition temperatures Tc of quenched Hf-Rh alloys in the hexagonal phase, as with homologous systems Ti-Rh and Zr-Rh, but it does not stabilise the cubic high temperature phase. For > 6 at.% Rh-Hf, Hf2Rh is formed with Tc = 1.98°K and there is a transition at 1.73°K, probably due to HfRh.

Electron and Ion Emission from Iridium and Lithium Vapour

r. g. wilson and e. d. wolf, J. Appl. Phys., 1966, 37, (12), 4458–4462

Electron emission S curves for the Li-Ir system in Li vapour at 275−450°C indicate only an uniform heavily Li-covered work function of 2.8 eV which is constant in the Li arrival flux range of 1013 to 1018 at./cm2sec. The adsorption/desorption energy, 2.1 eV, of Li on Ir at low coverage is found to be similar to that of Cs.

Lattice Parameters of Some h.c.p. Binary Alloys of Rhenium and Osmium: Re-W, Re-Ir, Re-Pt, Os-Ir, Os-Pt

p. s. rudman, J. Less-Common Metals, 1967, 12, (1), 79–81

Lattice parameters a, c, c/a are reported for the binary alloys of Re-W, Re-Ir, Re-Pt, Os-Ir, Os-Pt and the lattice parameter-group number relationship is studied. No unique relationship exists for all these alloys.

Laves Phases of the Scandium Group Elements with Ruthenium, Osmium, Iridium, and Platinum

a. e. dwight, j. w. downey and r. a. conner,

Trans. Met. Soc. A.I.M.E., 1966, 236, (10), 1509–1510

New or revised crystallographic data are tabulated for 31 AB2 laves phases, where A is a rare earth and B is Ru, Rh, Os, Ir or Pt. The Rh, Ir and Pt phases have cubic MgCu2 type structures but the Ru and Os phases have hexagonal MgZn2-type structures.

CHEMICAL COMPOUNDS

Oxygen Complexes of Zero-valent Nickel, Palladium and Platinum

g. wilke, h. schott and p. heimbach, Angew. Chem., 1967, 79, (1), 62

Triphenylphosphine complexes (Ph3P)4Pt(O).O2 and (Ph3P)4Pd(O).O2 are more stable than similar Ni complexes at low temperatures but decompose at 20°C after prolonged stirring to produce the metals in the zero-valent state. Complexing reoccurs by addition of excess Ph3P. Each Pd atom can catalyse the oxidation of 500 molecules of Ph3P.

π -Complexes of PdCl2 with Straight-chain Olefins

g. f. pregaglia, m. donati and f. conti, Chem. & Ind., 1966, (46), 1923–1924

π -complexes of the general formula (CnH2n.PdCl2)2, where CnH2n is any straight chain olefin, are synthesised by direct addition of PdCl2 to the olefin in the liquid state. The product is generally a mixture of the π-complex of isomeric olefins in which the cis -form is predominant. The complexes are stable in air for a few hours. They are yellow-brown, crystalline compounds which decompose on melting.

π -Allylic Complexes of Palladium(II) Chloride with Straight Chain Mono-olefins

m. donati and f. conti, Inorg. Nucl. Chem. Letters, 1966, 2, (11), 343–347

Compounds of the type [(CnH2n−1)2Pd3Cl4] were prepared by reacting π -allyl [PdClCnH2n−1]2 with PdCl2 in 1-octene or 1-decene at 100°C for 12 h, followed by addition of excess pet ether and filtration, to give the brown compound. On cooling the reaction mixture to −78°C a yellow compound was obtained, (CnH2n−1PdCl)2. NMR and IR studies show that the coordinated molecule PdCl2 can easily be displaced indicating weak bonding, and a cluster structure with weak metal-metal bonds is proposed.

Synthesis of Metal-Metal Bonds via Iridium and Rhodium Anions

j. p. collman, f. d. vastine and w. r. roper,

J. Am. Chem. Soc., 1966, 88, (21), 5035–5037

Reduction of Ir(CO)2L2 with Na amalgam in tetrahydrofuran under pco = 60 psi yielded the intermediate Na+[Ir(CO)3L], where L = Ph3P. The intermediate reacted with (CH3)3SnCl, (C6H5)3SnCl, (CH3)2SnCl2, L-AuCl, and Hg(CN)2 to form crystalline, air-stable compounds, which apparently contain metal-metal bonds. Reduction of RhL2(CO)Cl with Na amalgam yielded Na+[RhL2(CO)2], which combined with (CH3)3SnCl to form (CH3)3Sn-RhL2(CO)2.

The Mechanism of the Formation of an Iridium Complex of Molecular Nitrogen via Organic Azides

j. p. collman, m. kubota, j.-y. sun and f. vastine, Ibid., 1967, 89, (1), 169–170

Spectral studies enabled the mechanism of formation of an Ir complex with N2 to be elucidated as one stage in the search for a catalyst to hydrogenate N2 under mild conditions and thereby fix atmospheric N2.

Reactivity of Dodecacarbonyltriruthenium

j. p. candlin, k. k. joshi and d. t. thompson, Chem. & Ind., 1966, (47), 1960–1961

The reactions of Ru3(CO)12 with PPh3, P2(CH3)4 and moist NO to give, respectively, (Ph3P)3Ru3(CO)9, [(CH3)2P]2Ru2(CO)6 and polymer Ru(CO)2(NO)2 were studied in order to elucidate the solid state structure of Ru3(CO)12 with respect to Fe3(CO)12 which X-ray analysis suggests is slightly different. Reactions with P2(CH3)4 and moist NO yielded compounds analogous to those of Fe, whereas with PPh3 the resultant product showed no cleavage of metal-metal bonds as found in the analogous Fe compound. Physical data for the Ru products are tabulated.

Reactions of Ruthenium Compounds with Sulphuric Acid

s. i. ginzburg, m. i. yuz’ko and t. v. fomina, Zh. Neorg.Khim., 1966, 11, (11), 2551–2553

Studies on Ru(III) and Ru(IV) compounds with H2SO4 at 100−300°C showed that, whatever the original compounds, the reaction products have the same absorption spectra. The anionic form occurs in solution even at 150°C. Together with coordinated sulphato groups are seen oxidation-reduction processes; Ru(III) is oxidised and Ru(IV) is reduced to the formal state of oxidation 3.5. Green complex Ru sulphate is formed during reduction of Ru(IV) in H2SO4 at 150−200°C and it has an absorption band at 630–640 nm. It contains the peroxy groups –O–O– and –O2–. Green compounds are formed also in aqueous H2SO4 by the reaction of RUiii, iv sulphates with H2O2.

On Green Ruthenium Sulphate

Ibid., 2554–2559

Green Ru sulphate complexes containing K and Cs were synthesised similarly to those of Ir and Rh. Studies of Ru sulphate indicated the existence of a polynuclear complex anion in which Ru: SO4≈2:3 or 3:5, and with sulphate groups with bidentate coordination to the central atoms. The Ru exists in oxidation states Ruiii and Ruiv; formal oxidation state 3.5. O2 or O22− groups are probably present.

ELECTROCHEMISTRY

Interaction of Carbon Dioxide with Hydrogen Chemisorbed on a Platinum Electrode

b. j. piersma, t. b. warner and s. schuldiner,

U.S. Rept. AD 633,686, N.R.L.6388, 1966, (April), 12 pp

The interaction of CO2 with chemisorbed H2 on a Pt electrode was studied using transient galvanostatic and potentiostatic techniques. The presence of CO2 or HCO3 in solution was found to inhibit the H2–evolution reaction as in the dissociation of HCOOH to Hads and CO2 in which the CO2 interacts on the Pt to retard further oxidation. Results indicate that the reduction of CO2 by Hads is unlikely and that the rate of oxidation of H2 is affected by the rate of diffusion of irreversibly chemisorbed H atoms on the Pt electrode.

Measurement of the Potential of Powder Catalysts in Dielectric Media. II. Reduction of Unsaturated Compounds.

g. v. taneeva, a. b. fasman and d. v. sokol’skii, Elektrokhimiya, 1966, 2, (12), 1457–1463

Comparison of the results of potentiometric and kinetic measurements of changes of potentials of Pt, Pd and Ni catalysts during hydrogenations of phenylacetylene and crotonaldehyde in polar and non-polar solvents indicated saturation of —C≡C—, = C = C = and = C = O bonds as the catalyst, solvent and temperature were varied. The value of Δφ varied across the phase boundaries of the system.

Radiochemical Study of the Anodic Corrosion of Ruthenium

j. llopis, j. m. gamboa and j. m. alfayate,

Electrochim. Acta, 1967, 12, (1), 57–65

The corrosion and passivation of irradiated Ru in 2 N and 4 N HCl at 50°C, studied electrolytically at up to 1150 mV, show that Ru is passivated at potentials >950 mV. Pt is passivated more completely than Ru, and Ru and Os form well defined oxides.

ELECTRODEPOSITION AND SURFACE COATINGS

Production of Foils of the Platinum Group Metals and of Gold and the Measurement of their Thickness

v. n. karev, a. p. klyucharev, l. g. lishenko and v. n. medyanik, Zh. Prikladnoi Khim., 1966, 39, (11), 2525–2529

Electrolytes were prepared from which Pd, Pt, Rh and Au were deposited on Cu, which was subsequently dissolved. Deposition conditions are tabulated. Deposit thicknesses were measured with a modified spectrometer.

LABORATORY APPARATUS AND TECHNIQUE

Single-crystal Growth of Sapphire

b. cockayne, m. chesswas and d. b. gasson,

J. Materials Sci., 1967, 2, (1), 7–11

Single sapphire crystals are prepared from Al2O3 using either the vertical pulling technique or the floating zone recrystallisation technique in which the apparatus has been modified by the inclusion of an Ir-lined Al2O3 jacket to the afterheater, and an additional heating shield of MgO lined with Ir, respectively. Formation of Ir platelets in the crystal due to the decomposition of volatile IrO2 in the afterheater is eliminated below 1020° by suitable adjustment of the Ar-O2 or N2-O2 gas flow; contamination is more severe with the floating zone method. Reduction of pulling rate to ≤12 mm/h reduced the formation of voids; use of the afterheater reduced the number of dislocations and low angle boundaries.

Catalytic Hydrogenation. II. A New, Convenient Technique for Laboratory Hydrogenations. A Simple Automatic Device for Atmospheric Pressure Hydrogenations

c. a. brown and h. c. brown, J. Org. Chem., 1966, 31, (12), 3989–3995

A wide range of laboratory hydrogenations may be carried out with highly active Pt/C hydrogenation catalyst prepared in situ by reduction of Pt metal salts with H2 from a generator, which incorporates NaBH4 as the source of H2. Advantages of this apparatus include simple assembly, pure H2 from the NaBH4 source, operation at atm. pressure, accurate measurement of H2 uptake, ready hydrogenation of labile materials at low pressure, and no serious limitation on capacity.

BRAZING

The Selection of Brazing Alloys

m. l. sloboda, Welding Met. Fabric., 1966, 34, (10), 386–393

A review of the suitability of thirty industrial brazing alloys for various applications. Pallabraze 810 and 880 are used principally in vacuum tubes, Pallabraze 1237 is used principally for high strength and oxidation resistance at elevated temperature, and Pt is used for brazing Mo and W for ultra-high temperature service.

HETEROGENEOUS CATALYSIS

On the Catalytic Oxidation of Ammonia in the Industrial Production of Nitric Acid

h. holzmann, Chem.-Ing.-Tech., 1967, 39, (2), 89–95

A review of the current state of catalytic oxidation of NH3 for production of HNO3 and the effects on it of oxidation temperature, gas pressure, rate of flow and of the various possible types of catalyst gauzes. (33 references).

Chemisorption of Carbon Monoxide on Finely Divided Platinum Held in Aqueous Suspension

j. w. hightower and p. h. emmett, J. Colloid Interface Sci., 1966, 22, (2), 158–160

Approximately a monolayer of CO is chemisorbed on a stirred suspension of Pt in H2O, giving a method of determining the surface area of colloidal Pt metals. A Pt suspension was obtained by reduction of PtO2 with H2 in situ and the volume of CO adsorbed was determined by equilibrating the solution with CO at 200 mm for 5h. The CO adsorbed by H2O, which is linearly dependent on the pressure, was determined in a blank run. The volume of the monolayer was found by adsorption of N2 on the dried Pt. The ratio CO:N2 adsorbed was ≥0.96.

Adsorption and Interaction of Hydrogen and Oxygen on Platinum

v. ponec, J. Catalysis, 1966, 6, (3), 362–370

Conditions under which gases react on Pt were established by studies of the chemisorption and mutual interaction of H2 and O2 on Pt films, and of simultaneous resistance changes. A model for the H2 chemisorption bond for transition metals is suggested.

Activation of Platinum-on-Alumina Catalyst in the Isomerisation and Hydrogenolysis of Hydrocarbons by Means of High Temperature Treatment by Hydrogen

i. i. levitskii, m. g. gonikberg, kh. m. minachev and v. i. bogomolov, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1966, (10), 1695–1701

Treatment of 0.3% Pt/Al2O3 by H2 at 500−550°C sharply increased its activity for isomerisation of cyclohexane and of n −C6H14 and also for hydrogenolysis of methylcyclopentane. Treatment by N2, containing 0.5% O2, at 420°C deactivated the catalyst for isomerisation and hydrogenolysis of hydrocarbons but activated it for hydrogenation of C6H6. Treatment by H2 to remove O2 and H2O from the catalyst at 350−420°C caused methylcyclopentane to be converted to isohexane but after treatment of the catalyst by H2 at 550°C the main product of hydrogenolysis of methylcyclopentane was n -hexane.

The Hydrogenation of Acetylene. IV. The Reaction of Acetylene with Deuterium Catalysed by Alumina-supported Rhodium, Palladium, Iridium, and Platinum

g. c. bond and p. b. wells, J. Catalysis, 1966, 6, (3), 397–410

During studies of the C2H2–D2 reaction over Rh/Al2O3, Pd/Al2O3, Ir/Al2O3 and Pt/Al2O3 no C2H2 exchange was observed; H exchange was fairly rapid over Rh and Ir, slow over Pt, negligible over Pd; ethylene-d 2 was the most abundant form of ethylene. Major component of ethylene-d 2 was the cis isomer in high yields over Pd, Pt; higher yields of ethylene-d 3 and -d 4 were observed over Rh.

Conversions of Spiro-(4,4)-nonane on Platinum- and Palladium-Alumina Catalysts in Catalytic Reforming Conditions

n. i. shuikin and i. i. voznesenskaya, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1966, (11), 2052–2053 o -Methylethylbenzene formed 41% of the catalysate from conversion of spiro-(4,4)-nonane over 0.5% Pt/Al2O3 at 450°C, atm, rate 0.3 h−1, H : hydrocarbon = 5:1. Indane formed 68% of the catalysate by isomerisation of spiro-(4,4)-nonane over 0.5% Pd/Al2O3 in similar conditions.

Catalytic Conversions of Spiro-(4,5)-decane on Platinum-, Palladium- and Cobalt-Alumina Catalysts in Catalytic Reforming Conditions

Ibid., 2054–2055

The main reaction during conversion of spiro-(4,5)-decane over 0.5% Pt/Al2O3, 0.5% Pd/Al2O3 and 10% Co/Al2O3 at 450°C, atm is isomerisation to naphthalene, which occurs most easily on the Pt catalyst. Spirodecane breaks at the C5 ring to form smaller amounts of gem -substituted cyclohexanes and alkylbenzenes.

Study of Supported Catalysts by the Method of Exoelectronic Emission. IV. Platinum on Aluminium Oxide and Zirconium Oxide

yu. p. simonite, v. m. mozzhukhina, a. s. shashkov and i. v. krylova, Zh. Fiz. Khim., 1966, 40, (11), 2860–2864

Variations of catalytic activity and exoelectronic emission from Pt/Al2O3 and from Pt/ZrO2 as the Pt content changes are similar. Small amounts of Pt sharply reduce exoemission from Al2O3 and ZrO2 but at medium Pt concentrations (α ≈ 0.01–0.04) there are formed active centres both for emission and for catalysis.

V. Platinum on Aluminium Oxide; Measurement by Secondary Electronic Multiplication

a. p. filonenko and i. v. krylova, Ibid., (12), 3060–3064

Exoelectronic emission from Pt/Al2O3 in vacuo was measured by secondary electronic multiplication and was accompanied by strong desorption. Emission from Al2O3 and from Pt/Al2O3 depends on the nature of the film adsorbed on the surface.

VII. Platinum on Magnesium Oxide. Investigation by Secondary Electronic Multiplication

i. v. krylova and o. g. kupenko, Ibid., (11), 2918–2920

Exoelectronic emission from Pt/MgO was measured using a Geiger counter and using secondary electronic multiplication in vacuo. Samples with high Pt contents show greatly reduced emission after a period in an high vacuum.

Conversions of Dihydropyran and Propyldioxene on Various Catalysts

n. i. shuikin, r. a. karakhanov and s. n. khar’kov, Izv. Akad. Nauk S.S.S.R., Ser.Khim., 1966, (11), 2044–2045

2,3-Dihydropyran decomposes at 300−400°C over Pt/C, active C and quartz to form acrolein with up to 30% yield. In analogous conditions 2-propyl-1,4-dioxene undergoes cracking to form gaseous products.

Dehydrocyclisation of Methyl Propyl Ketone on Metal

d. cornet and f. g. gault, Bull. Soc. Chim. Fr., 1966, (10), 3264–3268

The dehydrocyclisation of methyl propyl ketone to 2-methylfuran was studied gas-chromato-graphically on supported Pt, and on Pt and Pd metal films. Results indicate maximum conversion between 300° and 360°C. Thermodynamics and mechanism of the reaction are discussed.

Metal-catalysed Hydrogenation and Exchange of Cyclohexene

g. v. smith and j. r. swoap, J. Org. Chem., 1966, 31, (12), 3904–3906

To explain how cyclohexene desorbs with D in either its allylic or olefinic position during deuterogenation over 5% Pd/C, 5% Pt/C, and reduced PtO2, a new surface involving an intramolecular H shift is suggested.

Hydrogenation of Allyl Alcohols on Platinum and Palladium Catalysts Supported on Poly-acrylonitrile

d. v. sokol’skii, o. a. tyurenkova, v. a. dashevskii and e. i. seliverstova, Kinetika i Kataliz, 1966, 7, (6), 1032–1038

Potentiometric studies of the catalytic activities of Pt and Pd on polyacrylonitrile for hydrogenation of allyl alcohols at room temperature and atm. pressure in relation to the medium and the nature of the solvent showed reproducible and stable catalytic properties. The Pd catalyst has more activity than the Pt catalyst. The apparent activation energies were calculated. The reaction is zero order with respect to the hydrogenated substances.

The Microcatalytic Hydrogenation of Benzene over Groups VIII and Ib Metals and Alloys

d. a. cadenhead and n. g. masse, J. Phys. Chem., 1966, 70, (11), 3558–3566

Microcatalytic studies of the hydrogenation of C6H6 over Cu-Ni, Cu-Pd and Au-Pd alloys determined specific activites at 84−144°C for the Pd alloys and apparent activation energies. The behaviour of Cu-Pd and Au-Pd indicated the formation of transition metal – Group Ib metal – H2 ternary systems.

Poison-resistant Zeolite Catalysts

j. g. firth and h. b. holland, Nature, 1966, 212, (5066), 1036–1037

The reaction between O2 and C2H6 on Pd adsorbed on zeolite, and on Pd incorporated into the zeolite structure, was studied to determine the resistance to poisoning of the latter. The zeolites were poisoned by preferential adsorption of either hexamethyldisiloxane or CCl4. The zeolites incorporating Pd in their structure were not poisoned except where the pore size was large enough to admit CCl4 molecules. The experiment also indicated that C2H6 and CCl4 could react on single atoms of Pd.

Hydrogenation of Benzene in the Presence of a Palladium Catalyst

a. v. lozovoi, t. i. markina, d. p. pchelina and s. a. senyavin, Neftekhimiya, 1966, 6, 683–689

Studies of hydrogenation of C6H6 at 150−350°C, 50–100 atm over 0.5 and 4.5 wt.% Pd/γ-Al2O3 treated with H2S and HF showed 93−100% conversion at 250−270°C and indicated that 99.7−99.9% pure C6H12 can be produced under optimum conditions. Isomerisation of C6H12 to methylcyclopentane was very small at 200−250°C, was 0.13−0.27% at 250−270°C, and was appreciable at 300°C. Treatment of Al2O3 by 0.5% HF left the catalyst activity for C6H6 hydrogenation unaltered but enhanced the isomerisation process. C6H6 hydrogenation at 235−265°C was zero order in H2; first order in C6H6. C6H12 tended to retard the hydrogenation. Apparent activation energy for C6H6 hydrogenation was 8190 cal/mole; temperature coefficient of the reaction rate was 1.157. Raising the pressure from 50 to 100 atm increased the hydrogenation rate by 4% but increasing H2:C6H6 from 7.6:1 to 18:1 had little effect.

USDA-ADM Produce Mazda from Soybean Oil

Chem. Engng. News, 1966, 44, (53), 38–39

A process developed by the U.S. Department of Agriculture has been modified by Archer Daniels Midland and a continuous pilot plant is now making a versatile intermediate, known as mazda – methyl azelaaldehydate dimethyl acetal – from soybean oil by ozonolysis of methyl soyate and catalytic hydrogenation of the ozonolysis products over Pd/C. Tests on solvent-to-ester ratio, catalyst type, pressure and temperature of the hydrogenation indicated an H2O:methyl soyate optimum of 1.3:1 over Pd/C at 300 p.s.i.g., 75°C. The pilot plant gives almost 90% yield and a $3.0–$3.5 million, 10 million lb/yr plant is under design.

Free and Active Surface of Pd/C catalysts

h. kral, Chem. – Z., 1967, 91, (2), 41–47

Kinetics of the hydrogenation of C6H5NO2, acetophenone and sorbic acid at 20°C on 5% Pd/C of 560–1060 m2/g surface were studied by poisoning the catalyst to determine its selectivity and active sites to find a characteristic quantity more specific than hydrogenation activity alone.

Hydrogenation and Hydrogenolysis. IX. The Hydrogenation of Benzyl Alcohol with Platinum Metal Catalysts

s. nishimura and m. hama, Bull. Chem. Soc. Japan, 1966, 39, (11), 2467–2470

The rate of hydrogenation of benzyl alcohol at 25°C, atm, shows a more marked decrease for Rh catalysts than for Pt due to the formation of cyclohexanecarboxaldehyde, by isomerisation of the intermediate 1-cyclohexanecarbinol, which inhibits the hydrogenation more on Rh than on Pt.

Low-pressure Hydrogenation of Some Benzenepolycarboxylic Acids with Rhodium Catalyst

m. freifelder, d. a. dunnigan and e. j. baker, J. Org. Chem., 1966, 31, (10), 3438–3439

Hydrogenation of an aqueous solution of pyromellitic acid using 5% Rh/C catalyst at up to 60°C and <3 atm gave a high yield of cyclohexane-1,2,4,5-tetracarboxylic acid. At 60−70°C, phthalic, isophthalic and tetraphthalic acids similarly gave high yields of dicarboxylic acids. The resulting 1,2- and 1,4-dicarboxylic acids had cis configuration whereas the 1,3-dicarboxylic acid was a 60:40 cis-trans mixture. Results indicate that H2O solubility of the product is more important than that of the starting material.

On the Conversion of Acetophenone during Hydrogenation on Ruthenium Catalyst

n. s. barinov, d. v. mushenko and e. g. lebedeva, Zh. Prikladnoi Khim., 1966, 39, (11), 2599–2601

Methylcyclohexylcarbinol may be produced from acetophenone on Ru/C. Conversion of acetophenone to the naphthenyl alcohol occurs in two ways; via methylcyclohexylketone and methyl-phenylcarbinol. Increasing the temperature causes the former to predominate. Content of methylcyclohexylcarbinol in the catalysate decreases during this treatment.

On the Reduction of Chloronitrobenzenes into Chloroaniline. Part 2. The Use of Ruthenium in the Reduction of para-Chloronitrobenzene

n. p. sokolova, a. a. balandin, m. p. maksimova and z. m. skul’skaya, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1966, (11), 1891–1895

5% Ru/BaSO4 catalyses the reduction of p -chloronitrobenzene to p -chloroaniline, yielding 99.5−99.7% at optimum conditions with only 0.3−0.5% separation of HCl. The yield is less with 1, 0.5 or 0.05% Ru/BaSO4. The use of Al2O3 as the support leads to greater dehalogenation.

HOMOGENEOUS CATALYSIS

Coordination Chemistry and Homogeneous Catalysis

j. halpern, Chem. Engng. News, 1966, 44, (45) 68–75

A review of the use of transition metal complexes, including those of the Pt metals, as coordination compounds for the homogeneous catalysis of many reactions: activation of H2, hydrogenation of olefins and their isomerisation, dimerisation, polymerisation, hydroformylation, and oxidation. Other uses and likely future trends are indicated (8 references).

Investigation of the Mechanism of Hydrogenation of Ethylene on an Homogeneous Pt-Sn Chloride Catalyst

a. p. khrushch, l. a. tokina and a. e. shilov, Kinetika i Kataliz, 1966, 7, (5), 901–904

The hydrogenation of C2H4 in the presence of Pt-SnCl2 in CH3OH solution produced C2H5D from the systems C2H4 + D2 + CH3OH and C2H4 + H2 + CH3OD. This suggests a reaction mechanism in which C2H4 molecules are combined with Pt-H followed by hydrolysis of the ethyl-platinum derivative.

Isomerisation of Butenes Initiated by Palladium Chloride

i. i. moiseev and s. v. pestrikov, Dokl. Akad. Nauk S.S.S.R., 1966, 171, (1), 151–154

Studies of the kinetics of isomerisation of butenes in the presence of PdCl2 lead to proposals for the mechanism of reaction which involves the initial formation of π -complexes of PdCl2 with subsequent regeneration of the PdCl2 as the isomers are formed.

Organic Syntheses by Means of Noble-metal Compounds. XXX. The Mechanism of Simultaneous Formation of Isocyanate and π -Allylpalladium Chloride from Sodium Chloropalladate, Allyl Chloride, Primary Amine and Carbon Monoxide

t. tsuji and n. iwamoto, Chem. Commun., 1966, (22), 828–829

Oxidation of a primary amine with PdCl2 by abstraction of 2 H atoms in the presence of allyl chloride to give π -allyl palladium chloride is believed to be the mechanism of the reaction which occurs between n-butylamine, allyl chloride, NaCl and PdCl2 in C6H6 through which CO was passed for 2 h at 60°C. Dibutylurea was isolated on addition of excess butylamine and evaporation of solvent under pressure yielded π -allylpalladium chloride. A similar reaction is observed in CH3OH.

Aspects of Catalytic Hydrogenation with a Soluble Catalyst

a. j. birch and k. a. m. walker, J. Chem. Soc., C, Org., 1966, (21), 1894–1896

RhCl(PPh3)3 catalyses the specific addition of D2 to systems containing more than one double bond, e.g. cyclohexene, oleic and linoleic acids, and ergosterol, without additional labelling; and catalyses selective hydrogenation in the presence of groups sensitive to hydrogenolysis, e.g. ω -nitrostyrene to phenylnitroethane, and cinnamyl chloride in part to phenyl propyl chloride. 10−20 wt.% catalyst to 100 wt.% compound to be hydrogenated is used and results indicate the reagent is nucleophilic or the mechanism is governed by steric factors.

Formation and Properties of Some Chloro-carbonyl Complexes of Ruthenium(II) and Ruthenium(III)

j. halpern, b. r. james and a. l. w. kemp, J. Am. Chem. Soc., 1966, 88, (22), 5142–5147

Kinetics of the reactions of CO with chlororuthenate(II) and (III) complexes in HCl to form Ru(CO)Cl52−, Ru(CO)(H2O)Cl42− and Ru(CO)2Cl42− were studied and the NH4 salts were isolated. Neutral Ru(CO)Cl2(PPh3)3 and Ru(CO)2Cl2(PPh3)2 were obtained by addition of PPh3 to the appropriate anions. Homogeneous reduction of Ru(CO)Cl52− with H2 produced Ru(CO)(H2O)Cl42−, which catalysed the reaction and also catalysed D2-H2O exchange and hydration of C2H2. Ru carbonyl chloride complexes are formed during Ru(III)-catalysed hydration of acetylenes and a reduction of catalytic activity results.

The Decarbonylation of Formic Acid by Ruthenium(II) Chloride

j. halpern and a. l. w. kemp, Ibid., 5147–5150

RuCl42− + HCOOH → Ru(CO)(H2O)Cl42− in aqueous HCl. The rate of this reaction depends on the concentrations of Ru(II), HCOOH, H+, Cl and temperature. Results suggest a stepwise reaction mechanism in which a chlororuthenate (II) complex initially is dissociated.

Homogeneous Catalysis of the Hydrogenation of Olefinic Compounds by Ruthenium(II) Chloride

j. halpern, j. f. harrod and b. r. james, Ibid., 5150–5155

RuCl2 catalyses the homogeneous hydrogenation of maleic and fumaric acids in aqueous solution to succinic acid via the apparent formation of a Ru(II)-olefin complex. The rate law for each reaction is k[H2][Ruii(olefin)], where, at 80°C in 3M HCl, for maleic acid: k = 2.3 ± 0.1 M −1sec−1, ΔH⋆ = 14 kcal/mole, ΔS⋆ = 17 eu; for fumaric acid: k = 3.6 ± 0.6 M −1sec−1, ΔH⋆ – 17 kcal/mole, ΔS⋆ = 8 eu. Hydrogenation of fumaric acid in D2O yields mainly DL-2,3-dideuterio-succinic acid, indicating stereospecific cis addition.

FUEL CELLS

Hydrocarbon Fuel Cells with Fluoride Electrolytes

e. j. cairns, J. Electrochem. Soc., 1966, 113, (11), 1200–1204

The ternary acid electrolyte system CsF-HF-H2O is suitable for high-performance fuel cells with Teflon-bonded Pt electrodes operating near 150°C on paraffins. C2-C4 n -paraffins give maximum performance when electrolyte composition is F/Cs = 2.0, H2O = 10 mole/%. C1 and C4-C16 n -paraffins give somewhat lower performance. Good performance is obtained with C2-C4 n -paraffins and HF-H2O electrolyte at 105°C also. C3H8 is converted completely to CO2 and H2O at 105−166°C in both sets of electrolytes at a wide range of current densities. There is no current or voltage cycling.

Electrochemical Cells with Halogen Fluoride Electrolytes

m. s. toy and w. a. cannon, Electrochem. Technol., 1966, 4, (11–12), 520–523

The anodic and cathodic polarisation curves of the pure electrolytes BF3, BrF3 and ClF3 were determined using electrodes of Pt, which was found to be the only material with sufficient inertness and low polarisability. The polarisation behaviour, measured galvanostatically and potentiometrically, showed, respectively, an anodic and cathodic limiting current of 20 mA/cm2 and a rapidly attained high current density. Investigations of potential/current density show Pb-Pt couple to have the highest cell voltage but show Cd-Pt couple to have a constant current density up to dissolution of the anodes.

Use of Raney Platinum for Anodic Oxidation of Hydrocarbons, Alcohols, and Carboxylic Acids into Carbon Dioxide

h. binder, a. köhling and g. sandstede, Advanced Energy Conversion, 1966, 6, (3), 135–148

Studies of current-voltage curves and of potentiostatic-coulometric determinations of conversions over Raney Pt at 25−100°C of hydrocarbons, alcohols, aldehydes, ketones and carboxylic acids in acid and alkaline electrolytes permit its evaluation as a catalyst for anodic oxidation in fuel cells.

CHEMICAL TECHNOLOGY

On the Measurement of the Hydrogen Permeability of Palladium and Iron Cathodes by the H2-Pressure Formed in the Closed Diffusion Chamber

f. lange, e. kahrig and d. kirstein, Chem. Tech., 1966, 18, (11), 672–674

H2 diffusing through Pd causes a rise in the pressure in a closed diffusion chamber and no back-diffusion is observed up to 170 atm. The permeability P of Pd and Fe for H2 can be calculated from the pressure-time curve by the equation where Vr = residual gas volume, F = area of diffusion surface, p = pressure, po = 1 atm, p = initial pressure in chamber, t = time, and M1 = βVo, where β is the solubility coefficient and Vo is the volume.

GLASS TECHNOLOGY

An Electrochemical Theory for Oxygen Reboil

j. h. cowan, w. m. buehl and j. r. hutchins, J. Am. Ceram. Soc., 1966, 49, (10), 559–562

O2 reboil with the development of O2 blisters may occur during glass melting in air in Pt vessels but can be reduced by elimination of electron conductors from the system, removal of O2 from the atmosphere above the melt, application of an external bucking potential, reversal of concentration gradients, and removal of temperature gradients. A mechanism for the phenomenon is proposed.

ELECTRICAL AND ELECTRONIC ENGINEERING

Influence of Platinum Group Metal Films on Oxide Cathode Emission

yu. a. volodin, a. v. druzhinin and v. a. smirnov, Radiotekh. Elektron., 1966, 11, (12), 2262–2265

Thermionic emission from an heated cathode can be controlled by coating with Pt, Ir, or Os, which suppress emission from the coated areas. 0.3–0.5μ coatings of Ir reduce emission from an oxide cathode by 300 times, 0.3–0.5μ Pt by 10 times, 0.01μ Os by 100 times.

TEMPERATURE MEASUREMENT

Survey of Thermocouples

c. p. smith, Engng. Materials Design, 1966, 9, (12), 1966–1970

A survey of base and Pt metal thermocouples, with the instrumentation required and factors to be considered in selection and installation. A guide to fifty-one British thermocouple manufacturers is included.

Use of Noble Metals and Noble Metal Alloys for Temperature Measurement

s. landor, Mérés Automat., 1966, 14, (3), 85–88

Values of thermal e.m.f. Ex are tabulated against temperature t for Pt:10−100% Rh-Pt thermocouples and for Pt:0−100% Au-Pd thermocouples. Data for combinations of Pt with Pt-Mo, Pt-W, Pt-Re, Pt-Os, Pt-Co, Pt-Cu, Pt-Ir and Pt-Pd-Au are presented graphically. Advantages of various thermocouple alloys are discussed in relation to Ex and to physical properties. Some discrepancies exist between these experimental results and accepted British figures.

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