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Platinum Metals Rev., 1964, 8, (3), 107

ABSTRACTS: July 1964

of current literature on the platinum metals and their alloys

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PROPERTIES


Platinum as a Thermal Conductivity Standard


g. a. slack, J. Appl. Phys., 1964, 35, (2), 339-344

An evaluation of data on the thermal conductivity K of Pt suggests that Pt would make a reproducible K standard in the range 75-2047°K. From 200 to 2047°K, K conforms to within ± 2% of K=(0.648 +1.8, × 10-4T)W/cm deg. but further work, especially at higher temperatures, is required before adoption of the standard.

Absolute and Relative Linear Thermal Expansion Coefficients of Vitreous Silica and Platinum


l. f. oldfield, Glass TechnoL, 1964, 5, (1), 41-50

Work on expansion coefficients was reviewed and standard values are recommended: for Pt:-α (50-400°C) = 9.56 × 10-6/°C, α (20-350°C) = 9.50×10-6/°C; α (20-350°C) = 9.46× 10-6/°C for vitreous SiO2:- α (50-400°C) =0.60 × 10-6/°C, α (50-350°C) = 0.6l × 10-6/°C, α (20-350°C = 0.60 × 10-6/°C; expansion of Pt relative to SiO2:-8.88 ±0.03 ×10-6/°C.

Change of Platinum Resistance by Hydrogen


r. j. galagali, Br. J. Appl. Phys., 1964, 15, (2), 208-209

A glowing Pt filament was cooled by the presence of even a trace of H2 and the resistance decreased more as pHa increased. Ar had no effect and air had only a minor effect, even at higher temperatures. Ageing of Pt and electrical excitation of H2 modified the effect somewhat. It is suggested that energy derived from the wire dissociated H2 to H at the Pt surface, hence cooling the wire.

Oxidation of the Platinum Metals in Air


w. l. phillips, Am. Soc. Met. Trans. Q., 1964, 57, (1), 33-37

Oxidation rates were measured in air over the range 800-l400°C. Each metal obeyed the linear weight loss law. Activation energies were: Os, 10 kcal /mole; Ru, 46.1 kcal /mole; Ir, 9.2 kcal /mole; Pd, 24.2 kcal/mole; Pt, 25.4 kcal/mole; Rh, 29.6 kcal/mole.

A Constitution Diagram for the Tungsten-Palladium System


w. k. goetz and j. h. brophy, J. Less-Common Metals, 1964, 6, (5), 345-353

X-ray and metallographic studies confirmed that no intermediate phase exists in the W-Pd system above 1100°C. The solubility of Pd in α-W at 1815°C is 5%, decreasing to 1.5% at1100°C. The Pd-rich solid solution forms peritectically from liquid and α-W at 1815°C, 78% Pd. W is 0.5% less soluble at 1100°C. The solid solution lattice parameters have a minimum at 90% Pd.

The System Palladium-Tungsten-Rhenium


m. a. tylkina, v. p. polyakova and e. m. savitskii, Zh. Neorg. Khim., 1964, 9, (3), 671-673

Raising the Re content of Pd-rich alloys in the Pd-W-Re system decreased their melting points and electrical resistance but increased their hardness, resistance to deformation and temperature coefficient of resistivity. Microstructural analysis further elucidated the structure of the system.

Heat Capacity of Ni-Pd Alloys


c. a. mackliet and a. i. schindler, J. Phys. Chem. Solids, 1963, 24, (12), 1639-1643

Measurements in the liquid He range for pure Pd and 20, 40, 60 and 80 at.% Ni-Pd alloys gave electronic specific heat coefficients of 9.38, 10.66, 8.54, 7.82 and 7.52 mJ/mole°K2, respectively, and Debye temperatures 272, 295, 305, 330.5 and 388°K. The band structure of the system is discussed.

Alloys of Thorium with Certain Transition Metals. III. The System Thorium-Palladium


j. e. thomson, J. Less-Common Metals, 1964, 6, (2), 94-99

X-ray and metallographic studies at l000-1500°C showed that at l000°C seven Th-Pd compounds are stable. The solid solubility of Th in Pd is not more than 15-17%. Th2Pd and “ThPd” crystallise at 1162±12 and 1412+12°C respectively. Th3Pd4 melts above 1500°C. “Th3Pd4” and Th3Pd5 form peritectically at 1325±12 and 1387 + 12°C respectively. ThPd4 and another compound occur in the 79-85% Pd range. Their phase relationships are not known. A sharp minimum in the solidus-liquidus curve occurs at 12% Th; 1125±12°C.

New Ferromagnetic 5:2 Compounds in the Rare Earth-Palladium Systems


a. e. berkowitz, f. holtzberg and s. methfessel, J. Appl. Phys., 1964, 35, (3/2), 1030-1031

Magnetic data are tabulated for Gd5Pd2, Tb5.16Pd1.90, Dy5.07Pd1.93 and Ho5.04Pd1.96. Gd5Pd2 is ferromagnetic below 335°K. The other compounds are b.c. tetragonal isostructures with para- to metamagnetic transitions at 62, 41, 27°K. They become ferromagnetic at lower temperatures with very high hysteresis. Energyproducts (B×H)max of 20 to 26 × 106 GOe at 4.2°K have been observed.

Arsenides of the Transition Metals. VII. The Palladium-Arsenic System


g. s. saini, l. d. calvert, r. d. heyding and j. b. taylor, Canad.J. Chem., 1964, 42, (3), 620-629

Seven intermediate phases in the Pd-As system were detected by X-ray diffraction and thermal analysis.

Exchange Inversion in Ternary Modifications of Iron Rhodium


p. h. l. walter, J. Appl. Phys., 1963, 35, (3/2), 938-939

The exchange inversion temperature Ts, residual magnetisation and maximum magnetisation of Fe-Rh alloys are affected by the nature and amount of transition metal modifiers added. 2 at.% Co, Ni, Cu, Nb, Mo, Ta or W is enough to eliminate the inversion. Ru, Os, Ir, or Pt additions raise Ts and Pd, V, Mn, or Au decrease Ts. For FeRhIrx, T3 increases as x increases from 0-0.25. For FeRhPdx, Ts decreases as x increases.

Solid Solutions of Rhodium with Copper and Nickel


h. -l. luo and p. duwez, J. Less-Common Metals, 1964, 6, (3), 248-249

The Rh-Cu and Rh-Ni alloy systems form continuous series of solid solutions, as shown by X-ray techniques. The Rh-Cu alloys are meta-stable. 50 and 75 at.% Cu-Rh alloys annealed in vacuo at 600 and 800°C for seven to ten days decomposed into two f.c.c. solid solutions with 9.2 and 81.5 at.% Cu concentrations. No decomposition or ordering of Rh-Ni alloys was observed after similar heat treatment.

The Change of Resistivity of Rh after Cold Work


j. g. m. van kuijk, Physica, 1964, 30, (2), 398-400

0.25 mm Rh wires had 20μ. grain size after annealing at 1050°C, restivity of 4.5, μ.Ωcm at o°C and 0.53 μ Ωcm at — 196°C. Load and resistivity changes at — 196°C and 30% maximum extension, and isochronous annealing curves at — 196°C after pulse annealing at temperatures between — 196°C and 500°C are illustrated.

Recovery of the Resistivity of Pt after Deformation at Low Temperature


l. c. menting, Ibid., 407-409

Comparisons of the recoveries for Pt, Rh and Cu after stretching and rolling in liquid N2 are tabulated.

Resistivity of Ruthenium


r. j. tainsh and g. k. white, Canad. J. Phys., 1964, 42, (1), 208-209

Thermal resistivity data from 90 down to 2°K and electrical resistivity data from 293 down to 2°K for a Ru rod confirmed previous results for the pure h.c.p. metal. Values obtained were ρ0 =0.0184, ρi(90°K) =0.93, ρi(273°K) =6.72 μΩcm; Wi(30°K)=0.038, Wi(80°K)=0.535 cm deg w-1.

Ferromagnetism and Incipient Superconductivity in a CeRu2+ 7.3% GdRu2 Alloy


j. j. drautman, c. j. anderson and r. del grosso, J. Appl. Phys., 1964, 35, (3/2), 974-975

Measurements between 1.3 and 20°K showed that this alloy is weakly ferromagnetic below 4.15°K. Tm for CeRu2 was 5.1°K; for the alloy was 3.2°K. A superconducting transition reduced the positive susceptibility. The resistance was less, but did not reach zero.

Superconductivity of Solid Solutions of Ti and Zr with Co, Rh and Ir


c. j. raub and g. w. hull, Phys. Rev., 1964, 133, (4A), A932-A934

Transition temperature-composition curves for α and β-Ti and Zr solid solutions showed that Tc rises with increasing valence electron concentration n. Small Co, Rh and Ir additions to α -Ti or Zr raise Tc by 2 to 4 times. Tc has a 4°K maximum for 90 at.% Ti in the b.c.c. region of the β-Ti alloys.

Superconductivity of Precious Metals and their Alloys


c. j. raub, Z. Metallkunde, 1964, 55, (4), 195-199

A review of the superconductivity of Au, Ag, the Pt metals, and their alloys. The transition temperatures are very low. No solid solutions of Au or of Ag but of some of the Pt metals are superconducting. Noble metal additions to group V superconductors reduce Tc; to group IV they increase Tc. General features of P diamagnetic with a structure t metal compound superconductors are summarised. (42 references)

CHEMICAL COMPOUNDS


Fluorides of the Noble Metals. Part III. The Fluorides of Platinum


n. bartlett and d. h. lohmann, J. Chem. Soc, 1964, (Feb.), 619-626

Attempts to prepare and isolate PtF2 and PtF3 were unsuccessful. Pure PtF4 was shown to be diamagnetic with a structure similar to UC14. Complex fluorides of Pt(IV) and Pt(V) have been prepared and their properties are discussed. PtF6 is sufficiently strong an oxidising agent to oxidise molecular oxygen and this property is discussed.

Carbonyl Complexes by Reaction with Alcohols


l. vaska, Abs. Papers, 147th Meeting, Am. Chem. Soc, 1964, 4L-8

Carbonyl complexes including [MX3(CO)L2] (M=Ru, Os, Rh, Ir), [MX2(CO)L3] [MHX(CO)L3](M=Ru, Os), [MHX2(CO)L2], [MX(CO)L2] (M=Rh, Ir) have been synthesised without using CO. Certain transition metal halides reacted with some group VA donor ligands (e.g. Ph3P) in alcohols and similar solvents to form complexes with CO groups co-ordinated to the metals. The CO originated from the solvents.

Some Ethylenediamine Derivatives of Tetra-valent Platinum


i. i. chernyaev, n. n. zheligovskaya, le ti-k’en and d. v. kurganovich, Zh. Neorg.Khitn., 1964, 9, (3), 562-568

The following Pt complexes were isolated: EnCl2Br2Pt, EnCl2CIOHPt, EnCl2(NO3)2Pt EnCl2ClNO3Pt, EnCl2BrNO3Pt, EnCl2BrNOaPt, EnCl2IOHPt, EnCl2INO2Pt, EnCl2NO2OHPt. They were studied by X-ray and thermal methods and their solubilities and conductivities were determined and tabulated.

Transition Metal Complexes of Secondary Phosphines. IV. Some Complexes of Ruthenium, Rhodium and Palladium


r. g. hayter, Inorg. Chem., 1964, 3, (2), 301-302

Chloro complexes of Ru, Rh and Pd were prepared and attempts were made to convert them to P-bridged complexes, with success only with [PdCl2{HP(CH3)}2] converted to [PdCl{P(CH3)2}{HP(CH3)2}]2. Two forms, presumed to be cis and trans, of [RhCl{HP(C6H5)2}3] were isolated. [RhCl{HP(C6H5)2}8] could only be formed by the [RhCl(C2H4)2]2-di-pheny-phosphine route.

Mass Spectrometric Study of Gaseous Oxides of Rhodium and Palladium


j. h. norman, h. g. staley and w. e. bell, J. Phys. Chem., 1964, 68, (3), 662-663

Studies on the volatility of Rh and Pd in the 1900-2100°K range at 10-5-10 3 atm. O2 pressures indicated the existence of RhO, RhO2 and PdO. ΔHo2000 values were determined for the Rh oxides.

ELECTROCHEMISTRY


Nature of Potentials Established on Some Electrodes of Metals of the VIII Group


a. damjanovic, m. l. b. rao and j. o’m. bockris, Extended Abs., Theoretical Div., Electrochem. Soc, 1964, 2, (May), 159-161, abs. 205

Potential and poa did not follow a simple Nernst relationship when noble metal electrodes were immersed in solutions at 0-80°C. Electrodes tested were Ru, Rh, Ir, Pt, Pd, Au, 13 wt.% Rh-Pt, 20 wt.% Rh-Pt and 50 wt.% Rh-Pt. Coverage by O2 was related to the number of unpaired d-electrons. A graph of O2 coverage against at.% Rh in Rh-Pt alloys was a straight line.

On the Study of Mixed Potentials in Noble Metal-Oxygen-Acid Systems


j. p. hoare, Extended Abs. Theoretical Div., Electrochem. Soc, 1964, 2, (May), 162-163, abs. 206

Rest potentials of Pt, Au, Rh, Pd and Ir electrodes in O2-saturated H2SO4 solutions were studied as functions of pH, po2j and electrode pretreatment in order to determine the nature of the potential-determining reactions. If the rest potential is independent of po2, there may be a metal-metal oxide system or a mixed potential. Different polarisation curves at low current densities in O2- and N2-stirred solutions indicated a mixed potential. The mechanism for each noble metal was considered.

A Study of Surface Oxides on Platinum Electrodes


j. s. ma yell and s. h. langer, J Electrochem. Soc, 1964, III, in, (4), 438-446

Anodic oxidation and cathodic stripping tests on smooth Pt, Pt black, and Pt black-polytetra-fluoroethylene moulded electrodes showed that the initial oxidation sequence is Pt→Pt(OH)2→Pt(O)2, which was used to determine the Pt electro-active areas, but that at higher potentials smooth Pt forms Pt(O)4 and PtO whereas Pt black forms Pt(O)~2.5. A “tight” PtO structure on smooth Pt at higher potentials may account for their unusual properties whereas none forms on Pt black—perhaps because of irregular Pt atom arrangements and its catalytic behaviour.

Voltammetric Study of the Reduction of Molecular Oxygen on Bright Platinum in Perchloric Acid Solution


m. w. breiter, Electrochim. Acta., 1964, 9, (4), 441-450

Cathodic reduction mechanisms for O2 at bright Pt in 1 N HClO4 include neither formation of adsorbed O atoms as intermediates nor participation of adsorbed H atoms. Periodic current-potential curves at 30 mV/sec and impedance measurements at 1000 c/s showed that O2 or H2 coverage of the electrode at a given potential are the same in the presence or absence of O2 reduction. O2 coverage inhibits O2 reduction and Cl- adsorption has a similar effect.

Anodic Formation and Cathodic Removal of Oxides on Palladium


yu. a. mazitov, k. i. rosental’ and v. i. veselovskii, Zh. Fiz.KMm., 1964, 38, (1), 151-155

Kinetics of the formation and reduction of oxides on Pd in concentrated KOH solution were studied in the —30 to +95°C range. At anodic potentials the surface was covered with an oxide of Pd (II) commencing at 1.05 v and at O2 evolution potentials with two oxides, the second of which may have been a superoxide. The slope of the Tafel equation for cathodic reduction of both oxideswas 55 mV. An additional reduction overvoltage of the second oxide was associated with concentration polarisation in the oxide layer.

An Electrochemical Study of Thin Adsorbed Oxygen Films on Rhodium in Oxygen-saturated Acid Solution


j. p. hoare, J, Electrochem. Soc., 1964, in, III, (2), 232-236

After determination of rest potentials of Rh electrodes in O2-saturated acid solutions as functions of time, pH, partial pressure of O2, and electrode preparation, two electrode systems could be distinguished; Rh/Rh-O with an adsorbed layer of O atoms on the Rh surface (mixed rest potential 930±20 mV); Rh/Rh2O3 with adsorbed oxide layer on the Rh surface (mixed rest potential 880±10 mV). These O2 films were good electronic conductors but poor catalysts for peroxide decompositions. The properties of the two films differed because of different Rh to O bondings.

LABORATORY APPARATUS AND TECHNIQUE


Determination of Oxygen in Gases


Control, 1964, 8, (70), 195-196

A brief description of the B.I. S.R.A. Pt/zirconia/Pt reversible electrochemical cell for O2 determination. The e.m.f. of the cell depends only on the O2 of the unknown gas if the gas at the reference electrode remains constant. The ranges are 550-1200°C and 1-10-20 atm.

A High Temperature Differential Calorimeter


c. v. thomasson and d. a. cunningham, J. Sci. Instrum., 1964, 41, (5), 308-310

The endothermic heats of reaction of raw materials for glass making were measured by heating samples and a fired alumina reference at 10°C/min in 0.2 mm Pt sheet crucibles of identical heat capacity. Zero temperature difference during an endothermic process was maintained by heating the sample by a 24 s.w.g. 10% rhodium-platinum element in the form of two D-shaped coils with 0.2 mm Pt rod leads. The crucibles were cemented together, the sample above the reference, and ten Pt:13% Rh-Pt thermocouples, five in each crucible, measured the temperature.

Thermal Condensation of Polymerisations of Inorganic Monomers in Platinum-Metal Crucibles


m. c. miller, d. w. rhys and r. a. shaw, Ind. Chem., 1964, 40, (4), 183-187

The effect of the Pt-metal sintered crucibles on the preparation of phospham macromolecules from 6- and 8-membered ring aminocyclophos-phazenes was studied. Pt and Pd crucibles were attacked severely after only one or two pyrolyses. Rh and Ir crucibles were slightly discoloured and corroded. Only Ru remained bright and un-attacked. Phosphide formation and attack are discussed. Thermogravimetric analysis indicated phospham decomposition on Rh at only 650°C but stability with Ru until 850-950°C.

Ceramic Double Cell for Crystal Growth by Fused Salt Electrolysis


w. kunnmann and a. ferretti, Rev. Sclent. Instrum., 1964, 35, (4), 465-466

A low cost cell consists of two alumina concentric crucibles supported in a Pt safety cup. The electrodes are a Pt strip anode and a Pt disc cathode. Leads, inner crucible supports and cover are also Pt. Single crystals of Na-Mo bronzes were produced satisfactorily at 550°C.

CATALYSIS


Catalysts Are Made Shape-selective. Zeolitic Materials Contain Uniform Size Pores, Catalyse Only Molecules of Certain Size and Shape


Chem. Eng. News, 1964, 42, (6), 45

Pt/zeolite catalysts are shape-selective for hydrogenation of linear hydrocarbons; e.g. a 9:1 molar ratio of H2:butene had 95% of I-butene converted to alkane but less than 1% isobutene was hydro-genated. This was because molecules with one side group have effective diameters greater than the pores of the zeolites and cannot enter the cavities, but the linear molecules can do so.

Particle to Particle Migration of Hydrogen Atoms on Platinum-Alumina Catalysts from Particle to Neighbouring Particles


s. khoobiar, J. Phys. Chem., 1964, 68, (2), 411-412

H2 alone or with Al2O3, at room temperature, did not reduce yellow WO3 but, with Pt/Al2O3, blue W4O11 was formed immediately. This is evidence for dissociation of H2 on Pt and H atom migration to WO3 mixed with catalyst to cause reduction.

Kinetics of Ethylene Hydrogenation over a Platinum-Silica Catalyst


j.h. sinfelt, J. Phys. Chem., 1964, 68, (4), 856-860

When C2H4 was hydrogenated over 0.05% Pt/SiO2 catalyst at 45-93°C in a flow reactor system, the rate of reaction was proportional to √ph2 but as pc2h4 increased the rate decreased and approached zero order dependence at sufficiently higher pressures. Apparent activation energy was 16 kcal/mole.

Composition and Structure of a Catalyst Used in the Synthesis of HCN from NH3 and CH4 at 1150 to 1200°C


f. endter, Abs. Papers, 147th Meeting, Am. Chem. Soc., 1964, 10K-28

Pt catalyst coatings on the inner walls of externally heated, sintered corundum tubes, in which the synthesis takes place, became coated with C, which had to be burned off. After 400 hours operation and 3-5 reactivations no further C deposits or deactivation occurred. The aged catalyst contained Pt3Al, Pt5Al and A1N. To reduce this initial activation period finely dispersed A12O3 is now incorporated in the catalyst coating. No C deposits occur and maximum HCN yields begin at once.

On a New Method for the Investigation of Heterogeneous Catalytic Reactions. I. Decomposition of Ammonia on Platinum


ya. m. fogel’, b. t. nadykto, v. f. rybalko, r. p. slabospitskii, i. e. korobchanskaya and v. i. shvachko, Kinetika i Kataliz, 1964, 5, (1), 154-162.

The mechanisms of the catalytic decomposition of NH3 on Pt and of catalyst-poisoning and activation were established by a new mass-spectrometric method based on simultaneous observation of the intensities of primary and secondary ions. First, NH is adsorbed on the catalyst after NH, decomposes into NH and H2. Secondly, two adsorbed NH molecules react to form N 2 and H 2 molecules.

Reduction of Platinum Oxide by Organic Compounds. Catalytic Self-activation in Deuterium Exchange Reactions


j. l. garnett and w. a. sollich, J. Phys. Chem., 1964, 68, (2), 436-437

PtO2 was reduced by C6R6, above 90°C and then catalysed isotope exchange between C6H6 and heavy water. At 120°C equilibrium was reached after 24 hr shaking. “Self-activation” of PtO2 presumably occurred by C-H bond rupture in C6H6. Aromatic compounds were more reactive than aliphatic compounds for “self-activation” and isotope exchange. Tritiation without H2 pre-activation of catalyst is now possible.

The Hydrogenation of Dihydrolanosteryl and Dihydroagnosteryl Acetates


j. d. chanley and t. mezzetti, J. Org. Chem., 1964, 29, (1), 228-229

Hydrogenation of these substances in acetic acid with added HClO4 using Adams’ catalyst at atmospheric pressure produced an easily separable mixture of the saturated acetate 3β-acetoxy-5a-lanostane (67% yield) and the saturated ether 3β-ethoxy-5α-lanostane (24% yield). The reactions are slow but were previously believed not to occur. For 340 mg dihydroagnosteryl acetate, 300 mg PtO 2 were used at first and 200 mg extra catalyst after 48 hours.

Catalysis by Oxides and by Oxide-Supported Metals. Kinetic, I.R. and Adsorption Studies


v. kevorkian, p. j. lucchesi, j. h. sinfelt and d. j. yates, Chim. e Ind., 1964, 46, (1), 46-50

Oxide (A12O3, SiO2) and Pt/oxide catalysts were studied. Oxide support surfaces behave like polar solvents due to H2O, OH groups or impurities. Their dielectric constants were determined under different conditions, including temperature variation. The supports are not inert and are heterogeneous. Pt may be very finely dispersed on the supports and may interact with them. Kinetics due to surface migration are considered.

Hydrogenolysis of Ethane over Supported Platinum


j. h. sinfelt, J. Phys. Chem., 1964, 68, (2), 344-346

The apparent activation energies for the hydrogenolysis of C2H6 over 0.6 wt.% Pt/Al2O3 and 0.6 wt.% Pt/SiO2 were 31 and 54 kcal/mole respectively, suggesting that the supports and Pt interacted, but in different ways. The rate of hydrogenolysis increased with C2H6 partial pressure to a power in the 0.7-0.9 range but decreased with increasing H2 partial pressure. The suggested mechanism involved extensive surface dehydrogenation followed by a slow breaking of C-C bonds.

Studies of the Hydrogen Held by Solids. V. Investigation of Platinum Supported on Alumina Catalysts by Exchange with Deuterium Gas


w. k. hall and f. e. lutinski, J. Catalysis, 1963, 2, (6), 518-527

Both the Pt surface area and number of alumina hydroxyl ions were determined in the same investigation by D2 exchange as the temperature was raised. All the metal-associated H2 could be exchanged at —80°C (H/Pt=0.7 to 0.9). Hardly any D2 exchange occurred with the support below 100°C. Pt is believed to be present as submicroscopic crystallites. More than one species of H2 on the support was indicated. Fluoriding increased the temperature interval of D2 exchange.

Catalytic Transformations of Cyclododecane in the Presence of Platinised Charcoal


e. s. balenkova, a. yu. alybina, t. i. adveeva, s. 1. khromov and b. a. kazanskii, Dokl. Akad. Nauk S.S.S.R., 1964, 155, (1), 118-121

Cyclododecane and H2 were led over 5% Pt/Cat 3000°C, producing paraffins, naphthenes and aromatic fractions. 50% was converted. Principal products were benzpentalane, indane, dimethyl-napthalene, benzcyclooctane and n -dodecane.

Production of Benzene by Catalytic Aromat-isation of Gasoline


j. vybihal, Internat. Chem. Eng., 1964, 4, (1), 104-109 (Eng. trans, of Chemicky Prumysl, 1963, (8), 393-397)

Optimum conditions for preparation of C6H6 from gasoline derived from Romaskin crude are reforming over a Pt catalyst at 65-120°C, 15-20 atm. Space velocity and catalyst properties are also important. The composition of the input gasoline—C6H12, methylcyclopentane and aro-matics content generally—affects the output. Specimen fractions of wide and narrow limits are used as examples.

Effect of Ultrasonics on the Genesis and Properties of Heterogeneous Catalysts


li ven’-chzhou, a. n. mal’tsev and n. 1. kobozev, Zh. Fiz. Khim., 1964, 38, (1), 80-88

Ultrasonic irradiation can increase or reduce the catalytic activity of Pt and Pd black depending on the gaseous atmosphere and the ultrasonic frequency. Tests with N2, H2, and air showed that the best conditions for preparing active Pt black are N3 atmosphere and high frequency (3000 Kc/s).

Activity of Pt Black Prepared in an Ultrasonic Field from H2PtCl6 Solutions of Various Concentrations


Ibid, (2), 439-441

Pt black catalysts prepared in an ultrasonic field are best produced from dilute H2PtCl6 solutions and their activity depends upon initial Pt concentration. 0.5, 0.25, 0.1 and 0.05% Pt concentrations were studied.

Promotion of Raney Palladium and Platinum Catalysts by Boron


b. d. polkovnikov, a. a. balandin and a. m. taber, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1964, (2), 267-270

2 and 4 wt.% B additions to Raney Pd and Pt catalysts considerably increased their catalytic activity and stability during hydrogenation tests with cyclopentadiene, cyclohexane, cinnamalde-hyde, and crotonaldehyde at 20°C and atmospheric pressure. Results are fully tabulated and discussed.

The Catalytic Oxidation of Olefins on Metal Films


w. r. patterson and c. kemball, J. Catalysis, 1963, 2, (6), 465-478

Acyclic olefins were oxidised at Pt and Pd films mainly to CO2 and H2O. Side reactions produced acetone from propylene and higher olefins and, over Pd, tert-butyl ethyl ketone from tert- butylethylene. C2H4 oxidation over Pt from 5 to 100°C gave results similar to those with Pd. The reaction kinetics were determined. Tests with Rh, Au and W films showed that metal-O2 bond strength governs catalytic activity. C6H12 and C6H6 oxidation over Pd and the effect of HCl on Pd film catalytic activity were also studied.

Palladium-catalysed Olefin Isomerisation


n. r. davies, Austral. J. Chem., 1964, 17, (2), 212-218

The isomerisation of I-octene to cis- and trans 2-octene, rans -3-octene and trans -4-octene is catalysed by sodium chloropalladate (II) in glacial HAc at 55-65°C. N.m.r. analysis of the products from I-octene-3d2 suggests that the mechanism involves the stepwise migration of H atoms along the C chain.

Physical Chemistry of Concentrated Ozone. XII. The Low Temperature Heterogeneous Catalytic Decomposition of Concentrated Liquid Ozone


g. i. emel’yanova, v. p. lebedev and n. i. kobozev, Zh. Fiz. Khim., 1964, 38, (1), 170-175

Pt and Pd actively catalyse the decomposition of 100% liquid O3 at −195.8 and −183°C. Un-oxidised Ag is slightly active. Fe, Cu, and oxides of Fe, Cu, and Ni are inactive. The third order kinetics are caused by poisoning of the catalyst surface by O2 produced in the reaction. The apparent activation energy in the range studied is 1000 cal/mole. Oxide catalysts effective at room temperature were inactive in both liquid and gas phase ( −81°C) catalysis. Catalyst efficiencies at −195.8°C were found to be: Pt black, 4.48 × 10-3 molecule, sec.-1 atom-1; Pd black, 7.53 × 10-3 molecule, sec.-1 atom-1.

Improved Procedures for Converting Higher α-Olefins to Methyl Ketones with Palladium Chloride


w. h. clement and c. m. selwitz, J. Org. Chem., 1964, 29, (1), 241-243

Hexene-l and higher α-olefins, which do not readily react with aqueous PdCl2 solution, may be converted to methyl ketones with 80% yield by using PdCl2 and CuCl2 in dimethylformamide solvent containing 12-17% H2O by volume. Results for the conversion of I-dodecene to 2-dodecanone showed that more H2O reduced the yield considerably. The method can be adapted to use ρ -benzoquinone instead of CuCl2. The olefin feed rate must be controlled. Other factors affecting the reaction are catalyst concentration and temperature.

Studies of Mixed Adsorption Catalysts for Dehydrogenation. Part I. Pd/SiO2 as Catalyst for the Dehydrogenation of Cyclohexane


a. a. alchodzhan, m. a. mantikyan and a. m. aikazyan, Izv. Akad. Nauk Armyan. S.S.R., Khim. Nauki, 1963, 16, (4), 303-314

Decreased activity of freshly-prepared Pd/SiO2 in cyclohexane dehydrogenation was due not to H2 produced in the process but to H2 adsorbed while reducing the catalyst before use. Catalyst treated in air had higher activity. Studies at 320, 265 and 240°C showed that adsorption of C6H6, C6H12 or dehydrogenation products reduces catalyst activity. Air treatment restored the activity. Deactivated catalyst after 20 days storage also was restored to a stable activity.

Part II. Pd-Ag/SiO2 as Catalyst for the; Dehydrogenation of Cyclohexane


Ibid., 315-325

Catalysts tested contained either 1,0 or 0.2 wt.% Pd and varying amounts of Ag, such that the: Pd:Ag ratio varied between 32:1 and 1:9. Addition of Ag to 1% Pd/SiO2 decreased the: activity but a maximum activity was obtained for Pd: Ag=4:1 with 0.2% Pd/SiO2. The degree of activity also depended on the number of sites on SiO2 filled by Pd or Ag. A comparison was made with the hydrogenation of benzene.

Deactivation of Palladium-Alumina Catalysts


d. g. manly and f. j. rice, J. Phys. Chem., 1964, 68, (2), 420-421

Regeneration at 650°C for 13 hr did not restore deactivated 0.3% Pd/Al2O3 catalyst to its original level of activity. After regeneration in vacuo, CO adsorption was complete but in air was only 80% and in O2 only 36%. These effects are attributed to the growth of Pd crystals accelerated by O 2, even below 400°C.

Double Bond Migration and Racemisation during the Hydrogenation of Olefins


w. d. huntsman, n. l. madison and s. i. schlesinger, J. Catalysis, 1963, 2, (6), 498-505

Pd/C considerably catalysed the double bond migration and racemisation of optically active alkenes. Generally about 52% racemisation occurred. Racemisation by processes other than double bond migration was not detected. Bases present reduced the migration rate.

On the Interaction between Acetylene and Palladium Salts in Aqueous Solution


o. n. temkii, s. m. brailovskii, r. m. flid, m. p. strukova, v. b. belyanin and m. g. baitseva, Kinetika i Kataliz, 1964, 5, (1), 192-193

Pd compounds and aldehydes were formed during the reaction of C2H2 and PdCl.;., according to the acidity and temperature of the aqueous solution. Acrolein and formaldehyde were formed in increasing amounts as the temperature rose to 100ºC by the decomposition of PdC4H5OCl formed at 20-25ºC the hydrate PdC4H7O2Cl formed at 1-2°C. Acetaldehyde was formed by the hydration of C2H2 with Pd(II) as catalyst. Propionaldehyde was formed by the decomposition of π-complexes of Pd.

Catalytic Exchange of Methane and Deuterium on Platinum, Ruthenium and Platinum-Ruthenium Alloys


d. w. mckee and f. j. norton, J. Phys. Chem., 1964, 68, (3), 481-489

Pt-rich alloys were more active catalysts than Ru-rich alloys for CH4-D2 exchange in the 70-200°C range. 10-25% Ru-Pt reached the highest specific activity. The orders of formation of the deuteromethanes indicated different reaction mechanisms; stepwise exchange for Pt, multiple exchange for Ru. When one mechanism dominated, measurement of HD on the metal surface gave the rate of exchange.

The Role of Supports in Catalytic Hydrogenation. Part II. Activation Effects of Various Metallic Oxide Carriers on Palladium with relation to the Magnetic Susceptibility and Adsorption Capacity of the Catalyst, and Studies on the Sintering of Palladium Catalysts


e. b. maxted and s. 1. ali, J. Chem. Soc, 1964 (March), 1127-1132

Adsorption capacity and catalytic activity cannot be correlated for fast reactions, and susceptibility and activity only increase together up to a certain limiting quantity of Pd on the support. Where the oxide has high susceptibility there is no correlation. MgO + CeO2 and MgO-ThO2 give the greatest activities as supports. Pd catalysts with larger pores after sintering have higher activities. Decrease of activity on sintered catalyst is also related to Pd content, sintering temperature and duration of sintering.

Catalytic Activity of Noble Metal Alloys. Methane-Deuterium Exchange and Propane Cracking on Platinum-Palladium and Palladium-Rhodium Alloys


d. w. mckee and f. norton, Abs. Papers, 147th Meeting, Am. Chem. Soc, 1964, 29H-68

The order of catalytic activity for CH4-D2 exchange and C3H8 cracking was Pt>Pd>Rh with alloys showing intermediate activities. Pt and Pd exhibited stepwise exchange and Rh exhibited predominantly multiple exchange at higher temperatures. Alloys showed mainly stepwise exchange with more multiple exchange at higher temperatures. An atomic radius-exchange relation was observed and exchange mechanisms are discussed.

Selective Hydrogenation of Haloalkenes to Haloalkanes Using Rhodium Catalyst


g. e. ham and w. p. coker, J. Org. Chem., 1964 29, (i), 194-198

Rh/Al2O3 successfully catalysed the hydrogenation of haloalkenes to haloalkanes. 40-60% chloroalkane yields were obtained from I-chloropropene, allyl chloride and 1, 3-dichloro-propene, and a 96% yield of 2-chlorohexane from 5-chlorohexene-i. Neither Rh, Pd, nor Pt catalysed hydrogenation of chloroalkanes under similar conditions. Yields depended on the solvent, on poisoning by thiophene and on the catalyst support. The order of yields with catalyst is Rh>Pd>Pt. Isomerisation of cis- or trans -dichloropropene over Rh catalyst did not occur in the absence of H2 but there was some in partially dehydrogenated material.

FUEL CELLS


High-performance Propane Fuel Cells


w. t. grubb, Nature, 1964, 201, (4920), 699-700

A complete C3Hs-O2 fuel cell operating at 150°C with Pt electrodes and 85% (14.6 M) H3PO4 electrolyte had a limiting current density imposed by the kinetics of electro-oxidation in excess of 500 mA/cm2. The form of the e.m.f.-current density curve indicates that current density probably is limited by a diffusion process involving C3H8 or CO 2. Electrode structure is therefore a critical factor.

Physical Chemistry and Construction of Fuel Cells. II. Different Types of Electrode for Fuel Cells in Current Use


g. feuillade, La Technique Moderne, 1964, 56, (1), 16-20

Pt metals are used in many of the types of fuel cells summarised. The research organisations and companies engaged on fuel cell projects are surveyed. (64 refs.)

A Simple Gas Electrode Structure for the Evaluation of Catalysts (Electrocatalysts) in Working Fuel Cells


w. t. grubb and c. j. michalske, J. Electrochem. Soc, 1964, III in, (4), 477-478

Details are given for preparing a Pt black electrode by applying an aqueous slurry to a metal mesh screen, drying it, and treating it with hydrocarbon was to make it hydrophobic. It can be used in H2-O2 fuel cells up to 65°C in immobilised liquids. 1:1 Pt black/Ag powder mixture gave similar results in alkaline electrolyte.

CATHODIC PROTECTION


Lead/Platinum Anodes for Marine Applications

d. b. peplow and l. l. shreir, Corrosion Techno!., 1964, 11, (4), 16-18

Pb/Pt bielectrodes were tested in sea-water at 5oA/ft2 for one year and appeared to offer an inexpensive system of power-impressed marine protection. Six Pb alloys were studied. Small Te or Bi additions to 1% Ag-Pb alloy reduce Pb peroxide formation. Anode structure and electrochemical mechanism are described.

CHEMICAL TECHNOLOGY


Ultrapure Hydrogen in Metal Processing


g. l. matlack, Metal Progress, 1964, 85, (3), 114-117

H2 derived from dissociated NH3 is purified by using the Bishop Ag-Pd alloy diffusion cell. Complete units based on these cells have been designed by the Drever Co. The first commercial installation by Drever is saving Magnetics, Inc. an estimated $50,000 per year.

GLASS TECHNOLOGY


Measurement of Kinematic Viscosity at Elevated Temperatures


w. skatuixa and s. schÖne, Silikat Technik, 1964, 15, (1), 5-10

Ir-Pt alloy is used in the tube furnace and stirrer of a rotating viscometer used to measure the dynamic viscosity of optical glass up to 1500°C. The temperature is measured with a Pt:Rh-Pt thermocouple. The kinematic viscosity in stokes is then obtained by dividing the dynamic viscosity in poise by the density in g/cm3.

ELECTRICAL ENGINEERING


Pressed Tungstate Cathode on Iridium Base


a. i. zhadan and b. m. tsarev, Radiotekh. i Elektronika, 1964, 9, (2), 355-356

Pressed cathodes of baria-calcia-tungstate on Ir bases can be used from 450 to 1350ºC whereas W base cathodes which have lower heat of vaporisation, can only be used from 550 to 1250°C. The Ir-based cathodes emit 7A/cm2 at 1000°C, they are activated quickly and they have good reproducibility. Little sublimation is noticed. Use in V.H.F. apparatus is possible. The effect of surface films on the emission is discussed.

TEMPERATURE MEASUREMENT


Reference Tables for Thermocouples of Iridium-Rhodium Alloys versus Iridium


g. f. blackburn and f. r. caldwell, J. Res. Nat. Bur. Stds., 1964, 680, (1), 41-59

Temperatures from o to 2150°C are tabulated against e.m.f. in mV for Ir:6o% Ir-Rh and Ir: 50% Ir-Rh thermocouples. Temperature-e.m.f. relationships are also given for Ir versus 10,25, 75 and 90% Ir-Rh alloys. 50% Ir-Rh gives the maximum thermal e.m.f. (12.2 mV at 2150°C) and may provide the optimum thermocouple combination.

Some Recent Developments in Noble Metal Thermocouples


l. o. olsen, Soc Automotive Eng. Paper 750 A, 1963, (Sept.), 10 pp.

Empirical reference tables of temperatures versus thermal e.m.f. are presented for Pd:15% Ir-Pt, Platinel II, Ir.40% Ir-Rh, If.50% Ir-Rh and Ir:6o% Ir-Rh. Experimental apparatus and test procedures are described briefly. Work on the thermoelectric stability of Platinel II is discussed.

A Dew Point Meter Based on Thermoelectric Cooling


o. g. griffin and c. m. stringfield, J. Sdent. Instrum., 1964, 41, (4)5 241

The dew point of a gas flowing in a tube is measured by observing the temperature at which condensation forms on a mirror surface that is heated and cooled electrically. The Pallador thermocouple is soldered into a cavity in the centre of the mirror. Dew points 20°C<gas temperature and from 50 to — 5°C have been measured in gas flows of 40 1/min.

Thermal and Hydrostatic Behaviour of Miniature Platinum Resistance Elements


c. m. knobler, w. i. honeywell and c j. pings, Rev. Sci. Instrum., 1963, 34, (12), 1437-1438

Glass-clad Pt wire resistance elements by Degussa were calibrated against an N.B.S. Pt resistance thermometer from 77 to 300°K. No systematic resistance deviations were observed. Pressures up to 2,000 p.s.i. at room temperature caused no damage to the elements. Slight decrease in resistance up to 1,500 p.s.i. was equivalent to 30 −150 ×10-6 °K/p.s.i.

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