ABSTRACTS: October 1961
ABSTRACTS: October 1961
of current literature on the platinum metals and their alloys
The Zirconium-Platinum Alloy System
e.g. kendall, c. hays and r. e. swift, Trans. Met. Soc. A.I.M.E., 1961, 221, (3), 445-452
Phase relationships in the region 0-50 at.% (68.2 wt.%) Pt were investigated by metallographic, incipient melting, and X-ray diffraction techniques. Phase fields in the Pt-rich region were outlined. The maximum solubility of Pt in βZr is 13.5 ± 1 wt.% and the minimum solubility in αZr is < 1.0 wt.%. Zr solubility in pure Pt is < 1.0 wt.%. A eutectic exists between βZr and Zr2Pt at 36 ± 1 wt.% and 1185°C, and a eutectoid reaction between βZr and αZr+Zr2Pt occurs at 8.5 ± 1 wt.% Pt and 826°C. Zr2Pt is formed peritectically at about 51.7 wt.% Pt and 1725°C. ZrPt and ZrPt3 occur at 68.2 and 86.5 wt.% Pt, respectively, with melting points at 2100°C and >2120°C, respectively.
Constitution Diagrams of the Palladium-Tungsten System
m. a. tylkina, v. p. polyakova and e. m. savitskii, Zhur. Neorg. Khim., 1961, 6, (6), 1471-1474
The system was investigated by thermal analysis, microscopic and X-ray analysis, and measurement of hardness, microhardness and absolute thermal e.m.f. No chemical compounds were observed in the system. A peritectic reaction occurs at 2175±25°C. a solid solution of W in Pd extends up to 28 wt.% W and its melting point increases steadily from 1552°C to 2100°C for the alloy containing 25 wt.% W. A narrow 3-phase solid solution based on W extends up to 2 wt.% Pd. Between the α- and β-solid solutions there is a two-phase (α + β) region.
Kirkendall Effect and Diffusion in the Gold- Platinum System
I. The Kirkendall Effect
a. bolk, Acta Met., 1961, 9, (7), 632-642
Sandwich-type diffusion couples of pure Au and pure Pt (poly- and single-crystalline), and of pure Au and a 73.5 at.% Au-Pt alloy were prepared by welding platelets of Au on both sides of a platelet of Pt or the Au-rich alloy. Diffusion took place in a furnace and the Kirkendall effect was measured as a function of temperature and time. A displacement of the marker interface in the direction of the highest Au concentration was observed. A difference in the magnitude of the effect in couples with polycrystalline Pt and in those with single-crystalline Pt is interpreted in terms of an extra diffusion transport along the grain boundaries in polycrystalline Pt. Porosity and dimensional and structural changes were also studied.
II. The Concentration Penetration Curves and the Diffusion Coefficients
Concentration penetration curves were determined and the overall diffusion coefficient was calculated according to the graphical method of Matano. Partial diffusion coefficients may be calculated from the observed Kirkendall displacement and data concerning the concentration gradient and the concentration in the marker interface. A method of expressing an observed Kirkendall effect in a numerical value between 1 and 0 is given.
An Investigation of the Ageing of Platinum- Rich Alloys of Platinum with Silver
a. a. rudnitskii and n. a. birun, Zhur. Neorg. Khim., 1961, 6, (6), 1342-1346
Vickers hardness measurements were made on alloys containing 5, 10, 15, 20, 25 and 30 wt.% Ag which had been aged for various periods in the range 10 min-3½ h at 400°, 500°, 600° and 700°C. The alloys were also aged at 500°C for periods in the range 11-75 h and then hardness-tested. Alloys containing 15-30 wt.% Ag show the greatest ageing effect which is obtained by soaking at 500°C for 10-20 h.
Ternary Carbon Alloys of Palladium and Platinum with Magnesium, Aluminium, Zinc, Gallium, Germanium, Cadmium, Indium, Tin, Mercury, Thallium and Lead
h. h. stadelmaier and w. k. hardy,Z. Metall- kunde, 1961, 52, (6), 391-396
The crystal structure of 22 ternary alloy systems was examined. True ternary phases of the A1 and related structures were found in the Pd-In-C, Pd-Sn-C, Pd-Pb-C, Pt-Mg-C, Pt-Al-C, Pt-Ga-C, Pt-In-C, Pt-Sn-C and Pt-Pb-C systems. The structures of PdMg, Pd2Zn, Pd3Tl, Pt3Mg, PtMg, Pt3Al, Pt3In and Pt3Hg were also determined.
Metal-Optical Investigations on Silver- Palladium and Nickel-Chromium Alloys
h.-e. schmidt and r. e. hummel, Z. Metallkunde, 1961, 52, (5), 337-343
Optical constants of mechanically polished samples were determined using incident visible light of different wave-lengths. Reflected intensity and phase of the originally plane polarised light were observed and the refractive coefficient and absorption coefficient were calculated as a function of intensity ratio and principal angle of incidence. Data obtained are used to study the application of the free conduction electron model to the alloys studied.
Ferromagnetism in Dilute Solutions of Cobalt in Palladium
r. m. bozorth, p. a. wolff, d. d. davis, v. b. compxon and j. h. wernik, Phys. Rev., 1961, 122, (4), 1157-1160
Magnetic moments were measured in fields up to 12k oersteds at temperatures down to 1.3°K. Ferromagnetism exists in the 0.1 at.% Co-Pd alloy even though the Co atoms are about 10 at. diameters apart. The Curie point of this alloy is 7°K. It was found that the moment associated with one Co atom increases from 1.7 Bohr units in pure Co to 9 to 10 units in the maximum dilution. The onset of ferromagnetism at about 10 at.% Co was indicated by measurement of lattice constants.
Magnetic Coupling in Palladium-Dilute Iron Group Alloys
e. o. wollan, Phys. Rev., 1961, 122, (6), 1710-1713
The magnetic properties of Pd and its alloys with Fe group metals is discussed in terms of the splitting of the d orbitals. Data already obtained for the Curie point temperatures of Pd-Fe alloys and ferromagnetic saturation moments of Pd-Fe and Pd-Ni alloys are shown graphically.
Néel Temperatures and Thermoremanent Magnetisation of MnxPd100-x Alloys (34 ≤ x ≤ 42)
r. wendling, Compt. rend., 1961, 252, (21), 3207-3209
The susceptibilities of alloys quenched at 1200°C show a sharp maximum at temperatures TN which increase as x increases. After annealing at 450°C, the thermoremanent magnetisation is very feeble. The susceptibility maxima for alloys cooled slowly after melting are less sharp. Thermoremanent magnetisation induced by annealing at 450°C disappears at TN.
The Hall Effect in Some Pd-Co-H Alloys
j.-p. burger, Compt. rend., 1961, 252, (24), 3763-3765
Pd and Co-Pd alloys containing 2, 4 and 7 at.% Co were studied before and after hydrogenation. The ferromagnetic Curie points of the 2, 4, and 7% Co-Pd alloys before hydrogenation are < 80°, 175° and 248°K, respectively. The Hall effect of the hydrogenated paramagnetic alloys was measured and a term proportional to paramagnetic magnetisation proposed.
Crystallography of the Ru-B and Os-B Systems
c. p. kempter and r. j. fries,J. Chem. Rhys., 1961, 34, (6), 1994-1995
The systems were studied by X-ray powder diffraction. The existence of the hexagonal Ru7B3 phase was confirmed and the hexagonal phases RuB2, Ru2B5, OsB2 and Os2B5 were found. Crystallographic data are given.
Arsenides of the Transition Metals
IV. A Note on the Platinum Metal Arsenides
r. d. heyding and l. d. calvert, Canad. J. Chem., 1961, 39, (4), 955-957
Binary alloys corresponding to M3As, M2As, MAs, mas2 and MAs3 (M=Ru, Rh, Pd, Os, Ir, or Pt) were prepared and their structures were examined by X-ray powder diffraction techniques. The compounds Pd3As, Rh2As, RuAs, RhAs, ruas2, osas2, PdAs2, PtAs2, RhAs3, and IrAs3 were detected and their structures are discussed.
h. h. claassen, h. selig, j. g. malm, c. l. chernick and b. weinstock, J. Amer. Chem. Soc., 1961, 83, (10), 2390-2391
RuF6, was prepared by heating the metal powder in a F atmosphere at 300 mm pressure. The resultant dark brown solid melts at 54°C and decomposes at 200°C according to the reaction: RuF6->RuF5+½F2.
Experimental Study of Intermetallic Diffusion in Large Temperature Gradients
c. j. meechan, J. Appl. Phys., 1961, 32, (5), 954-950
Diffusion couples of Au/Ni, Cu/Ni, γFe/Ni, γFe/Pd, and Ni/Pd were fabricated by a sintering technique and temperature gradients in the range 2000°C/cm to 3000°C/cm were applied across the specimen interfaces. Diffusion zone widths were measured by microhardness, colouration and etching techniques. It is shown that diffusion is influenced by the temperature gradient. Some of the factors which may be affected by the temperature gradient are noted.
Kinetics of the Oxidation of Platinum
g. c. fryburg and h. m. petrus, J. Electrochem. Soc., 1961, 108, (6), 496-503
Oxidation rates of Pt ribbons electrically heated in normal oxygen were determined over the temperature range 900°-1500°C under pressures from 15μ to 1 atm. It was found that the oxidation rate is a function of the temperature of the Pt and the temperature and pressure of the oxygen. The activation energy, obtained from temperature-dependence data, is 42.5 kcal/mole. Back-reflection of volatile PtO2 by the surrounding gas molecules is thought to cause a decrease in the oxidation rate with increased pressure.
Vaporisation of Iridium and Rhodium
m. b. panish and l. reif, J. Chem. Phys., 1961, 34, (6), 1915-1918
Knudsen effusion and Langmuir evaporation techniques were used in the study. The vapour pressure of Ir over the temperature range 2100°-2600°k is represented by the equation: log pmm=10.46-(33980/T), and that for Rh over the temperature range 2050°-2200°K by the equation: log pmm = 10.28-(28300/T). Heats of vaporisation calculated are: Ir, ΔH298 = 158.4 ± 0.5 kcal/mole, and Rh, ΔH298 = 132.8 ± 0.3 kcal/mole. Boiling points are estimated for Ir and Rh as 4800°K and 3980°K, respectively.
Heat Capacity and Resistivity Anomalies in Palladium Hydride
p. mitacek and j. g. aston, Nature, 1961, 191, (Jul. 15), 271
Slow exothermal processes were observed near 150°K and above 200°K on cooling solutions of hydrogen in polycrystalline Pd. Heat capacity measurements with H/Pd ratios of 0.25 and 0.125 show a maximum at 55°K coinciding with that previously reported for a H/Pd ratio of 0.50. A migration of hydrogen from the α- to β-phase at low temperatures is suggested. Resistivity and heat capacity data are compared.
The Electrical Resistance of Alpha Hydrogen-Palladium
w. t. lindsay and f. w. pement, Bull. Amer. Phys. Soc., Series II, 1961, 6, (4), 353 (Abstract of paper presented at the 1961 Summer Meeting, Mexico City, June 1961)
Resistance measurements were made on gas charged alloys in the range 100° - 400°C. The increase of resistance of Pd resulting from hydrogen addition is proportional to the hydrogen concentration, and the proportionality constant is independent of temperature. Results obtained combined with those obtained previously may be represented in the range 75°-400°C by the equation (R/R°) - 1 =(2.41±0.04)m, where R = resistance of αH-Pd, R°= resistance of H-free Pd, and m=H:Pd atom ratio.
The Kinetics of Oxygen Absorption at Vapour-Coated Fe, Ni or Pt Layers and Alloys
c. weissmantel, k. schwabe and g. hecht, Werkstoffe u. Korrosion, 1961, 12, (6), 353-359
The rate of oxygen sorption on layers of metal about 500Å thick was measured manometrically in the temperature range 25°-450°C. The effect of the simultaneous addition of H2O vapour was studied. The exchange rate between combined oxygen and gas-phase oxygen was examined with the O18 mass spectrometer. Pt and Ni, compared with Fe, have a much slower sorption rate. The atmospheric behaviour of the coatings was observed during several months.
Some Specific Chemical Reactions at the Surfaces of Noble Metals
a. keil, Metall, 1961, 15, (7), 655-657
Reactions which occur at room temperature include the formation of Ag2S and diffusion of Ag2S on Au surfaces. Conditions for the occurrence of this phenomenon are discussed. Adsorption and polymerisation reactions of organic vapours on Pt metal surfaces are described. The atmospheric oxidation of Ag, Au, and the Pt metals at high temperatures is discussed. (14 references)
Rates of Chemisorption of Hydrogen on Hydrogen-Covered Ruthenium Surfaces
m. j. d. low , J. Phys. Chem., 1961, 65, (5), 887-888
Hydrogen was pre-adsorbed on a 0.5% Ru/ALO3 catalyst at 257°C. The rate of hydrogen uptake on the pre-adsorbed gas was then measured at 257°C. Data obtained for the chemisorption kinetics indicate that the chemisorption mechanism requires a surface which changes in character during adsorption.
The Fundamental Behaviour of Passive Alloys
h. h. uhlig, Werkstoffe u. Korrosion, 1961, 12, (7), 413-416
The mechanism of passivation of a base metal by alloying, as in the addition of Cr to Fe, is discussed. Passivation achieved by the addition of alloying constituents of lower overvoltage, exemplified by the addition of 0.1% Pd to Ti and 18/8 stainless steel, is also described. Critical alloy compositions for Cr-Fe and Ni-Cu alloys are discussed.
Possibilities of Protecting Titanium from Corrosion
w. r. fischer, Techn. Mitt. Krupp, 1961, 19, (2), 16-72
The possible corrosion protection of Ti is predicted from a study of potential-pH (Pourbaix) diagrams for the Ti-TiO2-H2O system and of current-voltage curves for Ti in aqueous solutions. Cathodic and anodic methods of protection in aqueous solutions are described. Methods of anodic protection include the addition of oxidising substances to the corrosive medium, the application of impressed currents, and galvanic contact of the Ti with Pt metals by coupling or coating. The corrosion resistance of Ti in HC1 and H2SO4 is greatly improved by alloying with small amounts of Pt or Pd; the addition of 0.2% Pd is sufficient. Alloying with base metals such as Mo, Ta, V, and Zr is also mentioned. The corrosion properties of Ti in non-aqueous solutions and gases are also discussed.
An Investigation of the Mechanism of the Electrochemical Corrosion of Titanium
III. The Corrosion and Electrochemical Behaviour of Titanium and of its Platinum and Palladium Alloys in Sulphuric and Hydrochloric Acid Solutions
n. d. tomashov, g. p. chernova and r. m. al’tovskii, Zhur. Fiz. Khim., 1961, 35, (5), 1068-1077 (English summary)
The polarisation in H2S04 and HC1 solutions of anodes and cathodes of Ti and its alloys with 1% and 2% Pt and Pd was investigated by potentiostatic methods. It was shown that increases in both acid concentration and temperature cause an increase in the passivation current and a shift of the total passivation potential in the positive direction. Alloying of Ti with Pt or Pd lowers the cathodic hydrogen overvoltage with a positive shift of the steady state potential. Consequently the corrosion resistance of the alloys is increased.
Electrochemical Properties of Anodically Prepared Oxide Layers on Platinum
k. nagel and h. dietz, Electrochim. Acta, 1961, 4, (1), 1-11
Conditions for the formation of thick oxide layers on Pt by anodic treatment with pure d.c. or with superposed a.c. were investigated. Cathodic charging curves obtained with the Pt oxide electrodes thus produced show a plateau region. Rest values obtained with intermittent current indicate that the equilibrium potential of the PtO2 electrode should be close to uh=0.80 V, the rest value measured with thin layers. An explanation of the electrochemical behaviour of the Pt oxide electrode is given.
Potential-Activity Diagram for Important Electrode Reactions in the System Platinum/ Platinum Oxide/Solution
k. nagel and h. dietz, Electrochim. Acta, 1961, 4, (2-4), 141-154
The dependence of UH values for electrode reactions in the system on the activity ai of dissolved reactants is shown graphically in a U(a) diagram. The possibilities of determining equilibrium values of the Pt oxide electrode are discussed.
The Anodic Oxidation of Oxalic Acid on Platinum. I. Passivation Effect of a Bright Platinum Electrode
j. giner, Electrochim. Acta, 1961, 4, (1), 42-54
The mechanism of the anodic passivation of a bright Pt electrode in IN H2S04 for the reaction H2C2O4→2CO2 + 2H++2e- was studied. A layer of chemisorbed oxygen is formed on the Pt electrode by oxygen separated from the H2O. This passivating oxygen layer may be removed either by cathodic reduction or by reduction by the H2C2O4. It is suggested that the anodic oxidation of H2C2O4 is effected by intermediate active oxygen.
Mechanisms for the Evolution and Ionisation of Oxygen at Platinum Electrodes
a. c. riddiford, Electrochim. Acta, 1961, 4, (2-4), 170-178
Observations by other workers on the oxygen electrode process support the suggestion that it follows the same path in both acid and alkaline solution. The path is identified.
Effect of Adsorption of Anions on the Discharge of Hydrogen on Palladium and the Ionisation of Hydrogen Dissolved in Palladium
l. t. shanina, Proc. Acad. Sci. U.S.S.R., Phys. Chem. Section, 1960, 133, (1-6), 647-649 (Transl. of Doklady Akad. Nauk S.S.S.R., 1960, 133, (2), 417-419)
Polarisation measurements on a palladised Pt electrode were made in HC1, HBr, KI + 1NH2SO4, and KI + 1N NaOH at 20°C, and anode charging curves were plotted. Charging curves plotted in HCI (0.1N, 0.5N and 2N) differ little from those plotted in 1N H2SO4. The reversibility of the process is disrupted in the presence of Br- and there is an even greater deviation in the presence of I-.
Effect of Surface Oxidation on the Behaviour of Platinum Electrodes. The Fe(III)-Fe(II) Couple in Sulphuric Acid and Perchloric Acid
f. c. anson, Analyt. Chem., 1961, 33, (7), 934-939
Chronopotentiometric studies showed that a film of platinised Pt is formed on the surface of an electrode which has been oxidised and reduced electrolytically. The behaviour of the electrode is influenced by the presence of this film as well as by that of a Pt oxide film. The oxide film is chemically reduced rapidly by Fe(II) in 1M H2SO4, but in 1M HCIO4 solutions of Fe(III) and Fe(II) it persists on the electrode and causes decreases in the reversibility of the reduction and oxidation of Fe(III) and Fe(II).
The Problem of Hydrogen Overpotential on Platinum
ya. m. kolotyrkin and a. n. chemodanov, Proc. Acad. Sci. U.S.S.R., Phys. Chem. Section, 1960, 134, (1-6), 819-822 (Transl. of Doklady Akad. Nauk S.S.S.R., 1960, 134, (1), 128-131)
Determination of the hydrogen concentration in the vicinity of a functioning Pt microcathode by means of oscillographic polarography was used to examine the theory that, for low potentials, the rate of evolution of hydrogen in acid media is controlled by the rate of diffusion of molecular hydrogen from the cathode surface into the liquid.
Intermediate Temperature Fuel Cells
g. v. elmore and h. a. tanner, J. Electrochem. Soc ., 1961, 108, (7), 669-671
The construction and performance of two types of gas cell operating from 1250 to 200°C is described. A Pd foil, 0.0005 in. thick, hydrogen electrode and Teflon-treated Ag powder oxygen electrode are used in an alkaline cell with a NaOH−KOH−Ca(OH)3 electrolyte. In a H3PO4−SiO2 electrolyte, carbon coated with Teflon and Pt or Pd is used for both the hydrogen and oxygen electrodes. Current densities up to about 100 ma/cm2 have been attained.
Electrochemical Corrosion of Platinum in Hydrochloric Acid Solutions
j. llopis and a. sancho, J. Electrochem. Soc., 1961, 108, (8), 720-726
Anodic corrosion of Pt by d.c. (ic ) is increased by increasing temperature, high CI− concentration, high acidity and by superimposing a.c. (ia). Corrosion by a.c. at frequencies below 50 c/s was studied. Using a 10 c/s square wave, intense corrosion is increased by increasing acidity and temperature. Corrosion is nil until ia reaches a critical value above which it increases, and with solutions of low acidity, it goes through a maximum with increasing ia. Oscillographic cathodic and anodic charging curves were studied and interpreted.
Electrochemical Applications of Platinised Titanium
c. e. tirrell, Crucible Titanium Rev., 1961, 9, (2) , 2-6
The electrochemical properties of Ti and Pt- coated Ti anodes are discussed, and methods of applying Pt to Ti are outlined. Applications in which Pt/Ti anodes have been used include fuel cells, impressed current cathodic protection systems, electrodialysis cells, and caustic-chlorine cells. In chlorine production, Pt/Ti anodes may be used in concentrated brine cells with current densities ranging from 100 to 300 A/sq. ft. A fifteen-month plant-scale test with a diaphragm cell has resulted in reduced power consumption, increased diaphragm life and improved chlorine and NaOH quality.
Immersion Plating of the Platinum Group Metals
r. w. johnson, J. Electrochem. Soc., 1961, 108, (7), 632-635
Pd, Rh, and Pt may be deposited on Cu from chloride solutions, while Ru is deposited from solutions based on ammonium nitroso ruthenium chloride or ruthenium sulphamate. Plating solutions containing 5 g metal/1 and 250 ml HCI (32%)/l are recommended with operating temperatures of 25°C for Rh and Pd and 95°C and 65°C for Ru and Pt, respectively. Deposits of Pd, Rh, Pt, and Ru up to thicknesses of 50, 30, 65, and 100 µin., respectively, may be obtained. The coatings are sealed by immersion in a replacement Au solution, in boiling H2O, or in NH4OH. The adhesion, tarnish and corrosion resistance, and solderability of the deposits are discussed.
Barrel Plating by Means of Electroless Palladium
r. n. rhoda, J. Electrochem. Soc., 1961, 108, (7), 707-708
Experimental work was carried out using a bath of composition: Pd (as chloride of tetrammine amine complex) 2.5-20 g/1, Na,EDTA 8 g/1, and NH4OH 280 g/1. The effect on plating rates of variations in temperature (25°-45°C), addition rates of the N2H4 reducer, and Pd concentration were studied. The maximum rate (0.1 mil Pd deposited in 1¼h) is obtained at 45°C with the addition of 0.096 g N2H4/15 min and log Pd/1. Operating techniques for long and short runs, storage of the baths, and pretreatment of substrates are discussed.
Crack-free Rhodium Deposits
f. h. reid, Metalloberfläche, 1961, 15, (2), 33-37
Two modified plating baths have been developed. Rh deposits containing A1 and Mg, which are practically crack-free, are suitable for applications where corrosion resistance is most important and surface quality is of less importance. These coatings must be polished for applications in electrical engineering. Rh deposits containing Se have good surface quality and, though not truly crack-free, have enhanced protective properties.
LABORATORY APPARATUS AND TECHNIQUE
Induction Heated Pressure Vessel for Growing Oxide Single Crystals
a. ferretti, d. g. wickham and a. wold, Rev. Sci. Instr., 1961, 32, (5), 566-568
The pressure vessel consists basically of a water-cooled stainless steel tube. This contains an A12O3 tube which surrounds a radio frequency load coil. The heating chamber, located in the cylindrical space enclosed by the load coil, consists of a 20% Rh-Pt crucible sheathed by fused A12O3 and heated by Rh-Pt-Al2O3 ring elements the whole assembly being contained in a fused Al2O3 crucible. Two Pt:10% Rh-Pt thermocouples are mounted in the heating chamber. The furnace, which operates at 1600°C and 75 atm oxygen pressure, has been used to grow ferrite crystals.
j. weissbart and r. ruka, Rev. Set. Instr., 1961, 32, (5), 593-595
A galvanic cell which measures oxygen partial pressure and oxygen pressures in vacuum systems, both at high temperatures, is described. The gauge consists of a ¾ in. diameter tube of Ca stabilised ZrO2 sealed to a Kovar metal flange through a graded glass seal. The flat bottom of the tube, coated on both sides with a porous Pt film, acts as the electrolyte. The electrodes are connected by Pt wire leads to a potentiometer. A Pt:10% Rh-Pt thermocouple measures the cell temperature.
Plants Tests on the Decomposition of Nitrous Oxide over a Heated Rhodium Catalyst
l. t. lakey, U.S.A.E.C. Report IDO-14545, 11 pp.
Dissolver off gases containing 14.2 to 19.8 vol.% N2O were passed over a 0.5% Rh/Al2O3 catalyst bed in a stainless steel reactor. It was found that, with outlet temperatures maintained between 1300° and 1500°F, the N2O content of the off gases may be reduced to < 0.05 vol.%. Suggestions for the design of a single, double-pass reactor are given.
Reaction of Ethane with a Clean Rhodium Film
r. w. roberts, Nature, 1961, 191, (Jul. 8), 170
C2H6 at low pressure was brought into contact with a Rh film 30Å thick at 27°C and 100°C. At 27°C the C2H6 decomposed to yield gaseous CH, and an adsorbed residue with the composition CH1.5. It was found that the rate of reaction is a function of the surface temperature and of surface cleanliness.
The Selective Hydrogenation of Linolenic Acid
j. g. willard and m. l. martinez, J. Amer. Oil. Chem. Soc., 1961, 38, (6), 282-286
Methyl linoleate was hydrogenated in the presence of Rufert Ni, reduced NiO, Cu chromite, or Pd-Pb catalysts. It was found that variation of catalyst, catalyst concentration, solvent, temperature, and pressure had little influence on the selectivity. Differences in relative reactivity of the 9, 12, and 15 double bonds of the methyl linoleate were found.
The Hydrogenation of Monovinylacetylene
a. rieche, a. grimm and h. albrecht, Brennstoff-Chem., 1961, 42, (6), 177-185
Known methods of partial hydrogenation of monovinylacetylene to butadiene are reviewed. A number of Pd, Pt, and Ni catalysts on various bases were used in the hydrogenation reactions and in some cases complete hydrogenation to butane was found. The optimum yield of butadiene (69%), given with a Pd/BaSO4 catalyst, was accompanied by 21% butene-l, 5.5% trarts- butene-2, 3.5% cis -butene-2 and 1% butane. Further hydrogenation of butadiene-(1, 2) and-(1, 3), butine-(1) and butine-(2) was investigated in the liquid- and gas-phases. Hydrocarbons with 12-16 C atoms are produced in the gas phase.
f. g. ciapetta, Petroleum Eng., 1961, 33, (5), C19-C31
The history of the development of the catalytic reforming process is outlined. Various reactions which occur in the reforming of petroleum naphthas are discussed and the functions of the constituents of Pt/SiO2, Pt/Al2O3/SiO2 and other reforming catalysts in these processes are described. Factors which affect the activity, selectivity and life of Pt catalysts are discussed in detail. These include boiling range of the feed, feed composition, the presence of catalyst poisons, and variations in operating temperature, pressure, space velocity and hydrogen recycle rate. (88 references)
Alumina: Catalyst and Support. VI. Aromatisation of 1,1-Dimethylcyclohexane, Methylcycloheptane, and Related Hydrocarbons over Platinum/Alumina Catalysts
h. pines and t. w. greenlee, J. Org. Chem., 1961, 26, (4), 1052-1057
Catalysts prepared by impregnating aluminas of various intrinsic acidities with a solution of Pt(NH3NO2)2 were used in the investigation. Aromatisation of 1,1-dimethylcyclohexane (I), 4,4-dimethylcyclohexene (II), methylcycloheptane (III), and 5,5-dimethylcyclohexadiene was studied at 350°C. The composition of the aromatised product is affected by the relative acidities of the aluminas and the method of platinising them. Absorption of the Pt complex probably neutralises the acid sites of the Al2O3. Isomerisation, with the production of xylenes, accompanies the aromatisation of I and II and the extent of isomerisation is related to the intrinsic acidity of the Al2O3. Aromatisation of (III) gives C6H5CH3, C6H5C2H5 and xylenes.
Ethylene Oxidation: Low-Cost Route to Acetaldehyde Manufacture
anon., Chem. Eng., 1961, 68, (10), 66-68
The Aldehyd G.m.b.H. process is described. An aqueous solution of CuCl2 containing a small amount of PdCl2 acts as the oxygen-carrier in the conversion of C2H4 to CH3CHO. In a one-stage oxidation, C2H4, oxygen, and recycle gas are boiled together with the catalytic solution under slight pressure, the gaseous effluent is scrubbed with H2O and the resulting aqueous CH3CHO solution is distilled. When air is used instead of oxygen, the spent catalyst is regenerated in a separate reactor before recycling. Operating costs for the one- and two-stage processes are given.
Preparation of Some Condensed Ring Carbazole Derivatives
h. m. grotta, c. j. riggle and a. e. bearse, J. Org. Chem., 1961, 26, (5), 1509-1511
A Pt/MgO catalyst was used in the vapour phase cyclodehydrogenation of N,N´-diphenylphenyl-enediamines. Indolo [3, 2-b ] carbazole and indolo [2, 3-b ] carbazole were prepared from N,N´- diphenyl-p -phenylenediamine and N,N´- diphenyl-m -phenylenediamine, respectively. Benzo-carbazoles were prepared from phenylnaphthyl-amines by a similar method.
Catalytic Fission of the Carbon-Halogen Bond
Part 1. Reactions of Ethyl Chloride and Ethyl Bromide with Hydrogen on Evaporated Metal Films
j. s. campbell and c. kemball, Trans. Faraday Soc., 1961, 57, (5), 809-820
Evaporated films of Pd, Pt, Ni, Fe, W and Rh were used as catalysts in a study of the hydrogenolysis of the ethyl halides. The principal reaction observed was: C2H5X+H2→C2H6+HX, but with Ni and Fe, C2H4 was also formed. Some CH4 was formed over Rh. No exchange of the alkyl halides with deuterium was found up to 450°C. The distributions of isotopic ethanes formed by deuterolysis of the halides was observed. Kinetic results and reaction mechanisms are discussed.
A Study of the Catalytic Hydrogenation of Hydroxybenzenes over Platinum and Rhodium Catalysts
g. a. smith and b. i.. stump, J. Amer. Chem. Soc., 1961, 83, (12), 2739-2743
Adams’ Pt and 5% Rh/Al2O3 were used in the hydrogenation of phenol, catechol, resorcinol, hydroquinone, phloroglucinol and pyrogallol. Reduction rates were found to be of the same order as those for corresponding methyl- and methoxybenzenes. It is suggested that, in the reduction of the phenols, cyclohexenols are formed as intermediates and that these are reduced to form cyclohexanols, isomerised to form cyclohexanones or cleaved to form cyclohexanes. Kinetic data are given.
Catalytic Activation of Molecular Hydrogen by Ruthenium (III) Chloride Complexes
j. f. harrod, s. ciccone and j. halpern, Canad. J. Chem., 1961, 39, (6), 1372-1376
Ru (III) in aqueous HC1 solution was found to catalyse the homogeneous reduction by hydrogen of RuIV and of FeIII, RuIII itself is resistant to reduction by hydrogen. The rate law for the reduction of RuIV and FeIII is −d[H2]/dt = k1[H2][RuIII], where k1=4.0 × 1014 exp [-23,800/ RT]M−1 sec−1. Mechanisms of the reduction reactions are discussed.
Adsorption of Hydrogen on Low Percentage Pt/Al2O3 and Pd/Al2O3 Catalysts in the Liquid Phase
d. v. sokol’skii and e. i. gil’debrand, Proc. Acad. Sci. U.S.S.R., Chem. Section, 1960, 133,(1−6), 855-857 (Transl. of Doklady Akad. Nauk S.S.S.R., 1960, 133, (3), 609-612)
Catalysts containing 0.05 to 3.47% of the metal were prepared, suspended in a buffer solution (CH3COOH/NaOH), and saturated with hydrogen by shaking. The adsorbed hydrogen was determined by shaking the catalyst with quinone and determining the hydroquinone formed. It was found that as the concentration of Pt and Pd in the catalyst is increased, their adsorption capacities decrease sharply at first and then more slowly. The adsorption capacity of Pd is less than that of Pt. The phenomenon of excess paramagnetism developed by the Pt and Pd during hydrogenation reactions is discussed.
Annual Review of U.S.A. Patents on Petroleum Refining and Processing
g. heinemannand p. a. lefrancois, World Petroleum, 1961, 32, (8), 53-59, 112 183
patents are reviewed. The processes covered by the patents include catalytic reforming and petrochemical production, hydrocracking, catalytic cracking, hydrogenation, dehydrogenation, alkylation, dealkylation, isomerisation, and desulphurisation. Pt metal catalysts are employed in many of the processes.
Reforming the 60°-140° Benzine Fraction and Standard B-70 Benzine of Bakinski Petroleum on a Platinum Catalyst
n. i. shuikin, kh. m. minachev, v. s. aliev, i. i. sidorchuk and m. a. ryashentseva, Zhur. Priklad. Khim., 1961, 34, (2), 461-463
Reforming was carried out at 480°−500°C, 40−50 atm hydrogen pressure, and space velocity 2−3/h in the presence of a 0.5% Pt/Al2O3 catalyst. Under the given conditions, 45.8−57.9% aromatic hydrocarbons were produced from the 60°−140° benzine fraction and 38.6% from the B−70 benzine. Five-membered ring compounds and alkanes were also present in the catalysate.
Catalytic Isomerisation of n-Pentane on a Platinum Catalyst
n. r. bursian and g. n. maslyanskii, Khim. Prom., 1961, (3), 18-20
A supported 0.6% Pt catalyst was used in the isomerisation process which was carried out under pressure. The effect of variations in the hydrogen: n-pentane ratio, pressure, temperature, and volumetric flow rate was studied. Optimum parameters found were: temperature, 400-420°C; molar ratio of hydrogen :n-pentane, 3:1; the rate of addition of n-pentane, I volume/volume of catalyst/h. The yield of iso-pentane under these conditions was 50%, and that of C,-C., gases below 1.5%.
Galvanic Corrosion of Glass Tank Refractories
f. j. shonebarger, Glass Technol., 1961, 2, (2), 53-59
Cells consisting of molten glass as the electrolyte and a refractory bar and coiled Pt wire as electrodes were used to investigate the corrosion of refractories by molten glass. The refractory bars were supported by Pt tie wires. It was found that the corrosion of refractories may be accelerated by the electrical potentials established by refractory combinations exposed to molten glass.
New Plant Features Latest Look in Making Glass Fibres
n. p. chopey, Chem. Eng., 1961, 68, (10), 136-139
The processes operated at the Aiken, S. C., Owens-Coming plant are described briefly and a flowsheet is given. Glass filaments are drawn directly from the forehearths of recuperative furnaces through Rh-Pt bushings, treated with a binder material, and wound on spindles. New features of the winding process are mentioned.
Mechanical Strength of Polycrystalline Materials Produced from Glasses Containing Platinum
m. tashiro, s. sakka and m. wada, Yogyo Kyokai Shi, 1960, 68,223 (Br. Ceram. Abs., 1961, 60, (5), 215A)
The effect of the addition of Pt on the bend- strength of glasses containing Li2O, MgO, Al2O3 and SiO2 was investigated. 0.01% Pt is sufficient to cause complete devitrification of some glasses. The bend strength of devitrified glass increases with increasing Pt content and is influenced by the Li2O content.
The Transfer of Material between Contacts of Precious Metal Alloys and Its Dependence on Heat Treatment
w. merl, Metall, 1961, 15, (7), 672-674
Contact materials used in the investigation were 40% Cu-Pd, 3% Co-Au, 10% Ni-Au and 16% Ni-Au alloys. The electrical and thermal conductivities of these alloys may be increased by lattice changes (Cu-Pd) or precipitation processes (Co-Au, Ni-Au). The mechanisms of bridge transfer and coarse transfer are discussed.
Mechanics of Electrical-Contact Failure Caused by Surface Contamination
s. w. chaikin, Electro-Technol., 1961, 68, (2), 70-75
Methods of examining sealed relays contaminated by base metals and organic material are described. Non-conducting deposits may be formed on contact surfaces, either spontaneously or during friction, by the polymerisation of organic vapours evolved by insulating materials. The contamination of Pd and Au contacts under static conditions was studied, and frictional polymers formed on Au, Ag, Pd and Au alloy contacts were also examined. It is concluded that the latter are produced by the combined effects of catalysis and electron emission. Contamination may be controlled by chemical and ultrasonic cleaning, selection of insulating and contact materials, and the use of carbon pellet “getters”.
ELECTRONICS AND TELECOMMUNICATIONS
The Selection of Contact Materials for Telephone Switching
l. borchert, Nachrichtentech. Z. (N.T.Z. ), 1961, 14, (4), 175-179
The suitability of Ag, Pd, Pd-Ag, Ni-Au, Ni-Pt, and W-Pt contact materials is discussed. Pd-Ag alloys containing 30-50% Pd are recommended for use in relays and selectors. Their satisfactory performance in the presence of H2S, organic vapours, and under various climatic conditions, is described. (20 references)
Calibration of Platinum Resistance Thermometers
anon., Nat. Bur. Stds. Tech. News Bull., 1961, 45, (4), 62-65
The calibration of long stem-, capsule-, and calorimetric-type resistance thermometers is described. Stem-type thermometers are calibrated at the boiling points of oxygen (−182.97°C), water, and sulphur (444.6°C), and at the triple point of water (0.01°C). The calorimetric-type are calibrated at the triple point, steam point, and near 50°C. Capsule-type thermometers are calibrated over the range −263° to −183°C in a hydrogen bath against N.B.S. standard resistance thermometers. Resistance measurements are made using a Mueller-type bridge.
Accurate Recording of Fast-Changing Temperatures
d. h. nalle, I.S.A.J., 1961, 8, (6), 58-59
A system consisting of a Pt resistance thermometer, a Wheatstone bridge, a carrier amplifier and a direct-recording oscillograph is described. Applications include the measurement of average and differential temperatures.
High Temperature Black Body Radiation Source
h. p. beerman, Bull. Amer. Ceram. Soc., 1961, 40, (5), 308-309
A standard radiation source consists of 40% Rh-Pt wire wound on an Al2O3 core which has a conical cavity, blackened with a fired-on Pt paste.
A Pt:10% Rh-Pt thermocouple is embedded in the counterbore of the cone close to its apex. The core is insulated by bubble Al2Os and diatoma- ceous earth. The operating range may be extended from 1650° to r850°C by using a Rh winding, an Ir:40% Rh-Ir thermocouple, and different core and insulating materials.