ABSTRACTS: January 1964
ABSTRACTS: January 1964
of current literature on the platinum metals and their alloys
On the Thermal Expansion Coefficient and the Temperature Coefficient of Young’s Modulus of the Alloys of Iron and Platinum
h. masumoto and t. kobayashi, J. Japan Inst. Met., 1963, 27, (9), 459-460
53.5 to 57.0% Pt alloys with Fe have negative coefficients of thermal expansion with a maximum value of —23.68 × 10-6 for 56% Pt alloy at o to 40°C. 51 to 69% Pt alloys have positive temperature coefficients of Young’s modulus with a maximum value of +161.5 ×10-6 for 55% Pt alloy in the same temperature range. A vertical dilatometer and a vibrator-controlled oscillator with an electrostatic transducer were used for the respective measurements.
Theory of Hydrogen Adsorption on Platinum
t. toya, J. Res. Inst. Catalysis Hokkaido Univ., 1962, 10, (3), 236-260
There are two types of H adsorption on Pt. r-type adsorption increases the work function and electrical resistance of clean Pt while s-type adsorption decreases them. The total effect on Pt is complex as the difference between the two heats of adsorption is only 0.4 kcal/mol whereas for Ni, which behaves similarly, it is 10 kcal/mol. The positions and entropies of the two types of adsorption are discussed. The broad, intense infra-red band at 4.86μ in the spectrum of H on Pt is caused by s-type adsorption and the sharp, weak band at 4.74 μ by r-type adsorption.
Ultra-pure Hydrogen by Diffusion through Palladium Alloys
j. b. hunter, Abs. Papers, 145th Meeting, Am. Chem. Soc., 1963, 128-130
The development of a stable, highly permeable alloy of Pd has led to its industrial application in a variety of diffusion units. H2 transfer rate data are presented for wide ranges of pressure and temperature.
Magnetic and Dilatometric Measurements on the Transformation Kinetics of the Iron-Palladium Alloys
a. kussman and k. jessen, Z. Metallkunde, 1963, 54. (9), 504-510
Studies on γ-α. transformations and γ1-γ2 ordering confirmed the existence of a miscibility gap between 10 and 25 at.% Pd-Fe alloys at high temperatures. The critical temperature curve for γ1-γ2 ordering showed a maximum at 800°C, 65 at. % Pd. A eutectoid occurred at 46 at. % Pd, 605±8°C. The effects of variations in the treatment of the alloys were also studied. Fe-Pd alloys behaved similarly to Ni-Fe alloys after quenching, particularly by showing an Invar effect.
The Iron-Palladium Phase Diagram below 950°C
e. raub, h. beeskow and o. loebich, Z. Metallkunde, 1963, 54, (10), 549-552
The results of room- and high-temperature X-ray analysis of the Fe-Pd system are tabulated. No γ/α eutectoid was observed but a miscibility gap extended from 7 to 23 at.% Fe, with a critical temperature of about 900ºC. A eutectoid between α-Fe and the γ1 phase was confirmed at about 620°C, 43 at.% Fe. The two ordering phases γ1 and γ2 were separated by a narrow two-phase region below a eutectoid area. γ2 has a higher critical temperature than γ1- (820±20°C and 790±20°C).
On the Structural Form of Copper-Palladium Solid Solutions near the Composition Cu3Pd
a. a. presnyakov, l. i. dautova and e. a. dzhanbusinov, Fiz. Met. Metalloved., 1963, 16, (1), 61-64
28.8 at.% Pd-Cu alloy samples were tempered at 750°C, annealed and studied by X-ray methods. The crystal lattice structure is discussed. At high temperatures a structure was detected which indicated the existence of a new phase but its lattice parameters were not determined.
Properties of Palladium-Rhenium Alloys
m. a. tylkina and i. a. tsyganova, Zh. Neorg. Khim., 1963, 8, (10), 2346-2350.
Additions of up to 11.9 wt.% Re increased the hardness and strength and the specific electrical resistance of Pd but decreased the temperature coefficient of resistance. Re also raised the initial temperature of recrystallisation of Pd; by up to 600°C in the case of 8.74 wt.% Re-Pd. Annealing studies on Re-Pd showed that higher temperatures reduced the hardness and strength but improved the elastic properties of the alloys. Electrical properties were unaffected by the annealing treatments.
The Temperature Dependence of the Magnetic Susceptibility of Some Palladium Alloys
w. köster, d. hagmann and r. lueck, Ann. Physik, 1963, 11, (1-6), 52-58
Temperature-reciprocal paramagnetic susceptibility curves for Pd alloys with up to 4 at. % Ru or 10 at.% Cd, In or Rh between 120 and 1100°K agreed with the transport aspects of Stoner’s theory of paramagnetism. Various explanations of the electron specific heat-susceptibility discrepancy in Pd showed that no one definition of Stoner’s parameters 0F, q, 01 was possible. An approximation using the reciprocal temperature coefficient of the reciprocal susceptibility explained vacancy variations in the alloys but this quantity was not the same as the Curie constant unless T>>0F. The rigid band model gave a partial interpretation of the results.
Hysteresis in the Palladium-Hydrogen System
n. a. scholtus and w. k. hall, J. Chem. Phys., 1963, 39, (4). 868-870
When H2 dissolves in Pd, the α phase forms first. The β phase nucleates and grows in this causing plastic deformation of the α phase beyond its elastic limit because of the large α → β volume change. Absorption is accompanied by β phase growth under α phase compression but desorption takes place from the β phase of the plastically deformed solid. This is not reversible and hysteresis occurs. Earlier theories are discussed. The absorption loop of the isotherm is calculated from the desorption loop and the yield strength of Pd.
Role of Hydrogen Atoms in Palladium
t. tsuchida, J. Phys. Soc. Japan, 1963, 18, (7), 1016-1019
Ag-Pd alloys are similar in electronic structure to Pd but do not have the narrow regions of H2 content stability of pure Pd. Measurements of the Hall coefficient and magnetic susceptibility of hydrides of 10 to 30 at.% Ag-Pd alloys were made as functions of H2 content. As H2 was occluded the paramagnetic susceptibility decreased and the Hall coefficient decreased considerably in the high H2 content β-phase alloys. The H atom was considered to act like a proton in the Pt lattice by transferring a valence electron to the Pd 4d band.
The Phase Diagram Rh-Sb
r. n. kuz’min and n. n. zhuravlev, Vestnik Mosk. Univ., Ser. III, Fie. Astron., 1963, 18, (2), 9-14
X-ray and micrographic studies of the Rh-Sb system indicated the existence of a γ-phase at about the Rh3Sb2 composition and a eutectic point between the compositions RhSb2 and Rh2Sb. The solubility of Sb in Rh reached about 8 wt. % at 1150°C.
Thermal Analysis of the Rh-Bi System
r. i. kuz’min, n. n. zhuravlev and g. s. zhdanov, Zh. Neorg. Khim., 1963, 8, (8), 1906-1914
Results of thermal analysis of Bi-rich alloys slightly modified previous constitution diagrams of the Bi-Rh system. The eutectic point was detected at 1.4 at.% Rh and 268°C. The transition temperature between α- and β-Bi2Rh occurred at 430°C. Peritectic temperatures were 456°C and 775°C.
On the Superconductivity of Ti- and Zr-Rh Alloys
c. J. raub and c. a. andersen, Z. Physik, 1963, 175, (1), 105-114
The connection between superconductivity and valence electron concentration was studied in Ti-and Zr-alloys containing up to 12 at.% Rh. In both the h.c.p. α-phases and b.c.c. β-phases the transformation temperature increased with valence electron concentration. By extrapolation to 0% Rh it was shown that the transformation temperatures for Ti and Zr β-phases lie below those of the α-phases.
The Structure of the Stable Tantalum-Ruthenium Alloys
e. raub, h. beeskow and w. fritzsche, Z. Metallkunde, 1963, 54, (8), 451-454
The Ru-Ta system is similar to the Ru-V and Ru-Nb systems. X-ray and microscopic analysis of alloys with increasing Ru content showed the occurrence of transitions from the b.c.c. solid solution to an ordered B2 structure, followed by tetragonal distortion, an ordered orthorhombic form and an ordered f.c. tetragonal form at high Ru content.
Melting Points of LaRu2, CeRu2 and PrRu2
r. d. reiswig and k. a. gschneidner, J. Less-Common Metals, 1963, 5, (5), 432-433
The observed melting points of the Laves phases were: LaRu2 at 1431±30°C, CeRu2 at 1539 + 30°C, PrRu2 at 1681±15°C. Melting was probably incongruent.
Vapour Pressures of Platinum Metals. III. Iridium and Ruthenium
r. c. paule and j. l. margrave, J. Phys. Chem., 1963, 67, (9), 1896-1897
Vapour pressures, heats of sublimation and boiling points were obtained for solid Ir and Ru. Ir has log P Ir (solid) = 10.120—33,680/T for 2140°K<T<2477°K, ΔH298 = 160.9±2.8 kcal/ mole and estimated normal b.p.≈4850±1100°K. Ru has log PmmRu (solid) = 11.200—33,600/T for 2140°K<T<2330°K, AH298 = 151.5±4 kcal/ mole and estimated normal b.p. ≈4350±100°K.
The Alloys of Ruthenium with Titanium and Zirconium
e. raub and e. roschel, Z. Metallkunde, 1963, 54, (8), 455-462
Microscopic and X-ray methods confirmed the existence of intermediate B2 phases TiRu and ZrRu, which melt congruently at 2100-2150°C and show no phase transformations nor decompositions at lower temperatures, and of the C14 Laves phase ZrRu2, which decomposes eutectoid-ally at 1300± 20°C. Ru has low solubility in α-Ti and α-Zr but more in β-Ti and β-Zr. Ru stabilises, β-Ti and can depress the β →α transformation below room temperature for 16-20 at. % Ru. Considerable precipitation hardening occurs in Ti-rich alloys. Study of the β→α transformation in Zr-Ru alloys is made difficult by the oxidation of Zr, causing the alloys to appear ternary.
A Study of the Adsorption and Decomposition of Hydrocarbons on Clean Iridium Surfaces
r. w. roberts, J. Phys. Chem., 1963, 67, (10), 2035-2038
CH4, C2H6 and C2H4 were admitted to Pyrex flasks on the inner surfaces of which Ir films had been prepared under ultra-high vacuum conditions. They were adsorbed on the clean films at 27 and 100°C. CH4 did not decompose on Ir but C2H„ decomposed to CH4 and H2 at 27°C and to CH4 at 100°C. O2 preadsorbed on Ir inhibited C2H6 decomposition. C2H4 was self-hydrogenated to C2H6 and CH4. The roughness factor of the Ir films was about 7.
High Temperature Properties of Refractory Alloys
e. j. rapperport and a. l. geary, U.S.A.E.C. Report N.M.I.-1253, 67 pp.
Ten alloy systems of the refractory metals Mo, W, Nb and Ta with additions of Hf, Re, Os, Ru, Rh, Ir and Zr were studied by hot hardness tests up to 1200°C and oxidation resistance tests at 1000°C to determine their suitability for use in nuclear reactors. Ru, Os and Re additions increased the hardness by up to 7 times at room temperature and up to 17 times compared to the unalloyed refractory metals. These alloys were then tested for tensile strength up to 1800°C. 2-10 at. % Ru-W, 2-10 at. % Ru-Ta and 2-10 at. % Re-Nb showed greater strength worth further study.
Oxidation of the Platinum-Group Metals
c. a. krier and r. 1. jaffee, J. Less-Common Metals, 1963, 5, (5), 411-431
Samples of the six Pt-group metals were heated in a slowly moving stream of dry air at 1000-1400°C and all showed linear weight loss rates in the range 1200-1400°C by the formation of volatile oxides. Rh gained weight at 1000°C by the formation of an oxide film and Pd initially absorbed O2. At I400°C in a slow air stream at 1 atm. the rates of weight loss were 6.8 × 10-3 mg/cm2/hr for Rh, 9.6 × 10-3 for Pt, 3.1 for Ir, 1.2 × 102 for Ru and 1.2 × 10-3 for Os. The rates depended on the gas flow rate, the partial pressure of O2 and the total gas pressure. The kinetics of the reactions also depended on the temperature. The mechanism of reaction of the O2 at the surface is discussed and specimens are illustrated.
Superconductivity of Some New Pt-Metal Compounds
c. j. raub, w. h. zachariasen, t. h. geballe and b. t. matthias, J. Phys. Chem. Solids., 1963, 24, (9), 1093-1100
Tests on compounds of the Pt metals with P, As, Sb, Bi and S revealed several previously unknown superconductors in the systems Rh-As, Pd-P and Pd-As. Transition temperatures and crystallo-graphic data are listed for all known superconductors of the Pt metals with elements of groups IVA, VA, and VIA.
The Problem of Producing Superconducting Materials
e. m. savitskii and v. v. baron, Metallurgiya i Gornoe Delo, 1963, (5), 3-12
Among a large number of superconducting substances reviewed there are more than thirty compounds of the Pt metals, for which the transition temperatures and Curie points are tabulated. Their formation, properties and uses are discussed. (24 references.)
Structure and Reactivity of the Oxyanions of Transition Metals
a. carrington and m. c. r. symons, Chem. Rev., 1963. 63, (5), 443-460
Known oxyanions of the Pt metals are RuO4, RuO-2 RuO2-4 and OsO4 and RhO2-4” is also believed to exist. The electronic structure and reactions of these tetrahedral oxyanions, together with those of V, Nb, Ta, Cr, Mo, W, Mn, Ti, Re and Fe are critically discussed. (115 references.)
Unusual Oxidation States of the Noble Elements
n. bartlfett, Chem. in Canada, 1963, 15, (8), 33-40
The structure and properties of the fluorides, oxides and oxyfluorides of the Pt metals are discussed. Particular note is made of OsOF5 and PtO2F6. Work on the [PtF6r ion led to the discovery of the noble gas fluoride compounds, the bonding of which is also reviewed. (38 references.)
Aromaticity of Five-Membered Rings Containing Platinum (II)
p. haake and p. a. cronin, Inorg. Chem., 1963, 2, (4), 879-880
Conductometric studies on the kinetics of displacement of chloride by dithiooxamide in methanol indicated that a strong trans effect resulting from aromaticity in the Pt-α-diimine chelate ring caused the Pt(bipy)Cl2 complex to react nearly one hundred times faster than the cis-Pt(py)2Cl2 or Pt(en)Cl2 complexes.
Aromatic Complexes of Metals. LXXV. Cyclopentadienyl-palladium-nitrosyl
e. o. fischer and a. vogler, Z. Naturf., 1963, 186, (9), 771-772
C5H5PdNO was prepared by the reaction of PdNOCl with NaC5H5 in pentane with air excluded and its absorption spectrum was studied.
Complexes between Palladium (II) and Pyridine-2-aldoxime
c. f. liu and c. h. liu, Inorg. Chem., 1963, 2, (4), 706-707
The tetrachloropalladate (II), chloride and nitrate of monohydrogen bis-(pyridine-2-aldoxime)-pal-ladium (II) ion were prepared and compared to similar Pt(II) and Cu(II) compounds. The inner complex between pyridine-2-aldoxime and Pd(II) was also prepared. In contrast to the Pt(II) inner complex only the trans isomer of Pd(II) was obtained.
Preparation and Properties of Anhydrous Rhodium (II) Acetate and Some Adducts Thereof
s. a. johnson, h. r. hunt and h. m. neumann, Inorg. Chem., 1963, 2, (5), 960-962
Rh(II) acetate was prepared by the reaction of Rh(OH)3. H20 with glacial acetic acid. Stable adducts with 2 ligands to each dimer were formed with H20, tetrahydrofuran, acetonitrile, dimethyl sulphoxide, dimethyl sulphide, trimethylamine, NH3, N02 and ethylenediamine. The properties and spectra of Rh(II) acetate and these adducts are discussed.
J. h. holloway and r. d. peacock, J. Chem. Soc., 1963, (July), 3892-3893
RuF4 was formed by the reaction of I2 with RuF5 dissolved in IF5. RuF4 was highly reactive and reacts violently with H2O to form RuO2. The magnetic moments of RuF4 were measured in the range 90 to 300°K. X-ray diffraction analysis suggested that it has a simple structure.
Anhydrous Ruthenium Chlorides
j. m. fletcher, w. e. gardner, e. w. hooper, k. r. hyde, f. h. moore and j. l. woodhead. Nature, 1963, 199, (4898), 1089-1090
The preparation and magnetic properties of α-RuCl3, β-RuCl3 and Ru2OCl2 are described. α -RuCl3 formed by heating Ru and Cl2 in siliceous vessels at 600°C contains some Ru2OCl6 which is diamagnetic and reduces the susceptibility. α -RuCl3 has now been made by heating β-RuCl3 above the β -transition temperature of 450°C. β -RuCls is formed by reacting Ru in CO and Cl2 at 360-390°C, with some α-RuCl3 formation. Ru2OCl6 occurs as a volatile oxide chloride in the mixture of aquochloro complexes known as commercial RuCl3. α -RuCl3 is antiferromagnetic and β -RuCl3 has low magnetic susceptibility.
Relation between the Activation Energy of Some Electrochemical and Catalytic Processes and the Properties of Metals
v. v. demchenko, Zh. Fiz.Khim., 1963, 37, (8), 1718-1725
Electrochemical and catalytic processes such as hydrogenation, isotope exchange and H2 formation at the electrode, where metal-H2 bonding occurs as an intermediate step, are reviewed. Activation energy is proportional to the increase in surface tension of the cathode or catalyst surface. Graphs illustrate this effect for Pt, Pd, Rh, Ir, Os and a number of base metals. (16 references).
On the Thermodynamics of Platinum Oxide Electrodes
b. novak and t. markovic, Monat. Chem., 1963, 94 (3), 607-620
The energy of formation of each oxide, hydroxide and oxide hydrate of Pt in aqueous solution was determined. Data are fully tabulated and extensively discussed.
Electrochemical Oxygen- and Hydrogen-Chemisorption on Smooth and Rough Platinum
h. dietz and h. gohr, Z. phys. Chem., Leipzig, 1963, 223, (1/2), 113-131
The chemisorbed H2 or O2 films which can be formed on Pt electrodes are produced continuously only if the electrodes are continually cleaned. Film formation then becomes a steady process whereas if the films are allowed to build up the potential of the circuit alters and the current is reduced.
The Mechanism of Electrochemical Oxidation of Carbon Monoxide and Methanol on Platinum. I. Carbon Monoxide Adsorption and Desorption and Simultaneous Oxidation of the Platinum Surface at Constant Potential
s. gilman, J. Phys. Chem., 1963, 67, (9), 1898-1905
The oxidation of the surface of a Pt electrode covered with adsorbed CO in a saturated solution in 1 NHClO4 of a 100% or 1% CO gas mixture is rate-controlled by the removal of adsorbed CO, as shown by current-time traces after raising the electrode potential from 0.4 to >0.8V.
II. Interpretation of the CO and “Oxygen” Adsorption Data Obtained at Constant Potential
s. gilman, Abs. Papers, 145th Meeting, Am. Chem. Soc, 1963, 22B-49
The oxidation of both the adsorbed CO and thePt surface are interpreted by a reactant-pair mechanism which assumes that the actual reactants are adjacent CO arid H2O adsorption molecules.
Mechanism of Anodic Oxidation of Organic Compounds on Platinum
v. s. BAGOTZKY, Abs. Papers, 145th Meeting, Am. Chem. Soc., 1963, 21K-58
The adsorption of reacting species on the Pt surface affects the rate of oxidation. Adsorption of O2 on the surface reduces the reaction rate exponentially.
The Normal Oxygen Potential on Bright Platinum
J. p. hoare, J, Electrochem. Soc, 1963, 110, (9), 1019-1021
Experiments showed that when a Pt surface was completely covered by a chemisorbed monolayer of O2 the surface was passivated with respect to its reaction with oxygen. The layer was produced by passivating Pt beads in HN03. A rest potential of 1225 ±10 mV was observed for up to 24 hours or more.
Electrochemical Corrosion of Iridium in Hydrochloric Acid Solutions
J. llopis and l. jorge, J. Electrochem. Soc, 1963,110, (9), 947-951
Electrolysis of Ir in HCl showed that in all respects Ir is more corrosion resistant than Pt. Ir was attacked more strongly as the HCl concentration and temperature increased. An a.c. superimposed on the d.c. increased the effect, especially at low frequencies, but the corrosion was negligible until a threshold value of ia.c.»id.c. was reached. Dissolution and passivation mechanisms were studied.
LABORATORY APPARATUS AND TECHNIQUE
Purity of Hydrogen Permeating through Pd, Pd-25% Ag, and Ni
j. r. young, Rev. Scient. Instrum., 1963, 34, (8), 891-892
A technique for determining the purity of diffused H2 is described. Impurities in H2 permeating through Pd or 25% Ag-Pd alloy tubes were a few parts in 1010. The lowest impurity content from Ni was found to be 1 part in 106. CO was the main impurity in all cases.
Specimen Heating with Temperature Measurement from — 150°C to 2200°C inside the EM6 Electron Microscope
j. a. headley and j. mcgeagh, J. Scient. Instrum., 1963, 40, (10), 484-486
Equipment is described to enable the temperature range —150 to 2200°C to be studied. The high and medium temperature heating stages incorporate solid Pt in the grid holders and caps because of its high melting point, low electrical resistance and resistance to oxidation. The Pt carries the current to heat the grid in the high temperature stage. Pt wire forms a resistance furnace in the other case.
The Durability of Pt-Rh Alloys in Analytical Apparatus
g. reinacher, Werkstoffe u. Korrosion, 1963, 14, (7), 574-579
Five typical analytical laboratory operations tested Rh-Pt alloys to show that they can well be used in corrosive conditions up to 1000°C. A tarnish developed during annealing in air and during soda-potash fusions but weight constancy was of the same order as ordinary apparatus Pt. Resistance to acids was as good as with Pt. Weight losses during potassium bisulphate fusions increased with temperature but, by lining with Pt, the crucibles combined resistance to attack with resistance to deformation. 20% Rh-Pt has been used for ferrophosphorus and ferrosilicon extractions and 10% Rh-Pt for HF and H2SO4 evaporations and various fusions. The dark Rh oxide tarnish could be avoided by Pt linings. Lined and unlined 10, 20 and 30 wt.% Rh-Pt alloy apparatus is therefore profitable for many high temperature analyses.
New Era Brazing Turns to Filler Metals with Palladium
a. s. cross and j. b. adamec, Welding J., 1963, 42, (8), 645-649
Pd-containing brazing alloys are ductile with good wetting and flowing properties and do not erode the base metals with which they are used. Sixteen alloys are described of which five Ag-Pd and Ag-Cu-Pd alloys cover the melting range 1490°C to 2250°C which is so important for electronic equipment. The alloys possess considerable strength at high temperature. They also fill gaps satisfactorily and reduce stress cracking. Their low vapour pressure makes them suitable for vacuum applications. (13 references).
Ceramic-to-Metal Seals for High Temperature Operation
e. l. brundige and g. s. hanks, U.S.A.E.C. Report LAMS 2917, 1963, 36 pp.
A nuclear fuel element design required Nb components to be separated by A12O3-Y2O3, a ceramic capable of withstanding Cs vapour at 1500°C. Bonding the ceramic to Nb was by metallising with W and then brazing with Pd applied by plating the W surface or as Pd foil before joining and sealing. Seals for use to 1000°C can be made from Co-Pd braze alloy added to the joint as foil or by plating with alternate layers of Co and Pd.
Active Centres of Platinum Adsorption Catalyst in the Oxidation of Ammonia
v. i. shekhobalova and n. i. kobozev, Zh. Fiz. Khim., 1963, 37, (9), 2131-2132
Analysis of the reaction products of oxidation of NH3 over Pt/SiO2 showed that the Pt exists in monoatomic form on the catalyst support. Theoretical relations were established such that for SiO2 with 300 m2/g and temperatures of 300 and 350°C, the apparent activation energy could be calculated as 10,700 cal/mol.
The Relation of the Catalytic Properties of Platinised Silica Gel to the Conditions of its Preparation
m. d. adamenkova and o. m. poltorak, Vest. Mosk. Univ., Ser. II, Khim., 1963, (5), 12-16
The catalytic activity of Pt/SiO2 prepared by the adsorption of ammines of Pt on Si02 depends on the SiO2 grain size, the drying temperature and the conditions of ammine reduction by H2. SiO2 should be homogeneous but too much grinding reduces the activity. Pt ammine adsorption is uniform after 3 days but not after 5 minutes. Drying at 100°C gives higher activity than drying at 60°C. 300°C is the optimum reduction temperature for the Pt ammines. Tests on three series of differently prepared samples showed that the level of activity for 0.5 to 3.15% Pt contents is higher than for 3.5 to 7% Pt.
The Hydrogenation of Diene Hydrocarbons over a Platinum Catalyst in Liquid Phase
l. kh. freidlin and e. f. litvin, Izv. Akad. Nauk S.S.S.R., Ser. Khim., 1963, (7), 1307-1312
Saturated hydrocarbons were formed by the hydrogenation of dienes over Pt black catalyst at conversions of up to 70 to 80%, mainly by two H2 molecules becoming attached to each diene molecule without desorption of intermediate products from the catalyst surface. Tests with isoprene, trans -piperylene and 2, 3-dimethyl-butadiene-I, 3 and binary mixtures of α -olefins with isoprene showed that, at high degrees of diene conversion, some saturated hydrocarbon was derived from the α-olefins, simultaneous hydrogenation having taken place. There was high diene selectivity with alkaline solution but poor selectivity with acid solutions.
Kinetics of Dehydration of Cyclohexa-diene-1, 3 on Platinum Films over a Wide Range of Temperature
v. d. yagodovskii, v. m. gryaznov and e. a. savel’eva, Kinetika i Kataliz, 1963, 4, (5), 746-752
The activation energy of the dehydrogenation of cyclohexadiene-I, 3 on thin Pt films was shown to increase sharply at higher temperatures in the 200-500°C range. Treatment of the Pt films at 700°C further increased the activation energy for tests in the 500-600°C range. An interpretation of the results relates the condition of the active part of the Pt surface to the thermodynamic equilibrium of the system.
Stereoisomers 3β, -Dihydroxyandrostan-16-ylacetic Acids
p. kurath, w. cole, j. tadanier, m. freifelder, g. r. stone and e. v. schuber, J. Org. Chem., 1963, 28, (9), 2189-2194
The conditions of hydrogenation of 3βα, 17β-diacetoxy-5-androsten-16-ylidenacetic acid over Pt02 were adjusted to improve the yield of 3β, 17β-diacetoxy-5-androsten-16β-ylacetic acid and the stereochemistry of the four possible tetra-hydro products was derived.
The Hydrogenation of the Stereoisomers of Piperylene on Metallic Catalysts
l. kh. freidlin and e. f. litvin, Neftekkimiya, 1963, 3, (3), 326-329
The hydrogenation of the cis and trans isomers of piperylene (1, 3-pentadiene) in methanol using Pt and Pd blacks and Raney Ni as catalysts yields all the three possible pentenes in amounts which differ substantially from one system to another. Very little pentane is formed in the early stages of the reaction over Pd and Ni, but pentane constitutes about 35% of the initial products formed over Pt. No isomerisation between the piperylene isomers was detected.
Selectivity and Stereospecificity in the Hydrogenation of Acetylene Hydrocarbons on Metal Catalysts
l. kh. friedlin and yu. yu. kaup, Doklady Akad. Nauk S.S.S.R., 1963, 152, (6), 1383-1386
Tests on pentyne-2 and pentyne-I, using Raney Ni, Raney Co, Pd black, Pt black, and Rh black catalysts established that the order of selectivity in the first stage of hydrogenation is Pd>Pt> Rh>Ni>Co and that the order of stereospecificity is Pd> Ni=Co>Pt>Rh. Isomerisation of the products was also studied.
Hydrogenation of 2-Methyl-5-acetylfurans in Liquid Phase
n. i. shuikin, 1. f. bel’skii, g. k. vasilevskaya and v. m. shostakovskii, izv. Akad. Nauk S.S.S.R., Ser. Khim., 1963, (8), 1475-1478
When 2-methyl-5-acetylfuran was hydrogenated over Pt/C and Pd/C in liquid phase at 100°C with 100 atm. initial pressure of H2, the furan ring was not reduced but hydrogenolysis occurred at the C-O bond adjacent to the CO group. Heptane-dione-2, 6 was produced which was further converted by cyclisation to cyclohexanone and cyclohexanol (20-30%) and by reduction to heptanediol-2, 6, which was partly cyclised to 2, 6-dimethyltetrahydropyrane (about 50-60%). Over Pd/Al2O3 at 180°C the CO group was reduced to CH2 followed by hydrogenation of the furan ring to produce 2-methyl-5-ethyltetra-hydrofuran (about 60%).
The Oxidation of defines by Palladium Chloride Catalyst
j smidtj Bull. Assoc. Franc. Tech. Petrole, 1963, (160), 467-487
The oxidation of olefines to carbonyl compounds with the same number of C atoms by O2 in aqueous solutions of PdCl2 and CuCl2 is described and reaction mechanisms are discussed. Higher olefines and other unsaturated compounds are attacked by O2 at points within the molecule depending on the groups attached to the double-bond C atoms and on the Pd ligands. Ketones and aldehydes are formed from α-olefines in fixed proportions. The transesterification of vinyl esters is the most important non-oxidation reaction of unsaturated compound in which Pd salts act as catalysts.
Kinetic Study on the Oxidation of Propylene in the Presence of Palladium Chloride
t. dozono and t. shiba, Bull. Japan Petroleum Inst., 1963, 5, (March), 8-12
The rate of the catalytic oxidation of propylene to form carbonyl compounds by Smidt’s process, using acidic PdCl2/CuCl2 solution, was shown to be r=k Pp’°p’ where [PdCl2] and [CI-] are the total concentrations of PdCl2 and Cl- ion respectively, where [H+] is the initial H+ ion concentration and where pprop, is the partial pressure of propylene; k is a constant.
Oxidation of Alcohols by Palladium Salts in Aqueous Solution
a. v. nikiforova, i. i. moiseev and ya. k. syrkin, Zh. Obshch. Khim., 1963, 33, (10), 3239-3242
Aliphatic alcohols were oxidised to aldehydes and aliphatic-aromatic alcohols to ketones by PdCl2 in aqueous solution. The reactions were slower than for the corresponding olefines. Alcohols tested were ethyl-, isopropyl, N -butyl, N -amyl- and benzoyl-alcohol.
Isomerisation of Hexenes in Liquid Phase Hydrogenation Conditions in the Presence of Palladium Black
i. v. gostunskaya, a. i. leonova, n. b. dobroserdova and b. a. kazanskii, Neftekkimiya, 1963, 3, (4), 498-502
Double bond transfer from position I to position 2, but no further along the C chain, was observed during partial hydrogenations of hexene-l, 2-methylpentene-I, 3-methylpentene-I, 4- methylpentene-I and 2, 3-dimethylbutene-I in the presence of Pd black at atm. pressure and 20°C in C2H5OH medium. Compounds with two H atoms in the allyl positions were isomerised more readily than those with only one. Where the numbers of H atoms were equal, isomerisation occurred more readily with the compound more difficult to hydrogenate.
Isomerisation of Hexenes in the Presence of Palladium on Charcoal
b. a. kazanskii, n. b. dobroserdova, g. s. bakhmet’eva and 1. v. gostunskaya, Neftekkimiya, 1963, 3, (4). 503-506
The transfer of double bonds in hexenes was studied at 80°C in the presence of Pd/C and a stream of H2. The relation between the initial hexenes and the rates of transfer was obtained and this agreed with the associative mechanism for the reaction.
Inhibitors in the Palladium-Catalysed Hydrogenation of Aryl Nitro Groups
h. greenfield, J. Org. Chem., 1963. 28, (9), 2434-2435
Potential inhibitors of the hydrogenation of p -nitrotoluene to p -toluidine over 5% Pd/C were added to the reaction mixture at the rate of 5 mole% with respect to p -nitrotoluene, i.e. more than trace amounts. Sodium nitrate, acetate, sulphate, carbonate, phosphate, hydroxide, fluoride, bromide and chloride and ferrous chloride, n -octyl chloride, chlorobenzenc, bromobenzene, aniline, piperidine, sodium methoxide, phenol and p-nitrophenol caused no inhibition. Various amounts of poisoning were caused by potassium nitrite and sodium nitrate, sulphite, iodide, cyanide, sulphide and bisulphite and also by nickel (II), ferric, cobalt (II), chromium (III), copper (II), silver, aluminium, zinc and lead nitrates, ferric chloride, copper chloride and by certain nitroso compounds. Phenyl disulphide caused inhibition at very low concentrations.
Comparison of the Rates of Catalytic Reduction and Electroreduction of Some Organic Substances on Rhodium. HI
t. m. grishina, l. p. khomciienko and g. d. vovchenko, Vest. Mosk. Univ., Ser. II, Khim., 1963, (4). 55-58
The catalytic reduction rate on Rh was several times as great as its electroreduction rate for crotonaldehyde, acetone and amylaldehyde. Both rates decreased in the same order of substances. The rates decreased with changes in the electrolyte in the order H2SO4, HCl, KOH and HBr. Br- ions particularly poisoned the reductions. Rh has lower reduction rates than Pt but higher than Ru.
Study of Ruthenium Catalyst. I. Hydrogenation of Organic Compounds by Ruthenium Catalyst
y. tagaki, Sci. Papers Inst. Phys. Chem. Res. (Japan), 1963, 57, (2), 105-109
Ru and Ru/C catalysts were prepared and used in liquid phase hydrogenations at ordinary and high pressures. Carbonyl groups were more easily hydrogenated at ordinary pressure over Ru than over Pd. H2O and alkaline solvents were more effective than alcohol for these reactions. The hydrogenation of double bonds was difficult. Nitro groups could be hydrogenated but nitriles could not. At high pressure the rate of hydrogenation of allyl alcohol was rapid. Citronellal was used for studies on the hydrogenation of unsaturated aldehydes and the selectivity of such processes.
The Production of Polyhydroxy Alcohols from Wood-Polysaccharides
v. i. scharkow, Chem. -Ing. -Tech., 1963, 35, (7), 494-497
Optimum conditions for the simultaneous hydrolysis and hydrogenation of polysaccharides in the presence of Ru/BaSO4 or of Ru/’C are 0.7% H3PO4 solution, l60-165°C, 60-80 atm. pressure of H2 and a reaction time of 50-60 min. Other processes developed in the U.S.S.R. are based on the hydrolysis of the polysaccharides to monosaccharides which are subsequently hydrogenated, on hydrogenolysis of monosaccharides and on the pyrolysis of cellulose.
An Investigation of Catalysts Produced by Reactions between Sodium Borohydride and Salts of Heavy Metals
a. m. taber, b. d. polkovnikov, n. n. mal’tseva, v. i. mikheeva and a. a. balandin, Doklady Akad. Nauk S.S.S.R., 1963, 152, (i), 119-121
0.25 g samples of PdCl2, RhCl3 and H2PtCl„ were reacted with i g samples of NaBH4 and the products were analysed chemically, thermally and by spectrography. The infra-red spectra of Pd-B alloys and of borided Pd catalyst were very similar. H2 in the catalysts acted similarly to adsorbed H2.
Charging Curves of the Boride Catalysts of Pt-Group Metals
a. m. taber, a. a. balandin, d. v. sokol’skii and b. d. polkovnikov, Doklady Akad. Nauk S. S.S.R., 1963, 152,(2), 379-381
Results were plotted for Pt, Pd and Rh boride catalysts in 0.1 N solutions of NaOH, H2SO4 and HCl and for the anodic polarisation of phenyl-acetylene and diphenylacetylene. Charging was most rapid for the NaOH electrolyte and the acetylenes were most readily polarised over Pt. Isotherms for the solution of H2 in the catalysts were also determined.
Hydrogenolysis and Reciprocal Transitions of cis- and trans- 1,2-Dimethylcyclopen-tanes in the Presence of Rhodium, Osmium, Iridium and Palladium Catalysts
o. v. bragin, a. l. liberman, g. k. gurianova and b. a. kazanskh, Doklady Akad. Nauk S.S.S.R., 1963, 152, (4), 865-868
Studies at 150 to 280°C over Rh/C, Os/C, Ir/C and Pd/C showed the relative amounts of isomerisation and hydrogenolysis of cis- and trans 1,2-dimethylcyclopentane. The amount of hydrogenolysis and the proportion of cis- to trans- isomer increase with temperature. Pd/C and Rh/C appeared to be most active in these respects. The reaction mechanism is discussed and the effects are compared with Pt/C catalyst action.
A High Performance Saturated Hydrocarbon Fuel Cell
w. t. grubb and l. w. niedrach, J. Electrochem. Soc, 1963, 110, (10), 1086-1087
Propane has been oxidised rapidly in a new propane-oxygen fuel cell operating at only 150°C with a new porous electrode structure to preserve the catalytic properties of the Pt incorporated in it. The electrolyte was H3PO4. A voltage-current density curve when 14.6 M H3PO4 was used showed no limiting current in the range examined thanks to the thin structure of the electrodes.
A Direct Hydrocarbon/Air Fuel Cell
h. g. oswin, a. j. hartner and f. malaspina, Nature, 1963, 200, (4903), 256-257
The combustion of propane in a fuel cell using Pt black electrodes and H3PO4 electrolyte at temperatures up to 220°C produced currents of 100-200 mA/cm2 at 20-35% thermal efficiency. The process appeared to consist of catalytic cracking followed by combustion and again demonstrated the feasibility of direct hydrocarbon/air fuel cells.
The Development of a High-efficiency Hydrogen-diffusing Palladium-Alloy Anode for Use in Fuel Cells
h. g. oswin, s. m. chodosh and n. i. palmer, Abs. Papers, 145th Meeting, Am. Chem. Soc, 1963,14K-39
Thin Pd alloy membranes for use as H2-diffusing anodes were studied electrochemically and the effect of various operating parameters on anode polarisation were determined. Variables discussed include temperature, electrolyte composition, gas pressure and composition, membrane thickness and surface preparation.
Thin Fuel Cell Electrodes
r. g. haldeman, w. p. colman, s. h. langer and w. a. barber, Abs. Papers, 145th Meeting, Am. Chem. Soc, 1963,15K-42
Thin electrodes consisting of Pt and Pt-C supported on screens were found to be capable of very high performance. The Pt used was from 1 to 9 mg/cm2. Electrodes were tested in acidic and basic media and were studied for initial polarisation, length of service, effect of temperature and operation in air.
Anodic Protection of Carbon Steel in Sulphuric Acid
w. p. banks and j. d. sudbury, Corrosion, 1963, 19, (9), 300t-307t
Pt cathodes were used in tests on 1020-type mild steel samples. The tests showed that the effectiveness of anodic protection and the current density for maintaining protection depended on acid concentration and temperature. H2SO4 varied from 45 to 105% concentration and temperature from 80 to 535°F. Graphs illustrate the large increase in current density required with higher temperatures.