ABSTRACTS: October 1964
ABSTRACTS: October 1964
of current literature on the platinum metals and their alloys
The Properties of Platinum-Cobalt Magnets Produced by Powder Metallurgy
h. c. angus, Powder Metallurgy, 1964, 7, (13), 1-12
Co-Pt alloy magnets prepared from Pt and Co powders are superior to those prepared by melting. Fabrication and testing are described. Careful heat treatment is vital. The equiatomic stoichiometric alloy gives the best results. Energy products >107 gauss-Oe and coercive forces up to 4900 Oe have been obtained.
The Magnetic Structure of CoPt
b. van laar, J. Physique, 1964, 25, (5), 600-603
X-ray diffraction showed that tetragonal CoPt has a a=2.677Å,c= 3.685Å. Magnetic moments point along the c-axis. Co at (0, 0, 0) and Pt at (½,½, ½) are coupled ferromagnetically.
Ordering in CoPt-CrPt and CoPt-MnPt Alloys
j. c. woolley, j. h. phillips and j. a. clark, J. Less-Common Metals, 1964, 6, (6), 461-471
Ordering effects in the Co-Cr-Pt system were studied by taking CoPt-CrPt alloys with equal increments of composition and determining lattice parameter values for ordered and disordered structures, and by X-ray methods estimating ordering temperatures and the type of ordering reaction. Similar studies on the Co-Mn-Pt system showed that alloys containing 20 at.% Mn do not have the CoPt-type ordering reaction.
Relations between the Structures of Phases in the System Platinum-Molybdenum
h. p. rooksby and b. lewis, J. Less-Common Metals, 1964, 6, (6), 451-460
Crystal structure changes occurred in Pt-coated Mo wire above 800°C as Mo diffused into Pt, forming successively the intermediate phases [β-Pt3Mo, γ-Pt2Mo, δ-Pt3Mo2 and ε-PtMo3.
The System Platinum-Aluminium
r. huch and w. klemm, Z. anorg. allgem. Chem., 1964, 329, (1-6), 123-135
X-ray and thermal analyses revealed the inter-metallic phases ‘PtAl4’, PtAl3, PtAl2, Pt2Al3, PtAl, Pt3Al2, Pt5Al3, Pt3Al and Pt3Al3. Pt2Al3 has hexagonal Ni2Al3-type structure with a = 4.209Å, c = 10.35Å. Pt5Al3 has rhombic Th5Ge3 structure with a=5.4l, b = 10.70, c = 3-95.
Pt3Al has cubic Cu3Au-type structure with a = 3.876 Å. Molecular volumes are discussed. Pt-rich alloys contract strongly; Al-rich alloys dilate strongly.
Lattice Constants and Thermodynamic Parameters of the Hydrogen-Platinum-Palladium and Deuterium-Platinum-Palladium Systems
a. maeland and t. b. flanagan, J. Phys. Chem., 1964, 68, (6), 1419-1426
Absorption isotherms at 25°C and thermodynamic parameters of D2 absorption were measured foro,2.79, 5.73, 8.80 and 12.03% Pt-Pd alloys. The effect of D2 content on the relative resistance of the alloys was compared with data from the H-Pt-Pd system.
The Palladium-Uranium Phase Diagram up to 25 at.% Uranium
g.p. pells, J. Inst. Metals, 1964, 92, (12), 416-418
X-ray diffraction and metallographic studies of U-Pd alloys with <25 at.% U showed two eutectoidal transformations: at 13.5at.% U, 694°C giving Pd17U8 and Pd11U2; at 15.5 at.% U, 1015°C giving PD11U2,; and Pd5U2. Pd5U formed peritectically at 18.8 at.% U, 1440°C. Pdi17U2, Pdl1U2 and Pd5U2 have non-cubic structure. They and Pd4U, formed peritectically at 21 at.% U, 1525°C with Cu3Au-type structure, all have small solubility ranges. Pd3U was detected above 20.8 at.%U. The variation of electrical resistivity with composition was determined up to 15.5 at.% U.
Melting Equilibrium in the Ternary System Cobalt-Manganese-Palladium
g. zwingmann, Metall, 1964, 18, (7), 708-710
Thermal analysis and metallographic examination of the Co-Mn-Pd system showed that the two Mn-Pd eutectics are joined by a continuous series of eutectics in the ternary region with temperature minima at 1140 and 1210°C on either side of a maximum at 1330°C. Less than 3% Co is soluble in β-phase alloys.
The Thermal Decomposition of Rhodium (III) Oxide and the Influence on Alloying with Platinum and Palladium
n. g. schmahl and e. minzl, Z. phys. Chem. (Frankfurt), 1964, 41, (1-2), 78-96
The decomposition of Rh2O3 at 900-1100°C was studied. RhO and Rh2O were not detected but RhO2 evaporated from Rh. The temperature dependence of the layer on Rh affected by O2 was studied. Pt powder additions to Rh2O3 showed that the O2-pressure from decomposition was a function of Rh-Pt alloy composition but was only slightly temperature-dependent. Results were discussed in relation to NH3-oxidation at Rh-Pt contacts and to thermocouple oxidation. The Rh-Pd-O2 system was also tested.
The Constitution Diagram Tantalum-Rhodium
b.c. giessen, h. ibach and n.j. grant, Trans. Met. Soc. A.I.M.E., 1964, 230, (1), 113-122
The system was studied by X-ray and metallographic methods and by thermal analysis. Five intermediate phases were detected: σ, tetragonal FeCr-type; α1 orthorhombic; α2, orthorhombic Co2Si-type; α3, structure unknown, α-TaRh3, cubic AuCu3-type. σ, α1 α2 and α3 melt peritectically and α -TaRh3 has a maximum melting point.
New Intermediate Phases in Systems of Nb or Ta with Rh, Ir, Pd or Pt
b. c. giessen and n. j. grant, Acta Cryst., 1964, 17, (5), 615-616
The existence of 18 new phases in these systems is reported, together with data on their crystal structures.
The Osmium-Iridium Equilibrium Diagram
r. d. reiswig and j. m. dickinson, Trans. Met. Soc. A.I.M.E., 1964, 230, (3), 469-472
The Os-Ir equilibrium diagram exhibits a peritectic temperature of about 2660°C with a miscibility gap between 42 and 63 wt.% Os. Two-phase specimens near the boundaries of the miscibility gap led to the discovery of Widmans-taetten figures and accounted for a previously suspected transformation. (7 figs.)
The Ruthenium-Iridium Alloys
e. raub,Z. Metallkunde, 1964, 55, (6), 316-319
The high mutual solubility of Ru and Ir was indicated by X-ray and metallographic studies, with the binary phase at 2000°C extending from 46 to52 at.% Ir. Ir-rich solid solutions showed greater temperature dependence of the solubility curve. Completely homogeneous supersaturated alloys cannot be obtained by cooling from high temperatures. Secondary spectral bands for Ru-rich phase alloyed with 55 at.% Ir are due to spinodal decomposition to an extent depending on the treatment.
The Palladium-Iridium Alloys
e. raub and e. roschel, Ibid., 320-321
X-ray and metallographic studies confirmed that Pd-Ir solid solutions do not form from the melt by a peritectic reaction. A continuous series of solid solutions exists from the miscibility gap to the liquid state.
The Structure of Solid Iron-Iridium Alloys
e. raub, o. loebich and h. beeskow, Ibid., (7),367-370
An h.c.p. phase in the Fe-Ir system was found by X-ray diffraction. Transformation occurred at about 470°C, 19 at.% Ir. Maximum formation temperature was 625°C, 38 at.% Ir. The phase showed a wide range of homogeneity.
The Constitution Diagram Tungsten-Ruthenium
e. j. rapperport and m. f. smith, Trans. Met. Soc. A.I.M.E., 1964, 230, (1), 6-11
The system was studied by X-ray and metallographic methods and by electron microprobe analysis. Terminal solid solutions have 23 at.% maximum solubility of Ru in W at 2300°C and 48at.% W in Ru at 2205°C. Solubilities decrease at lower temperatures, a-phase W3Ru2 forms peritectically at 2300°C and decomposes eutectoid-ally at 1667°C to a-W and p-Ru. An eutectic occurs at 45at.% Ru, 2205°C and yields σ-phase and (β-Ru.
Vapour Pressures of Ruthenium and Osmium
n. j. carrera, r. f. walker and e. r. plante, J. Res. Nat. Bur. Stds., Pt. A, 1964, 68A, (3), 325-330
A modified Langmuir method with a micro-balance technique measured the vapour pressures of Ru and Os and their heats of sublimation at 298°K. For Ru: log Patm=7-500 - 32,769/T at 1940-2377°K ΔH°5(298)=156.1 ± 1.5 kcal/mole; the boiling point is 4150±100°K. For Os: log Patm =7.484 -39=880/T at 2157 - 2592°K; AFTS (298) =189.0 ± 1.4 kcal/mole; b.p. is 5300 ±100°K.
Some Experiments on the Osmium-Carbon and Ruthenium-Carbon Systems
b. jeantet and a. g. knapton, Planseeber. Pulver- met., 1964, 12, (1), 12-18.
Attempts to prepare carbides of Os and Ru were unsuccessful. Doubt is cast on the report of their preparation by Kempter and Nadler.
Mechanical Properties of Several Nickel-Platinum-Group Metal Alloys
w. l. phillips, Trans. Met. Soc, A.I.M.E., 1964, 230, (3) 526-529
Tension tests at 25, 500, 800 and 1000 °C and stress-rupture tests at 650 and 800°C on 0.5, 2.0 and 6.0 at.% Os-, Pd-, Ru-, and Rh-Ni alloys showed that room- and elevated-temperature tensile strengths, as well as stress-rupture life, increase at the same Pt-metal content in the order Pd, Rh, Ru, Os. Ductility decreases with increasing Pt-metal content or with temperature at a given concentration of Pt-metal. These results are discussed in relation to solid-solution theory.
Specific Heats and Magnetic Susceptibility of Superconducting Binary Complex Phases of Transition Metals
e. bucher, f. heinigerand j. muller, Phys. kondens. Materie, 1964, 2, (3), 210-240
Measurements are described and results presented for 15 phases with σ and χ-structures both in the normal and in the superconducting states. Among the alloys are phases from the systems Nb-Os, Nb-Rh, Nb-Ir, Nb-Pd, Nb-Pt, Mo-Ru, Mo-Os and W-Ir.
A Simple Method for Determining the Cleanliness of a Platinum Anode
s. schuldiner and t. b. warner, j. Phys. Chem., 1964, 68, (5), 1223-1224
The linearity of the voltage-time curve in the atomic O adsorption region can serve as a reliable index of electrode cleanliness. Oscilloscope traces illustrate this for a Pt bead electrode in 1M H2SO4. The true area of the clean Pt electrode can be derived also.
The Relative Electrocatalytic Activity of Noble Metals in the Oxidation of Ethylene
h. dahms and j. o’m. bockris, J. Electrochem. Soc., 1964, III,(6), 728-736
Complete anodic oxidation of C2H4 to CO2 occurred at Pt, Ir, and Rh electrodes but on Au and Pd the main products were aldehydes and acetone with hardly any CO2. The electrolyte was 1 M H2SO4 at 80°C and the cell is described. The orders of reactivity for the two groups of electro-catalysts were Pt>Rh>Ir and Pd>Au.
The Mechanism of the Electro-Oxidation of Acetylene on Platinum
j. w. johnson, h. wroblowa and j. o’m. bockris, Ibid., (7), 863-870
Parameters for C2H2 oxidation on platinised Pt gauze electrodes were determined at 80°C in solutions of H2SO4.+ Na2SO4 and NaOH of constant ionic strength. Reaction rates depended on potential, pH, and Pc2H2- Coulombic efficiency, measured as CO2 production in acidic solutions and C2H2 production in alkaline solutions, was 100 ±1% in acid, 95 ±5% in alkali. Heats of activation and passivation effects were also measured.
Hydrogenation of Ethylene at Palladised Palladium and Platinised Platinum Electrodes
l.d. burke, c. kemball and f. a. lewis, Trans. Faraday Soc, 1964, 60, (5), 913-918
Hydrogenation of Acetylene at Palladised Palladium and Platinised Platinum Electrodes
l. d. burke, f. a. lewis and c. kemball, Ibid., 919-929
Electrocatalytic hydrogenation of C2H4 and of C2H2 dissolved in aqueous solutions of HC1 and NaOH was measured at 25and 50°C and results compared, using H2 preadsorbed on Pd as well as electrolytic H2. C2H6 was produced from C2H4 and C2H4 and C2H4 were produced from C2H2, as shown by gas chromatography. Electrolytic H2 was most efficient with C2H2 at palladised Pd electrodes in alkaline solution. C2H4 was reduced to C2H6 at a rate dependent on olefin diffusion through the Brunner-Nernst boundary layer on the electrode surface.
ELECTRODEPOSITION AND SURFACE COATINGS
Vapour Deposition of Pure Ruthenium Metal from Ruthenocene
d, e. trent, b. paris and h. h. krause, Inorg. Chem., 1964, 3, (7), 1057-1058 99.99%
pure Ru film was deposited from bis-(cyclopentadienyl) ruthenium at 595°C in a stream of H2 on the inside of a Vycor tube in which the reaction took place. Ruthenocene, which has an appreciable vapour pressure at relatively low temperatures, was carried by the gas stream to the point of deposition. A non-uniform deposit formed on the graphite susceptor used for heating.
LABORATORY APPARATUS AND TECHNIQUE
The Weight Constancy of Rhodium and Iridium Vessels during Analytical Operations
g. reinacher, Werkstoffe u. Korrosion, 1964, 15, (6), 451-457
Rh and Ir crucibles plated with Pt and unplated were tested in various analytical operations. Unplated vessels were tarnished after heating at 800-1000°C. Rh had gained some weight at 1000°C but Ir tended to lose it by 900°C. Both resisted attack by HNO3 and HC1 better than Pt. KHSO4 fusion at 400°C had no effect but, at 600°C, Rh was attacked. Rh resisted attack during NaHCO3 fusion better than Ir. Vessels covered with Pt had the usual good resistance of Pt.
Chemisorption and Surface Chemistry of Ethylene on Supported Platinum Catalysts
p. j. lucchesi, j. l. carter and j. h. sinfelt, J. Am. Chem. Soc, 1964, 86, (8), 1494-1497
Comparisons of C2H4 chemisorption and surface chemistry on A12O3 ando.6and i.owt.% Pt/Al2O3 catalysts showed that identical species formed on them with different reactivities. H, treatment removed adsorbed species more easily from Pt/Al2O3 than from A12O3, suggesting that migration of reactive species between Pt and A12O3 centres may be an important mechanism. Desorp-tion products of this treatment were mainly C2H6 and n -C4H10 at 100-150cC, with more CH4 and C3H8 at higher temperatures.
Reactions of Some C9 Aromatics on Platinum-Alumina Catalysts
f. e. shephard and j. j. rooney, jf. Catalysis, 1964, 3, (2), 129-144
When n -propylbenzene, °C03C9-methylstyrene, and o-ethyltoluene reacted with excess H2 over Pt/γ-Al2O3 in the range 337 to 490°C and when indane reacted at 337,392, and434°C, equilibrium between olefins and corresponding paraffins by hydrogenation and dehydrogenation occurred rapidly. Dehydrocyclisation of the substituted benzenes gave indane, the C5 ring of which was hydrogenolysed to give the isomeric alkylbenzene without reaching equilibrium. Product analyses and tests on catalysts with varying composition, sintering and thiophene poisoning showed that the reactions depended on the state of the supported Pt.
Hydrogenolysis of Cyclopentane Hydrocarbons in the Presence of Platinum on Alumina
i. v. gostunskaya, ho chin-fyn and b. a.kazanskii, Izv. Akad. Nauk. S.S.S.R., Ser. Khim., 1964, (5), 832-836
The hydrogenolysis of cyclopentane, methyl-cyclopentane, and ethylcyclopentane was studied using 9.8% Pt/Al2O3 catalyst at 230 to 280°C. Apparent activation energies were determined; for the alkylcyclopentanes these were lower than for cyclopentane itself. The products were linear and branched alkanes.
Hydrogenolysis of Cyclopentane Hydrocarbons in the Presence of Platinum Supported on Silica Gel
Ibid., (6), 1073-1077
The apparent activation energies of hydrogenolysis of methyl- and ethylcyclopentanes on Pt/SiO2 at 210-260°C are less than that for cyclopentane. The deactivating effect of alkyl groups on 5-membered rings was clearly apparent.
Catalytic Conversion of Cyclopentane and its Homologues in the Presence of Platinum Supported on Aluminosilicate
Conversions over Pt/SiO2-Al2O3 were studied at atmospheric pressure in the200-270°C range. At 200-235°C hydrogenolysis of cyclopentane and methylcyclopentane was selective and the apparent activation energy of the reaction could be calculated. Ethylcyclopentane was not selectively hydrogenolysed but most of it was isomerised to methylcyclohexane. The temperature coefficient of isomerisation was less than that of dehydrogenation of methylcyclohexane. At 230-270°C, there was less hydrogenolysis of ethylcyclopentane as the temperature rose.
Desorption of Hydrogen from Platinum Catalysts
y. kubokawa, s. takashima and o. toyama, J. Phys. Chem., 1964, 68, (5), 1244-1245
1.15 wt.% Pt/Al2O3, Pt/SiO2, and Pt black catalysts all have nearly the same minimum and maximum heats of adsorption and exhibit two types of adsorption of H2. The activation energy of desorption E for 1.15wt.% Pt/Al2O3 was almost constant at 10kcal/mole below room temperature and rose to 23 kcal/mole at about 300°C. H2 was chemisorbed on the catalyst at 300°C, the catalyst was cooled in H2 to —52°C and then heated in stages. At — 52°C the H:Pt ratio was nearly 1, indicating high Pt dispersion.
On the Hydrogenation of Dimethylene-cyclobutane
ya. m. slobodin and a. p. khitrov, Zh. Obshch. Khim., 1964, 34, (6), 1727-1728
During the hydrogenation over PtO3 of 1,2-dimethylenecyclobutane, cis- and trans-1,2-di- methylcyclobutane were formed. Similar hydrogenation of 1,3-dimethylenecyclobutane caused some breaking of the 4-membered ring and the formation of 2-methylpentane.
Catalytic Reduction of Aromatic Nitrocompounds. XTY. Reduction of Nitrobenzene on Platinum Black
v. p. shmonina, Ibid., 2020-2026
Nitrobenzene was reduced over Pt black in tests in the range o-50°C, 40-80% C2H5OH solution. Addition of 0.1 N KOH or 0.1N HCl to the solution retarded the reaction.
Tritium-labelling of Natural Products
r. maurer, m. wenzel and p. karlson, Nature, 1964, 202, (4935). 896-898
Tritiation of pure digitogenin by the charcoal adsorption method combined with Pt catalysis was almost 100 times faster than by the Wilzbach technique at room temperature and gave specific activities three times better than with charcoal adsorption alone. Digitogenin in CeH6/C2H5OH was shaken with 10% Pt/C, exposed to 2cT2 for 7.5h,separated and tested.
Shifts of Double Bonds in Hexenes in the Presence of Platinum Catalysts
n. b. dobroserdova, g. s. bakhmet’eva, a. i. leonova, i. v. gostunskaya and b. a. kazanskii, Neftekhimiya, 1964, 4, (2), 215-218
Catalytic isomerisation under partial hydrogenation conditions by Pt black and Pt/C was studied on hexenes with double bonds in the α-position (hexene-1, 2-, 3- and 4-methylpentene-1, 2,3-dimethylbutene-l). Different forms of H2 are believed to cause double-bond transfer and hydrogenation. Isomerisation increases when more H2 dissolves in the catalyst metal; hence Pd is more active than Pt.
Catalytic Conversions of Spiro-(5, 6)-dode-cane on a Platinum Catalyst
n. v. elagina, a. k. mirzaeva, kh. e. sterin, a. v. bobrov and b. a. kazanskii, Ibid., 241-245
66% of spiro-(5, 6)-dodecane was converted over Pt/C at 320°C. C-C bond rupture occurred at the quaternary C atom, followed by isomerisation and dehydrogenation. Principal product was diphenyl, produced by dehydrogenation via dicyclohexyl. Minor products were n -hexylbenzenc, benz-cycloheptane and 1, 2-benzbicyclo-(o,3,3)-octane.
On a Series of Hydrogen Additions to Double Bonds of 4-Vinylcyclohexane-l on Pt- and Ni Catalysts
l. kh. freidlin, a. f. plate, i. f. zhukova and b. a. belinkova, Ibid., (3), 382-385
When 4-vinylcyclohexene-I was hydrogenated over Pt/C and Raney Ni the first double bond affected was that outside the ring. Product ratios of 4-ethylcyclohexene-I and ethylcyclohexane were ~3:1 on Pt/C and ~9:1 on Raney Ni.
Catalytic Conversion of 1,1-Dimethyl-cyclo-hexane on Platinum Catalyst at Elevated Temperature and Hydrogen Pressure
s. i. khromov, d. chultem and e. s. balenkova, Ibid., 413-416
Toluene was the principal product of conversion of 1, I-dimethylcyclohexane over 1% Pt/C at 320 and460°C, and 20 atm H2. Meta- and ortho-xylene were the chief products over 1% Pt/Al2O3 at 400-460°C, and 20 atm H2.
Catalytic Conversion of n -Amylbenzene on Platinum Catalyst
a. k. mirzaeva, n. v. elagina, kh. e. sterin, a. v. bobrov and b. a. kazanskii, Ibid., 417-420
«-Amylbenzene was dehydrogenated over 15 % Pt/C at 320°C and converted into α-ethylindane, α-methylnaphthalene, β-methylnaphthalene and naphthalene, which were determined by chromatography.
Olefin Isomerisation with Noble Metal Catalysts
j. falbe and f. korte, Brennstoff-Chem., 1964, 45, (4), 103-1051
Pd/C and Pt/C were shown to be good catalysts for the isomerisation of butene-2 and pentene-2 to mixtures of the corresponding olefin isomers. The amount of isomerisation of pentene-2 using RhCI3 and IrCl3 as catalysts during the formation of CO-compounds of Rh and Ir was also studied.
Stereoisomeric Conversion of Individual cis- and tra/»s-3-Methylpentene-2 in Liquid Phase Catalytic Hydrogenation Conditions
i. v. gostunskaya, a. i. leonova and b. a. kazanskii, Neftekhimiya, 1964, 4, (3), 379-381
Isomerisation of each of cis- and trans-3-methyl-pentene-2 in alcoholic solution increased with catalysts in the order Pt<Ni<Pd. Low boiling-point isomers reacted faster than those of higher boiling-point. Minor products included 3-methylpentane and 2-ethylbutene-I.
Homogeneous Catalysis. I. Double Bond Migration in n -Olefins, Catalysed by Group Vin Metal Complexes
j. f. harrod and a. j. chalk, J. Am. Chem. Soc, 1964, 86, (9), 1776-1779
Catalysis of double bond migration in linear olefins by Pt metal complexes yielded equilibrium distribution of isomers. The effects on reaction rates, cocatalysts, and isomer distribution of the metal ions, their oxidation state, and their ligand attachments were studied. When suitable cocatalysts were present, I-hexene was isomerised by dichlorobis(ethylene)dichlorodiplatinum(II), RhCls.3H2O isomerised I-hexene, cis- and trans- 2-heptene, Pd(II) complexes catalysed similar reactions until reduced to Pd, and IrCl3 behaved like Pt(II).
On the Mechanism of Hydrogenation of Dienes with Linked Double Bonds on Palladium Catalyst
l. kh. freidlin and e. f. litvin, Neftekhimiya, 1964, 4, (3), 374-378
The composition of olefins derived from hydrogenation over Pd black of isoprene, 2,3-dimethyl-butadiene, 3-methylbutene-I, and 2,3-dimethyl-butene-I depended on the point of H2 addition or on the amount of isomerisation before desorption at the catalyst. Olefines produced were not isomerised in the presence of the diene.
Study of the Partial Catalytic Hydrogenation of Nitrocyclohexene
p. guyer and h. j. merz, Chimia, 1964, 18, (4), 144-146
When nitrocyclohexene was hydrogenated in the presence of Pd/C, the double bond was attacked 7.8 times more quickly than with Pt/C, but with Pt/C the NO 2 was reduced 1.8 times more quickly than with Pd/C. Hydrogenation of nitrocyclohexane with Pd/C therefore leads principally to cyclohexylhydroxylamine but with Pt/C the reaction can be selective for cyclo-hexanonoxime.
The Activation on Palladous Chloride by Metal Ions in the Homogeneous Hydrogenation of Ethyl Crotonate
e. b. maxted and s. m. ismaiL f.Chem. Soc, 1964, (May), 1750-1752
10_4M aqueous solutions of acetates of Cu, Ni, Zn, Ag, Hg, Cd, Na and Ca, and of chlorides of Cu, Ni, Co, Al, Mg, Ce and Cr were tested as promoters of 1% PdCl2 solution as catalyst for the hydrogenation of ethyl crotonate. Activation was successful at as low as 30°C, I atm. Na+ was most active, increasing the activity of PdCl2 by up to seven times. Decrease in activity and the precipitation of Pd as the reaction proceeded indicated a homogeneous reaction in which individual Pd atoms in PdCl2 are catalysts.
Investigations of the Hydrogenation Reactions of Olefins and Dienes in the Presence of Rhodium Black
l. kh. freidlin, e. f. litvin and l. m. krylova, Neftekhimiya, 1964, 4, (2), 185-189
Rh black catalysed liquid phase hydrogenations ofdienes, (cis -piperylene, isoprene and 2,3-dimethylbutadiene) and defines (pentene-I, cis- and fram-pentene-2, 3-methylbutene-I and 2,3-dimethylbutene-I) with selectivity close to that of Pt black and isomerisation properties (double-bond transfer and cis-trans isomerisation) intermediate to those of Pd and Pt black.
Synthesis of High-Molecular-weight Paraffins from Carbon Monoxide in Aqueous Suspensions of Ruthenium
h. kolbel, w. h. e. muller and h. hammer, Makromol. Chem., 1964, 70, 1-11
Paraffin waxes with melting points up to 131°C and mol. wt. up to 7000 were synthesised by feeding CO into an aqueous suspension of finely divided, metallic Ru at 75-200 atm, 150-260°C. ΔH = 57.2 kcal/mole wax. 100% CO-conversion was possible. CO2, CH4 and H2 were byproducts. H2O acted as reactant, suspension liquid, coolant and heat transfer medium.
Polymethylene from Carbon Monoxide and Hydrogen
h. pichler, b. firnhaber, d. kioussis and a. dawallu, Ibid., 1964, 70, 12-22
Polymethylene, similar to low-pressure polyethylene, with mol. wt. up to 100,000+ was synthesised from CO and H2 in the presence of RuO2 at high pressures below 140°C.
Hydrogenation and Hydrogenolysis. VIII. The Ruthenium-catalysed Hydrogenation of Aromatic Compounds Containing C-0 Linkage to be Easily Hydrogenolysed
y. takagi, t. naito and s. nishimura, Bull. Chem. Soc. Japan, 1964, 37, (4), 585-587
RuOs successfully catalysed hydrogenations of compounds in which it was desired to avoid hydrogenolysis of C-O linkages. Reactions were rapid and gave good yields of the corresponding alcohols or ethers, although slightly more hydrogenolysis occurred than with Rh and (7:3) Rh-Pt oxides as catalysts, perhaps because the latter operated at lower temperatures. Solvents were not used, except for C2H5OH or HaO with benzyl alcohol, but CH3COOH additives were used to neutralise alkaline traces in RuO2. Reactions took place at 95-100°C, 80-100 kg/cm3 H2.
Catalysts for Selective Hydrogenation of Soybean Oil. II. Commercial Catalysts
c. h. riesz and h. s. weber, J. Am. Oil Chem. Soc, 1964, 41, (6), 400-403
Linolenic components of soybean oil are hydrogenated with high selectivity by commercial Pt, Pd, and Rh catalysts. Many of the latter had selectivities SL of 2.4 to 2.7, but of the Ni catalysts tested only Raney Ni had SL>2.0. The Pt metal catalysts isomerised the linolenic components to the trans -from to the extent 7.8 - 15.4% but Ni caused only 5.2 - 7.4% isomerisation.
Electrochemical Oxidation of Methanol in Fuel Cells
m. prigent, Rev. Inst. Fr. Petrole, 1964, 19, (6), 1-54
The complete oxidation of CH3OH is affected by the electrode potential, reactant concentration, and the state of the catalyst electrode. Studies of these parameters showed that Pt black electrodes gave the best results. Electrode properties depended on the weight of Pt deposit, on the deposition potential, and on additives. (83 references).
Structure and Activity of a Type of Sintered Electrode for Gas Cells
r. coffre, g. feuillade and b. michel, Ann. Radioelect., 1964, 18, (74), 40-59
The theoretical basis of sintered fuel cell electrodes is expounded and the efficiency, activation processes, and passivation and ageing of oxygen and hydrogen electrodes are described. Au is used as catalyst on the Ni oxygen electrodes and Pd or Pt on the Ni alloy hydrogen electrodes. The latter age as Pd or Pt recrystallises.
The H2-C12 Fuel Cell. A Study of the Prospects of Power Recovery in Plants for Electrolytic Manufacture of Chlorine and Soda
g. bianchi and c. traini, Chim. e Ind., 1964, 46, (4), 363-370 (English summary)
The capillary-inhibition H2 electrode and the flowing-electrolyte Cl2 electrode were porous graphite discs activated with Pt or Ir. The electrolyte was HC1 solution. Ionisation occurred at room temperature and 1000 A/m2 was obtained with 0.5 V at the H2 electrode. 1000 A/m2 was reached with 0.2 V at the Cl2 electrode. Pure H2 and dilute Cl2 from the Deacon process could yield 500 A/m2 at 0.88 V working voltage at room temperature and pressure. This represents 25% power recovery from the electrolysis but actual power recovery is less because some is used in auxiliary process equipment.
Electrochemical Oxidation of Hydrocarbons
r. jasinski, j. huff, s. tomter and l. swette, Ber. Bunsengesell. Phys. Chem., 1964, 68, (4), 400-404
Pt/Ta screens were used in fuel cell oxidation tests at 70°C with 30% H2SO4 electrolyte. Current densities of 35 mA/cm2 with CH3OH fuel and 80 mA/cm2 with HCOOH were achieved, both at 0.3 V. Pt black mixed with a Teflon dispersion and spread over a Ta screen was used in similar tests on CH4, C3H8, C3H6, n -C4H10 and iso -C4H10, with O2 as oxidant and 85% H3PO4 electrolyte. Such cells generated 40 mA/cm2 at 0.37 V, 150°C using C3H8 or n -C4H10 fuels.