ABSTRACTS: January 1983
ABSTRACTS: January 1983
of current literature on the platinum metals and their alloys
The Chemistry of Ruthenium, Osmium, Rhodium, Iridium, Palladium and Platinum in the Higher Oxidation States
d. j. gulliver and w. levason, Coord. Chem. Rev., 1982, 46, 1–127
A review is given of papers on the chemistry of platinum group metals in the high oxidation state which is a formal oxidation state of M(IV) or above. The emphasis is placed upon isolated compounds and coverage of solution chemistry is restricted to well-defined species. (1,131 Refs.)
Hydrogen-Induced Disruption of Oxygen-Doped Platinum Coatings on Glass Microspheres
w. l. ping and s. f. meyer, J. Vac. Sci. Technol., 1982, 21, 2, 689–694
Sputter deposited Pt coatings on glass microspheres were severely disrupted after a deuterium-tritium mix was permeated into the hollow spheres at high temperature and pressure. The disruptions were characterised. They suggested that H2 gas was occluded in the Pt rift structure during the high-pressure filling. Subsequent H2 pressure release expanded the occluded gas; because diffusion rates were too low to relieve the stress concentrations produced, the Pt coating delaminated along weakly bound interfaces.
Sound Absorption Properties of Platinum Catalysed Silicone RTV Foam
c. l. lee and s. spells, J. Cell. Plast., 1982, 18, (3), 174–177
Pt catalysed silicone RTV foam was examined for its sound absorption properties. It was found to be as good or even better than existing commercial acoustic foams if its density is decreased to 5–6 lb/ft3. Incorporating C black into the foam gives an improved sound absorption in a certain frequency range and flame retardancy.
Reduced Cu-Cr Mixing and Reduced Pt-Cu Interdiffusion by Oxygen in Cu/Cr and Pt/Cu/Cr Thin Films
c.-a. chang, J. Appl. Phys., 1982, 53, (10), 7092–7094
The effects of O2 on the Pt-Cu and Cu-Cr interdiffusion was studied using Cu/Cr and Pt/Cu/Cr thin film structures. Both processes were reduced by O2, in agreement with the predicted effects of O2 by the surface potential model. The Pt-Cu interactions were an example of competing ambient effects dominated by the more electronegative species Pt.
Detection of Interstitial Hydrogen on Pt/TiO2 by Means of Conductivity Measurements
h. zupei, c. yixuan, l. huiqing, y. fengyun and w. hongli, J. Catal. (Dalian, China), 1982, 2, (2), 132–135
A large instantaneous change in conductivity of Pt/TiO2 in H2 was observed at room temperature. Current carriers for different forms of TiO2 during thermal treatment in H2 were produced in different modes. The interaction between H2 and Pt/TiO2 is discussed. It is suggested that H2 is activated and dissociated to H atoms on Pt clusters, it then spills over the TiO2 as interstitial H which is then ionised and causes the jump in conductivity
Effects of Ion-Implantation-Induced Damages and Impurity on Platinum Silicide Formation
y. mashiko, h. koyama, s. kawazu and t. kashiwaki, J. Appl. Phys., 1982, 53, (9), 6144–6147
The effects of damages and impurities on the formation of Pt silicide introduced into polycrystalline substrate by ion implantation prior to preparation of metal layer, were studied by spectroscopy. A formation of irregular and nonplanar structure at the Pt silicide/Si interface was observed which was caused by damage.
Alloying Effects of Palladium. 1966-July, 1982 (Citations from the Metals Abstracts Data Base)
National Technical Information Service, Springfield, VA, PB82–871823, July 1982, pp. 217
A review is given of alloying effects of Pd, and topics include alloying elements, magnetic and physical properties, temperature and pressure effects and corrosion resistance. Mechanical and surface properties, metallic glasses, impurity and composition effects, Curie temperature and superconductivity are included. (283 Refs.)
Studies of the Structural Diagrams of Cu-Pd-S and Ni-Pd-S
g. n. zviadadze, s. f. gulianitskaia, n. m. pavliuchenko and n. v. blagoveshchenskaia, Izv. Akad. Nauk. SSSR, Met., 1982, (5), 53–56
Studies were made of the interaction of Pd with Cu sulphides, and partial structural diagrams were constructed for Cu-Pd-S and Ni-Pd-S systems containing ≤ 50 mole%S. In both studied systems, Pd was found in the form of solid solutions with Ni or Cu and also as sulphides PdS and Pd4S with dissolved Ni and Cu. Interaction of Pd with Cu sulphides was more active than with Ni sulphides.
Synthesis and Properties of Phases in La2O3-PdO
b. g. kakhan, v. b. lazerev and i. s. shaplygin, Zh. Neorg. Khim., 1982, 27, (8), 2090–2093
Studies of oxide phases in the La2O3/PdO system, prepared by heating the La2O3 and Pd (C4N2-H7O2) oxides in air at 500−810°C, showed the formation of La2PdO4 and La2Pd2O5. Crystal structure studies showed that the lattice parameters of La2PdO4 are a=4.055 and c=12.62 Å, and of La2Pd2O5 are a=6.686 and c=5.616 Å.
Bulk Formation of a Metallic Glass: Pd40Ni40P20
a. j. drehman, a. c. greer and d. turnbull, Appl. Phys. Lett., 1982, 41, (8), 716–717
Molten spheroids of Pd40Ni40P20 under a vacuum of 10−6 torr were slowly cooled at 1.4 K/s on a fused SiO2 surface to a form which was glassy except for some superficial crystallinity, of less than 0.5% by volume. Crystallisation was eliminated by surface etching the specimens followed by heating and cooling cycles.
An X-Ray Study of Domain Structure and Stress in Pd2Si Films at Pd-Si Interfaces
h. chen, g. e. white and s. r. stock, Thin Solid Films, 1982, 93, (1/2), 161–169
The domain structures of Pd and Pd2Si, as well as their crystallographic relationship to the Si substrates, were determined on Si(111) and Si(100) samples by mapping X-ray diffraction pole figures. Elastic and/or plastic deformation in the substrates caused by silicide formation were measured. The stresses in the silicide films were determined from the bending of the Si substrates using X-ray diffraction.
The Structures and Properties of Some Rh0.92−xBxSi0.08Metallic Glasses
a. williams, m. mehra and w. i. johnson, J. Phys. F, 1982, 12, (9), 1861–1868
Rh-based metallic glasses were produced with >40 at.% metalloids (Si and B). X-ray diffraction studies on Rh0.92−xBxSi0.08 metallic glasses, with x=0.22, 0.27 and 0.32 were performed and mechanical, electrical and thermal analysis data are given. The structural studies showed that this system undergoes great changes at short-range with increasing B concentration.
Thermal Stability of Iridium Chlorides
i. m. sinitsin, v. v. borisov and a. s. kozlov, Zh. Neorg. Khim., 1982, 27, (9), 2322–2328
The thermal stability of IrCl3, K3[IrCl6], K2[IrCl6].H2O, K3[Ir(H2O)Cl5] and K4[Ir2Cl10] was studied in air, Ar and Cl2. Chemical and phase conversions occurring during chlorination of Ir in the presence of KCl were also investigated. High-temperature X-ray phase analysis of basic intermediate products of thermal dissociation of K3[IrCl6] showed the existence of high temperature modification with reverse polymorphic transfer at 485°C.
Chemical Vapour Transport of Transition-Metal Oxides. II. Epitaxial Growth of RuO2, IrO2 and (Rui−x,Irx)O2 on TiO2
p. triggs, c. a. georg and f. lévy, Mater. Res. Bull., 1982, 17, (5), 671–679
Epitaxial growth of RuO2 and IrO2 has been performed by chemical vapour transport on TiO2 substrates. Two types of samples were found. The first showed epitaxial layers of the Ru and Ir oxides with orientations close to that of the substrate, and with low level interdiffusion of the components. The second shows no epitaxial growth but the incorporation of Ru and Ir into the substrate surface giving a brown colouration.
Synthesis and Properties of Platinum Metal Oxides of the Type MxPt3O4
r. d. shannon, t. e. gier, p. f. carcia, p. e. bierstedt, r. b. flippen and a. j. vega, Inorg. Chem., 1981, 21, (9), 3372–3382
Methods were developed for high yield syntheses of MxPt3O4 where M = Li, Na, Mg, Ca, Zn, Cd, Co and Ni. Vapour phase hydrolysis of chloride mixtures produces samples with surface areas of 10−40 m2/g and has yielded compositions HxPt3O4−yCly and NixPt3O4−yCly, probably the first example of insertion of H and Cl into the MxPt3O4 lattice. Plots of cell dimensions, a vs . x for NaxPt3O4, Cd3Pt3O4, MgxNayPt3O4, CoxNayPt3O4 and NixNayPt3O4 are given. Magnetic susceptibility and XPS data are given. Metallic conductivity in NaPt3O4, Ni0.25Pt3O4 and Li0.8Pt3O4 is consistent with short Pt–Pt bonds and conflicts with recent claims of semiconducting behaviour.
Disulfur and Diselenium Complexes of Rhodium and Iridium
a. p. ginsberg, w. e. lindsell, c. r. sprinkle, k. w. west and r. l. cohen, Inorg. Chem., 1982, 21, (10), 3666–3681
A review of Rh and Ir complexes which cleave S8 and Se8 rings to form complexes with the fragments is given. The syntheses are stated and the complexes formed are characterised. (79 Refs.)
Investigation on the Electrocatalytic Dehydrogenation of CHO-Compounds in Acidic Media via a Palladium Membrane
w. güther and w. wielstich, Electrochim. Acta, 1982, 27, (7), 811–816
The dehydrogenation of formic acid, formaldehyde and methanol was studied using a H2 diffusion membrane. The catalytic effect of Pt was followed via the electrodeposition of this electrocatalyst on one side of the Pd membrane.
Corrosion of Platinum Catalyst in Alkaline Solutions
v. s. bagotzky, e. i. khrushcheva, m. r. tarasevich and n. a. shumilova, J. Power Sources, 1982, 8, (243), 301–309
The corrosion behaviour, as affected by time and potential of Pt black in alkaline solution at 20 and 70°C has been studied. Over the range 0.85−1.37V Pt undergoes dissolution, the maximum corrosion rate being at 0.93−0.95V. With time the corrosion current decreases to 10−6−10−7 A/m2. When Pt passes into solution the complex ion [Pt(OH)6]2− is formed. The influence of Pt pretreatment on the corrosion rate was investigated, and Ba2+ ions were found to slow down the dissolution process, while Cl− ions increased its rate.
Preparation and Characterisation of a New Electrode of the Type Ti/PtOx.TiO2
ch. comninellis and e. plaitner, Oberflaeche-Surf., 1982, 23, (9), 315–318
The electrode Ti/PtOx. TiO2 in dilute HCl has been studied as a function of the relative composition of the two oxides thermally deposited at different temperatures. It has been found that the maximum for catalytic activity of the electrode for discharge of chlorine is at a ratio PtOx:TiO2 of 10:1.
An Investigation of the Hydrogen Permeation through the α/β Phase Palladium by the Electrochemical Method
y. sakamoto, m. kawachi and s. hirata, J. Jpn. Inst. Met., 1982, 46, (5), 530–537
The H2 permeation rate through annealed and cold rolled Pd foil under various current densities to form a region of co-existence of α -Pd and β -Pd phase hydride was measured at 299±1K by the electrochemical permeation method. The rate determining step for the permeation was examined as a H2-diffusion process in the remaining α -phase Pd of the matrix accompanying the α/β -Pd phase transformation. Adding H2SeO3 to the electrolyte for cathodic polarisation strongly inhibited the discharge step of H ions for both Pd specimens, but scarcely influenced the H permeation behaviour.
Cathodic H2 Gas Production through Pd Alloy Membrane Electrodes
t. shirogami and k. murata, Int. J. Hydrogen Energy, 1982, 7, (11), 877–882
A H2 permeable membrane electrode (HPME)-H2-NiOOH rechargeable cell was tested to aid development of a high performance H2-metal oxide cell. A 66.6wt.%Pd-13.4wt.%Ag-20wt.%Au alloy membrane with one surface covered with Pd-Pt black catalyst and the other with Pd black was used as one of the walls of the vessel. When the Pd-Pt catalysed electrolyte-facing surface is cathodically polarised in concentrated KOH solution, H atoms dissolve in the membrane by penetrating it and leave the other (palladised) surface as free H2.
Electrochemical Activity of Dispersed Palladium-Silver Alloys during Production and lonisation of Hydrogen
zh. l. vert, v. f. pavlova and i. p. tverdovskii, Electrokhimiya, 1982, 18, (8), 1055–1058
Electrochemical activity of Pd-Ag alloys was studied during ionisation and production of H2 from acidic and alkaline solutions by a polarisation method. Comparison was made of calculated current exchanges with constant values of the rate of hydrogenation of maleic acid on Pd-Ag alloys, and with electrochemical properties of solid Pd-Cu and Pd-Pt solutions.
Metal Oxide Anodes for Oxygen Evolution
h. tamura and c. iwakura, Int. J. Hydrogen Energy, 1982, 7, (11), 857–865
The kinetics of anodic dissolution and O2 evolution at a Ru electrode in acidic solution were studied. Hydrous and anhydrous RuO2 electrodes were prepared by heating hydrous RuO2 samples at 90−1000°C, and their anodic characteristics were studied in connection with their physical properties. The anodic characteristics of the Ti/RuO2 electrode, especially the cause of its activity loss during O2 evolution were studied.
Metallic Clusters in Solid Solutions of Ti1−xRuxO2 and Electrochemical Properties of Oxidised Ruthenium-Titanium Anodes
iu. e. roginskaia, b. sh. galiamov, i. d. belova, r. r. shifrina, v. b. kozhevnikov and v. i. bystrov, Electrokhimiya, 1982, 18, (10), 1327–1334
Spectroscopic and electrophysical studies of the structure of the active layer of oxidised Ru-Ti anodes and of RuxTi1−xO2 solid solutions showed the formation of elongated clusters with metallic properties at x<0.25 while at x<0.25 these agglomerate into infinite clusters. A strong interaction observed between the metallic components and TiO2 resulted in the occurrence of electronic density 3d-state in TiO2.
Photoelectrochemical Behavior of n-Si Electrodes Protected with Pt-Polypyrrole
t. skotheim, i.-g. petersson, o. inganäs and i. lundström, J. Electrochem. Soc., 1982, 129, (8), 1737–1741
Highly stable photoanodes based on single crystal n-Si protected with a thin coating of Pt and electrochemically grown polypyrrole films have been studied. A power conversion efficiency of 5.5% under illumination by a W halogen light occurred with an iodide/triiodide electrolyte. The cells are stable for several weeks. The junctions show almost ideal Schottky junction behaviour. (41 Refs.)
Photoassisted Water-Gas Shift Reaction on Platinized Titania. The Influence of Preparation Parameters
s.-m. fang, b.-h. chen and j. m. white, J. Phys. Chem., 1982, 86, (16), 3126–3130
The variation in the rate of the photoassisted water-gas shift reaction over Pt/TiO2, with changes in catalyst preparation were studied. The reaction rate: is independent of the Pt deposition method, is first order in light intensity, is independent of the chemical state or the Pt loading above 2wt.%, depends on reduction of the TiO2, and is strongly dependent on surface concentration of NaOH. It is concluded that with NaOH present, the rate limiting step is the reaction of photoproduced holes with surface OH− ions.
Photopotential Behaviour of Platinized TiO2 Particles
k. uosaki and h. kita, J. Electrochem. Soc., 1982, 129, (8), 1752–1753
The photoeffect of a Xe lamp on the potential of platinised TiO2 particle catalysts suspended in NaOH solution is reported. The potential does not exceed some steady value at which the rate of electron excitation equals that of electron consumption by the reaction with H2O plus the recombination. The steady potential is positive compared with the reversible H electrode potential, suggesting no H evolution at atmospheric pressure.
Excited-State Photoelectrochemical Cells for the Generation of H2 and O2 Based on
w. j. dressick, t. j. meyer, b. durham and d. p. rillema, Inorg. Chem., 1982, 21, (9), 3451–3458
Excited-state photoelectrochemical cells are described for the production of H2 or O2 (or I2) in aqueous solution. The cells are based on visible excitation of followed by oxidative quenching of the resultant charge-transfer excited state(s). In the H2 cell the quencher is paraquat. In the O2(or I2) cell, acts as a quencher. Descriptions of the functions of the quenchers, variation in photocurrents in the cells as functions of pH, quencher and scavenger concentration are given.
Photoelectrochemistry of in Basic Medium at SnO2 and Metal Electrodes
a. kirsch-de mesmaeker, j. nasielski and r. willem, Bull. Soc. Chim. Belg., 1982, 91, (9), 731–742
The effect of the pH on the photoelectrochemical behaviour of is examined at a highly doped SnO2 electrode. An important photocurrent increase from pH 11 to 13 is explained by the photochemical production of a long-lived reductant generated from . Photocurrent observations at metallic electrodes and the photogalvanic cell behaviour confirm this interpretation.
Photo-Induced Hydroxide Addition to Nitrosyl Group of Bis (2,2′-Bipyridine)-ChloronitrosyIruthenium(2+) in Aqueous Solution
a. sugimori, h. uchida, t. akiyama, m. mukaida and k. shimizu, Chem. Lett., 1982, (8), 1135–1138
A novel photoreactivity of [RuCI(bpy)2NO]2+ in aqueous solution at pH ≈ 5 by u.v. or solar light is reported. Hydroxide is added to a co-ordinating NO to give metastable [RuCl(bpy)2NO2H]+ which returns to [RuCl(bpy)2NO]2+ in the dark. The reaction gives a reversible change of H+ concentration. Quantum yields at various irradiation wavelengths are given.
ELECTRODEPOSITION AND SURFACE COATINGS
Deposition of Palladium from an Acid Electrolyte
f. simon and w. zilske, Galvanotechnik, 1982, 73, (9), 981–982
A new Pd bath is described from which coatings with low H content and low internal stresses can be deposited. The coatings have high corrosion resistance and wear resistance and can, in many cases, replace hard gold. A typical example of this is in the field of plug connections for low current technology. The Pd electrolyte contains 2−15 g/l Pd, 0.5−2 g/l Pd as a sulphite complex and 100 g/l acid concentration. The properties of the deposition and of the H content are discussed. A H:Pd ratio of 0.0004:1 can be achieved.
LABORATORY APPARATUS AND TECHNIQUE
On the Theory and Use of a New Fast-Response Dissolved Hydrogen Probe for Hydrogen Transfer Studies
b. andersson and t. berglin, Chem. Eng. J., 1982, 24, (2), 201–212
A fast response H2 analogue to the well-known membrane-covered O2 electrode was constructed, based upon anodic oxidation of H2 on Pt in concentrated H2SO4. The hydrogen probe was also found to serve as an excellent chromatograph H2 flow-cell detector.
A Novel Hydrogen Gas Sensor Based on Hydrogen Uranyl Phosphate
j. s. lundsgaard, j. malling and m. l. s. birchall, Solid State Ionics, 1982, 7, (1), 53–56
Porous composite electrodes of Pt and Pd are used in a novel H2 gas sensor with layered hydrate HUO2PO4.4H2O. The conductivity is dependent on the pressure of water vapour, and long term stability is obtained even at current densities as high as 5 mA/cm2. The Pt and Pd electrodes in the cells gave correct voltages according to Nernst’s law.
Pd-InP Schottky Diode Hydrogen Sensors
m. yousuf, b. kuliyev, b. lalevic and t. l. poteat, Solid-State Electron., 1982, 25, (8), 753–758
Pd-InP Schottky diodes are very sensitive and reproducible detectors of H2. Absorption or desorption of H2 by Pd causes large changes in the diode C-V or I-V characteristics.
Conducting MIS Diode Gas Detectors: The Pd/SiOx/Si Hydrogen Sensor
s. j. fonash, h. huston and s. ashok, Sens. Actuators, 1982, 2, (4), 363–369
A survey of barrier formation and transport in MS and conducting MIS structures is presented and used to describe the H2 sensitivity of Pd/SiOx/Si structures. The presence of the interfacial oxide is necessary for the Pd diode to be sensitive to H2. The sensitivity of highly responsive devices is due to Schottky barrier modification in the presence of H2 and not to an additional channel of transport caused by an increased interface state density in H2.
Catalytic Combustion of Hydrogen. IV. Fabrication of Prototype Catalytic Heaters and Their Operating Properties
m. haruta and h. osano, Int. J. Hydrogen Energy, 1982, 7, (10), 801–807
Two prototypes of catalytic heaters operating on H2 were constructed. The H2 fuelled catalytic heater offers an adjustable heat output of 0−1.5 kcal/cm2h with Pt impregnated Ni foam as a catalyst. Studies of local combustion efficiency and local amounts of air entrained from the ambience were made.
Bimetallic Catalysts; Application in Catalytic Reforming
j. l. carter, g. b. mcvicker, w. weissman, w. s. kmak and j. h. sinfelt, Appl. Catal., 1982, 3, (4), 327–346
The results of various studies on Pt-Ir and Pt-Re reforming catalysts are reported. The studies include catalyst characterisation by H2 and CO chemisorption, catalyst comparisons for conversion of selected hydrocarbons and extended runs on the reforming of petroleum naphtha fractions.
Catalytic Performance of Egg White Type Pt/Al2O3 Catalyst in the Oxidation of C3H8 and CO
k. kunimori, i. nakajima and t. uchijima, Chem. Lett., 1982, (8), 1165–1168
An egg white type Pt/Al2O3 catalyst, without any Pt on the exterior surface, was prepared and the catalytic activities for C3H8 and CO oxidation were compared with conventional egg shell and uniform type catalysts. For the CO oxidation, it was confirmed that the egg white type catalyst was more active than the egg shell type.
Metal Surface Areas of Platinum-Rhenium Catalysts
v. eskinazi, Appl. Catal., 1982, 4, (1), 37–40
H2 and O2 chemisorption and H2 titration measurements were used to characterise the surface structure and find the degree of interaction between Pt and Re on Pt-Re/Al2O3 catalysts. The effects of surface support area and calcination conditions on metal dispersion were also investigated. Maximum metal surface areas were obtained with 55 mole% Re/Al2O3 supports with surface areas greater than 150 m2/g and with catalyst pretreatment involving a 500°C air calcination before reduction.
Selective Reduction of Nitrogen Monoxide with Hydrogen on Pt/Al2O3 Containing a Metal Oxide
y. kosaki, a. miyamoto and y. murakami, Bull. Chem. Soc. Jpn., 1982, 55, (6), 1719–1726
The NO-H2 reaction on a Pt-V2O5/Al2O3 three-way catalyst was composed of three main steps. Step I, the formation of NH3 by the reduction of NO with H2 on Pt; Step II, the NO-NH3 reaction on Pt to form N2 or N2O; and Step III, the reduction of V2O5 in the catalyst by H2 which is accelerated by “H2 spillover”. In the NO-H2 reaction on the Pt-V2O5/Al2O3 catalyst, the formation of excess NH3 is suppressed by the removal of H2 from Pt in Step III, and the NH3 thus produced reacts with NO to form N2 or N2O selectively in Step II.
Properties of Platinum Supported on Oxides of Titanium
b.-h. chen and j. m. white, J. Phys. Chem., 1982, 86, (18), 3534–3541
Pt supported on TiO2, TiO and Ti2O3 in various forms has been investigated by several techniques. On H2-pretrcated TiO2, on TiO and on Ti2O3 platinised samples, strong metal-support interactions (SMSI) with limited H2 uptake was noted. Very fast H-for-D exchange was observed on all materials, showing that dissociative adsorption still occurs. It was concluded that surface contamination, Pt diffusion into the bulk oxide, formation of surface mixed metal oxides and metal agglomeration do not significantly contribute to loss of H2 uptake capacity. The SMSI effect may be best understood in terms of a bulk oxide reduction.
Acidity and Catalytic Activity of RECaY Zeolites for Toluene Disproportionation
r. p. dimitrova, c. dimitrov, z. popova and k. h. steinburg, Appl. Catal., 1982, 3, (4), 377–380
The conversion of toluene was studied on three series of zeolite catalysts based on CaY, RECaY and Pt/RECaY. A relationship was observed between demethylation and disproportionation, and the concentrations of the active sites with acidity −8.2≤pKa≤−5.6, and −5.6≤pKa≤−3.0, respectively, for the CaY and RECaY series. Pt supported catalysts when tested under identical conditions show higher activity and selectivity.
Adsorption of Benzene during Benzene Hydrogenation over Palladium/Alumina Catalyst
k. nakano and k. kusunoki, Kagaku Kogaku Ronbunshu, 1982, 8, (2), 162–167
To clarify the adsorption amounts and adsorption sites of organic species during C6H6 hydrogenation, adsorption measurements of C6H6 and cyclohexane on Pd/Al2O3 catalysts were made at 108−175°C using an electrobalance. Reversible adsorption on the Al2O3 support was predominant and the amount adsorbed on Pd was negligibly small under a H2 atmosphere during C6H6 hydrogenation. A reversible adsorption on Pd atoms and irreversible adsorption exist as well as the reversible adsorption on the support under H2-free conditions. Thus C6H6 hydrogenation appears to occur between H2 adsorbed on metal atoms and C6H6 adsorbed reversibly on the Al2O3 support situated near the metal-support boundary.
Effect of Particle Size on the Activity of Supported Palladium Catalysts
y. takasu, t. akimaru, k. kasahara and y. matsuda, J. Am. Chem. Soc., 1982, 104, (19), 5249–5250
The effect of particle size in a Pd/C catalyst on the kinetics of the H2-D2 exchange reaction at up to 30°C and at 2.8 × 10−2 torr pressure was studied. The catalyst was the first to be prepared in situ in an UHV system and to have electronic energy levels characterised by XPS. As average particle diameter, , increases the activation energy for the exchange reaction declines from 50 kJ/mol at = 1.1 nm to 20 kJ/mol at 1.8 nm. It is postulated that as particle size increases and the binding energy of the core and valence electrons within the Pd particles increases, adsorption energy of H2 on the Pd decreases.
A Silica-Supported Inorganic Photosensitizer
p. a. grutsch and c. kutal, J. Chem. Soc., Chem. Commun., 1982, (16), 893–894
Adsorbing [Ir(bipy)3OH]2+ (bipy = 2,2’-bipyridine) onto the surface of silica gel gives a highly efficient heterogeneous photosensitiser for the valence isomerisation of norbornadiene to quadricyclene.
Catalytic Hydrogenation of Ethylene with (H)Os3(CO)10OSi≡). Spectroscopic Evidence for a Cluster Catalysed Reaction
a. besson, a. choplin, l. d’ornelas and j. m. basset, J. Chem. Soc., Chem. Commun., 1982, (15), 843–845
(H)Os3(CO)10(OSi≡) is a catalyst for C2H4 hydrogenation at 353K. Evidence is presented for the reversibility of C2H4 co-ordination with the cluster and for the complete catalytic cycle of C2H4 hydrogenation. This is the first case of catalysis by a molecular cluster grafted onto unmodified SiO2. The absence of catalyst ageing may be due to the grafting, which may stabilise co-ordinate unsaturation and avoid secondary reactions.
Natural Gas from Carbon Dioxide
New Sci., 1982, 95, (1324), 831
A new Ru carbonyl metal cluster catalyst makes natural-quantity gas from gasified coal. It not only hydrogenates CO but also hydrogenates a waste product of the process, CO2. With a 4:1 mix of H2:CO2 at 1 atm and 275°C, CH4 yields are 60−70% on one pass of gas mixture. Higher yields may be possible at higher pressures.
Carbon Dioxide and Carbon Monoxide Methanation by Supported Ruthenium Catalysts
h. e. ferkul, d. j. stanton, j. d. mccowan and m. c. baird, J. Chem. Soc., Chem. Commun., 1982, (16), 955–956
Ru carbonyl clusters adsorbed on oxide supports and thermally decomposed under H2, are very active catalysts for the methanation of both CO and CO2.
Transition Metals in Organic Synthesis; Annual Survey Covering the Year 1980
l. s. hegedus, J. Organomet. Chem., 1982, 237, (1), 231–451
A review is given of the C-C bond forming reactions, including alkylations of organic halides, acid halides, olefins, alkynes, alcohols and acetates, carbonyl compounds, epoxides, dienyl complexes, coupling and cycloaddition reactions, all using various platinum group meals catalysts. Conjugate addition, carbonylation, oligomerisations, rearrangements, oxidations, reductions and functional group preparations are also surveyed. (1,045 Refs.)
Catalytic Oxidative Chlorination of n -Pentane by Platinum Complexes
w. yubin and d. fuguan, J. Catal. (Dalian, China), 1982, 3, (2), 144–146
Catalytic oxidative chlorination of n -pentane by Pt(II) complexes, [PtCl2(PPh3)2], [PtHCl(PPh3)2], [PtHBr(PPh3)2], [PtHI(PPh3)2], [PtCOCl2(PPh3)] and K2PtCl4 under mild conditions was studied using H2PtCl6 and K2PtCl6 as oxidants. The Pt(II)(catalyst)-Pt(IV)(oxidant) system is not only effective for catalysing the title reaction, but is also more active in the impregnated form on a carrier.
Transition-Metal-Catalyzed Oxidation of Carbon Monoxide by Dichlorine to Produce Phosgene
f. calderazzo and d. belli dell’amico, Inorg. Chem., 1982, 21, (10), 3639–3642
Halometal carbonyls of Pt, Pd and Au catalysed the formation of COCl2 from CO and Cl2 at atmospheric pressure and room temperature under exclusion of light. Attack at the carbonyl C of soluble halo-carbonyl complexes by co-ordinated chloride or Cl2 to give M-C(O)-Cl groupings is thought to be the process involved.
General Synthetic Route for SO2 Cluster Compounds of Platinum and the Structural Characterisation of Pt5(μ -CO)2(μ -SO2)3(CO)(PPh3)4
c. e. briant, d. g. evans and d. m. p. mingos, J. Chem. Soc., Chem. Commun., 1982, (2), 1144–1146
The reaction of 1 atm of SO2 at 60°C with toluene solutions of Pt carbonyl cluster compounds provides a general synthetic route for Pt SO2 cluster compounds.
A Rh Cluster which Selectively Reduces Aldehyde Functions Using CO and H2O as the Hydrogen Source
k. kaneda, m. yasumura, t. imanaka and s. teranishi, J. Chem. Soc., Chem. Commun., 1982, (16), 935–936
The Rh6(CO)16-N,N,N’,N’ -tetramethyl-1,3,-propane-diamine catalyst system has high activity for the reduction of aldehydes using CO and H2O as the H2 source; unsaturated aldehydes give the corresponding unsaturated alcohols in high yields.
Reactivity and Selectivity in Catalysis by Rhodium Complexes
j.m. brown, Chem. Ind., 1982, (19), 737–741
Homogeneous and asymmetric homogeneous reactions, olefin isomerisation, internal asymmetric induction hydroformylation and decarbonylation by organorhodium complex catalysts are discussed. The reactions involve a series of linked intermediates where H2, an olefin and possibly CO are simultaneously co-ordinated and undergo rearrangement.
Activating Hydrogen with Iridium Compounds
r. h. crabtree, Chemtech, 1982, 12, (8), 506–512
A review of Ir homogeneous catalysts is presented. The use of the catalysts in hydrogenation and dehydrogenation reactions, reaction conditions and mechanisms, ligands tested and product yields are discussed. H-bridged cluster compounds and alkane activation systems were examined and t -butyl ethylene was found to weakly bind the metal but also to be very reactive, stripping H from organometals. (34 Refs.)
Ruthenium-Catalysed Reduction of Carbonyl Compounds Using Formic Acid
y. watanabe, t. ohta and y. tsuji, Bull. Chem. Soc. Jpn., 1982, 55, (8), 2441–2444
Carbonyl compounds were hydrogenated to the corresponding alcohols in excellent yields using formic acid with a Ru complex at 125°C for 3 h. 2-Propanone was reduced to 2-propanol by the RuCl2(PPh3)3-HCOOH system in 94% yield with 98% selectivity. The catalytic activity was found to decrease in the order RuCl2(PPh3)3, RuHCl(CO)(PPh3)3, RuHCl(CO)(PPh3)3 and RuH2(PPh3)4.
Effect of Added Ru3(CO)12 on the Indirect Hydrogenation of Cellulose
j. d. cotton, j. c. penrose and p. r. wells, Fuel, 1982, 61, (9), 873–874
The addition of small amounts of Ru3(CO)12 to a mixture of a cellulose substrate, Na2CO3, CO and H2O significantly enhances the extent of the conversion and the H:C ratio in the oil produced in its indirect hydrogenation at 250−350°C. However, the O2 content of the oil is slightly higher.
Catalytic Oxidation of Water by an Oxo-Bridged Ruthenium Dimer
s. w. gersten, g. t. samuels and t. j. meyer, J. Am. Chem. Soc., 1982, 104, (14), 4029–4030
An oxo-bridged dimeric system of Ru(III), [(bpy)2(H2O)RuORu(H2O)(bpy)2)4+, on oxidation by 4 equivalents, (electrochemically or via Ce(IV)) leads to the rapid oxidation of H2O. After catalysis the dimer was present in its Ru(III), Ru(IV) form. 50-fold and 100-fold excesses of Ce(IV) were used.
Engineering Analysis of an NH3-Air Fuel Cell System for Vehicles
p. n.ross,Electrochem. Soc. Symp., Detroit, Oct. 1982, Extended Abstract No. 288, p. 467
An alkaline fuel cell for vehicles using anhydrous liquid NH3 as the H2 storage medium and cracked NH3 as the anode feed, with supported Pt PAFC-type electrodes containing 0.15 mg Pt/cm2 on the anode and 0.35 mg Pt/cm2 on the cathode is described. Power consumption, mass and energy balances for the system are described. NH3 is stored as saturated liquid, is vapourised, superheated and fed to the reactor for H2 generation.
ELECTRICAL AND ELECTRONIC ENGINEERING
Effects of Interface Structure on Electrical Characteristics of PtSi-Si Schottky Barrier Contacts
s.-y. tsaur, d. j. silversmith, r. w. mountain and c. h. anderson, Thin Solid Films, 1982, 93, (3/4), 331–340
The properties of PtSi-Si Schottky barrier contacts formed by a new technique employing multilayer metallisation are studied. The multilayer technique permits the formation of very shallow contacts without any limitation in the thickness of the PtSi layer. The interfacial uniformity is independent of PtSi thickness for shallow PtSi-Si contacts produced by this technique. Larger area (9.4 × 10−3cm2) diodes utilising shallow PtSi-Si contacts about 200 Å deep were fabricated without guard rings. These diodes exhibit near-ideal forward current-voltage characteristics, low reverse leakage currents and high breakdown voltages.
Reduction in the Effective Barrier Height in PtSi-p-Si Schottky Diodes by Using Low Energy Ion Implantation
c.-y. wei, w. tantraporn, w. katz and g. smith, Thin Solid Films, 1982, 93, (3/4), 407–412
A reduction in the effective barrier height in a PtSi-p-Si Schottky diode was achieved by low energy implantation, to introduce a shallow Pt layer on a p-Si substrate. After the Schottky diode was implanted with 3 keVIIB+ ions to a dose of 4 × 1012 ions/cm2, the barrier height was observed to decrease from 0.26 to 0.16 eV.
Preparation of a RuO2-Modified Semiconductor Oxide Surface. An Optimization Procedure of Interest in Energy Conversion Systems
i. d. burke, j. f. healy and o. ni dhubhghaill, Surf. Technol., 1982, 16, (4), 341–347
A simple procedure is described for modifying the surface of a semiconducting or insulating oxide powder (such as TiO2) by the adsorption of RuCl3 from isopropanol solution. Adsorption at monolayer and submonolayer level was readily achieved, 1 g of Ru being uniformly dispersed as RuCl3 or RuO2 over 9000 m 2 of the surface of a TiO2 support. Heating the powder in air at 425°C resulted in the formation of a RuO2-modified surface. The surface-bonded RuO2 groups were shown to be active with respect to catalytic oxidation reactions, and repeated runs with the same catalyst confirmed the stability of the RuO2 linkage to the oxide support.
Strange Temperature Characteristics of RuO2-Based Thick Film Resistors
t. inokuma, y. taketa and m. haradome, Electro-component Sci. Technol., 1982, 9, (3), 205–207
For some thick film resistors with conductive element RuO2 and having almost zero TCRs, the electrical properties can be improved by doping with MnO2. These MnO2 doped resistors have low TCR which is constant from low to high resistivity. The glass frits the resistors were made of was 52 PbO-35 SiO2-10 B2O3-3 Al2O3 and RuO2 was mixed into them in the ratio RuO2:glass 55:50, 25:75, 15:85 and 10:90, all measured in wt.%.
Synthesis and Antitumour Activity of Platinum Complexes Containing Neutral and Protonated Amine-Olefin Ligands
d. b. brown, a. r. khokhar, m. p. hacker, j. j. mccormack and w. m. stalick, Inorg. Chim. Acta, Bioinorganic Chem. Artic. Lett., 1982, 67, (2), 45–52
A series of N-substituted allyl amines bound to Pt are reported. Under acidic conditions compounds of general formula (protonated amino-olefin) PtCl3 are formed. All the complexes contain Pt-chloride bonds activated towards hydrolysis, and were examined for potential anti-tumour activity. Most of the protonated ligand complexes exhibited significant cytotoxicity against both cis -Pt sensitive and resistant L1210 leukaemia in cell culture.