Platinum Metals Rev., 2013, 57, (1), 76
Abstracts: January 2013
CATALYSIS – INDUSTRIAL PROCESSES
Heterogeneous Catalytic Chemistry by Example of Industrial Applications
J. Heveling, J. Chem. Educ., 2012, 89, (12), 1530–1536
A heterogeneous metal catalyst typically consists of the active metal component, promoters and a support material. The metallic state itself may form the active ingredient. Examples of practical industrial importance are used by the author to highlight important principles of catalysis. These include for the pgms: ammonia oxidation (Pt-Rh), automotive exhaust catalysts (Pt, Pd and Rh) and oxidation catalysts (Pt-Bi).
CATALYSIS – REACTIONS
Photocatalytic Hydrogen Generation in the Presence of Ethanolamines over Pt/ZnIn2S4 under Visible Light Irradiation
Y. Li, K. Zhang, S. Peng, G. Lu and S. Li, J. Mol. Catal. A: Chem., 2012, 363–364, 354–361
The photocatalytic activity for H2 evolution and decomposition of ethanolamine (EA), diethanolamine (di-EA) and triethanolamine (tri-EA) as electron donors (pollutants) over Pt/ZnIn2S4 were investigated. The Pt was deposited on ZnIn2S4 by in situ photoreduction of H2PtCl6. The order of activity for H2 evolution was: tri-EA >> di-EA > EA. The order of adsorption intensity of the ethanolamines on ZnIn2S4 was: EA > di-EA >> tri-EA. The order of activity was found to depend on their molecular structure and adsorption performance.
Application of an Air-and-Moisture-Stable Diphenylphosphinite Cellulose-Supported Nanopalladium Catalyst for a Heck Reaction
Q. Du and Y. Li, Res. Chem. Intermed., 2012, 38, (8), 1807–1817
The title catalyst (Cell–OPPh2-Pd0) was prepared from cellulose and chlorodiphenylphosphine in pyridine, followed by treatment with an ethanol solution of PdCl2. The prepared catalyst was air- and moisture-stable. Phenyl halides were coupled with alkenes in DMF under air, to afford the corresponding products in good yields. The catalyst could be easily recovered by filtration and reused for up to 6 cycles.
Hydrogenation of Phenol Using Silica-Supported Pd and PdAu Catalysts in the Presence of H2 and O2
S. Okada, K. Fujiwara, T. Kamegawa, K. Mori and H. Yamashita, Bull. Chem. Soc. Jpn., 2012, 85, (9), 1057–1059
2-Cyclohexen-1-one was obtained from phenol by hydrogenation under H2 and O2 gases using a Pd/SiO2 catalyst. The effects of the H2:O2 ratio, solvent and alloying Pd with Au were all investigated. Similar transformations to form corresponding cyclic enones were achieved with other phenolic type compounds.
Iridium-Catalyzed Intramolecular [4 + 2] Cycloadditions of Alkynyl Halides
A. Tigchelaar and W. Tam, Beilstein J. Org. Chem., 2012, 8, 1765–1770
Ir-catalysed intramolecular [4 + 2] cycloadditions of diene-tethered alkynyl halides were carried out using [IrCl(cod)]2. The most suitable phosphine ligand for the reaction was dppe. The cycloadditions proceeded smoothly at 90ºC to give the halogenated cycloadducts in good yield (75–94%). No oxidative insertion of the Ir into the carbon–halide bond was observed.
A Three-Electrode Column for Pd-Catalytic Oxidation of TCE in Groundwater with Automatic pH-Regulation and Resistance to Reduced Sulfur Compound Foiling
S. Yuan, M. Chen, X. Mao and A. N. Alshawabkeh, Water Res., 2013, 47, (1), 269–278
A hybrid electrolysis and Pd-catalysed oxidation process was evaluated for the degradation of trichloroethylene (TCE) in groundwater. A three-electrode (one anode and two cathodes) column was used to automatically develop a low pH in the vicinity of Pd and neutral effluent. Simulated groundwater containing up to 5 mM bicarbonate could be acidified to below pH 4 in the vicinity of Pd using a total of 60 mA with 20 mA passing through the third electrode. By packing 2 g of Pd/Al2O3 pellets in the developed acidic region, the column efficiency for TCE oxidation in simulated groundwater (5.3 mg l−1 TCE) increased from 44% to 59% and 68% with increasing Fe(II) concentration from 0 mg l−1 to 5 mg l−1 and 10 mg l−1, respectively. This process may be used to control the fouling caused by reduced sulfur compounds (RSCs) because the in situ generated reactive oxidising species such as O2, H2O2 and ·OH can oxidise RSCs.
A New Oxygen Storage Capacity Material of a Tin-Doped Ceria–Zirconia-Supported Palladium–Alumina Catalyst with High CO Oxidation Activity
Q. Dong, S. Yin, C. Guo and T. Sato, Chem. Lett., 2012, 41, (10), 1250–1252
Ce0.5Zr0.4Sn0.1O2/Pd–Al2O3 composite catalysts were prepared by mechanical mixing of Ce0.5Zr0.4Sn0.1O2 and 2 wt% Pd–Al2O3 powder (weight ratio of Ce0.5Zr0.4Sn0.1O2:Pd–Al2O3 = 50:50). These composites had a high BET surface area of 38 m2 g−1 and exhibited a high oxygen storage capacity and high CO oxidation activity at low temperatures, even after calcination at 1000ºC for 20 h. The authors state that the prepared Ce0.5Zr0.4Sn0.1O2/Pd–Al2O3 has potential as a key material in advanced catalytic converters for the design of three-way catalysts.
Application of a Re–Pd Bimetallic Catalyst for Treatment of Perchlorate in Waste Ion-Exchange Regenerant Brine
J. Liu, J. K. Choe, Z. Sasnow, C. J. Werth and T. J. Strathmann, Water Res., 2013, 47, (1), 91–101
Re–Pd/C was shown to reduce ClO4− to Cl− in waste ion-exchange (IX) brines. The catalyst activity was not inhibited in synthetic NaCl-only brine compared to DI water. Re–Pd/C was deactivated by reaction with excess NO3− present in the real waste IX brine. The deactivation of the Re–Pd/C catalyst could be prevented by pretreating NO3− with an In–Pd/Al2O3 catalyst.
Self-Recovery of Pd Nanoparticles That Were Dispersed over La(Sr)Fe(Mn)O3 for Intelligent Oxide Anodes of Solid-Oxide Fuel Cells
T. H. Shin, Y. Okamoto, S. Ida and T. Ishihara, Chem. Eur. J., 2012, 18, (37), 11695–11702
High-performance ‘intelligent oxide anodes’ for SOFCs have been prepared. These anodes can achieve self-recovery from power density degradation during the redox cycle by using a Pd-substituted La(Sr)Fe(Mn)O3 cell as an oxide anode. The recovery of the power density could be explained by the formation of Pd NPs, which were self-recovered through reoxidation and reduction. This process was shown to be effective for improving the durability of SOFC systems when under severe operating conditions.
A Dual-Chambered Microbial Fuel Cell with Ti/Nano-TiO2/Pd Nano-Structure Cathode
M. G. Hosseini and I. Ahadzadeh, J. Power Sources, 2012, 220, 292–297
The title cathode was used in a dual-chambered microbial fuel cell with a graphite anode and a Flemion cation exchange membrane. Ti/nano-TiO2/Pd gave satisfactory long term performance as a cathode to reduce water dissolved oxygen. The maximum output power of the cell was about 200 mW m−2 normalised to the cathode surface area. The open circuit potential of the cell was about 480 mV and the value of the short circuit current was 0.21 mA cm−2 of the cathode geometric surface area.
Additive-Free Fabrication of Spherical Hollow Palladium/Copper Alloyed Nanostructures for Fuel Cell Application
C. Hu, Y. Guo, J. Wang, L. Yang, Z. Yang, Z. Bai, J. Zhang, K. Wang and K. Jiang, ACS Appl. Mater. Interfaces, 2012, 4, (9), 4461–4464
Spherical hollow Pd-Cu alloyed nanostructures supported on MWCNTs were obtained by alloying through a one-pot preparative method. A Pd(II) salt and a Cu(II) salt (atomic ratio 1:1) and MWCNTs were simultaneously dispersed into ethylene glycol in a stainless steel autoclave, and the pH was adjusted to 12. Then it was sealed and heated at 160ºC for 6 h. The PdCu/MWCNTs exhibited a higher electrochemical active surface area than that of Pd/MWCNTs and therefore their electrocatalytic activity for formic acid oxidation was enhanced.
METALLURGY AND MATERIALS
Thermal Stability of Grain Structure and Material Properties in an Annealing-Twinned Ag–8Au–3Pd Alloy Wire
T.-H. Chuang, H.-C. Wang, C.-H. Tsai, C.-C. Chang, C.-H. Chuang, J.-D. Lee and H.-H. Tsai, Scr. Mater., 2012, 67, (6), 605–608
A large number of annealing twins can be observed in a Ag–8Au–3Pd wire. In contrast to the rapid grain growth in Au and Cu wires during ageing at 600ºC, the grain size of this alloy wire remained almost unchanged. The annealing twins in this alloy wire exhibited increasing strength and elongation with ageing time. The electrical resistivity remained constant.
High Energy Resolution Off-Resonant Spectroscopy at Sub-Second Time Resolution: (Pt(acac)2) Decomposition
J. Szlachetko, M. Nachtegaal, J. Sá, J.-C. Dousse, J. Hoszowska, E. Kleymenov, M. Janousch, O. V. Safonova, C. König and J. A. van Bokhoven, Chem. Commun., 2012, 48, (88), 10898–10900
The decomposition of Pt(acac)2 in H2 induced by flash heating was investigated. The changes in the local Pt structure were followed using in situ high energy resolution off-resonant spectroscopy (HEROS). The metal complex was flash heated to 150ºC and HEROS spectra were collected every 500 ms. The Pt(acac)2 decomposition was shown to consist of a two-step reduction process of the Pt(II) species.
ELECTRICAL AND ELECTRONICS
Influence of Thin Platinum Layer on the Magnetic Properties of Multiple Layers of CVD Cobalt Thin Films
N. Deo, M. F. Bain, J. H. Montgomery and H. S. Gamble, J. Mater. Sci.: Mater. Electron., 2012, 23, (10), 1881–1886
Co layers were deposited by MOCVD on oxidised Si substrates at 450ºC, in H2 at ambient temperature with 2 Torr processing pressure. Pt layers were then deposited by E-beam evaporation in another vacuum system. Multiple layers of Co/Pt/Co and Co/Pt with Co thickness 15 nm and 30 nm and a 1.5 nm Pt spacer layer showed significant change in magnetic properties (coercivity Hc and magnetisation Ms). They had soft magnetic properties with Hc values of 51 Oe and 49 Oe, respectively, which are significantly less than the Hc values of single Co layers on oxidised Si.
Controlled Synthesis of Concave Tetrahedral Palladium Nanocrystals by Reducing Pd(acac)2 with Carbon Monoxide
H. Zhu, Q. Chi, Y. Zhao, C. Li, H. Tang, J. Li, T. Huang and H. Liu, Mater. Res. Bull., 2012, 47, (11), 3637–3643
Concave tetrahedral Pd nanocrystals with uniform sizes were prepared using Pd(acac)2 as a precursor, PVP as a stabiliser and CO as a reducing agent under atmospheric pressure. The best CO flow rate, temperature and time for the formation of the ideal concave tetrahedral Pd nanocrystals were 0.033 mL s−1, 100ºC and 3 h, respectively. In the absence of CO, the reaction did not occur.
Microfluidic Size Selective Growth of Palladium Nano-Particles on Carbon Nano-Onions
F. Md Yasin, R. A. Boulos, B. Y. Hong, A. Cornejo, K. S. Iyer, L. Gao, H. T. Chua and C. L. Raston, Chem. Commun., 2012, 48, (81), 10102–10104
Size selective growth of Pd NPs (2–7 nm in diameter) on the surface of C nano-onions (CNOs) in water involved pretreating the CNOs with p-phosphonic acid calixarene, 1, then mixing with H2PdCl4 followed by dynamic thin film processing under H2 in a vortex fluidic device (VFD). The control in particle size by varying the speed using the VFD was consistent with variations in mass transfer of H into the dynamic thin films.