Platinum emissions

Rosner, G., and Merget, R. (2000). Evaluation of the health risk of platinum emissions from automotive emissions control catalysts. In Anthropogenic Platinum-Group Element Emissions. Their Impact on Man and Environment (F. Zereini and F. Alt, eds.), pp. 267—281. Springer-Verlag, Berlin. 

E. Helmers, Platinum emission rate of automobiles with catalytic converters D comparison and assessment of results from different approaches, Environ. Sci. Pollut. Res., 4 (1997), 100D103. 

H. P. Konig, R. F. Hertel, W. Koch, G. Rosner, Determination of platinum emissions from a three-way catalyst-equipped gasoline engine, Atmos. Environ., 26A (1992), 741D745. 

Ward, N.I., Dudding, L.M. Platinum emissions and levels in motorway dust samples influence of traffic characteristics. Sci. Total Environ. 334-335, 457 63 (2004)... 

Artelt S, Kock H, Konig H, Levsen K, Rosner G (1999) Engine dynamometer experiments platinum emissions from differently aged three-way catalytic converters. Atmos Environ... 

Therefore preparation of non-contaminated and well defined particulate material, which resemble Pd particles emitted from automobile catalysts into the environment and which are available in higher standardized quantities, is very reasonable. A comparable approach for platinum was made by Ruehle et al. (1997) focussing on traffic related platinum emissions, but for palladium appropriate material was not yet available. Synthesis of the Pd particles was performed by chemical reduction of Pd° to Pd° in aqueous solutions similar to a method first described by Mucalo et al. (1991). Optimization of this method yielded in a simple, fast and very reproducible preparation method for appropriate Pd nanoparticles with a narrow size distribution. Three types of Pd particles—Pd... 

Artelt S, Levsen K, Konig HP, Rosner G (2000) Engine test bench experiments to determine platinum emissions from three-way catalytic converters. In Zereini F, Alt F (eds) Anthropogenic platinum group element emissions. Their impact on man and environment. Sjainger, Berlin, pp 33-44... 

Ultraviolet photoelectron spectroscopy (UPS) results have provided detailed infomiation about CO adsorption on many surfaces. Figure A3.10.24 shows UPS results for CO adsorption on Pd(l 10) [58] that are representative of molecular CO adsorption on platinum surfaces. The difference result in (c) between the clean surface and the CO-covered surface shows a strong negative feature just below the Femii level ( p), and two positive features at 8 and 11 eV below E. The negative feature is due to suppression of emission from the metal d states as a result of an anti-resonance phenomenon. The positive features can be attributed to the 4a molecular orbital of CO and the overlap of tire 5a and 1 k molecular orbitals. The observation of features due to CO molecular orbitals clearly indicates that CO molecularly adsorbs. The overlap of the 5a and 1 ti levels is caused by a stabilization of the 5 a molecular orbital as a consequence of fomiing the surface-CO chemisorption bond. 

PGM catalyst technology can also be appHed to the control of emissions from stationary internal combustion engines and gas turbines. Catalysts have been designed to treat carbon monoxide, unbumed hydrocarbons, and nitrogen oxides in the exhaust, which arise as a result of incomplete combustion. To reduce or prevent the formation of NO in the first place, catalytic combustion technology based on platinum or palladium has been developed, which is particularly suitable for appHcation in gas turbines. Environmental legislation enacted in many parts of the world has promoted, and is expected to continue to promote, the use of PGMs in these appHcations. 

Another important potential appHcation for fuel cells is in transportation (qv). Buses and cars powered by fuel cells or fuel cell—battery hybrids are being developed in North America and in Europe to meet 2ero-emission legislation introduced in California. The most promising type of fuel cell for this appHcation is the SPEC, which uses platinum-on-carbon electrodes attached to a soHd polymeric electrolyte. 

To add surface area, the supports are uniformly coated with a slurry of gamma-alumina and recalcined under moderate conditions. The wash coat acts to accept the active metals, typically low levels of platinum and palladium, in a conventional impregnation process. In the United States in passenger car apphcations the spherical catalyst is used almost exclusively, and methods have been developed to replace the catalyst without removing the converter shell when vehicle inspection reveals that emission standards are not met. 

Another potential solution is the use of catalytic combustors, which produce extremely low levels of emissions by the use of combustion catalysts such as platinum. The main disadvantage of catalytic combustors, however, is thek high cost. 

Emission spectra have been recorded for four aryl-substituted isoindoles rmder conditions of electrochemical stimulation. Electrochemiluminescence, which was easily visible in daylight, was measured at a concentration of 2-10 mM of emitter in V jV-dimethylformamide with platinum electrodes. Emission spectra due to electrochemi-luminescence and to fluorescence were found to be identical, and quantum yields for fluorescence were obtained by irradiation with a calibrated Hght source. Values are given in Table X. As with peak potentials determined by cyclic voltammetry, the results of luminescence studies are interpreted in terms of radical ion intermediates. ... 

Probably the most significant control technology breakthrough came m 1977, when Volvo released a computer-controlled, fuel-mjected vehicle equipped with a three-way catalyst. The new catalytic converters employed platinum, palladium, and rhodium to simultaneously reduce NO and oxidize CO and HC emissions under carefully controlled oxygen conditions. The new Bosch fuel injection system on the vehicle provided the precise air/fuel control necessary for the new catalyst to perform effectively. The combined fuel control and three-way catalyst system served as the foundation for emissions control on the next generation of vehicles. 

Palladium (Pd) is an element with properties similar to those of platinum. It is useful in eliminating harmful emissions produced by internal combustion engines. Two students were given identical cylindrical palladium bars with die following data ... 

For the preparation of samples for X-ray fluorescence spectroscopy, lithium metaborate is the preferred flux because lithium does not give rise to interfering X-ray emissions. The fusion may be carried out in platinum crucibles or in crucibles made from specially prepared graphite these graphite crucibles can also be used for the vacuum fusion of metal samples for the analysis of occluded gases. 

The main use of rhodium is with platinum in catalysts for oxidation of automobile exhaust emissions. In the chemical industry, it is used in catalysts for the manufacture of ethanoic acid, in hydroformylation of alkenes and the synthesis of nitric acid from ammonia. Many applications of iridium rely on... 

Characteristic x-ray emission spectra, from x-ray excitation, 27, 28 of platinum, measurement by Bragg, 25, 26, 35 origin, 30-34... 

Phototubes, multiplier, 56-59, 222 Placement error, 285-287 Planck s constant, 7, 8 Plastics, characterization by absorptiometry, 78, 79 Plateau, characteristic, 60 Platinum, determination by x-ray emission spectrography, 161, 328 L peaks, measured by Bragg, 25, 26, 35 L spectra, 35... 

Serious research in catalytic reduction of automotive exhaust was begun in 1949 by Eugene Houdry, who developed mufflers for fork lift trucks used in confined spaces such as mines and warehouses (18). One of the supports used was the monolith—porcelain rods covered with films of alumina, on which platinum was deposited. California enacted laws in 1959 and 1960 on air quality and motor vehicle emission standards, which would be operative when at least two devices were developed that could meet the requirements. This gave the impetus for a greater effort in automotive catalysis research (19). Catalyst developments and fleet tests involved the partnership of catalyst manufacturers and muffler manufacturers. Three of these teams were certified by the California Motor Vehicle Pollution Control Board in 1964-65 American Cyanamid and Walker, W. R. Grace and Norris-Thermador, and Universal Oil Products and Arvin. At the same time, Detroit announced that engine modifications by lean carburation and secondary air injection enabled them to meet the California standard without the use of catalysts. This then delayed the use of catalysts in automobiles. 

For the noble metals used in oxidation, the loading is about 0.1 oz per car, with calls for a million ounces per year. The current world production rates of platinum, palladium, and rhodium are 1.9, 1.6, and 0.076 million ounces respectively the current U,S. demand for platinum, palladium, rhodium, and ruthenium are 0.52, 0.72, 0.045, and 0.017 million ounces respectively (72, 73). The supply problem would double if NO reduction requires an equal amount of noble metal. Pollution conscious Japan has adopted a set of automobile emission rules that are the same as the U.S., and Western Europe may follow this creates a demand for new car catalysts approaching the U.S. total. The bulk of world production and potential new mines are in the Soviet Union and South Africa. The importation of these metals, assuming the current price of platinum at 155/oz and palladium at 78/oz, would pose a balance of payment problem. The recovery of platinum contained in spent catalysts delivered to the door of precious metal refiners should be above 95% the value of platinum in spent catalysts is greater than the value of lead in old batteries, and should provide a sufficient incentive for scavengers. 

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