Contaminant tolerance

Carbon-supported Pt can also be used as the anode catalyst. However, this requires pure H2. Contaminants such as carbon monoxide (CO) poison the catalyst, because CO can strongly adsorb on Pt, blocking the catalytic sites and reducing platinum s catalytic activity. In H2 produced from the reforming of other fuels, CO is always present. Thus, to improve contaminant tolerance, carbon-supported PtRu was developed and now is always used as the anode catalyst. Ru can facilitate the oxidation of CO, releasing the catalytic sites on Pt through the following reactions ... 

Xiang, F. and Beavis, R. C., A method to increase contaminant tolerance in protein matrix-assisted laser desorption/ionization by the fabrication of thin protein-doped polycrystalline films. Rapid Communication Mass Spectrometry, 8, 199-204,1994. 

Food contaminant Tolerable intakes and other toxicological recommendations ... 

Table 2 summarizes the known contaminant tolerance limits for the common commercially die cast alloys of magnesium plus the recently published tolerance limits for the developmental alloy AE42 [11], As may be noted in Table 2, while the tolerance limits for nickel and copper are essentially independent of the alloy composition, within its normal... 

TABLE 2—Contaminant tolerance limits for cast alloys. 

Improved Contaminant Tolerance with Increasing Temperature... 

High electrochemical activity and contamination tolerance. An eleetroeatalyst should be of high intrinsic activity, to diminish electrochemical reaction polarization and enhance energy conversion effieiency. More specifieally, the anode catalyst should have the ability to resist detrimental by-products such as CO and other intermediates that poison the active reaction surface the cathode catalyst should have the ability to restrain crossover methanol oxidation when liquid methanol is seleeted as the fuel. 

Future work in contamination mitigation in PEMFCs should include improving gas stream filtering methodologies as well as developing more contamination tolerant fuel cell components, such as the catalyst, catalyst layers, and membranes. 

Illustrates how to develop contaminant-tolerant catalysts by evaluating the impacts of impurities on PEMFC performance... 

Some industries have found a contamination level equal to or below 500 mg/m (47.5 mg/ft ) to be the maximum level of hydrocarbon contamination tolerable for components, equipment, and systems in oxygen service. The actual level depends on the specific application (state of fluid, temperature, and pressure). 

Any of several acid solutions (Table 5) can remove flux that remains after washing- The choice dqtends largely on the thickness of the brazed parts, the accessibility of fluxed areas, and the adequacy of flux removal in the initial water treatment. A pitting or intergranular type of attack on parts can result as chlorides from the flux build up in the acid solution. Some solutions have a greater tolerance for these chlorides than others before parts are attacked. The degree of flux contamination tolerable for the five typical flux removal solutions listed in Table 5 is given in the table footnotes. It should be noted that because of disposal/... 

Xiang, F., andBeavis, R.C., 1993, A Method to Increase contaminant Tolerance inProtein-Matrix-assisted Laser Desorption/Ionization by the Fabrication of Thin Protein-doped Polycrystalline films. In Rapid Commun. In Mass Spectrom., 199-204... 

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