Impurities nitrogen

Chemical Conversion. Except for control of nitrogen impurity levels, the same chemical conversion methods used for nitrogen purification at low flow rates can also be used for argon purification. Although used less commonly for argon purification than for nitrogen purification, these chemical conversion methods are appHed in point-of-use purifiers located close to where the gas is consumed. 

Semiconducting Properties. Sihcon carbide is a semiconductor it has a conductivity between that of metals and insulators or dielectrics (4,13,46,47). Because of the thermal stabiUty of its electronic stmcture, sihcon carbide has been studied for uses at high (>500° C) temperature. The Hall mobihty in sihcon carbide is a function of polytype (48,49), temperature (41,42,45—50), impurity, and concentration (49). In n-ty e crystals, activation energy for ioniza tion of nitrogen impurity varies with polytype (50,51). 

Sometimes hydroxylamines are formed in systems where the amino compound would have been expected. This occurs usually in compounds containing either sulfur or basic nitrogen impurities may have had an... 

Reduce harmful impurities in petroleum fractions and residues to control pollution and to avoid poisoning certain processing catalysts. For example, hydrotreatment of naphtha feeds to catalytic reformers is essential because sulfur and nitrogen impurities poison the catalyst. 

The color of diamond due to nitrogen impurities has been described in Section 9.6.3 It has been found that nitrogen impurities that are located next to a carbon vacancy in diamond thin films endow the solid with quite new properties, somewhat similar to the properties of a solid containing FLi centers compared with ordinary F centers. The diamond structure is built up of carbon atoms each surrounded by four... 

So-called prepolymerization is frequently used to achieve a very high purification a monomer that has already been purified by the normal methods is polymerized to about 10-20% conversion by heating or irradiation, or if necessary by addition of initiator. It is then separated from the polymer by fractional distillation under nitrogen. Impurities that affect the initiation (e.g., by reaction with the initiator or its fragments) or that react with the growing macromolecules (causing chain termination or chain transfer) are thereby removed. 

Electrolysis of brines regularly produces low levels of nitrogen trichloride from nitrogenous impurities as byproduct, this concentrates when liquid chlorine is evaporated and should be largely removed by distillation before the product is sold... 

Akhtar, J., S.K. Durrani, N.A. Chughtai, et al. 2002. Determination of oxygen and nitrogen impurities in magnesium metal by vacuum distillation and ICP-OES techniques. Turk. J. Chem. 26 681-690. 

As already mentioned, quinoline is one of the major nitrogenated compounds found in heavy oils, and with its pyridine and benzene rings is a good representative of the other nitrogenated impurities. These two facts explain why its HDN has been extensively used as model reaction by different research groups, mainly Satterfield et al. (MIT),31 Katzer et al. (Delaware),32 and by Schultz etal.,33 Vlugter etal.,34 and Flinn etal.3Sa Some studies have also been published on benzoquinolines,36 acridine,32 and indole.35b... 

Impurities in the feed The design calculations were based on an assumption that the feed contains only MEK vapor and nitrogen. Impurities present in the feed could react with the MEK, or they could condense and affect the vapor-liquid equilibrium distribution of MEK in the products. 

Later it was observed that LiNOs gives saturated esters in oxidation of olefins in the presence of palladium(II) acetate (259). This result demonstrates one of the pitfalls in interpreting the results of earlier studies of oxidations by palladium(II) acetate, since, as usually prepared by the nitric acid oxidations of Pd sponge, it contains some nitrogeneous impurities 24). 

TABLE 9.1.11. Trace nitrogenous impurity compounds identified in the pyrogram of a... 

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