Additives metal deactivators

Metal Deactivators. The abiUty of metal ions to catalyse oxidation can be inhibited by metal deactivators (19). These additives chelate metal ions and increase the potential difference between the oxidised and reduced states of the metal ions. This decreases the abiUty of the metal to produce radicals from hydroperoxides by oxidation and reduction (eqs. 15 and 16). Complexation of the metal by the metal deactivator also blocks its abiUty to associate with a hydroperoxide, a requirement for catalysis (20). 

The stabili2ation of polyolefins used to insulate copper conductors requires the use of a long-term antioxidant plus a copper deactivator. Both A[,Ar-bis(3,5-di-/ A-butyl-4-hydroxycinnamoyl)hydra2ine (29) and 2,2 -oxamidobisethyl(3,5-di-/ A-butyl-4-hydroxycinnamate) (30) are bifimctional. They are persistent antioxidants that have built-in metal deactivators. Oxalyl bis(ben2yhdenehydra2ide) (28) is an effective copper deactivator when part of an additive package that includes an antioxidant. 

The precious metals possess much higher specific catalytic activity than do the base metals. In addition, base metal catalysts sinter upon exposure to the exhaust gas temperatures found in engine exhaust, thereby losing the catalytic performance needed for low temperature operation. Also, the base metals deactivate because of reactions with sulfur compounds at the low temperature end of auto exhaust. As a result, a base metal automobile exhaust... 

Another additive used is a metal deactivator to chemically deactivate any catalytic metals such as copper accidentally dissolved in the fuel from metal surfaces. Uless they are chemically deactivated, dissolved metals cause the loss of good stability quality. 

All of the Au/metal oxide catalysts deactivate quickly, under the conditions shown in Figure 4. In addition, the deactivation of the Au/metal oxide catalysts appears to be enhanced in the presence of COj. In support of the theory that increased basicity of the metal oxides leads to lower stability, we carried out COj temperature programmed desorption experiments on the various catalysts. The COj TPD data also confirmed that an increase in the basicity of the metal oxides leads to an increase in the amount of COj adsorption on the catalysts. 

In TLC the choice of mobile phase depends primarily on the additive in question. Gedeon el al. [394] have listed mobile phases for the separation of AOs and plasticisers. Bataillard et al. [351] have reported R values for various solvents and visualisation modes for a great variety of primary and secondary AOs, UVAs, HALS and metal deactivators. 

There have been some examples of the use of LDMS applied to the analysis of compounds separated via TLC, although not specifically dealing with polymer additives [852]. Dewey and Finney [838] have described direct TLC-spectroscopy and TLC-LMMS as applied to the analysis of lubricating oil additives (phenolic and amine antioxidants, detergents, dispersants, viscosity index improvers, corrosion inhibitors and metal deactivators). Also a series of general organics and ionic surfactants were analysed by means of direct normal-phase HPTLC-LMMS [837]. Novak and Hercules [858] have... 

Metal-deactivating antioxidants. Transition metal compounds decompose hydroperoxides with the formation of free radicals, thereby increasing the rate of oxidation. Such an enhanced oxidation can be slowed down by the addition of a compound that interacts with metal ions to form complexes that are inactive with respect to hydroperoxides. Diamines, hydroxy acids, and other bifunctional compounds exemplify this type of antioxidants. 

If a gasoline does not meet this specification, antioxidants can be added to the fuel to provide an increase in induction time. Antioxidant treat rates of 5 to 50 ppm are typical. Also, the addition of a metal deactivator at a 1 to 2 ppm treat rate may improve induction time. 

Additive A chemical substance added to a product to impart or improve certain properties. Typical fuel additives include antioxidants, cetane improvers, corrosion inhibitors, demulsifiers, detergents, dyes, metal deactivators, octane improvers, and wax crystal modifiers. 

This kind of experiment could be useful when evaluating stabilisers that are designed to act as metal deactivators. Different additives could also be placed in contact with the polymer. The additives that initiated oxidation could be expected to reduce the oxidative stability of the polymer. 

The nature of existing fuels as a complex liquid mixture of hydrocarbons lends itself well to adjustment of properties by choice of fraction, blending, treatment, etc., so that the properties of the fuel can be tailored to meet the demands of particular applications. The fuels are essentially non-polar organic solvents, and readily dissolve a variety of additives. Thus, military fuels can be based on commercial fuels, but with adjusted properties. For example, JP 8 is essentially identical to commercial Jet A-l, but with the addition of a military additive pack to account for the more demanding military requirements. This includes antioxidants to prevent fuel oxidation, metal deactivators to counteract metals, fuel system icing inhibitor to prevent water in fuel from freezing, and a corrosion inhibitor/lubricity enhancer to prevent corrosion and fuel pump failure.1... 

The measure of activity on these pretreated catalysts gives a direct access to the real toxicity of sulfur for the specific reaction. Figure 12 emphasizes the turnover numbers of the 1-butene hydrogenation and isomerization versus the sulfur level. The sulfiding of the metal deactivates the catalyst for both reactions. Nevertheless, they are quantitatively not similarly affected the hydrogenation shows a toxicity of 5 and the izomerization of 2. The rates are not proportional to the free surface portion, which would be indicated by a toxicity of 1. The addition of one sulfur atom deactivates more than one palladium atom. 

Metal deactivator. Metal deactivator prevents precipitation of metal ion oxidation reactions and precipitation of insoluble metal compounds. Metal deactivator in combination with other antioxidants, shows strong synergistic effects. Oxygen and moisture present, diffuse through oil film and cause corrosion. Amine derivative, used in the additive has good water-displacing properties. They impede sludge formulation, disperse sediments and reduce corrosion in various fuel systems. 

In addition to the metal deactivation effects which obviously would make useless this procedure in metal dispersion studies, the likely occurrence of CO dissociation should also be considered (113,164,168,192). 

It is well known that metal catalysts are poisoned by compounds of Group VB and VIB elements (ref. 90). The precise effect of a given poison however, may vary from system to system. In addition, catalyst deactivation may also result from the adsorption of a product of the reaction onto the active surface. The poisoning effect may be reversible, and in some cases catalytic activity can be restored by eliminating the source of poison. On the other hand, when poisoning occurs by an irreversible process, regeneration of the catalyst may not be possible, and so it may have to be discarded. 

Jet fuels are aviation fuels used mainly by the United States and other North Atlantic Treaty Organization (NATO) nations for military establishments. Other fuels called Jet A and Jet A-1 are closely related fuels used by commercial airlines. JP are a complex mixture of primarily aliphatic (but also aromatic) hydrocarbons, derived from crude oil and/or kerosene by refining and adding various other additives such as fuel icing inhibitors, antioxidants, corrosion inhibitors, metal deactivators, and static dissipaters. Gas chromatographic analysis of JP-8, the most recent JP, indicates that it is made up of complex mixture of 9 to 17 different hydrocarbons, including thousands of isomers and three to six performance additives. They are generally colorless liquids and smell like kerosene. 

Metal deactivator that acts as a hindered phenolic antioxidant. Used in conjunction with phenolic antioxidants, phosphites/ phosphonites, thio-synergists and other co-additives. Most suited for PA PE, Rubbers and PP applications. 

Muller, H. Metal deactivators. In Plastics Additives Handbook, 2nd Ed. Gachter, R., Muller, H., Eds. Hanser Munich, 1987 75-95. 

The time to mechanical failure due to thermal oxidation for several nonr-black samples is shown In Figure 3. Here it is seen that the hlgh-denslty polyethylene Is more resistant to thermal oxidation than the low-density material. This can be related to the rate of loss of antioxidant, which Is lost more slowly from the high density polyethylene. Since these are wire insulation samples In contact with copper, the addition of a metal deactivator would further Increase their longevity. 

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