Naphthenic acid salts

Using strong caustic solutions for the extraction may create separation problems because naphthenic acid salts are emulsifying agents. Properties of two naphthenic acid types are shown in Table 4-4. ... 

Most of the inhibitors in use are organic nitrogen compounds and these have been classified by Bregman as (a) aliphatic fatty acid derivatives, b) imidazolines, (c) quaternaries, (d) rosin derivatives (complex amine mixtures based on abietic acid) all of these will tend to have long-chain hydrocarbons, e.g. CigH, as part of the structure, (e) petroleum sulphonic acid salts of long-chain diamines (preferred to the diamines), (/) other salts of diamines and (g) fatty amides of aliphatic diamines. Actual compounds in use in classes (a) to d) include oleic and naphthenic acid salts of n-tallowpropylenediamine diamines RNH(CH2) NH2 in which R is a carbon chain of 8-22 atoms and x = 2-10 and reaction products of diamines with acids from the partial oxidation of liquid hydrocarbons. Attention has also been drawn to polyethoxylated compounds in which the water solubility can be controlled by the amount of ethylene oxide added to the molecule. 

Caustic wash fuel to remove naphthenic acids. Naphthenic acid salts are water-soluble. Care should be taken to ensure that emulsification does not result. 

Naphthenic acid salts (copper and zinc salts) (III.6.2.1)... 

Copper quinolinolate (oxine copper) is the chelate of divalent copper and 8-hydroxyquinoline and shares most of its market with copper naphthenate, which is a complex copper salt of mixed naphthenic acids. The principal uses are in wood treatments and some military textiles, where the green color is not objectionable. Copper naphthenate has an odor but is cheaper than oxine. Both copper naphthenate and 2inc naphthenate have performed well in environment tests, with exposure to soil above-ground, as well as concrete (33). 

More than two-thirds of the naphthenic acid produced is used to make metal salts, with the largest volume being used for copper naphthenate, consumed in the wood preservative industry (see Wood). Metal salts used as paint driers accounted for only 16% of the naphthenic acid market in 1993 (see Paint). This is a dramatic contrast with 1977 usage, when 75% of the naphthenates went into the paint drier market. An overall view of the 1993 naphthenic acid market in North America shows the following uses ... 

Oil field uses are primarily imidazolines for surfactant and corrosion inhibition (see Petroleum). Besides the lubrication market for metal salts, the miscellaneous market is comprised of free acids used ia concrete additives, motor oil lubricants, and asphalt-paving applications (47) (see Asphalt Lubrication AND lubricants). Naphthenic acid has also been studied ia ore flotation for recovery of rare-earth metals (48) (see Flotation Lanthanides). 

Free naphthenic acids are corrosive and are mainly used as their salts and esters. The sodium salts are emulsifying agents for preparing agricultural insecticides, additives for cutting oils, and emulsion breakers in the oil industry. 

Other metal salts of naphthenic acids have many varied uses. For example, calcium naphthenate is a lubricating oil additive, and zinc naphthenate is an antioxidant. Lead, zinc, and barium naphthenates are wetting agents used as dispersion agents for paints. Some oil soluble metal naphthenates, such as those of zinc, cobalt, and lead, are used as... 

Salts of nitrogenous molecules with carboxylic acids (fatty acids, naphthenic acids)... 

To mitigate the effects of corrosion resulting from the presence of salts, it is advantageous to reduce the salt concentration to the range of 3 to 5 ppm. Typically, brine droplets in crude oil are stabilized by a mixture of surface-active components such as waxes, asphaltenes, resins, and naphthenic acids that are electrostatically bound to the droplets surface. Such components provide an interfacial film over the brine droplet, resulting in a diminished droplet coalescence. Adding water to the crude oil can decrease the concentration of the surface-active components on the surface of each droplet, because the number of droplets is increased without increasing component concentration. 

Naphthenic acids occur primarily in distillate and some heavy fuel fractions. Topically, caustic treatment effectively removes these compounds. However, even after caustic treatment, alkali salts of heavier naphthenic acids may still remain oil soluble. In fuel, these compounds can act as very effective emulsifying agents. Fuel haze and particulate contamination can be due to these acid salts. Caustic solutions of various strengths can be used to wash fuel. Usually 10 to 20 vol% of a 5% to 10% caustic wash solution is effective for most applications. 

Distillate fuel fractions can contain naphthenic acids, sulfonic acids, and other hydrophilic compounds. If these hydrophilic compounds are present as sodium salts due to caustic washing of fuel, they become powerful emulsifying agents. Also, heavy resinous compounds in fuel can act to stabilize existing emulsions. 

During the processing of fuels and fuel components, solutions of sodium hydroxide or potassium hydroxide may be used. These caustic solutions can react with phenols, mercaptans, and naphthenic acids to form water-soluble salts. As a result, these undesirable components are removed from the fuel as the caustic separates from the fuel. Further water washing can be performed to clear the fuel of residual caustic and salts. 

The rates at which nonconjugated drying oils dry are slow. Metal salts (driers) arc known to catalyze the drying rate. The most widely used are the oil-soluble cobalt, manganese, lead, zirconium, and calcium salts of 2-ethylhexanoic acid or naphthenic acids. See also Paints and Coatings. 

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