Naphthenic acid extraction

Aluminum nitrate nonahydrate is prepared by dissolving aluminum or aluminum hydroxide in dilute nitric acid, and crystaUi2ing the product from the resulting aqueous solution. It is made commercially from aluminous materials such as bauxite. Iron compounds may be extracted from the solution with naphthenic acids (21) before hydrate precipitation. In the laboratory it is prepared from aluminum sulfate and barium nitrate. 

Naphthenic acids in the naphtha fraction have a special commercial importance and can be extracted by using dilute caustic solutions. The total acid content of most crudes is generally low, but may reach as much as 3%, as in some California crudes. 

Naphthenic acids and cresylic acid, which are extracted from certain crude oil fractions, are briefly reviewed at the end of the chapter. 

The production of naphthenic acids from middle distillates occurs by extraction with 7-10% caustic solution. 

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. ... 

It should be noted that the extraction of cresylic acid does not create an isolation problem with naphthenic acids which are principally present in heavier fractions. Naphthenic acids, which are relatively stronger acids (lower pKa value), are extracted with less concentrated caustic solution. 

Napalm (Thickened Fuel). An acronym for NAphthenic acid and PALMetate, the former being a petroleum product, while the latter is extracted from palm oils. Napalm was developed by Dr Louis F. Fieser of Harvard University... 

NAPFINING A process for removing naphthenic acids from petroleum fractions by extracting with aqueous alkali, using a bundle of hollow fibers. Developed by the Merichem Company, Houston, TX, and used in 19 plants in 1991. 

Although petroleum basically consists of hydrocarbons, there are smaller amounts of other types of materials. For example, carboxylic acids occur to the extent of about 0.1-3%. These can be isolated quite easily by base extraction and the mixture is known as naphthenic acid, which can be used... 

Aqueous solutions of NaOH or KOH are very effective at removing a variety of compounds from fuel. Components removed by extracting or washing the fuel with either of these caustic solutions include mercaptans, phenols, hydrogen sulfide, and naphthenic acids. Removal of these compounds can improve the color, odor,... 

The commercial production of naphthenic acid from petroleum is based on the formation of sodium naphthenate. Naphthenic acids are recovered by caustic extraction uf petroleum distillates rather than from crude petroleum. Crude naphthenic acid is obtained by acidulating the sodium naphthenate, and can be further refined to remove impurities. 

The use of carboxylic acids for the removal of iron(III) from solutions of the rare-earth metals has been reported,38 but has not been described in detail. The stoichiometries of the extracted complexes of iron(III) have not been clearly established. The n-decanoic acid complex has been variously described as (FeA3)3 and Fe3A9 x(OH) (HA) 51 or [Fe(OH)A2]2 and [Fe(OH)2A-HA]2,57 the H-octanoic acid complex as (FeA3-H20)3,58 the naphthenic acid complex as FeA3,47 and that of Versatic 10 acid as [FeA3(HA)J>, or [Fe(OH)A2]3.59... 

The presence of acid substances in petroleum first appears to have been reported in 1874 and it was established nine years later that these substances contained carboxyl groups and were carboxylic acids. These were termed naphthenic acids. Although alicyclic (naphthenic) acids appear to be the more prevalent, it is now well known that aliphatic acids are also present. In addition to the carboxylic acids, alkaline extracts from petroleum contain phenols. 

In the naphthenic acid (mixture of cyclopentylalkylcarboxylic acids)-petroleum ether systems, Singh et al. (132) found the extracted species of Zn(II), Cd(II), and Hg(II) to be ZnA2HA-H20, CdA2(HA)2, and Hg2A4(HA)4, respectively, and the extraction constant to decrease in the order Hg > Cd > Zn. They also extracted HgA2(HA)2 with hexanoic acid in chloroform (133). 

Fundamental studies have been reported using the cationic liquid ion exchanger di(2-ethylhexyl) phosphoric acid in the extraction of uranium from wet-process phosphoric acid (H34), yttrium from nitric acid solution (Hll), nickel and zinc from a waste phsophate solution (P9), samarium, neodymium, and cerium from their chloride solutions (12), aluminum, cobalt, chromium, copper, iron, nickel, molybdenum, selenium, thorium, titanium, yttrium, and zinc (Lll), and in the formation of iron and rare earth di(2-ethylhexyl) phosphoric acid polymers (H12). Other cationic liquid ion exchangers that have been used include naphthenic acid, an inexpensive carboxylic acid to separate copper from nickel (F4), di-alkyl phosphate to recover vanadium from carnotite type uranium ores (M42), and tributyl phosphate to separate rare earths (B24). 

In addition, a method of petroleum classification has been developed that is based on other properties as well as the density of selected fractions. The method consists of a preliminary examination of the aromatic content of the fraction boiling up to 145°C as well as that of the asphaltene content, followed by more detailed examination of the chemical composition of the naphtha (b.p. <200°C). For this examination, a graph (a composite of curves expressing the relation between percentage distillate from the naphtha, the aniline point, refractive index, specific gravity, and the boiling point) is used. The aniline point after acid extraction is included in order to estimate the paraffin-naphthene ratio. 

FIGURE 8.3-5 Fractional amonnt of extraction of trace levels of some metal cations from aqueous solution into organic solutions of naphthenic acid as a function of pH. From Ref. 18, with permission,... 

Synonyms Carboxylic acids, naphthenic Naphthenic acids Definition Any of a group of sat. higher fatty acids derived from gas-oil fraction of petroleum by extraction with caustic acid sol n. and subsequent acidification... 

Naphthenic acid are most significant environmental contaminants. They are comprised of a large collection of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Moreover, they are toxic components in refinery wastewaters and in oil sands extraction waters. In addition, there are many industrial uses for naphthenic acids, so there is a potential for their release to the environment from a variety of activities. Studies have shown that naphthenic adds are susceptible to biodegradation, which decreases their concentration and reduces toxidty. 

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