Petroleum waxes

Petroleum wax is of two general types the paraffin waxes in petroleum distillates and the microcrystalline waxes in petroleum residua. The melting point of wax is not directly related to its boiling point, because waxes contain hydrocarbons of different chemical structure. Nevertheless, waxes are graded according to their melting point and oil content. 

Paraffin wax is a solid crystalline mixture of straight-chain (normal) hydrocarbons ranging from C20 to C30 and higher. Wax constituents are solid at ordinary temperatures (25°C, 77°F) whereas petrolatum (petroleum jelly) does contain both solid and liquid hydrocarbons. 

Wax recrystallization, like wax sweating, separates wax into fractions but, instead of rel5nng upon differences in melting points, the process makes use of the different solubility of the wax fractions in a solvent such as a ketone. When a mixture of ketone and wax is heated, the 

This method of producing wax fractions is much faster and more convenient than sweating and results in a much more complete separation of the various fractions. Furthermore, recrystallization can also be applied to the microcrystalline waxes obtained from intermediate and heavy paraffin distillates, which cannot be sweated. Indeed, the microcrystalline waxes have higher melting points and differ in their properties from the paraffin waxes obtained from light paraffin distillates, and thus, wax recrystallization has made new kinds of waxes available. 

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Petroleum wax is used in the manufacture of candles, polishes, ointments and for waterproofing purposes. Waxes are also used as a cracking feedstock for the production of 1-alkene.s for conversion to detergents. 

Fig. 5. Effect of alumina trihydrate on the oxygen index of flexible PVC (30) having 5 phr Tribase XL, 3 phr Sb202, 0.05 phr petroleum wax, and (—...

Detergents have been manufactured from long-chain alkenes and sulfuhc acid, especially those obtained from shale oil or cracking of petroleum wax. These are sulfated with 90—98 wt % acid at 10—15°C for a 5-min contact time and at an acid—alkene molar ratio of 2 1 (82). Dialkyl sulfate initially forms when 96 wt % acid is added to 1-dodecene at 0°C, but it is subsequently converted to the hydrogen sulfate in 80% yield upon the further addition of sulfuhc acid. The yield can be increased to 90% by using 98 wt % sulfuhc acid and pentane as the solvent at -15°C (83). 

Geresin wax [8001 -75-0] originally was a refined and bleached o2okerite wax, but now is a paraffin wax of very narrow molecular weight distribution or blend of petroleum waxes. 

Petroleum Waxes. Waxes derived from petroleum are hydrocarbons of three types paraffin [64742-43-4] (clay-treated) sernimicrocrystaUine or intermediate and microcrystalHne [64742-42-3] (clay-treated). SernimicrocrystaUine waxes are not generally marketed as such (7). Others include acid-treated, chemically neutrali2ed, and hydrotreated and paraffin and hydrocarbon waxes, untreated. The quaHty and quantity of the wax separated from the cmde oil depends on the source of the cmde oil and the degree of refining to which it has been subjected prior to wax separation. Petroleum waxes are produced in massive quantities throughout the world. Subject to the wax content in the cmde, paraffin and, to a substantially lesser degree, microcrystalHne wax are produced in almost all countries of the world that refine cmde oil. Production capacity in the United States and imports for the years 1990 to 1995 are Hsted in Table 2. Canada suppHes over 50% of the petroleum wax imported into the United States (3). 

A paraffin wax is a petroleum wax consisting principally of normal alkanes. MicrocrystalHne wax is a petroleum wax containing substantial proportions of branched and cycHc saturated hydrocarbons, in addition to normal alkanes. SernimicrocrystaUine wax contains more branched and cycHc compounds than paraffin wax, but less than microcrystalHne. A classification system based on the refractive index of the wax and its congealing point as... 

Paraffin wax is macrocrystalline, britde, and is composed of 40—90 wt % normal alkanes, with the remainder C g—isoalkanes and cycloalkanes. Paraffin wax has Httle affinity for oil content fully refined paraffin has less than 1 wt % cmde scale, 1—2 wt %, and slack [64742-61-6] above 2 wt %. Within these classes, the melting point of the wax determines the actual grade, with a range of about 46—71°C. Typical properties of petroleum waxes are listed in Table 3. 

Fig. 1. Refining of petroleum waxes. Courtesy of Baker PetroHte Corporation.

Oil Content. The production of petroleum waxes involves the removal of oil therefore, the oil content (actually the percentage of oil and low molecular weight fractions) is one indication of the quaUty of the wax. Oil content is deterrnined (ASTM D721) as that percentage of the wax soluble in methyl ethyl ketone at —31.7 C. 

Infrared Spectroscopy (ir). Infrared curves are used to identify the chemical functionality of waxes. Petroleum waxes with only hydrocarbon functionality show slight differences based on crystallinity, while vegetable and insect waxes contain hydrocarbons, carboxyflc acids, alcohols, and esters. The ir curves are typically used in combination with other analytical methods such as dsc or gc/gpc to characterize waxes. 

Petroleum Waxes—Charactericyation, Peformance, andMdditives, STAP No. 2, Technical Association of the Pulp and Paper Industry, Atlanta, Ga., 1963,... 

Chemical Designations - Synonyms Petroleum wax Chemical Formula Not pertinent. 

SFC Petroleum wax Atmospheric and vacuum residues Lube oil additives Open tubular FID... 

The pour point of a crude oil or product is the lowest temperature at which an oil is observed to flow under the conditions of the test. Pour point data indicates the amount of long-chain paraffins (petroleum wax) found in a crude oil. Paraffinic crudes usually have higher wax content than other crude types. Handling and transporting crude oils and heavy fuels is difficult at temperatures helow their pour points Often, chemical additives known as pour point depressants are used to improve the flow properties of the fuel. Long-chain n-paraffins ranging from 16-60 carhon atoms in particular, are responsible for near-ambient temperature precipitation. In middle distillates, less than 1% wax can be sufficient to cause solidification of the fuel. ... 

Oil content, %, as described in ASTM Standard D721-65T, Oil Content of Petroleum Waxes ... 

Most companies in the consumer products industries realize that their products and processes must be continually changed to compete with other items that are attempting to replace them. Sometimes almost a complete replacement occurs within a short time and a company may be forced to close plants unless an alternate use of its products is found. As an example, consider the case of petroleum waxes. In the late 1950s the dairy industry consumed 220,000 tons per year of petroleum waxes for coating paperboard cartons and milk bottle tops. This was 35% of the total U.S. wax production. By 1966 this market had dropped to 14% of its former level (25,000 tons / yr) because polyethylene and other coatings had replaced it.1... 

Petroleum vacuum residua, 48 589-591. See also Petroleum residua (resid) nitrogen and oxygen in, 48 590 Petroleum waxes, 48 670-671 26 214-218 applications for, 26 218 production of, 26 216... 

This process seems much simpler than the Ziegler process, and you may wonder why it has not crowded Ziegler out. The problem is the olefin feed. Where do you get a ready supply of olefins the right size to feed to the process The answer is you have to malce them, and therein lies the rub. Normal paraffins from petroleum waxes or other chemical processes provide the feedstock to a two-step process, chlorination and dehydrochlorination, which produces an olefin corresponding to the paraffin. 

Nomenclature Panel of Standardization Subcommittee No. 8, Petroleum Waxes, J. Inst. 

Kalvoort, Moser, and Verver (27) in 1937, relating to petroleum waxes... 

D.S. Partridge W.S.1 Partridge, USP 3148095(1964) CA 62, 2662(1965) (A blasting mixt which detonates in the presence of a certain amt of water is prepd from FGAN prill coated successively with paraffin, a mixt of gilsonite with.A145 Petroleum Wax, mica and AX)... 

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