Pour point depressant

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Pour point depressants are used to allow the use of petroleum based mineral oils at lower temperatures. The lowest temperature at which a fuel or oil will pour is called a pour point. Wax crystals, which form at lower temperatures, may interfere with lubrication of mechanical equipment. High-quality pour point depressants can lower a pour point of an oil additive by as much as 40°C. [1]

Contents

Methods

Pour point depressants do not lower the temperature at which wax crystals begin to form, called the cloud point, or the amount of wax that is formed—pour point depressants work by altering the crystal shape and size, which inhibits lateral crystal growth. There are two known methods by which this may be achieved: surface adsorption and co-crystallization. [1]

Types

Any reduction in an oil's pour point depends on both the composition and properties of the oil, as well as the type of pour point depressant used. Other factors are the substance's relative molecular weight, its chemical composition, and the substance's concentration in the oil. If the concentration of pour point depressant is too high, there may be a visible effect on viscosity at higher temperatures. [2]

Pour point depressants are only effective on refined oils. Non-refined oils contain polyaromatic hydrocarbons and resins which act as antagonists against synthetic pour point depressants. Pour point depressants are also ineffective for engine oils with a viscosity above SAE 30. [3] Generally they are most effective on thinner oils like SAE 10, SAE 20 or SAE 30 grade oils. [2]

Alkylaromatics and aliphatic polymers are two types of pour point depressants that are commercially available. Most commercially available pour point depressants are organic polymers, but nonpolymeric substances such as phenyltristearyloxysilane and pentaerythritol tetrastearate may also be effective. [1]

Winter 1980-1981

In 1981 there was a problem with lubricating oil pumpability. The same thing happened the following winter, along with reports that oil would not flow out of containers. The issue seemed to be caused by olefin copolymers which caused the oil to gel in cold temperatures. [2]

Related Research Articles

A lubricant is a substance, usually organic, introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity.

Paraffin wax Soft colorless solid derived from petroleum, coal or shale oil

Paraffin wax is a soft colorless solid derived from petroleum, coal or shale oil that consists of a mixture of hydrocarbon molecules containing between twenty and forty carbon atoms. It is solid at room temperature and begins to melt above approximately 37 °C (99 °F), and its boiling point is above 370 °C (698 °F). Common applications for paraffin wax include lubrication, electrical insulation, and candles; dyed paraffin wax can be made into crayons. It is distinct from kerosene and other petroleum products that are sometimes called paraffin.

Vegetable oil

Vegetable oils, or vegetable fats, are oils extracted from seeds, or less often, from other parts of fruits. Like animal fats, vegetable fats are mixtures of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of fats from seeds. Olive oil, palm oil, and rice bran oil are examples of fats from other parts of fruits. In common usage, vegetable oil may refer exclusively to vegetable fats which are liquid at room temperature. Vegetable oils are usually edible; non-edible oils derived mainly from petroleum are termed mineral oils.

Tallow rendered form of beef or mutton fat

Tallow is a rendered form of beef or mutton fat, primarily made up of triglycerides. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.

Motor oil Lubricant used for lubrication of internal combustion engines

Motor oil, engine oil, or engine lubricant is any one of various substances that consist of base oils enhanced with various additives, particularly antiwear additives, detergents, dispersants, and, for multi-grade oils, viscosity index improvers. Motor oil is used for lubrication of internal combustion engines. The main function of motor oil is to reduce friction and wear on moving parts and to clean the engine from sludge and varnish (detergents). It also neutralizes acids that originate from fuel and from oxidation of the lubricant (detergents), improves sealing of piston rings, and cools the engine by carrying heat away from moving parts.

Hydraulic fluid

A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. Examples of equipment that might use hydraulic fluids are excavators and backhoes, hydraulic brakes, power steering systems, transmissions, garbage trucks, aircraft flight control systems, lifts, and industrial machinery.

Cutting fluid

Cutting fluid is a type of coolant and lubricant designed specifically for metalworking processes, such as machining and stamping. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. Cutting fluids are made from petroleum distillates, animal fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant.

Synthetic oil

Synthetic oil is a lubricant consisting of chemical compounds that are artificially made. Synthetic lubricants can be manufactured using chemically modified petroleum components rather than whole crude oil, but can also be synthesized from other raw materials. The base material, however, is still overwhelmingly crude oil that is distilled and then modified physically and chemically. The actual synthesis process and composition of additives is generally a commercial trade secret and will vary among producers.

Gear oil

Gear oil is a lubricant made specifically for transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery. It is of a high viscosity and usually contains organosulfur compounds. Some modern automatic transaxles do not use a heavy oil at all but lubricate with the lower viscosity hydraulic fluid, which is available at pressure within the automatic transmission. Gear oils account for about 20% of the lubricant market.

Petroleum product

Petroleum products are materials derived from crude oil (petroleum) as it is processed in oil refineries. Unlike petrochemicals, which are a collection of well-defined usually pure chemical compounds, petroleum products are complex mixtures. The majority of petroleum is converted to petroleum products, which includes several classes of fuels.

The viscosity index (VI) is an arbitrary, unit-less measure of a fluid's change in viscosity relative to temperature change. It is mostly used to characterize the viscosity-temperature behavior of lubricating oils. The lower the VI, the more the viscosity is affected by changes in temperature. The higher the VI, the more stable the viscosity remains over temperature fluctuations. The VI was originally measured on a scale from 0 to 100; however, advancements in lubrication science have led to the development of oils with much higher VIs.

Grease is a solid or semisolid lubricant formed as a dispersion of thickening agents in a liquid lubricant. Grease generally consists of a soap emulsified with mineral or vegetable oil.

Zinc dithiophosphate Lubricant additive

Zinc dialkyldithiophosphates are a family of coordination compounds developed in the 1940s that feature zinc bound to the anion of a dialkyldithiophosphoric acid. These uncharged compounds are not salts. They are soluble in nonpolar solvents, and the longer-chain derivatives easily dissolve in mineral and synthetic oils used as lubricants. They come under CAS number 68649-42-3. In aftermarket oil additives, the percentage of ZDDP ranges approximately between 2 and 15%. Zinc dithiophosphates have many names, including ZDDP, ZnDTP, and ZDP.

An oil is any nonpolar chemical substance that is a viscous liquid at ambient temperatures and is both hydrophobic and lipophilic. Oils have a high carbon and hydrogen content and are usually flammable and surface active. Most oils are unsaturated lipids that are liquid at room temperature.

Sperm oil

Sperm oil is a waxy liquid obtained from sperm whales. It is a clear, yellowish liquid with a very faint odor. Sperm oil has a different composition from common whale oil, obtained from rendered blubber. Although it is traditionally called an "oil", it is technically a liquid wax. It is composed of wax esters with a small proportion of triglycerides, an ester of an unsaturated fatty acid and a branched-chain fatty alcohol. It is a natural antioxidant and heat-transfer agent. In the late-18th and early-19th centuries, sperm oil was prized as an illuminant for its bright, odorless flame and as a lubricant for its low viscosity and stability. It was supplanted in the late 19th century by less expensive alternatives such as kerosene and petroleum-based lubricants. With the 1987 international ban on whaling, sperm oil is no longer legally sold.

Polyphenyl ether

Phenyl ether polymers are a class of polymers that contain a phenoxy or a thiophenoxy group as the repeating group in ether linkages. Commercial phenyl ether polymers belong to two chemical classes: polyphenyl ethers (PPEs) and polyphenylene oxides (PPOs). The phenoxy groups in the former class of polymers do not contain any substituents whereas those in the latter class contain 2 to 4 alkyl groups on the phenyl ring. The structure of an oxygen-containing PPE is provided in Figure 1 and that of a 2, 6-xylenol derived PPO is shown in Figure 2. Either class can have the oxygen atoms attached at various positions around the rings.

Oil additives are chemical compounds that improve the lubricant performance of base oil. The manufacturer of many different oils can utilize the same base stock for each formulation and can choose different additives for each specific application. Additives comprise up to 5% by weight of some oils.

Dry lubricants or solid lubricants are materials that, despite being in the solid phase, are able to reduce friction between two surfaces sliding against each other without the need for a liquid oil medium.

Automotive oil recycling

Automotive oil recycling involves the recycling of used oils and the creation of new products from the recycled oils, and includes the recycling of motor oil and hydraulic oil. Oil recycling also benefits the environment: increased opportunities for consumers to recycle oil lessens the likelihood of used oil being dumped on lands and in waterways. For example, one gallon of motor oil dumped into waterways has the potential to pollute one million gallons of water.

Base oils are used to manufacture products including lubricating greases, motor oil and metal processing fluids. Different products require different compositions and properties in the oil. One of the most important factors is the liquid’s viscosity at various temperatures. Whether or not a crude oil is suitable to be made into a base oil is determined by the concentration of base oil molecules as well as how easily these can be extracted.

References

  1. 1 2 3 Fuels and Lubricants Handbook. ASTM International.
  2. 1 2 3 Mortier, R. M.; Orszulik, S. T. (2012-12-06). Chemistry and Technology of Lubricants. Springer. ISBN   978-1-4615-3272-9.
  3. Stepina, V.; Vesely, V. (1992-12-04). Lubricants and Special Fluids. Elsevier. ISBN   978-0-08-087587-3.