Propane is produced as a by-product of two other processes, natural gas processing and petroleum refining. The processing of natural gas involves removal of butane, propane, and large amounts of ethane from the raw gas, to prevent condensation of these volatiles in natural gas pipelines. Additionally, oil refineries produce some propane as a by-product of cracking petroleum into gasoline or heating oil.

The supply of propane cannot easily be adjusted to meet increased demand, because of the by-product nature of propane production. About 90% of U.S. propane is domestically produced.  The United States imports about 10% of the propane consumed each year, with about 70% of that coming from Canada via pipeline and rail. The remaining 30% of imported propane comes to the United States from other sources via ocean transport.

After it is separated from the crude oil, North American propane is stored in huge salt caverns. Examples of these are Fort SaskatchewanAlbertaMont Belvieu, Texas; and Conway, Kansas. These salt caverns can store 80,000,000 barrels (13,000,000 m3) of propane.



An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion should be used when both phases, dispersed and continuous, are liquids. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include vinaigrettes, homogenized milk, liquid biomolecular condensates, and some cutting fluids for metal working.

Metalworking fluids and other industrial lubricants are typically oil & water emulsions. Emulsifiers allow metalworkers to make use of both the lubricating properties of oils and the cooling capabilities of water. Anionic and nonionic emulsifiers are often used together in metalworking fluids. Cationic emulsifiers are rarely used because they are unstable in the alkaline solutions (pH 8–9.5) required for metalworking fluids.



Normal butane can be used for gasoline blending, as a fuel gas, fragrance extraction solvent, either alone or in a mixture with propane, and as a feedstock for the manufacture of ethylene and butadiene, a key ingredient of synthetic rubberIsobutane is primarily used by refineries to enhance (increase) the octane number of motor gasoline.


When blended with propane and other hydrocarbons, it may be referred to commercially as LPG, for liquefied petroleum gas. It is used as a petrol component, as a feedstock for the production of base petrochemicals in steam cracking, as fuel for cigarette lighters and as a propellant in aerosol sprays such as deodorants.

Very pure forms of butane, especially isobutane, can be used as refrigerants and have largely replaced the ozone-layer-depleting halomethanes, for instance in household refrigerators and freezers. The system operating pressure for butane is lower than for the halomethanes, such as R-12, so R-12 systems such as in automotive air conditioning systems, when converted to pure butane will not function optimally and therefore a mix of isobutane and propane is used to give cooling system performance comparable to R-12.



In material sciences and engineering, the terms "asphalt" and "bitumen" are often used interchangeably to mean both natural and manufactured forms of the substance, although there is regional variation as to which term is most common. Worldwide, geologists tend to favor the term "bitumen" for the naturally occurring material.


For the manufactured material, which is a refined residue from the distillation process of selected crude oils, "bitumen" is the prevalent term in much of the world; however, in American English, "asphalt" is more commonly used. To help avoid confusion, the phrases "liquid asphalt", "asphalt binder", or "asphalt cement" are used in the U.S.


Colloquially, various forms of asphalt are sometimes referred to as "tar", as in the name of the La Brea Tar Pits, although tar is a different material.


Specialty Chemicals

Speciality chemicals are usually manufactured in batch chemical plants using batch processing techniques. A batch process is one in which a defined quantity of product is made from a fixed input of raw materials during a measured period of time.


The batch process most often consists of introducing accurately measured amounts of starting materials into a vessel followed by a series of processes involving mixing, heating, cooling, making more chemical reactions, distillationcrystallization, separation, drying, packaging etc., taking place at predetermined and scheduled intervals.


The manufacturing processes are supported by activities such as the quality testing, storage, warehousinglogistics of the products, and management by recycling, treatment and disposal of by-products, and waste streams.


For the next "batch" the equipment may be cleaned and the above processes repeated.