Octane is one of the most significant substances in today’s world. This is because of thousands of vehicles on the road today demanding nearly fifty to sixty percent of all crude oil refined. With such extremely high demand, the advancement in the chemistry and the refining processes related with octane have been improved in the past few years as the automobile industry is growing and changing rapidly to meet the demands and standards of customers. As these customers continue to demand for more efficiency and power from their vehicles, refineries companies must find new ways and improved ways to produce high quality octane to satisfy these customers. But continuously increasing environmental awareness and hazards of octane have put some new limitations on oil refinery companies.
Most people have heard the word “octane” used in the terms of the hydrocarbon fuel gasoline. In reality octane is the general name for molecules consists of eight carbon atoms. Chemical formula for octane is C8H18. Octane actually has two definitions. (Octane Facts, Internet)
“One is chemical: Octane is a flammable hydrocarbon liquid that along with other hydrocarbons -- pentane, hexane, heptane, and many others -- is refined from crude oil and makes up the blend of chemical components called gasoline.
A second definition: Octane is a measure of a fuel's tendency to knock or ping when it is mixed with air and burned in the cylinder of an engine. This octane rating is not based on the amount of chemical octane in the gasoline. It is called octane because pure hydrocarbon octane is used as a knock standard, with a rating of 100. Gasoline, made from a blend of octane and other hydrocarbons, may have a higher or lower rating, depending on its tendency to knock.”
Normally, octane is used and represented in reference to grades of gasoline. Everyday when we pass or stop by a gasoline station, we see the numbers like 87, 89, and 93. Most people know that this is octane number or the grade of fuel, but very few people know what these numbers and grade of octane actually mean and how a higher priced octane could enhance the performance of car. The octane number or grade is a rating based on a specific range using reference fuels that have been assigned octane numbers from zero to hundred. The octane numbers seen at the petrol station are the arithmetic mean (A.M) of two standard octane testing processes. An octane with rating number of 87 is produced to burn effectively in a normal modern engine with a compression ratio of around eight. The refining companies are using new advanced processes to produce gasoline that will perform better in new advanced vehicles. The typical processes used to purify the octane gasoline are reforming, cracking, and blending.
Catalyst is used in the cracking reactions, catalyst is easier to control. Gasoline yields of ~50% are obtained and higher quality gasoline with an octane grade of around 100 is produced. In this process catalysts tend to crack hydrocarbons near the center of the chain, resulting in improved yields of hydrocarbons.
Reforming has become an increasingly significant process in the purification of octane since its first commercial use fifty years ago. The main aim of reforming process is to convert low octane gasoline into high octane fuel by continuously increasing the fractions of branched and aromatics paraffins.
Catalytic reforming is totally different than catalytic cracking; in cracking its function is to rebuild hydrocarbons with a higher octane number and without changing the numbers of carbon atoms. The most significant reactions in catalytic reforming are paraffin isomerization, dehydrogenation, paraffin dehydrocyclization, and hydrocracking.
In the end, the final products of cracking and reforming are all combined to create a useable octane that goes to the gas stations. Obtaining a desired octane grade through blending process requires a complete knowledge of how the octane rating or grade is affected by the addition of various mixtures.
These reforming reactions have become significant for the purification companies as the demand for improved gasoline has increased from an octane grade of 30 in the beginning of the twentieth century to current grades of 87, 89 and 93.
The greatest hazard of octane is explosion or fire. Liquid Fire can easily ignited by a cigarette, match, hot exhaust pipe, pilot light faulty wiring, or any spark. This is the common and most the greatest problem with all gasoline.
Octane can also be a health hazard. When it comes into contact with human skin, it removes the skin's normal oils and causes it to crack and dry, creating the possibility for secondary infections to occur. Octane fumes can cause dizziness, vomiting and nausea or, in extremely high enough concentrations, death. If vomiting occurs immediately after ingestion, octane vapors can enter the lungs and can cause chemical pneumonia, which can be very dangerous. The higher the octane rating, the more hazardous and dangerous it becomes.
Octane vapors have a mild narcotic effect and might irritate the mucous membranes. Severe exposures to octane may also cause drowsiness, unconsciousness and even death.
Ingestion of octane may produce abdominal pain or nausea. Aspiration into lungs can cause lungs damage and is immediate medial treatment is required.
Physical contact with octane might cause mild irritation, redness or pain.
Eye contact with octane vapors may cause irritation. Splashes may produce redness or pain.
Prolonged or continuous skin contact with octane may cause dermatitis.
Persons with pre-existing skin disorders problems or impaired pulmonary function might be at greater risk to the effects of octane. Production, distribution and consumer use of octane results in environmental effects, including regional and local pollution as well as releases of greenhouse gases like carbon dioxide, which contribute to climate or environment change.
It is possible to recycle a greater proportion of waste, but for economic and technical reasons about thirty per cent of municipal solid waste, which includes octane and other gasoline, is not recyclable and it requires alternative and safe methods of disposal to prevent any environment effects.
Environmental issues associated with the disposal of the octane as a waste are not severe because when released into the air, this substance is expected to have a half-life between one and ten days. But still any amount of octane which cannot be saved for recovery or recycling must be handled and considered as hazardous waste and must be sent to a RCRA approved incinerator or must be disposed in a RCRA approved waste facility area and it should be disposed in accordance with federal, local and state requirements.
(Octane Facts, Internet)
(October 30, 2002)