Ethane

Ethane is a naturally occurring organic chemical compound with the chemical formula C₂H₆. At standard temperature and pressure, ethane is a colorless, odorless gas. It is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining.

Like many hydrocarbons, ethane is mainly used as feedstock for producing ethylene. The ethyl group is formally derived from ethane, although this is rarely done in practice. Ethane is different from related compounds such as ethene, ethyne, or methane.

History

Ethane was first made in 1834 by Michael Faraday. He used a special process called electrolysis on a solution of potassium acetate, but he thought the gas he got was methane and didn’t study it more. Later, from 1847 to 1849, Hermann Kolbe and Edward Frankland made ethane in different ways but also thought they had found something else.

It wasn’t until 1864 that Carl Schorlemmer proved that the gas from these experiments was really ethane. That same year, Edmund Ronalds found ethane mixed in a type of oil from Pennsylvanian fields.

Properties

At normal temperature and pressure, ethane is a colorless, odorless gas. It freezes at very cold temperatures and melts at even colder temperatures. Ethane does not mix well with water.

Ethane can be found as a tiny part of the air we breathe and has also been spotted in the air around other planets and moons, like Titan, one of Saturn’s moons. Scientists believe ethane might have helped form seas on Titan’s surface a long time ago. It is also found in some comets and on the surface of Pluto.

Chemistry

Ethane can react with certain gases, especially chlorine and bromine, in a special kind of reaction. This process creates new substances and releases heat.

When ethane burns, it gives off a lot of energy and makes carbon dioxide and water. If there isn’t enough oxygen, it can make other gases too. At very high temperatures, ethane can change into ethylene, which is used to make many everyday products.

Production

After methane, ethane is the second most common part of natural gas. The amount of ethane in natural gas changes from place to place, ranging from less than 1% to more than 6%. In the past, ethane was often burned with methane as fuel. Now, ethane is important for making chemicals and is separated from natural gas in many places. It can also be taken from petroleum gas, which is made when petroleum is cleaned and prepared.

Ethane is best separated from methane by cooling it to very cold temperatures. One common way to do this uses a special kind of machine called a turboexpander. In this process, gas is cooled by letting it expand through a turbine, making the temperature drop to about −100 °C. At this cold temperature, methane stays a gas while ethane and heavier gases turn liquid. Then, distillation can separate ethane from propane and other heavier gases.

Usage

Ethane is mainly used to make a chemical called ethylene through a process called steam cracking. This process works well with ethane to produce ethylene, unlike using heavier hydrocarbons which create a mix of different chemicals.

Ethane has also been studied for making other important chemicals. For example, it could be used to make vinyl chloride, but this method has faced challenges. Currently, a small plant in Germany tests this idea. Another plant in Saudi Arabia uses ethane to make acetic acid, taking advantage of the low cost of ethane in that area.

Ethane can also act as a cooling agent in very cold refrigeration systems.

In the laboratory

In scientific research, liquid ethane is sometimes used to quickly freeze water-containing samples. This fast freezing prevents the water from forming crystals that could damage the samples and affect the quality of detailed images.

Health and safety

Ethane is a very flammable gas at room temperature. If it mixes with air in amounts between 3.0% and 12.5%, it can explode.

Ethane does not cause cancer.