Butane is one of the lightest liquid streams typically produced in a refinery. The butane molecule has four carbon atoms and 10 hydrogen atoms. Butane is typically either blended into gasoline or LPG (in small volumes) or sold directly as a finished product. When blending into gasoline, butane is favored for its high octane but limited by its high vapor pressure. Because of vapor pressure limits, what is butane blending into gasoline is often completely eliminated in warmer months of the year, resulting in a seasonal glut of butane.

So you have probably read somewhere, or have perhaps been told, that propane and butane are both forms of LPG gas - but what exactly does that mean and what are the similarities and differences between the two? Before we get into that, let’s first take a look at LPG and what it is. Liquefied petroleum gas (LPG) is a term widely used to describe a family of light hydrocarbon gases. The two most well known gases in this family are propane and what is butane.

Both of these gases have commercial and residential uses as well as similar qualities, this means people often get confused between the two. The gases can both be used as a fuel in heating, cooking, hot water, vehicles, refrigerants and much more. As a commercial finished product, butane is used as a home heating fuel, as cigarette lighter fluid, as a refrigerant gas, and as a propellant, but all of these require in fairly small volumes.
Butane is also frequently converted into isobutane for use as an alkylation feedstock. It is sometimes used as a refinery fuel, but this is typically its lowest-value end use and avoided where possible.

What is propane and what is butane?
Propane, which comes from natural gas processing and oil refining, is a flammable hydrocarbon gas that is liquefied through pressurization. It is commonly used for heating and cooking, but can be used for a wide range of residential and commercial uses from home water heaters to powering a restaurant’s kitchen. Meanwhile, butane is also a flammable hydrocarbon gas that comes from natural gas processing and oil refining. Butane on the other hand, is more commonly used as a fuel, propellant and refrigerant.
If they are so similar, why does it matter about their differences? Despite both having similar qualities, there are certain differences between propane and butane which could be either advantageous or disadvantageous depending on how you intend to use them.