Britannica
Sources used in this answer
How is pure oxygen produced from liquid air?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
oxygen group element
Modern version of the periodic table of the elements (printable).
Pure oxygen is produced in large quantities through the fractional distillation of liquid air. This process relies on the fact that oxygen has a higher boiling point and is less volatile than other primary components of air, such as nitrogen and argon.1
The production process involves several key stages:
- Preparation: Air is filtered to remove particulates, and moisture and carbon dioxide are removed using alkali absorption.1
- Compression and Cooling: The air is compressed and cooled. Through repeated cycles of compression and expansion—which cools the gas—the air is eventually liquefied at approximately −196 °C.1
- Distillation: The liquid air is allowed to warm gradually. Because of their different boiling points, the lighter rare gases and nitrogen distill first, leaving behind liquid oxygen.1
Through multiple fractionations, this method can produce oxygen with a purity of 99.5 percent, which is sufficient for most industrial, medical, and aerospace applications.1