What is the most common and least expensive method for commercial production of oxygen?

Most Common Method: Air Separation

The most common method for commercial production of oxygen is air separation. This method relies on the fact that air is a mixture of gases, and that oxygen is the most abundant gas in air (about 21% by volume). Air separation is achieved through a process called fractional distillation, which involves cooling and compressing air until it liquefies. The liquefied air is then heated, causing the different gases to evaporate at different temperatures. Oxygen, which has a lower boiling point than other major components of air, is the first gas to evaporate. The evaporated oxygen is then collected and purified to obtain high-purity oxygen.

Least Expensive Method: Pressure Swing Adsorption (PSA)

The least expensive method for commercial production of oxygen is Pressure Swing Adsorption (PSA). PSA is based on the principle that certain materials, known as adsorbents, have a greater affinity for certain gases than others. In PSA, compressed air is passed through a bed of adsorbent material that selectively adsorbs nitrogen, allowing oxygen to pass through. The nitrogen-depleted air is then collected as oxygen-enriched air, which can be further purified if needed. PSA is a relatively simple and energy-efficient process, making it a cost-effective option for small-scale oxygen production.