The air around us is a mixture of many different gases, but just three elements – nitrogen, oxygen and argon - form nearly all of it. The pie chart shows the amount of these gases in dry air.
Air is the raw material for producing gases. After the gases are extracted, what remains is returned to the atmosphere. Linde (former AGA)’s most important products are oxygen, nitrogen and argon.
The most common technique to separate each gas from the air is by cryotechnology. The prefix “cryo” is Greek and means cold or frost.
The air is condensed and liquefies at -194 °C. Since the different air gases have different boiling-points, you separate the gases through distillation. The first gas to boil is nitrogen with its boiling-point at -196 °C; followed by argon at -186 °C; and finally, oxygen with a boiling point of -183 °C.
The gas with the lowest boiling point separates from the liquefied air first and physically moves upwards. There the temperature is lower and the gas is condensed again and gathered in liquid form.
The noble gases neon, krypton and xenon can be produced in a similar way.
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