This is the sixth most common element
occupying 78% of the Earth’s atmosphere. It is separated from air both through
cryogenic distillation and non-cryogenic molecular sieve absorption under pressure. It is
a chemically inert gas and therefore is extensively used in industrial process, which
needs to take place in an oxygen free environment. Nitrogen, in liquid form, is intensely
cold (-95.8° C) and freezes organic matter such as foodstuff almost instantaneously.
First isolated in the late
18th century, oxygen, in contrast to nitrogen, is useful for its reactivity. It is also
essential to life, both for respiration and in the form of its most important compound
– water. It supports combustion, making it ideal for improving the fuel burning
efficiency. Simultaneously it suppresses formation of NOx and SOx. Air, enriched in
oxygen, carries less nitrogen by volume, making it ideal for de-bottlenecking a variety of
air based processes. Oxygen is vital to healthcare, simulates micro organisms in
fermentation and reduces Biological Oxygen Demand in wastewaters.
Argon makes up a tiny fraction of the
atmosphere and together with Xenon, Krypton and Neon is classified as "Noble
Gases". Its chemical stability makes it suitable for a variety of industrial uses.
These gases, also called rare gases are found
in minute quantities in the atmosphere. All these gases produce light when an electric
current is passed through them.
Helium forms one part in 186,000 parts of the
Earth’s atmosphere but is found in Natural Gas through radioactive decay and is
extracted from such gas deposits. Only a few sources in the world contain a significant
proportion of helium to justify its separation. Because of its high value, helium is the
only major industrial gas to be extensively traded.
Carbon dioxide is normally recovered for
industrial purposes from the flue gases or as a by-product of ammonia or hydrogen
manufacture. Its inert qualities make it useful as a combustion suppressant but its major
use is as refrigerant or freezing agent. Carbon dioxide freezes at 78.5° C and sublimes
into gas from liquid phase. Dissolved in water, it produces slightly acidic solution which
is used for neutralizing or killing bacteria.
Hydrogen is not only the simplest chemical
element but also the most common, forming 75% of the mass of the universe. It combines
readily with oxygen – a property utilized in rocket propellants. It is produced
through electrolysis of water or through reforming of hydrocarbons such as methane or
natural gas. It also happens to be a natural reducing agent.
The most common production method is
hydration of Calcium Carbide, but is also produced through pyrolysis or cracking of
natural gas or liquid hydrocarbon feeds. It burns with a high intensity flame in
combination with oxygen gas.
