Nitrogen is an inert gas that is often used to treat various materials or parts at high temperatures in a protective atmosphere. To this end, impurities (oxygen and water vapor) in nitrogen should be removed to the lowest level.

In general, when the oxygen content of nitrogen taken by the nitrogen production mechanism is less than 0.5%, it is appropriate to use deoxidizer directly, when the oxygen content is 0.5-3%, it is appropriate to use catalyst hydrogenation deoxygenation, and when the oxygen content is greater than 3%, fractional catalytic deoxygenation can be used. Because the oxygen content of nitrogen is too high, the amount of hydrogen required by stoichiometry is large, and there may be a risk of explosion when all are added at one time. And the heat released in the reaction is large, easy to burn the catalyst. Therefore, the amount of hydrogenation must be strictly controlled for fractional deoxygenation. When the oxygen content of raw nitrogen is too high, the raw gas can also be diluted with part of pure nitrogen, so that the oxygen content of the mixed gas is less than 3% and then hydrogenated catalytic deoxygenation.

The typical process of using deoxidizer to remove impurity oxygen: nitrogen is passed through catalytic deaerator (to remove oxygen), water cooler and adsorption dryer (to remove water vapor), gas filter (to remove dust particles) to obtain pure nitrogen products.

The typical process of hydrogenation catalytic deoxygenation is adopted: first add an appropriate amount of hydrogen in nitrogen (the addition amount is more than twice the oxygen content of nitrogen), and then pass the catalytic deaerator (to remove oxygen), water cooler and adsorption in the dryer (to remove water vapor), gas filter (to remove dust particles) to obtain pure nitrogen products.

When the oxygen content of nitrogen is large (greater than 3%), the fractional hydrogenation catalytic deoxygenation process can be used. Before nitrogen enters the catalytic deoxygenator, the amount of hydrogenation needs to be strictly controlled. Through catalytic deoxygenator 1(primary deoxygenation), a small amount of hydrogen is added into catalytic deoxygenator 2 for secondary deoxygenation.

If the oxygen content of raw nitrogen is high, excess hydrogen is not required for pure nitrogen. At this time, the nitrogen purification device uses hydrogenation catalytic deoxygenation first, and then purification of nitrogen with activated copper oxide and other methods of dehydrogenation, the typical process flow is: in the raw nitrogen according to the oxygen content, add slightly excess hydrogen (according to stoichiometric) through the catalytic deoxygenator deoxygenation, and then through the electric heater and oxidation reaction to remove excess hydrogen in nitrogen. In addition to active copper oxide, the commonly used dehydrogenation agent can also be silver molecular sieve.