CS269255B1 - Method of raw nitrogen purifying - Google Patents

Abstract

Method for purifying crude nitrogen as a by-product of low temperature air rectification on pure nitrogen with oxygen content in hundreds to tens of ppm mol. oxygen, wherein ae nitrogen is mixed with 1.0 up to 1.2 times the theoretical amount of hydrogen required for the consumption of the present oxygen and reported at 50 ° C. up to 60 ° C and load from 2,000 to 10,000 h ” to a catalyst containing 0.2 to 0.6% wt. palladium and / or platinum on gamaalumine.

Description

EN 269 255 B1 1

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to purified crude nitrogen, which falls as a by-product of low-temperature air refining in the industrial production of pure oxygen and nitrogen.

According to the current technological arrangement, 30 to 50% of crude nitrogen containing 2 to 5% oxygen is to be withdrawn from the rectification column. This intermediate product is discharged after the heat exchange as an unusable gas mixture and causes energy losses to the rectification process. The head of the column leaves the product, pure nitrogen with the order of oxygen in hundreds of moles. ppm, which, after heat exchange, is conducted to a purification process in which nitrogen is heated by preheating after mixing with 1.5 to 2 moles. % hydrogen, conducted at 150 ° C to a palladium catalyst and nitrogen is obtained with a content of about 10 moles. ppm oxygen. Furthermore, this product is used by a synthesis gas producer (ammonia synthesis) to fill all types of inert atmospheres or pressurized cylinders.

In addition to the aforementioned disadvantage, energy losses are due to the draining of raw nitrogen, the existing method of operation does not allow to increase nitrogen production at its increased consumption and to produce nitrogen of other quality.

However, it has now been found that even a fraction of the nitrogen gas which contains 2 to 5% of oxygen is purified to nitrogen suitable for further syntheses or as an inert atmosphere.

A method for purifying crude nitrogen as a by-product of a low temperature air recrystallization containing 2-5 moles. oxygen to nitrogen with a content of about 100 ppm mol of oxygen by flameless combustion of the addition of hydrogen on metal-containing catalysts of the VIII group of the periodic system on an inert support, the residual oxygen content optionally being reduced to a final content of up to 10 ppm mol. 0g in the second stage after mixing with 1.5 to 2 mol%. % of hydrogen at 150 ° C on a palladium wax catalyst, according to the invention, in that nitrogen having a content of 2 to 5 mol% of the catalyst is based on the invention. Oxygen, after mixing with the dibble containing up to 200 ppm mol. oxygen, is mixed with hydrogen to a hydrogen content of 1.0 to 1.2 times the theoretical amount for total oxygen consumption to burn hydrogen and is conducted at 50 to 200 ° C and a load of 1000 to 10,000 h -1 on catalyst % containing 0.2 to 0.6 wt. platinum and / or palladium on gamma-alumina, then the gas is removed for consumption or the final oxygen content is purified in a manner known per se. In the process for purifying the crude nitrogen of the present invention, a stream of crude nitrogen from the degassing column is fed to a blower suction which is fed with additional hydrogen and then passed to an additional reactor, where oxygen is removed catalytically. pre-treated nitrogen, further leads to consumption or finishing of the second stage purification.

The method is further illustrated by the following examples. Example 1 -

Crude nitrogen deriving from the rectification separation of liquid air containing 2.1 mol. % oxygen is mixed with pure hydrogen such that the resulting gas mixture contains 50 moles of hydrogen, 21 moles of oxygen, and 1,000 moles of nitrogen. The resulting mixture was preheated to 120 ° C on a layer-porous catalytically inactive material and passed to a platinum-deposited gamma-alumina catalyst bed of 0.41% by weight. relative to the carrier. Reaction conditions are as follows: 1400,152,000 temperature (° C) pressure (MPa) load (h “^)

The gas leaving the reactor is cooled, dried and subjected to anelytic analysis. The content of the main components (permanent gases) is as follows (0 mol): nitrogen oxygen hydrogen 99.1 0.01 0.8

Claims (1)

2 EN 269 255 B1 ·. Example 2 Crude nitrogen dropping and rectifying liquid air separation containing 2.1 mol. % oxygen is mixed with pure nitrogen (overhead product) with an oxygen content of 0.01 mol. % in such a ratio that the resulting mixture contains 0.5 mol%. oxygen. This mixture is mixed with the pure hydrogen and the resulting gas mixture and the following molar content (in moles). 41 wt. with respect to the carrier. The reaction conditions are as follows: temperature (° C) 140 pressure (MPa) 0.15 load (H 2) 2,000 The gas leaving the reactor is further fed to a purification process where a 10 ppm purity product is achieved under normal technological conditions mol. BACKGROUND OF THE INVENTION A method for purifying crude nitrogen as a by-product of low temperature air recrystallization with up to 5 mol%. oxygen to nitrogen with about 100 ppm mol. of carbon by flameless combustion of the addition of hydrogen on metal-containing catalysts VIII. groups of the periodic system on an inert support, the residual oxygen content being optionally reduced to a final content of up to 10 moles. ppm g in the second stage after mixing with 1.5 to 2 mol% hydrogen at 150 ° C on a palladium support catalyst, characterized in that nitrogen having a content of 2 to 5 mol. oxygen is mixed with hydrogen to a hydrogen content of 1.0 to 1.2 times the theoretical amount for complete oxygen uptake to burn hydrogen and is conducted at 80 to 200 ° C, if appropriate, with nitrogen containing up to 200 ppm mol of oxygen. C and a load of 1,000 to 10,000 h-1 per catalyst containing 0.2 to 0.5 wt. platinum and / or palladium on gamma-alumina, then the gas is removed for consumption or purified to the final oxygen content.