Purifying method for nitric oxide gas with 3N purity

Abstract

The invention discloses a purification method of nitrogen oxide with 3N purity, which comprises the following steps: carrying out the decomposion of sodium nitrite with dilute sulfuric acid, alkali liquor absorption, gas and liquid separation, and drying and separating to obtain the gas, wherein the gas after being dried positively passes through a polyethylene glycol-methacrylate copolymer adsorption zone under the conditions that the temperature is minus 20 DEG C to 30 DEG C and the pressure is 0.5 MPa to 1.5 MPa; and then collecting the gas after being absorbed. By adopting a polyethylene glycol-methacrylate copolymer as an adsorbent, the disproprotionation of the nitrogen oxide and oxidation reaction can be effectively restrained, so that the impurity contents of nitrogen dioxide and nitrous oxide are reduced, and the purity of the nitrogen oxide is improved; the purity of the nitrogen oxide after being purified is larger than 99.9 percent; the content of the nitrogen dioxide is less than 20 ppm; and the content of the nitrous oxide is less than 50 ppm. Particularly, by adopting the secondary circulating adsorption process, foreign gas is positively absorbed, and simultaneously the negative decompression is performed to regenerate the absorbent. The invention has the advantages of simple operation process and low cost.

Description

Technical field: [0001] The invention relates to a gas purification method, in particular to a purification method of 3N (99.9%) pure nitric oxide gas with simple operation process, low cost and high purity. Background technique: [0002] At present, nitric oxide has played a unique role in various fields such as medicine, electronics, and chemical industry. For example, it can be used as an emergency terminator in the production of PVC to quickly terminate the polymerization of PVC monomer in the reactor when there is a power failure or an emergency. In order to prevent the temperature in the kettle from being too high to explode and avoid dangerous accidents, it has obvious advantages over the liquid-type termination additives used in the production of PVC in the past. It does not require N 2 As a carrier gas, combined with PVC monomer, it has strong ability, fast speed and long shelf life. However, in general, nitric oxide gas contains nitrogen dioxide gas, and nitrogen ...

AI Technical Summary

Problems solved by technology

However, in general, nitric oxide gas contains nitrogen dioxide gas, and nitrogen dioxide gas can be combined with PVC monomer to form explosive chelate, which has potential safety hazards. Therefore, it is necessary to strictly control the amount of nitrogen dioxide charged into the reactor The nitrogen dioxide content in the nitrogen monoxide gas stream shall not exceed 50ppm, and the purity of the nitrogen monoxide shall not be less than 3N

[0003] There are multiple methods for producing nitric oxide. U.S. Patent No. 3,663,167 points out that ammonia is oxidized in the air to prepare it, but the conditions required for this method are relatively high and difficult to realize; Nitrogen oxide gas, the disadvantage of this method is that the content of impurities (sulfur dioxide) is too much, and it is troublesome to remove; there is another method that uses sodium nitrite and dilute sulfuric acid to react to produce nitric oxide. The production process is to combine sodium nitrite with dilute sulfuric acid React in the reaction pool to generate sodium sulfate and sodium nitrate solutions as well as NO, H 2 O, while also producing NO 2 , N 2 O, N 2 , SO 2 , water vapor and other impurities, and sometimes a small amount of CO 2 (Air into the impact), etc.; the remaining reaction solution and generated sodium sulfate and sodium nitrate solution and a small amount of CO 2 , a small part of SO 2 , NO 2 Separation and removal from the bottom of the reactor by alkaline absorption and water washing, most of the NO 2 , N 2 O, water vapor, etc. flow out from the top of the reactor in gaseous form along with NO; water vapor is absorbed and removed in the dryer where the gas flow passes through the presence of anhydrous calcium chloride, and the operation is simple

[0004] Because nitric oxide is easy to combine with oxygen to generate nitrogen dioxide, and nitric ox

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