Process for preparing ultrapure nitric acid

A preparation process, pure nitric acid technology, applied in the field of ultra-high-purity nitric acid preparation process, can solve the problems of unstable product quality, large fluctuations in purity, and high cost, and achieve the goal of overcoming unstable product quality, improving purity, and stabilizing quality Effect

Inactive Publication Date: 2011-04-06
SHANGHAI CHEM REAGENT RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a preparation process for ultra-high-purity nitric acid with good separation effect, low impurity

Method used

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  • Process for preparing ultrapure nitric acid
  • Process for preparing ultrapure nitric acid
  • Process for preparing ultrapure nitric acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Industrial nitric acid pretreatment before rectifying of embodiment 1

[0028] The ultrapure water and the silver nitrate are respectively prepared into a 1-10wt% silver nitrate solution, and the barium nitrate is prepared into a 1-10wt% barium nitrate solution.

[0029] Add industrial nitric acid in the rectification preprocessor 1, at room temperature, drip 1-10wt% silver nitrate solution and 1-10wt% barium nitrate solution under stirring respectively, make the anion Cl in the nitric acid - and SO 4 2- React with silver nitrate and barium nitrate to precipitate silver chloride and barium sulfate, and use 0.1μm perfluorinated membrane filter 2 to perform membrane filtration to obtain the impurity-removing anion Cl - and SO 4 2- The pretreatment liquid is transported to the rectification tower 4 tower kettle with the delivery pump 3 to carry out the next process. The test results of the pretreatment solution are shown in Table 1.

[0030] Table 1 Industrial nitric...

Embodiment 3

[0040] Influence of the hydrophilic microporous membrane demister 5 composed of perfluorosulfonic acid resin on the rectification result of embodiment 3

[0041] The rectification is carried out under the condition that the temperature of the 4th column of the rectification tower is 125-127 °C, and the flow rate of the pretreatment liquid into the tower is 2.0kg / h. The microporous membrane demister 5 prevents metal ions or solid particles from mixing into the steam to remove mist impurity particles in the steam. The test results are shown in Table 3.

[0042] Table 3 The impact of the hydrophilic microporous membrane demister on the top of the tower on the rectification result

[0043]

[0044]

[0045] As can be seen from Table 3, whether there is a hydrophilic microporous membrane eliminator 5 composed of perfluorosulfonic acid resin at the top of the rectification tower has a significant impact on the quality of the ultra-high-purity nitric acid product. During recti...

Embodiment 4

[0046] Embodiment 4 air cleaning and nitric acid blowing white

[0047] The unpurified air is filtered through the secondary membrane respectively, that is, the mist impurity particles in the gas are removed through the hydrophilic microporous membrane filter 17 composed of perfluorosulfonic acid resin, the oxygen concentration is increased, and then passed through the polyethersulfone ( PES) hollow fiber gas separation membrane membrane filter 16 removes trace acid gas SO in gas 2 , CO 2 、H 2 S and other impurities, that is, to obtain the purified air required for whitening. The test results before and after air purification are shown in Table 4.

[0048] Table 4 Test results before and after air purification

[0049] name

[0050] It can be seen from Table 4 that the oxygen concentration before and after air purification is increased from 21.8% to 36.5%, which is beneficial to the nitric acid bleaching process; the number of particles larger than 0.5 μm is redu...

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Abstract

The invention discloses a process for preparing ultrapure nitric acid. The method comprises the following steps of: adding nitric acid metal salt to react with impurity anions, namely Cl<-> and SO4<2-> in industrial nitric acid serving as a raw material, precipitating, performing membrane filtration purification, rectifying to remove inorganic salt, regulating rectification liquid to form 69 to 70 weight percent nitric acid by using ultrapure water, white-blowing by using purified air in a white-blowing tower, absorbing blown nitrogen oxide by using saturated aqueous solution of sodium hydroxide, adding white-blowing liquid into a crude product groove, and performing membrane filtration to obtain the ultrapure nitric acid. The detection shows that: the content of the ultrapure nitric acidprepared by the process reaches 69 to 70 weight percent and various indexes of the product all meet the semiconductor equipment and material international (SEMI) C8 standard. The rectification is performed and waste acid is collected simultaneously, and the waste acid is treated and recycled, so that the quality and productivity of the product are improved; and the product has stable quality, lowimpurity content and high purity and is suitable for large-scale and continuous production.

Description

technical field [0001] The invention relates to a preparation process of ultra-high-purity nitric acid, in particular to a preparation process of electronic-grade ultra-high-purity nitric acid. Background technique [0002] Electronic grade reagents, also known as microelectronic chemicals, are one of the indispensable key basic chemical materials in the fine processing of microelectronics. The main varieties are ultra-high-purity sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, hydrofluoric acid, acetic acid, and ammonium hydroxide , hydrogen peroxide, absolute ethanol, isopropanol, acetone, xylene, etc. It is mainly used for chip cleaning and corrosion, and its cleanliness and purity have a very important impact on the yield, electrical performance and reliability of IC products. [0003] Ultra-high-purity nitric acid is often used in wet etching of silicon, such as chemical-mechanical planing of certain metals, corrosion of precious metals, and for defect ...

Claims

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Application Information

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IPC IPC(8): C01B21/46
Inventor 沈哲瑜魏永明蒋旭亮
Owner SHANGHAI CHEM REAGENT RES INST
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