Preparation process of electronic-grade potassium hydroxide

Abstract

The invention relates to a preparation process of electronic-grade potassium hydroxide, which comprises the following successive and continuous steps: sequentially passing a potassium chloride aqueous solution through a first chelating resin and a second chelating resin at a constant flow rate for adsorption to obtain a potassium chloride high-purity solution, then conducting concentrating to obtain potassium chloride crystals, adding pure water into the potassium chloride crystals for dissolving, after dissolving, conducting treating by a bipolar membrane electrodialysis system to obtain a low-concentration potassium hydroxide solution, and finally conducting heating and concentrating to obtain the electronic-grade potassium hydroxide. According to the preparation process of the electronic-grade potassium hydroxide, metal cations Fe<2+>, Ca<2+>, Mg<2+>, Ni<2+> and Zn<2+> are less than or equal to 100ppb, Na<+> is less than or equal to 50ppm, the preparation process is simple and easy to operate, and the high-concentration and high-purity electronic-grade potassium hydroxide can be continuously produced on a large scale.

Description

technical field [0001] The invention belongs to the technical field of chemical preparations, and in particular relates to a preparation process of electronic grade potassium hydroxide. Background technique [0002] Potassium hydroxide is the main raw material for stripping liquid and developer in photovoltaic, panel, semiconductor and other electronic industries. The purity of potassium hydroxide has a great influence on the quality of later-stage products. Industrial grade potassium hydroxide can no longer meet the requirements. Therefore, it is necessary to purify industrial grade potassium hydroxide to improve its quality. [0003] At present, in the production of electronic grade potassium hydroxide, potassium hydroxide is generally prepared into potassium hydroxide solution first, and then heavy metals and sodium ions are removed by ion exchange or cooling and crystallization, but this method has slow production efficiency, low energy efficiency and high purification e...

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Problems solved by technology

[0003] At present, in the production of electronic grade potassium hydroxide, potassium hydroxide is generally prepared into potassium hydroxide solution first, and then heavy metals and sodium ions are removed by ion exchange or cooling and crystallization, but this method has slow production efficiency, low energy efficiency and high purification effect. Not ideal, the resulting potassium hydroxide concentration of heavy metal ions is still high

[0004] Chinese patent CN106904637A discloses a high-activity potassium hydroxide purification process, which is dissolved in ionized water, acetone crystallization is added dropwise at 5°C, centrifuged under nitrogen protection, the filter cake is filtered out and then dried under reduced pressure under nitrogen protection to obtain high-purity Potassium hydroxide suitable for ITO development needs, this method is only aimed at the purity and fineness of potassium hydroxide, and does not involve the removal of metal cations

The crystallization efficiency of the potassium chloride crystal prepared in this method is low, and the purity requirement of the introduced hydrogen chloride gas or hydrogen chloride aqueous solution is higher, otherwise more impurity ions will be introduced, which is not conducive to purification, and then affects the purity of subsequent potassium hydroxide

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