Method for preparing electronic-grade sulfuric acid solution

Abstract

This invention relates to a method for preparing an electronic-grade sulfuric acid solution, comprising the following steps: providing a sulfuric acid feed solution; introducing the sulfuric acid feed solution into an evaporation device, subjecting the sulfuric acid feed solution to an evaporation step under a gas pressure of 5-20 torr, and generating a gaseous sulfuric acid with a concentration of 70-90 wt%; introducing the gaseous sulfuric acid into an absorption device, and introducing an absorbent liquid into the bottom of the absorption device to perform an absorption step; obtaining an electronic-grade sulfuric acid solution from a bottom outlet of the absorption device; wherein, in the absorption step, the ratio of the mass flow rate of the absorbent liquid circulating from the bottom to the top of the absorption device to the mass flow rate of the gaseous sulfuric acid introduced into the absorption device is 1.80-3.60.

Claims

1. A method for preparing an electronic-grade sulfuric acid solution, comprising the following steps: providing a sulfuric acid feed solution; introducing the sulfuric acid feed solution into an evaporation device, subjecting the sulfuric acid feed solution to an evaporation step under conditions of a gas pressure of 5-20 torr and a temperature of less than or equal to 220°C, and generating a gaseous sulfuric acid with a concentration of 70-90 wt%; introducing the gaseous sulfuric acid into an absorption device, and introducing an absorbent liquid into the bottom of the absorption device, subjecting the absorption step under conditions of a gas pressure of 2-12 torr and a temperature of 120-200°C; obtaining an electronic-grade sulfuric acid solution from a bottom outlet of the absorption device; wherein, in the absorption step, the ratio of the mass flow rate of the absorbent liquid circulating from the bottom to the top of the absorption device to the mass flow rate of the gaseous sulfuric acid introduced into the absorption device is 1.80-3.

60.

2. The method as described in claim 1, wherein the concentration of the sulfuric acid feed solution is 80-90 wt%.

3. The method as described in claim 1, wherein the evaporation apparatus is a falling film evaporator or a still evaporator.

4. The method as described in claim 1, wherein the evaporation apparatus comprises tantalum, silicon alloy, quartz, glass, graphite, tetrafluoroethylene polymer, or a combination thereof.

5. The method as described in claim 1, wherein the concentration of the gaseous sulfuric acid is 70-86 wt%.

6. The method as described in claim 1, wherein a demister is further provided between the evaporation device and the absorption device.

7. The method as described in claim 6, wherein the demister is in the form of a mesh, a candle, a fiberglass bed, or a combination thereof.

8. The method as described in claim 1, wherein the absorbent is a sulfuric acid solution with a concentration greater than 96 wt%.

9. The method as claimed in claim 1, wherein the absorption device comprises tantalum, silicon alloy, quartz, glass, graphite, tetrafluoroethylene polymer, or a combination thereof.

10. The method as described in claim 1, wherein the organic content of the electronic-grade sulfuric acid solution is less than 1 ppm.

11. The method as described in claim 1, wherein the metal content of the electronic-grade sulfuric acid solution is less than 0.1 ppb.

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