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Method for preparing high-purity sodium sulfite through supercritical hydrothermal reduction

A technology of supercritical water and sodium sulfite, which is applied in the preparation of alkali metal sulfites and the production of bulk chemicals, can solve the problems of energy consumption, high reaction temperature, long process route, etc., so as to reduce production costs and reduce reaction temperature. , the effect of shortening the reaction time

Inactive Publication Date: 2015-05-20
CHENGDU CHENGDE CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method achieves the regeneration of sodium dichromate, but using carbon to reduce calcium sulfate, the SO 2 converted to SO 3 The energy consumption of the process is very high, and the economic cost of the whole process is too high
[0005] Publication number is that the Chinese patent application of CN88103072A discloses the method utilizing sodium sulfate to produce sodium hydroxide, and the process route of this method is long, carbon reduction barium sulfate, barium sulfide and CO 2 response, and SO 2 converted to SO 3 The process is quite energy-intensive, and the economic cost cannot pass the test for actual production
[0006] Chen Yinfei et al. proposed to use gas-solid phase catalytic reaction to Fe 2 o 3 As a catalyst, using H 2 Direct reduction of sodium sulfate to prepare sodium sulfide, although the highest conversion rate of this method can reach 95%, but the reaction time is as long as 90-120min, and the reaction temperature is as high as 600-700°C (research on hydrogen reduction of sodium sulfate to sodium sulfide, chemical reaction Engineering and Technology, 1998,14(3):257-262, Research on hydrogen reduction of sodium sulfate in a fluidized bed, Journal of Zhejiang University of Technology, 1998,26(2):89-93), resulting in high production costs

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  • Method for preparing high-purity sodium sulfite through supercritical hydrothermal reduction

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Effect test

Embodiment 1

[0033] In this embodiment, the process flow chart of the method for preparing high-purity sodium sulfite by supercritical hydrothermal reduction is shown in figure 1 , the process steps are as follows:

[0034] (1) Glauber's salt is formulated into 500mL of sodium sulfate aqueous solution with a sodium sulfate concentration of 0.01mol / L, then adjusted to a pH value of 2 with sulfuric acid with a concentration of 98wt% and transferred to a hydrothermal reactor, and then poured into the reactor Add elemental sulfur to form reaction solution; The add-on of described elemental sulfur is 0.02g in every liter of sodium sulfate aqueous solution;

[0035] (2) Close the hydrothermal reaction kettle, use the vacuum pump to work continuously for 30 minutes to remove the air in the reaction kettle, and then pass in N 2 Until the pressure in the reactor is 0.15MPa, then use a vacuum pump to pump air for 30min, and then feed in N 2 Until the pressure in the reactor is 0.15MPa, after repea...

Embodiment 2

[0038] In this embodiment, the process flow chart of the method for preparing high-purity sodium sulfite by supercritical hydrothermal reduction is shown in figure 1 , the process steps are as follows:

[0039] (1) Glauber's salt is formulated into 50mL of sodium sulfate aqueous solution with a sodium sulfate concentration of 0.02mol / L, then adjusted to a pH value of 2.5 with a concentration of 98wt% sulfuric acid and transferred to a hydrothermal reactor, and then to the reactor Add elemental sulfur to form reaction solution; The add-on of described elemental sulfur is 0.1g in every liter of sodium sulfate aqueous solution;

[0040] (2) Close the hydrothermal reaction kettle, use the vacuum pump to work continuously for 30 minutes to remove the air in the reaction kettle, then pass in argon until the pressure in the reaction kettle is 0.1MPa, then use the vacuum pump to pump air for 30 minutes, and then pass in argon to the reaction The pressure in the kettle is 0.1MPa, and ...

Embodiment 3

[0043] In this embodiment, the process flow chart of the method for preparing high-purity sodium sulfite by supercritical hydrothermal reduction is shown in figure 1 , the process steps are as follows:

[0044] (1) Yuanming powder is mixed with sodium sulfate concentration and is 10L of aqueous sodium sulfate solution of 1mol / L, then adjusts its pH value to be 5 with the sulfuric acid of 98wt% with concentration and transfers in the hydrothermal reactor, then to described reaction Add elemental sulfur in the still to form reaction solution; The add-on of described elemental sulfur is 2g in every liter of sodium sulfate aqueous solution;

[0045] (2) Close the hydrothermal reaction kettle, use the vacuum pump to work continuously for 30 minutes to remove the air in the reaction kettle, and then pass in N 2 Until the pressure in the reactor is 0.1MPa, then use a vacuum pump to pump air for 30min, and then feed in N 2 Until the pressure in the reactor is 0.1MPa, after repeating...

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Abstract

The invention belongs to the field of comprehensive utilization of chemical by-product sodium sulfate and particularly relates to a method for preparing high-purity sodium sulfite through supercritical hydrothermal reduction. The method comprises the following process steps: (1) preparing mirabilite or anhydrous sodium sulfate to a sodium sulfate aqueous solution with concentration of 0.01-1 mol / L, and then, adjusting the pH value of the sodium sulfate aqueous solution to 2-5, transferring the sodium sulfate aqueous solution into a hydrothermal reaction kettle, and adding elemental sulfur into the reaction kettle to form reaction liquid; (2) sealing the reaction kettle, completely replacing the air in the reaction kettle through an inert gas, and then, filling H2, heating the reaction liquid to 380-500 DEG C, reacting under the temperature for 1-20 minutes, constantly maintaining the H2 partial pressure to 0.4-2 MPa in the reaction process, cooling the obtained solution to room temperature, and adjusting the pH value of the solution to 5-7; and (3) dripping an anti-solvent into the solution obtained in the step (2) at the room temperature while stirring to carry out solvent-out crystallization, performing solid-liquid separation, and washing and drying the solid phase to obtain the high-purity sodium sulfite.

Description

technical field [0001] The invention belongs to the field of comprehensive utilization of chemical by-product sodium sulfate, in particular to a method for preparing high-purity sodium sulfite by supercritical hydrothermal reduction using chemical by-product mirabilite or sodium sulfate as raw materials. Background technique [0002] A large amount of mirabilite (sodium sulfate decahydrate) and sodium sulfate (sodium sulfate) by-products are produced in many chemical production processes. A large amount of by-products of sodium sulfate decahydrate will also be produced in the by-products of cooling and crystallization of the mother liquor in the process, in the process of producing soap acids with paraffin wax in the production of fatty acids, and in the chlor-alkali industry. After using anhydrous sodium sulfate as a dehydrating agent, a large amount of Glauber's salt by-product. Even though the current market price of thenardite is only about 5 yuan / ton, there is still no...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01D5/14
CPCY02P20/54
Inventor 徐程浩杨德建
Owner CHENGDU CHENGDE CHEM TECH