Method for preparing two alkalis and co-producing high-purity gypsum from mirabilite and limestone through PCET reaction

A technology of limestone and reaction, applied in the direction of electrodes, calcium/strontium/barium sulfate, electrolysis process, etc., can solve the problems of high environmental pressure, high energy consumption, high energy consumption of electrolysis, etc., and achieve the goal of reducing manufacturing energy consumption and reducing energy consumption Effect

Active Publication Date: 2020-01-07
王昱飞
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the problems faced by caustic soda production mainly include: (1) high energy consumption for electrolysis: during the electrolysis process, the cathode and anode will continuously produce hydrogen and chlorine, and its theoretical potential is as high as 2.172V. In actual industrial production, the electrolysis voltage is as high as 3V Above, the DC power consumption reaches 2200kWh / t-NaOH, accounting for more than 80% of the total energy consumption of caustic soda production
(2) High risk of operation: liquid chlorine and chlorine gas belong to the first batch of hazardous chemicals under key supervision. Even under strict regulatory policies, safety accidents caused by chlorine gas still emerge in endlessly
(3) Environmental protection pressure is high: chlorine gas, as a highly toxic gas, is the largest by-product of the ion-exchange membrane caustic soda industry, and 0.89 tons of chlorine gas is produced by producing 1 ton of caustic soda
This has brought about many environmental problems: 1. For every ton of chlorine gas produced, 20kg of chlorine-containing waste sulfuric acid will be produced, which has a high environmental risk; The emission concentration limit is changed from 65mg / m 3 reduced to 5mg / m 3 , greatly increasing the cost of environmental protection operation; 3. In the long run, the downstream market of chlorine gas cannot match the production volume of chlorine gas
However, with the development of chemical technology, especially electrochemical technology, and the enhancement of human awareness of environmental protection, economic and environmental problems such as high energy consumption, high emissions, and high safety risks in the two-alkali manufacturing process have become more prominent, which has seriously restricted the development of the two-alkali industry. Further development

Method used

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  • Method for preparing two alkalis and co-producing high-purity gypsum from mirabilite and limestone through PCET reaction
  • Method for preparing two alkalis and co-producing high-purity gypsum from mirabilite and limestone through PCET reaction
  • Method for preparing two alkalis and co-producing high-purity gypsum from mirabilite and limestone through PCET reaction

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0089] In this embodiment, the process of producing soda ash and co-producing high-purity gypsum with Glauber's salt and limestone by PCET reaction is as follows:

[0090] The cation exchange membrane is placed in the electrolytic cell and the electrolytic cell is divided into an anode area and a cathode area. The anode area adds 50ml sodium acetate solution (concentration is 2M) as the anolyte, and the cathode area adds 50ml sodium carbonate (concentration is 3M). Bubble CO into the cathode area at a rate of 10ml / min 2 Gas for 5 minutes, the electrolyte is continuously circulated into the electrode chamber of the electrolytic cell by a peristaltic pump at a flow rate of 20mL / min, and 0.3mol / L riboflavin-5-phosphate (FMN, ) as the cathode electrocatalyst, adding 0.3mol / L reduced riboflavin (FMNH 2 , ) as the anode electrocatalyst, and a DC power supply (IT6932A, Itech) was applied between the anode electrode and the cathode electrode to provide the current.

[0091] Among...

Embodiment 2

[0100] In this embodiment, the process of producing soda ash and co-producing high-purity gypsum with Glauber's salt and limestone by PCET reaction is as follows:

[0101] The cation exchange membrane is placed in the electrolytic cell and the electrolytic cell is divided into an anode area and a cathode area. The anode area adds 50ml sodium formate solution (concentration is 3M) as the anolyte, and the cathode area adds 50ml sodium carbonate (concentration is 2M). The cathode area was bubbled into CO at a rate of 20ml / min 2 gas, the electrolyte is continuously circulated into the electrode chamber of the electrolytic cell through a peristaltic pump at a flow rate of 20mL / min, and 0.1mol / L of As the cathode electrocatalyst Q, add 0.1mol / L of As the anode electrocatalyst QH, a DC power supply (IT6932A, Itech) was applied between the anode and cathode electrodes to provide current.

[0102] Among them, the anode electrode is carbon felt, the cathode electrode is carbon felt,...

Embodiment 3

[0111] The present embodiment utilizes PCET reaction to produce caustic soda co-production process of high-purity gypsum with Glauber's salt and limestone as follows:

[0112] The cation exchange membrane is placed in the electrolytic cell and the electrolytic cell is divided into an anode area and a cathode area. The anode area adds 50ml sodium formate solution (concentration is 3M) as the anolyte, and the cathode area adds 50ml sodium hydroxide (concentration is 1M). The peristaltic pump continuously circulates the electrolyte into the electrode chamber of the electrolytic cell at a flow rate of 20mL / min, and at the same time adds 2mol / L of As the cathode electrocatalyst Q, add 2mol / L of As the anode electrocatalyst QH, a DC power supply (IT6932A, Itech) was applied between the anode and cathode electrodes to provide current.

[0113] Among them, the anode electrode is carbon cloth, the cathode electrode is carbon cloth, and the current density is 55.6mA / cm 2 When the el...

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Abstract

The invention provides a method for preparing two alkalis and co-producing high-purity gypsum from mirabilite and limestone through a PCET reaction, belonging to the technical field of low-energy-consumption production of two alkalis. According to the invention, a cation exchange membrane is putted into an electrolytic cell; a weakly acidic sodium salt solution and a compound QH are added into ananode region to serve as an anode electrocatalyst; sodium carbonate or sodium hydroxide is added into a cathode region, and a compound Q is added as a cathode electrocatalyst; a direct-current power supply is applied between a negative electrode and a positive electrode; in the process of electrolysis, QH is oxidized into Q, H<+> is released, and Na<+> in an anolyte permeates the cation exchange membrane, reaches the cathode region and is combined with OH<-> in a catholyte to generate NaOH, or NaOH further absorbs CO2 to realize conversion into Na2CO3; and an anolyte containing a large amountof H<+> is generated through electrolysis and undergoes a dissolution reaction with limestone, H<+> is consumed to generate Ca<2+>, and SO4<2-> and Ca<2+> are combined to generate a high-purity CaSO4precipitate. A compound with PCET reactivity is used as an electrocatalyst, Q is the oxidation state of the compound, QH is the reduction state of the compound, mirabilite and limestone are used as raw materials, and preparation of sodium carbonate, caustic soda and gypsum is realized.

Description

technical field [0001] The invention belongs to the technical field of chemical production of novel low-energy two-alkali, and specifically relates to a method for producing two-alkali and co-producing high-purity gypsum with mirabilite and limestone by using PCET reaction. Background technique [0002] Two alkalis (soda ash and caustic soda) are one of the most important products in the chemical industry, and are widely used in construction, chemical industry, metallurgical industry, printing and dyeing industry, leather industry, daily chemical industry and food industry. my country is the country with the largest production capacity of soda ash and caustic soda in the world. According to statistics, in 2012, the total national consumption of salt (sodium chloride) was 86.6 million tons, while the proportion of salt used by the two alkali industries exceeded 80%, reaching 70.75 million tons. At present, my country's annual output of soda ash is close to 30 million tons, c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25B1/14C25B1/16C01F11/46C25B11/06
CPCC01F11/46C01P2006/80C25B1/14C25B1/16C25B11/04
Inventor 陆宗禄
Owner 王昱飞
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