阅读说明：本技术 一种联产焦硫酸钠和硫酰氯的方法 (Method for co-producing sodium pyrosulfate and sulfuryl chloride ) 是由 孙国庆 侯永生 梁倩 李盼盼 杨海龙 葛岩 牟红海 于 2018-09-30 设计创作，主要内容包括：本发明公开了一种联产焦硫酸钠和硫酰氯的方法,利用工业副产氯化钠与含三氧化硫的气体在高温下进行反应,制备焦硫酸钠,产生的尾气先经过冷凝回流处理回收三氧化硫,再通入硫酰氯合成装置中合成硫酰氯。本发明在国内外均未有报道,属于首创科技,即制备出高含量的焦硫酸钠,又解决了目前副产氯化钠堆积、处理成本高的问题,将低值副产氯化钠转变为可直接用于下游生产的高值产品,真正实现了资源的综合利用。(The invention discloses a method for co-producing sodium pyrosulfate and sulfuryl chloride, which comprises the steps of utilizing industrial by-product sodium chloride to react with gas containing sulfur trioxide at high temperature to prepare sodium pyrosulfate, carrying out condensation reflux treatment on generated tail gas to recover sulfur trioxide, and then introducing the tail gas into a sulfuryl chloride synthesis device to synthesize sulfuryl chloride. The method is not reported at home and abroad, belongs to the pioneering science and technology, not only prepares the high-content sodium pyrosulfate, but also solves the problems of accumulation of the current by-product sodium chloride and high treatment cost, converts the low-value by-product sodium chloride into a high-value product which can be directly used for downstream production, and really realizes the comprehensive utilization of resources.)

1. A method for co-producing sodium pyrosulfate and sulfuryl chloride is characterized by comprising the following steps:

(1) Placing the byproduct sodium chloride in a reactor, heating to 400-600 ℃, then continuously and slowly introducing gas containing sulfur trioxide into the reactor until the sodium chloride completely reacts to obtain sodium pyrosulfate, and collecting tail gas generated in the reaction process;

(2) Reacting the tail gas under the action of a catalyst to obtain a crude product of sulfuryl chloride, and rectifying the crude product to obtain a pure product of sulfuryl chloride.

2. The method of claim 1, further comprising: the method also comprises a step of recovering unreacted sulfur trioxide in the tail gas, wherein the tail gas is firstly subjected to condensation reflux treatment, the recovered sulfur trioxide is recycled to the step (1), and then the tail gas is reacted under the action of a catalyst.

3. A method according to claim 1 or 2, characterized by: the byproduct sodium chloride is a sodium chloride byproduct generated in the chemical production process, and preferably the sodium chloride byproduct generated in the 2,4-D production process.

4. A method according to claim 1 or 2, characterized by: drying the byproduct sodium chloride until the byproduct sodium chloride is anhydrous, and adding the byproduct sodium chloride into the reactor.

5. A method according to claim 1, 2 or 3, characterized by: in the step (1), the gas containing sulfur trioxide is a gas with the volume concentration of 10-100% of sulfur trioxide, and the concentration of 100% represents pure sulfur trioxide gas; in the step (1), the ratio of the molar weight of the sulfur trioxide to the molar weight of the sodium chloride in the byproduct sodium chloride is 1.5: 1-1.8: 1.

6. The method of claim 1 or 5, wherein: in the step (1), the reaction time is 100-200 min.

7. The method of claim 2, wherein: during condensation and reflux, the condensation temperature is controlled below the boiling point of sulfur trioxide, preferably about 40 ℃.

8. The method of claim 2 or 7, wherein: condensing and refluxing in a two-stage water cooling mode.

9. the method of claim 1, further comprising: in the step (1), the main components of the generated tail gas are chlorine gas and sulfur dioxide, and the molar weights of the chlorine gas and the sulfur dioxide are the same.

10. The method of claim 1 or 9, wherein: in the step (2), the reaction is carried out at the temperature of-10 to-25 ℃; in the step (2), the catalyst is activated carbon.

Technical Field

The invention relates to a method for co-producing sodium pyrosulfate and sulfuryl chloride, in particular to a method for preparing sodium pyrosulfate and sulfuryl chloride by taking by-product sodium chloride and sulfur trioxide as raw materials, and belongs to the technical field of waste resource utilization.

Background

Sodium pyrosulfate is widely used as a sewage purifying agent, an analytical reagent, a fruit and vegetable preservative, a melting agent for ores and the like. Sodium pyrosulfate as a sewage purifying agent can act together with hydrogen peroxide, and has good effect on degrading organic matters in sewage under the catalysis of ultraviolet light; with the increasing ore exploitation utilization amount, the usage amount of sodium pyrosulfate is greatly increased.

At present, the production method of sodium pyrosulfate mainly adopts sodium bisulfate high-temperature cracking preparation, and the method has high energy consumption, low cracking efficiency and longer cracking time. In addition, the sodium pyrosulfate can be prepared by pyrolysis of sodium persulfate, but the sodium persulfate is a high-value chemical product, and the method for producing the sodium pyrosulfate has high raw material and energy consumption, and can bring negative economic benefits to enterprises.

At present, a large amount of byproduct sodium chloride, especially fine chemical products, is produced in the production process of a plurality of chemical products, and the byproduct sodium chloride often contains some toxic and harmful organic matters, can not be directly recycled, can only be treated as hazardous waste, and has high treatment cost. How to recycle the organic matters needs to remove the organic matters. At present, the technology for treating organic matters in the byproduct sodium chloride comprises high-temperature treatment methods such as a pyrolysis method, a rotary kiln incineration method, a graded critical carbonization method and the like, the energy consumption of the methods is high, the value of the generated sodium chloride is not enough to meet the requirement of cost, and negative benefits are brought to enterprises.

Therefore, how to find an economic resource utilization method of byproduct sodium chloride, reduce the treatment cost and produce products with high utilization value has great significance for enterprises.

Disclosure of Invention

The invention provides a method for co-producing sodium pyrosulfate and sulfuryl chloride aiming at the defects of the prior art, the method takes industrial byproduct sodium chloride as a raw material, organic matters in the sodium chloride are not required to be removed in advance, downstream production can be directly carried out, the organic matters are eliminated in the production process, and the produced product is not influenced by the organic matters. The invention realizes the co-production of the sodium pyrosulfate and the sulfuryl chloride, has high economic value of the product and reduces the cost of treating byproducts by enterprises.

The industrial by-product sodium chloride and sulfur trioxide are reacted at high temperature, organic matters in the by-product sodium chloride can be oxidized and decomposed to prepare a sodium pyrosulfate product and a large amount of tail gas, the main components of the tail gas are chlorine gas and sulfur dioxide which exist in equimolar manner, and the tail gas also contains a part of sulfur trioxide, carbon dioxide and hydrogen chloride. Firstly, carrying out reflux treatment on tail gas through a condenser, refluxing unreacted sulfur trioxide to an initial reaction stage for recycling, then introducing mixed gas into a sulfuryl chloride synthesis device to obtain a sulfuryl chloride crude product, and carrying out rectification treatment to obtain a sulfuryl chloride product. Through the two-step reaction, all components in the sodium chloride byproduct are fully utilized, and organic matters in the sodium chloride are almost completely removed, so that qualified sodium pyrosulfate and sulfuryl chloride products are finally obtained.

The invention provides a method for co-producing sodium pyrosulfate and sulfuryl chloride, which comprises the following steps:

(1) Placing the byproduct sodium chloride in a reactor, heating to 400-600 ℃, then continuously and slowly introducing gas containing sulfur trioxide into the reactor until the sodium chloride completely reacts to obtain sodium pyrosulfate, and collecting tail gas generated in the reaction process;

(2) reacting the tail gas under the action of a catalyst to obtain a crude product of sulfuryl chloride, and rectifying the crude product to obtain a pure product of sulfuryl chloride.

The specific equation of the present invention is as follows:

Furthermore, the byproduct sodium chloride used in the invention is a sodium chloride byproduct generated in the chemical production process, wherein the sodium chloride byproduct contains organic impurities. Preferably, the byproduct sodium chloride is a sodium chloride byproduct generated in the 2,4-D production process, and specifically is a byproduct obtained after the high-salt wastewater generated in the 2,4-D production process is treated by an MVR (mechanical vapor recompression) process. The content of organic matters in the byproduct sodium chloride is 500-3000 ppm (300 g/L saline water), the content of water is 2-10 wt%, and the byproduct sodium chloride is dried before use. The method directly takes the byproduct sodium chloride as a raw material, directly reacts with sulfur trioxide gas at high temperature without pretreatment to form sodium pyrosulfate, avoids the problem of sodium chloride wrapping by the generated sodium pyrosulfate through high-temperature reaction, and has the advantages of good material dispersibility, thorough reaction, good product fluidity, high purity and no other solid byproducts.

Further, in the step (1), the gas containing sulfur trioxide is slowly introduced into the reactor for reaction until the sodium chloride reaction is completed. The gas containing sulfur trioxide is a gas having a sulfur trioxide volume concentration of 10 to 100%, and when the concentration is 100%, it represents a pure sulfur trioxide gas, and when the concentration is other than 100%, it represents a mixed gas of sulfur trioxide and dry air. Generally, the ratio of the molar amount of sulfur trioxide to the molar amount of sodium chloride is 1.5:1 to 1.8:1, and the reaction time is generally 100 to 200 min. The sodium pyrosulfate product obtained by the reaction has a content of over 98%.

Further, when the byproduct sodium chloride reacts with sulfur trioxide at high temperature, organic matters in the byproduct sodium chloride are oxidized and decomposed to generate yellow-green gas, and the product is not influenced by organic impurities; the main components of the mixed gas generated by the reaction, namely the tail gas, are chlorine and sulfur dioxide, the chlorine and the sulfur dioxide exist in equimolar mode, and the tail gas also contains a part of unreacted sulfur trioxide, carbon dioxide and hydrogen chloride.

And further, the method also comprises a step of recovering unreacted sulfur trioxide in the tail gas, wherein the tail gas generated in the step (1) is subjected to condensation reflux treatment, the sulfur trioxide in the recovered tail gas is recycled to the step (1), and then the tail gas is reacted under the action of a catalyst. Condensation reflux adopts the condenser to go on, and the condensation mode can adopt two-stage water-cooling, guarantees the condensing temperature below the sulfur trioxide boiling point during the condensation to make sulfur trioxide separate out from the tail gas. Preferably, the condensation temperature is around 40 ℃.

furthermore, chlorine and sulfur dioxide in the tail gas exist in equimolar amount, so that the tail gas can be just used for synthesizing sulfuryl chloride, and the synthesis can be carried out in a sulfuryl chloride synthesis device. Therefore, the tail gas after condensation treatment enters the step (2) to synthesize sulfuryl chloride under the action of the catalyst, secondary pollution is not caused in the process, the full reuse of resources is realized, and the requirements of green and clean production are met.

Further, in the step (2), the tail gas is reacted under the catalysis of a catalyst, the catalyst is preferably activated carbon, and the amount of the activated carbon is the amount disclosed in the prior art. The reaction is carried out at the temperature of-10 to-25 ℃, and the residual tail gas after the reaction can be merged into the next batch of tail gas for circular treatment, thereby realizing clean production. The purity of the sulfuryl chloride crude product generated by the reaction is more than 96 percent, the purity can reach more than 99 percent through rectification, and the quality is high.

The method directly utilizes the industrial byproduct sodium chloride to prepare the sodium pyrosulfate, the production process is not influenced by organic impurities, and the generated tail gas can be synthesized into the sulfuryl chloride, so that the method does not cause secondary pollution and meets the requirements of green and clean production. The obtained product can be directly used for downstream production and can also be directly sold, thereby bringing good economic benefit for enterprises and having strong operability. The method is not reported at home and abroad, belongs to the pioneering science and technology, not only prepares the high-content sodium pyrosulfate, but also solves the problems of accumulation and high treatment cost of the current by-product sodium chloride, avoids the waste of sodium chloride resources, reduces the harm of the by-product sodium chloride to the environment, converts the low-value by-product sodium chloride into a high-value product which can be directly used for downstream production, and really realizes the comprehensive utilization of resources.

Detailed Description

The present invention will be described in more detail with reference to the following examples, which are not intended to limit the scope of the present invention.

Sodium chloride by-products used in the following examples are all sodium chloride obtained by subjecting high-salt wastewater generated in a 2,4-D production process to MVR process treatment, wherein the organic matter content is 500-3000 ppm (300 g/L of saline water), the organic matter is glycolic acid, 2,4-D technical product, phenol and the like, the water content is 2-10% and the like, and the sodium chloride by-product is dried before being placed in a four-neck flask.

In the following examples, the utilization rate of sulfur trioxide = (mass of sulfur trioxide fed-mass of sulfur trioxide reacted)/mass of sulfur trioxide fed.

In the following examples, sulfur trioxide used is pure sulfur trioxide or a mixed gas of sulfur trioxide and dry air.