阅读说明：本技术 一种硫氰酸钠的绿色合成方法 (Green synthesis method of sodium thiocyanate ) 是由 任磊 于晓锋 于 2021-07-24 设计创作，主要内容包括：一种硫氰酸钠的绿色合成方法,包括以下步骤：以摩尔比1-1.05:1的比例的硫氰酸铵和氢氧化钠为原料,无需溶剂直接混合搅拌,搅拌过程中伴随抽真空除去氨气并用水喷淋吸收,反应完后直接过滤并干燥得到高品质的硫氰酸钠。本方法无需任何溶剂,两个固体底物直接接触,无需特殊设备,即可得到高品质的硫氰酸钠,反应速率高且工艺绿色环保,高效节能。(A green synthesis method of sodium thiocyanate comprises the following steps: taking ammonium thiocyanate and sodium hydroxide with the molar ratio of 1-1.05:1 as raw materials, directly mixing and stirring without a solvent, removing ammonia gas by vacuumizing in the stirring process, spraying and absorbing with water, directly filtering and drying after the reaction to obtain high-quality sodium thiocyanate. The method does not need any solvent, the two solid substrates are directly contacted, special equipment is not needed, the high-quality sodium thiocyanate can be obtained, the reaction rate is high, the process is green and environment-friendly, and the efficiency and the energy are high.)

1. A green synthesis method of sodium thiocyanate is characterized by comprising the following steps: taking ammonium thiocyanate and sodium hydroxide with the molar ratio of 1-1.05:1 as raw materials, directly mixing and stirring without a solvent, removing ammonia gas by vacuumizing in the stirring process, spraying and absorbing with water, directly filtering and drying after the reaction to obtain high-quality sodium thiocyanate.

2. The green synthesis method of sodium thiocyanate according to claim 1, characterized in that: the molar ratio of the ammonium thiocyanate to the sodium hydroxide is 1: 1.

3. The green synthesis method of sodium thiocyanate according to claim 1, characterized in that: the purity of ammonium thiocyanate in the raw materials is more than 96 percent, and the purity of sodium hydroxide is more than 90 percent.

Technical Field

The invention relates to a green synthesis method of sodium thiocyanate.

Background

Sodium thiocyanate (NaSCN) has a wide range of applications. In the textile field, the fiber is used as a solvent extraction agent for polyacrylonitrile fibers; in the field of crop protection, the plant defoliant is used as a certain plant defoliant and a synthetic raw material of some bactericides, insecticides, herbicides and the like; the method is used for synthesizing 2-amino-6-methoxybenzothiazole, allyl isothiocyanate and the like which are important intermediates of veterinary drugs, materials, dyes and the like in the field of equipment protection such as corrosion prevention, pollution prevention and the like, rust remover for roads, electroplating of ship bodies and the like and in other fine chemical engineering fields.

The first method is a sodium cyanide (NaCN) sulfur synthesis process, which comprises the steps of reacting NaCN with sulfur to generate sodium thiocyanate, removing impurities, decoloring, filtering, evaporating and crystallizing to obtain the product. The process has the advantages of high product purity, good product quality and stable product quality. The disadvantage is that highly toxic chemical Na CN is used, and has strict restriction system in purchasing, transporting and using. The second method is an arsenic-alkali by-product method, wherein arsenic trioxide is used as a catalyst, sodium carbonate is used as an absorbent, waste liquid from oxidative desulfurization and decyanation is used as a raw material, and the sodium thiocyanate is obtained by purification in a mode of multiple concentration and fractional crystallization or an organic solvent recrystallization method. The process has the advantages of cheap and easily available raw materials and low cost. The defects are that the produced product has poor quality and low purity, can not be exported and can only be sold as a low-grade product. The third method is an ammonium thiocyanate conversion method, which adopts ammonium thiocyanate and sodium hydroxide as raw materials and obtains the product after impurity removal, decoloration, filtration, evaporation and crystallization. The process has the advantages of simple production process, easy operation, great influence of raw material purity and high raw material cost.

With the wider application of sodium thiocyanate, the preparation process is gradually improved, but all the existing synthesis methods are liquid-phase synthesis methods, the total energy consumption is large, the cycle is long, and the production capacity of a reaction kettle is low.

Disclosure of Invention

The invention aims to solve the technical problem of providing an environment-friendly synthesis method of sodium thiocyanate, wherein high-quality sodium thiocyanate can be obtained by directly contacting two solid substrates without any solvent or special equipment, and the method has the advantages of high reaction rate, environment-friendly process, high efficiency and energy conservation.

In order to solve the technical problem, the invention provides a green synthesis method of sodium thiocyanate, which comprises the following steps: taking ammonium thiocyanate and sodium hydroxide with the molar ratio of 1-1.05:1 as raw materials, directly mixing and stirring without a solvent, removing ammonia gas by vacuumizing in the stirring process, spraying and absorbing with water, directly filtering and drying after the reaction to obtain high-quality sodium thiocyanate.

Preferably, the molar ratio of the ammonium thiocyanate to the sodium hydroxide is 1: 1.

Preferably, the purity of the ammonium thiocyanate in the raw material is more than 96 percent, and the purity of the sodium hydroxide is more than 90 percent.

The invention has the advantages that: the method has simple process, and the produced sodium thiocyanate has high quality (the content is more than 99.0%). The reaction rate is high, the utilization rate of the reaction kettle is high, no solvent is needed, the continuous reaction can be realized by using the water generated by the reaction, the atom economy is high, and the circular economy is realized. Compared with the traditional reaction kettle, the efficiency is improved by about 10 times, the use of water and other solvents is eliminated, and the reaction kettle is green, environment-friendly, efficient and energy-saving. In addition, ammonia gas is removed by vacuumizing in the stirring process and is absorbed by water spraying, so that by-product ammonia water with the concentration of about 20% can be formed, and the ammonia water can be widely applied to industry.

Detailed Description

The first embodiment is as follows:

adding 317.167 g of ammonium thiocyanate (96% content, 4.0mol) into a 500ml reaction bottle, adding 168.463 g of sodium hydroxide (95% content, 4.0mol) under stirring, stirring for 10 minutes, vacuumizing to remove ammonia gas (the ammonia gas is sprayed and absorbed by water to form about 20% of by-product ammonia water), directly filtering after the reaction is finished, and vacuum-drying for 20 minutes at 80 ℃ to obtain the sodium thiocyanate. 346.212 g of white solid, yield 90%, content 99.1%, ammonium salt 0.01%, pH 7.3 and sulfate 0.02%. The whole reaction process was carried out for 3 hours.

Example two:

adding 333.025 g of ammonium thiocyanate (96% content, 4.2mol) into a 500ml reaction bottle, adding 168.463 g of sodium hydroxide (95% content, 4.0mol) under stirring, stirring for 10 minutes, vacuumizing to remove ammonia gas (the ammonia gas is sprayed and absorbed by water to form about 20% of by-product ammonia water), directly filtering after the reaction is finished, and vacuum-drying for 20 minutes at 80 ℃ to obtain the sodium thiocyanate. 353.905 g of white solid, 92% of yield, 99.1% of content, 0.04% of ammonium salt, 7.1% of pH value and 0.02% of sulfate. The whole reaction process was carried out for 3 hours.

Example three:

adding 333.025 g of ammonium thiocyanate (96% content, 4.0mol) into a 500ml reaction bottle, adding 172.631 g of sodium hydroxide (95% content, 4.1mol) under stirring, stirring for 10 minutes, vacuumizing to remove ammonia gas (the ammonia gas is sprayed and absorbed by water to form about 20% of by-product ammonia water), directly filtering after the reaction is finished, and vacuum-drying for 20 minutes at 80 ℃ to obtain the sodium thiocyanate. 342.365 g of white solid, 89% yield, 99.0% content, no detectable ammonium salt, 9.5 pH, 0.015% sulfate. The whole reaction process was carried out for 3 hours.

Example four:

adding 317.167 g (96% content, 4.0mol) of ammonium thiocyanate into a 500ml reaction bottle, adding 177.821 g (90% content, 4.0mol) of sodium hydroxide under the stirring condition, stirring for 10 minutes, vacuumizing to remove ammonia gas (the ammonia gas is sprayed and absorbed by water to form about 20% of by-product ammonia water), directly filtering after the reaction is finished, and performing vacuum drying at 80 ℃ for 20 minutes to obtain the sodium thiocyanate. 334.081 g of white solid, the yield is 87%, the content is 99.1%, the ammonium salt is 0.01%, the pH value is 7.1, and the sulfate is 0.015%. The whole reaction process was carried out for 3 hours.

Example five:

adding 634.333 kg of ammonium thiocyanate (96% in content, 800.0mol) into a 100L reaction bottle, adding 33.684kg of sodium hydroxide (95% in content, 800.0mol) into a solid feeder under the stirring condition, stirring for 10 minutes, vacuumizing for 1 hour to remove ammonia gas (tail gas is sprayed and absorbed by water to form 20% of by-product ammonia water), directly filtering after detection is qualified, and vacuum drying at 80 ℃ for 60 minutes to obtain the sodium thiocyanate. 67.584 kg of white solid, 88% of yield, 99.1% of content, 0.005% of ammonium salt, 7.4% of pH value and 0.02% of sulfate. The whole reaction process was carried out for 4 hours. 6 batches per day. The 100L reaction kettle can realize the capacity of about 250 kg. Compared with the traditional process, about 20 kilograms of products can be produced in a 100L reaction kettle every day, the product quality is high (> 99.0%), and the production efficiency is improved by 8-12 times.

In the embodiment of the invention, the raw materials with other qualities sold in the market are as follows: 99 percent of ammonium thiocyanate, 90 percent of sodium hydroxide and 99 percent of high-quality sodium hydroxide are verified to meet the requirements of the invention, and the invention has low requirements on the product quality of raw materials.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, but the present invention is not limited to the embodiment, and any modifications, equivalents and equivalent changes made to the above embodiment according to the present invention are within the scope of the present invention.