Preparation process of thionyl chloride

Abstract

The invention relates to the technical field of chemical synthesis, and particularly discloses a preparation process of thionyl chloride. Sulfur, chlorine and sulfur dioxide enter a fixed bed to react, mixed gas obtained after the reaction is subjected to two-time sulfur preparation reaction, the content of sulfur dichloride in thionyl chloride is reduced, a composite catalyst is used in the second-time sulfur preparation reaction, decomposition of dichlorosulfuryl is promoted, and the content of dichlorosulfuryl in thionyl chloride is reduced. The thionyl chloride prepared by the method has the advantages of few impurities and high purity.

Description

Technical Field

[0001] The present application relates to the technical field of chemical synthesis, and more specifically, to a preparation process of thionyl chloride. Background Art

[0002] As an important organic chemical intermediate, thionyl chloride is primarily used in pharmaceuticals, pesticides, dyes, and organic synthesis. Currently, there are four main production processes for thionyl chloride: the sulfur dioxide vapor phase method, the chlorosulfonic acid method, the co-production method, and the sulfur trioxide vapor phase method.

[0003] Currently, the sulfur dioxide vapor phase process is one of the most advanced and mature technologies for producing thionyl chloride. Using liquid chlorine, sulfur, and sulfur dioxide as the primary raw materials, the sulfur dioxide vapor phase process continuously synthesizes high-temperature thionyl chloride gas at a certain temperature and in the presence of a catalyst. However, the purity of the thionyl chloride gas is often low, requiring condensation, separation, sulfur addition, and distillation to ultimately produce a high-purity thionyl chloride product. However, in actual production, the sulfur dioxide vapor phase process can produce thionyl chloride with poor product color and low purity for various reasons.

[0004] Chinese patent publication CN106698364B discloses a method for producing thionyl chloride. Synthesis gas, produced by the reaction of sulfur and chlorine in a synthesis reactor, enters a reactor along with sulfur dioxide gas. The crude thionyl chloride produced in the reactor passes directly into a gaseous state through an absorption tower and then into a decomposer. The crude thionyl chloride gas exiting the decomposer enters a distillation tower, where the overhead gas phase is condensed and enters a reflux tank. The gas phase in the reflux tank enters an evacuation tank via an ejector, where it is recycled back to the synthesis reactor. Qualified thionyl chloride product is extracted from the middle of the distillation tower. The thionyl chloride production method disclosed in this Chinese patent has the main advantages of being easy to operate and automate, while also reducing the load on the distillation system. However, the thionyl chloride produced is of low purity. Summary of the Invention

[0005] In order to further improve the purity of thionyl chloride, the present application provides a preparation process of thionyl chloride.

[0006] The present application provides a preparation process of thionyl chloride, which adopts the following technical solution: A preparation method of thionyl chloride comprises the following steps: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle, and liquid sulfur is sprayed into the sulfur preparation kettle from the top. The sulfur preparation kettle is filled with activated carbon. (3) The crude thionyl chloride is extracted from the middle of the sulfur preparation kettle and enters the condenser, and the liquid crude thionyl chloride is extracted from the bottom of the condenser; (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. A composite catalyst is attached to the distillation tower, and gaseous crude thionyl chloride is extracted from the middle of the distillation tower. The preparation of the composite catalyst comprises the following steps: S1: diammonium hydrogen phosphate, copper source, calcium nitrate and deionized water are mixed evenly, ammonia water is added, the temperature is increased, the reaction is carried out for 5 hours, the mixture is cooled to room temperature, aged for 24 hours, filtered, washed and dried to obtain copper-doped hydroxyapatite; S2: mixing copper-doped hydroxyapatite and starch, granulating, calcining, cooling, loading sulfur, and drying to obtain a composite catalyst; (5) The crude gaseous thionyl chloride product is then passed into the finished product condenser, and the liquid product is taken out from the bottom of the finished product condenser to obtain thionyl chloride.

[0007] By implementing this technical solution, the sulfur dichloride impurity is removed twice, improving the purity of thionyl chloride and giving it a clear and transparent appearance. Furthermore, the entire reaction system is in a circulating state, effectively eliminating the generation of three wastes pollution while also achieving cost savings and increasing yield.

[0008] By adopting the above technical solution, a catalyst for promoting the decomposition of dichlorothionyl is prepared. The catalyst has the characteristic of being insoluble in thionyl chloride, can efficiently remove the dichlorothionyl impurity in thionyl chloride, and simultaneously, in the process of impurity removal, no new impurities are introduced, and can effectively improve the appearance quality of thionyl chloride and increase the purity of thionyl chloride.

[0009] Preferably, in step (1), the flow rate of chlorine is 70-100m 3 / h, the flow rate of sulfur dioxide is 40-70m 3 / h.

[0010] By adopting the above technical solution, the reaction rate of the reaction is accelerated, thereby improving the production efficiency of thionyl chloride, and it can also ensure that the reactants have a suitable residence time to fully contact and react, thereby improving the conversion rate and product yield, reducing the occurrence of side reactions, and improving the purity of thionyl chloride.

[0011] Preferably, in step (2), the flow rate of the mixed gas is 4600-4800 kg / h, and the flow rate of the liquid sulfur is 360-390 kg / h.

[0012] By adopting the above technical solution, sulfur is fully reacted with sulfur dioxide, the generation of excess sulfur is avoided, and the occurrence of side reactions is reduced. At the same time, the separation rate of the mixed gas within this flow rate range can be improved, thereby ensuring the production efficiency of thionyl chloride and improving the purity of thionyl chloride.

[0013] Preferably, the temperature in the condenser is 50-60°C.

[0014] By adopting the above technical solution, sulfur dioxide and chlorine are separated in gaseous form, while thionyl chloride is effectively condensed and collected; at this temperature, the separated sulfur dioxide and chlorine still have a small amount of energy, which makes it easy to continue to enter the fixed bed for reaction, saving energy, while removing impurities in thionyl chloride and improving the purity of thionyl chloride.

[0015] Preferably, the temperature in the sulfur preparation kettle and the distillation tower is 85-100°C.

[0016] By adopting the above technical solution, sulfur chloride is condensed and collected, and thionyl chloride is effectively separated in a gaseous form and enters the next stage, thereby avoiding the loss of thionyl chloride in a liquid form, reducing the impurity content in thionyl chloride, and improving the purity and yield of thionyl chloride.

[0017] Preferably, in step S1, the mass ratio of diammonium hydrogen phosphate, copper source and calcium nitrate is (1.7-2.1):1:(6.5-7.3).

[0018] By adopting the above technical solution, the prepared copper-doped hydroxyapatite has good stability, and the appropriate copper doping amount effectively promotes the decomposition of dichlorothionyl, improves the purity of thionyl chloride, and does not allow excess free copper ions to enter the thionyl chloride, thereby avoiding new pollution to the thionyl chloride.

[0019] Preferably, in step S1, the copper source is one of copper nitrate, copper phosphate and copper chloride.

[0020] By adopting the above technical solution, copper ions can be fully dissolved and evenly dispersed in the reaction system, which is conducive to full contact and reaction between copper ions and other reactants, thereby improving the uniformity of copper doping, and further improving the performance and structural stability of copper-doped hydroxyapatite, maintaining good activity throughout the catalytic process, and effectively reducing the impurity content in thionyl chloride.

[0021] Preferably, in step S2, the mass ratio of copper-doped hydroxyapatite to starch is (15-19.5):1.

[0022] By adopting the above technical solution, the prepared composite catalyst has high porosity and good mechanical strength, which prevents the composite catalyst from being broken or pulverized during the reaction, extends its service life, and prevents new impurities from entering the thionyl chloride. The high porosity allows the reaction to proceed more fully, increases the impurity removal rate, and improves the purity of the thionyl chloride.

[0023] Preferably, in step S2, the roasting treatment includes drying, pre-roasting and high-temperature roasting; the drying temperature is 80-100°C and the time is 12-15h, the pre-roasting temperature is 300-400°C and the time is 2-3h, and the high-temperature roasting temperature is 700-800°C and the time is 3-4h.

[0024] By adopting the above technical solution, copper-doped hydroxyapatite crystals can grow in a relatively stable environment, reducing the stress and defects caused by the rapid decomposition of starch. At a relatively low temperature in the early stage, the gas generated by the decomposition of starch inside the copper-doped hydroxyapatite particles can slowly escape, forming some small pores. As the temperature rises, these small pores will merge and expand to a certain extent, making the final pore size distribution of the copper-doped hydroxyapatite more uniform, increasing the sulfur loading, and thus improving the catalytic performance of the copper-doped hydroxyapatite composite catalyst, effectively removing impurities in thionyl chloride, and thus improving the purity of thionyl chloride.

[0025] Preferably, the heating rate of the pre-calcination is 1.5-2°C / min, and the heating rate of the high-temperature calcination is 8-10°C / min.

[0026] By adopting the above technical solution, the temperature is slowly increased during pre-baking to gradually carbonize and decompose the starch, and the starch is evenly decomposed into gases such as carbon dioxide and water vapor. These gases can escape gently, which helps to maintain the integrity of the copper-doped hydroxyapatite particles. The temperature is quickly increased during high-temperature calcination, so that the pore structure inside the copper-doped hydroxyapatite particles is further adjusted. During the rapid heating process, the small pores are properly fused and expanded, so that the porosity of the composite catalyst is increased, thereby improving the adsorption performance of the composite catalyst, allowing the reactants to be more fully contacted, and improving the removal rate of impurities in thionyl chloride.

[0027] In summary, this application has the following beneficial effects: 1. The porous, high specific surface area carrier can increase the contact area between the reactants, allowing sulfur dichloride and sulfur to fully react. Compared with directly adding solid sulfur into the distillation tower, it reduces the amount of solid sulfur used, avoids clogging the bottom discharge port of the distillation tower, and improves the yield and purity of thionyl chloride.

[0028] 2. Copper ions are electrophilic, which promotes the polarization of sulfur-chlorine bonds in dichlorothionyl, catalyzes the decomposition of dichlorothionyl, reduces the content of dichlorothionyl byproduct in thionyl chloride, and improves the purity of thionyl chloride. In addition, copper ions replace part of calcium ions and enter the hydroxyapatite crystal structure, making them unable to move freely and will not dissolve in thionyl chloride, so they will not introduce new impurities into the product. DETAILED DESCRIPTION

[0029] The present application is further described in detail below with reference to the embodiments.

[0030] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0031] Example 1 The preparation method of thionyl chloride of the present embodiment comprises the steps: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction at a temperature of 200°C and a flow rate of sulfur dioxide of 40 m / s. 3 / h, the flow rate of chlorine is 70m 3 / h, the amount of sulfur added is 60kg / h; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle at a rate of 4600 kg / h. At the same time, liquid sulfur is sprayed into the sulfur preparation kettle from the upper end at a flow rate of 360 kg / h. Activated carbon is attached to the sulfur preparation kettle. The temperature inside the sulfur preparation kettle is 85°C. Liquid sulfur chloride is extracted from the bottom of the sulfur preparation kettle, enters the sulfur chloride collection tank, and is re-sprayed into the fixed bed of step (1) for reaction; (3) The crude thionyl chloride is extracted from the middle of the sulfur preparation kettle and enters the condenser. The temperature in the condenser is 50°C. The crude liquid thionyl chloride is extracted from the bottom of the condenser, and a mixed gas of sulfur dioxide and chlorine is extracted from the top. The mixed gas of sulfur dioxide and chlorine is directly introduced into the fixed bed of step (1); (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. The temperature in the distillation tower is 85°C. A composite catalyst is attached to the distillation tower. Sulfur chloride is extracted from the bottom of the distillation tower and enters the sulfur chloride collection tank and is re-sprayed into the fixed bed of step (1) for reaction. Gaseous crude thionyl chloride is extracted from the middle. (5) The crude gaseous thionyl chloride is then introduced into a finished product condenser, the temperature of which is 50°C. Sulfur dioxide is extracted from the upper portion of the finished product condenser and the extracted sulfur dioxide gas is directly introduced into the fixed bed of step (1). The liquid product is extracted from the bottom to obtain thionyl chloride.

[0032] The preparation method of the composite catalyst of the present embodiment comprises the following steps: S1: Take 17g of diammonium hydrogen phosphate, 10g of copper nitrate, 65g of calcium nitrate and 400g of deionized water, mix and stir evenly, add 2.8mL of 25% ammonia water by mass, heat to 85℃, continue stirring and react for 5h, cool to room temperature, age for 24h, filter and wash until the pH value of the filtrate is 7, and dry to obtain copper-doped hydroxyapatite; S2: 1500g of copper-doped hydroxyapatite and 100g of starch were placed in a granulator. During the granulation process, a carboxymethyl cellulose aqueous solution with a mass percentage concentration of 1.5% was sprayed to obtain particles with an average particle size of 3mm. The particles were placed in a cool and ventilated place for 24h, then dried in an oven at 100℃ for 12h, transferred to a muffle furnace for calcination, and heated to 400℃ at a heating rate of 1.5℃ / min, kept warm for 2h, and then heated to 700℃ at a heating rate of 10℃ / min, kept warm for 4h, taken out, cooled, put into a reactor, and introduced hydrogen sulfide and sulfur dioxide gas. After 20min, the particles were taken out and dried to obtain a composite catalyst.

[0033] Example 2 The preparation method of thionyl chloride of the present embodiment comprises the steps: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction at a temperature of 250°C and a flow rate of sulfur dioxide of 70 m / s. 3 / h, the flow rate of chlorine is 100m 3 / h, the amount of sulfur added is 80kg / h; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle at a rate of 4800 kg / h. At the same time, liquid sulfur is sprayed into the sulfur preparation kettle from the top at a flow rate of 390 kg / h. Activated carbon is attached to the sulfur preparation kettle. The temperature inside the sulfur preparation kettle is 100°C. Liquid sulfur chloride is extracted from the bottom of the sulfur preparation kettle, enters the sulfur chloride collection tank, and is re-sprayed into the fixed bed for reaction; (3) The crude thionyl chloride is extracted from the middle of the sulfur preparation kettle and enters the condenser. The temperature in the condenser is 60°C. The crude liquid thionyl chloride is extracted from the bottom of the condenser, and a mixed gas of sulfur dioxide and chlorine is extracted from the top. The mixed gas of sulfur dioxide and chlorine is directly introduced into the fixed bed of step (1); (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. The temperature in the distillation tower is 100°C. A composite catalyst is attached to the distillation tower. Sulfur chloride is extracted from the bottom of the distillation tower and enters the sulfur chloride collection tank and is re-sprayed into the fixed bed of step (1) for reaction. Gaseous crude thionyl chloride is extracted from the middle.

[0034] (5) The crude gaseous thionyl chloride is then introduced into the finished product condenser at a temperature of 60°C. Sulfur dioxide is extracted from the upper portion and the extracted sulfur dioxide gas is directly introduced into the fixed bed of step (1). The liquid product is extracted from the bottom of the finished product condenser to obtain thionyl chloride.

[0035] The preparation method of the composite catalyst of the present embodiment comprises the following steps: S1: Take 21g of diammonium hydrogen phosphate, 10g of copper phosphate, 73g of calcium nitrate and 400g of deionized water, mix and stir evenly, add 3.2mL of 25% by mass ammonia water, heat to 85℃, continue stirring and react for 5h, cool to room temperature, age for 24h, filter and wash until the pH value of the filtrate is 7, and dry to obtain copper-doped hydroxyapatite; S2: 1950g of copper-doped hydroxyapatite and 100g of starch were placed in a granulator. During the granulation process, a carboxymethyl cellulose aqueous solution with a mass percentage concentration of 1.5% was sprayed to obtain particles with an average particle size of 3mm. The particles were placed in a cool and ventilated place for 24h, then dried in an oven at 80℃ for 15h, transferred to a muffle furnace for calcination, heated to 300℃ at a heating rate of 2℃ / min, kept warm for 3h, and then heated to 800℃ at a heating rate of 8℃ / min, kept warm for 3h. The particles were taken out, cooled, put into a reactor, and hydrogen sulfide and sulfur dioxide gas were introduced. After 25min, the particles were taken out and dried to obtain a composite catalyst.

[0036] Example 3 The preparation method of thionyl chloride of the present embodiment comprises the steps: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction at a temperature of 250°C and a flow rate of sulfur dioxide of 50 m / s. 3 / h, the flow rate of chlorine is 90m 3 / h, the amount of sulfur added is 65kg / h; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle at a rate of 4700 kg / h. At the same time, liquid sulfur is sprayed into the sulfur preparation kettle from the top at a flow rate of 370 kg / h. Activated carbon is attached to the sulfur preparation kettle. The temperature inside the sulfur preparation kettle is 90°C. Liquid sulfur chloride is extracted from the bottom of the sulfur preparation kettle, enters the sulfur chloride collection tank, and is re-sprayed into the fixed bed for reaction; (3) The crude thionyl chloride is extracted from the middle of the sulfur preparation kettle and enters the condenser. The temperature in the condenser is 52°C. The crude liquid thionyl chloride is extracted from the bottom of the condenser, and a mixed gas of sulfur dioxide and chlorine is extracted from the top. The mixed gas of sulfur dioxide and chlorine is directly introduced into the fixed bed of step (1); (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. The temperature in the distillation tower is 90°C. A composite catalyst is attached to the distillation tower. Sulfur chloride is extracted from the bottom of the distillation tower and enters the sulfur chloride collection tank and is re-sprayed into the fixed bed of step (1) for reaction. Gaseous crude thionyl chloride is extracted from the middle. (5) The crude gaseous thionyl chloride is then introduced into the finished product condenser. The temperature in the finished product condenser is 52°C. Sulfur dioxide is extracted from the upper part of the finished product condenser and the extracted sulfur dioxide gas is directly introduced into the fixed bed of step (1). The liquid product is extracted from the bottom to obtain thionyl chloride.

[0037] The preparation method of the composite catalyst of the present embodiment comprises the following steps: S1: Take 20g of diammonium hydrogen phosphate, 10g of copper chloride, 70g of calcium nitrate and 400g of deionized water, mix and stir evenly, add 3mL of 25% ammonia water by mass, heat to 85℃, continue stirring and react for 5h, cool to room temperature, age for 24h, filter and wash until the pH value of the filtrate is 7, and dry to obtain copper-doped hydroxyapatite; S2: 1750g of copper-doped hydroxyapatite and 100g of starch were placed in a granulator. During the granulation process, a carboxymethyl cellulose aqueous solution with a mass percentage concentration of 1.5% was sprayed to obtain particles with an average particle size of 3mm. The particles were placed in a cool and ventilated place for 24h, then dried in an oven at 95℃ for 13h, transferred to a muffle furnace for calcination, heated to 380℃ at a heating rate of 1.7℃ / min, kept warm for 2.5h, and then heated to 750℃ at a heating rate of 9℃ / min, kept warm for 3.5h, taken out, cooled, put into a reactor, and introduced hydrogen sulfide and sulfur dioxide gas. After 25min, the particles were taken out and dried to obtain a composite catalyst.

[0038] Comparative Example 1 The preparation method of the thionyl chloride of this comparative example comprises the steps: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction at a temperature of 200°C and a flow rate of sulfur dioxide of 40 m / s. 3 / h, the flow rate of chlorine is 70m 3 / h, the amount of sulfur added is 60kg / h; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle at a rate of 4600 kg / h. At the same time, liquid sulfur is sprayed into the sulfur preparation kettle from the upper end at a flow rate of 360 kg / h. Activated carbon is attached to the sulfur preparation kettle. The temperature inside the sulfur preparation kettle is 85°C. Liquid sulfur chloride is extracted from the bottom of the sulfur preparation kettle, enters the sulfur chloride collection tank, and is re-sprayed into the fixed bed of step (1) for reaction; (3) The crude thionyl chloride is extracted from the middle of the sulfur preparation kettle and enters the condenser. The temperature in the condenser is 50°C. The crude liquid thionyl chloride is extracted from the bottom of the condenser, and a mixed gas of sulfur dioxide and chlorine is extracted from the top. The mixed gas of sulfur dioxide and chlorine is directly introduced into the fixed bed of step (1); (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. The temperature in the distillation tower is 85°C. A composite catalyst is attached to the distillation tower. Sulfur chloride is extracted from the bottom of the distillation tower and enters the sulfur chloride collection tank and is re-sprayed into the fixed bed of step (1) for reaction. Gaseous crude thionyl chloride is extracted from the middle. (5) The crude gaseous thionyl chloride is then introduced into a finished product condenser, the temperature of which is 50°C. Sulfur dioxide is extracted from the upper portion of the finished product condenser and the extracted sulfur dioxide gas is directly introduced into the fixed bed of step (1). The liquid product is extracted from the bottom to obtain thionyl chloride.

[0039] The preparation method of the composite catalyst of this comparative example comprises the following steps: mixing 40 g of activated carbon, 5 g of copper nitrate, and 50 g of deionized water, uniformly dispersing the mixture through ultrasonication, filtering, drying the filter residue, placing the mixture into a reactor, introducing hydrogen sulfide and sulfur dioxide gas, taking the mixture out after 20 minutes, and drying the mixture to obtain the composite catalyst.

[0040] Comparative Example 2 The preparation method of the thionyl chloride of this comparative example comprises the steps: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction at a temperature of 200°C and a flow rate of sulfur dioxide of 40 m / s. 3 / h, the flow rate of chlorine is 70m 3 / h, the amount of sulfur added is 60kg / h; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle at a rate of 4600 kg / h. At the same time, liquid sulfur is sprayed into the sulfur preparation kettle from the upper end at a flow rate of 360 kg / h. Activated carbon is attached to the sulfur preparation kettle. The temperature inside the sulfur preparation kettle is 85°C. Liquid sulfur chloride is extracted from the bottom of the sulfur preparation kettle, enters the sulfur chloride collection tank, and is re-sprayed into the fixed bed of step (1) for reaction; (3) The crude thionyl chloride is extracted from the middle of the sulfur preparation kettle and enters the condenser. The temperature in the condenser is 50°C. The crude liquid thionyl chloride is extracted from the bottom of the condenser, and a mixed gas of sulfur dioxide and chlorine is extracted from the top. The mixed gas of sulfur dioxide and chlorine is directly introduced into the fixed bed of step (1); (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. The temperature in the distillation tower is 85°C. A catalyst is attached to the distillation tower. Sulfur chloride is extracted from the bottom of the distillation tower and enters the sulfur chloride collection tank and is re-sprayed into the fixed bed of step (1) for reaction. Gaseous crude thionyl chloride is extracted from the middle. (5) The crude gaseous thionyl chloride is then introduced into a finished product condenser, the temperature of which is 50°C. Sulfur dioxide is extracted from the upper portion of the finished product condenser and the extracted sulfur dioxide gas is directly introduced into the fixed bed of step (1). The liquid product is extracted from the bottom to obtain thionyl chloride.

[0041] The preparation method of the catalyst of this comparative example comprises the following steps: S1: 17 g of diammonium hydrogen phosphate, 75 g of calcium nitrate and 400 g of deionized water were mixed and stirred evenly, 2.8 mL of 25% ammonia water was added, the temperature was raised to 85°C, the reaction was continued with stirring for 5 h, the mixture was cooled to room temperature, aged for 24 h, filtered and washed until the pH value of the filtrate was 7, and dried to obtain hydroxyapatite; S2: 1500g of hydroxyapatite and 100g of starch are placed in a granulator. During the granulation process, a carboxymethyl cellulose aqueous solution with a mass percentage concentration of 1.5% is sprayed to obtain particles with an average particle size of 3mm. The particles are placed in a cool and ventilated place for 24h, then dried in an oven at 100℃ for 12h, transferred to a muffle furnace for calcination, and heated to 400℃ at a heating rate of 1.5℃ / min, kept warm for 2h, and then heated to 700℃ at a heating rate of 10℃ / min, kept warm for 4h, taken out, cooled, put into a reactor, and introduced hydrogen sulfide and sulfur dioxide gas. After 20min, the particles are taken out and dried to obtain a catalyst.

[0042] Performance testing 1. Copper ion content detection Inductively coupled plasma mass spectrometry was used.

[0043] 2. Sulfur dichloride content test Using liquid chromatography, add excess anhydrous ethanol to the test sample, then introduce excess ammonia gas, centrifuge, and take the oil and ester layer for chromatographic analysis.

[0044] 3. Test of sulfur dichloride and thionyl chloride content Gas chromatography was used, and the chromatographic column was a 3.2 m × 3.1 mm glass column filled with OC-210.

[0045] The test data of the content of each component of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1 below: Table 1 Test data of each component content

[0046] Analysis of Examples 1-3 and Comparative Examples 1-2 and in combination with Table 1 shows that after the crude thionyl chloride product is subjected to secondary impurity removal using the composite catalyst, the thionyl chloride has a high purity and does not introduce new impurities.

[0047] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A preparation process for thionyl chloride, characterized in that, The steps include: (1) Sulfur, sulfur dioxide and chlorine are introduced into a fixed bed with activated carbon for reaction; (2) The mixed gas after the reaction is introduced into the sulfur preparation kettle, and liquid sulfur is sprayed into the sulfur preparation kettle from the top. The sulfur preparation kettle contains activated carbon. (3) The crude thionyl chloride is taken out from the middle of the sulfur preparation kettle and enters the condenser, and the liquid crude thionyl chloride is taken out from the bottom of the condenser; (4) Liquid crude thionyl chloride is sprayed into the distillation tower from the top. A composite catalyst is attached to the distillation tower, and gaseous crude thionyl chloride is taken out from the middle of the distillation tower. The preparation of the composite catalyst comprises the following steps: S1: Evenly mix diammonium hydrogen phosphate, copper source, calcium nitrate and deionized water, add ammonia water, heat up, react for 5 hours, cool to room temperature, age for 24 hours, filter, wash, and dry to obtain copper-doped hydroxyapatite; S2: mixing copper-doped hydroxyapatite and starch, granulating, calcining, cooling, loading sulfur, and drying to obtain a composite catalyst; (5) The crude gaseous thionyl chloride is then introduced into the finished product condenser, and the liquid product is taken out from the bottom of the finished product condenser to obtain thionyl chloride.

2. A preparation process for thionyl chloride according to claim 1, characterized in that, In step (1), the flow rate of chlorine gas is 70-100m 3 / h, the flow rate of sulfur dioxide is 40-70m 3 / h.

3. A preparation process for thionyl chloride according to claim 1, characterized in that, In the step (2), the flow rate of the mixed gas is 4600-4800 kg / h, and the flow rate of the liquid sulfur is 360-390 kg / h.

4. A preparation process for thionyl chloride according to claim 1, characterized in that, The temperature in the condenser and the finished product condenser is 50-60°C.

5. A preparation process for thionyl chloride according to claim 1, characterized in that, The temperature in the sulfur preparation kettle and the distillation tower is 85-100°C.

6. A preparation process for thionyl chloride according to claim 1, characterized in that, In the step S1, the mass ratio of diammonium hydrogen phosphate, copper source and calcium nitrate is (1.7-2.1):1:(6.5-7.3).

7. A preparation process for thionyl chloride according to claim 1, characterized in that, In the step S1, the copper source is one of copper nitrate, copper phosphate and copper chloride.

8. A preparation process for thionyl chloride according to claim 1, characterized in that, In step S2, the mass ratio of copper-doped hydroxyapatite to starch is (15-19.5):

1.

9. A process for preparing thionyl chloride according to claim 1, characterized in that, In step S2, the roasting treatment includes drying, pre-roasting and high-temperature roasting; the drying temperature is 80-100°C, the time is 12-15h, the pre-roasting temperature is 300-400°C, the time is 2-3h, and the high-temperature roasting temperature is 700-800°C, the time is 3-4h.

10. A process for preparing thionyl chloride according to claim 9, characterized in that: The heating rate of the pre-calcination is 1.5-2°C / min, and the heating rate of the high-temperature calcination is 8-10°C / min.

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