A clean production process for sulfur-containing silanes

Abstract

This invention belongs to the field of sulfur-containing silane production technology, and particularly relates to a clean production process for sulfur-containing silanes, comprising the following steps: Step S1, synthesizing mercaptopropyltriethoxysilane; S2, reacting the obtained mercaptopropyltriethoxysilane liquid with iodine solution and iodine in carbon tetrachloride solution in a reaction tower, with the generated hydrogen iodide discharged from the top of the reaction tower; Step S3, after the reaction, the mixture of liquid product and unreacted mercaptopropyltriethoxysilane is pumped from the bottom of the reaction tower into a vacuum distillation tower for separation to obtain qualified Si-75 product, and the unreacted mercaptopropyltriethoxysilane is recovered and returned to the reaction tower. This achieves recycling to reduce raw material costs, minimizes the types of materials used in the process, avoids the difficulties of using and handling solid materials, and thus enables high-capacity, low-cost, clean production of the sulfur-containing silane sulfurizing agent Si-75.

Description

Technical Field

[0001] This invention belongs to the field of sulfur-containing silane production technology, and particularly relates to a clean production process for sulfur-containing silanes. Background Technology

[0002] Sulfur-containing mercaptosilane coupling agents have a wide range of applications, with mercaptopropyltriethoxysilane being the most widely used, primarily as a rubber vulcanization accelerator. The main production process for mercaptopropyltriethoxysilane involves the reaction of chloropropylsilane with thiourea or sodium thiolate. Mercaptopropyltriethoxysilane can be reacted with S2Cl2 to produce the rubber vulcanizing agent Si-69, a key raw material for green tire production. Sulfur-containing silane vulcanizing agent Si-75 is a disulfide compound that overcomes the drawback of premature vulcanization and scorching associated with Si-69. It represents an upgraded replacement for green tire raw materials and has significant market demand. Currently, it is produced using a complex phase transfer reaction process and has been patented, for example, by CN201610229521.3 and CN202020481759.7. The superior performance of the new generation of sulfur-containing silane vulcanizing agents NXT and VP-Si-363 requires mercaptopropyltriethoxysilane as a raw material to produce high-purity products. However, the current production process for mercaptopropylsilanes is costly and expensive, severely limiting the use of high-purity new sulfur-containing silane vulcanizing agents. While the direct reaction of haloalkylalkoxysilanes and hydrogen sulfide can produce mercaptopropylsilanes with high selectivity and better halogen recycling, the high-pressure reaction process raises safety concerns and hinders its use in production facilities. Yantai Tongye Chemical Technology Co., Ltd. in my country has successfully implemented a large-scale, high-efficiency, low-cost production facility with a capacity exceeding 10,000 tons, directly reacting sulfur and hydrogen to synthesize hydrogen sulfide. Therefore, researching a reasonable process and equipment to directly react hydrogen sulfide to produce mercaptopropylsilanes, with simple raw materials, can significantly reduce the production cost of sulfur-containing silanes. In addition, Shanghai Chlor-Alkali Co., Ltd. and Yantai Wanhua Chemical Group Co., Ltd. have respectively launched patented technologies for large-scale fixed-bed and fluidized-bed processes to catalytically oxidize excess hydrogen chloride and oxygen into chlorine for low-cost recycling. Technological cooperation can reduce the difficulty of building large-scale plants.

[0003] The currently used sulfur-containing silane production process has high raw material costs and a variety of auxiliary raw materials. Some of these involve the use of solid raw materials that are easy to agglomerate and difficult to disperse, such as anhydrous solid sulfur and sodium sulfide. The large amount of solid sodium chloride produced as a byproduct requires crystallization and filtration separation. The production process requires the separation and isolation of moisture, which makes the dispersion and mass transfer of raw materials and the separation of solid byproducts very difficult. The process is highly corrosive and requires high corrosion resistance of equipment. As a result, the process flow, operation control and equipment maintenance are very complex. Due to the low material recycling capacity and the large amount of waste, it is difficult to achieve large-capacity, low-cost, clean production. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned technical problems by providing a clean production process for sulfur-containing silanes. This process achieves recycling to reduce raw material costs, minimizes the types of materials used in the process, and avoids the difficulties of using and handling solid materials. As a result, it enables high-capacity, low-cost, and clean production of sulfur-containing silane vulcanizing agent Si-75.

[0005] In view of this, the present invention provides a clean production process for sulfur-containing silanes, characterized by comprising the following steps:

[0006] Step S1: Chloropropyltriethoxysilane and hydrogen sulfide liquid are pressurized by pumps and flowed into a multi-layer sieve plate reactor. Then, the gas and liquid phases after the reaction in the multi-layer sieve plate reactor are fed into a stripping tower reactor. Fresh, pure, high-temperature hydrogen sulfide gas is introduced into the bottom of the stripping tower reactor to expel the hydrogen chloride generated in the reaction. After the reaction is completed, the reaction products flowing out of the stripping tower reactor are collected and post-processed to obtain mercaptopropyltriethoxysilane.

[0007] Step S2: The mercaptopropyltriethoxysilane liquid obtained in step S1 is reacted with iodine solution and iodine in carbon tetrachloride solution in a reaction tower. The hydrogen iodide generated in the reaction is discharged from the top of the reaction tower.

[0008] Step S3: After the reaction is completed, the liquid product and the unreacted mercaptopropyltriethoxysilane mixture are pumped from the bottom of the reaction tower into a vacuum distillation tower for separation to obtain qualified Si-75 product. The unreacted mercaptopropyltriethoxysilane is recovered and returned to the reaction tower.

[0009] In this technical solution, elemental iodine and its carbon tetrachloride solution react with mercaptopropyltriethoxysilane in a distillation column to synthesize the disulfide compound Si-75. This is a highly selective and high-conversion reaction with quantitative reaction properties. The types of materials in its reaction system are much fewer than those in existing production patents. It does not require the addition of complex composite solvents and catalysts, making the product easy to separate and purify. After the iodine is converted into hydrogen iodide, it can be recovered and recycled at low cost by combustion reaction with inexpensive chlorine gas. The process does not require solid treatment, making it easy to design for energy saving. The equipment is compact and occupies a small area, achieving a high-capacity, low-cost, clean production process.

[0010] In the above technical solution, further, the pressure inside the multi-layer sieve plate tower reactor in step S1 is 15-25 MPa and the reaction temperature is 120-180℃, and the pressure inside the gas stripping tower reactor is 8-14 MPa and the reaction temperature is increased to 180-240℃.

[0011] In the above technical solution, further, the pressure inside the reaction tower in step S2 is -0.1 to 0.1 MPa, and the reaction temperature is 40 to 240°C.

[0012] In this technical solution, a multi-layer sieve plate tower-type high-pressure reactor with co-flow of gas and liquid is used to achieve the function of a plug flow reactor that maintains gas-liquid mixing. This improves the selectivity and conversion rate of the direct gas-liquid phase reaction of hydrogen sulfide and chloropropyltriethoxysilane to synthesize mercaptosilane under high pressure. Simultaneously, fresh, pure, high-temperature hydrogen sulfide gas is introduced into the bottom of the gas-lift tower reactor, causing the gas to flow upward. Since the boiling point of hydrogen sulfide is higher than that of hydrogen chloride, the heat it carries raises the temperature, causing the dissolved hydrogen chloride in the liquid to vaporize and flow towards the top of the tower. This reduces the hydrogen chloride content in the downward-flowing liquid, thereby promoting the complete conversion of chloropropylsilane to mercaptopropyltriethoxysilane. Because the reaction process is not corrosive to carbon steel and stainless steel, this invention can use a vertical high-tower-type reaction device with a small footprint to ensure the safety and economy of the direct reaction of chloropropyltriethoxysilane and hydrogen sulfide to synthesize mercaptopropyltriethoxysilane.

[0013] In the above technical solution, the gas phase at the top of the gas tower reactor is mainly composed of hydrogen chloride and hydrogen sulfide. The hydrogen chloride and hydrogen sulfide at the top are discharged into a distillation column. The top of the distillation column is equipped with a condenser. The condenser discharges hydrogen chloride in gaseous or liquid form into a hydrogen chloride collection and storage system. The bottom of the distillation column yields a mixed liquid mainly composed of hydrogen sulfide. After being pressurized by a pump and heated by a heater, it is used as the reaction material in the multi-layer sieve plate tower reactor.

[0014] In this technical solution, hydrogen chloride, either in gaseous or liquid form, is discharged into a hydrogen chloride collection and storage system to serve as a raw material for the trichlorosilane synthesis unit. Trichlorosilane is used to produce chloropropyltriethoxysilane chloride, thereby improving the rational use of resources. The reboiler at the bottom of the column can be heated using the reaction heat of the sieve plate reactor. A liquid containing mainly hydrogen sulfide is obtained at the bottom of the distillation column. After being pressurized and reheated by a pump, it is distributed as needed to the parallel-flow sieve plate reactors connected in series as a reaction raw material.

[0015] In the above technical solution, the multi-layer sieve tray reactor further includes:

[0016] Inlet and outlet;

[0017] The cylinder is arranged vertically, and multiple layers of sieve plates are horizontally installed inside the cylinder. A lower grid is installed close to the upper end of the sieve plates, and a heat exchange coil is provided at the upper end of part of the lower grid. An upper grid is provided at the upper end of the heat exchange coil.

[0018] In this technical solution, the slow reaction rate results in a small temperature rise in the reaction zone. The upper and lower grids are used to clamp and prevent the heat exchange coils from vibrating. The heat exchange tower sections are arranged discontinuously and dispersedly on the tower body, which enables segmented and optimized temperature control of the reactor. It is not necessary to set up many heat exchange tubes inside the reaction zone to control the reaction temperature, which simplifies the equipment structure.

[0019] In the above technical solution, further, the sieve plate is provided with a plurality of through holes, the diameter of the through holes is 2 to 5 mm, and the spacing between the through holes is 10 to 15 mm.

[0020] In this technical solution, the sieve plate enhances the mass transfer in the reaction zone through small-hole jet disturbance, which blocks the axial backmixing of the liquid in the reactor and makes the liquid flow velocity nearly uniformly distributed across the entire cross section of the tower to create a plug flow. This allows the reactor to achieve the function of a tubular plug flow reactor, which is beneficial to improving reaction selectivity and conversion rate.

[0021] In the above technical solution, the heat exchange coil is further defined as a horizontal Archimedean equidistant spiral.

[0022] In this technical solution, the heat exchange coil is made by using the Archimedes equidistant spiral principle to reduce the temperature difference in the reaction zone. The disturbance of the small-aperture close-range jet makes the heat exchange coil obtain a high heat transfer coefficient, which can increase the residence time of the reactants in the reactor, thereby improving the reaction efficiency.

[0023] In the above technical solution, further, there are multiple multi-layer sieve plate tower reactors, and the multiple multi-layer sieve plate tower reactors are connected in series through the feed inlet and the discharge outlet.

[0024] In this technical solution, a series tower with a compact structure and small footprint is used to connect multiple multi-layer sieve plate reactors in series, thereby obtaining an ultra-long flow channel to meet the residence time required for slow reactions, thus improving the reaction conversion rate of chloropropyltriethoxysilane.

[0025] In the above technical solution, the hydrogen iodide discharged in step S2 is further purified and then burned with dry chlorine in a pressurized combustion furnace. The combustion produces iodine solution, hydrogen gas and hydrogen chloride, which are then recycled.

[0026] In the above technical solution, hydrogen iodide and chlorine are further heated with high-temperature liquid iodine before being mixed and burned.

[0027] In this technical solution, hydrogen iodide and chlorine are heated to 100-250°C by high-temperature liquid iodine to facilitate stable combustion, which can increase the flame temperature of the pressurized combustion furnace to 800-1300°C, making it easier for chlorine to react quickly and completely, and reducing the consumption of chlorine.

[0028] The beneficial effects of this invention are:

[0029] 1. The synthesis of disulfide compounds Si-75 by reacting elemental iodine and its carbon tetrachloride solution with mercaptopropyltriethoxysilane in a distillation column is a highly selective and high-conversion reaction with quantitative reaction properties. The types of materials in its reaction system are much fewer than those in existing production patents. It does not require the addition of complex composite solvents and catalysts, making the product easy to separate and purify. After the iodine is converted into hydrogen iodide, it can be recovered and recycled at low cost by combustion reaction with inexpensive chlorine gas. The process does not require solid treatment, making it easy to design for energy saving. The equipment is compact and occupies a small area, making it easy to achieve a high-capacity, low-cost, clean production process.

[0030] 2. A multi-layer sieve plate tower-type high-pressure reactor with co-flow of gas and liquid is used to achieve the function of a plug flow reactor that maintains gas-liquid mixing. This improves the selectivity and conversion rate of the direct gas-liquid phase reaction of hydrogen sulfide and chloropropyltriethoxysilane to synthesize mercaptosilane under high pressure. At the same time, fresh, pure, high-temperature hydrogen sulfide gas is introduced into the bottom of the gas stripping tower reactor, causing the gas to flow upward. Since the boiling point of hydrogen sulfide is higher than that of hydrogen chloride, the heat it carries raises the temperature, causing the dissolved hydrogen chloride in the liquid to vaporize and flow towards the top of the tower. This reduces the hydrogen chloride content in the downward flowing liquid, thereby promoting the complete conversion of chloropropylsilane to mercaptopropyltriethoxysilane.

[0031] 3. The reaction process of hydrogen sulfide and chloropropyltriethoxysilane is not corrosive to carbon steel and stainless steel. This invention can use a vertical tower-shaped reaction device with a small footprint to ensure the safety and economy of directly reacting chloropropyltriethoxysilane and hydrogen sulfide to synthesize mercaptopropyltriethoxysilane. Attached Figure Description

[0032] Figure 1 This is a flow chart of the reaction apparatus for synthesizing mercaptopropylsilane by direct reaction of chloropropylsilane and hydrogen sulfide in a clean production process of sulfur-containing silanes according to the present invention.

[0033] Figure 2 This is a schematic diagram of the structure of a multi-layer sieve tray reactor for the clean production process of sulfur-containing silanes according to the present invention.

[0034] Figure 3 This is a schematic diagram of the internal structure of the main tower section of a multi-layer sieve tray reactor in a clean production process for sulfur-containing silanes according to the present invention.

[0035] Figure 4 This is a schematic diagram of the internal structure of a multi-layer sieve tray reactor with heat exchange function in a clean production process of sulfur-containing silanes according to the present invention.

[0036] Figure 5 This is a flowchart of the Si-75 synthesis process for a clean production process of sulfur-containing silanes according to the present invention.

[0037] Figure 6 This is a process diagram of a hydrogen iodide pressurized combustion furnace temperature control process for a clean production process of sulfur-containing silanes according to the present invention;

[0038] The markings in the diagram are as follows:

[0039] 1. Multi-layer sieve plate tower reactor; 2. Feed inlet; 3. Discharge outlet; 4. Main inlet pipe for heat medium; 5. Main outlet pipe for heat medium; 6. Shell; 7. Sieve plate; 8. Lower grid; 9. Heat exchange coil; 10. Upper grid; 11. Through hole; 12. Pressurized combustion furnace. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0041] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0042] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0043] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0044] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0045] Example 1:

[0046] Depend on Figures 1-6 As shown, this embodiment provides a clean production process for sulfur-containing silanes, including the following steps:

[0047] Step S1: Chloropropyltriethoxysilane and liquid hydrogen sulfide are pressurized by pumps and flowed into multi-layer sieve tray reactor 1. Then, the gas and liquid phases after the reaction in multi-layer sieve tray reactor 1 are fed together into a stripping tower reactor. Fresh, pure, high-temperature hydrogen sulfide gas is introduced into the bottom of the stripping tower reactor to expel the hydrogen chloride generated in the reaction. After the reaction is completed, the reaction product flowing out of the stripping tower reactor is collected and post-processed to obtain mercaptopropyltriethoxysilane. Step S2: The mercaptopropyltriethoxysilane liquid obtained in step S1 is reacted with iodine solution and iodine in carbon tetrachloride solution in a reaction tower. The hydrogen iodide generated in the reaction is discharged from the top of the reaction tower. Step S3: After the reaction is completed, the liquid product and the unreacted mercaptopropyltriethoxysilane mixture are pumped from the bottom of the reaction tower into a vacuum distillation tower for separation to obtain qualified Si-75 product. The unreacted mercaptopropyltriethoxysilane is recovered and returned to the reaction tower.

[0048] In the above technical solution, further, in step S1, the pressure inside the multi-layer sieve plate tower reactor 1 is 15-25 MPa, and the reaction temperature is 120-180℃; the pressure inside the gas stripping tower reactor is 8-14 MPa, and the reaction temperature is increased to 180-240℃.

[0049] In this technical solution, the reactants flow in parallel from the bottom to the top of the tower. Hydrogen sulfide has a low boiling point, and increasing the reaction pressure of the multi-layer sieve plate tower reactor 1 is beneficial for hydrogen sulfide to dissolve in the liquid phase and prolong its residence time in the reaction zone. Although increasing the reaction temperature is beneficial for increasing the reaction rate, a higher reaction pressure must be used to prevent hydrogen sulfide from leaving the reaction zone too quickly. The hydrogen chloride generated in the reaction has a low boiling point and will preferentially accelerate upward flow in the gaseous state, carrying some hydrogen sulfide away from the reaction zone.

[0050] In the above technical solution, further, the pressure inside the reaction tower in step S2 is -0.1 to 0.1 MPa, and the reaction temperature is 40 to 240°C.

[0051] In the above technical solution, the multi-layer sieve plate 7 tower reactor 1 further includes: a feed inlet 2 and a discharge outlet 3; a cylinder 6, which is arranged in a vertical direction, and a multi-layer sieve plate 7 is horizontally installed inside the cylinder 6. A lower grid 8 is installed close to the upper end of the sieve plate 7, and a heat exchange coil 9 is provided at the upper end of part of the lower grid 8. An upper grid 10 is provided at the upper end of the heat exchange coil 9.

[0052] In this technical solution, the temperature rise in the reaction zone is very small due to the slow reaction rate. The upper grid 10 and the lower grid 8 are clamped together to prevent the heat exchange coil 9 from vibrating. The heat exchange tower sections are set up discontinuously and dispersedly on the tower body, so that the reactor can be optimized for segmented temperature control. It is not necessary to set up many heat exchange tubes inside the reaction zone to control the reaction temperature, which facilitates the simplification of the equipment structure.

[0053] In the above technical solution, further, a plurality of through holes 11 are evenly distributed on the sieve plate 7, the diameter of the through holes 11 is 2 to 5 mm, and the spacing between the through holes 11 is 10 to 15 mm.

[0054] In this technical solution, the sieve plate 7 enhances the mass transfer in the reaction zone through small-hole jet disturbance, which blocks the axial backmixing of the liquid in the reactor and makes the liquid flow velocity nearly uniformly distributed across the entire cross section of the tower to form a plug flow. This allows the reactor to achieve the function of a tubular plug flow reactor, which is beneficial to improving reaction selectivity and conversion rate.

[0055] In the above technical solution, the heat exchange coil 9 is further described as having a horizontal Archimedean equidistant spiral shape.

[0056] In this technical solution, the heat exchange coil 9 is made by using the Archimedes equidistant spiral principle to reduce the temperature difference in the reaction zone. The heat exchange coil 9 can obtain a high heat transfer coefficient by using the small-hole close-range jet disturbance, which can increase the residence time of the reactants in the reactor, thereby improving the reaction efficiency.

[0057] In the above technical solution, further, there are multiple multi-layer sieve plate tower reactors 1, and the multiple multi-layer sieve plate tower reactors 1 are connected in series through the feed inlet 2 and the discharge outlet 3.

[0058] In this technical solution, a series tower with a compact structure and small footprint is used to connect multiple multi-layer sieve plate tower reactors 1 in series, thereby obtaining an ultra-long flow channel to meet the residence time required for slow reactions, thereby improving the reaction conversion rate of chloropropyltriethoxysilane.

[0059] Specifically, a multi-layer sieve tray reactor (multi-layer sieve tray high-pressure reactor) 1 with co-current gas-liquid flow achieves the function of a plug flow reactor that maintains gas-liquid mixing. This improves the selectivity and conversion rate of the direct gas-liquid phase reaction of hydrogen sulfide and chloropropyltriethoxysilane to synthesize mercaptosilane under high pressure. Simultaneously, fresh, pure, high-temperature hydrogen sulfide gas is introduced into the bottom of the stripping tower reactor, causing the gas to flow upwards. Since hydrogen sulfide has a higher boiling point than hydrogen chloride, its heat-carrying capacity raises the temperature, causing the dissolved hydrogen chloride in the liquid to vaporize and flow towards the top of the tower, thereby reducing the concentration of hydrogen chloride in the downward-flowing liquid. The hydrogen chloride content promotes the complete conversion of chloropropylsilane to mercaptopropyltriethoxysilane. Since the reaction process is non-corrosive to carbon steel and stainless steel, this invention utilizes a compact, vertical, high-tower reaction unit to ensure the safe and economical direct synthesis of mercaptopropyltriethoxysilane from chloropropyltriethoxysilane and hydrogen sulfide. All tower-type equipment in the process has a simple internal structure, allowing for segmented processing at a chemical machinery plant before being transported to the chemical plant construction site for welding and assembly into a very tall tower unit. This avoids the difficulties of transporting large, high-pressure equipment by road due to its weight and length. Although the equipment operates at high pressure, this invention avoids corrosion problems. It does not involve unstable substances prone to spontaneous explosion or polymerization, nor does it involve mass transfer problems, blockage, or wear risks associated with solid materials. Gas-liquid phase material transfer and storage are convenient, and the process and operation are simple, easily enabling highly automated control of a large-capacity single-unit reaction unit.

[0060] In the above technical solution, the gas phase at the top of the gas tower reactor is mainly composed of hydrogen chloride and hydrogen sulfide. The hydrogen chloride and hydrogen sulfide at the top are discharged into a distillation column. The top of the distillation column is equipped with a condenser. The condenser discharges hydrogen chloride in gaseous or liquid form into a hydrogen chloride collection and storage system. A mixed liquid mainly composed of hydrogen sulfide is obtained at the bottom of the distillation column. The mixed liquid is used as the reaction material in the multi-layer sieve tray reactor 1.

[0061] In this technical solution, hydrogen chloride is discharged into the hydrogen chloride collection and storage system in gaseous or liquid form as a raw material for the trichlorosilane synthesis device. Trichlorosilane is used to produce chloropropyltriethoxysilane chloride, thereby improving the rational use of resources. The reboiler at the bottom of the column can be heated by the reaction heat of the multi-layer sieve plate reactor 1. A liquid containing mainly hydrogen sulfide is obtained at the bottom of the distillation column. After being pressurized and reheated by a pump, it is distributed as needed to the parallel-flow sieve plate reactors connected in series as a reaction raw material.

[0062] Example 2:

[0063] Depend on Figure 5 As shown, this embodiment provides a clean production process for sulfur-containing silanes, which, in addition to the technical solutions of the above embodiments, also has the following technical features:

[0064] After achieving simple, efficient, low-cost, and clean production of mercaptopropyltriethoxysilane through the above methods, mercaptopropyltriethoxysilane can be further used as a raw material to produce Si-75, NTX, and VP-Si-363 on a large scale at low cost, which can promote the upgrading of production processes in the green tire manufacturing industry. A method for achieving high-quality, large-scale, low-cost, and clean production of Si-75 coupling agent is illustrated below. Liquid mercaptopropyltriethoxysilane is reacted with iodine solution and a carbon tetrachloride solution of iodine in a reaction column with a structure similar to a bubble-cap plate distillation column, primarily constructed of nickel-molybdenum alloy for corrosion resistance. The pressure inside the reaction column is -0.1 to 0.1 MPa, and the reaction temperature is 40 to 240°C. The preheated liquid mercaptopropylsilane is mixed with a portion of the high-temperature iodine solution at the top of the column before entering the reaction column. A small amount of carbon tetrachloride solution is used as a reflux at the top of the column to intercept the rising iodine gas and mercaptopropylsilane. The resulting high-boiling-point product flows to the bottom of the column. The remaining hot iodine solution is divided into multiple streams and sprayed into the lower part of the reaction column at different flow rates to maintain optimal reactant concentration distribution. A gas-liquid phase bubbling reaction occurs on the trays. The generated hydrogen iodide rises and exits from the top of the column. This reaction releases very little heat, and since the generation of hydrogen iodide gas is endothermic, sufficient reaction temperature is maintained within the column by heating with a falling film evaporator in the bottom of the column. Most of the liquid mercaptopropylsilane reacts to convert into the liquid product Si-75. The mixture of liquid product and unreacted mercaptopropylsilane is pumped from the bottom of the reactor into a vacuum distillation column for separation to obtain qualified Si-75 product. Unreacted mercaptopropylsilane is recovered and returned to the reaction column. The generated hydrogen iodide gas is sent to a distillation column for purification using a magnetically driven Roots compressor. The purified hydrogen iodide, maintained at an excess of 3–30%, is mixed with dry chlorine gas and burned in a 0–0.6 MPa combustion furnace. Before combustion, both hydrogen iodide and chlorine are sequentially heated to 100–250°C with high-temperature liquid iodine to promote stable combustion, increasing the flame temperature to 800–1300°C, facilitating rapid and complete reaction of chlorine, and reducing chlorine consumption. Pressurized combustion can significantly reduce the size of the furnace body, thus lowering the difficulty of equipment manufacturing. It can also obtain high-temperature circulating liquid iodine at 240-300℃ as a high-temperature heat medium to utilize the high-temperature heat energy released by combustion. The pressurized hydrogen / hydrogen chloride mixture generated by the reaction can also be easily purified by reflux distillation of hydrogen chloride liquid through a condenser at -30 to -40℃, thereby reducing refrigeration energy consumption.

[0065] Specifically, the synthesis of disulfide compounds Si-75 by reacting elemental iodine and its carbon tetrachloride solution with mercaptopropyltriethoxysilane in a distillation column is a highly selective and high-conversion reaction with quantitative reaction properties. The types of materials in its reaction system are much fewer than those in existing production patents, and there is no need to add complex composite solvents and catalysts, making the product easy to separate and purify. After the iodine is converted into hydrogen iodide, it can be recovered and recycled at low cost by combustion reaction with inexpensive chlorine gas. The process does not require solid processing, making it easy to design for energy saving. The equipment is compact and occupies a small area, achieving a high-capacity, low-cost, clean production process.

[0066] To ensure safety, such as Figure 6As shown, the pressurized combustion furnace 12 uses a cylindrical shroud made of permeable graphite with excellent thermal conductivity and resistance to high-temperature iodine vapor corrosion to surround the high-temperature flame. The graphite cylindrical shroud is cooled by liquid iodine spraying. Inside the furnace body, an annular liquid trough is made of materials such as nickel-molybdenum alloy, which is resistant to high-temperature liquid iodine. Liquid iodine is evenly distributed through a sawtooth overflow weir at the top of the annular trough and flows down from the annular gap into the liquid iodine bottom trough along the annular trough wall. This allows the high-temperature combustion gas flowing up along the annular gap to be evaporated and cooled by the liquid iodine. A graphite lining ring is used to prevent the metal wall surface from being corroded by high temperature. This design effectively prevents the risk of runaway high temperature and rapid damage to the outer cylinder caused by factors such as failure of the liquid iodine circulation pump. The pressure-bearing outer furnace body is made of thick nickel-molybdenum alloy / steel composite plates that can withstand high-temperature liquid iodine corrosion, and a semi-pipe jacket is welded to the outer wall of the outer cylinder. This jacket carries heat transfer oil, which can utilize the heat of reaction and provides convenience for the start-up of the combustion furnace. The combustion furnace is positioned higher than the iodine storage tank to facilitate rapid emptying of the iodine in case of an accident. The furnace is also designed to be close to a dedicated, pressure-resistant, large-capacity carbon tetrachloride storage tank at ambient temperature and pressure. This tank maintains a suitable amount of liquid carbon tetrachloride and is equipped with a liquid circulation pump connected to a spray system that washes the tank's inner walls. This allows for low-resistance flow of emergency depressurization from the combustion furnace or depressurization from a rupture disc during an accident into the carbon tetrachloride storage tank. The high-temperature iodine vapor generated during depressurization flashes is then cooled, sprayed, absorbed, and recycled by the liquid carbon tetrachloride, preventing emissions pollution. High-temperature combustion gas containing hydrogen, hydrogen chloride, and gaseous iodine is cooled by heat absorption in the graphite cylinder as it flows downwards in the reaction zone. As it flows upwards along the annular gap, it is further cooled by contact with liquid iodine. After being further cooled by the externally circulating liquid iodine outside the graphite cylinder, it enters the carbon tetrachloride scrubbing tower. A hot carbon tetrachloride solution containing iodine is obtained at the bottom of the tower. The liquid in the upper part of the tower does not contain iodine and has a very low freezing point, allowing for the safe generation of a large amount of waste heat for the recovery of liquid hydrogen iodide and the vaporization of the raw material liquid chlorine, while also meeting the heating requirements of the atmospheric pressure carbon tetrachloride distillation tower and the hydrogen iodide distillation tower. Currently, domestic manufacturers have produced graphite towers with diameters up to Φ2600, so large graphite hoods can be used to build single-unit high-capacity combustion furnaces, improving economic efficiency. The hydrogen chloride / hydrogen mixture obtained from the combustion furnace is sent to the trichlorosilane synthesis section for use. Trichlorosilane is used to produce chloropropyltriethoxysilane. The by-product hydrogen from the trichlorosilane synthesis section is then sent to the hydrogen sulfide production section to react with elemental sulfur to produce hydrogen sulfide, which is then supplied back to the mercaptosilane synthesis section. At the same time, the newly generated iodine and iodine in carbon tetrachloride solution are recycled back to react with mercaptopropylsilane to produce Si-75, which can significantly reduce production costs.

[0067] The domestic technology for the equipment, materials, and processing involved in the construction of the aforementioned Si-75 production unit can well meet domestic needs. Its stable operation phase only requires handling gas-liquid phase materials, without involving the heterogeneous mass transfer problems associated with solids. Because material transport and mass transfer are easy, the equipment can be compactly arranged with a small footprint. It is also easy to reduce investment by using a single high-capacity unit, thus minimizing the use of expensive materials. Similarly, NXT synthesizes Si-75 through the reaction of octanoyl chloride and mercaptopropyltriethoxysilane, a miscible liquid-liquid reaction that requires no catalyst and reacts easily to completion. Because the process does not involve the solid phase and there are no equipment corrosion problems, the byproduct hydrogen chloride gas can be easily separated, purified, and recycled. Therefore, it is easy to achieve a high-capacity single-unit reaction unit. The process of producing VP-Si-363 using mercaptopropyltriethoxysilane also only involves gas-liquid phase transport and mass transfer, without equipment corrosion problems, thus also making it easy to achieve a single high-capacity reaction unit.

[0068] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A clean production process for sulfur-containing silanes, characterized in that, Includes the following steps: Step S1: Chloropropyltriethoxysilane and hydrogen sulfide liquid are pressurized by pumps and flowed into multi-layer sieve plate reactor (1). Then, the gas and liquid phases after the reaction in multi-layer sieve plate reactor (1) are fed into a gas stripping tower reactor. Fresh pure high-temperature hydrogen sulfide gas is introduced into the bottom of the gas stripping tower reactor to expel the hydrogen chloride generated in the reaction. After the reaction is completed, the reaction products flowing out of the gas stripping tower reactor are collected and post-processed to obtain mercaptopropyltriethoxysilane. Step S2: The mercaptopropyltriethoxysilane liquid obtained in step S1 is reacted with iodine solution and iodine in carbon tetrachloride solution in a reaction tower. The hydrogen iodide generated in the reaction is discharged from the top of the reaction tower. Step S3: After the reaction is completed, the liquid product and the unreacted mercaptopropyltriethoxysilane mixture are pumped from the bottom of the reaction tower into a vacuum distillation tower for separation to obtain qualified Si-75 product. The unreacted mercaptopropyltriethoxysilane is recovered and returned to the reaction tower.

2. The clean production process for sulfur-containing silanes according to claim 1, characterized in that, The pressure inside the multi-layer sieve plate reactor (1) in step S1 is 15-25 MPa and the reaction temperature is 120-180°C. The pressure inside the gas stripping tower reactor is 8-14 MPa and the reaction temperature is increased to 180-240°C.

3. The clean production process for sulfur-containing silanes according to claim 1, characterized in that, The pressure inside the reaction tower in step S2 is -0.1 to 0.1 MPa, and the reaction temperature is 40 to 240°C.

4. The clean production process for sulfur-containing silanes according to claim 1, characterized in that, The gas phase at the top of the gas tower reactor is mainly composed of hydrogen chloride and hydrogen sulfide. The hydrogen chloride and hydrogen sulfide at the top are discharged into a distillation column. The top of the distillation column is equipped with a condenser. The condenser discharges hydrogen chloride in gaseous or liquid form into a hydrogen chloride collection and storage system. The bottom of the distillation column obtains a mixed liquid mainly composed of hydrogen sulfide. After being pressurized by a pump and heated by a heater, it is used as the reaction material in the multi-layer sieve plate reactor (1).

5. The clean production process for sulfur-containing silanes according to claim 2, characterized in that, The multi-layer sieve tray reactor (1) includes: Inlet (2) and outlet (3); A cylindrical body (6) is arranged vertically. Multiple layers of sieve plates (7) are horizontally installed inside the cylindrical body (6). A lower grid (8) is installed close to the upper end of the sieve plate (7). A heat exchange coil (9) is provided at the upper end of part of the lower grid (8). An upper grid (10) is provided at the upper end of the heat exchange coil (9).

6. The clean production process for sulfur-containing silanes according to claim 5, characterized in that, The sieve plate (7) is provided with a plurality of through holes (11) evenly distributed on it. The diameter of the through holes (11) is 2 to 5 mm and the spacing between the through holes (11) is 10 to 15 mm.

7. The clean production process for sulfur-containing silanes according to claim 5, characterized in that, There are multiple multi-layer sieve plate tower reactors (1), and the multiple multi-layer sieve plate tower reactors (1) are connected in series through the feed inlet (2) and the discharge outlet (3).

8. The clean production process for sulfur-containing silanes according to claim 5, characterized in that, The heat exchange coil (9) is in the shape of a horizontal Archimedean equidistant spiral.

9. The clean production process for sulfur-containing silanes according to claim 1, characterized in that, The hydrogen iodide discharged in step S2 is purified and then burned with dry chlorine in a pressurized combustion furnace (12). The combustion produces iodine solution, hydrogen gas and hydrogen chloride, which are then recycled.

10. A clean production process for sulfur-containing silanes according to claim 9, characterized in that, Before the hydrogen iodide and chlorine are mixed and burned, they are each heated sequentially with high-temperature liquid iodine.

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