Efficient preparation method and system of methyl sodium silicate

Abstract

The invention discloses an efficient preparation method and system of sodium methyl silicate, and relates to the technical field of sodium methyl silicate production. The efficient preparation method of the methyl sodium silicate comprises the following steps: preheating methyl trichlorosilane to be gaseous, introducing the gaseous methyl trichlorosilane into a reaction tower, keeping a certain temperature and pressure in the reaction tower, spraying a high-concentration hydrochloric acid solution into the reaction tower by adopting a spray head, hydrochloric acid and methyl trichlorosilane gas are subjected to a contact reaction to generate small-particle methyl sodium silicate, the small-particle methyl sodium silicate flows into the bottom of the reaction tower, solid-liquid separation is completed through a centrifugal machine, and solids obtained through separation are washed with water; and transferring the washed solid into a reaction kettle, completing substitution reaction with a sodium hydroxide solution under certain conditions, and concentrating and drying to obtain a sodium methyl silicate solid. The sodium methyl silicate is prepared by adopting the reaction tower, so that the reaction is more uniform, and the efficiency is higher; hydrochloric acid is used as a reaction medium, so that the byproduct hydrogen chloride can be effectively recovered, and the green and environment-friendly purposes are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sodium methyl silicate production, and in particular to a high-efficiency preparation method and system of sodium methyl silicate. Background Art

[0002] Sodium methyl silicate is an advanced rigid building waterproof material. Its unique permeability and crystallization properties have attracted much attention in the construction industry. The molecular structure of this material contains silanol groups, which can undergo dehydration and cross-linking reactions with silanol groups in silicate materials to form an excellent hydrophobic layer with an "anti-capillary effect". This hydrophobic layer can not only effectively prevent water penetration, but also increase the density of the material through micro-expansion, thereby significantly improving the waterproof performance of the building. This is the core mechanism of the efficient waterproofing effect of silicone waterproofing agents.

[0003] At present, the conventional method for producing sodium methyl silicate mainly involves the use of a ratio of monomethyltrichlorosilane and dimethyldichlorosilane, such as the Chinese patent applications with application numbers 201610533059.6 and 98123919.6. Under conditions below 40°C, these two substances will undergo a hydrolysis reaction to generate methylsilicic acid. Subsequently, at a temperature of 80-90°C, methylsilicic acid will undergo a substitution reaction with sodium hydroxide to eventually generate sodium methyl silicate.

[0004] However, the existing production process has some obvious shortcomings. Since the temperature of the hydrolysis reaction must be strictly controlled below 40°C to prevent further polymerization of the active silicic acid, this limits the reaction to a certain extent, resulting in an incomplete reaction and a long reaction time. At the same time, the substitution reaction is carried out at a high temperature of 80-90°C, which is too intense and difficult to control, which not only affects the yield of the product, but may also have adverse effects on the environment. Summary of the invention

[0005] In view of the above problems, the present invention provides a method and system for efficiently preparing sodium methyl silicate.

[0006] The highly efficient preparation method of sodium methyl silicate comprises the following steps: S1, preheating monomethyltrichlorosilane to make it gaseous and then passing it into the reaction tower; S2, using a nozzle to spray a high concentration hydrochloric acid solution into the reaction tower, so that the hydrochloric acid and monomethyltrichlorosilane gas are in contact and reacted, and the temperature and pressure inside the reaction tower are controlled; S3, the hydrogen chloride gas generated in the reaction in step S2 is collected for preparing a high-concentration hydrochloric acid solution, and the methylsilicic acid solid-liquid mixture generated in the reaction in step S2 is transferred to a primary buffer tank, and nitrogen is introduced to keep the solid in a suspended state for further reaction; S4, using a centrifuge to separate the suspension in the primary buffer tank into solid and liquid, returning the separated liquid to the reaction tower for recycling, washing the separated solid with water to obtain methylsilicic acid, and mixing the acid liquid after washing with the hydrogen chloride gas generated in the reaction process to prepare a high-concentration hydrochloric acid solution for reuse; S5. The washed methylsilicic acid is transferred into a substitution reaction kettle to complete the substitution reaction with a sodium hydroxide solution to prepare a sodium methyl silicate solution, which is then concentrated, filtered and dried to obtain a sodium methyl silicate solid.

[0007] Preferably, the temperature of the preheating treatment in step S1 is 70-75° C., which can ensure that monomethyltrichlorosilane is fully converted into a gaseous state.

[0008] Preferably, the mass ratio of monomethyltrichlorosilane to high concentration hydrochloric acid solution in step S2 is 1:4-7.

[0009] Preferably, the concentration of hydrogen chloride in the high-concentration hydrochloric acid solution described in step S2 is 30wt%~33wt%.

[0010] Preferably, the liquid spraying direction of the nozzle in step S2 is adjusted according to the nozzle angle, and the nozzle angle A ranges from 30° to 60°.

[0011] Preferably, the number of nozzles described in step S2 is 4 to 8.

[0012] Preferably, the internal temperature of the reaction tower in step S2 is 30-45° C., and the reaction pressure is 0.1-0.2 MPa.

[0013] Preferably, the reaction time in step S3 is 1 to 1.5 h.

[0014] Preferably, the water washing in step S4 is washing the methylsilicic acid solid with neutral water or alkaline water until the pH value is 5-6.

[0015] Preferably, the concentration of the sodium hydroxide solution described in step S5 is 35wt%~45wt%.

[0016] Preferably, the mass ratio of methylsilicic acid to sodium hydroxide solution in step S5 is 1:2-3.

[0017] Preferably, the temperature of the substitution reaction in step S5 is 70-90° C., and the substitution reaction time is 1-2 h.

[0018] Preferably, the sodium methyl silicate solid described in step S5 is white, has a solid content of more than 98%, a pH of 12-13, and a density of 1.1-1.2 g / cm 3 .

[0019] The invention discloses an efficient preparation system of sodium methyl silicate, comprising: a discharge end of a high-concentration hydrochloric acid solution storage tank connected to a feed end of a reaction tower, a discharge end of a monomethyltrichlorosilane storage tank connected to the feed end of the reaction tower through a preheater, a primary buffer tank connected to a liquid discharge end of the reaction tower, an acid-making tank connected to a gas discharge end of the reaction tower, the discharge end of the primary buffer tank connected to a centrifuge, the liquid discharge end of the centrifuge connected to the feed end of the reaction tower, the solid discharge end of the centrifuge connected to a cleaning tank, the liquid discharge end of the cleaning tank connected to the feed end of the acid-making tank, the solid discharge end of the cleaning tank and a sodium hydroxide solution storage tank connected to a substitution reactor, the discharge end of the substitution reactor connected to a concentration, filtration and drying system, the liquid discharge end of the concentration, filtration and drying system connected to a feed end of a water transfer tank, and the feed and discharge end of the water transfer tank connected to the feed end of the cleaning tank.

[0020] Preferably, a nozzle with adjustable angle is provided at 1 / 2 to 3 / 4 of the height in the reaction tower.

[0021] Compared with the prior art, the beneficial effects of the present invention are: 1. High efficiency of production equipment: Compared with reactors, the use of reaction towers to prepare methylsilicic acid can achieve continuous production. After monomethyltrichlorosilane is heated to a gaseous state and mixed with sprayed hydrochloric acid inside the reaction tower, the heat generated by the dissolution of hydrogen chloride gas in water during the hydrolysis process can be quickly released, so that the reaction temperature remains basically constant, avoiding the high temperature causing the hydrolysis and condensation of monomethyltrichlorosilane into abnormally large solids. The hydrochloric acid is fed by a high-pressure nozzle with a certain spray angle. When it fully contacts and reacts with the monomethyltrichlorosilane gas, it can also achieve the purpose of flushing the wall of the reaction tower, avoiding the deposition of methylsilicic acid solids on the tower wall and causing the reaction tower to be blocked.

[0022] 2. Recycling of hydrogen chloride: Using high-concentration hydrochloric acid solution as a hydrolysis solvent can reduce the solubility of hydrogen chloride gas during the hydrolysis process, and high-purity hydrogen chloride gas can be recovered; the low-concentration hydrochloric acid solution after water washing is dissolved with hydrogen chloride gas to re-prepare high-concentration hydrochloric acid solution, and then continue to return to the reaction production stage to achieve the purpose of green recycling.

[0023] 3. Thorough reaction and uniform product: By adjusting the appropriate raw material ratio and using high-concentration hydrochloric acid solution as the hydrolysis solvent, the hydrolysis rate of monomethyltrichlorosilane is reduced to avoid excessive condensation of monomethyltrichlorosilane and condensation into hard particles; at the same time, nitrogen is used to blow the crude methylsilicic acid product, and the unreacted silicon-chlorine bonds are further hydrolyzed and condensed. After nitrogen blowing and balancing, the methylsilicic acid particles are finer and more uniform.

[0024] 4. The synthesis conditions of sodium methyl silicate are mild and the product yield is high, with a yield of >78%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a schematic diagram of an efficient preparation system of sodium methyl silicate.

[0026] Figure 2 This is the front view of the nozzle inside the reaction tower.

[0027] Figure 3 This is a top view of the nozzle inside the reaction tower. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention is further described below by way of examples. The raw materials used in the examples can be purchased from the market or prepared by conventional methods.

[0029] Example 1 An efficient preparation system for sodium methyl silicate, such as Figure 1 As shown, it includes: a high-concentration hydrochloric acid solution storage tank is connected to the feed end of the reaction tower, the discharge end of the monomethyltrichlorosilane storage tank is connected to the feed end of the reaction tower through a preheater, a primary buffer tank is connected to the liquid discharge end of the reaction tower, an acid-making tank is connected to the gas discharge end of the reaction tower, the discharge end of the primary buffer tank is connected to a centrifuge, the liquid discharge end of the centrifuge is connected to the feed end of the reaction tower, the solid discharge end of the centrifuge is connected to a cleaning tank, the liquid discharge end of the cleaning tank is connected to the feed end of the acid-making tank, the solid discharge end of the cleaning tank and the sodium hydroxide solution storage tank are connected to the substitution reactor, the discharge end of the substitution reactor is connected to a concentration, filtration and drying system, the liquid discharge end of the concentration, filtration and drying system is connected to the feed end of a water transfer tank, and the feed and discharge end of the water transfer tank is connected to the feed end of the cleaning tank; as shown Figure 2 and Figure 3 As shown, a nozzle with adjustable angle is arranged at 1 / 2 to 3 / 4 of the height in the reaction tower.

[0030] Example 2 A method for efficiently preparing sodium methyl silicate using the system in Example 1 comprises the following steps: S1, pass monomethyltrichlorosilane into the preheater, control the preheating temperature to 70 ° C, make monomethyltrichlorosilane gaseous and then pass it into the reaction tower, according to the mass ratio m 一甲基三氯硅烷 :m 高浓度盐酸溶液 =1:5 to prepare a high-concentration hydrochloric acid solution with a mass fraction of hydrogen chloride of 30%, and make it turn into mist droplets evenly distributed in the reaction tower after passing through the nozzle. The number of special nozzles is controlled to be 4, the injection angle A=45°, the internal temperature of the reaction tower is controlled to be 30 ℃, and the reaction pressure is controlled to be 0.1 MPa; S2. After the initial hydrolysis is completed, the materials in the reaction tower are transferred to the primary buffer tank, and nitrogen is continuously introduced to keep the liquid in the primary buffer tank in a surging state, while maintaining the residence time of the mixture in the tank for 1 h; S3. Separate the methylsilicic acid solid-liquid mixture in the primary buffer tank by using a centrifuge, wash the methylsilicic acid solid with neutral water until the pH is 5-6, and mix the separated low-concentration hydrochloric acid liquid, washing water and hydrogen chloride generated in the reaction process in an acid-making tank to prepare a 30-33% hydrochloric acid solution for continued reuse; S4, according to the raw material ratio m 甲基硅酸 :m 氢氧化钠溶液 =1:2 prepare a sodium hydroxide solution with a mass concentration of 45%, put the methyl silicate solid into the reactor, control the reaction temperature to 70 ℃, and the reaction time to 1 h; after the reaction is completed, distill and concentrate the sodium methyl silicate solution, filter and dry it, and the waste liquid obtained flows into the water transfer tank and is used for the next cleaning treatment. The white solid obtained is sodium methyl silicate.

[0031] After testing, the solid content of the prepared sodium methyl silicate was 98.1%, pH = 12 ~ 13, and the density was 1.13 g / cm 3 ; The yield of sodium methyl silicate was calculated to be 78.5%.

[0032] Example 3 A method for efficiently preparing sodium methyl silicate using the system in Example 1 comprises the following steps: S1, pass monomethyltrichlorosilane into the preheater, control the preheating temperature to 70 ° C, make monomethyltrichlorosilane gaseous and then pass it into the reaction tower, according to the mass ratio m 一甲基三氯硅烷 :m 高浓度盐酸溶液 =1:6 Prepare a hydrochloric acid solution with a mass fraction of hydrogen chloride of 30%, and make it pass through a special nozzle and then turn it into mist droplets evenly distributed in the reaction tower. The number of special nozzles is controlled to be 4, the spray angle A=45°, the internal temperature of the reaction tower is controlled to be 30 ℃, and the reaction pressure is controlled to be 0.1 MPa; S2. After the initial hydrolysis is completed, the materials in the reaction tower are transferred to the primary buffer tank, and nitrogen is continuously introduced to keep the liquid in the primary buffer tank in a surging state, while maintaining the residence time of the mixture in the tank for 1 hour; S3. Separate the methylsilicic acid solid-liquid mixture in the primary buffer tank by using a centrifuge, wash the methylsilicic acid solid with neutral water until the pH is 5-6, and mix the separated low-concentration hydrochloric acid liquid, washing water and hydrogen chloride generated in the reaction process in an acid-making tank to prepare a 30-33% hydrochloric acid solution for continued reuse; S4, according to the raw material ratio m 甲基硅酸 :m 氢氧化钠溶液=1:2 prepare a sodium hydroxide solution with a mass concentration of 45%, put the methyl silicate solid into the reactor, control the reaction temperature to 70 ℃, and the reaction time to 1 h; after the reaction is completed, distill and concentrate the sodium methyl silicate solution, filter and dry it, and the waste liquid obtained flows into the water transfer tank and is used for the next cleaning treatment. The white solid obtained is sodium methyl silicate.

[0033] After testing, the solid content of the prepared sodium methyl silicate was 98.2%, pH = 12 ~ 13, and the density was 1.12 g / cm 3 ; The yield of sodium methyl silicate was calculated to be 78.8%.

[0034] Example 4 A method for efficiently preparing sodium methyl silicate using the system in Example 1 comprises the following steps: S1, pass monomethyltrichlorosilane into the preheater, control the preheating temperature to 70 ℃, make monomethyltrichlorosilane become gaseous and then pass it into the reaction tower, according to the mass ratio m 一甲基三氯硅烷 :m 高浓度盐酸溶液 =1:7 Prepare a hydrochloric acid solution with a mass fraction of hydrogen chloride of 30%, and make it pass through a special nozzle and then turn it into mist droplets evenly distributed in the reaction tower. The number of special nozzles is controlled to be 4, the spray angle A=45°, the internal temperature of the reaction tower is controlled to be 30 ℃, and the reaction pressure is controlled to be 0.1 MPa; S2. After the initial hydrolysis is completed, the materials in the reaction tower are transferred to the primary buffer tank, and nitrogen is continuously introduced to keep the liquid in the primary buffer tank in a surging state, while maintaining the residence time of the mixture in the tank for 1 h; S3. Separate the methylsilicic acid solid-liquid mixture in the primary buffer tank by using a centrifuge, wash the methylsilicic acid solid with neutral water until the pH is 5-6, and mix the separated low-concentration hydrochloric acid liquid, washing water and hydrogen chloride generated in the reaction process in an acid-making tank to prepare a 30-33% hydrochloric acid solution for continued reuse; S according to the raw material ratio m 甲基硅酸 :m 氢氧化钠溶液 =1:2 prepare a sodium hydroxide solution with a mass concentration of 45%, put the methyl silicate solid into the reactor, control the reaction temperature to 70 ℃, and the reaction time to 1 h; after the reaction is completed, distill and concentrate the sodium methyl silicate solution, filter and dry it, and the waste liquid obtained flows into the water transfer tank and is used for the next cleaning treatment. The white solid obtained is sodium methyl silicate.

[0035] After testing, the solid content of the prepared sodium methyl silicate was 98.1%, pH = 12 ~ 13, and the density was 1.15 g / cm 3 ; The yield of sodium methyl silicate was calculated to be 79.2%.

[0036] Comparative Example 1 A method for efficiently preparing sodium methyl silicate using the system in Example 1 comprises the following steps: S1, pass monomethyltrichlorosilane into the preheater, control the preheating temperature to 70 ℃, make monomethyltrichlorosilane become gaseous and then pass it into the reaction tower, according to the mass ratio m 一甲基三氯硅烷 :m 高浓度盐酸溶液 =1:3 Prepare a hydrochloric acid solution with a mass fraction of hydrogen chloride of 30%, and make it pass through a special nozzle and turn it into mist droplets evenly distributed in the reaction tower. The number of special nozzles is controlled to be 4, the injection angle A=45°, the internal temperature of the reaction tower is controlled to be 30 ℃, and the reaction pressure is controlled to be 0.1 MPa; S2, when the quality of the hydrochloric acid solution is too small, the hydrogen chloride released during the hydrolysis of monomethyltrichlorosilane cannot be absorbed quickly, part of the monomethyltrichlorosilane is entrained into the tail gas, and large pieces of hard solid appear during the hydrolysis and polycondensation process; S3. Separate the methylsilicic acid solid-liquid mixture in the primary buffer tank by using a centrifuge, wash the methylsilicic acid solid with neutral water until the pH is 5-6, and mix the separated low-concentration hydrochloric acid liquid, washing water and hydrogen chloride generated in the reaction process in an acid-making tank to prepare a 30-33% hydrochloric acid solution for continued reuse; S4, according to the raw material ratio m 甲基硅酸 :m 氢氧化钠溶液 =1:2 prepare a sodium hydroxide solution with a mass concentration of 45%, put the methyl silicate solid into the reactor, control the reaction temperature to 70 ℃, and the reaction time to 1 h; after the reaction is completed, distill and concentrate the sodium methyl silicate solution, filter and dry it, and the waste liquid obtained flows into the water transfer tank and is used for the next cleaning treatment. The white solid obtained is sodium methyl silicate.

[0037] After testing, the solid content of the prepared sodium methyl silicate was 97.6%, pH = 12 ~ 13, and the density was 1.01 g / cm 3 ; The yield of sodium methyl silicate was calculated to be 58%.

[0038] Comparative Example 2 A method for efficiently preparing sodium methyl silicate using the system in Example 1, wherein the preparation method is substantially consistent with that in Example 1, except that in step S1, monomethyltrichlorosilane is not preheated, and monomethyltrichlorosilane is directly in contact with a high concentration hydrochloric acid solution in a liquid form.

[0039] As a result, a violent reaction occurred in the reaction tower, and large pieces of solid were produced rapidly, which eventually blocked the pipeline outlet. Moreover, the obtained methylsilicic acid solid particles were uneven in size, and some of the solids were very hard and difficult to react during the replacement process.

[0040] It is understood that the above embodiments are only used to illustrate the present invention and are not used to limit the protection scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. An efficient preparation method of sodium methyl silicate, characterized in that: The following steps are involved: S1, preheating monomethyltrichlorosilane to make it gaseous and then passing it into the reaction tower; S2, using a nozzle to spray a high concentration hydrochloric acid solution into the reaction tower, so that the hydrochloric acid and monomethyltrichlorosilane gas are in contact and reacted, and the temperature and pressure inside the reaction tower are controlled; S3, the hydrogen chloride gas generated in the reaction in step S2 is collected for preparing a high-concentration hydrochloric acid solution, and the methylsilicic acid solid-liquid mixture generated in the reaction in step S2 is transferred to a primary buffer tank, and nitrogen is introduced to keep the solid in a suspended state for further reaction; S4, using a centrifuge to separate the suspension in the primary buffer tank into solid and liquid, returning the separated liquid to the reaction tower for recycling, washing the separated solid with water to obtain methylsilicic acid, and mixing the acid liquid after washing with the hydrogen chloride gas generated in the reaction process to prepare a high-concentration hydrochloric acid solution for reuse; S5. The washed methylsilicic acid is transferred into a substitution reaction kettle to complete the substitution reaction with a sodium hydroxide solution to prepare a sodium methyl silicate solution, which is then concentrated, filtered and dried to obtain a sodium methyl silicate solid.

2. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The temperature of the preheating treatment in step S1 is 70-75°C.

3. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The concentration of hydrogen chloride in the high-concentration hydrochloric acid solution described in step S2 is 30wt%~33wt%; the mass ratio of monomethyltrichlorosilane to the high-concentration hydrochloric acid solution described in step S2 is 1:4~7.

4. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The liquid spraying direction of the nozzle described in step S2 is adjusted according to the nozzle angle, and the nozzle angle A ranges from 30° to 60°. The number of nozzles described in step S2 is 4 to 8.

5. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The internal temperature of the reaction tower described in step S2 is 30-45° C., and the reaction pressure is 0.1-0.2 MPa.

6. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The reaction time in step S3 is 1 to 1.5 h.

7. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The water washing in step S4 is to use neutral water or alkaline water to wash the methylsilicic acid solid until the pH value is 5-6.

8. The efficient preparation method of sodium methyl silicate according to claim 1, characterized in that: The concentration of the sodium hydroxide solution described in step S5 is 35wt%~45wt%; The mass ratio of methylsilicic acid to sodium hydroxide solution in step S5 is 1:2-3; The temperature of the substitution reaction in step S5 is 70-90° C., and the substitution reaction time is 1-2 h.

9. An efficient preparation system for sodium methyl silicate, characterized in that: The efficient preparation method of sodium methyl silicate according to any one of claims 1 to 8 is implemented by utilizing the efficient preparation system of sodium methyl silicate, and the efficient preparation system of sodium methyl silicate comprises: a discharge end of a high-concentration hydrochloric acid solution storage tank is connected to a feed end of a reaction tower, a discharge end of a methyltrichlorosilane storage tank is connected to a feed end of a reaction tower through a preheater, a primary buffer tank is connected to a liquid discharge end of the reaction tower, an acid-making tank is connected to a gas discharge end of the reaction tower, the discharge end of the primary buffer tank is connected to a centrifuge, the liquid discharge end of the centrifuge is connected to the feed end of the reaction tower, the solid discharge end of the centrifuge is connected to a cleaning tank, the liquid discharge end of the cleaning tank is connected to the feed end of the acid-making tank, the solid discharge end of the cleaning tank and a sodium hydroxide solution storage tank are connected to a substitution reactor, the discharge end of the substitution reactor is connected to a concentration, filtration and drying system, the liquid discharge end of the concentration, filtration and drying system is connected to a feed end of a water transfer tank, and the feed and discharge end of the water transfer tank is connected to the feed end of the cleaning tank.

10. The efficient preparation system of sodium methyl silicate according to claim 9, characterized in that: A nozzle with adjustable angle is arranged at 1 / 2 to 3 / 4 of the height in the reaction tower.

Images