Multi-stage separation method for oil in dimethyl dichlorosilane hydrolysis byproduct acid

Abstract

The invention discloses a multistage separation method of oil in dimethyl dichlorosilane hydrolysis byproduct acid, which is used for removing organic oil impurities in dimethyl dichlorosilane hydrolysis byproduct hydrochloric acid, and comprises the following steps: S1, static pre-separation: introducing the dimethyl dichlorosilane hydrolysis byproduct hydrochloric acid to be treated into a static settling tank; most easily separated oil drops in the byproduct hydrochloric acid are removed; s2, introducing the byproduct hydrochloric acid treated in the step S1 into a high-shear device, adding a polymer demulsifier, and stirring to promote oil drop coalescence; s3, deeply filtering the demulsified acid liquor by adopting a strong acid-resistant, temperature-resistant and anti-pollution ceramic membrane, and intercepting fine oil drops; and S4, introducing the byproduct hydrochloric acid filtered in the S3 into an activated carbon adsorption column, and adsorbing residual trace soluble organic matters and pigments. Compared with the prior art, the multi-stage separation method for the oil in the dimethyl dichlorosilane hydrolysis byproduct acid has the advantages of being convenient to operate and use, efficient, low in cost and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of organosilicon production by-product treatment technology, specifically to a multi-stage separation method for oil in acid produced by the hydrolysis of dimethyldichlorosilane. Background Technology

[0002] In the industrial process of producing polysiloxanes by hydrolysis of organosilicon monomers (dimethyldichlorosilane), a large amount of hydrochloric acid with a concentration of 20-35% is generated as a byproduct.

[0003] The by-product hydrochloric acid generally contains 0.5%-2% organic oil impurities, the main components of which are methylchlorosilane oligomers, cyclic / linear siloxanes, etc. These organic oils are stably dispersed in hydrochloric acid in the form of microemulsions or fine droplets, and are difficult to separate naturally.

[0004] Currently, the industry mainly uses traditional static separation or gravity sedimentation to separate organic oil from the by-product hydrochloric acid. These methods have extremely low separation efficiency, and the oil content in the hydrochloric acid after treatment is still as high as 0.3%-0.5%, far exceeding the standard requirements for high-quality industrial hydrochloric acid.

[0005] The high oil content means that the by-product hydrochloric acid cannot be used to produce high-purity hydrogen chloride or recycled in the chloromethane synthesis process, nor can it be sold for high-value utilization. Ultimately, it can only be treated as hazardous waste. This not only brings huge hazardous waste treatment costs, but also causes serious waste of hydrochloric acid resources. At the same time, it faces environmental emission pressure, and the residual organic oil can cause problems such as equipment blockage, pipeline corrosion, and catalyst pollution, posing significant safety risks. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a multi-stage separation method for oil in the by-product acid from the hydrolysis of dimethyldichlorosilane that is easy to operate and use, and can be applied efficiently, at low cost and in an environmentally friendly manner.

[0007] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a multi-stage separation method for oil in dimethyldichlorosilane hydrolysis by-product acid, used to remove organic oil impurities from dimethyldichlorosilane hydrolysis by-product hydrochloric acid, comprising the following steps:

[0008] S1: Static pre-separation: The hydrochloric acid byproduct of the hydrolysis of dimethyldichlorosilane to be treated is introduced into a static settling tank to remove most of the easily separable oil droplets in the byproduct hydrochloric acid;

[0009] S2: The by-product hydrochloric acid after step S1 is introduced into a high-shear device, a polymer demulsifier is added and stirred to promote the coalescence of oil droplets;

[0010] S3: A ceramic membrane that is resistant to strong acids, high temperatures, and pollution is used to deeply filter the acidic liquid after demulsification, trapping fine oil droplets;

[0011] S4: The hydrochloric acid byproduct filtered in S3 is passed into an activated carbon adsorption column to adsorb residual trace amounts of soluble organic matter and pigments.

[0012] S5: The organic oil content in the by-product hydrochloric acid is ≤0.1%, the total organic oil recovery rate is ≥98%, and the color of the by-product hydrochloric acid is ≤50 Hazen.

[0013] Preferably, the organic oil impurities include methylchlorosilane oligomers and cyclic / linear siloxanes dispersed in the form of microemulsions or fine droplets.

[0014] Preferably, in S1, the static settling tank is controlled by adjusting the angle of the inclined plate and the temperature to regulate the settling.

[0015] The angle of the inclined plate is 30-60°, and the temperature range is 40-60℃.

[0016] Preferably, the polymer demulsifier in S2 is a modified polyether demulsifier or a polyamide demulsifier, and the amount added is 0.01-0.05% of the mass of the by-product hydrochloric acid, and the acute toxicity LD50 of the demulsifier is [not specified]. 50 >5000mg / kg.

[0017] Preferably, the high-shear device in S2 rotates at 1500-3000 rpm, the processing time is 5-15 min, and the temperature of the by-product hydrochloric acid during the processing is 40-55℃.

[0018] Preferably, the ceramic membrane in S3 that is resistant to strong acids, high temperatures, and pollution is α-alumina or silicon carbide, with a membrane pore size of 0.1-1 μm and a filtration operating pressure of 0.2-0.5 MPa.

[0019] Preferably, the activated carbon in S4 is columnar granular activated carbon with a specific surface area of ​​800-1200 m². 2 / g, adsorption space velocity of 1-3h-1, adsorption column operating temperature of 30-50℃, and pretreated with hydrochloric acid.

[0020] Preferably, the hydrochloric acid pretreatment in S4 involves soaking in 10-15% hydrochloric acid for 24 hours followed by drying.

[0021] Preferably, S1-S4 further includes joint optimization through CFD fluid simulation and system orthogonal experiment, wherein the factors in the orthogonal experiment include static settling temperature, high shear speed, demulsifier addition amount, and ceramic membrane filtration pressure.

[0022] The advantages of this invention compared to the prior art are:

[0023] In this invention, through a four-stage coupling process, the organic oil content in the by-product hydrochloric acid is stably reduced to below 0.1%, the total organic oil recovery rate is ≥98%, and the color of the by-product hydrochloric acid is ≤50 Hazen, which fully meets the high-quality industrial hydrochloric acid standard.

[0024] The waste heat from the hydrolysis reaction is used to preheat hydrochloric acid, reducing external energy consumption; low-cost, environmentally friendly demulsifiers and acid-resistant ceramic membranes are selected to reduce equipment investment and operating costs.

[0025] To avoid problems such as equipment blockage, corrosion, and catalyst contamination caused by organic oil, thereby reducing production safety risks. Detailed Implementation

[0026] The present invention will now be described in further detail.

[0027] As shown, a multi-stage separation method for oil in dimethyldichlorosilane hydrolysis by-product acid is used to remove organic oil impurities from dimethyldichlorosilane hydrolysis by-product hydrochloric acid, comprising the following steps:

[0028] S1: Static pre-separation: The hydrochloric acid byproduct of the hydrolysis of dimethyldichlorosilane to be treated is introduced into a static settling tank to remove most of the easily separable oil droplets in the byproduct hydrochloric acid;

[0029] S2: The by-product hydrochloric acid after step S1 is introduced into a high-shear device, a polymer demulsifier is added and stirred to promote the coalescence of oil droplets;

[0030] S3: A ceramic membrane that is resistant to strong acids, high temperatures, and pollution is used to deeply filter the acidic liquid after demulsification, trapping fine oil droplets;

[0031] S4: The hydrochloric acid byproduct filtered in S3 is passed into an activated carbon adsorption column to adsorb residual trace amounts of soluble organic matter and pigments.

[0032] S5: The organic oil content in the by-product hydrochloric acid is ≤0.1%, the total organic oil recovery rate is ≥98%, and the color of the by-product hydrochloric acid is ≤50 Hazen.

[0033] The organic oil impurities include methylchlorosilane oligomers and cyclic / linear siloxanes dispersed in the form of microemulsions or fine droplets, while the static settling tank in S1 controls the settling through the angle of the inclined plate and temperature.

[0034] The angle of the inclined plate is 30-60°, and the temperature range is 40-60℃.

[0035] The polymer demulsifier in S2 is a modified polyether demulsifier or a polyamide demulsifier, and the addition amount is 0.01-0.05% of the mass of the by-product hydrochloric acid, and the acute toxicity LD50 of the demulsifier is specified. 50>5000mg / kg, wherein the high shear device rotates at 1500-3000rpm, the processing time is 5-15min, and the temperature of the by-product hydrochloric acid during the processing is 40-55℃.

[0036] In S3, the ceramic membrane, which is resistant to strong acids, high temperatures, and fouling, is made of α-alumina or silicon carbide with a pore size of 0.1-1 μm and a filtration operating pressure of 0.2-0.5 MPa. In S4, the activated carbon is columnar granular activated carbon with a specific surface area of ​​800-1200 m². 2 / g, adsorption space velocity of 1-3h-1, adsorption column operating temperature of 30-50℃, and pretreated with hydrochloric acid.

[0037] In S4, the hydrochloric acid pretreatment involves soaking in 10-15% hydrochloric acid for 24 hours followed by drying.

[0038] In one embodiment:

[0039] S1-S4 also include joint optimization through CFD fluid simulation and system orthogonal experiments, where the factors in the orthogonal experiments include static settling temperature, high shear speed, demulsifier addition amount, and ceramic membrane filtration pressure.

[0040] In a specific implementation of this invention, the angle of the inclined plate in the static settling tank is 45°, the hydrochloric acid is preheated to 50°C using the residual heat from hydrolysis, the settling time is 2 hours, the mixture is separated, 0.03% of a modified polyether demulsifier is added, the high shear device rotates at 2000 rpm, the processing time is 10 minutes, and the temperature is 48°C.

[0041] An α-alumina ceramic membrane with a pore size of 0.5 μm was selected for filtration at an operating pressure of 0.3 MPa and a temperature of 48 °C. Columnar granular activated carbon with a specific surface area of ​​1000 m² was also used. 2 / g, soaked in 12% hydrochloric acid for 24h and dried, adsorption space velocity 2h-1, temperature 40℃, adsorption;

[0042] The organic oils separated in each step are collected and purified by vacuum distillation at a vacuum degree of -0.096 MPa and a temperature of 100℃, with a recovery rate of 98.5%, and can be returned to the hydrolysis production system.

[0043] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0044] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0045] The present invention and its embodiments have been described above. This description is not restrictive, and the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and, without departing from the spirit of the invention, design similar structures and embodiments without creative effort, such designs should fall within the protection scope of the present invention.

Claims

1. A multi-stage separation method for oil from acid produced by the hydrolysis of dimethyldichlorosilane, characterized in that: The method for removing organic oil impurities from hydrochloric acid, a byproduct of dimethyldichlorosilane hydrolysis, includes the following steps: S1: Static pre-separation: The hydrochloric acid byproduct of the hydrolysis of dimethyldichlorosilane to be treated is introduced into a static settling tank to remove most of the easily separable oil droplets in the byproduct hydrochloric acid; S2: The by-product hydrochloric acid after step S1 is introduced into a high-shear device, a polymer demulsifier is added and stirred to promote the coalescence of oil droplets; S3: A ceramic membrane that is resistant to strong acids, high temperatures, and pollution is used to deeply filter the acidic liquid after demulsification, trapping fine oil droplets; S4: The hydrochloric acid byproduct filtered in S3 is passed into an activated carbon adsorption column to adsorb residual trace amounts of soluble organic matter and pigments. S5: The organic oil content in the by-product hydrochloric acid is ≤0.1%, the total organic oil recovery rate is ≥98%, and the color of the by-product hydrochloric acid is ≤50 Hazen.

2. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 1, characterized in that: The organic oil impurities include methylchlorosilane oligomers and cyclic / linear siloxanes dispersed in the form of microemulsions or fine droplets.

3. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 1, characterized in that: In S1, the static settling tank is controlled by adjusting the angle of the inclined plate and the temperature to regulate the settling process. The angle of the inclined plate is 30-60°, and the temperature range is 40-60℃.

4. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 1, characterized in that: The polymer demulsifier in S2 is a modified polyether demulsifier or a polyamide demulsifier, and the amount added is 0.01-0.05% of the mass of the by-product hydrochloric acid, and the acute toxicity LD50 of the demulsifier is specified. 50 >5000mg / kg.

5. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 4, characterized in that: The high-shear device in S2 operates at a speed of 1500-3000 rpm, with a processing time of 5-15 minutes, and the temperature of the by-product hydrochloric acid during the process is 40-55℃.

6. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 1, characterized in that: The ceramic membrane in S3 that is resistant to strong acids, high temperatures, and pollution is made of α-alumina or silicon carbide, with a pore size of 0.1-1 μm and a filtration operating pressure of 0.2-0.5 MPa.

7. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 1, characterized in that: The activated carbon in S4 is columnar granular activated carbon with a specific surface area of ​​800-1200 m². 2 / g, adsorption space velocity of 1-3h-1, adsorption column operating temperature of 30-50℃, and pretreated with hydrochloric acid.

8. The multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to claim 7, characterized in that: The hydrochloric acid pretreatment in S4 involves soaking in 10-15% hydrochloric acid for 24 hours followed by drying.

9. A multi-stage separation method for oil from acid byproducts of dimethyldichlorosilane hydrolysis according to any one of claims 1-8, characterized in that: S1-S4 also include joint optimization through CFD fluid simulation and system orthogonal experiments, where the factors in the orthogonal experiments include static settling temperature, high shear speed, demulsifier addition amount, and ceramic membrane filtration pressure.