CN110734045B - Method for removing siloxane from concentrated sulfuric acid containing siloxane - Google Patents
Method for removing siloxane from concentrated sulfuric acid containing siloxane Download PDFInfo
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- C01B17/00—Sulfur; Compounds thereof
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Abstract
The invention relates to a method for removing siloxane from concentrated sulfuric acid containing siloxane, which comprises the following steps: adding hydrogen peroxide into concentrated sulfuric acid containing siloxane to oxidize the siloxane into white carbon black, and filtering to remove the white carbon black. In the presence of concentrated sulfuric acid, the white carbon black is obtained by oxidizing siloxane by using hydrogen peroxide, so that the method is simple in process and good in effect; the generated white carbon black floats on the surface of concentrated sulfuric acid, and is easy to filter and separate, so that siloxane can be conveniently removed.
Description
Technical Field
The invention relates to a method for removing siloxane from concentrated sulfuric acid containing siloxane.
Background
In the production process of organic silicon chloromethane or methane chloride, concentrated sulfuric acid is needed to be adopted to wash and purify harmful substances in chloromethane gas, dichloromethane gas or trichloromethane gas: dimethyl ether, methanol, water vapor and siloxane, thereby producing a byproduct of dilute sulfuric acid containing organic matters, and the dilute sulfuric acid contains a large amount of organic matters, which brings great difficulty to secondary utilization. The siloxane which is a high molecular organic substance in the dilute sulfuric acid is easy to polymerize and blocks equipment and pipelines.
China is a world production country of methane chloride, organic silicon and glyphosate with the largest capacity, methyl chloride is produced by adopting a methanol hydrogen chloride method in the production process of the methane chloride and the organic silicon, and methyl chloride is a byproduct in the synthesis of dimethyl phosphite serving as a raw material of the glyphosate, so that dilute sulfuric acid containing organic matters is produced as a byproduct in the production process of the methane chloride, the organic silicon and the glyphosate, according to incomplete statistics, 80-90% of dilute sulfuric acid is produced as a byproduct in China, and the problem that the dilute sulfuric acid as a byproduct with high organic matters is difficult to treat is more obvious in 2017 years under the background of continuously enhancing the environmental protection and wholehearting force.
In addition, the silicone-containing hydrochloric acid is also by-produced in the silicone plant, and the main sources are:
1. hydrolyzates of chlorosilane monomers can produce a wide variety of organosilicon polymers, and a large amount of by-product hydrochloric acid is produced during hydrolysis of chlorosilanes, such as: complete hydrolysis of 1 mole of dimethyldichlorosilane can yield 2 moles of hydrogen chloride. The hydrochloric acid, which is a byproduct of the hydrolysis, contains a large amount of silicone-based substances, mainly silanol (linear substances) and cyclosiloxane (cyclic substances), and is hereinafter collectively referred to as "siloxane".
2. The hydrochloric acid which hydrolyzes the monomethylchlorosilane monomer and produces a large amount of hydrogen-containing silicone oil as a byproduct is small in specific gravity difference between the hydrogen-containing silicone oil and the dilute hydrochloric acid, and some hydrogen-containing silicone oils are mutually soluble and extremely difficult to treat.
3. The byproduct hydrochloric acid generated in acid washing in the chlorosilane monomer hydrolysis process and the byproduct acid synthesized by chloromethane contain siloxane.
The threadlike substances in the siloxane in the by-products can be further polymerized to form macromolecules in the reaction device, so that the blockage of an acid conveying pipeline and the blockage of a hydrogen chloride desorption tower are caused, an acid storage container can be formed into a rubber-like siloxane layer, the equipment has to be frequently stopped and disassembled in production, the rubber-like siloxane layer is cleared, the yield of the siloxane is reduced, the starting period is shortened, the labor waste is caused, the siloxane in the hydrogen chloride gas is analyzed, the synthesis quality of the methyl chloride is influenced, the economic benefit of enterprises is directly damaged, and the removal of the siloxane in the by-product hydrochloric acid is a problem to be solved urgently. However, in the diluted hydrochloric acid containing siloxane, because the specific gravity difference between siloxane and diluted hydrochloric acid is small, and some siloxane and diluted hydrochloric acid are mutually soluble, the siloxane and diluted hydrochloric acid are extremely difficult to separate, and great pressure is generated for environmental protection.
Therefore, in each link of organosilicon production, siloxane-containing hydrochloric acid or siloxane-containing sulfuric acid can be produced as a byproduct, and the components are difficult to separate, the impurities are difficult to remove, and the recovery and the utilization are difficult.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for removing siloxane from concentrated sulfuric acid containing siloxane with low cost and good effect, and also provides a method for extracting hydrochloric acid containing siloxane to obtain hydrogen chloride gas.
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of: adding hydrogen peroxide into concentrated sulfuric acid containing siloxane to oxidize the siloxane into white carbon black, and filtering to remove the white carbon black.
Applicants have found that hydrogen peroxide in the presence of concentrated sulfuric acid can oxidize siloxanes to white carbon. And the white carbon black floats on the surface of concentrated sulfuric acid due to light weight, so that the subsequent separation is easy.
The reaction formula is as follows:
preferably, the concentrated sulfuric acid has a mass concentration of 70% or more.
Preferably, the mass concentration of the concentrated sulfuric acid is 70-98%.
Preferably, the mass concentration of the concentrated sulfuric acid is 80-96%.
Preferably, the mass ratio of the content of siloxane to the added amount of hydrogen peroxide in hydrogen peroxide is 1: 3 to 5.
Preferably, the siloxane accounts for 0.01-1.0% of the mass of the concentrated sulfuric acid, and the adding amount of the hydrogen peroxide in the hydrogen peroxide accounts for 0.03-4% of the mass of the concentrated sulfuric acid.
Preferably, the siloxane accounts for 0.05-0.5% of the mass of the concentrated sulfuric acid, and the hydrogen peroxide in the hydrogen peroxide accounts for 0.2-2.0% of the mass of the concentrated sulfuric acid.
Preferably, the concentrated siloxane-containing sulfuric acid is prepared by: and carrying out vacuum concentration on dilute sulfuric acid containing siloxane to obtain concentrated sulfuric acid containing siloxane.
Preferably, the diluted sulfuric acid containing siloxane is prepared by the following method: and (3) extracting dilute hydrochloric acid containing siloxane by adopting concentrated sulfuric acid to separate out hydrogen chloride gas, and transferring the siloxane into sulfuric acid to obtain dilute sulfuric acid containing the siloxane.
Preferably, the dilute siloxane-containing sulfuric acid is phase separated to isolate the majority of the siloxane prior to vacuum concentration. The dilute sulfuric acid obtained here contains only a small amount of residual siloxane.
The concentrated siloxane-containing sulfuric acid employed in the present invention is generally from:
(1) a byproduct in the production of organic silicon, namely concentrated sulfuric acid containing siloxane, if the byproduct is dilute sulfuric acid containing siloxane, the concentrated sulfuric acid needs to be concentrated for use;
(2) a byproduct in the production of organic silicon, namely diluted hydrochloric acid containing siloxane, is extracted and concentrated by concentrated sulfuric acid to obtain concentrated sulfuric acid containing siloxane.
The hydrogen peroxide adopted by the invention can be industrial hydrogen peroxide.
The invention has the beneficial effects that:
1. in the presence of concentrated sulfuric acid, hydrogen peroxide is adopted to oxidize siloxane to obtain white carbon black, the process is simple, and the effect is good;
2. the generated white carbon black floats on the surface of concentrated sulfuric acid, so that the filtration and separation are easy, and siloxane can be conveniently removed;
3. carrying out vacuum concentration on dilute sulfuric acid containing siloxane to obtain concentrated sulfuric acid, thereby facilitating the oxidation of the siloxane;
4. extraction of the siloxane-containing hydrochloric acid transfers the siloxane to sulfuric acid, allowing for easy separation of the siloxane from the sulfuric acid.
Drawings
FIG. 1 is a schematic view of the analytical purification apparatus according to example 11;
FIG. 2 is a schematic view of the structure of an extraction column of the present invention;
FIG. 3 is a schematic view of the dilute sulfuric acid concentration apparatus according to the present invention;
FIG. 4 is a schematic view of the structure of a desorption/purification apparatus according to example 12.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.
Example 1
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) adding 10g of siloxane into 10Kg of 93% concentrated sulfuric acid, adding hydrogen peroxide (containing 35g of hydrogen peroxide), and oxidizing the siloxane into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 2
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) adding 20g of siloxane into 10Kg of 97% concentrated sulfuric acid, adding hydrogen peroxide (containing 80g of hydrogen peroxide), and oxidizing the siloxane into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 3
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) adding 100g of siloxane into 10Kg of 93% concentrated sulfuric acid, adding hydrogen peroxide (containing 400g of hydrogen peroxide), and oxidizing the siloxane into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 4
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) adding 300g of siloxane into 10Kg of 94% concentrated sulfuric acid, adding hydrogen peroxide (containing 1.0Kg of hydrogen peroxide), and oxidizing the siloxane into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 5
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) adding 60g of siloxane into 10Kg of 90% concentrated sulfuric acid, adding hydrogen peroxide (containing 200g of hydrogen peroxide), and oxidizing the siloxane into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 6
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) the raw material adopts 10Kg of concentrated sulfuric acid containing siloxane, which is a byproduct in the production of organic silicon, wherein the mass concentration of the concentrated sulfuric acid is 85 percent, and the concentrated sulfuric acid contains 500g of siloxane. Adding hydrogen peroxide (containing 1800g of hydrogen peroxide) into concentrated sulfuric acid to oxidize siloxane in the concentrated sulfuric acid into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 7
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) the raw material adopts 10Kg of concentrated sulfuric acid containing siloxane, which is a byproduct in the production of organic silicon, wherein the mass concentration of the concentrated sulfuric acid is 85 percent, and the concentrated sulfuric acid contains 15g of siloxane. Adding hydrogen peroxide (containing 50g of hydrogen peroxide) to oxidize siloxane in the hydrogen peroxide into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 8
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) the raw material adopts 10Kg of concentrated sulfuric acid containing siloxane, which is a byproduct of organic silicon production, wherein the mass concentration of the concentrated sulfuric acid is 85 percent, and the concentrated sulfuric acid contains 20g of siloxane. Adding hydrogen peroxide (containing 70g of hydrogen peroxide) to oxidize siloxane in the hydrogen peroxide into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 9
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) the raw material adopts 10Kg of concentrated sulfuric acid containing siloxane, which is a byproduct in the production of organic silicon, wherein the mass concentration of the concentrated sulfuric acid is 90 percent, and the mass concentration of the concentrated sulfuric acid contains 100g of siloxane. Adding hydrogen peroxide (containing 400g of hydrogen peroxide) to oxidize siloxane in the hydrogen peroxide into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 10
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) the raw material adopts 10Kg of concentrated sulfuric acid containing siloxane, which is a byproduct of organic silicon production, wherein the mass concentration of the concentrated sulfuric acid is 91 percent, and the concentrated sulfuric acid contains 300g of siloxane. Adding hydrogen peroxide (containing 1.0Kg of hydrogen peroxide) to oxidize siloxane in the hydrogen peroxide into white carbon black;
(2) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Example 11
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) extracting dilute hydrochloric acid containing siloxane by adopting concentrated sulfuric acid to separate out hydrogen chloride gas, and transferring the siloxane into dilute sulfuric acid;
(2) vacuum concentrating dilute sulfuric acid to obtain concentrated sulfuric acid containing siloxane;
(3) 10Kg of concentrated sulfuric acid containing siloxane in the step (2) is taken, and the mass concentration of the concentrated sulfuric acid is 91 percent, wherein the concentrated sulfuric acid contains 300g of siloxane. Adding hydrogen peroxide (containing 1.0Kg of hydrogen peroxide) to oxidize siloxane in the hydrogen peroxide into white carbon black;
(4) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Referring to fig. 1-2, the step (1) adopts a desorption purification device for extraction, which comprises an extraction tower 1 and a hydrogen chloride condenser 2, wherein the top of the extraction tower 1 is provided with a gas outlet 11, the upper part is provided with a first concentrated sulfuric acid inlet 12, the lower part is provided with a diluted hydrochloric acid inlet 13 containing siloxane, and the bottom is provided with a diluted sulfuric acid outlet 14; a gas outlet 11 at the top of the extraction tower 1 is communicated with a gas inlet of a hydrogen chloride condenser 2, and the hydrogen chloride condenser 2 is also provided with a hydrogen chloride discharge port and a condensed water outlet.
Referring to fig. 2, three layers of fillers 17 are arranged in the extraction tower 1 from top to bottom, a liquid distributor 16 is arranged above each layer of fillers 17, a first concentrated sulfuric acid inlet 12 is arranged at the uppermost layer of liquid distributor, and a siloxane-containing dilute hydrochloric acid inlet 13 is arranged at the lowermost layer of liquid distributor; a second concentrated sulfuric acid inlet 15 is also provided at the liquid distribution layer of the intermediate layer.
Referring to fig. 3, step (2) adopts a dilute sulfuric acid concentration device 4 for concentration, which comprises a first-stage vacuum concentration kettle 41 and a second-stage vacuum concentration kettle 42, wherein the dilute sulfuric acid outlet 14 of the extraction tower 1 is communicated with the liquid inlet of the first-stage vacuum concentration kettle 41, and the liquid outlet of the first-stage vacuum concentration kettle 41 is communicated with the liquid inlet of the second-stage vacuum concentration kettle 42.
The primary vacuum concentration kettle is provided with a primary heater 43 and a primary condenser 45, the primary heater 43 adopts 0.6-1.0 MPa low-pressure saturated steam as a heat source, a gas inlet of the primary condenser 45 is communicated with a gas outlet of the primary vacuum concentration kettle 41, a gas outlet of the primary condenser 45 is communicated with vacuum, and a liquid outlet of the primary condenser 45 is communicated with a condensed water storage tank 6.
The second-stage vacuum concentration kettle 42 is provided with a second-stage heater 44 and a second-stage condenser 46, the second-stage heater 44 adopts 1.0-2.0 MPa medium-pressure saturated steam as a heat source, a gas inlet of the second-stage condenser 46 is communicated with a gas outlet of the second-stage vacuum concentration kettle 42, a gas outlet of the second-stage condenser 46 is communicated with vacuum, and a liquid outlet of the second-stage condenser 46 is communicated with the condensed water storage tank 6.
The step (1) is specifically as follows:
(1.1) inputting dilute hydrochloric acid containing siloxane (the mass concentration of the siloxane is 0.01-5.0%, and the mass concentration of the hydrochloric acid is 3-31%) into an extraction tower 1 through a dilute hydrochloric acid inlet 13 containing siloxane, and inputting concentrated sulfuric acid into the extraction tower 1 through a first concentrated sulfuric acid inlet 12 and a second concentrated sulfuric acid inlet 15 respectively;
(1.2) the dilute hydrochloric acid and the high-concentration sulfuric acid meet in an extraction tower 1, hydrogen chloride is dissociated from water, and the hydrogen chloride containing moisture passes through a hydrogen chloride condenser 2 and then is discharged (can be recycled) through a hydrogen chloride discharge port on the hydrogen chloride condenser 2; siloxane and water are transferred into sulfuric acid together, and dilute sulfuric acid (the mass concentration is usually 35-65%) is obtained from a dilute sulfuric acid outlet 14 at the bottom of the extraction tower 1.
The step (2) is specifically as follows:
the dilute sulfuric acid obtained from the extraction tower 1 enters a dilute sulfuric acid concentration device, and is subjected to vacuum concentration sequentially through a first-stage vacuum concentration kettle 41 and a second-stage vacuum concentration kettle 42 to obtain concentrated sulfuric acid (usually 80-97%) containing siloxane and having a mass concentration of more than 80%. The waste water obtained by the dilute sulfuric acid concentration device enters a condensed water storage tank 6, can be recycled and can also be subjected to centralized treatment and discharge.
The concentrated sulfuric acid obtained in the step (4) can be returned to the extraction tower through the first concentrated sulfuric acid inlet 12 of the extraction tower 1 for recycling. Of course, concentrated sulfuric acid may be used for other purposes as well.
Example 12
A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of:
(1) extracting dilute hydrochloric acid containing siloxane by adopting concentrated sulfuric acid to separate out hydrogen chloride gas, and transferring the siloxane into dilute sulfuric acid;
(1-2) carrying out phase separation on the dilute sulfuric acid containing siloxane to obtain siloxane and dilute sulfuric acid;
(2) vacuum concentrating dilute sulfuric acid to obtain concentrated sulfuric acid containing siloxane;
(3) 10Kg of concentrated siloxane-containing sulfuric acid is taken, wherein the mass concentration of the concentrated sulfuric acid is 91 percent, and the mass concentration of the concentrated sulfuric acid contains 300g of siloxane. Adding hydrogen peroxide (containing 1.0Kg of hydrogen peroxide) to oxidize siloxane in the hydrogen peroxide into white carbon black;
(4) and filtering the concentrated sulfuric acid to remove white carbon black to obtain the concentrated sulfuric acid.
Referring to fig. 2 and 4, the steps (1) and (1-2) adopt a desorption purification device for extraction and separation, and the desorption purification device comprises an extraction tower 1, a hydrogen chloride condenser 2 and a phase separator 3, wherein the top of the extraction tower 1 is provided with a gas outlet 11, the upper part of the extraction tower is provided with a first concentrated sulfuric acid inlet 12, the lower part of the extraction tower is provided with a diluted hydrochloric acid inlet 13 containing siloxane, and the bottom of the extraction tower is provided with a diluted sulfuric acid outlet 14; a dilute sulfuric acid outlet 14 at the bottom of the extraction tower 1 is communicated with a liquid inlet of the phase separator 3, and the phase separator 3 is also provided with a dilute sulfuric acid outlet and a siloxane outlet; a gas outlet 11 at the top of the extraction tower 1 is communicated with a gas inlet of a hydrogen chloride condenser 2, and the hydrogen chloride condenser 2 is also provided with a hydrogen chloride discharge port and a condensed water outlet.
Referring to fig. 2, three layers of fillers 17 are arranged in the extraction tower 1 from top to bottom, a liquid distributor 16 is arranged above each layer of fillers 17, a first concentrated sulfuric acid inlet 12 is arranged at the uppermost layer of liquid distributor, and a siloxane-containing dilute hydrochloric acid inlet 13 is arranged at the lowermost layer of liquid distributor; a second concentrated sulfuric acid inlet 15 is also provided at the liquid distribution layer of the intermediate layer.
The phase separator may be commercially available, such as liquid-liquid phase separator PT600-D from Franken, Germany, or liquid-liquid phase separator from Sulsho, Switzerland.
Referring to fig. 3, in the step (2), a dilute sulfuric acid concentration device 4 is used for concentration, the dilute sulfuric acid concentration device 4 includes a first-stage vacuum concentration kettle 41 and a second-stage vacuum concentration kettle 42, a dilute sulfuric acid outlet of the phase separator 3 is communicated with a liquid inlet of the first-stage vacuum concentration kettle 41, a liquid outlet of the first-stage vacuum concentration kettle 41 is communicated with a liquid inlet of the second-stage vacuum concentration kettle 42, and a liquid outlet of the second-stage vacuum concentration kettle 42 is communicated with the first concentrated sulfuric acid inlet 12 of the extraction tower 1.
The primary vacuum concentration kettle is provided with a primary heater 43 and a primary condenser 45, the primary heater 43 adopts 0.6-1.0 MPa low-pressure saturated steam as a heat source, a gas inlet of the primary condenser 45 is communicated with a gas outlet of the primary vacuum concentration kettle 41, a gas outlet of the primary condenser 45 is communicated with vacuum, and a liquid outlet of the primary condenser 45 is communicated with a condensed water storage tank 6.
The second-stage vacuum concentration kettle 42 is provided with a second-stage heater 44 and a second-stage condenser 46, the second-stage heater 44 adopts 1.0-2.0 MPa medium-pressure saturated steam as a heat source, a gas inlet of the second-stage condenser 46 is communicated with a gas outlet of the second-stage vacuum concentration kettle 42, a gas outlet of the second-stage condenser 46 is communicated with vacuum, and a liquid outlet of the second-stage condenser 46 is communicated with the condensed water storage tank 6.
A dilute sulfuric acid outlet 14 at the bottom of the extraction tower 1 is communicated with a liquid inlet of the phase separator 3 through a second sulfuric acid storage tank 7; a siloxane outlet of the phase separator 3 is communicated with a siloxane storage tank 8; the dilute sulphuric acid outlet of the phase separator 3 is communicated with the liquid inlet of the first-stage vacuum concentration kettle 41 through a third sulphuric acid storage tank 9.
The step (1) is specifically as follows:
1. inputting dilute hydrochloric acid containing siloxane (the mass concentration of the siloxane is 0.01-5%, the mass concentration of the hydrochloric acid is 3-31%) into an extraction tower 1 through a dilute hydrochloric acid inlet 13 containing siloxane, and inputting concentrated sulfuric acid into the extraction tower 1 through a first concentrated sulfuric acid inlet 12 and a second concentrated sulfuric acid inlet 15 respectively;
2. the dilute hydrochloric acid meets high-concentration sulfuric acid (comprising concentrated sulfuric acid input at two positions in the step 1) in an extraction tower 1, hydrogen chloride is dissociated from water and separated out, the hydrogen chloride containing water passes through a hydrogen chloride condenser 2 to be subjected to two-stage condensation, and is finally discharged (can be recycled) through a hydrogen chloride discharge port on the hydrogen chloride condenser 2, and condensed water circularly enters the extraction tower 1 through a second concentrated sulfuric acid inlet 15; siloxane and water are transferred into sulfuric acid together, and dilute sulfuric acid is obtained from a dilute sulfuric acid outlet 14 at the bottom of the extraction tower 1;
the step (1-2) is specifically:
the dilute sulfuric acid enters a phase separator 3, the siloxane is separated from the dilute sulfuric acid, the siloxane enters a siloxane storage tank 8, and the dilute sulfuric acid enters a third sulfuric acid storage tank 9.
The step (2) is specifically as follows:
the dilute sulfuric acid obtained by separation in the phase separator 3 enters a dilute sulfuric acid concentration device, and is subjected to vacuum concentration in a first-stage vacuum concentration kettle 41 and a second-stage vacuum concentration kettle 42 in sequence to obtain concentrated sulfuric acid (usually 80-97%) with the mass concentration of more than 80%. The waste water obtained by the dilute sulfuric acid concentration device enters a condensed water storage tank 6, can be recycled and can also be subjected to centralized treatment and discharge.
The concentrated sulfuric acid obtained in the step (4) can be returned to the extraction tower through the first concentrated sulfuric acid inlet 12 of the extraction tower 1 for recycling. Of course, concentrated sulfuric acid may be used for other purposes as well.
Examples of effects
The white carbon black obtained in examples 1 to 12 was subjected to performance measurement, and the results are shown in the following table:
| example numbering | Specific surface area (m)2/g) |
| Example 1 | 186 |
| Example 2 | 169 |
| Example 3 | 202 |
| Example 4 | 204 |
| Example 5 | 178 |
| Example 6 | 187 |
| Example 7 | 198 |
| Example 8 | 203 |
| Example 9 | 183 |
| Example 10 | 176 |
| Example 11 | 203 |
| Example 12 | 232 |
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising the steps of: adding hydrogen peroxide into concentrated sulfuric acid containing siloxane to oxidize the siloxane into white carbon black, and filtering to remove the white carbon black.
2. The method of claim 1 for removing siloxane from concentrated sulfuric acid containing siloxane, wherein: the mass concentration of the concentrated sulfuric acid is more than 70%.
3. A method of removing siloxane from concentrated sulfuric acid containing siloxane as claimed in claim 2, wherein: the mass concentration of the concentrated sulfuric acid is 70-98%.
4. A method of removing siloxane from concentrated sulfuric acid containing siloxane according to claim 3, wherein: the mass concentration of the concentrated sulfuric acid is 80-96%.
5. The method of claim 1 for removing siloxane from concentrated sulfuric acid containing siloxane, wherein: the mass ratio of the content of siloxane to the addition of hydrogen peroxide in hydrogen peroxide is 1: 3 to 5.
6. The method of removing siloxane from concentrated sulfuric acid containing siloxane according to claim 1 or 5, wherein: the siloxane accounts for 0.01-1.0% of the mass of the concentrated sulfuric acid, and the adding amount of the hydrogen peroxide in the hydrogen peroxide accounts for 0.03-4% of the mass of the concentrated sulfuric acid.
7. The method of claim 6 wherein the removal of siloxane from concentrated siloxane-containing sulfuric acid is performed by: the siloxane accounts for 0.05-0.5% of the mass of the concentrated sulfuric acid, and the addition amount of the hydrogen peroxide in the hydrogen peroxide accounts for 0.2-2.0% of the mass of the concentrated sulfuric acid.
8. The method of claim 1 for removing siloxane from concentrated sulfuric acid containing siloxane, wherein: concentrated sulfuric acid containing siloxane is prepared by the following method: and carrying out vacuum concentration on dilute sulfuric acid containing siloxane to obtain concentrated sulfuric acid containing siloxane.
9. The method of claim 8 wherein the removal of siloxane from concentrated siloxane-containing sulfuric acid is performed by: the diluted sulfuric acid containing siloxane is prepared by the following method: and (3) extracting dilute hydrochloric acid containing siloxane by adopting concentrated sulfuric acid to separate out hydrogen chloride gas, and transferring the siloxane into sulfuric acid to obtain dilute sulfuric acid containing the siloxane.
10. The method of removing siloxane from concentrated sulfuric acid containing siloxane as claimed in claim 9, wherein: before vacuum concentration, the diluted sulfuric acid containing siloxane is phase separated to separate most siloxane.
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