CN114671418A - Separation method of nitration reaction binary mixed acid - Google Patents
Separation method of nitration reaction binary mixed acid Download PDFInfo
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- 239000002253 acid Substances 0.000 title claims abstract description 110
- 238000000926 separation method Methods 0.000 title claims abstract description 47
- 238000006396 nitration reaction Methods 0.000 title claims abstract description 22
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 131
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 131
- 238000011084 recovery Methods 0.000 claims abstract description 47
- 239000007788 liquid Substances 0.000 claims abstract description 46
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000006722 reduction reaction Methods 0.000 claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 10
- 230000001590 oxidative effect Effects 0.000 claims abstract description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 95
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 90
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 44
- 238000010521 absorption reaction Methods 0.000 claims description 34
- 230000003647 oxidation Effects 0.000 claims description 26
- 238000007254 oxidation reaction Methods 0.000 claims description 26
- 238000005507 spraying Methods 0.000 claims description 15
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 125000004122 cyclic group Chemical group 0.000 claims description 10
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 7
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 claims description 5
- 239000007921 spray Substances 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 4
- 239000007789 gas Substances 0.000 description 34
- 239000000243 solution Substances 0.000 description 22
- 238000000034 method Methods 0.000 description 18
- 239000002699 waste material Substances 0.000 description 12
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 238000005530 etching Methods 0.000 description 5
- 238000004064 recycling Methods 0.000 description 5
- 150000007513 acids Chemical class 0.000 description 4
- 159000000007 calcium salts Chemical class 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- -1 fluoride ions Chemical class 0.000 description 4
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 229910002651 NO3 Inorganic materials 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 239000004317 sodium nitrate Substances 0.000 description 2
- 235000010344 sodium nitrate Nutrition 0.000 description 2
- XWROUVVQGRRRMF-UHFFFAOYSA-N F.O[N+]([O-])=O Chemical compound F.O[N+]([O-])=O XWROUVVQGRRRMF-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-M Nitrite anion Chemical compound [O-]N=O IOVCWXUNBOPUCH-UHFFFAOYSA-M 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000001476 alcoholic effect Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229940104869 fluorosilicate Drugs 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- ZODDGFAZWTZOSI-UHFFFAOYSA-N nitric acid;sulfuric acid Chemical compound O[N+]([O-])=O.OS(O)(=O)=O ZODDGFAZWTZOSI-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
- C01B21/38—Nitric acid
- C01B21/46—Purification; Separation ; Stabilisation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/90—Separation; Purification
- C01B17/94—Recovery from nitration acids
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention provides a separation method of nitration reaction binary mixed acid, which comprises the following steps: (1) mixing an alcohol reducing agent and a binary mixed acid, and carrying out reduction reaction to obtain a reducing gas and a reducing liquid; (2) absorbing the reducing gas obtained in the step (1), and oxidizing to obtain nitric acid recovery liquid. The separation method is suitable for treating the binary mixed acid containing the nitric acid, the nitric acid is reduced into NOx gas by using the alcohol reducing agent, the NOx gas is absorbed and oxidized, the nitric acid in the binary mixed acid is separated, the nitric acid with higher concentration can be obtained, and the recovery rate is higher.
Description
Technical Field
The invention belongs to the technical field of waste liquid recovery, relates to a method for recovering waste acid, and particularly relates to a method for separating nitration binary mixed acid.
Background
Nitric acid is often used in industries such as circuit board etching, and is often mixed into binary mixed acid such as nitric acid, sulfuric acid nitrate, hydrofluoric acid nitrate and the like in order to improve the use effect, and if the waste acid is directly discharged, environmental pollution and waste of valuable components are caused; nitration waste acid is also generated in the process of relating to nitration reaction in other chemical processes; therefore, it is necessary to recycle the waste acid containing nitric acid.
The separation method commonly used in the prior art comprises the steps of discharging mixed acid into a neutralization tank, neutralizing with alkaline liquor and then discharging, so that the mixed acid and the alkaline liquor are greatly wasted, and simultaneously, a large amount of nitrate and sulfate are easily generated to pollute the environment; another common method is to send the mixed acid to a distillation device and adopt a distillation methodThe nitric acid is extracted from the top of a distillation device in a gas phase form, the nitric acid with certain concentration is formed after condensation and cooling, and the evaporation residue is the sulfuric acid with certain concentration, so that the nitric acid and the sulfuric acid are fully utilized, but the method has the following defects: (1) the distillation temperature is high, and nitric acid or sulfuric acid in the mixed acid is easy to decompose to generate NOxWith SO3Etc., causing environmental pollution and resulting in a decrease in the yield of nitric acid and sulfuric acid; (2) the operation temperature is high, the material selection of the separation equipment is difficult, only expensive metal materials can be used, and the investment cost of the device is high; (3) the nitric acid needs to be heated to a temperature higher than the bubble point, and the energy consumption is higher.
CN 110127728A discloses an etching waste liquid mixed acid treatment method, wherein the etching waste acid mixed acid comprises: fluoride, sulfate, fluorosilicate and sulfate ions, the method comprising a first aspect comprising: reacting the etching waste acid mixed acid with lime to make fluoride ions, sulfate ions and fluosilicic acid follow ions to prepare calcium salt, and reacting the nitrate ions with sodium salt to prepare sodium nitrate and removing the sodium nitrate through crystallization; the second method comprises the following steps: and reacting the etching waste acid mixed acid with lime to make fluoride ions, sulfate ions, fluosilicate ions and nitrate ions into calcium salt. Although the method can convert waste acid into calcium salt, different components in the calcium salt are difficult to separate, more lime is consumed, the cost is higher, and the method is not beneficial to industrial treatment.
CN 109824022A discloses a low-temperature separation method of nitric acid mixed acid, wherein the nitric acid mixed acid is fed into the upper part of a stripping tower at the temperature of 40-100 ℃, stripping gas is fed into the lower part of the stripping tower at the temperature of 50-150 ℃, a gas phase containing nitric acid is extracted from the top of the stripping tower, and a separated sulfuric acid product is extracted from the bottom of the stripping tower; and (3) introducing a gas phase containing nitric acid extracted from the top of the stripping tower into the lower part of the washing tower, absorbing the nitric acid in the gas phase introduced into the lower part of the washing tower by using production water extracted from the bottom of the washing tower as a circulating absorbent, delivering the nitric acid as a separated nitric acid product after the concentration of the nitric acid in the production water reaches a control value, and extracting gas phase tail gas from the top of the washing tower. However, the method is not suitable for separating mixed acid with high mass fraction of nitric acid, otherwise, the separation effect of nitric acid and sulfuric acid is difficult to ensure.
CN 113479854a discloses a method for removing nitric acid from mixed acid solution, which comprises the following steps: heating a mixed acid solution, wherein the mixed acid solution is a mixed solution of sulfuric acid and nitric acid; adding urea into the mixed acid solution until no bubbles are generated; and cooling the mixed acid solution, and collecting sulfuric acid. The removal method can efficiently remove the nitric acid in the mixed acid solution, has high removal efficiency, can realize the recycling of the sulfuric acid, and improves the utilization rate of the sulfuric acid. However, if the concentration of nitric acid in the mixed acid is high, a large amount of urea needs to be consumed, the cost is high, and the nitric acid cannot be recycled.
In view of the above, it is desirable to provide a simple separation method capable of efficiently separating acid components in a mixed acid with a high recovery rate of each acid, and particularly to provide a simple, reliable and easy-to-implement separation method for a binary mixed acid.
Disclosure of Invention
The invention aims to provide a separation method of nitration binary mixed acid, which is simple to operate, and can realize the recycling of two acids in the binary mixed acid by reducing nitric acid in the binary mixed acid, and the separation method reduces the cost and risk of waste acid recovery and improves the economic benefit of enterprises.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a separation method of nitration reaction binary mixed acid, which comprises the following steps:
(1) mixing a reducing agent and a binary mixed acid, and carrying out reduction reaction to obtain a reducing gas and a reducing liquid;
(2) absorbing the reducing gas obtained in the step (1), and oxidizing to obtain nitric acid recovery liquid.
The invention uses the reducing agent to reduce the binary mixed acid, so that the nitric acid in the binary mixed acid is reduced into NOx gas, and the NOx gas is absorbed and oxidized and is converted into the nitric acid again, thereby realizing the recycling of the two acids in the binary mixed acid.
Preferably, the reducing agent in step (1) comprises an alcohol reducing agent and/or an aldehyde reducing agent.
The alcohol reducing agent and/or the aldehyde reducing agent are/is used, so that the separation of nitric acid in the binary mixed acid can be realized, the separation of the nitric acid from the reducing solution can be facilitated, and the purity of the residual acid in the reducing solution can be ensured.
Preferably, the alcoholic reducing agent comprises any one of methanol, ethanol or propanol or a combination of at least two thereof, typical but non-limiting combinations include a combination of methanol and ethanol, a combination of ethanol and propanol, a combination of methanol and propanol or a combination of methanol, ethanol and propanol.
Preferably, the aldehyde reducing agent comprises formaldehyde.
Preferably, the reducing agent in step (1) is methanol.
The reduction of nitric acid using methanol as a reducing agent, in the reduction of nitric acid to NOx, oxidizes itself to CO2Gas, thereby facilitating separation from the reducing liquid; moreover, the boiling point of the methanol is only 64.8 ℃, and the energy consumption is low when the methanol is separated from the reducing liquid.
Preferably, the molar ratio of the reducing agent in the step (1) to the nitric acid in the dibasic mixed acid is 1 (1-1.5), and may be, for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, but is not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.
Preferably, the mixed dibasic acid in step (1) includes a mixed dibasic acid composed of nitric acid and sulfuric acid, or a mixed dibasic acid composed of nitric acid and hydrofluoric acid.
Preferably, in the dibasic mixed acid in the step (1), the concentration of the nitric acid is 80-150g/L, such as 80g/L, 90g/L, 100g/L, 110g/L, 120g/L, 130g/L, 140g/L or 150g/L, but not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.
Preferably, the mixed dibasic acid in step (1) is a mixed dibasic acid composed of nitric acid and sulfuric acid, and the concentration of sulfuric acid is 30-45 wt%, such as 30 wt%, 32 wt%, 35 wt%, 36 wt%, 38 wt%, 40 wt%, 42 wt% or 45 wt%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the temperature of the reduction reaction in step (1) is 50 to 90 ℃, for example, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃ or 90 ℃, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the time of the reduction reaction in step (1) is 8-15min, such as 8min, 9min, 10min, 11min, 12min, 13min, 14min or 15min, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Under the condition of the reduction reaction, the nitric acid can be fully reduced into NOx, the generation of nitrite is effectively avoided, and the separation efficiency of binary mixed acid is improved.
Preferably, the absorbing of step (2) comprises cyclic spray absorption.
The method for cyclic spraying absorption is a conventional absorption method in the field, as long as the absorption of the reducing gas can be realized, and the specific parameters of the cyclic spraying absorption are not further limited in the invention.
Preferably, the absorbed absorption liquid of step (2) comprises water.
Preferably, the gauge pressure in the absorption in step (2) is 0.5 to 0.8MPa, for example, 0.5MPa, 0.6MPa, 0.7MPa or 0.8MPa, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.
The invention is beneficial to the absorption of the reducing gas by the absorption liquid by controlling the gauge pressure to be 0.5-0.8Mpa during the absorption.
Preferably, the oxidizing of step (2) comprises ozone oxidation.
Preferably, the ozone oxidation is carried out with a molar ratio of ozone to nitric acid of (0.8-1.2):1, for example 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1, but not limited to the values recited, and other values not recited within the numerical ranges are equally applicable.
When ozone is supplied by ozone oxidation, a certain gauge pressure can be provided for absorption, and when the gauge pressure provided by ozone is insufficient, protective gas is supplemented to a proper gauge pressure. The protective gas comprises nitrogen and/or an inert gas.
Preferably, the absorbing of step (2) is performed simultaneously with the oxidizing.
The absorption and oxidation are carried out simultaneously, namely, ozone is introduced during the circulating spray absorption to realize the ozone oxidation of NOx, so that the circulating spray absorption efficiency is improved, the time required by the circulating spray absorption is reduced, and the separation efficiency of the binary mixed acid is improved.
Preferably, the separation method further comprises the steps of:
(a) concentrating the reducing liquid obtained in the step (1) to obtain concentrated sulfuric acid;
(b) concentrating the nitric acid recovery liquid obtained in the step (2) to obtain concentrated nitric acid;
the step (a) and the step (b) are not in sequence.
The concentration method of the present invention includes, but is not limited to, conventional evaporation concentration in the art, as long as the purpose of concentration can be achieved, and the present invention is not further limited.
As a preferable technical solution of the separation method of the present invention, the separation method comprises the steps of:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 8-15min at 50-90 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 30-45 wt%, and the concentration of the nitric acid is 80-150 g/L; the molar ratio of the formaldehyde to the nitric acid is 1 (1-1.5);
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by using water as an absorption liquid under the condition of gauge pressure of 0.5-0.8Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is (0.8-1.2) to 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid and concentrated nitric acid.
Compared with the prior art, the invention has the following beneficial effects:
(1) the invention uses alcohol reducer to reduce the nitration binary mixed acid, so that the nitric acid in the binary mixed acid is reduced into NOx gas, and the NOx gas is absorbed and oxidized and converted into nitric acid again, thereby realizing the recycling of two acids in the binary mixed acid; the alcohol reducing agent can be used for not only realizing the separation of nitric acid in the binary mixed acid, but also being convenient for being separated from the reducing liquid, and ensuring the purity of the residual acid in the reducing liquid;
(2) the invention uses methanol as a reducing agent to reduce nitric acid, and when the nitric acid is reduced into NOx, the nitric acid is oxidized into CO2Gas, thereby facilitating separation from the reducing liquid; moreover, the boiling point of the methanol is only 64.8 ℃, and the energy consumption is low when the methanol is separated from the reducing liquid;
(3) according to the invention, absorption and oxidation are carried out simultaneously, and ozone is introduced during cyclic spraying absorption to realize ozone oxidation of NOx, so that the cyclic spraying absorption efficiency is improved, the time required by cyclic spraying absorption is reduced, and the separation efficiency of binary mixed acid is improved;
(4) the separation method provided by the invention is particularly suitable for separating the binary mixed acid of sulfuric acid and nitric acid, the recovery rate of the nitric acid is more than or equal to 97%, and the recovery rate of the sulfuric acid is more than or equal to 98%.
Drawings
FIG. 1 is a flow chart of the separation method of nitration binary mixed acid provided by the present invention.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a separation method of nitration binary mixed acid as shown in figure 1, which comprises the following steps:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 12min at 70 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 40 wt%, and the concentration of the nitric acid is 100 g/L; the molar ratio of methanol to nitric acid is 1: 1.2;
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by using water as an absorption liquid under the condition of gauge pressure of 0.6Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is 1: 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid with the concentration of 98 wt% and concentrated nitric acid with the concentration of 97 wt%.
In this example, the recovery rate of nitric acid was 97.8% and the recovery rate of sulfuric acid was 98.5%.
Example 2
The embodiment provides a separation method of nitration binary mixed acid, which comprises the following steps:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 14min at 60 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 35 wt%, and the concentration of the nitric acid is 120 g/L; the molar ratio of methanol to nitric acid is 1: 1.1;
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by using water as an absorption liquid under the condition of gauge pressure of 0.7Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is 1.1: 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid with the concentration of 98 wt% and concentrated nitric acid with the concentration of 97 wt%.
In this example, the recovery rate of nitric acid was 97.6% and the recovery rate of sulfuric acid was 98.2%.
Example 3
The embodiment provides a separation method of nitration binary mixed acid, which comprises the following steps:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 10min at 80 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 42 wt%, and the concentration of the nitric acid is 140 g/L; the molar ratio of methanol to nitric acid is 1: 1.3;
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by using water as an absorption liquid under the condition of gauge pressure of 0.7Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is 0.9: 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid with the concentration of 98 wt% and concentrated nitric acid with the concentration of 97 wt%.
In this example, the recovery rate of nitric acid was 97.2% and the recovery rate of sulfuric acid was 98.3%.
Example 4
The embodiment provides a separation method of nitration binary mixed acid, which comprises the following steps:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 15min at 50 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 30 wt%, and the concentration of the nitric acid is 80 g/L; the molar ratio of methanol to nitric acid is 1: 1;
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by using water as an absorption liquid under the condition of gauge pressure of 0.5Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is 1.2: 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid with the concentration of 98 wt% and concentrated nitric acid with the concentration of 97 wt%.
In this example, the recovery rate of nitric acid was 97.0% and the recovery rate of sulfuric acid was 98.0%.
Example 5
The embodiment provides a separation method of nitration binary mixed acid, which comprises the following steps:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 8min at 90 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 45 wt%, and the concentration of the nitric acid is 150 g/L; the molar ratio of methanol to nitric acid is 1: 1.5;
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by taking water as an absorption liquid under the condition of gauge pressure of 0.8Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is 0.8: 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid with the concentration of 98 wt% and concentrated nitric acid with the concentration of 97 wt%.
In this example, the recovery rate of nitric acid was 97.4% and the recovery rate of sulfuric acid was 98.3%.
Example 6
This example provides a separation method of a nitration reaction dibasic mixed acid, which is the same as example 1 except that methanol in step (1) is replaced by an equimolar amount of ethanol.
In this example, the recovery rate of nitric acid was 97.3% and the recovery rate of sulfuric acid was 98.2%.
Example 7
This example provides a method for separating a nitration reaction dibasic mixed acid, which is the same as example 1 except that methanol in step (1) is replaced with an equimolar amount of n-propanol.
In this example, the recovery rate of nitric acid was 97.1% and the recovery rate of sulfuric acid was 98.1%.
Example 8
This example provides a separation method of nitration reaction binary mixed acid, which is the same as example 1 except that the temperature of the reduction reaction in step (1) is 45 ℃.
In this example, the recovery rate of nitric acid was 96.2% and the recovery rate of sulfuric acid was 98.3%.
Example 9
This example provides a method for separating a dibasic mixed acid in a nitration reaction, which is the same as that in example 1 except that the gauge pressure in step (2) is 0.4 MPa.
In this example, the recovery rate of nitric acid was 96.9% and the recovery rate of sulfuric acid was 98.5%.
Comparative example 1
This comparative example provides a separation process for nitration reaction dibasic mixed acid, which is the same as example 1 except that ozone oxidation is not performed.
In this comparative example, the recovery rate of nitric acid was 94.1% and the recovery rate of sulfuric acid was 98.5%.
In conclusion, the alcohol reducing agent is used for reducing the nitration binary mixed acid, so that nitric acid in the binary mixed acid is reduced into NOx gas, and the NOx gas is absorbed and oxidized and is converted into nitric acid again, thereby realizing the recycling of two acids in the binary mixed acid; the alcohol reducing agent can be used for not only realizing the separation of nitric acid in the binary mixed acid, but also being convenient for being separated from the reducing liquid, and ensuring the purity of the residual acid in the reducing liquid; the invention uses methanol as a reducing agent to reduce nitric acid, and when the nitric acid is reduced into NOx, the nitric acid is oxidized into CO2 gas, thereby being convenient to separate from the reducing liquid; moreover, the boiling point of the methanol is only 64.8 ℃, and the energy consumption is low when the methanol is separated from the reducing liquid; according to the invention, absorption and oxidation are carried out simultaneously, and ozone is introduced during cyclic spraying absorption to realize ozone oxidation of NOx, so that the cyclic spraying absorption efficiency is improved, the time required by cyclic spraying absorption is reduced, and the separation efficiency of binary mixed acid is improved; the separation method provided by the invention is particularly suitable for separating the binary mixed acid of sulfuric acid and nitric acid, the recovery rate of the nitric acid is more than or equal to 97%, and the recovery rate of the nitric acid is more than or equal to 98%.
The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the protection scope and the disclosure of the present invention.
Claims (10)
1. A separation method of nitration reaction binary mixed acid is characterized by comprising the following steps:
(1) mixing a reducing agent and a binary mixed acid, and carrying out reduction reaction to obtain a reducing gas and a reducing liquid;
(2) absorbing the reducing gas obtained in the step (1), and oxidizing to obtain nitric acid recovery liquid.
2. The separation process according to claim 1, wherein the reducing agent of step (1) comprises an alcohol reducing agent and/or an aldehyde reducing agent;
preferably, the alcohol reducing agent comprises any one of methanol, ethanol or propanol or a combination of at least two thereof;
preferably, the aldehyde reducing agent comprises formaldehyde.
3. The separation process of claim 2, wherein the reducing agent of step (1) is methanol;
preferably, the molar ratio of the reducing agent in the step (1) to the nitric acid in the dibasic mixed acid is 1 (1-1.5).
4. The separation method according to any one of claims 1 to 3, wherein the mixed dibasic acid in step (1) comprises a mixed dibasic acid consisting of nitric acid and sulfuric acid, or a mixed dibasic acid consisting of nitric acid and hydrofluoric acid.
5. The separation method according to claim 4, wherein the concentration of nitric acid in the mixed dibasic acid in the step (1) is 80-150 g/L.
6. The separation method according to claim 4 or 5, wherein the mixed dibasic acid in the step (1) is a mixed dibasic acid consisting of nitric acid and sulfuric acid, and the concentration of the sulfuric acid is 30-45 wt%.
7. The separation method according to any one of claims 1 to 6, wherein the temperature of the reduction reaction of step (1) is 50 to 90 ℃;
preferably, the time of the reduction reaction in the step (1) is 8-15 min.
8. The separation process of any one of claims 1 to 7, wherein the absorption of step (2) comprises cyclic spray absorption;
preferably, the absorbed absorption liquid of step (2) comprises water;
preferably, the gauge pressure in the absorption in the step (2) is 0.5-0.8 MPa;
preferably, the oxidizing of step (2) comprises ozone oxidation;
preferably, the molar ratio of ozone to nitric acid used for the ozone oxidation is (0.8-1.2): 1;
preferably, the absorbing of step (2) is performed simultaneously with the oxidizing.
9. The separation method according to any one of claims 1 to 8, further comprising the steps of:
(a) concentrating the reducing liquid obtained in the step (1) to obtain concentrated sulfuric acid;
(b) concentrating the nitric acid recovery liquid obtained in the step (2) to obtain concentrated nitric acid;
the step (a) and the step (b) are not in sequence.
10. The separation method according to any one of claims 1 to 9, characterized in that it comprises the steps of:
(1) mixing methanol and binary mixed acid, and carrying out reduction reaction for 8-15min at 50-90 ℃ to obtain reducing gas and reducing liquid; the binary mixed acid is composed of nitric acid and sulfuric acid, the concentration of the sulfuric acid is 30-45 wt%, and the concentration of the nitric acid is 80-150 g/L; the molar ratio of the formaldehyde to the nitric acid is 1 (1-1.5);
(2) circularly spraying and absorbing the reducing gas obtained in the step (1) by using water as an absorption liquid under the condition of gauge pressure of 0.5-0.8Mpa, and simultaneously introducing ozone for ozone oxidation to obtain a nitric acid recovery liquid; the molar ratio of ozone to nitric acid used for ozone oxidation is (0.8-1.2) to 1;
and (3) respectively concentrating the reducing solution obtained in the step (1) and the nitric acid recovery solution obtained in the step (2) to obtain concentrated sulfuric acid and concentrated nitric acid.
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| US20040265202A1 (en) * | 2003-04-21 | 2004-12-30 | Manufacturing and Technology Conversion, International, Inc. | Process for the treatment of waste streams |
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