Preparation method for improving purity and stability of diesel vehicle tail gas treatment fluid

Abstract

The invention belongs to the technical field of diesel vehicle tail gas treatment, and provides a preparation method for improving the purity and stability of diesel vehicle tail gas treatment fluid. Preparing ultrapure water; preparing a urea solution; purification treatment; carrying out stabilizing treatment; and finely filtering. The industrial urea raw material is pretreated and the ultrapure water is prepared, so that the purity of the raw material is effectively improved, and the influence of impurities on the performance of the urea solution is reduced; activated carbon and ion exchange resin are adopted for purification treatment, impurities and ions in the solution are further removed, by adding a specific stabilizer, the stability of the urea solution is remarkably improved, urea crystallization and decomposition are effectively prevented, high quality and stability of the diesel vehicle tail gas treatment liquid are ensured through fine filtration, and the treatment effect is good. And strict tail gas emission standards and vehicle operation requirements can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of diesel vehicle exhaust treatment, and in particular to a preparation method for improving the purity and stability of diesel vehicle exhaust treatment liquid. Background Art

[0002] As environmental protection requirements become increasingly stringent, diesel vehicle exhaust emission standards continue to improve. Diesel vehicle exhaust treatment fluid (commonly known as automotive urea solution) is a key substance for reducing nitrogen oxide emissions in selective catalytic reduction (SCR) technology, and its quality and performance have an important impact on the exhaust purification effect. However, in the existing preparation process, diesel vehicle exhaust treatment fluid often has problems such as low purity and poor stability of urea solution, which can easily lead to urea crystallization and block the injection system, affecting the exhaust treatment effect and the normal operation of the vehicle. Summary of the invention

[0003] The purpose of the present invention is to provide a preparation method for improving the purity and stability of diesel vehicle exhaust treatment fluid to overcome the defects of the prior art.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a preparation method for improving the purity and stability of diesel vehicle exhaust treatment liquid, which is characterized by comprising the following steps:

[0006] (1) Raw material pretreatment: The industrial urea raw material is subjected to coarse filtration, fine filtration and ultrafiltration in sequence to obtain high-purity urea;

[0007] (2) Preparation of ultrapure water: Ultrapure water is obtained by passing water through a combined system of reverse osmosis membrane and ion exchange resin;

[0008] (3) Preparation of urea solution: high-purity urea and ultrapure water are mixed and stirred to obtain a urea solution;

[0009] (4) Purification treatment: urea solution, activated carbon and ion exchange resin are mixed and stirred for purification to obtain a urea mixed solution;

[0010] (5) Stabilization treatment: mixing and stirring the urea mixed solution and the stabilizer for stabilization treatment to obtain a urea stabilized solution;

[0011] (6) Fine filtration: The urea stabilized liquid is finely filtered to obtain the diesel vehicle exhaust treatment liquid.

[0012] Preferably, the purity of the high-purity urea in step (1) is ≥99.90%.

[0013] Preferably, the pressure of the reverse osmosis membrane in step (2) is 0.8-1.2 MPa.

[0014] Preferably, the conductivity of the ultrapure water in step (2) is ≤0.1 μs / cm.

[0015] Preferably, in step (3), the mass ratio of high-purity urea to ultrapure water is 28-35:65-75.

[0016] Preferably, the stirring time in step (3) is 0.5 to 2 hours;

[0017] The stirring rate in step (3) is 100-200 rpm.

[0018] Preferably, the mass of the activated carbon in step (4) is 1 to 3% of the mass of the urea solution, and the amount of the ion exchange resin in step (4) is 0.5 to 1.5% of the mass of the urea solution;

[0019] The stirring temperature in step (4) is 20 to 30° C.

[0020] The stirring time in step (4) is 1 to 2 hours.

[0021] Preferably, the stabilizer in step (5) comprises melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate;

[0022] The mass of the stabilizer is 0.1-0.3% of the mass of the urea solution;

[0023] The mass ratio of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate is 1:1:1.

[0024] Preferably, the stirring time in step (5) is 0.4 to 0.8 h, and the stirring rate in step (5) is 50 to 100 rpm.

[0025] Preferably, the pore size of the filter membrane used for fine filtration in step (6) is 0.01 to 0.1 μm.

[0026] Beneficial effects:

[0027] (1) The present invention effectively improves the purity of industrial urea raw materials and reduces the impact of impurities on the performance of urea solution by pretreating industrial urea raw materials and preparing ultrapure water.

[0028] (2) The present invention uses activated carbon and ion exchange resin for purification, which further removes impurities and ions in the solution and improves the purity of the urea solution.

[0029] (3) The present invention significantly improves the stability of the urea solution by adding a specific stabilizer, effectively prevents urea crystallization and decomposition, and prolongs the storage and use period of the urea solution.

[0030] (4) The present invention ensures the high quality and stability of the diesel vehicle exhaust treatment fluid through fine filtration, and can meet strict exhaust emission standards and vehicle operation requirements. DETAILED DESCRIPTION

[0031] The present invention provides a preparation method for improving the purity and stability of diesel vehicle exhaust treatment liquid, which is characterized by comprising the following steps:

[0032] (1) Raw material pretreatment: The industrial urea raw material is subjected to coarse filtration, fine filtration and ultrafiltration in sequence to obtain high-purity urea;

[0033] (2) Preparation of ultrapure water: Ultrapure water is obtained by passing water through a combined system of reverse osmosis membrane and ion exchange resin;

[0034] (3) Preparation of urea solution: high-purity urea and ultrapure water are mixed and stirred to obtain a urea solution;

[0035] (4) Purification treatment: urea solution, activated carbon and ion exchange resin are mixed and stirred for purification to obtain a urea mixed solution;

[0036] (5) Stabilization treatment: mixing and stirring the urea mixed solution and the stabilizer for stabilization treatment to obtain a urea stabilized solution;

[0037] (6) Fine filtration: The urea stabilized liquid is finely filtered to obtain the diesel vehicle exhaust treatment liquid.

[0038] In the present invention, the pore size of the filter membrane used for coarse filtration in step (1) is preferably 60 to 120 μm, more preferably 70 to 110 μm, and even more preferably 80 to 100 μm.

[0039] In the present invention, the pore size of the filter membrane used for fine filtration in step (1) is preferably 3 to 12 μm, more preferably 4 to 11 μm, and even more preferably 5 to 10 μm.

[0040] In the present invention, the pore size of the ultrafiltration membrane in step (1) is preferably 0.3 to 1.2 μm, more preferably 0.4 to 1.1 μm, and even more preferably 0.5 to 1 μm.

[0041] In the present invention, the purity of the high-purity urea in step (1) is preferably ≥99.90%, more preferably ≥99.91%, and even more preferably ≥99.92%.

[0042] In the present invention, the pressure of the reverse osmosis membrane in step (2) is preferably 0.8 to 1.2 MPa, more preferably 0.85 to 1.15 MPa, and even more preferably 0.9 to 1.1 MPa.

[0043] In the present invention, the conductivity of the ultrapure water in step (2) is preferably ≤0.1 μs / cm, more preferably ≤0.09 μs / cm, and more preferably ≤0.08 μs / cm.

[0044] In the present invention, the mass ratio of high-purity urea to ultrapure water in step (3) is preferably 28-35:65-75, more preferably 29-34:66-74, and more preferably 30-33:67-73.

[0045] In the present invention, the stirring time in step (3) is preferably 0.5 to 2 h, more preferably 0.7 to 1.8 h, and more preferably 1.0 to 1.5 h.

[0046] In the present invention, the stirring rate in step (3) is preferably 100 to 200 rpm, more preferably 120 to 180 rpm, and even more preferably 140 to 160 rpm.

[0047] In the present invention, the mass of the activated carbon in step (4) is preferably 1-3% of the mass of the urea solution, more preferably 1.2-2.8% of the mass of the urea solution, and even more preferably 1.5-2.5% of the mass of the urea solution.

[0048] In the present invention, the amount of ion exchange resin used in step (4) is preferably 0.5-1.5% of the mass of the urea solution, more preferably 0.7-1.3% of the mass of the urea solution, and more preferably 0.8-1.2% of the mass of the urea solution.

[0049] In the present invention, the stirring temperature in step (4) is preferably 20 to 30°C, more preferably 22 to 28°C, and even more preferably 24 to 26°C.

[0050] In the present invention, the stirring time in step (4) is preferably 1 to 2 h, more preferably 1.1 to 1.9 h, and more preferably 1.2 to 1.8 h.

[0051] In the present invention, the stabilizer in step (5) includes melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate.

[0052] In the present invention, the mass of the stabilizer is preferably 0.1-0.3% of the mass of the urea solution, more preferably 0.12-0.28% of the mass of the urea solution, and more preferably 0.15-0.25% of the mass of the urea solution.

[0053] In the present invention, the mass ratio of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate is preferably 1:1:1.

[0054] In the present invention, the stirring time in step (5) is preferably 0.4 to 0.8 h, more preferably 0.45 to 0.75 h, and more preferably 0.5 to 0.7 h.

[0055] In the present invention, the stirring rate in step (5) is preferably 50 to 100 rpm, more preferably 60 to 90 rpm, and more preferably 70 to 80 rpm.

[0056] In the present invention, the pore size of the filter membrane used for fine filtration in step (6) is preferably 0.01 to 0.1 μm, more preferably 0.02 to 0.09 μm, and even more preferably 0.03 to 0.08 μm.

[0057] In the present invention, the prepared diesel vehicle exhaust treatment liquid needs to be placed in a sealed container and stored in a cool, dry and well-ventilated environment.

[0058] In the present invention, the storage temperature is preferably 15 to 25°C, more preferably 16 to 24°C, and even more preferably 18 to 22°C.

[0059] In the present invention, the relative humidity of the storage is preferably 30-60%, more preferably 35-55%, and even more preferably 40-50%.

[0060] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0061] Example 1

[0062] (1) Raw material pretreatment: industrial urea raw material with a purity of 99.5% is selected and filtered through a three-stage filtration device, followed by coarse filtration with a pore size of 100 μm, fine filtration with a pore size of 10 μm, and ultrafiltration with a pore size of 1 μm, to obtain high-purity urea with a purity of 99.95%;

[0063] (2) Preparation of ultrapure water: water is passed through a combined system of a reverse osmosis membrane and an ion exchange resin, the operating pressure of the reverse osmosis membrane is controlled to be 0.9 MPa, and ultrapure water with a conductivity of 0.08 μs / cm is obtained;

[0064] (3) Preparation of urea solution: High-purity urea and ultrapure water were mixed in a mass ratio of 32.5:67.5, and stirred at a rate of 150 rpm for 1 h to fully dissolve the urea to obtain a urea solution;

[0065] (4) Purification treatment: adding 2% of activated carbon by mass of the urea solution and 1% of ion exchange resin by mass of the urea solution to the urea solution, stirring at 25° C. for 1.5 h for purification treatment, and obtaining a urea mixed solution;

[0066] (5) Stabilization treatment: The urea mixed solution was mixed with a stabilizer at 0.2% of the mass of the urea solution, and stirred at a stirring rate of 80 rpm for 0.5 h for stabilization treatment (wherein the stabilizer was a mixture of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate, and the mass ratio of the three was 1:1:1) to obtain a urea stabilized solution;

[0067] (6) Fine filtration: The urea stabilized liquid is finely filtered through a microporous filter membrane with a pore size of 0.01 μm to obtain the diesel vehicle exhaust treatment liquid.

[0068] (7) Filling and storage

[0069] The diesel vehicle exhaust treatment liquid is filled into sealed plastic barrels and stored in a warehouse with a temperature of 20°C and a relative humidity of 50%.

[0070] The diesel vehicle exhaust treatment liquid prepared in this example was tested, and the results of various index parameters are shown in Table 1.

[0071] Table 1 Test results of diesel vehicle exhaust treatment fluid

[0072]

[0073]

[0074] It can be seen from the data in Table 1 that the diesel vehicle exhaust treatment liquid prepared in this embodiment has high purity and all indicators meet national standards. After 18 months of storage, the urea solution remains stable without crystallization and decomposition.

[0075] Example 2

[0076] (1) Raw material pretreatment: industrial urea raw material with a purity of 99.7% is selected and filtered through a three-stage filtration device, followed by coarse filtration with a pore size of 80 μm, fine filtration with a pore size of 5 μm, and ultrafiltration with a pore size of 0.5 μm, to obtain high-purity urea with a purity of 99.98%;

[0077] (2) Preparation of ultrapure water: water is passed through a combined system of a reverse osmosis membrane and an ion exchange resin, the operating pressure of the reverse osmosis membrane is controlled to be 1.0 MPa, and ultrapure water with a conductivity of 0.05 μs / cm is obtained;

[0078] (3) Preparation of urea solution: High-purity urea and ultrapure water were mixed in a mass ratio of 32.5:67.5, and stirred at a rate of 180 rpm for 0.8 h to fully dissolve the urea to obtain a urea solution;

[0079] (4) Purification treatment: adding activated carbon in an amount of 1.5% by mass of the urea solution and ion exchange resin in an amount of 0.8% by mass of the urea solution to the urea solution, mixing, stirring at 28° C. for 1 h for purification treatment, and obtaining a urea mixed solution;

[0080] (5) Stabilization treatment: The urea mixed solution was mixed with a stabilizer in an amount of 0.15% by mass of the urea solution, and stirred at a stirring rate of 60 rpm for 0.6 h for stabilization treatment (wherein the stabilizer was a mixture of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate, and the mass ratio of the three was 1:1:1) to obtain a urea stabilized solution;

[0081] (6) Fine filtration: The urea stabilized liquid is finely filtered through a microporous filter membrane with a pore size of 0.01 μm to obtain the diesel vehicle exhaust treatment liquid.

[0082] (7) Filling and storage

[0083] The diesel vehicle exhaust treatment liquid is filled into sealed plastic barrels and stored in a warehouse with a temperature of 15°C and a relative humidity of 40%.

[0084] After testing, the diesel vehicle exhaust treatment liquid prepared in this embodiment has high purity, and all indicators meet national standards. After 24 months of storage, the urea solution remains stable without crystallization and decomposition.

[0085] Example 3

[0086] (1) Raw material pretreatment: industrial urea raw material with a purity of 99.2% is selected and filtered through a three-stage filtration device, followed by coarse filtration with a pore size of 60 μm, fine filtration with a pore size of 3 μm, and ultrafiltration with a pore size of 0.3 μm, to obtain high-purity urea with a purity of 99.91%;

[0087] (2) Preparation of ultrapure water: water is passed through a combined system of a reverse osmosis membrane and an ion exchange resin, the operating pressure of the reverse osmosis membrane is controlled at 0.8 MPa, and ultrapure water with a conductivity of 0.08 μs / cm is obtained;

[0088] (3) Preparation of urea solution: High-purity urea and ultrapure water were mixed in a mass ratio of 28:65, and stirred at a rate of 100 rpm for 0.5 h to fully dissolve the urea to obtain a urea solution;

[0089] (4) Purification treatment: adding 3% of activated carbon by mass of the urea solution and 0.5% of ion exchange resin by mass of the urea solution to the urea solution, stirring at 20° C. for 1 h for purification treatment to obtain a urea mixed solution;

[0090] (5) Stabilization treatment: The urea mixed solution was mixed with a stabilizer at 0.1% of the mass of the urea solution, and stirred at a stirring rate of 50 rpm for 0.4 h for stabilization treatment (wherein the stabilizer was a mixture of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate, and the mass ratio of the three was 1:1:1) to obtain a urea stabilized solution;

[0091] (6) Fine filtration: The urea stabilized liquid is finely filtered through a microporous filter membrane with a pore size of 0.01 μm to obtain the diesel vehicle exhaust treatment liquid.

[0092] (7) Filling and storage

[0093] The diesel vehicle exhaust treatment liquid is filled into sealed plastic barrels and stored in a warehouse with a temperature of 15°C and a relative humidity of 30%.

[0094] After testing, the diesel vehicle exhaust treatment liquid prepared in this embodiment has high purity, and all indicators meet national standards. After 18 months of storage, the urea solution remains stable without crystallization and decomposition.

[0095] Example 4

[0096] (1) Raw material pretreatment: industrial urea raw material with a purity of 99.5% is selected and filtered through a three-stage filtration device, followed by coarse filtration with a pore size of 120 μm, fine filtration with a pore size of 12 μm, and ultrafiltration with a pore size of 1.2 μm, to obtain high-purity urea with a purity of 99.98%;

[0097] (2) Preparation of ultrapure water: water is passed through a combined system of reverse osmosis membrane and ion exchange resin, the operating pressure of the reverse osmosis membrane is controlled at 1.2 MPa, and ultrapure water with a conductivity of 0.05 μs / cm is obtained;

[0098] (3) Preparation of urea solution: High-purity urea and ultrapure water were mixed in a mass ratio of 35:75, and stirred at a rate of 200 rpm for 2 h to fully dissolve the urea to obtain a urea solution;

[0099] (4) Purification treatment: adding 3% of activated carbon by mass of the urea solution and 1.5% of ion exchange resin by mass of the urea solution to the urea solution, stirring at 30° C. for 2 h for purification treatment, and obtaining a urea mixed solution;

[0100] (5) Stabilization treatment: The urea mixed solution was mixed with a stabilizer at a mass ratio of 0.3% of the mass of the urea solution, and the mixture was stirred at a stirring rate of 100 rpm for 0.8 h for stabilization treatment (wherein the stabilizer was a mixture of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate, and the mass ratio of the three was 1:1:1) to obtain a urea stabilized solution;

[0101] (6) Fine filtration: The urea stabilized liquid is finely filtered through a microporous filter membrane with a pore size of 0.08 μm to obtain the diesel vehicle exhaust treatment liquid.

[0102] (7) Filling and storage

[0103] The diesel vehicle exhaust treatment fluid is filled into sealed plastic barrels and stored in a warehouse at a temperature of 25°C and a relative humidity of 60%.

[0104] After testing, the diesel vehicle exhaust treatment liquid prepared in this embodiment has high purity, and all indicators meet national standards. After 24 months of storage, the urea solution remains stable without crystallization and decomposition.

[0105] It can be seen from the above embodiments that the present invention provides a preparation method for improving the purity and stability of diesel vehicle exhaust treatment liquid. The present invention effectively improves the purity of the raw materials and reduces the influence of impurities on the performance of the urea solution by pretreating the industrial urea raw materials and preparing ultrapure water; activated carbon and ion exchange resin are used for purification to further remove impurities and ions in the solution, thereby improving the purity of the urea solution; the present invention significantly improves the stability of the urea solution by adding a specific stabilizer, effectively prevents urea crystallization and decomposition, and extends the storage and service life of the urea solution; the present invention ensures the high quality and stability of the diesel vehicle exhaust treatment liquid through fine filtration, and can meet strict exhaust emission standards and vehicle operation requirements.

Claims

1. A method for improving the purity and stability of diesel vehicle exhaust treatment fluid, characterized in that: The following steps are involved: (1) Raw material pretreatment: The industrial urea raw material is subjected to coarse filtration, fine filtration and ultrafiltration in sequence to obtain high-purity urea; (2) Preparation of ultrapure water: Ultrapure water is obtained by passing water through a combined system of reverse osmosis membrane and ion exchange resin; (3) Preparation of urea solution: high-purity urea and ultrapure water are mixed and stirred to obtain a urea solution; (4) Purification treatment: urea solution, activated carbon and ion exchange resin are mixed and stirred for purification to obtain a urea mixed solution; (5) Stabilization treatment: mixing and stirring the urea mixed solution and the stabilizer for stabilization treatment to obtain a urea stabilized solution; (6) Fine filtration: The urea stabilized liquid is finely filtered to obtain the diesel vehicle exhaust treatment liquid.

2. The preparation method according to claim 1, characterized in that: The purity of the high-purity urea in step (1) is ≥99.90%.

3. The preparation method according to claim 1, characterized in that: The pressure of the reverse osmosis membrane in step (2) is 0.8-1.2 MPa.

4. The preparation method according to claim 1, characterized in that: The conductivity of the ultrapure water in step (2) is ≤0.1 μs / cm.

5. The preparation method according to claim 1, characterized in that: In the step (3), the mass ratio of high-purity urea to ultrapure water is 28-35:65-75.

6. The preparation method according to claim 1, characterized in that: The stirring time in step (3) is 0.5 to 2 hours; The stirring rate in step (3) is 100-200 rpm.

7. The preparation method according to claim 1, characterized in that: The mass of the activated carbon in step (4) is 1-3% of the mass of the urea solution, and the amount of the ion exchange resin in step (4) is 0.5-1.5% of the mass of the urea solution; The stirring temperature in step (4) is 20 to 30° C. The stirring time in step (4) is 1 to 2 hours.

8. The preparation method according to claim 1, characterized in that: In step (5), the stabilizer comprises melamine, diammonium phosphate and disodium ethylenediaminetetraacetate; The mass of the stabilizer is 0.1-0.3% of the mass of the urea solution; The mass ratio of melamine, diammonium hydrogen phosphate and disodium ethylenediaminetetraacetate is 1:1:

1.

9. The preparation method according to claim 1, characterized in that: The stirring time in step (5) is 0.4 to 0.8 h, and the stirring rate in step (5) is 50 to 100 rpm.

10. The preparation method according to claim 1, characterized in that: The pore size of the filter membrane used for fine filtration in step (6) is 0.01 to 0.1 μm.

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