Hydrolysis tail gas treatment process for preparing glyphosate by alkyl ester method

Abstract

The invention discloses a hydrolysis tail gas treatment process for glyphosate prepared by an alkyl ester method, and belongs to the technical field of glyphosate production. A recyclable adsorbent is prepared to remove HCl gas in the glyphosate hydrolysis tail gas, the outer layer of UiO-66-NH2 / Fe3O4-NH2 is coated with ZIF-8, Cl <-> in HCl is adsorbed on Zr, protons of HCl and carboxyl O atoms show intermolecular hydrogen bond interaction, the protons of HCl and the carboxyl O atoms are subjected to reversible physical adsorption, and the hydrogen bond interaction effect is good. The existence of the Fe3O4-NH2 nanoparticles endows the adsorbent with magnetism and enhances the adsorption effect at the same time, the adsorbent can be recycled due to the stable structure of the adsorbent under the acidic condition, the stability of tail gas recovery is improved, and the method has good application prospects in the technical field of glyphosate production.

Description

Technical Field

[0001] The invention belongs to the technical field of glyphosate production, and particularly relates to a hydrolysis tail gas treatment process for preparing glyphosate using an alkyl ester method. Background Art

[0002] The main components of the tail gas from the hydrolysis of glyphosate synthesis liquid by the alkyl ester method are a mixture of water, methylal, methanol, hydrogen chloride and methyl chloride. The recovery process of this tail gas is referred to as solvent recovery in the glyphosate industry.

[0003] The traditional liquid phase recovery route for hydrolysis tail gas recovery involves condensing the glyphosate hydrolysis tail gas, whose main components are water, methylal, methanol, hydrogen chloride, and methyl chloride, through a multi-stage graphite condenser. The non-condensable gas is then sent to a methyl chloride unit for recovery. The water, methylal, methanol, and hydrogen chloride in the tail gas are condensed and liquefied to produce acidic dilute methanol. After neutralization and removal of hydrogen chloride, neutral dilute methanol is obtained. This is a ternary liquid mixture consisting of methylal (A), methanol (B), and water (C). The volatility of A, B, and C decreases in sequence, and the three components are separated using a two-stage tower. Specifically, A and B are separated from the top of the tower in order of their relative volatility. The specific process is as follows: Component A is distilled from the top of the first tower, and the bottom mixture is B+C. B+C enters the second tower for further separation into B (top distillate) and C (bottom residue).

[0004] This method is easy to operate, but it suffers from drawbacks such as a high reliance on graphite condensers, poor intrinsic safety, and high energy consumption. The hydrolysis offgas from this process is an acidic gas containing a large amount of hydrogen chloride, making it highly dependent on graphite condensers. However, graphite condensers are not resistant to temperature fluctuations or pressure. Therefore, the glyphosate gas and liquid produced using this glyphosate process are subject to the risk of internal leakage within the graphite condenser, resulting in high equipment investment and maintenance costs. Condenser leakage allows acidic and organic substances to enter the chilled water and circulating water systems, corroding them and posing a risk of explosion. This results in low intrinsic safety and significant environmental pressure. Condenser leakage also allows chilled water to enter the dilute methanol system, increasing dilute methanol processing capacity and operating costs. Furthermore, this method involves multiple phase transitions of the material through "condensation, vaporization, and recondensation," resulting in high energy consumption and uneconomical operation.

[0005] Patent application publication number CN 103736384 A discloses a process for treating glyphosate hydrolysis tail gas. The process involves adding an alkaline solution to an alkaline scrubber, heating the alkaline solution to above 60°C, then introducing the glyphosate hydrolysis tail gas to the bottom of the scrubber. The glyphosate hydrolysis tail gas and the alkaline solution mix and react to produce a gas at the top of the scrubber. This gas is then introduced into a methylal distillation tower to separate methylal, methyl chloride, and a bottoms-produced liquid. Compared to existing technologies, the alkaline solution in this application effectively absorbs the hydrochloric acid in the glyphosate hydrolysis tail gas, rendering the gas neutral or weakly alkaline. However, the alkaline solution in the scrubber is consumable and produces a new mixed liquid, which is not conducive to subsequent processing. Summary of the Invention

[0006] The object of the present invention is to provide a hydrolysis tail gas treatment process for preparing glyphosate by an alkyl ester process, thereby eliminating the corrosion of HCl on equipment and improving the quality of recovered tail gas.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A process for treating hydrolysis tail gas from glyphosate prepared by an alkyl ester process comprises the following steps:

[0009] (1) mixing an adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 with water to obtain an adsorbent mixed liquid, adding the adsorbent mixed liquid to an adsorption tower, then introducing glyphosate hydrolysis tail gas into the bottom of the adsorption tower, mixing the glyphosate hydrolysis tail gas with the adsorbent mixed liquid, stirring, and obtaining gas at the top of the adsorption tower;

[0010] (2) completely condensing the gas to separate chloromethane; dehydrating the gas, condensing it, and then passing it into a methylal distillation tower for distillation to separate methylal and residual liquid; passing the residual liquid into a methanol distillation tower for distillation to separate methanol;

[0011] (3) The adsorbent is recovered by magnetic separation to separate the adsorbed HCl for recycling.

[0012] Furthermore, the usage ratio of the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 to water is 1-3 g:1 L.

[0013] Furthermore, the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 was prepared by the following steps:

[0014] 1) 2-aminoterephthalic acid, zirconium tetrachloride, N,N-dimethylformamide, glacial acetic acid and deionized water were mixed and dissolved, reacted in an oil bath at 115-120°C for 1-1.5 hours, cooled to room temperature, centrifuged and washed, and vacuum dried at 75-80°C for 22-24 hours to obtain UiO-66-NH2;

[0015] 2) adding Fe3O4 nanoparticles to a 20% ethanol aqueous solution, stirring and mixing, then adding an aminosilane coupling agent dropwise while stirring, shaking for 10 to 12 hours, centrifuging and washing, and vacuum drying to obtain Fe3O4-NH2 nanoparticles;

[0016] 3) UiO-66-NH2 and Fe3O4-NH2 nanoparticles were stirred in a 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4 to 6 h, magnetically separated and washed, and then dispersed in a 0.08 mol / L Zn(NO3)2·6H2O methanol solution with continuous stirring. A 5 mol / L 2-methylimidazole methanol solution was added dropwise. The mixture was reacted at 50 to 60°C for 4 to 6 h, then allowed to stand at room temperature for 2 to 3 h, magnetically separated and fixed, washed, and dried to obtain UiO-66-NH2 / Fe3O4-NH2@ZIF-8.

[0017] Furthermore, the usage ratio of 2-aminoterephthalic acid, zirconium tetrachloride, N,N-dimethylformamide, glacial acetic acid and deionized water is 0.5-1.5 g:0.8-1.2 g:60-70 mL:30-35 mL:5-10 mL.

[0018] Furthermore, the dosage ratio of the Fe3O4 nanoparticles, ethanol aqueous solution and aminosilane coupling agent is 5-6 g: 50-60 mL: 5-8 mL.

[0019] Furthermore, the aminosilane coupling agent is one of 3-aminopropyltriethoxysilane and N-aminoethyl-3-aminopropyltriethoxysilane.

[0020] Furthermore, the usage ratio of the UiO-66-NH2, Fe3O4-NH2 nanoparticles, poly(sodium p-styrenesulfonate) aqueous solution, Zn(NO3)2·6H2O methanol solution, and 2-methylimidazole methanol solution is 1.5-2.5 g:0.15-0.25 g:60-70 mL:30-40 mL:30-40 mL.

[0021] Furthermore, the gas is dehydrated, condensed to 60° C. to 65° C., and then introduced into a methylal distillation tower.

[0022] Beneficial effects of the present invention:

[0023] (1) UiO-66-NH2 used in the present invention, wherein the metal cluster Zr6O4(OH)4(CO2) of UiO-66 12The exposed 30 unsaturated metal sites make it highly stable in acidic environments. The amino modification of UiO-66 improves the adsorption performance of HCl and CO2. - First, it adsorbs on the metal site to form a weak Zr-Cl bond. The protons of HCl and the carboxyl O atoms show intermolecular hydrogen bonding interactions, which is a reversible physical adsorption. Amino functionalization provides an active cationic surface by more easily protonating in aqueous media to adsorb aqueous CO2 as bicarbonate ions. The change in the pore structure of UiO-66 after amination enhances the physical adsorption of CO2.

[0024] (2) The Fe3O4-NH2 nanoparticles used in the present invention not only enhance the adsorption of HCl and aqueous CO2 after amination, but also the aminosilane coupling agent protects Fe3O4 from being decomposed by HCl during the adsorption process, thereby enhancing the recyclability.

[0025] (3) The ZIF-8 used in the present invention is composed of 2-methylimidazole zinc and a zeolite porous structure, has a saturated four-coordinate Zn-N bond, and has a certain adsorption capacity for HCl and CO2. Moreover, due to the high strength of the Zn-N bond of ZIF-8, HCl molecules cannot break it, thereby retaining the original topological structure of ZIF-8 and ensuring the integrity of the adsorbent. Based on the characteristic of UiO-66-NH2 that can cyclically adsorb HCl, magnetic Fe3O4-NH2 nanoparticles are combined with UiO-66-NH2 through electrostatic adsorption, and then ZIF-8 is in situ grown on the outer layer. The synthesized UiO-66-NH2 / Fe3O4-NH2@ZIF-8 solves the problem of adsorbent recovery and the problem of acidic gas corrosiveness to the adsorbent. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a hydrolysis tail gas treatment process for preparing glyphosate by the alkyl ester method, and the specific implementation method is as follows:

[0029] In the first step, 1 g of 2-aminoterephthalic acid, 1 g of zirconium tetrachloride, 60 mL of N,N-dimethylformamide, 30 mL of glacial acetic acid, and 5 mL of deionized water were mixed and dissolved, reacted in an oil bath at 120°C for 1 h, cooled to room temperature, centrifuged and washed, and vacuum dried at 80°C for 22 h to obtain UiO-66-NH2;

[0030] 5 g of Fe3O4 nanoparticles were added to 50 mL of 20% ethanol aqueous solution and stirred to mix. Then, 6 mL of 3-aminopropyltriethoxysilane was added dropwise while stirring. The mixture was then shaken for 10 to 12 hours, washed by centrifugation, and dried in vacuo to obtain Fe3O4-NH2 nanoparticles.

[0031] 2 g of UiO-66-NH2 and 0.2 g of Fe3O4-NH2 nanoparticles were stirred in 60 mL of 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4 to 6 h, magnetically separated and washed, and then dispersed in 30 mL of 0.08 mol / L Zn(NO3)2·6H2O methanol solution. Stirring was continued, and 30 mL of 5 mol / L 2-methylimidazole methanol solution was added dropwise. The mixture was reacted at 50 ° C for 6 h, then allowed to stand at room temperature for 3 h, magnetically separated and fixed, washed and dried to obtain UiO-66-NH2 / Fe3O4-NH2@ZIF-8.

[0032] In the second step, 2 g of the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 was mixed with 1 L of water to obtain an adsorbent mixture. The adsorbent mixture was added to an adsorption tower, and then glyphosate hydrolysis tail gas was introduced into the bottom of the adsorption tower. After the glyphosate hydrolysis tail gas and the adsorbent mixture were mixed and stirred, gas was obtained at the top of the adsorption tower.

[0033] In the third step, the gas is completely condensed to separate methyl chloride; the gas is dehydrated and condensed to 65°C, and then passed into a methylal distillation tower for distillation to separate methylal and residual liquid; the residual liquid is passed into a methanol distillation tower for distillation to separate methanol;

[0034] In the fourth step, the adsorbent is recovered by magnetic separation to separate the adsorbed HCl for recycling.

[0035] Example 2

[0036] Compared with Example 1, this example is different in that “1 g of 2-aminoterephthalic acid” is changed to “0.5 g of 2-aminoterephthalic acid”.

[0037] The remaining raw materials and preparation process remain the same as in Example 1.

[0038] Example 3

[0039] Compared with Example 1, this example is different in that “1 g of 2-aminoterephthalic acid” is changed to “1.5 g of 2-aminoterephthalic acid”.

[0040] The remaining raw materials and preparation process remain the same as in Example 1.

[0041] Example 4

[0042] The difference between this embodiment and embodiment 1 is that “2 g UiO-66-NH2” is changed to “1.5 g UiO-66-NH2”.

[0043] The remaining raw materials and preparation process remain the same as in Example 1.

[0044] Example 5

[0045] The difference between this embodiment and embodiment 1 is that “0.2 g Fe 3 O 4 —NH 2 nanoparticles” is changed to “0.15 g Fe 3 O 4 —NH 2 nanoparticles”.

[0046] The remaining raw materials and preparation process remain the same as in Example 1.

[0047] Example 6

[0048] Compared with Example 1, this example is different in that “3-aminopropyltriethoxysilane” is replaced with “N-aminoethyl-3-aminopropyltriethoxysilane”.

[0049] The remaining raw materials and preparation process remain the same as in Example 1.

[0050] Example 7

[0051] Compared with Example 1, this embodiment differs in that "the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 is added in an amount of 2 g / L" is changed to "the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 is added in an amount of 1 g / L".

[0052] The remaining raw materials and preparation process remain the same as in Example 1.

[0053] Example 8

[0054] Compared with Example 1, this embodiment differs in that "the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 is added in an amount of 2 g / L" is changed to "the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 is added in an amount of 3 g / L".

[0055] The remaining raw materials and preparation process remain the same as in Example 1.

[0056] Comparative Example 1

[0057] This comparative example is different from Example 1 in that the UiO-66 in the first step is not aminated. The specific implementation steps are as follows:

[0058] In the first step, 5 g of Fe3O4 nanoparticles were added to 50 mL of 20% ethanol aqueous solution and stirred to mix. Then, 6 mL of 3-aminopropyltriethoxysilane was added dropwise while stirring. The mixture was then shaken for 10 to 12 hours, centrifuged and washed, and vacuum dried to obtain Fe3O4-NH2 nanoparticles.

[0059] 2g UiO-66 and 0.2g Fe3O4-NH2 nanoparticles were stirred in 60mL of 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4-6h, magnetically separated and washed, and then dispersed in 30mL of 0.08mol / L Zn(NO3)2·6H2O methanol solution. Stirring was continued, and 30mL of 5mol / L 2-methylimidazole methanol solution was added dropwise. The reaction was carried out at 50℃ for 6h and then allowed to stand at room temperature for 3h. The mixture was fixed by magnetic separation, washed and dried to obtain UiO-66 / Fe3O4-NH2@ZIF-8.

[0060] The remaining raw materials and preparation process remain the same as in Example 1.

[0061] Comparative Example 2

[0062] This comparative example is different from Example 1 in that the Fe3O4 in the first step is not subjected to amination. The specific implementation steps are as follows:

[0063] In the first step, 1 g of 2-aminoterephthalic acid, 1 g of zirconium tetrachloride, 60 mL of N,N-dimethylformamide, 30 mL of glacial acetic acid, and 5 mL of deionized water were mixed and dissolved, reacted in an oil bath at 120°C for 1 h, cooled to room temperature, centrifuged and washed, and vacuum dried at 80°C for 22 h to obtain UiO-66-NH2;

[0064] 2 g of UiO-66-NH2 and 0.2 g of Fe3O4 nanoparticles were stirred in 60 mL of 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4 to 6 h, magnetically separated and washed, and then dispersed in 30 mL of 0.08 mol / L Zn(NO3)2·6H2O methanol solution. Stirring was continued, and 30 mL of 5 mol / L 2-methylimidazole methanol solution was added dropwise. The mixture was reacted at 50 ° C for 6 h, then allowed to stand at room temperature for 3 h, magnetically separated and fixed, washed and dried to obtain UiO-66-NH2 / Fe3O4@ZIF-8.

[0065] The remaining raw materials and preparation process remain the same as in Example 1.

[0066] Comparative Example 3

[0067] Compared with Example 1, this comparative example differs in that Fe3O4-NH2 nanoparticles are not added in the first step. The specific implementation steps are as follows:

[0068] In the first step, 1 g of 2-aminoterephthalic acid, 1 g of zirconium tetrachloride, 60 mL of N,N-dimethylformamide, 30 mL of glacial acetic acid, and 5 mL of deionized water were mixed and dissolved, reacted in an oil bath at 120°C for 1 h, cooled to room temperature, centrifuged and washed, and vacuum dried at 80°C for 22 h to obtain UiO-66-NH2;

[0069] 2 g of UiO-66-NH2 was stirred in 60 mL of a 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4 to 6 h, magnetically separated and washed, and then dispersed in 30 mL of a 0.08 mol / L Zn(NO3)2·6H2O methanol solution. Stirring was continued, and 30 mL of a 5 mol / L 2-methylimidazole methanol solution was added dropwise. The mixture was reacted at 50 ° C for 6 h, then allowed to stand at room temperature for 3 h, magnetically separated and fixed, washed and dried to obtain UiO-66-NH2@ZIF-8.

[0070] The remaining raw materials and preparation process remain the same as in Example 1.

[0071] Comparative Example 4

[0072] Compared with Example 1, this comparative example differs in that UiO-66-NH2 is not added in the first step. The specific implementation steps are as follows:

[0073] In the first step, 5 g of Fe3O4 nanoparticles were added to 50 mL of 20% ethanol aqueous solution and stirred to mix. Then, 6 mL of 3-aminopropyltriethoxysilane was added dropwise while stirring. The mixture was then shaken for 10 to 12 hours, centrifuged and washed, and vacuum dried to obtain Fe3O4-NH2 nanoparticles.

[0074] 0.2 g of Fe3O4-NH2 nanoparticles were stirred in 60 mL of 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4 to 6 h, magnetically separated and washed, and then dispersed in 30 mL of 0.08 mol / L Zn(NO3)2·6H2O methanol solution. Stirring was continued, and 30 mL of 5 mol / L 2-methylimidazole methanol solution was added dropwise. The reaction was carried out at 50°C for 6 h, and then allowed to stand at room temperature for 3 h. The particles were fixed by magnetic separation, washed, and dried to obtain Fe3O4-NH2@ZIF-8.

[0075] The remaining raw materials and preparation process remain the same as in Example 1.

[0076] Comparative Example 5

[0077] This comparative example is different from Example 1 in that ZIF-8 coating is not performed in the first step. The specific implementation steps are as follows:

[0078] In the first step, 1 g of 2-aminoterephthalic acid, 1 g of zirconium tetrachloride, 60 mL of N,N-dimethylformamide, 30 mL of glacial acetic acid, and 5 mL of deionized water were mixed and dissolved, reacted in an oil bath at 120°C for 1 h, cooled to room temperature, centrifuged and washed, and vacuum dried at 80°C for 22 h to obtain UiO-66-NH2;

[0079] 5 g of Fe3O4 nanoparticles were added to 50 mL of 20% ethanol aqueous solution and stirred to mix. Then, 6 mL of 3-aminopropyltriethoxysilane was added dropwise while stirring. The mixture was shaken for 10 to 12 hours, washed by centrifugation, and dried in vacuo to obtain Fe3O4-NH2 nanoparticles.

[0080] 2 g of UiO-66-NH2 and 0.2 g of Fe3O4-NH2 nanoparticles were stirred in 60 mL of a 0.3% volume fraction poly(sodium p-styrene sulfonate) aqueous solution for 4 to 6 h, and then magnetically separated and washed to obtain UiO-66-NH2 / Fe3O4-NH2.

[0081] The remaining raw materials and preparation process remain the same as in Example 1.

[0082] The purity of the methylal and methanol separated in Examples 1 to 8 and Comparative Examples 1 to 5 was analyzed by high performance liquid chromatography; the pH of the gas at the top of the adsorption tower was measured; the adsorbent was recycled by a solvent washing method (alternating washing with deionized water and anhydrous ethanol three times), dried, and then added back to the adsorption tower mixed liquid. The adsorption effect of the adsorbent after five cycles was evaluated;

[0083] The results are shown in Table 1:

[0084] Table 1

[0085]

[0086]

[0087] As can be seen from Table 1, compared with Example 1, Examples 2 to 6 only adjust the raw material ratio and reasonable replacement of raw materials within the required range, which has little effect on the final recovery of methylal and methanol and the pH of the gas at the top of the adsorption tower; compared with Example 1, the difference between Examples 7 and 8 lies in the difference in the final adsorption effect caused by the different amount of adsorbent added.

[0088] Compared with Example 1, the adsorption effect of comparative example 1 on acidic gas is greatly reduced after amination is not performed. This is because the lone pair of electrons on the nitrogen atom of the amino group reacts with the H in HCl. +ions form coordination bonds, thereby enhancing the adsorption of HCl; Comparative Example 2 shows a decrease in adsorption effect and a decrease in effect after 5 cycles compared with Example 1. This is because after Fe3O4 is aminated, the added amino group not only improves the adsorption of acidic gases, but also protects Fe3O4 from being decomposed by HCl, further improving the performance of the adsorbent; Comparative Example 3 shows a decrease in adsorption effect after 5 cycles compared with Example 1, because Fe3O4-NH2 nanoparticles themselves have good magnetic effects, and their application in the adsorbent material system enhances the recyclability of the adsorbent; Comparative Example 4 shows a significant decrease in both adsorption effect and circulation effect after not adding UiO-66-NH2 compared with Example 1. This is because UiO-66-NH2, on the one hand, Cl in HCl - First, it is adsorbed on the metal site to form a weak Zr-Cl bond. The protons of HCl and the carboxyl O atoms show intermolecular hydrogen bond interactions, which is a reversible physical adsorption, laying the foundation for the recyclability of the adsorbent. Compared with Example 1, Comparative Example 5 does not undergo ZIF-8 coating, showing a decrease in adsorption effect and a significant decrease in circulation effect. On the one hand, ZIF-8 has a certain adsorption capacity for HCl and due to the high strength of the Zn-N bond of ZIF-8, HCl molecules cannot break it, so that the ZIF-8-coated UiO-66-NH2 / Fe3O4-NH2 has a good stable structure in cyclic adsorption. The binding force between UiO-66-NH2 / Fe3O4-NH2 is not strong, which will cause decomposition of the material during cyclic adsorption, reducing the adsorption effect.

[0089] In summary, the present invention provides a process for treating hydrolysis tail gas from glyphosate prepared by the alkyl ester method, which prepares a recyclable adsorbent, and the adsorption effect of HCl is still good after recycling.

[0090] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0091] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A process for treating hydrolysis tail gas from glyphosate prepared by the alkyl ester method, characterized in that: The steps include: (1) mixing an adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 with water to obtain an adsorbent mixed liquid, adding the adsorbent mixed liquid to an adsorption tower, then introducing glyphosate hydrolysis tail gas into the bottom of the adsorption tower, mixing the glyphosate hydrolysis tail gas with the adsorbent mixed liquid, stirring, and obtaining gas at the top of the adsorption tower; (2) completely condensing the gas to separate chloromethane; dehydrating the gas, condensing it, and then passing it into a methylal distillation tower for distillation to separate methylal and residual liquid; passing the residual liquid into a methanol distillation tower for distillation to separate methanol; (3) The adsorbent is recovered by magnetic separation to separate the adsorbed HCl for recycling.

2. The hydrolysis tail gas treatment process for preparing glyphosate by the alkyl ester method according to claim 1, characterized in that: The usage ratio of the adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 to water is 1-3 g:1 L.

3. The hydrolysis tail gas treatment process for preparing glyphosate by the alkyl ester method according to claim 1, characterized in that: The adsorbent UiO-66-NH2 / Fe3O4-NH2@ZIF-8 was prepared by the following steps: 1) 2-aminoterephthalic acid, zirconium tetrachloride, N,N-dimethylformamide, glacial acetic acid and deionized water were mixed and dissolved, reacted in an oil bath at 115-120°C for 1-1.5 hours, cooled to room temperature, centrifuged and washed, and vacuum dried at 75-80°C for 22-24 hours to obtain UiO-66-NH2; 2) adding Fe3O4 nanoparticles to a 20% ethanol aqueous solution, stirring and mixing, then adding an aminosilane coupling agent dropwise while stirring, shaking for 10 to 12 hours, centrifuging and washing, and vacuum drying to obtain Fe3O4-NH2 nanoparticles; 3) UiO-66-NH2 and Fe3O4-NH2 nanoparticles were stirred in a 0.3% poly(sodium p-styrenesulfonate) aqueous solution for 4 to 6 h, magnetically separated and washed, and then dispersed in a 0.08 mol / L Zn(NO3)2·6H2O methanol solution with continuous stirring. A 5 mol / L 2-methylimidazole methanol solution was added dropwise. The mixture was reacted at 50 to 60°C for 4 to 6 h, then allowed to stand at room temperature for 2 to 3 h, magnetically separated and fixed, washed, and dried to obtain UiO-66-NH2 / Fe3O4-NH2@ZIF-8.

4. The hydrolysis tail gas treatment process for preparing glyphosate by the alkyl ester method according to claim 3, characterized in that: The usage ratio of the 2-aminoterephthalic acid, zirconium tetrachloride, N,N-dimethylformamide, glacial acetic acid and deionized water is 0.5-1.5 g: 0.8-1.2 g: 60-70 mL: 30-35 mL: 5-10 mL.

5. The hydrolysis tail gas treatment process for preparing glyphosate by the alkyl ester method according to claim 3, characterized in that: The dosage ratio of the Fe3O4 nanoparticles, the ethanol aqueous solution and the aminosilane coupling agent is 5-6 g: 50-60 mL: 5-8 mL.

6. The process for treating hydrolysis tail gas from glyphosate prepared by the alkyl ester method according to claim 3, characterized in that: The aminosilane coupling agent is one of 3-aminopropyltriethoxysilane and N-aminoethyl-3-aminopropyltriethoxysilane.

7. The process for treating hydrolysis tail gas from glyphosate prepared by the alkyl ester method according to claim 3, characterized in that: The usage ratio of the UiO-66-NH2, Fe3O4-NH2 nanoparticles, poly (sodium p-styrene sulfonate) aqueous solution, Zn (NO3) 2·6H2O methanol solution, and 2-methylimidazole methanol solution is 1.5-2.5 g: 0.15-0.25 g: 60-70 mL: 30-40 mL: 30-40 mL.

8. The process for treating hydrolysis tail gas from glyphosate prepared by the alkyl ester method according to claim 1, characterized in that: The gas is dehydrated, condensed to 60° C. to 65° C., and then introduced into a methylal distillation tower.

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