Functionalized ionic liquids for absorbing vocs and methods of making the same

Abstract

The application belongs to the field of chemical industry and environmental protection, and particularly relates to a functionalized ionic liquid capable of absorbing VOC, and simultaneously relates to a preparation method of the ionic liquid. The raw materials used in the ionic liquid are butyl-methyl imidazolium p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate. The functionalized ionic liquid prepared in the application serves as a solvent, an absorbent and a reaction reagent in the system, so that VOC is physically dissolved and absorbed and chemically captured in the gas-liquid exchange of the functionalized ionic liquid, thereby achieving efficient treatment of VOC.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical industry and environmental protection, and particularly relates to a functionalized ionic liquid capable of absorbing VOCs, and simultaneously relates to a preparation method of the ionic liquid. BACKGROUND

[0002] Volatile organic compounds (VOCs) mainly refer to all organic compounds having corresponding volatility at normal temperature. Volatile organic compounds (VOCs) generally refer to organic compounds with small relative molecular mass, high saturated vapor pressure and easy volatilization at normal temperature. Generally, according to the components and chemical structures of volatile organic compounds, they are divided into aldehydes and ketones, aromatic hydrocarbons, halogenated hydrocarbons, aliphatic hydrocarbons, and other oxygen-containing and nitrogen-containing compounds and many other complex compounds. VOC gas is an important precursor of atmospheric pollution, which seriously threatens people's health. Long-term exposure to volatile organic compounds (VOCs) can cause chronic poisoning, damage to the liver and nervous system, and cause general weakness, drowsiness, and skin itching. The reduction and treatment of VOCs are imminent and arduous.

[0003] The treatment methods of VOCs are divided into two categories: one is the recycling method, and the other is the destructive treatment method. The recycling method includes condensation method, adsorption method, absorption method and membrane separation method. This kind of method highlights the recycling of organic volatile substances, but the VOC removal rate is low, and it cannot achieve the ideal effect when used alone. It is generally used as pretreatment of high-concentration organic volatile substances and combined with other methods. The destructive method includes heat storage type thermal combustion method (RTO), heat storage type catalytic combustion method (RCO), biodegradation method, photocatalytic oxidation method and low-temperature plasma method. This kind of method has high VOC removal rate, but has high investment and prominent operation safety problem, and is suitable for low-concentration VOCs treatment.

[0004] CN106237920A discloses a treatment process and system for VOC-containing industrial waste gas, which uses a combination of absorption and incineration to treat VOC-containing industrial waste gas. The absorbent is machine oil, washing oil or organic solvent, and the absorption device uses jet nozzle mixing absorption. Most VOCs are absorbed by gas-liquid mixing absorption, and the VOC-containing industrial waste gas that is not absorbed by the absorbent is incinerated in a incinerator and then discharged. The treatment efficiency is above 99%. However, the absorbent used in this technology still has a certain vapor pressure and will volatilize into the gas phase under certain conditions, causing the absorption of VOCs in the industrial waste gas, and also producing new VOCs into the subsequent incinerator. The incineration process will produce new SO2 or NO2 when treating sulfur-containing, nitrogen-containing and other organic volatile substances, which has certain limitations. CN106994293 discloses a device and process for treating VOC waste gas from oil refineries. This technology uses an absorption tower, a desulfurization tower and a catalytic oxidation unit to treat waste gas. The absorption tower uses low-temperature diesel oil at 5-10℃ as the absorbent, and the absorbed diesel oil is regenerated. This method is not universal and is only suitable for VOC treatment in oil refineries. CN108905577A discloses a VOC waste gas purification treatment method. This method uses two-stage alkaline spray absorption, and the gas absorbed by the alkali is then subjected to a three-stage adsorption process to achieve waste gas purification. However, alkali absorption is only suitable for absorbing acidic VOC gas, and the absorption effect of spray absorption is poor. In addition, the treatment of adsorption waste residue produced in the adsorption process is still a difficult problem. SUMMARY

[0005] Therefore, the present application aims to provide a functionalized ionic liquid for absorbing VOC and a preparation method thereof.

[0006] The technical scheme adopted by the present application is as follows:

[0007] A functionalized ionic liquid for absorbing VOC, wherein the raw materials are sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:1-8:0.1-4.0:0.1-1.

[0008] Further preferably, the molar ratio of sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate is 1:1-4:0.1-2:0.1-1.

[0009] A method for preparing a functionalized ionic liquid, comprising the following steps: dissolving potassium permanganate in deionized water to form a solution with a concentration of 1-5%, then adding lead acetate powder, stirring to dissolve, and then adding 1-butyl-3-methyl imidazole tetrafluoroborate and sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid under stirring, and stirring until uniform.

[0010] The functionalized ionic liquid of the present application is used by loading the functionalized ionic liquid into a circulating tank, pumping the liquid into a liquid inlet of a high gravity absorber by a circulating pump, introducing a gas containing VOCs such as ammonia, hydrogen sulfide, sulfide, mercaptan, etc. into a gas inlet of the high gravity absorber by a fan, and removing the VOCs under the action of a high gravity field in the gas-liquid two-phase microcosmic mixing to achieve standard discharge.

[0011] In the present application, the sulfobutyl-methylimidazolium-p-toluenesulfonic acid has a strong capturing reaction ability for ammonia, and the N at 3-position has a strong capturing reaction ability for hydrogen sulfide, and the captured amino group and hydrogen sulfide can be removed under specific conditions, so that the ionic liquid can be recycled and used.

[0012] 1-butyl-3-methylimidazolium tetrafluoroborate has a strong solubility and high absorption capacity for organic volatile substances, and can fully absorb organic volatile substances such as organic aldehyde, acid, dichloroethane, ethyl acetate, toluene, styrene, etc. The absorption saturation can realize the recovery of the organic volatile substances by evaporation, and the ionic liquid can be recycled and utilized.

[0013] Lead acetate can capture the mercaptan in the odor to form a non-toxic, odorless and hardly soluble yellow precipitate.

[0014]

[0015] Potassium permanganate can oxidize mercaptan and sulfide to odorless and tasteless sulfonic acid and high-boiling sulfoxide under the strong acidic conditions of the sulfobutyl-methylimidazolium-p-toluenesulfonic acid ionic liquid.

[0016] ,

[0017] .

[0018] The sulfobutyl-methylimidazolium-p-toluenesulfonic acid, 1-butyl-3-methylimidazolium tetrafluoroborate, lead acetate and potassium permanganate used in the present application each have absorption characteristics, but more importantly, the mutual interaction between these raw materials is a decisive factor for the high absorption efficiency of the ionic liquid. The specific connection is that the sulfonic acid group of the sulfobutyl-methylimidazolium-p-toluenesulfonic acid can release hydrogen ions, making the system acidic, and making the oxidizing property of potassium permanganate stronger under the system conditions in the presence of the sulfobutyl-methylimidazolium-p-toluenesulfonic acid. The ammonium nitrogen in the sulfobutyl-methylimidazolium-p-toluenesulfonic acid and 1-butyl-3-methylimidazolium tetrafluoroborate can form stable hydrogen bonds with the acetate anion in lead acetate, the BF4 anion and water, promoting the formation of a stable macromolecular complex group of the sulfobutyl-methylimidazolium-p-toluenesulfonic acid, 1-butyl-3-methylimidazolium tetrafluoroborate and acetate, thereby facilitating the absorption of VOCs and SO2, NOx, H2S, etc. in the odor by the ionic liquid. xO combined, the four selected combinations of the present application form synergies, so that the prepared ionic liquid has the combined effect of physical absorption and chemical reaction, and further efficiently absorbs VOC.

[0019] The functionalized ionic liquid prepared in the present application acts as a solvent, an absorbent, and a reaction reagent in the system, so that VOC is physically and chemically captured in the gas-liquid exchange of the functional ionic liquid, thereby achieving efficient treatment of VOC. The ionic liquid after absorption saturation can be easily desorbed by heating, so that the ionic liquid can be recycled. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The equipment connection diagram for VOC gas absorption experiment. DETAILED DESCRIPTION

[0021] The specific embodiments of the present application will be described below in conjunction with examples, but the following examples are only used to illustrate the present application in detail, and do not limit the scope of the present application in any way.

[0022] Example 1: A functionalized ionic liquid for absorbing VOC, the raw materials used are butyl-methyl imidazolium p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:4:2:1.

[0023] Example 2: A functionalized ionic liquid for absorbing VOC, the raw materials used are butyl-methyl imidazolium p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:1:0.1:0.1.

[0024] Example 3: A functionalized ionic liquid for absorbing VOC, the raw materials used are butyl-methyl imidazolium p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:8:4:1.

[0025] Example 4: A functionalized ionic liquid for absorbing VOC, the raw materials used are butyl-methyl imidazolium p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:3:2:1.

[0026] Example 5: A functionalized ionic liquid for absorbing VOC, the raw materials used are butyl-methyl imidazolium p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:6:1:0.5.

[0027] Example 6: A functionalized ionic liquid for absorbing VOCs, using butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid, 1-butyl-3-methylimidazolium tetrafluoroborate, lead acetate and potassium permanganate in a molar ratio of 1:5:2:1.

[0028] For the preparation of the ionic liquid of example 1-6, the following procedure was used: potassium permanganate was dissolved in deionized water to form a solution with a concentration of 1-5%, then lead acetate powder was added, stirred and dissolved, and then 1-butyl-3-methylimidazolium tetrafluoroborate and butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid were added under stirring, and stirred until uniform.

[0029] Example 7:

[0030] A functionalized ionic liquid for absorbing VOCs, using butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid, 1-butyl-3-methylimidazolium tetrafluoroborate and lead acetate in a molar ratio of 1:4:2.

[0031] For the preparation, the following procedure was used: lead acetate was dissolved in deionized water to form a solution with a concentration of 0.1-4%, stirred and dissolved, and then 1-butyl-3-methylimidazolium tetrafluoroborate and butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid were added under stirring, and stirred until uniform.

[0032] Example 8:

[0033] A functionalized ionic liquid for absorbing VOCs, using butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid, 1-butyl-3-methylimidazolium tetrafluoroborate and potassium permanganate in a molar ratio of 1:4:1.

[0034] For the preparation, the following procedure was used: potassium permanganate was dissolved in deionized water to form a solution with a concentration of 1-5%, and then 1-butyl-3-methylimidazolium tetrafluoroborate and butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid were added under stirring, and stirred until uniform.

[0035] Example 9:

[0036] A functionalized ionic liquid for absorbing VOCs, using butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid, lead acetate and potassium permanganate in a molar ratio of 1:2:1.

[0037] For the preparation, the following procedure was used: potassium permanganate was dissolved in deionized water to form a solution with a concentration of 1-5%, then lead acetate powder was added, stirred and dissolved, and then butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid was added under stirring, and stirred until uniform.

[0038] Example 10:

[0039] A kind of functionalized ionic liquid for absorbing VOC, the raw material used is 1-butyl-3-methyl imidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 4:2:1.

[0040] When preparing: potassium permanganate is dissolved in deionized water to form a solution with a concentration of 1-5%, then lead acetate powder is added, stirred and dissolved, and 1-butyl-3-methyl imidazole tetrafluoroborate is continuously added under stirring, and then stirred evenly.

[0041] Example 11

[0042] A kind of functionalized ionic liquid for absorbing VOC, the raw material used is butyl-methyl imidazolium sulfonic acid-p-toluene sulfonic acid, 1-butyl-3-methyl imidazole tetrafluoroborate, and the molar ratio is 1:4.

[0043] Example 12

[0044] A kind of functionalized ionic liquid for absorbing VOC, the raw material used is butyl-methyl imidazolium sulfonic acid-p-toluene sulfonic acid and lead acetate, and the molar ratio is 8:1.

[0045] Example 13

[0046] A kind of functionalized ionic liquid for absorbing VOC, the raw material used is butyl-methyl imidazolium sulfonic acid-p-toluene sulfonic acid and potassium permanganate, and the molar ratio is 8:1.

[0047] Example 14

[0048] A kind of functionalized ionic liquid for absorbing VOC, the raw material used is 1-butyl-3-methyl imidazole tetrafluoroborate and potassium permanganate, and the molar ratio is 8:1.

[0049] The ionic liquids prepared in Examples 1-14 were subjected to VOC gas absorption experiments. The experimental method was as follows: first, simulate VOC gas was prepared, and 14 gas production bottles were filled with liquid mixtures in the ratio of ethanol / acetone / toluene / xylene / ethyl acetate / ethyl sulfide / ethyl mercaptan 3:5:6:4:3:0.5:0.1, respectively. Then, the ionic liquids prepared in Examples 1-14 were filled into another 14 gas washing bottles, which were labeled as experiments 1-14, respectively. The air discharged from the air compressor was introduced into the gas production bottles, and the VOC value (non-methane total hydrocarbon) of the gas at the outlet of the gas production bottles was detected. The VOC value was generally 2500-3000 mg / L, and there was a foul odor of hydrogen sulfide and mercaptan. The gas outlet of the gas production bottle was connected to the gas inlet of the gas washing bottle, and the functional ionic liquid was introduced into the deep part. The VOC values (non-methane total hydrocarbon) at the inlet and outlet of each gas washing bottle were measured, and the values obtained from the 14 experiments are shown in the following table:

[0050]

[0051] From the above data, when no potassium permanganate is added to the raw material, the absorption liquid cannot oxidize the gas, and only the ammonium nitrogen in sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid and 1-butyl-3-methyl imidazole tetrafluoroborate and the acetate anion in lead acetate, BF4 anion pair and water can form stable hydrogen bonds, and the synergistic effect between them is poor, and the VOC removal effect is affected.

[0052] When no lead acetate is added to the raw material, the ammonium nitrogen in sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid and 1-butyl-3-methyl imidazole tetrafluoroborate cannot form stable hydrogen bonds with the acetate anion in lead acetate, BF4 anion pair and water, and the molecular complexing ability is affected, and the VOC removal effect is affected.

[0053] When no 1-butyl-3-methyl imidazole tetrafluoroborate is added to the raw material, although the sulfonic acid group of sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid can release hydrogen ions, making the oxidizing property of potassium permanganate stronger in the system condition where sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid exists, but without the absorption of VOC in 1-butyl-3-methyl imidazole tetrafluoroborate, the prepared ionic liquid has a significant decrease in the combined effect of physical absorption and chemical reaction, and the VOC removal effect is affected.

[0054] When no sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid is added to the raw material, both the oxidizing property of potassium permanganate and the absorption of 1-butyl-3-methyl imidazole tetrafluoroborate to form a stable macromolecular complex are affected, and the VOC removal effect is affected.

[0055] When the raw material only has sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid and 1-butyl-3-methyl imidazole tetrafluoroborate, the absorption liquid only has physical absorption without the combined effect of chemical reaction.

[0056] When the raw material only has sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid and lead acetate, there is absorption of sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid and reaction of lead acetate, and the effects of physical absorption and chemical reaction are both poor.

[0057] When the raw material only has sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid and potassium permanganate, the sulfonic acid group of sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid can release hydrogen ions, making the oxidizing property of potassium permanganate stronger in the system condition where sulfonic acid butyl-methyl imidazolium-p-toluenesulfonic acid exists, and the combined effect of physical absorption and chemical reaction is poor.

[0058] When the raw material only has 1-butyl-3-methyl imidazole tetrafluoroborate and potassium permanganate, there is absorption of 1-butyl-3-methyl imidazole tetrafluoroborate and weak oxidizing ability of potassium permanganate, and the combined effect of physical absorption and chemical reaction is poor.

[0059] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Other modifications or equivalent replacements to the technical solutions of the present application made by those skilled in the art should be covered in the scope of claims of the present application as long as they do not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A functionalized ionic liquid for absorbing VOCs, characterized in that: The raw materials used are butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid, 1-butyl-3-methylimidazole tetrafluoroborate, lead acetate and potassium permanganate, and the molar ratio is 1:1-8:0.1-4.0:0.1-1.

2. The functionalized ionic liquid of claim 1, wherein: The molar ratio of the butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid, 1-butyl-3-methylimidazole tetrafluoroborate, lead acetate and potassium permanganate is 1:1-4:0.1-2:0.1-1.

3. A method of preparing the functionalized ionic liquid of claim 1, characterized in that, The method comprises the following steps: dissolving potassium permanganate in deionized water to form a solution with a concentration of 1-5%, then adding lead acetate powder, stirring to dissolve, and continuously adding 1-butyl-3-methylimidazole tetrafluoroborate and butyl-methylimidazolium sulfonic acid-p-toluenesulfonic acid under stirring, and stirring until uniform.

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