Adsorbent material and use thereof

Abstract

The application provides an adsorbing material and application thereof. The adsorbing material comprises an ionic liquid [P 66614 ][3-F-4-CN-PhO]. In application, CO2 / HCN mixed gas is introduced into the adsorbing material to adsorb CO2, and after saturation, the adsorbing material can be desorbed and reused. The pKa of the ionic liquid in the adsorbing temperature range is between HCN and H2CO3, so the ionic liquid has high selective absorption capacity for CO2. The adsorbing material has good thermal stability, is not easy to volatilize, has low toxicity, can realize CO2 desorption through heating, has no quality loss after multiple cycles, and has no obvious decrease in adsorption effect. Through the use of the adsorbing material in the separation and purification of hydrocyanic acid gas, hydrocyanic acid with a concentration of more than 99.8% can be prepared, the purification efficiency of hydrocyanic acid can be significantly improved, and the energy consumption can be greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of gas separation, and particularly relates to an adsorption material and application thereof. BACKGROUND

[0002] Hydrocyanic acid is a basic chemical raw material with wide application, and downstream products such as adiponitrile, methionine, sodium cyanide, insecticide and herbicide have a large demand. Taking the downstream product adiponitrile as an example, an adiponitrile device with an annual output of 300,000 tons needs to consume hundreds of thousands of tons of hydrocyanic acid every year. In recent years, with the breakthrough of the domestication of adiponitrile technology, the demand for adiponitrile is more than one million tons, so the demand for hydrocyanic acid will also increase accordingly. Although hydrocyanic acid has a wide range of applications and a huge demand, due to its characteristics as a highly toxic medium, there are fewer domestic and foreign enterprises that master the safe production technology, thus limiting the large-scale development of hydrocyanic acid products.

[0003] The production method of hydrocyanic acid mainly includes the Andrussow method. The reaction mixed gas obtained by producing hydrocyanic acid needs to be treated through three steps of ammonia removal, absorption and rectification to obtain high-purity liquid hydrocyanic acid. However, in the above hydrocyanic acid purification process, especially in summer, due to the high temperature, the refined hydrocyanic acid contains a small amount of by-product carbon dioxide, and the presence of carbon dioxide will limit the application range of hydrogen cyanide. A high-efficiency and safe carbon dioxide removal process is needed before the absorption of liquid-phase hydrocyanic acid. Both of the two gases are acidic gases, and the use of conventional carbon dioxide removal methods will cause a large loss of HCN. Therefore, how to separate the hydrogen cyanide gas and obtain high-concentration hydrocyanic acid liquid under low energy consumption is a difficult problem to be solved in the industry at present. There is no report on the method for removing CO2 from CO2 / HCN mixed gas at home and abroad. SUMMARY

[0004] Based on the above technical problems, the present application provides an adsorption material and its application in removing CO2 from CO2 / HCN mixed gas. According to the difference in pKa value of HCN and CO2, an adsorption material with high selectivity for CO2 in CO2 / HCN mixed gas is screened out as an absorbent through experiments. The absorbent has good thermal stability, low toxicity, and can efficiently and selectively remove CO2 with extremely low concentration, with little loss of HCN. Moreover, the adsorption material can realize CO2 desorption through heating, so as to realize the recycling of the absorbent. The above hydrocyanic acid gas separation and purification method can prepare hydrocyanic acid with a concentration of more than 99.8%, significantly improve the purification efficiency of hydrocyanic acid, and greatly reduce the energy consumption.

[0005] The specific scheme of the present application is as follows:

[0006] The present application provides an adsorption material, which comprises an ionic liquid [P 66614][3-F-4-CN-PhO].

[0007] The preparation method of the ionic liquid is not particularly limited, and can be prepared by a conventional method, such as one-step synthesis. Specifically, but not limited to:

[0008] The ionic liquid is prepared by reacting a tetradecyl trihexyl phosphonium chloride aqueous solution and a 3-fluoro-4-cyanophenol aqueous solution at a water bath temperature of 20-30℃ for 24-48h. After the reaction is completed, the mixture is subjected to rotary evaporation to remove residual deionized water, and then vacuum drying is performed to obtain the ionic liquid.

[0009] The anion of the ionic liquid is selected from a basic adjustable phenolic ion. The position, type and number of the substituents on the phenol change the charge on the oxygen atom in the phenolic ionic liquid, thereby changing the basicity of the ionic liquid. The ionic liquid [P 66614 ][3-F-4-CN-PhO] has a pKa value between HCN and H2CO3 at 25-40℃, which is beneficial to the high selective absorption of CO2. The anion and the cation are selected from a phenolic ion and a quaternary phosphonium ion, rather than the commonly used amino anion and cation in the prior art. After absorbing carbon dioxide, the ionic liquid does not form a complex three-dimensional hydrogen bond structure, has a lower viscosity, and is beneficial to improving the mass transfer efficiency of CO2, thereby making the separation of CO2 from the CO2 / HCN mixed gas more effective. The fluorine substituent and the cyano substituent on the phenol affect the basicity of the anion through electronic effect and steric effect. At the same time, the cyano group on the substituent is beneficial to further inhibiting the absorption of HCN gas when removing CO2 from the CO2 / HCN mixed gas, thereby making the separation effect better.

[0010] In addition, the chemical reaction between the O electronegative site on the phenolic hydroxyl group and CO2 is reversible, and the ionic liquid can be recycled by desorption.

[0011] [P 66614 The principle of separating CO2 from the CO2 / HCN mixed gas by the ionic liquid [P

[0012]

[0013] Preferably, the adsorption material is a porous supported ionic liquid, which is obtained by loading the ionic liquid [P 66614 ][3-F-4-CN-PhO] on a porous carrier material.

[0014] Preferably, the porous carrier material is at least one of a molecular sieve, silica gel, mesoporous carbon and activated carbon fiber.

[0015] Preferably, the molecular sieve is at least one of MCM-41, MCM-48, SBA-15, 13X, ZSM-5, and CMK-3.

[0016] Preferably, the mass fraction of the ionic liquid in the porous supported ionic liquid is 20-70%.

[0017] The ionic liquid is combined with the porous carrier material by physical or chemical methods to form a porous supported ionic liquid material as a CO2 adsorption material, which has the advantages of both ionic liquids and porous materials, can not only improve the separation effect, but also effectively avoid the high viscosity problem caused by direct absorption of ionic liquids, and improve the CO2 adsorption efficiency. Due to the large gas-liquid contact area provided by the porous material, the ionic liquid is easier to adsorb and desorb, consumes less energy, and thus greatly reduces the cost.

[0018] The preparation method of the porous supported ionic liquid is not specifically limited, and a conventional wet impregnation method can be used to obtain it, and the specific methods include but are not limited to the following methods: dissolving the ionic liquid in anhydrous ethanol, dissolving thoroughly, adding a certain amount of porous carrier material, stirring and mixing at room temperature, and then heating and vacuum drying to remove ethanol.

[0019] The application also provides the use of the above-mentioned adsorption material in the removal of CO2 from CO2 / HCN mixed gas.

[0020] Preferably, the CO2 / HCN mixed gas is introduced into the adsorption material to adsorb CO2, and the saturated adsorption material can be desorbed and recycled.

[0021] Specifically, the adsorption material is loaded into an adsorption container, helium is blown, then the helium is closed, the CO2 / HCN mixed gas is introduced into the adsorption container, selective adsorption of CO2 is carried out, after saturation, heating and vacuumizing are carried out, and the adsorption material is desorbed under helium blowing, and the desorbed material can be recycled.

[0022] Preferably, the volume fraction of CO2 in the CO2 / HCN mixed gas is 1% or more.

[0023] The ionic liquid designed in the application can selectively remove very low concentration of CO2 in CO2 / HCN mixed gas, which has great practical significance in the purification process of hydrocyanic acid in industrial production.

[0024] Preferably, the pressure of the adsorption material when adsorbing CO2 is 0.01-0.2 Mpa.

[0025] Preferably, the temperature of the adsorption material when adsorbing CO2 is 30-40℃.

[0026] The change of temperature has little influence on the change of pKa of the ionic liquid, so the influence of temperature on pKa can be ignored when the adsorption material of the application is used. When the adsorption temperature is 30-40℃, highly selective adsorption of CO2 can be realized.

[0027] Preferably, the flow rate of helium gas during adsorption and desorption is 15-25 mL / min.

[0028] Preferably, the flow rate of the mixed gas is 50-100 mL / min when the adsorption material absorbs CO2 in the CO2 / HCN mixed gas.

[0029] Preferably, the desorption temperature of the adsorption material is 80-150℃, and the desorption pressure is 0.01-1 kPa.

[0030] After the adsorption material of the application is saturated with adsorption of CO2, it can be recycled by heating and vacuumizing, and the absorption capacity of CO2 is not greatly reduced after multiple recycling, and the adsorption performance is stable.

[0031] Advantages:

[0032] (1) The adsorption material of the application can efficiently and selectively remove the by-product gas CO2 with low concentration in the industrial production of hydrogen cyanide gas, and the loss of HCN is very small during the removal process, so that hydrocyanic acid with a concentration of more than 99.8% can be prepared.

[0033] (2) The ionic liquid of the application has a larger adsorption capacity than traditional absorbents, has low energy consumption, can be recycled multiple times, has a long service life, and has stable adsorption effect. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 SEM image of the ion liquid modified SBA-15 molecular sieve of Example 1. DETAILED DESCRIPTION

[0035] Hereinafter, the technical solutions of the application will be described in detail through specific examples, but it should be clear that these examples are used for illustration, but not to limit the scope of the application.

[0036] The calculation formula of the CO2 removal rate in the examples and comparative examples of the application is: η = CO2 absorbed mass / CO2 mass passing through the absorption column*100%.

[0037] The calculation formula of the loss rate of HCN is: β = HCN reduced mass / HCN mass passing through the absorption column*100%.

[0038] Example 1

[0039] (1) 0.1 mol of tetradecyl trihexyl phosphonium chloride ([P66614 ]Cl) was added into a 500ml round bottom flask, then 150ml deionized water was added to dissolve, then 0.1mol 3-fluoro-4-cyanophenol (3-F-4-CN-PhOH) aqueous solution was slowly added dropwise through a constant pressure dropping funnel under stirring, the reaction temperature was controlled at 25°C by water bath, and the reaction was carried out for 24h. After the reaction was completed, the mixture was dried by rotary evaporator at 60°C to remove residual deionized water, and then vacuum dried at 60°C for 12h to obtain the ionic liquid [P 66614 ][3-F-4-CN-PhO].

[0040] (2) 7g of the ionic liquid [P 66614 ][3-F-4-CN-PhO] was dissolved in 50ml anhydrous ethanol, and fully stirred to completely dissolve. Then, 3g SBA-15 molecular sieve was added to the solution, and stirred at room temperature for 24h to ensure full mixing. Finally, the mixture was dried at 90°C for 24h, and vacuum dried at 70°C for 12h to remove ethanol, to obtain a white powder, which was the porous supported ionic liquid.

[0041] (3) The porous supported ionic liquid was loaded into a stainless steel empty column, and the loading was ensured to be compact, and the adsorption column was connected to the absorption device. Helium was first introduced (15mL / min) to purge for 2h at 30°C and 1bar, and then the helium was turned off. Then, the CO2 / HCN mixed gas, which was mainly composed of HCN and contained 1% CO2 by volume, was switched to flow at a flow rate of 50mL / min. The mixed gas passed through the adsorption column, and the composition and content of the outlet gas were detected by a gas chromatograph. The CO2 removal rate was 91.5%, and the HCN loss rate was 0.08%. The porous supported ionic liquid after adsorption was desorbed at 80°C and 0.1kPa helium (15mL / min), and CO2 was completely released. The desorbed material was used again for the treatment of the mixed gas, and no obvious quality loss and no obvious change in adsorption capacity were observed after more than 15 cycles.

[0042] Example 2

[0043] (1) 0.1mol of tetradecyltrihexylphosphonium chloride ([P 66614 ]Cl) was added into a 500ml round bottom flask, then 150ml deionized water was added to dissolve, then 0.1mol 3-fluoro-4-cyanophenol (3-F-4-CN-PhOH) aqueous solution was slowly added dropwise through a constant pressure dropping funnel under stirring, the reaction temperature was controlled at 25°C by water bath, and the reaction was carried out for 24h. After the reaction was completed, the mixture was dried by rotary evaporator at 60°C to remove residual deionized water, and then vacuum dried at 60°C for 12h to obtain the ionic liquid [P 66614 ][3-F-4-CN-PhO].

[0044] (2) Take 2g of [P] 66614 The [3-F-4-CN-PhO] ionic liquid was dissolved in 50 ml of anhydrous ethanol and stirred thoroughly until completely dissolved. Then, 8 g of activated carbon fiber was added to the solution, and the mixture was stirred at room temperature for 24 h to ensure thorough mixing. Finally, the mixture was dried at 90 °C for 24 h and then vacuum dried at 70 °C for 12 h to remove ethanol, yielding a porous supported ionic liquid.

[0045] (3) The porous supported ionic liquid was packed into a stainless steel empty column, ensuring tight packing. The adsorption column was connected to the absorption device, and helium gas (15 mL / min) was first introduced at 40℃ and 1 bar for 2 hours to purge, then the helium gas was turned off. Then, the CO2 / HCN mixed gas was switched to a gas with HCN as the main component and CO2 content of 1.5% by volume at a flow rate of 100 mL / min. The mixed gas passed through the adsorption column, and the composition and content of the outlet gas were detected by gas chromatograph. The CO2 removal rate was 94%, and the HCN loss rate was 0.1%. The porous supported ionic liquid after adsorption saturation was desorbed at 150℃ and 1 kPa helium gas (15 mL / min). CO2 was completely released. The desorbed material was then used to treat the mixed gas. After more than 15 cycles, there was no significant mass loss, and the adsorption capacity did not change significantly.

[0046] Example 3

[0047] (1) Add 0.1 mol of tetradecyltrihexylphosphine chloride ([P 66614 [Cl] was added to a 500 ml round-bottom flask, followed by 150 ml of deionized water to dissolve it. Then, under stirring, an aqueous solution containing 0.1 mol of 3-fluoro-4-cyanophenol (3-F-4-CN-PhOH) was slowly added dropwise through a constant-pressure dropping funnel. The reaction temperature was controlled at 25 °C using a water bath, and the reaction was carried out for 24 h. After the reaction was completed, the mixture was evaporated at 60 °C using a rotary evaporator to remove residual deionized water, and then dried under vacuum at 60 °C for 12 h to obtain the ionic liquid [P]. 66614 [3-F-4-CN-PhO].

[0048] (2) Take 5g of [P] 66614 The [3-F-4-CN-PhO] ionic liquid was dissolved in 50 ml of anhydrous ethanol and stirred thoroughly until completely dissolved. Then, 5 g of mesoporous carbon was added to the solution, and the mixture was stirred at room temperature for 24 h to ensure thorough mixing. Finally, the mixture was dried at 90 °C for 24 h and then vacuum dried at 70 °C for 12 h to remove ethanol, yielding a porous supported ionic liquid.

[0049] (3) The porous supported ionic liquid was packed into a stainless steel empty column, ensuring tight packing. The adsorption column was connected to the absorption device, and helium gas (15 mL / min) was first introduced at 35°C and 1 bar for 2 hours to purge, then the helium gas was turned off. Then, the CO2 / HCN mixed gas was switched to a gas with HCN as the main component and CO2 content of 2% by volume at a flow rate of 60 mL / min. The mixed gas passed through the adsorption column, and the composition and content of the outlet gas were detected by gas chromatograph. The CO2 removal rate was 93%, and the HCN loss rate was 0.15%. The porous supported ionic liquid after adsorption saturation was desorbed at 80°C and 0.01 kPa helium gas (15 mL / min). CO2 was completely released. The desorbed material was then used to treat the mixed gas. After more than 15 cycles, there was no significant mass loss, and the adsorption capacity did not change significantly.

[0050] Example 4

[0051] (1) Add 0.1 mol of tetradecyltrihexylphosphine chloride ([P 66614 [Cl] was added to a 500 ml round-bottom flask, followed by 150 ml of deionized water to dissolve it. Then, under stirring, an aqueous solution containing 0.1 mol of 3-fluoro-4-cyanophenol (3-F-4-CN-PhOH) was slowly added dropwise through a constant-pressure dropping funnel. The reaction temperature was controlled at 25 °C using a water bath, and the reaction was carried out for 24 h. After the reaction was completed, the mixture was evaporated at 60 °C using a rotary evaporator to remove residual deionized water, and then dried under vacuum at 60 °C for 12 h to obtain the ionic liquid [P]. 66614 [3-F-4-CN-PhO].

[0052] (2) Ionic liquid [P 66614 [3-F-4-CN-PhO] was packed into a stainless steel empty column, which was then connected to the absorption device. The column was purged with helium (15 mL / min) for 2 hours at 35°C and 1 bar, then the helium was stopped. The process was then switched to a CO2 / HCN mixed gas, with HCN as the main component and CO2 content at a volume fraction of 1.2%, at a flow rate of 70 mL / min. The mixed gas was passed through the adsorption column, and the composition and content of the outlet gas were analyzed by gas chromatograph. The CO2 removal rate was 92%, and the HCN loss rate was 0.2%. The [P] after adsorption saturation was then... 66614 [3-F-4-CN-PhO] was desorbed at 100℃ under 0.01kPa helium (15mL / min), and CO2 was completely released. The desorbed material was then used to treat the mixed gas. After more than 15 cycles, there was no significant mass loss and no significant change in adsorption capacity.

[0053] Comparative Example

[0054] (1) Add 0.1 mol of tetradecyltrihexylphosphine chloride ([P 66614 [Cl] was added to a 500 ml round-bottom flask, followed by 150 ml of deionized water to dissolve it. Then, under stirring, an aqueous solution containing 0.1 mol of 3-fluorophenol (3-F-PhOH) was slowly added dropwise through a constant-pressure dropping funnel. The reaction temperature was controlled at 25 °C using a water bath, and the reaction was carried out for 24 h. After the reaction was completed, the mixture was evaporated at 60 °C using a rotary evaporator to remove residual deionized water, and then dried under vacuum at 60 °C for 12 h to obtain the ionic liquid [P]. 66614 [3-F-PhO].

[0055] (2) Take 7g of [P] 66614 The [3-F-PhO] ionic liquid was dissolved in 50 ml of anhydrous ethanol and stirred thoroughly until completely dissolved. Then, 3 g of SBA-15 molecular sieve was added to the solution, and the mixture was stirred at room temperature for 24 h to ensure thorough mixing. Finally, the mixture was dried at 90 °C for 24 h and then vacuum dried at 70 °C for 12 h to remove ethanol, yielding a porous supported ionic liquid.

[0056] (3) The porous supported ionic liquid was packed into a stainless steel empty column, ensuring tight packing. The adsorption column was connected to the absorption device, and helium gas (15 mL / min) was first introduced at 30℃ and 1 bar for 2 hours to purge, then the helium gas was turned off. Then, the CO2 / HCN mixed gas was switched to a gas with HCN as the main component and CO2 content of 1% by volume at a flow rate of 50 mL / min. The mixed gas passed through the adsorption column, and the composition and content of the outlet gas were detected by gas chromatograph. The CO2 removal rate was 92.5%, and the HCN loss rate was 7%. The porous supported ionic liquid after adsorption saturation was desorbed at 80℃ and 0.1 kPa helium gas (15 mL / min). CO2 was completely released. The desorbed material was then used to treat the mixed gas. After more than 15 cycles, there was no significant mass loss, and the adsorption capacity did not change significantly.

[0057] Due to ionic liquids [P 66614 At the adsorption temperature, the pKa of [3-F-PhO] is greater than that of HCN, meaning that the basicity of this ionic liquid is greater than that of both H2CO3 and HCN. This results in the adsorption of HCN during the separation of CO2 in a CO2 / HCN mixture, leading to a significant loss of HCN gas.

[0058] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. Use of an adsorbent material for removing CO2 from a CO2 / HCN mixture, characterized in that, The adsorbent material comprises an ionic liquid [P 66614 ][3-F-4-CN-PhO].

2. Use of the adsorbent material according to claim 1 for removing CO2 from a CO2 / HCN mixture, characterized in that, The adsorbent material is a porous supported ionic liquid, which is an ionic liquid [P 66614 ][3-F-4-CN-PhO] supported on a porous support material.

3. Use of the adsorbent material according to claim 2 for the removal of CO2 from a CO2 / HCN mixture, characterized in that, The porous carrier material is at least one of a molecular sieve, silica gel, mesoporous carbon, and activated carbon fiber.

4. Use of the adsorbent material according to claim 3 for the removal of CO2 from a CO2 / HCN mixture, characterized in that, The molecular sieve is at least one of MCM-41, MCM-48, SBA-15, 13X, ZSM-5, and CMK-3.

5. Use of the adsorbent material according to any one of claims 2 to 4 for the removal of CO2 from a CO2 / HCN mixture, characterized in that, The mass fraction of the ionic liquid in the porous supported ionic liquid is 20-70%.

6. Use of the adsorbent material according to claim 1 for removing CO2 from a CO2 / HCN mixture, characterized in that, The CO2 / HCN mixed gas is introduced into the adsorbent material to adsorb CO2, and the adsorbent material can be desorbed and recycled after being saturated with CO2.

7. Use of the adsorbent material according to claim 6 for the removal of CO2 from a CO2 / HCN mixture, characterized in that, The volume fraction of CO2 in the CO2 / HCN mixed gas is greater than 1%.

8. Use of the adsorbent material according to claim 6 or 7 for the removal of CO2 from a CO2 / HCN mixture, characterized in that, The temperature of the adsorbent material when adsorbing CO2 is 30-40℃.

9. Use of the adsorbent material according to claim 6 or 7 for the removal of CO2 from a CO2 / HCN mixture, characterized in that, The desorption temperature of the adsorbent material is 80-150℃, and the desorption pressure is 0.01-1kPa.

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