A method for preparing a modified anti-polymerization adsorbent for styrene adsorption and its product.

Abstract

The application discloses a preparation method of a modified anti-polymerization adsorbent for styrene adsorption, and comprises the following steps: (1) mixing a molecular sieve carrier with ammonia water, uniformly stirring, and obtaining an ammonia modified molecular sieve carrier through post-treatment I; (2) mixing the ammonia modified molecular sieve carrier, a metal precursor and deionized water, and obtaining the modified anti-polymerization adsorbent through impregnation treatment, post-treatment II and calcination treatment. When the modified adsorbent prepared by the method is used in a VOCs adsorption reaction in rubber chemical industry flue gas, the styrene in the VOCs has the characteristics of large adsorption capacity and strong anti-styrene polymerization capacity.

Description

Technical Field

[0001] This invention relates to the technical field of adsorbents, and more particularly to a modified anti-polymerization adsorbent for styrene adsorption and its preparation method. Background Technology

[0002] Synthetic rubber is widely used in the manufacture of tires, hoses, belts, and cables, and is one of the important basic industries of my country's national economy. VOCs (volatile organic compounds) are a major pollutant in the rubber chemical industry, accounting for over 95% of its total emissions. The emissions are large, complex, and contain high levels of non-methane hydrocarbons, with malodorous components causing serious environmental pollution. In practical applications, the complex composition of VOCs in the waste gas from the rubber chemical industry easily leads to problems such as incomplete adsorption by adsorbents and VOC polymerization on the adsorbent surface. Among the typical components of VOCs, styrene is a representative aromatic hydrocarbon (AH) compound that can harm human health and the environment. Therefore, effectively controlling styrene emissions is of great research significance. Consequently, domestic and international research on adsorption technology mainly focuses on the design and development of highly efficient adsorption materials.

[0003] In recent years, VOCs treatment technologies have been greatly improved. VOCs control technologies are mainly divided into two categories: source control and end-of-pipe treatment. Source control reduces VOCs generation by enacting relevant laws and regulations to regulate enterprise emissions and by restricting and treating raw materials. End-of-pipe treatment, on the other hand, uses various treatment technologies to prevent and control pollution and is the main technology for VOCs control. Currently, the end-of-pipe treatment technologies we commonly use include two main categories: VOCs recovery technologies and VOCs destruction technologies. Recovery methods utilize physical methods to effectively treat and separate VOCs, mainly including VOCs adsorption and absorption technologies. Destruction technologies are methods that use biological processes or catalytic materials to completely oxidize organic matter, including biological control technologies, low-temperature plasma control technologies, and catalytic oxidation technologies.

[0004] Molecular sieves have the following characteristics: (1) They have a large specific surface area and pore volume, and their adsorption properties can be changed by adjusting the surface functional groups; (2) They can separate mixed organic matter according to the pore diameter, thus playing a sieving role; (3) For organic matter with similar molecular diameters, they are more likely to adsorb highly polar organic matter; (4) Their main component is aluminosilicate, which is heat-resistant and can maintain a high adsorption capacity under low concentration and high temperature environments, and the high-temperature regeneration process is safe. Therefore, molecular sieves are widely used as adsorbent materials or catalyst carriers in capturing small molecule gases, selective catalysis, and product purification.

[0005] To address the physicochemical properties of styrene, adsorbents must possess not only high adsorption activity but also the tendency of styrene molecules to polymerize. Specifically, under the influence of free radicals, the C=C bonds in styrene break, forming styrene free radicals. These free radicals then polymerize with another styrene molecule, forming even larger free radicals, ultimately resulting in highly viscous polystyrene. The aggregation of polystyrene on the adsorbent surface leads to a decrease in adsorbent activity and eventual deactivation. Therefore, developing adsorbents with good resistance to styrene polymerization is currently a major research direction. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, this invention discloses a method for preparing a modified anti-polymerization adsorbent for styrene adsorption. The prepared modified adsorbent exhibits high adsorption capacity for styrene (St) and has the advantage of resisting styrene polymerization when used for VOCs adsorption reactions in flue gas from the rubber chemical industry.

[0007] The specific technical solution is as follows:

[0008] A method for preparing a modified anti-polymerization adsorbent for styrene adsorption includes the following steps:

[0009] (1) The molecular sieve carrier is mixed with ammonia water and stirred thoroughly. After post-treatment I, the ammonia-modified molecular sieve carrier is obtained.

[0010] (2) The ammonia-modified molecular sieve carrier, the metal precursor and deionized water are mixed and then subjected to impregnation treatment, post-treatment II and calcination treatment to obtain the modified anti-polymerization adsorbent.

[0011] Experiments have shown that the modified anti-polymerization adsorbent prepared by using molecular sieve as a carrier and ammonia modification in conjunction with metal modification can not only significantly increase the adsorption capacity of the adsorbent for styrene, but more importantly, it can significantly improve the anti-styrene polymerization performance.

[0012] Regarding the resistance to styrene polymerization, comparative experiments revealed that when USY molecular sieves were used directly as the carrier, polystyrene spheres were clearly observed on the adsorbent surface after styrene adsorption activity testing. When only ammonia modification was applied to the USY molecular sieve carrier, polystyrene spheres were still observed on the adsorbent surface after activity testing, but their volume decreased. When metal modification was applied to the USY molecular sieve carrier, styrene polymerization on the adsorbent surface decreased after activity testing, and the number of styrene spheres decreased significantly, but their volume increased slightly. When both ammonia and metal modification were applied to the USY molecular sieve carrier, no polystyrene spheres were observed on the adsorbent surface after activity testing.

[0013] In step (1):

[0014] The molecular sieve support is selected from USY molecular sieve support.

[0015] The concentration of the ammonia solution is 0.5–10 mol·L⁻¹. -1 Preferably 2–6 mol·L -1 .

[0016] The mass-to-volume ratio of the molecular sieve carrier to ammonia water is 0.1–1.0 g / mL, preferably 0.1–0.5 g / mL.

[0017] In step (1):

[0018] The thorough stirring is carried out at a speed of 100–300 r·min. -1 The time is 5 to 8 hours.

[0019] After thorough stirring, ensure that the molecular sieve carrier and ammonia water are evenly mixed.

[0020] The post-processing I includes filtration, washing, and drying.

[0021] The wash is made until neutral;

[0022] The drying process is carried out at a temperature of 80–100°C for 3–6 hours.

[0023] In step (2):

[0024] The metal precursor is selected from one or more of the following: metal chlorides, nitrates, and sulfates;

[0025] The metal is selected from one or more of silver, copper, and aluminum.

[0026] The mass-to-volume ratio of ammonia-modified molecular sieve carrier to deionized water is 5–20 g / L, preferably 8–15 g / L.

[0027] The mass ratio of ammonia-modified molecular sieve support to metal precursor is 1:(0.05-0.25).

[0028] Preferred:

[0029] The metal precursor is selected from silver nitrate and copper nitrate;

[0030] The mass ratio of ammonia-modified molecular sieve support, silver nitrate, and copper nitrate is 1:(0.01–0.05):(0.08–0.14).

[0031] Experiments have shown that the modified adsorbent prepared by co-loading with metal Ag and Cu exhibits better adsorption performance and resistance to styrene polymerization.

[0032] In step (2):

[0033] The impregnation treatment is carried out under stirring at a speed of 100–300 r / min. -1 The time is 3 to 8 hours; preferably 200 r·min. -1 The time is 5 hours.

[0034] The post-processing II includes filtration and drying.

[0035] The calcination treatment is carried out at a temperature of 300–500°C for 2–8 hours; preferably at 400°C.

[0036] The present invention also discloses a modified antipolymerization adsorbent for styrene adsorption prepared according to the method.

[0037] The modified anti-polymerization adsorbent uses ammonia-modified molecular sieves as a carrier, and the loaded active components are selected from one or more of silver oxide, copper oxide, and aluminum oxide.

[0038] Preferably, the supported active component is selected from silver oxide and copper oxide.

[0039] The modified anti-polymerization adsorbent prepared in this invention is used in the adsorption reaction of VOCs in the exhaust gas of the rubber industry. It has the characteristics of large adsorption capacity and strong anti-styrene polymerization ability for styrene.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] This invention discloses a method for preparing a modified anti-polymerization adsorbent. The modified adsorbent prepared by using molecular sieve as a carrier and ammonia modification combined with metal modification can not only significantly improve its adsorption capacity for styrene, but also significantly improve its anti-styrene polymerization ability. Attached Figure Description

[0042] Figure 1 The XRD patterns are of the adsorbents prepared in Examples 1-4, respectively.

[0043] Figure 2 The FTIR curve of the adsorbent prepared in Example 2 as a function of adsorption time;

[0044] Figure 3 Here are SEM images of St adsorbed using USY molecular sieve support as adsorbent.

[0045] Figure 4 The image shows a SEM image of the adsorbent prepared in Comparative Example 1 after adsorbing St.

[0046] Figure 5 The image shows a SEM image of the adsorbent prepared in Comparative Example 2 after adsorbing St.

[0047] Figure 6The image shows a SEM image of St after adsorption using the adsorbent prepared in Example 2. Detailed Implementation

[0048] The specific implementation methods of the present invention will be further described below with reference to examples. It should be noted that the specific implementation methods described herein are only for illustration and explanation of the present invention and are not intended to limit the scope of protection of the present invention.

[0049] Example 1

[0050] (1) Weigh 10.00 g of USY molecular sieve support and 50 mL of 4 mol·L⁻¹ -1 Add NH3·H2O and place it in a 500 mL beaker. Stir with a magnetic stirrer at 200 rpm. -1 After stirring for 432 minutes, filtering and washing to adjust the pH to neutral, the mixture was dried in an oven at 100°C for 4 hours to obtain the ammonia-modified USY molecular sieve support.

[0051] (2) Weigh 5.00g of ammonia-modified USY molecular sieve support, 0.08g of AgNO3 and 0.40g of Cu(NO3)2·3H2O, place them in a 500mL beaker and add 500mL of deionized water, and stir with a magnetic stirrer at 200r·min. -1 Stir for 5 hours, dry in an oven at 100℃ for 1 hour, then calcine in a muffle furnace at 400℃ for 5 hours, press into tablets, and sieve to finally obtain the modified anti-polymerization adsorbent.

[0052] Example 2

[0053] The preparation process is basically the same as in Example 1, except that in step (2), the raw materials weighed are replaced with 5.00g of ammonia-modified USY molecular sieve support, 0.25g of AgNO3 and 0.64g of Cu(NO3)2·3H2O.

[0054] Example 3

[0055] The preparation process is basically the same as in Example 1, except that in step (2), the weighed raw materials are replaced with 5.00g of ammonia-modified USY molecular sieve support and 0.25g of AgNO3, and copper nitrate is not added.

[0056] Example 4

[0057] The preparation process is basically the same as in Example 1, except that in step (2), the raw materials weighed are replaced with 5.00g of ammonia-modified USY molecular sieve support and 0.64g of Cu(NO3)2·3H2O, and silver nitrate is not added.

[0058] Figure 1The XRD patterns of the adsorbents prepared in Examples 1-4 are shown in the figure. Diffraction peaks were observed at 2θ = 7.2°, 11.7°, 13.8°, 18.2°, 21.7°, 25.1°, 27.5°, 31.5°, and 36.6°, corresponding to the dealuminolite molecular sieves (111), (220), (311), and (331), respectively.

[0059] (511), (442), (533), (642) and (555) lattice planes, PDF#88-2290. No diffraction peaks corresponding to silver and copper were observed, indicating that the silver and copper contents are low and the dispersion is high.

[0060] Comparative Example 1

[0061] Weigh 10.00 g of USY molecular sieve support and 50 mL of 4 mol·L⁻¹. -1 Add NH3·H2O and place it in a 500 mL beaker. Stir with a magnetic stirrer at 200 rpm. -1 After stirring for 432 minutes, filtering and washing to adjust the pH to neutral, the mixture was dried in an oven at 100°C for 4 hours to obtain the ammonia-modified USY molecular sieve support.

[0062] Comparative Example 2

[0063] Weigh 5.00 g of USY molecular sieve support, 0.25 g of AgNO3, and 0.64 g of Cu(NO3)2·3H2O, place them in a 500 mL beaker, add 500 mL of deionized water, and stir with a magnetic stirrer at 200 r·min. -1 Stir for 432 minutes, dry in an oven at 100°C for 1 hour, then calcine in a muffle furnace at 400°C for 5 hours, press into tablets, and sieve to obtain the final adsorbent.

[0064] Activity test for adsorbing styrene:

[0065] The adsorbents prepared according to the various examples and comparative examples, as well as the adsorbent using USY molecular sieve support as a blank group, were subjected to adsorption tests on styrene (St) under the following conditions:

[0066] The adsorption reaction of styrene was detected and quantitatively analyzed using an online gas chromatograph equipped with an FID detector. The test conditions were as follows: carrier gas: high-purity N2; inlet temperature: 165℃; column oven temperature: 150℃; FID detector temperature: 180℃; reaction condition: 0.1g adsorbent (40-60 mesh); reaction gas: 200ppm styrene stripping gas + N2 (equilibrium); flow rate: 50mL / min.

[0067] The adsorbents prepared in each embodiment and comparative example, as well as the adsorbents using USY molecular sieve support as a blank group, are listed in Table 1 below for their adsorption capacity for styrene (St).

[0068] Table 1

[0069] serial number <![CDATA[St adsorption capacity / mg·g -1 > Example 1 190.4 Example 2 392.7 Example 3 156.2 Example 4 186.5 Comparative Example 1 100.0 Comparative Example 2 137.2 Blank group 51.7

[0070] Figure 2 The figure shows the FTIR spectrum of the adsorbent prepared in Example 2 as a function of adsorption time. The graphs show the FTIR spectra of the adsorbent after 1 h, 2 h, 3 h, 4 h, and 5 h of styrene adsorption. At 1590 cm⁻¹, the FTIR spectrum is... -1 And 1493cm -1 A relatively obvious vibrational peak appeared at 1460 cm⁻¹, which is the stretching vibration peak of the benzene ring. -1 The peak at 2924 cm⁻¹ represents the stretching vibration of the C=C bond. -1 The peak at this point represents the antisymmetric stretching vibration of the —CH2— bond. If styrene undergoes polymerization, the C=C bond needs to be broken to form the —CH2— bond to initiate the polymerization reaction. This leads to the C=C bond becoming undetectable due to breakage, while the —CH2— bond strength shows a significant increase. Infrared characterization results show that the stretching vibration peak of the C=C bond strengthens with increasing adsorption time, indicating that the adsorbent has a good adsorption effect on styrene. Simultaneously, the —CH2— bond vibration peak does not show a significant change with increasing adsorption time, indicating that the adsorbent has a good anti-polymerization effect, inhibiting the conversion of styrene to polystyrene.

[0071] Figure 3 The image shows a SEM image of styrene adsorbed using USY molecular sieve as the adsorbent. The polymerization of styrene on the adsorbent surface is obvious, and the resulting polystyrene spheres are relatively large.

[0072] Figure 4 The image shows a SEM image of the adsorbent prepared in Comparative Example 1 after adsorbing St. It was observed that the polymerization of styrene on the surface of the adsorbent was still obvious, but the volume of the polystyrene spheres formed decreased.

[0073] Figure 5 The image shows a SEM image of the adsorbent prepared in Comparative Example 2 after adsorbing St. It was observed that the polymerization of styrene on the surface of the adsorbent decreased significantly, but the number of polystyrene spheres formed decreased significantly, while their volume increased slightly.

[0074] Figure 6 The image shows a SEM image of St after adsorption by the adsorbent prepared in Example 2. No polystyrene spheres were observed on the surface of the adsorbent.

[0075] contrast Figure 3 and Figure 4 It was found that after ammonia modification of the USY molecular sieve support, the volume of polystyrene microspheres decreased. This may be because ammonia modification changes the surface pore structure and functional groups, resulting in a slight anti-polymerization effect in the sample.

[0076] contrast Figure 3 and Figure 5 It was found that after metal modification of the USY molecular sieve support, the number of polystyrene microspheres decreased significantly. This may be because the metal modification caused the introduced metal ions to form a π complex with the styrene molecules, which effectively prevented the carbon-carbon double bonds of the styrene molecules from breaking and undergoing polymerization, thus resulting in an anti-polymerization effect in the sample.

[0077] contrast Figure 3 and Figure 6 It was found that after simultaneous ammonia and metal modification of the USY molecular sieve support, polystyrene microspheres were barely observable. Therefore, it was inferred that the sample had excellent anti-polymerization effect, which was the result of the combined effect of ammonia and metal modification.

[0078] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The specific examples used above to illustrate the present invention are only for the purpose of helping to understand the present invention and are not intended to limit the present invention. Those skilled in the art to which this invention pertains can make several simple deductions, modifications, substitutions, or combinations based on the concept of the present invention. These deductions, modifications, substitutions, or combinations also fall within the scope of the claims of the present invention.

Claims

1. Use of a modified anti-polymerization adsorbent for the adsorption of styrene, characterized in that, The preparation method of the modified anti-polymerization adsorbent comprises the following steps: (1) mixing a molecular sieve carrier with ammonia water, uniformly stirring, and then obtaining an ammonia modified molecular sieve carrier through post-treatment I; The molecular sieve carrier is selected from a USY molecular sieve carrier; (2) mixing the ammonia modified molecular sieve carrier, a metal precursor and deionized water, obtaining the modified anti-polymerization adsorbent through impregnation treatment, post-treatment II and calcination treatment; The metal precursor is selected from one or more of chlorides, nitrates and sulfates of metals; The metal is selected from one or more of silver and copper.

2. Use of the modified anti-polymerization adsorbent according to claim 1 for styrene adsorption, characterized in that, In step (1): The concentration of the ammonia water is 0.5-10 mol·L -1 ; The mass-volume ratio of the molecular sieve carrier to ammonia water is 0.1-1.0 g / mL.

3. Use of the modified anti-polymerization adsorbent according to claim 1 for styrene adsorption, characterized in that, In step (1): The sufficient stirring is at a speed of 100-300 r·min -1 for 5-8 hours.

4. Use of the modified anti-polymerization adsorbent according to claim 1 for styrene adsorption, characterized in that, In step (1): The post-treatment I comprises filtration, washing and drying treatment.

5. Use of the modified anti-polymerization adsorbent according to claim 1 for styrene adsorption, characterized in that, In step (2): The mass-volume ratio of the ammonia modified molecular sieve carrier to deionized water is 5-20 g / L; The mass ratio of the ammonia modified molecular sieve carrier to the metal precursor is 1:(0.05-0.25).

6. Use of the modified anti-polymerization adsorbent according to claim 1 for styrene adsorption, characterized in that, In step (2): The impregnation treatment is carried out under stirring at a rotation speed of 100-300 r·min -1 for 3-8 h. The post-treatment II comprises filtration and drying treatment; The temperature of the calcination treatment is 300-500 ℃, and the time is 2-8 h.

7. Use of the modified anti-polymerization adsorbent according to claim 1 for styrene adsorption, characterized in that, In step (2): The metal precursor is selected from silver nitrate and copper nitrate; The mass ratio of the ammonia modified molecular sieve carrier, silver nitrate and copper nitrate is 1:(0.01-0.05):(0.08-0.14).

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