A method for preparing modified 13x molecular sieve

Abstract

This invention provides a method for preparing modified 13x molecular sieves, comprising the following steps: S1, adding ammonia ion solution to a 13x molecular sieve sample to submerge the sample, heating at 80-100℃ for 1-3 hours for ion exchange to obtain an intermediate; S2, taking the intermediate obtained in step S1, soaking and washing it in deionized water, drying it at 120℃, and then calcining it at 550℃ for 2-3 hours to obtain an ion-exchanged sample; S3, taking the ion-exchanged sample obtained in step S2, purging it with argon gas for 20-30 minutes, calcining it, and then treating it with deionized water droplets for 6-8 hours, cooling it to 80℃ and removing it to obtain a 13x modified molecular sieve. This method reduces problems such as molecular sieve framework collapse and deactivation, and crystal breakage. Furthermore, it does not use silane coupling agents during production, thus avoiding the generation of additional waste gas and wastewater, reducing production costs and environmental pollution. The modified 13x molecular sieve prepared by this method can also meet the requirements for efficient capture and recovery of CO2 in humid flue gas environments.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation, and more particularly to a method for preparing modified 13x molecular sieve. Background Technology

[0002] The massive release of carbon dioxide from global industrial and energy production is one of the main contributors to climate change. Many industrial and energy production processes generate exhaust gases that often carry water vapor, making CO2 capture from these humid flue gases particularly crucial. Under humid conditions, the effectiveness of traditional CO2 capture molecular sieve materials is often limited, leading to a decline in the adsorption performance of traditional adsorbents.

[0003] Patents CN116212815A, CN115417422A, and CN103301805A all modify molecular sieves by soaking them in alkaline solution to increase CO2 adsorption sites. However, this treatment method does not solve the competitive adsorption relationship between CO2 and water. When the two coexist, the molecular sieve will adsorb more water molecules, occupy the active sites, and thus lose its function.

[0004] Patent CN113083227A employs a more thorough alkali treatment, which increases CO2 adsorption sites while removing the framework aluminum in the molecular sieve, thus achieving hydrophobic modification. However, this method requires high processing precision, and excessive alkali treatment can easily cause large-scale collapse and deactivation of the molecular sieve framework, resulting in grain breakage, which is not conducive to industrial-scale application.

[0005] Patents CN112390270A, CN115445582A, CN114570328A, CN102992341B, and CN115228431A all employ silane coupling agents to dealucate the molecular sieve framework and perform hydrophobic modification. However, silane coupling agents are expensive, and large quantities are typically added to ensure effective use, further increasing costs. Moreover, they are prone to decomposition under high temperature and humidity, generating additional waste gas and wastewater during production and use, which is neither economically sound nor environmentally friendly. Summary of the Invention

[0006] The present invention provides a method for preparing modified 13x molecular sieves, which is used to solve related technical problems in the background art.

[0007] The technical solution provided by this invention is as follows: A method for preparing modified 13x molecular sieve, comprising the following steps:

[0008] S1. Add ammonia ion solution to the 13x molecular sieve sample to cover the sample, and heat at 80-100℃ for 1-3 hours to carry out ion exchange to obtain the intermediate.

[0009] S2. Take the intermediate obtained in step S1, soak and wash it in deionized water, dry it at 120°C, and then calcine it at 550°C for 2-3 hours to obtain the ion exchange sample.

[0010] S3. Take the ion exchange sample obtained in step S2, pass argon gas through it for 20-30 minutes, calcine it, and then treat it with deionized water for 6-8 hours. After cooling it to 80℃, take it out to obtain 13x modified molecular sieve.

[0011] In one embodiment, the concentration of the ammonia ion solution in step S1 is 0.5-1.5 mol / L.

[0012] In one embodiment, the ammonia ion solution in step S1 is ammonium sulfate.

[0013] In one embodiment, the ion exchange sample obtained in step S2 is subjected to the steps of soaking, washing, drying, and calcining 0-2 times.

[0014] In one embodiment, in step S3, the ion exchange sample is placed in a tube furnace, and during calcination, the temperature in the tube furnace is increased to 650°C at a rate of 3-5°C / min.

[0015] In one embodiment, in step S3, the deionized water is added at a rate of 10-30 drops / min.

[0016] The modified 13x molecular sieve adsorbent material prepared according to the above preparation method is applied to CO2 adsorption and capture in a humid environment.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention discloses a method for preparing modified 13x molecular sieves. First, sodium ions in the 13x molecular sieve are effectively removed by ammonium ion exchange, making the molecular sieve skeleton easier to remove aluminum. Then, the molecular sieve skeleton is dealuminized by high-temperature hydrothermal treatment. High-temperature hydrothermal treatment has a significant effect on the removal of skeleton aluminum and has little impact on the structure of the molecular sieve itself. It is less likely to cause problems such as collapse and deactivation of the molecular sieve skeleton and crystal breakage. Thus, it achieves the beneficial effect of large-scale production of modified 13x molecular sieves and reduces the cost of its industrial production.

[0019] The present invention discloses a method for preparing modified 13x molecular sieves. First, sodium ions in the 13x molecular sieve are effectively removed by ammonium ion exchange, making the molecular sieve skeleton easier to remove aluminum. Then, the molecular sieve skeleton is dealuminized by high-temperature hydrothermal treatment. By reducing the crystalline aluminum content and eliminating polar ions in the skeleton, its hydrophobic properties are improved. This enables the modified 13x molecular sieve to achieve efficient CO2 adsorption in the presence of water vapor, thus realizing the technical effect of efficient capture and recovery of CO2 in humid flue gas emitted by gas-fired and coal-fired power plants.

[0020] The method for preparing modified 13x molecular sieves of this invention reduces problems such as molecular sieve framework collapse and deactivation, and crystal breakage. Moreover, it does not use silane coupling agents in the production process, and does not generate additional waste gas and wastewater, which not only reduces production costs, but also reduces environmental pollution. Furthermore, the modified 13x molecular sieve prepared by this method can also meet the requirements for efficient capture and recovery of CO2 in humid flue gas in humid flue gas environments. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the adsorption effects of modified 13x molecular sieve samples on CO2 obtained in various embodiments of the preparation method of modified 13x molecular sieve of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] In this application, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe the present invention and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation. Example

[0025] S1. Add 1 mol / L ammonium sulfate solution to the 13x molecular sieve sample to cover the sample, and heat at 90℃ for 2 h to carry out ion exchange to obtain the intermediate.

[0026] S2. Pour out the ammonium sulfate solution, take the intermediate obtained in step S1, soak and wash it with deionized water, dry it at 120°C, and calcine it in a muffle furnace at 550°C for 3 hours to obtain the ion exchange sample.

[0027] S3. Take the ion exchange sample obtained in step S2, place it in a tube furnace, introduce argon gas for 20 min, then heat the tube furnace to 650℃ at a rate of 4℃ / min for calcination, and treat it with deionized water at a rate of 20 drops / min for 8 h. After cooling naturally to 80℃, take it out to obtain the 13x modified molecular sieve sample 13x-JH1. Example

[0028] S1. Add 1 mol / L ammonium sulfate solution to the 13x molecular sieve sample to cover the sample, and heat at 90℃ for 2 h to carry out ion exchange to obtain the intermediate.

[0029] S2. Pour out the ammonium sulfate solution, take the intermediate obtained in step S1, soak and wash it with deionized water, dry it at 120°C, and calcine it in a muffle furnace at 550°C for 3 hours to obtain the first ion exchange sample. Repeat the soaking, washing, drying and calcining steps once to obtain the second ion exchange sample.

[0030] S3. Take the second ion exchange sample obtained in step S2, place it in a tube furnace, introduce argon gas for 20 min, then heat the tube furnace to 650℃ at a rate of 4℃ / min for calcination, and treat it with deionized water at a rate of 20 drops / min for 8 h. After cooling naturally to 80℃, take it out to obtain the 13x modified molecular sieve sample 13x-JH2. Example

[0031] S1. Add 1 mol / L ammonium sulfate solution to the 13x molecular sieve sample to cover the sample, and heat at 90℃ for 2 h to carry out ion exchange to obtain the intermediate.

[0032] S2. Pour out the ammonium sulfate solution, take the intermediate obtained in step S1, soak and wash it with deionized water, dry it at 120°C, and calcine it in a muffle furnace at 550°C for 3 hours to obtain the first ion exchange sample. Repeat the soaking, washing, drying and calcining steps twice to obtain the second ion exchange sample.

[0033] S3. Take the second ion exchange sample obtained in step S2, place it in a tube furnace, introduce argon gas for 20 min, then heat the tube furnace to 650℃ at a rate of 4℃ / min for calcination, and treat it with deionized water at a rate of 20 drops / min for 8 h. After cooling naturally to 80℃, take it out to obtain the 13x modified molecular sieve sample 13x-JH3. Example

[0034] S1. Add 0.5 mol / L ammonium sulfate solution to the 13x molecular sieve sample to cover the sample, and heat at 80℃ for 1 h to carry out ion exchange to obtain the intermediate;

[0035] S2. Pour out the ammonium sulfate solution, take the intermediate obtained in step S1, soak and wash it with deionized water, dry it at 120°C, and calcine it in a muffle furnace at 550°C for 2 hours to obtain the first ion exchange sample. Repeat the soaking, washing, drying, and calcining steps once to obtain the second ion exchange sample.

[0036] S3. Take the second ion exchange sample obtained in step S2, place it in a tube furnace, introduce argon gas for 25 min, then heat the tube furnace to 600℃ at a rate of 3℃ / min for calcination, and treat it with deionized water at 10 drops / min for 6 h. After cooling naturally to 80℃, take it out to obtain the 13x modified molecular sieve sample 13x-JH4. Example

[0037] S1. Add 1.5 mol / L ammonium sulfate solution to the 13x molecular sieve sample to cover the sample, and heat at 100℃ for 3 h to carry out ion exchange to obtain the intermediate;

[0038] S2. Pour out the ammonium sulfate solution, take the intermediate obtained in step S1, soak and wash it in deionized water, dry it at 120°C, and calcine it in a muffle furnace at 550°C for 2.5 hours to obtain the first ion exchange sample. Repeat the soaking, washing, drying, and calcining steps once to obtain the second ion exchange sample.

[0039] S3. Take the second ion exchange sample obtained in step S2, place it in a tube furnace, introduce argon gas for 30 min, then heat the tube furnace to 700℃ at a rate of 5℃ / min for calcination, and treat it with deionized water at a rate of 30 drops / min for 7 h. After cooling naturally to 80℃, take it out to obtain the 13x modified molecular sieve sample 13x-JH5.

[0040] Comparative Example 1

[0041] S1. Add deionized water to the 13x molecular sieve sample to cover the sample, and heat at 90℃ for 2 hours to obtain the intermediate.

[0042] S2. Pour out the deionized water, take the intermediate obtained in step S1, dry it at 120°C, and calcine it in a muffle furnace at 550°C for 3 hours to obtain a preliminary sample.

[0043] S3. Take the preliminary sample obtained in step S2, place it in a tube furnace, introduce argon gas for 20 minutes, then heat it to 650℃ at a rate of 4℃ / min and calcine it for 8 hours. After cooling it naturally to 80℃, take it out to obtain the 13x modified molecular sieve sample 13x-JH0.

[0044] The sodium elemental analysis of the samples obtained in the above embodiments was performed using X-ray fluorescence spectroscopy, and the results are shown in Table 1:

[0045] Table 1 - Sodium elemental analysis results of samples obtained from various ammonium ion exchange examples.

[0046] Sample number <![CDATA[Na2O / %]]> 13x-JH0 3.21 13x-JH1 1.13 13x-JH2 0.12 13x-JH3 0.10 13x-JH4 0.22 13x-JH5 0.11

[0047] As can be seen above, the removal of sodium ions from 3x molecular sieves by ammonium ion exchange is effective. Furthermore, the amount of sodium ions remaining in 13x-JH2 and 13x-JH3 shows that the effect weakens after two repeated exchanges. Therefore, repeating the ammonium ion exchange step twice in Example 3 is the best embodiment for removing sodium ions from 3x molecular sieves.

[0048] The samples obtained in the above embodiments were analyzed for silicon and aluminum elements using X-ray fluorescence spectroscopy. The results are shown in Table 2.

[0049] Table 2 - Elemental analysis results of silicon and aluminum in samples obtained from various hydrothermal treatment examples

[0050] Sample number <![CDATA[SiO2 / %]]> <![CDATA[Al2O3 / %]]> <![CDATA[SiO2 / Al2O3]]> 13x-JH0 66.99 24.81 2.7 13x-JH1 82.91 9.39 8.83 13x-JH2 82.45 9.15 9.01 13x-JH3 82.94 9.16 9.05 13x-JH4 81.38 9.97 8.16 13x-JH5 81.49 9.08 8.97

[0051] As can be seen above, after ammonium ion exchange, the silicon-to-aluminum ratio of the samples obtained in each embodiment is significantly improved compared with that of Comparative Example 1, indicating that the degree of dealuminization of the molecular sieve is closely related to the sodium content. When sodium ions decrease, the degree of dealuminization is deepened during hydrothermal treatment.

[0052] The nitrogen adsorption isotherms of the samples obtained in the above embodiments were determined by BET comparative area measurement, and the results are shown in Table 3:

[0053] Table 3 - Specific surface area of ​​samples obtained in each embodiment

[0054] Sample number <![CDATA[S BET / (m 2 ·g -1 )]]> 13x-JH0 657.3 13x-JH1 642.1 13x-JH2 621.5 13x-JH3 598.2 13x-JH4 638.1 13x-JH5 610.3

[0055] As can be seen above, after modification, the specific surface area of ​​the samples obtained in each embodiment is slightly lower than that of the sample obtained in Comparative Example 1. This is because during the high-temperature hydrothermal treatment, the dealuminization of the skeleton will cause some of the channels to collapse, but the reduction is controlled within 0.1%.

[0056] Dynamic CO2 adsorption performance of the samples obtained in each embodiment was determined using a fixed adsorption bed. The simulated flue gas was heated to 50°C, with a humidity of 40% RH, and the remaining components were 1% CO2 / 99% N2. The test results are attached. Figure 1As shown.

[0057] Through append Figure 1 It can be seen that, at 40% RH humidity, the 13x-JH0 obtained in Comparative Example 1 without ion exchange and high-temperature hydrothermal treatment had a CO2 adsorption capacity of only 0.39 mmol / g; the 13x-JH1 obtained in Example 1 with a single ion exchange had an adsorption capacity of 0.52 mmol / g, which is more than 30% higher than that of the sample in Comparative Example 1; the 13x-JH2, 13x-JH3, 13x-JH4, and 13x-JH5 obtained in Examples 2, 3, 4, and 5 with two and three ion exchanges had an adsorption capacity of 0.58 mmol / g, which is 50% higher than that of the sample in Comparative Example 1, and the modified 13x-JH1, 13x-JH2, and 13x-JH3 samples had longer breakthrough times, indicating better CO2 adsorption performance. In summary, the 13x modified molecular sieve prepared by the ion exchange and high-temperature hydrothermal treatment in the preparation method of the modified 13x molecular sieve of this invention can effectively improve the CO2 capture performance in humid flue gas.

[0058] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing modified 13x molecular sieve, characterized in that, Includes the following steps: S1. Add ammonium ion solution to the 13x molecular sieve sample to cover the sample, and heat at 80-100℃ for 1-3 hours to carry out ion exchange to obtain the intermediate. S2. Take the intermediate obtained in step S1, soak and wash it in deionized water, dry it at 120°C, and then calcine it at 550°C for 2-3 hours to obtain the ion exchange sample. S3. Take the ion exchange sample obtained in step S2, pass argon gas through it for 20-30 minutes, calcine it to 600-700℃, and then treat it with deionized water for 6-8 hours. After cooling it to 80℃, take it out to obtain 13x modified molecular sieve.

2. The method for preparing a modified 13x molecular sieve as described in claim 1, characterized in that, In step S1, the concentration of ammonium ion solution is 0.5-1.5 mol / L.

3. The method for preparing a modified 13x molecular sieve as described in claim 1, characterized in that, The ammonium ion solution mentioned in step S1 is one or a combination of ammonium sulfate, ammonium chloride, or ammonium nitrate.

4. The method for preparing a modified 13x molecular sieve as described in claim 1, characterized in that, The ion exchange sample obtained in step S2 is subjected to the soaking, washing, drying, and calcination steps 0-2 times.

5. The method for preparing a modified 13x molecular sieve as described in claim 1, characterized in that, In step S3, the ion exchange sample is placed in a tube furnace, and during calcination, the temperature in the tube furnace is increased to 600-700℃ at a rate of 3-5℃ / min.

6. The method for preparing a modified 13x molecular sieve as described in claim 1, characterized in that, In step S3, the deionized water is added at a rate of 10-30 drops / min.

7. The application of the modified 13x molecular sieve prepared by any one of claims 1-6 for CO2 adsorption and capture in a humid environment.

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