13X molecular sieve adsorbent for removing CO2 as well as preparation method and application of 13X molecular sieve adsorbent

Abstract

The invention belongs to the technical field of preparation of adsorption materials, and relates to a 13X molecular sieve adsorbent for removing CO2 as well as a preparation method and application of the 13X molecular sieve adsorbent. The preparation method comprises the following steps: firstly, soaking clay powder in an acid solution, and carrying out filter pressing to obtain a clay filter cake; then, mixing the high-silica-alumina-ratio 13X molecular sieve, the clay filter cake and a pore-forming agent, granulating and forming, and drying and roasting to obtain the spherical high-silica-alumina-ratio 13X molecular sieve adsorbent with the particle size of 1.6-2.4 mm, and finally, treating the 13X molecular sieve adsorbent with the high silica-alumina ratio in a caustic alkali solution, washing, drying and roasting to obtain the efficient 13X molecular sieve adsorbent for removing CO2. According to the method, one-step aluminizing-directional crystal transformation is realized, and the prepared 13X molecular sieve adsorbent has higher CO2 adsorption capacity and is suitable for efficient removal of trace CO2 in air separation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adsorbent material preparation, and relates to a 13X molecular sieve adsorbent for removing CO2 and a preparation method and application thereof. BACKGROUND

[0002] In the field of cryogenic air separation, granular low-silicon-to-aluminum ratio 13X molecular sieve adsorbent is generally used in industry to remove trace amounts of CO2 contained in air. At present, there are mainly two technical routes for preparing spherical low-silicon-to-aluminum ratio 13X molecular sieve adsorbent. The first route is to first synthesize low-silicon-to-aluminum ratio 13X molecular sieve raw powder, and then mix the powder-shaped molecular sieve with inorganic binder and the like and shape into spherical adsorbent. This method has a relatively limited CO2 adsorption performance of the adsorbent due to a high content of inorganic binder; meanwhile, the additional low-silicon-to-aluminum ratio raw powder synthesis step not only increases the process complexity and length, but also produces a large amount of wastewater due to multiple washing steps. The second route directly uses the already shaped spherical high-silicon-to-aluminum ratio 13X molecular sieve adsorbent, which is converted into a low-silicon-to-aluminum ratio product by alkali treatment. In comparison, this route eliminates the independent low-silicon-to-aluminum ratio 13X molecular sieve raw powder synthesis link, significantly shortens the process flow, and fundamentally reduces the amount of wastewater generated. Meanwhile, the prepared adsorbent has a low inorganic clay content and a high CO2 adsorption capacity. However, the existing preparation process based on spherical high-silicon-to-aluminum ratio 13X molecular sieve adsorbent still has certain limitations: on the one hand, it needs to go through two steps of “alkali conversion-aluminization”, and has many process steps; on the other hand, the inorganic clay used for shaping needs to be converted into active metakaolin by high-temperature calcination, which not only significantly increases the complexity and operation intensity of the process, but also leads to a substantial increase in overall energy consumption and production cost.

[0003] Patent CN112408415A discloses a granular low-silicon 13X molecular sieve and a preparation method and application thereof, and the preparation method comprises the following steps: 1) shaping: mixing common-silicon 13X molecular sieve, inorganic binder and pore-forming agent, and then shaping, and then drying and calcining to obtain granular 13X molecular sieve; 2) alkali conversion: alkali treatment of the granular 13X molecular sieve by using an alkaline solution of sodium silicate, and then liquid-solid separation and drying to obtain the alkali-treated granular 13X molecular sieve; and 3) aluminization: immersing the alkali-treated granular 13X molecular sieve into a high-alkalinity sodium aluminate solution for conversion treatment, and then washing, drying and activating. However, this method has obvious defects: the alkali conversion and aluminization processes are carried out independently in two steps, which leads to a long overall preparation process, increases the comprehensive production cost, and greatly reduces the industrialization conversion feasibility of the process.

[0004] Driven by the goal of carbon neutrality, air separation technology is innovating towards higher efficiency and lower carbon emissions, and process flows are accelerating their comprehensive upgrade towards energy conservation and intelligentization. Against this backdrop, the development of more advanced and environmentally friendly low-silicon-to-aluminum ratio 13X molecular sieve adsorbent products and related preparation processes, as key adsorption materials in the air separation field, has become an urgent industry need. Based on this market demand, there is an urgent need to develop a high-efficiency 13X molecular sieve adsorbent preparation method for CO2 removal with a simple process flow and low production cost to meet the technological upgrading needs of the air separation industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a 13X molecular sieve adsorbent for CO2 removal, its preparation method and application.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a 13X molecular sieve adsorbent for CO2 removal includes the following steps: 1) Clay pretreatment: Clay powder is soaked in an acid solution and then filtered to obtain a clay filter cake; 2) Granulation: The high silica-to-alumina ratio 13X molecular sieve, the clay filter cake obtained in step 1), and the pore-forming agent are mixed and granulated. After drying and calcination, spherical high silica-to-alumina ratio 13X molecular sieve adsorbent is obtained. The particle size of the spherical high silica-to-alumina ratio 13X molecular sieve adsorbent is 1.6~2.4 mm. 3) Aluminization and crystal transformation: The spherical high silicon-to-aluminum ratio 13X molecular sieve adsorbent obtained in step 2) is placed in a caustic alkali solution for treatment, followed by washing, drying and calcination to obtain a 13X molecular sieve adsorbent for CO2 removal.

[0007] Further, the clay mentioned in step 1) is selected from one or more of the following: lime clay, white clay, attapulgite, shale clay, bentonite, halloysite, or argillaceous clay, and the Fe content (calculated as Fe2O3) in the clay is ≤3.0 wt%.

[0008] Preferably, the clay is selected from one or both of halloysite and argillaceous clay.

[0009] Further, in step 1), the acid solution is a hydrochloric acid solution with a mass concentration of 0.005~0.5%; the soaking treatment is carried out by continuous stirring at room temperature to 80°C for 2~24 h; and the water content of the clay filter cake is 40~55%.

[0010] Further, in step 2), the silica-alumina ratio of the high silica-alumina ratio 13X molecular sieve is 2.6~3.0; the pore-forming agent is selected from one or more of methylcellulose, carboxyethylcellulose, maltodextrin or starch; the mass ratio of the high silica-alumina ratio 13X molecular sieve to the clay filter cake is (75~90):(10~25), and the mass of the pore-forming agent is 1~5% of the total mass of the high silica-alumina ratio 13X molecular sieve and the clay filter cake; the granulation is carried out using a high-speed granulator.

[0011] Further, in step 2), the drying conditions are drying at 100~180℃ for 2~8 h; the calcination conditions are calcination at 500~650℃ for 1~6 h.

[0012] Further, in step 3), the caustic alkali solution contains K. + Na + OH - And aluminate ions ([Al(OH)4]) - An aqueous solution system of ); wherein, n (K) in the solution + ) / (n (K + )+n (Na + The molar ratio is 0.02~0.4, and the molar ratio of total alkali metal oxides to aluminum oxide, n(K2O + Na2O) / n(Al2O3), is 2~6 (where, according to the law of conservation of elements, n(K2O) = n(K2O)). + ) / 2、n (Na2O)=n (Na + ) / 2、n (Al2O3)=n ([Al(OH)4] - ) / 2).

[0013] In the caustic alkali solution, the total concentration of alkali metal hydroxides (expressed as OH⁻) - The concentration (calculated) is 2~10 mol / L; The aluminum component in the solution is introduced by dissolving aluminum hydroxide in an aqueous solution of KOH and / or NaOH; the aluminum hydroxide is ordinary aluminum hydroxide or high-whiteness aluminum hydroxide; The content of silicon (Si), an impurity element, in the caustic alkali solution is no greater than 0.5 mol / L.

[0014] Further, in step 3), the mass ratio of the spherical high silica-alumina ratio 13X molecular sieve adsorbent to the caustic alkali solution is 1:(1.2~5).

[0015] Further, the aluminization and crystallization treatment conditions in step 3) are as follows: first, treatment at 20~50℃ for 6~36 h, then treatment at 60~100℃ for 4~24 h; the washing step includes washing the treated molecular sieve until the pH value of the washing liquid or filter cake is 9~10; the drying step is at a temperature of 100~150℃ and a drying time of 2~8 hours; the calcination step is at a temperature of 400~600℃ and a calcination time of 2~6 hours.

[0016] The present invention also provides a 13X molecular sieve adsorbent for CO2 removal, which is prepared by the method described in any of the preceding claims.

[0017] The adsorbent does not contain type A molecular sieves or sodalite-type molecular sieve impurities (SOD impurities), and the molecular sieve crystal phase it contains is only type 13X molecular sieve; the silica-alumina molar ratio of the adsorbent is 1.9~2.1, and the strength of a single particle is not less than 30 N; under the conditions of 25℃ and 2.5 mmHg, the static CO2 adsorption capacity of the adsorbent is not less than 8.0 wt%; under the conditions of 25℃ and 250 mmHg, the static CO2 adsorption capacity of the adsorbent is not less than 23.0 wt%.

[0018] The present invention also provides an application of the 13X molecular sieve adsorbent for CO2 removal as described above, which can be used for the efficient removal of trace amounts of CO2 in cryogenic air separation.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) Unlike the traditional stepwise aluminization and alkaline crystal conversion, this invention achieves one-step aluminization-directional crystal conversion, which can aluminize 13X molecular sieves with high silicon-to-aluminum ratio into 13X molecular sieves with low silicon-to-aluminum ratio, and can simultaneously convert uncalcined inorganic clay into 13X molecular sieves. This avoids the high-temperature calcination process, simplifies the process flow, reduces manufacturing costs, and helps downstream air separation fields achieve a lower carbon and more economical green upgrade.

[0020] (2) This invention achieves efficient and directional conversion of clay to 13X molecular sieves by precisely controlling the silicon-to-aluminum ratio of the system through the synergistic effect of acid treatment and mixed caustic alkali solution. Acid treatment selectively dissolves aluminum in the clay, increasing its silicon content; simultaneously, this process weakens the silicon-oxygen bonds in the inorganic clay, creating conditions for the efficient release of silicon oxide in subsequent alkali treatment. The mixed caustic alkali solution introducing potassium ions enables the directional and controllable breaking of silicon-oxygen bonds in the clay, achieving efficient and selective dissolution of silicon oxide from the acid-treated clay, providing a precise silicon-to-aluminum source ratio for the synthesis of 13X molecular sieves. Simultaneously, the guiding effect of potassium ions causes the clay to directionally transform into 13X molecular sieves, suppressing the formation of impurities such as type A and sodalite (SOD), ensuring the purity of the product's crystalline phase. Compared to traditional transformation processes requiring high-temperature calcination (e.g., conversion to metakaolin), this invention directly transforms uncalcined clay in situ, avoiding high-energy-consuming steps and significantly reducing overall energy consumption.

[0021] (3) The present invention uses a high-speed granulator to form spherical adsorbents. Compared with traditional methods such as drum granulation, sugar coating machine granulation or disc granulation, the production efficiency is increased by more than 30%, which is more suitable for the needs of large-scale production.

[0022] (4) Compared with existing 13X molecular sieve adsorbents, the 13X molecular sieve adsorbent prepared by this invention does not contain impurities such as type A and SOD, and has a higher CO2 adsorption capacity. The static CO2 adsorption capacity of the obtained 13X molecular sieve adsorbent is ≥8.0 wt% at 25℃ and 2.5 mmHg, and ≥23.0 wt% at 25℃ and 250 mmHg. Under the same filling volume, this invention can significantly extend the service life and shorten the regeneration frequency, resulting in a lower overall cost. Attached Figure Description

[0023] Figure 1 The XRD pattern of the low-silica 13X molecular sieve adsorbent prepared in Example 1; Figure 2 The image shows the SEM image of the low-silica 13X molecular sieve adsorbent prepared in Example 1. Figure 3 The XRD pattern of the low-silica 13X molecular sieve adsorbent prepared in Example 2; Figure 4 The image shows the SEM image of the low-silica 13X molecular sieve adsorbent prepared in Example 2. Figure 5 The XRD pattern of the molecular sieve adsorbent prepared in Comparative Example 1 is shown. Figure 6 The image shows the SEM image of the molecular sieve adsorbent prepared in Comparative Example 1. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0025] Unless otherwise specified, the raw materials or processing techniques used in the following embodiments and comparative examples are conventional commercially available raw materials or conventional processing techniques in the art.

[0026] Example 1 A 13X molecular sieve adsorbent for CO2 removal is prepared using the following steps: 1) Clay pretreatment: Halloysite with Fe content (calculated as Fe2O3) ≤ 3.0 wt% was placed in hydrochloric acid with a mass concentration of 0.1% and stirred continuously for 12 h at room temperature. After pressure filtration, a clay filter cake with a water content of 40% was obtained.

[0027] 2) Granulation and molding: Weigh high-silicon-aluminum ratio 13X molecular sieve and clay filter cake at a dry basis mass ratio of 90:10, and add 3% maltodextrin as a pore-forming agent, accounting for 3% of the total mass of the high-silicon-aluminum ratio 13X molecular sieve and clay filter cake. After mixing the above materials evenly, use water as a liquid binder and granulate using a high-speed granulator. After granulation, dry at 120℃ for 5 h to obtain a semi-finished product of low-silicon 13X molecular sieve adsorbent with a particle size of 1.6~2.4 mm. Place the semi-finished product in an atmosphere furnace, introduce a gas with an oxygen content of 50%, raise the temperature to 550℃ at 5℃ / min, and calcine at this temperature for 4 h to obtain spherical high-silicon-aluminum ratio 13X molecular sieve adsorbent with a particle size of 1.6~2.4 mm.

[0028] 3) Aluminization and Crystallization: Spherical high-silicon-to-aluminum ratio 13X molecular sieve adsorbents are placed in a caustic alkaline solution at a mass ratio of 1:3; in this caustic alkaline solution, n (K + ) / (n (K + )+n (Na + The molar ratio is 0.3, the molar ratio of n(K2O + Na2O) / n(Al2O3) is 5, and the total concentration of alkali metal hydroxides (in OH groups) is... - The concentration of the molecular sieve was 4 mol / L. After the system was mixed evenly, it was transferred to a reaction vessel and heated at 50°C for 10 h. Then, the temperature was rapidly increased to 80°C and heated for another 10 h. After the reaction was completed, the molecular sieve particles were removed and washed until the pH of the system was 9-10. The system was then dried at 120°C for 6 h and calcined at 500°C for 4 h to obtain 13X molecular sieve adsorbent for CO2 removal.

[0029] Comparative Example 1 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner that is basically the same as in Example 1, except that the clay pretreatment step (step 1) is omitted. Halloysite clay with the same specifications as the raw materials in Example 1 (Fe content ≤ 3.0 wt% based on Fe2O3) is directly selected. There is no need for stirring at room temperature for 12 h with 0.1% hydrochloric acid and pressure filtration. The untreated halloysite clay and the high silica-alumina ratio 13X molecular sieve are weighed directly at a dry basis mass ratio of 90:10.

[0030] Example 2 A 13X molecular sieve adsorbent for CO2 removal is prepared using the following steps: 1) Clay pretreatment: Halloysite with Fe content (calculated as Fe2O3) ≤ 3.0 wt% was placed in hydrochloric acid with a mass concentration of 0.1% and stirred continuously for 12 h at room temperature. After pressure filtration, a clay filter cake with a water content of 40% was obtained.

[0031] 2) Granulation and molding: Weigh high-silicon-aluminum ratio 13X molecular sieve and clay filter cake at a dry basis mass ratio of 85:15, and add 3% maltodextrin as a pore-forming agent as the total mass of the high-silicon-aluminum ratio 13X molecular sieve and clay filter cake. After mixing the above materials evenly, use water as a liquid binder and granulate using a high-speed granulator. After granulation, dry at 120℃ for 5 h to obtain a semi-finished product of low-silicon 13X molecular sieve adsorbent with a particle size of 1.6~2.4 mm. Place the semi-finished product in an atmosphere furnace, introduce a gas with an oxygen content of 50%, raise the temperature to 550℃ at 5℃ / min, and calcine at this temperature for 4 h to obtain spherical high-silicon-aluminum ratio 13X molecular sieve adsorbent with a particle size of 1.6~2.4 mm.

[0032] 3) Aluminization and Crystallization: Spherical high-silicon-to-aluminum ratio 13X molecular sieve adsorbents are placed in a caustic alkaline solution at a mass ratio of 1:3; in this caustic alkaline solution, n (K + ) / (n (K + )+n (Na + The molar ratio is 0.3, the molar ratio of n(K2O + Na2O) / n(Al2O3) is 5, and the total concentration of alkali metal hydroxides (in OH groups) is... - The concentration of the molecular sieve was 4 mol / L. After the system was mixed evenly, it was transferred to a reaction vessel and heated at 50°C for 10 h. Then, the temperature was rapidly increased to 80°C and heated for another 10 h. After the reaction was completed, the molecular sieve particles were removed and washed until the pH of the system was 9-10. The system was then dried at 120°C for 6 h and calcined at 500°C for 4 h to obtain 13X molecular sieve adsorbent for CO2 removal.

[0033] Comparative Example 2 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner essentially the same as in Example 2, except that in step 3), the caustic alkali solution contains only Na+ ions. + The molar ratio of n(Na2O) / n(Al2O3) is 5, and the total concentration of alkali metal hydroxides (in OH groups) is... - The concentration (calculated) is 4 mol / L.

[0034] Example 3 A 13X molecular sieve adsorbent for CO2 removal is prepared using the following steps: 1) Clay pretreatment: Halloysite with Fe content (calculated as Fe2O3) ≤ 3.0 wt% was placed in hydrochloric acid with a mass concentration of 0.1% and stirred continuously for 12 h at room temperature. After pressure filtration, a clay filter cake with a water content of 40% was obtained.

[0035] 2) Granulation and molding: Weigh high-silicon-aluminum ratio 13X molecular sieve and clay filter cake at a dry basis mass ratio of 80:20, and add 3% maltodextrin as a pore-forming agent as the total mass of the high-silicon-aluminum ratio 13X molecular sieve and clay filter cake. After mixing the above materials evenly, use water as a liquid binder and granulate using a high-speed granulator. After granulation, dry at 120℃ for 5 h to obtain a semi-finished product of low-silicon 13X molecular sieve adsorbent with a particle size of 1.6~2.4 mm. Place the semi-finished product in an atmosphere furnace, introduce a gas with an oxygen content of 50%, raise the temperature to 550℃ at 5℃ / min, and calcine at this temperature for 4 h to obtain spherical high-silicon-aluminum ratio 13X molecular sieve adsorbent with a particle size of 1.6~2.4 mm.

[0036] 3) Aluminization and Crystallization: Spherical high-silicon-to-aluminum ratio 13X molecular sieve adsorbents are placed in a caustic alkaline solution at a mass ratio of 1:3; in this caustic alkaline solution, n (K + ) / (n (K + )+n (Na + The molar ratio is 0.3, the molar ratio of n(K2O + Na2O) / n(Al2O3) is 5, and the total concentration of alkali metal hydroxides (in OH groups) is... - The concentration of the molecular sieve was 4 mol / L. After the system was mixed evenly, it was transferred to a reaction vessel and heated at 50°C for 10 h. Then, the temperature was rapidly increased to 80°C and heated for another 10 h. After the reaction was completed, the molecular sieve particles were removed and washed until the pH of the system was 9-10. The system was then dried at 120°C for 6 h and calcined at 500°C for 4 h to obtain 13X molecular sieve adsorbent for CO2 removal.

[0037] Comparative Example 3 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner that is basically the same as in Example 3, except that in step 2), granulation is performed using roller granulation.

[0038] Example 4 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner that is basically the same as in Example 1, except that in step 1), a clay with an Fe content (calculated as Fe2O3) ≤ 3.0 wt% is placed in hydrochloric acid with a mass concentration of 0.1%.

[0039] Example 5 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner that is basically the same as in Example 1, except that in step 3), the molar ratio of n(K2O + Na2O) / n(Al2O3) in the caustic alkali solution is 6.

[0040] Example 6 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner essentially the same as in Example 1, except that in step 3), the total alkali metal hydroxide concentration (expressed as OH⁻) in the caustic alkali solution is... - The concentration (calculated) is 2 mol / L.

[0041] Example 7 A 13X molecular sieve adsorbent for CO2 removal is prepared in a manner essentially the same as in Example 1, except that in step 3), the total alkali metal hydroxide concentration (expressed as OH⁻) in the caustic alkali solution is... - The concentration (calculated) is 6 mol / L.

[0042] The following performance tests were conducted on the 13X molecular sieve adsorbents prepared in Examples 1-7 and Comparative Examples 1-3: Phase analysis and 13X molecular sieve proportion: X-ray diffraction (XRD) was used for testing. An X-ray diffractometer was used with CuKα as the radiation source, the scanning range was 2θ=3~60°, and the scanning rate was 5° / min. The characteristic peaks in the diffraction pattern were used to determine whether the sample was a pure phase of 13X molecular sieve. At the same time, the mass proportion (%) of 13X molecular sieve in the sample was calculated using the XRD results.

[0043] Crystal morphology: The microscopic crystal morphology of the samples was observed using scanning electron microscopy (SEM) with a German ZEISS GeminiSEM 300 instrument.

[0044] Strength: The single-particle compressive strength test method is adopted. Using a particle compressive strength tester, select the molecular sieve particles to be tested, apply axial pressure to each particle until it breaks, and record the pressure value at the time of breakage (unit: N); at least 20 particles are tested, and the average value of the test results is taken as the strength of the sample (N / particle).

[0045] SiO2 / Al2O3: After the sample is digested, the contents of Si and Al elements in the sample are determined by X-ray fluorescence spectroscopy (XRF), and then converted into the mass of SiO2 and Al2O3 respectively. Finally, the ratio of SiO2 to Al2O3 is calculated.

[0046] CO2 adsorption performance: The CO2 adsorption performance of the samples was tested using a Micromeritics ASAP 2020 HD88 physical adsorption instrument. The samples were degassed and activated under vacuum at 420℃ for 4 hours. After the samples were cooled to 25℃, CO2 was introduced to pressures of 2.5 mmHg and 250 mmHg, respectively. After adsorption reached equilibrium, the amount of CO2 adsorbed by the samples was recorded and converted into a mass percentage (wt%), which is the CO2 adsorption performance data under the corresponding conditions.

[0047] Table 1. Main indicators and performance data of the adsorbents prepared in Examples 1-7 and Comparative Examples 1-3 Table 1 lists the main indicators and performance data of the 13X molecular sieve adsorbents prepared in Examples 1-7 and Comparative Examples 1-3.

[0048] As shown in the table, the adsorbents prepared in Examples 1-7 of this invention are all pure-phase 13X molecular sieves, accounting for 96.2%-97.4% of the total composition, with a silicon-to-aluminum ratio of 1.90-1.99. XRD analysis revealed no characteristic peaks of type A or SOD impurities in the spectra of all the sample samples, and SEM analysis also failed to observe the corresponding crystal morphology of the impurities. Taking Examples 1 and 2 as examples... Figure 1 , Figure 3 The XRD pattern shown and Figure 2 , Figure 4 The SEM images shown all confirm that, through the synergistic effect of acid treatment and mixed caustic alkali solution, an adsorbent product containing only 13X molecular sieve has been successfully prepared using a one-step aluminization-crystallization method.

[0049] Comparative Example 1: The clay was not acid-treated; the adsorbent was prepared solely via a one-step aluminization-crystallization method. XRD results (e.g.) Figure 5 As shown in the figure, the product contains obvious A-type impurity crystal characteristic peaks; SEM testing (as shown in the figure) indicates the presence of these peaks. Figure 6 As shown in the figure, a large number of characteristic crystal morphologies of type A molecular sieves were also observed, confirming that a pure-phase 13X molecular sieve product was not obtained. The above characterization results indicate that without acid treatment of the clay, it is impossible to prepare an adsorbent product containing only 13X molecular sieve using only a one-step aluminization-crystallization method. Furthermore, the silica-alumina ratio of the adsorbent in Comparative Example 1 is relatively high.

[0050] The alkali metal ions in the caustic alkali solution used in Comparative Example 2 consisted only of Na. +K-free + The prepared adsorbent also showed obvious A-type impurities; further SEM analysis also revealed a large number of A-type molecular sieve crystals. Combining the XRD and SEM results, it can be seen that the composition of alkali metal ions in the caustic alkali solution has a significant impact on the purity of the adsorbent product. When the alkali metal ion content is only Na... + And without K + At this point, the guiding effect weakens, making it impossible to prepare an adsorbent product containing only 13X molecular sieve. Additionally, the silica-alumina ratio of the adsorbent in Comparative Example 2 is relatively high.

[0051] The CO2 adsorption performance and mechanical strength test results are shown in Table 1. The adsorbents prepared in Examples 1 to 7 of this invention exhibit excellent CO2 adsorption performance. Under the conditions of 2.5 mmHg and 25℃, the static CO2 adsorption capacity is 8.15~8.34 wt%; under the conditions of 250 mmHg and 25℃, the static CO2 adsorption capacity reaches 23.12~23.28 wt%. At the same time, they have good mechanical strength, with a strength range of 30.7~32.4 N / particle.

[0052] In comparison, the adsorbent of Comparative Example 1 exhibited a static CO2 adsorption capacity of 7.23 wt% at 2.5 mmHg and 25°C, and 21.89 wt% at 250 mmHg and 25°C, with a mechanical strength of 31.8 N / particle. The adsorbent of Comparative Example 2 showed a static CO2 adsorption capacity of 7.45 wt% at 2.5 mmHg and 25°C, and 21.97 wt% at 250 mmHg and 25°C, with a mechanical strength of 31.4 N / particle. Clearly, the static CO2 adsorption performance of Comparative Example 1 and Comparative Example 2 is significantly inferior to the products of Examples 1-7 of this invention.

[0053] The preparation process of Comparative Example 3 is basically the same as that of Example 3 of the present invention, except for the granulation method: Comparative Example 3 uses drum granulation, while Example 3 uses a high-speed granulator. The product performance of the two is basically the same, but the yield of Comparative Example 3 is about 30% lower than that of Example 3.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for the preparation of a 13X molecular sieve adsorbent for the removal of CO2, characterized in that, The method comprises the following steps: 1) clay pretreatment: clay powder is soaked in an acid solution, filtered, and a clay filter cake is obtained; 2) granulation and molding: high-silicon aluminum ratio 13X molecular sieve, the clay filter cake obtained in step 1) and a pore-forming agent are mixed and granulated and molded, and after drying and calcination, spherical high-silicon aluminum ratio 13X molecular sieve adsorbent is obtained; 3) aluminizing and crystallization transformation: the spherical high-silicon aluminum ratio 13X molecular sieve adsorbent obtained in step 2) is treated in a caustic soda solution, and then washed, dried and calcined to obtain 13X molecular sieve adsorbent for removing CO2.

2. The method of claim 1, wherein the 13X molecular sieve adsorbent is prepared by the steps of: The clay in step 1) is selected from one or more of the following: clay, white clay, attapulgite, rod clay, bentonite, halloysite or kaolin.

3. The method of claim 1, wherein the 13X molecular sieve adsorbent is prepared by the steps of: In step 1), the acid solution is a hydrochloric acid solution with a mass concentration of 0.005-0.5%; the soaking treatment is continuous stirring at room temperature-80°C for 2-24 h; and the water content of the clay filter cake is 40-55%.

4. The method of claim 1, wherein the 13X molecular sieve adsorbent is prepared by the steps of: In step 2), the high-silicon aluminum ratio 13X molecular sieve has a silicon aluminum ratio of 2.6-3.0; the pore-forming agent is selected from one or more of the following: methyl cellulose, carboxyethyl cellulose, malt dextrin or starch; the mass ratio of the high-silicon aluminum ratio 13X molecular sieve to the clay filter cake is (75-90):(10-25), and the mass of the pore-forming agent is 1-5% of the total mass of the high-silicon aluminum ratio 13X molecular sieve and the clay filter cake.

5. The method for preparing a 13X molecular sieve adsorbent for CO2 removal according to claim 1, characterized in that, In step 2), the drying conditions are 100-180°C for 2-8 h, and the calcination conditions are 500-650°C for 1-6 h.

6. The method of claim 1, wherein the 13X molecular sieve adsorbent is prepared by the steps of: In step 3), the caustic solution is an aqueous solution system comprising K + , Na + , OH - , and aluminate ions ([Al(OH)4] - ); wherein the molar ratio of n (K + ) / (n (K + ) + n (Na + )) in the solution is 0.02 to 0.4, and the molar ratio of total alkali metal oxide to aluminum oxide n (K2O + Na2O) / n (Al2O3) is 2 to 6.

7. The method for preparing a 13X molecular sieve adsorbent for CO2 removal according to claim 1, characterized in that, In step 3), the mass ratio of the spherical high-silicon aluminum ratio 13X molecular sieve adsorbent to the caustic soda solution is 1:(1.2-5).

8. The method for preparing a 13X molecular sieve adsorbent for CO2 removal according to claim 1, characterized in that, In step 3), the aluminizing and crystallization transformation treatment conditions are: first at 20-50°C for 6-36 h, and then at 60-100°C for 4-24 h; the washing step includes washing the treated molecular sieve to a pH value of 9-10 of the washing liquid or filter cake; the drying step is at a temperature of 100-150°C for 2-8 h; and the calcination step is at a temperature of 400-600°C for 2-6 h.

9. A 13X molecular sieve adsorbent for the removal of CO2, characterized in that, The 13X molecular sieve adsorbent for removing CO2 is prepared by the method according to any one of claims 1-8.

10. Use of a 13X molecular sieve adsorbent according to claim 9 for the removal of CO2, characterized in that, The adsorbent can be used for efficient removal of trace CO2 in cryogenic air separation.

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