MCM-41 molecular sieve prepared by using coal gasification slag rich silicon component and preparation method and application thereof

Abstract

The application discloses MCM-41 molecular sieve prepared by using a coal gasification slag rich silicon component, a preparation method and application thereof, relates to the technical field of industrial solid waste resource utilization, and effectively solves the problems of low comprehensive utilization rate of the coal gasification slag, waste of residual carbon resources, decline of molecular sieve crystallinity and mesoporous structure blockage caused by metal impurities, and limited cationic dye adsorption capacity in the prior art, realizes organic combination of high-value utilization of solid waste and wastewater treatment, and realizes preliminary separation and graded quality utilization of carbon silicon components through particle size separation of the gasification slag by a cyclone separator, and then separates magnetic oxides by a high gradient magnetic separator, so that the adverse effects of metal impurities on subsequent molecular sieve synthesis are reduced, the product performance is improved, and efficient resource recovery and environmental protection benefits are realized.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, specifically to an MCM-41 molecular sieve prepared using silicon-rich components from coal gasification slag, its preparation method, and its application. Background Technology

[0002] Coal gasification, a key technology for achieving clean and efficient coal utilization, generates a large amount of coal gasification slag while promoting efficient coal conversion. Currently, the comprehensive utilization rate of coal gasification slag is low, and its disposal methods still mainly involve stockpiling and landfilling, which not only wastes resources but also poses certain environmental risks. Meanwhile, the pollution situation of dye wastewater is becoming increasingly serious. Rhodamine B, as a typical cationic dye pollutant, has high toxicity, carcinogenicity, and is not easily biodegradable, urgently requiring the development of economical and efficient treatment technologies. Coal gasification slag typically contains a certain amount of carbon, has irregular particle morphology, and a well-developed porous structure. Its ash is rich in inorganic minerals such as silicates and aluminosilicates. Against this backdrop, using coal gasification slag as a precursor to prepare wastewater purification functional materials aims to achieve the green circular goal of "treating waste with waste," providing a new path for the high-value utilization of coal gasification slag and wastewater treatment.

[0003] MCM-41 molecular sieves are widely used in adsorption, catalysis and other fields due to their highly ordered pore structure, high specific surface area and good hydrothermal and chemical stability. Using coal gasification slag as a low-cost silicon source to replace expensive chemical reagents such as tetraethyl orthosilicate in the synthesis of MCM-41 not only realizes the high-value utilization of solid waste, but also significantly reduces the cost of molecular sieve preparation. However, the existing technology faces key bottlenecks: (1) The residual carbon in coal gasification slag is not effectively utilized in the traditional MCM-41 synthesis process. It is usually removed as an impurity in the pretreatment stage, resulting in the waste of carbon resources and increased acid and alkali consumption. (2) Metal impurities (Fe, Mg, Ca, etc.) in coal gasification slag are easily doped into the MCM-41 framework, leading to a decrease in the crystallinity of the molecular sieve and blockage of the mesoporous structure. (3) Most reported MCM-41 adsorption of cationic dyes (such as Rhodamine B) mainly relies on electrostatic attraction. The adsorption sites are limited, and there is still a large room for improvement in adsorption capacity. Moreover, there is a lack of effective control over adsorption selectivity.

[0004] Therefore, developing an MCM-41 molecular sieve prepared using silicon-rich components from coal gasification slag, along with its preparation method and applications, can not only achieve efficient extraction of silicon sources, synergistic utilization of residual carbon, and significant improvement in adsorption performance, but also reduce process energy consumption and chemical consumption, thus becoming a pressing technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides an MCM-41 molecular sieve prepared using silicon-rich components from coal gasification slag, its preparation method, and its applications.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for preparing MCM-41 molecular sieve using silicon-rich components from coal gasification slag is provided, comprising the following steps: S1: Pre-treat the coal gasification slag to obtain the silicon-rich components in the coal gasification slag; S2: The silicon-rich components are pickled using hydrochloric acid solution; S3: Wash the acid washing product with deionized water until the waste liquid is neutral, filter it dry, and then put it into sodium hydroxide solution for stirring reaction. After the reaction is completed, filter the liquid to obtain Na2SiO3 enriched solution. S4: After mixing the Na2SiO3 enrichment solution with hexadecyltrimethylammonium bromide and water, stir the reaction at room temperature, adjust the pH value to 5.5~10.5 with acetic acid, and continue stirring the reaction. S5: The reaction system obtained in step S4 is subjected to hydrothermal crystallization reaction in a high-temperature and high-pressure hydrothermal reactor. After the reaction is completed, the solid is filtered out. S6: After washing and drying the filtered solid, calcination yields MCM-41 molecular sieve.

[0007] Furthermore, step S1 specifically includes: S11: Screen the coal gasification slag to remove carbon-rich components and retain the gasification slag; S12: The gasification slag is subjected to magnetic separation to remove the magnetic oxides, and then dried to a moisture content of less than 1%. S13: The dried gasification slag is subjected to physicochemical property testing to screen out the silicon-rich components.

[0008] Further, step S2 specifically involves: adding the silicon-rich component into a hydrochloric acid solution with a mass fraction of 10-25%, stirring and refluxing at 60-100°C for 2-6 hours, and using a heat-treated silicon-rich component to hydrochloric acid solution in a ratio of 1g:10mL.

[0009] Further, step S3 specifically involves: washing the pickling product with deionized water until the waste liquid is neutral, filtering it, adding the filtered pickling product to a sodium hydroxide solution with a concentration of 1~4 mol / L, stirring and refluxing at 60~100℃ for 4~8 h, filtering the liquid to obtain a Na2SiO3 enriched solution, and using a ratio of the filtered pickling product to sodium hydroxide solution of 1 g: 10 mL.

[0010] Further, step S4 specifically involves: determining the molar amount of sodium silicate in the Na2SiO3 enrichment solution, adding hexadecyltrimethylammonium bromide to the Na2SiO3 enrichment solution, and stirring the reaction at room temperature for 3 hours; adjusting the pH value to 5.5~10.5 with acetic acid and continuing to stir the reaction at room temperature for 2 hours. The molar ratio of hexadecyltrimethylammonium bromide to sodium silicate in the Na2SiO3 enrichment solution is 0.1~0.5∶1.0.

[0011] Furthermore, step S5, the hydrothermal crystallization reaction, specifically involves reacting at 80~120℃ for 24~72 hours.

[0012] Further, step S6 specifically involves washing the filtered solid with deionized water until the waste liquid is neutral, drying it at 105°C for 12 hours, and then calcining it in air. The calcination process involves raising the temperature to 550°C at a rate of 2°C / min and calcining for 6 hours.

[0013] The present invention also provides an MCM-41 molecular sieve prepared by the above preparation method.

[0014] This invention also provides a system for preparing MCM-41 molecular sieves using silicon-rich components from coal gasification slag, comprising: a cyclone separator for separating coal gasification slag to obtain coal gasification slag of different particle sizes; a magnetic separator connected to the outlet of the cyclone separator for extracting magnetic oxides from the coal gasification slag of different particle sizes discharged from the cyclone separator; a physicochemical sieving device connected to the outlet of the magnetic separator for detecting the gasification slag discharged from the magnetic separator and sieving out silicon-rich components; an acid washing device connected to the outlet of the physicochemical sieving device for acid treatment of the silicon-rich components to obtain acid-washed products; and an alkaline washing device connected to the outlet of the acid washing device for alkaline treatment of the acid-washed products. The process involves several steps: a washing process to obtain a silica-rich filtrate; a stirring device connected to the outlet of the alkaline washing device to stir the silica-rich filtrate to obtain a mixed solution; a crystallization device connected to the outlet of the stirring device to heat the mixed solution under high temperature and high pressure to obtain a crystallized solution; a filtration device connected to the outlet of the crystallization device to filter and wash the crystallized solution to obtain filter residue; a calcination device connected to the outlet of the filtration device to calcine the filter residue in an air atmosphere to obtain an MCM-41 molecular sieve sample; and a drying device located between the magnetic separation device and the physicochemical sieving device, between the acid washing device and the alkaline washing device, and between the filtration device and the calcination device to dry and remove water from the input product.

[0015] The beneficial effects of this invention are as follows: This invention utilizes coal gasification slag as a low-cost silicon source to prepare MCM-41 molecular sieves, effectively solving key bottleneck problems in existing technologies such as low comprehensive utilization rate of coal gasification slag, waste of residual carbon resources, metal impurities leading to decreased crystallinity and mesoporous blockage of molecular sieves, and limited adsorption capacity of cationic dyes. It achieves an organic combination of high-value utilization of solid waste and wastewater treatment. This invention uses a cyclone separator to perform particle size separation of the gasification slag, achieving preliminary separation and graded utilization of carbon and silicon components. Then, a high-gradient magnetic separator separates magnetic oxides, significantly reducing the adverse effects of metal impurities on subsequent molecular sieve synthesis, improving product performance, and simultaneously achieving efficient resource recovery and enhanced environmental benefits.

[0016] A process combining acid washing, alkali leaching, and hydrothermal synthesis was employed to efficiently extract silicon-rich components from coal gasification slag and synergistically utilize residual carbon resources. This significantly reduced acid and alkali consumption, as well as process energy consumption, thereby lowering the cost of molecular sieve preparation. Under optimized process conditions, the MCM-41 molecular sieve prepared achieved a specific surface area as high as 900 m². 2 / g, with a highly ordered mesoporous structure, exhibits excellent adsorption performance for typical cationic dyes such as Rhodamine B, and can be used as a highly efficient adsorbent for dye wastewater treatment.

[0017] This invention is simple to operate, low in energy consumption and low in cost, and easy to achieve continuous production. It truly achieves the green circular goal of "treating waste with waste" and realizes the reduction, resource utilization and harmless use of coal gasification slag. It has significant economic benefits, environmental benefits and application prospects. Attached Figure Description

[0018] Figure 1 Nitrogen adsorption-desorption isotherms for different MCM-41 molecular sieves in Example 2; Figure 2 Nitrogen adsorption-desorption isotherms for different MCM-41 molecular sieves in Example 3; Figure 3 Nitrogen adsorption-desorption isotherms for different MCM-41 molecular sieves in Example 4; Figure 4 Nitrogen adsorption-desorption isotherms for different MCM-41 molecular sieves in Example 5; Figure 5 Nitrogen adsorption-desorption isotherms for different MCM-41 molecular sieves in Example 6; Figure 6 This is a connection diagram of the first half of the system in Example 7; Figure 7 This is a connection diagram of the latter half of the system in Example 7; The system includes: cyclone separator 1, cyclone inlet 11, gas outlet 12, fly ash outlet 13, magnetic separator 2, magnetic separator inlet 21, magnetic outlet 22, gasified slag outlet 23, physicochemical screening device 3, acid washing device 4, acid inlet 41, acid washing inlet 42, first outlet 43, first product outlet 44, first stirring motor 45, first stirring rod 46, alkali washing device 5, alkali inlet 51, alkali washing inlet 52, second outlet 53, second product outlet 54, second stirring motor 55, second stirring rod 56, stirring device 6, stirring inlet 61, mixing inlet 62, third product outlet 63, third stirring motor 64, third stirring rod 65, crystallization device 7, filtration device 8, filtration inlet 81, washing inlet 82, fourth product outlet 83, third outlet 84, calcination device 9, drying device 10, first dryer 101, second dryer 102, and third dryer 103. Detailed Implementation

[0019] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0020] The embodiments of this invention use gasification slag produced by the fixed-bed coal gasification furnace of Xinjiang Xinyue Energy Chemical Company. Unless otherwise specified, other raw materials used are all commercially available industrial-grade pure materials.

[0021] Example 1 A method for preparing MCM-41 molecular sieve using silicon-rich components from coal gasification slag comprises the following steps: S1: Pre-treat the coal gasification slag by screening it to remove carbon-rich components and retaining the gasification slag; perform magnetic separation on the gasification slag to remove magnetic oxides, and then dry it until the moisture content is below 1%; perform physicochemical property testing on the dried gasification slag to screen out silicon-rich components.

[0022] S2: Add the silicon-rich component to a 15% hydrochloric acid solution and stir and reflux at 80°C for 4 hours. The ratio of the heat-treated silicon-rich component to the hydrochloric acid solution is 1g:10mL.

[0023] In specific implementation, the mass fraction of the hydrochloric acid solution can also be 10%, 12%, 17%, 20%, 22% or 25%; the temperature during the stirring and reflux reaction can also be 60℃, 70℃, 90℃ or 100℃, and the stirring and reflux reaction time can also be 2h, 3h, 5h or 6h.

[0024] S3: Wash the pickling product with deionized water until the waste liquid is neutral, filter it dry, put the filtered pickling product into a sodium hydroxide solution with a concentration of 2 mol / L, stir and reflux at 90℃ for 6 h, filter and take the liquid to obtain Na2SiO3 enriched solution. The ratio of the amount of filtered pickling product to sodium hydroxide solution is 1 g: 10 mL.

[0025] In practice, the concentration of sodium hydroxide solution can be 1 mol / L, 3 mol / L or 4 mol / L; the temperature during stirring and reflux can be 60℃, 70℃, 80℃ or 100℃; and the stirring and reflux reaction time can be 4h, 5h, 7h or 8h.

[0026] S4: Determine the molar amount of sodium silicate in the Na2SiO3 enrichment solution, and add hexadecyltrimethylammonium bromide to the Na2SiO3 enrichment solution. Stir and react at room temperature for 3 hours; adjust the pH value to 5.5~10.5 with acetic acid and continue stirring and reacting at room temperature for 2 hours. The molar ratio of hexadecyltrimethylammonium bromide added to sodium silicate in the Na2SiO3 enrichment solution was 0.3:1.0.

[0027] In specific implementation, the molar ratio of sodium silicate to hexadecyltrimethylammonium bromide can also be 0.1:1.0, 0.2:1.0, 0.4:1.0 or 0.5:1.0.

[0028] S5: Place the reaction system obtained in step S4 into a high-temperature and high-pressure hydrothermal reactor and react at 110°C for 24 to 72 hours to carry out hydrothermal crystallization reaction. After the reaction is completed, filter to obtain the solid. In practice, the temperature of the hydrothermal crystallization reaction can be 80, 90, 100 or 120°C, and the time of the hydrothermal crystallization reaction can be 24 h, 36 h, 60 h or 72 h.

[0029] S6: The filtered solid is washed with deionized water until the waste liquid is neutral, and then dried at 105℃ for 12 hours. After drying, it is calcined in air atmosphere. The calcination process is carried out by heating at a rate of 2℃ / min to 550℃ and calcining for 6 hours.

[0030] Example 2 This embodiment investigates the effect of sodium hydroxide solution concentration on MCM-41 molecular sieves. Using the method of Example 1, in step S3, alkali leaching was performed with sodium hydroxide solutions of concentrations of 1 mol / L, 2 mol / L, 3 mol / L, and 4 mol / L, respectively, while maintaining the other concentrations consistently. The obtained molecular sieves were subjected to BET specific surface area testing, and the results were as follows: Figure 1 The nitrogen adsorption-desorption isotherms shown are compared by... Figure 1It can be seen that all four isotherms conform to the characteristics of Type IV isotherms in the IUPAC classification, and are accompanied by typical H1-type hysteresis loops, indicating that all samples successfully synthesized MCM-41 molecular sieves with mesoporous structures. The rapid adsorption rise in the low-pressure region (P / P0<0.1) corresponds to the micropore filling process of the material. This feature can significantly increase the adsorption sites of dyes, making up for the deficiency of pure MCM-41 relying solely on mesoporous adsorption. The steep adsorption plateau in the medium-high pressure region (P / P0=0.3~0.8) corresponds to the capillary condensation phenomenon of mesopores. The height of the plateau directly reflects the pore volume, while the width of the hysteresis loop corresponds to the uniformity of pore size distribution and the degree of mesoporous order.

[0031] The specific surface area S of each molecular sieve was calculated based on the nitrogen adsorption-desorption isotherm. BET (m 2 / g), total pore volume V total (cm 3 / g) and average pore size d ave. (nm), and the results are shown in Table 1 below; Table 1

[0032] As shown in Table 1, the MCM-41 prepared by treatment with 2 mol / L NaOH has the highest specific surface area (631 m²). 2 It has the smallest average pore size (4.23 nm) and the smallest average pore size ( / g).

[0033] Depend on Figure 1 As shown in Table 1, the sample prepared with 2 mol / L NaOH exhibits the best pore structure performance: the high-pressure region has the highest adsorption plateau, corresponding to the largest mesopore volume; the hysteresis loop is the narrowest and has the best closure, indicating that it has the narrowest pore size distribution and the highest mesopore order.

[0034] Example 3 This embodiment investigates the effect of adjusting the pH value with acetic acid to different endpoints on the preparation of MCM-41 molecular sieves. Using the optimal method of Example 2, the pH value was adjusted to 5.5, 7.5, 8.5, 9.5, and 10.5 with acetic acid in step S4, while keeping the other values ​​constant. The BET specific surface area of ​​the prepared molecular sieves was measured, and the results are as follows: Figure 2 The nitrogen adsorption-desorption isotherms shown are compared by... Figure 2 It can be seen that the isotherms of all samples conform to the characteristics of type IV isotherms in the IUPAC classification, and are accompanied by typical H1 type hysteresis loops, confirming that the process of the present invention can successfully synthesize MCM-41 molecular sieves with mesoporous structures regardless of pH value changes.

[0035] The rapid adsorption rise in the low-pressure region (P / P0 < 0.1) corresponds to the micropore filling process of the material. Introducing a certain amount of microporous structure into the mesoporous molecular sieve can additionally increase dye adsorption sites and improve adsorption capacity. The steep adsorption plateau in the medium-pressure region (P / P0 = 0.3~0.8) corresponds to the capillary aggregation phenomenon of the mesopores. The height of the plateau directly reflects the size of the mesopore pores, while the steepness of the plateau and the width of the hysteresis loop correspond to the uniformity of pore size distribution and the degree of mesopore order.

[0036] The specific surface area S of each molecular sieve was calculated based on the nitrogen adsorption-desorption isotherm. BET (m 2 / g), total pore volume V total (cm 3 / g) and average pore size d ave. (nm), and the results are shown in Table 2 below; Table 2

[0037] As shown in Table 2, as the pH value was gradually increased from 5.5 to 9.5, the BET specific surface area of ​​the molecular sieve showed a continuous upward trend, increasing from 443 m². 2 / g increased significantly to 649m 2 The pore size was the highest among all samples, while the average pore size gradually decreased from 6.49 nm to 3.71 nm, and the total pore volume ranged from 0.60 to 0.72 cm³. 3 The specific surface area of ​​BET fluctuated within a range of / g; when the pH value was further increased to 10.5, the specific surface area of ​​BET decreased slightly to 631m². 2 / g, and the total pore volume increased significantly to 0.77cm³. 3 / g, and the average pore size also increased to 4.23nm.

[0038] Depend on Figure 2 As shown in Table 2, the sample prepared at pH=9.5 exhibits the best pore structure performance: the pressure zone adsorption plateau is the steepest, the hysteresis loop is the narrowest and has the best closure, indicating that it has the highest mesoporous order and the narrowest pore size distribution, which is completely consistent with the result in Table 2 that the sample has the highest specific surface area.

[0039] Example 4 This embodiment investigates the effect of adding different amounts of hexadecyltrimethylammonium bromide in step S4 on the preparation of MCM-41 molecular sieves. Using the optimal method of Example 3, the ratio of Na2SiO3 to CTAB in step S4 was 1:0.1, 1:0.2, 1:0.3, 1:0.4, and 1:0.5, while keeping the other ratios constant. The BET specific surface area of ​​the prepared molecular sieves was measured, and the results are as follows: Figure 3 The nitrogen adsorption-desorption isotherms shown are compared by... Figure 3It can be seen that the isotherms of all samples conform to the characteristics of type IV isotherms in the IUPAC classification, and are accompanied by typical H1 type hysteresis loops, confirming that the process of the present invention can successfully synthesize MCM-41 molecular sieves with mesoporous structures under different amounts of CTAB.

[0040] The specific surface area S of each molecular sieve was calculated based on the nitrogen adsorption-desorption isotherm. BET (m 2 / g), total pore volume V total (cm 3 / g) and average pore size d ave. (nm), and the results are shown in Table 3 below; Table 3

[0041] As shown in Table 3, as the amount of CTAB gradually increases from 0.1 to 0.4, the BET specific surface area of ​​the molecular sieve increases from 577 m² / m³. 2 / g continued to rise to 769m 2 / g, reaching the maximum value among all samples, and the total pore volume also increased from 0.63cm. 3 / g increased synchronously to 0.85cm 3 / g, the average pore size first narrowed from 3.77nm to 3.30nm (CTAB=0.3) and then slightly rebounded to 3.63nm; when the CTAB dosage was further increased to 0.5, the BET specific surface area slightly decreased to 752m². 2 / g, and the total pore volume also decreased slightly to 0.83cm. 3 / g, the average pore size remains basically stable.

[0042] Depend on Figure 3 As shown in Table 3, the sample prepared with Na2SiO3∶CTAB=1∶0.4 exhibits the best pore structure performance: the pressure zone adsorption plateau is the steepest, the nitrogen adsorption capacity is the highest, the hysteresis loop is the narrowest and the closure is the best, indicating that it has the highest mesoporous order, the narrowest pore size distribution, and the largest mesoporous volume, which is completely consistent with the results in Table 3 that the specific surface area and total pore volume of the sample are both the maximum values.

[0043] Example 5 This embodiment investigates the effect of hydrothermal crystallization temperature on the preparation of MCM-41 molecular sieves; using the optimal method of Example 4, the hydrothermal crystallization reaction temperatures were 80℃, 90℃, 100℃, 110℃, and 120℃, with other parameters remaining consistent; the BET specific surface area of ​​the prepared molecular sieves was measured, and the results are as follows. Figure 4 The nitrogen adsorption-desorption isotherms shown are compared by... Figure 4It can be seen that the isotherms of all samples conform to the characteristics of type IV isotherms in the IUPAC classification, and are accompanied by typical H1 type hysteresis loops, confirming that the process of the present invention can successfully synthesize MCM-41 molecular sieves with mesoporous structures at different crystallization temperatures.

[0044] The specific surface area S of each molecular sieve was calculated based on the nitrogen adsorption-desorption isotherm. BET (m 2 / g), total pore volume V total (cm 3 / g) and average pore size d ave. (nm), and the results are shown in Table 4 below; Table 4

[0045] As shown in Table 4, as the crystallization temperature gradually increases from 80℃ to 100℃, the BET specific surface area of ​​the molecular sieve increases from 835m². 2 / g continued to rise to 859m 2 / g, reaching the maximum value among all samples, while the average pore size gradually narrowed from 3.99nm to 3.10nm, and the total pore volume increased from 1.01cm³. 3 / g gradually decreased to 0.80cm 3 / g; When the crystallization temperature is further increased to 110℃ and 120℃, the BET specific surface area drops sharply to 769m². 2 / g and 762m 2 / g, total pore volume initially rose slightly to 0.85cm³. 3 / g then decreased to 0.72cm 3 / g, the average pore size first increased to 3.63nm and then fell back to 3.22nm.

[0046] Depend on Figure 4 As shown in Table 4, the sample prepared at 100℃ exhibits the best pore structure performance: the pressure zone adsorption plateau is the steepest, the hysteresis loop is the narrowest and has the best closure, indicating that it has the highest mesoporous order and the narrowest pore size distribution, which is completely consistent with the results in Table 4 that the sample has the highest specific surface area and the smallest average pore size.

[0047] Example 6 This embodiment investigates the effect of hydrothermal crystallization reaction time on the preparation of MCM-41 molecular sieves; using the optimal method of Example 5, the hydrothermal crystallization reaction times were 24h, 36h, 48h, 60h, and 72h, respectively, with other parameters remaining consistent; the BET specific surface area of ​​the prepared molecular sieves was measured, and the results are as follows. Figure 5 The nitrogen adsorption-desorption isotherms shown are compared. Depend on Figure 5It can be seen that the isotherms of all samples conform to the characteristics of type IV isotherms in the IUPAC classification, and are accompanied by typical H1 type hysteresis loops, confirming that the process of the present invention can successfully synthesize MCM-41 molecular sieves with mesoporous structures under different crystallization times.

[0048] The specific surface area S of each molecular sieve was calculated based on the nitrogen adsorption-desorption isotherm. BET (m 2 / g), total pore volume V total (cm 3 / g) and average pore size d ave. (nm), and the results are shown in Table 5 below; Table 5

[0049] As shown in Table 5, as the crystallization time increased from 24 h to 36 h, the BET specific surface area of ​​the molecular sieve increased from 803 m² / h. 2 / g significantly increased to 900m 2 / g, reaching the maximum value among all samples, and the total pore volume also increased synchronously from 0.79cm. 3 / g increased to 0.86cm 3 / g, while the average pore size remained relatively stable at 3.11~3.16nm; when the crystallization time was further extended to 48h, 60h and 72h, the BET specific surface area showed a continuous decreasing trend, decreasing to 859m² / g. 2 / g、846m 2 / g and 808m 2 / g, total pore volume initially decreased slightly to 0.78cm³. 3 The concentration of 0.81 cm / g (after 60 hours) rose slightly to 0.81 cm / g. 3 / g (72h), the average pore size increased significantly to 3.34nm at 72h.

[0050] Depend on Figure 5 As shown in Table 5, the sample prepared at 36 h exhibits the best pore structure performance: the pressure zone adsorption plateau is the highest, the nitrogen adsorption capacity is the largest, the hysteresis loop is the narrowest and the closure is the best, indicating that it has the highest mesoporous order, the narrowest pore size distribution, and the largest mesoporous volume, which is completely consistent with the results in Table 5 that the specific surface area and total pore volume of the sample are both the maximum values.

[0051] Based on Examples 2-6, it can be seen that when the NaOH concentration is 2 mol / L, the system pH is 9.5, n(CTAB) / n(Si) = 0.4, the crystallization temperature is 100℃, and the crystallization time is 36 h, the specific surface area of ​​the prepared molecular sieve is as high as 900 m². 2 / g. Therefore, this condition is the optimal condition for preparing high specific surface area MCM-41 molecular sieves, which can be used as the main adsorbent for treating dye wastewater, thereby achieving the effect of "treating waste with waste" and realizing the reduction, resource utilization, and harmless utilization of gasification ash.

[0052] Example 7 like Figure 6 and Figure 7 As shown, a system for preparing MCM-41 molecular sieve using silicon-rich components from coal gasification slag includes a cyclone separator 1, a magnetic separation device 2, a physicochemical sieving device 3, an acid washing device 4, an alkaline washing device 5, a stirring device 6, a crystallization device 7, a filtration device 8, a calcination device 9, and a drying device 10. Cyclone separator 1 is used to separate coal gasification slag to obtain coal gasification slag of different particle sizes; cyclone separator 1 includes cyclone inlet 11, gas outlet 12 and fly ash outlet 13; cyclone separator 1 is generally conical in shape, cyclone inlet 11 is located on the top circumferential surface of cyclone separator 1 and is tangent to the cross-sectional arc of cyclone separator 1, gas outlet 12 is located at the center of the top end face of cyclone separator 1, and fly ash outlet 13 is located at the bottom end of cyclone separator 1; The magnetic separator 2 is used to extract magnetic oxides from coal gasification slag of different particle sizes discharged from the cyclone separator 1. The magnetic separator 2 includes a magnetic inlet 21, a magnetic outlet 22 and a gasification slag outlet 23. The fly ash outlet 13 is connected to the magnetic inlet 21, the magnetic outlet 22 is located in the middle of the magnetic separator 2, and the gasification slag outlet 23 is located at the bottom of the magnetic separator 2. The physicochemical screening device 3 is used to detect the gasification slag discharged from the magnetic separator 2 and screen out silicon-rich components; the physicochemical screening device 3 is an X-ray separator, and the inlet of the X-ray separator is connected to the gasification slag outlet 23. The pickling device 4 is used to perform acid treatment on silicon-rich modules to obtain pickling products. The pickling device 4 includes an acid inlet 41, a pickling inlet 42, a first outlet 43, a first product outlet 44, a first stirring motor 45, and a first stirring rod 46. The pickling inlet 42 and the acid inlet 41 are both located at the top of the pickling device 4. The pickling inlet 42 is connected to the outlet of the X-ray separator. The first outlet 43 and the first product outlet 44 are both located at the bottom of the pickling device 4. The first stirring motor 45 is vertically located at the top of the pickling device 4 with its output shaft pointing downwards. The first stirring rod 46 is fixedly connected to the output shaft of the first stirring motor 45 and is located inside the pickling device 4. Alkali washing device 5 is used to perform alkali washing treatment on acid washing products to obtain silica-rich filtrate; alkali washing device 5 includes alkali inlet 51, alkali washing inlet 52, second outlet 53, second product outlet 54, second stirring motor 55, and second stirring rod 56; alkali washing inlet 52 and alkali inlet 51 are both located at the top of alkali washing device 5, alkali washing inlet 52 is connected to first product outlet 44, second outlet 53 and second product outlet 54 are both located at the bottom of alkali washing device 5, second stirring motor 55 is vertically located at the top of alkali washing device 5 with its output shaft pointing downwards, and second stirring rod 56 is fixedly connected to the output shaft of second stirring motor 55 and located inside alkali washing device 5; A stirring device 6 is used to stir the silica-rich filtrate to obtain a mixed liquid. The stirring device 6 includes a stirring inlet 61, a mixing inlet 62, a third product outlet 63, a third stirring motor 64, and a third stirring rod 65. The stirring inlet 61 and the mixing inlet 62 are both located at the top of the stirring device 6. The stirring inlet 61 is connected to the second product outlet 54. The third product outlet 63 is located at the bottom of the stirring device 6. The third stirring motor 64 is vertically located at the top of the stirring device 6 with its output shaft pointing downwards. The third stirring rod 65 is fixedly connected to the output shaft of the third stirring motor 64 and is located inside the stirring device 6. A crystallization device 7 is used to heat the mixed liquid under high temperature and high pressure to obtain a crystallized liquid. The inlet of the crystallization device 7 is connected to the third product outlet 63. The filtration device 8 is used to filter and wash the crystallization solution to obtain filter residue; the filtration device 8 includes a filter inlet 81, a washing inlet 82, a fourth product outlet 83, and a third outlet 84; the filter inlet 81 and the washing inlet 82 are both located at the top of the filtration device 8, the outlet of the crystallization device 7 is connected to the filter inlet 81, and the fourth product outlet 83 and the third outlet 84 are both located at the bottom of the filtration device 8; the calcination device 9 is used to calcine the filter residue in an air atmosphere to obtain MCM-41 molecular sieve samples; the calcination device 9 is a tubular furnace; The drying device 10 is used to dry and remove water from the input product. The drying device 10 includes a first dryer 101, a second dryer 102 and a third dryer 103. The first dryer 101 is located between the gasification slag outlet 23 and the inlet of the X-ray separator. The second dryer 102 is located between the first product outlet 44 and the alkaline washing inlet 52. The third dryer 103 is located between the fourth product outlet 83 and the feed inlet of the calcining device 9.

[0053] In this application, the material conveying between devices is selected as needed based on the material form, using pneumatic conveying and liquid pump conveying. The installation of pneumatic conveying systems and liquid pumps on pipelines are both mature existing technologies, and therefore are not described in this document.

[0054] Cyclone separator 1 separates the gasification slag particles, achieving initial separation of carbon and silicon components for graded and differentiated utilization. Magnetic separator 2 then separates the magnetic oxides of the mixture, significantly improving the performance of subsequent molecular sieve preparations and enabling efficient resource recovery, thus enhancing environmental benefits. Acid washing device 4, alkali washing device 5, stirring device 6, and crystallization device 7 further process the gasification slag through acid washing, alkali leaching, and hydrothermal synthesis. This process not only achieves efficient extraction of silicon sources, synergistic effects of residual carbon, and significant improvement in adsorption performance, but also reduces process energy consumption and chemical energy consumption, making it a functional material for wastewater purification. This process achieves the reduction, resource utilization, and harmless treatment of gasification slag. The crystallization liquid is then filtered through a filtration device 8, and the filter residue is transported to a calcination device 9 for calcination to obtain MCM-41 molecular sieve samples. The operation is simple, with low energy consumption, low cost, and high specific surface area, enabling continuous production. Silicon-rich components from the X-ray separator are input through the acid washing inlet 42, and hydrochloric acid solution is added through the acid inlet 41 to acid wash the silicon-rich components. This significantly reduces the inorganic mineral content in the gasification slag, breaks Si-OM (M=Fe, Ca, Mg, etc.) bonds, and decomposes Si-O-Si polymers, achieving reactive reconstruction. After pickling, the waste liquid is discharged from the first outlet 43, and the pickling product is discharged from the first product outlet 44 and enters the alkaline washing inlet 52. Sodium hydroxide solution is added from the alkaline inlet 51 and stirred. The silica-rich filtrate after alkaline washing is discharged through the second product outlet 54, and the waste residue is discharged through the second outlet 53. The silica-rich filtrate enters from the stirring inlet 61, and CTAB and water are added from the mixing inlet 62. Acetic acid is added to adjust the internal pH value, and then the mixture is thoroughly stirred by the third motor and the third stirring rod 65 to obtain a mixed solution. The mixed solution is discharged from the third product outlet 63. The thoroughly stirred mixed solution enters the crystallization device 7. Inside, a high-temperature, high-pressure hydrothermal crystallization reaction is carried out to obtain a crystallization liquid. The crystallization liquid is then introduced into the filtration device 8 through the filter inlet 81, and distilled water is added through the washing inlet 82 to filter the crystallization liquid. The filtrate is discharged from the third outlet 84, and the filter residue is discharged from the fourth product outlet 83. The drying device 10 is set up so that the filter residue enters the third dryer 103 from the fourth product outlet 83 for drying. The dried filter residue is then transported to the calcination device 9 for calcination to obtain the MCM-41 molecular sieve sample. Both the first dryer 101 and the second dryer 102 dry the product entering them, making the product more stable.

Claims

1. A method for preparing MCM-41 molecular sieves using silicon-rich components from coal gasification slag, characterized in that, The following steps are used: S1: Pre-treat the coal gasification slag to obtain the silicon-rich components in the coal gasification slag; S2: The silicon-rich components are pickled using hydrochloric acid solution; S3: Wash the acid washing product with deionized water until the waste liquid is neutral, filter it dry, and then put it into sodium hydroxide solution for stirring reaction. After the reaction is completed, filter the liquid to obtain Na2SiO3 enriched solution. S4: After mixing the Na2SiO3 enrichment solution with hexadecyltrimethylammonium bromide and water, stir the reaction at room temperature, adjust the pH value to 5.5~10.5 with acetic acid, and continue stirring the reaction. S5: The reaction system obtained in step S4 is subjected to hydrothermal crystallization reaction in a high-temperature and high-pressure hydrothermal reactor. After the reaction is completed, the solid is filtered out. S6: After washing and drying the filtered solid, calcination yields MCM-41 molecular sieve.

2. The method according to claim 1, characterized in that, Step S1 specifically involves: S11: Screen the coal gasification slag to remove carbon-rich components and retain the gasification slag; S12: The gasification slag is subjected to magnetic separation to remove the magnetic oxides, and then dried to a moisture content of less than 1%. S13: The dried gasification slag is subjected to physicochemical property testing to screen out the silicon-rich components.

3. The method according to claim 1, characterized in that, Step S2 specifically involves: adding the silicon-rich component into a hydrochloric acid solution with a mass fraction of 10-25%, stirring and refluxing at 60-100°C for 2-6 hours, and using a heat-treated silicon-rich component to hydrochloric acid solution in a ratio of 1g:10mL.

4. The method according to claim 3, characterized in that, Step S3 specifically involves: washing the pickling product with deionized water until the waste liquid is neutral, filtering it, adding the filtered pickling product to a sodium hydroxide solution with a concentration of 1-4 mol / L, stirring and refluxing at 60-100℃ for 4-8 hours, filtering the liquid to obtain a Na2SiO3 enriched solution, and using a ratio of the filtered pickling product to sodium hydroxide solution of 1 g: 10 mL.

5. The method according to claim 4, characterized in that, Step S4 specifically involves: determining the molar amount of sodium silicate in the Na2SiO3 enrichment solution, adding hexadecyltrimethylammonium bromide to the Na2SiO3 enrichment solution, stirring the reaction at room temperature for 3 hours, adjusting the pH value to 5.5~10.5 with acetic acid, and continuing to stir the reaction at room temperature for 2 hours. The molar ratio of hexadecyltrimethylammonium bromide to sodium silicate in the Na2SiO3 enrichment solution is 0.1~0.5∶1.

0.

6. The method according to claim 5, characterized in that, The hydrothermal crystallization reaction in step S5 specifically involves reacting at 80~120℃ for 24~72 hours.

7. The method according to claim 6, characterized in that, Step S6 specifically involves washing the filtered solid with deionized water until the waste liquid is neutral, drying it at 105°C for 12 hours, and then calcining it in air. The calcination process involves raising the temperature to 550°C at a rate of 2°C / min and calcining for 6 hours.

8. The MCM-41 molecular sieve prepared by the preparation method described in claims 1 to 7.

9. A system for preparing MCM-41 molecular sieves using silicon-rich components from coal gasification slag, characterized in that, include: Cyclone separators are used to separate coal gasification slag to obtain coal gasification slag of different particle sizes; A magnetic separator is connected to the outlet of the cyclone separator to extract magnetic oxides from the gasification slag of different particle sizes discharged from the cyclone separator; a physicochemical screening device is connected to the outlet of the magnetic separator to detect the gasification slag discharged from the magnetic separator and screen out silicon-rich components; an acid washing device is connected to the outlet of the physicochemical screening device to perform acid treatment on the silicon-rich components to obtain acid washing products. An alkaline washing device is connected to the outlet of the acid washing device to perform alkaline washing treatment on the acid washing product to obtain a silicon-rich filtrate; a stirring device is connected to the outlet of the alkaline washing device to stir the silicon-rich filtrate to obtain a mixed liquid; and a crystallization device is connected to the outlet of the stirring device to heat the mixed liquid under high temperature and high pressure to obtain a crystallized liquid. A filtration device is connected to the outlet of the crystallization device to filter and wash the crystallization liquid to obtain filter residue; a calcination device is connected to the outlet of the filtration device to calcine the filter residue in an air atmosphere to obtain an MCM-41 molecular sieve sample; a drying device is located between the magnetic separation device and the physicochemical sieving device, between the acid washing device and the alkali washing device, and between the filtration device and the calcination device, and the drying device dries and removes water from the input product.

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