Preparation method and application of high-efficiency granular carclazyte adsorbent for olefin removal / denitrification

Abstract

The invention provides a preparation method and application of an efficient granular carclazyte adsorbent for olefin removal / denitrification, and the preparation method comprises the following steps: carrying out organic intercalation modification treatment on activated carclazyte by adopting hexadecyl trimethyl ammonium bromide and caprolactam to obtain intercalation modified carclazyte; carrying out surface hydrophobic modification treatment on the intercalated modified carclazyte by adopting a silane coupling agent to obtain composite modified carclazyte; adding magnesium chloride into the carclazyte dispersion liquid to obtain an intermediate solution; adding sodium hydroxide into the intermediate solution, mixing, stirring and heating for reaction, and obtaining the efficient granular carclazyte adsorbent after the reaction is finished. According to the preparation method disclosed by the invention, the nano magnesium oxide is synthesized on the surface and interlayer of the composite modified carclazyte through a hydrothermal synthesis reaction of magnesium chloride and sodium hydroxide, and more new gaps are formed through stacking of the nano magnesium oxide, so that the efficient granular carclazyte adsorbent with high specific surface area and high porosity is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of petrochemical industry, and relates to a preparation method and application of an efficient granular clay adsorbent for olefin / denitrogenation removal. Background Art

[0002] Clay, scientifically named bentonite, is a natural multi-functional clay mineral, whose main component is montmorillonite and contains a small amount of impurities such as quartz and feldspar. Due to its unique layered structure and large specific surface area, clay exhibits excellent adsorption, ion exchange and catalytic properties. In many fields such as petrochemical industry, environmental protection and daily chemical industry, clay plays an irreplaceable role. Especially in the process of oil refining, as an adsorbent, clay can effectively remove impurities in oil products and improve the purity and quality of products.

[0003] In the field of olefin removal, the application of clay mainly focuses on the refining of aromatics and the treatment of reformate. Aromatics are important raw materials in the petrochemical industry, but their production process is often accompanied by the generation of impurities such as olefins. These impurities not only affect the purity of aromatics, but may also have an adverse impact on subsequent processing. Traditionally, the clay adsorption method can effectively remove these olefin impurities and improve the purity of aromatics. However, with the continuous improvement of the requirements for oil product quality, the application of traditional clay adsorbents in the field of olefin removal faces many challenges. First of all, the adsorption capacity of clay is limited and it is difficult to meet the demand for large-scale production of high-purity aromatics. Secondly, clay is prone to reach adsorption saturation during use, resulting in a short service life. Frequent replacement of the adsorbent not only increases the production cost, but also affects the production efficiency. In addition, clay is prone to deactivate under harsh operating conditions such as high temperature or high pressure, which limits its application in some special processes.

[0004] In addition to olefin removal, clay also has certain applications in the field of denitrogenation. In oil products, basic nitrogen compounds are one of the important factors affecting the quality and stability of oil products. Through the adsorption of clay, these nitrogen compounds can be effectively removed to improve the quality of oil products. However, the application of clay in the field of denitrogenation also faces many limitations. On the one hand, the denitrogenation ability of clay is relatively weak and the adsorption amount is small, making it difficult to meet the requirements of high denitrogenation rate. On the other hand, the problem of waste clay treatment is becoming increasingly prominent. Waste clay contains a large amount of harmful substances, which will cause serious pollution to the environment if not properly treated. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a preparation method and application of a high-efficiency granular clay adsorbent for olefin / denitrification removal. First, the bentonite ore is treated with a specific acidifying agent, effectively improving the activation effect of bentonite and laying a solid foundation for subsequent modification treatment. Cetyltrimethylammonium bromide and caprolactam are used to carry out organic intercalation modification on activated clay, further enhancing the interlayer structure and adsorption performance of activated clay; subsequently, a silane coupling agent is used for surface hydrophobic modification, enabling the activated clay to have good hydrophobic properties while maintaining high adsorption capacity, and improving its affinity with olefins. Finally, through the hydrothermal synthesis reaction of magnesium chloride and sodium hydroxide, nano-magnesium oxide is synthesized on the surface and between the layers of the composite modified clay, and more new pores are formed by the stacking of nano-magnesium oxide, and finally a high-efficiency granular clay adsorbent with high activity and large pore size is obtained.

[0006] To achieve this purpose, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a preparation method of a high-efficiency granular clay adsorbent for olefin / denitrification removal, and the preparation method includes: (I) Mix concentrated hydrochloric acid, concentrated sulfuric acid, oxalic acid and deionized water to obtain an acidifying agent. Crush and screen the bentonite ore to obtain bentonite powder, and mix the bentonite powder with deionized water to obtain a bentonite slurry; mix the bentonite slurry, the acidifying agent and sodium chloride evenly to obtain a raw material mixture, heat and activate the raw material mixture to obtain an activated product, and rinse, centrifuge, dry and crush the activated product to obtain activated clay; (II) Carry out organic intercalation modification treatment on the activated clay obtained in step (I) with cetyltrimethylammonium bromide and caprolactam to obtain intercalation-modified clay; subsequently, carry out surface hydrophobic modification treatment on the intercalation-modified clay with a silane coupling agent to obtain composite-modified clay; (III) Disperse the composite-modified clay obtained in step (II) in deionized water to obtain a clay dispersion; add magnesium chloride to the clay dispersion, mix, stir and heat to obtain an intermediate solution; add sodium hydroxide to the intermediate solution, mix, stir and heat to react, and after the reaction is completed, filter, wash, extrude into shape, dry, calcine and crush and screen to obtain the high-efficiency granular clay adsorbent.

[0007] The present invention first treats the original bentonite ore with a specific acidifying agent, effectively enhancing the activation effect of the bentonite and laying a solid foundation for subsequent modification treatment. Cetyltrimethylammonium bromide and caprolactam are used to conduct organic intercalation modification on the activated clay, further enhancing the interlayer structure and adsorption performance of the activated clay; subsequently, a silane coupling agent is used for surface hydrophobic modification, enabling the activated clay to have good hydrophobic properties while maintaining high adsorption capacity, and improving its affinity with olefins. Finally, through the hydrothermal synthesis reaction of magnesium chloride and sodium hydroxide, nano-magnesium oxide is synthesized on the surface and between the layers of the composite modified clay, and more new pores are formed through the stacking of nano-magnesium oxide, ultimately obtaining an efficient granular clay adsorbent with high activity and large pore size.

[0008] The present invention uses a mixed acid solution composed of concentrated hydrochloric acid, concentrated sulfuric acid, and oxalic acid to conduct acid activation treatment on bentonite, which can significantly improve the olefin and nitrogen removal capabilities of the activated clay. On the one hand, during the acidification process, some non-adsorptive impurities, soluble impurities, and minerals in the bentonite are decomposed by the acid and dissolved in the liquid phase system, causing partial lattice destruction of the bentonite, an increase in the crystal plane spacing, the opening of the pore channels of the bentonite, an increase in the pore size, and an increase in the adsorption sites, thereby enhancing the physical adsorption capacity of the activated clay for olefins and nitrogen. On the other hand, in terms of olefin removal, the surface of the activated clay after acid activation treatment has a large number of acidic sites, which can cause olefins to undergo alkylation and condensation polymerization reactions, and thus be effectively removed; in terms of nitrogen removal, when the bentonite is activated with the mixed acid, hydrogen ions replace the exchangeable metal ions, forming abundant acid centers on the surface. The basicity of the basic nitride morpholine lies in the unshared electron pair on its nitrogen atom, which can combine with protons to form a positively charged ion. When the strongly basic morpholine adsorbs on the surface of the activated clay, the acid center of the activated clay can undergo a neutralization reaction with the nitrogen atom of morpholine, forming the corresponding amine salt and depositing on the surface of the activated clay to achieve the purpose of nitrogen removal.

[0009] The activated clay obtained after acidification is hydrophilic, has poor affinity for organic substances, and the interlayer structure of the activated clay is not completely opened, resulting in weak adsorption capacity for olefins and nitrogen. In order to improve the affinity and adsorption capacity of the activated clay and make full use of its large specific surface area, the present invention uses cetyltrimethylammonium bromide and caprolactam to conduct composite intercalation modification treatment on the activated clay. After the organic cations of cetyltrimethylammonium bromide exchange with the inorganic cations between the layers of the activated clay, the cationic part adheres to the activated clay platelets, and the organic part remains between the layers, thereby increasing the interlayer spacing of the activated clay, making the structure more loose, having a higher porosity, and partial platelet peeling occurs.

[0010] However, the modification of activated clay with cetyltrimethylammonium bromide not only has a relatively high cost, but also the compatibility between the modified activated clay and olefins is poor, so it is difficult to form an intercalated structure. Therefore, on the basis of the organic intercalation modification with cetyltrimethylammonium bromide, the present invention adds caprolactam to perform composite modification on the activated clay. After the composite intercalation modification with cetyltrimethylammonium bromide / caprolactam, the interlayer spacing of the intercalated modified clay is significantly increased. This is because, after the cation exchange between cetyltrimethylammonium bromide and the activated clay, on the one hand, the interlayer spacing of the activated clay is expanded to a certain extent, providing sufficient adsorption space for the subsequent entry of caprolactam; on the other hand, after the intercalation modification with cetyltrimethylammonium bromide, the interlayer microenvironment of the activated clay changes from hydrophilic to lipophilic. In this environment, it is beneficial for caprolactam to be adsorbed into the interlayer of the activated clay. The C=O group of the caprolactam adsorbed into the interlayer of the activated clay is easy to form a hydrogen bond with the -OH group in the interlayer of the bentonite layer, thereby introducing caprolactam molecules into the interlayer of the activated clay and further expanding the interlayer spacing of the activated clay.

[0011] The organic intercalation modification of activated clay with cetyltrimethylammonium bromide and caprolactam is achieved by entering the interlayer of the activated clay through ion exchange and chemical bond action to realize the intercalation modification. However, this modification method can only modify the interlayer of the activated clay platelets, which can increase the interlayer spacing of the activated clay and provide a certain space for the adsorption of olefins and nitrogen. However, the surface modification effect of the activated clay by only intercalation modification is insufficient. Therefore, it is impossible to significantly improve the surface hydrophobicity of the activated clay, which affects its compatibility with the organic phase and results in insufficient affinity for olefins. Therefore, after the intercalation modification of the activated clay, the present invention further performs hydrophobic modification on the surface of the intercalated modified clay with a silane coupling agent. A silane coupling agent is a substance with two different chemically reactive functional groups, a non-hydrolyzable group and a hydrolyzable group. The silanol generated by its hydrolysis can react with the hydroxyl groups on the surface of the intercalated modified clay and then graft onto the surface of the intercalated modified clay. At the same time, the silanols grafted onto the surface of the intercalated modified clay associate with each other to form a network-structured hydrophobic film and cover the surface of the intercalated modified clay. The composite modified clay obtained after the modification with the silane coupling agent changes from hydrophilic to hydrophobic. The improvement of hydrophobicity enhances the affinity, swelling property and dispersibility of the composite modified clay in the organic phase, making it better applied in the organic system for olefin / nitrogen removal.

[0012] The present invention generates magnesium hydroxide through the hydrothermal synthesis reaction of magnesium chloride and sodium hydroxide. Then, using magnesium hydroxide as a precursor, magnesium oxide particles are in-situ loaded on the surface and between the layers of the composite modified clay after high-temperature calcination, and finally the high-efficiency particulate clay adsorbent provided by the present invention is obtained. Compared with the composite modified clay, the specific surface area of the high-efficiency particulate clay adsorbent loaded with magnesium oxide particles decreases (the specific surface area of the composite modified clay is about 91-100 m 2 / g, and the specific surface area of the high-efficiency particulate clay adsorbent is about 30-40 m 2 / g). This is because the magnesium oxide particles are inserted between the layers of the composite modified clay, resulting in the blockage of the channels between the layers and the surface pores, reducing the specific surface area of the composite modified clay. However, at the same time, the pore volume and pore diameter of the high-efficiency particulate clay adsorbent loaded with magnesium oxide particles increase significantly (the pore volume of the composite modified clay is about 0.1-0.15 cc / g, and the pore diameter is about 3.5-4 nm; the pore volume of the high-efficiency particulate clay adsorbent is about 0.35-0.4 cc / g, and the pore diameter is about 35-40 nm). This is because the magnesium hydroxide deposited on the surface of the composite modified clay decomposes into magnesium oxide after high-temperature calcination. During the high-temperature calcination process, by-products volatilize, including physically and chemically adsorbed water molecules and carbon dioxide, etc. The space originally occupied by these products forms a pore structure, thus generating a certain number of micropores inside and on the surface of the magnesium oxide. In addition, as the calcination continues, the magnesium oxide loaded on the surface of the composite modified clay continuously generates and accumulates and overlaps, forming a large number of mesoporous structures, resulting in a significant increase in the pore volume and pore diameter of the finally obtained high-efficiency particulate clay adsorbent, a significant increase in the adsorption sites, and a significant enhancement in the adsorption capacity.

[0013] As a preferred technical solution of the present invention, in step (Ⅰ), when preparing the acidifying agent, first slowly add the concentrated hydrochloric acid to deionized water, and after mixing evenly, obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid to the dilute hydrochloric acid to obtain a mixed acid solution; finally, add oxalic acid to the mixed acid solution and mix evenly to obtain the acidifying agent.

[0014] In some alternative examples, the mass fraction of the concentrated hydrochloric acid is 35-37 wt%, for example, it can be 35 wt%, 35.2 wt%, 35.4 wt%, 35.6 wt%, 35.8 wt%, 36 wt%, 36.2 wt%, 36.4 wt%, 36.6 wt%, 36.8 wt% or 37 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0015] In some alternative examples, the mass fraction of the concentrated sulfuric acid is 95 - 98 wt%, for example, it can be 95 wt%, 95.5 wt%, 96 wt%, 96.5 wt%, 97 wt%, 97.5 wt% or 98 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0016] In some alternative examples, the volume ratio of the concentrated hydrochloric acid, the concentrated sulfuric acid and the deionized water is 1:(1.4 - 1.6):(35 - 40), for example, it can be 1:1.4:35, 1:1.42:35.5, 1:1.44:36, 1:1.46:36.5, 1:1.48:37, 1:1.5:37.5, 1:1.52:38, 1:1.5:38.5, 1:1.56:39, 1:1.58:39.5 or 1:1.6:40, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0017] The present invention specifically defines the volume ratio of the concentrated hydrochloric acid, the concentrated sulfuric acid and the deionized water as 1:(1.4 - 1.6):(35 - 40). If the hydrogen ion concentration ionized by sulfuric acid is too high, it will destroy the crystal layer structure of bentonite, resulting in the dissolution of some aluminum ions and magnesium ions in the interlayer of bentonite by hydrogen ions, thus causing the collapse of the bentonite skeleton and the destruction of the octahedron. While the hydrogen ion concentration ionized by hydrochloric acid is relatively low, and its activation effect during the acid modification process is inferior to that of the mixed acid. The hydrogen ion concentration ionized by the mixed acid composed of hydrochloric acid, sulfuric acid and oxalic acid is moderate. After adding oxalic acid, it can form insoluble salts with calcium ions and magnesium ions, which is beneficial to the replacement of calcium ions and magnesium ions in the interlayer of bentonite, and the activation effect is the best.

[0018] In some alternative examples, the mass fraction of oxalic acid in the acidifying agent is 5 - 10 wt%, for example, it can be 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt%, 8.5 wt%, 9.0 wt%, 9.5 wt% or 10.0 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0019] As a preferred technical solution of the present invention, in step (Ⅰ), the particle size of the bentonite powder is 100 - 200 mesh, for example, it can be 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh or 200 mesh, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0020] In some alternative examples, the bentonite powder and deionized water are mixed at a mass ratio of (0.6~0.7):1 to obtain the bentonite slurry. For example, it can be 0.6:1, 0.61:1, 0.62:1, 0.63:1, 0.64:1, 0.65:1, 0.66:1, 0.67:1, 0.68:1, 0.69:1 or 0.7:1. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0021] In some alternative examples, the mass ratio of the bentonite slurry, the acidifying agent and sodium chloride is 1:(0.6~0.7):(0.08~0.1). For example, it can be 1:0.6:0.08, 1:0.61:0.082, 1:0.62:0.084, 1:0.63:0.086, 1:0.64:0.088, 1:0.65:0.09, 1:0.66:0.092, 1:0.67:0.094, 1:0.68:0.096, 1:0.69:0.098 or 1:0.7:0.1. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0022] The present invention specifically defines that the mass ratio of the bentonite slurry, the acidifying agent and sodium chloride is 1:(0.6~0.7):(0.08~0.1). When the dosage of the acidifying agent is lower than the lower limit of the range defined by the present invention, the replacement of calcium ions by hydrogen ions is incomplete, and the quality of the finally obtained activated clay is poor. As the dosage of the acidifying agent increases, the hydrogen ion concentration increases, and the activity of the activated clay obtained after acid activation increases rapidly. This indicates that the calcium ions and magnesium ions in the bentonite interlayer are fully replaced by hydrogen ions and are acid-modified into highly efficient activated clay with a larger specific surface area and stronger adsorption. When the dosage of the acidifying agent exceeds the upper limit of the range defined by the present invention, the excessive hydrogen ion concentration causes the aluminum ions in the tetrahedral structure of the bentonite to be exchanged and dissolved, destroying the framework structure of the bentonite, resulting in a significant decrease in the activity of the finally obtained activated clay.

[0023] In some alternative examples, the operation steps of the heating activation include: Heating the raw material mixture to the first activation temperature and holding it for a certain time. After the holding ends, continue to heat it to the second activation temperature and hold it again. After the holding ends, cool it to room temperature to obtain the activation product.

[0024] In some alternative examples, the first activation temperature is 80~90℃. For example, it can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃ or 90℃. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0025] In some alternative examples, keep the temperature at the first activation temperature for 2 to 3 hours. For example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0026] In some alternative examples, the second activation temperature is 100 to 110 °C. For example, it can be 100 °C, 101 °C, 102 °C, 103 °C, 104 °C, 105 °C, 106 °C, 107 °C, 108 °C, 109 °C or 110 °C, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0027] In some alternative examples, keep the temperature at the second activation temperature for 2 to 3 hours. For example, it can be 2.0h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3.0h, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0028] In some alternative examples, rinse the activated product with deionized water until the pH value of the activated product reaches 4 to 5. For example, it can be 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 or 5.0, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0029] In some alternative examples, the rotation speed of the centrifugation is 3000 to 4000 rpm. For example, it can be 3000 rpm, 3100 rpm, 3200 rpm, 3300 rpm, 3400 rpm, 3500 rpm, 3600 rpm, 3700 rpm, 3800 rpm, 3900 rpm or 4000 rpm, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0030] In some alternative examples, the time of the centrifugation is 5 to 10 minutes. For example, it can be 5.0 min, 5.5 min, 6.0 min, 6.5 min, 7.0 min, 7.5 min, 8.0 min, 8.5 min, 9.0 min, 9.5 min or 10.0 min, but it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0031] As a preferred technical solution of the present invention, in step (II), the operation steps of the organic intercalation modification treatment include: Disperse the activated clay in deionized water to obtain a clay suspension; under continuous stirring and water bath heating conditions, successively add cetyltrimethylammonium bromide and caprolactam to the clay suspension to react. After the reaction is completed, centrifuge, wash and dry the precipitate obtained after centrifugation to obtain the intercalation-modified clay.

[0032] As a preferred technical solution of the present invention, the mass fraction of the activated clay in the clay suspension is 2-5 wt%, for example, it can be 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt% or 5.0 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0033] In some optional examples, the mass ratio of the activated clay to cetyltrimethylammonium bromide in the clay suspension is 1:(0.3-0.5), for example, it can be 1:0.3, 1:0.32, 1:0.34, 1:0.36, 1:0.38, 1:0.4, 1:0.42, 1:0.44, 1:0.46, 1:0.48 or 1:0.5, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0034] The present invention specifically limits the mass ratio of the activated clay to cetyltrimethylammonium bromide to 1:(0.3-0.5). As the amount of cetyltrimethylammonium bromide used increases, the layer spacing of the finally obtained intercalation-modified clay shows a trend of first increasing and then decreasing. When the mass ratio of the activated clay to cetyltrimethylammonium bromide is within the numerical range defined by the present invention, a larger layer spacing can be obtained and a higher intercalation efficiency can be achieved. When the amount of cetyltrimethylammonium bromide used is lower than the lower limit of the range defined by the present invention, the interlayer cations of the activated clay cannot be completely exchanged by the cetyltrimethylammonium bromide chain, resulting in a smaller layer spacing of the intercalation-modified clay, thereby affecting the adsorption capacity for olefins and nitrogen. When the amount of cetyltrimethylammonium bromide used exceeds the upper limit of the range defined by the present invention, excessive organic chains are easily stacked in the interlayer edge region of the activated clay, blocking the exchange channels between the organic chains and the interlayer cations, generating steric hindrance to the molecular chains of cetyltrimethylammonium bromide that have not entered the interlayer. As a result, only a small part of the cetyltrimethylammonium bromide molecular chains can successfully enter the interlayer of the activated clay, while most of the cetyltrimethylammonium bromide molecular chains cannot successfully enter the interlayer of the activated clay and are only simply adsorbed on the surface of the activated clay, hindering the continuous increase of the layer spacing of the activated clay. Therefore, continuously increasing the amount of cetyltrimethylammonium bromide used cannot make the layer spacing of the activated clay continue to expand, and the intercalation efficiency is low.

[0035] In some alternative examples, the mass ratio of cetyltrimethylammonium bromide to caprolactam is (2 - 3):1. For example, it can be 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1 or 3.0:1. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0036] The present invention specifically defines that the mass ratio of cetyltrimethylammonium bromide to caprolactam is (2 - 3):1. When cetyltrimethylammonium bromide and caprolactam are within this range, the interlayer spacing of the intercalation-modified bentonite obtained is the largest. This is because caprolactam reacts with sodium ions between the layers of activated bentonite to open the ring and generate amide ions, thereby entering the interlayer of activated bentonite and increasing the interlayer spacing of activated bentonite. When the dosage of caprolactam is lower than the lower limit of the range defined in the present invention, there is not enough caprolactam participating in the reaction, and too little caprolactam enters the interlayer of activated bentonite, making it impossible to effectively intercalate and modify activated bentonite, and the improvement degree of the interlayer spacing of activated bentonite is limited. When the dosage of caprolactam exceeds the upper limit of the range defined in the present invention, it will act on the lattice sites in the opposite direction, damaging the lattice sites between the layers of activated bentonite, causing the cetyltrimethylammonium bromide that has entered the interlayer of activated bentonite and completed cation exchange to lose its binding sites and finally fall off from the interlayer of activated bentonite; in addition, due to the large solubility of caprolactam in water, and it is easy to form amide ions with the hydroxyl groups and hydrogen ions between the layers and at the edges of activated bentonite, it can preferentially enter the interlayer of activated bentonite. The caprolactam that preferentially enters the interlayer of activated bentonite will have a certain hindering effect on the cetyltrimethylammonium bromide that has not entered the interlayer of activated bentonite, affecting the intercalation modification effect of cetyltrimethylammonium bromide.

[0037] In some alternative examples, the temperature of the water bath heating is 70 - 80 °C. For example, it can be 70 °C, 71 °C, 72 °C, 73 °C, 74 °C, 75 °C, 76 °C, 77 °C, 78 °C, 79 °C or 80 °C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0038] In some alternative examples, after adding cetyltrimethylammonium bromide to the bentonite suspension, continue to mix and stir for 10 - 20 min under the condition of water bath heating, and then add caprolactam. For example, it can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0039] In some alternative embodiments, after adding caprolactam, mixing and stirring are continued for 3 to 4 hours under water bath heating conditions. For example, it can be 3.0h, 3.1h, 3.2h, 3.3h, 3.4h, 3.5h, 3.6h, 3.7h, 3.8h, 3.9h or 4.0h, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0040] In some alternative embodiments, the rotation speed of the centrifugation is 7000 to 8000 rpm. For example, it can be 7000 rpm, 7100 rpm, 7200 rpm, 7300 rpm, 7400 rpm, 7500 rpm, 7600 rpm, 7700 rpm, 7800 rpm, 7900 rpm or 8000 rpm, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0041] In some alternative embodiments, the time of the centrifugation is 10 to 20 minutes. For example, it can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0042] As a preferred technical solution of the present invention, in step (II), the operating steps of the surface hydrophobic modification treatment include: Mix the silane coupling agent and the ethanol aqueous solution evenly to obtain a coupling agent solution, add the intercalation-modified bentonite to the coupling agent solution, mix and stir and heat to cause a reaction, and after the reaction is completed, filter, wash and dry to obtain the composite-modified bentonite.

[0043] As a preferred technical solution of the present invention, the volume ratio of ethanol to deionized water in the ethanol aqueous solution is (4 to 5):1. For example, it can be 4.0:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1 or 5.0:1, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0044] In some alternative embodiments, the mass fraction of the silane coupling agent in the coupling agent solution is 1 to 5 wt%. For example, it can be 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt% or 5.0 wt%, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0045] In some alternative examples, the mass ratio of the silane coupling agent in the coupling agent solution to the intercalation-modified clay is (0.02~0.05):1. For example, it can be 0.02:1, 0.025:1, 0.03:1, 0.035:1, 0.04:1, 0.045:1 or 0.05:1. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0046] The present invention specifically defines that the mass ratio of the silane coupling agent to the intercalation-modified clay is (0.02~0.05):1. As the amount of the silane coupling agent increases, the hydrophobicity of the finally obtained composite-modified clay shows a trend of first increasing and then decreasing. This is because when the amount of the silane coupling agent is lower than the lower limit of the range defined by the present invention, it cannot react completely with the intercalation-modified clay. As the amount of the silane coupling agent increases, the number of silane coupling agents grafted on the surface of the intercalation-modified clay continuously increases, thereby enhancing the surface hydrophobicity of the intercalation-modified clay and further improving its affinity with olefins. When the amount of the silane coupling agent reaches the upper limit of the range defined by the present invention, the silane coupling agent just reacts completely with all the hydroxyl groups on the surface of the intercalation-modified clay, thereby grafting and forming an ordered monolayer of silane coupling agent on the surface of the intercalation-modified clay. At this time, the intercalation-modified clay has the highest hydrophobicity and the best affinity with olefins. When the amount of the silane coupling agent exceeds the upper limit of the range defined by the present invention, the silane coupling agent hydrolyzes excessively to form silanol, and the silanol accumulates on the surface of the intercalation-modified clay to form a multi-molecular layer of silanol, which instead reduces the surface hydrophobicity of the intercalation-modified clay, thereby affecting its affinity with olefins and its removal rate of olefins.

[0047] In some alternative examples, the reaction temperature of the intercalation-modified clay and the coupling agent solution is 70~80°C. For example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0048] In some alternative examples, the reaction time of the intercalation-modified clay and the coupling agent solution is 3~5 h. For example, it can be 3.0 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4.0 h, 4.2 h, 4.4 h, 4.6 h, 4.8 h or 5.0 h. However, it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0049] As a preferred technical solution of the present invention, in step (III), the mass fraction of the composite modified clay in the clay dispersion is 2-5 wt%, for example, it can be 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt% or 5.0 wt%, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0050] In some alternative examples, the mass ratio of the composite modified clay to magnesium chloride in the clay dispersion is 1:(0.5-0.6), for example, it can be 1:0.5, 1:0.51, 1:0.52, 1:0.53, 1:0.54, 1:0.55, 1:0.56, 1:0.57, 1:0.58, 1:0.59 or 1:0.6, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0051] In the present invention, magnesium oxide particles are in-situ synthesized on the surface and between the layers of the composite modified clay by hydrothermal synthesis method, greatly increasing the specific surface area of the composite modified clay, so that the finally obtained high-efficiency granular clay adsorbent has an appropriate number of mesopores, which is beneficial to improving the removal effect of olefins and nitrogen. The present invention specifically limits the mass ratio of the composite modified clay to magnesium chloride in the clay dispersion to 1:(0.5-0.6). During the hydrothermal synthesis process, as the amount of magnesium chloride used increases, the specific surface area of the finally obtained high-efficiency granular clay adsorbent first increases and then decreases. This is because when magnesium chloride and sodium hydroxide are used as reaction raw materials for hydrothermal reaction in the present invention, magnesium hydroxide flocculent precipitate will be generated, and the magnesium hydroxide flocculent precipitate forms magnesium oxide after calcination. After adding an appropriate amount of magnesium chloride, an appropriate amount of nano-magnesium oxide is obtained after reaction and calcination. The appropriate amount of nano-magnesium oxide can be evenly distributed on the surface and between the layers of the composite modified clay and stack with each other to form more new pores, thereby increasing the porosity of the composite modified clay. When the amount of magnesium chloride used exceeds the upper limit of the range defined in the present invention, too much magnesium hydroxide flocculent precipitate is generated, resulting in the surface pores of the composite modified clay being covered by too much magnesium hydroxide. During the calcination process, magnesium hydroxide will decompose into nano-magnesium oxide, and the nano-magnesium oxide is prone to agglomeration due to its high surface energy, resulting in the surface voids of the composite modified clay being blocked by the agglomerated magnesium oxide, causing the porosity to decrease.

[0052] In some alternative examples, the mixing and stirring time of the clay dispersion and magnesium chloride is 1-2 h, for example, it can be 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h or 2.0 h, but is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0053] In some alternative embodiments, the heating temperature during the mixing and stirring of the clay dispersion and magnesium chloride is 50 to 60 °C. For example, it can be 50 °C, 51 °C, 52 °C, 53 °C, 54 °C, 55 °C, 56 °C, 57 °C, 58 °C, 59 °C, or 60 °C. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0054] In some alternative embodiments, the molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide in the intermediate solution is (0.5 to 0.7):1. For example, it can be 0.5:1, 0.52:1, 0.54:1, 0.56:1, 0.58:1, 0.6:1, 0.62:1, 0.64:1, 0.66:1, 0.68:1, or 0.7:1. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0055] In some alternative embodiments, the mixing and stirring time of the intermediate solution and sodium hydroxide is 6 to 8 h. For example, it can be 6.0 h, 6.2 h, 6.4 h, 6.6 h, 6.8 h, 7.0 h, 7.2 h, 7.4 h, 7.6 h, 7.8 h, or 8.0 h. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0056] In some alternative embodiments, the heating temperature during the mixing and stirring of the intermediate solution and sodium hydroxide is 80 to 90 °C. For example, it can be 80 °C, 81 °C, 82 °C, 83 °C, 84 °C, 85 °C, 86 °C, 87 °C, 88 °C, 89 °C, or 90 °C. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0057] In some alternative embodiments, the heating rate of the calcination is 10 to 20 °C / min. For example, it can be 10 °C / min, 11 °C / min, 12 °C / min, 13 °C / min, 14 °C / min, 15 °C / min, 16 °C / min, 17 °C / min, 18 °C / min, 19 °C / min, or 20 °C / min. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0058] In some alternative embodiments, the temperature of the calcination is 440 to 460 °C. For example, it can be 440 °C, 442 °C, 444 °C, 446 °C, 448 °C, 450 °C, 452 °C, 454 °C, 456 °C, 458 °C, or 460 °C. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0059] The present invention specifically limits the calcination temperature to 440 - 460 °C. When the calcination temperature is lower than 440 °C, magnesium hydroxide cannot be fully decomposed; when the calcination temperature is higher than 460 °C, the generated magnesium oxide is prone to agglomeration, which will not only lead to a decrease in the porosity of the high - efficiency particulate clay adsorbent, but also reduce the number of effective adsorption sites.

[0060] In some alternative examples, the calcination time is 2 - 3 h. For example, it can be 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h or 3.0 h, but it is not limited to the listed values, and other unlisted values within this numerical range are equally applicable.

[0061] In a second aspect, the present invention provides an application of a high - efficiency particulate clay adsorbent for olefin / denitrogenation prepared by the preparation method described in the first aspect, and the high - efficiency particulate clay adsorbent is used in the fields of olefin removal and denitrogenation.

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses a mixed acid solution composed of concentrated hydrochloric acid, concentrated sulfuric acid and oxalic acid to perform acid activation treatment on bentonite, which can significantly improve the olefin - removing and denitrogenating abilities of activated clay. On the one hand, during the acidification process, some non - adsorptive impurities, soluble impurities and minerals in bentonite will be decomposed by acid and dissolved in the liquid - phase system, causing partial lattice destruction of bentonite, an increase in the crystal plane spacing, opening of the pore channels of bentonite, an increase in pore diameter and an increase in adsorption sites, thereby enhancing the physical adsorption ability of activated clay for olefins and nitrogen. On the other hand, in terms of olefin removal, the surface of the activated clay after acid activation treatment has a large number of acidic sites, which can cause olefins to undergo alkylation and condensation polymerization reactions, and thus be effectively removed; in terms of denitrogenation, when activating bentonite with the mixed acid, hydrogen ions replace exchangeable metal ions, forming rich acid centers on the surface. The basicity of the basic nitride morpholine lies in the unshared electron pair on its nitrogen atom, which can combine with protons to form a positively charged ion. When the strongly basic morpholine adsorbs on the surface of the activated clay, the acid centers of the activated clay can undergo a neutralization reaction with the nitrogen atom of morpholine, forming the corresponding amine salt and depositing on the surface of the activated clay to achieve the purpose of denitrogenation. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a process flow chart of the preparation of a high - efficiency particulate clay adsorbent for olefin / denitrogenation provided in Examples 1 - 5 of the present invention; Figure 2 It is a schematic structural diagram of the olefin - removal evaluation device adopted by the present invention; Among them, 1 - raw material tank; 2 - feed pump; 3 - reactor; 4 - cooler; 5 - product collection tank; Figure 3 XRD patterns of bentonite, activated clay prepared in Example 1 of the present invention, and composite modified clay Figure 4 Infrared spectra of bentonite and activated clay prepared in Example 1 of the present invention Figure 5 Scanning electron micrograph of Example 1 of the present invention, where Figure 5 (a) Scanning electron micrograph of bentonite powder used in Example 1 of the present invention Figure 5 (b) Scanning electron micrograph of activated clay prepared in Example 1 of the present invention Figure 5 (c) Scanning electron micrograph of composite modified clay prepared in Example 1 of the present invention Figure 5 (d) Scanning electron micrograph of the high-efficiency granular clay adsorbent prepared in Example 1 of the present invention at low magnification Figure 5 (e) Scanning electron micrograph of the high-efficiency granular clay adsorbent prepared in Example 1 of the present invention at high magnification Figure 6 XRD patterns of the activated clay and the high-efficiency granular clay adsorbent prepared in Example 1 of the present invention Detailed implementation manners

[0064] The technical solutions of the present invention will be described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific specific implementation manners of the present invention and are used to illustrate the concept of the present invention; these descriptions are all explanatory and exemplary and should not be construed as limiting the implementation manners of the present invention and the protection scope of the present invention. Except for the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of the present application, and these technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments described herein.

[0065] The chemical reagents used in the specific implementation manners of the present invention are all commercially available products, and their model, specifications, manufacturer information, etc. are as follows: Concentrated hydrochloric acid: analytically pure, purchased from Tianjin Damao Chemical Reagent Factory; Concentrated sulfuric acid: analytically pure, purchased from Tianjin Damao Chemical Reagent Factory; Oxalic acid: analytically pure, purchased from Shandong Zhengxing New Materials Co., Ltd.; Sodium chloride: R21092 - 500ml, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.; Cetyltrimethylammonium bromide: S15001 - 100g, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.; Caprolactam: S70056 - 100g, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.; Silane coupling agent KH550: S15028-500ml, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.; Silane coupling agent KH560: S15029-500ml, purchased from Shanghai Yuanye Bio-Technology Co., Ltd.; Absolute ethanol: analytically pure, purchased from Nanjing Chemical Reagent Co., Ltd.; Magnesium chloride: analytically pure, purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.; Sodium hydroxide: analytically pure, purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.

[0066] Example 1 This example provides a preparation method for an efficient particle bleaching earth adsorbent for olefin / denitrification removal, as Figure 1 shown, the preparation method specifically includes the following steps: (1) Slowly add concentrated hydrochloric acid with a mass fraction of 35wt% to deionized water, and after mixing evenly, obtain dilute hydrochloric acid; subsequently, slowly add concentrated sulfuric acid with a mass fraction of 98wt% to the dilute hydrochloric acid. The volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid, and deionized water is 1:1.4:35. After mixing evenly, obtain a mixed acid solution; finally, add oxalic acid to the mixed acid solution, and after mixing evenly, obtain an acidifying agent. The mass fraction of oxalic acid in the acidifying agent is 5wt%; Crush and screen the raw bentonite ore to obtain bentonite powder with a particle size of 100 mesh. Mix the bentonite powder and deionized water according to a mass ratio of 0.6:1 to obtain a bentonite slurry; mix the bentonite slurry, acidifying agent, and sodium chloride evenly according to a mass ratio of 1:0.6:0.08 to obtain a raw material mixture. Heat the raw material mixture to 80°C and keep it warm for 3h. After the heat preservation ends, continue to raise the temperature to 100°C and keep it warm for 3h. After the heat preservation ends, cool it to room temperature to obtain an activated product; rinse the activated product with deionized water until the pH value of the activated product reaches 4, and then centrifuge at a speed of 3000rpm for 10min. Take the centrifuged precipitate for drying and crushing to obtain activated bleaching earth; (2) Disperse the activated bleaching earth obtained in step (1) in deionized water to obtain a bleaching earth suspension with a mass fraction of 2wt%; under the conditions of continuous stirring and water bath heating at 70°C, add cetyltrimethylammonium bromide to the bleaching earth suspension. The mass ratio of activated bleaching earth to cetyltrimethylammonium bromide is 1:0.3. After adding cetyltrimethylammonium bromide, mix and stir at 70°C in a water bath for 20min, and then add caprolactam. The mass ratio of cetyltrimethylammonium bromide to caprolactam is 2:1. After adding caprolactam, continue to mix and stir at 70°C in a water bath for 4h to carry out the reaction. After the reaction ends, centrifuge at a speed of 7000rpm for 20min, wash and dry the centrifuged precipitate to obtain intercalation-modified bleaching earth; Mix ethanol and deionized water evenly according to a volume ratio of 4:1 to obtain an ethanol aqueous solution. Mix the silane coupling agent and the ethanol aqueous solution evenly to obtain a coupling agent solution with a mass fraction of 1 wt%. Add the intercalated modified bentonite to the coupling agent solution. The mass ratio of the silane coupling agent to the intercalated modified bentonite is 0.02:1. Mix and stir at 70 °C for 5 h to carry out the reaction. After the reaction is completed, filter, wash, and dry to obtain the composite modified bentonite. (3) Disperse the composite modified bentonite obtained in step (2) in deionized water to obtain a bentonite dispersion with a mass fraction of 2 wt%. Add magnesium chloride to the bentonite dispersion. The mass ratio of the composite modified bentonite to magnesium chloride is 1:0.5. Mix and stir at 50 °C for 2 h to obtain an intermediate solution. Add sodium hydroxide to the intermediate solution. The molar ratio of the magnesium ions of magnesium chloride to the hydroxide ions of sodium hydroxide is 0.5:1. Mix and stir at 80 °C for 8 h to carry out the reaction. After the reaction is completed, filter, wash, extrude into pellets, and dry. Heat the dried reaction product to 440 °C at a heating rate of 10 °C / min and hold for 3 h to complete the calcination treatment. After the calcination is completed, crush and screen to obtain the high-efficiency granular bentonite adsorbent.

[0067] Figure 3 XRD patterns of bentonite, activated bentonite prepared in Example 1 of the present invention, and composite modified bentonite. It can be seen from the figure that bentonite shows a strong diffraction peak at 2θ = 7.00°. Using the Bragg equation: 2dsinθ = nλ, where n is taken as 1 and λ is taken as 0.15406 nm, the layer spacing of bentonite can be calculated to be 1.048 nm. Activated bentonite shows a strong diffraction peak at 2θ = 7.96°. Using the Bragg equation, the layer spacing of activated bentonite can be calculated to be 1.455 nm. The composite modified bentonite shows a strong diffraction at 2θ = 6.48°. Using the Bragg equation, the layer spacing of the composite modified bentonite can be calculated to be 2.512 nm. It can be seen that compared with unmodified bentonite, the layer spacing of the activated bentonite obtained after acid activation treatment is significantly increased. This is because during the acid activation process of bentonite, hydrogen ions in the acid replace metal cations in bentonite, enabling interlayer ion exchange in bentonite and further increasing the layer spacing of bentonite. Compared with activated bentonite, the layer spacing of the composite modified bentonite obtained after organic intercalation modification and silane coupling agent surface modification is further increased, the specific surface area is increased, and the number of active sites is increased, which is beneficial to improving the adsorption performance of the composite modified bentonite.

[0068] Figure 4 Infrared spectra of bentonite and activated bentonite prepared in Example 1 of the present invention. By comparison, it can be seen that at 1653 cm -1corresponds to the stretching and bending vibration absorption peaks of water molecule hydroxyl groups in the bentonite crystal structure, 1043 cm -1 , 471 cm -1 and 823 cm -1 correspond to the stretching vibration absorption peak of Si-O, the bending vibration absorption peak of Si-O-Si, and the asymmetric stretching vibration absorption peak of O-Si-O, respectively. The difference between the infrared curves of bentonite and activated clay is that the peak intensity of activated clay increases at 3628 cm -1 in the high-frequency region, which is caused by the O-H stretching vibration. This indicates that during the acid activation treatment, exchangeable cations are replaced by protons, thereby increasing the number of hydroxyl groups available for further functionalization. In addition, the band intensities of the stretching vibration absorption peak of Si-O and the bending vibration absorption peak of Si-O-Si at 1043 cm -1 and 471 cm -1 decrease, and the band intensity of the asymmetric stretching vibration absorption peak of O-Si-O at 823 cm -1 increases, indicating that after the acid activation treatment, due to the change in the Si environment caused by acid corrosion, the organizational structure of activated clay changes and the number of active sites increases.

[0069] Figure 5 (a), Figure 5 (b), Figure 5 (c) and Figure 5 (d) are the scanning electron microscope images of the bentonite powder, the activated clay prepared in this example, the composite modified clay, and the high-efficiency granular clay adsorbent used in this example, respectively. From the comparison of Figure 5 (a) and Figure 5 (b), it can be seen that compared with the bentonite powder, the activated clay has better particle dispersion, larger specific surface area, and higher porosity, and overall shows a loose and regular granular aggregate. From Figure 5 (c), it can be seen that the composite modified clay has higher porosity and more uniform particle size dispersion, a more porous structure, significantly fewer flaky structures, a larger interlayer spacing, and a large number of voids are generated. From Figure 5 (d) and Figure 5 (e), it can be seen that magnesium oxide in the form of a hexagonal flaky structure can be seen on the surface of the high-efficiency granular clay adsorbent, and the accumulation of magnesium oxide generates more pores, forming a mesoporous structure.

[0070] Figure 6XRD patterns of the activated clay and the high-efficiency granular clay adsorbent prepared in this example. As can be seen from the figure, compared with the activated clay, the high-efficiency granular clay adsorbent shows two strong diffraction peaks at 2θ = 42.9° and 62.2°, corresponding to the (200) and (220) crystal planes respectively. The positions of these two diffraction peaks are consistent with the standard XRD pattern of magnesium oxide, indicating that magnesium oxide has been successfully loaded onto the high-efficiency granular clay adsorbent prepared in the invention. In addition, the diffraction peaks of the XRD of the high-efficiency granular clay adsorbent are significantly broadened and relatively sharp, indicating that the loaded magnesium oxide particles are small in particle size and have good crystallinity.

[0071] Example 2 This example provides a preparation method for a high-efficiency granular clay adsorbent for olefin / denitrification, as Figure 1 shown. The specific preparation method includes the following steps: (1) Slowly add concentrated hydrochloric acid with a mass fraction of 35.5 wt% to deionized water, and mix evenly to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 97 wt% to the dilute hydrochloric acid. The volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water is 1:1.45:36, and mix evenly to obtain a mixed acid solution; finally, add oxalic acid to the mixed acid solution and mix evenly to obtain an acidifying agent, and the mass fraction of oxalic acid in the acidifying agent is 6 wt%; Crush and screen the original bentonite ore to obtain bentonite powder with a particle size of 120 mesh. Mix the bentonite powder and deionized water according to a mass ratio of 0.62:1 to obtain a bentonite slurry; mix the bentonite slurry, the acidifying agent and sodium chloride evenly according to a mass ratio of 1:0.62:0.085 to obtain a raw material mixture. Heat the raw material mixture to 82 °C and keep it warm for 2.8 h. After the heat preservation is completed, continue to heat up to 102 °C and keep it warm for 2.8 h. After the heat preservation is completed, cool it to room temperature to obtain an activated product; rinse the activated product with deionized water until the pH value of the activated product reaches 4.2, then centrifuge at a speed of 3200 rpm for 8 min, and take the centrifuged precipitate for drying and pulverization to obtain activated clay; (2) Disperse the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 3 wt%. Under continuous stirring and water bath heating at 72 °C, add cetyltrimethylammonium bromide to the clay suspension. The mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.35. After adding cetyltrimethylammonium bromide, mix and stir at 72 °C under water bath heating for 18 min. Then add caprolactam. The mass ratio of cetyltrimethylammonium bromide to caprolactam is 2.2:1. After adding caprolactam, continue to mix and stir at 72 °C under water bath heating for 3.8 h to carry out the reaction. After the reaction is completed, centrifuge at a speed of 7200 rpm for 18 min. Wash and dry the precipitate obtained after centrifugation to obtain the intercalation-modified clay; Mix ethanol and deionized water evenly according to a volume ratio of 4.2:1 to obtain an ethanol aqueous solution. Mix the silane coupling agent and the ethanol aqueous solution evenly to obtain a coupling agent solution with a mass fraction of 2 wt%. Add the intercalation-modified clay to the coupling agent solution. The mass ratio of the silane coupling agent to the intercalation-modified clay is 0.03:1. Under heating conditions at 72 °C, mix and stir for 4.5 h to carry out the reaction. After the reaction is completed, filter, wash and dry to obtain the composite-modified clay; (3) Disperse the composite-modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 3 wt%. Add magnesium chloride to the clay dispersion. The mass ratio of the composite-modified clay to magnesium chloride is 1:0.52. Under heating conditions at 52 °C, mix and stir for 1.8 h to obtain an intermediate solution. Add sodium hydroxide to the intermediate solution. The molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide is 0.55:1. Under heating conditions at 82 °C, mix and stir for 7.5 h to carry out the reaction. After the reaction is completed, filter, wash, extrude into pellets and dry. Heat the dried reaction product to 445 °C at a heating rate of 12 °C / min and hold for 2.8 h to complete the calcination treatment. After the calcination is completed, crush and screen to obtain the high-efficiency granular clay adsorbent.

[0072] Example 3 This example provides a preparation method for a high-efficiency granular clay adsorbent for olefin / nitrogen removal, as Figure 1 shown. The specific preparation method includes the following steps: (1) Slowly add concentrated hydrochloric acid with a mass fraction of 36 wt% to deionized water, and mix evenly to obtain dilute hydrochloric acid. Then slowly add concentrated sulfuric acid with a mass fraction of 96 wt% to the dilute hydrochloric acid. The volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water is 1:1.5:37. Mix evenly to obtain a mixed acid solution. Finally, add oxalic acid to the mixed acid solution and mix evenly to obtain an acidifying agent. The mass fraction of oxalic acid in the acidifying agent is 7 wt%; The original bentonite ore is crushed and sieved to obtain bentonite powder with a particle size of 150 mesh. The bentonite powder is mixed with deionized water at a mass ratio of 0.65:1 to obtain a bentonite slurry. The bentonite slurry, acidifying agent and sodium chloride are mixed evenly at a mass ratio of 1:0.65:0.09 to obtain a raw material mixture. The raw material mixture is heated to 85 °C and kept warm for 2.5 h. After the heat preservation is completed, the temperature is continued to be raised to 105 °C and kept warm for 2.5 h. After the heat preservation is completed, it is cooled to room temperature to obtain an activated product. The activated product is rinsed with deionized water until the pH value of the activated product reaches 4.5. Subsequently, it is centrifuged at a speed of 3500 rpm for 7 min. The centrifuged precipitate is taken for drying and pulverization to obtain activated clay. (2) The activated clay obtained in step (1) is dispersed in deionized water to obtain a white clay suspension with a mass fraction of 4 wt%. Under the conditions of continuous stirring and water bath heating at 75 °C, cetyltrimethylammonium bromide is added to the white clay suspension. The mass ratio of the activated clay to cetyltrimethylammonium bromide is 1:0.4. After adding cetyltrimethylammonium bromide, it is mixed and stirred for 15 min under the conditions of water bath heating at 75 °C. Subsequently, caprolactam is added. The mass ratio of cetyltrimethylammonium bromide to caprolactam is 2.5:1. After adding caprolactam, it is continued to be mixed and stirred for 3.5 h under the conditions of water bath heating at 75 °C to carry out the reaction. After the reaction is completed, it is centrifuged at a speed of 7500 rpm for 15 min. The centrifuged precipitate is washed and dried to obtain intercalation-modified clay. Ethanol and deionized water are mixed evenly at a volume ratio of 4.5:1 to obtain an ethanol aqueous solution. A silane coupling agent and the ethanol aqueous solution are mixed evenly to obtain a coupling agent solution with a mass fraction of 3 wt%. The intercalation-modified clay is added to the coupling agent solution. The mass ratio of the silane coupling agent to the intercalation-modified clay is 0.03:1. It is mixed and stirred for 4 h under the heating condition of 75 °C to carry out the reaction. After the reaction is completed, it is filtered, washed and dried to obtain composite-modified clay. (3) The composite-modified clay obtained in step (2) is dispersed in deionized water to obtain a white clay dispersion with a mass fraction of 3 wt%. Magnesium chloride is added to the white clay dispersion. The mass ratio of the composite-modified clay to magnesium chloride is 1:0.55. It is mixed and stirred for 1.5 h under the heating condition of 55 °C to obtain an intermediate solution. Sodium hydroxide is added to the intermediate solution. The molar ratio of the magnesium ions of magnesium chloride to the hydroxide ions of sodium hydroxide is 0.6:1. It is mixed and stirred for 7 h under the heating condition of 85 °C to carry out the reaction. After the reaction is completed, it is filtered, washed, extruded into strips and dried. The dried reaction product is heated to 450 °C at a heating rate of 15 °C / min and kept warm for 2.5 h to complete the calcination treatment. After the calcination is completed, it is crushed and sieved to obtain the high-efficiency granular clay adsorbent.

[0073] Example 4 This embodiment provides a preparation method for an efficient olefin / nitrogen removal granular clay adsorbent, as follows Figure 1 shown. The preparation method specifically includes the following steps: (1) Slowly add concentrated hydrochloric acid with a mass fraction of 36.5 wt% to deionized water, and after mixing evenly, obtain dilute hydrochloric acid; subsequently, slowly add concentrated sulfuric acid with a mass fraction of 96 wt% to the dilute hydrochloric acid. The volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid, and deionized water is 1:1.55:38. After mixing evenly, obtain a mixed acid solution; finally, add oxalic acid to the mixed acid solution and mix evenly to obtain an acidifying agent, and the mass fraction of oxalic acid in the acidifying agent is 8 wt%; Crush and screen the original bentonite ore to obtain bentonite powder with a particle size of 180 mesh. Mix the bentonite powder and deionized water according to a mass ratio of 0.68:1 to obtain a bentonite slurry; mix the bentonite slurry, acidifying agent, and sodium chloride evenly according to a mass ratio of 1:0.68:0.095 to obtain a raw material mixture. Heat the raw material mixture to 88 °C and keep it warm for 2.2 h. After the heat preservation ends, continue to heat up to 108 °C and keep it warm for 2.2 h. After the heat preservation ends, cool it to room temperature to obtain an activated product; rinse the activated product with deionized water until the pH value of the activated product reaches 4.8, and then centrifuge at a speed of 3800 rpm for 6 min. Take the centrifuged precipitate for drying and pulverization to obtain activated clay; (2) Disperse the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 4 wt%; under the conditions of continuous stirring and water bath heating at 78 °C, add cetyltrimethylammonium bromide to the clay suspension. The mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.45. After adding cetyltrimethylammonium bromide, mix and stir at 78 °C under the conditions of water bath heating for 12 min, and then add caprolactam. The mass ratio of cetyltrimethylammonium bromide to caprolactam is 2.8:1. After adding caprolactam, continue to mix and stir at 78 °C under the conditions of water bath heating for 3.2 h to carry out the reaction. After the reaction ends, centrifuge at a speed of 7800 rpm for 12 min, wash and dry the centrifuged precipitate to obtain intercalation-modified clay; Mix ethanol and deionized water evenly according to a volume ratio of 4.8:1 to obtain an ethanol aqueous solution. Mix the silane coupling agent and the ethanol aqueous solution evenly to obtain a coupling agent solution with a mass fraction of 4 wt%. Add the intercalation-modified clay to the coupling agent solution. The mass ratio of the silane coupling agent to the intercalation-modified clay is 0.04:1. Mix and stir at 78 °C under the heating conditions for 3.5 h to carry out the reaction. After the reaction ends, filter, wash, and dry to obtain composite-modified clay; (3) Disperse the composite modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 4 wt%; add magnesium chloride to the clay dispersion, and the mass ratio of the composite modified clay to magnesium chloride is 1:0.58. Mix and stir at 58 °C for 1.2 h to obtain an intermediate solution; add sodium hydroxide to the intermediate solution, and the molar ratio of magnesium ions in magnesium chloride to hydroxide ions in sodium hydroxide is 0.65:1. Mix and stir at 88 °C for 6.5 h to cause a reaction. After the reaction is completed, filter, wash, extrude into pellets and dry. Heat the dried reaction product to 455 °C at a heating rate of 18 °C / min and hold for 2.2 h to complete the calcination treatment. After the calcination is completed, crush and screen to obtain the high-efficiency granular clay adsorbent.

[0074] Example 5 This example provides a preparation method for a high-efficiency granular clay adsorbent for olefin / nitrogen removal, as Figure 1 shown. The specific preparation method includes the following steps: (1) Slowly add concentrated hydrochloric acid with a mass fraction of 37 wt% to deionized water, and after mixing evenly, obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 95 wt% to the dilute hydrochloric acid. The volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water is 1:1.6:40. After mixing evenly, obtain a mixed acid solution; finally add oxalic acid to the mixed acid solution, and after mixing evenly, obtain an acidifying agent. The mass fraction of oxalic acid in the acidifying agent is 10 wt%; Crush and screen the original bentonite ore to obtain bentonite powder with a particle size of 200 mesh. Mix the bentonite powder and deionized water according to a mass ratio of 0.7:1 to obtain a bentonite slurry; mix the bentonite slurry, acidifying agent and sodium chloride evenly according to a mass ratio of 1:0.7:0.1 to obtain a raw material mixture. Heat the raw material mixture to 90 °C and hold for 2 h. After the holding is completed, continue to heat to 110 °C and hold for 2 h. After the holding is completed, cool to room temperature to obtain an activated product; rinse the activated product with deionized water until the pH value of the activated product reaches 5, and then centrifuge at 4000 rpm for 5 min. Take the centrifuged precipitate for drying and crushing to obtain activated clay; (2) Disperse the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 5 wt%. Under continuous stirring and water bath heating at 80 °C, add cetyltrimethylammonium bromide to the clay suspension. The mass ratio of the activated clay to cetyltrimethylammonium bromide is 1:0.5. After adding cetyltrimethylammonium bromide, mix and stir at 80 °C under water bath heating for 10 min, and then add caprolactam. The mass ratio of cetyltrimethylammonium bromide to caprolactam is 3:1. After adding caprolactam, continue to mix and stir at 80 °C under water bath heating for 3 h to carry out the reaction. After the reaction is completed, centrifuge at a speed of 8000 rpm for 10 min, wash and dry the precipitate obtained after centrifugation to obtain the intercalation-modified clay; Mix ethanol and deionized water evenly according to a volume ratio of 5:1 to obtain an ethanol aqueous solution. Mix the silane coupling agent and the ethanol aqueous solution evenly to obtain a coupling agent solution with a mass fraction of 5 wt%. Add the intercalation-modified clay to the coupling agent solution. The mass ratio of the silane coupling agent to the intercalation-modified clay is 0.05:1. Mix and stir at 80 °C under heating for 3 h to carry out the reaction. After the reaction is completed, filter, wash and dry to obtain the composite-modified clay; (3) Disperse the composite-modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 5 wt%. Add magnesium chloride to the clay dispersion. The mass ratio of the composite-modified clay to magnesium chloride is 1:0.6. Mix and stir at 60 °C under heating for 1 h to obtain an intermediate solution. Add sodium hydroxide to the intermediate solution. The molar ratio of the magnesium ions of magnesium chloride to the hydroxide ions of sodium hydroxide is 0.7:1. Mix and stir at 90 °C under heating for 6 h to carry out the reaction. After the reaction is completed, filter, wash, extrude and shape, and dry. Heat the dried reaction product to 460 °C at a heating rate of 20 °C / min and hold for 2 h to complete the calcination treatment. After the calcination is completed, crush and screen to obtain the high-efficiency granular clay adsorbent.

[0075] Comparative Example 1 This comparative example provides a preparation method for a high-efficiency granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that in the preparation process of the acidifying agent, concentrated hydrochloric acid is omitted, concentrated sulfuric acid is slowly added to deionized water, and after mixing evenly, dilute sulfuric acid is obtained. Subsequently, oxalic acid is added to the dilute sulfuric acid, and after mixing evenly, the acidifying agent is obtained. Other process parameters and operation steps are exactly the same as those in Example 1.

[0076] Comparative Example 2 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that during the preparation of the acidifying agent, concentrated sulfuric acid is omitted, concentrated hydrochloric acid is slowly added to deionized water, and after mixing evenly, dilute hydrochloric acid is obtained. Subsequently, oxalic acid is added to the dilute hydrochloric acid, and after mixing evenly, the acidifying agent is obtained. Other process parameters and operating steps are exactly the same as those in Example 1.

[0077] Comparative Example 3 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that during the preparation of the acidifying agent, oxalic acid is omitted, concentrated hydrochloric acid is slowly added to deionized water, and after mixing evenly, dilute hydrochloric acid is obtained. Subsequently, concentrated sulfuric acid is slowly added to the dilute hydrochloric acid, and after mixing evenly, the acidifying agent is obtained. Other process parameters and operating steps are exactly the same as those in Example 1.

[0078] Comparative Example 4 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that the mass ratio of activated clay to cetyltrimethylammonium bromide in the clay suspension is adjusted to 1:0.2. Other process parameters and operating steps are exactly the same as those in Example 1.

[0079] Comparative Example 5 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that the mass ratio of activated clay to cetyltrimethylammonium bromide in the clay suspension is adjusted to 1:0.6. Other process parameters and operating steps are exactly the same as those in Example 1.

[0080] Comparative Example 6 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that the mass ratio of cetyltrimethylammonium bromide to caprolactam is adjusted to 1.5:1. Other process parameters and operating steps are exactly the same as those in Example 1.

[0081] Comparative Example 7 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that the mass ratio of cetyltrimethylammonium bromide to caprolactam is adjusted to 3.5:1. Other process parameters and operating steps are exactly the same as those in Example 1.

[0082] Comparative Example 8 This comparative example provides a preparation method for an efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that the mass ratio of the composite modified clay to magnesium chloride in the clay dispersion is adjusted to 1:0.3. Other process parameters and operating steps are exactly the same as those in Example 1.

[0083] Comparative Example 9 This comparative example provides a preparation method for a highly efficient granular clay adsorbent for olefin / denitrification. The difference from Example 1 is that the mass ratio of the composite modified clay to magnesium chloride in the clay dispersion is adjusted to 1:0.8, and other process parameters and operating steps are exactly the same as those in Example 1.

[0084] The activity, pore size, denitrification rate, and olefin removal rate of the highly efficient granular clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-9 were tested. The specific test steps are as follows: (1)Activity test: Activity is an important index to measure the adsorption performance of activated clay. Usually, the volume (mL) of the NaOH standard solution [c(NaOH = 1.000 mol / L)] consumed to neutralize 1000 g of the clay sample is used to represent the activity.

[0085] In this invention, referring to the industry standard HG / T 2569-2007 "Activated Clay", the activity of the highly efficient granular clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-9 was determined.

[0086] (2)Pore size test: A fully automatic gas adsorption analyzer was used to analyze and detect the pore size of the sample. Before the test, it was degassed under vacuum conditions at 150 °C for 7 h, and then the nitrogen adsorption-desorption performance test was carried out.

[0087] (3)Denitrification rate test: The raw material for denitrification activity evaluation was the aromatics raffinate oil provided by a certain petrochemical company, with a nitrogen content of 12.51 μg / g.

[0088] The denitrification evaluation device was a tubular fixed-bed reaction device. The outside of the reaction device was equipped with an electric heating temperature control system. 100 g of the adsorbent was filled in the catalyst bed layer of the reaction device. The aromatics raffinate oil was metered and pumped to a pressure of 0.8 MPa, and then entered the preheater at a certain space velocity. After being heated to 40 °C, it entered the adsorbent bed layer. The denitrified and refined raffinate oil product entered the low-pressure separator after cooling, and the refined product was sampled and analyzed regularly. When the nitrogen content in the refined product was greater than 0.5 μg / g, it was regarded as the inactivation standard of the solid adsorbent.

[0089] The total nitrogen content in the raw material and the product was determined by SH / T 0657-2007 "Determination of Trace Nitrogen in Liquid Petroleum Hydrocarbons - Oxidative Combustion and Chemiluminescence Method", and the denitrification rate was calculated through the total nitrogen content in the raw material and the total nitrogen content in the product.

[0090] (4)Olefin removal rate test: The raw material for the deolefination activity evaluation is the reformate provided by a petrochemical company, with a bromine index of 670 mgBr / 100 g.

[0091] The deolefination evaluation device is as Figure 2 shown, including a raw material tank 1, a feed pump 2, a reactor 3, a cooler 4, and a product collection tank 5. The reactor 3 is divided into upper, middle, and lower sections. A certain amount of 20 - 40 mesh quartz sand is filled in the upper and lower sections respectively. The middle section is a constant temperature section, where 5 mL of adsorbent is loaded and tamped with a leather hammer. The evaluation conditions are a temperature of 170 °C, a pressure of 1 MPa, and a volume space velocity of 10 h -1 . Samples are taken every 2 h. The bromine index of the raw material and the product is measured using the national standard GB / T 5177 - 2017 "Industrial Linear Alkylbenzene". The smaller the bromine index of the aromatics deolefination product, the lower the olefin content, indicating that the deolefination effect of the adsorbent is better.

[0092] The olefin removal rate of the aromatics product is calculated using the following formula: The test results are shown in Table 1.

[0093] Table 1 Performance test results of the high - efficiency granular clay adsorbents prepared in Examples 1 - 5 and Comparative Examples 1 - 9 It can be seen from the test data provided in Table 1 that the high - efficiency granular clay adsorbent prepared by the present invention has a relatively high activity and a relatively large pore size, enabling it to show good removal rates in the fields of deolefination and denitrification. The test results show that the activity of the high - efficiency granular clay adsorbent prepared by the present invention exceeds 215 mmol / 100 g, indicating that it has extremely strong adsorption activity and reaction ability, enabling the adsorbent to interact more effectively with target substances (such as nitrogen compounds and olefins), thereby improving the adsorption efficiency and removal rate. In addition, the average pore size of the high - efficiency granular clay adsorbent prepared by the present invention exceeds 36 nm. The large pore size not only facilitates the rapid diffusion and transmission of adsorbates (such as nitrogen and olefin molecules), but also provides more adsorption sites, thereby enhancing the adsorption capacity and adsorption rate. Under the combined action of high activity and large pore size, the denitrification rate of the high - efficiency granular clay adsorbent prepared by the present invention in the denitrification activity evaluation test is as high as over 95%, and the olefin removal rate in the deolefination activity evaluation test is as high as over 90%. This data fully demonstrates the significant advantages of the clay adsorbent prepared by the present invention in deolefination and denitrification.

[0094] It can be seen from the test data of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 that the denitrification rate and olefin removal rate of Comparative Example 1, Comparative Example 2 and Comparative Example 3 are all lower than those of Example 1. This is because hydrochloric acid is omitted in the acidifying agent of Comparative Example 1, sulfuric acid is omitted in the acidifying agent of Comparative Example 2, and oxalic acid is omitted in the acidifying agent of Comparative Example 3. This shows that the acidification modification of bentonite with the mixed acid solution composed of hydrochloric acid, sulfuric acid and oxalic acid in the present invention can effectively improve the activity and pore size of activated clay, thereby greatly improving the adsorption capacity of the high-efficiency granular clay adsorbent.

[0095] It can be seen from the test data of Example 1, Comparative Example 4 and Comparative Example 5 that the denitrification rate and olefin removal rate of Comparative Example 4 and Comparative Example 5 are all lower than those of Example 1. This is because the dosage of cetyltrimethylammonium bromide in Comparative Example 4 is too low, and the dosage of cetyltrimethylammonium bromide in Comparative Example 5 is too high. The dosage of cetyltrimethylammonium bromide will directly affect the intercalation modification effect of activated clay, and thus affect the adsorption capacity of the high-efficiency granular clay adsorbent.

[0096] It can be seen from the test data of Example 1, Comparative Example 6 and Comparative Example 7 that the denitrification rate and olefin removal rate of Comparative Example 6 and Comparative Example 7 are all lower than those of Example 1. This is because the dosage of cetyltrimethylammonium bromide in Comparative Example 6 is too low, while the dosage of caprolactam is relatively too high; the dosage of cetyltrimethylammonium bromide in Comparative Example 7 is too high, while the dosage of caprolactam is relatively too low. The ratio of cetyltrimethylammonium bromide and caprolactam will directly affect the intercalation modification effect of activated clay, and thus affect the adsorption capacity of the high-efficiency granular clay adsorbent.

[0097] It can be seen from the test data of Example 1, Comparative Example 8 and Comparative Example 9 that the denitrification rate and olefin removal rate of Comparative Example 8 and Comparative Example 9 are all lower than those of Example 1. This is because the dosage of magnesium chloride in Comparative Example 8 is too low, resulting in less magnesium oxide finally generated and unable to effectively increase the pore size of the high-efficiency granular clay adsorbent; in Comparative Example 9, the dosage of magnesium chloride is too high, resulting in excessive aggregation of the generated magnesium oxide, which will also affect the pore size of the high-efficiency granular clay adsorbent and finally lead to a decrease in the adsorption capacity of the high-efficiency granular clay adsorbent.

[0098] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a highly efficient granular clay adsorbent for deolefination / denitrification, characterized in that: The preparation method comprises: (I) mixing concentrated hydrochloric acid, concentrated sulfuric acid, oxalic acid and deionized water to obtain an acidifier, crushing and sieving bentonite ore to obtain bentonite powder, mixing the bentonite powder with deionized water to obtain bentonite slurry; uniformly mixing the bentonite slurry, the acidifier and sodium chloride to obtain a raw material mixture, heating and activating the raw material mixture to obtain an activated product, rinsing, centrifuging, drying and crushing the activated product to obtain activated clay; (II) using hexadecyltrimethylammonium bromide and caprolactam to carry out organic intercalation modification treatment on the activated clay obtained in step (I) to obtain intercalation modified clay; then, using a silane coupling agent to carry out surface hydrophobic modification treatment on the intercalation modified clay to obtain composite modified clay; (III) dispersing the composite modified clay obtained in step (II) in deionized water to obtain a clay dispersion; adding magnesium chloride to the clay dispersion, mixing, stirring and heating to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, mixing, stirring and heating to react, filtering, washing, extruding, drying, calcining and crushing and screening after the reaction is completed to obtain the high-efficiency granular clay adsorbent.

2. The preparation method according to claim 1, characterized in that: In step (I), when preparing the acidulant, the concentrated hydrochloric acid is first slowly added to deionized water, and the mixture is mixed to obtain dilute hydrochloric acid; then concentrated sulfuric acid is slowly added to the dilute hydrochloric acid to obtain a mixed acid solution; finally, oxalic acid is added to the mixed acid solution, and the mixture is mixed to obtain the acidulant.

3. The preparation method according to claim 2, characterized in that: The mass fraction of the concentrated hydrochloric acid is 35-37wt%; The mass fraction of the concentrated sulfuric acid is 95-98wt%; The volume ratio of the concentrated hydrochloric acid, the concentrated sulfuric acid and the deionized water is 1:(1.4-1.6):(35-40); The mass fraction of oxalic acid in the acidulant is 5-10wt%.

4. The preparation method according to claim 1, characterized in that: In step (I), the particle size of the bentonite powder is 100-200 mesh; The bentonite powder and deionized water are mixed in a mass ratio of (0.6-0.7):1 to obtain the bentonite slurry; The mass ratio of the bentonite slurry, the acidulant and sodium chloride is 1:(0.6-0.7):(0.08-0.1); The heating activation operation steps include: The raw material mixture is heated to a first activation temperature and kept warm, and then the temperature is further raised to a second activation temperature and kept warm after the insulation is completed, and then the temperature is cooled to room temperature after the insulation is completed to obtain the activated product; The first activation temperature is 80-90°C; Keeping the temperature at the first activation temperature for 2 to 3 hours; The second activation temperature is 100-110°C; Keeping the temperature at the second activation temperature for 2 to 3 hours; The activated product is rinsed with deionized water until the pH value of the activated product reaches 4-5; The centrifugal speed is 3000-4000 rpm; The centrifugation time is 5 to 10 minutes.

5. The preparation method according to claim 1, characterized in that: In step (II), the operation steps of the organic intercalation modification treatment include: The activated clay is dispersed in deionized water to obtain a clay suspension; under continuous stirring and water bath heating conditions, hexadecyltrimethylammonium bromide and caprolactam are sequentially added to the clay suspension to react, and after the reaction is completed, centrifugation is performed, and the precipitate obtained after centrifugation is washed and dried to obtain the intercalated modified clay.

6. The preparation method according to claim 5, characterized in that: The mass fraction of the activated clay in the clay suspension is 2-5wt%; The mass ratio of activated clay to hexadecyltrimethylammonium bromide in the clay suspension is 1:(0.3-0.5); The mass ratio of the hexadecyltrimethylammonium bromide to the caprolactam is (2-3):1; The water bath heating temperature is 70-80°C; After adding hexadecyltrimethylammonium bromide to the clay suspension, continue mixing and stirring under water bath heating conditions for 10 to 20 minutes, and then add caprolactam; After adding caprolactam, continue mixing and stirring under heating in a water bath for 3 to 4 hours; The centrifugal speed is 7000-8000 rpm; The centrifugation time is 10 to 20 minutes.

7. The preparation method according to claim 1, characterized in that: In step (II), the surface hydrophobic modification treatment comprises: The silane coupling agent and the ethanol aqueous solution are uniformly mixed to obtain a coupling agent solution, the intercalated modified clay is added to the coupling agent solution, mixed and stirred and heated to react, and after the reaction is completed, filtered, washed and dried to obtain the composite modified clay.

8. The preparation method according to claim 7, characterized in that: The volume ratio of ethanol to deionized water in the ethanol aqueous solution is (4-5):1; The mass fraction of the silane coupling agent in the coupling agent solution is 1-5wt%; The mass ratio of the silane coupling agent in the coupling agent solution to the intercalation modified clay is (0.02-0.05):1; The reaction temperature of the intercalation modified clay and the coupling agent solution is 70-80°C; The reaction time of the intercalated modified clay and the coupling agent solution is 3 to 5 hours.

9. The preparation method according to claim 1, characterized in that: In step (III), the mass fraction of the composite modified clay in the clay dispersion is 2-5wt%; The mass ratio of the composite modified clay to magnesium chloride in the clay dispersion is 1:(0.5-0.6); The mixing time of the clay dispersion and magnesium chloride is 1 to 2 hours; The heating temperature of the clay dispersion and magnesium chloride during mixing and stirring is 50-60°C; The molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide in the intermediate solution is (0.5-0.7):1; The mixing time of the intermediate solution and sodium hydroxide is 6 to 8 hours; The heating temperature of the intermediate solution and sodium hydroxide during mixing and stirring is 80-90°C; The heating rate of the calcination is 10-20°C / min; The calcination temperature is 440-460°C; The calcination time is 2 to 3 hours.

10. An application of a highly efficient granular clay adsorbent for deolefination / denitrification prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The high-efficiency granular clay adsorbent is used in the fields of olefin removal and nitrogen removal.

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