Preparation method and application of granular clay adsorbent for deolefination or denitrification

Abstract

The present invention provides a preparation method and application of a granular clay adsorbent for deolefination or denitrification, comprising: organically intercalating activated clay using hexadecyltrimethylammonium bromide and caprolactam to obtain intercalated modified clay; surface hydrophobicizing the intercalated modified clay using a silane coupling agent to obtain a composite modified clay; adding magnesium chloride to a clay dispersion to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, mixing, stirring, and heating to react, and obtaining a high-efficiency granular clay adsorbent after the reaction. The present invention synthesizes nanomagnesium oxide on the surface and between layers of the composite modified clay through a hydrothermal synthesis reaction of magnesium chloride and sodium hydroxide. The stacking of the nanomagnesium oxide creates more new voids, resulting in a high-efficiency granular clay adsorbent with a high specific surface area and high porosity.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry and relates to a preparation method and application of a granular clay adsorbent for deolefination or denitrification. Background Art

[0002] Bentonite, also known as kaolin, is a natural, multifunctional clay mineral primarily composed of montmorillonite, with small amounts of impurities such as quartz and feldspar. Due to its unique layered structure and large surface area, kaolin exhibits excellent adsorption, ion exchange, and catalytic properties. It plays an irreplaceable role in various fields, including petrochemicals, environmental protection, and daily chemicals. In particular, kaolin, as an adsorbent, can effectively remove impurities from oil products, improving product purity and quality.

[0003] In the field of deolefination, the application of bleaching clay is primarily focused on the refining of aromatics and the treatment of reformate oil. Aromatics are important raw materials in the petrochemical industry, but their production process is often accompanied by the formation of impurities such as olefins. These impurities not only affect the purity of the aromatics but can also adversely affect subsequent processing. Traditionally, bleaching clay adsorption has been used to effectively remove these olefin impurities and improve the purity of aromatics. However, with the increasing demand for oil quality, the application of traditional bleaching clay adsorbents in the deolefination field faces numerous challenges. First, bleaching clay's limited adsorption capacity makes it difficult to meet the needs of large-scale production of high-purity aromatics. Second, bleaching clay easily reaches adsorption saturation during use, resulting in a short service life. Frequent adsorbent replacement not only increases production costs but also affects production efficiency. Furthermore, bleaching clay is easily deactivated under harsh operating conditions such as high temperature or high pressure, limiting its application in certain specialized processes.

[0004] In addition to olefin removal, bleaching clay also has applications in nitrogen removal. In oil products, alkaline nitrogen compounds are a key factor affecting oil quality and stability. Through the adsorption action of bleaching clay, these nitrogen compounds can be effectively removed, improving oil quality. However, the application of bleaching clay in nitrogen removal also faces numerous limitations. Firstly, bleaching clay's denitrification capacity is relatively weak, and its adsorption capacity is relatively low, making it difficult to meet the requirements of high nitrogen removal rates. Secondly, the disposal of spent bleaching clay is an increasingly prominent issue. Wasted bleaching clay contains a large number of harmful substances, which, if not handled properly, can cause serious environmental pollution. Summary of the Invention

[0005] In response to the shortcomings of the prior art, the present invention aims to provide a preparation method and application of a granular clay adsorbent for deolefination or denitrification. The present invention first treats the bentonite ore with a specific acidifying agent, effectively improving the activation effect of the bentonite and laying a solid foundation for subsequent modification. The activated clay is then organically intercalated with hexadecyltrimethylammonium bromide and caprolactam to further enhance the interlayer structure and adsorption performance of the activated clay. Subsequently, a silane coupling agent is used to perform surface hydrophobic modification, so that the activated clay maintains high adsorption capacity while having good hydrophobic properties, thereby 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 interlayer of the composite modified clay. More new pores are formed by the stacking of nano-magnesium oxide, and ultimately a high-efficiency granular clay adsorbent with high activity and large pore size is obtained.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / denitrification, the preparation method comprising:

[0008] (I) Concentrated hydrochloric acid, concentrated sulfuric acid, oxalic acid, and deionized water are mixed to obtain an acidifier, bentonite ore is crushed and sieved to obtain bentonite powder, and the bentonite powder is mixed with deionized water to obtain a bentonite slurry; the bentonite slurry, the acidifier, and sodium chloride are uniformly mixed to obtain a raw material mixture, the raw material mixture is heated and activated to obtain an activated product, and the activated product is rinsed, centrifuged, dried, and crushed to obtain activated clay;

[0009] (II) performing an organic intercalation modification treatment on the activated clay obtained in step (I) using hexadecyltrimethylammonium bromide and caprolactam to obtain intercalation modified clay; subsequently, performing a surface hydrophobic modification treatment on the intercalation modified clay using a silane coupling agent to obtain a composite modified clay;

[0010] (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; and after the reaction is completed, filtering, washing, extruding, drying, calcining, and crushing and screening to obtain the high-efficiency granular clay adsorbent.

[0011] The present invention first treats the bentonite ore with a specific acidifying agent, effectively improving the activation effect of the bentonite and laying a solid foundation for subsequent modification treatment. Cetyltrimethylammonium bromide and caprolactam are used to organically intercalate the activated clay, further enhancing the interlayer structure and adsorption performance of the activated clay. Subsequently, a silane coupling agent is used to perform surface hydrophobic modification, so that the activated clay has good hydrophobic properties while maintaining its efficient adsorption capacity, thereby 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 interlayer of the composite modified clay. 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.

[0012] 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 deolefination and denitrification capabilities of the activated white clay. On the one hand, during the acidification process, some non-adsorbable impurities, soluble impurities, and minerals in the bentonite are decomposed by the acid and dissolved in the liquid phase system, so that part of the bentonite crystal lattice is destroyed, the interplanar spacing is increased, the pores of the bentonite are opened, the pore diameter is increased, and the number of adsorption sites is increased, thereby improving the physical adsorption capacity of the activated white 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 reactions, thereby being effectively removed; in terms of denitrification, when the bentonite is activated with a mixed acid, hydrogen ions replace exchangeable metal ions, forming abundant acid centers on the surface. The alkalinity of the alkaline nitride morpholine lies in the fact that its nitrogen atom contains unshared electron pairs, which can combine with protons to form positively charged ions. When the highly alkaline morpholine is adsorbed on the surface of the activated clay, the acid centers of the activated clay can react with the nitrogen atoms of the morpholine to form corresponding amine salts that are deposited on the surface of the activated clay, thereby achieving the purpose of denitrification.

[0013] The activated clay obtained after acidification is hydrophilic and has poor affinity for organic matter. Furthermore, the interlayer structure of the activated clay is not fully opened, resulting in weak adsorption capacity for olefins and nitrogen. To improve the affinity and adsorption capacity of the activated clay and fully utilize its large specific surface area, the present invention uses cetyltrimethylammonium bromide and caprolactam to perform a composite intercalation modification treatment on the activated clay. After ion exchange between the organic cations of cetyltrimethylammonium bromide and the inorganic cations between the activated clay layers, the cationic portion adheres to the activated clay layers, while the organic portion remains between the layers. This increases the interlayer spacing of the activated clay, resulting in a looser structure, higher porosity, and partial flaking.

[0014] However, the use of cetyltrimethylammonium bromide to modify activated clay is not only costly, but also has poor compatibility with olefins, making it difficult to form an intercalation structure. To this end, on the basis of using cetyltrimethylammonium bromide for organic intercalation modification, the present invention adds caprolactam to carry out composite modification of activated clay. The intercalation modified clay obtained by the cetyltrimethylammonium bromide / caprolactam composite intercalation modification has an significantly improved interlayer spacing. This is because, after the cetyltrimethylammonium bromide and the activated clay undergo cation exchange, 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 cetyltrimethylammonium bromide intercalation modification, the interlayer microenvironment of the activated clay is changed from hydrophilic to lipophilic, which is conducive to the adsorption of caprolactam between the layers of the activated clay. The C=O group of the caprolactam adsorbed between the activated clay layers easily forms a hydrogen bond with the -OH group between the bentonite layers, thereby introducing the caprolactam molecules into the activated clay layers, further increasing the interlayer spacing of the activated clay.

[0015] The organic intercalation modification of activated clay using hexadecyltrimethylammonium bromide and caprolactam is achieved by entering the interlayers of activated clay through ion exchange and chemical bonding. However, this modification method can only modify the interlayers of activated clay, which can increase the interlayer spacing of activated clay and provide a certain space for the adsorption of olefins and nitrogen. However, the surface modification effect of activated clay by intercalation modification alone is insufficient, and therefore the surface hydrophobicity of activated clay cannot be significantly improved, thereby affecting its compatibility with the organic phase and resulting in insufficient affinity for olefins. To this end, after the activated clay is intercalated and modified, the surface of the intercalated modified clay is further hydrophobically modified using a silane coupling agent. The silane coupling agent is a substance having two functional groups with different chemical properties, namely a non-hydrolyzable group and a hydrolyzable group. The silanols generated by the hydrolysis of the silane coupling agent can react with the hydroxyl groups on the surface of the intercalated modified clay to be grafted 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 hydrophobic film with a network structure and cover the surface of the intercalated modified clay. The composite modified clay obtained after modification with the silane coupling agent changes from hydrophilic to hydrophobic. The improved hydrophobicity enhances the affinity, expansion and dispersibility of the composite modified clay in the organic phase, making it better applicable to deolefination / denitrification in organic systems.

[0016] The present invention generates magnesium hydroxide through a hydrothermal synthesis reaction of magnesium chloride and sodium hydroxide, and then uses magnesium hydroxide as a precursor. After high-temperature calcination, magnesium oxide particles are in situ loaded on the surface and interlayers of the composite modified clay, ultimately obtaining the high-efficiency granular clay adsorbent provided by the present invention. Compared with the composite modified clay, the high-efficiency granular clay adsorbent loaded with magnesium oxide particles has a smaller specific surface area (the specific surface area of ​​the composite modified clay is 91-100 m 2 / g, the specific surface area of ​​high-efficiency granular clay adsorbent is 30~40m 2 / g), this is because the magnesium oxide particles are inserted into the interlayers of the composite modified clay, resulting in the blocking of the channels between the layers and the surface pores, which reduces the specific surface area of ​​the composite modified clay. However, at the same time, the pore volume and pore diameter of the high-efficiency granular clay adsorbent loaded with magnesium oxide particles increased significantly (the pore volume of the composite modified clay is about 0.1~0.15cc / g, and the pore diameter is about 3.5~4nm; the pore volume of the high-efficiency granular clay adsorbent is about 0.35~0.4cc / g, and the pore diameter is about 35~40nm). This is because the magnesium hydroxide deposited on the surface of the composite modified clay is decomposed into magnesium oxide after high-temperature calcination. During the high-temperature calcination process, by-products evaporate and escape, including physically adsorbed and chemically adsorbed water molecules and carbon dioxide. The space originally occupied by these products forms a pore structure, thereby 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 is continuously generated and stacked and overlapped, forming a large number of mesoporous structures, which greatly increases the pore volume and pore diameter of the final high-efficiency granular clay adsorbent, significantly increases the adsorption sites, and significantly enhances the adsorption capacity.

[0017] As a preferred technical solution of the present invention, in step (I), when preparing the acidulant, the concentrated hydrochloric acid is first slowly added to deionized water and mixed evenly 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 mixed evenly to obtain the acidulant.

[0018] In some optional examples, the mass fraction of the concentrated hydrochloric acid is 35~37wt%, for example, it can be 35wt%, 35.2wt%, 35.4wt%, 35.6wt%, 35.8wt%, 36wt%, 36.2wt%, 36.4wt%, 36.6wt%, 36.8wt% or 37wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0019] In some optional 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 the numerical range are also applicable.

[0020] In some optional 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 the numerical range are also applicable.

[0021] The present invention specifically limits the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid, and deionized water to 1:(1.4-1.6):(35-40). The excessively high concentration of hydrogen ions ionized by sulfuric acid disrupts the bentonite crystal layer structure, causing aluminum and magnesium ions in the interlayers of the bentonite to be dissolved by hydrogen ions, thereby collapsing the bentonite skeleton and destroying the octahedron. The relatively low concentration of hydrogen ions ionized by hydrochloric acid makes it less effective than mixed acid in the acid modification process. A mixed acid composed of hydrochloric acid, sulfuric acid, and oxalic acid ionizes a moderate concentration of hydrogen ions. Adding oxalic acid allows the hydrogen ions to form sparingly soluble salts with calcium and magnesium ions, facilitating the replacement of calcium and magnesium ions between bentonite layers and achieving the best activation effect.

[0022] In some optional examples, the mass fraction of oxalic acid in the acidulant is 5 to 10 wt %, for example, 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 values ​​not listed within the numerical range are also applicable.

[0023] 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 values ​​not listed within the numerical range are also applicable.

[0024] In some optional examples, the bentonite powder and deionized water are mixed in 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, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0025] In some optional examples, the mass ratio of the bentonite slurry, the acidulant 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, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] The present invention particularly limits the mass ratio of bentonite slurry, acidulant and sodium chloride to 1:(0.6-0.7):(0.08-0.1). When the amount of the acidulant 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 activated clay finally obtained is poor. As the amount of the acidulant increases, the hydrogen ion concentration increases, and the activity of the activated clay obtained after acid activation increases rapidly, indicating that the calcium ions and magnesium ions between the bentonite layers are fully replaced by hydrogen ions, and the activated clay is modified by acidification to form a high-efficiency activated clay with a larger specific surface area and stronger adsorption. When the amount of the acidulant exceeds the upper limit of the range defined by the present invention, the excessive hydrogen ion concentration causes the aluminum ions in the bentonite tetrahedron structure to be exchanged and dissolved, destroying the skeleton structure of the bentonite, and significantly reducing the activity of the activated clay finally obtained.

[0027] In some optional examples, the heating activation step includes:

[0028] 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, and then cooled to room temperature after the temperature is maintained to obtain the activated product.

[0029] In some optional 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℃, but is not limited to the listed values. Other unlisted values ​​within this numerical range are also applicable.

[0030] In some optional examples, the first activation temperature is kept warm for 2 to 3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In some optional embodiments, the second activation temperature is 100~110°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 is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In some optional examples, the second activation temperature is kept warm for 2 to 3 hours, for example, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In some optional embodiments, the activated product is rinsed 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 is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional examples, the centrifugal speed is 3000~4000rpm, for example, it can be 3000rpm, 3100rpm, 3200rpm, 3300rpm, 3400rpm, 3500rpm, 3600rpm, 3700rpm, 3800rpm, 3900rpm or 4000rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] In some optional examples, the centrifugation time is 5 to 10 min, 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 is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] As a preferred technical solution of the present invention, in step (II), the operation steps of the organic intercalation modification treatment include:

[0037] The activated clay is dispersed in deionized water to obtain a clay suspension; under conditions of continuous stirring and water bath heating, hexadecyltrimethylammonium bromide and caprolactam are sequentially added to the clay suspension to react; after the reaction is completed, centrifugation is performed, and the precipitate obtained after centrifugation is washed and dried to obtain the intercalated modified clay.

[0038] As a preferred technical solution of the present invention, the mass fraction of the activated clay in the clay suspension is 2 to 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 values ​​not listed within this numerical range are also applicable.

[0039] In some optional examples, the mass ratio of activated clay to hexadecyltrimethylammonium 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 also applicable.

[0040] The present invention specifically limits the mass ratio of activated clay to hexadecyltrimethylammonium bromide to 1:(0.3-0.5). As the amount of hexadecyltrimethylammonium bromide increases, the interlayer spacing of the resulting intercalated modified clay shows a trend of first increasing and then decreasing. When the mass ratio of activated clay to hexadecyltrimethylammonium bromide is within the numerical range defined by the present invention, both a larger interlayer spacing and a higher intercalation efficiency can be obtained. When the amount of hexadecyltrimethylammonium bromide is below the lower limit of the range defined by the present invention, the interlayer cations of the activated clay cannot be completely chain-exchanged by the hexadecyltrimethylammonium bromide, resulting in a smaller interlayer spacing of the intercalated modified clay, which in turn affects the adsorption capacity for olefins and nitrogen. When the amount of cetyltrimethylammonium bromide exceeds the upper limit of the range defined in the present invention, excessive organic chains tend to accumulate in the interlayer edge region of the activated clay, blocking the exchange channel between the organic chains and the interlayer cations, and generating steric hindrance for the cetyltrimethylammonium bromide molecular chains that have not entered the interlayer. As a result, only a small number of cetyltrimethylammonium bromide molecular chains can successfully enter the interlayers of the activated clay, while the majority of the cetyltrimethylammonium bromide molecular chains cannot successfully enter the interlayers of the activated clay and are simply adsorbed on the surface of the activated clay, hindering the further increase in the interlayer spacing of the activated clay. Therefore, further increasing the amount of cetyltrimethylammonium bromide cannot further expand the interlayer spacing of the activated clay, and the intercalation efficiency is low.

[0041] In some optional examples, the mass ratio of the hexadecyltrimethylammonium bromide to the caprolactam is (2-3):1, for example, 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, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] The present invention particularly limits the mass ratio of hexadecyltrimethylammonium bromide to caprolactam to (2-3):1. When the mass ratio of hexadecyltrimethylammonium bromide to caprolactam is within this range, the intercalation modified clay has the largest interlayer spacing. This is because caprolactam reacts with the sodium ions between the activated clay layers to form amide ions, thereby entering the interlayers of the activated clay and increasing the interlayer spacing of the activated clay. When the amount of caprolactam used is lower than the lower limit of the range defined by the present invention, there is not enough caprolactam to participate in the reaction, and too little caprolactam enters the interlayers of the activated clay, making it impossible to effectively intercalate the activated clay, and the degree of improvement in the interlayer spacing of the activated clay is limited. When the amount of caprolactam used exceeds the upper limit of the range defined in the present invention, it will react on the lattice sites, destroying the lattice sites between the activated clay layers. This will cause the cetyltrimethylammonium bromide that has already entered the activated clay layers and completed cation exchange to lose its binding sites and eventually fall off from the activated clay layers. In addition, because caprolactam has a high solubility in water and it easily forms amide ions with the hydroxyl groups and hydrogen ions between and at the edges of the activated clay layers, it can preferentially enter the activated clay layers. The caprolactam that preferentially enters the activated clay layers will have a certain hindering effect on the cetyltrimethylammonium bromide that has not entered the activated clay layers, thereby affecting the intercalation modification effect of the cetyltrimethylammonium bromide.

[0043] In some optional embodiments, the water bath heating temperature is 70~80℃, for example, it can be 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃ or 80℃, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] In some optional examples, after adding cetyltrimethylammonium bromide to the clay suspension, the mixture is continued to be stirred under heating in a water bath for 10 to 20 minutes, and then caprolactam is added. For example, the mixture may be stirred for 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0045] In some optional embodiments, after adding caprolactam, mixing and stirring are continued under heating conditions in a water bath for 3 to 4 hours, for example, 3.0 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours or 4.0 hours, but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] In some optional examples, the centrifugal speed is 7000~8000rpm, for example, it can be 7000rpm, 7100rpm, 7200rpm, 7300rpm, 7400rpm, 7500rpm, 7600rpm, 7700rpm, 7800rpm, 7900rpm or 8000rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In some optional embodiments, the centrifugation time 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 is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] As a preferred technical solution of the present invention, in step (II), the surface hydrophobic modification treatment comprises:

[0049] 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.

[0050] As a preferred technical solution of the present invention, the volume ratio of ethanol to deionized water in the ethanol aqueous solution is (4-5):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 is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0051] In some optional examples, the mass fraction of the silane coupling agent in the coupling agent solution is 1 to 5 wt%, for example, 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 is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0052] In some optional examples, the mass ratio of the silane coupling agent in the coupling agent solution to the intercalated 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, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0053] The present invention specifically limits the mass ratio of the silane coupling agent to the intercalation modified clay to (0.02-0.05):1. As the amount of the silane coupling agent increases, the hydrophobicity of the resulting composite modified clay first increases and then decreases. This is because, when the amount of the silane coupling agent is below the lower limit of the range defined by the present invention, it cannot completely react with the intercalation modified clay. As the amount of the silane coupling agent increases, the amount of the silane coupling agent grafted on the surface of the intercalation modified clay increases, thereby improving 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 completely reacts with all the hydroxyl groups on the surface of the intercalation modified clay, thereby grafting an ordered monolayer of the 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 in the present invention, the silane coupling agent is excessively hydrolyzed to form silanol, which accumulates on the surface of the intercalated modified clay to form a silanol multi-molecular layer, thereby reducing the surface hydrophobicity of the intercalated modified clay, thereby affecting its affinity with olefins and affecting its olefin removal rate.

[0054] In some optional examples, the reaction temperature of the intercalated 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, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In some optional examples, the reaction time of the intercalated modified clay and the coupling agent solution is 3 to 5 hours, for example, it can be 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours or 5.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] 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 to 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 values ​​not listed within the numerical range are also applicable.

[0057] In some optional 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 the numerical range are also applicable.

[0058] The present invention synthesizes magnesium oxide particles in situ on the surface and interlayer of composite modified clay by hydrothermal synthesis, greatly improving the specific surface area of ​​the composite modified clay, so that the high-efficiency granular clay adsorbent finally obtained has an appropriate number of mesopores, which is conducive to improving the removal effect of olefins and nitrogen. The present invention specifically limits the mass ratio of 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 increases, the specific surface area of ​​the high-efficiency granular clay adsorbent finally obtained shows a trend of first increasing and then decreasing. This is because when the present invention uses magnesium chloride and sodium hydroxide as reaction raw materials for hydrothermal reaction, magnesium hydroxide flocculent precipitate is generated, and the magnesium hydroxide flocculent precipitate is calcined to form magnesium oxide. 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 interlayer of the composite modified clay and stacked with each other to form more new pores, thereby improving the porosity of the composite modified clay. When the amount of magnesium chloride exceeds the upper limit of the range defined in the present invention, too much flocculent magnesium hydroxide precipitate is generated, resulting in the surface pores of the composite modified clay being covered by too much magnesium hydroxide. During the calcination process, the magnesium hydroxide will decompose into nano-magnesium oxide. Nano-magnesium oxide is prone to agglomeration due to its high surface energy, resulting in the surface pores of the composite modified clay being blocked by the agglomerated magnesium oxide, resulting in a decrease in porosity.

[0059] In some optional examples, the mixing and stirring time of the clay dispersion and magnesium chloride is 1 to 2 hours, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In some optional examples, the heating temperature of the clay dispersion and magnesium chloride during mixing and stirring is 50~60°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, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0061] In some optional examples, 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, 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, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0062] In some optional examples, the mixing and stirring time of the intermediate solution and sodium hydroxide is 6 to 8 hours, for example, it can be 6.0 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7.0 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours or 8.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In some optional embodiments, the heating temperature of the intermediate solution and sodium hydroxide during mixing and stirring is 80~90°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, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0064] In some optional embodiments, the calcination heating rate is 10~20℃ / min, 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, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] In some optional embodiments, the calcination temperature is 440~460℃, for example, it can be 440℃, 442℃, 444℃, 446℃, 448℃, 450℃, 452℃, 454℃, 456℃, 458℃ or 460℃, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] The present invention specifically limits the calcination temperature to 440-460°C. When the calcination temperature is lower than 440°C, the magnesium hydroxide cannot be fully decomposed; when the calcination temperature is higher than 460°C, the generated magnesium oxide is prone to agglomeration, which not only leads to a decrease in the porosity of the high-efficiency granular clay adsorbent, but also reduces the number of effective adsorption sites.

[0067] In some optional embodiments, the calcination time is 2 to 3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0068] In a second aspect, the present invention provides an application of a high-efficiency granular clay adsorbent for deolefination / denitrification prepared by the preparation method described in the first aspect, wherein the high-efficiency granular clay adsorbent is used in the field of deolefination or denitrification.

[0069] Compared with the prior art, the present invention has the following beneficial effects:

[0070] 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 deolefination and denitrification capabilities of the activated white clay. On the one hand, during the acidification process, some non-adsorbable impurities, soluble impurities, and minerals in the bentonite are decomposed by the acid and dissolved in the liquid phase system, so that part of the bentonite crystal lattice is destroyed, the interplanar spacing is increased, the pores of the bentonite are opened, the pore diameter is increased, and the number of adsorption sites is increased, thereby improving the physical adsorption capacity of the activated white 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 reactions, thereby being effectively removed; in terms of denitrification, when the bentonite is activated with a mixed acid, hydrogen ions replace exchangeable metal ions, forming abundant acid centers on the surface. The alkalinity of the alkaline nitride morpholine lies in the fact that its nitrogen atom contains unshared electron pairs, which can combine with protons to form positively charged ions. When the highly alkaline morpholine is adsorbed on the surface of the activated clay, the acid centers of the activated clay can react with the nitrogen atoms of the morpholine to form corresponding amine salts that are deposited on the surface of the activated clay, thereby achieving the purpose of denitrification. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 A flow chart of the preparation process of a high-efficiency granular clay adsorbent for deolefination / denitrification provided in Examples 1-5 of the present invention;

[0072] Figure 2 This is a schematic structural diagram of the deolefination evaluation device used in the present invention;

[0073] Among them, 1-raw material tank; 2-feed pump; 3-reactor; 4-cooler; 5-product collection tank;

[0074] Figure 3 XRD patterns of bentonite, activated clay prepared in Example 1 of the present invention, and composite modified clay;

[0075] Figure 4 IR spectra of bentonite and activated clay prepared in Example 1 of the present invention;

[0076] Figure 5 (a) is a scanning electron micrograph of the bentonite powder used in Example 1 of the present invention; Figure 5 (b) is a scanning electron micrograph of the activated clay prepared in Example 1 of the present invention; Figure 5 (c) is a scanning electron microscope image of the composite modified clay prepared in Example 1 of the present invention; Figure 5 (d) is a scanning electron micrograph of the high-efficiency granular clay adsorbent prepared in Example 1 of the present invention at low magnification; Figure 5 (e) is a scanning electron microscope image of the high-efficiency granular clay adsorbent prepared in Example 1 of the present invention at a high magnification;

[0077] Figure 6 The XRD patterns of the activated clay and high-efficiency granular clay adsorbent prepared in Example 1 of the present invention are shown. DETAILED DESCRIPTION

[0078] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and their accompanying drawings. The embodiments described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0079] The chemical reagents used in the specific embodiments of the present invention are all commercially available products, and their models, specifications, and manufacturers are as follows:

[0080] Concentrated hydrochloric acid: analytical grade, purchased from Tianjin Damao Chemical Reagent Factory;

[0081] Concentrated sulfuric acid: analytical grade, purchased from Tianjin Damao Chemical Reagent Factory;

[0082] Oxalic acid: analytical grade, purchased from Shandong Zhengxing New Materials Co., Ltd.

[0083] Sodium chloride: R21092-500ml, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0084] Hexadecyltrimethylammonium bromide: S15001-100 g, purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0085] Caprolactam: S70056-100g, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0086] Silane coupling agent KH550: S15028-500ml, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0087] Silane coupling agent KH560: S15029-500ml, purchased from Shanghai Yuanye Biotechnology Co., Ltd.;

[0088] Anhydrous ethanol: analytical grade, purchased from Nanjing Chemical Reagent Co., Ltd.

[0089] Magnesium chloride: analytical grade, purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.

[0090] Sodium hydroxide: analytical grade, purchased from Fuchen (Tianjin) Chemical Reagent Co., Ltd.

[0091] Example 1

[0092] This embodiment provides a method for preparing a highly efficient granular clay adsorbent for deolefination / denitrification, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0093] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 35 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 98 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.4:35, and mix well to obtain a mixed acid solution; finally, add oxalic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 5 wt%;

[0094] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 100 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.6:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.6:0.08 to obtain a raw material mixture, the raw material mixture is heated to 80° C. and kept warm for 3 hours, and then further heated to 100° C. and kept warm for 3 hours after the insulation is completed, and then cooled to room temperature after the insulation is completed to obtain an activated product; the activated product is rinsed with deionized water until the pH value of the activated product reaches 4, and then centrifuged at a speed of 3000 rpm for 10 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0095] (2) dispersing the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 2 wt%; adding cetyltrimethylammonium bromide to the clay suspension under conditions of continuous stirring and heating in a water bath at 70°C, wherein the mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.3; after adding cetyltrimethylammonium bromide, mixing and stirring for 20 minutes under conditions of heating in a water bath at 70°C; then adding caprolactam, wherein the mass ratio of cetyltrimethylammonium bromide to caprolactam is 2:1; after adding caprolactam, mixing and stirring for 4 hours under conditions of heating in a water bath at 70°C to react; after the reaction is completed, centrifuging at a speed of 7000 rpm for 20 minutes; washing and drying the precipitate obtained after centrifugation to obtain intercalated modified clay;

[0096] Ethanol and deionized water are uniformly mixed in a volume ratio of 4:1 to obtain an ethanol aqueous solution, a silane coupling agent and the ethanol aqueous solution are uniformly mixed to obtain a coupling agent solution with a mass fraction of 1 wt%, intercalated modified clay is added to the coupling agent solution, the mass ratio of the silane coupling agent to the intercalated modified clay is 0.02:1, the mixture is heated at 70° C. and stirred for 5 h to react, and after the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified clay;

[0097] (3) dispersing the composite modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 2 wt%; adding magnesium chloride to the clay dispersion, with a mass ratio of the composite modified clay to the magnesium chloride being 1:0.5, and mixing and stirring for 2 h at a heating condition of 50°C to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, with a molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide being 0.5:1, and mixing and stirring for 8 h at a heating condition of 80°C to react; after the reaction is completed, filtering, washing, extruding and drying are performed; the dried reaction product is heated to 440°C at a heating rate of 10°C / min and kept warm for 3 h to complete the calcination treatment; after the calcination is completed, the high-efficiency granular clay adsorbent is obtained by crushing and screening.

[0098] Figure 3The XRD patterns of bentonite, activated clay prepared in Example 1 of the present invention, and composite modified clay are shown. As can be seen from the figure, bentonite exhibits a strong diffraction peak at 2θ=7.00°. Using the Bragg equation: 2dsinθ=nλ, where n is 1 and λ is 0.15406 nm, the interlayer spacing of bentonite can be calculated to be 1.048 nm; the activated clay exhibits a strong diffraction peak at 2θ=7.96°, and the interlayer spacing of the activated clay can be calculated to be 1.455 nm using the Bragg equation; the composite modified clay exhibits strong diffraction at 2θ=6.48°, and the interlayer spacing of the composite modified clay can be calculated to be 2.512 nm using the Bragg equation. This indicates that the interlayer spacing of the activated clay obtained after acid activation is significantly increased compared to unmodified bentonite. This is because during the acid activation process, the hydrogen ions in the acid replace the metal cations in the bentonite, causing interlayer ion exchange in the bentonite, further increasing the interlayer spacing. Compared to activated clay, the interlayer spacing of the composite modified clay obtained after organic intercalation modification and silane coupling agent surface modification is further increased, resulting in a higher specific surface area and more active sites, which is beneficial to improving the adsorption performance of the composite modified clay.

[0099] Figure 4 The infrared spectra of bentonite and the activated clay prepared in Example 1 of the present invention are compared. It can be seen that 1653 cm -1 The corresponding absorption peaks are the stretching and bending vibrations of the hydroxyl groups of water molecules in the bentonite crystal structure, 1043 cm -1 、471cm -1 and 823cm -1 The corresponding absorption peaks are the Si-O stretching vibration absorption peak, the Si-O-Si bending vibration absorption peak and the O-Si-O asymmetric stretching vibration absorption peak. The difference between the infrared curves of bentonite and activated clay is that the activated clay has a high frequency absorption peak of 3628cm -1 The peak intensity at 1043 cm-1 increases, which is due to the OH stretching vibration, indicating that the exchangeable cations are replaced by protons during the acid activation treatment, thereby increasing the number of hydroxyl groups available for further functionalization. -1 and 471cm -1 The energy band intensity of the Si-O stretching vibration absorption peak and the Si-O-Si bending vibration absorption peak at 823 cm -1 The energy band intensity of the O-Si-O asymmetric stretching vibration absorption peak at is enhanced, which indicates that after acid activation treatment, the Si environment changes due to acid corrosion, the organizational structure of the activated clay changes, and the active sites increase.

[0100] Figure 5 (a) Figure 5 (b) Figure 5 (c) and Figure 5 (d) are scanning electron micrographs of the bentonite powder used in this example, the activated clay prepared in this example, the composite modified clay, and the high-efficiency granular clay adsorbent, respectively. Figure 5 (a) and Figure 5 (b) Compared with bentonite powder, activated clay has better particle dispersion, larger specific surface area, higher porosity, and overall presents loose and regular granular aggregates. Figure 5 (c) It can be seen that the porosity of the composite modified clay is higher and the particle size dispersion is more uniform, the structure is looser, the flaky structure is significantly reduced, the interlayer spacing is larger, and a large number of voids are generated. Figure 5 (d) and Figure 5 (e) It can be seen that magnesium oxide with a hexagonal flake structure can be seen on the surface of the high-efficiency granular clay adsorbent. The accumulation of magnesium oxide produces more pores and forms a mesoporous structure.

[0101] Figure 6 The XRD patterns of the activated clay and high-efficiency granular clay adsorbent prepared in this example are shown. As can be seen from the figure, compared with the activated clay, the high-efficiency granular clay adsorbent exhibits two stronger 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 spectrum of magnesium oxide, indicating that magnesium oxide has been successfully loaded onto the high-efficiency granular clay adsorbent prepared in this invention. Furthermore, the XRD diffraction peaks of the high-efficiency granular clay adsorbent are significantly broadened and sharper, indicating that the loaded magnesium oxide particles have a small particle size and good crystallinity.

[0102] Example 2

[0103] This embodiment provides a method for preparing a highly efficient granular clay adsorbent for deolefination / denitrification, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0104] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 35.5 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 97 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.45:36, and mix well to obtain a mixed acid solution; finally, add oxalic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 6 wt%;

[0105] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 120 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.62:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.62:0.085 to obtain a raw material mixture, the raw material mixture is heated to 82° C. and kept warm for 2.8 hours, and then further heated to 102° C. and kept warm for 2.8 hours after the end of the heat preservation, and then 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 4.2, and then centrifuged at a speed of 3200 rpm for 8 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0106] (2) dispersing the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 3 wt%; adding cetyltrimethylammonium bromide to the clay suspension under continuous stirring and heating in a water bath at 72°C, wherein the mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.35; after adding cetyltrimethylammonium bromide, mixing and stirring for 18 minutes under heating in a water bath at 72°C; then adding caprolactam, wherein the mass ratio of cetyltrimethylammonium bromide to caprolactam is 2.2:1; after adding caprolactam, mixing and stirring for 3.8 hours under heating in a water bath at 72°C to react; after the reaction is completed, centrifuging at a speed of 7200 rpm for 18 minutes; washing and drying the precipitate obtained after centrifugation to obtain intercalated modified clay;

[0107] Ethanol and deionized water are uniformly mixed in a volume ratio of 4.2:1 to obtain an ethanol aqueous solution, a silane coupling agent and the ethanol aqueous solution are uniformly mixed to obtain a coupling agent solution with a mass fraction of 2 wt%, and intercalated modified clay is added to the coupling agent solution with a mass ratio of the silane coupling agent to the intercalated modified clay of 0.03:1. The mixture is stirred under heating conditions of 72° C. for 4.5 hours to react, and after the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified clay;

[0108] (3) dispersing the composite modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 3 wt%; adding magnesium chloride to the clay dispersion, with a mass ratio of the composite modified clay to the magnesium chloride being 1:0.52, and mixing and stirring for 1.8 h at a heating condition of 52°C to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, with a molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide being 0.55:1, and mixing and stirring for 7.5 h at a heating condition of 82°C to react; after the reaction is completed, filtering, washing, extruding and drying are performed; the dried reaction product is heated to 445°C at a heating rate of 12°C / min and kept warm for 2.8 h to complete the calcination treatment; after the calcination is completed, the high-efficiency granular clay adsorbent is obtained by crushing and screening.

[0109] Example 3

[0110] This embodiment provides a method for preparing a highly efficient granular clay adsorbent for deolefination / denitrification, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0111] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 36 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 96 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.5:37, and mix well to obtain a mixed acid solution; finally, add oxalic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 7 wt%;

[0112] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 150 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.65:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.65:0.09 to obtain a raw material mixture, and the raw material mixture is heated to 85° C. and kept warm for 2.5 hours. After the insulation, the temperature is further increased to 105° C. and kept warm for 2.5 hours. After the insulation, the mixture 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, and then centrifuged at a speed of 3500 rpm for 7 minutes. The precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0113] (2) dispersing the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 4 wt%; adding cetyltrimethylammonium bromide to the clay suspension under continuous stirring and heating in a water bath at 75°C, wherein the mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.4; after adding cetyltrimethylammonium bromide, mixing and stirring for 15 minutes under heating in a water bath at 75°C; then adding caprolactam, wherein the mass ratio of cetyltrimethylammonium bromide to caprolactam is 2.5:1; after adding caprolactam, mixing and stirring for 3.5 hours under heating in a water bath at 75°C to react; after the reaction is completed, centrifuging at a speed of 7500 rpm for 15 minutes; washing and drying the precipitate obtained after centrifugation to obtain intercalated modified clay;

[0114] Ethanol and deionized water are uniformly mixed in a volume ratio of 4.5:1 to obtain an ethanol aqueous solution, a silane coupling agent and the ethanol aqueous solution are uniformly mixed to obtain a coupling agent solution with a mass fraction of 3 wt%, intercalated modified clay is added to the coupling agent solution, the mass ratio of the silane coupling agent to the intercalated modified clay is 0.03:1, the mixture is heated at 75° C. and stirred for 4 h to react, and after the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified clay;

[0115] (3) dispersing the composite modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 3 wt%; adding magnesium chloride to the clay dispersion, with a mass ratio of the composite modified clay to the magnesium chloride being 1:0.55, and mixing and stirring for 1.5 h at a heating condition of 55°C to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, with a molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide being 0.6:1, and mixing and stirring for 7 h at a heating condition of 85°C to react; after the reaction is completed, filtering, washing, extruding and drying are performed; 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, the high-efficiency granular clay adsorbent is obtained by crushing and screening.

[0116] Example 4

[0117] This embodiment provides a method for preparing a highly efficient granular clay adsorbent for deolefination / denitrification, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0118] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 36.5 wt% into deionized water and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 96 wt% into the dilute hydrochloric acid, the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water being 1:1.55:38, and mix well to obtain a mixed acid solution; finally, add oxalic acid into the mixed acid solution and mix well to obtain an acidifier, wherein the mass fraction of oxalic acid in the acidifier is 8 wt%;

[0119] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 180 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.68:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.68:0.095 to obtain a raw material mixture, the raw material mixture is heated to 88° C. and kept warm for 2.2 hours, and then further heated to 108° C. and kept warm for 2.2 hours after the end of the heat preservation, and then 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 4.8, and then centrifuged at a speed of 3800 rpm for 6 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0120] (2) dispersing the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 4 wt%; adding cetyltrimethylammonium bromide to the clay suspension under continuous stirring and heating in a water bath at 78°C, wherein the mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.45; after adding cetyltrimethylammonium bromide, mixing and stirring for 12 minutes under heating in a water bath at 78°C; then adding caprolactam, wherein the mass ratio of cetyltrimethylammonium bromide to caprolactam is 2.8:1; after adding caprolactam, mixing and stirring for 3.2 hours under heating in a water bath at 78°C to react; after the reaction is completed, centrifuging at a speed of 7800 rpm for 12 minutes; washing and drying the precipitate obtained after centrifugation to obtain intercalated modified clay;

[0121] Ethanol and deionized water are uniformly mixed in a volume ratio of 4.8:1 to obtain an ethanol aqueous solution, a silane coupling agent and the ethanol aqueous solution are uniformly mixed to obtain a coupling agent solution with a mass fraction of 4 wt%, and intercalated modified clay is added to the coupling agent solution with a mass ratio of the silane coupling agent to the intercalated modified clay of 0.04:1. The mixture is stirred under heating conditions of 78° C. for 3.5 hours to react, and after the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified clay;

[0122] (3) dispersing the composite modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 4 wt%; adding magnesium chloride to the clay dispersion, with a mass ratio of the composite modified clay to the magnesium chloride being 1:0.58, and mixing and stirring for 1.2 h at a heating condition of 58°C to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, with a molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide being 0.65:1, and mixing and stirring for 6.5 h at a heating condition of 88°C to react; after the reaction is completed, filtering, washing, extruding and drying are performed; the dried reaction product is heated to 455°C at a heating rate of 18°C / min and kept warm for 2.2 h to complete the calcination treatment; after the calcination is completed, the high-efficiency granular clay adsorbent is obtained by crushing and screening.

[0123] Example 5

[0124] This embodiment provides a method for preparing a highly efficient granular clay adsorbent for deolefination / denitrification, such as Figure 1 As shown, the preparation method specifically includes the following steps:

[0125] (1) Slowly add concentrated hydrochloric acid with a mass fraction of 37 wt% to deionized water, and mix well to obtain dilute hydrochloric acid; then slowly add concentrated sulfuric acid with a mass fraction of 95 wt% to the dilute hydrochloric acid, and the volume ratio of concentrated hydrochloric acid, concentrated sulfuric acid and deionized water is 1:1.6:40, and mix well to obtain a mixed acid solution; finally, add oxalic acid to the mixed acid solution, and mix well to obtain an acidifier, and the mass fraction of oxalic acid in the acidifier is 10 wt%;

[0126] The bentonite ore is crushed and sieved to obtain a bentonite powder with a particle size of 200 mesh, and the bentonite powder is mixed with deionized water in a mass ratio of 0.7:1 to obtain a bentonite slurry; the bentonite slurry, an acidifier, and sodium chloride are uniformly mixed in a mass ratio of 1:0.7:0.1 to obtain a raw material mixture, the raw material mixture is heated to 90° C. and kept warm for 2 hours, and then further heated to 110° C. and kept warm for 2 hours after the end of the heat preservation, and then 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 5, and then centrifuged at a speed of 4000 rpm for 5 minutes, and the precipitate after centrifugation is dried and crushed to obtain activated white clay;

[0127] (2) dispersing the activated clay obtained in step (1) in deionized water to obtain a clay suspension with a mass fraction of 5 wt%; adding cetyltrimethylammonium bromide to the clay suspension under continuous stirring and heating in a water bath at 80°C, wherein the mass ratio of activated clay to cetyltrimethylammonium bromide is 1:0.5; after adding cetyltrimethylammonium bromide, mixing and stirring for 10 minutes under heating in a water bath at 80°C; then adding caprolactam, wherein the mass ratio of cetyltrimethylammonium bromide to caprolactam is 3:1; after adding caprolactam, mixing and stirring for 3 hours under heating in a water bath at 80°C to react; after the reaction is completed, centrifuging at a speed of 8000 rpm for 10 minutes; washing and drying the precipitate obtained after centrifugation to obtain intercalated modified clay;

[0128] Ethanol and deionized water are uniformly mixed in a volume ratio of 5:1 to obtain an ethanol aqueous solution, a silane coupling agent and the ethanol aqueous solution are uniformly mixed to obtain a coupling agent solution with a mass fraction of 5 wt%, intercalated modified clay is added to the coupling agent solution, and the mass ratio of the silane coupling agent to the intercalated modified clay is 0.05:1. The mixture is stirred under heating conditions of 80° C. for 3 h to react, and after the reaction is completed, the mixture is filtered, washed, and dried to obtain a composite modified clay;

[0129] (3) dispersing the composite modified clay obtained in step (2) in deionized water to obtain a clay dispersion with a mass fraction of 5 wt%; adding magnesium chloride to the clay dispersion, with a mass ratio of the composite modified clay to the magnesium chloride being 1:0.6, and mixing and stirring for 1 h at a heating condition of 60°C to obtain an intermediate solution; adding sodium hydroxide to the intermediate solution, with a molar ratio of magnesium ions of magnesium chloride to hydroxide ions of sodium hydroxide being 0.7:1, and mixing and stirring for 6 h at a heating condition of 90°C to react; after the reaction is completed, filtering, washing, extruding and drying are performed; the dried reaction product is heated to 460°C at a heating rate of 20°C / min and kept warm for 2 h to complete the calcination treatment; after the calcination is completed, the high-efficiency granular clay adsorbent is obtained by crushing and screening.

[0130] Comparative Example 1

[0131] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that, in the preparation of the acidulant, concentrated hydrochloric acid is omitted, and concentrated sulfuric acid is slowly added to deionized water and mixed uniformly to obtain dilute sulfuric acid. Subsequently, oxalic acid is added to the dilute sulfuric acid and mixed uniformly to obtain the acidulant. The other process parameters and operating steps are exactly the same as those in Example 1.

[0132] Comparative Example 2

[0133] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that, in the preparation of the acidulant, concentrated sulfuric acid is omitted, concentrated hydrochloric acid is slowly added to deionized water, and mixed evenly to obtain dilute hydrochloric acid, and then oxalic acid is added to the dilute hydrochloric acid, and mixed evenly to obtain the acidulant. The other process parameters and operating steps are exactly the same as those in Example 1.

[0134] Comparative Example 3

[0135] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that, in the preparation of the acidulant, oxalic acid is omitted, concentrated hydrochloric acid is slowly added to deionized water, and mixed evenly to obtain dilute hydrochloric acid, and then concentrated sulfuric acid is slowly added to the dilute hydrochloric acid, and mixed evenly to obtain the acidulant. The other process parameters and operating steps are exactly the same as those in Example 1.

[0136] Comparative Example 4

[0137] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that the mass ratio of activated clay to hexadecyltrimethylammonium bromide in the clay suspension is adjusted to 1:0.2, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0138] Comparative Example 5

[0139] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that the mass ratio of activated clay to hexadecyltrimethylammonium bromide in the clay suspension is adjusted to 1:0.6, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0140] Comparative Example 6

[0141] This comparative example provides a preparation method for a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that the mass ratio of hexadecyltrimethylammonium bromide to caprolactam is adjusted to 1.5:1, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0142] Comparative Example 7

[0143] This comparative example provides a preparation method for a high-efficiency granular clay adsorbent for deolefination / denitrification. The difference from Example 1 is that the mass ratio of hexadecyltrimethylammonium bromide to caprolactam is adjusted to 3.5:1, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0144] Comparative Example 8

[0145] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / 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, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0146] Comparative Example 9

[0147] This comparative example provides a method for preparing a high-efficiency granular clay adsorbent for deolefination / 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 the other process parameters and operating steps are exactly the same as those in Example 1.

[0148] The activity, pore size, denitrification rate and olefin removal rate of the high-efficiency granular clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-9 were tested. The specific test steps are as follows:

[0149] (1) Activity test:

[0150] Activity is an important indicator to measure the adsorption performance of activated clay. It is usually expressed as the volume (mL) of NaOH standard solution [c(NaOH=1.000mol / L] consumed to neutralize 1000g of clay sample.

[0151] The present invention measures the activity of the high-efficiency granular clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-9 with reference to the industry standard HG / T2569-2007 "Activated Clay".

[0152] (2) Aperture test:

[0153] The pore size of the samples was analyzed and detected using a fully automatic gas adsorption analyzer. Before the test, the samples were degassed at 150°C under vacuum conditions for 7 h, and then the nitrogen adsorption-desorption performance test was performed.

[0154] (3) Denitrification rate test:

[0155] The raw material for denitrification activity evaluation was aromatic raffinate oil provided by a petrochemical company, with a nitrogen content of 12.51 μg / g.

[0156] The denitrification evaluation device is a tubular fixed-bed reaction device. The outside of the reaction device is equipped with an electric heating temperature control system. 100g of adsorbent is loaded in the catalyst bed of the reaction device. The aromatic raffinate oil is metered and pressurized to 0.8MPa by a pump. It enters the preheater at a certain air velocity and enters the adsorbent bed after being heated to 40°C. The raffinate oil product after denitrification refinement is cooled and then enters the low-fraction tank. The refined product is sampled and analyzed regularly, and the nitrogen content in the refined product is greater than 0.5μg / g as the deactivation standard of the solid adsorbent.

[0157] The total nitrogen content in raw materials and products adopts SH / T0657-2007 "Determination of trace nitrogen in liquid petroleum hydrocarbons - Oxidative combustion and chemiluminescence method", and the denitrification rate is calculated based on the total nitrogen content in the raw materials and the total nitrogen content in the products.

[0158] (4) Olefin removal rate test:

[0159] The raw material for the deolefination activity evaluation was reforming oil provided by a petrochemical company, with a bromine index of 670 mgBr / 100 g.

[0160] Deolefin evaluation unit such as Figure 2 As shown, it includes 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 three sections: upper, middle, and lower. The upper and lower sections are respectively filled with a certain amount of 20-40 mesh quartz sand. The middle section is a constant temperature section, filled with 5 mL of adsorbent and hammered with a leather hammer. The evaluation conditions are temperature 170 ° C, pressure 1 MPa, and volume space velocity 10 h -1 , sampling was taken every 2 hours, and the bromine index of the raw materials and products was determined using the national standard GB / T 5177-2017 "Industrial Linear Alkylbenzene". The smaller the bromine index of the aromatic deolefination product, the lower the olefin content, indicating that the adsorbent has a better deolefination effect.

[0161] The olefin removal rate of aromatic products is calculated using the following formula:

[0162]

[0163] The test results are shown in Table 1.

[0164] Table 1 Performance test results of high-efficiency granular clay adsorbents prepared in Examples 1-5 and Comparative Examples 1-9

[0165]

[0166] The test data provided in Table 1 demonstrates that the high-efficiency granular clay adsorbent prepared in accordance with the present invention exhibits high activity and a large pore size, resulting in excellent removal rates for olefin and nitrogen removal. Test results show that the high-efficiency granular clay adsorbent prepared in accordance with the present invention exhibits an activity exceeding 215 mmol / 100 g, demonstrating its extremely strong adsorption activity and reactivity, enabling the adsorbent to more effectively interact with target substances (such as nitrogen compounds and olefins), thereby improving adsorption efficiency and removal rate. Furthermore, the average pore size of the high-efficiency granular clay adsorbent prepared in accordance with the present invention exceeds 36 nm. This large pore size not only facilitates the rapid diffusion and transport of adsorbates (such as nitrogen and olefin molecules), but also provides more adsorption sites, thereby enhancing adsorption capacity and rate. Due to the combined effects of high activity and large pore size, the high-efficiency granular clay adsorbent prepared in accordance with the present invention achieved a denitrification rate exceeding 95% in denitrification activity evaluation tests and an olefin removal rate exceeding 90% in deolefination activity evaluation tests. These data fully demonstrate the significant advantages of the clay adsorbent prepared in accordance with the present invention in both olefin and nitrogen removal.

[0167] It can be seen from the test data of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 that the denitrification rates and olefin removal rates 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 from the acidulant of Comparative Example 1, sulfuric acid is omitted from the acidulant of Comparative Example 2, and oxalic acid is omitted from the acidulant of Comparative Example 3. This shows that the acidification modification of bentonite by a 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 the activated clay, thereby greatly improving the adsorption capacity of the high-efficiency granular clay adsorbent.

[0168] 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 lower than those of Example 1. This is because the amount of cetyltrimethylammonium bromide in Comparative Example 4 is too low, and the amount of cetyltrimethylammonium bromide in Comparative Example 5 is too high. The amount of cetyltrimethylammonium bromide directly affects the intercalation modification effect of the activated clay, thereby affecting the adsorption capacity of the high-efficiency granular clay adsorbent.

[0169] The test data for Example 1, Comparative Examples 6, and 7 show that the denitrification and olefin removal rates in Comparative Examples 6 and 7 are lower than those in Example 1. This is because the amount of cetyltrimethylammonium bromide in Comparative Example 6 is too low, while the amount of caprolactam is relatively high; while the amount of cetyltrimethylammonium bromide in Comparative Example 7 is too high, while the amount of caprolactam is relatively low. The ratio of cetyltrimethylammonium bromide to caprolactam directly affects the intercalation modification effect on the activated clay, thereby affecting the adsorption capacity of the high-efficiency granular clay adsorbent.

[0170] 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 lower than those of Example 1. This is because the amount of magnesium chloride in Comparative Example 8 is too low, resulting in less magnesium oxide being generated, and the pore size of the high-efficiency granular clay adsorbent cannot be effectively increased; in Comparative Example 9, the amount of magnesium chloride is too high, resulting in excessive magnesium oxide being generated and agglomerating, which also affects the pore size of the high-efficiency granular clay adsorbent, and ultimately leads to a decrease in the adsorption capacity of the high-efficiency granular clay adsorbent.

[0171] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection 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 scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a granular clay adsorbent for deolefination or denitrification, characterized in that: The preparation method comprises: (I) Concentrated hydrochloric acid, concentrated sulfuric acid, oxalic acid, and deionized water are mixed to obtain an acidifier, bentonite ore is crushed and sieved to obtain bentonite powder, and the bentonite powder is mixed with deionized water to obtain a bentonite slurry; the bentonite slurry, the acidifier, and sodium chloride are uniformly mixed to obtain a raw material mixture, the raw material mixture is heated and activated to obtain an activated product, and the activated product is rinsed, centrifuged, dried, and crushed to obtain activated clay; (II) performing an organic intercalation modification treatment on the activated clay obtained in step (I) using hexadecyltrimethylammonium bromide and caprolactam to obtain intercalation modified clay; subsequently, performing a surface hydrophobic modification treatment on the intercalation modified clay using a silane coupling agent to obtain a 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; and after the reaction is completed, filtering, washing, extruding, drying, calcining, and crushing and screening to obtain the 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 mixed evenly 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 mixed evenly to obtain the acidulant.

3. The preparation method according to claim 2, characterized in that The mass fraction of the concentrated hydrochloric acid is 35-37 wt %; 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 5-10 wt %.

4. The preparation method according to claim 1, characterized in that In step (I), the bentonite powder has a particle size of 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 acidifier 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 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; Rinse the activated product 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 conditions of continuous stirring and water bath heating, hexadecyltrimethylammonium bromide and caprolactam are sequentially added to the clay suspension to react; 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 cetyltrimethylammonium bromide to the clay suspension, continue mixing and stirring under heating in a water bath 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 following steps: 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 intercalated modified clay is (0.02-0.05):1; The reaction temperature of the intercalated 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 2-5 wt%; 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. Use of a granular clay adsorbent for deolefination or denitrification prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The granular clay adsorbent is used in the field of deolefination or denitrification.

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