Plastic oil desiliconizing agent, preparation method thereof and plastic oil desiliconizing method

Abstract

The invention relates to a plastic oil desiliconization agent, a preparation method thereof and a plastic oil desiliconization method, the desiliconization agent comprises 5-95 wt% of magnesium oxide and 5-95 wt% of aluminum oxide on the basis of the dry basis weight of the desiliconization agent, and at least part of magnesium oxide and aluminum oxide form magnesium aluminate spinel, the weight of the magnesium aluminate spinel accounts for more than 60% of the total weight of the magnesium oxide and the aluminum oxide; the bulk density of the desiliconizing agent is 0.5 to 0.85 g / cm < 3 >. The desiliconization agent disclosed by the invention has a good desiliconization effect.

Description

Technical Field

[0001] This application relates to a desilication agent for plastic oil, its preparation method, and a method for desilication plastic oil. Background Technology

[0002] Waste plastic recycling includes energy recovery, mechanical recovery, and chemical recovery. Among these, chemical recycling of waste plastics is considered a sustainable method for recycling waste plastics, as it not only solves environmental pollution problems but also saves energy consumption. Waste plastic pyrolysis is a relatively mature chemical recycling method, which involves converting complex plastic macromolecules into smaller molecule products (usually gases or liquids) primarily composed of hydrocarbons through thermal pyrolysis. These smaller molecules can then be further used to produce petrochemical products.

[0003] Studies have shown that using waste plastic oil as a feedstock for catalytic cracking is theoretically feasible. However, the high silicon and chlorine content in waste plastic oil can negatively impact the catalytic cracking reaction. The silicon species in waste plastic oil mainly originate from the thermal decomposition products of silicon-containing additives in plastics, typically existing as alkylcyclosiloxanes, primarily octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, with a Si content of 10-103 μg / g. During subsequent processing of waste plastic oil, these silicon species mainly deposit on the catalyst surface, affecting catalyst activity.

[0004] Therefore, in the technical route of catalytic conversion of waste plastic oil into low-carbon olefins or oil products, the influence of silicon impurities in the waste plastic oil cannot be ignored. Measures for treating silicon impurities in waste plastic oil include desilication and silicon dissolution. CN113862018A discloses a new technology for removing organosilicon by dissolving waste plastic in a special oil. This technology can reduce the viscosity of waste plastic and improve heat transfer efficiency while removing silicon. However, this technology suffers from problems such as low removal rate and secondary pollution. Summary of the Invention

[0005] The purpose of this disclosure is to provide a desilication agent for plastic oil, its preparation method, and a desilication method for plastic oil. The desilication agent for plastic oil disclosed herein has a superior desilication effect, and the desilication rate is high when it is used for desilication of high-silicon plastic oil.

[0006] To achieve the above objectives, the first aspect of this disclosure provides a desilication agent for pretreatment of plastic oils, wherein, based on the dry weight of the desilication agent, the desilication agent contains 5-95% by weight of magnesium oxide and 5-95% by weight of aluminum oxide, and at least a portion of the magnesium oxide and aluminum oxide forms magnesium aluminum spinel, wherein the weight of the magnesium aluminum spinel accounts for more than 60% of the total weight of the magnesium oxide and the aluminum oxide; the bulk density of the desilication agent is 0.5-0.85 g / cm³. 3 .

[0007] Optionally, the desiliconizing agent contains 10-90% by weight of magnesium oxide and 10-90% by weight of aluminum oxide, and at least a portion of the magnesium oxide and aluminum oxide form a magnesium aluminum spinel structure.

[0008] Optionally, the bulk density of the desilication agent is 0.55-0.83 g / cm³. 3 .

[0009] Optionally, the abrasion index of the desiliconizing agent is 1.5-3.0%.

[0010] Optionally, based on the dry weight of the desiliconizing agent, the desiliconizing agent contains 10-90% by weight of magnesium oxide, 10-90% by weight of aluminum oxide, and 0-20% by weight of a third component; the third component is selected from binders and / or clay.

[0011] Preferably, the binder is selected from one or more of silicon dioxide, calcium oxide, titanium dioxide and zirconium oxide, and the clay is selected from one or more of kaolin, metakaolin, sepiolite, attapulgite, montmorillonite, calcite, diatomite, halloysite, soapstone, boronite and hydrotalcite.

[0012] A second aspect of this disclosure provides a method for preparing the desilication agent provided in the first aspect of this disclosure, the method comprising:

[0013] S1. The aluminum source, acid and water are mixed for the first time to obtain the first slurry;

[0014] S2. The first slurry and the insoluble magnesium source are mixed for a second time, and the resulting second slurry is spray-dried to obtain solid microspheres;

[0015] S3. The solid microspheres, water-soluble magnesium source and water are mixed for the third time, and the resulting mixture is calcined.

[0016] Optionally, the solid content of the first slurry is 10-40% by weight, and the pH value is 1-6; the conditions for the first mixing include: a temperature of 10-50°C and a time of 15-40 min.

[0017] The second slurry has a solid content of 10-30% by weight and a pH value of 7-10; the second mixing conditions include a temperature of 50-60℃ and a time of 40-90 min.

[0018] The conditions for the third mixing include: a temperature of 10-40℃ and a time of 5-15 minutes.

[0019] Optionally, in step S2, the average particle size of the solid microspheres is 70-85 μm, the volume of solid microspheres with a particle size in the range of 0-149 μm accounts for 85-95% of the total volume of the solid microspheres, and the volume of solid microspheres with a particle size in the range of 0-40 μm accounts for 8-18% of the total volume of the solid microspheres.

[0020] Optionally, the aluminum source is selected from one or more of aluminum hydroxide, alumina, gibbsite, boehmite, diaspore, boehmite, and pseudoboehmite; the acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

[0021] The non-water-soluble magnesium source is selected from one or more of magnesium oxide, magnesium hydroxide, and magnesium carbonate;

[0022] The water-soluble magnesium source is selected from one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium chlorate, and magnesium acetate.

[0023] The third aspect of this disclosure provides a method for desiliconization pretreatment of plastic oil, the method comprising: contacting the plastic oil with a desiliconizing agent at 150-250°C to perform desiliconization pretreatment, wherein the desiliconizing agent is the desiliconizing agent provided in the first aspect of this disclosure.

[0024] Optionally, the desilication pretreatment is carried out in a fluidized bed reactor or a conveyor bed reactor, and the plastic oil is introduced from the bottom of the fluidized bed reactor or the bottom of the conveyor bed reactor.

[0025] Through the above technical solution, the desilication agent disclosed herein has a superior desilication effect.

[0026] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is the XRD pattern of the desilication agent A1 prepared in Example 1 of this disclosure. Detailed Implementation

[0029] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0030] The first aspect of this disclosure provides a desilicifying agent for pretreatment of plastic oils, wherein, based on the dry weight of the desilicifying agent, the desilicifying agent contains 5-95% by weight of magnesium oxide and 5-95% by weight of aluminum oxide, and at least a portion of the magnesium oxide and aluminum oxide forms magnesium aluminum spinel, wherein the weight of the magnesium aluminum spinel accounts for more than 60% of the total weight of the magnesium oxide and the aluminum oxide; the bulk density of the desilicifying agent is 0.5-0.85 g / cm³. 3 .

[0031] The inventors of this disclosure have discovered that conventional desilication agents, due to their high viscosity, do not mix well with plastic oils. The desilication agent of this disclosure has a suitable bulk density, allowing for more thorough mixing and contact with the plastic oil. This enables the organosilicon in the plastic oil to better diffuse into the pores of the desilication agent, promoting a desilication reaction between the organosilicon and the active component, magnesium aluminum spinel. The desilication agent of this disclosure exhibits excellent desilication performance and a high desilication rate when used for the pretreatment of plastic oils.

[0032] In this disclosure, the bulk density of the desilication agent was determined using the RIPP standard method (see "Analytical Methods in Petrochemical Industry (RIPP Experimental Method)," edited by Yang Cuiding et al., Science Press, 1990). XRD analysis of the desilication agent was used to determine whether a magnesium-aluminum spinel structure formed from magnesium oxide and aluminum oxide existed in the desilication agent.

[0033] In a preferred embodiment of this disclosure, the desilication agent contains 10-90% by weight of magnesium oxide and 10-90% by weight of aluminum oxide, and at least a portion of the magnesium oxide and aluminum oxide form a magnesium aluminum spinel structure. Preferably, the desilication agent contains 30-60% by weight of magnesium oxide and 40-70% by weight of aluminum oxide, and the weight of the magnesium aluminum spinel accounts for 60-95% of the total weight of the magnesium oxide and the aluminum oxide.

[0034] In a preferred embodiment of this disclosure, the bulk density of the desilication agent is 0.55-0.83 g / cm³. 3 The preferred value is 0.75-0.83 g / cm³. 3 .

[0035] In a preferred embodiment of this disclosure, the wear index of the desilication agent is 1.5-3.0h. -1 Preferably 1.2-2.5h -1 In this disclosure, the wear index was determined using the RIPP standard method (see "Analytical Methods in Petrochemical Industry (RIPP Experimental Methods)", edited by Yang Cuiding et al., Science Press, 1990).

[0036] According to this disclosure, the desilication agent may also contain a third component, the content of which can vary within a wide range. In a preferred embodiment of this disclosure, based on the dry weight of the desilication agent, the desilication agent contains 10-90% by weight of magnesium oxide, 10-90% by weight of aluminum oxide, and 0-20% by weight of the third component; the third component is selected from binders and / or clay. According to this disclosure, the binder can be one or more of those skilled in the art, for example, the binder can be selected from one or more of silica, calcium oxide, titanium oxide, and zirconium oxide. The clay can also be one or more of those skilled in the art, for example, the clay can be selected from one or more of kaolin, metakaolin, sepiolite, attapulgite, montmorillonite, tert-tungsten, diatomaceous earth, halloysite, soapstone, boronite, and hydrotalcite, more preferably, the clay is selected from one or more of kaolin, diatomaceous earth, sepiolite, attapulgite, montmorillonite, and tert-tungsten.

[0037] The second aspect of this disclosure provides a method for preparing the desilication agent provided in the first aspect of this disclosure. The method includes: S1, mixing an aluminum source, an acid, and water to obtain a first slurry; S2, mixing the first slurry with a non-water-soluble magnesium source to obtain a second slurry, and spray-drying the obtained second slurry to obtain solid microspheres; S3, mixing the solid microspheres, a water-soluble magnesium source, and water to obtain a third slurry, and calcining the obtained mixture.

[0038] The inventors of this disclosure have discovered that, by employing the method of this disclosure, particularly by introducing insoluble and water-soluble magnesium sources stepwise during the preparation process, it is possible to prepare a product with a bulk density of 0.5-0.85 g / cm³. 3 Furthermore, the desiliconizing agent with a magnesium-aluminum spinel structure has a good desiliconizing effect. When used for desiliconizing pretreatment of high-silicon plastic oil, the silicon removal rate reaches 98%, which is beneficial for subsequent pretreatment of plastic oil.

[0039] According to this disclosure, the solid content of the first slurry can vary within a wide range. In one specific embodiment of this disclosure, the solid content of the first slurry is 10-40% by weight, and the pH value is 1-6. The conditions for the first mixing include a temperature of 10-50°C and a time of 15-40 min.

[0040] According to this disclosure, the solid content of the second slurry can vary within a wide range. In one specific embodiment of this disclosure, the solid content of the second slurry is 10-30% by weight, and the pH value is 7-10. The conditions for the second mixing include a temperature of 50-60°C and a time of 40-90 min.

[0041] In one specific embodiment of this disclosure, the conditions for the third mixing include: a temperature of 10-40°C and a time of 5-15 minutes. In this disclosure, mixing can be performed using a stirring method, such as magnetic stirring or mechanical stirring, and the mixing time can be the same as the stirring time.

[0042] According to this disclosure, the aluminum source can be any aluminum source known to those skilled in the art, and can be any aluminum source that can be dissolved by acid. In one specific embodiment of this disclosure, the aluminum source is selected from one or more of aluminum hydroxide, aluminum oxide, gibbsite, boehmite, boehmite, boehmite, and boehmite. Among them, aluminum oxide can include, but is not limited to, p-alumina, χ-alumina, η-alumina, γ-alumina, κ-alumina, δ-alumina, θ-alumina, etc.

[0043] According to this disclosure, the acid may be selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid.

[0044] According to this disclosure, the water-insoluble magnesium source may be selected from one or more of magnesium oxide, magnesium hydroxide, and magnesium carbonate.

[0045] According to this disclosure, the water-soluble magnesium source refers to any magnesium source that can dissolve in water. In one embodiment, the water-soluble magnesium source can be a water-soluble magnesium salt, including but not limited to one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium chlorate, and magnesium acetate.

[0046] According to this disclosure, in step S2, the average particle size of the solid microspheres is 70-85 μm, the volume of solid microspheres with a particle size in the range of 0-149 μm accounts for 85-95% of the total volume of the solid microspheres, and the volume of solid microspheres with a particle size in the range of 0-40 μm accounts for 8-18% of the total volume of the solid microspheres.

[0047] According to this disclosure, in step S3, the calcination can be carried out in an apparatus well known in the art, such as a tube furnace or a muffle furnace, and this disclosure does not impose any specific limitations. The calcination atmosphere can be an air atmosphere, and the calcination conditions can include: a temperature of 500-700℃ and a time of 2-5 hours.

[0048] The third aspect of this disclosure provides a method for desiliconization pretreatment of plastic oil, the method comprising: contacting the plastic oil with a desiliconizing agent at 150-250°C to perform desiliconization pretreatment, wherein the desiliconizing agent is the desiliconizing agent provided in the first aspect of this disclosure.

[0049] In one specific embodiment, the desilication pretreatment is carried out in a fluidized bed reactor or a conveyor bed reactor, and the plastic oil is introduced from the bottom of the fluidized bed reactor or the bottom of the conveyor bed reactor.

[0050] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0051] In this disclosure, the weight on a dry basis refers to the weight after calcination at about 800°C for 1 hour.

[0052] In this disclosure, the solid content of a substance refers to the ratio of the weight of the substance after high-temperature roasting to its weight before roasting, i.e., solid content of the substance = 100% - water content of the substance.

[0053] In this disclosure, the desilicifying agent-to-oil ratio refers to the mass ratio of the desilicifying agent to the raw oil.

[0054] In the examples and comparative examples, the kaolin was sourced from Suzhou, China (76.9% by weight solids), the boehmite was supplied by Shandong Aluminum Plant (60.8% by weight solids), and the magnesium oxide and magnesium chloride were supplied by Hebei Magnesium Chemical Co., Ltd. Unless otherwise specified, all chemical reagents used in the comparative examples and examples were of chemical purity.

[0055] In all embodiments and comparative examples, the wear index and bulk density were determined using the RIPP standard method (see *Analytical Methods in Petrochemical Industry (RIPP Experimental Method)*, edited by Yang Cuiding et al., Science Press, 1990). The phase composition of the desilication agent was determined using XRD.

[0056] In the examples, the particle size distribution of the solid microspheres was determined by laser particle size distribution method, see NB / SH / T0951-2017 Determination of particle size distribution of catalytic cracking catalysts.

[0057] The weight ratio of magnesium aluminum spinel in the desilication agent to the total weight of magnesium oxide and aluminum oxide was determined by XRD.

[0058] Examples 1-6 illustrate the method for preparing the desilication agent of this disclosure.

[0059] Example 1

[0060] (1) 280g of pseudoboehmite (calculated as Al2O3) was added to deionized water at 25℃, and after being dispersed evenly, hydrochloric acid was added. After contacting for 30 minutes, the first slurry was obtained. The solid content of the first slurry was 15% by weight and the pH was 1.2.

[0061] (2) The first slurry was added to the MgO slurry (containing 640g of MgO) dispersed in deionized water, and the temperature was controlled at 55℃. After contact mixing for 60 minutes, the second slurry was obtained. The solid content of the second slurry was 28% by weight, and the pH value was 9.8. The second slurry was spray-dried to form solid microspheres, wherein the microspheres with a particle size in the range of 0-149 micrometers accounted for 92% by volume, the microspheres with a particle size in the range of 0-40 micrometers accounted for 12% by volume, and the average particle size (APS) of the microspheres was 70 micrometers.

[0062] (3) At room temperature (10-40℃), 920g of solid microspheres were contacted and mixed with 0.35L of water-soluble magnesium source solution (properties shown in Table 1) for 10min. The mixture after contact was dried at 120℃ for 4 hours and then calcined at 600℃ for 2h to obtain desilication agent A1.

[0063] The formulation, preparation parameters, bulk density, and wear index of desilication agent A1 are listed in Table 1. The XRD pattern of desilication agent A1 is shown below. Figure 1 ,Depend on Figure 1 It can be seen that the desiliconizing agent contains a magnesium aluminum spinel structure, that is, at least part of the magnesium oxide and aluminum oxide in the desiliconizing agent form magnesium aluminum spinel.

[0064] Examples 2-5

[0065] Desilication agents A2-A5 were prepared according to the method in Example 1, except that the formulations used in the preparation were different. The formulation parameters, bulk density and wear index are listed in Table 1.

[0066] Example 6

[0067] (1) 280g of pseudoboehmite (calculated as Al2O3) was added to deionized water at 25℃, and after being dispersed evenly, hydrochloric acid was added. After contacting for 30 minutes, the first slurry was obtained. The solid content of the first slurry was 15% by weight and the pH was 1.2.

[0068] (2) The first slurry was added to a deionized water-dispersed MgO slurry (containing 440g of MgO) and 200g of kaolin. The temperature was controlled at 55℃. After contact mixing for 60 minutes, a second slurry was obtained. The solid content of the second slurry was 28% by weight and the pH value was 9.8. The second slurry was spray-dried to form solid microspheres. Among them, the microspheres with a particle size in the range of 0-149 micrometers accounted for 91% by volume, the microspheres with a particle size in the range of 0-40 micrometers accounted for 11% by volume, and the average particle size (APS) of the microspheres was 68 micrometers.

[0069] (3) At room temperature (10-40℃), 920g of solid microspheres were contacted and mixed with 0.35L of water-soluble magnesium source solution (properties shown in Table 1) for 10min. The mixture after contact was dried at 120℃ for 4 hours and then calcined at 600℃ for 2h to obtain desilication agent A6.

[0070] The formulation, preparation parameters, bulk density and wear index of desilication agent A6 are listed in Table 1.

[0071] Comparative Example 1

[0072] SB powder (containing 560g of Al2O3) was added to deionized water and dispersed evenly. Formic acid was then added and dissolved for 30 minutes to obtain the first slurry. The pH value of the first slurry was measured to be 3.3.

[0073] The first slurry was added to 1046g of MgO slurry (containing 440g of MgO) dispersed in deionized water, and the mixture was kept at 75℃ for 60 minutes to obtain the second slurry. The pH value of the second slurry was measured to be 9.1. The second slurry was spray-dried and shaped, and then directly calcined at 730℃ for 3 hours. The calcined sample was then sieved, and particles with a particle size of 20-40μm were selected to obtain desilication agent B1.

[0074] The formulation, preparation parameters, bulk density and wear index of desiliconizing agent B1 are listed in Table 2. B1 does not contain magnesium aluminum spinel structure.

[0075] Comparative Example 2

[0076] Desilicon agent B2 was prepared using the same method as in Example 2, except that step (3) was omitted. After the second slurry in step S2 was spray-dried, the obtained solid microspheres were calcined. The formulation, preparation parameters, bulk density and wear index of desilicon agent B1 are listed in Table 2. It does not have a magnesium aluminum spinel structure.

[0077] Examples 7-12 illustrate the performance of desilication agents in desilication plastic oils.

[0078] Example 7

[0079] The desilication performance of the desilication agent on plastic oil was investigated using an ACE apparatus. The plastic oil entered from the bottom of the reactor and contacted the desilication agent. Desilication pretreatment was performed at a reaction temperature of 120°C and an agent-to-oil ratio of 7. The properties of the plastic oil used are shown in Table 3, and the evaluation conditions and results are shown in Table 4.

[0080] Comparative Examples 3-4 are used to illustrate the desilication performance of the comparative desilication agents.

[0081] Comparative Examples 3-4

[0082] The desilication performance of the desilication agent on plastic oil was investigated using the same method as in Example 7, except that the desilication agent used was the one prepared in Comparative Examples 1-2.

[0083] Table 1

[0084]

[0085]

[0086]

[0087] In Table 1, the proportion of magnesium aluminum spinel refers to the ratio of the weight of magnesium aluminum spinel to the total weight of magnesium oxide and aluminum oxide in the desilication agent.

[0088] Table 2

[0089]

[0090]

[0091] Table 3

[0092] Properties of plastic oil <![CDATA[Density (20 °C) / (g / cm 3 )]]> 0.9048 <![CDATA[Viscosity (80 °C) / (mm 2 / s)]]> 18.54 <![CDATA[Viscosity (at 100 °C) / (mm 2 / s)]]> 10.89 Pour point / °C 38 Aniline point / °C 92.5 Carbon residue / % 2.8 Refractive index (70℃) 1.4912 Element content / mass % C 86.09 H 12.51 S 0.65 N 0.28 Si 0.15 Distillation range (D1160) / ℃ Initial boiling point 233 5％ 295 10％ 333 30％ 395 50％ 429 70％ 470 90％ 539

[0093] Table 4

[0094] Desilicon agent number Desiliconization rate / % Example 7 A1 97 Example 8 A2 98 Example 9 A3 95 Example 10 A4 99 Example 11 A5 95 Example 12 A6 92 Comparative Example 3 B1 32 Comparative Example 4 B2 24

[0095] As shown in Table 4, the desilicifying agent disclosed herein has an extremely high silicon removal rate and superior effect when used for the desilicification pretreatment of plastic oil.

[0096] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0097] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0098] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A desilicifying agent for pretreatment of plastic oil, comprising, based on the dry weight of the desilicifying agent, 5-95% by weight of magnesium oxide and 5-95% by weight of aluminum oxide, wherein at least a portion of the magnesium oxide and aluminum oxide forms magnesium aluminum spinel, the weight of the magnesium aluminum spinel accounting for more than 60% of the total weight of the magnesium oxide and the aluminum oxide; and the bulk density of the desilicifying agent is 0.5-0.85 g / cm³. 3 .

2. The desilication agent according to claim 1, wherein, The desiliconizing agent contains 10-90% by weight of magnesium oxide and 10-90% by weight of aluminum oxide, and at least a portion of the magnesium oxide and aluminum oxide form magnesium aluminum spinel, wherein the weight of the magnesium aluminum spinel accounts for 60-95% of the total weight of the magnesium oxide and the aluminum oxide.

3. The desilication agent according to claim 1, wherein, The bulk density of the desilication agent is 0.55-0.83 g / cm³. 3 .

4. The desilication agent according to claim 1, wherein, The wear index of the desiliconizing agent is 1.5-3.0%.

5. The desilication agent according to claim 1, wherein, Based on the dry weight of the desiliconizing agent, the desiliconizing agent contains 10-90% by weight of magnesium oxide, 10-90% by weight of aluminum oxide, and 0-20% by weight of a third component; the third component is selected from binders and / or clay. Preferably, the binder is selected from one or more of silicon dioxide, calcium oxide, titanium dioxide and zirconium oxide; the clay is selected from one or more of kaolin, metakaolin, sepiolite, attapulgite, montmorillonite, calcite, diatomite, halloysite, soapstone, boronite and hydrotalcite.

6. A method for preparing the desilication agent according to any one of claims 1-5, the method comprising: S1. The aluminum source, acid and water are mixed for the first time to obtain the first slurry; S2. The first slurry and the insoluble magnesium source are mixed for a second time, and the resulting second slurry is spray-dried to obtain solid microspheres; S3. The solid microspheres, water-soluble magnesium source and water are mixed for the third time, and the resulting mixture is calcined.

7. The method according to claim 6, wherein, The first slurry has a solid content of 10-40% by weight and a pH value of 1-6; the first mixing conditions include a temperature of 10-50℃ and a time of 15-40 min. The second slurry has a solid content of 10-30% by weight and a pH value of 7-10; the second mixing conditions include a temperature of 50-60℃ and a time of 40-90 min. The conditions for the third mixing include: a temperature of 10-40℃ and a time of 5-15 minutes.

8. The method according to claim 6, wherein, In step S2, the average particle size of the solid microspheres is 70-85 μm, the volume of solid microspheres with a particle size in the range of 0-149 μm accounts for 85-95% of the total volume of the solid microspheres, and the volume of solid microspheres with a particle size in the range of 0-40 μm accounts for 8-18% of the total volume of the solid microspheres.

9. The method according to claim 6, wherein, The aluminum source is selected from one or more of aluminum hydroxide, aluminum oxide, gibbsite, boehmite, boehmite, diatomite, and pseudoboehmite. The acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid; The non-water-soluble magnesium source is selected from one or more of magnesium oxide, magnesium hydroxide, and magnesium carbonate; The water-soluble magnesium source is selected from one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium chlorate, and magnesium acetate.

10. A method for pretreatment of plastic oil for desilicification, the method comprising: At 150-250°C, plastic oil is brought into contact with a desilication agent for desilication pretreatment, wherein the desilication agent is the desilication agent described in any one of claims 1-5.

11. The method according to claim 10, wherein, The desilication pretreatment is carried out in a fluidized bed reactor or a conveyor bed reactor, and the plastic oil is introduced from the bottom of the fluidized bed reactor or the bottom of the conveyor bed reactor.

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