Modified kaolin as well as preparation method and application thereof

Abstract

The invention relates to modified kaolin as well as a preparation method and application thereof, the modified kaolin contains 30-70wt% of aluminum oxide, 30-70wt% of silicon dioxide and 0-40wt% of modified metal in terms of oxide, and the modified metal is selected from one or more of IA, IIA, IVB and lanthanide metals; the density of weakly alkaline sites on the surface of the modified kaolin is 50-800 [mu] mol / g, the density of neutral alkaline sites on the surface of the modified kaolin is 100-2000 [mu] mol / g, and the density of strong alkaline sites on the surface of the modified kaolin is 60-2000 [mu] mol / g; and the density of surface acidic sites is 50-500 [mu] mol / g. The surface of the modified kaolin provided by the invention is rich in weak, medium and strong alkaline sites and acidic sites at the same time; according to the preparation method, by limiting a modification formula, the acid-base property of the surface of kaolin is regulated and controlled, and the technological process is simple; the modified kaolin provided by the invention can be applied to the fields of catalysts, fillers, ceramics, coatings, medical textiles and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a modified kaolin, a preparation method and application thereof. BACKGROUND

[0002] Kaolin is an important and common industrial catalyst raw material, which has low specific surface, low type and density of surface active center, and is often used as an inert matrix or filler. However, after modification, it can be endowed with rich organizational structure properties, thereby widening its application and being more suitable for the iteration and upgrading of the synthesized materials (catalytic materials, filling materials, special materials, etc.). There are many reports on the modification methods of kaolin in the prior art.

[0003] CN102188963A discloses a preparation method of modified kaolin, which is to add high-temperature calcined kaolin, an external aluminum source and an acidic solution into a container under stirring, and then react at 90-150℃ after uniform stirring. The obtained slurry can be directly used as a raw material for preparing a catalytic cracking catalyst without filtration.

[0004] CN105983449A discloses a preparation method of a catalytic cracking catalyst for bottom oil prepared by using kaolin, which is to contact calcined kaolin microspheres with an alkaline solution at room temperature to 100℃ for not less than 1h, filter the obtained slurry, and then mix it with clay and a dispersing agent, spray, calcine and exchange to obtain a catalytic cracking catalyst for bottom oil.

[0005] CN100478069A discloses a modification method of kaolin, which is to mix kaolin, a dispersion modifier, an acid solution and deionized water, and then perform beating, calcination, cooling and washing to obtain modified kaolin. The modified kaolin as a matrix of a cracking catalyst has improved catalytic activity for heavy oil cracking, increased gasoline yield and reduced dry gas yield.

[0006] CN109692702A discloses a preparation method of a macroporous kaolinite, which is to mix calcined kaolin, an acid compound and a modified metal compound, re-calcine, and then mix with an acid solution, a pore-expanding agent and the metal to obtain a macroporous kaolinite. The macroporous kaolinite has high cracking activity and can be used to prepare a cracking catalyst, and the obtained catalyst has high gasoline yield and octane value and low coke selectivity.

[0007] The above prior art does not report how to endow kaolin with unique surface basic properties, and the basic properties have wide application in petrochemical industry, sewage treatment and drug synthesis. Therefore, it is of great significance to develop a modified kaolin with unique surface basic properties for the development of these fields. SUMMARY

[0008] The present application aims to overcome the inertness of the kaolin used in the preparation of catalysts and provide a modified kaolin, a preparation method and application thereof.

[0009] In the first aspect, the present application provides a modified kaolin, which contains 30-70wt% of alumina, 30-70wt% of silica and 0-40wt% of modified metal in terms of oxide, the modified metal being selected from one or more of IA, IIA, IVB and lanthanide series metals; the density of weak basic sites on the surface of the modified kaolin is 50-800μmol / g, the density of medium basic sites is 100-2000μmol / g, and the density of strong basic sites is 60-2000μmol / g; and the density of surface acid sites is 50-500μmol / g.

[0010] The surface basic sites correspond to the CO2 desorption temperature in the CO2-TPD test, and the surface acid sites correspond to the NH3 desorption temperature in the NH3-TPD test.

[0011] The weak basic sites correspond to the acid adsorption sites from which CO2 escapes in the range of room temperature-200℃, the medium basic sites correspond to the acid adsorption sites from which CO2 escapes in the range of 200-600℃, and the strong basic sites correspond to the acid adsorption sites from which CO2 escapes in the range of 600-800℃.

[0012] In the second aspect, the present application provides a preparation method of the modified kaolin, which comprises the following steps:

[0013] (1) calcining kaolin at a temperature of 400-1200℃ for 0.5-10h to obtain metakaolin;

[0014] (2) mixing the metakaolin with water to obtain a metakaolin slurry, and treating the metakaolin slurry with a shearing machine to obtain a slurry metakaolin;

[0015] (3) mixing an inorganic acid with the slurry metakaolin to obtain a mixture with pH<1.5, and filtering and washing the mixture to obtain the acid-treated metakaolin;

[0016] (4) mixing the silicon source, the modified metal salt solution, the non-ionic surfactant, the biomass-based microcrystalline hydrophobic material and the oil to obtain a mixture, and then mixing the mixture with the acid-treated metakaolin to obtain a modified mixture, wherein the mass ratio of the silicon source, the modified metal salt, the non-ionic surfactant, the biomass-based microcrystalline hydrophobic material, the oil, and the metakaolin is 1:0-12:0.1-3:0.4-10:0.1-5:10-80, and the mass concentration of the metal salt in the modified metal salt solution is 5-30 wt.%;

[0017] (5) filtering, washing, drying and calcining the modified mixture to obtain the modified metakaolin.

[0018] In a third aspect, the present application provides an application of the modified metakaolin in catalysts, fillers, ceramics, paints, medical textiles.

[0019] Compared with the prior art, the modified metakaolin and the preparation method thereof provided by the present application have the following beneficial effects:

[0020] (1) The modified metakaolin provided by the present application has unique surface acid-base properties, specifically, there are abundant weak, medium and strong alkaline sites on the surface of the modified metakaolin, and a certain amount of acid sites are also present on the surface of the modified metakaolin; the modified metakaolin presents a sheet-like aggregate, and the pore size is irregular.

[0021] (2) The preparation method of the modified metakaolin provided by the present application enhances the surface acid-base properties of the metakaolin, and the process flow is simple and convenient for industrial production; the modified metakaolin prepared by the present application has a catalytic effect of reducing the coke yield when applied to the catalytic cracking reaction of heavy oil.

[0022] (3) The modified metakaolin provided by the present application can be applied in the fields of catalysts, fillers, ceramics, paints, medical textiles and the like. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The CO2-TPD spectrum of the modified metakaolin prepared in Example 1 and Comparative Examples 1-2.

[0024] Figure 2 The NH3-TPD spectrum of the modified metakaolin prepared in Example 1 and Comparative Examples 1-2.

[0025] Figure 3 The N2 isotherm adsorption line of the modified metakaolin prepared in Example 1.

[0026] Figure 4 The pore size distribution graph of the modified metakaolin prepared in Example 1. DETAILED DESCRIPTION

[0027] The following detailed description of the application is not intended to limit the application. The endpoints of the ranges and any values disclosed in this document are not limited to the precise values stated. The ranges and values are approximations that are intended to convey the meaning within the scope of the disclosure. For numeric values, the endpoints of the ranges, the endpoints of the ranges and individual points, and individual points can be combined with each other to form one or more new numeric ranges, which should be considered as specifically disclosed herein.

[0028] In a first aspect, the present application provides a modified kaolin, comprising 30-70 wt% of alumina, 30-70 wt% of silica and 0-40 wt% of modifying metal in terms of oxide, said modifying metal being selected from one or more of IA, IIA, IVB and lanthanide series metals; the density of weak basic sites on the surface of the modified kaolin is 50-800 μmol / g, the density of medium basic sites is 100-2000 μmol / g, and the density of strong basic sites is 60-2000 μmol / g; the density of surface acidic sites is 50-500 μmol / g.

[0029] In the CO2-TPD test, CO2 desorption temperature < 200°C corresponds to the weak basic sites, CO2 desorption temperature in the range of 200-600°C corresponds to the medium basic sites, and CO2 desorption temperature > 600°C corresponds to the strong basic sites; in the NH3-TPD test, NH3 desorption temperature < 200°C corresponds to the weak acidic sites, and desorption temperature ≥ 600°C corresponds to the strong acidic sites.

[0030] In the CO2-TPD test, CO2 desorption temperature < 200°C corresponds to the weak basic sites, CO2 desorption temperature in the range of 200-600°C corresponds to the medium basic sites, and CO2 desorption temperature > 600°C corresponds to the strong basic sites; in the NH3-TPD test, NH3 desorption temperature < 200°C corresponds to the weak acidic sites, and desorption temperature ≥ 600°C corresponds to the strong acidic sites.

[0031] Preferably, the modified kaolin comprises 30-48 wt% of alumina, 30-52 wt% of silica and 1-25 wt% of modifying metal in terms of oxide. More preferably, the modified kaolin comprises 30-48 wt% of alumina, 32-52 wt% of silica and 1-20 wt% of modifying metal.

[0032] Preferably, the specific surface area of the modified kaolin is 30-80 m 2 / g, preferably 40-50 m 2 / g.

[0033] Preferably, the density of weak basic sites on the surface of the modified kaolin is 80-600 μmol / g; the density of medium basic sites is 120-1600 μmol / g, and the density of strong basic sites is 80-1400 μmol / g; the density of acid sites on the surface of the modified kaolin is 100-350 μmol / g.

[0034] The inventors of the present application have found that kaolin is a surface-inert mineral and is widely used in catalysts, paints, enamel, building materials and the like. Etching the surface of kaolin to make it have unique surface basic properties can expand its application in the field of catalyst preparation. Kaolin is activated at high temperature, slurried and sheared, and treated with a modified mixture, so that the surface of the kaolin is endowed with rich basic sites, so that the surface has the characteristics of high density of weak basic sites, medium basic sites and strong basic sites, and the surface has acid characteristics.

[0035] In one specific embodiment of the present application, based on the total weight of the modified kaolin, the content of alumina is 30-70 wt%, and the content of silicon dioxide is 30-70 wt%, and no modified metal component is contained. In the modified kaolin, the density of weak basic sites on the surface is 50-800 μmol / g, the density of medium basic sites is 100-2000 μmol / g, and the density of strong basic sites is 60-2000 μmol / g; the density of acid sites on the surface is 50-500 μmol / g.

[0036] In one preferred embodiment of the present application, based on the total weight of the modified kaolin, the modified kaolin contains 30-48 wt% of alumina and 30-52 wt% of silicon dioxide, and the content of modified metal, calculated as metal oxide, is 1-25 wt%. In the modified kaolin, the density of weak basic sites on the surface is 80-600 μmol / g; the density of medium basic sites is 120-1600 μmol / g, and the density of strong basic sites is 80-1400 μmol / g; the density of acid sites on the surface of the modified kaolin is 100-350 μmol / g.

[0037] In one preferred embodiment of the present application, the specific surface area of the modified kaolin is 30-80 m 2 / g.

[0038] In one preferred embodiment of the present application, the specific surface area of the modified kaolin is 40-50 m 2 / g.

[0039] In one preferred embodiment of the present application, the modified metal component is selected from one or more of sodium, potassium, magnesium, calcium, zirconium, lanthanum and cerium.

[0040] In a second aspect, the present application provides a method for preparing modified kaolin, comprising the following steps:

[0041] (1) calcining kaolin at a temperature of 400-1200℃ for 0.5-10h to obtain metakaolin;

[0042] (2) mixing metakaolin with water to obtain a metakaolin slurry, and treating the metakaolin slurry with a shearing machine to obtain a slurry metakaolin;

[0043] (3) mixing an inorganic acid with the slurry metakaolin to obtain a mixture with a pH<1.5, and filtering and washing the mixture to obtain acid-treated metakaolin;

[0044] (4) mixing a silicon source, a modified metal salt solution, a non-ionic surfactant, a biomass-based microcrystalline hydrophobic material and an oil with the acid-treated metakaolin, and controlling the pH to be 7.5-8 to obtain a modified mixture; wherein the mass ratio of the silicon source, the modified metal salt, the non-ionic surfactant, the biomass-based microcrystalline hydrophobic material, the oil and the metakaolin is 1:0-12:0.1-3:0.4-10:0.1-5:10-80; and the mass concentration of the metal salt in the modified metal salt solution is 5-30wt%;

[0045] (5) filtering, washing, drying and calcining the modified mixture to obtain modified kaolin.

[0046] In the present application, the inorganic acid comprises a relatively wide selection range. The silicon source can be a soluble inorganic silicon compound or an organic silicon compound; the non-ionic surfactant can be selected from the selection range available in the art, and the present application does not limit the same; and the oil is a fat or an aromatic substance extracted from petroleum or plants.

[0047] Preferably, the silicon source is selected from one or more of tetraethyl orthosilicate, tetramethylsilane, silica aerogel and silicon tetrachloride; the modified metal salt is selected from one or more of chloride salts, nitrate salts, sulfate salts and phosphate salts of IA, IIA, IVB and lanthanide series metals; the non-ionic surfactant is selected from one or more of polyethylene glycol, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, coconut fatty acid ethanolamide, alkyl polyglucoside, polyethylene glycol bis-stearate and sucrose monostearate; the biomass-based microcrystalline hydrophobic material is selected from one or more of microcrystalline cellulose, lignin and hemicellulose; and the oil is selected from one or more of naphtha, lubricating oil, jet fuel, kerosene, diesel, peanut oil, perilla oil and tea tree oil.

[0048] More preferably, the silicon source is selected from one or more of ethyl orthosilicate, tetramethylsilane and silica aerogel, the modified metal salt is selected from one or more of chloride, nitrate and sulfate of IA, IIA, IVB and lanthanide series metals, the non-ionic surfactant is selected from one or more of polyethylene glycol, fatty alcohol polyoxyethylene ether and polyethylene glycol bis-stearate, and the oil is selected from one or more of naphtha, lubricating oil and diesel oil.

[0049] In the present application, the metakaolin framework is destroyed by inorganic acid treatment, and the organic / inorganic silicon in the modified mixture can fill the etched silicon elements in the metakaolin framework, and the inorganic ion salt creates unique alkali active sites in the subsequent calcination process; and the mixing of the non-ionic surfactant, the biomass-based microcrystalline hydrophobic material and the oil can promote the metakaolin to obtain a lamellar stacking structure to a certain extent.

[0050] In the preparation method of the modified metakaolin provided in the present application, preferably, in step (1), the metakaolin calcination temperature is 600-900℃, and the calcination time is 2-6h.

[0051] In step (2), the feeding amount of the metakaolin and water can meet the preparation of the slurry. Preferably, the mass ratio of metakaolin to water is 0.01-0.5:1, and more preferably 0.1-0.35:1; in step (2), the particle size of the slurry metakaolin treated by the shearing machine is 5nm-20μm, and preferably 10nm-15μm.

[0052] In step (3), the inorganic acid and the metakaolin are mixed uniformly under stirring, and the mixture is washed to pH 0-1 to obtain the acid-treated metakaolin.

[0053] In step (4), the modified mixture contains a silicon source, a non-ionic surfactant, a biomass-based microcrystalline hydrophobic material, an oil and metakaolin, with or without a modified metal salt. The mass ratio of the silicon source, the modified metal salt, the non-ionic surfactant, the biomass-based microcrystalline hydrophobic material and the oil is 1:0-12:0.1-3:0.4-10:0.1-5:10-80; and preferably 1:0-6:0.1-2.5:0.5-8:0.3-3:20-50.

[0054] In the present application, the modification mixture in step (4) can change the metakaolin skeleton and enhance the surface acid-base property by regulating the surface structure thereof; in the process of preparing the modification mixture, the mixing temperature is 40-80℃, preferably 50-70℃. In the process of preparing the modification mixture, the mixture is stirred by a stirrer, the stirring speed is 50-1000rpm, preferably 300-1000rpm; the stirring time is 0.5-10h, preferably 1-3h. The pH of the mixture is adjusted to 7.5-8 by using lye, preferably ammonia water, to obtain the modified kaolin mixture.

[0055] Preferably, in step (5), the drying temperature of the mixture is 80-150℃, preferably 100-120℃; the calcination temperature is 400-1000℃, and the calcination time is 1-10h; preferably, the calcination temperature is 500-900℃, and the calcination time is 2-5h.

[0056] In a third aspect, the present application provides a use of the above-mentioned modified kaolin in catalysts, fillers, ceramics, paints, medical textiles.

[0057] The specific embodiments and technical effects of the present application will be further illustrated below in combination with examples and drawings, but the drawings and examples do not constitute a limitation on the present application.

[0058] In the examples and comparative examples:

[0059] The kaolin raw material is Suzhou kaolin, and other chemical reagents are commercially available.

[0060] The content of alumina, silicon oxide and modified metal components in the modified alumina is measured by an X-ray fluorescence spectrometer (XRF).

[0061] The specific surface area parameter is measured by a full-automatic isothermal adsorption instrument.

[0062] The base density and base amount are measured by carbon dioxide-programmed temperature desorption (CO2-TPD); wherein, the CO2 desorption temperature in the range of 50-200℃ represents the CO2 desorption peak of weak basic sites, the CO2 desorption temperature in the range of 200-600℃ represents the CO2 desorption peak of medium basic sites, and the CO2 desorption temperature in the range of 600-800℃ represents the CO2 desorption peak of strong basic sites.

[0063] The acid density and acid amount are measured by amino-programmed temperature desorption (NH3-TPD); wherein, the NH3 desorption temperature in the range of 50-200℃ represents the NH3 desorption peak of weak basic sites, the NH3 desorption temperature in the range of 200-600℃ represents the NH3 desorption peak of medium basic sites, and the NH3 desorption temperature in the range of 600-800℃ represents the NH3 desorption peak of strong basic sites.

[0064] The particle size of the slurry of kaolin is measured by dynamic light scattering particle size analyzer.

[0065] Example 1

[0066] (1) 2 kg of kaolin is calcined at 600℃ for 3h to obtain metakaolin;

[0067] (2) 1 kg of metakaolin is mixed with 2 kg of water at high speed and stirred uniformly, and the slurry of metakaolin is treated by a shearing machine;

[0068] (3) hydrochloric acid and nitric acid are mixed with the slurry of metakaolin according to a ratio of 3:1, and the pH is controlled at 0.8; the mixture is filtered and washed until the pH is neutral to obtain the metakaolin treated by acid;

[0069] (4) 50 g of tetramethylsilane, 500 g of MgCl2 aqueous solution (MgCl2 mass concentration of 30 wt%), 30 g of polyethylene glycol, 100 g of microcrystalline cellulose and 180 g of perilla oil are mixed uniformly, and the mixture is mixed with 1 kg of the metakaolin treated by acid at 60℃, and the pH is adjusted to 7.8 by using ammonia water to obtain a modified mixture;

[0070] (5) the modified mixture is filtered and washed until the pH is neutral, and is dried at 120℃ to obtain a dry product; the dry product is calcined at 600℃ for 2h to obtain modified kaolin S1.

[0071] The CO2-TPD spectrum of the modified kaolin S1 is shown in Figure 1 It can be seen from Figure 1 that the modified kaolin S1 has absorption peaks at 50-200℃, 200-600℃ and 60-800℃, and the densities of the weak basic sites, the medium basic sites and the strong basic sites on the surface are 263.6 μmol / g, 1577.4 μmol / g and 1187.0 μmol / g respectively. The modified kaolin S1 has a relatively strong basic density.

[0072] The NH3-TPD spectrum of the modified kaolin S1 is shown in Figure 2 It can be seen from Figure 2 that the modified kaolin S1 has an absorption peak at 200-300℃, and the density of the weak acid sites on the surface is 300.7 μmol / g.

[0073] The pore size distribution of the modified kaolin S1 is shown in Figure 3 It can be seen from Figure 3 that the modified kaolin S1 has a random lamellar structure.

[0074] The composition and physical property parameters of the modified kaolin S1 are listed in Table 1, and the surface acid and base properties are listed in Table 2.

[0075] Example 2

[0076] (1) 3 kg of kaolin was calcined at 800°C for 2 h to obtain metakaolin;

[0077] (2) 2 kg of metakaolin was mixed with 30 kg of water and stirred at high speed, and the slurry was treated with a shearing machine;

[0078] (3) phosphoric acid was mixed with the slurry metakaolin, and the pH was controlled at 1.5; the mixture was filtered and washed until the pH was neutral to obtain acid-treated metakaolin;

[0079] (4) 20 g of sodium silicate, 500 g of La(NO3)3 aqueous solution (La(NO3)3 mass concentration 20 wt%), 50 g of polyethylene glycol bis-stearate, 160 g of microcrystalline cellulose, and 100 g of peanut oil were uniformly mixed, and the mixture was mixed with 1 kg of acid-treated metakaolin at 55°C, and the pH was adjusted and controlled to remain at 7.5 with ammonia water to obtain a modified mixture;

[0080] (5) the modified mixture was filtered and washed until the pH was neutral, and the mixture was dried at 100°C to obtain a dry product; the dry product was calcined at 600°C for 5 h to obtain modified kaolin S3.

[0081] The composition and physical property parameters of the modified kaolin S3 are shown in Table 1. The surface acid-base properties are shown in Table 2.

[0082] Example 3

[0083] (1) 3 kg of kaolin was calcined at 800°C for 2 h to obtain metakaolin;

[0084] (2) 2 kg of metakaolin was mixed with 30 kg of water and stirred at high speed, and the slurry was treated with a shearing machine;

[0085] (3) phosphoric acid was mixed with the slurry metakaolin, and the pH was controlled at 1.5; the mixture was filtered and washed until the pH was neutral to obtain acid-treated metakaolin;

[0086] (4) 20 g of sodium silicate, 500 g of La(NO3)3 aqueous solution (La(NO3)3 mass concentration 20 wt%), 50 g of polyethylene glycol bis-stearate, 160 g of microcrystalline cellulose, and 100 g of peanut oil were uniformly mixed, and the mixture was mixed with 1 kg of acid-treated metakaolin at 55°C, and the pH was adjusted and controlled to remain at 7.5 with ammonia water to obtain a modified mixture;

[0087] (5) the modified mixture was filtered and washed until the pH was neutral, and the mixture was dried at 100°C to obtain a dry product; the dry product was calcined at 600°C for 5 h to obtain modified kaolin S3.

[0088] The composition and physical property parameters of modified kaolin S3 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0089] Example 4

[0090] (1) 2 kg of kaolin was calcined at 600°C for 5 h to obtain metakaolin;

[0091] (2) 2 kg of metakaolin was mixed with 40 kg of water at high speed and the slurry was treated with a shearing machine;

[0092] (3) Hydrochloric acid and nitric acid were mixed with the slurry of metakaolin at a ratio of 5:1, and the pH was controlled at 1.2; the mixture was filtered and washed until the pH was neutral to obtain acid-treated metakaolin;

[0093] (4) 30 g of silicon tetrachloride, 800 g of zirconyl nitrate aqueous solution (zirconyl nitrate mass concentration 25 wt%), 40 g of sucrose monostearate, 150 g of microcrystalline hemicellulose, and 50 g of lubricating oil were uniformly mixed, and the mixture was mixed with 1 kg of acid-treated metakaolin at 50°C, and the pH was controlled at 7.8 with ammonia water to obtain a modified mixture;

[0094] (5) The modified mixture was filtered and washed until the pH was neutral, and then dried at 120°C to obtain a dry product; the dry product was calcined at 800°C for 2 h to obtain modified kaolin S4.

[0095] The composition and physical property parameters of modified kaolin S4 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0096] Example 5

[0097] (1) 2 kg of kaolin was calcined at 1000°C for 2 h to obtain metakaolin;

[0098] (2) 2 kg of metakaolin was mixed with 5 kg of water at high speed and the slurry was treated with a shearing machine;

[0099] (3) Nitric acid was mixed with the slurry of metakaolin, and the pH was controlled at 0.5; the mixture was filtered and washed until the pH was neutral to obtain acid-treated metakaolin;

[0100] (4) 50 g of tetramethylsilicon, 800 g of NaNO3 aqueous solution (NaNO3 mass concentration 28.8 wt%), 80 g of sucrose distearate, 100 g of microcrystalline lignin, and 60 g of lubricating oil were uniformly mixed, and the mixture was mixed with 2 kg of acid-treated metakaolin at 50°C, and the pH was adjusted and controlled at 7.8 with ammonia water to obtain a modified mixture;

[0101] (5) The modified mixture was filtered, washed to neutral pH, dried at 100°C to obtain a dry product; the dry product was calcined at 800°C for 2h to obtain modified kaolin S5.

[0102] The composition and physical property parameters of modified kaolin S5 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0103] Example 6

[0104] (1) 3kg of kaolin was calcined at 600°C for 3h to obtain metakaolin;

[0105] (2) 3kg of metakaolin was mixed with 3kg of water and stirred at high speed, and the slurry of metakaolin was treated with a shearing machine;

[0106] (3) Nitric acid was mixed with the slurry of metakaolin, and the pH was controlled at 0.5; the mixture was filtered and washed to neutral pH to obtain acid-treated metakaolin;

[0107] (4) 100g of tetraethyl orthosilicate, 2000g of Ce(NO3)3 aqueous solution (25wt% of Ce(NO3)3 mass concentration), 220g of fatty alcohol polyoxyethylene ether, 300g of microcrystalline lignin, and 20g of tea tree oil were mixed uniformly, and the mixture was mixed with 3kg of acid-treated metakaolin at 70°C, and the pH was controlled at 7.8 with ammonia water to obtain a modified mixture;

[0108] (5) The modified mixture was filtered, washed to neutral pH, dried at 100°C to obtain a dry product; the dry product was calcined at 600°C for 3h to obtain modified kaolin S6.

[0109] The composition and physical property parameters of modified kaolin S6 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0110] Example 7

[0111] (1) 1kg of kaolin was calcined at 800°C for 2h to obtain metakaolin;

[0112] (2) 1kg of metakaolin was mixed with 6kg of water and stirred at high speed, and the slurry of metakaolin was treated with a shearing machine;

[0113] (3) Sulfuric acid was mixed with the slurry of metakaolin, and the pH was controlled at 0.5; the mixture was filtered and washed to neutral pH to obtain acid-treated metakaolin;

[0114] (4) 55 g of sodium silicate, 600 g of CaCl2 aqueous solution (CaCl2 mass concentration 25 wt%), 100 g of fatty alcohol polyoxyethylene ether, 240 g of microcrystalline cellulose and 20 g of kerosene were uniformly mixed, and the mixture was mixed with 1 kg of the acid-treated metakaolin at 80°C, ammonia water was used to adjust and control the pH to 7.6 to obtain a modified mixture;

[0115] (5) The modified mixture was filtered, washed to neutral pH, dried at 120°C to obtain a dry product; the dry product was calcined at 800°C for 2h to obtain modified kaolin S7.

[0116] The composition and physical property parameters of the modified kaolin S7 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0117] Example 8

[0118] (1) 2 kg of kaolin was calcined at 900°C for 1h to obtain metakaolin;

[0119] (2) 1 kg of metakaolin was mixed with 5 kg of water and uniformly stirred at high speed, and the slurry metakaolin was treated with a shearing machine;

[0120] (3) Hydrochloric acid and sulfuric acid were mixed with the slurry metakaolin according to the use amount of 2:1, and the pH was controlled at 1; the mixture was filtered and washed to neutral pH to obtain acid-treated metakaolin;

[0121] (4) 20 g of tetraethyl orthosilicate, 400 g of KCl aqueous solution (KCl mass concentration 20 wt%), 150 g of alkylphenol polyoxyethylene ether, 60 g of microcrystalline hemicellulose and 20 g of tea tree oil were uniformly mixed, and the mixture was mixed with 1 kg of the acid-treated metakaolin at 55°C, ammonia water was used to adjust and control the pH to 7.8 to obtain a modified mixture;

[0122] (5) The modified mixture was filtered, washed to neutral pH, dried at 120°C to obtain a dry product; the dry product was calcined at 600°C for 4h to obtain modified kaolin S8.

[0123] The composition and physical property parameters of the modified kaolin S8 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0124] Example 9

[0125] (1) 2 kg of kaolin was calcined at 600°C for 3h to obtain metakaolin;

[0126] (2) 2 kg of metakaolin was mixed with 6 kg of water and uniformly stirred at high speed, and the slurry metakaolin was treated with a shearing machine;

[0127] (3) Hydrochloric acid, nitric acid and sulfuric acid were mixed with the slurry metakaolin in a ratio of 3:2:1, and the pH was controlled at 0.6; the mixture was filtered and washed until the pH was neutral to obtain the acid-treated metakaolin;

[0128] (4) 70 g of tetraethyl orthosilicate, 350 g of polyethylene glycol, 40 g of microcrystalline cellulose and 90 g of diesel oil were uniformly mixed, and the mixture was mixed with 2 kg of the acid-treated metakaolin at 45°C, and the pH was adjusted and controlled to 7.8 with ammonia water to obtain a modified mixture;

[0129] (5) The modified mixture was filtered and washed until the pH was neutral, and then dried at 100°C to obtain a dry product; the dry product was calcined at 600°C for 2 h to obtain modified kaolin S9.

[0130] The composition and physical property parameters of the modified kaolin S9 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0131] Example 10

[0132] (1) 2 kg of kaolin was calcined at 800°C for 2 h to obtain metakaolin;

[0133] (2) 1 kg of metakaolin was mixed with 5 kg of water and stirred at high speed, and the slurry metakaolin was treated with a shearing machine;

[0134] (3) Hydrochloric acid, nitric acid and sulfuric acid were mixed with the slurry metakaolin in a ratio of 4:1:1, and the pH was controlled at 0.5; the mixture was filtered and washed until the pH was neutral to obtain the acid-treated metakaolin;

[0135] (4) 30 g of tetraethyl orthosilicate, 640 g of an aqueous MgCl2 solution (25 wt% of MgCl2), 600 g of polyethylene glycol, 90 g of microcrystalline cellulose and 100 g of lubricating oil were uniformly mixed, and the mixture was mixed with 1 kg of the acid-treated metakaolin at 60°C, and the pH was adjusted and controlled to 8 with ammonia water to obtain a modified mixture;

[0136] (5) The modified mixture was filtered and washed until the pH was neutral, and then dried at 100°C to obtain a dry product; the dry product was calcined at 700°C for 3 h to obtain modified kaolin S10.

[0137] The composition and physical property parameters of the modified kaolin S10 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0138] Comparative Example 1

[0139] According to the method of Example 1, except that there was no metakaolin acid treatment process in step (3), DS1 was obtained.

[0140] The CO2-TPD spectrum of the modified kaolin DS1 is shown inFigure 1 As shown, by Figure 1 It can be seen that the modified kaolin DS1 has a low alkali density.

[0141] The NH3-TPD spectrum of modified kaolin DS1 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the modified kaolin DS1 has a low acid density.

[0142] The composition and physical properties of modified kaolin DS1 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0143] Comparative Example 2

[0144] The method of Example 1 is different except that in step (4), no nonionic surfactant, biomass-based microcrystalline hydrophobic material and oil are added to obtain DS2.

[0145] The CO2-TPD spectrum of modified kaolin DS2 is shown below. Figure 1 As shown, by Figure 1 It can be seen that the modified kaolin DS1 has a low alkali density.

[0146] The NH3-TPD spectrum of modified kaolin DS2 is shown below. Figure 2 As shown, by Figure 2 It can be seen that the modified kaolin DS1 has a low acid density.

[0147] The pore size distribution of modified kaolin DS2 is as follows: Figure 4 As shown, by Figure 4 It can be seen that the modified kaolin DS2 does not exhibit an irregular lamellar structure, and its average pore size is 18 nm.

[0148] The composition and physical properties of modified kaolin DS2 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0149] Comparative Example 3

[0150] The method of Example 1 is the same, except that in step (4), no silicon source and modified metal salt are added to obtain DS3.

[0151] The composition and physical properties of modified kaolin DS3 are listed in Table 1. The surface acid-base properties are listed in Table 2.

[0152] Table 1-1

[0153]

[0154] Table 1-2

[0155]

[0156] Table 1-3

[0157]

[0158] Table 2-1

[0159]

[0160]

[0161] Table 2-2

[0162]

[0163] Table 2-3

[0164]

[0165]

[0166] Example 11

[0167] Catalyst Preparation and Evaluation Examples

[0168] 1 kg of modified matrix S1, 0.7 kg of Y-type molecular sieve, 0.2 kg of pseudoboehmite, 0.13 kg of alumina sol (20 wt%) and 6 kg of water were mixed and pulped at a stirring speed of 500 rpm and a temperature of 15 °C. The slurry was then spray-dried at an inlet temperature of 400 °C and an outlet temperature of 160 °C to obtain a microspherical catalyst precursor. The microspherical catalyst precursor was calcined at 600 °C to obtain catalyst SS1 based on the modified matrix.

[0169] Catalyst evaluation conditions: 2 kg catalyst samples (Example SS1 or Comparative Example SS2) were evaluated in a fixed-bed microreactor. The feedstock was Daqing vacuum residue. The catalyst aging temperature was 790℃, and the water vapor (100% content) was introduced for 17 h during the aging process. The catalytic reaction temperature was 600℃.

[0170] The test results are listed in Table 3. In Table 3, "light oil slurry" specifically refers to "gasoline + diesel".

[0171] Comparative Example 4

[0172] Catalyst preparation and evaluation comparative example

[0173] The modified matrix S1 in the above catalyst preparation example SS1 was replaced with unmodified kaolin, while other processes and raw material amounts were the same as in SS1, to obtain catalyst SS2 based on the unmodified matrix.

[0174] The catalyst evaluation method is the same as in Example 1 of catalyst preparation and evaluation. The test results are shown in Table 3.

[0175] Table 3

[0176]

[0177]

[0178] The results in Tables 1-1, 1-2, 1-3, 2-1, 2-2, and 2-3 show that, compared to Comparative Examples 1-3, the modified kaolin prepared in Examples 1-10 possesses unique surface acid-base properties. Its surface simultaneously exhibits abundant weak, medium, and strong alkaline sites, along with weakly acidic sites. The modified kaolin presents as plate-like aggregates with a dispersed pore size distribution. Furthermore, the test results for catalysts SS1 and SS2 in Table 3 indicate that kaolin with the aforementioned properties can be added as an additive to catalytic reactions using alkaline catalysts, reducing coke production and methane yield while increasing the yield of light oil slurry products. The modified kaolin provided by this invention can be applied in catalysts, fillers, ceramics, coatings, pharmaceuticals, textiles, and other fields.

Claims

1. A modified kaolin, characterized in that, It contains 30-70 wt% alumina, 30-70 wt% silica, and 0-40 wt% modified metal (calculated as oxides), wherein the modified metal is selected from one or more of IA, IIA, IVB and lanthanide metals; the density of weakly basic sites on the surface of the modified kaolin is 50-800 μmol / g, the density of moderately basic sites is 100-2000 μmol / g, the density of strongly basic sites is 60-2000 μmol / g, and the density of acidic sites on the surface is 50-500 μmol / g.

2. The modified kaolin according to claim 1, characterized in that, The specific surface area of ​​the modified kaolin is 30-80 m². 2 / g, preferably 40-50m 2 / g.

3. The modified silicon-aluminum material according to claim 1, characterized in that, The modified kaolin contains 30-48 wt% alumina, 30-52 wt% silicon dioxide, and 0-30 wt% modified metals (calculated as oxides). Preferably, the modified kaolin contains 1-25 wt% modified metal; Preferably, the modified kaolin contains 30-48 wt% alumina, 32-52 wt% silicon dioxide, and 1-20 wt% modified metal.

4. The modified silicon-aluminum material according to any one of claims 1-3, characterized in that, The density of weakly alkaline sites on the surface of modified kaolin is 80-600 μmol / g; the density of moderately alkaline sites is 120-1600 μmol / g; and the density of strongly alkaline sites is 80-1400 μmol / g. The alkaline sites correspond to the CO2 desorption temperature in the CO2-TPD test, and the acidic sites correspond to the NH3 desorption temperature in the NH3-TPD test. Preferably, the density of acidic sites on the surface of the modified kaolin is 100-350 μmol / g.

5. The method for preparing modified kaolin according to any one of claims 1-4, characterized in that, include: (1) Kaolin is calcined at 400-1200℃ for 0.5-10h to obtain metakaolin; (2) Mix metakaolin with water to obtain metakaolin slurry, and process the metakaolin slurry with a shearing machine to obtain slurry metakaolin; (3) Mixing inorganic acid with slurry metakaolin to obtain a mixture with pH < 1.5, and after filtering and washing the mixture, obtaining acid-treated metakaolin; (4) Mix the silicon source, modified metal salt solution, nonionic surfactant, biomass-based microcrystalline hydrophobic material and oil, and then mix with acid-treated metakaolin, controlling the pH to 7.5-8 to obtain a modified mixture; wherein the mass ratio of silicon source, modified metal salt, nonionic surfactant, biomass-based microcrystalline hydrophobic material, oil and metakaolin is 1:0-12:0.1-3:0.4-10:0.1-5:10-80; the mass concentration of metal salt in the modified metal salt solution is 5-30 wt%; (5) The modified mixture is filtered, washed, dried and calcined to obtain modified kaolin.

6. The method for preparing modified kaolin according to claim 5, characterized in that, The silicon source is selected from one or more of tetraethyl orthosilicate, tetramethylsilicon, silica aerogel, and silicon tetrachloride; the modified metal salt is selected from one or more of chloride, nitrate, sulfate, and phosphate salts of IA, IIA, IVB, and lanthanide metals; the nonionic surfactant is selected from one or more of polyethylene glycol, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, coconut oil fatty acid ethanolamide, alkyl polyglucoside, polyethylene glycol distearate, and sucrose monostearate; the biomass-based microcrystalline hydrophobic material is selected from one or more of microcrystalline cellulose, lignin, and hemicellulose; and the oil is selected from one or more of naphtha, lubricating oil, jet fuel, kerosene, diesel oil, peanut oil, perilla oil, and tea tree oil.

7. The method for preparing modified kaolin according to claim 6, characterized in that, The silicon source is selected from one or more of tetramethylsiloxane, tetramethylsiloxane, and silica aerogel; the modified metal salt solution is selected from aqueous solutions of chloride, nitrate, and sulfate salts of IA, IIA, IVB, and lanthanide metals; the nonionic surfactant is selected from one or more of polyethylene glycol, fatty alcohol polyoxyethylene ether, and polyethylene glycol distearate; the biomass-based microcrystalline hydrophobic material is selected from microcrystalline cellulose and / or lignin; and the oil is selected from one or more of naphtha, lubricating oil, and diesel oil.

8. The method for preparing modified kaolin according to claim 5, characterized in that, In step (1), the kaolin is roasted at a temperature of 600-900℃ and for 2-6 hours. In step (2), the mass ratio of metakaolin to water is 0.01-0.5:1; the particle size of the slurry metakaolin obtained by shearing is 5nm-20μm; In step (3), the inorganic acid and metakaolin are mixed evenly under stirring to make the pH of the solid-liquid mixture reach 0-1. After maintaining this for 1-3 hours, the metakaolin is filtered and washed until neutral to obtain acid-treated metakaolin. In step (4), the mass ratio of silicon source, modified metal salt, nonionic surfactant, biomass-based microcrystalline hydrophobic material, oil, and metakaolin is 1:0-6:0.1-2.5:0.5-8:0.3-3:20-50; the mixing temperature is 40-80℃, and a stirrer is used for mixing at a speed of 50-1000 rpm; the mixing time is 0.5-10h. In step (5), the drying temperature of the modified mixture is 80-150℃, the calcination temperature is 400-1000℃, and the calcination time is 1-10h.

9. The method for preparing modified kaolin according to claim 8, characterized in that, In step (2), the mass ratio of metakaolin to water is 0.1-0.35:1; the particle size of the slurry metakaolin obtained by shearing is 10nm-15μm; In step (4), the temperature during the mixing of silicon source, modified metal salt solution, nonionic surfactant, biomass-based microcrystalline hydrophobic material and oil is 50-70℃, the stirring speed is 300-1000rpm, and the stirring time is 1-3h.

10. The use of the modified kaolin according to any one of claims 1-4 in catalysts, fillers, ceramics, coatings, pharmaceuticals and textiles.

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