High-silica alumina gel and method for producing the same

Abstract

This invention relates to the field of silicon-aluminum materials and discloses a method for preparing silicon-aluminum adhesive. The method includes the following steps: subjecting a mixed system containing silicon-containing filtrate, an aluminum source, and an inorganic acid to an aging reaction and solid-liquid separation to obtain a high silicon-to-aluminum ratio silicon-aluminum adhesive; the pH value of the mixed system is 5-10. This method is simple, the silicon-to-aluminum ratio is easy to adjust, it is suitable for industrial-scale production, and it can prepare silicon-aluminum adhesive with a high silicon-to-aluminum ratio and low impurity content, with a silicon-to-aluminum ratio (SiO2 / Al2O3) reaching above 15.

Description

Technical Field

[0001] This invention relates to the field of silica-alumina adhesive preparation, specifically to a high silica-alumina ratio silica-alumina adhesive and its preparation method. Background Technology

[0002] Aluminosilicate silica gel is a type of silica gel containing alumina. Its chemical formula consists of silicon oxide, aluminum oxide, and water. It is chemically stable and is mainly used as a catalyst and catalyst carrier in the petrochemical industry. Industrially, it is also used as a desiccant, liquid adsorbent, and gas separator.

[0003] There are three main conventional methods for preparing aluminosilicate gel: 1) Sol-gel method with aluminum salt, which cannot form a uniform solution, thus affecting the uniformity of the product; 2) Template agent method, which is expensive and difficult to process; 3) Carbonization method, which uses aluminum salt and silicon-containing compounds to react with carbon dioxide to form a gel. The aluminosilicate gel obtained by this method has a small pore size and needs to be enlarged, which limits its application.

[0004] CN102050469A discloses a method for preparing silica-alumina gel from molecular sieve crystallization mother liquor. The prepared silica-alumina gel is used in the preparation process of NaY molecular sieve as a directing agent. The main problem is that it only involves using the prepared silica-alumina gel in the synthesis of NaY molecular sieve, and there is still a continuous generation of silica-containing mother liquor in the subsequent process, which still presents a large amount of wastewater treatment problem.

[0005] CN108046280A discloses a silica-alumina gel and its preparation method. This method uses sodium silicate, aluminum salts, and raw material acid, followed by sol-gelation, aging, acid exchange treatment, washing, ammonia treatment, and drying to obtain the silica-alumina gel product. The product exhibits a large specific surface area and pore volume, stable quality, high compressive strength, and uniform strength. The main problems are: the preparation process is relatively complex, involving acid exchange treatment and subsequent ammonia treatment, which increases the difficulty of controlling the silica-alumina gel structure and generates a large amount of wastewater, increasing wastewater treatment costs. The acid exchange treatment and subsequent ammonia treatment also have long processing times, increasing energy consumption costs and the preparation cycle of the silica-alumina gel, thus hindering its industrial application.

[0006] CN112340742A discloses a macroporous high-purity silica-alumina adhesive and its preparation method. The method uses aluminum hydrochloric acid solution and prepared sodium silicate as raw materials. The macroporous high-purity silica-alumina adhesive has the characteristics of large pore volume, large specific surface area, high content of coordinated aluminum and bonded aluminum, low content of metal ion impurities, high purity, and wide range of silica-alumina ratio adjustment. However, the method requires eleven production steps to obtain the silica-alumina adhesive product. The process is long, the production efficiency is low, and it is difficult to realize industrial promotion.

[0007] CN113184860A discloses a method for preparing aluminosilicate silica gel. This method uses tetraethyl orthosilicate as the silicon source and aluminum nitrate as the aluminum source. By adjusting the pH value to 4-11 with the addition of acid and alkali, aluminosilicate silica gel with different pore structures is produced. The gel is then subjected to a series of steps, including gelation for 1-4 hours, distillation at 90-100℃ for 0.5-3 hours, distillation at 100-120℃ for 0.5-1 hours, drying for 10-12 hours, and calcination for 1-4 hours, to finally obtain the finished aluminosilicate silica gel. This method has low production efficiency and high energy consumption.

[0008] CN106587085A discloses a method for preparing macroporous aluminosilicate silica gel. The method uses boehmite and silica sol as raw materials, adds acid to control the pH value at 3-5 and keeps it at a certain temperature, then adds alkali to adjust the pH value of the slurry to 9-10 to obtain aluminosilicate silica gel, and then dries it to obtain macroporous aluminosilicate silica gel. The reaction process of this method is limited by the uniformity of stirring, the pulping of the boehmite raw material, and the uniformity of pH value. The reaction process cannot obtain a uniform aluminosilicate silica gel, the content of silicon-oxygen-aluminum chemical coordination bonds is low, and the obtained macroporous aluminosilicate silica gel has low strength, which limits its application fields.

[0009] Literature (Zou Lingfeng. Technical discussion on the preparation of silica-alumina gel from NaY crystallization mother liquor [J]. Industrial Catalysis, 2002(06):56-60.) and literature (Wang Juan, Yang Ling. Discussion on the preparation of silica-alumina gel from NaY molecular sieve mother liquor [J]. Shandong Chemical Industry, 2018, 47(10):20-22.) report the preparation of silica-alumina gel using NaY molecular sieve crystallization mother liquor and aluminum sulfate. This is beneficial to improving the usability of silica-containing filtrate and avoiding the pollution of the environment caused by the direct discharge of silica-containing filtrate. It also reduces the production cost. However, the problem that exists in all of them is that the silica-alumina ratio of the prepared silica-alumina gel is generally between 6 and 9, which is too low and will limit its application in other aspects.

[0010] Therefore, a method for preparing aluminosilicate gel with a higher silicon-to-aluminum ratio is needed. Summary of the Invention

[0011] The purpose of this invention is to overcome the problems of complex preparation process and low silicon-aluminum ratio of the high silicon-aluminum ratio silica-aluminum adhesive in the prior art. This invention provides a high silicon-aluminum ratio silica-aluminum adhesive and its preparation method. The method has simple steps, the silicon-aluminum ratio is easy to adjust, it is suitable for industrial scale-up production, and it can prepare silica-aluminum adhesive with high silicon-aluminum ratio and low impurity content. The silicon-aluminum ratio SiO2 / Al2O3 can reach more than 15.

[0012] To achieve the above objectives, the first aspect of the present invention provides a method for preparing aluminosilicate adhesive, wherein the method includes the following steps: A mixed system containing silicon-containing filtrate, aluminum source and inorganic acid is subjected to aging reaction and solid-liquid separation to obtain high silicon-aluminum ratio silica-alumina gel. The pH value of the mixture is 5-10.

[0013] Preferably, the pH value of the mixture is 5.5-9.

[0014] Preferably, the silica content in the silica-containing filtrate is ≥15g / L, and more preferably 30-100g / L.

[0015] Preferably, the sodium oxide content in the silicon-containing filtrate is 0-50 g / L, and more preferably 10-25 g / L.

[0016] Preferably, the pH value of the silica-containing filtrate is 10-14, more preferably 11.5-12.5.

[0017] Preferably, the silicon-containing filtrate is a molecular sieve silicon-containing filtrate.

[0018] Preferably, the molecular sieve in the silica-containing filtrate is selected from at least one of L-type molecular sieve, X-type molecular sieve, Y-type molecular sieve and ZSM-5 molecular sieve.

[0019] Preferably, the aluminum source is an aluminum source solution and / or an acidic aluminum gel.

[0020] Preferably, the aluminum source solution is selected from at least one of aluminum sulfate solution, aluminum chloride solution, and aluminum nitrate solution.

[0021] Preferably, the concentration of the aluminum source solution, based on alumina, is 8-150 g / L, and more preferably 30-100 g / L.

[0022] Preferably, the volume ratio of the aluminum source to the inorganic acid is 1:0.5-2, and more preferably 1:1-1.5.

[0023] Preferably, the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0024] Preferably, the aging reaction conditions include: an aging temperature of 30-90℃, more preferably 50-70℃; and an aging time of 20-120 min, more preferably 40-60 min.

[0025] Preferably, the method further includes washing and drying the solid product obtained from solid-liquid separation.

[0026] Preferably, the washing conditions include a washing temperature of 20-70℃, more preferably 25-60℃.

[0027] Preferably, the drying conditions include a drying temperature of 110-170℃, more preferably 120-160℃.

[0028] The second aspect of the present invention provides a silica-alumina adhesive prepared by the preparation method described in the first aspect.

[0029] Preferably, based on the total weight of the silica-alumina gel, the SiO2 content is 80-95 wt%, preferably 82-90 wt%, the Al2O3 content is 2-10 wt%, preferably 3-10 wt%, the Na2O content is 2-10 wt%, preferably 3-7 wt%, and the impurity content is 0-2.5 wt%, preferably 0-1 wt%.

[0030] Preferably, the specific surface area of ​​the silica-alumina adhesive is 300-600 m² / g. 2 / g, preferably 350-550m 2 / g.

[0031] Preferably, the bulk density of the silica-alumina adhesive is 0.2-0.6, and more preferably 0.3-0.5.

[0032] Preferably, the pore volume of the silica-alumina paste is 0.5-1 cm. 3 / g, preferably 0.6-0.9cm 3 / g.

[0033] Preferably, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the silica-alumina adhesive is 10-60, and more preferably 15-50.

[0034] The beneficial effects achieved through the above technical solution are as follows: The method for preparing silica-alumina adhesive provided by this invention is simple, the silica-alumina ratio is easy to adjust, it is suitable for industrial scale-up production, and it can prepare silica-alumina adhesive with a high silica-alumina ratio and low impurity content, with the silica-alumina ratio reaching more than 15. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the apparatus for preparing the high silica-alumina ratio silica-alumina adhesive of the present invention.

[0036] Explanation of reference numerals in the attached figures Detailed Implementation

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0038] The first aspect of this invention provides a method for preparing aluminosilicate adhesive, wherein the method includes the following steps: A mixed system containing silicon-containing filtrate, aluminum source and inorganic acid is aged and separated into solid and liquid components to obtain a high silicon-to-aluminum ratio silica-alumina gel. The pH value of the mixture is 5-10.

[0039] The preparation method provided in this invention is simple and easy to operate. The silicon-aluminum ratio is easy to adjust and suitable for industrial scale-up production. It can prepare silicon-aluminum gel with a high silicon-aluminum ratio and low impurity content. The silicon-aluminum ratio SiO2 / Al2O3 can reach more than 15.

[0040] According to the present invention, preferably, the pH value of the mixed system is 5-10, for example 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 10, or any range between the two, preferably 5.5-9. In the present invention, controlling the pH value of the mixed system can ensure that the mixed system forms a colloidal system.

[0041] According to the present invention, preferably, the silica content in the silica-containing filtrate is ≥15g / L, for example, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, 55g / L, 60g / L, 65g / L, 70g / L, 75g / L, 80g / L, 85g / L, 90g / L, 95g / L, 100g / L, or any range between the two, preferably 30-100g / L.

[0042] According to the present invention, preferably, the sodium oxide content in the silica-containing filtrate is 0-50 g / L, more preferably 10-25 g / L. In the present invention, the composition of the silica-containing filtrate satisfies the above-mentioned limitations, and can provide an appropriate amount of silica to generate a silica-alumina gel with a high silica-to-alumina ratio and low impurity content.

[0043] According to the present invention, preferably, the pH value of the silica-containing filtrate is 10-14, more preferably 11.5-12.5.

[0044] According to the present invention, the type of silicon-containing filtrate is not particularly limited, and any filtrate from which a silicon source can be provided in the art is acceptable. Preferably, the silicon-containing filtrate is a molecular sieve silicon-containing filtrate. In the present invention, the molecular sieve silicon-containing filtrate has the conventional interpretation in the art, referring to the molecular sieve silicon-containing filtrate obtained by solid-liquid separation after the crystallization reaction in the molecular sieve preparation process. By using molecular sieve silicon-containing filtrate, the recycling of the silicon-containing filtrate derived in the molecular sieve preparation process is realized, saving resources and reducing costs.

[0045] In this invention, preferably, the suspended solids content in the silica-containing filtrate is 0-5000 mg / L, more preferably 0-500 mg / L. The suspended solids are molecular sieve particles.

[0046] According to the present invention, the type of molecular sieve in the silica-containing filtrate is not particularly limited, and is a conventional molecular sieve in the art. Preferably, the molecular sieve in the silica-containing filtrate is selected from at least one of L-type molecular sieves, X-type molecular sieves, Y-type molecular sieves, and ZSM-5 molecular sieves. In this invention, the silica-containing filtrate generated during the conventional molecular sieve production process is used, enabling comprehensive utilization of raw materials in the molecular sieve preparation process. The raw material sources are wide-ranging, which is conducive to the green development of the molecular sieve synthesis field.

[0047] According to the present invention, the type and source of the aluminum source are not particularly limited, as long as alumina can be provided. Preferably, the aluminum source is an aluminum source solution and / or acidic aluminum gel.

[0048] According to the present invention, preferably, the aluminum source solution is selected from at least one of aluminum sulfate solution, aluminum chloride solution, and aluminum nitrate solution.

[0049] According to the present invention, preferably, the concentration of the aluminum source solution, calculated as alumina, is 8-150 g / L, for example, 8 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, or any range between the two, preferably 30-100 g / L.

[0050] According to the present invention, preferably, the amount of aluminum source solution is not particularly limited. Depending on the silicon-to-aluminum ratio of the target silica-alumina gel, the silica content in the silica-containing filtrate, the amount of silica-containing filtrate, and the concentration of alumina in the aluminum source solution, those skilled in the art can adaptively adjust the amount of aluminum source solution.

[0051] In this invention, the source of the acidic aluminum gel is not particularly limited; it can be commercially available or prepared using existing methods. The content of aluminum oxide in the acidic aluminum gel is 8-150 g / L, preferably 30-100 g / L.

[0052] According to the present invention, the type of inorganic acid is not particularly limited, and it is a conventional inorganic acid in the art. Preferably, the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid. The form of addition of the inorganic acid is not particularly limited; it can be added directly or in the form of an inorganic acid solution. The mass concentration of the inorganic acid solution is not particularly limited.

[0053] According to the present invention, preferably, the volume ratio of the aluminum source to the inorganic acid is 1:0.5-2, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, or any range between the two, preferably 1:1-1.5. In the present invention, the volume ratio of the aluminum source to the inorganic acid is not particularly limited; controlling the amount of inorganic acid added to adjust the pH value of the mixing system to meet the limited range can improve the silicon-to-aluminum ratio of the obtained silica-alumina gel.

[0054] According to a preferred embodiment of the present invention, the mixed system containing silicon-containing filtrate, aluminum source, and inorganic acid is obtained by mixing the silicon-containing filtrate, aluminum source, and inorganic acid. The mixing method is not particularly limited; simply mixing the silicon-containing filtrate, aluminum source, and inorganic acid until they are homogeneous is sufficient.

[0055] According to the present invention, preferably, the conditions for the aging reaction include: an aging temperature of 30-90°C, for example 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any range between the two, preferably 50-70°C; and an aging time of 20-120 min, for example 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, or any range between the two, preferably 40-60 min.

[0056] In this invention, the aging reaction conditions are easy to control, and the aging reaction can be completed in a short time, resulting in high production efficiency. If the aging time is too long, the final silicone-aluminum adhesive will have a high impurity content and a small specific surface area.

[0057] In this invention, the equipment for the aging reaction is not particularly limited, and those skilled in the art can choose conventional aging reaction equipment. According to a preferred embodiment of the invention, the aging reaction is carried out in a reaction vessel. A mixed system containing silicon-containing filtrate, an aluminum source, and an inorganic acid enters the reaction vessel, remains for a certain period of time for aging, and then is discharged from the reaction vessel. The residence time corresponds to the aging reaction time.

[0058] In this invention, preferably, after the aging reaction is completed, the aging product is subjected to solid-liquid separation. The method of solid-liquid separation is not particularly limited, and those skilled in the art can choose conventional solid-liquid separation methods, preferably filtration.

[0059] According to the present invention, preferably, the method further includes washing and drying the solid product obtained from solid-liquid separation.

[0060] According to the present invention, the washing conditions are not particularly limited and are conventional washing methods in the art, preferably using deionized water. Preferably, the washing conditions include a washing temperature of 20-70°C, more preferably 25-60°C. According to a preferred embodiment of the present invention, tertiary water is used for washing. The mass ratio of the washing water to the aging product is 1-1.5:1.

[0061] According to the present invention, the drying is carried out under conventional drying conditions in the art. According to a preferred embodiment of the present invention, flash drying of the washing product is used to obtain aluminosilicate powder. Preferably, the drying conditions include a drying temperature of 110-170°C, more preferably 120-160°C.

[0062] In this invention, preferably, in Figure 1 The apparatus shown is used to prepare a silica-alumina gel. A silica-containing filtrate is introduced into a mixer 1 through a silica-containing filtrate inlet 2, an inorganic acid is introduced into a mixer 1 through an inorganic acid inlet 3, and an aluminum source is introduced into a mixer 1 through an aluminum source inlet 4. After being mixed evenly, the mixture enters a reaction vessel 5, where an aging reaction is carried out to obtain a silica-alumina gel with a high silica-alumina ratio.

[0063] The second aspect of the present invention provides a silica-alumina adhesive prepared by the preparation method described in the first aspect.

[0064] In this invention, the silica-alumina gel prepared by the above method has a controllable silica-alumina ratio, enabling the preparation of silica-alumina gels with high specific surface area, large pore volume, and high silica-alumina ratio. It can be widely used in fields such as catalysts and catalyst supports, adsorption separation, and molecular sieve preparation.

[0065] In this invention, the silica-alumina adhesive comprises aluminum oxide, silicon dioxide, sodium oxide, and impurities, wherein the impurities include compounds containing at least one of sulfate, nitrate, and chloride ions.

[0066] According to the present invention, preferably, based on the total weight of the silica-alumina gel, the content of SiO2 is 80-95wt%, 82-90wt%, the content of Al2O3 is 2-10wt%, preferably 3-10wt%, the content of Na2O is 2-10wt%, preferably 3-7wt%, and the content of impurities is 0-2.5wt%, preferably 0-1wt%.

[0067] In this invention, the chemical composition of the silica-alumina gel is obtained by semi-quantitative analysis using X-ray fluorescence spectrometry.

[0068] According to the present invention, preferably, the specific surface area of ​​the silica-alumina adhesive is 300-600 m². 2 / g, for example 300m 2 / g, 350m 2 / g、400m2 / g、450m 2 / g、500m 2 / g、550m 2 / g、600m 2 / g, or any range between the two, preferably 350-550m 2 / g. In this invention, the specific surface area and pore volume of the silica-alumina gel refer to the specific surface area and pore volume of the silica-alumina gel dry powder, which are measured by low-temperature nitrogen adsorption method.

[0069] According to the present invention, preferably, the pore volume of the aluminosilicate is 0.5-1 cm. 3 / g, for example, 0.5cm 3 / g, 0.55cm 3 / g, 0.6cm 3 / g, 0.65cm 3 / g, 0.7cm 3 / g, 0.75cm 3 / g, 0.8cm 3 / g, 0.85cm 3 / g, 0.9cm 3 / g, 1cm 3 / g, or any range between the two, preferably 0.6-0.9cm 3 / g.

[0070] According to the present invention, preferably, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the silica-alumina adhesive is 10-60, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or any range between the two, preferably 15-50. This is calculated based on the silicon dioxide and aluminum oxide content in the silica-alumina adhesive.

[0071] According to the present invention, the bulk ratio of the aluminosilicate adhesive refers to the weight of a unit volume of aluminosilicate adhesive dry powder material. The bulk ratio of the aluminosilicate adhesive is 0.2-0.6, for example, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, or any range between the two, preferably 0.3-0.5. In the present invention, the method for measuring the bulk ratio includes: filling a 500mL standard graduated cylinder with aluminosilicate adhesive dry powder, measuring the weight, and then subtracting the weight of the standard graduated cylinder to obtain the weight of the aluminosilicate adhesive dry powder, with the weight expressed in grams. The value of the weight of a unit volume of aluminosilicate adhesive dry powder material is the bulk ratio.

[0072] According to a particularly preferred embodiment of the present invention, a method for preparing aluminosilicate adhesive includes the following steps: A mixed system containing silicon-containing filtrate, aluminum source and inorganic acid is subjected to aging reaction and solid-liquid separation to obtain high silicon-aluminum ratio silica-alumina gel. The pH value of the mixture is 5.5-9; The silica content in the silica-containing filtrate is 30-100 g / L; The volume ratio of the aluminum source to the inorganic acid is 1:1-1.5; The conditions for the aging reaction include: an aging temperature of 50-70℃ and an aging time of 40-60 min.

[0073] The present invention will be described in detail below through examples and comparative examples. Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available. In this invention, the pH value is the pH value at 28-32℃.

[0074] Example 1 exist Figure 1 The apparatus shown is used to prepare a silica-alumina gel. Silica-containing filtrate is introduced into mixer 1 through silica-containing filtrate inlet 2, inorganic acid is introduced into mixer 1 through inorganic acid inlet 3, and aluminum source is introduced into mixer 1 through aluminum source inlet 4.

[0075] The silica-containing filtrate is a silica-containing filtrate produced by X-type molecular sieve. The silica content in the filtrate is 25 g / L, the sodium oxide content is 12.5 g / L, the pH value is 12.6, and the suspended solids are from X-type molecular sieve with a suspended solids content of 100 mg / L. The addition volume of the silica-containing filtrate is 2 mg / L. 3 / h, with a stay time of 20min.

[0076] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 60 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 15.

[0077] Aluminum sulfate solution and concentrated sulfuric acid were added at a volume ratio of 1:0.5. The pH of the mixture was controlled at 8.3-8.4. The mixture was then subjected to an aging reaction in reactor 5 at 45°C for 20 minutes. The solid product obtained by filtration was washed at 30°C, with the washing feed rate controlled at 5-5.5 ml. 3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0078] Example 2 exist Figure 1 The apparatus shown is used to prepare a silica-alumina gel. Silica-containing filtrate is introduced into mixer 1 through silica-containing filtrate inlet 2, inorganic acid is introduced into mixer 1 through inorganic acid inlet 3, and aluminum source is introduced into mixer 1 through aluminum source inlet 4. The silica-containing filtrate is an L-type molecular sieve filtrate, with a silica content of 30 g / L, a sodium oxide content of 16 g / L, and a pH of 12.2. The suspended solids are also L-type molecular sieves, with a suspended solids content of 150 mg / L. The amount of silica-containing filtrate added is 2 mg / L. 3 / h, stay time 45min.

[0079] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 70 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 20.

[0080] Aluminum sulfate solution and hydrochloric acid were added at a volume ratio of 1:0.5, and the pH of the mixture was controlled at 8.5-8.8. The mixture was then subjected to an aging reaction in reactor 5 at 60°C for 45 minutes. The solid product obtained by filtration was then washed at 30°C, with the washing feed rate controlled at 5-5.5 ml. 3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0081] Example 3 exist Figure 1 The apparatus shown is used to prepare a silica-alumina gel. Silica-containing filtrate is introduced into mixer 1 through silica-containing filtrate inlet 2, inorganic acid is introduced into mixer 1 through inorganic acid inlet 3, and aluminum source is introduced into mixer 1 through aluminum source inlet 4.

[0082] The silica-containing filtrate is a Y-type molecular sieve filtrate, with a silica content of 40 g / L, a sodium oxide content of 15 g / L, and a pH of 12. The suspended solids are Y-type molecular sieves with a suspended solids content of 200 mg / L. The amount of silica-containing filtrate added is 2 mg / L. 3 / h, with a stay time of 45min.

[0083] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 80 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 26.

[0084] Aluminum sulfate solution and concentrated sulfuric acid were added at a volume ratio of 1:1.5. The pH of the mixture was controlled at 7.7-8.2. The mixture was then subjected to an aging reaction in reactor 5 at 55°C for 45 minutes. The solid product obtained by filtration was washed at 30°C, with the washing feed rate controlled at 5-5.5 ml. 3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0085] Example 4 exist Figure 1The apparatus shown is used to prepare a silica-alumina gel. Silica-containing filtrate is introduced into mixer 1 through silica-containing filtrate inlet 2, inorganic acid is introduced into mixer 1 through inorganic acid inlet 3, and aluminum source is introduced into mixer 1 through aluminum source inlet 4.

[0086] The silica-containing filtrate is a Y-type molecular sieve filtrate, with a silica content of 33 g / L, a sodium oxide content of 16 g / L, and a pH of 12.6. The suspended solids are Y-type molecular sieves with a suspended solids content of 100 mg / L. The amount of silica-containing filtrate added is 2 mg / L. 3 / h, with a stay time of 60min.

[0087] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 90 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 30.

[0088] Aluminum sulfate solution and hydrochloric acid were added at a volume ratio of 1:1.2, and the pH of the mixture was controlled at 5.8-6.3. The resulting silica-alumina gel was then aged in reactor 5 at 75°C for 60 minutes. The solid product obtained by filtration was washed at 30°C, with the washing feed rate controlled at 5-5.5 ml. 3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0089] Example 5 exist Figure 1 The apparatus shown is used to prepare a silica-alumina gel. Silica-containing filtrate is introduced into mixer 1 through silica-containing filtrate inlet 2, inorganic acid is introduced into mixer 1 through inorganic acid inlet 3, and aluminum source is introduced into mixer 1 through aluminum source inlet 4.

[0090] The silica-containing filtrate is a ZSM-5 molecular sieve filtrate, with a silica content of 38 g / L, a sodium oxide content of 20 g / L, and a pH of 12.9. The suspended solids are also ZSM-5 molecular sieves, with a suspended solids content of 150 mg / L. The amount of silica-containing filtrate added is 2 mg / L. 3 / h, with a stay time of 70min.

[0091] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 100 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 45.

[0092] Aluminum sulfate solution and hydrochloric acid were added at a volume ratio of 1:1.5. The pH of the mixture was controlled at 5.8-6.3. The mixture was then subjected to an aging reaction in reactor 5 at 75°C for 70 minutes. The solid product obtained by filtration was washed at 30°C, with the washing feed rate controlled at 5-5.5 ml.3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0093] Example 6 exist Figure 1 In the apparatus shown, silica-alumina gel is prepared by introducing silica-containing filtrate into mixer 1 through silica-containing filtrate inlet 2, introducing inorganic acid into mixer 1 through inorganic acid inlet 3, and introducing aluminum source into mixer 1 through aluminum source inlet 4.

[0094] The silica-containing filtrate is a ZSM-5 molecular sieve filtrate, with a silica content of 45 g / L, a sodium oxide content of 20 g / L, and a pH of 12. The suspended solids are also ZSM-5 molecular sieves, with a suspended solids content of 250 mg / L. The amount of silica-containing filtrate added is 2 mg / L. 3 / h, with a stay time of 90min.

[0095] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 110 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 50.

[0096] Aluminum sulfate solution was added at a volume ratio of 1:2 to sulfuric acid. The pH of the mixture was controlled at 5.5-6. The mixture was then subjected to an aging reaction in reactor 5 at 75°C for 90 minutes. The solid product obtained by filtration was then washed at 30°C, with the washing feed rate controlled at 5-5.5 ml. 3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0097] Example 7 exist Figure 1 In the apparatus shown, silica-alumina gel is prepared by introducing silica-containing filtrate into mixer 1 through silica-containing filtrate inlet 2, introducing inorganic acid into mixer 1 through inorganic acid inlet 3, and introducing aluminum source into mixer 1 through aluminum source inlet 4. The silica-containing filtrate is a ZSM-type molecular sieve filtrate, with a silica content of 60 g / L, a sodium oxide content of 25 g / L, and a pH of 11.8. The suspended solids are also from the ZSM-type molecular sieve, with a suspended solids content of 300 mg / L. The addition volume of the silica-containing filtrate is 2 mg / L. 3 / h, with a stay time of 90min.

[0098] The aluminum source is an aluminum sulfate solution with an aluminum oxide content of 150 g / L. The amount of aluminum source added makes the silicon-aluminum ratio (SiO2 / Al2O3) of the target silica-alumina gel 55.

[0099] Aluminum sulfate solution and hydrochloric acid were added at a volume ratio of 1:2. The pH of the mixture was controlled at 5.5-6. The mixture was then subjected to an aging reaction in reactor 5 at 75°C for 90 minutes. The solid product obtained by filtration was washed at 30°C, with the washing feed rate controlled at 5-5.5 ml. 3 The mixture is processed by adding three stages of water washing, with the total water consumption being 1.5 times the feed amount. Finally, it is flash-dried at 140℃ to obtain silica-alumina gel powder.

[0100] Example 8 The silica-alumina adhesive was prepared according to the method of Example 2, except that the aging time was changed to 120 min, while other conditions were the same as in Example 2, and silica-alumina adhesive dry powder was obtained.

[0101] Example 9 The silica-alumina adhesive was prepared according to the method of Example 2, except that the aging time was changed to 10 min, while other conditions were the same as in Example 2, and silica-alumina adhesive dry powder was obtained.

[0102] Comparative Example 1 The silica-alumina gel was prepared according to the method of Example 1, except that the amount of inorganic acid added was changed so that the pH value of the mixed system was 10.5, and other conditions were the same as in Example 1, and silica-alumina gel dry powder was obtained.

[0103] Comparative Example 2 The silica-alumina gel was prepared according to the method of Example 1, except that the amount of inorganic acid added was changed so that the pH value of the mixed system was 4.5, and other conditions were the same as in Example 1, and silica-alumina gel dry powder was obtained.

[0104] The silica-aluminum adhesive dry powders prepared in the examples and comparative examples were subjected to semi-quantitative analysis using X-ray fluorescence spectrometry to obtain the chemical composition of the silica-aluminum adhesive, as shown in Table 1. In this invention, the content of each component of the silica-aluminum adhesive obtained by semi-quantitative analysis has a certain error, and the sum of the contents of each component may not equal 100wt%, with an error not exceeding ±0.5wt%.

[0105] The test results of specific surface area, pore volume, silicon-to-aluminum ratio and bulk density of the silica-alumina gel dry powder are shown in Table 2.

[0106] Table 1

[0107] Table 2

[0108] As can be seen from the results in Tables 1 and 2, the silica-alumina gel prepared by the preparation method provided by the present invention has a higher specific surface area and pore volume, less impurity content, and a higher silica-alumina ratio.

[0109] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a silica alumina gel, characterized by, The method includes the following steps: A mixed system containing silicon-containing filtrate, aluminum source and inorganic acid is subjected to aging reaction and solid-liquid separation to obtain high silicon-aluminum ratio silica-alumina gel. The pH value of the mixture is 5-10.

2. The method of claim 1, wherein, The pH value of the mixture is 5.5-9.

3. The method of claim 1 or 2, wherein, The silica content in the silica-containing filtrate is ≥15g / L, preferably 30-100g / L; Preferably, the sodium oxide content in the silica-containing filtrate is 0-50 g / L, more preferably 10-25 g / L; Preferably, the pH value of the silica-containing filtrate is 10-14, more preferably 11.5-12.

5.

4. The method of any of claims 1-3, wherein, The silicon-containing filtrate is a molecular sieve silicon-containing filtrate; Preferably, the molecular sieve in the silica-containing filtrate is selected from at least one of L-type molecular sieve, X-type molecular sieve, Y-type molecular sieve and ZSM-5 molecular sieve.

5. The method of any of claims 1-4, wherein, The aluminum source is an aluminum source solution and / or acidic aluminum gel; Preferably, the aluminum source solution is selected from at least one of aluminum sulfate solution, aluminum chloride solution, and aluminum nitrate solution; Preferably, the concentration of the aluminum source solution, based on alumina, is 8-150 g / L, and more preferably 30-100 g / L.

6. The method of any of claims 1-5, wherein, The volume ratio of the aluminum source to the inorganic acid is 1:0.5-2, preferably 1:1-1.5; Preferably, the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid, and nitric acid.

7. The method of any of claims 1-6, wherein, The conditions for the aging reaction include: an aging temperature of 30-90℃, preferably 50-70℃; and an aging time of 20-120 min, preferably 40-60 min.

8. The method of any of claims 1-7, wherein, The method further includes washing and drying the solid product obtained from solid-liquid separation; Preferably, the washing conditions include a washing temperature of 20-70℃, more preferably 25-60℃; Preferably, the drying conditions include a drying temperature of 110-170℃, more preferably 120-160℃.

9. The silica-alumina adhesive prepared by the preparation method according to any one of claims 1-8; Preferably, based on the total weight of the silica-alumina gel, the SiO2 content is 80-95 wt%, preferably 82-90 wt%, the Al2O3 content is 2-10 wt%, preferably 3-10 wt%, the Na2O content is 2-10 wt%, preferably 3-7 wt%, and the impurity content is 0-2.5 wt%, preferably 0-1 wt%.

10. The silica-alumina gel of claim 9 wherein, The specific surface area of the silica-alumina gel is between 300 and 600 m 2 / g, preferably between 350 and 550 m 2 / g; Preferably, the pore volume of the silica alumina gel is 0.5-1 cm 3 / g, preferably 0.6-0.9 cm 3 / g; Preferably, the bulk ratio of the silica-alumina adhesive is 0.2-0.6, more preferably 0.3-0.5; Preferably, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the silica-alumina adhesive is 10-60, and more preferably 15-50.

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