Continuous preparation device for silica sol

Abstract

The utility model relates to a silica sol continuous preparation device which comprises a water glass storage tank and a water glass metering pump which are connected in series and used for storing and conveying raw material water glass; the acid storage tank and the acid metering pump are connected in series and are used for storing and conveying inorganic acid; the first-stage reactor and the product collecting tank are communicated in sequence; and the water glass metering pump and the acid metering pump are respectively communicated with a raw material inlet of the primary reactor. The continuous preparation device for the silica sol is used for preparing the silica sol, the preparation process flow is short, and stable operation is easy. The reaction feeding rate can be accurately controlled, homogenizing mixing is rapid, the pH value stable interval is accurately controlled, and silica sol colloid condensation is avoided. The prepared silica sol is good in stability and high in cohesiveness, and meets the use requirements of a low green coke cracking catalyst binder.

Description

Technical Field

[0001] The utility model relates to a silica sol continuous preparation device, more specifically, a preparation device which uses low-cost raw materials such as water glass and acid to continuously prepare high-stability silica sol through an acid-base neutralization method. Background Art

[0002] Silica sol, also known as silicic acid sol or silica hydrosol, is a widely used inorganic silicon material. As an excellent inorganic silicon fine chemical product, it is widely used in industries such as chemicals, precision casting, textiles, papermaking, materials, coatings, and electronics. Currently, global demand for silica sol is approximately 3.5 million tons / year, primarily concentrated in developed countries such as Europe and the United States. Domestic market demand is also gradually expanding, with domestic silica sol consumption exceeding 600,000 tons / year in 2021.

[0003] As of 2021, there are approximately 40 silica sol manufacturers in China. Ten of these companies have a production capacity exceeding 20,000 tons / year, bringing their combined production capacity to 540,000 tons / year and their total output to approximately 400,000 tons / year. Most Chinese silica sol manufacturers primarily produce low-end, standard silica sols, primarily for use in industries such as precision casting, refractories, inorganic coatings, papermaking, and the chemical industry.

[0004] Catalytic cracking is one of my country's most important secondary petroleum processing technologies, and the regeneration of cracking catalysts is a major source of carbon emissions from the refining process. In traditional aluminum-based cracking catalysts using activated alumina as a binder, the alumina carrier, while improving the catalyst's strength and pore volume, also creates acidic sites susceptible to hydrogen transfer reactions, promoting coking. Silicon-based cracking catalysts using silica sol as a binder, on the other hand, have lower hydrogen transfer activity, which can reduce coke yields and olefin saturation, improving product distribution while also helping to lower carbon emissions from catalytic cracking units. However, the relatively high price and relatively poor stability of silica sol have hampered its application in cracking catalysts. Therefore, there is a significant market demand for a low-cost, simple-to-use silica sol preparation technology that can enhance the stability of the catalyst production process.

[0005] Existing research on silica sol preparation technologies focuses primarily on ion exchange and elemental silica powder dissolution. The ion exchange method suffers from limitations in that the concentration of the starting material, water glass, cannot be very high, resulting in a long and energy-intensive concentration process. Furthermore, the regeneration of the ion exchange resin generates a large amount of wastewater that requires treatment. The elemental silica powder sol method also suffers from the fact that the silica sol produced using this method typically has particle sizes ranging from 10 to 20 nm, with unclear interparticle interfaces and uncontrollable non-spherical morphology. Consequently, it is generally used in industries such as foundry, and is less commonly used in more demanding applications such as precision polishing and catalysis. Direct acid-base synthesis methods, due to their extremely demanding preparation conditions, have received limited research, with no reports of industrial applications. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a silica gel continuous preparation device, which is used for continuously preparing silica sol by acid-base neutralization method using low-cost raw materials.

[0007] A silica sol continuous preparation device, comprising:

[0008] The water glass storage tank and water glass metering pump connected in series are used to store and transport raw water glass;

[0009] Acid storage tanks and acid metering pumps connected in series are used to store and transport inorganic acids;

[0010] The primary reactor and the product collecting tank are sequentially connected; the water glass metering pump and the acid metering pump are respectively connected to the raw material inlet of the primary reactor.

[0011] Preferably, a secondary reactor is also provided, which is an overflow stirred reactor with a raw material inlet at the bottom, an overflow port at the top, and a stirring paddle inside; wherein the primary reactor, the secondary reactor and the product collection tank are connected in sequence.

[0012] The beneficial effects of the silica sol continuous preparation device provided by the utility model are:

[0013] The silica sol continuous preparation device provided by the utility model is used for preparing silica sol by reacting water glass and acid. It can accurately control the reaction feed rate, quickly and evenly mix the reactants, and the pH value fluctuates little during the silica sol preparation process, and colloid coagulation is not easy to occur. The preparation process is short and easy to operate stably. The prepared silica sol has good stability and high adhesion, meeting the requirements for use as a binder for low-coking cracking catalysts. Compared with the silica sol preparation method of the prior art, the continuous preparation device provided by the utility model is used for silica sol preparation, and the production cost of silica sol can be reduced by more than 50%; it overcomes the shortcomings of the ion exchange method for preparing silica sol, such as the low concentration of the water glass starting raw material of the ion exchange method, the long time and high energy consumption of the subsequent concentration process, and the large amount of wastewater generated when the ion exchange resin is regenerated and needs to be treated. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to illustrate and understand the present invention, but the present invention is not limited thereby.

[0015] Figure 1 This is a schematic structural diagram of a preferred embodiment of a silica sol continuous preparation device.

[0016] in:

[0017] 1- Sodium silicate storage tank 2- Acid storage tank 3- Sodium silicate metering pump

[0018] 4-Acid metering pump 5-First pressure stabilizer 6-Second pressure stabilizer

[0019] 7- Primary Reactor 8- Dispersant Storage Tank 9- Flow Controller

[0020] 10-Secondary Reactor 11-Product Collection Tank DETAILED DESCRIPTION

[0021] The specific implementation of the present utility model is described in detail below.

[0022] In this application, the terms "upper," "lower," and "bottom" are used relative to the container or component. The "bottom" refers to the 0% to 10% position of the container from the bottom to the top, the "upper" refers to the 50% to 100% position of the container from the bottom to the top, and the "top" refers to the 90% to 100% position of the container from the bottom to the top.

[0023] A continuous preparation device for silica sol comprises: a water glass storage tank and a water glass metering pump connected in series, for storing and conveying raw water glass; an acid storage tank and an acid metering pump connected in series, for storing and conveying inorganic acid; a primary reactor and a product collection tank connected in sequence; the water glass metering pump and the acid metering pump are respectively connected to the raw material inlet of the primary reactor.

[0024] Preferably, a secondary reactor is further provided. The overflow stirred reactor is provided with a raw material inlet at the bottom, an overflow port at the top, and a stirring paddle inside; wherein the primary reactor, the secondary reactor and the product collection tank are connected in sequence.

[0025] Optionally, the method further comprises a dispersant storage tank and a flow controller connected in series therewith, wherein the flow controller is connected to the secondary reactor.

[0026] Preferably, a first pressure stabilizer is provided on the pipeline connecting the water glass metering pump and the primary reactor; and a second pressure stabilizer is provided on the pipeline connecting the acid metering pump and the primary reactor.

[0027] Preferably, in the present invention, the pressure stabilizer is a tank body equipped with a pressure stabilization system. During use of the silica sol continuous preparation device provided by the present invention, the pressure control range of the pressure stabilizer is 0.3-1.0 MPa. Preferably, the primary reactor is a powerful dispersing mixer equipped with a set of mutually interlocking stirring teeth. Preferably, the volume of the primary reactor is 5-20 L. During use of the silica sol continuous preparation device provided by the present invention, the rotation speed of the stirring teeth is 500-4500 rpm, and the processing capacity of the primary reactor is 50-450 kg / h.

[0028] Preferably, the inner wall of the secondary reactor is provided with a plurality of deflection baffles.

[0029] In a specific embodiment, the volume of the secondary reactor is 25-40 L; a plurality of baffles are staggeredly arranged on the inner wall of the secondary reactor to promote further mixing of materials in the secondary reactor.

[0030] Optionally, the water glass metering pump is a reciprocating plunger pump, a diaphragm pump or a hose pump, preferably a reciprocating plunger pump; the acid metering pump is selected from a reciprocating plunger pump, a diaphragm pump or a hose pump, preferably a reciprocating plunger pump.

[0031] Preferably, the inner wall of the water glass storage tank is made of M304 stainless steel, and the inner wall of the acid storage tank is made of PVC, organic glass or steel with an acid corrosion-resistant coating. The volume ratio of the water glass storage tank to the acid storage tank is 1.5-4:1.

[0032] In a preferred embodiment, a flow controller is provided on the pipeline between the dispersant storage tank and the secondary reactor, and the flow controller is preferably a hose pump.

[0033] The following uses the acid-base neutralization method for preparing silica sol as an example to illustrate the application of the continuous silica sol preparation device provided by the present invention. The raw material, water glass, is metered into a primary reactor via a water glass metering pump. Dilute sulfuric acid is then metered into the primary reactor via an acid metering pump. The water glass and dilute sulfuric acid are rapidly homogenized, and an acid-base neutralization reaction occurs. The reacted materials enter a secondary reactor, where they continue mixing and reacting. The completed silica sol enters and is stored in a product collection tank.

[0034] In a preferred embodiment, a dispersant storage tank and a flow controller connected in series are also provided. The reacted material in the primary reactor enters the secondary reactor, where a metered amount of dispersant is added for continued mixing and reaction. This significantly improves the stability of the prepared silica sol. The dispersant is any one or more of citric acid, ammonium citrate, polyacrylamide, ammonium polymethacrylate, sodium lauryl sulfate, and cetyltrimethylammonium bromide. The amount of dispersant added is 0.05%-1.5%, preferably 0.1%-0.5%, based on the dry weight of the silica sol.

[0035] The feed rates of the liquid raw materials, sodium silicate and dilute acid, are precisely controlled using sodium silicate and acid metering pumps. The acid solution flow rate error can be controlled within 0.5%, and the pH fluctuation range is controlled to within 0.05-0.15. This prevents colloid coagulation caused by large pH fluctuations. Specifically, the pH of the reaction materials after mixing in the primary reactor is controlled within the range of 0.2-2.8, preferably 0.5-2.0.

[0036] In a preferred embodiment, a first pressure stabilizer is installed on the pipeline connecting the water glass metering pump and the primary reactor; a second pressure stabilizer is installed on the pipeline connecting the acid metering pump and the primary reactor. The pressure stabilizer comprises an outlet on the tank body and a pressure gauge mounted thereon, and the outlet and pressure gauge are linked to control pressure stability. During the silica sol preparation process, the pressure stabilizer can maintain a certain liquid material outlet pressure, reducing liquid material flow rate fluctuations and further improving the control accuracy of liquid material feed. The pressure range for liquid material feed flow control is 0.2-0.8 MPa, preferably 0.3-0.5 MPa.

[0037] In a preferred embodiment, the primary reactor uses a powerful dispersing mixer equipped with a set of interlocking high-speed stirring teeth. The stirring teeth rotate at a speed of 1500-3000 rpm, and the processing capacity of the primary reactor is 150-350 kg / hour. The high-density energy input to the high-speed rotating stirring teeth achieves rapid and uniform mixing of the materials. During application, the residence time of the reaction material in the primary reactor is 0.5-10 seconds, preferably 1-3 seconds.

[0038] In a preferred embodiment, the secondary reactor is an overflow stirred reactor equipped with a stirring paddle to thoroughly and evenly mix the material passing through the primary reactor with the dispersant, thereby improving the stability of the prepared silica sol product. The residence time of the material in the secondary reactor is 5-60 seconds, preferably 15-35 seconds.

[0039] The structure of the silica sol continuous preparation device of the present invention and its application method are further described below with reference to the accompanying drawings.

[0040] Attachment Figure 1 This is a schematic diagram of the structure of a preferred embodiment of the silica sol continuous preparation device provided by the utility model. Figure 1 As shown, the silica sol continuous preparation device includes: a water glass storage tank 1 is connected to a primary reactor 7 via a water glass metering pump 3; an acid storage tank 2 is connected to the primary reactor 7 via an acid metering pump 4; the primary reactor 7, the secondary reactor 10 and the product collection tank 11 are connected in series in sequence; a first pressure stabilizer 5 is provided on the pipeline connecting the water glass metering pump 3 and the primary reactor 7; a second pressure stabilizer 6 is provided on the pipeline connecting the acid metering pump 4 and the primary reactor 7; and a dispersant storage tank 8 is connected to the secondary reactor 10 via a flow controller 9.

[0041] Taking the reaction of water glass and dilute sulfuric acid to prepare silica sol as an example, the water glass solution is precisely metered from the water glass storage tank 1 through the water glass metering pump 3 and the first pressure stabilizer 5 to the primary reactor 7. Simultaneously, the dilute sulfuric acid solution is precisely metered from the raw material storage tank 2 through the water glass metering pump 4 and the second pressure stabilizer 6 to the primary reactor 7. The two streams are rapidly homogenized in the primary reactor 7, and an acid-base neutralization reaction occurs. The reacted materials enter the secondary reactor 10 from the bottom. Simultaneously, the dispersant solution enters the secondary reactor 10 from the bottom through the dispersant storage tank 8 through the flow controller 9. After mixing and staying in the secondary reactor for a period of time, the two streams flow out of the secondary reactor's overflow port and into the product collection tank 11, where the silica sol product is obtained.

[0042] The bottom of the container refers to the position of 0-10% of the height of the container from bottom to top.

[0043] The following examples will further illustrate the technical effects of the silica sol continuous preparation device provided by the present invention, but do not limit the present invention thereby.

[0044] In the Examples and Comparative Examples:

[0045] Water glass solution, dilute sulfuric acid solution and ammonium citrate solution are all commercially available products.

[0046] Comparative Example 1

[0047] To a 100-liter conventional stirring tank, 15 kg of a 25 wt% sulfuric acid solution was added. While stirring, 45 kg of a 20 wt% water glass solution was slowly added over a 0.5-hour period. Stirring was continued for 0.5 hours, and 0.36 kg of a 5 wt% ammonium citrate solution was added. Stirring was continued for 0.5 hours to obtain a silica sol product, designated as silica sol D1. The stabilization time, particle size, and pH value of the silica sol were measured. The results are shown in Table 1.

[0048] The stability time of silica sol is defined as the storage time during which the silica sol does not gel. The stability time of silica sol represents the stability of the silica sol during use. Prepared silica sol is placed in a constant temperature water bath at 40°C until the silica sol gels and agglomerates. The time at which gel agglomeration occurs is recorded as the stability time.

[0049] The particle size of silica sol was measured using a laser particle size analyzer.

[0050] pH value of silica sol: measured by a portable pH meter.

[0051] Example 1

[0052] Use attached Figure 1 The silica sol continuous preparation apparatus shown in the figure uses a reciprocating plunger pump for the water glass metering pump; a hose pump for the acid metering pump; a powerful dispersing mixer equipped with a set of interlocking high-speed stirring teeth running at 1800-2500 rpm, with a processing capacity of 50-150 kg / hour. The secondary reactor is a 30L overflow stirred kettle equipped with a stirring paddle running at 500 rpm.

[0053] First, add a water glass solution with a silicon dioxide content of 20 wt% to the water glass storage tank 1, and add a 25 wt% sulfuric acid solution to the dilute sulfuric acid storage tank 2; start the water glass metering pump 3, adjust the first pressure stabilizer 5 so that the outlet pressure of the water glass metering pump is 0.3-0.35 MPa, and adjust the flow rate of the water glass metering pump 3 to 45 kg / h; start the dilute sulfuric acid metering pump 4, adjust the second pressure stabilizer 6 so that the outlet pressure of the dilute sulfuric acid metering pump is 0.3-0.35 MPa, and adjust the flow rate of the dilute sulfuric acid metering pump 4 to 15 kg / h; start The high-speed stirring teeth of the primary reactor 7 were used. After the flow rates of water glass and dilute sulfuric acid stabilized, both streams were added simultaneously to the primary reactor 7. A 5 wt% ammonium citrate solution was added to the dispersant storage tank 8, and the flow rate of the ammonium citrate solution was adjusted to 0.36 kg / h by opening the flow controller 9. The discharge from the primary reactor 7 and the ammonium citrate solution were simultaneously added to the bottom of the secondary reactor 10. When the liquid level rose to the stirring paddle of the secondary reactor 10, stirring was initiated, and the liquid level continued to rise until it entered the product collection tank 11 through the overflow port of the secondary reactor. The prepared silica sol product, designated as silica sol S1, was obtained in the product collection tank 11. The stabilization time, particle size, and pH value of the silica sol were measured, and the results are shown in Table 1.

[0054] Example 2

[0055] Using similar Figure 1 The low-cost continuous silica sol preparation device shown is different in that it does not have a first pressure stabilizer and a second pressure stabilizer.

[0056] First, a 20wt% silica solution was added to a water glass storage tank 1, and a 25wt% sulfuric acid solution was added to a dilute sulfuric acid storage tank 2. The water glass metering pump 3 was started and adjusted to a flow rate of 45 kg / h. The dilute sulfuric acid metering pump 4 was started and adjusted to a flow rate of 15 kg / h. The primary intensive mixing reactor 7 was started and both streams were simultaneously added to the primary reactor 7. A 5wt% ammonium citrate solution was added to a dispersant storage tank 8, and the flow rate of the ammonium citrate solution was adjusted to 0.36 kg / h by using a flow controller 9. The discharge from the primary reactor 7 and the ammonium citrate solution were simultaneously added to the bottom of the secondary reactor 10. When the liquid level rose to the top of the stirring paddle in the secondary reactor 10, the stirring motor was started, and the liquid level continued to rise until it overflowed from the secondary reactor and entered the product collection tank 11. The prepared silica sol product, designated as silica sol S2, was obtained in the product collection tank 11. The stabilization time, particle size, and pH value of the silica sol were measured, and the results are shown in Table 1.

[0057] Example 3

[0058] Using similar Figure 1 The low-cost continuous silica sol preparation device shown in the figure differs in that it does not have a dispersant storage tank and flow controller. First, a water glass solution containing 20 wt% silica is added to a water glass storage tank 1, and a 25 wt% sulfuric acid solution is added to a dilute sulfuric acid storage tank 2. Then, the water glass metering pump 3 is turned on, and the first pressure stabilizer 5 is adjusted so that the outlet pressure of the water glass metering pump is 0.3-0.35 MPa, and the flow rate of the water glass metering pump 3 is adjusted to 45 kg / h. Then, the dilute sulfuric acid metering pump 4 is turned on, and the second pressure stabilizer 6 is adjusted so that the outlet pressure of the dilute sulfuric acid metering pump is 0.3-0.35 MPa, and the flow rate of the dilute sulfuric acid metering pump 4 is adjusted to 15 kg / h. Then, the high-speed stirring teeth of the primary reactor 7 are turned on, and after the flow rates of the water glass and dilute sulfuric acid stabilize, the two streams are simultaneously added to the primary reactor 7. The discharge from the primary reactor 7 is added to the bottom of the secondary reactor 10. When the liquid level rises to the stirring paddle of the secondary reactor 10, stirring is started, and the liquid level continues to rise until it enters the product collection tank 11 through the overflow port of the secondary reactor. The prepared silica sol product, referred to as silica sol S3, was obtained in the product collection tank 11. The stabilization time, particle size, and pH value of the silica sol were measured, and the results are shown in Table 1.

[0059] Example 4

[0060] Using similar Figure 1The low-cost continuous silica sol preparation apparatus shown here differs in that it lacks a secondary reactor. First, a 20wt% silica solution is added to a water glass storage tank 1, and a 25wt% sulfuric acid solution is added to a dilute sulfuric acid storage tank 2. The water glass metering pump 3 is turned on and its flow rate is adjusted to 45kg / h. The dilute sulfuric acid metering pump 4 is turned on and its flow rate is adjusted to 15kg / h. A 5wt% ammonium citrate solution is added to a dispersant storage tank 8, and the flow controller 9 is turned on to adjust the flow rate of the ammonium citrate solution to 0.36kg / h. The high-speed stirring teeth of the primary reactor 7 are turned on to simultaneously add the three streams of material to the primary reactor 7. The output of the primary reactor 7 is then added to a product collection tank 11. The prepared silica sol product, designated as silica sol S4, is obtained in the product collection tank 11. The stabilization time, particle size, and pH value of the silica sol are measured, and the results are shown in Table 1.

[0061] The stability time, particle size and pH value of the silica sol prepared under the above different conditions are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] As can be seen from the results in Table 1, the silica sol prepared using the silica sol continuous preparation device provided by the present invention has a stability time of 42-66 hours, and the silica sol prepared using the preferred technical solution has a stability time of 66 hours, which is much longer than the stability time of the silica sol prepared by the acid-base neutralization method in the prior art. The silica sol obtained by the silica sol continuous preparation device of the present invention has higher stability and can meet the use requirements of cracking agent binders. Secondly, the technical process of the present invention is short and the production cost is low, with a cost of 1,500 yuan / ton to 2,200 yuan / ton. Compared with the existing conventional silica sol preparation technologies of ion exchange method and single-substance silicon powder dissolution method (commercial silica sol price is 5,000-6,000 yuan / ton), the production cost is reduced by 56-70%. In addition, the present invention overcomes many shortcomings of the ion exchange method, such as the low concentration of the starting raw material water glass, the long subsequent concentration process required, the high energy consumption, and the large amount of wastewater generated when the ion exchange resin is regenerated and needs to be treated.

Claims

1. A silica sol continuous preparation device, characterized in that: include: The water glass storage tank and water glass metering pump connected in series are used to store and transport raw water glass; Acid storage tanks and acid metering pumps connected in series are used to store and transport inorganic acids; The primary reactor and the product collecting tank are sequentially connected; the water glass metering pump and the acid metering pump are respectively connected to the raw material inlet of the primary reactor.

2. The silica sol continuous preparation device according to claim 1, characterized in that: A secondary reactor is also provided, which is an overflow stirred reactor with a raw material inlet at the bottom, an overflow port at the top and a stirring paddle inside; wherein the primary reactor, the secondary reactor and the product collection tank are connected in sequence.

3. The silica sol continuous preparation device according to claim 2, characterized in that: It also includes a dispersant storage tank and a flow controller connected in series, and the dispersant flow controller is connected to the secondary reactor.

4. The silica sol continuous preparation device according to claim 1, 2 or 3, characterized in that: A first pressure stabilizer is provided on the pipeline connecting the water glass metering pump and the primary reactor; a second pressure stabilizer is provided on the pipeline connecting the acid metering pump and the primary reactor.

5. The silica sol continuous preparation device according to claim 4, characterized in that: The pressure stabilizer is a tank body provided with a pressure stabilization system.

6. The silica sol continuous preparation device according to claim 1, 2 or 3, characterized in that: The primary reactor is a powerful dispersing mixer equipped with a set of mutually engaged stirring teeth.

7. The silica sol continuous preparation device according to claim 2, characterized in that: The volume of the secondary reactor is 15-50L, and a deflection baffle is provided on the inner wall of the secondary reactor.

8. The silica sol continuous preparation device according to claim 1, 2 or 3, characterized in that: The water glass metering pump is a reciprocating plunger pump, a diaphragm pump or a hose pump; the acid metering pump is a reciprocating plunger pump, a diaphragm pump or a hose pump.

9. The silica sol continuous preparation device according to claim 1, 2 or 3, characterized in that: The inner wall of the water glass storage tank is made of M304 stainless steel, and the inner wall of the acid storage tank is made of PVC, organic glass or steel with an acid corrosion resistant coating. The volume ratio of the water glass storage tank to the acid storage tank is 1.5-4:

1.

10. The silica sol continuous preparation device according to claim 3, characterized in that: The flow controller is a reciprocating plunger pump, a diaphragm pump or a hose pump.

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