Spherical aluminum oxide composite carrier with millimeter-level tunnel structure on surface and preparation method of spherical aluminum oxide composite carrier
By preparing spherical alumina composite supports with millimeter-scale concave channel structures on their surfaces, the problems of insufficient catalyst powder adhesion and mechanical strength were solved, thereby improving the stability and mass transfer efficiency of the catalyst at high temperatures.
Patent Information
- Application Number
- CN202511173010.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-12-16
AI Technical Summary
Existing catalyst supports have shortcomings in terms of catalyst powder adhesion and mechanical strength, especially when used in high-temperature environments, and traditional inorganic fiber additives have problems with size inhomogeneity and agglomeration.
Using calcined alumina, calcined kaolin, quartz, and sintering aids as the main raw materials, a spherical alumina composite carrier is formed through primary and secondary balling. Combined with a pore-forming agent and a binder, a spherical alumina composite carrier with a uniform millimeter-level concave pit structure on the surface is prepared, which ensures that the catalyst powder adheres firmly and enhances the mechanical strength.
The prepared spherical alumina composite support exhibits high strength and stability at high temperatures, good adhesion of catalyst powder, improved mechanical strength and mass transfer efficiency of the catalyst, and is suitable for high temperature and high pressure environments.
Smart Images
Figure CN121130867A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a kind of catalyst carriers, in particular to a kind of millimeter-level tunnel structure of spherical alumina composite carrier with surface, also relates to its preparation method, belong to catalyst carrier technical field. BACKGROUND
[0002] The core process of chemical industry (such as catalytic cracking, hydrotreating, olefin polymerization, etc.) is highly dependent on catalyst and carrier technology. Catalysts can improve the chemical reaction rate, promote large-scale production, and help the green and efficient development of industry. At the same time, the carrier is the core component of the catalyst, which affects the dispersion, stability and mass transfer efficiency of the active component. Common catalyst carriers include alumina, activated carbon, silicon dioxide, zeolite molecular sieve, etc. Alumina is a high-hardness compound. Coated catalysts prepared with alumina inert carrier have the advantages of high strength, good heat transfer effect, less catalyst active component, easy to load, etc. Therefore, it is favored in catalyst research and industrial application. The focus of the research of coated catalysts is how to firmly attach the catalyst powder to the inert carrier, thereby enhancing the mechanical strength of the catalyst. In order to enhance the mechanical strength of the connection between the catalyst active component and the carrier, glass fibers, carbon fibers and other substances are usually added to the catalyst active powder. However, inorganic fibers have the problems of uneven size and easy agglomeration. Some studies add organic matter to the catalyst to adjust the specific surface area and pore volume of the catalyst. However, these organic matters may not be completely calcined, and there may be residual carbon impurities. Therefore, chemical or physical modification of the surface of the carrier is a research direction with practical application significance. It not only achieves the purpose of enhancing the mechanical strength of the catalyst, but also expects to have a synergistic effect on the catalytic reaction. SUMMARY
[0003] In view of the defects of the prior art, the first object of the present application is to provide a spherical alumina composite carrier with millimeter-level tunnel structure on the surface. The surface has a "concave" tunnel structure and the tunnels are uniformly distributed. The size is 0.1-1.0 mm, and the depth of the concave pit is 0.1-1.0 mm. It is beneficial for the firm attachment of catalyst powder. At the same time, the composite carrier has the characteristics of high strength and high temperature resistance, and is suitable for use in high temperature environment for a long time.
[0004] The second object of the present application is to provide a preparation method of a spherical alumina composite carrier with millimeter-level tunnel structure on the surface. The method has wide raw material sources and simple operation, and meets the batch production.
[0005] In order to achieve the above technical purpose, the present application improves a preparation method of a spherical alumina composite carrier with millimeter-level tunnel structure on the surface, which comprises the following steps:
[0006] 1) mixing raw materials including calcined alumina, calcined kaolin, quartz and sintering aids to form a base material;
[0007] 2) forming a ball material rough blank by primary balling of a part of the base material;
[0008] 3) mixing another part of the base material with a pore-forming agent and a binder to form a pore-forming raw material; the pore-forming agent has a particle structure with a particle size distribution of 0.1-1.0 mm; the average particle size of the pore-forming agent is 2-5 times the particle size of the base material;
[0009] 4) forming a ball blank body by secondary balling of the pore-forming raw material and the ball material rough blank;
[0010] 5) the obtained ball blank body is sequentially subjected to drying, calcination and shaping, and the spherical alumina composite carrier with millimeter-level tunnel structure on the surface is obtained.
[0011] The preparation process of the spherical alumina composite carrier with millimeter-level tunnel structure on the surface of the present application is as follows: a part of the base material composed of calcined alumina, calcined kaolin, quartz and sintering aids and the like is formed into a ball material rough blank by primary balling, and these base materials can form a high-strength and high-temperature-stable composite carrier skeleton in the subsequent high-temperature solid-phase reaction process; and the ball material rough blank is further subjected to secondary balling with the base material doped with a pore-forming agent with a proper particle size and a binder, and the pore-forming agent is uniformly embedded in the surface layer of the ball material rough blank in the secondary balling process; the pore-forming agent is an organic particle, which can be pyrolyzed and volatilized in the subsequent high-temperature calcination process; and after polishing, a uniform "concave" tunnel structure can be formed on the surface of the composite carrier skeleton, and these tunnel structures are not through holes, but "concave" tunnels with a certain depth and millimeter-level size, which can ensure the stable loading of catalyst powder and will not affect the mechanical properties of the composite carrier.
[0012] The spherical alumina composite carrier with millimeter-level tunnel structure on the surface of the present application is prepared by using calcined alumina, calcined kaolin, quartz and sintering aids as main raw materials; the calcined alumina (α-Al2O3) as the main crystal phase imparts high melting point, high hardness and chemical stability to the composite carrier; the calcined kaolin is converted into mullite phase with high mechanical strength and high-temperature resistance at high temperature, and is compounded with α-Al2O3 to compensate for the brittleness of pure α-Al2O3 phase; the quartz reacts with impurities in alumina or kaolin to generate a liquid phase, which promotes sintering densification; and the sintering aids can reduce the sintering temperature and promote particle rearrangement through liquid or solid phase diffusion.
[0013] In the preparation process of the spherical alumina composite carrier with millimeter-level tunnel structure, the particle size distribution of the raw materials such as calcined alumina, calcined kaolin, quartz and sintering aids should match the particle size distribution of the pore-forming agent particles, so as to ensure that the pore-forming agent particles can be uniformly dispersed in the raw materials and uniformly embedded in the surface layer of the spherical rough blank, thereby forming a uniform "concave" tunnel structure on the surface of the composite carrier.
[0014] As a preferred scheme, the mass percentage composition of the calcined alumina, calcined kaolin, quartz and sintering aid in the base material is: 65-75%, 5-15%, 10-15%, 1-5%. If the proportion of calcined alumina is too high, the sintering difficulty will increase, and if the proportion of calcined alumina is too low, the high-temperature performance will decrease; if the proportion of calcined kaolin is too high, too much glass phase will be generated, and if the proportion of calcined kaolin is too low, too little mullite phase will be generated, and the composite carrier will be brittle; if the proportion of quartz is too high, the high-temperature strength will decrease, and if the proportion of quartz is too low, the sintering will be difficult; if the proportion of sintering aid is too high, the high-temperature performance will be damaged, and if the proportion of sintering aid is too low, incomplete sintering will occur.
[0015] As a preferred scheme, the sintering aid includes at least one of MgO, CaCO3 and CaO. The preferred sintering aid can promote the low-temperature generation of liquid phase, reduce the solid phase reaction temperature and improve the solid phase reaction efficiency.
[0016] As a preferred scheme, in step 3), the base material, the pore-forming agent and the binder are mixed in a mass ratio of 1:0.6-1.2:0.01-0.05. If the proportion of the pore-forming agent is too low, the "concave" tunnel structure formed on the surface of the composite carrier is less, which is not conducive to the loading of the catalyst, and if the proportion of the pore-forming agent is too high, it is difficult to form a single and uniformly distributed tunnel structure on the surface of the composite carrier, and a connected tunnel structure is easily formed, which reduces the strength of the composite carrier and is not conducive to the loading of the catalyst. The introduction of the appropriate binder can improve the bonding strength of the base material and avoid the collapse of the pore during the low-temperature roasting process for removing the pore-forming agent.
[0017] As a preferred scheme, the pore-forming agent includes at least one of walnut sand, hawthorn core, polystyrene, polyvinyl alcohol, polymethyl methacrylate and polyvinylpyrrolidone. The preferred pore-forming agent has poor water solubility, which can ensure that the pore-forming agent will not dissolve in water during the balling process, otherwise the pore-forming agent will dissolve and adhere to the surface of the base material particles, and on the other hand, the pore-forming agent has a stable structure morphology at room temperature and a low decomposition temperature, and the residual amount is low during the decomposition process, so that the pore diameter formed is almost similar to the particle size of the pore-forming agent particles, and it is particularly easy to control the size of the "concave" tunnel.
[0018] As a preferred scheme, the binder comprises at least one of hydroxypropyl methyl cellulose, carboxymethyl cellulose and sesbania powder.
[0019] As a preferred scheme, the particle size of the spherical material rough blank is 3.6-4.2 mm.
[0020] As a preferred scheme, the particle size of the spherical material rough blank is 3.6-4.2 mm.
[0021] As a preferred scheme, the particle size of the spherical material rough blank is 3.6-4.2 mm.
[0022] As a preferred scheme, the particle size of the spherical material rough blank is 3.6-4.2 mm.
[0023] As a preferred scheme, the drying condition is 80-150 ℃ for 6-24 h.
[0024] As a preferred scheme, the calcination condition is first calcination at 300-500 ℃ for 2-3 h, and then calcination at 1200-1400 ℃ for 3-5 h. The calcination process first realizes pyrolysis removal of the organic binder and the pore-forming agent at low temperature, and then realizes sintering at high temperature to generate a high-strength carrier. The first calcination at low temperature removes the volatile components (water and organic matter) and completes phase transition, which can avoid volume mutation during high-temperature sintering, improve reaction efficiency, and thus obtain a more uniform and dense microstructure.
[0025] As a preferred scheme, the shaping condition is a polishing process, the polishing machine rotates at 40-60 r / min for 5-20 min. The shaping process mainly exposes the “concave” channel structure on the surface of the sphere, which needs to be completed at a low speed to avoid damage to the pore structure on the surface of the composite carrier, and the polishing time needs to be properly controlled. If the polishing is excessive, the “concave” channel depth will be shallow, which is not conducive to subsequent catalyst loading. If the polishing is not enough, the “concave” channel will still be embedded and cannot be fully exposed.
[0026] The application also provides the spherical alumina composite carrier with millimeter-scale trench structure on the surface, which is obtained by the preparation method.
[0027] Compared with the prior art, the technical scheme of the application has the beneficial technical effects:
[0028] (1) The composite carrier has the characteristics of high mechanical strength, high temperature resistance and the like, and has good stability under high temperature and high filling pressure, and is suitable for application in high temperature and high pressure environments.
[0029] (2) The composite carrier has the uniformly distributed millimeter-scale concave structure on the surface, which is beneficial to the adhesion of the catalyst powder, and further enhances the connection strength between the catalyst powder and the carrier, thereby also enhancing the impact-resistant mechanical strength of the catalyst particles. BRIEF DESCRIPTION OF DRAWINGS
[0030] Figure 1 The figure is the real object picture of the spherical alumina composite carrier with millimeter-scale trench structure on the surface prepared in Example 1.
[0031] Figure 2 The figure is the real object picture of the spherical alumina composite carrier with millimeter-scale trench structure on the surface prepared in Example 2.
[0032] Figure 3 The figure is the real object picture of the spherical alumina composite carrier prepared in Comparative Example 1.
[0033] Figure 4 The figure is the real object picture of the spherical alumina composite carrier prepared in Comparative Example 2.
[0034] Figure 5 The figure is the real object picture of the spherical alumina composite carrier prepared in Comparative Example 3.
[0035] Figure 6 The figure is the real object picture of the spherical alumina composite carrier prepared in Comparative Example 4. DETAILED DESCRIPTION
[0036] The following specific examples are intended to further illustrate the present application and are not intended to limit the scope of the claims.
[0037] The raw materials involved in the following specific examples are all conventional commercially available materials, if not otherwise specified.
[0038] Example 1
[0039] (1) Calcined alumina, calcined kaolin, quartz and sintering aids (MgO, CaCO3 in a mass ratio of 2:1) were mixed according to the following mass percentage composition: 74%, 13%, 10%, 3% to obtain a uniform base material (average particle size 0.15 mm), and then the mixed base material was added to a balling machine together with pure water (the mass of pure water was 20% of the mass of the base material), and the balling was carried out under the conditions of a rotation speed of 40 r / min and an inclination angle of 20° to obtain a ball material rough blank with an average particle size of 4.0 mm.
[0040] (2) The base material, pore-forming agent (particle size distribution 0.1-1.0 mm, average particle size 0.4 mm) and binder were mixed to obtain a uniform pore-forming agent mixed powder, wherein the mass ratio of the base material, pore-forming agent (hawthorn core and polyvinyl alcohol in a mass ratio of 1:1) and binder (sesbania powder) was 1:1:0.02. The ball material rough blank and the above-mentioned pore-forming agent mixed powder were added to a balling machine (the mass of pure water was 12% of the mass of the pore-forming agent mixed powder), and the balling was carried out under the conditions of a rotation speed of 50 r / min and an inclination angle of 20° to obtain a ball material blank with an average particle size of 5.4 mm.
[0041] (3) The ball material blank was dried at 120°C for 300 min.
[0042] (4) The dried product was heated to a temperature of 300°C and calcined for 2 h, and then heated to a temperature of 1300°C and calcined for 4 h.
[0043] (5) After the calcined product was shaped (coated and polished), wherein the polishing conditions were: the rotation speed of the polishing machine was 50 r / min and the polishing time was 10 min, a spherical alumina composite carrier with a millimeter-level tunnel structure on the surface was obtained, and the composite carrier surface had a uniform distribution of millimeter-level "concave" tunnel structures, as shown in Figure 1 .
[0044] The compressive strength of the composite carrier was 512 N / pellet, and the loose bulk density was 1.03 g / cm 3 After the surface was coated with a catalyst, the composite carrier did not crack under the conditions of 1200°C for 4 hours, and no obvious catalyst powder was observed to fall off from the surface.
[0045] Example 2
[0046] The calcined alumina, calcined kaolin, quartz and sintering aids (MgO, CaCO3 in a mass ratio of 2:1) are mixed in the following mass percentage components: 72%, 15%, 10%, 3% to obtain a uniform base material (average particle size of 0.15 mm), and then the mixed base material is mixed with pure water (the mass of pure water is 20% of the mass of the base material) under the action of a balling machine with a rotation speed of 40 r / min and an inclination angle of 20° to obtain a ball material rough blank with an average particle size of 3.7 mm.
[0047] (1) The base material, pore-forming agent (particle size distribution of 0.1-1.0 mm, average particle size of 0.55 mm) and binder are mixed to obtain a uniform pore-forming agent mixed powder, wherein the mass ratio of the base material, pore-forming agent (walnut sand) and binder (hydroxypropyl methyl cellulose) is 1:1.1:0.02. The ball material rough blank is mixed with the above-mentioned pore-forming agent mixed powder and pure water (the mass of pure water is 12% of the mass of the pore-forming agent mixed powder) under the conditions of a rotation speed of 50 r / min and an inclination angle of 20° to obtain a ball material blank with an average particle size of 5.4 mm.
[0048] (2) The ball material blank is dried at 120°C for 300 min.
[0049] (3) The dried product is heated to a temperature of 300°C and calcined for 2 h, and then heated to a temperature of 1350°C and calcined for 4 h.
[0050] (4) After shaping (coating and polishing), the calcined product has a millimeter-level tunnel structure on the surface, and the polishing conditions are: the rotation speed of the polishing machine is 50 r / min, and the shaping time is 10 min.
[0051] The mechanical strength of the qualified carrier is 500 N per carrier, and the loose bulk density is 0.96 g / cm 3 . Under the condition of 1200°C for 4 hours, no cracking occurs, and the carrier surface has a uniform millimeter-level tunnel structure, as shown in Figure 2 .
[0052] Comparative Example 1
[0053] Compared with Example 1, the only difference is that a micrometer-level (particle size distribution of 5-40 microns) potato starch pore-forming agent is used.
[0054] On the one hand, potato starch is in the form of an oval sheet and has good water solubility, and is easily wetted by water to be attached to the surface of the base ball with a large contact surface, and after decomposition, a thin shell is formed on the surface of the ball, and no tunnel of the target size is generated; on the other hand, the starch will expand and foam at 300°C, causing the base material in the pore-forming raw material to be separated from the expanded starch before sintering with the base ball to form a whole, so that the tunnel cannot be formed on the outer surface.
[0055] The final composite carrier has a smooth appearance, and the pores are invisible to the naked eye. The micro-pores need to be observed by electron microscopy and other instruments, which is not conducive to the adhesion of catalyst powder and cannot be applied to coated catalysts, such as Figure 3 .
[0056] Comparative Example 2
[0057] The only difference compared with Example 1 is that the mass ratio of base material, pore-forming agent and binder is 1:2:0.02.
[0058] Excessive addition of pore-forming agent leads to excessive development of pore structure and too large pore size of the obtained composite carrier, thereby causing pore collapse and surface powdering, which cannot produce a surface dimple structure appearance, and reduces the mechanical strength (compressive strength of 189 N / pellet) and thermal stability of the carrier, thereby affecting the overall performance and service life of the catalyst, such as Figure 4 .
[0059] Comparative Example 3
[0060] The only difference compared with Example 1 is that the mass ratio of base material, pore-forming agent and binder is 1:0.2:0.02.
[0061] Insufficient addition of pore-forming agent and too large spacing between pore-forming agent particles lead to uneven pore size distribution, thereby causing the carrier surface to lose the pore structure characteristics and appear more smooth surface, which is not conducive to the adhesion of catalyst powder and cannot be applied to coated catalysts, such as Figure 5 .
[0062] Comparative Example 4
[0063] The only difference compared with Example 1 is that the pore-forming agent with an average particle size of 0.9 mm is used, which has a large difference in particle size from the base material.
[0064] Due to the large difference in particle size between the pore-forming agent and the base material, the density or fluidity does not match, which is prone to stratification or segregation, and the large pore-forming agent particles will protrude from the surface, making the formed spherical body uneven, and the sphericity of the spherical body is poor, which cannot be applied to coated spherical catalysts, such as Figure 6 .
Claims
1. A method for preparing a spherical alumina composite carrier with a surface having millimeter-scale channel structure, characterized in that: Includes the following steps: 1) Mix the raw materials, including calcined alumina, calcined kaolin, quartz and sintering aids, evenly to form a base material; 2) A portion of the base material is ball-smoked to form a ball-shaped rough blank; 3) Mix another portion of the base material with the pore-forming agent and binder evenly to form a pore-forming raw material; The pore-forming agent has a granular structure with a particle size distribution of 0.1~1.0 mm; The average particle size of the pore-forming agent is 2 to 5 times that of the base material. 4) The pore-forming raw material and the ball blank are subjected to secondary ball-boring to form a ball blank; 5) The obtained spherical blanks are successively dried, fired and shaped to obtain the final product.
2. The method for preparing a spherical alumina composite carrier with a millimeter-scale channel structure on its surface according to claim 1, characterized in that: The mass percentage composition of the base material is as follows: 65-75%, 5-15%, 10-15%, and 1-5%, respectively.
3. The method for preparing a spherical alumina composite carrier with a millimeter-scale channel structure on its surface according to claim 2, characterized in that: The sintering aid includes at least one of MgO, CaCO3, and CaO.
4. The method for preparing a spherical alumina composite carrier with a millimeter-scale channel structure on its surface according to claim 1, characterized in that: In step 3), the base material, pore-forming agent and binder are mixed at a mass ratio of 1:0.6~1.2:0.01~0.
05.
5. The method for preparing a spherical alumina composite carrier with a surface having millimeter-scale channel structure according to claim 1 or 4, characterized in that: The pore-forming agent includes at least one of walnut shell, hawthorn kernel, polystyrene, polyvinyl alcohol, polymethyl methacrylate, and polyvinylpyrrolidone. The binder includes at least one of hydroxypropyl methylcellulose, carboxymethyl cellulose, and guar gum powder.
6. The method for preparing a spherical alumina composite carrier with a surface having millimeter-level channel structure according to claim 1, characterized in that: The particle size of the spherical blank is 3.6~4.2mm; The particle size of the spherical preform is 5.2~5.6mm.
7. The method for preparing a spherical alumina composite carrier with a millimeter-scale channel structure on its surface according to claim 1, characterized in that: The conditions for the first ball-smearing process are as follows: add the base material and water into the ball-smearing machine, control the rotation speed of the ball-smearing machine to be 30~60 r / min, and the tilt angle to be 15°~35°; The conditions for the secondary ball-making process are as follows: the hole-making raw material, the ball blank, and water are added to the ball-making machine, and the rotation speed of the ball-making machine is controlled at 40~70 r / min, and the tilt angle is 15°~35°.
8. The method for preparing a spherical alumina composite carrier with a millimeter-scale channel structure on its surface according to claim 1, characterized in that: The drying conditions are: drying at 80~150 ℃ for 6~24 h; The calcination conditions are as follows: first, calcin at 300~500℃ for 2~3 hours, then raise the temperature to 1200~1400℃ and calcin for 3~5 hours.
9. The method for preparing a spherical alumina composite carrier with a surface having millimeter-level channel structure according to claim 1, characterized in that: The shaping conditions are as follows: a polishing process is used, the polishing machine speed is 40~60 r / min, and the time is 5~20 min.
10. A spherical alumina composite carrier with a surface having millimeter-scale channel structure, characterized in that: It is obtained by the preparation method described in any one of claims 1 to 9.