Method for preparing coating type catalyst by non-bonding method and application of coating type catalyst
By using a binderless method to prepare coated catalysts, the catalyst powder slurry is directly used as a binder, which solves the problems of pore structure changes and active site coverage caused by organic binders in traditional methods. This achieves efficient and stable catalyst preparation, and reduces costs and environmental impact.
Patent Information
- Application Number
- CN202511703080.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-02-10
AI Technical Summary
The use of organic binders in traditional catalyst forming methods leads to changes in catalyst pore structure, coverage or poisoning of active sites, increased preparation costs and environmental burden, and dilution of active component concentration, affecting catalytic efficiency.
A binderless method was used to prepare coated catalysts. The catalyst powder slurry was directly sprayed onto the surface of the support and coated, avoiding the use of organic binders. The original catalyst slurry was used as a binder to form a spherical catalyst with high activity, high selectivity and high strength.
It improves the intrinsic activity and selectivity of the catalyst, maintains the original pore structure, reduces production costs and operational complexity, and enhances catalytic reaction efficiency.
Smart Images
Figure CN121490831A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a method for preparing coated catalysts without binding and its application. Background Technology
[0002] In catalytic reaction processes, catalyst molding technology is a crucial bridge connecting the preparation of active catalyst components with industrial applications. Efficient, stable, and economical molding processes have a vital impact on improving the mechanical strength, mass and heat transfer performance, utilization rate of active components, and overall catalytic reaction efficiency of the catalyst. Traditional catalyst molding methods typically involve adding a certain amount of organic binders, such as cellulose derivatives, starch, polyvinyl alcohol, and resins, to the catalyst powder to impart sufficient plasticity and binding strength for processing into specific shapes (e.g., spherical, columnar, or sheet-like forms) and to ensure that the molded catalyst possesses sufficient mechanical strength to resist wear and impact during handling, loading, and reaction processes.
[0003] However, while the introduction of organic binders brings convenience in molding, it also raises a series of problems that cannot be ignored. First, during the subsequent catalyst calcination and activation process, organic binders usually decompose and escape in the form of carbon dioxide, water and other volatile organic compounds. This not only leads to changes in the catalyst pore structure (such as the generation of additional micropores or pore blockage), affecting its mass transfer performance, but may also leave a small amount of carbonaceous material or other impurities on the catalyst surface, causing coverage or poisoning of the active sites of the catalyst, thereby reducing catalytic activity and selectivity.
[0004] Secondly, the use of organic binders increases the cost of catalyst preparation, especially for large-scale industrial production, where the procurement and disposal costs of binders are a considerable expense. In addition, the decomposition process of organic binders requires additional energy and may release harmful gases, which imposes a certain burden on the environment, contradicting the current concepts of green chemistry and sustainable development. Furthermore, the addition of binders often dilutes the concentration of the active components of the catalyst, reducing the activity per unit mass of catalyst. To achieve the desired catalytic effect, it may be necessary to increase the amount of catalyst or the reactor volume.
[0005] Therefore, in order to solve the negative impact of adding organic binders on catalysts, we need to propose a binder-free method for preparing coated catalysts and its application to address the aforementioned problems. Summary of the Invention
[0006] The purpose of this invention is to provide a method for preparing coated catalysts without binders and its application, which can directly bind the active component powder of the catalyst or its precursor into shape, thereby avoiding the negative effects of organic binders, and preparing practical catalysts with high activity, high selectivity, high strength and excellent stability, so as to solve the problems mentioned in the background art.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A method for preparing a coated catalyst without binder includes the following steps:
[0009] S1. The catalyst powder slurry is heated and stirred to ensure the uniformity of the catalyst powder slurry and obtains a catalyst slurry. The catalyst slurry is then poured into a solvent bottle for later use. The catalyst powder slurry is either catalyst powder that has been dissolved in water and then dried or the original slurry from the catalyst preparation process.
[0010] S2. Pour the carrier onto the turntable of the centrifugal granulation and coating machine, pump the catalyst slurry into the high-pressure spray gun through the peristaltic pump, and spray the catalyst slurry evenly onto the surface of the carrier through the high-pressure spray gun.
[0011] S3. After the catalyst carrier surface is evenly covered with catalyst slurry and the surface has obvious wetness, the weighed powder is evenly sprinkled onto the carrier balls coated with catalyst slurry through a sieve and coated in a centrifugal granulation and coating machine.
[0012] S4. After drying and calcining the coated support, spherical catalysts are obtained.
[0013] Preferably, in step S1, the catalyst powder that is dissolved in water and then dried is prepared by mixing the catalyst powder with water at a mass ratio of 1:6-12g, and then drying it to form a slurry with a viscosity range of 200-600mPa.s.
[0014] Preferably, when the catalyst powder slurry is heated and stirred, the heating temperature is 60-80℃ and the stirring rate is 50-80r / min.
[0015] Preferably, in step S2, the carrier is an alumina microsphere with a diameter of 3.5-5.5 mm, the alumina microsphere has a water absorption rate of 20-30%, the number of surface pits is 80-120, and the pit diameter is 0.1-0.3 mm.
[0016] Preferably, the flow rate of the peristaltic pump is 5-12 mL / min, the nozzle diameter of the spray gun is 0.5 mm, the working pressure of the spray gun is 55-65 psi, the spray distance of the spray gun is 160-200 mm, the atomization diameter is 13-18 cm, the air consumption is 75-230 L / min, and the adhesive flow rate is 95-195 cc / min.
[0017] Preferably, the rotational speed of the centrifugal granulation and coating machine turntable is 600-900 r / min, and its centrifugal force is 220-270 N.
[0018] Preferably, in step S3, the sieve is an 80-120 mesh sieve, and the coating temperature of the centrifugal granulation coating machine is 60-100℃.
[0019] Preferably, the mass ratio of the weighed powder to the carrier is 7-15:10, and the weighed powder is any one of dried powder, pre-calcined powder, and calcined powder.
[0020] Preferably, in step S4, the drying temperature of the coated carrier is 60-120℃, the drying time is 5-10 hours, and the calcination temperature is 380-480℃.
[0021] This invention also provides an application of a method for preparing a coated catalyst without binding, specifically in a fixed-bed process for producing acrolein from propylene or acrolein from acrylic acid.
[0022] The present invention provides a method for preparing coated catalysts without binding and its application, which has the following advantages compared with the prior art:
[0023] 1. The method of the present invention avoids the residual impurities generated by the high-temperature decomposition of organic binders added during molding using traditional techniques, reduces the coverage or poisoning of catalyst active sites, thereby improving the intrinsic activity and selectivity of the catalyst; it can eliminate the pore blockage or structural collapse problems that may occur during binder decomposition, which helps to maintain the original pore structure and specific surface area of the catalyst, and improves mass transfer efficiency and stability; it simplifies the preparation process of the molded catalyst, eliminates the purchase, storage, and mixing of binders, reduces production costs and operational complexity, and shortens the production cycle;
[0024] 2. This invention uses the original catalyst slurry as a binder for catalyst molding, which can significantly improve the dispersion uniformity of the active components of the catalyst. Since the active components in the original slurry are already in a specific dispersion state, using it directly as a binder can avoid the problems of active component agglomeration or uneven distribution that may be caused by traditional external binders. This allows the molded catalyst to have a higher utilization rate of active sites during the reaction process, thereby effectively enhancing the catalytic reaction efficiency. Attached Figure Description
[0025] Figure 1 This is a flowchart of the present invention;
[0026] Figure 2 This is an image of the spherical catalyst prepared in Example 1 of the present invention.
[0027] Figure 3 This is an image of the spherical catalyst prepared in Comparative Example 1 of this invention.
[0028] Figure 4 This is an image of the spherical catalyst prepared in Comparative Example 2 of this invention.
[0029] Figure 5 This is an image of the spherical catalyst prepared in Comparative Example 3 of this invention.
[0030] Figure 6 This is an image of the spherical catalyst prepared in Example 5 of the present invention. Detailed Implementation
[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] This invention provides, for example Figure 1 The method for preparing a coated catalyst using a binderless method, as shown, includes the following steps:
[0033] S1. The catalyst powder slurry is heated and stirred to obtain a catalyst slurry, wherein the catalyst powder slurry is a catalyst powder that has been dissolved in water and dried or the original slurry in the catalyst preparation process.
[0034] The catalyst powder, after being dissolved in water and dried, is prepared by mixing the catalyst powder with water at a mass ratio of 1:6-12g, and then drying it to form a slurry with a viscosity range of 200-600mPa.s.
[0035] When the catalyst powder slurry is heated and stirred, the heating temperature is 60-80℃ and the stirring rate is 50-80r / min.
[0036] S2. Pour the carrier onto the turntable of the centrifugal granulation and coating machine, pump the catalyst slurry into the high-pressure spray gun through the peristaltic pump, and spray the catalyst slurry evenly onto the surface of the carrier through the high-pressure spray gun.
[0037] The carrier is an alumina microsphere with a diameter of 3.5-5.5 mm, a water absorption rate of 20-30%, and 80-120 pits on the surface with a pit diameter of 0.1-0.3 mm.
[0038] The peristaltic pump has a flow rate of 5-12 mL / min, the spray gun nozzle diameter is 0.5 mm, the spray gun working pressure is 55-65 psi, the spray gun spray distance is 160-200 mm, the atomization diameter is 13-18 cm, the air consumption is 75-230 L / min, and the adhesive flow rate is 95-195 cc / min.
[0039] The rotation speed of the centrifugal granulation and coating machine is 600-900 r / min, and its centrifugal force is 220-270 N.
[0040] S3. After the catalyst carrier surface is evenly covered with catalyst slurry and the surface has obvious wetness, the weighed powder is evenly sprinkled onto the carrier balls coated with catalyst slurry through a sieve and coated in a centrifugal granulation and coating machine.
[0041] The screen is an 80-120 mesh screen, and the coating temperature of the centrifugal granulation coating machine is 60-100℃.
[0042] The mass ratio of the weighed powder to the carrier is 7-15:10, and the weighed powder is any one of dried powder, pre-calcined powder, and calcined powder.
[0043] S4. After drying and calcining the coated support, spherical catalysts are obtained.
[0044] The drying temperature of the coated carrier is 60-120℃, the drying time is 5-10 hours, and the calcination temperature is 380-480℃.
[0045] This invention also provides an application of a method for preparing a coated catalyst using a non-binding method. The method described above is applied to a fixed-bed process for preparing a coated catalyst from propylene to acrolein or from acrolein to acrylic acid. The spherical catalyst prepared by the non-binding method is evaluated and tested in a fixed-bed process for preparing acrolein or from acrolein to acrylic acid.
[0046] Based on the above-described method for preparing coated catalysts without binders, the following specific examples and comparative examples are provided to verify that the method can solve the problem of negative impacts on catalysts caused by the addition of binders:
[0047] Example 1
[0048] Step 1: Weigh 10g of dried catalyst powder and mix it with 100g of deionized water. Heat and stir the mixture until there is no obvious powder residue in the solution to obtain a catalyst slurry. Collect the catalyst slurry for later use. At the same time, weigh 100g of alumina microspheres and pour them onto the turntable of a centrifugal granulation and coating machine. Set the turntable speed to 600r / min. Then, use a peristaltic pump with a flow rate of 8.5ml / min to flow the catalyst slurry into a high-pressure spray gun. Spray the catalyst slurry evenly onto the surface of the alumina microspheres through the high-pressure spray gun for 1-2 minutes.
[0049] Step 2: Weigh 150g of the fully calcined catalyst powder and pass it through an 80-mesh sieve. Spread the powder evenly onto the carrier spheres that have been coated with the catalyst powder slurry. During this coating process, alternate between spraying the slurry and spreading the powder 3-5 times.
[0050] Step 3: After the powder coating is completed, place the coated spherical catalyst in an iron pan and dry it in an oven set at 100℃ for 6-8 hours. After the drying process is completed and the spherical catalyst is cooled, place it in a muffle furnace for calcination. The calcination program is set to raise the temperature to 250℃ at a heating rate of 2℃ / min and hold for 2 hours, then raise the temperature to 480℃ within 57 minutes and hold for 8 hours. Finally, the acrylic acid one-transforming catalyst (denoted as B1-1) is obtained.
[0051] Comparative Example 1
[0052] In Example 1, the mixture of 10g powder and deionized water was replaced with 100ml of deionized water, and the mixture was heated and stirred. The other steps were the same as in Example 1, and an acrylic acid one-transforming catalyst (denoted as B1-2) was obtained.
[0053] Comparative Example 2
[0054] In Example 1, 10g of dried catalyst powder was replaced with 5g of polyvinyl alcohol, hydroxyethyl cellulose, and glycerol, respectively. The other steps were the same as in Example 1, resulting in three different acrylic acid one-transforming catalysts (denoted as B1-3, B1-4, and B1-5, respectively).
[0055] Comparative Example 3
[0056] In Example 1, the catalyst powder in step 2 was replaced with catalyst powder and inorganic binder silicon tripolyphosphate for coating. The other steps were the same as in Example 1, and an acrylic acid one-reverse molding catalyst (denoted as B1-6) was obtained.
[0057] Load calculations, wear tests, and evaluation tests were performed on the different acrylic acid one-transforming catalysts obtained in Example 1 and Comparative Examples 1-3. The results are shown in Tables 1, 2, and 3, respectively.
[0058] Loading rate calculation: Loading amount (%) = [(mass after calcination - carrier mass) / total mass after calcination] * 100%
[0059] Wear test conditions: the wear tester speed was set to 25 r / min, the time was 10-12 min; the catalyst mass was 35±1 g;
[0060] Calculation method: Wear (%) = [(Pre-grind mass - Post-grind mass) / Pre-grind mass] * 100%,
[0061] Evaluation conditions: The performance evaluation of the propylene catalyst was carried out in a side-stream reaction tube. The catalyst was placed in the isothermal zone of the reaction tube using the external diluent method (20 ml catalyst + 20 ml inert spheres). The reaction pressure was atmospheric pressure. The reaction temperature of the first-stage reaction catalyst was 300-350℃, the space velocity was 70-120 h⁻¹, and the reactants contained 9.8 vol% propylene, 15.3 vol% oxygen, 17.3 vol% water vapor, and 57.6 vol% nitrogen. The reaction temperature of the second-stage reaction catalyst was 240-300℃, the space velocity was 70-120 h⁻¹, and the reactants contained 5-15 vol% acrolein, 10-20 vol% oxygen, 5-20 vol% water vapor, and 55-70 vol% nitrogen. Both reactions simulated an industrial setup for the oxidation of propylene to acrolein. The reaction conversion and yield results were analyzed by gas chromatography, as shown in Tables 1 to 3 below.
[0062] Table 1
[0063]
[0064] As shown in Table 1, under the same reaction temperature and space velocity conditions, sample B1-1 in Example 1 exhibited the lowest attrition rate and the highest catalytic activity compared to other samples, with a loading deviation of 1.5%. In Comparative Example 1, using water as a binder, although its catalytic activity was similar to B1-1, its attrition rate was higher, and visible cracks appeared on the catalyst surface after calcination. This may be due to the internal shrinkage force of the powder during calcination, which prevented the filling of these vacancies, leading to cracks and resulting in a poorly prepared catalyst. Figure 3 As shown. Using catalyst powder slurry as a binder can effectively compensate for this deficiency, and the catalyst surface is smoother, resulting in a catalyst as shown. Figure 2 As shown.
[0065] Table 2
[0066]
[0067] As shown in Table 2, in Comparative Example 2, after adding organic binders and undergoing coating treatment, it was clearly observed that although the wear rate was reduced, the catalytic activity of the spherical catalyst was low, with a propylene conversion rate of only about 90%. Although adding organic binders can more effectively adhere the powder to the support, the organic matter they contain may have a partial poisoning effect on the active catalyst, resulting in lower catalyst activity. For example, the catalyst prepared in Comparative Example 2... Figure 4 As shown. However, using catalyst powder slurry as a binder can effectively avoid such problems because the introduced binder itself is the active substance of the catalyst.
[0068] Table 3
[0069]
[0070] Table 3 shows that in Comparative Example 3, powder additives were added to reduce the wear rate. The data in the table indicate that the wear rate of the spherical catalyst was indeed reduced, but the catalytic activity was poor, and the sphericity was not ideal. The poor catalytic activity may be due to the difficulty in volatilizing silicon tripolyphosphate, which clogs the catalyst pores, leading to a decrease in activity. The poor sphericity is because silicon tripolyphosphate is a macromolecule with a large particle size, making it difficult to achieve uniform coating during the coating process, resulting in bumps that affect the sphericity. The catalyst prepared in Comparative Example 3... Figure 5 As shown.
[0071] Example 2
[0072] In Example 1, 10g of dried catalyst powder was dissolved in 100g of deionized water and heated and stirred. Instead, 100ml of concentrated slurry from the catalyst preparation process was used. The other steps were the same as in Example 1, resulting in an acrylic acid one-reaction molding catalyst (denoted as B1-7). Using the original catalyst slurry as a binder for catalyst molding can significantly improve the dispersion uniformity of the active components of the catalyst. Since the active components in the original slurry are already in a specific dispersion state, using it directly as a binder can avoid the problems of active component agglomeration or uneven distribution that may be caused by traditional external binders. This results in a higher utilization rate of active sites in the molded catalyst during the reaction process, thereby effectively enhancing the catalytic reaction efficiency.
[0073] Example 3
[0074] In Example 1, the powder that had been completely calcined was replaced with the powder that had been dried, and the other steps were the same as in Example 1, to obtain an acrylic acid one-transforming catalyst (denoted as B1-8).
[0075] Example 4
[0076] In Example 1, the powder that had been fully calcined was replaced with the powder that had been pre-calcined, and the other steps were the same as in Example 1, to obtain an acrylic acid one-transforming catalyst (denoted as B1-9).
[0077] The loading rate of the spherical acrylic acid catalysts obtained in Examples 2-4 above was calculated after calcination, the wear was tested, and the catalysts were evaluated on an acrylic acid fixed bed. The data are shown in Table 4.
[0078] Table 4
[0079]
[0080] The data in Table 4 show that the catalysts with different pretreatment methods (concentrated slurry, dried powder, and pre-calcined powder) do not differ much in terms of loading rate, wear rate, and catalytic activity, indicating that the pretreatment method has little impact on catalyst performance.
[0081] Example 5
[0082] In Example 1, 150g of the fully calcined primary reaction catalyst powder weighed in step 2 was replaced with 72g of the calcined secondary reaction catalyst powder. The other steps were the same as in Example 1, yielding an acrylic acid secondary reaction molding catalyst (denoted as B2-1). The catalyst prepared in Example 5 is as follows... Figure 6 As shown.
[0083] The calculated loading, wear test, and fixed-bed evaluation test of the acrylic acid double-transforming catalyst obtained in Example 5 are shown in Table 5.
[0084] Table 5
[0085]
[0086] The data in Table 5 show that the catalyst in the oxidation of acrolein to acrylic acid exhibits excellent performance. The high conversion rate (XACR) and high yield (YAA) indicate that the catalyst performs well in this reaction, while the low YCOx value reflects the high selectivity of the reaction.
[0087] In summary, the method provided by this invention avoids the residual impurities generated by the high-temperature decomposition of organic binders added during molding using traditional techniques, reducing the coverage or poisoning of catalyst active sites, thereby improving the intrinsic activity and selectivity of the catalyst; it can eliminate the pore blockage or structural collapse problems that may occur during binder decomposition, helping to maintain the original pore structure and specific surface area of the catalyst, improving mass transfer efficiency and stability; it simplifies the preparation process of the molded catalyst, eliminating the procurement, storage, and mixing of binders, reducing production costs and operational complexity, and shortening the production cycle.
[0088] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a coated catalyst using a binderless method, characterized in that: Includes the following steps: S1. The catalyst powder slurry is heated and stirred to obtain a catalyst slurry, wherein the catalyst powder slurry is a catalyst powder that has been dissolved in water and dried or the original slurry in the catalyst preparation process. S2. Pour the carrier onto the turntable of the centrifugal granulation and coating machine, pump the catalyst slurry into the high-pressure spray gun through the peristaltic pump, and spray the catalyst slurry evenly onto the surface of the carrier through the high-pressure spray gun. S3. After the catalyst carrier surface is evenly covered with catalyst slurry and the surface has obvious wetness, the weighed powder is evenly sprinkled onto the carrier balls coated with catalyst slurry through a sieve and coated in a centrifugal granulation and coating machine. S4. After drying and calcining the coated support, spherical catalysts are obtained.
2. The method for preparing a coated catalyst using a non-binding method according to claim 1, characterized in that: In step S1, the catalyst powder that is dissolved in water and then dried is prepared by mixing the catalyst powder with water at a mass ratio of 1:6-12g and drying it to form a slurry with a viscosity range of 200-600mPa.s.
3. The method for preparing a coated catalyst using a non-adhesive method according to claim 2, characterized in that: When the catalyst powder slurry is heated and stirred, the heating temperature is 60-80℃ and the stirring rate is 50-80r / min.
4. The method for preparing a coated catalyst using a non-binding method according to claim 3, characterized in that: In step S2, the carrier is an alumina microsphere with a diameter of 3.5-5.5 mm, the alumina microsphere has a water absorption rate of 20-30%, the number of surface pits is 80-120, and the pit diameter is 0.1-0.3 mm.
5. The method for preparing a coated catalyst using a non-adhesive method according to claim 4, characterized in that: The peristaltic pump has a flow rate of 5-12 mL / min, the spray gun nozzle diameter is 0.5 mm, the spray gun working pressure is 55-65 psi, the spray gun spray distance is 160-200 mm, the atomization diameter is 13-18 cm, the air consumption is 75-230 L / min, and the adhesive flow rate is 95-195 cc / min.
6. The method for preparing a coated catalyst using a non-adhesive method according to claim 5, characterized in that: The rotation speed of the centrifugal granulation and coating machine is 600-900 r / min, and its centrifugal force is 220-270 N.
7. The method for preparing a coated catalyst using a non-adhesive method according to claim 6, characterized in that: In step S3, the sieve is an 80-120 mesh sieve, and the coating temperature of the centrifugal granulation coating machine is 60-100℃.
8. The method for preparing a coated catalyst using a non-adhesive method according to claim 7, characterized in that: The mass ratio of the weighed powder to the carrier is 7-15:10, and the weighed powder is any one of dried powder, pre-calcined powder, and calcined powder.
9. The method for preparing a coated catalyst using a non-adhesive method according to claim 8, characterized in that: In step S4, the drying temperature of the coated carrier is 60-120℃, the drying time is 5-10 hours, and the calcination temperature is 380-480℃.
10. An application of a method for preparing coated catalysts using a binderless process, characterized in that: The application of the method for preparing coated catalysts without adhesive as described in any one of claims 1-9 in a fixed bed for propylene to acrolein or acrolein to acrylic acid production.