Tabletting method and mold for improving forming rate of catalyst

Abstract

The invention discloses a tabletting method and mold for improving the forming rate of a catalyst, and the method comprises the following steps: mold pretreatment: preheating the temperature of a mold cavity to a preset temperature through a temperature regulation and control unit, and keeping the temperature constant; cleaning the inner wall of the neck bush; material filling: uniformly filling the catalyst powder into a neck bush of a die cavity assembly; pre-pressing and exhausting, starting a pressure driving mechanism, controlling an upper punch to move downwards, and exhausting air in a material gap; gradient pressure forming is conducted, and after prepressing is completed, the pressure is increased in a three-section gradient mode; after constant-temperature pressure maintaining and gradient pressurization are completed, the temperature of the mold cavity and the final pressure are kept unchanged, the pressure maintaining time is 60-90 s, and catalyst powder particles are fully combined; and after pressure maintaining is finished, two-section type pressure relief is carried out. Through the synergistic effect of uniform pressurization, sufficient exhaust, mild demolding and temperature regulation and control, the catalyst tabletting forming rate is increased to be larger than or equal to 98% from traditional smaller than or equal to 85%, and material waste is greatly reduced.

Description

Technical Field

[0002] This invention relates to the field of catalyst preparation technology, and in particular to a tableting method and mold for improving catalyst forming rate. Background Technology

[0004] Catalyst tableting is a crucial preparation step in industrial catalysis. Tableting allows catalyst powder to be formed into particles with specific shapes, sizes, and mechanical strengths to meet the requirements of reactor loading and catalytic reactions. Traditional tableting molds often employ a rigidly connected upper and lower punch and a fixed mold cavity structure. The tableting method involves a single pressure application and forming process, which has the following core drawbacks:

[0005] 1. Uneven material stress: The coaxiality error between the upper and lower die punches and the die cavity, and the rigid impact during the pressure transmission process, result in a large difference in pressure between the edge and center of the material in the die cavity. After molding, the density of the pressed tablets is uneven and cracks are prone to occur.

[0006] 2. High demolding breakage rate: The inner wall of the mold cavity is smooth, and there is an adsorption force between the tablet and the mold cavity. When rigidly demolded, the tablet is prone to edge chipping and surface peeling.

[0007] 3. Insufficient venting: One-time pressurization prevents air from being expelled from the material gaps in time, resulting in pores inside the tablet, which reduces mechanical strength and catalytic activity;

[0008] 4. Lack of temperature control: The bonding performance of catalyst powder is related to temperature. When tableting at room temperature, the material has poor flowability and the particles are not tightly bound, which further reduces the molding rate.

[0009] The aforementioned problems result in catalyst formation rates generally below 85% in traditional tableting processes, leading to significant material waste due to breakage and substandard materials, while also affecting the stability of subsequent catalytic reactions. Therefore, there is an urgent need to design a tableting mold and supporting methods that combine uniform pressure transmission, efficient venting, gentle demolding, and temperature control to solve the low formation rate problem of traditional technologies.

[0010] A method for tableting a Cr-based catalyst is disclosed in Chinese patent document CN119386935A. The method includes: (1) preparing Cr-based catalyst powder by co-precipitation; the Cr-based catalyst powder is calcined powder; (2) mixing the Cr-based catalyst powder obtained in step (1), an aqueous solution of auxiliary agent I, and selectively added water to obtain a mixed material; (3) drying, crushing, and sieving the mixed material obtained in step (2), then mixing it with auxiliary agent II and auxiliary agent III, and tableting it to obtain a tablet; (4) calcining the tablets prepared in step (3) to obtain the shaped catalyst. The Cr-based catalyst prepared by this method has no problems such as delamination, transverse cracking, or cap removal, and its physicochemical properties are stable. However, the tableting method of this Cr-based catalyst still uses traditional molds in the tableting process, and the problem of pressure concentration is not solved.

[0011] A molding method, the molded catalyst, and its applications are disclosed in Chinese patent document CN119746938A. The molding method, the molded catalyst, and its applications include the following steps: 1) mixing the supercrosslinked phosphine ligand polymer Rh catalyst with an inert substance, and then slowly adding a liquid adhesive solution during the mixing process to obtain a mixture; 2) drying the obtained mixture to obtain a dried catalyst; 3) thoroughly grinding the dried catalyst, pressing it into tablets using a tablet press, and passing it through a 20-40 mesh sieve to obtain the molded catalyst. The molded catalyst prepared according to the molding method of this invention solves the problem of catalyst swelling, can be used for a long time in a fixed-bed reactor, has virtually no metal loss, and is beneficial for subsequent separation and purification, with better selectivity for linear aldehydes. However, the mold used in the molding method and applications of this supercrosslinked phosphine ligand polymer Rh catalyst lacks anti-slip texture and temperature control.

[0012] A carbon dioxide hydrogenation to methanol catalyst, its molding method, and its uses are disclosed in Chinese patent document CN113842920B. The catalyst includes the following steps: 1) uniformly mixing catalyst powder with a molding aid; 2) particle size pretreatment; 3) pressing the pretreated powder into tablets, followed by calcination. This molding method yields a catalyst with high activity, achieving a CO2 single-pass conversion rate of up to 35%, effectively avoiding the problem of reduced catalyst activity after molding, and also solving the problem of uniformity in the side pressure strength of the molded catalyst. However, this carbon dioxide hydrogenation to methanol catalyst and its molding method and uses utilize a conventional tablet press and do not involve any innovation in the mold cavity structure.

[0013] To address the shortcomings of the existing technology, providing a tableting method and mold to improve the catalyst forming rate is a problem worthy of research. Summary of the Invention

[0015] The purpose of this invention is to overcome the shortcomings of uneven material stress, high demolding breakage rate and lack of temperature control, and to provide a tableting method and mold that improves the catalyst forming rate, achieving the technical effects of uniform pressure, sufficient venting, gentle demolding and temperature control.

[0016] The objective of this invention is achieved through the following technical solution:

[0017] A tableting method for improving catalyst forming rate includes the following steps:

[0018] Step 1: Mold pretreatment, preheating the mold cavity to the preset temperature using the temperature control unit and maintaining a constant temperature; cleaning the inner wall of the inner liner;

[0019] Step 2: Material loading. The catalyst powder is evenly filled into the inner liner of the mold cavity assembly.

[0020] Step 3: Pre-pressurize and vent air. Start the pressure drive mechanism to control the upper die to move downward and expel the air in the material gap.

[0021] Step 4: Gradient pressure molding. After pre-compression, the pressure is increased in a three-stage gradient.

[0022] Step 5: Constant temperature and pressure holding. After the gradient pressurization is completed, maintain the mold cavity temperature and final pressure at a constant time of 60-90 seconds to allow the catalyst powder particles to fully combine.

[0023] Step 6: After elastic demolding and pressure holding, the pressure is released in two stages. The catalyst tableting rate is increased from the traditional ≤85% to ≥98%. There are no obvious pores inside the tablets, no chipping at the edges, and the mechanical strength meets the requirements of industrial applications.

[0024] Optionally, the preset temperature in step one is 30-60℃, and the inner wall of the inner liner is cleaned until the anti-slip texture is free of impurities, which reduces the problems of tablet cracking and uneven density caused by temperature fluctuations or impurities, and further improves the stability of molding quality.

[0025] Optionally, in step two, the material filling height is 70-80% of the mold cavity depth. During the filling process, a vibrator is used to gently vibrate the mold sleeve at a frequency of 50-100Hz to reduce internal air holes and stress concentration caused by uneven filling, thus laying a uniform material foundation for subsequent gradient pressurization.

[0026] Optionally, in step two, the particle size of the catalyst powder is 20-200μm. The catalyst powder is dried before filling, with a drying temperature of 100-120℃ and a drying time of 2-4h. During the filling process, the mold cavity temperature is kept consistent with the preheating temperature to avoid the material absorbing moisture and clumping, improve the bonding force between particles, and extend the service life of the mold.

[0027] Optionally, in step three, the upper die punch applies pre-pressure at a pressure rise rate of 0.5-1 MPa / s, the pre-pressure is 5-8 MPa, and the pre-pressure state is maintained for 10-20s. This significantly reduces the porosity inside the tablet and improves the mechanical strength (compressive strength ≥15 MPa), thus avoiding a decrease in catalytic activity due to residual air.

[0028] Optionally, the three-segment gradients in step four are as follows:

[0029] The first stage involves increasing the pressure to 20-30 MPa at a rate of 1-1.5 MPa / s and maintaining it for 15-25 seconds.

[0030] The second stage involves increasing the pressure to 40-60 MPa at a rate of 0.8-1 MPa / s and maintaining it for 30-40 seconds.

[0031] The third stage increases the pressure to 70-90 MPa at a rate of 0.5-0.8 MPa / s and holds it for 40-60 seconds. This significantly improves the uniformity of the tablet density and eliminates defects such as cracks and delamination, making it suitable for the molding requirements of different types of catalysts, such as molecular sieves and metal oxides.

[0032] Optionally, during the gradient pressurization process in step four, pressure data is collected in real time by pressure sensors of the upper and lower die punches. When the pressure difference exceeds 1MPa, the pressure difference is automatically compensated by the deformation of the elastic buffer to ensure that the pressure deviation between the upper and lower surfaces of the material in the die cavity is ≤0.5MPa, thus avoiding local damage or insufficient mechanical strength caused by uneven pressure.

[0033] Optionally, the two-stage pressure relief in step six are as follows:

[0034] The first stage involves depressurizing to 30-40 MPa at a rate of 1-1.5 MPa / s and maintaining this pressure for 10-15 seconds.

[0035] The second stage involves depressurizing to atmospheric pressure at a rate of 0.8-1 MPa / s;

[0036] After the pressure is released, the lower die punch pushes the catalyst tablet upwards, and the upper die punch simultaneously resets upwards to complete the demolding. The demolding breakage rate is reduced to ≤1%, and there are no chips or peeling on the tablet edges, ensuring the integrity of the formed catalyst.

[0037] Optionally, in step six, during the elastic demolding process, the guide buffer spring works in conjunction with the upper and lower elastic buffer components to control the upper die punch reset rate and the lower die punch ejection rate to both be 5-10 mm / s, further reducing the risk of demolding breakage, ensuring that the pressed tablet has a regular shape and a good surface, and improving the yield of qualified products.

[0038] A tableting mold for improving catalyst forming rate includes an upper mold assembly, a lower mold assembly, a mold cavity assembly, an elastic buffer guide mechanism, and a temperature control unit;

[0039] The upper mold assembly includes an upper mold punch, an upper mold base, and an upper elastic buffer. The upper mold punch is fixed to the bottom of the upper mold base, and the upper elastic buffer is sleeved on the outside of the upper mold punch, with its two ends abutting against the top of the upper mold base and the mold cavity assembly, respectively.

[0040] The lower die assembly includes a lower die punch, a lower die base, and a lower elastic buffer. The lower die punch is fixed to the top of the lower die base, and the lower elastic buffer is sleeved on the outside of the lower die punch, with both ends abutting against the bottom of the lower die base and the die cavity assembly, respectively.

[0041] The mold cavity assembly includes a mold sleeve and an inner liner. The inner liner is embedded inside the mold sleeve. The inner wall of the inner liner has a gradient anti-slip texture. The depth of the anti-slip texture gradually decreases from both ends of the mold cavity to the middle, with a depth of 0.1-0.2 mm at both ends and 0.03-0.05 mm in the middle. An annular temperature control channel is opened inside the side wall of the mold sleeve. The inlet and outlet of the temperature control channel are connected to an external temperature control device.

[0042] The elastic buffer guide mechanism includes guide posts and guide sleeves. The guide posts are symmetrically arranged at the four corners of the bottom of the upper mold base, and the guide sleeves are correspondingly arranged at the four corners of the top of the lower mold base. The guide posts and guide sleeves are fitted with a clearance of 0.01-0.02mm, and a guide buffer spring is sleeved on the outside of the guide posts.

[0043] The temperature control unit includes a temperature sensor and a temperature control valve. The temperature sensor is embedded in the side wall of the inner bushing and is used to monitor the temperature of the mold cavity in real time. The temperature control valve is connected in series with the temperature control channel and is used to adjust the flow rate of the temperature control medium.

[0044] Positive and beneficial effects: 1. The tableting method and mold forming rate of the catalyst are significantly improved: Through the synergistic effect of uniform pressure, full degassing, gentle demolding and temperature control, the catalyst tablet forming rate is increased from the traditional ≤85% to ≥98%, greatly reducing material waste;

[0045] 2. The tableting method and mold forming quality of this catalyst forming method are excellent: the tablet density variation coefficient is ≤2%, there are no obvious pores inside, no chipping at the edges, and the mechanical strength (compressive strength ≥15MPa) meets the requirements of industrial applications;

[0046] 3. The tableting method and mold for improving catalyst forming rate are highly durable: the inner liner is made of silicon nitride ceramic material, combined with DLC-coated die punches, which have excellent wear resistance and a service life that is 3-5 times longer than that of traditional molds;

[0047] 4. The tableting method and mold for improving catalyst forming rate have wide adaptability: they are suitable for various catalyst powders such as molecular sieves, metal oxides, and composite oxides, and can be adapted to the forming requirements of different materials by adjusting temperature and pressure parameters;

[0048] 5. The tableting method and mold for improving catalyst forming rate are simple to operate: the mold structure is compact, the tableting process is clear, it can be directly adapted to existing tableting equipment, no large-scale modification is required, and it is easy to promote industrialization. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the method of the present invention;

[0051] Figure 2 This is a schematic diagram of the structure of the mold of the present invention. Detailed Implementation

[0053] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0054] Example 1

[0055] like Figure 1 As shown, a tableting method and mold for improving catalyst forming rate includes the following steps:

[0056] Step 1: Mold pretreatment, preheating the mold cavity to the preset temperature using the temperature control unit and maintaining a constant temperature; cleaning the inner wall of the inner liner;

[0057] Step 2: Material loading. The catalyst powder is evenly filled into the inner liner of the mold cavity assembly.

[0058] Step 3: Pre-pressurize and vent air. Start the pressure drive mechanism to control the upper die to move downward and expel the air in the material gap.

[0059] Step 4: Gradient pressure molding. After pre-compression, the pressure is increased in a three-stage gradient.

[0060] Step 5: Constant temperature and pressure holding. After the gradient pressurization is completed, maintain the mold cavity temperature and final pressure at a constant time of 60-90 seconds to allow the catalyst powder particles to fully combine.

[0061] Step Six: Elastic Demolding. After the pressure holding period, the pressure is released in two stages. The six-step tableting process of "mold pretreatment → material loading → pre-pressure venting → gradient pressure molding → constant temperature pressure holding → elastic demolding" is adopted to achieve uniform pressure transmission, sufficient air discharge between materials, tight bonding of catalyst particles, and gentle and impact-free demolding process. This solves the core problems of uneven force, insufficient venting, and demolding damage in traditional processes. The catalyst tableting rate is increased from ≤85% to ≥98%. There are no obvious pores inside the tablets, no chipping at the edges, and the mechanical strength meets the requirements of industrial applications.

[0062] The preset temperature in step one is 30-60℃. The inner wall of the inner liner is cleaned until the anti-slip texture is free of impurities. By precisely controlling the temperature, the bonding performance and flowability of the catalyst powder are optimized, avoiding material slippage or pressure transmission obstruction caused by the blockage of the anti-slip texture. This ensures the consistency of the internal environment of the mold cavity, promotes the tight bonding of catalyst particles, reduces problems such as tablet cracks and uneven density caused by temperature fluctuations or impurities, and further improves the stability of molding quality.

[0063] In step two, the material filling height is 70-80% of the mold cavity depth. During the filling process, a vibrator is used to gently vibrate the mold sleeve at a frequency of 50-100Hz, so that the filling material is evenly distributed, avoiding pressure transmission imbalance caused by excessive or insufficient filling. The vibration eliminates local voids formed by material accumulation, ensuring that the initial material distribution in the mold cavity is uniform, reducing the coefficient of variation of tablet density (≤2%), and reducing internal porosity and stress concentration caused by uneven filling, laying a uniform material foundation for subsequent gradient pressurization.

[0064] In step two, the catalyst powder has a particle size of 20-200μm. The catalyst powder is dried before filling at a temperature of 100-120℃ for 2-4 hours. During filling, the mold cavity temperature is kept consistent with the preheating temperature to prevent the material from absorbing moisture and clumping. The drying process prevents the material from absorbing moisture and clumping. The appropriate particle size range ensures the material's flowability and mold cavity compatibility. Constant temperature filling prevents the material from reabsorbing moisture due to temperature changes, eliminates uneven filling and pressure molding defects caused by clumping material, ensures consistent tablet density, improves the bonding force between particles, and extends the service life of the mold.

[0065] In step three, the upper die punch applies pre-pressure at a pressure rise rate of 0.5-1 MPa / s, with a pre-pressure of 5-8 MPa, and maintains the pre-pressure state for 10-20 seconds. The low-pressure, short-time pre-pressure mode can fully expel air from the gaps between materials, preventing air from being trapped and forming pores during subsequent high-pressure molding. At the same time, it initially compacts the material, providing a stable foundation for gradient pressurization. The porosity inside the tablet is significantly reduced, and the mechanical strength (compressive strength ≥15 MPa) is improved, avoiding a decrease in catalytic activity due to residual air.

[0066] The three gradients in step four are as follows:

[0067] The first stage involves increasing the pressure to 20-30 MPa at a rate of 1-1.5 MPa / s and maintaining it for 15-25 seconds.

[0068] The second stage involves increasing the pressure to 40-60 MPa at a rate of 0.8-1 MPa / s and maintaining it for 30-40 seconds.

[0069] The third stage increases the pressure to 70-90 MPa at a rate of 0.5-0.8 MPa / s and holds it for 40-60 seconds. During the pressurization process, the deformation compensation of the upper and lower elastic buffers ensures uniform material pressure in the mold cavity. The pressure is gradually increased from low to high, allowing the material particles to rearrange and combine in an orderly manner under different pressure levels. This avoids particle breakage or stress concentration caused by one-time high pressure. The elastic buffers ensure uniform pressure transmission in the mold cavity, significantly improving the uniformity of tablet density and eliminating defects such as cracks and delamination. This is suitable for the molding requirements of different types of catalysts such as molecular sieves and metal oxides.

[0070] In step four, during the gradient pressurization process, pressure data is collected in real time by pressure sensors on the upper and lower die punches. When the pressure difference exceeds 1MPa, the pressure difference is automatically compensated by the deformation of the elastic buffer, so that the pressure deviation between the upper and lower surfaces of the material in the die cavity is ≤0.5MPa. The pressure deviation is monitored and compensated in real time, which solves the problem of pressure difference between the material edge and center caused by coaxiality error and rigid impact in traditional molds. The coefficient of variation of the tablet density is ≤2%, the molding quality stability is greatly improved, and local damage or insufficient mechanical strength caused by uneven pressure is avoided.

[0071] The two-stage pressure relief in step six are as follows:

[0072] The first stage involves depressurizing to 30-40 MPa at a rate of 1-1.5 MPa / s and maintaining this pressure for 10-15 seconds.

[0073] The second stage involves depressurizing to atmospheric pressure at a rate of 0.8-1 MPa / s;

[0074] After the pressure is released, the lower die punch pushes the catalyst tablet upwards, and the upper die punch simultaneously resets upwards to complete the demolding. The staged pressure release avoids uneven release of internal stress in the tablet caused by a sudden drop in pressure. The slow pressure release process allows the tablet to gradually adapt to pressure changes, reducing the demolding breakage rate to ≤1%. There are no chips or peeling on the tablet edges, ensuring the integrity of the formed catalyst.

[0075] In step six, during the elastic demolding process, the guide buffer spring works in conjunction with the upper and lower elastic buffer components to control the upper die punch reset rate and the lower die punch ejection rate to both be 5-10 mm / s. This prevents the demolding rate from being too fast and causing damage to the pressed tablet. By steadily controlling the demolding rate, the impact stress generated by excessively fast demolding is prevented from causing damage to the pressed tablet. The synergistic buffer structure absorbs the rigid impact during the demolding process, further reducing the risk of demolding damage, ensuring that the pressed tablet has a regular shape and a good surface, and improving the yield of qualified products.

[0076] like Figure 2 As shown, a tableting mold for improving catalyst forming rate includes an upper mold assembly, a lower mold assembly, a mold cavity assembly, an elastic buffer guide mechanism, and a temperature control unit.

[0077] The upper mold assembly includes an upper mold punch, an upper mold base, and an upper elastic buffer. The upper mold punch is fixed to the bottom of the upper mold base, and the upper elastic buffer is sleeved on the outside of the upper mold punch, with its two ends abutting against the top of the upper mold base and the mold cavity assembly, respectively.

[0078] The lower die assembly includes a lower die punch, a lower die base, and a lower elastic buffer. The lower die punch is fixed to the top of the lower die base, and the lower elastic buffer is sleeved on the outside of the lower die punch, with its two ends abutting against the bottom of the lower die base and the die cavity assembly, respectively.

[0079] The mold cavity assembly includes a mold sleeve and an inner liner. The inner liner is embedded inside the mold sleeve. The inner wall of the inner liner has a gradient anti-slip texture. The depth of the anti-slip texture gradually decreases from both ends of the mold cavity to the middle, with a depth of 0.1-0.2 mm at both ends and 0.03-0.05 mm in the middle. An annular temperature control channel is opened inside the side wall of the mold sleeve. The inlet and outlet of the temperature control channel are connected to an external temperature control device.

[0080] The elastic buffer guide mechanism includes guide posts and guide sleeves. The guide posts are symmetrically arranged at the four corners of the bottom of the upper mold base, and the guide sleeves are correspondingly arranged at the four corners of the top of the lower mold base. The guide posts and guide sleeves are fitted with a clearance of 0.01-0.02mm, and a guide buffer spring is sleeved on the outside of the guide posts.

[0081] The temperature control unit includes a temperature sensor and a temperature control valve. The temperature sensor is embedded in the side wall of the inner bushing for real-time monitoring of the mold cavity temperature. The temperature control valve is connected in series with the temperature control channel to regulate the flow rate of the temperature control medium. Both the upper and lower elastic buffer components adopt a combined buffer structure, including a rubber buffer pad, a disc spring, and a pressure sensor stacked in sequence. The hardness of the rubber buffer pad is Shore 60-70A, the elastic coefficient of the disc spring is 50-80N / mm, and the pressure sensor has a measurement range of 0-50MPa and an accuracy of ±0.1MPa.

[0082] The inner liner is made of silicon nitride ceramic material and the surface is polished (roughness Ra≤0.2μm); the gradient anti-slip texture is a spiral groove with a groove pitch of 2-5mm, and the inner wall of the groove is rounded (rounded radius 0.02-0.03mm).

[0083] The temperature control channel has an annular cross-section (3-5mm wide, 2-3mm high) and is spirally distributed along the side wall of the mold sleeve with a spiral angle of 30-45°. The temperature control medium is heat transfer oil or cooling water, and the mold cavity temperature control range is 20-80℃ with a temperature control accuracy of ±0.5℃.

[0084] Both the upper and lower die punches have arc-shaped transition edges (transition radius 1-2mm) on their end faces, and the surface of the punch is coated with diamond-like carbon (DLC) coating with a thickness of 2-5μm and a hardness ≥2000HV.

[0085] Example 2

[0086] Molecular sieve catalyst tableting

[0087] 1. Mold parameters: Inner bushing inner diameter 10mm, depth 20mm; anti-slip texture depth at both ends 0.15mm, middle depth 0.04mm; temperature control channel circulates 45℃ heat transfer oil;

[0088] 2. Material parameters: Molecular sieve catalyst powder with a particle size of 50-150μm, drying temperature of 110℃, and drying time of 3h;

[0089] Tableting method steps:

[0090] 1. Mold pretreatment: Preheat the mold cavity to 45℃ and maintain the temperature; clean the anti-slip texture on the inner wall of the inner liner;

[0091] 2. Material filling: Fill the mold cavity with the dried molecular sieve powder to a height of 15mm, and start the vibrator (frequency 80Hz) to vibrate gently for 5s;

[0092] 3. Pre-pressure exhaust: Increase the pressure to 6MPa at a rate of 0.8MPa / s and maintain it for 15s;

[0093] 4. Gradient pressurization: In the first stage, the pressure is increased to 25 MPa at 1.2 MPa / s and held for 20 s; in the second stage, the pressure is increased to 50 MPa at 0.9 MPa / s and held for 35 s; in the third stage, the pressure is increased to 80 MPa at 0.6 MPa / s and held for 50 s.

[0094] 5. Constant temperature and pressure holding: Maintain 45℃ and 80MPa for 70s;

[0095] 6. Elastic demolding: In the first stage, the pressure is released from 1.2MPa / s to 35MPa and held for 12s; in the second stage, the pressure is released from 0.9MPa / s to normal pressure; the lower die punch ejects at a rate of 8mm / s, and the upper die punch resets synchronously.

[0096] Implementation results:

[0097] The tableting rate is 98.5%, the tablet diameter is 10mm, the thickness is 6mm, the density variation coefficient is 1.8%, the compressive strength is 18MPa, and the demolding breakage rate is 0.8%.

[0098] Example 3

[0099] Metal oxide catalyst tableting

[0100] 1. Mold parameters: Inner bushing inner diameter 12mm, depth 25mm; anti-slip texture depth at both ends 0.18mm, middle depth 0.05mm; temperature control channel circulates 35℃ heat transfer oil;

[0101] 2. Material parameters: Metal oxide catalyst powder with a particle size of 30-120μm, drying temperature of 105℃, and drying time of 2.5h;

[0102] Tableting method adjustment:

[0103] Pre-compression pressure 7MPa, gradient pressurization final pressure 75MPa, constant temperature pressure holding temperature 35℃;

[0104] Implementation results:

[0105] The tableting rate is 99.2%, the density variation coefficient is 1.5%, the compressive strength is 20MPa, and the demolding breakage rate is 0.5%, which meets the requirements for filling and catalytic reaction in chemical reactors.

[0106] This invention fundamentally solves the core pain points of traditional tableting molds and methods by using elastic buffering, anti-slip texture, temperature control and guiding design of the mold structure, combined with process optimization of pre-pressure venting, gradient pressurization, constant temperature pressure holding and elastic demolding, to achieve high molding rate and high quality of catalyst tablets, and has outstanding innovation and industrial applicability.

[0107] The above is only used to illustrate the technical solution of the present invention and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A tableting method for improving the molding rate of a catalyst, characterized by, The method comprises the following steps: Step 1: mold pretreatment, preheat the mold cavity temperature to the preset temperature through the temperature control unit, and keep constant temperature; clean the inner wall of the inner sleeve; Step 2: material loading, uniformly fill the catalyst powder into the inner sleeve of the mold cavity assembly; Step 3: pre-pressing and air exhausting, start the pressure driving mechanism, control the upper die to move downward, and exhaust the air in the material gap; Step 4: gradient pressure forming, after pre-pressing, pressurize in three stages; Step 5: constant temperature and pressure maintaining, after gradient pressure forming, maintain the mold cavity temperature and the final pressure unchanged, and the pressure maintaining time is 60-90s, so that the catalyst powder particles are fully combined; Step 6: elastic demolding, after the pressure maintaining is completed, depressurize in two stages.

2. The tabletting method for improving the forming rate of a catalyst according to claim 1, characterized by: The preset temperature in step 1 is 30-60℃, and the inner wall of the inner sleeve is cleaned to the state that the anti-skid texture is free of impurity residues.

3. The tabletting method for improving the forming rate of a catalyst according to claim 1, characterized by: In step 2, the height of material loading is 70-80% of the depth of the mold cavity, and a vibrator is used to vibrate the mold sleeve during the loading process, and the vibration frequency is 50-100Hz.

4. The tabletting method for improving the forming rate of a catalyst according to Claim 1, characterized by: In step 2, the particle size of the catalyst powder is 20-200μm, and the catalyst powder is dried before loading, the drying temperature is 100-120℃, the drying time is 2-4h, and the temperature of the mold cavity during the loading process is kept consistent with the preheating temperature.

5. The tabletting method of claim 1, wherein the tabletting method is characterized by: In step 3, the upper die is applied with a pre-pressure at a pressure rising rate of 0.5-1MPa / s, the pre-pressure is 5-8MPa, and the pre-pressure state is maintained for 10-20s.

6. The tabletting method of claim 1, wherein, In step 4, the three-stage gradient is as follows: In the first stage, the pressure is raised to 20-30MPa at a rate of 1-1.5MPa / s, and maintained for 15-25s; In the second stage, the pressure is raised to 40-60MPa at a rate of 0.8-1MPa / s, and maintained for 30-40s; In the third stage, the pressure is raised to 70-90MPa at a rate of 0.5-0.8MPa / s, and maintained for 40-60s.

7. The tabletting method of claim 1, wherein the tabletting method is characterized by: In step 4, during the gradient pressure forming process, the pressure sensor of the upper and lower dies collects pressure data in real time, when the pressure difference exceeds 1MPa, the pressure difference is automatically compensated by the deformation of the elastic buffer, so that the pressure deviation of the upper and lower surfaces of the material in the mold cavity is ≤0.5MPa.

8. The tabletting method of claim 1, wherein the tabletting method is characterized by, In step 6, the two-stage depressurization is as follows: In the first stage, the pressure is released to 30-40MPa at a rate of 1-1.5MPa / s, and maintained for 10-15s; In the second stage, the pressure is released to normal pressure at a rate of 0.8-1MPa / s; After the depressurization is completed, the lower die is ejected upward, the upper die is reset upward synchronously, and the demolding is completed.

9. The tabletting method of claim 1, wherein the tabletting method is characterized by, In step 6, during the elastic demolding process, the guiding buffer spring and the upper and lower elastic buffers cooperate to control the reset rate of the upper die and the ejection rate of the lower die, both of which are 5-10mm / s.

10. The tablet press die for improving the forming rate of a catalyst according to any one of claims 1 to 9, characterized by: The device comprises an upper die assembly, a lower die assembly, a mold cavity assembly, an elastic buffer guiding mechanism and a temperature control unit. The upper die assembly comprises an upper die, an upper die seat and an upper elastic buffer, the upper die is fixed to the bottom of the upper die seat, the upper elastic buffer is sleeved outside the upper die, and the two ends are respectively in abutment with the upper die seat and the top of the mold cavity assembly. The lower die assembly comprises a lower die punch, a lower die seat and a lower elastic buffer, the lower die punch is fixed on the top of the lower die seat, the lower elastic buffer is sleeved outside the lower die punch, and the two ends are respectively in abutment with the lower die seat and the bottom of the mold cavity assembly; The mold cavity assembly comprises a mold sleeve and an inner sleeve, the inner sleeve is embedded in the mold sleeve, the inner wall of the inner sleeve is provided with a gradually changing anti-skid texture, the depth of the anti-skid texture gradually decreases from both ends to the middle part, the depth of both ends is 0.1-0.2mm, and the depth of the middle part is 0.03-0.05mm; a ring-shaped temperature control channel is arranged in the inner wall of the mold sleeve, and the inlet and outlet of the temperature control channel are respectively connected with external temperature control equipment; The elastic buffer guiding mechanism comprises guiding columns and guiding sleeves, the guiding columns are symmetrically arranged at the bottom of the upper die seat, the guiding sleeves are correspondingly arranged at the top of the lower die seat, the guiding columns and the guiding sleeves are gap-fitted, the fitting gap is 0.01-0.02mm, and the guiding columns are sleeved with guiding buffer springs outside; The temperature control unit comprises a temperature sensor and a temperature control valve, the temperature sensor is embedded in the side wall of the inner sleeve for real-time monitoring of the temperature of the mold cavity, and the temperature control valve is connected with the temperature control channel in series for adjusting the flow of the temperature control medium.

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