Preparation method of acrylic acid catalyst partner

Abstract

The invention belongs to the technical field of chemical catalyst auxiliary materials, and particularly relates to a manufacturing method of an acrylic acid catalyst partner, the acrylic acid catalyst partner comprises the following raw materials: selected kaolin and a pore-forming agent, a rolling forming process is adopted, the uniformly mixed selected kaolin and pore-forming agent are made into spheres with the diameter of 5mm-5.5 mm, the bulk specific gravity is 1.1 g / ml-1. 15 g / ml, the strength is greater than or equal to 400N, and the water absorption is less than or equal to 5%. According to the preparation method of the acrylic acid catalyst partner, by selecting raw materials for mixing and optimizing the proportion of the mixture, the prepared partner porcelain ball has the bulk density, size and strength similar to those of the catalyst, and through multiple times of experimental optimization, the determined proportion can enable the porcelain ball to achieve the bulk density extremely similar to that of the catalyst after being fired; the error is controlled within an extremely small range, and further, the partner porcelain balls can be uniformly mixed with the catalyst, so that the layering phenomenon caused by density difference is avoided, and the requirements of diluting the catalyst and uniformly filling a bed layer are met.

Description

Technical Field

[0001] The invention relates to the technical field of chemical catalyst auxiliary materials, in particular to a method for preparing an acrylic acid catalyst partner. Background Art

[0002] Catalyst loading is a critical step in many chemical production processes, such as the two-step oxidation of propylene to acrylic acid. To ensure uniformity in the bed, the catalyst must be diluted. Uneven catalyst loading can lead to uneven distribution of the reactant fluids within the bed, compromising reaction efficiency and selectivity. This can cause localized over- or underreaction, resulting in increased byproducts and reduced yields of the target product.

[0003] Currently, in the existing technology, the two-step oxidation of propylene to acrylic acid is the mainstream process for producing acrylic acid. The catalyst and other fillers are still mostly imported from Japan and other countries. During the catalyst loading process, the catalyst needs to be diluted. Therefore, a companion ceramic ball with a bulk density, size, and strength index similar to that of the catalyst needs to be added to the catalyst to achieve the goal of uniformly diluting the catalyst and uniformly loading the bed. In view of this, we propose a method for preparing an acrylic acid catalyst companion. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the shortcomings and problems of the prior art, the present invention provides a method for preparing an acrylic acid catalyst partner, which produces a partner porcelain ball that meets the catalyst dilution requirements by selecting raw materials, optimizing the ratio and forming and firing processes.

[0006] (2) Technical solution

[0007] To achieve the above object, the present invention provides a method for preparing an acrylic acid catalyst partner, comprising the following raw materials: selected kaolin and a pore-forming agent. The uniformly mixed selected kaolin and the pore-forming agent are formed into spheres with a diameter of 5 mm to 5.5 mm by a rolling molding process. The spheres have a bulk density of 1.1 g / ml to 1.15 g / ml, a strength of 400 N or higher, and a water absorption rate of 5% or less.

[0008] Preferably, the mass ratio of the selected kaolin and the pore-forming agent is in the range of 70:30-85:15, and the volume ratio of the selected kaolin and the pore-forming agent is in the range of 60:40-75:25. When the mass ratio is in the range of 70:30-85:15, after the subsequent molding and firing processes, the performance indicators such as strength, bulk density and water absorption can be better balanced. The difference in volume ratio will affect the distribution and mixing uniformity of the raw materials in the mixing equipment, and thus affect the performance of the final product. When the mass ratio is 70:30, the pore-forming agent is relatively more, which may produce Creating more voids makes it easier to reduce the bulk density, and attention should be paid to the effect on strength during the firing process. At a ratio of 85:15, the proportion of selected kaolin is relatively large, and the strength after firing may be higher. It should be noted that the pore-forming agent can still create enough voids to meet the bulk density requirements. The determined ratio can make the porcelain balls reach a bulk density that is very similar to that of the catalyst after firing, and the error is controlled within an extremely small range. The companion porcelain balls can be evenly mixed with the catalyst to avoid stratification due to density differences, and meet the requirements of catalyst dilution and uniform loading of the bed.

[0009] Preferably, the method comprises the following steps:

[0010] S1. Mixing raw materials: Selected kaolin is selected as the main raw material, and an appropriate amount of pore-forming agent is added. The selected kaolin and pore-forming agent are weighed according to a predetermined ratio and placed in a mixing device for thorough mixing.

[0011] S2, molding, put the mixed raw materials into the rolling molding equipment for rolling molding, and the mixed raw materials are made into spheres with a diameter of 5mm-5.5mm.

[0012] S3. Firing: Place the formed sphere in a high-temperature kiln and fire it at a temperature of 1200°C-1400°C to ensure that the sphere can be fully porcelainized and to achieve the purpose of reducing water absorption, increasing strength and creating internal voids.

[0013] Firing reduces the water absorption rate of the companion porcelain balls. This low water absorption characteristic enables them to effectively resist moisture erosion during use. In the acrylic acid production environment, there may be a certain amount of humidity or water vapor. The porcelain balls with low water absorption will not expand, deform or lose strength due to absorbing moisture, thereby ensuring the structural integrity of the bed, increasing its strength, and improving its service life and stability.

[0014] S4. Screening after testing: The fired companion porcelain balls are subjected to quality testing, including bulk density, strength, water absorption and other indicators, to screen out the companion porcelain balls that meet the requirements and ensure that they have similar performance indicators to the catalyst.

[0015] Preferably, the mixing equipment in step S1 is a planetary mixer made of corrosion-resistant materials such as stainless steel. For mixing the selected kaolin and pore-forming agent, the rotational speed is between 10 rpm and 100 rpm, and the mixing time is between 10 minutes and 60 minutes. For powdered selected kaolin and pore-forming agent, the planetary mixer can achieve efficient and uniform mixing by adjusting parameters such as the rotational speed and mixing time. For paste-like raw materials, the parameters can also be appropriately adjusted to achieve thorough mixing within the container. Compared to traditional stirring equipment, the planetary mixer improves the uniformity of raw material mixing by 20% to 50% within the same time.

[0016] Preferably, the rolling molding equipment in step S2 produces spheres with a diameter of 5mm-5.5mm, the roller diameter is between 20cm-50cm, and the length is between 50cm-100cm. The above-mentioned size design can provide sufficient space for the raw materials to roll and mold. For the production of spheres with a diameter of 5mm-5.5mm, the running time is between 10 minutes and 60 minutes. When the running time is between 30 minutes and 60 minutes, the spheres can be fully formed, the size meets the requirements, and the product quality is high.

[0017] Preferably, the main component of the kaolin is kaolinite, whose chemical formula is Al2Si2O5(OH)4, and the chemical reaction equation of high temperature firing is: As the temperature rises further, a ceramic structure is eventually formed, which helps increase strength and reduce water absorption.

[0018] Preferably, the pore-forming agent is ammonium bicarbonate NH4HCO3, which decomposes during the firing process to produce gas, thereby creating voids inside the sphere. The chemical formula is:

[0019] Preferably, the firing process in step S3 includes firing in a key temperature range and a constant temperature holding stage. After firing in the key temperature range, the dehydration reaction of kaolinite is basically completed, the structure is rearranged, and a new crystal structure is formed, which greatly increases the strength of the green body. At the same time, the decomposition reaction of the pore-forming agent is basically completed, and the generated gas forms a stable pore structure inside the green body, thereby achieving the purpose of reducing the stacking weight. The color of the green body changes further and eventually presents a white or grayish white ceramic color. In order to ensure that the green body is fully porcelainized, it is necessary to maintain a constant temperature at a high temperature of 1200°C-1400°C for a certain period of time. During the constant temperature process, the chemical reactions and structural changes inside the green body are fully carried out, the crystal structure is continuously improved, the pore structure is more uniform and stable, and the strength and other performance indicators reach the best state.

[0020] Preferably, the cooling phase of the firing in step S3 utilizes natural cooling or a controlled cooling rate method. During natural cooling, the green body begins cooling from approximately 1400°C. The temperature drop may be rapid in the first few hours, and the rate of cooling gradually slows as the green body temperature approaches ambient temperature. Natural cooling does not require additional equipment to control the cooling process and is relatively simple to operate. Controlling the cooling rate involves equipping the kiln with a cooling fan and a temperature sensor. At the start of cooling, the temperature sensor monitors the temperature inside the kiln and in the green body in real time. While controlling the cooling rate requires relatively complex equipment and operation, it can produce a more stable and reliable acrylic acid catalyst partner.

[0021] Preferably, in the step S4, the post-test screening stage adopts a strength test device (such as a universal material testing machine) to carry out a strength test on the acrylic acid catalyst partner, and the strength test device is followed by water absorption test and bulk specific gravity detection. The spheroid is placed in a fixture of the testing device, and pressure is applied at a stable loading rate until the spheroid breaks, and the maximum pressure value at this time is recorded as the strength of the spheroid. A certain number of samples should be extracted from each batch for testing. If the test result shows that the strength is lower than 400N, the product strength is judged to be unqualified. In the water absorption test, the mass of the dried spheroid is first weighed and recorded as m1. The spheroid is then completely immersed in water and kept for a certain period of time (such as 24 hours) to allow the spheroid to fully absorb water. After taking out the spheroid, the surface excess water is gently wiped with a wet cloth and the mass is weighed again and recorded as m2. According to the formula: Calculate the water absorption rate. Also test according to a certain sampling ratio. If the calculated water absorption rate is greater than 5%, the water absorption rate of the product is judged to be unqualified. In the bulk specific gravity test, a measuring cylinder (volume V) is used. Place the container on a horizontal table and slowly pour the acrylic acid catalyst partner sample into the container. Try to avoid impact and shaking of the sample to allow the sample to accumulate naturally. When the sample accumulates to near the top of the container, use a ruler or other flattening tool to scrape the sample surface to ensure that the sample surface is flat. Then weigh the total mass M of the container and sample. According to the formula (m0 is the container mass) Calculate the bulk density. Take a certain number of samples from each batch and measure them. If the calculated result is not within the range of 1.1g / ml-1.15g / ml, the product is considered unqualified for bulk density.

[0022] The present invention provides a method for preparing an acrylic acid catalyst partner. It has the following beneficial effects:

[0023] (1) The preparation method of the acrylic acid catalyst companion is to select raw materials and optimize the ratio, and the prepared companion porcelain balls have a bulk density, size and strength similar to that of the catalyst. After multiple experimental optimizations, the determined ratio can enable the porcelain balls to reach a bulk density very similar to that of the catalyst after firing, and the error is controlled within an extremely small range. The companion porcelain balls can be evenly mixed with the catalyst to avoid stratification due to density differences, and meet the requirements of catalyst dilution and uniform loading bed.

[0024] (2) The preparation method of the acrylic acid catalyst partner reduces the water absorption rate of the partner porcelain ball through a high-temperature firing process. This low water absorption rate characteristic enables it to effectively resist the erosion of water during use. In the acrylic acid production environment, there may be a certain amount of humidity or water vapor. The porcelain ball with low water absorption rate will not expand, deform or reduce strength due to the absorption of water, thereby ensuring the structural integrity of the bed layer, increasing the strength, and improving its service life and stability.

[0025] (3) The preparation method of the acrylic acid catalyst partner is simple and easy, with low cost. During the raw material mixing process, the mixing operation of the selected kaolin and the pore-forming agent is easy to implement and does not require complex equipment and technology. The rolling molding process is mature and can quickly and efficiently form the mixed raw materials into spherical blanks, and the molding equipment cost is low. Although high-temperature firing requires a certain amount of energy consumption, due to the relatively mature process, large-scale production can be achieved under reasonable control of the firing temperature and time, which is conducive to reducing the production cost of acrylic acid and improving production efficiency. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1:

[0028] The invention provides a preparation method of an acrylic acid catalyst partner, which comprises the following raw materials: selected kaolin and a pore-forming agent, wherein the mass ratio of the selected kaolin to the pore-forming agent is 75:30.

[0029] A method for preparing an acrylic acid catalyst partner comprises the following steps:

[0030] S1. Select carefully selected kaolin and pore-forming agent in a mass ratio of 75:30, mix the kaolin and pore-forming agent evenly according to the above ratio, and ensure that the two are fully integrated.

[0031] S2. Roll the mixture in S1 into spheres with a diameter of 5-5.5 mm.

[0032] S3, firing the sphere formed in S2 at a high temperature of 1200-1400℃ to make it porcelain, reduce water absorption and increase strength. At the same time, the pore-forming agent creates voids inside the sphere to reduce the bulk weight.

[0033] S4. Perform performance tests on the fired catalyst partner to ensure that its bulk density is 1.1-1.15 g / ml, its strength is ≥400 N, and its water absorption rate is ≤5%.

[0034] The main component of kaolin in step S1 is kaolinite, whose chemical formula is Al2Si2O5(OH)4, and the chemical reaction equation of high temperature firing is: As the temperature rises further, a ceramic structure is eventually formed, which helps to increase strength and reduce water absorption. The pore-forming agent is ammonium bicarbonate NH4HCO3, which decomposes during the firing process to produce gas, thereby creating gaps inside the sphere. The chemical formula is: The mixing equipment is a planetary mixer, made of corrosion-resistant materials such as stainless steel. For mixing selected kaolin and pore-forming agents, the speed ranges from 10 to 100 rpm, and the mixing time ranges from 10 to 60 minutes. For powdered selected kaolin and pore-forming agents, the planetary mixer can achieve efficient and uniform mixing by adjusting parameters such as speed and mixing time. For paste-like raw materials, appropriate parameter adjustments can also ensure thorough mixing within the container. Compared to traditional mixing equipment, the planetary mixer improves the uniformity of raw material mixing by 20% to 50% within the same timeframe.

[0035] Furthermore, in step S2, the rolling forming equipment produces spheres with a diameter of 5 mm to 5.5 mm. The diameter of the roller is between 20 cm and 50 cm, and the length is between 50 cm and 100 cm. The above-mentioned size design can provide sufficient space for the raw materials to be rolled and formed. For the production of spheres with a diameter of 5 mm to 5.5 mm, the operation time is between 10 minutes and 60 minutes. When the operation time is between 30 minutes and 60 minutes, the spheres can be fully formed, the size meets the requirements, and the product quality is high.

[0036] Furthermore, the firing process in step S3 includes firing in a key temperature range and a constant temperature holding stage. After firing in the key temperature range, the dehydration reaction of kaolinite is basically completed, the structure is rearranged, and a new crystal structure is formed, which greatly increases the strength of the green body. At the same time, the decomposition reaction of the pore-forming agent is basically completed, and the generated gas forms a stable pore structure inside the green body, thereby achieving the purpose of reducing the bulk weight. The color of the green body changes further, and finally presents a white or off-white ceramic color. In order to ensure that the green body is fully formed into porcelain, it is necessary to maintain a constant temperature at a high temperature of 1200℃-1400℃ for a certain period of time. During the constant temperature process, the chemical reaction and structural changes inside the green body are fully carried out, and the crystal structure is continuously Improved, the pore structure is more uniform and stable, and the strength and other performance indicators reach the best state. The cooling stage of firing in step S3 adopts natural cooling or controlled cooling rate method. Natural cooling does not require additional equipment to control the cooling process, and the operation is relatively simple. The equipment and operation of controlled cooling rate are relatively complex, but it can produce acrylic acid catalyst partners with more stable and reliable quality. During the natural cooling process, the blank starts to cool down from about 1400°C. In the first few hours, the temperature drop rate may be relatively fast. As the blank temperature approaches the ambient temperature, the cooling rate will gradually slow down. The entire cooling process may take hours or even days. To control the cooling rate, the kiln is equipped with a cooling fan and a temperature sensor. At the beginning of cooling, the temperature sensor monitors the temperature inside the kiln and the blank in real time, and transmits the data to the control system. The control system adjusts the speed of the cooling fan according to the preset cooling rate curve to control the flow of cooling air, thereby achieving precise control of the cooling rate.

[0037] Further, in step S4, the post-test screening stage adopts strength testing equipment (such as universal material testing machine) to carry out strength testing on the acrylic acid catalyst partner, and the strength testing equipment is followed by water absorption test and bulk specific gravity detection. The sphere is placed in the fixture of the testing equipment, and pressure is applied at a stable loading rate until the sphere breaks, and the maximum pressure value at this time is recorded as the strength of the sphere. A certain number of samples should be extracted from each batch for testing. If the test results show that the strength is less than 400N, the product strength is judged to be unqualified. In the water absorption test, the mass of the dried sphere is first weighed and recorded as m1. The sphere is then completely immersed in water and kept for a certain period of time (such as 24 hours) to allow the sphere to fully absorb water. After taking out the sphere, the excess water on the surface is gently wiped with a wet cloth, and the mass is weighed again and recorded as m2. According to the formula: Calculate the water absorption rate. Also test according to a certain sampling ratio,

[0038] If the calculated water absorption rate is greater than 5%, the water absorption rate of the product is judged to be unqualified. In the bulk specific gravity test, a measuring cylinder (volume V) is used. The container is placed on a horizontal table and the acrylic acid catalyst partner sample is slowly poured into the container. Try to avoid impact and shaking of the sample to allow the sample to accumulate naturally. When the sample is accumulated close to the top of the container, use a ruler or other flattening tool to scrape the sample surface to ensure that the sample surface is flat. Then weigh the total mass M of the container and sample. According to the formula (m0 is the container mass) Calculate the bulk density. Take a certain number of samples from each batch and measure them. If the calculated result is not within the range of 1.1g / ml-1.15g / ml, the product is considered unqualified for bulk density.

[0039] Example 2: The present invention provides a method for preparing an acrylic acid catalyst partner, comprising the following raw materials: selected kaolin and a pore-forming agent, wherein the mass ratio of kaolin to pore-forming agent is 80:15.

[0040] A method for preparing an acrylic acid catalyst partner comprises the following steps:

[0041] S1. Select carefully selected kaolin and pore-forming agent in a mass ratio of 80:15, mix the kaolin and pore-forming agent evenly according to the above ratio, and ensure that the two are fully integrated.

[0042] S2. Roll the mixture in S1 into spheres with a diameter of 5-5.5 mm.

[0043] S3, firing the sphere formed in S2 at a high temperature of 1200-1400℃ to make it porcelain, reduce water absorption and increase strength. At the same time, the pore-forming agent creates voids inside the sphere to reduce the bulk weight.

[0044] S4. Perform performance tests on the fired catalyst partner to ensure that its bulk density is 1.1-1.15 g / ml, its strength is ≥400 N, and its water absorption rate is ≤5%.

[0045] In this embodiment, the detailed steps of raw material mixing, molding, firing and post-test screening in the method for preparing the acrylic acid catalyst partner are consistent with those in the first embodiment.

[0046] The test results are as follows:

[0047] Example 1 Since kaolin accounts for a large proportion, the prepared catalyst partner may have higher strength and a more stable structure, the pore-forming agent accounts for a small proportion, the internal voids may be relatively small, the bulk density may be closer to the upper limit of 1.15g / ml, the porcelain-forming effect is better, the water absorption rate may be low, meeting or exceeding the requirement of ≤5%, high strength, not easy to break, reduced replacement frequency, wear resistance, and suitable for catalyst beds for long-term use, but the bulk density is high, which may lead to a larger filling density of the catalyst bed, which is not conducive to the uniform dilution of the catalyst, and the internal voids are small, which may affect the permeability of the catalyst partner and the overall performance of the catalyst bed.

[0048] In Example 2, since the pore-forming agent accounts for a small proportion, the prepared catalyst partner may have more internal voids while maintaining a certain strength, and the bulk density may be closer to the lower limit of 1.1 g / ml, which is conducive to the uniform dilution of the catalyst. Although the porcelain-forming effect may be slightly inferior to that of Method 1, it is still within an acceptable range and meets the requirement of ≤5%. The low bulk density is conducive to the uniform dilution of the catalyst and the permeability of the bed, and may improve the overall performance of the catalyst bed, such as mass transfer efficiency and reaction rate, but the strength may be slightly lower than that of Method 1, the wear resistance is slightly worse, the structural stability may be slightly weaker, and regular inspection and replacement are required.

[0049] Through the experiments of Example 1 and Example 2, it is concluded that the appropriate mass ratio of kaolin to pore-forming agent is selected according to the specific needs and performance requirements of the catalyst bed. If strength and structural stability are more important, method 1 can be selected; if bulk density and permeability are more important, method 2 can be selected.

[0050] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing an acrylic acid catalyst partner, characterized in that: The raw materials include selected kaolin and pore-forming agent. The mixed selected kaolin and pore-forming agent are made into spheres with a diameter of 5mm-5.5mm by rolling molding process. The bulk density is 1.1g / ml-1.15g / ml, the strength is ≥400N, and the water absorption rate is ≤5%.

2. The method for preparing an acrylic acid catalyst partner according to claim 1, characterized in that: The mass ratio of the selected kaolin and the pore-forming agent is in the range of 70:30-85:15, and the volume ratio of the selected kaolin and the pore-forming agent is in the range of 60:40-75:

25.

3. The method for preparing an acrylic acid catalyst partner according to claim 1, characterized in that: The following steps are involved: S1. Mixing raw materials: Selected kaolin is selected as the main raw material, and an appropriate amount of pore-forming agent is added. The selected kaolin and pore-forming agent are weighed according to a predetermined ratio and placed in a mixing device for thorough mixing. S2, molding, put the mixed raw materials into the rolling molding equipment for rolling molding, and the mixed raw materials are made into spheres with a diameter of 5mm-5.5mm. S3. Firing: Place the formed sphere in a high-temperature kiln and fire it at a temperature of 1200°C-1400°C to ensure that the sphere can be fully porcelainized and to achieve the purpose of reducing water absorption, increasing strength and creating internal voids. S4. Screening after testing: The fired companion porcelain balls are subjected to quality testing, including bulk density, strength, water absorption and other indicators, to screen out the companion porcelain balls that meet the requirements and ensure that they have similar performance indicators to the catalyst.

4. The method for preparing an acrylic acid catalyst partner according to claim 3, characterized in that: The mixing equipment in step S1 is a planetary mixer, which is made of corrosion-resistant materials such as stainless steel.

5. The method for preparing an acrylic acid catalyst partner according to claim 3, characterized in that: In step S2, the rolling forming equipment produces spheres with a diameter of 5 mm to 5.5 mm, the roller diameter is between 20 cm and 50 cm, and the length is between 50 cm and 100 cm.

6. The method for preparing an acrylic acid catalyst partner according to claim 1, characterized in that: The main component of the kaolin is kaolinite, whose chemical formula is Al2Si2O5(OH)4, and the chemical reaction equation of high temperature firing is:

7. The method for preparing an acrylic acid catalyst partner according to claim 1, characterized in that: The pore-forming agent is ammonium bicarbonate NH4HCO3, which decomposes during the firing process to produce gas, thereby creating gaps inside the sphere. The chemical formula is:

8. The method for preparing an acrylic acid catalyst partner according to claim 3, characterized in that: The firing process in step S3 includes firing in a key temperature range and a constant temperature holding stage.

9. The method for preparing an acrylic acid catalyst partner according to claim 3, characterized in that: The cooling stage of the firing in step S3 adopts a natural cooling method or a controlled cooling rate method.

10. The method for preparing an acrylic acid catalyst partner according to claim 3, characterized in that: In the post-test screening stage in step S4, a strength test device (such as a universal material testing machine) is used to perform a strength test on the acrylic acid catalyst partner, followed by a water absorption test and a bulk specific gravity test.

Images