Filler, preparation method thereof and application of filler in fixed bed oxidation exothermic reaction

Abstract

The invention discloses filler, a preparation method thereof and application of the filler in fixed bed oxidation exothermic reaction, and belongs to the technical field of fixed bed filler. The preparation method comprises the following steps: pretreating a talc material to remove impurities, mixing the treated talc material with alkaline earth metal, alkali metal and other auxiliary metals according to a ripening ratio, pulping, ball-milling, grinding, spray-drying, molding to obtain a Raschig ring, carrying out first-stage roasting, and carrying out second-stage roasting to obtain a filler finished product. The strength of the filler finished product is greater than 150N / grain, the water absorption is less than 0.3%, and the BET is less than 0.1 m < 2 > / g. The filler is used for oxidation exothermic reaction and is filled with the catalyst according to different proportions, so that heat transfer is enhanced, and local exothermic overtemperature is reduced; mass transfer contact of the materials is improved, the materials are fully mixed, and the filler can inhibit backmixing of the materials; the fillers in different shapes are suitable for different oxidation reaction scenes, the pressure difference in the reactor is reduced, and pulverization of the catalyst is reduced.

Description

Technical Field

[0001] This invention belongs to the field of fixed-bed packing technology, and particularly relates to a packing material, its preparation method, and its application in fixed-bed oxidative exothermic reactions. Background Technology

[0002] Oxidation reactions are essentially electron transfer reactions, typically involving the breaking of chemical bonds in reactants and the formation of chemical bonds in products. Breaking reactant bonds requires energy absorption, while forming product bonds releases energy. In oxidation reactions, the energy released is far greater than the energy absorbed. This excess energy is dissipated as heat, causing the system temperature to rise, resulting in an exothermic reaction.

[0003] Formaldehyde is an important downstream product of methanol and a raw material for organic chemicals. It is one of the common platform molecules in C1 and low-carbon chemicals. There are two commonly used methods for producing formaldehyde both domestically and internationally: the "silver catalytic method" and the "iron-molybdenum catalytic method." The former has been gradually replaced by the "iron-molybdenum method" due to the high cost of the catalyst, the high catalytic reaction temperature, and the low concentration of formaldehyde produced. However, due to the formation of hot spots in the oxidation reaction, molybdenum volatilizes from the catalyst, thus deactivating it. In addition, the large amount of air in the reaction leads to catalyst pulverization, reducing the catalyst's catalytic activity and selectivity for aldehydes.

[0004] In the butane oxidation to maleic anhydride reaction, exothermic reaction is a key influencing factor, exhibiting a double-edged sword effect of "moderate benefit, excessive harm." The core issue is balancing reaction efficiency and product selectivity. Excessive exothermic reaction leads to a rapid increase in reaction temperature, causing deep oxidation of butane or maleic anhydride, generating byproducts such as CO and CO2, and significantly reducing maleic anhydride selectivity and yield. Excessively high temperatures can easily cause "runaway" phenomena, not only damaging reaction stability but also potentially leading to safety risks such as equipment overheating and sudden pressure increases. Industrially used VPO catalysts are temperature-sensitive; high temperatures can cause sintering of the active catalyst components and phase transformation, resulting in permanent catalyst deactivation and shortening its lifespan.

[0005] Excessive exothermic reaction has a destructive effect on the ammoxidation of propylene to acrylonitrile, causing a chain reaction of harm in terms of product yield, safe operation, and catalyst life. The core issue is that it disrupts the thermodynamic and kinetic equilibrium of the reaction.

[0006] For exothermic reactions, the core function of the packing material is to enhance heat and mass transfer, enabling the rapid and uniform removal of reaction heat, which is crucial for achieving safe, efficient, stable, and selective operation of the reaction. Summary of the Invention

[0007] The purpose of this invention is to provide a packing material and its preparation method, as well as its application in fixed-bed exothermic oxidation reactions. The packing material of this invention, through a special material ratio and after molding and calcination, has good performance in fixed-bed exothermic oxidation reactions.

[0008] To solve the above technical problems and achieve the above-mentioned objectives, the present invention adopts the following technical solution: The present invention provides a filler comprising silicon dioxide, alkali metal oxide, alkaline earth metal oxide and auxiliary metal oxide, wherein the auxiliary metal oxide comprises zirconium oxide and aluminum oxide.

[0009] Furthermore, the alkaline earth metal is selected from at least one of magnesium, barium, and calcium, and the alkali metal is selected from at least one of potassium, sodium, and cesium.

[0010] Further, the filler comprises the following components by mass percentage: Al2O3 2%~8%, SiO2 50%~65%, MO 2%~45%, ZrO 0.1%~2%, R2O 0.1%~1%, M is an alkaline earth metal, and R is an alkali metal.

[0011] Further, the filler comprises the following components by mass percentage: Al2O3 2%~8%, SiO2 50%~65%, MgO 20%~35%, CaO 1%~5%, BaO 1%~5%, ZrO 0.1%~2%, K2O 0.1%~1%.

[0012] Furthermore, the packing material is in the shape of a Raschig ring, a sphere, or a honeycomb briquette.

[0013] Furthermore, the filler has a strength greater than 150 N / particle, a water absorption rate of less than 0.3%, and a BET of less than 0.1 m. 2 / g.

[0014] The present invention also provides a method for preparing the above-mentioned filler, comprising mixing pretreated talc material with an alkaline earth metal source, an alkali metal source and an auxiliary metal source to form a slurry, ball milling and spray drying, molding and calcining to obtain the filler, wherein the auxiliary metal source includes a zirconium source and an aluminum source.

[0015] Furthermore, the talc material includes raw talc and clinker talc, and the mass ratio of clinker talc to raw talc is 7~9:3~1.

[0016] Furthermore, the talc material includes raw talc and clinker talc, and the mass ratio of clinker talc to raw talc is 8~9:2~1.

[0017] Furthermore, after mixing and pulping, the mass ratio of the components, calculated as oxides, is Al2O3:SiO2:MO:ZrO:R2O = 0.02~0.08:0.5~0.65:0.02~0.45:0.001~0.02:0.001~0.01, where M is an alkaline earth metal and R is an alkali metal.

[0018] Further, the alkaline earth metal source is selected from at least one of alkaline earth metal nitrates, chlorides, carbonates, sulfates, phosphates, and hydroxides, and the alkaline earth metal is selected from at least one of magnesium, barium, and calcium; the alkali metal source is selected from at least one of alkali metal nitrates, chlorides, carbonates, sulfates, phosphates, and hydroxides, and the alkali metal is selected from at least one of potassium, sodium, and cesium; the zirconium source is selected from at least one of zirconium nitrates, acetates, sulfates, and chlorides; and the aluminum source is aluminum nitrate or aluminum oxide.

[0019] Furthermore, after ball milling, the particle PSD was measured to be D90 < 30 micrometers.

[0020] Furthermore, after ball milling, the particle PSD was measured to be D90 < 25 micrometers.

[0021] Furthermore, the conditions for spray drying include: spray inlet air temperature of 300~500℃ and outlet temperature of 150~250℃.

[0022] Furthermore, the conditions for spray drying include: spray inlet air temperature of 350~450℃ and outlet temperature of 170~220℃.

[0023] Furthermore, the calcination includes primary calcination and secondary calcination. The primary calcination involves heating to 500-900℃ at a rate of 1-2℃ / min and calcining for 4-10 hours. The secondary calcination involves heating to 1000-1420℃ at a rate of 1-2℃ / min and calcining for 4-12 hours.

[0024] Furthermore, the calcination includes primary calcination and secondary calcination. The primary calcination involves heating to 650-900°C at a rate of 1-2°C / min, and the secondary calcination involves heating to 1200-1400°C at a rate of 1-2°C / min.

[0025] Furthermore, the preprocessing includes: (1) Crush the talc material; (2) After washing, filtering, and drying I, acid treatment is performed; (3) Filter, wash with water until neutral, dry II, and pulverize.

[0026] Furthermore, in step (1), the talc material is crushed to below 60 mesh.

[0027] Further, in step (2), the washing includes taking 5 to 8 times the mass of the talc material and mixing it with the talc material, and stirring at 40 to 80°C for 6 to 8 hours.

[0028] Furthermore, the drying process I includes drying at 100~150℃ for 4~10 hours.

[0029] Furthermore, the acid treatment includes mixing an acid solution with talc material at a solid-liquid mass ratio of 5 to 10:1, treating at 40 to 80°C for 4 to 6 hours, and the acid concentration being 1 wt% to 10 wt%.

[0030] Furthermore, the acid treatment includes mixing an acid solution with talc material and treating it at 50-70°C for 4-6 hours, with an acid concentration of 2wt%-6wt%.

[0031] In the pretreatment of this invention, the purpose of treating the dried talc material with a certain amount of acid solution is to remove trivalent metal ions in order to achieve the purpose of impurity removal.

[0032] Furthermore, the iron oxide content in the pretreated talc material is less than 0.05 wt%.

[0033] Furthermore, in step (3), the drying process II includes drying at 100~150℃ for 2~10 hours.

[0034] Furthermore, in step (3), the talc material is crushed to below 100 mesh.

[0035] The present invention also provides an application of the above-mentioned packing material in a fixed-bed exothermic oxidation reaction.

[0036] Furthermore, the fixed-bed exothermic oxidation reaction includes the reaction of methanol oxidation to formaldehyde, butane oxidation to maleic anhydride, and propylene ammoxidation to acrylonitrile.

[0037] The beneficial effects of this invention include: During the catalyst loading process, the packing material of this invention is mixed and loaded in different proportions. By adjusting the ratio of the packing material synthesis according to different reactions, the prepared packing material can be applied to the exothermic oxidation reaction, which can achieve: ① enhanced heat transfer and reduced local exothermic overheating; ② improved mass transfer contact of materials, thorough mixing, and suppression of material backmixing; ③ different shaped packing materials are suitable for different oxidation reaction scenarios, reducing the pressure difference in the reactor and reducing catalyst pulverization. Detailed Implementation

[0038] The following description, in conjunction with embodiments, aims to make the advantages and features of the present invention more readily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0039] The talc components used in the following examples are as follows:

[0040] In this invention, the strength of Raschig rings is tested using a particle strength tester. The dimensions of each Raschig ring are: outer diameter 5mm ± 1mm, inner diameter 2.4mm ± 0.02mm, and height 2.6mm ± 0.1mm. The water absorption rate is tested using the vacuum immersion method.

[0041] Example 1 Take 142.8 kg of calcined talc material and 37 kg of raw talc material, crush them to below 60 mesh, wash them with 5 times their weight of deionized water, filter them and dry them in an oven at 120℃ for 12 hours; after taking them out, add 5 times their weight of 1.34% hydrochloric acid aqueous solution, heat to 60℃ and keep warm for 6 hours; filter them, wash them with deionized water until neutral, dry them at 150℃ for 8 hours, crush them to below 100 mesh, and test that the content of metallic iron oxide is less than 0.05%, to obtain talc material H.

[0042] Take 5.6 kg of aluminum nitrate, 6.5 kg of magnesium nitrate, 8.5 kg of calcium nitrate, 4.78 kg of barium nitrate, 0.75 kg of potassium nitrate, and 4.13 kg of zirconium nitrate. Dissolve them in 500 g of deionized water to obtain a salt solution. Mix 89.93 kg of the above-treated talc material H with the salt solution and ball mill. When the PSD (Power Distribution Scale) is D90 < 25 micrometers, stop ball milling and transfer the material to a spray dryer for spraying. The spray inlet air temperature is 400℃ and the outlet temperature is 190℃. After spray molding, the material is shaped into Raschig rings and calcined. The temperature is increased to 980℃ at a rate of 1℃ / min and calcined for 6 hours. Then, the temperature is increased to 1400℃ at a rate of 1℃ / min and calcined for 8 hours to obtain the finished filler. The finished product is tested and the specifications are: strength 152 N / particle, water absorption 0.14%, BET = 0.007m. 2 / g.

[0043] Example 2 Take 132 kg of calcined talc material and 34.4 kg of raw talc material, crush them to below 60 mesh, wash them with 5 times their weight of deionized water, filter them, and dry them in an oven at 120℃ for 12 hours; after taking them out, add 5 times their weight of 1.5% sulfuric acid aqueous solution to the material, heat it to 60℃ and keep it at that temperature for 6 hours; filter it, wash it with deionized water until neutral, dry it at 150℃ for 8 hours, crush it to below 100 mesh, and test it to find that the content of metallic iron oxide is less than 0.05%, thus obtaining talc material H.

[0044] Take 5.2 kg of aluminum nitrate, 36.5 kg of magnesium nitrate, 5.8 kg of calcium nitrate, 3.4 kg of barium nitrate, 0.25 kg of potassium nitrate, and 3.0 kg of zirconium nitrate. Dissolve them in 500 g of deionized water to obtain a salt solution. Mix 83.2 kg of the above-treated talc material H with the salt solution and ball mill. When the PSD (partial pressure distribution) is measured to be D90 < 25 micrometers, ball milling is stopped. The material is then transferred to a spray dryer for spraying. The inlet air temperature is 400℃, and the outlet temperature is 190℃. After spray molding, the material is shaped into Raschig rings and calcined. The temperature is increased to 980℃ at a rate of 1℃ / min and calcined for 6 hours. Then, the temperature is increased to 1400℃ at a rate of 1℃ / min and calcined for 8 hours to obtain the finished filler. The product has a strength of 154 N / particle, a water absorption rate of 0.17%, and a BET of 0.009 m. 2 / g.

[0045] Example 3 Take 148.8 kg of calcined talc material and 38.6 kg of raw talc material, crush them to below 60 mesh, wash them with 5 times their weight of deionized water, filter them, and dry them in an oven at 120℃ for 12 hours; after taking them out, add 5 times their weight of 2.0% nitric acid aqueous solution to the material, heat it to 60℃ and keep it at that temperature for 6 hours; filter it, wash it with deionized water until neutral, dry it at 150℃ for 8 hours, crush it to below 100 mesh, and test it to find that the content of metallic iron oxide is less than 0.05%, thus obtaining talc material H.

[0046] Take 0.52 kg of aluminum nitrate, 3.2 kg of magnesium nitrate, 7.3 kg of calcium nitrate, 3.4 kg of barium nitrate, 0.42 kg of potassium nitrate, and 3.3 kg of zirconium nitrate. Dissolve them in 500 g of deionized water to obtain a salt solution. Mix 93.7 kg of the above-treated talc material H with the salt solution and ball mill. When the PSD (partial diastolic density) is D90 < 25 micrometers, stop ball milling and transfer the material to a spray dryer for spraying. The spray inlet air temperature is 400℃ and the outlet temperature is 190℃. After spray molding, the material is shaped into Raschig rings and calcined. The temperature is increased to 980℃ at a rate of 1℃ / min and calcined for 6 hours. Then, the temperature is increased to 1400℃ at a rate of 1℃ / min and calcined for 8 hours to obtain the finished filler. The product has a strength of 154 N / particle, a water absorption rate of 0.15%, and a BET of 0.009 m. 2 / g.

[0047] Example 4 Take 156 kg of calcined talc material and 40.4 kg of raw talc material, crush them to below 60 mesh, wash them with 5 times their weight of deionized water, filter them, and dry them in a 120℃ oven for 12 hours; after taking them out, add 5 times their weight of 2.0% nitric acid aqueous solution to the material, heat it to 60℃ and keep it at that temperature for 6 hours; filter it, wash it with deionized water until neutral, dry it at 150℃ for 8 hours, crush it to below 100 mesh, and test it to find that the content of metallic iron oxide is less than 0.05%, thus obtaining talc material H.

[0048] Take 2.6 kg of aluminum nitrate, 2.06 kg of magnesium nitrate, 0.58 kg of calcium nitrate, 0.68 kg of barium nitrate, 0.21 kg of potassium nitrate, and 1.37 kg of zirconium nitrate. Dissolve them in 500 g of deionized water to obtain a salt solution. Mix 98.2 kg of the above-treated talc material H with the salt solution and ball mill. When the PSD (partial diastolic density) is D90 < 25 micrometers, stop ball milling and transfer the material to a spray dryer for spraying. The spray inlet air temperature is 400℃ and the outlet temperature is 190℃. After spray molding, the material is shaped into Raschig rings and calcined. The temperature is increased to 980℃ at a rate of 1℃ / min and calcined for 6 hours. Then, the temperature is increased to 1400℃ at a rate of 1℃ / min and calcined for 8 hours to obtain the finished filler. The product has a strength of 152 N / particle, a water absorption rate of 0.2%, and a BET of 0 m. 2 / g.

[0049] Example 5 Take 135.6 kg of calcined talc material and 35.2 kg of raw talc material, crush them to below 60 mesh, wash them with 5 times their weight of deionized water, filter them, and dry them in a 120℃ oven for 12 hours; after taking them out, add 5 times their weight of 2.0% nitric acid aqueous solution to the material, heat it to 60℃ and keep it at that temperature for 6 hours; filter it, wash it with deionized water until neutral, dry it at 150℃ for 8 hours, crush it to below 100 mesh, and test it to find that the content of metallic iron oxide is less than 0.05%, thus obtaining talc material H.

[0050] Take 6.13 kg of aluminum nitrate, 8.39 kg of magnesium nitrate, 13.7 kg of calcium nitrate, 7.67 kg of barium nitrate, 0.75 kg of potassium nitrate, and 5.5 kg of zirconium nitrate. Dissolve them in 500 g of deionized water to obtain a salt solution. Mix 85.4 kg of the above-treated talc material H with the salt solution and ball mill. When the PSD (partial diastolic density) is measured to be D90 < 25 micrometers, ball milling is stopped. The material is then transferred to a spray dryer for spraying. The inlet air temperature is 400℃, and the outlet temperature is 190℃. After spray molding, the material is shaped into Raschig rings and calcined. The temperature is increased to 980℃ at a rate of 1℃ / min and calcined for 6 hours. Then, the temperature is increased to 1400℃ at a rate of 1℃ / min and calcined for 8 hours to obtain the finished filler. The product has a strength of 152 N / particle, a water absorption rate of 0.2%, and a BET of 0.005 m. 2 / g.

[0051] Example 6 The packing materials obtained in Examples 1-5 were applied to the methanol oxidation reaction to prepare formaldehyde. The size of each Raschig ring was 5 mm ± 1 mm outer diameter, 2.4 mm ± 0.02 mm inner diameter, and 2.6 mm ± 0.1 mm height. The specific steps are as follows, wherein the pure phase catalyst was prepared using the steps in Example 1 of patent CN117839712A.

[0052] A reactor with a length of 2.0 m and an inner diameter of 21 mm was selected. The lower end of the reactor was filled with 60 g of packing material. 145 g of pure-phase catalyst was added to obtain reaction layer 3. A mixture of 24 g of catalyst and 18 g of packing material was added to obtain reaction layer 2. 33 g of catalyst and 50 g of packing material were added to obtain reaction layer 1. The upper end was filled with packing material. The temperature was raised to a controlled reaction temperature of 285 °C for dehydration. Methanol and air were introduced at a nitrogen flow rate of 15 L / min, an air flow rate of 19 L / min, and a methanol flow rate of 6 mL / min to initiate the reaction. The results are shown in Table 1.

[0053] Table 1

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A packing material, characterized in that, The filler includes silica, alkali metal oxides, alkaline earth metal oxides, and auxiliary metal oxides, wherein the auxiliary metal oxides include zirconium oxide and alumina.

2. The packing material according to claim 1, characterized in that, The alkaline earth metals are selected from at least one of magnesium, barium, and calcium, and the alkali metals are selected from at least one of potassium, sodium, and cesium. Preferably, the filler comprises the following components by mass percentage: Al2O3 2%~8%, SiO2 50%~65%, MO 2%~45%, ZrO 0.1%~2%, R2O 0.1%~1%, M is an alkaline earth metal, R is an alkali metal; Preferably, the filler comprises the following components by mass percentage: Al2O3 2%~8%, SiO2 50%~65%, MgO 20%~35%, CaO 1%~5%, BaO 1%~5%, ZrO 0.1%~2%, K2O 0.1%~1%.

3. The packing material according to claim 1 or 2, characterized in that, The packing material is in the shape of a Raschig ring, a sphere, or a honeycomb briquette. And / or, the filler has a strength greater than 150 N / particle, a water absorption rate less than 0.3%, and a BET of less than 0.1 m. 2 / g.

4. A method for preparing the filler according to any one of claims 1 to 3, characterized in that, The process involves mixing pretreated talc material with an alkaline earth metal source, an alkali metal source, and an additive metal source to form a slurry, ball milling, spray drying, molding, and calcining to obtain the filler. The additive metal source includes a zirconium source and an aluminum source.

5. The preparation method according to claim 4, characterized in that, The talc material includes raw talc and clinker talc, and the mass ratio of clinker talc to raw talc is 7~9:3~1, preferably 8~9:2~1; And / or, after mixing and pulping, the mass ratio of the components, calculated as oxides, is Al2O3:SiO2:MO:ZrO:R2O = 0.02~0.08:0.5~0.65:0.02~0.45:0.001~0.02:0.001~0.01, where M is an alkaline earth metal and R is an alkali metal; And / or, the alkaline earth metal source is selected from at least one of alkaline earth metal nitrates, chlorides, carbonates, sulfates, phosphates, and hydroxides, and the alkaline earth metal is selected from at least one of magnesium, barium, and calcium; the alkali metal source is selected from at least one of alkali metal nitrates, chlorides, carbonates, sulfates, phosphates, and hydroxides, and the alkali metal is selected from at least one of potassium, sodium, and cesium; the zirconium source is selected from at least one of zirconium nitrates, acetates, sulfates, and chlorides; and the aluminum source is aluminum nitrate or aluminum oxide. And / or, after ball milling, the particle PSD is detected as follows: D90 < 30 micrometers, preferably D90 < 25 micrometers.

6. The preparation method according to claim 4 or 5, characterized in that, The conditions for spray drying include: spray inlet air temperature of 300~500℃, outlet temperature of 150~250℃, preferably spray inlet air temperature of 350~450℃, and outlet temperature of 170~220℃. And / or, the calcination includes primary calcination and secondary calcination, wherein the primary calcination is to raise the temperature to 500-900℃ at a rate of 1-2℃ / min, preferably to 650-900℃, and calcinate for 4-10 hours; and the secondary calcination is to raise the temperature to 1000-1420℃ at a rate of 1-2℃ / min, preferably to 1200-1400℃, and calcinate for 4-12 hours.

7. The preparation method according to any one of claims 4 to 6, characterized in that, The preprocessing includes: (1) Crush the talc material, preferably to a fineness of 60 mesh or less; (2) After washing, filtering, and drying I, acid treatment is performed; (3) Filter, wash with water until neutral, dry II, and pulverize, preferably pulverize to below 100 mesh.

8. The preparation method according to claim 7, characterized in that, In step (2), the washing includes taking 5 to 8 times the mass of the talc material and mixing it with the talc material, and stirring at 40 to 80°C for 6 to 8 hours; And / or, the drying I includes drying at 100~150℃ for 4~10 hours; And / or, the acid treatment includes mixing an acid solution with a talc material at a solid-liquid mass ratio of 5-10:1, and treating at 40-80°C, preferably 50-70°C, for 4-6 hours. The acid solution is selected from at least one of nitric acid, sulfuric acid, hydrochloric acid, acetic acid, and acetic acid, and the acid concentration is 1wt%-10wt%, preferably 2wt%-6wt%. And / or, in step (3), the drying II includes drying at 100~150℃ for 2~10h; And / or, the iron oxide content in the pretreated talc material is less than 0.05 wt%.

9. The use of the packing material according to any one of claims 1 to 3 in a fixed-bed exothermic oxidative reaction.

10. The application according to claim 9, characterized in that, The fixed-bed exothermic oxidation reactions include the methanol oxidation to formaldehyde reaction, the butane oxidation to maleic anhydride reaction, and the propylene ammoxidation to acrylonitrile reaction.

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