A molding catalyst for selective oxidation of isobutylene / tert-butanol and its preparation method

Abstract

This invention provides a molded catalyst for the selective oxidation of isobutylene / tert-butanol and its preparation method. The molded catalyst comprises an active component and a hydroxysilicate, wherein the active component includes a molybdenum-bismuth-based composite metal oxide. In the catalyst preparation process, this invention improves the mechanical strength of the molded catalyst body after pore-expansion treatment by adding layered hydroxysilicates as a lubricant and reinforcing agent, resulting in a structurally stable molded body. This catalyst can selectively catalyze the selective oxidation of isobutylene / tert-butanol to produce valuable products with high selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, and more specifically, to a shaped catalyst for the selective oxidation of isobutylene / tert-butanol and its preparation method. Background Technology

[0002] Molybdenum-bismuth composite metal oxides (Mo-Bi-O) are most widely used in the selective oxidation of isobutylene / tert-butanol to methacrolein / methacrylic acid (unsaturated aldehyde / acid). The general preparation process for this type of catalyst is as follows: Molybdenum, bismuth, iron, cobalt, alkali metals, and other additives are simultaneously added to a mother liquor system to form a homogeneous system. The solvent (usually water) is removed from this system, and the resulting solid precipitate is calcined at high temperature to obtain a catalyst matrix powder. The catalyst matrix powder is granulated to form particles with a specific particle size distribution. Reinforcing agents are added to improve mechanical strength, and the mixture is further shaped using specific molding techniques to obtain a molded body with a specific shape.

[0003] Typically, these catalyst profiles are packed into high-temperature fixed-bed tubular reactors for catalytic gas-solid selective oxidation reactions. For gas-solid phase catalytic oxidation reactions, the selectivity and rate of the reaction are greatly limited by the number of active sites on the catalyst surface and the rate at which reactants diffuse to these sites. The diffusion of reactants through the catalyst's pore structure and their contact with active sites become the limiting steps of the reaction. Higher specific surface area and pore volume are beneficial for rapid conversion of reactants on the catalyst. However, after prolonged high-temperature, high-flow-rate gas passage, the catalyst must possess high mechanical stability to minimize powder shedding, structural collapse, and even the resulting reduction in catalyst life and equipment failure during long-term use of the catalyst profile.

[0004] For gas-solid phase reaction catalysts, pore-forming agents are typically removed from the catalyst body through heat treatment or dissolution with organic solvents. This creates large pores within the catalyst body, facilitating contact between reactant molecules and active sites, thus promoting more economical catalyst use. However, after this treatment, optimal pore volume and optimal mechanical strength are often not simultaneously achieved in a single catalyst body. Catalyst bodies with high pore volume tend to have lower mechanical strength, while those with high mechanical strength often require increased molding pressure or bulk density, resulting in typically lower pore volume. To further enable the catalyst to utilize more active sites, a suitable pore structure is required.

[0005] Graphite is typically added as a reinforcing agent during catalyst molding because its good fluidity can significantly reduce frictional stress caused by excessive pressure. However, due to its high fluidity, graphite can easily detach from the catalyst body during pore-expanding operations, leading to a decrease in the catalyst's impact resistance and affecting its performance.

[0006] Compared to graphite, hydroxysilicates possess a superior layered unit structure, with interlayer connections via hydrogen bonds and van der Waals forces, far smaller than ionic bonds and covalent bonds within each layer. Under high pressure, these bonds readily spread and dissociate along directions parallel to the layers. Their layered structure is remarkably similar to that of graphite. Furthermore, during the molding process, hydroxysilicate sheets can spread, deposit, or undergo a series of tribochemical reactions on the grinding surface, forming a self-lubricating film or inducing traditional abrasive wear. Therefore, they exhibit excellent self-lubricating and self-healing properties, which are beneficial for maintaining the catalyst's pore structure. At high temperatures, the hydroxyl groups on the surface of the added hydroxysilicates can undergo a certain degree of removal, strengthening their interaction with the catalyst bulk. The rigid structure of hydroxysilicates further preserves the internal pore structure of the catalyst at high temperatures, further enhancing catalyst performance. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention discloses a shaped catalyst for the selective oxidation of isobutylene / tert-butanol in a heterogeneous manner and its preparation method. Compared with the catalyst shaped body in the prior art, this improved shaped catalyst is formed by adding a certain amount of hydroxysilicate as a lubricant and structural reinforcing agent, and a certain amount of organic acid as a pore expander during the catalyst forming process. Then, the pore expander is removed by high-temperature calcination to form an improved shaped catalyst. This catalyst, when used in the selective oxidation reaction of isobutylene / tert-butanol, has the characteristics of high raw material conversion rate and high selectivity and high yield of the target product.

[0008] One objective of this invention is to provide a molding catalyst for the selective oxidation of isobutylene / tert-butanol, comprising an active component and a hydroxysilicate, wherein the active component comprises a molybdenum-bismuth composite metal oxide.

[0009] The molybdenum-bismuth composite metal oxide includes at least molybdenum, bismuth, iron, and cobalt.

[0010] The hydroxysilicate is preferably at least one of aluminum hydroxysilicate, magnesium hydroxysilicate, copper hydroxysilicate, and natural minerals containing hydroxysilicates, wherein the hydroxysilicate may optionally be surface-modified.

[0011] The hydroxysilicate is preferably 0.1-5 wt% of the molding catalyst, more preferably 0.1-4 wt%. Specifically, the hydroxysilicate content can be 0.1 wt%, 0.5 wt%, 1 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt% of the molding catalyst, etc.

[0012] Preferably, the active component may further include a metal additive, which is preferably selected from at least one of cesium, antimony, rubidium, potassium, vanadium, magnesium, tungsten, and nickel.

[0013] Optionally, the molding catalyst may further include a lubricant, preferably at least one of graphite, starch, and stearate.

[0014] The lubricant is preferably 0.1-8 wt% of the molding catalyst, more preferably 0.1-4 wt%. Specifically, the lubricant content can be 0.1 wt%, 0.5 wt%, 1 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, etc. of the molding catalyst.

[0015] The lateral impact strength of the shaped catalyst is 10-70N, preferably 10-60N.

[0016] The specific surface area of ​​the shaped catalyst is 5-50 m². 2 / g, preferably 10-40m 2 / g.

[0017] The bulk density of the shaped catalyst is 0.5–1.8 g / cm³. 3 Preferably, it is 0.8–1.5 g / cm³. 3 .

[0018] The pore volume of the shaped catalyst is 0.05–0.20 cm³. 3 / g, preferably 0.08~0.15cm 3 / g.

[0019] A second objective of this invention is to provide a method for preparing the aforementioned molding catalyst, comprising the following steps:

[0020] S1, raw materials, including the active component source, are added to a liquid solvent for reaction, and then ball milled;

[0021] S2, the solid material in the reaction product of step S1 is separated and dried to obtain the catalyst precursor;

[0022] S3, activate the catalyst precursor to obtain catalyst matrix powder;

[0023] S4, the catalyst matrix powder is mixed with the pore-expanding agent, and after molding, a catalyst preform is obtained. Then, the pore-expanding treatment is performed to obtain the shaped catalyst.

[0024] Hydroxysilicates are added to the raw materials in step S1 and / or the catalyst precursor in step S2 and / or the catalyst matrix powder in step S3.

[0025] In the preparation method of the present invention, step S1 includes the following steps:

[0026] S1-1) Mix a portion of the active ingredient source with a liquid solvent and heat;

[0027] S1-2) Add the remaining active ingredient source and continue heating;

[0028] S1-3) Perform ball milling.

[0029] Hydroxysilicates can be added in step S1-2).

[0030] The hydroxysilicate is preferably at least one of aluminum hydroxysilicate, magnesium hydroxysilicate, copper hydroxysilicate, or a natural mineral containing hydroxysilicate.

[0031] The hydroxysilicate can also be surface modified, for example, to obtain a hydroxysilicate with a surface amino group modified. The surface modification method employs a modification method commonly used in the art.

[0032] The selected hydroxysilicate has a size of 20–2000 nm, preferably 50–2000 nm.

[0033] In step S1-1), the active component source includes molybdenum-containing compounds, bismuth-containing compounds, iron-containing compounds, and cobalt-containing compounds. There are no particular limitations on the molybdenum-containing compounds, bismuth-containing compounds, iron-containing compounds, and cobalt-containing compounds; common compounds used in the art for preparing molybdenum-bismuth composite metal oxides can be used.

[0034] In step S1-1), the liquid solvent is an aqueous solvent.

[0035] Optionally, a metal additive source is added in step S1-2). The metal additive is preferably at least one selected from cesium, antimony, rubidium, potassium, vanadium, magnesium, tungsten, and nickel.

[0036] The metal auxiliary source can be an oxide, salt, nitrate, carbonate, bicarbonate, sulfate, phosphate, hydrogen phosphate, halide, or their complex, such as oxalate or acetylacetone complex.

[0037] In step S1-1), the heating temperature is 20-80℃ and the heating time is 0-5h; preferably, the heating temperature is 40-60℃ and the heating time is 3-5h.

[0038] In steps S1-2), the heating temperature is 40-80℃ and the heating time is 3-24h; preferably, the heating temperature is 50-80℃ and the heating time is 3-16h.

[0039] When hydroxysilicate is added in step S1-2), the hydroxysilicate is 0.1-11 wt% of the molybdenum-containing compound, preferably 0.15-7 wt%. Specifically, the amount of hydroxysilicate added can be 0.1 wt%, 0.15 wt%, 0.3 wt%, 0.5 wt%, 1 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10.0 wt%, 11.0 wt%, etc., of the molybdenum-containing compound.

[0040] In the preparation method of this invention, there is no particular limitation on the amount of molybdenum compound, bismuth-containing compound, iron-containing compound, and cobalt-containing compound in the active component source; the amount of catalysts commonly used in the art can be used.

[0041] In the preparation method of this invention, there is no particular limitation on the amount of metal auxiliary agent source used; the amount of catalyst commonly used in the art can be adopted.

[0042] In the preparation method of the present invention, in step S2, the product is dried at 60-150°C for 6-24 hours, preferably at 100-140°C for 12-24 hours;

[0043] In the preparation method of the present invention, in step S2, optionally, a hydroxysilicate is added to the catalyst precursor. When the hydroxysilicate is added to the catalyst precursor, the hydroxysilicate is 0.1-7 wt% of the catalyst precursor, preferably 0.15-4.5 wt%. Specifically, the hydroxysilicate can be 0.1 wt%, 0.15 wt%, 0.3 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt% of the catalyst precursor, etc.

[0044] In the preparation method of this invention, in step S2, optionally, a lubricant is added to the catalyst precursor. The lubricant is 0.1-7 wt% of the catalyst precursor, preferably 0.15-4.5 wt%. Specifically, the lubricant can be 0.1 wt%, 0.15 wt%, 0.3 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt% of the catalyst precursor, etc.

[0045] In the preparation method of the present invention, step S3, the activation treatment includes: heating to 250-350°C in an air atmosphere at a heating rate of 1-4°C / min, and then maintaining the temperature for 0-3 hours with or without changing the atmosphere; continuing to heat to 400-550°C at a heating rate of 1-4°C / min, and maintaining the temperature for a period of time with or without changing the atmosphere, preferably within a time range of 2-8 hours; and then cooling to room temperature with or without the addition of an inert gas.

[0046] In the preparation method of the present invention, in step S3, optionally, hydroxysilicate is added to the catalyst matrix powder. When hydroxysilicate is added to the catalyst matrix powder, the hydroxysilicate is 0.1-9 wt% of the catalyst matrix powder, preferably 0.15-5.5 wt%. Specifically, the hydroxysilicate can be 0.1 wt%, 0.15 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt%, 8.5 wt%, 9.0 wt% of the catalyst matrix powder, etc.

[0047] In the preparation method of the present invention, in step S3, a lubricant is optionally added to the catalyst matrix powder. The lubricant is 0.1-9 wt% of the catalyst matrix powder, preferably 0.15-5.5 wt%. Specifically, the hydroxysilicate can be 0.1 wt%, 0.15 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt%, 8.5 wt%, 9.0 wt% of the catalyst matrix powder, etc.

[0048] In the preparation method of the present invention, in step S4, the mass ratio of the pore-expanding agent to the catalyst matrix powder is (2-20):(80-98), preferably (4-12):(88-96).

[0049] The pore-expanding agent is an organic acid, preferably at least one selected from stearic acid, glycolic acid, salicylic acid, malic acid, tartaric acid, citric acid, and citric acid.

[0050] In the preparation method of the present invention, in step S4, when extruding, after the catalyst matrix powder and the pore-expanding agent are mixed, a binder and water are added before molding; preferably, the binder is 1-4.5 wt% of the catalyst matrix powder, the binder is 10-18 wt% of the added water, and the binder is guar gum powder, cellulose and its derivatives.

[0051] The cellulose and its derivatives are preferably cellulose ethers, anionic cellulose derivatives, or nonionic cellulose derivatives, and are more preferably selected from at least one of methylcellulose, ethylcellulose, sodium carboxymethylcellulose, cellulose acetate, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose.

[0052] The pore-expanding treatment employs high-temperature calcination. Preferably, the calcination temperature is 20–100°C higher than the boiling point of the pore-expanding agent and at least 50°C lower than the maximum activation temperature of the catalyst.

[0053] The catalyst molding obtained by the preparation method of the present invention has improved lateral impact pressure resistance and overall mechanical strength, which is beneficial for its long-term use in high-temperature reactors.

[0054] A third objective of this invention is to provide a shaped catalyst obtained by the aforementioned preparation method.

[0055] The fourth objective of this invention is to provide a method for oxidizing isobutylene / tert-butanol to produce methacrolein / acid, comprising oxidizing isobutylene / tert-butanol in the presence of a catalyst, wherein the catalyst is the molding catalyst described above or the molding catalyst obtained by the preparation method described above.

[0056] In the method for oxidizing isobutylene / tert-butanol to produce methacrolein / acid, the reaction temperature is 300–400℃, the pressure is 0.01–0.2 MPa, the volume fraction of isobutylene or tert-butanol is 3–10%, and the total volume hourly space velocity of the feedstock is 500–3000 h⁻¹. -1 .

[0057] This invention obtains a shaped catalyst by simultaneously adding hydroxysilicate and a pore expander to a catalyst shaped body with a specific shape and then removing the pore expander. On the one hand, this improves the utilization rate of the outer surface of the catalyst shaped body, and at the same time, the pore structure of the catalyst is expanded by the pore expansion operation, which improves the utilization rate of the active centers in the catalyst channels. On the other hand, the addition of hydroxysilicate improves the mechanical strength of the catalyst shaped body and improves the performance of the catalyst.

[0058] The beneficial effects of this invention are as follows: The catalyst provided by this invention is used in a fixed-bed reactor for the catalytic gas-phase selective oxidation of isobutylene / tert-butanol to synthesize methacrolein, at a reaction temperature of 300–400°C, isobutylene / tert-butanol at 3–10 vol%, and a space velocity of 500–3000 h⁻¹. -1 Under pressures of 0.01–0.2 MPa, the isobutylene / tert-butanol conversion rate can reach 96.0–99.0%, and the selectivity for methacrolein can reach 86.1–89.1%. Under the same conditions, using a molybdenum bismuth oxygen catalyst without added hydroxysilicates, the catalytic performance is 93.2–97.2% for isobutylene / tert-butanol conversion and 83.7–86.3% for methacrolein. Using a molybdenum bismuth oxygen catalyst with added hydroxysilicates and a molybdenum bismuth oxygen catalyst without pore-expanding treatment, the catalytic performance is 92.2–93.1% for isobutylene / tert-butanol conversion and 78.6–79.4% for methacrolein. The catalyst of this invention can increase the isobutylene / tert-butanol conversion rate by up to 9.4% and the total selectivity for methacrolein and methacrylic acid by up to 7.9%. Detailed Implementation

[0059] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0060] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0061] In a preferred embodiment of the present invention, the method for preparing the molding catalyst for the selective oxidation of isobutylene / tert-butanol may include:

[0062] S1, the raw materials, including the active component source, are added to a liquid solvent and reacted at a certain temperature for a period of time. The dispersion system is then transferred to a ball mill and ball milled for a certain time.

[0063] S2, the liquid solvent is extracted, and the resulting solid material is dried at 60-150℃ to obtain the catalyst precursor;

[0064] S3, the catalyst precursor is activated in different atmospheres at 250-550°C to obtain catalyst matrix powder;

[0065] S4, a pore-expanding agent is added to the catalyst matrix powder and removed in a certain manner to obtain the catalyst molding body for selective oxidation of isobutylene / tert-butanol.

[0066] According to a preferred embodiment of the present invention, step S1 may include the following steps:

[0067] S1-1) A compound containing some metal components (the source of the active component) is added to a liquid solvent and heated to a certain temperature;

[0068] S1-2) Add the remaining dispersion system containing other active substances to the reaction system of step S1-1), and continue heating to a certain temperature to obtain a reaction solution containing precipitate;

[0069] Optionally, a certain amount of auxiliary metal element (i.e., metal auxiliary source) may be added to the reaction system in step S1-2);

[0070] Optionally, a certain amount of hydroxysilicate is added to the reaction system in step S1-2);

[0071] S1-3) The resulting dispersion system is transferred to a ball mill and ball milled for 1 to 6 hours.

[0072] According to a preferred embodiment of the present invention, the liquid solvent in step S1-1) is not particularly limited. Depending on the catalyst reaction system, any solvent commonly used in the art can be selected. According to some embodiments of the present invention, the liquid solvent is an aqueous solvent, i.e., a solvent containing water or a liquid mixture containing one or more other solvents miscible with water (such as polar organic solvents, particularly alcohols). For catalysts for the oxidation of isobutylene / tert-butanol to methacrolein and / or methacrylic acid, the solvent is preferably deionized water or a mixture of deionized water and an alcohol.

[0073] For aqueous solvents, acidic aqueous solvents are preferred. In many cases, since Bi and Mo precursor compounds are typically immiscible in a solution under the same conditions, acidic aqueous solvents are needed to promote the maximum dissolution of precursor compounds containing catalytically active components, including Mo and Bi, in the system. This promotes the formation of a homogeneous system of all catalytically active components, which is beneficial for improving catalytic performance. By using acid, the dissolution of all precursor compounds can be promoted, resulting in a final catalyst with smaller particle size and a relatively higher specific surface area. It also facilitates the uniform distribution of the catalytically active metal components throughout the catalyst bulk phase.

[0074] According to a preferred embodiment of the present invention, the acid used can be an inorganic acid, an organic acid, or a mixture of multiple acids. The inorganic acid is preferably nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid, while the organic acid is such as acetic acid, citric acid, oxalic acid, lactic acid, malonic acid, succinic acid, maleic acid, fumaric acid, malic acid, adipic acid, tartaric acid, caffeic acid, ferulic acid, or mixtures thereof. Particularly preferred are combinations of inorganic acids, inorganic acids, or acetic acid with chelated organic acids, i.e., metals that can stabilize the precursor compounds of the catalytically active component under certain acidic conditions through more than one coordinate bond in the organic acid. Further preferred are α-hydroxycarboxylic acids, dicarboxylic acids, and tricarboxylic acids, such as acetic acid, citric acid, tartaric acid, maleic acid, succinic acid, adipic acid, and oxalic acid. The amount of acid used is not particularly limited; the amount typically used in molybdenum-bismuth composite metal oxide catalysts in the art is sufficient.

[0075] According to a preferred embodiment of the present invention, the reaction time of step S1-1) is 0 to 5 hours, preferably 3 to 5 hours.

[0076] According to some embodiments of the present invention, there are no particular limitations on the methods and conditions in step S1-2). For example, the reaction system in step S1-1) can be cooled to 20-80°C, a dispersion system containing other active substances can be added to it, and the system can be heated to a certain temperature to carry out the reaction.

[0077] According to a preferred embodiment of the present invention, the reaction time of step S1-2) is 3 to 24 hours, preferably 3 to 16 hours.

[0078] According to the preparation method of the present invention, there is no particular limitation on the order of addition of the metal additives. The metal additives or their solutions can be added directly to other dispersion systems in steps S1-2), or directly to the mixed reaction solution formed, or simultaneously.

[0079] According to a preferred embodiment of the present invention, the auxiliary metal element may or may not be added to the reaction system in step S1-2). In some specific embodiments, the reaction system in step S1-2) may be cooled to 25-80°C, the auxiliary metal element may be added thereto, and the mixture may be heated to a certain temperature to continue the reaction, thereby obtaining a reaction solution containing a precipitate.

[0080] In the above technical solution, the active component source includes molybdenum-containing compounds, bismuth-containing compounds, iron-containing compounds, and cobalt-containing compounds, wherein the metal-containing compounds are selected from at least one of metal oxides, ammonium salts, nitrates, carbonates, bicarbonates, sulfates, halides, oxalates, phosphates, hydrogen phosphates, or their complexes. The complexes may, for example, be acetylacetone complexes.

[0081] In the above technical solution, the hydroxysilicate is one or a mixture of two of aluminum hydroxysilicate, magnesium hydroxysilicate, or copper hydroxysilicate, including natural minerals containing hydroxysilicate or hydroxysilicate products that have undergone certain modifications.

[0082] The selected hydroxysilicate material has a size of 20–2000 nm, preferably 50–2000 nm.

[0083] Based on the characteristics of oxidation reactions, the catalyst in the reaction bed must have sufficient bulk density to withstand the reaction pressure, while also ensuring a certain bulk density to form specific channels within the catalyst, thereby improving the utilization of the catalyst channel surface. Furthermore, for bulk-formed catalyst bodies, a suitable bulk density can also reduce catalyst costs. In a preferred embodiment of the present invention, the bulk density of the catalyst is 0.5–1.8 g / cm³. 3 Preferably, it is 0.8–1.5 g / cm³. 3 More preferably, it is 0.8–1.2 g / cm³. 3 .

[0084] Changes in specific surface area have a significant impact on catalyst activity, feed conversion rate, and target product selectivity. Therefore, in one embodiment of the present invention, the specific surface area of ​​the catalyst is 5–50 m². 2 / g; preferably 10-40m 2 / g, particularly preferably 10-30m 2 / g. Within this range, the catalyst surface facilitates effective contact between reactant molecules and the catalyst active sites, while also helping to inhibit the peroxidation of the target product, thereby improving catalyst activity and product selectivity.

[0085] The catalyst molded body exhibits high and relatively consistent mechanical strength. In a preferred embodiment of the present invention, the lateral impact strength (S) of the catalyst molded body is 10N≤S≤70N, preferably 10N≤S≤60N, and more preferably 20N≤S≤50N.

[0086] According to one embodiment of the present invention, step S2 includes:

[0087] A) Perform solid-liquid separation treatment on the reaction solution containing the precipitate;

[0088] B) The precipitate obtained is dried to obtain the catalyst precursor.

[0089] According to the preparation method of the present invention, there are no particular limitations on the treatment of step S2. For example, the reaction solution containing the precipitate can be spray-dried to obtain the precipitate, or the solid precipitate can be obtained by evaporating the solvent in the reaction solution. Finally, the catalyst precursor is dried at 60-150°C for 6-24 hours, preferably at 100-140°C for 12-24 hours, to obtain the final product.

[0090] According to some embodiments of the present invention, step S3 includes:

[0091] The catalyst precursor obtained in step S2 is placed in an air atmosphere for activation treatment to obtain the activated catalyst.

[0092] According to some embodiments of the present invention, the activation treatment includes: placing the billet in an air atmosphere, heating it to 250-350°C at a certain heating rate, and then maintaining it for a period of time with or without changing the atmosphere, preferably within the range of 0-3 hours; continuing to heat it to 400-550°C at a certain heating rate, and maintaining it for a period of time with or without changing the atmosphere, preferably within the range of 2-8 hours; and then cooling the activated billet to room temperature under the protection of adding or not adding inert gas, thus obtaining the product.

[0093] In a preferred embodiment, the billet is first placed in an air atmosphere and heated to 250-350°C at a heating rate of 1-4°C / min. After maintaining this temperature for 0-3 hours, the temperature is further increased to 400-550°C at a heating rate of 1-4°C / min. The billet is then calcined in this atmosphere for 3-5 hours and subsequently cooled to room temperature to obtain the activated molybdenum bismuth oxygen catalyst.

[0094] According to the preparation method of the present invention, there is no particular limitation on the order of addition of hydroxysilicate. For example, a certain amount of hydroxysilicate can be added first in step S1-2, or a certain amount of hydroxysilicate can be added to the dried catalyst precursor in step S2, or a certain amount of hydroxysilicate can be added to the activated matrix powder in step S3.

[0095] When adding hydroxysilicate material in process S1-2, the amount of hydroxysilicate material added is 0.1 to 11 wt% of the molybdenum-containing compound, preferably 0.15 to 7 wt%.

[0096] When a hydroxysilicate material is added in process S2, the amount of the hydroxysilicate material added is 0.1 to 7% of the content of the catalyst precursor, preferably 0.15 to 4.5%.

[0097] When hydroxysilicate material is added in process S3, the amount of hydroxysilicate material added is 0.1-9% of the catalyst matrix powder, preferably 0.15-5.5%.

[0098] According to the preparation method of the present invention, a lubricant may be optionally added, and there is no particular limitation on the order of adding the lubricant. For example, a certain amount of hydroxysilicate may be added to the dried catalyst precursor in step S2, or a certain amount of hydroxysilicate may be added to the activated matrix powder in step S3.

[0099] When a lubricant is added to the catalyst precursor, the lubricant is 0.1 to 7 wt% of the catalyst precursor, preferably 0.15 to 4.5 wt%.

[0100] When a lubricant is added to the catalyst matrix powder, the lubricant is 0.1 to 9 wt% of the catalyst matrix powder, preferably 0.15 to 5.5 wt%.

[0101] According to some embodiments of the present invention, step S4 includes:

[0102] 1) The activated catalyst matrix powder is mixed with a pore expander and then pressed into tablets or extruded to obtain a catalyst preform;

[0103] 2) The rough blank is subjected to a pore-expanding agent removal treatment to obtain the catalyst molded body for selective oxidation of isobutylene / tert-butanol.

[0104] The catalyst forming method is not particularly limited, but due to the shape requirements of the catalyst body, tableting or extrusion forming is preferred. According to a preferred embodiment of the present invention, before forming, the activated slab in step S2 is granulated into particles smaller than 20 mesh. After the crushed particles are sieved, the weight ratio of particles between 20 and 40 mesh is 10-50%, and the weight ratio of particles >40 mesh is 50-90%.

[0105] The mass ratio of the pore-expanding agent to the activated catalyst matrix powder is (2-20):(80-98), preferably (4-12):(88-96), and more preferably (6-12):(88-94).

[0106] The pore-expanding agent is an organic acid, including but not limited to one or more of stearic acid, glycolic acid, salicylic acid, malic acid, citric acid, stearic acid, tartaric acid, and citric acid.

[0107] According to an embodiment of the present invention, a high-temperature calcination method is used to remove the pore-expanding agent from the preform. In a preferred embodiment of the present invention, when using the high-temperature calcination method, the molded body should be held at a certain temperature for a period of time. This facilitates the slow removal of the pore-expanding agent from the catalyst structure, thereby avoiding rapid collapse of the catalyst structure due to excessively rapid heating and protecting the overall mechanical strength of the catalyst. In a preferred embodiment of the present invention, the selected calcination temperature is preferably 20–100°C higher than the boiling point of the pore-expanding agent and at least 50°C lower than the maximum activation temperature of the catalyst, to ensure that the heat release from the high-temperature decomposition of the pore-expanding agent during high-temperature removal does not affect the crystal phase or composition of the catalyst.

[0108] In this invention, the specific surface area was measured using the ASAP-2020 fully automated specific surface area and pore size distribution instrument from Quantachrome, USA.

[0109] The bulk density of the catalyst was determined using a PH-702 tap density meter developed by Dalian Penghui Technology Development Co., Ltd.

[0110] The lateral impact strength of the catalyst was measured using the ZQJ-III intelligent particle strength tester manufactured by Dalian Intelligent Testing Machine Factory.

[0111] Catalyst performance evaluation experiments were conducted in a single-tube reactor. The reactor tube was 4 m long with an effective length of 3.6 m and an inner diameter of 25 mm, containing a 6 mm outer diameter thermocouple. The catalyst loading was 1200 mL, with a loading height of 3.3–3.6 m. Air and isobutylene were metered by mass flow meters, and tert-butanol was metered by a precision metering pump before entering the reaction tube. A branch line was added at the inlet for gas chromatography analysis of the feed gas composition. The reaction gas underwent selective oxidation to generate the selective target product under the action of the activated catalyst. The tail gas composition was analyzed by adding a branch line at the tail gas outlet. Chromatographic analysis was performed using an Agilent 7890b gas chromatograph. All data used in the following discussion are based on carbon balance values ​​between 98% and 102%.

[0112] According to the present invention, the contact conditions can be selected within a wide range. However, in order to further improve the selectivity of methacrolein and methacrylic acid, the contact conditions preferably include: a temperature of 300–400°C, a pressure of 0.01–0.2 MPa, a reaction time of 1–48 h, and a total volume hourly space velocity (VHSV) of 500–3000 h⁻¹. -1 Preferably 800-2000h -1The molar ratio of isobutylene:oxygen:water in the raw materials is 1:1–5:2–6. Alternatively, the contact conditions include: a temperature of 300–400°C, a pressure of 0.01–0.2 MPa, a reaction time of 1–48 h, and a space velocity of 500–3000 h⁻¹. -1 Preferably 800-2000h -1 The molar ratio of tert-butanol to oxygen in the raw materials is 1:1 to 5:1 to 5.

[0113] The calculations for the conversion rate of reactants and the selectivity of products during the reaction process are as follows:

[0114]

[0115]

[0116]

[0117] Example 1

[0118] Add 960 mL of ethanol, 30 g of methylethanolamine, 60 g of aminosilane coupling agent, and 600 g of 10 wt% sodium silicate solution to a 3 L round-bottom flask, mix well, add aluminum sulfate aqueous solution at 50 °C, control the molar ratio of aluminum sulfate solution to sodium silicate to be 1:3, stir and react at 50 °C for 1 h, precipitate, filter, and obtain aluminum silicate; continue to wash the aluminum silicate particles obtained in the above steps repeatedly with anhydrous ethanol 3 times until the pH of the washing solution is 7-8; place the washed nano aluminum silicate particles in an 80 °C oven and dry for 10 h to obtain surface amino-modified nano hydroxyl aluminum silicate particles with a particle size of 20-50 nm.

[0119] 1000g of ammonium heptamolybdate was dissolved in 2000g of deionized water at 60℃ to obtain solution A; 229g of bismuth nitrate, 381g of ferric nitrate, 961g of cobalt nitrate, 37g of cesium nitrate, and 38g of boric acid were dissolved in 1840g of 5% dilute nitric acid aqueous solution at 60℃ to obtain solution B; 62g of antimony pentoxide and 62g of amino-modified nano-hydroxyaluminate silicate were dispersed in 100mL of ethanol to prepare dispersion system C; solution B and dispersion system C were added dropwise to solution A, respectively. The slurry was stirred and matured at 60℃ for 4h, and then transferred to a ball mill and ball-milled for 4h. The obtained slurry was kept at 100℃ for 24 hours, and the solvent components were evaporated by spray drying. The resulting solid was calcined in air at a heating rate of 1.5℃ / min to 300℃ for 3 hours, and then calcined at a heating rate of 3℃ / min to 500℃ for 5 hours to obtain catalyst matrix powder. 62g of graphite and 183g of glycolic acid were added to the catalyst matrix powder and sieved and mixed evenly. The mass ratio of glycolic acid to catalyst matrix powder was 10:90, and the mass ratio of hydroxysilicate to graphite was 1:1. The total mass of both accounted for 6.3% of the mass of the mixed sample. 800g of the obtained catalyst mixture powder and 20g of methylcellulose powder were thoroughly mixed, and 200g of an aqueous solution containing 4g of methylcellulose was added. The mixture was then kneaded using a mixer to form a clay-like substance. The obtained amorphous compound was extruded into hollow cylindrical catalysts with a four-petal flower-shaped cross-section using a screw extruder. The extruded strips were then cut into particles with an outer diameter of 5 mm, a height of 4 mm, and an inner diameter of 2 mm using a roller mill. The resulting molded products were dried at 110°C, then heated to 175°C at a rate of 2°C / min and held at this temperature for 6 hours. Subsequently, the temperature was increased to 185°C at a rate of 2°C / min and held at this temperature for another 6 hours. The active component of the obtained catalyst was Mo. 12 Bi1Fe2Co7Sb 0.9 Cs 0.4 B 0.1 The composition of the catalyst was calculated based on the input amounts of each element in the raw materials. The bulk density of the catalyst is 1.18 g / cm³. 3 Its specific surface area is 18.4 m². 2 / g, pore volume is 0.12m 3 / g, with a lateral impact strength of 36N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0120] Comparative Example 1

[0121] Except for the absence of hydroxysilicate in the catalyst preparation process, the other steps were the same as in Example 1. The resulting catalyst had a bulk density of 1.16 g / cm³. 3 Its specific surface area is 16.5 m². 2 / g, pore volume is 0.11m 3 / g, with a lateral impact strength of 27N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0122] Example 2

[0123] Add 960 mL of ethanol, 30 g of methylethanolamine, 60 g of aminosilane coupling agent, and 600 g of 10 wt% sodium silicate solution to a 3 L round-bottom flask and mix well. Add aluminum sulfate aqueous solution and magnesium sulfate aqueous solution at 50 °C, controlling the molar ratio of aluminum sulfate solution, magnesium sulfate aqueous solution and sodium silicate to be 1:5. Stir and react at 50 °C for 1 h, precipitate, filter, and obtain magnesium aluminum silicate. Continue to wash the magnesium aluminum silicate particles obtained in the above steps repeatedly with anhydrous ethanol 3 times until the pH of the washing solution is 7-8. Place the washed nano-magnesium aluminum silicate particles in an 80 °C oven and dry for 10 h to obtain surface amino-modified nano-hydroxyl magnesium aluminum silicate particles with a particle size of 50-100 nm.

[0124] 1000g of ammonium heptamolybdate was dissolved in 2000g of deionized water at 60℃ to obtain solution A; 137g of bismuth nitrate, 419g of ferric nitrate, 824g of cobalt nitrate, 37g of cesium nitrate, and 38g of boric acid were dissolved in 1840g of 5% dilute nitric acid aqueous solution at 60℃ to obtain solution B; 62g of antimony pentoxide and 31g of magnesium aluminum silicate hydroxysilicate were dispersed in 100mL of ethanol to prepare dispersion system C; solutions B and dispersion system C were added dropwise to solution A respectively. The slurry was stirred and matured at 60℃ for 4h. It was then transferred to a ball mill and ball-milled for 4h. The resulting slurry was kept at 140℃ for 24h to evaporate the solvent components; the resulting solid was calcined in air at a heating rate of 1℃ / min to 300℃ for 3h, and then calcined at a heating rate of 2.5℃ / min to 500℃ for 5h to obtain catalyst matrix powder. 62g of graphite and 92g of salicylic acid were added to the catalyst matrix powder and sieved and mixed evenly. The mass ratio of salicylic acid to catalyst matrix powder was 5:95, and the mass ratio of hydroxysilicate to graphite was 1:2. The total mass of both accounted for 4.8% of the mixed sample. After uniform mixing, the mixture was stamped into hollow cylindrical catalyst particles with an outer diameter of 5mm, a height of 4mm, and an inner diameter of 2mm. The resulting molded particles were heated to 185℃ at a rate of 2℃ / min and held at this temperature for 6 hours. Then, the temperature was increased to 250℃ at a rate of 2℃ / min and held at this temperature for another 2 hours. The active component of the obtained catalyst was Mo. 12 Bi 0.6 Fe 2.2 Co6Sb 0.9 Cs 0.4 B 1.0The composition of the catalyst was calculated based on the amount of each element input. The bulk density of the catalyst is 1.17 g / cm³. 3 Its specific surface area is 19.0 m². 2 / g, pore volume is 0.13m 3 / g, with a lateral impact strength of 38N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0125] Comparative Example 2

[0126] Except for the absence of hydroxysilicate in the catalyst preparation process, the other steps were the same as in Example 2. The catalyst bulk density was 1.17 g / cm³. 3 Its specific surface area is 17.2 m². 2 / g, pore volume is 0.12m 3 / g, with a lateral impact strength of 26N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0127] Example 3

[0128] Add 960 mL of ethanol, 30 g of methylethanolamine, 60 g of aminosilane coupling agent, and 600 g of 10 wt% sodium silicate solution to a 3 L round-bottom flask and mix well. Add copper sulfate aqueous solution at 50 °C, controlling the molar ratio of copper sulfate solution to sodium silicate to be 1:6. Stir the reaction at 50 °C for 1 h, precipitate, filter, and obtain copper silicate. Continue to wash the copper silicate particles obtained in the above steps repeatedly with anhydrous ethanol 3 times until the pH of the washing solution is 7-8. Place the washed nano-copper silicate particles in an 80 °C oven and dry for 10 h to obtain surface amino-modified nano-hydroxy copper silicate particles with a particle size of 100-200 nm.

[0129] 1000g of ammonium heptamolybdate was dissolved in 2000g of deionized water at 60℃ to obtain solution A; 137g of bismuth nitrate, 419g of ferric nitrate, 824g of cobalt nitrate, 37g of cesium nitrate, and 38g of boric acid were dissolved in 1840g of 5% dilute nitric acid aqueous solution at 60℃ to obtain solution B; 62g of antimony pentoxide and 62g of nano-copper hydroxysilicate were dispersed in 100mL of ethanol to prepare dispersion system C; solutions B and dispersion system C were added dropwise to solution A respectively. The slurry was stirred and matured at 60℃ for 4h. It was then transferred to a ball mill and ball-milled for 4h. The resulting slurry was spray-dried at 130℃ to remove the solvent components; the resulting solid was calcined in air at a heating rate of 2℃ / min to 300℃ for 3h, and then calcined at a heating rate of 4℃ / min to 500℃ for 5h to obtain catalyst matrix powder. 31g of graphite and 229g of salicylic acid were added to the catalyst matrix powder and sieved and mixed thoroughly. The mass ratio of salicylic acid to catalyst matrix powder was 12:88, and the mass ratio of hydroxysilicate to graphite was 2:1. The total mass of both accounted for 4.8% of the mixed sample. After thorough mixing, the powder was pressed into hollow cylindrical catalysts with a five-petal flower-shaped cross-section, an outer diameter of 5mm, a height of 4mm, and an inner diameter of 2mm. The resulting molded product was heated to 200℃ at a rate of 2℃ / min and held at this temperature for 6 hours. The active component of the obtained catalyst was Mo. 12 Bi 0.6 Fe 2.2 Co6Sb 0.9 Cs 0.4 B 1.0 The composition of the catalyst was calculated based on the amount of each element input. The bulk density of the catalyst is 1.12 g / cm³. 3 Its specific surface area is 22.3 m². 2 / g, pore volume 0.15m 3 / g, with a lateral impact strength of 29N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0130] Comparative Example 3

[0131] Except for the absence of hydroxysilicate in the catalyst preparation process, the other operations were the same as in Example 3. The catalyst bulk density was 1.09 g / cm³. 3 Its specific surface area is 21.8 m². 2 / g, pore volume is 0.14m 3 / g, with a lateral impact strength of 24N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 2.

[0132] Example 4

[0133] 1000g of ammonium heptamolybdate was dissolved in 2000g of deionized water at 60℃ to obtain solution A; 274g of bismuth nitrate, 705g of ferric nitrate, 349g of cobalt nitrate, 37g of cesium nitrate, and 38g of boric acid were dissolved in 1840g of 5% dilute nitric acid aqueous solution at 60℃ to obtain solution B; 62g of antimony pentoxide and 56g of commercially available aluminum hydroxysilicate powder (particle size 1000-2000nm) were dispersed in 100mL of ethanol to prepare dispersion system C; solution B and dispersion system C were added dropwise to solution A respectively. The slurry was stirred and matured at 60℃ for 4h. It was then transferred to a ball mill and ball-milled for 4h. The obtained slurry was kept at 100℃ for 24 hours to evaporate the solvent components. The resulting solid was calcined in air at a heating rate of 2℃ / min to 300℃ for 3 hours, followed by calcination at 3℃ / min to 500℃ for 5 hours to obtain catalyst matrix powder. 14g of graphite and 145g of citric acid were added to the catalyst matrix powder and sieved and mixed thoroughly. The mass ratio of citric acid to catalyst matrix powder was 8:92, and the mass ratio of hydroxysilicate to graphite was 4:1. The total mass of both accounted for 3.9% of the mixed sample. After thorough mixing, the mixture was stamped into hollow cylindrical catalysts with a four-petal flower-shaped cross-section, an outer diameter of 5mm, a height of 4mm, and an inner diameter of 2mm. The resulting molded product was heated to 190℃ at a rate of 2℃ / min and held at this temperature for 6 hours, then heated to 220℃ at a rate of 2℃ / min and held at this temperature for 2 hours. The active component of the obtained catalyst was Mo. 12 Bi 1.2 Fe 3.7 Co4Sb 0.9 Cs 0.4 B 1.0 The composition of the catalyst was calculated based on the input amounts of each element in the raw materials. The bulk density of the catalyst is 1.20 g / cm³. 3 Its specific surface area is 21.4 m². 2 / g, pore volume is 0.17m 3 / g, with a lateral impact strength of 31N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0134] Comparative Example 4

[0135] Except for the catalyst being formed into a hollow cylindrical catalyst body by stamping (with an outer diameter of 5 mm, a height of 4 mm, and an inner diameter of 2 mm, and without the addition of a pore-expanding agent during the catalyst forming process), the other implementation steps are the same as in Example 4. The catalyst bulk density is 1.32 g / cm³. 3 Its specific surface area is 12.6 m². 2 / g, pore volume 0.08m 3 / g, with a lateral impact strength of 28N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0136] Example 5

[0137] 1000g of ammonium heptamolybdate was dissolved in 2000g of deionized water at 60℃ to obtain solution A; 228g of bismuth nitrate, 705g of ferric nitrate, 824g of cobalt nitrate, 52g of rubidium nitrate, and 38g of boric acid were dissolved in 1840g of 5% dilute nitric acid aqueous solution at 60℃ to obtain solution B; 62g of antimony pentoxide and 62g of commercially available aluminum hydroxysilicate powder (particle size 800-1000nm) were dispersed in 100mL of ethanol to prepare dispersion system C; solution B and dispersion system C were added dropwise to solution A respectively. The slurry was stirred and matured at 60℃ for 4h, and then ball-milled in a ball mill for 4h. The resulting slurry was spray-dried at 130℃; the resulting solid was calcined in air at a heating rate of 1℃ / min to 300℃ for 3h, and then calcined at a heating rate of 4℃ / min to 500℃ for 5h to obtain catalyst matrix powder. 183g of stearic acid was added to the catalyst matrix powder and sieved to mix thoroughly. The mass ratio of stearic acid to catalyst matrix powder was 10:90. After thorough mixing, the mixture was pressed into a hollow cylindrical catalyst with an outer diameter of 5mm, a height of 4mm, and an inner diameter of 2mm. The resulting molded product was heated to 195℃ at a rate of 2℃ / min and held at this temperature for 6 hours. Then, the temperature was increased to 230℃ at a rate of 2℃ / min and held at this temperature for 6 hours. The active component of the obtained catalyst consisted of Mo. 12 Bi1Fe 3.7 Co6Sb 0.9 Rb 0.8 B 1.0 The composition of the catalyst was calculated based on the input amounts of each element in the raw materials. The bulk density of the catalyst is 1.20 g / cm³. 3 Its specific surface area is 21.4 m². 2 / g, pore volume 0.15m 3 / g, with a lateral impact strength of 33N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0138] Comparative Example 5

[0139] Except for the absence of hydroxysilicate and pore-expanding agent during catalyst forming and the lack of pore-expanding operation, the other implementation steps were the same as in Example 5. The catalyst bulk density was 1.32 g / cm³. 3 Its specific surface area is 10.6 m². 2 / g, pore volume 0.05m 3 / g, with a lateral impact strength of 30N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0140] Example 6

[0141] The catalysts prepared in Examples 1-5 and Comparative Examples 1-5 were used as selective oxidation catalysts for the oxidation of isobutylene / tert-butanol to methacrolein / acid, and their performance was tested at a reaction temperature of 360°C. The catalytic results, analyzed by online gas chromatography, are shown in Table 1. The evaluation methods used were, but not limited to, the above conditions.

[0142] Table 1 Catalytic performance of the catalyst for the selective oxidation of isobutene / tert-butanol to methacrolein / acid

[0143]

[0144]

[0145] The raw material is isobutylene: oxygen: nitrogen: water;

[0146] The raw materials are tert-butanol, oxygen, nitrogen, and water.

[0147] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0148] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A molding catalyst for selective oxidation of isobutylene / tert-butanol, comprising an active component and a hydroxysilicate, wherein the active component comprises a molybdenum-bismuth composite metal oxide, and the hydroxysilicate is at least one of aluminum hydroxysilicate, magnesium hydroxysilicate, copper hydroxysilicate, and a natural mineral containing hydroxysilicate, wherein the hydroxysilicate comprises 0.1 to 5 wt% of the molding catalyst; The shaped catalyst is prepared through the following steps: S1, adding raw materials, including the active component source, to a liquid solvent for reaction, followed by ball milling; S2, separating the solid substances from the reaction product of step S1 and drying them to obtain a catalyst precursor; S3, activating the catalyst precursor to obtain a catalyst matrix powder; S4, mixing the catalyst matrix powder with a pore-expanding agent, shaping it to obtain a catalyst preform, and then performing pore-expanding treatment to obtain the shaped catalyst; wherein... Hydroxysilicates are added to the raw materials in step S1 and / or the catalyst precursor in step S2 and / or the catalyst matrix powder in step S3.

2. The molding catalyst according to claim 1, characterized in that: The molybdenum-bismuth composite metal oxide includes at least molybdenum, bismuth, iron, and cobalt; and / or, Optionally, the hydroxysilicate is surface-modified; and / or, The hydroxysilicate is 0.1–4 wt% of the molding catalyst; and / or, The active component includes a metal additive selected from at least one of cesium, antimony, rubidium, potassium, vanadium, magnesium, tungsten, and nickel; and / or, The molding catalyst includes a lubricant, which is at least one of graphite, starch, and stearate.

3. The molding catalyst according to claim 2, characterized in that: The lubricant is 0.1 to 8 wt% of the molding catalyst.

4. The molding catalyst according to claim 3, characterized in that: The lubricant is 0.1 to 4 wt% of the molding catalyst.

5. The molding catalyst according to any one of claims 1 to 4, characterized in that: The lateral impact strength of the molded catalyst is 10–70 N; and / or, The specific surface area of ​​the shaped catalyst is 5-50 m². 2 / g; and / or, The bulk density of the shaped catalyst is 0.5–1.8 g / cm³. 3 ; and / or, The pore volume of the shaped catalyst is 0.05–0.20 cm³. 3 / g.

6. The molding catalyst according to claim 5, characterized in that... The lateral impact strength of the molded catalyst is 10–60 N; and / or, The specific surface area of ​​the shaped catalyst is 10–40 m². 2 / g; and / or, The bulk density of the shaped catalyst is 0.8–1.5 g / cm³. 3 ; and / or, The pore volume of the shaped catalyst is 0.08–0.15 cm³. 3 / g.

7. A method for preparing a shaped catalyst according to any one of claims 1 to 6, comprising the following steps: S1, raw materials, including the active component source, are added to a liquid solvent for reaction, and then ball milled; S2, the solid material in the reaction product of step S1 is separated and dried to obtain the catalyst precursor; S3, activate the catalyst precursor to obtain catalyst matrix powder; S4, the catalyst matrix powder is mixed with the pore-expanding agent, and after molding, a catalyst preform is obtained. Then, the pore-expanding treatment is performed to obtain the shaped catalyst. in, Hydroxysilicates are added to the raw materials in step S1 and / or the catalyst precursor in step S2 and / or the catalyst matrix powder in step S3.

8. The preparation method according to claim 7, characterized in that... Step S1 includes: S1-1) Mix a portion of the active ingredient source with a liquid solvent and heat; S1-2) Add the remaining active ingredient source and continue heating; S1-3) Perform ball milling; The active component sources include molybdenum-containing compounds, bismuth-containing compounds, iron-containing compounds, and cobalt-containing compounds; Optionally, a metal additive source is added in step S1-2).

9. The preparation method according to claim 8, characterized in that: In step S1-1), the liquid solvent is an aqueous solvent; In step S1-1), the heating temperature is 20–80℃ and the heating time is 0–5h; In steps S1-2), the heating temperature is 40-80℃ and the heating time is 3-24h; Optionally, a hydroxysilicate is added in step S1-2), wherein when the hydroxysilicate is added in step S1-2), the hydroxysilicate is 0.1 to 11 wt% of the molybdenum-containing compound.

10. The preparation method according to claim 9, characterized in that: In step S1-1), the heating temperature is 40-60℃ and the heating time is 3-5 hours; In steps S1-2), the heating temperature is 50-80℃ and the heating time is 3-16h; The hydroxysilicate is 0.15–7 wt% of the molybdenum-containing compound.

11. The preparation method according to claim 7, characterized in that... In step S2: Dry at 60–150℃ for 6–24 hours; and / or, Optionally, a hydroxysilicate is added to the catalyst precursor, wherein when a hydroxysilicate is added to the catalyst precursor, the hydroxysilicate is 0.1 to 7 wt% of the catalyst precursor; Optionally, a lubricant is added to the catalyst precursor. When a lubricant is added to the catalyst precursor, the lubricant is 0.1 to 7 wt% of the catalyst precursor.

12. The preparation method according to claim 11, characterized in that: Dry at 100–140℃ for 12–24 hours; and / or, Hydroxysilicate constitutes 0.15–4.5 wt% of the catalyst precursor; The lubricant is 0.15–4.5 wt% of the catalyst precursor.

13. The preparation method according to claim 7, characterized in that... In step S3: The activation treatment includes: heating to 250–350°C in an air atmosphere at a heating rate of 1–4°C / min, and then holding for 0–3 hours with or without changing the atmosphere; continuing to heat to 400–550°C at a heating rate of 1–4°C / min, and holding for a period of time with or without changing the atmosphere, ranging from 2 to 8 hours; then cooling to room temperature with or without the addition of an inert gas; and / or, Optionally, hydroxysilicates are added to the catalyst matrix powder, wherein when hydroxysilicates are added to the catalyst matrix powder, the hydroxysilicates are 0.1 to 9 wt% of the catalyst matrix powder; Optionally, a lubricant may be added to the catalyst matrix powder. When a lubricant is added to the catalyst matrix powder, the lubricant is 0.1 to 9 wt% of the catalyst matrix powder.

14. The preparation method according to claim 13, characterized in that: Hydroxysilicate comprises 0.15–5.5 wt% of the catalyst matrix powder; The lubricant is 0.15 to 5.5 wt% of the catalyst matrix powder.

15. The preparation method according to claim 7, characterized in that... In step S4: The mass ratio of the pore-expanding agent to the catalyst matrix powder is (2-20):(80-98); and / or, The pore-expanding agent is an organic acid, selected from at least one of stearic acid, glycolic acid, salicylic acid, malic acid, tartaric acid, citric acid, and citric acid; and / or, When using extrusion molding, after mixing the catalyst matrix powder and pore expander, a binder and water are added before molding; and / or, The hole-expanding process is performed by high-temperature calcination.

16. The preparation method according to claim 15, characterized in that: The mass ratio of the pore-expanding agent to the catalyst matrix powder is (4-12):(88-96); The binder is 1-4.5 wt% of the catalyst matrix powder, the binder is 10-18 wt% of the added water, and the binder is guar gum powder, cellulose and its derivatives; The high-temperature calcination temperature is 20–100°C higher than the boiling point of the pore-expanding agent and at least 50°C lower than the maximum activation temperature of the catalyst.

17. The shaped catalyst obtained by the preparation method according to any one of claims 7 to 16.

18. A method for oxidizing isobutylene / tert-butanol to produce methacrolein / acid, comprising oxidizing isobutylene / tert-butanol in the presence of a catalyst, wherein the catalyst is a molding catalyst according to any one of claims 1 to 6 or a molding catalyst obtained by any one of claims 7 to 16.

19. The method for producing methacrolein / acid by oxidation of isobutylene / tert-butanol according to claim 18, characterized in that: The reaction temperature is 300–400℃, the pressure is 0.01–0.2 MPa, the volume fraction of isobutylene or tert-butanol is 3–10%, and the total volume hourly space velocity of the feedstock is 500–3000 h⁻¹. -1 .

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