A heterogeneous ammoximation catalyst, its preparation and use

Abstract

This invention provides a heterogeneous ammonium oximation catalyst, its preparation method, and its application, belonging to the field of catalyst molding. The heterogeneous ammonium oximation catalyst of this invention comprises the following components: MOR molecular sieve raw powder, waste acid mother liquor, pore-forming agent, and binder, in a mass ratio of 1:(1-50):(2-10):(50-100); wherein the modifier is one or more of boric acid, ammonia, ammonium nitrate, and ammonium chloride; the heterogeneous ammonium oximation catalyst is obtained through a molding process. This invention significantly improves the uniform distribution of Ti active sites in the catalyst and effectively reduces waste acid emissions by using a one-pot post-processing method to prepare the Ti-MOR catalyst mother liquor instead of the acid added during the molding process. In the ammoxidation reactions of various cycloalkanones, it effectively improves the conversion rate of cycloalkanones and the selectivity of cycloalkanoximes.

Description

Technical Field

[0001] This invention belongs to the field of catalyst forming, specifically relating to a heterogeneous ammonium oxime catalyst, its preparation method, and its application. Background Technology

[0002] Compared to traditional homogeneous ammonium oximation catalysts, heterogeneous ammonium oximation catalysts for cycloalkanone ammoxidation have higher requirements for the distribution of Ti sites after molding. This is mainly because the industrial TS-1 catalyst is synthesized in situ, with Ti sites uniformly dispersed within the molecular sieve framework. However, the industrial preparation of heterogeneous ammonium oximation catalysts primarily uses a two-step post-treatment method to replenish titanium active sites. During molding, a large number of Ti active sites are covered, resulting in low actual Ti utilization. Therefore, developing and preparing highly efficient heterogeneous ammonium oximation molding catalysts can effectively improve the utilization rate of active centers and reduce wastewater discharge throughout the preparation and molding process, which is of great significance for promoting the green development of the nylon industry.

[0003] Existing technologies, such as patent CN106964400A, disclose a method for forming titanium-silicon molecular sieves, a forming catalyst, and its application, as well as a method for cyclohexanone oxidation. These methods improve the selectivity of the target product by replacing the water added during the forming process with the crystallization mother liquor of the titanium-silicon molecular sieve. However, they do not solve the problem of titanium active sites being covered during the forming process. Patent CN120421034A discloses a one-pot post-processing method for preparing Ti-MOR catalysts and its application. This method does not involve catalyst forming; it uses a one-step liquid-phase titanium-supported process with acid and titanium source co-treatment agents to obtain the molecular sieve catalyst mother liquor. However, the production process generates a large amount of waste acid, which needs to be treated before discharge, increasing operating costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a heterogeneous ammonium oxime catalyst, its preparation method, and its applications. The objective of this invention is to solve the problems of uneven Ti site dispersion, loss of active sites, and excessive waste acid discharge by replacing the acid solution added during the molding process with a one-pot post-processing method for preparing the Ti-MOR catalyst mother liquor. A further objective of this invention is to effectively create pores in the molecular sieve by controlling the proportion of added additives, reducing pore blockage by binders, and solving the problem of Ti active sites being covered.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, in a mass ratio of 1: (1-50): (2-10): (50-100); wherein the modifier is one or more of boric acid, ammonia, ammonium nitrate, and ammonium chloride.

[0006] This invention uses the waste acid generated during the one-pot post-processing preparation of Ti-MOR catalyst as the waste acid mother liquor. Utilizing the abundant crystal grains and crystalline structural units contained within, it effectively promotes the dispersion of Ti active sites, reduces the loss of active sites, and enables the formation of four-coordinated framework titanium. It employs B or NH4+-containing materials. 4+ Modifiers can effectively improve the bonding between Ti sites and the molecular sieve framework. By adding auxiliary modifiers and binders, and controlling the mass ratio of addition, it is beneficial to the mesoporous formation of heterogeneous ammonium oximation catalysts, reducing the blockage of pores during the molding process promoted by binders, promoting the exposure of more Ti active sites and their dispersion on the catalyst surface, and at the same time, the binder can prevent the internal collapse of crystals during the mesoporous formation process, ensuring that the heterogeneous ammonium oximation catalyst has good mechanical strength.

[0007] Preferably, the heterogeneous ammonium oxime catalyst comprises the following components: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, in a mass ratio of 1: (10-40): (4-8): (60-90).

[0008] Preferably, the adhesive is one or more of boehmite, kaolin, and silica sol.

[0009] Preferably, the acid concentration in the waste acid mother liquor is 1-5 mol / L and the titanium concentration is 0.1-2 mol / L.

[0010] Preferably, the acid source in the waste acid mother liquor is one or more of nitric acid, acetic acid, hydrochloric acid, sulfuric acid, formic acid, and citric acid; and the titanium source is one or more of titanium tetrachloride, titanium powder, tetraethyl titanate, and tetrabutyl titanate.

[0011] On the other hand, the present invention provides a method for preparing the heterogeneous ammonium oximation catalyst based on the above, comprising the following steps: mixing MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, heating, drying and calcining, and obtaining the heterogeneous ammonium oximation catalyst through molding treatment.

[0012] Preferably, the waste acid mother liquor is obtained from the waste acid produced in the one-pot post-processing preparation of Ti-MOR catalyst.

[0013] Preferably, in the above steps, the heating temperature is 80-150℃ and the calcination temperature is 400-600℃; the forming process includes one or more of extrusion, spraying, ball rolling, and tableting.

[0014] Preferably, the heterogeneous ammonium oxime catalyst has a particle size of 0.1 μm-1 mm.

[0015] On the other hand, the present invention provides an application of the above-mentioned heterogeneous ammonium oxime catalyst in the ammoxidation of cycloalkanes. In the ammoxidation reaction of cycloalkanes, the heterogeneous ammonium oxime catalyst of the present invention, with cyclopentanone, cyclohexanone, or cycloheptanone as the raw materials, achieves a cycloalkanone conversion rate of 99.9% and a cycloalkane oxime selectivity of over 99.6%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention uses a one-pot post-processing method to prepare the mother liquor for Ti-MOR catalyst, replacing the acid solution added during the molding process. This effectively reduces waste acid emissions and is more suitable for industrial production. This invention utilizes B or NH4+ in the modifier... 4+ This invention effectively improves the bonding between Ti sites and the molecular sieve framework, reduces pore blockage by binders, and promotes the dispersion of active sites on the catalyst surface. The heterogeneous ammoniation oxime-forming catalyst of this invention is widely applicable to the ammoxidation reactions of various cycloalkanones, effectively improving reaction efficiency, enabling cycloalkanone conversion to reach 99.9% and cycloalkane oxime selectivity to reach over 99.6%. Attached Figure Description

[0017] Figure 1 The image shows the ultraviolet absorption spectrum of the shaped catalyst prepared in this invention after grinding. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0019] General Implementation Examples A heterogeneous ammonium oxime catalyst comprises the following components: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, in a mass ratio of 1: (1-50): (2-10): (50-100).

[0020] In some preferred embodiments of the present invention, the heterogeneous ammonium oxime catalyst comprises the following components: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, in a mass ratio of 1: (10-40): (4-8): (60-90).

[0021] In some more preferred embodiments of the present invention, the modifier is one or more of boric acid, ammonia, ammonium nitrate, and ammonium chloride.

[0022] In some more preferred embodiments of the present invention, the modifier is boric acid or ammonium chloride.

[0023] In some preferred embodiments of the present invention, the adhesive is one or more of boehmite, kaolin, and silica sol.

[0024] In some more preferred embodiments of the present invention, the adhesive is boehmite or kaolin.

[0025] In some preferred embodiments of the present invention, the acid concentration in the waste acid mother liquor is 1-5 mol / L, and the titanium concentration is 0.1-2 mol / L. The present invention regulates the degree of dealumination by controlling the strength of the acid source in the waste acid mother liquor, thereby promoting the formation of more Ti active sites; and further regulates the content of the active component Ti by utilizing the degree of hydrolysis or solubility of the titanium source in the acid, thus improving catalytic activity.

[0026] In some more preferred embodiments of the present invention, the acid concentration in the waste acid mother liquor is 2-4 mol / L and the titanium concentration is 0.5-1.6 mol / L.

[0027] In some preferred embodiments of the present invention, the acid source in the waste acid mother liquor is one or more of nitric acid, acetic acid, hydrochloric acid, sulfuric acid, formic acid, and citric acid; the titanium source is one or more of titanium tetrachloride, titanium powder, tetraethyl titanate, and tetrabutyl titanate.

[0028] In some more preferred embodiments of the present invention, the acid source in the waste acid mother liquor is one or more of nitric acid, acetic acid, and hydrochloric acid; the titanium source is one or more of titanium tetrachloride, titanium powder, and tetraethyl titanate.

[0029] A method for preparing a heterogeneous ammonium oximation catalyst includes the following steps: mixing MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, heating, drying, and calcining, and obtaining the heterogeneous ammonium oximation catalyst through molding treatment.

[0030] The waste acid mother liquor is obtained from the waste acid produced in the one-pot post-processing preparation of Ti-MOR catalyst.

[0031] In some preferred embodiments of the present invention, the heating temperature is 80-150°C and the calcination temperature is 400-600°C.

[0032] In some more preferred embodiments of the present invention, the heating temperature is 100-150°C and the calcination temperature is 450-600°C.

[0033] In some preferred embodiments of the present invention, the molding process includes one or more of extrusion, spraying, ball rolling, and tableting.

[0034] In some more preferred embodiments of the present invention, the molding process is spray molding.

[0035] In some preferred embodiments of the present invention, the particle size of the heterogeneous ammonium oximation catalyst is 0.1 μm-1 mm. The present invention can effectively improve the conversion rate and the selectivity of the target product by controlling the particle size of the heterogeneous ammonium oximation catalyst. When the particle size of the catalyst is too large, although it does not affect the adsorption of cycloalkanones by the catalyst, the conversion efficiency decreases significantly, resulting in a decrease in the diffusion effect of both reactants and products per unit time, making it difficult to improve the conversion rate and the selectivity of the target product.

[0036] In some more preferred embodiments of the present invention, the particle size of the heterogeneous ammonium oxime catalyst is 1 μm-1 mm.

[0037] The application of a heterogeneous ammoniation catalyst in the ammoxidation of cycloalkanes, wherein the feedstocks for the ammoxidation reaction include, but are not limited to, cyclopentanone, cyclohexanone, and cycloheptanone.

[0038] The heterogeneous ammoniation catalyst of this invention was tested in the ammoxidation reaction of cycloalkanes. Results showed that it effectively improved the conversion rate and the selectivity of the target product; the conversion rate of cycloalkanones reached 99.9%, and the selectivity of cycloalkanes oximes reached over 99.6%. Figure 1 As shown, the UV absorption spectrum of the shaped catalyst prepared by this invention after grinding shows that 210 nm is the 210 nm region of the four-coordinated titanium active species within the framework. This invention can effectively promote the binding of Ti sites with the molecular sieve framework and promote the dispersion of active sites on the catalyst surface.

[0039] Example 1 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, boric acid, and boehmite; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 1 mol / L and a titanium concentration of 0.5 mol / L; the modifier is boric acid, and the binder is boehmite; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, boric acid, and boehmite is 1: 10: 4: 60; S2: MOR molecular sieve raw powder, waste acid mother liquor, boric acid, and pseudoboehmite are mixed in a mass ratio, heated at 100℃, dried, calcined at 550℃, and then spray-molded to obtain microspherical heterogeneous ammonium oxime catalyst with a particle size of 10-200μm. S3: The obtained catalyst was reacted in the heterogeneous cyclopentanone ammoxidation for 96 h.

[0040] Example 2 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, ammonium nitrate, and kaolin; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 5 mol / L and a titanium concentration of 2 mol / L; the modifier is ammonium nitrate, and the binder is kaolin; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, ammonium nitrate, and kaolin is 1: 40: 8: 90; S2: MOR molecular sieve raw powder, waste acid mother liquor, ammonium nitrate and kaolin are mixed in a mass ratio, heated at 150℃, dried and calcined at 400℃, and then extruded to obtain strip-shaped heterogeneous ammonium oxime catalyst with a particle size of 1-5mm. S3: The obtained catalyst was reacted in the heterogeneous cyclohexanone ammoxidation for 96 h.

[0041] Example 3 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride, and silica sol; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 2 mol / L and a titanium concentration of 1 mol / L; the modifier is ammonium chloride, and the binder is silica sol; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride, and silica sol is 1: 20: 6: 70; S2: MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride and silica sol are mixed in a mass ratio, heated at 130℃, dried and calcined at 600℃, and then sphericalized heterogeneous ammonium oxime catalyst with a particle size of 500μm-1mm is obtained by spherical molding. S3: The obtained catalyst was reacted in the heterogeneous cycloheptanone ammoxidation for 96 h.

[0042] Example 4 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, ammonia water, and pseudoboehmite; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 4 mol / L and a titanium concentration of 1.2 mol / L; the modifier is ammonia water, and the binder is pseudoboehmite; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, ammonia water, and pseudoboehmite is 1:30:7:80; S2: MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride and silica sol are mixed in a mass ratio, heated at 140℃, dried and calcined at 500℃, and then processed by spray molding and ball rolling to obtain microspherical heterogeneous ammonium oxime catalyst with a particle size of 200-500μm. S3: The obtained catalyst was reacted in the heterogeneous cyclopentanone ammoxidation for 96 h.

[0043] Comparative Example 1 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, boric acid, and boehmite; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 1 mol / L and a titanium concentration of 0.5 mol / L; the modifier is boric acid, and the binder is boehmite; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, boric acid, and boehmite is 1: 60: 2: 60; S2: MOR molecular sieve raw powder, waste acid mother liquor, boric acid, and pseudoboehmite are mixed in a mass ratio, heated at 100℃, dried, calcined at 550℃, and then spray-molded to obtain microspherical heterogeneous ammonium oxime catalyst with a particle size of 10-200μm. S3: The obtained catalyst was reacted in the heterogeneous cyclopentanone ammoxidation for 96 h.

[0044] Comparative Example 2 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, and kaolin; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 5 mol / L and a titanium concentration of 2 mol / L; the binder is kaolin; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, and kaolin is 1:40:90; S2: MOR molecular sieve raw powder, waste acid mother liquor and kaolin are mixed in a mass ratio, heated at 150℃, dried and calcined at 400℃, and then extruded to obtain strip-shaped heterogeneous ammonium oxime catalyst with a particle size of 1-5mm. S3: The obtained catalyst was reacted in the heterogeneous cyclohexanone ammoxidation for 96 h.

[0045] Comparative Example 3 A method for preparing and applying a heterogeneous ammonium oxime catalyst includes the following steps: S1: A heterogeneous ammonium oxime catalyst, comprising the following components: MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride, and silica sol; wherein, the waste acid mother liquor is waste acid generated in the one-pot post-processing preparation of Ti-MOR catalyst, with an acid concentration of 2 mol / L and a titanium concentration of 1 mol / L; the modifier is ammonium chloride, and the binder is silica sol; the mass ratio of MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride, and silica sol is 1: 20: 6: 70; S2: MOR molecular sieve raw powder, waste acid mother liquor, ammonium chloride and silica sol are mixed in a mass ratio, heated at 130℃, dried and calcined at 600℃, and then sphericalized heterogeneous ammonium oxime catalyst with a particle size of 10-50mm is obtained by spherical molding. S3: The obtained catalyst was reacted in the heterogeneous cycloheptanone ammoxidation for 96 h.

[0046] Test case The heterogeneous ammoniation catalysts obtained in Examples 1-4 and Comparative Examples 1-3 were tested in the ammoxidation reaction of cycloalkanes. The test results are shown in Table 1 below. As shown in Table 1, the heterogeneous ammoniation catalysts obtained in Examples 1-4 can improve reaction efficiency, promote the conversion of cycloalkanes, and simultaneously enhance the selectivity of the target product cycloalkanone oxime in the ammoxidation of cycloalkanes, showing significant advantages compared to the comparative examples.

[0047] This invention replaces the acid solution added during the molding process with a one-pot post-processing mother liquor for preparing Ti-MOR catalyst. This mother liquor contains a large number of crystal grains and crystalline structural units, which effectively promotes the dispersion of Ti active sites, reduces the loss of active sites, and forms four-coordinated titanium active species within the framework. The higher the strength of the acid source in the waste acid mother liquor, the greater the degree of dealumination. Since Ti occupies the dealumination sites, it forms Ti active sites. By utilizing the degree of hydrolysis or solubility of the titanium source in the acid solution, the content of the active component Ti can be further controlled, improving catalytic activity. After mixing MOR molecular sieve powder, waste acid mother liquor, modifier, and binder, the mixture undergoes molding. The molded heterogeneous ammonium oxime catalyst has a larger specific surface area and a better mesoporous structure compared to the unformed molecular sieve powder. This effectively promotes the diffusion of large molecular cycloalkane ketones and / or other intermediate products generated during the cycloalkane ammoxidation reaction through the pores, preventing the large accumulation of large molecular products from clogging the pores and covering the titanium active sites, thus hindering catalytic activity.

[0048] This invention employs a boron-containing modifier. By utilizing boron to initiate desilication of the molecular sieve framework, the Ti species are transformed from the Ti(OSi)4 structure to the Ti(OSi)3OH structure, i.e., a transformation from a closed structure to an open structure. This induces the transformation of the active center, further enhancing the Lewis acid strength of the titanium active center and improving catalytic oxidation performance. During catalyst preparation and molding, acid treatment removes boron species from the molecular sieve framework, expanding the interlayer pores in the structure while preventing binders from clogging the pores and exposing the titanium active sites. This facilitates the approach of macromolecular cycloalkanes and / or other intermediates to the active center, improving conversion and target product selectivity. Furthermore, in the molecular sieve crystal structure, B, Al, and Ti compete for placement at T sites, further promoting the dispersion of titanium active sites on the outer surface of the crystal. This allows substrate molecules in the cycloalkanes ammoxidation reaction to directly contact the active center, shortening the diffusion mass transfer path of the substrate molecules and improving catalytic efficiency.

[0049] In Example 1, boric acid was used as a modifier. During the catalyst preparation process, boric acid enables B atoms to form coordination bonds with oxygen atoms, inhibiting excessive growth of molecular sieve crystals, promoting the bonding of Ti sites with the molecular sieve framework, decomposing under calcination conditions, promoting the formation of molecular sieve pore structures, reducing pore collapse, and preventing binders from clogging pores and covering Ti active sites. The resulting heterogeneous ammonium oxime catalyst has more exposed titanium active sites and better dispersion on the surface. The introduction of aluminum-containing binders further provides acid sites for the molecular sieve, promoting the adsorption and activation of ammonia molecules, improving the conversion rate of cycloalkanones, reducing the formation of intermediate products, and improving the selectivity of the target product, cycloalkanone oximes. Compared to Example 1, the addition of excessive waste acid mother liquor in the comparative example resulted in a decrease in the conversion rate of cycloalkanone and the selectivity of the target product, cycloalkanone oxime. As a substitute for the acid added during the catalyst molding process, excessive acid reduces the crystallinity of the molecular sieve, destroys the framework structure, significantly reduces the number of titanium active sites, and makes it easy for titanium species to agglomerate and block the pores, making it difficult to form four-coordinate titanium active species within the framework. During the cycloalkanes ammoxidation reaction, the molded catalyst is unable to effectively exert its adsorption and activation capabilities, making it difficult to avoid the occurrence of side reactions and generating a large number of unevenly distributed intermediate products.

[0050] This invention uses NH4-containing + Modifiers can utilize NH 4+ Modifying the charge microenvironment. In Example 2, ammonium nitrate was used as a modifier, via NH4+. 4+Treatment effectively alters the charge microenvironment surrounding the active Ti site, increasing its positive charge and facilitating the formation of four-coordinate titanium species active centers. This prevents side reactions caused by protic acids within the zeolite structure, which could lead to decreased activity. Simultaneously, it promotes the generation of more uniformly distributed dealumination vacancies within the zeolite, providing sites for titanium species and fostering the formation of four-coordinate titanium species within the framework. The increased positive charge of the Ti sites promotes heterolytic cleavage of the OO bonds in the reaction intermediate Ti−OOH, thereby enhancing the selectivity of epoxidation. The ammonium salt releases gases during the calcination stage, enabling the zeolite structure to form mesopores, increasing the specific surface area, and preventing kaolin from acting as a binder and clogging the pores. NH4 + It can improve the strong acid sites on the surface of kaolin and inhibit the occurrence of catalytic side reactions. The mesoporous structure formed by molecular sieves can promote the adsorption and transformation of macromolecular substrates and macromolecular intermediates, thereby improving the selectivity of target products.

[0051] Comparative Example 2 did not contain NH4+ compared to Example 2. 4+ Modification leads to a significant decrease in the conversion rate of cycloalkanones and the selectivity of the target product, cycloalkanone oxime. When NH3 is absent... 4+ When modifiers participate in the reaction, titanium species agglomerate, dispersibility decreases, and the number of active centers is greatly reduced. Furthermore, molecular sieves are unable to form good mesoporous structures, and there is also the problem of binders clogging the pores. Macromolecular reactants cannot be effectively adsorbed and will come into contact with active centers for transformation. The intermediate products generated are also difficult to diffuse and transform within the pores. A large number of active sites are covered, leading to a large number of intermediate side reactions. Therefore, the conversion rate of cycloalkanones and the selectivity of the target product cycloalkane oximes are significantly reduced.

[0052] The difference between Example 3 and Comparative Example 3 lies in the particle size of the shaped catalyst. Comparative Example 3 used catalyst particles of 10-50 mm, while Example 3 optimized the particle size to 500 μm-1 mm microspheres. From a mass transfer perspective, smaller particle size significantly shortens the diffusion path of reactants to the active sites within the catalyst, while simultaneously accelerating the outward diffusion of products, effectively reducing internal diffusion resistance. This optimization not only improves the contact efficiency between reactants and the catalyst but also reduces side reactions, thereby enhancing the selectivity of the target product. Furthermore, the microspherical structure of the shaped catalyst provides a higher specific surface area, exposing more active sites and further enhancing catalytic performance. Example 4 uses a catalyst with a particle size of 200-500 μm, achieving comparable reaction conversion and selectivity performance to Example 3. Therefore, controlling the catalyst particle size within a reasonable range not only optimizes the mass transfer process but also ensures simultaneous achievement of mechanical strength and industrial filtration.

Claims

1. A heterogeneous ammonium oxime catalyst, characterized in that, The product comprises the following components: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, in a mass ratio of 1: (1-50): (2-10): (50-100). The modifier is one or more of boric acid, ammonia, ammonium nitrate, and ammonium chloride.

2. The heterogeneous ammonium oxime catalyst according to claim 1, characterized in that, It includes the following components: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder, with a mass ratio of 1: (10-40): (4-8): (60-90).

3. A heterogeneous ammonium oxime catalyst according to claim 1 or 2, characterized in that, The adhesive is one or more of boehmite, kaolin, and silica sol.

4. A heterogeneous ammonium oxime catalyst according to claim 1 or 2, characterized in that, The waste acid mother liquor has an acid concentration of 1-5 mol / L and a titanium concentration of 0.1-2 mol / L.

5. The heterogeneous ammonium oxime catalyst according to claim 4, characterized in that, The acid source in the waste acid mother liquor is one or more of nitric acid, acetic acid, hydrochloric acid, sulfuric acid, formic acid, and citric acid. The titanium source is one or more of titanium tetrachloride, titanium powder, tetraethyl titanate, and tetrabutyl titanate.

6. A method for preparing a heterogeneous ammonium oxime catalyst according to any one of claims 1-5, characterized in that, Includes the following steps: MOR molecular sieve raw powder, waste acid mother liquor, modifier, and binder are mixed, heated, dried, and calcined. After molding, a heterogeneous ammonium oxime catalyst is obtained.

7. The method for preparing a heterogeneous ammonium oxime catalyst according to claim 6, characterized in that, The waste acid mother liquor is obtained from the waste acid produced in the one-pot post-processing preparation of Ti-MOR catalyst.

8. The method for preparing a heterogeneous ammonium oxime catalyst according to claim 6, characterized in that, In the aforementioned steps, the heating temperature is 80-150℃, and the calcination temperature is 400-600℃; The forming process includes one or more of the following: extrusion, spraying, ball rolling, and tableting.

9. The forming process of a heterogeneous ammonium oxime catalyst according to claim 8, characterized in that, The heterogeneous ammonium oxime catalyst has a particle size of 0.1 μm-1 mm.

10. The application of a heterogeneous ammonium oxime catalyst according to any one of claims 1-5 in the ammoxidation of cycloalkanes.

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