Regeneration method and application of ammoxidation catalyst

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to an ammoxidation catalyst regeneration method and application. The ammoxidation catalyst regeneration method provided by the invention comprises the following steps: a to-be-treated catalyst and an additional component are subjected to mixed fluidization treatment under specific conditions, and the additional component is a catalyst of which the active component content is higher than that of a fresh catalyst or a compound containing IIIA main group elements. According to the method, online reactivation of the catalyst can be achieved, secondary roasting is not needed, the inactivated catalyst after running for a period of time can achieve activity regeneration in the fluidization process at the regeneration temperature and time, operation is easy, and the production efficiency is improved. Besides, through long-term research, the inventor finds that good regeneration of the catalyst activity can be realized by supplementing the compound containing the IIIA main group element, the inertial thinking that in the prior art, the activity regeneration is generally supplementing the expensive main active component is broken through, and the regeneration cost of the catalyst is reduced.

Description

Technical Field

[0001] The present application belongs to the field of catalyst technology, and specifically relates to an ammonia oxidation catalyst regeneration method and application. Background Art

[0002] The cyano group in aromatic nitrile has high chemical activity. After hydrogenation and condensation reaction, various fine chemical products can be synthesized. It has been widely used in many industries such as medicine, fragrance, pesticide and resin. As an important source of raw materials, the demand for aromatic nitrile has shown an upward trend in recent years. The synthetic route of aromatic nitrile is generally: aromatic hydrocarbons are obtained by ammoxidation under the conditions of ammonia and catalyst. Because the above manufacturing process has the advantages of simple operation, safe operation, high yield and low pollution, many scholars have invested a lot of research on it and it has been widely used.

[0003] However, after the catalyst is operated for a long time, problems such as increased deep oxidation, increased carbon dioxide selectivity, and reduced yield of nitrile products will occur. In view of these problems, some catalyst regeneration methods have been proposed in the prior art. However, these methods require the catalyst to be unloaded from the reactor and then regenerated, which is cumbersome to operate; in addition, most of the regeneration methods in the prior art achieve regeneration by adding the main active component, which is costly.

[0004] Based on this, there is an urgent need to develop a simple, low-cost remedial method to extend the life of the catalyst, thereby improving product selectivity, reducing the degree of deep oxidation of the raw materials, increasing the raw material conversion rate, reducing raw material waste, and effectively improving the activity of the catalyst during operation to ensure the long-term stability of the catalyst. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present application is to overcome the defects of the prior art such as cumbersome catalyst regeneration operation, the need to supplement the main active components, high cost, etc., thereby providing an ammonia oxidation catalyst regeneration method and application.

[0006] To this end, this application provides the following technical solutions:

[0007] According to one aspect of the present application, a method for regenerating an ammonia oxidation catalyst is provided, comprising the following steps:

[0008] The catalyst to be treated and the additional components are mixed and fluidized at 200-600° C. for 0.5-72 h. As an example, the temperature of the mixed fluidization can be 200° C., 250° C., 300° C., 350° C., 400° C., 450° C., 500° C., 550° C., 600° C., or within the range of any of the above values. The time of the mixed fluidization can be 0.5 h, 3 h, 10 h, 24 h, 36 h, 48 h, 60 h, 72 h, or within the range of any of the above values.

[0009] Wherein, the additional components include at least one of the following (1) or (2):

[0010] The (1) is a catalyst having a higher active component content than a fresh catalyst;

[0011] The (2) mentioned above is a compound containing an element of the IIIA main group.

[0012] In some optional embodiments, the mass ratio of the additional component to the catalyst to be treated is 0.01-10; as an example, the mass ratio of the additional component to the catalyst to be treated can be 0.01, 0.1, 0.3, 0.5, 0.8, 1, 3, 5, 7, 9, 10, or within the range of any of the above values.

[0013] In some optional embodiments, when the supplementary component is (1), the mass ratio of the supplementary component to the catalyst to be treated is 0.1-10;

[0014] And / or, when the supplementary component is (2), the mass ratio of the supplementary component to the catalyst to be treated is 0.01-1.

[0015] In some optional embodiments, the Group IIIA element includes at least one of B, Al, and Ga.

[0016] In some optional embodiments, the compound containing a Group IIIA element includes at least one of boron trioxide, aluminum oxide, and gallium oxide.

[0017] In some optional embodiments, the catalyst to be treated is a catalyst whose selectivity of the target product is less than 90% after the fresh catalyst has been run for a certain period of time. As an example, when applied to a catalyst in the preparation of aromatic nitrile, the catalyst to be treated is a catalyst whose selectivity of the aromatic nitrile is less than 90% after the fresh catalyst has been run for a certain period of time.

[0018] In some optional embodiments, the composition of the fresh catalyst includes: a carrier and an active component, and the mass percentage of the active component is 20-70% based on the total mass of the catalyst; as an example, the mass percentage of the active component in the fresh catalyst can be 20%, 30%, 40%, 50%, 60%, 70%, or within the range of any of the above values.

[0019] The active components satisfy the following structural formula calculated by atomic ratio: 1.0 Cr a A b C c D d O x ; Wherein, A is selected from any one of Zr, Ti or Mo or a combination of at least two, C is selected from any one of Al, Ga, B or Ag or a combination of at least two, and D is selected from any one of Bi, P or Sb or a combination of at least two; a=0.05~5, b=0.01~2, c=0.001~1, d=0.001~1, x=2.0~11; optionally, a=0.08~3, b=0.05~1, c=0.05~0.8, d=0.01~0.5, x=2.7~9.

[0020] In some optional embodiments, the carrier comprises Al2O3 / SiO2 type molecular sieve, and optionally the carrier comprises HZSM-5 molecular sieve;

[0021] Optionally, the silicon-to-aluminum ratio of the carrier (the silicon-to-aluminum ratio in this application refers to the molar ratio of SiO2 to Al element) is 1:(0.001-0.1), and further optionally is 1:(0.005-0.07); as an example, the silicon-to-aluminum ratio of the carrier can be 1:0.001, 1:0.005, 1:0.01, 1:0.03, 1:0.05, 1:0.07, 1:0.1, etc., or within the range of any of the above values.

[0022] In some optional embodiments, when the supplementary component is (1), the mass percentage of the active component in the supplementary component is 21%-80%; optionally, the mass percentage of the active component in the supplementary component is 1%-10% higher than the mass percentage of the active component in the fresh catalyst.

[0023] And / or, the mixed fluidized atmosphere is an air atmosphere or a nitrogen atmosphere, and the mass percentage of water is less than 1%.

[0024] According to another aspect of the present application, there is provided an application of the above-mentioned ammonia oxidation catalyst regeneration method in the preparation of aromatic nitrile;

[0025] Optionally, the aromatic nitrile is isophthalonitrile.

[0026] In the present application, the fresh catalyst belongs to a V-Cr system catalyst, which can not only improve product selectivity, reduce the deep oxidation degree of raw materials, improve raw material conversion rate, and reduce raw material waste, but also has high stability and mechanical strength, improves production efficiency, and is suitable for large-scale industrial production applications, especially for the application in the preparation of isophthalonitrile by ammoxidation of meta-xylene.

[0027] In the present application, by limiting the stoichiometric ratio of the C-type metal elements in the fresh catalyst, an effective composite reaction active site can be formed, which enables the active component and the carrier to form a synergistic reaction active site, effectively reducing the activation energy of the ammonia oxidation reaction, increasing the adsorption amount of ammonia, reducing the deep oxidation degree of raw materials such as meta-xylene, reducing the generation of small molecule products, and ensuring the conversion rate of raw materials such as meta-xylene and product selectivity.

[0028] Furthermore, the fresh catalyst described in the present application can effectively ensure the stability and mechanical strength of the ammonia oxidation catalyst by accurately defining the stoichiometric ratio of type A and type D metal elements in the active components, and ensure the stability of the ammonia oxidation catalyst during long-term operation.

[0029] In the present application, the carrier HZSM-5 molecular sieve in the fresh catalyst belongs to the artificially synthesized Al2O3 / SiO2 type molecular sieve and has a double ten-membered ring cross-channel structure.

[0030] In the present application, the preparation method of the above-mentioned fresh catalyst comprises the following steps:

[0031] (1) preparing a carrier synthesis liquid according to the required carrier silicon-aluminum ratio in the fresh catalyst and mixing it with a glycerol type C aqueous solution to form a mixed reaction liquid A;

[0032] (2) preparing an aqueous solution containing various metal elements according to the structural formula of the active component in the fresh catalyst to form a reaction solution B;

[0033] (3) slowly mixing the reaction solution A described in step (1) with the reaction solution B described in step (2) to form an impregnation mixed solution C;

[0034] (4) The impregnation mixed solution C of step (3) is evaporated, concentrated, dried and calcined in sequence to obtain the fresh catalyst.

[0035] In the present application, the preparation method of the fresh catalyst is to obtain a reaction liquid B according to the structural formula of the active component, prepare a carrier synthesis liquid according to the required carrier silicon-aluminum ratio and mix it with a glycerol C-type aqueous solution to form a mixed reaction liquid A, mix the reaction liquid A and the reaction liquid B, allow A to react with some components in B, and impregnate the active component on the carrier, and the obtained impregnation mixed liquid is evaporated, concentrated, dried and calcined in sequence to obtain the fresh catalyst.

[0036] In some optional embodiments, the method for preparing the reaction solution A in step (1) comprises the following steps:

[0037] The aluminum source and the silicon source are mixed to obtain a first mixed solution, the auxiliary agent and the C-type raw material aqueous solution are mixed to form an auxiliary agent C-type aqueous solution, and then the two are mixed to obtain a reaction solution A, where the aluminum element in the aluminum source added here also serves as an active component of the catalyst.

[0038] It is worth noting that the reaction solution A of the present invention controls the size of the pores and the number of pores in the carrier by adding an additive, which is beneficial for the target raw material to enter the pores and combine with the reactive active sites during the ammonia oxidation catalytic reaction.

[0039] Moreover, the C-type elements can combine with the Si-O bonds of the carrier to form new C-Si-O bond combinations, making the C-type elements more stable in the catalyst.

[0040] As a preferred technical solution of the present application, the aluminum source includes sodium aluminate and / or aluminum sulfate.

[0041] Preferably, the silicon source includes tetraethyl orthosilicate and / or silica sol.

[0042] Preferably, the silicon-aluminum ratio (molar ratio of SiO2 to Al) of the silicon source and the aluminum source is 1:(0.001-0.1). It is worth noting that by accurately adjusting the silicon-aluminum ratio of the reaction solution A, the Al2O3 content in the carrier can be accurately adjusted, and then the acid amount of the carrier can be regulated to provide more ammonia adsorption sites for the subsequent ammonia oxidation reaction. If the silicon-aluminum ratio is higher than the range selected in this application, the acid sites are insufficient, the adsorption capacity of ammonia is insufficient, and the effect of reducing the degree of xylene oxidation cannot be achieved; if the silicon-aluminum ratio is lower than the range selected in this application, the strong acid sites increase, resulting in excessive adsorption of ammonia, and it is difficult to react with xylene for ammonia oxidation, resulting in a deepening of the degree of xylene deep oxidation to generate carbon dioxide.

[0043] Preferably, the auxiliary agent includes any one of glycerol, organic amine or quaternary ammonium salt, preferably glycerol.

[0044] It is worth noting that the reaction liquid B described in the present application can effectively control the size of the pores in the carrier to be equivalent to the molecular dynamic diameter of benzene (about 0.6 nm) by adding additives, that is, improve the shape selectivity, and can also enhance the adsorption of ammonia, thereby improving the selectivity of aromatic products and reducing the degree of deep oxidation of the raw materials.

[0045] Preferably, the molar ratio of the auxiliary agent to the V element in the active component is 0.1 to 30, such as 0.1, 0.5, 1, 3, 5, 8, 10, 15, 20, 25 or 30, and preferably 0.5 to 20, such as 0.5, 1.5, 2, 4, 7, 9, 11, 13, 16, 18 or 20, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0046] As a preferred technical solution of the present invention, the temperature of the evaporation concentration in step (4) is 50-120°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0047] Preferably, the evaporation and concentration in step (4) obtains a slurry liquid with a solid content of 30-70%, and the solid content can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0048] As a preferred technical solution of the present invention, the drying in step (4) is spray drying.

[0049] Preferably, the inlet temperature of the spray drying is 150-350°C, for example, 150°C, 160°C, 180°C, 170°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 280°C, 290°C or 350°C, and the outlet temperature is 90-190°C, for example, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0050] As a preferred technical solution of the present invention, the heating rate of the roasting in step (4) is 1 to 10°C / min, for example, 1°C / min, 3°C / min, 5°C / min, 7°C / min or 10°C / min, etc., preferably 2 to 6°C / min, for example, 2°C / min, 2.5°C / min, 3.5°C / min, 4.5°C / min, 5.5°C / min or 6°C / min, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0051] Preferably, the roasting in step (4) is a primary roasting.

[0052] Preferably, the calcination temperature is 550°C to 700°C, for example 600°C, 620°C, 650°C, 680°C, 700°C, 720°C or 750°C, etc., preferably 620-700°C, for example 620°C, 640°C, 660°C, 670°C or 700°C, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0053] Preferably, the primary calcination time is 3 to 9 hours, for example 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours or 9 hours, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0054] The technical solution of this application has the following advantages:

[0055] The ammonia oxidation catalyst regeneration method provided by the present application comprises the following steps: mixing the catalyst to be treated with the supplementary component at 200-600°C for 0.5-72h; wherein the supplementary component is: (1) a catalyst having a higher active component content than the fresh catalyst, or (2) a compound containing a group IIIA element. The regeneration method provided by the present application can realize the online resurrection of the catalyst without secondary calcination. The catalyst that has been deactivated after running for a period of time can be regenerated in the fluidization process at the above regeneration temperature and time, which is simple to operate and improves production efficiency. In addition, after long-term research by the inventor, it is found that the catalyst activity can be well regenerated by adding a compound containing a group IIIA element, breaking through the inertial thinking that the active regeneration in the prior art is generally to add expensive main active components, thereby reducing the cost of catalyst regeneration. In addition, the catalyst regenerated by the method of the present application has a lower selectivity decline rate of the target product, that is, compared with the fresh catalyst, after running for the same time, the selectivity of the regenerated catalyst is slightly higher than that of the fresh catalyst, thereby slowing down the decline in the yield of the target product.

[0056] The ammonia oxidation catalyst regeneration method provided in the present application requires controlling the moisture content in the system to be below 1%, which can further improve the regeneration effect of the catalyst.

[0057] The application of the ammonia oxidation catalyst regeneration method provided in the present application in the preparation of aromatic nitriles can realize online resurrection of the catalyst, so there is no need for frequent disassembly and assembly of the catalyst, the operation is simple, and it is conducive to the stable operation of the reactor and improves production efficiency. DETAILED DESCRIPTION

[0058] The following examples are provided for a better understanding of the present application, but are not limited to the best implementation mode described, and do not limit the content and protection scope of the present application. Any product identical or similar to the present application obtained by anyone under the inspiration of the present application or by combining the features of the present application with other prior arts shall fall within the protection scope of the present application.

[0059] If no specific experimental steps or conditions are specified in the examples and comparative examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially. The raw materials used in the examples and comparative examples are all conventional raw materials in the field, and the purity specification used is AR grade.

[0060] The calculation formulas for the conversion rate of raw material meta-xylene and the selectivity of target product isophthalonitrile in the embodiments and comparative examples are as follows:

[0061] Meta-xylene conversion rate (%) = (the number of moles of meta-xylene reacted / the number of moles of meta-xylene fed) × 100%;

[0062] Isophthalonitrile selectivity (%) = (the number of moles of isophthalonitrile produced / the number of moles of meta-xylene reacted) × 100%.

[0063] Example 1

[0064] This embodiment provides a catalyst regeneration method, comprising the following steps:

[0065] Wherein, the preparation method of the fresh catalyst used is as follows:

[0066] (1) adding 2.49 g of NaAlO2 to 120 g of water and stirring at room temperature until completely dissolved to form an aluminum source; adding the aluminum source to 404.5 g of silica sol having a mass percentage of 30%, mixing to obtain a first mixed solution, and mixing 242.7 g of glycerol and 18.22 g of boric acid and adding the mixture to the first mixed solution to obtain the reaction solution A;

[0067] (2) According to the structural formula of the active component in the ammonia oxidation catalyst, 44.6 g of vanadium pentoxide was slowly added to 106.8 g of chromic acid solution, and then 7.28 g of ammonium molybdate, 3.28 g of phosphoric acid, and 1.9 g of antimony acetate were dissolved in 100 g of water respectively, and added to the chromic acid solution, and mixed to form a reaction solution B;

[0068] (3) adding the reaction solution B containing the active component into the reaction solution A described in step (1) to form an impregnation mixture, and slowly adding the mixture dropwise for 2 hours;

[0069] (4) The impregnation mixture of step (3) is evaporated and concentrated at 85°C and a pressure of 550 mbar until a slurry liquid with a solid content of 50% is obtained; the obtained slurry liquid is spray-dried at an inlet temperature of 250°C and an outlet temperature of 170°C to obtain a catalyst precursor; the obtained catalyst precursor is placed in a muffle furnace, heated to 600°C at a heating rate of 2°C / min, and kept warm for 3 hours for roasting, and finally cooled to room temperature to obtain a fresh catalyst.

[0070] After testing, the active component ratio in the above fresh catalyst is V in terms of atomic ratio. 1.0 Cr 1.0 B 0.02 Mo 0.08 P 0.05 Al 0.01 Sb 0.012 O 5.94 , the active component accounts for 56% in the catalyst (in order to facilitate the comparison between data, the preparation method of the fresh catalyst in the following examples and comparative examples is the same as that in Example 1).

[0071] The fresh catalyst obtained above was loaded into a laboratory ammonia oxidation fluidized bed reactor for reaction performance evaluation. The feed ratio of the reaction raw materials was 1:3.1:12 according to the molar ratio of m-xylene: ammonia: oxygen. The reaction temperature of the ammonia oxidation reactor was 400 °C, the reaction pressure (gauge pressure) was 70 kPa, and the catalyst weight load in the reactor was 0.05 h -1 .

[0072] After the reactor was operated for 500 h, the conversion rate of meta-xylene was 99.6% and the selectivity of isophthalonitrile was 97.3%.

[0073] After the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.8% and the selectivity of isophthalonitrile was 91.25%.

[0074] After the reactor was operated for 1450 hours, the conversion rate of meta-xylene was 99.8%, the selectivity of isophthalonitrile was 89.33%, and the catalyst was deactivated.

[0075] Catalyst regeneration: Add boron trioxide in the fluidized bed, the mass ratio of boron trioxide to catalyst is 0.1, and fluidize for 48 hours (catalyst regeneration) in an air atmosphere at 400°C (moisture content is controlled below 1%), and then conduct normal feeding reaction. The feed ratio of the reaction raw materials is 1:3.1:12 according to the molar ratio of m-xylene: ammonia: oxygen. The reaction temperature of the ammoxidation reactor is 400°C, the reaction pressure (gauge pressure) is 70kPa, and the catalyst weight load in the reactor is 0.05h -1 .

[0076] After the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.4% and the selectivity of isophthalonitrile was 98.8%.

[0077] Example 2

[0078] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that in the catalyst regeneration step, the mass ratio of boron trioxide to catalyst is 0.01.

[0079] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.5% and the selectivity of isophthalonitrile was 95.3%.

[0080] Example 3

[0081] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that in the catalyst regeneration step, the mass ratio of boron trioxide to catalyst is 1.

[0082] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.1% and the selectivity of isophthalonitrile was 96.1%.

[0083] Example 4

[0084] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that triisobutylaluminum with a molar ratio of Al / B = 1 is used instead of boron trioxide in the catalyst regeneration step.

[0085] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.2% and the selectivity of isophthalonitrile was 96.4%.

[0086] Example 5

[0087] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that gallium carbonate with a molar ratio of Ga / B = 1 is used instead of boron trioxide in the catalyst regeneration step.

[0088] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.1% and the selectivity of isophthalonitrile was 95.9%.

[0089] Example 6

[0090] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that the fluidization treatment temperature in the catalyst regeneration step is 200° C. and the mixed fluidization time is 72 h.

[0091] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.5% and the selectivity of isophthalonitrile was 96.9%.

[0092] Example 7

[0093] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that the fluidization treatment temperature in the catalyst regeneration step is 600° C. and the mixed fluidization time is 0.5 h.

[0094] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.6% and the selectivity of isophthalonitrile was 97.1%.

[0095] Example 8

[0096] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that in the catalyst regeneration step, a catalyst with an active component content of 65% is used for regeneration, and the mass ratio with the conventional catalyst in the reactor is 0.1.

[0097] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.3% and the selectivity of isophthalonitrile was 97.2%.

[0098] Example 9

[0099] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that in the catalyst regeneration step, a catalyst with an active component content of 57% is used for regeneration, and the mass ratio of the catalyst to the conventional catalyst in the reactor is 10.

[0100] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.2% and the selectivity of isophthalonitrile was 97.1%.

[0101] Example 10

[0102] This embodiment provides a catalyst regeneration method. Compared with Embodiment 1, the only difference is that in the catalyst regeneration step, a catalyst with an active component content of 59% is used for regeneration, and the mass ratio with the conventional catalyst in the reactor is 1.

[0103] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.4% and the selectivity of isophthalonitrile was 97.5%.

[0104] Comparative Example 1

[0105] This comparative example provides a catalyst regeneration method. Compared with Example 1, the only difference is that chromium vanadate, the main active component of the catalyst, is added in the catalyst regeneration step, and the mass ratio of chromium vanadate to the deactivated catalyst is 0.1.

[0106] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.9% and the selectivity of isophthalonitrile was 56.1%.

[0107] Comparative Example 2

[0108] This comparative example provides a catalyst regeneration method, wherein the deactivated catalyst is unloaded, and the deactivated catalyst is fully mixed with boron trioxide, wherein the mass ratio of boron trioxide to catalyst is 0.01. The mixed materials are placed in a muffle furnace, heated to 600°C at a heating rate of 2°C / min, and kept warm for 3 hours for roasting, and finally cooled to room temperature to obtain a regenerated catalyst.

[0109] After the catalyst was regenerated and the reactor was operated for 1000 h, the conversion rate of meta-xylene was 99.7% and the selectivity of isophthalonitrile was 93.2%.

[0110] From the data comparison of the embodiment and the comparative example, it can be seen that the regeneration method provided by the present application can effectively realize the online resurrection of the catalyst. At the same time, the selectivity decrease rate of the target product of the catalyst regenerated by the method of the present application is reduced, that is, compared with the fresh catalyst, after running for the same time, the selectivity of the regenerated catalyst is slightly higher than that of the fresh catalyst, thereby slowing down the decline in the yield of the target product. Compared with the catalyst regenerated by secondary calcination in Comparative Example 2, the catalyst regenerated by the method of the present application has better selectivity for the target product, and the regeneration operation is simple, the production efficiency is improved, and it is convenient for industrial application.

[0111] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for regenerating an ammonia oxidation catalyst, characterized in that: The steps include: Mix the catalyst to be treated and the additional components at 200-600°C and fluidize for 0.5-72h; Wherein, the additional components include at least one of the following (1) or (2): The (1) is a catalyst having a higher active component content than a fresh catalyst; The (2) mentioned above is a compound containing an element of the IIIA main group.

2. The method for regenerating an ammonia oxidation catalyst according to claim 1, characterized in that: The mass ratio of the supplementary component to the catalyst to be treated is 0.01-10.

3. The method for regenerating an ammonia oxidation catalyst according to claim 2, characterized in that: When the supplementary component is (1), the mass ratio of the supplementary component to the catalyst to be treated is 0.1-10; And / or, when the supplementary component is (2), the mass ratio of the supplementary component to the catalyst to be treated is 0.01-1.

4. The method for regenerating an ammonia oxidation catalyst according to claim 1, characterized in that: The IIIA main group element includes at least one of B, Al, and Ga.

5. The method for regenerating an ammonia oxidation catalyst according to claim 4, characterized in that: The compound containing the IIIA main group element includes at least one of boron trioxide, aluminum oxide, alkyl aluminum, gallium oxide, and gallium carbonate.

6. The method for regenerating an ammonia oxidation catalyst according to claim 1, characterized in that: The catalyst to be treated is a catalyst whose target product selectivity is lower than 90% after the fresh catalyst has been running for a certain period of time.

7. The method for regenerating an ammonia oxidation catalyst according to claim 1, characterized in that: The composition of the fresh catalyst includes: a carrier and an active component, and the mass percentage of the active component is 20-70% based on the total mass of the catalyst; The active components satisfy the following structural formula calculated by atomic ratio: 1.0 Cr a A b C c D d O x ; Wherein, A is selected from any one of Zr, Ti or Mo or a combination of at least two, C is selected from any one of Al, Ga, B or Ag or a combination of at least two, and D is selected from any one of Bi, P or Sb or a combination of at least two; a=0.05~5, b=0.01~2, c=0.001~1, d=0.001~1, x=2.0~11; optionally, a=0.08~3, b=0.05~1, c=0.05~0.8, d=0.01~0.5, x=2.7~9.

8. The method for regenerating an ammonia oxidation catalyst according to claim 7, characterized in that: The carrier comprises an Al2O3 / SiO2 type molecular sieve, and optionally the carrier comprises a HZSM-5 molecular sieve; Optionally, the silicon-aluminum ratio of the carrier is 1:(0.001-0.1), further optionally 1:(0.005-0.07).

9. The method for regenerating an ammonia oxidation catalyst according to claim 7 or 8, characterized in that: When the supplementary component is (1), the mass percentage of the active component in the supplementary component is 21%-80%; optionally, the mass percentage of the active component in the supplementary component is 1%-10% higher than the mass percentage of the active component in the fresh catalyst; And / or, the mixed fluidized atmosphere is an air atmosphere or a nitrogen atmosphere, and the mass percentage of water is less than 1%.

10. Use of the ammonia oxidation catalyst regeneration method according to any one of claims 1 to 9 in the preparation of aromatic nitrile; Optionally, the aromatic nitrile is isophthalonitrile.