Catalyst system and application thereof as well as production method and system of aromatic carboxylic acid

Abstract

The invention discloses a catalyst system and application thereof, and a production method and system of aromatic carboxylic acid. The catalyst system comprises a main catalyst containing metal ions and a co-catalyst, the metal ions comprise cobalt and manganese, and the cocatalyst is selected from hydrobromic acid and / or bromine-containing inorganic salt. When the aromatic carboxylic acid is produced, under the action of an organic acid aqueous solution and the catalyst system, aromatic hydrocarbon and oxygen-containing gas are sequentially subjected to oxidation and deep oxidation reaction, and the aromatic carboxylic acid is prepared. When the catalyst system is used for oxidation production, not only can the conversion rate of reactant aromatic hydrocarbon and the selectivity of product aromatic carboxylic acid be improved, but also a production process system of the aromatic carboxylic acid can stably run for a long time, and the catalyst system has excellent industrial application value. The aromatic carboxylic acid is produced by adopting oxidation and deep oxidation reactions in a cascade manner, the reaction conditions are mild, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to a catalyst system and application thereof, and a method and system for producing aromatic carboxylic acid. Background Art

[0002] Aromatic carboxylic acids are very important chemical products, among which naphthalene dicarboxylic acid and terephthalic acid are two important carboxylic acid products. Naphthalene dicarboxylic acid is a key monomer in the production of polyethylene naphthalate (PEN), which is used to produce high-end polymer products such as membrane materials, flexible printed circuit boards (FPC), fuel cell seals, electrical heat-resistant insulation, speaker membranes, food-grade pharmaceutical packaging, and aerospace materials; terephthalic acid is an important raw material for the production of polyethylene terephthalate (PET), with a global production capacity of more than 100 million tons / year and huge market demand.

[0003] At present, the production of naphthalene dicarboxylic acid, terephthalic acid and isophthalic acid in industry is with cobalt acetate and manganese acetate as catalyst, with hydrobromic acid as promoter, the solvent is watery acetic acid, dimethyl naphthalene, p-Xylene, m-Xylene react with oxygen in air to generate corresponding carboxylic acid products.But, the production process of naphthalene dicarboxylic acid has many side reactions, especially the content of trimellitic acid can reach 5%, which causes great difficulties to subsequent separation and purification, and the content of impurities such as naphthoic acid is higher in addition, which all causes great influence on the activity and reaction yield of catalyst.In addition, although the industrial production technology of terephthalic acid and isophthalic acid is very mature, the intermediate aldehyde products and the content of monocarboxylic acid products affect product quality and device consumption.

[0004] The existing aromatic carboxylic acid production technology has many impurities in the oxidation product, low yield and difficult separation. When the reaction is not sufficient, the intermediate product aldehydes and naphthalene monocarboxylic acid products have high content and low product yield; the reaction is prone to overoxidation, resulting in high content of impurities trimellitic acid and naphthoic acid, among which the content of trimellitic acid can reach up to 5%, affecting the product yield and making product separation more difficult. It is necessary to find a better process solution to improve the yield, reduce consumption, mild reaction conditions and efficient catalysts to promote clean production and energy saving and consumption reduction. Summary of the invention

[0005] In order to at least partially solve the technical problems existing in the above-mentioned prior art, the embodiments of the present invention provide a composition, a catalyst system and a production method and system for aromatic carboxylic acids, so as to improve the conversion rate of raw materials and adapt to industrial production.

[0006] As one aspect of the present invention, a catalyst system is provided, which includes a main catalyst containing metal ions and a co-catalyst; the metal ions include cobalt and manganese, and the co-catalyst is selected from hydrobromic acid and / or bromine-containing inorganic salts.

[0007] In one or some possible embodiments, the metal ions further include one or more of vanadium, molybdenum, nickel or tungsten.

[0008] In one or some possible embodiments, the molar ratio of cobalt, manganese and bromine is 1:(1-2):(1-2).

[0009] In one or some possible embodiments, the cobalt ion concentration is 500-2000 ppm.

[0010] In one or some possible embodiments, the cobalt ion concentration is 800-1500 ppm.

[0011] In one or some possible embodiments, the system is one of a Lindqvist-type compound, a Keggin-type compound, a Dawson-type compound, an Anderson-type compound, a Waugh-type compound or a Silverton-type compound.

[0012] As another aspect of the present invention, it relates to the use of the above catalyst system in the production of aromatic carboxylic acids.

[0013] As another aspect of the present invention, it relates to a method for producing an aromatic carboxylic acid, wherein the method uses the above catalyst system.

[0014] In one or some possible embodiments, the method comprises: in the presence of an organic acid aqueous solution and the catalyst system, the aromatic hydrocarbon and the oxygen-containing gas are subjected to oxidation and deep oxidation reactions in sequence to obtain the aromatic carboxylic acid. The preferred method of the embodiment of the present invention further comprises: crystallizing, filtering, washing and drying the crude aromatic carboxylic acid product obtained after deep oxidation to obtain an aromatic carboxylic acid product.

[0015] In one or some possible embodiments, the organic acid aqueous solution is a mixture of C2-C6 monocarboxylic acid and water in any ratio.

[0016] In one or some possible embodiments, the mass content of water is 5-20%.

[0017] In one or some possible embodiments, the mass content of water is 7-12%.

[0018] In one or some possible embodiments, the oxygen-containing gas is selected from one of air, oxygen-rich gas or oxygen-depleted gas.

[0019] In one or some possible embodiments, the aromatic hydrocarbon is selected from one of 2,6-dimethylnaphthalene, p-xylene or m-xylene.

[0020] In one or some possible embodiments, the mass ratio of the organic acid aqueous solution to the aromatic hydrocarbon is (3-20):1.

[0021] In one or some possible embodiments, the mass ratio of the organic acid aqueous solution to the aromatic hydrocarbon is (5-10):1.

[0022] In one or some possible embodiments, the operating conditions of the oxidation are: temperature 160-220°C, pressure 0.8-2.5 MPaG, and residence time 30-90 min; the operating conditions of the deep oxidation are: temperature 190-250°C, pressure 0.8-2.5 MPaG, and residence time 30-150 min.

[0023] In one or some possible embodiments, the operating conditions of the oxidation are: temperature 180-195°C, pressure 1.5-2.0 MPaG, and residence time 45-60 min; the operating conditions of the deep oxidation are: temperature 200-220°C, pressure 1.8-2.2 MPaG, and residence time 75-120 min.

[0024] As another aspect of the present invention, it relates to a production system of aromatic carboxylic acid, the system is used to implement the production method of aromatic carboxylic acid, the system comprises an oxidation reactor and a deep oxidation reactor;

[0025] The oxidation reactor is used for preliminarily oxidizing aromatic hydrocarbons to obtain a first oxidized slurry; the deep oxidation reactor is used for deeply oxidizing incompletely oxidized aromatic hydrocarbons and intermediate products in the first oxidized slurry to obtain a second oxidized slurry;

[0026] At least one deep oxidation reactor is provided; and a plurality of deep oxidation reactors are connected in series.

[0027] When the catalyst system of the present invention is used for oxidation production, it can not only improve the conversion rate of the reactant aromatic hydrocarbons and the selectivity of the product aromatic carboxylic acid, but also enable the production process system of the aromatic carboxylic acid to operate stably for a long time, and has excellent industrial application value.

[0028] The present invention adopts oxidation and deep oxidation reactions to produce aromatic carboxylic acids in stages, thereby further improving the conversion rate of reactant aromatic hydrocarbons and the selectivity of product aromatic carboxylic acids. In addition, the reaction conditions for producing aromatic carboxylic acids in the present invention are mild and suitable for industrial production.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 The present invention is a production process flow chart of aromatic carboxylic acid;

[0032] In the figure, 101, oxidation reactor; 102, deep oxidation reactor; 103, oxidation tail gas treatment system; a, oxygen-containing gas; b, aromatic hydrocarbons; c, solvent and catalyst; d, first oxidation slurry; e, second oxidation slurry. DETAILED DESCRIPTION

[0033] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0034] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0036] In the description of the present invention, it should be noted that the terms "include", "including", "have", "contain" and the like are open terms, meaning including but not limited to.

[0037] The present invention is further described below in conjunction with specific embodiments, and the protection scope of the present invention is not limited by the following embodiments. The sources of materials mainly involved in the embodiments are all conventional commercial products.

[0038] There are various methods known for producing naphthalene dicarboxylic acid, terephthalic acid and isophthalic acid.

[0039] CN87106585A invented a continuous production method for oxidizing alkyl aromatic compounds to aromatic carboxylic acids in the liquid phase using oxygen-containing gas in the presence of heavy metal compounds and / or bromine-containing compounds. However, the inventor believes that the naphthalene dicarboxylic acid obtained by this technology has a low purity.

[0040] CN111068759A discloses a method for preparing an alkylnaphthalene oxidation molecular sieve catalyst, which can make the catalytic oxidation conversion rate and selectivity of 2,6-dimethylnaphthalene both ≥98%, and the single-pass stability life test exceeds 700 hours. However, the catalyst is easy to deactivate, and it is difficult to separate it from the product, which affects the product quality.

[0041] CN100393687C invented a method for producing NDA by using a aging process. After the oxidation reaction is completed, heating aging is carried out. The gas used for aging is an inert gas or an atmosphere containing hydrogen. In essence, the aging process is a method of removing impurities by recrystallization and hydrogenation. However, the hydrogenation pressure of this technology is high, the operating conditions are harsh, and the impurity content of the obtained product quality is high.

[0042] CN105001073A invented a method and system for producing terephthalic acid with low energy consumption and low waste emissions, and made innovative inventions to the process flow, thereby simplifying the process flow and fully recycling the refined mother liquor, greatly reducing energy consumption and material consumption. However, the selection of catalyst was not as good as the inventors expected.

[0043] In summary, given that the prior art does not meet the inventor's expectations, the inventor made the present invention through further research and development.

[0044] Reference Figure 1 The process flow chart shown in the figure specifically illustrates the process flow of producing aromatic carboxylic acid according to the present invention.

[0045] (1) In an oxidation reactor 101, a raw material aromatic hydrocarbon b, a solvent and a catalyst c enter the reactor and react with oxygen in an oxygen-containing gas a under a first oxidation condition to obtain a first oxidation slurry d;

[0046] (2) introducing the first oxidation slurry d in step (1) into a deep oxidation reactor 102, and performing deep oxidation under a second oxidation condition, wherein the incompletely oxidized aromatic hydrocarbons and the intermediate products aldehydes and monocarboxylic acids further react with the oxygen in the oxygen-containing gas a to obtain a second oxidation slurry e;

[0047] (3) Cooling the tail gas in step (1) and step (2) through the oxidation tail gas treatment system 103 to separate the tail gas containing water vapor, and the condensate after condensation is an aqueous solution containing acetic acid, which is returned to the oxidation reactor 101 for recycling;

[0048] In a preferred embodiment of the present invention, it also includes:

[0049] (4) The second oxidation slurry e is crystallized, filtered, washed, and dried to obtain an aromatic carboxylic acid product.

[0050] The inventors applied the designed catalyst systems to the conventional aromatic carboxylic acid production process to obtain the following Examples 1-5.

[0051] Example 1

[0052] This embodiment provides a catalyst system, which is prepared by the following method: (NH4)3[CoMo6(OH)6O 18 , manganese acetate and a promoter, hydrobromic acid, are mixed to obtain the catalyst system of this embodiment;

[0053] Through infrared spectroscopy and XRD detection, it was determined that the catalyst system of this embodiment was Anderson type;

[0054] The cobalt ion concentration is 500 ppm, and the molar ratio of cobalt: manganese: bromine is 1:1:1.

[0055] Example 2

[0056] This embodiment provides a catalyst system, which is prepared by the following method: (NH4)3[CoMo6(OH)6O 18 , manganese acetate and a promoter, hydrobromic acid, are mixed to obtain the catalyst system of this embodiment;

[0057] The cobalt ion concentration is 800 ppm, and the molar ratio of cobalt: manganese: bromine is 1:1:2.

[0058] Example 3

[0059] This embodiment provides a catalyst system, which is prepared by the following method: (NH4)3[CoMo6(OH)6O 18 , manganese acetate and a promoter, hydrobromic acid, are mixed to obtain the catalyst system of this embodiment;

[0060] The cobalt ion concentration is 1500 ppm, and the molar ratio of cobalt: manganese: bromine is 1:1:2.

[0061] Example 4

[0062] This embodiment provides a catalyst system, which is prepared by the following method: (NH4)3[CoMo6(OH)6O 18 , manganese acetate and a promoter (sodium bromide) are mixed to obtain the catalyst system of this embodiment;

[0063] The cobalt ion concentration was 1200 ppm, and the molar ratio of cobalt: manganese: bromine was 1:2:1.

[0064] Example 5

[0065] This embodiment provides a catalyst system, which is prepared by the following method: (NH4)3[CoMo6(OH)6O 18 , manganese acetate and a promoter (a mixture of hydrobromic acid and potassium bromide) were mixed to obtain the catalyst system of this embodiment;

[0066] The cobalt ion concentration is 2000 ppm, and the molar ratio of cobalt: manganese: bromine is 1:2:2.

[0067] The molecular sieve disclosed in Patent No. CN111068759A was selected for catalytic production of aromatic carboxylic acids as Comparative Example 1 of the present invention.

[0068] The catalyst systems provided in the above Examples 1 to 5 and Comparative Example 1 were used in the production process of aromatic carboxylic acids, and the conversion rate of aromatic hydrocarbons and the selectivity of aromatic carboxylic acids were calculated. The calculation results are recorded in the following Table 1;

[0069] Among them, the conventional production process of aromatic carboxylic acid in the prior art is adopted, and the specific operation includes: in a reactor, adding an experimentally measured amount of 2,6-dimethylnaphthalene to an acetic acid solvent with a water content of 8%, controlling the solvent: raw material = 99:1, adding an experimentally measured amount of catalyst, heating to 180°C, passing air to react, and returning the tail gas discharged from the top to the reactor after cooling. After the reaction is completed, sampling and analyzing the conversion rate of the raw material and the yield of the product. The comparative example reference is Example Sample 3 in Patent No. CN111068759A.

[0070] Table 1 Calculation / test results of Examples 1 to 5 and Comparative Example 1

[0071] Aromatic hydrocarbon conversion rate / % Aromatic carboxylic acid selectivity / % Catalyst deactivation time / h Example 1 99.1 98.3 not inactivated Example 2 99.8 99.1 not inactivated Example 3 99.9 98.5 not inactivated Example 4 99.9 98.3 not inactivated Example 5 99.9 98.1 not inactivated Comparative Example 1 >99 >98 <900

[0072] The calculation results in Table 1 show that when the catalyst system provided by the present invention is used in the conventional production process of aromatic carboxylic acids, the conversion rate of aromatic hydrocarbons and the selectivity of aromatic carboxylic acids are similar to those when molecular sieves are used as catalysts in the prior art; however, the catalyst system of the present invention has no deactivation problem and is significantly better than the comparative example.

[0073] Therefore, the inventors believe that the catalyst system provided by the present invention can not only improve the conversion rate of the reactant aromatic hydrocarbons and the selectivity of aromatic carboxylic acids for the production of aromatic carboxylic acids, but also enable the production process system of aromatic carboxylic acids to operate stably for a long time, and has excellent industrial application value.

[0074] Taking the catalyst system provided in the above-mentioned Examples 2 and 3 as an example, it is applied to the production process of the aromatic carboxylic acid of the present invention to obtain the following Application Examples 1 to 4.

[0075] Application Example 1

[0076] This application example uses oxidation + two-stage deep oxidation to produce 2,6-naphthalene dicarboxylic acid, specifically including:

[0077] Air (oxygen-containing gas a), 2,6-dimethylnaphthalene (aromatic hydrocarbon b), acetic acid solution and the catalyst system (solvent and catalyst c) prepared in Example 2 are added to the oxidation reactor 101, wherein the mass content of water in the acetic acid solution is 8%;

[0078] The feed flow rate of 2,6-dimethylnaphthalene is controlled to be 1135 kg / h, the mass ratio of the acetic acid solution to the 2,6-dimethylnaphthalene is 10:1, the reaction operating temperature is 160° C., the operating pressure is 0.8 MPaG, and the reaction residence time is 30 min, to obtain an oxidized slurry d;

[0079] The oxidation slurry d is passed into the first deep oxidation reactor 102 for further deep oxidation. The oxygen-containing gas a in the first deep oxidation reactor 102 is the tail gas after the oxidation in the oxidation reactor 101 is completed. After the tail gas is treated by the oxidation tail gas treatment system 103, the oxygen is transported to the next deep oxidation reactor 102, wherein the oxygen content is 3.5% (v / v, referring to the ratio of oxygen in the tail gas to the total volume of the tail gas); in the first deep oxidation reactor 102, the deep oxidation reaction operating temperature is controlled to be 220° C., the operating pressure is 2.2 MPaG, and the reaction residence time is 60 min;

[0080] After the reaction is completed, it enters the second deep oxidation reactor 102 to continue the reaction, and the oxygen-containing gas a is the tail gas discharged from the first deep oxidation reactor 102, wherein the oxygen content is 0.5%. The reaction conditions are an operating temperature of 200°C, an operating pressure of 1.8MPaG, and a reaction residence time of 60min to obtain a second oxidation slurry e, which is then crystallized, filtered, washed, and dried to obtain a 2,6-naphthalenedicarboxylic acid product.

[0081] Application Example 2

[0082] This application example uses oxidation + two-stage deep oxidation to produce 2,6-naphthalene dicarboxylic acid, specifically including:

[0083] Air (oxygen-containing gas a), 2,6-dimethylnaphthalene (aromatic hydrocarbon b), acetic acid solution and the catalyst system (solvent and catalyst c) prepared in Example 2 are added to the oxidation reactor 101, wherein the mass content of water in the acetic acid solution is 10%;

[0084] The feed flow rate of 2,6-dimethylnaphthalene is controlled to be 1135 kg / h, the mass ratio of the acetic acid solution to the 2,6-dimethylnaphthalene is 8:1, the reaction operating temperature is 180° C., the operating pressure is 1.5 MPaG, and the reaction residence time is 60 min, to obtain an oxidized slurry d;

[0085] The oxidation slurry d is passed into the first deep oxidation reactor 102 for further deep oxidation. The oxygen-containing gas a in the first deep oxidation reactor 102 is the tail gas after the oxidation in the oxidation reactor 101 is completed. After the tail gas is treated by the oxidation tail gas treatment system 103, the oxygen is transported to the next deep oxidation reactor 102, wherein the oxygen content is 3.5% (v / v, referring to the ratio of oxygen in the tail gas to the total volume of the tail gas); in the first deep oxidation reactor 102, the deep oxidation reaction operating temperature is controlled to be 220° C., the operating pressure is 2.2 MPaG, and the reaction residence time is 45 min;

[0086] After the reaction is completed, the second deep oxidation reactor 102 is entered to continue the reaction. The oxygen-containing gas a is the tail gas discharged from the first deep oxidation reactor 102, wherein the oxygen content is 0.5%. The reaction conditions are an operating temperature of 200°C, an operating pressure of 1.8 MPaG, and a reaction residence time of 45 minutes to obtain a second oxidation slurry e, which is then crystallized, filtered, washed, and dried to obtain a 2,6-dimethylnaphthalene product.

[0087] Application Example 3

[0088] This application example uses oxidation + two-stage deep oxidation to produce 2,6-naphthalene dicarboxylic acid, specifically including:

[0089] Air (oxygen-containing gas a), 2,6-dimethylnaphthalene (aromatic hydrocarbon b), acetic acid solution and the catalyst system (solvent and catalyst c) prepared in Example 3 were added to the oxidation reactor 101, wherein the mass content of water in the acetic acid solution was 12%;

[0090] The feed flow rate of 2,6-dimethylnaphthalene is controlled to be 1135 kg / h, the mass ratio of the acetic acid solution to the 2,6-dimethylnaphthalene is 5:1, the reaction operating temperature is 195° C., the operating pressure is 2.0 MPaG, and the reaction residence time is 45 min, to obtain an oxidized slurry d;

[0091] The oxidation slurry d is passed into the first deep oxidation reactor 102 for further deep oxidation. The oxygen-containing gas a in the first deep oxidation reactor 102 is the tail gas after the oxidation in the oxidation reactor 101 is completed. After the tail gas is treated by the oxidation tail gas treatment system 103, the oxygen is transported to the next deep oxidation reactor 102, wherein the oxygen content is 3.5% (v / v, referring to the ratio of oxygen in the tail gas to the total volume of the tail gas); in the first deep oxidation reactor 102, the deep oxidation reaction operating temperature is controlled to be 215° C., the operating pressure is 2.1 MPaG, and the reaction residence time is 35 min;

[0092] After the reaction is completed, the reaction is continued in the second deep oxidation reactor 102, and the oxygen-containing gas a is the tail gas discharged from the first deep oxidation reactor 102, wherein the oxygen content is 0.5%. The reaction conditions are an operating temperature of 205°C, an operating pressure of 1.9 MPaG, and a reaction residence time of 45 minutes to obtain a crude 2,6-dimethylnaphthalene product, which is then crystallized, filtered, washed, and dried to obtain a 2,6-dimethylnaphthalene product.

[0093] Application Example 4

[0094] This application example uses oxidation + two-stage deep oxidation to produce para-dimethylformic acid (PTA), specifically including:

[0095] Air (oxygen-containing gas a), 2,6-dimethylnaphthalene (aromatic hydrocarbon b), acetic acid solution and the catalyst system (solvent and catalyst c) prepared in Example 3 are added to the oxidation reactor 101, wherein the mass content of water in the acetic acid solution is 8%;

[0096] The feed flow rate of p-xylene is controlled to be 1135 kg / h, the mass ratio of the acetic acid solution to the 2,6-dimethylnaphthalene is 7:1, the reaction operating temperature is 185° C., the operating pressure is 1.6 MPaG, and the reaction residence time is 60 min to obtain an oxidized slurry d;

[0097] The oxidation slurry d is passed into the first deep oxidation reactor 102 for further deep oxidation. The oxygen-containing gas a in the first deep oxidation reactor 102 is the tail gas after the oxidation in the oxidation reactor 101 is completed. After the tail gas is treated by the oxidation tail gas treatment system 103, the oxygen is transported to the next deep oxidation reactor 102, wherein the oxygen content is 3.5% (v / v, referring to the ratio of oxygen in the tail gas to the total volume of the tail gas); in the first deep oxidation reactor 102, the deep oxidation reaction operating temperature is controlled to be 220° C., the operating pressure is 2.2 MPaG, and the reaction residence time is 45 min;

[0098] After the reaction is completed, the reaction is continued in the second deep oxidation reactor 102, and the oxygen-containing gas a is the tail gas discharged from the first deep oxidation reactor 102, wherein the oxygen content is 0.5%. The reaction conditions are an operating temperature of 205°C, an operating pressure of 1.9 MPaG, and a reaction residence time of 30 minutes to obtain a crude terephthalic acid product, which is then crystallized, filtered, washed, and dried to obtain a terephthalic acid product.

[0099] The conversion rates of aromatic hydrocarbons and the selectivities of aromatic carboxylic acids in the above Application Examples 1 to 4 were calculated, and the data results were recorded in Table 2 below.

[0100] Conversion rate / % Selectivity / % Application Example 1 99.9 96.3 Application Example 2 99.9 97.5 Application Example 3 99.9 98.6 Application Example 4 99.9 98.9

[0101] From the data results in Table 2, it can be seen that when the mass ratio of acetic acid solution to aromatic hydrocarbon is controlled between (5-10):1, the conversion rate of the method for producing aromatic carboxylic acid of the present invention is not less than 99.9%, and the selectivity is not less than 96.3%, indicating that the catalytic system has a good effect on the production of aromatic carboxylic acid; in addition, in combination with Application Examples 1-4, it can be found that the conversion rate of aromatic hydrocarbon and the selectivity of aromatic carboxylic acid can be further improved by combining the catalyst system of the present invention with the production method of aromatic carboxylic acid. At the same time, in the process of producing aromatic carboxylic acid, the present invention not only has milder reaction conditions, but also has better industrial application value and achieves better economic benefits.

[0102] Although the description of the present invention has been quite detailed and has been described in particular with respect to several described embodiments, it is not intended to be limited to any of these details or embodiments or any particular embodiment, so as to effectively cover the intended scope of the present invention. In addition, the present invention is described above with the embodiments foreseeable by the inventors, and its purpose is to provide a useful description, and those non-substantial changes to the present invention that are not currently foreseen may still represent equivalent changes of the present invention.

[0103] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0104] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A catalyst system, characterized in that The system comprises a main catalyst and a co-catalyst containing metal ions; the metal ions comprise cobalt and manganese, and the co-catalyst is selected from hydrobromic acid and / or bromine-containing inorganic salts.

2. The catalyst system according to claim 1, characterized in that The metal ions also include one or more of vanadium, molybdenum, nickel or tungsten.

3. The catalyst system according to claim 1, characterized in that The molar ratio of cobalt, manganese and bromine is 1:(1-2):(1-2).

4. The catalyst system according to claim 1, characterized in that The cobalt ion concentration is 500-2000 ppm.

5. The catalyst system according to claim 4, characterized in that The cobalt ion concentration is 800-1500 ppm.

6. The catalyst system according to claim 1, characterized in that The system is one of a Lindqvist type compound, a Keggin type compound, a Dawson type compound, an Anderson type compound, a Waugh type compound or a Silverton type compound.

7. Use of the catalyst system according to any one of claims 1 to 6 in the production of aromatic carboxylic acids.

8. A method for producing an aromatic carboxylic acid, characterized in that: The method uses the catalyst system according to any one of claims 1 to 6.

9. The method for producing an aromatic carboxylic acid according to claim 8, characterized in that: The method comprises: under the action of an organic acid aqueous solution and the catalyst system, the aromatic hydrocarbon and the oxygen-containing gas are subjected to oxidation and deep oxidation reactions in sequence to obtain the aromatic carboxylic acid.

10. The method for producing an aromatic carboxylic acid according to claim 9, characterized in that: The organic acid aqueous solution is a mixture of C2-C6 monocarboxylic acid and water in any ratio.

11. The method for producing an aromatic carboxylic acid according to claim 10, characterized in that: The mass content of the water is 5-20%.

12. The method for producing an aromatic carboxylic acid according to claim 11, characterized in that: The mass content of the water is 7-12%.

13. The method for producing an aromatic carboxylic acid according to claim 9, characterized in that: The oxygen-containing gas is selected from one of air, oxygen-enriched gas or oxygen-deficient gas.

14. The method for producing an aromatic carboxylic acid according to claim 9, characterized in that: The aromatic hydrocarbon is selected from one of 2,6-dimethylnaphthalene, p-xylene or m-xylene.

15. The method for producing an aromatic carboxylic acid according to claim 9, characterized in that: The mass ratio of the organic acid aqueous solution to the aromatic hydrocarbon is (3-20):

1.

16. The method for producing an aromatic carboxylic acid according to claim 15, characterized in that: The mass ratio of the organic acid aqueous solution to the aromatic hydrocarbon is (5-10):

1.

17. The method for producing an aromatic carboxylic acid according to claim 9, characterized in that: The operating conditions of the oxidation are: temperature 160-220° C., pressure 0.8-2.5 MPaG, and residence time 30-90 min; the operating conditions of the deep oxidation are: temperature 190-250° C., pressure 0.8-2.5 MPaG, and residence time 30-150 min.

18. The method for producing an aromatic carboxylic acid according to claim 17, characterized in that: The operating conditions of the oxidation are: temperature 180-195°C, pressure 1.5-2.0 MPaG, and residence time 45-60 min; the operating conditions of the deep oxidation are: temperature 200-220°C, pressure 1.8-2.2 MPaG, and residence time 75-120 min.

19. A production system for aromatic carboxylic acids, characterized in that: The system is used to implement the production method according to any one of claims 8 to 18, wherein the system comprises an oxidation reactor and a deep oxidation reactor; The oxidation reactor is used for preliminarily oxidizing aromatic hydrocarbons to obtain a first oxidized slurry; the deep oxidation reactor is used for deeply oxidizing incompletely oxidized aromatic hydrocarbons and intermediate products in the first oxidized slurry to obtain a second oxidized slurry; At least one deep oxidation reactor is provided; and a plurality of deep oxidation reactors are connected in series.

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