Bubble column reactor and method for preparing naphthoic acid compound

Abstract

The present application relates to the technical field of fine chemical equipment and to a bubble column reactor and method for preparing a naphthoic acid compound. The bubble column reactor comprises: a column body in which a reaction chamber is provided; a gas distributor at least partially arranged in the reaction chamber, wherein the section of the gas distributor that is located inside the reaction chamber is provided with at least one first through hole in communication with the reaction chamber, and the axis of the first through hole forms an acute angle with an outer surface of the gas distributor or a tangent line at the outer surface of the gas distributor, so that a gas blown out of the gas distributor drives a liquid to flow and prolong the suspension time of solids in the liquid; and an air pump system configured to be in communication with the gas distributor and supply the gas. During reaction, a liquid containing a solid catalyst is injected into the reaction chamber, and the liquid is guided by means of second through holes on the gas distributor, thereby increasing the suspension time of the solid catalyst in the liquid, thus enhancing the mass transfer effect.

Description

Bubble column reactor and method for preparing naphthoic acid compounds

[0001] This application claims priority to Chinese Patent Application No. 202411842865.2, filed on December 12, 2024, entitled "Bubble Tower Reactor and Method for Preparing Naphthoic Acid Compounds", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application belongs to the field of fine chemical equipment technology, and in particular relates to a bubble column reactor and method for preparing naphthoic acid compounds. Background Technology

[0003] Alkyl oxidation of aromatic hydrocarbons is a highly useful type of chemical reaction. The resulting carboxylic acid derivatives containing aromatic rings are important fine chemical intermediates, widely used in pharmaceuticals, chemicals, and food. Benzoic acid, for example, is one of the simplest aromatic acids and is commonly used as a pharmaceutical or preservative. It also has wide applications in synthetic fibers, resins, and coatings. Naphthoic acid and its derivatives are another class of aromatic carboxylic acids, used in pesticides, photosensitive materials, dyes, and organic pigments.

[0004] Existing methods for preparing naphthoic acid compounds involve the catalytic oxidation of alkylnaphthalenes in a bubble column reactor. However, the solid catalyst used for the catalytic reaction in the bubble column reactor sinks rapidly under gravity, resulting in short mass transfer time and poor mass transfer efficiency, which severely affects the preparation of naphthoic acid compounds. Summary of the Invention

[0005] This application provides a bubble column reactor that improves mass transfer time and efficiency by changing the structure of the through holes on the gas distributor to allow solids to remain suspended in the liquid for a longer period of time.

[0006] This application provides a bubble column reactor, comprising:

[0007] The tower body has a reaction chamber inside;

[0008] A gas distributor is at least partially disposed within the reaction chamber. The gas distributor located within the reaction chamber has at least one first through hole communicating with the reaction chamber. The axis of the first through hole forms an acute angle with the outer surface of the gas distributor or the tangent of the outer surface of the gas distributor, so that the gas blown out by the gas distributor drives the liquid flow in the reaction chamber, thereby prolonging the suspension time of the solids in the liquid.

[0009] A gas pump system, which is connected to the gas distributor, is used to supply the gas.

[0010] In this embodiment of the application, a liquid guide is also included, which is at least partially disposed in the reaction chamber. The liquid guide located in the reaction chamber is provided with at least one second through hole communicating with the reaction chamber.

[0011] The circulation system is connected at both ends to the liquid guide and the reaction chamber, respectively, for circulating the liquid.

[0012] In this embodiment of the application, the liquid distributor includes a first tube and a second tube;

[0013] The first tube is disposed on the tower body, at least a portion of the first tube extends into the reaction chamber, the second tube is connected to the first tube, the second tube and the first tube have an angle between them, and the first through hole is disposed on the second tube.

[0014] In this embodiment of the application, the liquid guide includes a third tube and a fourth tube;

[0015] The third tube is disposed on the tower body, at least a portion of the third tube extends into the reaction chamber, and one end of the third tube is connected to the circulation system;

[0016] The fourth tube is disposed inside the reaction chamber and communicates with the other end of the third tube, and the second through hole is disposed on the fourth tube.

[0017] In this embodiment of the application, the second through hole is located below the first through hole.

[0018] In this embodiment of the application, the fourth tube is an annular tube, and the second tube is inserted into the middle of the fourth tube.

[0019] Secondly, a method for preparing naphthoic acid compounds is provided, the method comprising:

[0020] First, add the alkyl naphthalene solution and the composite catalyst together into the reaction chamber;

[0021] During the oxidation reaction, oxygen is continuously introduced into the reaction chamber through a gas distributor so that at least a portion of the composite catalyst is suspended under the guidance of the oxygen.

[0022] The unreacted alkylnaphthalene solution at the top of the reaction chamber is circulated through a circulation system to flow out from the liquid guide at the bottom, so that the unreacted alkylnaphthalene solution, a portion of the suspended composite catalyst, and the oxygen can undergo an oxidative catalytic reaction to obtain naphthoic acid compounds.

[0023] In the embodiments of this application, the temperature of the oxidation catalytic reaction is 90-130°C, and the pressure of the oxidation catalytic reaction is 0.1-0.5 MPa.

[0024] In the embodiments of this application, the oxygen flow rate is 0.05–1.8 mL / (min·gram alkylnaphthalene), and the oxygen content is 18–99 vol%.

[0025] In the embodiments of this application, the solvent in the alkylnaphthalene solution includes one or more of acetic acid, acetonitrile, propionic acid, and acetic anhydride.

[0026] This application provides a bubbling tower reactor, comprising: a tower body with a reaction chamber inside; a gas distributor, at least partially disposed within the reaction chamber, wherein the gas distributor within the reaction chamber has at least one first through-hole communicating with the reaction chamber, the axis of the first through-hole forming an acute angle with the outer surface of the gas distributor or the tangent to the outer surface of the gas distributor, so that the gas blown out by the gas distributor drives the liquid flow, prolonging the suspension time of solids in the liquid; and a gas pump system, connected to the gas distributor, for supplying gas. During the reaction, a solution containing a composite catalyst is injected into the reaction chamber, and the liquid is guided through a second through-hole on the gas distributor, increasing the suspension time of the solid catalyst in the liquid, thereby improving the mass transfer effect. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of the embodiments of this application.

[0028] Figure 1 is a schematic diagram of the bubble column reactor provided in this application;

[0029] Figure 2 is a schematic diagram of the gas distributor in Figure 1;

[0030] Figure 3 is a schematic diagram showing the angle at which the first through hole on the second tube in Figure 2 is circular;

[0031] Figure 4 is a schematic diagram showing that the first through hole on the second tube in Figure 2 is square.

[0032] Figure 5 is a schematic diagram of the liquid guide device in Figure 1;

[0033] Figure 6 is a schematic diagram of the second through hole on the fourth tube in Figure 5;

[0034] Figure 7 is a flow diagram of the vertical water flow in the bubbling tower reactor provided in this application;

[0035] Figure 8 is a flow diagram of the lateral flow of water in the bubbling tower reactor provided in this application.

[0036] Reference numerals: 100-Tower body; 110-Reaction chamber; 120-Circulating liquid outlet; 130-Gas outlet; 200-Gas distributor; 210-First through hole; 220-First pipe body; 230-Second pipe body; 300-Liquid guide; 310-Second through hole; 320-Third pipe body; 330-Fourth pipe body; 400-Circulation system; 500-Solid filter plate; 600-Pressure control system.

[0037] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0038] You can refer to the following stock phrases:

[0039] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0040] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those illustrated or described herein.

[0043] In this application, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0044] In the description of the embodiments of this application, it should be understood that the terms "inner", "outer", "upper", "bottom", "front", "rear", etc., indicate the orientation or positional relationship (if any) based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] Alkyl oxidation of aromatic hydrocarbons is a highly useful type of chemical reaction. The resulting carboxylic acid derivatives containing aromatic rings are important fine chemical intermediates, widely used in pharmaceuticals, chemicals, and food. Benzoic acid, for example, is one of the simplest aromatic acids and is commonly used as a pharmaceutical or preservative. It also has wide applications in synthetic fibers, resins, and coatings. Naphthoic acid and its derivatives are another class of aromatic carboxylic acids, used in pesticides, photosensitive materials, dyes, and organic pigments.

[0046] Existing methods for preparing naphthoic acid compounds involve the catalytic oxidation of alkylnaphthalenes in a bubble column reactor. However, the solid catalyst used for the catalytic reaction in the bubble column reactor sinks rapidly under gravity, resulting in short mass transfer time and poor mass transfer efficiency, which severely affects the preparation of naphthoic acid compounds.

[0047] The following describes the bubble column reactor. Its main function is to facilitate gas-liquid-solid reactions and mass transfer. The reactor ensures contact between gas, liquid, and solid phases by uniformly distributing gas as small bubbles and continuously passing through the gas-liquid reaction layer, allowing for thorough mixing and chemical reaction. It features a simple structure, is easy to clean, operates stably, and has low investment and maintenance costs. Furthermore, the bubble column reactor boasts extremely high liquid storage capacity and interphase contact area, resulting in high mass and heat transfer efficiency, making it suitable for slow chemical reactions and highly exothermic situations.

[0048] Existing bubble column reactors include a reaction chamber and a gas distributor disposed within the reaction chamber. The gas distributor is used to generate bubbles, thereby facilitating mass transfer with the liquid and solid catalyst entering the reaction chamber.

[0049] In the aforementioned bubble column reactor, the solid catalyst sinks rapidly under the influence of gravity, resulting in short mass transfer time and poor mass transfer effect.

[0050] The technical solution provided in this application is a bubble column reactor equipped with a specially structured gas distributor, which improves gas-liquid mass transfer efficiency, shortens reaction time, thereby reducing side reactions and improving oxidation reaction efficiency. The following will further describe this application with reference to the accompanying drawings.

[0051] Figure 1 is a schematic diagram of the bubble column reactor provided in this application. Figure 2 is a schematic diagram of the gas distributor in Figure 1. Figure 3 is a schematic diagram of the first through hole on the second tube in Figure 2 when it is circular. Figure 4 is a schematic diagram of the first through hole on the second tube in Figure 2 when it is square. Figure 5 is a schematic diagram of the liquid guide in Figure 1. Figure 6 is a schematic diagram of the second through hole on the fourth tube in Figure 5. Figure 7 is a flow diagram of the vertical water flow in the bubble column reactor provided in this application. Figure 8 is a flow diagram of the horizontal water flow in the bubble column reactor provided in this application.

[0052] Referring to Figures 1, 2, and 5, this application provides a bubble column reactor, comprising:

[0053] The tower body 100 has a reaction chamber 110 inside.

[0054] A gas distributor 200 is at least partially disposed within the reaction chamber 110. The gas distributor 200 located within the reaction chamber 110 is provided with at least one first through hole 210 communicating with the reaction chamber 110. The axis of the first through hole 210 forms an acute angle with the outer surface of the gas distributor 200 or the tangent of the outer surface of the gas distributor 200, so that the gas blown out by the gas distributor 200 drives the liquid flow in the reaction chamber 110, thereby prolonging the suspension time of solids in the liquid.

[0055] The liquid guide 300 is disposed in the reaction chamber 110 and has at least one second through hole 310 communicating with the reaction chamber 110.

[0056] The circulation system 400 is connected at both ends to the liquid guide 300 and the reaction chamber 110, respectively, and is used to circulate liquid.

[0057] A gas pump system, which is connected to a gas distributor 200, is used to supply gas.

[0058] In this application, during the chemical reaction process, liquid containing a solid catalyst is injected into the reaction chamber 110 through the first through-hole 210 of the liquid guide 300, and the liquid is guided through the second through-hole 310 of the gas distributor 200, thereby increasing the suspension time of the solid catalyst in the liquid and improving the mass transfer effect.

[0059] The tower body 100 is a cylindrical or cuboid structure, and the reaction chamber 110 inside it is used to provide a working place for mass transfer. The inner wall of the reaction chamber 110 is provided with a protective layer to isolate the tower body 100 from the chemical substances inside the reaction chamber 110, so as to avoid damage to the tower body 100.

[0060] The top of the tower body 100 is provided with a liquid outlet, and the bottom of the tower body 100 is provided with a liquid inlet. When a reaction is required, liquid containing solids is input through the liquid inlet. After the liquid in the reaction chamber 110 reaches the preset value, the circulation system 400 is started to circulate the liquid. The gas pump system emits gas through the gas generator to guide the liquid, thereby increasing the suspension time of solids in the liquid and achieving the effect of increasing mass transfer.

[0061] As shown in Figure 2, in this embodiment of the application, the gas distributor 200 includes a first tube 220 and a second tube 230.

[0062] The first tube 220 is disposed on the tower body 100, at least part of the first tube 220 extends into the reaction chamber 110, the second tube 230 is connected to the first tube 220, the second tube 230 and the first tube 220 have an angle between them, and the first through hole 210 is disposed on the second tube 230.

[0063] The included angle between the second tube 230 and the first tube 220 is 45-135 degrees. In this embodiment, the included angle is 90 degrees to facilitate the formation of a horizontal flow guide in the first through hole 210.

[0064] In the embodiments of this application, the second tube 230 is rectangular or cylindrical in shape.

[0065] As shown in Figure 3, a represents the tangent, c represents the axis, and α represents the angle between the tangent and the axis. Only one first through-hole 210 is shown in the figure; in actual installation, multiple through-holes can be arranged in a ring as needed. When both the first tube 220 and the second tube 230 are cylindrical glass tubes, the opening diameter of the first through-hole 210 is 0.001-2 mm, preferably 0.01-1 mm. α is 1-89 degrees, preferably 15-75 degrees.

[0066] The liquid can be controlled to flow in a clockwise direction through the first through hole 210, thereby increasing the suspension time of the solid.

[0067] For example, as shown in Figure 4, c is the axis, and α is the angle between the outer surface of the second tube 230 and the axis. Only one first through hole 210 is shown in the figure; in actual installation, multiple holes can be arranged in a ring shape as needed. When both the first tube 220 and the second tube 230 are rectangular glass tubes, the opening diameter of the first through hole 210 is 0.001-2 mm, preferably 0.01-1 mm. α is 1-89 degrees, preferably 15-75 degrees.

[0068] The tower body 100 is provided with a mounting hole for the first tube 220, which is used to fix the first tube 220. The first end of the first tube 220 is located outside the tower body 100 and is used to connect to the air pump system. The second end is located inside the reaction chamber 110 and is used to connect to the second tube 230.

[0069] In this embodiment, the liquid guide 300 includes a third tube 320 and a fourth tube 330;

[0070] As shown in Figure 5, the third tube 320 is installed on the tower body 100, and at least part of the third tube 320 extends into the reaction chamber 110. One end of the third tube 320 is connected to the circulation system 400.

[0071] The fourth tube 330 is disposed inside the reaction chamber 110 and is connected to the other end of the third tube 320. The second through hole 310 is disposed on the fourth tube 330.

[0072] The tower body 100 is provided with a mounting hole for a third tube 320 for fixing the third tube 320. The mounting holes of the first tube 220 and the third tube 320 are arranged opposite to each other on both sides of the tower body 100. The first end of the third tube 320 is located outside the tower body 100 and is connected to the circulation system 400. The second end of the third tube 320 is located inside the reaction chamber 110 and is used to connect to the fourth tube 330.

[0073] The third tube 320 is used to receive the liquid circulating in the circulation system 400 and guide it through the fourth tube 330 to the reaction chamber 110, thereby better dispersing the solids in the liquid.

[0074] In this embodiment, the second through-hole 310 is located below the first through-hole 210. This ensures that all the liquid output from the lower second through-hole 310 can pass through the first through-hole 210, thereby ensuring the suspension of solids and preventing solids from agglomerating and affecting mass transfer efficiency.

[0075] As shown in Figure 6, in this embodiment of the application, the second through hole 310 is provided at the lower part of the fourth tube 330. This is to prevent solids in the liquid from accumulating on the second through hole 310 of the fourth tube 330 during circulation.

[0076] As shown in Figures 7 and 8, in this embodiment of the application, the fourth tube 330 is an annular tube, and the second tube 230 is inserted into the middle of the fourth tube 330.

[0077] The third tube 320 is horizontally positioned inside the reaction chamber 110, and the fourth tube 330 is horizontally connected to the third tube 320. The fourth tube 330 is located around the outside of the second tube 230, thereby ensuring that all the liquid output from the fourth tube 330 is affected by the guiding effect of the second tube 230.

[0078] As shown in Figure 7, the liquid exits from the bottom of the fourth tube 330 and moves upward after impacting the bottom. When it reaches the second tube 230, it is guided by the second tube 230. As shown in Figure 8, the guided liquid rotates clockwise, thereby reaching the solids in the suspended liquid.

[0079] In this embodiment, a solid filter plate 500 is also included. A circulating liquid outlet 120 is provided on the tower body 100. The circulating liquid outlet 120 is connected to the circulation system 400 and is located above the third pipe body 320. The solid filter plate 500 is disposed in the reaction chamber 110 and is located between the circulating liquid outlet 120 and the third pipe body 320.

[0080] The solid filter plate 500 is used to block solids from entering the circulation system 400, so as to avoid solids entering the circulation and thus reducing the mass transfer reaction effect.

[0081] In this embodiment of the application, a pressure control system 600 is also included. An outlet 130 is provided on the tower body 100. The outlet 130 is located above the circulating liquid outlet 120. The pressure control system 600 is connected to the outlet 130 and is used to control the pressure in the reaction chamber 110.

[0082] The air outlet 130 is located at the top of the tower body 100. An air zone is formed between the air outlet 130 and the circulating liquid outlet 120. This zone is used to store air and adjust the pressure in the reaction chamber 110 by releasing it through the pressure control system 600.

[0083] In this embodiment, a heating layer is also included, which is disposed on the outer wall of the tower body 100 and is used to heat the reaction chamber 110. The heating layer is an electric heating plate or an electric heating tube.

[0084] For example, a solid dispensing pipe is provided on the side wall of the tower body 100, and the solid dispensing pipe is provided with an openable and closable opening for adding solids midway.

[0085] In this embodiment, during the reaction process, liquid is injected into the reaction chamber through the second through hole of the liquid guide and guided through the second through hole of the gas distributor to increase the suspension time of the solid catalyst in the liquid, thereby improving the mass transfer effect.

[0086] Furthermore, this embodiment utilizes a specially structured gas distributor and liquid guide to improve the dispersion of gas in the reaction liquid. Small-sized bubbles can increase the contact area between the gas and the solid and liquid, thereby enhancing the catalytic effect. Simultaneously, it induces the solid catalyst in the bubbling tower to be fully dispersed in the reaction liquid system, slowing down the settling speed due to gravity, improving the suspension and dispersion effect, and further promoting the catalytic oxidation effect.

[0087] This embodiment also provides a method for preparing naphthoic acid compounds, employing the aforementioned gas distributor, the method comprising:

[0088] First, add the alkyl naphthalene solution and the composite catalyst together into the reaction chamber 110;

[0089] During the oxidation reaction, oxygen is continuously introduced into the reaction chamber through the gas distributor 200 so that at least part of the composite catalyst is suspended under the guidance of oxygen.

[0090] The unreacted alkylnaphthalene solution at the top of the reaction chamber 110 is circulated out through the liquid guide 300 at the bottom, so that the unreacted alkylnaphthalene solution, the suspended composite catalyst, and oxygen can undergo an oxidative catalytic reaction to obtain naphthoic acid compounds.

[0091] In this process, the alkylnaphthalene solution and the composite catalyst are injected into the reaction chamber 110 through the bottom of the tower body 100. The composite catalyst includes a solid catalyst and N-hydroxyphthalimide (NHPI).

[0092] During the catalytic oxidation process, the gas pump system supplies oxygen to the gas distributor 200. The oxygen flows out from the first through hole 210 after passing through the first tube 220 and the second tube 230 in sequence. Under the action of the first through hole 210, the alkyl naphthalene solution flows clockwise, thereby suspending the solid catalyst in the alkyl naphthalene solution.

[0093] The circulation system 400 allows the unreacted alkyl naphthalene solution at the top of the reaction chamber 110 to flow out through the second through-hole 310 of the liquid guide 300 located at the bottom, and move upwards to fully contact the suspended solid catalyst and oxygen, thereby obtaining naphthoic acid compounds. The bubble column reactor provided in this application effectively improves the preparation efficiency of naphthoic acid compounds.

[0094] For example, in the catalytic oxidation process, the oxidation reaction temperature is 90–130°C, the reaction pressure is 0.1–0.5 MPa, and the time is 4–12 h.

[0095] The oxygen flow rate is 0.05–1.8 mL / (min·gram alkylnaphthalene).

[0096] Oxygen is introduced into the reaction system in the form of oxygen-containing gas. The oxygen-containing gas contains 18–99 vol%.

[0097] The solvent includes one or more of acetic acid, acetonitrile, propionic acid, and acetic anhydride.

[0098] The mass ratio of solvent to alkylnaphthalene is 3 to 50:1.

[0099] The preparation method of the solid catalyst includes: mixing a salt solution containing Co2+ and Mn2+ with a supporting medium, removing water, and then calcining to obtain the solid catalyst.

[0100] The preparation methods of specific naphthoic acid compounds will be described in detail below with reference to examples and comparative examples.

[0101] Example 1

[0102] After mixing 100 mL of 0.03 mol / L CoCl2 aqueous solution with 100 mL of 0.04 mol / L MnCl2 aqueous solution, 15 g of activated alumina was added. After stirring for 12 hours, water was removed by rotary evaporation, and the mixture was calcined at 350 °C for 4 hours. After cooling, solid catalyst Cat-1 was obtained.

[0103] 120 g of 3-chloro-2-methylnaphthalene was dissolved in 300 g of acetic acid and added to a bubble column along with 9 g of catalyst Cat-1 and 0.9 g of NHPI. The gas distributor had a cylindrical opening of 0.4 mm and an α = 5°. The liquid guide had an opening diameter of 8 mm. The oxygen-containing volume was 0.5 mL of oxygen / (min·g alkylnaphthalene). The reaction temperature was 130 °C, the pressure was 0.2 MPa, and the reaction time was 8 hours. The reaction was then stopped. The yield of 3-chloro-2-naphthoic acid was 85%.

[0104] Example 2

[0105] After mixing 100 mL of 0.05 mol / L Co(NO3)2 solution with 100 mL of 0.05 mol / L MnCl2 aqueous solution, 20 g of activated alumina was added. After stirring for 8 hours, water was removed by rotary evaporation, and the mixture was calcined at 400 °C for 6 hours. After cooling, solid catalyst Cat-2 was obtained.

[0106] 100g of 1-methylnaphthalene was dissolved in 400g of acetonitrile and added to a bubble column along with 12g of catalyst Cat-2 and 1g of NHPI. The gas distributor had a cylindrical opening of 0.8 mm and an α = 30°. The liquid guide had an opening of 2 mm. Air (oxygen content of 20%) was introduced at a rate of 0.75 mL of oxygen / (min·g alkylnaphthalene). The reaction temperature was 120℃, the pressure was 0.5 MPa, and the reaction time was 6 hours. The reaction was then stopped. The yield of 1-naphthoic acid was 92%.

[0107] Example 3

[0108] After mixing 200 mL of 0.25 mol / L Co(NO3)2 solution with 100 mL of 0.55 mol / L MnBr2 aqueous solution, 100 g of silicon dioxide was added. After stirring for 12 hours, water was removed by rotary evaporation, and the mixture was calcined at 380 °C for 3 hours. After cooling, solid catalyst Cat-3 was obtained.

[0109] 100g of 6-propionic-2-methylnaphthalene was dissolved in 500g of propionic acid and added together with 14.5g of catalyst Cat-3 and 5.5g of NHPI into a bubble column. The gas distributor had a cylindrical opening of 1 mm and α = 75°; the liquid guide had an opening of 5 mm. A mixture of 70% oxygen and 30% nitrogen was introduced at a flow rate of 1.4 mL oxygen / (min·g alkylnaphthalene). The reaction temperature was 125℃, the pressure was 0.3 MPa, and the reaction time was 4 hours. The reaction was then stopped. The yield of 6-propionic-2-naphthoic acid was 90%.

[0110] Example 4

[0111] 200 mL of 0.4 mol / L cobalt acetate solution was mixed with 300 mL of 0.3 mol / L manganese trifluoroacetate aqueous solution, and then 250 g of Y molecular sieve was added. After stirring for 3 hours, water was removed by rotary evaporation, and the mixture was calcined at 450 °C for 8 hours. After cooling, solid catalyst Cat-4 was obtained.

[0112] 100g of 2-cyclopentylnaphthalene was dissolved in 500g of acetic acid and added to a bubble column along with 15g of catalyst Cat-4 and 8g of NHPI. The gas distributor had a cylindrical opening of 0.05 mm and α = 60°; the liquid guide had an opening of 4 mm. Air (oxygen content 21%) was introduced at a rate of 1.5 mL oxygen / (min·g alkylnaphthalene). The reaction temperature was 118℃, the pressure was 0.3 MPa, and the reaction time was 5 hours. The reaction was then stopped. The yield of 2-naphthoic acid was 88%.

[0113] Example 5

[0114] After mixing 500 mL of 0.42 mol / L cobalt acetate solution with 300 mL of 0.55 mol / L manganese chloride aqueous solution, 550 g of ZSM-5 molecular sieve was added. After stirring for 10 hours, water was removed by rotary evaporation, and the mixture was calcined at 420 °C for 5 hours. After cooling, solid catalyst Cat-5 was obtained.

[0115] 100g of 6-methoxy-2-methylnaphthalene was dissolved in 900g of acetonitrile and added to a bubble column along with 20g of catalyst Cat-5 and 6g of NHPI. The gas distributor had a cylindrical opening of 0.6 mm and an α = 45° angle; the liquid guide had an opening of 5 mm. The oxygen-containing volume was 1.0 mL of oxygen / (min·g alkylnaphthalene). The reaction temperature was 125℃, the pressure was 0.3 MPa, and the reaction time was 12 hours. The reaction was then stopped. The yield of 6-methoxy-2-naphthoic acid was 94%.

[0116] Examples 1-5 describe the preparation of different naphthoic acid compounds using the bubble column reactor described in this application, specifically 3-chloro-2-naphthoic acid, 1-naphthoic acid, 6-propanoyl-2-naphthoic acid, 2-naphthoic acid, and 6-methoxy-2-naphthoic acid. The following will further illustrate this application by conducting controlled variable experiments under the conditions for preparing 1-naphthoic acid in Example 2.

[0117] Comparative Example 1

[0118] 100g of 1-methylnaphthalene was dissolved in 400g of acetonitrile. 12g of catalyst Cat-2 and 1g of NHPI were added to the reactor. Air (oxygen content of 20%) was directly introduced through the pipeline without a gas distributor, and no liquid guide or liquid circulation system was provided. The gas flow rate was 0.75 mL of oxygen / (min·g alkylnaphthalene). The reaction temperature was 120℃, the pressure was 0.5 MPa, and the reaction time was 6 hours. The reaction was then stopped, and the yield of 1-naphthoic acid was 42%. The reaction time was extended to 18 hours, and the yield of 1-naphthoic acid was 83%.

[0119] Comparative Example 2

[0120] 100g of 1-methylnaphthalene was dissolved in 400g of acetonitrile and added to a bubble column along with 12g of catalyst Cat-2 and 1g of NHPI. The gas distributor had a cylindrical opening of 0.8 mm and an α = 30°. Air (oxygen content of 20%) was introduced. There was no liquid guide or liquid circulation system. The gas flow rate was 0.75 mL of oxygen / (min·g alkylnaphthalene). The reaction temperature was 120℃, the pressure was 0.5 MPa, and the reaction time was 6 hours. The reaction was then stopped. The yield of 1-naphthoic acid was 58%.

[0121] Comparative Example 3

[0122] 100g of 1-methylnaphthalene was dissolved in 400g of acetonitrile and added together with 12g of catalyst Cat-2 and 1g of NHPI into a bubble column. There was no gas distributor; the liquid guide had an orifice diameter of 2mm. Air (oxygen content 20%) was introduced at a rate of 0.75 mL oxygen / (min·g alkylnaphthalene). The reaction temperature was 120℃, the pressure was 0.5 MPa, and the reaction time was 6 hours. The reaction was then stopped. The yield of 1-naphthoic acid was 60%.

[0123] Comparative Example 4

[0124] 100g of 1-methylnaphthalene was dissolved in 400g of acetonitrile and added to a bubble column along with 12g of catalyst Cat-2 and 1g of NHPI. The gas distributor was a cylindrical distributor with an opening of 0.8 mm and α = 30°. It had a liquid circulation system but no liquid guide. The circulating reaction liquid entered the bubble column directly through a straight pipe. Air (oxygen content of 20%) was introduced at a rate of 0.75 mL of oxygen / (min·g alkylnaphthalene). The reaction temperature was 120℃, the pressure was 0.5 MPa, and the reaction time was 6 hours. The reaction was then stopped. The yield of 1-naphthoic acid was 72%.

[0125] As can be seen from the above scheme, under the same conditions of added substance content and other conditions, comparative examples 1, 2, 3 and 4 respectively conducted controlled variable experiments on the absence of gas distributor, liquid guide and liquid circulation system, etc. The results of the experiments all showed that the 1-naphthoic acid separation yield of Example 2 was much higher than that of comparative examples 1, 2, 3 and 4 within the same time period.

[0126] Therefore, as can be seen from the above examples and comparative results, the technical solution provided by the present invention can effectively improve the reaction efficiency of alkyl naphthalene catalytic oxidation to prepare naphthoic acid compounds. Through the gas distributor and liquid guide with special structure, the gas, solid and liquid three-phase reaction system can be fully mixed, improving mass transfer efficiency, thereby improving the reaction effect, shortening the reaction time, and having high catalytic efficiency, which has obvious technical advantages.

[0127] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A bubble column reactor for preparing naphthoic acid compounds, characterized in that, include: The tower body (100) has a reaction chamber (110) inside; A gas distributor (200) is at least partially disposed within the reaction chamber (110). The gas distributor (200) located within the reaction chamber (110) is provided with at least one first through hole (210) communicating with the reaction chamber (110). The axis of the first through hole (210) forms an acute angle with the outer surface of the gas distributor (200) or the tangent of the outer surface of the gas distributor (200), so that the gas blown out by the gas distributor (200) drives the liquid in the reaction chamber (110) to flow, thereby prolonging the suspension time of solids in the liquid. A gas pump system, which is connected to the gas distributor (200), is used to supply the gas; A liquid guide (300) is at least partially disposed within the reaction chamber (110), and the liquid guide (300) located within the reaction chamber (110) is provided with at least one second through hole (310) communicating with the reaction chamber (110); The circulation system (400) is connected at both ends to the liquid guide (300) and the reaction chamber (110) respectively, and is used to circulate the liquid.

2. The bubble column reactor for preparing naphthoic acid compounds according to claim 1, characterized in that, The gas distributor (200) includes a first tube (220) and a second tube (230); The first tube (220) is disposed on the tower body (100), at least a portion of the first tube (220) extends into the reaction chamber (110), the second tube (230) communicates with the first tube (220), the second tube (230) and the first tube (220) have an angle between them, and the first through hole (210) is disposed on the second tube (230).

3. The bubble column reactor for preparing naphthoic acid compounds according to claim 2, characterized in that, The liquid guide (300) includes a third tube (320) and a fourth tube (330); The third tube (320) is disposed on the tower body (100), and at least a portion of the third tube (320) extends into the reaction chamber (110). One end of the third tube (320) is connected to the circulation system (400). The fourth tube (330) is disposed inside the reaction chamber (110) and communicates with the other end of the third tube (320), and the second through hole (310) is disposed on the fourth tube (330).

4. The bubble column reactor according to claim 3, characterized in that, The second through hole (310) is located below the first through hole (210).

5. The bubble column reactor for preparing naphthoic acid compounds according to claim 4, characterized in that, The fourth tube (330) is an annular tube, and the second tube (230) is inserted in the middle of the fourth tube (330).

6. A method for preparing naphthoic acid compounds, characterized in that, The methods include: First, add the alkyl naphthalene solution and the composite catalyst together into the reaction chamber (110); During the oxidation reaction, oxygen is continuously introduced into the reaction chamber (110) through a gas distributor (200) so that at least part of the composite catalyst is suspended under the guidance of the oxygen. The unreacted alkylnaphthalene solution at the top of the reaction chamber (110) is discharged from the liquid guide (300) at the bottom through the circulation system (400) so that the unreacted alkylnaphthalene solution, a portion of the suspended composite catalyst, and the oxygen can undergo an oxidative catalytic reaction to obtain naphthoic acid compounds.

7. The method for preparing naphthoic acid compounds according to claim 6, characterized in that, The temperature of the oxidation catalytic reaction is 90-130℃, and the pressure of the oxidation catalytic reaction is 0.1-0.5MPa.

8. The method for preparing naphthoic acid compounds according to claim 6, characterized in that, The oxygen flow rate is 0.05–1.8 mL / (min·gram alkylnaphthalene), and the oxygen content is 18–99 vol%.

9. The method for preparing naphthoic acid compounds according to claim 6, characterized in that, The solvent in the alkylnaphthalene solution includes one or more of acetic acid, acetonitrile, propionic acid, and acetic anhydride.

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