Method for preparing mononitroaromatic hydrocarbon using mixed acid of nitric acid and sulfuric acid

Abstract

A method for preparing a mononitroaromatic hydrocarbon using a mixed acid of nitric acid and sulfuric acid, comprising: preparing a mixed acid of nitric acid and sulfuric acid; gasifying an aromatic hydrocarbon to prepare a gaseous aromatic hydrocarbon; and mixing the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio, and subjecting the gaseous aromatic hydrocarbon and the mixed acid after the mixing to a gas-liquid heterogeneous reaction at a first preset temperature to prepare a mononitroaromatic hydrocarbon, wherein the preset ratio satisfies that the molar ratio of the nitric acid in the mixed acid to the gaseous aromatic hydrocarbon is 1:(1-2). The present application is used for using a mixed acid of nitric acid and sulfuric acid and a gaseous aromatic hydrocarbon to prepare a mononitroaromatic hydrocarbon.

Description

Method for preparing mononitroaromatics using nitric-sulfuric mixed acid

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202410160413.X, filed on February 4, 2024, entitled “Method for preparing mononitroaromatic hydrocarbons using nitric and sulfuric mixed acid”, the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the field of chemical engineering technology, and in particular to a method for preparing mononitroaromatic hydrocarbons by using nitric and sulfuric mixed acid. Background Art

[0004] The nitration reaction of aromatic hydrocarbons is a basic reaction in industrial production. Its products, nitroaromatic hydrocarbons, are important chemical raw materials and intermediates, and are widely used in the production of medicines, dyes, pesticides and energetic materials.

[0005] In current research, the nitration reaction of aromatics is mainly a liquid-liquid heterogeneous reaction between nitric and sulfuric acid mixtures and aromatics. Its intrinsic reaction rate is fast and the exothermic intensity is high. The reaction process is severely limited by mass transfer, resulting in a long residence time, which in turn easily leads to over-nitration side reactions and the production of polynitroaromatic by-products. As a result, the selectivity of mononitroaromatics is low, the efficiency is low, and the risk of combustion and explosion is prone to occur during the reaction and separation process, causing major safety hazards in the separation and purification process.

[0006] Summary of the Invention

[0007] Based on this, it is necessary to provide a method for preparing mononitroaromatics using nitric acid and sulfuric acid mixture to improve the selectivity and reaction efficiency of mononitroaromatics, reduce the difficulty of separation and purification, reduce the risk of combustion and explosion, and reduce safety hazards.

[0008] A method for preparing mononitroaromatic hydrocarbons using nitric-sulfuric mixed acid comprises:

[0009] Preparation of mixed acid of nitric acid and sulfuric acid;

[0010] Gasifying aromatic hydrocarbons to prepare gaseous aromatic hydrocarbons;

[0011] mixing the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio, and causing the mixed gaseous aromatic hydrocarbon and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature to prepare the mononitroaromatic hydrocarbon;

[0012] Wherein, the preset ratio satisfies: the molar ratio of nitric acid in the mixed acid to the gaseous aromatic hydrocarbon is 1:(1-2).

[0013] Optionally, the first preset temperature is greater than or equal to the boiling point of the aromatic hydrocarbon, and less than or equal to the sum of the boiling point of the aromatic hydrocarbon and 100°C.

[0014] Optionally, the aromatic hydrocarbons are gasified to prepare gaseous aromatic hydrocarbons, comprising:

[0015] The aromatic hydrocarbons are heated to a second preset temperature to vaporize the aromatic hydrocarbons into gaseous aromatic hydrocarbons; wherein the second preset temperature is greater than or equal to the boiling point of the aromatic hydrocarbons and less than or equal to the sum of the boiling point of the aromatic hydrocarbons and 100°C. Optionally, the second preset temperature is also greater than or equal to the first preset temperature.

[0016] Optionally, the mixing of the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio, and causing the mixed gaseous aromatic hydrocarbon and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature, comprises:

[0017] heating the mixed acid to the second preset temperature;

[0018] The gaseous aromatic hydrocarbon and the mixed acid are mixed at a first flow rate and a second flow rate, respectively, and the mixed gaseous aromatic hydrocarbon and the mixed acid are contacted at the first preset temperature for a preset time to react to generate the mononitroaromatic hydrocarbon; or the gaseous aromatic hydrocarbon is bubbled into the mixed acid and mixed with stirring, and after the bubbling is completed, the mixed gaseous aromatic hydrocarbon and the mixed acid are maintained at the first preset temperature for a preset time to react to generate the mononitroaromatic hydrocarbon;

[0019] Wherein, the first flow rate and the second flow rate satisfy: a molar ratio of the gaseous aromatic hydrocarbon and the mixed acid in a unit time satisfies the preset ratio.

[0020] Optionally, the preset time is 0.1s to 20s.

[0021] Optionally, the mixing and reaction process of the gaseous aromatic hydrocarbon and the mixed acid is carried out in a continuous flow reactor when the gaseous aromatic hydrocarbon and the mixed acid are mixed at a first flow rate and a second flow rate, respectively, and the mixed gaseous aromatic hydrocarbon and the mixed acid are contacted at the first preset temperature for a preset time to react to generate the mononitroaromatic hydrocarbon.

[0022] Optionally, the continuous flow reactor is a static mixer, a microreactor or a tubular reactor.

[0023] Optionally, the mixing and reaction process of the gaseous aromatic hydrocarbon and the mixed acid is carried out in a tank reactor, wherein the gaseous aromatic hydrocarbon is introduced into the mixed acid in a bubbling manner and the gaseous aromatic hydrocarbon and the mixed acid are mixed under stirring, and after the bubbling is completed, the mixed gaseous aromatic hydrocarbon and the mixed acid are maintained at the first preset temperature for a preset time to react to generate the mononitroaromatic hydrocarbon.

[0024] Optionally, the method further includes:

[0025] The product after the gas-liquid heterogeneous reaction is subjected to phase separation treatment to prepare the mononitroaromatic hydrocarbon.

[0026] Optionally, the product after the gas-liquid heterogeneous reaction is subjected to phase separation treatment to prepare the mononitroaromatic hydrocarbon, comprising:

[0027] After the gaseous aromatic hydrocarbon and the mixed acid are in contact at a first preset temperature for a preset time, performing a gas-liquid phase separation treatment on the product after the gas-liquid heterogeneous reaction occurs; and

[0028] The mixed solution obtained by gas-liquid phase separation treatment is subjected to liquid-liquid phase separation treatment, and the organic phase is collected.

[0029] Optionally, the preparation of a mixed acid of nitric acid and sulfuric acid comprises:

[0030] Diluting concentrated sulfuric acid to prepare a sulfuric acid solution with a mass percentage concentration of 50% to 90%;

[0031] The mixed acid is prepared by mixing fuming nitric acid and the sulfuric acid solution.

[0032] Optionally, the mass ratio of the fuming nitric acid to the sulfuric acid solution is 1:(100-1000).

[0033] Compared with the related art, the embodiments of the present application have the following technical effects:

[0034] Compared with the liquid-liquid nitration reaction of aromatic hydrocarbons and nitric-sulfuric mixed acid, by mixing gaseous aromatic hydrocarbons and mixed acid in a preset ratio and allowing the mixed gaseous aromatic hydrocarbons and mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature, the aromatic hydrocarbons can be mixed and contacted with the mixed acid in gaseous form. On the one hand, in the present application, gaseous aromatic hydrocarbons and mixed acids are used for reaction. Therefore, the reaction temperature used (that is, the first preset temperature in the present application) can be significantly higher than the temperature of the liquid-liquid nitration reaction. Therefore, the intrinsic reaction rate of the main reaction to produce mononitroaromatic hydrocarbons is greatly improved, and the occurrence of overnitration side reactions is greatly reduced, thereby improving the selectivity of mononitroaromatic hydrocarbons, reducing the risks of combustion and explosion caused by by-products, and the subsequent safety hazards in the separation and purification process. On the other hand, by mixing gaseous aromatics with mixed acids, the high diffusion coefficient of the gaseous aromatics can be utilized, thereby significantly improving the mass transfer effect during the reaction of gaseous aromatics and mixed acids, facilitating the full consumption of nitric acid in the main reaction, and reducing the production of polynitroaromatic by-products caused by slow mass transfer rates, thereby improving the selectivity of mononitroaromatics and reducing the reaction time of mononitroaromatics. It can also reduce the risks of explosion and combustion caused by by-products, as well as safety hazards in subsequent separation and purification processes. This solves the problem in the related art that the liquid-liquid mass transfer uniformity of aromatics and mixed acids during the reaction process is poor, resulting in an increase in by-products, making the selectivity of mononitroaromatics low, the efficiency low, and the risk of explosion and combustion easily occurring during the reaction process, causing greater safety hazards in the separation and purification process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] FIG1 is a schematic flow diagram of a method for preparing mononitroaromatics using nitric and sulfuric acid mixed acid provided in an embodiment of the present application. DETAILED DESCRIPTION

[0037] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0038] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as having an open, inclusive meaning, that is, "including, but not limited to." In the description of the specification, the terms "one embodiment," "some embodiments," "exemplary embodiments," "exemplarily," or "some examples" are intended to indicate that specific features, structures, materials, or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0039] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0040] As used herein, unless otherwise specified, "one or more" means one or more than two.

[0041] As used herein, the terms "for example," "such as," "example," and "for instance" are used for descriptive purposes to indicate that the preceding and following technical solutions are related in terms of their coverage, but should not be construed as limiting the preceding technical solution or the scope of protection herein. As used herein, unless otherwise specified, "A (such as B)" means that B is a non-limiting example of A, and it should be understood that A is not limited to B.

[0042] As used herein, "optionally," "optional," and "optional" mean optional or dispensable, meaning that the option is selected from either of two parallel options: "optional" or "optional." If a technical solution contains multiple "optional" clauses, each "optional" clause is considered independent unless otherwise specified and there are no conflicts or constraints.

[0043] Herein, descriptions such as “optionally contain” and “optionally include” mean “contain or not contain”. “Optional component X” means component X is present or not, or contains or not contains the component X.

[0044] In this document, the terms "first" and "second" in "the first aspect" and "the second aspect" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features.

[0045] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0047] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0048] In this document, "at least one" means more than one, such as one, two, or more than two. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layer" means at least two layers, such as two, three, etc., unless otherwise specifically defined. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise specifically defined.

[0049] Herein, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is considered continuous and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broad inclusion of numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0050] In this article, unless otherwise specified, the percentage content refers to mass percentage for solid-liquid mixing and solid-solid mixing, and refers to volume percentage for liquid-liquid mixing.

[0051] In this article, percentage concentrations, unless otherwise specified, refer to final concentrations, which are the percentage of an added ingredient in the system after the ingredient is added.

[0052] As used herein, % (w / w) and wt% both refer to weight percentage, % (v / v) refers to volume percentage, and % (w / v) refers to mass volume percentage.

[0053] In this article, when it comes to temperature parameters, unless otherwise specified, both constant temperature treatment and treatment within a certain temperature range are permitted. The constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument.

[0054] Herein, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments herein, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments herein, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0055] Based on the above technical problems, some embodiments of the present application provide a method for preparing mononitroaromatic hydrocarbons using nitric and sulfuric acid mixed acid, as shown in FIG1 . The method comprises the following steps S11) to S13):

[0056] S11), preparing a mixed acid of nitric acid and sulfuric acid;

[0057] Among them, the use of nitric and sulfuric acid mixture can efficiently produce the nitrification active intermediate NO2 + , thereby facilitating the efficient nitration of aromatics.

[0058] The specific preparation method of the mixed acid is not limited, as long as a nitric-sulfuric acid mixture can be obtained and the aromatic hydrocarbons can be nitrated using the nitric-sulfuric acid mixture. The specific concentration of the nitric-sulfuric acid mixture can be reasonably selected according to actual needs to reduce the formation of by-products such as sulfonation products and polynitroaromatic hydrocarbons.

[0059] In some embodiments, S11) preparing a mixed acid of nitric acid and sulfuric acid comprises the following steps S111) to S112):

[0060] S111), diluting concentrated sulfuric acid to prepare a sulfuric acid solution having a mass percentage concentration (i.e., mass fraction) of 50% to 90%;

[0061] The concentrated sulfuric acid may be one having a mass percent concentration (ie, mass fraction) of 98%. By diluting the concentrated sulfuric acid, a sulfuric acid solution having a mass percent concentration of 50% to 90% can be prepared.

[0062] S112), mixing fuming nitric acid and sulfuric acid solution to prepare the mixed acid.

[0063] The fuming sulfuric acid may be concentrated nitric acid having a mass percentage concentration of 98% of nitric acid.

[0064] The mixed acid is prepared by mixing fuming nitric acid and sulfuric acid solution; the method may include:

[0065] Add the fuming nitric acid to the sulfuric acid solution prepared in step S111) and mix them evenly; alternatively, add the sulfuric acid solution prepared in step S111) to the fuming nitric acid and mix them evenly.

[0066] The mass ratio of the fuming nitric acid and sulfuric acid solution when mixed can be reasonably selected according to actual needs and is not specifically limited here.

[0067] Among them, sulfuric acid is a strong acid that can provide protons for the dissociation of nitric acid, increasing the dissociation of nitric acid into NO2 + At the same time, sulfuric acid has a stronger affinity for water than nitric acid, which can reduce or avoid the dilution of nitric acid by the water generated by the reaction, thereby improving the utilization rate of nitric acid; and as nitric acid is diluted by sulfuric acid solution, its oxidizing ability and corrosion intensity decrease, it is not easy to produce oxidative side reactions, and can reduce the corrosion of cast iron equipment.

[0068] Based on this, in some embodiments of the present application, the mass ratio of the mixture of fuming nitric acid and sulfuric acid solution is 1:(100-1000).

[0069] In these embodiments, a nitric-sulfur mixed acid with an appropriate concentration can be provided to facilitate the nitration of aromatic hydrocarbons into mononitroaromatic hydrocarbons and reduce by-products.

[0070] S12), gasifying the aromatic hydrocarbons to prepare gaseous aromatic hydrocarbons;

[0071] The aromatic hydrocarbons may include compounds containing a benzene ring in the molecule, such as benzene, toluene, chlorobenzene, xylene, ethylbenzene, naphthalene, tetralin, and the like.

[0072] The aromatic hydrocarbons can be gasified in any manner as long as they can be converted into gaseous aromatic hydrocarbons. The specific gasification method is not limited here. The gasification can be heating gasification or spray gasification.

[0073] S13), mixing the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio, and allowing the mixed gaseous aromatic hydrocarbon and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature to prepare mononitroaromatic hydrocarbon.

[0074] Among them, the gaseous aromatic hydrocarbons and the mixed acid are mixed in a preset ratio, and the mixed gaseous aromatic hydrocarbons and the mixed acid are subjected to a gas-liquid heterogeneous reaction at a first preset temperature. Compared with the liquid-liquid mixing of aromatic hydrocarbons and the mixed acid in the related art and the liquid-liquid heterogeneous reaction, the dispersion effect of the gaseous aromatic hydrocarbons in the mixed acid can be increased, and the specific surface area of ​​the gaseous aromatic hydrocarbons and the mixed acid when in contact can be increased, thereby increasing the mass transfer effect and improving the uniformity of mass transfer; thereby solving the problems in the related art of slow mass transfer rate and poor uniformity of aromatic hydrocarbons and mixed acid during the reaction process, resulting in a long mononitration reaction time, an increase in by-products, low selectivity of mononitroaromatic hydrocarbons, low efficiency, and the risk of explosion and the like during the reaction process, causing greater safety hazards in the separation and purification process.

[0075] In some embodiments, the preset ratio satisfies: the molar ratio of nitric acid to gaseous aromatic hydrocarbon in the mixed acid is 1:(1-2).

[0076] In these embodiments, by controlling the molar ratio of nitric acid to gaseous aromatic hydrocarbons in the mixed acid to be 1:(1-2), the molar ratio of nitric acid to gaseous aromatic hydrocarbons can be effectively controlled, so that nitric acid and gaseous aromatic hydrocarbons can react to produce mononitroaromatic hydrocarbons rather than polynitroaromatic hydrocarbons.

[0077] Optionally, the molar ratio of nitric acid to gaseous aromatic hydrocarbons in the mixed acid is 1:1.1 to 1:1.5. This means that the gaseous aromatic hydrocarbons are slightly in excess, facilitating rapid consumption of nitric acid in the mononitration reaction to produce mononitroaromatic hydrocarbons during the gas-liquid heterogeneous reaction, thereby improving the selectivity of mononitroaromatic hydrocarbons and reducing the production of byproducts such as polynitroaromatic hydrocarbons. This also reduces safety hazards, improves reaction efficiency, and reduces unnecessary heat release, thereby reducing energy consumption.

[0078] In the method for preparing mononitroaromatics using nitric-sulfuric mixed acid provided in an embodiment of the present application, the gaseous aromatics and the mixed acid are mixed in a preset ratio, and the mixed gaseous aromatics and the mixed acid are subjected to a gas-liquid heterogeneous reaction at a first preset temperature, so that the aromatics can be mixed and contacted with the mixed acid in a gaseous form. On the one hand, the present application uses gaseous aromatics and mixed acids for reaction, so the reaction temperature used (i.e., the first preset temperature in the present application) can be significantly higher than the temperature of the liquid-liquid nitration reaction. Therefore, the intrinsic reaction rate of the main reaction to generate mononitroaromatics is greatly improved, and the occurrence of overnitration side reactions is greatly reduced, thereby improving the selectivity of mononitroaromatics and reducing the risks of combustion and explosion caused by by-products, as well as safety hazards in subsequent separation and purification processes. On the other hand, by mixing gaseous aromatics with mixed acids, the high diffusion coefficient of the gaseous aromatics can be utilized, thereby significantly improving the mass transfer effect during the reaction of gaseous aromatics and mixed acids, facilitating the full consumption of nitric acid in the main reaction, and reducing the production of polynitroaromatic by-products caused by slow mass transfer rates, thereby improving the selectivity of mononitroaromatics and reducing the reaction time of mononitroaromatics. It can also reduce the risks of explosion and combustion caused by by-products, as well as safety hazards in subsequent separation and purification processes. This solves the problem in the related art that the liquid-liquid mass transfer uniformity of aromatics and mixed acids during the reaction process is poor, resulting in an increase in by-products, making the selectivity of mononitroaromatics low, the efficiency low, and the risk of explosion and combustion easily occurring during the reaction process, causing greater safety hazards in the separation and purification process.

[0079] Among them, the specific implementation methods of the above-mentioned S12), gasifying the aromatic hydrocarbons to prepare gaseous aromatic hydrocarbons, and S13), mixing the gaseous aromatic hydrocarbons and the mixed acid in a preset ratio, and causing the mixed gaseous aromatic hydrocarbons and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature are not limited. As long as the aromatic hydrocarbons can be gasified, and the gaseous aromatic hydrocarbons and the mixed acid can be mixed in a preset ratio, and the mixed gaseous aromatic hydrocarbons and the mixed acid can undergo a gas-liquid heterogeneous reaction at a first preset temperature, all possible technical solutions for preparing mononitroaromatic hydrocarbons are within the scope of protection of this application.

[0080] In some embodiments of the present application, the aromatic hydrocarbons are gasified to prepare gaseous aromatic hydrocarbons; comprising:

[0081] Heating the aromatic hydrocarbon to a second preset temperature to vaporize the aromatic hydrocarbon into gaseous aromatic hydrocarbon; wherein the second preset temperature is greater than or equal to the boiling point of the aromatic hydrocarbon and less than or equal to the sum of the boiling point of the aromatic hydrocarbon and 100° C., and optionally, the second preset temperature is also greater than or equal to the first preset temperature;

[0082] The gaseous aromatic hydrocarbon and the mixed acid are mixed in a preset ratio, and the mixed gaseous aromatic hydrocarbon and the mixed acid are subjected to a gas-liquid heterogeneous reaction at a first preset temperature, comprising:

[0083] heating the mixed acid to a second preset temperature;

[0084] The gaseous aromatic hydrocarbon and the mixed acid are mixed at a first flow rate and a second flow rate, respectively, and the mixed gaseous aromatic hydrocarbon and the mixed acid are contacted at a first preset temperature for a preset time to react to produce a mononitroaromatic hydrocarbon; alternatively, the gaseous aromatic hydrocarbon is bubbled into the mixed acid and the gaseous aromatic hydrocarbon and the mixed acid are mixed under stirring, and after the bubbling is completed, the mixed gaseous aromatic hydrocarbon and the mixed acid are maintained at the first preset temperature for a preset time to react to produce the mononitroaromatic hydrocarbon;

[0085] The first flow rate and the second flow rate satisfy the following conditions: the molar ratio of the gaseous aromatic hydrocarbon and the mixed acid in a unit time satisfies the preset ratio.

[0086] In these embodiments, the gaseous aromatic hydrocarbon and the mixed acid are mixed at a first flow rate and a second flow rate, respectively, and the mixed gaseous aromatic hydrocarbon and the mixed acid are allowed to contact at a first preset temperature for a preset time to react to generate mononitroaromatic hydrocarbon. Since the first flow rate and the second flow rate satisfy: the molar ratio of the gaseous aromatic hydrocarbon and the mixed acid per unit time satisfies the above-mentioned preset ratio, the gaseous aromatic hydrocarbon and the nitric acid in the mixed acid can be continuously reacted in a precise mixing ratio. On the one hand, it is convenient for the gaseous aromatic hydrocarbon and the mixed acid to mix and contact at the first preset temperature; on the other hand, the contact time after the gaseous aromatic hydrocarbon and the mixed acid are mixed can be controlled, thereby facilitating the control of the reaction of the gaseous aromatic hydrocarbon and the mixed acid to generate mononitroaromatic hydrocarbon, further reducing the occurrence of side reactions.

[0087] By bubbling the gaseous aromatic hydrocarbon into the mixed acid and mixing the gaseous aromatic hydrocarbon and the mixed acid under stirring, the gaseous aromatic hydrocarbon and the mixed acid are also easily mixed and contacted at the first preset temperature. After the bubbling is completed, by maintaining the mixed gaseous aromatic hydrocarbon and mixed acid at the first preset temperature for a preset time, the gaseous aromatic hydrocarbon and the mixed acid can be fully contacted over a longer reaction time, thereby facilitating the reaction of the gaseous aromatic hydrocarbon and the mixed acid to generate mononitroaromatic hydrocarbons and reducing the occurrence of side reactions.

[0088] At the same time, in these embodiments, the aromatic hydrocarbons are gasified by heating. On the one hand, it is convenient to transport the aromatic hydrocarbons in a gaseous state, which can improve the mass transfer effect compared with the related art in which the aromatic hydrocarbons and mixed acid are transferred in a liquid state, the liquid viscosity is large, and the mass transfer resistance is large; on the other hand, by heating the mixed acid, the viscosity of the mixed acid can be reduced, which is convenient for transporting and mixing the mixed acid, thereby facilitating the mixing of the gaseous aromatic hydrocarbons and the mixed acid at a higher rate, thereby improving the mass transfer effect; on the other hand, the gaseous aromatic hydrocarbons and the mixed acid are mixed in a gaseous state, which can improve ... The hydrocarbons can contact the mixed acid at a higher specific surface area, which can improve the mass transfer effect, thereby making the mass and heat transfer between the gaseous aromatic hydrocarbons and the mixed acid uniform, facilitating the formation of mononitroaromatic hydrocarbons and reducing local high temperatures; and as the reaction proceeds, the volume of the aromatic hydrocarbon bubbles gradually decreases, further significantly reducing the interphase mass transfer resistance and significantly reducing the limitation of mass transfer on the nitration reaction. In this process, compared with liquid-liquid heterogeneous reactions, the mass transfer effect and mononitration rate can be improved, and reaction time can be saved, thereby improving the selectivity of mononitroaromatic hydrocarbons and further reducing the formation of polynitroaromatic hydrocarbons.

[0089] The preset time is not specifically limited, and the reaction time can be controlled according to the amount of reaction, temperature, mixing rate, etc., to minimize the limitation of mass transfer on the nitration reaction and increase the reaction rate.

[0090] In some embodiments, the preset time is 0.1s to 20s.

[0091] In these embodiments, by controlling the preset time to be 0.1s to 20s, the generation of polynitroaromatic by-products can be reduced to a certain extent, and the generation of mononitroaromatics can be increased, thereby improving the selectivity of mononitroaromatics and the efficiency.

[0092] Among them, there is no specific limitation on the type of reactor used for mixing the gaseous aromatic hydrocarbon and the mixed acid at the first flow rate and the second flow rate, respectively, and allowing the mixed gaseous aromatic hydrocarbon and the mixed acid to contact each other at the first preset temperature for a preset time. All reactors that can mix the gaseous aromatic hydrocarbon and the mixed acid at the first flow rate and the second flow rate, and allow the mixed gaseous aromatic hydrocarbon and the mixed acid to contact each other at the first preset temperature for a preset time are within the scope of protection of this application.

[0093] In some embodiments, the mixing and reaction process of the gaseous aromatic hydrocarbon and the mixed acid is carried out in a continuous flow reactor, where the gaseous aromatic hydrocarbon and the mixed acid are mixed at a first flow rate and a second flow rate, respectively, and the mixed gaseous aromatic hydrocarbon and the mixed acid are contacted at a first preset temperature for a preset time to react to produce mononitroaromatic hydrocarbons.

[0094] In some embodiments, the continuous flow reactor is a static mixer, a microreactor, or a tubular reactor.

[0095] In which case, when the above-mentioned continuous flow reactor is a microreactor, the microreactor may include a first pipe and a second pipe that intersect and communicate with each other, and a third pipe that is connected to the intersection and communication point of the first pipe and the second pipe. The first pipe can be used to transport the gaseous aromatic hydrocarbons, and the second pipe can be used to transport the mixed acid. The gaseous aromatic hydrocarbons and the mixed acid are mixed at the intersection and communication point of the first pipe and the second pipe, and converge into the third pipe. The mixed gaseous aromatic hydrocarbons and mixed acid flow at the same speed during the flow in the third pipe, so that the mixed gaseous aromatic hydrocarbons and mixed acid can be in contact for a preset time and react.

[0096] There is no specific limitation on the type of reactor used for the steps of bubbling the gaseous aromatic hydrocarbon into the mixed acid, mixing the gaseous aromatic hydrocarbon and the mixed acid under stirring, and maintaining the mixed gaseous aromatic hydrocarbon and the mixed acid at a first preset temperature for a preset time after the bubbling is completed to produce mononitroaromatic hydrocarbons.

[0097] In some embodiments, the gaseous aromatic hydrocarbon is bubbled into the mixed acid, and the gaseous aromatic hydrocarbon and the mixed acid are mixed under stirring. After the bubbling is completed, the mixed gaseous aromatic hydrocarbon and the mixed acid are maintained at a first preset temperature for a preset time to react to produce mononitroaromatic hydrocarbons. In this case, the mixing and reaction process of the gaseous aromatic hydrocarbon and the mixed acid is carried out in a tank reactor.

[0098] The stirring speed can be reasonably set according to needs and is not specifically limited here.

[0099] It should also be noted that, during the above-mentioned bubbling process, as the gaseous aromatic hydrocarbons are bubbled into the mixed acid at a certain rate, the gaseous aromatic hydrocarbons and the mixed acid come into contact and react, and the gaseous aromatic hydrocarbons and nitric acid are consumed. Under stirring, the gaseous aromatic hydrocarbons and nitric acid can be fully mixed and contacted, reducing local high temperature and reducing the generation of by-products; at the same time, after the bubbling is completed, by continuing to keep the mixed gaseous aromatic hydrocarbons and the mixed acid at the first preset temperature for a preset time, the gaseous aromatic hydrocarbons and the mixed acid can be fully contacted and reacted. At this time, those skilled in the art will understand that when the mixing and reaction are carried out in a tank reactor, the tank reactor can be closed during the bubbling process, and the tank reactor is opened only after the mixed gaseous aromatic hydrocarbons and the mixed acid are kept at the first preset temperature for a preset time, so that the gaseous aromatic hydrocarbons and the mixed acid can be fully contacted, reducing the loss of gaseous aromatic hydrocarbons in the air, and thus keeping the nitric acid and gaseous aromatic hydrocarbons in the mixed acid mixed and reacting in the above-mentioned preset ratio.

[0100] In some embodiments, the above method may further include:

[0101] The product after the gas-liquid heterogeneous reaction is subjected to phase separation treatment to prepare mononitroaromatic hydrocarbons.

[0102] In some embodiments, the product of the gas-liquid heterogeneous reaction is subjected to phase separation to prepare mononitroaromatic hydrocarbons, comprising:

[0103] After the gaseous aromatic hydrocarbon and the mixed acid are in contact at a first preset temperature for a preset time, performing a gas-liquid phase separation treatment on the product after the gas-liquid heterogeneous reaction occurs; and

[0104] The mixed solution obtained by gas-liquid phase separation treatment is subjected to liquid-liquid phase separation treatment, and the organic phase is collected.

[0105] In these embodiments, gas-liquid phase separation is first performed to separate the incompletely reacted gaseous aromatic hydrocarbons from the reaction products, and liquid-liquid phase separation is performed to remove the incompletely reacted mixed acid, thereby obtaining mononitroaromatic hydrocarbons in the organic phase.

[0106] In some examples, after the gaseous aromatic hydrocarbons and the mixed acid are in contact at a first preset temperature for a preset time, a gas-liquid phase separation treatment can be directly performed at a higher temperature to separate the unreacted gaseous aromatic hydrocarbons from the reaction products; then, the organic phase can be washed with alkali and water until the organic phase is neutral to obtain an organic phase with the mixed acid removed.

[0107] In order to objectively evaluate the technical effects of the embodiments of the present application, the present application will be described in detail and exemplarily through the following embodiments.

[0108] In the following examples, all raw materials can be purchased commercially, and in order to maintain the reliability of the experiments, the raw materials used in the following examples have the same physical and chemical parameters or are prepared by the same processing method.

[0109] Example 1

[0110] Example 1 The method for preparing mononitroaromatics using nitric and sulfuric acid mixed acid is as follows:

[0111] (1) adding 200 g of 98% concentrated sulfuric acid to 80 g of water to obtain 280 g of a sulfuric acid solution having a mass percent concentration (i.e., mass fraction) of 70%;

[0112] (2) adding 1.48 g of 98% concentrated nitric acid to a 70% sulfuric acid solution to obtain a nitric acid mixture A;

[0113] (3) heating the nitric-sulfuric acid mixture A and toluene to 150°C respectively, so that the toluene is completely vaporized into toluene vapor B;

[0114] (4) Nitric-sulfuric acid mixture A and toluene vapor B are respectively transported to the microreactor at a flow rate of 1 m / s. After the gas and liquid come into contact, a gas-liquid nitration reaction occurs. The molar ratio of toluene to nitric acid is 1.5. The residence time of the materials in the microreactor is 5 s. After gas-liquid phase separation, a mixture solution of the product mononitrotoluene and sulfuric acid solution is obtained;

[0115] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed, and the organic phase was washed with alkali and water until the organic phase was neutral to obtain a mononitrotoluene product.

[0116] Test results:

[0117] The mononitrotoluene prepared in Example 1 was analyzed by ultra-high performance liquid chromatography (UPLC), resulting in a mononitrotoluene selectivity of 99.95%, a dinitrotoluene byproduct selectivity of less than 0.05%, and a nitric acid conversion rate greater than 99.9%. The UPLC testing conditions were as follows: a mobile phase of water and methanol in a volume ratio of 0.65:0.35, a flow rate of 0.2 mL / min, an injection volume of 1 μL, a chromatographic column filler of 1.8 μm fluorophenyl (PFP), a chromatographic column inner diameter of 3 mm, and a length of 50 mm.

[0118] Example 2

[0119] Example 2 The method for preparing mononitroaromatics using nitric and sulfuric acid mixed acid is as follows:

[0120] (1) adding 200 g of 98% concentrated sulfuric acid to 45 g of water to obtain 245 g of a sulfuric acid solution having a concentration (i.e., mass fraction) of 80%;

[0121] (2) adding 1.48 g of 98% concentrated nitric acid to 80% sulfuric acid solution to obtain nitric acid mixed acid A;

[0122] (3) heating the nitric-sulfuric acid mixture A and benzene to 100°C respectively, so that the benzene is completely vaporized into benzene vapor B;

[0123] (4) Nitric-sulfuric acid mixture A and benzene vapor B are respectively transported to a static mixer at a flow rate of 1.5 m / s. After the gas and liquid come into contact, a gas-liquid nitration reaction occurs. The molar ratio of benzene to nitric acid is 1.5. The residence time of the materials in the static reactor is 5 s. After gas-liquid phase separation, a mixture solution of the product mononitrobenzene and sulfuric acid solution is obtained;

[0124] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed. The organic phase was washed with alkali and water until the organic phase was neutral to obtain mononitrobenzene product.

[0125] Test results:

[0126] Liquid chromatography analysis of the mononitrobenzene prepared in Example 2 revealed a mononitrobenzene selectivity of 99.98%, a dinitrobenzene selectivity of less than 0.02%, and a nitric acid conversion rate of greater than 99.9%. The liquid chromatography test conditions were the same as those in Example 1.

[0127] Example 3

[0128] Example 3 The method for preparing mononitroaromatics using nitric and sulfuric acid mixture is as follows:

[0129] (1) adding 200 g of 98% concentrated sulfuric acid to 17.78 g of water to obtain 217.78 g of a sulfuric acid solution having a mass percent concentration (i.e., mass fraction) of 90%;

[0130] (2) adding 1.48 g of 98% concentrated nitric acid to a 90% sulfuric acid solution to obtain a nitric acid mixture A;

[0131] (3) heating the nitric-sulfuric acid mixture A and chlorobenzene to 160°C respectively, so that the chlorobenzene is completely vaporized into chlorobenzene vapor B;

[0132] (4) Chlorobenzene vapor B is bubbled into a reactor containing nitric and sulfuric acid at a flow rate of 1.5 m / s. A gas-liquid nitration reaction occurs upon contact between the gas and liquid. The molar ratio of chlorobenzene to nitric acid is 2. The reaction ends approximately 1 second after the bubbling of the chlorobenzene gas is complete. The remaining liquid phase in the reactor is a mixture of the product mononitrochlorobenzene and sulfuric acid solution.

[0133] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed, and the organic phase was washed with alkali and water until the organic phase was neutral to obtain mononitrochlorobenzene product.

[0134] Test results:

[0135] The mononitrochlorobenzene prepared in Example 3 was tested by liquid chromatography, and the results showed that the selectivity of mononitrochlorobenzene was 99.96%, the selectivity of dinitrochlorobenzene was less than 0.04%, and the conversion rate of nitric acid was greater than 99.9%. The liquid chromatography test conditions were the same as those in Example 1.

[0136] Example 4

[0137] Example 4 The method for preparing mononitroaromatics using nitric and sulfuric acid mixed acid is as follows:

[0138] (1) adding 200 g of 98% concentrated sulfuric acid to 45 g of water to obtain 245 g of a sulfuric acid solution having a mass percent concentration (i.e., mass fraction) of 80%;

[0139] (2) adding 1.48 g of 98% concentrated nitric acid to 80% sulfuric acid solution to obtain nitric acid mixed acid A;

[0140] (3) heating the nitric-sulfuric acid mixture A and benzene to 120°C respectively, so that the benzene is completely vaporized into benzene vapor B;

[0141] (4) Nitric-sulfuric acid mixture A and benzene vapor B are respectively transported to a tubular reactor at a flow rate of 2 m / s. After the gas and liquid come into contact, a gas-liquid nitration reaction occurs. The molar ratio of benzene to nitric acid is 1.5. The residence time of the materials in the tubular reactor is 10 s. After gas-liquid phase separation, a mixture solution of mononitrobenzene and sulfuric acid solution is obtained;

[0142] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed. The organic phase was washed with alkali and water until the organic phase was neutral to obtain mononitrobenzene product.

[0143] Test results:

[0144] Liquid chromatography analysis of the mononitrobenzene prepared in Example 4 revealed a mononitrobenzene selectivity of 99.98%, a dinitrobenzene selectivity of less than 0.02%, and a nitric acid conversion rate of greater than 99.9%. The liquid chromatography test conditions were the same as those in Example 1.

[0145] Example 5

[0146] Example 5 The method for preparing mononitroaromatics using nitric and sulfuric acid mixture is as follows:

[0147] (1) adding 200 g of 98% concentrated sulfuric acid to 45 g of water to obtain 245 g of a sulfuric acid solution having a mass percent concentration (i.e., mass fraction) of 80%;

[0148] (2) adding 1.48 g of 98% concentrated nitric acid to 80% sulfuric acid solution to obtain nitric acid mixed acid A;

[0149] (3) heating the nitric-sulfuric acid mixture A and benzene to 120°C respectively, so that the benzene is completely vaporized into benzene vapor B;

[0150] (4) Nitric-sulfuric acid mixture A and benzene vapor B are respectively transported to the microreactor at a flow rate of 2 m / s. After the gas and liquid come into contact, a gas-liquid nitration reaction occurs. The molar ratio of benzene to nitric acid is 1.5. The residence time of the materials in the microreactor is 20 s. After gas-liquid phase separation, a mixture solution of the product mononitrobenzene and sulfuric acid solution is obtained;

[0151] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed. The organic phase was washed with alkali and water until the organic phase was neutral to obtain mononitrobenzene product.

[0152] Test results:

[0153] Liquid chromatography analysis of the mononitrobenzene prepared in Example 5 revealed a mononitrobenzene selectivity of 99.98%, a dinitrobenzene selectivity of less than 0.02%, and a nitric acid conversion rate of greater than 99.9%. The liquid chromatography test conditions were the same as those in Example 1.

[0154] Example 6

[0155] Example 6 The method for preparing mononitroaromatics using nitric and sulfuric acid is as follows:

[0156] (1) adding 200 g of 98% concentrated sulfuric acid to 45 g of water to obtain 245 g of a sulfuric acid solution having a mass percent concentration (i.e., mass fraction) of 80%;

[0157] (2) adding 1.48 g of 98% concentrated nitric acid to 80% sulfuric acid solution to obtain nitric acid mixture A;

[0158] (3) heating the nitric-sulfuric acid mixture A and benzene to 120°C respectively, so that the benzene is completely vaporized into benzene vapor B;

[0159] (4) Nitric-sulfuric acid mixture A and benzene vapor B are respectively transported to the microreactor at a flow rate of 2 m / s. After the gas and liquid come into contact, a gas-liquid nitration reaction occurs. The molar ratio of benzene to nitric acid is 1.5. The residence time of the materials in the microreactor is 0.1 s. After gas-liquid phase separation, a mixture solution of the product mononitrobenzene and sulfuric acid solution is obtained;

[0160] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed, and the organic phase was washed with alkali and water until the organic phase was neutral to obtain mononitrobenzene product.

[0161] Test results:

[0162] Liquid chromatography analysis of the mononitrobenzene prepared in Example 6 revealed a mononitrobenzene selectivity of 99.98%, a dinitrobenzene selectivity of less than 0.02%, and a nitric acid conversion rate of greater than 95%. The liquid chromatography test conditions were the same as those in Example 1.

[0163] Example 7

[0164] Example 7 The method for preparing mononitroaromatics using nitric and sulfuric acid mixture is as follows:

[0165] (1) adding 200 g of 98% concentrated sulfuric acid to 45 g of water to obtain 245 g of a sulfuric acid solution having a mass percent concentration (i.e., mass fraction) of 80%;

[0166] (2) adding 1.48 g of 98% concentrated nitric acid to 80% sulfuric acid solution to obtain nitric acid mixture A;

[0167] (3) heating the nitric-sulfuric acid mixture A and benzene to 130°C respectively, so that the benzene is completely vaporized into benzene vapor B;

[0168] (4) Nitric-sulfuric acid mixture A and benzene vapor B are respectively transported to the microreactor at a flow rate of 2 m / s. After the gas and liquid come into contact, a gas-liquid nitration reaction occurs. The molar ratio of benzene to nitric acid is 1.1. The residence time of the materials in the microreactor is 20 s. After gas-liquid phase separation, a mixture solution of the product mononitrobenzene and sulfuric acid solution is obtained;

[0169] (5) The mixture solution was cooled to room temperature for 30 minutes, and phase separation was performed, and the organic phase was washed with alkali and water until the organic phase was neutral to obtain mononitrobenzene product.

[0170] Test results:

[0171] Liquid chromatography analysis of the mononitrobenzene prepared in Example 7 revealed a mononitrobenzene selectivity of 99.95%, a dinitrobenzene selectivity of less than 0.05%, and a nitric acid conversion rate of greater than 95%. The liquid chromatography test conditions were the same as those in Example 1.

[0172] In summary, the nitration method provided herein can improve the selectivity of mononitroaromatics, significantly exceeding the product selectivity of liquid-liquid heterogeneous nitration reactions, reduce the formation of polynitroaromatics, and almost completely consume nitric acid, facilitating the direct recycling of sulfuric acid after the reaction. Compared with liquid-liquid heterogeneous reactions in related technologies, this method can improve mass transfer, shorten reaction time, and increase reaction efficiency. Furthermore, high-purity mononitroaromatics can be obtained after separation, meeting China's national quality standards without the need for purification.

[0173] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0174] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing mononitroaromatic hydrocarbons using nitric and sulfuric acid mixed acid, characterized in that: include: Preparation of mixed acid of nitric acid and sulfuric acid; Gasifying aromatic hydrocarbons to prepare gaseous aromatic hydrocarbons; mixing the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio, and causing the mixed gaseous aromatic hydrocarbon and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature to prepare the mononitroaromatic hydrocarbon; Wherein, the preset ratio satisfies: the molar ratio of nitric acid in the mixed acid to the gaseous aromatic hydrocarbon is 1:(1-2).

2. The method according to claim 1, characterized in that The first preset temperature is greater than or equal to the boiling point of the aromatic hydrocarbon, and less than or equal to the sum of the boiling point of the aromatic hydrocarbon and 100°C.

3. The method according to claim 1 or 2, characterized in that The process of gasifying aromatic hydrocarbons to prepare gaseous aromatic hydrocarbons comprises: The aromatic hydrocarbons are heated to a second preset temperature to vaporize the aromatic hydrocarbons into gaseous aromatic hydrocarbons; wherein the second preset temperature is greater than or equal to the boiling point of the aromatic hydrocarbons and less than or equal to the sum of the boiling point of the aromatic hydrocarbons and 100°C. Optionally, the second preset temperature is also greater than or equal to the first preset temperature.

4. The method according to any one of claims 1 to 3, characterized in that The step of mixing the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio and causing the mixed gaseous aromatic hydrocarbon and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature comprises: heating the mixed acid to the second preset temperature; mixing the gaseous aromatic hydrocarbon and the mixed acid at a first flow rate and a second flow rate, respectively, and allowing the mixed gaseous aromatic hydrocarbon and the mixed acid to contact at the first preset temperature for a preset time to react and generate the mononitroaromatic hydrocarbon; Wherein, the first flow rate and the second flow rate satisfy: a molar ratio of the gaseous aromatic hydrocarbon and the mixed acid in a unit time satisfies the preset ratio.

5. The method according to claim 4, characterized in that The preset time is 0.1s to 20s.

6. The method according to claim 4 or 5, characterized in that The mixing and reaction process of the gaseous aromatic hydrocarbon and the mixed acid is carried out in a continuous flow reactor.

7. The method according to claim 6, characterized in that The continuous flow reactor is a static mixer, a microreactor or a tubular reactor.

8. The method according to any one of claims 1 to 3, characterized in that The step of mixing the gaseous aromatic hydrocarbon and the mixed acid in a preset ratio and causing the mixed gaseous aromatic hydrocarbon and the mixed acid to undergo a gas-liquid heterogeneous reaction at a first preset temperature comprises: heating the mixed acid to the second preset temperature; The gaseous aromatic hydrocarbon is introduced into the mixed acid in a bubbling manner, and the gaseous aromatic hydrocarbon and the mixed acid are mixed under stirring, and After the bubbling is completed, the mixed gaseous aromatic hydrocarbon and the mixed acid are maintained at the first preset temperature for a preset time to react and generate the mononitroaromatic hydrocarbon.

9. The method according to claim 8, characterized in that The mixing and reaction process of the gaseous aromatic hydrocarbon and the mixed acid is carried out in a tank reactor.

10. The method according to any one of claims 1 to 9, characterized in that: The method further comprises: The product after the gas-liquid heterogeneous reaction is subjected to phase separation treatment to prepare the mononitroaromatic hydrocarbon.

11. The method according to claim 10, characterized in that The process of subjecting the product after the gas-liquid heterogeneous reaction to phase separation to prepare the mononitroaromatic hydrocarbon comprises: After the gaseous aromatic hydrocarbon and the mixed acid are in contact at a first preset temperature for a preset time, performing a gas-liquid phase separation treatment on the product after the gas-liquid heterogeneous reaction occurs; and The mixed solution obtained by gas-liquid phase separation treatment is subjected to liquid-liquid phase separation treatment, and the organic phase is collected.

12. The method according to any one of claims 1 to 11, characterized in that The method for preparing a mixed acid of nitric acid and sulfuric acid comprises: Diluting concentrated sulfuric acid to prepare a sulfuric acid solution with a mass percentage concentration of 50% to 90%; The mixed acid is prepared by mixing fuming nitric acid and the sulfuric acid solution.

13. The method according to claim 12, characterized in that The mass ratio of the fuming nitric acid to the sulfuric acid solution is 1:(100-1000).

14. The method according to any one of claims 1 to 13, characterized in that The aromatic hydrocarbons include compounds containing a benzene ring in the molecule.

15. The method according to any one of claims 1 to 14, characterized in that: The aromatic hydrocarbon is selected from one or more of benzene, toluene, chlorobenzene, xylene, ethylbenzene, naphthalene and tetralin.

16. The method according to any one of claims 1 to 15, characterized in that The molar ratio of nitric acid to gaseous aromatic hydrocarbons in the mixed acid is 1:1.1 to 1:1.5.

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