CN117903005A - Synthesis method of urea - Google Patents
Synthesis method of urea Download PDFInfo
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- CN117903005A CN117903005A CN202311624117.2A CN202311624117A CN117903005A CN 117903005 A CN117903005 A CN 117903005A CN 202311624117 A CN202311624117 A CN 202311624117A CN 117903005 A CN117903005 A CN 117903005A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C273/00—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups
- C07C273/02—Preparation of urea or its derivatives, i.e. compounds containing any of the groups, the nitrogen atoms not being part of nitro or nitroso groups of urea, its salts, complexes or addition compounds
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/141—Feedstock
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Abstract
本发明公开了一种尿素的合成方法，将含有水分子、氮气和二氧化碳的混合气体通入放电反应腔体中，使水分子产生水自由基阳离子团簇，与氮气和二氧化碳反应，获得尿素自由基阳离子，然后使用接地或接负极的装置捕捉尿素自由基阳离子，制得尿素。本发明能够解决现有技术在利用二氧化碳制备尿素时，反应条件苛刻，需要高温高压的问题，且该方法绿色温和，无需催化剂，满足碳中和要求等。The present invention discloses a method for synthesizing urea, wherein a mixed gas containing water molecules, nitrogen and carbon dioxide is introduced into a discharge reaction chamber, so that the water molecules generate water radical cation clusters, which react with nitrogen and carbon dioxide to obtain urea radical cations, and then a device connected to a ground or a cathode is used to capture the urea radical cations to obtain urea. The present invention can solve the problem that when the prior art uses carbon dioxide to prepare urea, the reaction conditions are harsh and high temperature and high pressure are required, and the method is green and mild, does not require a catalyst, and meets the requirements of carbon neutrality.
Description
Technical Field
The invention relates to the technical field of nitrogen fixation, in particular to a synthesis method of urea.
Background
Nitrogen widely exists in the atmosphere, and is a nitrogen source with abundant reserves, low cost and easy availability. However, nitrogen cannot be directly absorbed and utilized by human beings or animals and plants, and only the conversion of free nitrogen in air into nitrogen-containing compounds by chemical or biological methods is applied to industrial production, so that the research of fixing and converting nitrogen has important significance to the development of human society. The nitrogen fixation mode mainly comprises biological nitrogen fixation, artificial chemical nitrogen fixation and high-energy nitrogen fixation. Among the existing nitrogen fixation methods, only artificial chemical nitrogen fixation can be applied to industrial production on a large scale, and its main product is an ammonia-containing compound, such as urea.
Carbon dioxide (CO 2) is an inexpensive and renewable C1 resource on the one hand and a culprit for global warming on the other hand. In this context, CO 2 reuse is becoming a global focus of attention. The human can completely synthesize the CO 2 captured from the environment into high-added-value chemicals such as important chemical products of urea, carbonate, methanol, oxalic acid and the like which are mainly derived from petroleum at present through chemical conversion. However, CO 2 is an extremely chemically stable molecule and takes up a lot of energy as a raw material for chemical synthesis. Therefore, achieving efficient and economical chemical conversion is currently a very challenging research topic.
The synthesis of urea is known as a great achievement in the human industry. In 1828, the german scientist ville realized the synthesis of urea from inorganic to organic for the first time in the laboratory. The result breaks through the history that organic substances cannot be artificially synthesized, and initiates an idea bridge connecting life and non-life worlds. At present, the main process for producing urea in the world industry is a direct synthesis process (2NH3+CO2＝NH4COONH2;NH3COONH2＝NH2CONH2+H2O). of ammonia and CO 2, the process condition needs high temperature and high pressure, and how to realize efficient conversion of CO 2 into urea under mild conditions becomes a research hot spot for scientific researchers.
Disclosure of Invention
The invention aims to at least solve one of the technical problems in the prior art, and provides a novel reaction for rapidly preparing synthetic urea based on the action of water radical cations, CO 2 and nitrogen, which meets the requirements of new energy, has the characteristics of atom economy, green pollution-free property and the like, and is a model of green synthetic chemistry.
The technical scheme of the invention is as follows:
A process for synthesizing urea includes such steps as introducing the mixed gas containing water molecules, nitrogen and carbon dioxide to discharge reaction cavity, ionizing water molecules to generate water radical cation clusters, reacting with nitrogen and carbon dioxide to obtain urea radical cations, and capturing urea radical cations by means of grounded or negative electrode.
The reaction principle is as follows:
further, the flow rate of the nitrogen is 0.1-0.4L/min.
Further, the flow rate of the carbon dioxide is 0.1-0.4L/min.
Further, the discharge voltage in the discharge reaction cavity is 4-6 kV.
Further, a discharge array needle plate and a stainless steel groove are arranged in the discharge reaction cavity at opposite positions, the discharge array needle plate is connected with the positive electrode of the high-voltage power supply, the stainless steel groove is connected with the negative electrode of the high-voltage power supply, a reaction space is arranged between the discharge array needle plate and the stainless steel groove, and the mixed gas is introduced into the reaction space.
Further, the discharge array needle plate is made by welding tungsten needles on a PCB hole plate, the distance between the needles on the discharge array needle plate is optimized between 3 mm and 8mm, and the curvature radius of the needle tip is optimized between 0.01 mm and 0.1 mm.
Further, a urea detection developer or water or other absorbent solution for enriching urea is also placed in the discharge reaction cavity.
Further, the urea detection color reagent is p-dimethylaminobenzaldehyde or diacetyl oxime.
The beneficial effects of the invention are as follows: the invention utilizes the discharge reaction cavity to enable the mixed gas containing water molecules to generate water radical cation clusters, and the formed water radical cation clusters react with nitrogen and carbon dioxide gas to generate urea radical cations; urea radical cations reach the stainless steel tank quickly to produce urea. The method can solve the problems that the reaction condition is harsh and high temperature and high pressure are needed when the CO 2 is utilized to prepare urea in the prior art, and has the characteristics of being green and mild, requiring no catalyst and the like.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic view of a urea production plant according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a discharge array needle plate;
FIG. 3 is a schematic view of a stainless steel tank;
FIG. 4 is a graph of ultraviolet light spectrum of water radical cation after urea is prepared by reaction with nitrogen and CO 2, and after urea is developed with p-dimethylaminobenzaldehyde;
FIG. 5 is a graph of ultraviolet spectra of urea standards at different concentrations after interaction with p-dimethylaminobenzaldehyde;
fig. 6 is a standard graph of urea.
The device comprises a first pipeline, a second pipeline, a 3-discharge reaction cavity, a 4-reactant input channel, a 5-discharge array needle plate, a 6-stainless steel groove, a 7-water storage container, an 8-PCB hole plate, a 9-tungsten needle and a 10-rectangular groove.
Detailed Description
Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present invention, but not to limit the scope of the present invention.
In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, a number means one or more, a number means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.
Referring to fig. 1-3, a urea production apparatus for use in a urea synthesis process according to an embodiment of the present invention specifically includes a discharge reaction chamber 3, on which a reactant inlet channel 4 is provided for introducing water.
The discharge reaction cavity 3 is of a frame structure, an opened cover body is arranged above the discharge reaction cavity, a sealed cavity is formed between the closed cover body and the frame structure, the cover body is uncovered after the reaction is finished, and an auxiliary agent can be added into a stainless steel groove to confirm whether urea is generated or not, or a product is conveniently taken out.
The reactant channel 4 is communicated with a water storage container 7, the water storage container is respectively communicated with a nitrogen gas source and a carbon dioxide gas source through a first pipeline 1 and a second pipeline 2,
After being wetted by the water storage container, the nitrogen and the carbon dioxide enter the discharge reaction cavity 3 through the reactant channel 4. The water storage device 7 is arranged to facilitate the introduction of water vapor into the discharge reaction cavity 3 and maintain a certain humidity. Preferably, the water molecules account for 60 (v/v)% of the mixed gas, but are not limited thereto.
The discharge reaction cavity 3 is internally provided with a discharge array needle plate 5 and a stainless steel groove 6 at opposite positions, the discharge array needle plate 5 is connected with the positive electrode of a high-voltage power supply, the stainless steel groove 6 is connected with the negative electrode of the high-voltage power supply, and a reaction space is arranged between the discharge array needle plate 5 and the stainless steel groove 6. Preferably, the voltage of the high-voltage power supply is 4-6 kV.
Referring to fig. 2, in this embodiment, the discharge array needle plate 5 has a rectangular structure, the discharge array needle plate 5 is made by welding tungsten needles 9 on a PCB hole plate 8, the distance between the needles on the discharge array needle plate 5 is 3-8 mm, and the radius of curvature of the needle tip is 0.01-0.1 mm. Preferably, the discharge array needle plate 5 is coated with insulating paint except for the needle tip and the high voltage connection part.
Referring to fig. 3, the stainless steel tank 6 has a rectangular groove 10 with a small resistance and a high conductive capacity. The urea formed after the reaction is collected on the rectangular recess 10.
Based on the device, the urea preparation method comprises the following steps:
Nitrogen and carbon dioxide respectively enter water stored in the water storage device 7 through the first pipeline 1 and the second pipeline 2, so that the wetted mixed gas enters the discharge reaction cavity 3;
the high-voltage power supply is started, high voltage is applied to the discharge array needle plate 5, so that a water radical cation cluster is generated at the needle point of the discharge array needle plate 5, and the formed water radical cation cluster acts with nitrogen and carbon dioxide to generate urea radical cations, and the urea radical cations are transferred to the stainless steel groove 6 to form urea;
Urea formed on the stainless steel tank 6 is taken out and collected by opening the lid. In addition, the lid may be opened and an auxiliary agent may be added to the stainless steel tank 6, and if color development is performed, the generation of urea may be confirmed.
Specifically, by applying high voltage (4-6 kV) to the discharge array needle plate 5, corona discharge is generated at the tip of the discharge needle tip, nitrogen with certain humidity is taken as a nitrogen source, carbon dioxide with certain humidity is taken as a carbon source under normal temperature and normal pressure (for example, 25 ℃ and one atmosphere pressure), water radical ion clusters are generated through the high voltage corona discharge, the water radical cation clusters are fully contacted with the nitrogen and the carbon dioxide and react to generate urea radical cations, and the formed urea radical cations are simultaneously transferred to the stainless steel groove 6, so that the generated urea is enriched on the stainless steel groove 6.
The following are several examples of verification of the preparation of the urea preparation process described above:
example 1
Introducing nitrogen (with the control flow of 0.1L/min) and carbon dioxide (with the control flow of 0.1L/min) into water at normal temperature and normal pressure, allowing the wet mixed gas to flow into a discharge reaction cavity through a pipeline, and applying high voltage (4 kV) to a discharge array needle plate 5 to enable generated urea radical cations to be quickly adsorbed into a stainless steel groove to prepare urea.
Example 2
Introducing nitrogen (with the control flow of 0.2L/min) and carbon dioxide (with the control flow of 0.2L/min) into water at normal temperature and normal pressure, allowing the wet mixed gas to flow into a discharge reaction cavity through a pipeline, and applying high voltage (5 kV) to a discharge array needle plate 5 to enable generated urea radical cations to be quickly adsorbed into a stainless steel groove to prepare urea.
Example 3
Introducing nitrogen (with a control flow of 0.3L/min) and carbon dioxide (with a control flow of 0.3L/min) into water at normal temperature and normal pressure, allowing the wet mixed gas to flow into a discharge reaction cavity through a pipeline, and applying high voltage (6 kV) to a discharge array needle plate 5 to enable generated urea radical cations to be quickly adsorbed into a stainless steel groove to prepare urea.
Test one: the product of example 1 was taken and added to a p-dimethylaminobenzaldehyde solution, the color of the solution turned light yellow, the mixed solution was subjected to ultraviolet detection, and a characteristic absorption peak was observed at 420nm, which was the reaction product of urea and a p-dimethylaminobenzaldehyde developer, the absorption wavelength of the product peak was consistent with that reported in the literature (p-dimethylaminobenzaldehyde chromogenic spectrophotometry detection of very small amounts of urea 2011 in aqueous solution, university of northeast agricultural report, 42, 87-91), and the obtained results were shown in fig. 4. This indicates that urea is produced after mixing the nitrogen and carbon dioxide with water radical cations.
And II, testing: a series of urea standard solutions (0, 10, 25, 50, 100 and 1000 ppm) with different concentrations are prepared at normal temperature and normal pressure, the urea standard solutions are fully mixed and shaken with a p-dimethylaminobenzaldehyde solution developer solution respectively, ultraviolet spectrum analysis is carried out on the shaken solution, and characteristic absorption peaks (figure 5) can be observed at 420nm, are reaction products of urea and the p-dimethylaminobenzaldehyde solution, are consistent with figure 4, and show that the urea is successfully synthesized by adopting the device shown in figure 1.
In summary, according to the urea synthesis method provided by the embodiment, the whole synthesis process can be performed only at normal temperature and normal pressure (refer to pressure), no catalyst is needed, energy is saved, and the method is green and pollution-free.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing examples illustrate only a few embodiments of the invention and are described in detail herein without thereby limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (8)
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| CN202311624117.2A CN117903005B (en) | 2023-11-30 | 2023-11-30 | A method for synthesizing urea |
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| CN116356357A (en) * | 2023-03-01 | 2023-06-30 | 浙江大学 | Catalyst preparation method for electrochemical coupling co-reduction of CO2 and NO3-production of urea |
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Patent Citations (10)
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| US20070245787A1 (en) * | 2006-04-21 | 2007-10-25 | Hce, Llc | Fertilizer production from fossil fuel with minimal carbon dioxide emission |
| CN103739521A (en) * | 2013-12-09 | 2014-04-23 | 苏州市牛勿耳关电器科技有限公司 | Device used for producing urea with wind energy |
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| CN116240562A (en) * | 2023-03-07 | 2023-06-09 | 北京大学 | Electrocatalytic synthesis of urea from carbon dioxide and nitrate |
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