Method for selective synthesis of methyl formate by catalytic ozonation of methanol at ultra-low temperature using a graphdiyne catalyst

Abstract

The application discloses a method for selectively synthesizing methyl formate by catalytic ozonation of methanol at ultralow temperature by using a graphdiyne catalyst, and belongs to the technical field of fine chemical engineering. The method comprises the following steps: using graphdiyne as a catalyst, and performing a catalytic reaction in a mixed gas atmosphere containing methanol and ozone to selectively synthesize methyl formate; the temperature of the catalytic reaction is-25-25 DEG C; the concentration of methanol in the mixed gas atmosphere is 3000-10000 ppm; and the concentration of ozone in the mixed gas atmosphere is 750 ppm. The activity test results show that the graphdiyne catalyst has a methyl formate selectivity of 92% and a 16-cycle test stability at ultralow temperature (25 DEG C). In the method, the graphdiyne catalyst does not need to be activated, has high catalytic activity, and contains no metal, so that no environmental pollution is caused.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of fine chemical engineering, in particular to a method for selectively synthesizing methyl formate by catalyzing ozonation of methanol at ultralow temperature by using a graphdiyne catalyst. BACKGROUND

[0002] Methyl formate (MF) is a colorless and fragrant volatile liquid, which is often considered as one of the most basic structural units of C1 chemistry and is also a key synthetic intermediate in the coal chemical industry chain. Long-term exposure to methyl formate atmosphere can cause strong irritation to the respiratory tract, eyes and nose of human body, and can cause chest compression and lead to breathing difficulties. Importantly, methyl formate is an important intermediate, solvent and additive widely used in petroleum chemical industry, pesticide, organic synthesis and medicine fields, such as being directly used as a smoke fumigant and bactericide for treating tobacco, dried fruits, grains and the like; being often used as a solvent for nitrocellulose and cellulose acetate; and being often used as a synthetic raw material for sulfomethyl pyrimidine, cough suppressant dextromethorphan and the like. The market application potential is huge.

[0003] At present, the methods for selectively preparing methyl formate from methanol reported mainly include seven kinds, i.e. direct esterification of methanol (strong acid, 70 DEG C), carbonylation of methanol (high pressure, 110 DEG C), catalytic dehydrogenation of methanol (300 DEG C), formaldehyde dimerization, direct synthesis of synthesis gas, photocatalysis (current scale-up is impossible) and carbon dioxide methanol hydrogenation condensation. SUMMARY

[0004] The application aims to provide a method for selectively synthesizing methyl formate by catalyzing ozonation of methanol at ultralow temperature by using a graphdiyne catalyst, so as to solve the problem that most of the existing methods for catalytically synthesizing methyl formate from methanol have high temperature, leading to high energy consumption in the production process of methyl formate.

[0005] To achieve the above-mentioned purpose, the application provides the following solutions.

[0006] One of the technical solutions of the application is that graphdiyne is used as a catalyst in the selective synthesis of methyl formate by catalyzing ozonation of methanol at ultralow temperature, and the ultralow temperature specifically refers to-25-25 DEG C.

[0007] The second technical solution of the application is a method for selectively synthesizing methyl formate by catalyzing ozonation of methanol at ultralow temperature by using a graphdiyne catalyst, which comprises the following steps.

[0008] The catalytic reaction is carried out in a mixed gas atmosphere containing methanol and ozone, and the catalytic reaction temperature is -25-25℃, preferably 25℃.

[0009] In the reaction system of the present application, ozone molecules first react with the electron-rich active site sp-C in graphdiyne, rapidly generating surface active oxygen species (active singlet oxygen), which oxidizes sp-C into C=O double bond, and graphdiyne is in-situ generated into oxidized graphdiyne (named as GDY-6O) during the reaction. The newly generated C=O functional group acts as a proton acceptor, and methanol acts as a proton donor, generating a weak hydrogen bond interaction at the interface of oxidized graphdiyne (GDY-6O), and further proton tunneling effect makes the hydroxyl proton of methanol rapidly transfer to the C=O functional group of oxidized graphdiyne (GDY-6O), ultimately realizing the dehydrogenation oxidation of methanol (CH2O·) and the C-O coupling to produce methyl formate (CH3OH+CH2O·→CH3OCHO+2H(C-OH)), and at the same time, the C=O functional group is reduced to hydroxyl (C-OH), which is then oxidized by ozone to restore the C=O functional group in the next step, realizing the regeneration of the active site and sustainable catalysis.

[0010] Further, the concentration of methanol in the mixed gas atmosphere is 3000-10000 ppm (specifically, the volume concentration).

[0011] Further, the concentration of ozone in the mixed gas atmosphere is 750 ppm (specifically, the volume concentration).

[0012] Further, the ozone is generated from oxygen under the action of an ozone generator.

[0013] Further, the specific operation of the catalytic reaction using graphdiyne as the catalyst in a mixed gas atmosphere containing methanol and ozone is as follows: the graphdiyne catalyst is placed in a reaction container, methanol gas and nitrogen gas are introduced into the reaction container, oxygen gas is introduced into the ozone generator, and the mixed gas (containing oxygen and ozone) generated by the reaction of the ozone generator is output into the reaction container (by controlling the gas flow of oxygen and the power of the ozone generator to control the concentration of ozone in the mixed gas atmosphere in the reaction container, and nitrogen gas is used as the balance gas in the mixed gas atmosphere), and the catalytic reaction of methanol gas under the action of graphdiyne catalyst and ozone is carried out to synthesize methyl formate.

[0014] Further, the space velocity of the catalytic reaction is 30000-120000 mL g -1 h -1 .

[0015] Further, the graphdiyne is used in the form of pure graphdiyne powder or is prepared into a monolithic catalyst with a carrier.

[0016] Further, the particle size of the graphdiyne powder is 40-60 mesh.

[0017] The present application discloses the following technical effects:

[0018] The present application first proposes the application of graphdiyne as a catalyst in the selective synthesis of methyl formate from the catalytic ozonation of methanol at ultra-low temperature (-25-25 DEG C).

[0019] The present application provides a new method for the selective synthesis of methyl formate from the catalytic ozonation of methanol at ultra-low temperature using a graphdiyne catalyst.

[0020] According to the method of the present application, a 3% conversion rate of methanol and a 92% selectivity of methyl formate can be achieved at ultra-low temperature (25 DEG C), which has obvious energy consumption advantages compared with traditional processes.

[0021] The method of the present application has less reaction pollutants, only a small amount of carbon monoxide and carbon dioxide is generated in addition to methyl formate, and the process product is easy to separate.

[0022] In the method of the present application, the graphdiyne catalyst does not need to be activated, has high catalytic activity and good stability (still remains stable after 16 cycles of testing), and contains no metal, which will not pollute the environment. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below, and obviously, the drawings in the following description can only be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0024] Figure 1 The gas chromatogram of the catalytic reaction product in Example 1 is shown in Figure 1.

[0025] Figure 2 The mass spectrum of the catalytic reaction product in Example 1 is shown in Figure 2.

[0026] Figure 3 The characterization results of the graphdiyne catalyst used in the examples and comparative examples of the present application are shown in Figure 3; wherein a is the XRD pattern of the prepared graphdiyne catalyst (GDY); b is the Raman pattern of GDY; c is the XPS survey pattern of GDY; d is the XPS C1s pattern of GDY; e is the infrared spectrum of GDY; f is the SEM pattern and element Mapping pattern of GDY.

[0027] Figure 4 XPS O 1s spectrum of the graphdiyne catalyst (GDY) before catalytic reaction in Example 1;

[0028] Figure 5 XPS O 1s spectrum of the sample of graphdiyne oxide (GDY-60) after testing the selectivity of the graphdiyne catalyst to catalyze the ozonation of methanol to synthesize methyl formate in Example 1;

[0029] Figure 6 EPR superoxide radical detection spectrum of the graphdiyne (GDY) and graphdiyne oxide (GDY-60);

[0030] Figure 7 Cyclic stability test results of the graphdiyne catalyst to catalyze the ozonation of methanol to synthesize methyl formate. DETAILED DESCRIPTION

[0031] Various example embodiments of the present application will now be described in detail with reference to the accompanying drawings. The detailed description provided in this specification is only for a better understanding of the application, and should not be construed as a limitation to the scope of the present application.

[0032] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. In addition, for any numerical limits recited herein, these numerical limits are approximations. Although the term comprises, comprising, or variations such as comprises or comprising, is used throughout the detailed description and in the claims, these variations are to be taken in an open-ended manner – for example, in a sense of "including, but not limited to," and the like.

[0033] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials which are described herein. In the case of conflict between the present specification and any document incorporated herein by reference, the present specification will control.

[0034] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application in any way.

[0035] As used herein, "comprise", "comprising", "having", "including", "contain", "containing", "include" and the like are open-ended terms that are intended to mean including but not limited to.

[0036] The application provides application of graphdiyne as a catalyst in selective synthesis of methyl formate from catalytic ozonation of methanol at an ultra-low temperature, wherein the ultra-low temperature specifically refers to -25-25 DEG C.

[0037] The application also provides a method for selective synthesis of methyl formate from catalytic ozonation of methanol at an ultra-low temperature by using a graphdiyne catalyst, which comprises the following steps:

[0038] The graphdiyne is used as a catalyst to perform catalytic reaction in a mixed gas atmosphere containing methanol and ozone, so as to selectively synthesize methyl formate; the temperature of the catalytic reaction is -25-25 DEG C, preferably 25 DEG C.

[0039] As a preferred embodiment of the application, the concentration of methanol in the mixed gas atmosphere is 3000-10000 ppm.

[0040] As a preferred embodiment of the application, the concentration of ozone in the mixed gas atmosphere is 750 ppm.

[0041] As a preferred embodiment of the application, the ozone is generated from oxygen under the action of an ozone generator.

[0042] As a preferred embodiment of the application, the specific operation of using the graphdiyne as a catalyst to perform catalytic reaction in a mixed gas atmosphere containing methanol and ozone is as follows: the graphdiyne catalyst is placed in a reaction container, methanol gas and nitrogen gas are introduced into the reaction container, oxygen gas is introduced into the ozone generator, the mixed gas (containing oxygen and ozone) generated by the reaction of the oxygen gas in the ozone generator is output into the reaction container (the concentration of ozone in the mixed gas atmosphere in the reaction container is controlled by controlling the gas flow of the oxygen gas and the power of the ozone generator), the methanol gas is catalytically reacted under the action of the graphdiyne catalyst and the ozone, and methyl formate is synthesized.

[0043] As a preferred embodiment of the application, the concentration of methanol and the concentration of ozone in the mixed gas atmosphere are both the inlet concentrations at the reaction container.

[0044] As a preferred embodiment of the application, the methanol gas specifically refers to a gas containing methanol, i.e. a mixed gas of methanol and other gases (air or nitrogen, as a carrier gas), which can be generated by a VOCs generator. There is no special requirement for the concentration of methanol in the methanol gas, as long as the concentration of methanol in the mixed gas atmosphere in the final reaction container can reach 3000-10000 ppm.

[0045] As a preferred embodiment of the application, the nitrogen gas is pure nitrogen gas with a concentration of >99.5%.

[0046] As a preferred embodiment of the present application, the oxygen is pure oxygen with a concentration of >99.2%.

[0047] As a preferred embodiment of the present application, the space velocity of the catalytic reaction is 30000-120000 mL g -1 h -1 .

[0048] As a preferred embodiment of the present application, the catalytic reaction is carried out in a quartz glass tube fixed bed reactor, and the reaction container is a quartz glass tube.

[0049] As a preferred embodiment of the present application, the temperature of the catalytic reaction refers to the temperature of the reaction bed layer, which is controlled by a constant temperature water bath or a low temperature circulating refrigeration tank, and one of methanol, ethanol and ethylene glycol can be added as a refrigerant.

[0050] As a preferred embodiment of the present application, the concentration of ozone is monitored in real time online by an ozone detector.

[0051] As a preferred embodiment of the present application, the concentration changes of methanol, methyl formate, carbon monoxide and carbon dioxide and other components in the tail gas are monitored by a FID gas chromatograph (FID detector) and a handheld VOCs concentration detector.

[0052] As a preferred embodiment of the present application, the graphdiyne is used in the form of pure graphdiyne powder or prepared into a monolithic catalyst with a carrier (i.e. the graphdiyne powder is compounded with a carrier to prepare a monolithic catalyst for the catalytic reaction).

[0053] As a preferred embodiment of the present application, when the graphdiyne is used in the form of pure graphdiyne powder, the particle size of the graphdiyne powder is 40-60 mesh (controlled by tabletting and sieving by a tablet press); and the amount of the graphdiyne powder is 50-100 mg.

[0054] As a preferred embodiment of the present application, when the graphdiyne is prepared into a monolithic catalyst with a carrier, the graphdiyne catalyst includes but is not limited to a graphdiyne / copper foam monolithic catalyst or a graphdiyne / carbon cloth monolithic catalyst; and the specific preparation method of the monolithic catalyst can refer to the conventional method in the art, which is not a limitation of the present application.

[0055] The technical solutions of the present application are further described below in combination with specific examples.

[0056] The graphdiyne catalyst used in the following examples and comparative examples is a graphdiyne powder prepared in the laboratory, and the preparation method is as follows:

[0057] In 15 mL of tetrahydrofuran (THF), 400 mg (0.61 mmol) of hexa((trimethylsilyl)ethynyl)benzene, 5 mL of 1M tetrabutylammonium fluoride solution (solvent THF, containing 5 mmol of tetrabutylammonium fluoride), was stirred at 0°C for 10 min in the dark, then diluted with ethyl acetate, washed with saturated brine, dried over anhydrous Na2SO4, and the solvent was removed under vacuum to obtain product A. Product A was diluted with 120 mL of pyridine, and the diluted solution was slowly added to a copper foil solution of 100 mL of pyridine at 110°C, and 20 pieces of copper foil were added, each piece of copper foil was 0.1 x 10 x 100 mm. Then the reaction was placed at 110°C under nitrogen atmosphere for 3 days. After the reaction was completed, it was washed with deionized water, ethanol and DMF (N,N-dimethylformamide) at 60°C in turn until the washing liquid was clear and colorless, and then dried at 60°C under vacuum for 24 hours to obtain black graphite yne powder. The powder was pressed by a tablet press and sieved to prepare a 40-60 mesh powder, which was used as a graphite yne catalyst (denoted as GDY) in the specific embodiments of the present application.

[0058] In addition to the above prepared graphite yne catalyst, other ways of obtaining graphite yne can also be selected, such as purchasing commercially available graphite yne, which can achieve the technical effects of the present application, i.e. achieving the same or similar catalytic effect as the above prepared graphite yne catalyst.

[0059] Example 1

[0060] A method for selectively synthesizing methyl formate by catalytic ozonation of methanol at ultra-low temperature using a graphite yne catalyst, the specific operation is as follows:

[0061] In the quartz glass pipeline of a U-shaped quartz glass fixed bed reactor with an inner diameter of 6 mm and an outer diameter of 8 mm, 50 mg of graphite yne catalyst was placed, the temperature of the reaction bed was controlled at 25°C by a constant temperature water bath, methanol gas (gas flow rate was 30 mL / min, methanol concentration was 10000 ppm, and nitrogen was used as the carrier gas) and nitrogen (pure nitrogen, gas flow rate was 40 mL / min) were introduced into the quartz glass pipeline, oxygen (pure oxygen, gas flow rate was 30 mL / min) was introduced into the ozone generator, and the mixed gas (containing oxygen and ozone) generated by the reaction of oxygen in the ozone generator was introduced into the quartz glass pipeline. The concentration of methanol gas in the mixed gas atmosphere in the quartz glass pipeline (inlet concentration) was 3000 ppm, and the concentration of ozone (inlet concentration) was 750 ppm (the concentration of ozone was controlled by adjusting the power of the ozone generator). The reaction mass space velocity of the reaction system was 120000 mL g -1 h -1 .

[0062] The exhaust gas was collected twice using a gas bag and analyzed by gas chromatography-mass spectrometry. Each test was named sample 1 and sample 2, with methyl formate standard sample (commercially available analytical grade methyl formate, brand name: Sinopharm) as the standard reference. Figure 1 The gas chromatograms obtained from the test show that the peak positions of sample 1 and sample 2 are consistent with those of the standard sample. Figure 2 The corresponding mass spectrometry results show that the peak positions of sample 1 and sample 2 are consistent with those of the standard sample. Figure 1 and Figure 2 The results all proved the successful synthesis of methyl formate.

[0063] Meanwhile, the concentration changes of each gas in the exhaust gas were monitored using a Fuli gas chromatograph (FID detector) and a handheld VOCs concentration detector, and the methanol conversion rate and the selectivity of the main product and by-products were calculated (6 tests were conducted within 1 hour, once every 10 minutes, and the average value was taken). The test results are as follows: methanol conversion rate was 3%, methyl formate selectivity was 92%, carbon monoxide selectivity was 2%, and carbon dioxide selectivity was 6%.

[0064] Test Example 1

[0065] Figure 3 The figures show the characterization results of the graphyne catalyst (powder before tableting) used in the embodiments and comparative examples of this invention. Specifically, a is the XRD pattern of the prepared graphyne catalyst (GDY); b is the Raman spectroscopy pattern of GDY; c is the XPS survey pattern of GDY; d is the XPS C1s pattern of GDY; e is the infrared spectrum of GDY; and f is the SEM image and elemental mapping diagram of GDY. Figure 3 XRD pattern of a and Figure 3 The Raman diagrams for b all confirm that the basic structural unit of the graphdiyne catalyst contains a benzene ring and a diyne bond. Figure 3 The infrared spectrum of e also detected characteristic peaks of benzene ring C=C and alkyne bonds on the GDY surface. Furthermore, Figure 3 The XPS survey plot of c indicates that GDY is mainly composed of C and O elements. Figure 3 The element mapping of f also detected that C and O elements are evenly distributed on the GDY surface. Figure 3The XPS C1s peak fitting results of d show that GDY is mainly composed of sp-C and sp2-C, containing a small amount of C-O bond and C=O double bond functional groups (graphdiyne catalyst surface will adsorb oxygen, and XPS will also be oxidized by X-ray during detection, so XPS can detect the presence of a small amount of O elements).

[0066] Figure 4 The XPS O1s graph of the graphdiyne catalyst (GDY) before the catalytic reaction in Example 1, Figure 5 The XPS O1s graph of the graphdiyne oxide (GDY-6O) sample after testing the selective synthesis of methyl formate from the catalytic ozonation of methanol by the graphdiyne catalyst in Example 1, Figure 6 The EPR superoxide radical detection graph of graphdiyne (GDY) and graphdiyne oxide (GDY-6O).

[0067] Figure 4 show that the surface of GDY mainly contains adsorbed oxygen species, Figure 5 The peak fitting results of d show that C=O functional groups and C-OH functional groups are generated in situ on the surface of the catalyst material after ozonation, and the C=O functional groups will become new active sites to participate in the dehydrogenation and oxidation of methanol and the C-O coupling to generate methyl formate. Figure 6 show that the oxygen-containing functional groups generated on the surface of the graphdiyne catalyst by ozonation enable the obtained graphdiyne oxide to produce a stronger superoxide radical signal.

[0068] Example 2

[0069] The same as Example 1, except that the temperature of the reaction bed is controlled to be 10°C by a constant temperature water bath. The test results of this example are as follows: the conversion rate of methanol is 2.7%, the selectivity of methyl formate is 92%, the selectivity of carbon monoxide is 3%, and the selectivity of carbon dioxide is 5%.

[0070] Example 3

[0071] The same as Example 1, except that the temperature of the reaction bed is controlled to be 0°C by a constant temperature water bath. The test results of this example are as follows: the conversion rate of methanol is 2.2%, the selectivity of methyl formate is 94%, the selectivity of carbon monoxide is 3%, and the selectivity of carbon dioxide is 3%.

[0072] Example 4

[0073] The same as Example 1, except that the temperature of the reaction bed is controlled to be -10°C by a constant temperature water bath. The test results of this example are as follows: the conversion rate of methanol is 1.5%, the selectivity of methyl formate is 95%, the selectivity of carbon monoxide is 4%, and the selectivity of carbon dioxide is 1%.

[0074] Example 5

[0075] The same as Example 1, except that the temperature of the reaction bed is controlled to be -20°C by a constant temperature water bath. The test results of this example are as follows: methanol conversion is 0.4%, methyl formate selectivity is 96%, carbon monoxide selectivity is 3.4%, and carbon dioxide selectivity is 0.6%.

[0076] Comparative Example 1

[0077] The same as Example 1, except that the catalytic reaction is carried out using an equal mass of activated carbon (particle size of 40-60 mesh) instead of the graphdiyne catalyst. The test results of this comparative example are as follows: methanol conversion is 0.3%, methyl formate selectivity is 0%, carbon monoxide selectivity is 41%, and carbon dioxide selectivity is 59%.

[0078] Comparative Example 2

[0079] The same as Example 1, except that the catalytic reaction is carried out using an equal mass of graphene (particle size of 40-60 mesh) instead of the graphdiyne catalyst. The test results of this comparative example are as follows: methanol conversion is 4%, methyl formate selectivity is 0%, carbon monoxide selectivity is 37%, and carbon dioxide selectivity is 63%.

[0080] Comparative Example 3

[0081] A graphdiyne catalyst 50 mg is placed in the quartz glass pipeline of a U-shaped quartz glass tube fixed bed reactor with an inner diameter of 6 mm and an outer diameter of 8 mm, the temperature of the reaction bed is controlled to be 25°C by a constant temperature water bath, methanol gas (gas flow rate is 30 mL / min, methanol concentration is 10000 ppm, carrier gas is nitrogen), nitrogen (pure nitrogen, gas flow rate is 40 mL / min), and oxygen (pure oxygen, gas flow rate is 30 mL / min) are introduced into the quartz glass pipeline, the concentration of methanol gas in the mixed gas atmosphere in the quartz glass pipeline is 3000 ppm, and the reaction mass space velocity of the reaction system is 120000 mL g -1 h -1 The concentration changes of each gas in the tail gas are monitored by a Fuli gas chromatograph (FID detector) and a handheld VOCs concentration detector, and the conversion of methanol and the selectivity of the main product and byproduct are calculated (tested 6 times in 1 hour, once every 10 min, and the average value is taken). The test results are as follows: methanol conversion is 0%, methyl formate selectivity is 0%, carbon monoxide selectivity is 0%, and carbon dioxide selectivity is 0%.

[0082] Example 6

[0083] Cyclic stability test

[0084] 50 mg of graphylene catalyst was placed inside the quartz glass tube of a U-shaped quartz glass tube fixed-bed reactor with an inner diameter of 6 mm and an outer diameter of 8 mm. The reaction bed temperature was controlled at 25 °C using a constant-temperature water bath. Methanol gas (flow rate 30 mL / min, methanol concentration 10000 ppm, nitrogen as carrier gas) and nitrogen gas (pure nitrogen, flow rate 40 mL / min) were introduced into the quartz glass tube. Simultaneously, oxygen gas (pure oxygen, flow rate 30 mL / min) was introduced into an ozone generator. After the oxygen was reacted in the ozone generator to generate ozone, the resulting mixed gas (containing oxygen and ozone) entered the quartz glass tube. The concentration of methanol gas in the mixed atmosphere inside the quartz glass tube was 3000 ppm, and the concentration of ozone was 750 ppm (the ozone concentration was controlled by adjusting the power of the ozone generator). The mass hourly space velocity (HSV) of the reaction system was 120000 mL g. -1 h -1 After the catalytic reaction has been running for 12 hours, the reaction gas path is switched to a bypass and held for 30 minutes, then switched back to the main path for another 12 hours of catalytic reaction. This process is repeated for a total of 16 cycles.

[0085] Cyclic stability test results are as follows Figure 7 As shown, by Figure 7 It can be seen that the graphylene catalyst remained stable after 16 cycles of testing, maintaining excellent catalytic activity even during the 16th cycle. During the cycle stability test, the methanol conversion rate remained stable at around 3%, and the methyl formate selectivity remained at around 92%.

[0086] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for the selective synthesis of methyl formate from methanol by catalytic ozonation at ultra-low temperature using a graphdiyne catalyst, characterized in that, The method comprises the following steps: The catalytic reaction is carried out in a mixed gas atmosphere containing methanol and ozone, and the catalytic reaction is carried out at a temperature of-25-25℃, and the catalytic reaction is catalyzed by graphdiyne, and methyl formate is selectively synthesized. The concentration of methanol in the mixed gas atmosphere is 3000-10000ppm. The concentration of ozone in the mixed gas atmosphere is 750ppm. Nitrogen is used as the balance gas in the mixed gas atmosphere. The space velocity of the catalytic reaction is 30000-120000 mL g -1 h -1 ; The graphdiyne does not need to be activated before the catalytic reaction.

2. The method for selectively synthesizing methyl formate by ultra-low temperature catalytic ozonolysis of methanol using a graphdiyne catalyst as described in claim 1, characterized in that... The ozone is generated by oxygen in an ozone generator.

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