A Pd-Cu-X monolithic catalyst, its preparation method and uses

Abstract

The present invention discloses a Pd-Cu-X monolithic catalyst for gas-phase carbonylation synthesis of dimethyl carbonate and a preparation method thereof, which comprises a coating and a substrate. The coating includes an active component Pd, a promoter component Cu, an X metal, the X metal being one or a mixture of more than one of Co, Fe, and La, and a carrier γ-Al2O3. The substrate is a cordierite structure with a hydrotalcite coating. The preparation of this catalyst is characterized by using solid-phase synthesis to prepare a cordierite substrate with a spinel shell layer, preparing an active component coating by a stepwise impregnation method, and preparing the monolithic catalyst by a coating method. This catalyst has excellent activity and good stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of dimethyl carbonate production, and particularly relates to a Pd-Cu-X monolithic catalyst and a preparation method thereof, which are used for synthesizing dimethyl carbonate (DMC), and particularly relates to a catalyst for the gas-phase oxidative carbonylation reaction of carbon monoxide and methyl nitrite to prepare dimethyl carbonate and a preparation method thereof. Background Art

[0002] DMC is an environmentally friendly chemical product with great development potential. Due to its low toxicity, good biodegradability and high oxygen content (53.3%), it can be used as a gasoline additive to improve the combustion performance and anti-knock performance of oil products. DMC is an oxidant with relatively strong oxidizing property. Compared with traditional (methyl tert-butyl ether) MTBE, its CO emissions and total hydrocarbons will be greatly reduced. In addition, DMC is also an environmentally friendly solvent that can replace toxic solvents such as benzene, toluene, ethyl acetate, acetone, butyl acetate, xylene, and halogenated alkanes, and is widely used in fields such as beauty and skin care, lithium-ion battery electrolytes, pharmaceutical products, pesticides, fertilizers, and detergents. As a green chemical with great development potential, its market prospect is very broad.

[0003] The synthesis routes of DMC mainly include the following five types: phosgene method, transesterification method, oxidative carbonylation method, direct synthesis method of methanol and CO2, and urea alcoholysis method. Among them, the method of synthesizing dimethyl carbonate by gas-phase oxidative carbonylation of CO has the advantages of simple raw material preparation, low cost, avoiding the use of phosgene, simple process, and good product quality, and is a relatively advanced DMC synthesis method at present. Based on a large number of studies on carbonylation synthesis of oxalic acid and dimethyl oxalate, the Japanese UBE company successfully developed a technology for gas-phase carbonylation to prepare DMC by further improving the catalyst, and built an industrial device with a production capacity of 3000 t / a in 1992. This method uses palladium salt as a catalyst, methyl nitrite as a circulating solvent and intermediate, and the reaction proceeds in two steps. The reaction equations are as follows:

[0004] 3CH3OH + 2NO + 1 / 2O2 → 2CH3ONO + H2O

[0005] CO + 2CH3ONO → (CH3O)2CO + 2NO

[0006] The development of catalysts used in the reaction process of synthesizing dimethyl carbonate from carbon monoxide and methyl nitrite is one of the key technologies. Most of the existing industrialized processes for synthesizing dimethyl carbonate by oxidative coupling of carbon monoxide use palladium chloride-containing catalysts, and the loss of chloride ions on the catalysts often causes a decrease in catalyst activity. To improve the stability of the catalyst, the most common measure is to add a certain amount of chlorine-containing compounds, such as HCl or methyl chloroformate, etc., to the feed gas. For example, US Patent No. 5426209 discloses a catalyst with activated carbon as the carrier, palladium chloride as the main active component, and copper chloride as the promoter. The optimal space-time yield of DMC is 725 g / (L*h), and it can only be stable for 8 hours. US Patent No. 5688984 discloses a carrier for a catalyst for synthesizing dimethyl carbonate, which is lithium aluminate with a spinel structure. The catalyst prepared using this carrier has high activity and selectivity, and the selectivity reaches over 95% based on carbon monoxide and methyl nitrite. By adding different promoters, the performance of the catalyst can be improved to varying degrees, but the catalyst life is still short. From the data reported in the literature, even if HCl is continuously supplemented during the reaction process, the activity of the catalyst decreases by 20% - 30% during the 100-hour reaction period. The low activity and short service life of the catalyst greatly limit its industrial application. Summary of the Invention

[0007] The purpose of the present invention is to provide a Pd-Cu-X monolithic catalyst and its preparation method, which has high catalyst activity and good stability. The preparation method of the catalyst is simple and has low energy consumption, and is suitable for industrial production and application.

[0008] Another purpose of the present invention is to provide the use of the above-mentioned catalyst for catalytic preparation of dimethyl carbonate, especially for the gas-phase oxidative carbonylation reaction of carbon monoxide and methyl nitrite to prepare dimethyl carbonate, so as to solve the problems of poor stability of the existing chlorine-containing catalysts for CO gas-phase carbonylation synthesis of dimethyl carbonate and equipment corrosion caused by chlorine replenishing agents in the above-mentioned background technology.

[0009] The catalyst for gas-phase carbonylation to prepare dimethyl carbonate described in the present invention is a coated monolithic catalyst, which is composed of two major parts: a catalyst coating and a substrate. The catalyst coating includes an active component Pd, a promoter component Cu, a metal X, and a carrier γ-Al2O3. Preferably, based on the metal elements, the content of the active component Pd is 0.2 - 2% of the total weight of the coating, the content of the promoter component Cu is 0.4 - 4% of the total weight of the coating, the content of the promoter component X is 0.4 - 4% of the total weight of the coating, and the rest is γ-Al2O3. The catalyst also includes a cordierite structure with a hydrotalcite coating on the substrate, and the mass of the substrate is 1.5 - 4 times the mass of the coating.

[0010] The preparation method of the Pd-Cu-X monolithic catalyst described in the present invention comprises the following steps:

[0011] (1) Dissolve a copper salt in a solvent, add γ-Al2O3, stir, impregnate, age, dry, and calcine;

[0012] (2) Dissolve a palladium salt and a salt solution of metal element X in a hydrochloric acid solution. After complete dissolution, put the sample prepared in step (1)

[0013] into the above solution, impregnate, dry, and then calcine to obtain the catalyst precursor A sample;

[0014] (3) Cut cordierite into cubes, and treat cordierite by boiling in an acid solution at 90-110°C for 1-

[0015] 4 h, wash with deionized water until the washing liquid is neutral, and dry overnight at 80-140°C to obtain the pretreated cordierite;

[0016] (4) Mix a metal oxide with the pretreated cordierite, and calcine at a high temperature to obtain a cordierite matrix with a hydrotalcite coating;

[0017] (5) Ball-mill the catalyst precursor A and a certain amount of water together to make a slurry with a solid content of 30-50 wt%. Immerse the cordierite matrix with a hydrotalcite coating in the prepared slurry. Preferably, the mass of the matrix is 5.0-10.0 times the mass of the slurry. Take the matrix out of the slurry, and dry and then calcine the cordierite coated with the slurry to obtain the monolithic catalyst B.

[0018] Preferably, in step (1), the copper salt is one of copper nitrate and copper chloride, preferably the hydrate of copper chloride, and the solvent is one or more selected from methanol, ethanol, isopropanol, ethylene glycol, and propylene oxide. Preferably, it is a mixture of propylene oxide and methanol or ethanol, and more preferably, the volume ratio of propylene oxide to methanol (or ethanol) is 1:1-1.5:1.

[0019] Preferably, the specific surface area of the γ-Al2O3 is 200-350 m 2 / g, the pore volume of the carrier is 0.2-0.6 cm 3 / g, and the average pore diameter of the carrier is 10-50 nm.

[0020] Preferably, in step (1), the aging time of the γ-Al2O3 in the copper salt solution is 2-24 h, and the aging temperature is 20-60°C. More preferably, the aging time is 6-12 h, and the aging temperature is 30-50°C. Preferably, the drying temperature is 60-80°C, and the drying time is 2-6 h. Preferably, the calcination temperature is 200-350°C, and the calcination time is 2-4 h.

[0021] Preferably, the solvent of the palladium salt in step (2) of the catalyst preparation process is a 0.5% - 10% hydrochloric acid solution, and more preferably the concentration of the hydrochloric acid solution is 0.5% - 5%.

[0022] The salt of the X metal in step (2) is preferably a chloride or nitrate of one or a mixture of several of Co, Fe, and La.

[0023] Preferably, the impregnation process in step (2) is carried out at 20 - 60 °C for 2 - 24 h, and more preferably the impregnation time is carried out at 20 - 40 °C for 2 - 12 h. The drying process before calcination is carried out at 40 - 80 °C for 1 - 6 h, and then calcined at 150 - 350 °C for 1 - 4 h. More preferably, the drying temperature is 60 - 80 °C, the drying time is 2 - 6 h, the calcination temperature is 200 - 350 °C, and the calcination time is 2 - 4 h.

[0024] Preferably, the acid solution in step (3) is a mixture of one of organic acids such as citric acid and oxalic acid and one of inorganic acids such as hydrochloric acid and nitric acid. The concentration of the acid solution is 5 - 20%, and the mass ratio of the inorganic acid to the organic acid is 0.1 - 2. More preferably, the acid solution is oxalic acid and hydrochloric acid, with a ratio of 0.1 - 1.5, and the concentration of the acid solution is 10 - 15%.

[0025] Preferably, the calcination condition in step (4) is carried out at a temperature of 800 - 1000 °C for 4 - 12 h.

[0026] Preferably, the drying process before calcination in step (5) is to dry the cordierite coated with the slurry at 40 - 80 °C for 1 - 6 h, and then calcine it at 150 - 350 °C for 1 - 4 h. More preferably, the drying temperature is 60 - 80 °C, the drying time is 2 - 6 h, the calcination temperature is 200 - 350 °C, and the calcination time is 2 - 4 h.

[0027] Another object of the present invention is to provide a method for synthesizing dimethyl carbonate using the monolithic catalyst prepared above, that is, adding the monolithic Pd - Cu - X catalyst into a fixed - bed reactor, and then using methyl nitrite and carbon monoxide as reaction gases, and adding nitrogen for dilution and mixing at the same time, and carrying out a synthesis reaction after mixing. Preferably, the temperature of the synthesis reaction is controlled at 110 - 140 °C, the reaction pressure is controlled at atmospheric pressure - 1.0 Mpa; the volume fraction of CO is 10% - 20%, the volume fraction of methyl nitrite is 10% - 20%, the reaction control temperature is 120 - 140 °C, and the volume space velocity is 1500 - 6500 h -1 。

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] (1) The integral catalyst matrix used in the present invention is cordierite honeycomb ceramics. Cordierite itself has high thermal stability, and its unique honeycomb structure can achieve uniform distribution of gas flow to a certain extent, preventing local heat accumulation. The reaction of synthesizing dimethyl carbonate from CO and nitrite ester is a strongly exothermic reaction. The rapid removal of heat can effectively improve the space-time yield of dimethyl carbonate and reduce the generation probability of by-products. It can effectively solve the problems existing in the current industrial catalysts, such as large bed pressure drop, large bed temperature gradient, and poor mass transfer effect.

[0030] (2) The present invention adopts the method of stepwise impregnation. In the Wacker-type catalyst prepared by this method, the copper phase forms more active copper species Cu2Cl(OH)3 on the catalyst surface. This active copper species has better catalytic oxidation performance and can have a stronger interaction with the active component Pd, avoiding the reduction of the Pd active component and improving the stability of the catalyst.

[0031] (3) Through the action of metal oxides and acid-etched cordierite, acid etching makes cordierite form structural defects. The substitution of metal cations for Mg in the cordierite structure results in the formation of interstitial oxygen ion vacancy defects in the structure. The defects cause lattice distortion of cordierite and promote the diffusion of cations in the cordierite structure. A large number of structural defects enable alumina in the cordierite structure to react with metal oxides to form a spinel structure under solid-state conditions. The spinel shell increases the specific surface area of cordierite while retaining the strength of the cordierite structure, enhancing the interaction between the coating and the matrix. 2+ (4) The preparation method of the palladium catalyst provided by the present invention is simple and has low energy consumption, suitable for industrial production and application, and can be applied to the oxidative coupling of carbon monoxide to synthesize dimethyl carbonate.

[0032] (4) The preparation method of the palladium catalyst provided by the present invention is simple and has low energy consumption, suitable for industrial production and application, and can be applied to the oxidative coupling of carbon monoxide to synthesize dimethyl carbonate. Specific Embodiments

[0033] The present invention will be further described below in conjunction with embodiments. However, the present invention is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights required by the present invention.

[0034] Example 1

[0035] Catalyst Preparation: Dissolve 0.5 g of CuCl2·2H2O in a 2 mL mixed solution of propylene oxide and ethanol (propylene oxide:ethanol volume ratio is 1:1). Continuously stir until the solution becomes a light green turbid liquid. Add 15 g of γ-Al2O3 (Super Science Alumina Materials Co., Ltd., specific surface area 308 m² / g, pore volume 0.43 ml / g, average pore diameter 10.8 nm) to the above turbid liquid, stir for 30 min for impregnation, age at 50 °C for 6 h, dry at 80 °C under vacuum for 2 h, then transfer the sample to a muffle furnace and calcine at 350 °C for 2 h. Dissolve 0.34 g of PdCl2 and 1.78 g of Fe(NO3)3 in a 0.5% hydrochloric acid solution. After complete dissolution, put the prepared sample into the above solution, impregnate at 20 °C for 12 h, dry at 80 °C under vacuum for 2 h, then transfer the sample to a muffle furnace and calcine at 350 °C for 2 h to obtain the catalyst precursor A sample. Ball mill 15 g of the catalyst precursor A powder and 15 g of deionized water together to make a slurry with a solid content of 49 wt%. Immerse 40 g of cordierite honeycomb ceramics in a 10% oxalic acid solution, boil at 100 °C for 2 h. After treatment, take out the cordierite, wash it with deionized water until the washing liquid is neutral, dry the pretreated cordierite at 120 °C overnight. Mix 4 g of CeO solid with the pretreated cordierite and calcine at 800 °C for 4 h to obtain a cordierite matrix with a Ce-Al-O spinel shell layer. Immerse this matrix in the prepared slurry, take out the matrix from the slurry, dry the cordierite coated with the slurry at 80 °C under vacuum for 2 h, then transfer the sample to a muffle furnace and calcine at 350 °C for 2 h to obtain the monolithic catalyst B.

[0036] Catalyst Evaluation: Add 2 mL of the monolithic Pd-Cu-X catalyst B into a fixed-bed reactor, then use methyl nitrite and carbon monoxide as reaction gases, and add nitrogen for dilution and mixing at the same time. After mixing, carry out the synthesis reaction. The reaction temperature is 130 °C, and the reaction pressure is controlled at atmospheric pressure; the volume fraction of CO is 10%, the volume fraction of methyl nitrite is 20%, and the volume space velocity is 3000 h -1 。

[0037] Example 2

[0038] Catalyst Preparation: Dissolve 0.21 g of Cu(NO3)2 in a 2 mL mixed solution of propylene oxide and methanol (volume ratio of propylene oxide to methanol is 1.5:1), and continuously stir until the solution becomes a light green turbid liquid. Add 15 g of γ-Al2O3 to the above turbid liquid, stir for 30 min for impregnation, age at 40 °C for 8 h, dry in vacuum at 60 °C for 4 h, then transfer the sample to a muffle furnace and calcine at 200 °C for 4 h. Dissolve 1.56 g of PdCl2 and 0.35 g of La(NO3)3 in a 5% hydrochloric acid solution. After complete dissolution, put the prepared sample into the above solution, impregnate at 40 °C for 6 h, dry in vacuum at 60 °C for 4 h, then transfer the sample to a muffle furnace and calcine at 300 °C for 3 h to obtain the catalyst precursor A sample. Ball-mill 15 g of the catalyst precursor A powder and 30 g of deionized water together to make a slurry with a solid content of 30 wt%. Immerse 26 g of cordierite honeycomb ceramics in a 10% HCl solution, boil at 90 °C for 4 h. After treatment, take out the cordierite, wash it with deionized water until the washing liquid is neutral, dry the pretreated cordierite at 140 °C overnight. Mix 2.5 g of ZnO solid with the pretreated cordierite and calcine at 900 °C for 12 h to obtain a cordierite matrix with a Zn-Al-O spinel shell layer. Immerse this matrix in the prepared slurry, take out the matrix from the slurry. For the cordierite coated with the slurry, dry in vacuum at 65 °C for 6 h, then transfer the sample to a muffle furnace and calcine at 300 °C for 2 h to obtain the monolithic catalyst B.

[0039] Catalyst Evaluation: The evaluation steps of the catalyst are the same as those in Example 1, and the evaluation results of the catalyst are shown in the following table.

[0040] Example 3

[0041] Catalyst Preparation: Dissolve 1.6 g of CuCl₂·2H₂O in a 2 mL mixed solution of propylene oxide and ethanol (volume ratio of propylene oxide to ethanol is 1.3:1), and continuously stir until the solution becomes a light green turbid liquid. Add 15 g of γ-Al₂O₃ to the above turbid liquid, stir for 30 min for impregnation, age at 30 °C for 12 h, dry in vacuum at 70 °C for 6 h, then transfer the sample to a muffle furnace and calcine at 300 °C for 2.5 h. Dissolve 2.89 g of PdCl₂ and 0.23 g of Co(NO₃)₂ in a 10% hydrochloric acid solution. After complete dissolution, put the prepared sample into the above solution, impregnate at 40 °C for 12 h, dry in vacuum at 60 °C for 6 h, then transfer the sample to a muffle furnace and calcine at 350 °C for 4 h to obtain the catalyst precursor A sample. Ball-mill 15 g of the catalyst precursor A powder and 20 g of deionized water together to make a slurry with a solid content of 41 wt%. Immerse 72 g of cordierite honeycomb ceramics in a 15% oxalic acid solution, boil at 110 °C for 2 h. After treatment, take out the cordierite, wash it with deionized water until the washing liquid is neutral, dry the pretreated cordierite at 100 °C overnight. Mix 7 g of CeO solid with the pretreated cordierite and calcine at 1000 °C for 8 h to obtain a cordierite matrix with a Ce-Al-O spinel shell layer. Immerse this matrix in the prepared slurry, take out the matrix from the slurry, dry the cordierite coated with the slurry in vacuum at 80 °C for 2 h, then transfer the sample to a muffle furnace and calcine at 350 °C for 2 h to obtain the monolithic catalyst B.

[0042] Catalyst Evaluation: The evaluation steps of the catalyst are the same as those in Example 1, and the evaluation results of the catalyst are shown in the following table.

[0043] Comparative Example 1

[0044] Catalyst Preparation: The preparation process of the catalyst refers to that described in Example 2, the difference is that there is no pretreatment process of cordierite honeycomb ceramics. Mix 2.5 g of ZnO solid directly with cordierite and calcine at 900 °C for 12 h to obtain a cordierite matrix with a Zn-Al-O spinel shell layer. Immerse this matrix in the prepared slurry, take out the matrix from the slurry, dry the cordierite coated with the slurry in vacuum at 65 °C for 6 h, then transfer the sample to a muffle furnace and calcine at 300 °C for 2 h to obtain the monolithic catalyst B.

[0045] Comparative Example 2

[0046] Catalyst Preparation: The preparation process of the catalyst refers to that described in Example 2, with the difference that there is no pretreatment process for cordierite honeycomb ceramics. 0.21 g of Cu(NO3)2, 1.56 g of PdCl2, and 0.35 g of La(NO3)3 are dissolved in a 5% hydrochloric acid solution. After complete dissolution, 15 g of γ-Al2O3 is added to the above solution and impregnated at 40 °C for 6 h. After drying in vacuum at 60 °C for 4 h, the sample is transferred to a muffle furnace and calcined at 300 °C for 3 h to obtain the catalyst precursor A sample.

[0047] Catalyst Evaluation: The evaluation steps of the catalyst are the same as those in Example 1, and the evaluation results of the catalyst are shown in the following table.

[0048]

Claims

1. A Pd-Cu-X monolithic catalyst, characterized in that, It includes a coating and a substrate. The coating is composed of an active component Pd, a promoter component Cu, a metal X, and a support γ-Al₂O₃. The metal X is one or a mixture of more than one of Co, Fe, and La. The substrate is a cordierite structure with a hydrotalcite coating. Calculated by metal element, the content of the active component Pd is 0.2-2% of the total weight of the coating, the content of the promoter component Cu is 0.4-4% of the total weight of the coating, the content of the promoter component metal X is 0.4-4% of the total weight of the coating, and the rest is γ-Al₂O₃. The mass of the substrate is 1.5-4 times that of the coating. Among them, the preparation method of the Pd-Cu-X monolithic catalyst includes the following steps: (1) Dissolve the copper salt in a solvent, add γ-Al₂O₃, stir, impregnate, age, dry, and calcine. (2) Dissolve the palladium salt and the salt of metal X in a hydrochloric acid solution. After complete dissolution, put the sample prepared in step (1) into the above solution, impregnate, dry, and then calcine to obtain the catalyst precursor A sample. (3) Cut the cordierite into cubes, boil the cordierite with an acid solution, wash it with deionized water until the washing liquid is neutral, and dry overnight to obtain the pretreated cordierite. (4) Mix the metal oxide with the pretreated cordierite and calcine to obtain a cordierite substrate with a hydrotalcite coating. (5) Ball-mill the catalyst precursor A and water together to make a slurry with a solid content of 30-50 wt%. Immerse the cordierite substrate with a hydrotalcite coating in the prepared slurry, take out the substrate from the slurry, dry, and calcine to obtain the monolithic catalyst B.

2. The catalyst according to claim 1, characterized in that, In the preparation method of the catalyst, in step (1), the specific surface area of the γ-Al2O3 is 200-350 m 2 / g, the pore volume of the carrier is 0.2-0.6 cm 3 / g, and the average pore diameter of the carrier is 10-50 nm.

3. The catalyst according to claim 1, wherein In the catalyst preparation method, in step (1), the copper salt is one of copper nitrate and copper chloride, and the solvent is selected from one or more of methanol, ethanol, isopropanol, ethylene glycol, and propylene oxide.

4. The catalyst according to claim 3, characterized in that, In the catalyst preparation method, in step (1), the solvent is a mixture of propylene oxide and methanol or ethanol.

5. The catalyst according to claim 4, characterized in that, In the catalyst preparation method, in step (1), the volume ratio of propylene oxide to methanol or ethanol is 1:1-1.5:

1.

6. The catalyst according to claim 1, wherein In the catalyst preparation method, in step (2), the palladium salt is palladium chloride, and the concentration of the hydrochloric acid solution is 0.5%-10%.

7. The catalyst according to claim 1, wherein In the catalyst preparation method, in step (2), the metal X is one or a mixture of more than one of Co, Fe, and La, and the salt of metal X is one of the chlorides and nitrates of the above metal elements.

8. The catalyst according to claim 1, characterized in that, In the catalyst preparation method, in step (3), the acid solution is a mixture of one of citric acid and oxalic acid (organic acids) and one of hydrochloric acid and nitric acid (inorganic acids). The concentration of the acid solution is 5-20%, and the mass ratio of the inorganic acid to the organic acid mixture is 0.1-2.

9. The catalyst according to claim 1, characterized in that, In the catalyst preparation method, in step (3), the boiling temperature is 90-110 °C, and the drying temperature is 80-140 °C.

10. The catalyst according to claim 1, characterized in that, In the catalyst preparation method, in step (4), the metal oxide is the oxide of Ce and / or Zn.

11. The catalyst according to claim 1, characterized in that, In the catalyst preparation method, in step (4), the calcination condition is to calcine at a temperature of 800-1000 °C for 4-12 h.

12. The catalyst according to claim 1, characterized in that, In the preparation method of the catalyst, the calcination process after drying in step (5) is to dry the cordierite coated with the slurry at 40-80°C for 1-6 h, and then calcine it at 150-350°C for 1-4 h.

13. The catalyst according to claim 1, characterized in that, In the preparation method of the catalyst, the mass of the substrate in step (5) is 5.0-10.0 times the mass of the slurry.

14. Use of the catalyst according to any one of claims 1-13 in the gas-phase carbonylation for synthesizing dimethyl carbonate.

15. Use of the catalyst according to claim 14 for catalytic gas-phase carbonylation reaction of carbon monoxide and methyl nitrite to prepare dimethyl carbonate.

16. The use according to claim 15, characterized in that: Add the Pd-Cu-X monolithic catalyst into a fixed-bed reactor, then use methyl nitrite and carbon monoxide as reaction gases, and simultaneously add nitrogen for dilution and mixing, and carry out a synthesis reaction after mixing.

17. The use according to claim 16, wherein: The temperature of the synthesis reaction is controlled at 110 - 140 °C, and the reaction pressure is controlled at atmospheric pressure - 1.0 Mpa; the volume fraction of CO is 10% - 20%, the volume fraction of methyl nitrite is 10% - 20%, the reaction control temperature is 120 - 140 °C, and the volume space velocity is 1500 - 6500 h -1 .

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