A catalyst for preparing cyclopropanecarboxaldehyde, a method for preparing the same, and a method for preparing cyclopropanecarboxaldehyde

Abstract

The application discloses a catalyst for preparing cyclopropanecarboxaldehyde, a preparation method of the catalyst and a preparation method of the cyclopropanecarboxaldehyde. The catalyst comprises 100 parts by weight of an acidic carrier and 0.1-5 parts by weight of a noble metal supported on the surface of the acidic carrier; the catalyst can improve the yield of the cyclopropanecarboxaldehyde; a preparation method of the catalyst is also provided; the acidic carrier powder is mixed with an aqueous solution of a noble metal chloride, and the mixture is sequentially subjected to drying and cooling treatment to obtain a catalyst precursor; the catalyst precursor is sequentially subjected to calcination, reduction and cooling treatment to obtain a catalyst powder; the preparation method is simple and can be used for industrial amplification in batches; a preparation method of the cyclopropanecarboxaldehyde is also provided; 2-methylfuran and a hydrogen-donating solvent are subjected to catalytic hydrogen transfer, catalytic hydrogenation and rearrangement reaction under the action of the catalyst to obtain the cyclopropanecarboxaldehyde; the preparation method can avoid the use of high-pressure hydrogen gas, has the characteristics of shortening a process cycle and easy separation of a product.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically, it relates to a catalyst for preparing cyclopropyl methyl ketone, a method for preparing the same, and a method for preparing cyclopropyl methyl ketone. Background Technology

[0002] Cyclopropyl ketone is an important raw material for organic synthesis, playing a crucial role in introducing cyclopropyl structures into the preparation of many compounds. These structures can improve the lipid solubility and metabolic rate of the products. For example, Bayer AG in Germany developed a triazole thionine-based green fungicide, prothioconazole, for controlling wheat diseases; it degrades naturally without residue. Merck & Co. in the United States developed efavirenz, a non-nucleoside reverse transcriptase inhibitor, which, when combined with other drugs, is used to treat HIV-1 infections. Furthermore, cyclopropyl ketone possesses a strained ring structure, which can be used to prepare a series of synthetic fuels, improving their energy density, specific impulse, and other key properties, thereby enhancing carrying capacity. Therefore, research on industrial preparation methods for cyclopropyl ketone is of great significance.

[0003] Currently, one industrial method for preparing cyclopropyl ketone (CPK) involves using 2-methylfuran as a raw material and proceeding through three steps: catalytic hydrogenation, chlorination, and cyclization. The Pd / C catalyst used in the catalytic hydrogenation step is easily poisoned by trace impurities in the raw material, leading to reduced catalytic activity, prolonged process time, and low CPK yield. Furthermore, the chlorination and cyclization steps consume large amounts of acids and alkalis, generating saline wastewater and unusable tar waste liquid, further contributing to the low CPK yield.

[0004] Another industrial method for preparing cyclopropyl ketone involves the catalytic cracking of 2-acetyl-γ-butyrolactone using alkali metal iodides such as sodium iodide and potassium iodide, yielding cyclopropyl ketone in a single step. This method generates only CO2 as a byproduct and does not emit other toxic or harmful waste, making it environmentally friendly. However, this process requires high temperatures above 150°C, which easily deactivates the iodide catalyst, significantly reducing its catalytic activity. While adding high-boiling-point polar solvents such as N-methylpyrrolidone, dimethylacrylurea, or hexamethylphosphoric triamine can effectively inhibit iodide catalyst deactivation, it accelerates side reactions, introducing new, difficult-to-separate impurities and reducing product purity.

[0005] Chinese invention patent CN106554263 A discloses a novel method for preparing cyclopropyl ketone. This method requires only two steps: catalytic hydrogenation and acid-catalyzed rearrangement. It can produce cyclopropyl ketone in a relatively high yield at a lower temperature, while avoiding the generation of tar byproducts and the emission of large amounts of waste. However, this method still requires two reaction steps and different types of catalysts, prolonging the post-reaction processing and increasing the difficulty of separating the reaction mixture.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide a catalyst for the preparation of cyclopropyl methyl ketone, as well as a method for preparing cyclopropyl methyl ketone. On one hand, the catalyst can improve catalytic activity, thereby increasing the yield of cyclopropyl methyl ketone; on the other hand, the preparation method of the catalyst is simple, can be mass-produced for industrial scale-up, and has good recyclability; furthermore, the method for preparing cyclopropyl methyl ketone avoids the use of high-pressure hydrogen, improving process safety, shortening the process cycle, and features easy product separation, low waste, and simple process, providing a feasible solution for large-scale production.

[0008]

[0009] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0010] This invention provides a catalyst for preparing cyclopropyl methyl ketone, comprising an acidic support and a noble metal supported on the surface of the acidic support;

[0011] In the catalyst, the content of noble metals is 0.1-5 parts by weight relative to 100 parts by weight of acidic support.

[0012] Furthermore, in the catalyst, the content of precious metals is 2-4 parts by weight per 100 parts by weight of acidic support.

[0013] Preferably, in the catalyst, the content of the acidic support is 4 parts by weight, equivalent to 100 parts by weight.

[0014] This can be summarized as the percentage of precious metals in the acidic carrier being 0.1%-5% by mass;

[0015] Within the aforementioned limits, the reaction yield increases with increasing noble metal loading.

[0016] As the optimal solution, the noble metal accounts for 4% of the mass of the acidic carrier;

[0017] Once the noble metal loading reaches 4%, further increasing the loading will mask the acidic sites on the acidic support, hindering the rearrangement reaction and leading to a decrease in reaction yield. Therefore, to ensure a high product yield, a noble metal content of 4% of the support by mass is selected.

[0018] Furthermore, the acidic support is selected from one or more combinations of alumina, titanium dioxide, zirconium dioxide, hafnium dioxide, vanadium pentoxide, niobium pentoxide, or tantalum pentoxide;

[0019] The precious metal is selected from one or more combinations of palladium, platinum, ruthenium, and rhodium;

[0020] Preferably, the acidic carrier is titanium dioxide and the noble metal is palladium.

[0021] When palladium is used as the precious metal, hydrogen production efficiency is the highest, which can accelerate the formation of cyclopropyl ketone.

[0022] Furthermore, the acidic support titanium dioxide is titanium dioxide P25, which was purchased from Evonik-Degussa. Titanium dioxide P25, as a support, has a large specific surface area (approximately 50 m²). 2 / g), thereby increasing the loading of precious metals and dispersing them uniformly, thus significantly improving catalytic performance, making the catalyst highly stable and less prone to deactivation, and the support is strongly acidic, which can effectively promote the rearrangement reaction.

[0023] Further, 0.1-5 parts by weight of precious metal chloride powder are dissolved in water to prepare an aqueous solution of precious metal chloride;

[0024] 100 parts by weight of acidic support powder were mixed with an aqueous solution of noble metal chloride, and the mixture was dried and cooled in sequence to obtain a dry catalyst precursor.

[0025] The catalyst precursor was subjected to calcination, reduction and cooling treatment in sequence to obtain catalyst powder.

[0026] The catalyst is prepared by an equal-volume impregnation-reduction method. The resulting catalyst is a powder. The noble metal chloride can be one or more of palladium chloride, platinum tetrachloride, ruthenium trichloride, and rhodium trichloride. During the preparation process, acidic support powder is added to the aqueous solution of the noble metal chloride under stirring, or the aqueous solution of the noble metal chloride is added to the acidic support powder under stirring.

[0027] The added precious metal chloride accounts for 0.1%-5% of the carrier's mass, equivalent to 0.1-5 parts by weight of 100 parts by weight of acidic carrier powder.

[0028] This invention also provides a method for preparing cyclopropyl ketone using the catalyst described above.

[0029] 2-Methylfuran and a hydrogen-donating solvent undergo catalytic hydrogen transfer, catalytic hydrogenation, and rearrangement reactions in the presence of a catalyst to produce cyclopropyl ketone.

[0030] In the above scheme, the noble metal is supported on an acidic support in elemental form. The noble metal catalyzes the decomposition of the hydrogen-donating solvent to produce hydrogen and catalyzes the hydrogenation of 2-methylfuran. First, the noble metal catalyzes the decomposition of the hydrogen-donating solvent, promoting hydrogen generation. Then, it catalyzes the hydrogenation of 2-methylfuran adsorbed on the surface, generating 2-methyl-4,5-dihydrofuran. The acidic support provides acidic conditions for the rearrangement reaction of 2-methyl-4,5-dihydrofuran, effectively promoting the rearrangement reaction and the formation of cyclopropyl ketone from 2-methylfuran.

[0031] Furthermore, the hydrogen-donating solvent undergoes a catalytic hydrogen transfer reaction in the presence of noble metals in the catalyst to produce hydrogen and carbon dioxide;

[0032] 2-Methylfuran undergoes catalytic hydrogenation in the presence of noble metals in a catalyst to produce 2-methyl-4,5-dihydrofuran;

[0033] 2-Methyl-4,5-dihydrofuran undergoes a rearrangement reaction under acidic conditions provided by an acidic support in a catalyst to produce cyclopropyl ketone.

[0034] Further, 2-methylfuran, hydrogen-donating solvent, and catalyst powder are mixed;

[0035] The mixture is heated to the reaction temperature to carry out the reaction, and the reaction temperature is maintained until the reaction is complete;

[0036] The product obtained after the reaction was completed was processed to obtain cyclopropyl methyl ketone.

[0037] Furthermore, the hydrogen-donating solvent is selected from one or more combinations of formic acid, ammonium formate, hydrazine formate, hydrazine acetate, hydrazine hydrochloride, and hydrazine sulfate.

[0038] In the above scheme, under the catalysis of noble metals, the negative hydrogen molecules in the hydrogen-donating solvent are transferred to the catalyst surface and combine with protons to generate hydrogen in situ. Therefore, the above-mentioned hydrogen-donating solvent can be used as a hydrogen storage material. Compared with high-pressure hydrogen, the above-mentioned hydrogen-donating solvent has better stability, a narrower explosion limit, and is liquid or solid at room temperature, which facilitates feeding operations and enhances process safety.

[0039] Formic acid is the cheapest, and its decomposition to produce hydrogen is only CO2, which is easy to remove and does not interfere with the reaction. Therefore, formic acid is the preferred hydrogen donor solvent.

[0040] Furthermore, the reaction temperature is 40℃-120℃;

[0041] The molar ratio of the hydrogen-donating solvent to 2-methylfuran is 1.0:1 to 1.4:1;

[0042] The mass of the acid catalyst is 1%-10% of the mass of 2-methylfuran;

[0043] Preferably, the reaction temperature is 50-100℃;

[0044] The molar ratio of the hydrogen-donating solvent to 2-methylfuran is 1.1:1 to 1.3:1;

[0045] The mass of the acidic catalyst is 5%-8% of the mass of 2-methylfuran;

[0046] More preferably, the reaction temperature is 60°C;

[0047] The molar ratio of the hydrogen-donating solvent to 2-methylfuran is 1.1:1;

[0048] The mass of the acid catalyst is 6% of the mass of 2-methylfuran.

[0049] In the above scheme, it is necessary to ensure that the hydrogen-donating reagent is in excess of cyclopropyl ketone to provide sufficient hydrogen. However, if the amount of hydrogen-donating reagent is too high, it will cause the intermediate in the reaction process to continue to be hydrogenated, generating 2-methyltetrahydrofuran, which will reduce the reaction selectivity. Therefore, the molar ratio of hydrogen-donating solvent to 2-methylfuran is 1.0:1-1.4:1. In order to further improve the yield of cyclopropyl ketone, the preferred molar ratio of hydrogen-donating solvent to 2-methylfuran is 1.1:1.

[0050] At the temperatures specified above, 2-methylfuran can be readily converted to cyclopropyl ketone. However, if the reaction temperature is too high, side reactions will occur, reducing the reaction selectivity; if the reaction temperature is too low, the reaction will be too slow, reducing production efficiency.

[0051] When the mass of the catalyst and the mass of cyclopropyl methyl ketone are within the above-mentioned limits, the catalyst has good catalytic effect, convenient post-processing, and high production efficiency; however, a large amount of catalyst will reduce product selectivity, while a small amount of catalyst will prolong the reaction time and reduce production efficiency.

[0052] Furthermore, the reaction time for preparing cyclopropyl methyl ketone is 1-7 hours;

[0053] Preferably, the reaction time is 4-5 hours.

[0054] More preferably, the reaction time is 5 hours.

[0055] In the above scheme, reaction time can be understood as the contact time between the reactants and the catalyst. Within the defined reaction time range, 2-methylfuran and the catalyst can be fully contacted, allowing the catalytic reaction to proceed normally without over-reaction, ensuring the utilization rate of raw materials and the yield of products, and improving product selectivity. If the reaction time is too short, the raw materials cannot be converted in time, resulting in a low yield; if the reaction time is too long, by-products are easily generated, reducing product selectivity.

[0056] Furthermore, the reaction pressure for preparing cyclopropyl methyl ketone is 0.1 MPa-2 MPa, preferably 0.1 MPa-1 MPa. Because 2-methylfuran has a low boiling point, increasing the reaction temperature increases the system pressure, placing certain pressure resistance requirements on the reactor wall material. Therefore, the reaction pressure is limited to the range of 0.1 MPa-2 MPa; if the pressure is too high, the pressure resistance requirements become even more stringent, posing a safety hazard.

[0057] Furthermore, the purity of 2-methylfuran is not less than 98.5%, and the purity of the hydrogen-donating reagent is not less than 99%.

[0058] In the above scheme, the high purity of the raw material 2-methylfuran is beneficial to the smooth progress of the reaction; if the purity is too low, palladium poisoning in the catalyst will cause the reaction to stop.

[0059] Both 2-methylfuran and the hydrogen-donating reagent are industrial raw materials and are readily available for purchase.

[0060] Specifically, a catalyst, a hydrogen-donating solvent, and 2-methylfuran are loaded into a reaction vessel. After purging the reaction vessel with argon gas, the temperature is adjusted to the reaction temperature. The reaction vessel is kept at a constant temperature until the reaction is complete. The product obtained at the end of the reaction is then processed to obtain cyclopropyl ketone. During the process, stirring ensures that the 2-methylfuran and the hydrogen-donating reagent are fully in contact with the catalyst to generate cyclopropyl ketone.

[0061] Further, the products obtained after the reaction are filtered sequentially to obtain product filtrate and catalyst filter cake;

[0062] The catalyst filter cake is recovered and reused.

[0063] The product filtrate was distilled, and the fraction collected at normal pressure and a set temperature was cyclopropyl ketone.

[0064] In the above scheme, the steps for processing the product obtained after the reaction include filtration and distillation. Specifically, a hydrophobic polytetrafluoroethylene filter membrane with a pore size of 450 nm is used to filter the product obtained after the reaction. The catalyst is recovered for the next reaction. The filtrate is distilled using a pendulum distillation column, and the fraction at 114℃±1℃ under normal pressure is collected. The fraction is cyclopropyl ketone.

[0065] The product cyclopropyl ketone prepared according to the method of the present invention has a yield of up to 98% and a purity of up to 99.8%.

[0066] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0067] 1. The catalyst of the present invention can improve catalytic activity, thereby increasing the yield of cyclopropyl methyl ketone;

[0068] 2. The catalyst of the present invention has a simple preparation method, can be prepared in batches for industrial scale-up, and has good recyclability.

[0069] 3. The method for preparing cyclopropyl ketone of the present invention avoids the use of high-pressure hydrogen, is inexpensive, and improves process safety; and,

[0070] The method for preparing cyclopropyl methyl ketone of the present invention adopts a one-pot process, which can shorten the process cycle while improving the product yield. It has the characteristics of less product separation, less waste, and simple process, which is conducive to process scale-up and lays the foundation for subsequent large-scale production of the product.

[0071] The specific embodiments of the present invention will be described in further detail below. Detailed Implementation

[0072] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below with reference to some embodiments. Those skilled in the art will understand that the following embodiments are only used to explain the technical principles of this invention and are not intended to limit the scope of protection of this invention. For example, although this application describes the steps of the method of this invention in a specific order, these orders are not restrictive. Those skilled in the art can perform the steps in different orders without departing from the basic principles of this invention.

[0073] The method for calculating the yield of cyclopropyl ketone mentioned in the following examples is as follows:

[0074] Yield of cyclopropyl methyl ketone = (molar amount of cyclopropyl methyl ketone / molar amount of 2-methylfuran) * 100%;

[0075] The method for calculating the purity of cyclopropyl ketone mentioned in the following examples is as follows:

[0076] Using o-dichlorobenzene as a standard, the same mass of o-dichlorobenzene was added to the same mass of standard cyclopropane ketone sample and the test reaction solution, and the peak area was determined by gas chromatography.

[0077] Where S1 = peak area of ​​standard cyclopropyl ketone / peak area of ​​o-dichlorobenzene;

[0078] S2 = Peak area of ​​cyclopropyl methyl ketone in the test solution / Peak area of ​​o-dichlorobenzene;

[0079] Cyclopropyl methyl ketone purity = (S2 / S1) * 100%.

[0080] Example 1

[0081] A catalyst for preparing cyclopropyl methyl ketone includes an acidic support and a noble metal supported on the surface of the acidic support.

[0082] In the catalyst, the content of noble metal is 0.1 parts by weight relative to 100 parts by weight of acidic support.

[0083] Example 2

[0084] A catalyst for preparing cyclopropyl methyl ketone includes an acidic support and a noble metal supported on the surface of the acidic support.

[0085] In the catalyst, the content of noble metal is 5 parts by weight relative to 100 parts by weight of acidic support.

[0086] Example 3

[0087] A catalyst for preparing cyclopropyl methyl ketone includes an acidic support and a noble metal supported on the surface of the acidic support.

[0088] In the catalyst, the content of noble metals is 4 parts by weight relative to 100 parts by weight of acidic support.

[0089] Example 4

[0090] A method for preparing the catalyst as described in any of Examples 1-3 is as follows:

[0091] Impregnation: Dissolve 668 mg of palladium chloride in 25 mL of deionized water to prepare an aqueous solution of palladium chloride; add the aqueous solution of palladium chloride to a beaker containing 100 g of titanium dioxide support powder and mix; sonicate the mixture for 20 min to make palladium chloride uniformly distributed on the surface of titanium dioxide support; then, dry the mixture at 120 °C for 1 h and then cool it to room temperature to obtain a dry catalyst precursor.

[0092] Calcination and reduction: The dried catalyst precursor was removed from the beaker and transferred to a tube furnace. The inside of the tube furnace was heated to 300°C at 20°C / min in an argon atmosphere. A 10% hydrogen / argon mixture was continuously introduced into the tube furnace at a rate of 10 mL / min until no hydrogen chloride gas was generated. The absence of hydrogen chloride gas was determined by monitoring the pH of the tail gas from acidic to neutral. The inside of the tube furnace was then cooled to room temperature in an argon atmosphere. The product was removed and weighed, totaling 104 g, which is the palladium@titanium dioxide catalyst powder.

[0093] Example 5

[0094] A method for preparing cyclopropyl ketone using the catalyst described in any of Examples 1-3, comprising:

[0095] 1250g of 2-methylfuran, 772g of formic acid, and 75g of palladium@titanium dioxide catalyst powder were added to a 5L reactor and mixed. The inside of the reactor was then purged with argon three times.

[0096] The mixture was heated to a reaction temperature of 60°C and stirred vigorously for 5 hours, during which the reaction temperature was maintained until the reaction was completed.

[0097] The product obtained after the reaction was completed was cooled to room temperature and filtered through a hydrophobic polytetrafluoroethylene filter membrane with a pore size of 450 nm. The filtrate was transferred to a 5 L round-bottom flask and heated and distilled through a pendant distillation column with an inner diameter of 32 mm and an effective length of 300 mm. The fraction collected at atmospheric pressure at 114 °C ± 1 °C was the product cyclopropyl ketone.

[0098] Comparative Example 1

[0099] Based on Example 5, the palladium@titanium dioxide catalyst powder was replaced with equimolar amounts of palladium powder and titanium dioxide powder, while other preparation conditions remained unchanged.

[0100] Comparative Example 2

[0101] Based on Example 5, formic acid was replaced with 0.5 MPa hydrogen gas, while other preparation conditions remained unchanged.

[0102] Comparative Example 3

[0103] Based on Example 5, the palladium@titanium dioxide catalyst powder was replaced with equimolar amounts of palladium acetate and methanesulfonic acid to make it a homogeneous reaction system, while other preparation conditions remained unchanged.

[0104] The yields of cyclopropanone were tested in Examples 5, 1, 2, and 3, and the results are shown in Table 1.

[0105] Table 1

[0106]

[0107] As shown in Table 1, in Comparative Example 1, unsupported palladium was physically mixed with titanium dioxide support. During the reaction, palladium particles agglomerated, affecting its catalytic hydrogenation activity and resulting in a significant decrease in the yield of cyclopropyl ketone.

[0108] In Comparative Example 2, hydrogen was used as the hydrogen source. Although the yield of cyclopropyl methyl ketone was close to that of Example 1, the reaction pressure was higher, and there were safety hazards in the reaction system.

[0109] In Comparative Example 3, a homogeneous catalyst was used instead of a heterogeneous catalyst. Although the yield of cyclopropyl methyl ketone was as high as 91%, the catalyst could hardly be recovered after the reaction, which increased the cost and made it unsuitable for industrial production.

[0110] Examples 7-9

[0111] The preparation process described in Example 5 was modified to investigate the effect of the type of noble metal on the reaction effect. Only the noble metal composition was changed, while other conditions remained the same, resulting in Examples 7 to 9, as shown in Table 2.

[0112] Table 2

[0113]

[0114] As can be seen from the data in Table 2, when the active components are palladium, platinum, ruthenium, and ruthenium, they can all catalyze the preparation of cyclopropyl ketone from 2-methylfuran, with yields all above 64% and product purity all above 91%. This is because the above noble metals can all catalyze the decomposition of formic acid to produce hydrogen and the hydrogenation of 2-methylfuran, and palladium has the best catalytic effect, hence the highest yield of cyclopropyl ketone.

[0115] Examples 10-14

[0116] As described in Example 5, to investigate the effect of the hydrogen donor on the reaction, only the hydrogen donor was changed while other conditions remained the same, resulting in Examples 10 to 14, as shown in Table 3:

[0117] Table 3

[0118]

[0119]

[0120] As can be seen from the data in Table 3, the above-mentioned hydrogen-donating reagents can all catalyze the preparation of cyclopropyl ketone from 2-methylfuran, with yields all above 42% and product purity all above 71%. This is because hydrazine can also provide negative hydrogen, but its activity is weaker than that of formic acid. However, hydrazine formic acid has excessively high activity, resulting in the over-hydrogenation product 2-methyltetrahydrofuran. Formic acid has reasonable activity, hence the highest yield and purity of cyclopropyl ketone.

[0121] Experimental Examples 15-20

[0122] As described in Example 5, to investigate the effect of the mass percentage of noble metal in the acidic support on the reaction effect, only the mass percentage of noble metal in the acidic support was changed, while other conditions remained the same, resulting in Examples 15 to 20, as shown in Table 4:

[0123] Table 4

[0124]

[0125] As can be seen from the data in Table 4, when the mass percentage of palladium in the acidic support is between 0.1% and 4%, the yield of cyclopropyl ketone is significantly improved. However, if the palladium loading is further increased, the acidic sites on the support are masked, resulting in a decrease in the yield of cyclopropyl ketone. Under the premise of ensuring high yield and selectivity of the product without increasing the cost, an excessively high loading should not be used. Instead, a palladium mass percentage of 4% in the support should be selected.

[0126] Examples 21-24

[0127] As described in Example 5, to investigate the effect of reaction temperature on the reaction effect, only the reaction temperature was changed while other conditions remained the same, resulting in Examples 21 to 24, as shown in Table 5:

[0128] Table 5

[0129]

[0130] As can be seen from the data in Table 5, when the reaction temperature is 60℃, the yield of cyclopropyl ketone is as high as 98% and the purity is as high as 99.8%. However, catalytic hydrogenation is an exothermic reaction. If the reaction temperature continues to rise, it will not be conducive to the catalytic hydrogenation reaction of 2-methylfuran, thus reducing the yield and purity of cyclopropyl ketone. On the other hand, if the reaction temperature is too low, the reaction will be too slow.

[0131] Examples 25-33

[0132] Following the preparation process described in Example 5, the percentage of catalyst mass to 2-methylfuran mass was changed while other conditions remained the same, resulting in Examples 25 to 33, as shown in Table 6:

[0133] Table 6

[0134]

[0135]

[0136] As can be seen from the data in Table 6, when the mass of the catalyst is 1%-6% of the mass of 2-methylfuran, the yield of the product gradually increases with the increase of the catalyst mass. However, when the mass of the catalyst accounts for more than 6% of the mass of cyclopropyl methyl ketone, the increase of the catalyst mass has no effect on the increase of the cyclopropyl methyl ketone yield. Therefore, under the premise of ensuring that the target product can be obtained, it is preferable that the mass of the catalyst accounts for 6% of the mass of 2-methylfuran.

[0137] Examples 34-38

[0138] To investigate the effect of the amount of hydrogen donor on the reaction, the molar ratio of hydrogen donor to 2-methylfuran was changed while other conditions remained constant, resulting in Examples 34 to 38, as shown in Table 7:

[0139] Table 7

[0140]

[0141] As can be seen from the data in Table 7, increasing the amount of formic acid is beneficial to increasing the yield of cyclopropyl methyl ketone. However, when the molar ratio of formic acid to 2-methylfuran reaches 1.1:1, further increasing the amount of formic acid will cause excessive hydrogenation of 2-methylfuran, generating 2-methyltetrahydrofuran, which will reduce the yield and purity of cyclopropyl methyl ketone. Therefore, the preferred molar ratio of formic acid to 2-methylfuran is 1.1:1.

[0142] Examples 39-42

[0143] As described in Example 5, to investigate the effect of the catalyst support on the reaction effect, only the catalyst support was changed while other conditions remained the same, resulting in Examples 39 to 42, as shown in Table 8:

[0144] Table 8

[0145]

[0146] As shown in Table 8, when palladium remains constant as the noble metal and the catalyst support is titanium dioxide, zirconium dioxide, vanadium pentoxide, or niobium pentoxide, the yield of cyclopropyl ketone is above 20%, and the product purity is above 70%. When the catalyst support is titanium dioxide, zirconium dioxide, or hafnium dioxide, the product purity of cyclopropyl ketone is above 95%. In particular, when the catalyst support is titanium dioxide, the yield of cyclopropyl ketone reaches as high as 98%, and the product purity reaches as high as 99.8%. This is because titanium dioxide, as a support, has a large specific surface area, which increases the palladium loading and makes it uniformly dispersed, thereby significantly improving the catalytic performance and making the catalyst highly stable. Furthermore, the strong acidity of this titanium dioxide support can effectively promote the rearrangement reaction, thus improving the yield and purity of cyclopropyl ketone.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing cyclopropyl ketone, characterized in that, include: 2-Methylfuran and a hydrogen-donating solvent undergo catalytic hydrogen transfer, catalytic hydrogenation, and rearrangement reactions in the presence of a catalyst to produce cyclopropyl ketone. The hydrogen-donating solvent undergoes a catalytic hydrogen transfer reaction in the presence of noble metals in the catalyst to produce hydrogen and carbon dioxide. 2-Methylfuran undergoes catalytic hydrogenation in the presence of noble metals in a catalyst to produce 2-methyl-4,5-dihydrofuran; 2-Methyl-4,5-dihydrofuran undergoes a rearrangement reaction under acidic conditions provided by an acidic support in a catalyst to produce cyclopropyl ketone; The catalyst includes an acidic support and a noble metal supported on the surface of the acidic support; In the catalyst, the content of noble metals is 2-4 parts by weight relative to 100 parts by weight of acidic support. The acidic support is selected from one or a combination of two of alumina and titanium dioxide; The precious metal is selected from one or a combination of two of palladium and platinum; The hydrogen-donating solvent is selected from one or a combination of two of formic acid and ammonium formate. The mass of the acid catalyst is 5%-8% of the mass of 2-methylfuran.

2. The preparation method according to claim 1, characterized in that, In the catalyst, the content of 100 parts by weight of acidic support is 4 parts by weight of precious metal.

3. The preparation method according to claim 2, characterized in that, The acidic carrier is titanium dioxide, and the noble metal is palladium.

4. The preparation method according to any one of claims 1-3, characterized in that, include: Dissolve 0.1-5 parts by weight of precious metal chloride powder in water to prepare an aqueous solution of precious metal chloride; 100 parts by weight of acidic support powder were mixed with an aqueous solution of noble metal chloride, and the mixture was dried and cooled in sequence to obtain a dry catalyst precursor. The catalyst precursor was subjected to calcination, reduction and cooling treatment in sequence to obtain catalyst powder.

5. The preparation method according to claim 4, characterized in that, include: 2-Methylfuran, hydrogen-donating solvent, and catalyst powder are mixed; The mixture is heated to the reaction temperature to carry out the reaction, and the reaction temperature is maintained until the reaction is complete; The product obtained after the reaction was completed was processed to obtain cyclopropyl methyl ketone.

6. The preparation method according to claim 5, characterized in that, The hydrogen-donating solvent is formic acid.

7. The preparation method according to claim 5, characterized in that, The reaction temperature is 40℃-120℃; The molar ratio of the hydrogen-donating solvent to 2-methylfuran is 1.0:1 to 1.4:

1.

8. The preparation method according to claim 7, characterized in that, The reaction temperature is 50-100℃; The molar ratio of the hydrogen-donating solvent to 2-methylfuran is 1.1:1 to 1.3:

1.

9. The preparation method according to claim 8, characterized in that, The reaction temperature is 60℃; The molar ratio of the hydrogen-donating solvent to 2-methylfuran is 1.1:1; The mass of the acid catalyst is 6% of the mass of 2-methylfuran.

10. The preparation method according to claim 5, characterized in that, include: The products obtained after the reaction were filtered sequentially to obtain product filtrate and catalyst filter cake. The catalyst filter cake is recovered and reused; The product filtrate was distilled, and the fraction collected at normal pressure and a set temperature was cyclopropyl ketone.

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