Sulfur-doped activated carbon supported palladium metal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a sulfur-doped activated carbon supported palladium metal catalyst as well as a preparation method and application thereof. The preparation method comprises the following specific steps: obtaining a sulfur-doped activated carbon carrier; loading a palladium metal precursor compound on the sulfur-doped activated carbon carrier by an impregnation method; and reducing by using a liquid-phase reducing agent to obtain the sulfur-doped activated carbon supported palladium metal catalyst. The invention provides the application of the sulfur-doped activated carbon supported palladium metal catalyst in synthesis of 1, 3-dimethyl-2-imidazolinone by a hydrogenation method, the sulfur-doped activated carbon supported palladium metal catalyst shows excellent activity and high selectivity under mild conditions, the reaction time is shortened, and the sulfur-doped activated carbon supported palladium metal catalyst has good catalytic stability.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a sulfur-doped activated carbon-supported palladium metal catalyst for synthesizing 1,3-dimethyl-2-imidazolidinone by hydrogenation, and a preparation method and application thereof. Background Art

[0002] 1,3-Dimethyl-2-imidazolidinone (DMI) is a colorless, transparent, highly polar aprotic solvent with excellent solvent properties. It has excellent solubility for inorganic substances, organic substances and some resins. It can be miscible with water in any proportion. It has the advantages of low toxicity, acid and alkali resistance, good stability, high boiling point and flash point, and large dielectric constant. Therefore, it has been widely used in electrochemistry, microelectronics, drug synthesis, petrochemicals, etc. At the same time, its performance is better than that of ordinary inert solvents such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N-methylpyrrolidone (NMP), and it can replace carcinogenic hexamethylphosphoric acid triamide (HMPA). In industrial production, it can effectively improve safety, reduce environmental pollution, and improve product quality, and is known as the "ace solvent."

[0003] At present, the synthesis method of DMI can be divided into two processes:

[0004] (1) Direct cyclization method: DMI is synthesized by reacting N,N'-dimethylethylenediamine with a carbonylation reagent (phosgene, urea, carbon dioxide, trichloroacetyl chloride, etc.). However, it has obvious disadvantages, such as harsh reaction conditions, high cost, and high toxicity.

[0005] (2) Indirect methylation method: DMI is synthesized by N-methylation reaction of 2-imidazolidinone with alkylating agents (methyl halides, dimethyl sulfate, formaldehyde, etc.). Among them, the industry mainly adopts the reductive N-methylation reaction process of 2-imidazolidinone with formaldehyde, which is specifically divided into two types: formic acid method and hydrogenation method. Although the formic acid method is simple and low-cost, the presence of acid causes equipment corrosion and environmental pollution. In comparison, the hydrogenation method is a clean method that conforms to today's green and environmentally friendly production processes, but it still has shortcomings such as low efficiency, high cost, and harsh reaction conditions. Overall, the hydrogenation method has room for further optimization and improvement, and is gradually developing in a sustainable direction.

[0006] Therefore, it is very meaningful to explore a catalyst with high activity, high selectivity and high stability for the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone. Summary of the invention

[0007] To solve the above problems, the present invention provides a sulfur-doped activated carbon-supported palladium metal catalyst for synthesizing 1,3-dimethyl-2-imidazolidinone by hydrogenation, a preparation method thereof, and an application thereof in synthesizing 1,3-dimethyl-2-imidazolidinone by hydrogenation.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is described as follows.

[0009] In a first aspect, the present invention provides a method for preparing a sulfur-doped activated carbon-supported palladium metal catalyst for synthesizing 1,3-dimethyl-2-imidazolidinone by hydrogenation, comprising the following specific steps:

[0010] (1) dissolving a sulfur atom precursor in deionized water, adding completely dried activated carbon, stirring thoroughly for 6-12 hours, and then heating to 60-80° C. to evaporate the water to obtain a solid mixture A; the sulfur atom precursor is selected from at least one of Na2SO4, Na2S, NaHSO3, Na2SO3, Na2S2O3, K2SO4, K2S, KHSO3, K2SO3, K2S2O3, H2SO4, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, α-naphthalenesulfonic acid, β-naphthalenesulfonic acid, 2-mercaptoethanol, dimethyl sulfone, phenyl vinyl sulfone, and sodium dodecyl sulfate; the sulfur atom precursor and activated carbon are mixed according to the theoretical doping amount of sulfur atom y%=m S / (m S +m 活性炭 )×100%=2-10% feed, where m S It refers to the mass of S element contained in the added sulfur atom precursor;

[0011] (2) The solid mixture A is placed in a vacuum oven for drying; then placed in a tube furnace, calcined at 500-800° C. for 3-5 h in an inert atmosphere, and cooled to room temperature to obtain a sulfur-doped activated carbon carrier, which is denoted as CS. y ;

[0012] (3) adding a sulfur-doped activated carbon carrier to an appropriate amount of deionized water, stirring and dispersing it uniformly at room temperature (preferably stirring and dispersing it for 1-3 hours) to obtain a suspension B; adding a palladium metal precursor compound to an appropriate amount of deionized water, heating it to 60-80° C. and stirring it for 1-3 hours to obtain a solution C; then heating the suspension B to 60-80° C., adding the solution C dropwise to the suspension B, and immersing it for 3-5 hours; the suspension B and the solution C are mixed so that the theoretical loading amount of Pd is x%=m Pd / (m Pd +m 硫掺杂活性炭载体 )×100%=3-10% feed, where m Pd refers to the mass of Pd element contained in solution C, m 硫掺杂活性炭载体It refers to the mass of sulfur-doped activated carbon carrier contained in suspension B;

[0013] (4) After being fully impregnated in step (3), an appropriate amount of alkali solution is added to the suspension B, and the pH value of the suspension B is adjusted to 8-11, and then the suspension is allowed to stand for 1.5-2 hours; then the suspension is heated to 60-80° C., and an appropriate amount of an aqueous solution containing a liquid phase reducing agent is slowly added dropwise to the suspension B for full reduction; the suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is dried to obtain a sulfur-doped activated carbon-supported palladium metal catalyst, which is recorded as x% Pd / CS y .

[0014] Preferably, in step (1), the sulfur atom precursor is at least one of Na2SO4, Na2S, and NaHSO3, with Na2SO4 being most preferred.

[0015] Preferably, in step (2), y is 2-7, most preferably 5.

[0016] Preferably, in step (2), the drying conditions are: drying at 100-130° C. for 6-12 h.

[0017] Preferably, in step (2), the inert atmosphere is at least one of nitrogen, argon and helium.

[0018] Preferably, in step (2), the rate of heating to the calcination temperature is 1-5°C·min -1 The calcination temperature is 500-800°C, and the calcination time is 3-5h; more preferably, the heating rate is 3°C·min -1 The calcination temperature is 600℃ and the calcination time is 3h.

[0019] Preferably, in step (3), the palladium metal precursor compound is at least one of tetrachloropalladic acid (H2PdCl4), sodium tetrachloropalladate (Na2PdCl4), potassium tetrachloropalladate (K2PdCl4), palladium nitrate (Pd(NO3)2), and dichlorotetraamminepalladium (Pd(NH3)4Cl2).

[0020] Preferably, in step (3), when preparing solution C, in addition to adding the palladium metal precursor compound and deionized water, a dispersant is also added, wherein the dispersant is at least one of polyvinyl pyrrolidone and polyethylene glycol, and the mass amount of the dispersant is 5-10% of the mass amount of the sulfur-doped activated carbon carrier.

[0021] Preferably, in step (3), x is 5-10, most preferably 7.5.

[0022] Preferably, in step (4), the alkali solution is at least one of aqueous ammonia, aqueous sodium hydroxide solution, and aqueous potassium hydroxide solution.

[0023] Preferably, in step (4), the liquid phase reducing agent is at least one of sodium borohydride and hydrazine hydrate, and the molar ratio of the liquid phase reducing agent to the palladium element is 5-15:1, most preferably 10:1; and the reduction time is 1-2h.

[0024] Preferably, in step (4), the drying is performed by placing the filter cake in a vacuum oven and drying it at 100-130° C. for 6-12 hours.

[0025] In a second aspect, the present invention provides a sulfur-doped activated carbon-supported palladium metal catalyst for hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone, prepared according to the preparation method described in the first aspect.

[0026] In a third aspect, the present invention provides the use of the sulfur-doped activated carbon-supported palladium metal catalyst in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone.

[0027] The application includes the following specific steps: 2-imidazolidinone, deionized water, sulfur-doped activated carbon-supported palladium metal catalyst, and formaldehyde solution are sequentially added to a reaction kettle, and a continuous hydrogenation reaction is performed at 130-160° C., a hydrogen pressure of 1-5 MPa, and mechanical stirring to synthesize 1,3-dimethyl-2-imidazolidinone. The obtained reaction liquid is filtered, and the filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph is used to perform quantitative analysis of the target product.

[0028] Preferably, the mass feed ratio of the 2-imidazolidinone, deionized water, sulfur-doped activated carbon-supported palladium metal catalyst, and formaldehyde solution (37 wt.%) is 6:50:0.3:14.

[0029] Preferably, the reaction conditions are: reaction temperature of 140-160° C., and hydrogen pressure of 1-2 MPa; more preferably, the reaction temperature is 140° C., and hydrogen pressure is 1 MPa.

[0030] Preferably, the mechanical stirring rate is controlled at 700-1000 r / min -1 .

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention adopts a sulfur-doped activated carbon carrier prepared by an easy-to-implement method, so that sulfur species are effectively introduced into the activated carbon and exist stably. The defect sites and active sites formed on the carbon surface are conducive to the loading of metal nanoparticles and the activation of reactants. In addition, the carrier has excellent properties such as high specific area and rich pore structure, providing a larger platform for the reaction.

[0033] (2) The sulfur-doped activated carbon supported palladium metal catalyst of the present invention has a strong interaction between palladium and sulfur atoms, and the palladium nanoparticles are dispersed and anchored in the defect sites of the carrier, which produces a synergistic effect with the active sites on the surface of the carrier, thereby promoting the reaction. At the same time, the addition of the dispersant improves the dispersibility of the palladium nanoparticles.

[0034] (3) Compared with traditional catalysts, the catalyst of the present invention can make up for the shortcomings of low activity and complex preparation process. The catalyst of the present invention is applied to the reaction of synthesizing 1,3-dimethyl-2-imidazolidinone by hydrogenation, and exhibits excellent activity and high selectivity under mild conditions, shortens the reaction time, and has good catalytic stability, avoiding the use of organic solvents and acids, and practicing the concept of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a transmission electron microscope image of the catalyst 7.5% Pd / CS5 prepared in specific example 1 of the present invention;

[0036] Figure 2 It is the X-ray diffraction pattern of the catalyst 7.5% Pd / CS5 prepared in specific example 1 of the present invention. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described in more detail below in conjunction with embodiments, but the protection scope of the present invention is not limited to the following specific implementation methods.

[0038] Example 1

[0039] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0040] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0041] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0042] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water and stirred for 1 h at room temperature to obtain suspension B. 8.1 mL of tetrachloropalladic acid aqueous solution (Pd 0.02 g mL -1 ) was added into 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then, suspension B was heated to 70° C., and solution C was added dropwise into suspension B, and stirred and immersed for 5 h;

[0043] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 9, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.58g of sodium borohydride to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0044] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0045] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0046] Example 2

[0047] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0048] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0049] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0050] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.1746 g of sodium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0051] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 A potassium hydroxide aqueous solution is added to the suspension B, and the pH value of the suspension B is adjusted to 8, and then it is allowed to stand for 1.5 hours; then the temperature is raised to 70°C, and 10 mL of an aqueous solution containing 0.30 g of hydrazine hydrate is slowly added dropwise to the suspension B, and the reduction is carried out for 1 hour; the suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is placed in a vacuum oven and dried at 110°C for 9 hours to obtain a sulfur-doped activated carbon-supported palladium metal catalyst 3% Pd / CS5.

[0052] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0053] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0054] Example 3

[0055] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0056] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0057] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 in a helium atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0058] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.3296 g of potassium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0059] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add ammonia solution to suspension B, adjust the pH value of suspension B to 10, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.37g of sodium borohydride to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 5% Pd / CS5.

[0060] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0061] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0062] Example 4

[0063] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0064] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0065] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0066] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 1.2285 g of palladium nitrate (Pd 18.09 wt.%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0067] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 11, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 1.05g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 10% Pd / CS5.

[0068] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0069] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0070] Table 1 Effect of theoretical palladium loading on catalyst performance

[0071] Theoretical loading of palladium Conversion rate (%) Selectivity (%) Reaction time (h) Example 1 7.5% Pd >99.99 99.95 3.60 Example 2 3% Pd 98.47 99.02 6.91 Example 3 5% Pd 99.53 99.21 5.35 Example 4 10% Pd >99.99 99.87 3.42 Comparative Example 1 1% Pd 95.87 69.33 13.03

[0072] Example 5

[0073] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0074] (1) 0.4521 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h, and then heated to 70°C to evaporate the water to obtain a solid mixture A;

[0075] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 hours, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS2;

[0076] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.3818 g of dichlorotetraamminepalladium (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0077] (4) After sufficient impregnation in step (3), add 0.1 g mL -1Add potassium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 9, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.58g of sodium borohydride to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS2.

[0078] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0079] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0080] Example 6

[0081] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0082] (1) 0.6851 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h. The mixture was then heated to 70°C to evaporate the water to obtain a solid mixture A.

[0083] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 in a helium atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 hours, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS3;

[0084] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water and stirred for 1 h at room temperature to obtain suspension B. 8.1 mL of tetrachloropalladic acid aqueous solution (Pd 0.02 g mL -1) was added into 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then, suspension B was heated to 70° C., and solution C was added dropwise into suspension B, and stirred and immersed for 5 h;

[0085] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add ammonia solution to suspension B, adjust the pH value of suspension B to 8, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.77g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS3.

[0086] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0087] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0088] Example 7

[0089] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0090] (1) 0.9230 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h, and then heated to 70°C to evaporate the water to obtain a solid mixture A;

[0091] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1The temperature was raised to 600°C for calcination and maintained for 3 hours, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS4;

[0092] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.4576 g of sodium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0093] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 10, and then let it stand for 1.5 hours; then heat to 70°C, slowly add 10mL of aqueous solution containing 0.58g of sodium borohydride to suspension B, and reduce for 1 hour; cool and filter suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS4.

[0094] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0095] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0096] Example 8

[0097] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0098] (1) 1.4140 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h, and then heated to 70°C to evaporate the water to obtain a solid mixture A;

[0099] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 hours, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS6;

[0100] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.5077 g of potassium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0101] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 A potassium hydroxide aqueous solution is added to the suspension B, and the pH value of the suspension B is adjusted to 11, and then it is allowed to stand for 1.5 hours; then it is heated to 70°C, and 10 mL of an aqueous solution containing 0.77 g of hydrazine hydrate is slowly added dropwise to the suspension B, and reduced for 1 hour; the suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is placed in a vacuum oven and dried at 110°C for 9 hours to obtain a sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS6.

[0102] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0103] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0104] Example 9

[0105] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0106] (1) 1.6674 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h, and then heated to 70°C to evaporate the water to obtain a solid mixture A;

[0107] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 in a helium atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS7;

[0108] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.8965 g of palladium nitrate (Pd 18.09 wt.%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0109] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Ammonia solution was added to suspension B, the pH value of suspension B was adjusted to 9, and then it was allowed to stand for 1.5 hours; then the temperature was raised to 70°C, 10 mL of an aqueous solution containing 0.58 g of sodium borohydride was slowly added dropwise to suspension B, and reduced for 1 hour; suspension B was cooled and filtered, and the filter cake was repeatedly washed with deionized water until the pH of the filtrate was neutral; the filter cake was placed in a vacuum oven and dried at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS7.

[0110] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0111] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0112] Table 2 Effect of theoretical sulfur doping amount on catalyst performance

[0113] Theoretical doping amount of sulfur Conversion rate (%) Selectivity (%) Reaction time (h) Example 1 5％ >99.99 99.95 3.60 Example 5 2％ 99.82 99.31 6.35 Example 6 3％ 99.11 98.34 5.30 Example 7 4％ 98.34 99.46 4.31 Example 8 6％ >99.99 99.93 3.58 Example 9 7％ >99.99 99.24 3.47 Comparative Example 2 1％ 97.25 98.72 8.43 Comparative Example 3 0％ 92.74 88.65 13.08

[0114] Example 10

[0115] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0116] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0117] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 500°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS5;

[0118] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.3818 g of dichlorotetraamminepalladium (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0119] (4) After sufficient impregnation in step (3), add 0.1 g mL -1Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 8, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.77g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0120] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0121] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0122] Embodiment 11

[0123] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0124] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0125] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 700°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS5;

[0126] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water and stirred for 1 h at room temperature to obtain suspension B. 8.1 mL of tetrachloropalladic acid aqueous solution (Pd 0.02 g mL -1) was added into 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then, suspension B was heated to 70° C., and solution C was added dropwise into suspension B, and stirred and immersed for 5 h;

[0127] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 A potassium hydroxide aqueous solution is added to suspension B, and the pH value of suspension B is adjusted to 10, and then it is allowed to stand for 1.5 hours; then the temperature is raised to 70°C, and 10 mL of an aqueous solution containing 0.58 g of sodium borohydride is slowly added dropwise to suspension B, and reduced for 1 hour; suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is placed in a vacuum oven and dried at 110°C for 9 hours to obtain a sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0128] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0129] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0130] Example 12

[0131] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0132] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0133] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 in a helium atmosphere. -1The temperature was raised to 800°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS5;

[0134] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.4576 g of sodium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0135] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add ammonia solution to suspension B, adjust the pH value of suspension B to 11, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.77g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0136] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0137] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0138] Table 3 Effect of carrier calcination temperature on catalyst performance

[0139] Calcination temperature of the carrier Conversion rate (%) Selectivity (%) Reaction time (h) Example 1 600℃ >99.99 99.95 3.60 Example 10 500℃ 98.56 98.20 4.67 Embodiment 11 700℃ 99.35 99.23 3.51 Example 12 800℃ 97.38 98.29 4.18 Comparative Example 4 400℃ 97.62 90.14 9.03 Comparative Example 5 Uncalcined 98.30 99.27 13.08

[0140] Example 13

[0141] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0142] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0143] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0144] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.5077 g of potassium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.1 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0145] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 9, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.58g of sodium borohydride to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0146] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0147] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0148] Embodiment 14

[0149] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0150] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0151] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0152] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.8965 g of palladium nitrate (Pd 18.09 wt.%) was added to 20 mL of deionized water, and 0.2 g of polyethylene glycol (Mn800) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0153] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 A potassium hydroxide aqueous solution is added to suspension B, and the pH value of suspension B is adjusted to 8, and then it is allowed to stand for 1.5 hours; then the temperature is raised to 70°C, and 10 mL of an aqueous solution containing 0.77 g of hydrazine hydrate is slowly added dropwise to suspension B, and reduced for 1 hour; suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is placed in a vacuum oven and dried at 110°C for 9 hours to obtain a sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0154] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0155] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0156] Embodiment 15

[0157] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0158] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0159] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 in a helium atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0160] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.3818 g of dichlorotetramminepalladium (98%) was added to 20 mL of deionized water, and 0.1 g of polyethylene glycol (Mn800) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0161] (4) After sufficient impregnation in step (3), add 0.1 g mL -1Add ammonia solution to suspension B, adjust the pH value of suspension B to 10, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.58g of sodium borohydride to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0162] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0163] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0164] Table 4 Effect of dispersant on catalyst performance

[0165]

[0166]

[0167] Example 16

[0168] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0169] (1) 1.9715 g of Na2S·9H2O was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h. The mixture was then heated to 70°C to evaporate the water to obtain a solid mixture A.

[0170] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0171] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water and stirred for 1 h at room temperature to obtain suspension B. 8.1 mL of tetrachloropalladic acid aqueous solution (Pd 0.02 g mL -1 ) was added into 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then, suspension B was heated to 70° C., and solution C was added dropwise into suspension B, and stirred and immersed for 5 h;

[0172] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 11, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.77g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0173] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0174] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0175] Embodiment 17

[0176] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0177] (1) 0.8542 g of NaHSO3 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h, and then heated to 70°C to evaporate the water to obtain a solid mixture A;

[0178] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0179] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.4576 g of sodium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0180] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 A potassium hydroxide aqueous solution is added to suspension B, the pH value of suspension B is adjusted to 9, and then it is allowed to stand for 1.5 hours; then the temperature is raised to 70°C, 10 mL of an aqueous solution containing 0.58 g of sodium borohydride is slowly added dropwise to suspension B, and reduced for 1 hour; suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is placed in a vacuum oven and dried at 110°C for 9 hours to obtain a sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0181] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0182] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0183] Table 5 Effect of sulfur atom precursor on catalyst performance

[0184] Sulfur Atom Precursor Conversion rate (%) Selectivity (%) Reaction time (h) Example 1 <![CDATA[Na2SO4]]> >99.99 99.95 3.60 Example 16 <![CDATA[Na2S]]> >99.99 99.90 3.71 Embodiment 17 <![CDATA[NaHSO3]]> >99.99 99.28 5.07 Comparative Example 3 none 92.74 88.65 13.08

[0185] Embodiment 18

[0186] Example 18 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone at different reaction temperatures.

[0187] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 150°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in the pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0188] Embodiment 19

[0189] Example 19 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone at different reaction temperatures.

[0190] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 160°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0191] Embodiment 20

[0192] Example 20 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone under different reaction pressures.

[0193] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1.5MPa. When the pressure drops to 1.4MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0194] Embodiment 21

[0195] Example 21 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone under different reaction pressures.

[0196] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 2MPa. When the pressure drops to 1.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0197] Table 6 Effect of reaction conditions on the hydrogenation reaction of 1,3-dimethyl-2-imidazolidinone

[0198]

[0199]

[0200] Embodiment 22

[0201] Example 22 investigates the application performance of the catalyst prepared in Example 1 in the hydrogenation process for synthesizing 1,3-dimethyl-2-imidazolidinone.

[0202] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 , when the temperature is raised to 140°C, hydrogen is introduced until the pressure is 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is emptied, and the reaction solution is filtered by suction. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove moisture, a gas chromatograph (Agilent 7890B) is used to perform quantitative analysis of the target product. The catalyst after the reaction continues to be applied to the experiment, and 0.03g of fresh catalyst prepared in Example 1 is added before each feeding. The experimental conditions are the same, and the experimental results are shown in Table 7.

[0203] Table 7 Application performance of sulfur-doped activated carbon supported palladium metal catalyst

[0204] Number of reactions Conversion rate (%) Selectivity (%) Reaction time (h) 1 >99.99 99.78 3.60 2 >99.99 99.59 5.23 3 99.41 99.66 5.87 4 99.80 99.63 6.03 5 99.84 99.87 6.25 6 98.72 99.35 6.20 7 99.78 99.63 6.67 8 99.46 99.71 6.90 9 99.82 99.48 7.21 10 99.63 98.50 7.04

[0205] Comparative Example 1

[0206] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0207] (1) 1.1659 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h. The mixture was then heated to 70°C to evaporate the water to obtain a solid mixture A.

[0208] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0209] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water and stirred for 1 h at room temperature to obtain suspension B. 1.0 mL of tetrachloropalladic acid aqueous solution (Pd 0.02 g mL -1 ) was added into 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then, suspension B was heated to 70° C., and solution C was added dropwise into suspension B, and stirred and immersed for 5 h;

[0210] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Sodium hydroxide aqueous solution is added to suspension B, the pH value of suspension B is adjusted to 9, and then it is allowed to stand for 1.5 hours; then the temperature is raised to 70°C, 10 mL of aqueous solution containing 0.07 g of sodium borohydride is slowly added dropwise to suspension B, and reduced for 1 hour; suspension B is cooled and filtered, and the filter cake is repeatedly washed with deionized water until the pH of the filtrate is neutral; the filter cake is placed in a vacuum oven and dried at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 1% Pd / CS5.

[0211] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0212] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0213] Comparative Example 2

[0214] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0215] (1) 0.2238 g of Na2SO4 was dissolved in 75 mL of deionized water, 5 g of completely dried activated carbon (McLean, 200 mesh, powder) was added, and the mixture was stirred for 12 h. The mixture was then heated to 70°C to evaporate the water to obtain a solid mixture A.

[0216] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600 °C for calcination and maintained for 3 h, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS1;

[0217] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.4576 g of sodium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0218] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add potassium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 8, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.77g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS1.

[0219] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0220] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0221] Comparative Example 3

[0222] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0223] (1) Add 5 g of completely dried activated carbon (McLean, 200 mesh, powder) to 75 mL of deionized water, stir thoroughly for 12 h, and then heat to 70 °C to evaporate the water to obtain solid A;

[0224] (2) Solid A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 in a helium atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 hours, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS0;

[0225] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.5077 g of potassium tetrachloropalladate (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0226] (4) After sufficient impregnation in step (3), add 0.1 g mL -1Ammonia solution was added to suspension B, the pH value of suspension B was adjusted to 10, and then it was allowed to stand for 1.5 hours; then the temperature was raised to 70°C, 10 mL of an aqueous solution containing 0.58 g of sodium borohydride was slowly added dropwise to suspension B, and reduced for 1 hour; suspension B was cooled and filtered, and the filter cake was repeatedly washed with deionized water until the pH of the filtrate was neutral; the filter cake was placed in a vacuum oven and dried at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS0.

[0227] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0228] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0229] Comparative Example 4

[0230] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0231] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0232] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h. It was then placed in a tube furnace and heated at 3°C ​​min-1 under a nitrogen atmosphere. -1 The temperature was raised to 400°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain sulfur-doped activated carbon support CS5;

[0233] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.8965 g of palladium nitrate (Pd 18.09 wt.%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0234] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Add sodium hydroxide aqueous solution to suspension B, adjust the pH value of suspension B to 11, and then let it stand for 1.5 hours; then heat it to 70°C, slowly add 10mL of aqueous solution containing 0.77g of hydrazine hydrate to suspension B, and reduce it for 1 hour; cool and filter the suspension B, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; place the filter cake in a vacuum oven and dry it at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0235] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0236] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0237] Comparative Example 5

[0238] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0239] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0240] (2) The solid mixture A was placed in a vacuum oven and dried at 110° C. for 12 h to obtain an uncalcined sulfur-doped activated carbon support CS5. * ;

[0241] (3) 2 g of uncalcined sulfur-doped activated carbon carrier was added to 30 mL of deionized water, and the mixture was stirred and dispersed at room temperature for 1 h to obtain suspension B; 0.3818 g of dichlorotetraamminepalladium (98%) was added to 20 mL of deionized water, and 0.2 g of polyvinyl pyrrolidone (K16-18) was added, and the mixture was heated to 70° C. and stirred for 1 h to obtain solution C; then suspension B was heated to 70° C., and solution C was added dropwise to suspension B, and stirred and immersed for 5 h;

[0242] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Potassium hydroxide aqueous solution was added to suspension B, and the pH value of suspension B was adjusted to 9, and then it was allowed to stand for 1.5 hours; then it was heated to 70°C, and 10mL of aqueous solution containing 0.58g of sodium borohydride was slowly added dropwise to suspension B, and reduced for 1 hour; suspension B was cooled and filtered, and the filter cake was repeatedly washed with deionized water until the pH of the filtrate was neutral; the filter cake was placed in a vacuum oven and dried at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5 * .

[0243] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0244] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0245] Comparative Example 6

[0246] 1. Preparation of sulfur-doped activated carbon supported palladium metal catalyst:

[0247] (1) Dissolve 1.1659 g of Na2SO4 in 75 mL of deionized water, add 5 g of completely dried activated carbon (McLean, 200 mesh, powder), stir thoroughly for 12 h, and then heat to 70°C to evaporate the water to obtain a solid mixture A;

[0248] (2) The solid mixture A was placed in a vacuum oven and dried at 110°C for 12 h; then placed in a tube furnace and heated at 3°C ​​min-1 under an argon atmosphere. -1 The temperature was raised to 600°C for calcination and maintained for 3 h, and then cooled to room temperature to obtain the sulfur-doped activated carbon support CS5;

[0249] (3) 2 g of sulfur-doped activated carbon carrier was added to 30 mL of deionized water and stirred for 1 h at room temperature to obtain suspension B. 8.1 mL of tetrachloropalladic acid aqueous solution (Pd 0.02 g mL -1 ) was added into 20 mL of deionized water, heated to 70°C and stirred for 1 h to obtain solution C; then suspension B was heated to 70°C, solution C was added dropwise into suspension B, and stirred and immersed for 5 h;

[0250] (4) After sufficient impregnation in step (3), add 0.1 g mL -1 Ammonia solution was added to suspension B, the pH value of suspension B was adjusted to 8, and then it was allowed to stand for 1.5 hours; then the temperature was raised to 70°C, 10 mL of an aqueous solution containing 0.77 g of hydrazine hydrate was slowly added dropwise to suspension B, and reduced for 1 hour; suspension B was cooled and filtered, and the filter cake was repeatedly washed with deionized water until the pH of the filtrate was neutral; the filter cake was placed in a vacuum oven and dried at 110°C for 9 hours to obtain sulfur-doped activated carbon-supported palladium metal catalyst 7.5% Pd / CS5.

[0251] 2. Application of catalyst in the synthesis of 1,3-dimethyl-2-imidazolidinone by hydrogenation:

[0252] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0253] Comparative Example 7

[0254] Comparative Example 7 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone at different reaction temperatures.

[0255] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 120°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0256] Comparative Example 8

[0257] Comparative Example 8 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone at different reaction temperatures.

[0258] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1When the temperature rises to 130°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant change in pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0259] Comparative Example 9

[0260] Comparative Example 9 investigates the application of the catalyst prepared in Example 1 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone under different reaction pressures.

[0261] 12 g 2-imidazolidinone, 100 mL deionized water, 0.6 g sulfur-doped activated carbon-supported palladium metal catalyst, and 28 g formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the air tightness of the device). The mechanical stirring rate was set to 1000 r·min -1 When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 0.5MPa. When the pressure drops to 0.4MPa, hydrogen is added to 1MPa until there is no significant change in the pressure within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a sulfur-doped activated carbon-supported palladium metal catalyst. After the filtrate is distilled to remove water, a gas chromatograph (Agilent7890B) is used to quantitatively analyze the target product.

[0262] Comparative Example 10

[0263] Comparative Example 10 investigated the application of commercial 5% Pd / C catalyst in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone.

[0264] 12 g of 2-imidazolidinone, 100 mL of deionized water, 0.6 g of commercial 5% Pd / C catalyst (Huzhou Degong Chemical Co., Ltd.), and 28 g of formaldehyde solution (37 wt.%) were added to a 250 mL reactor (Yanzheng Instrument, YZQR-250 (M)). The gas in the reactor was replaced with nitrogen three times (pressurized to 1 MPa each time and maintained for 1 min to check the airtightness of the device). The mechanical stirring rate was set to 1000 r / min. -1When the temperature rises to 140°C, hydrogen is introduced until the pressure reaches 1MPa. When the pressure drops to 0.9MPa, hydrogen is added to 1MPa until there is no significant pressure change within half an hour, and the reaction is stopped. When the kettle temperature drops to room temperature, the pressure in the kettle is vented, and the reaction liquid is filtered. The filter cake is a commercial palladium carbon catalyst. After the filtrate is distilled to remove water, the target product is quantitatively analyzed by gas chromatograph (Agilent7890B).

[0265] Table 8 Catalytic performance of the catalyst prepared in Example 3 and the commercial 5% Pd / C catalyst

[0266]

[0267]

Claims

1. A method for preparing a sulfur-doped activated carbon-supported palladium metal catalyst for hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone, characterized in that: The preparation method comprises the following specific steps: (1) dissolving a sulfur atom precursor in deionized water, adding completely dried activated carbon, stirring thoroughly for 6-12 hours, and then heating to 60-80° C. to evaporate the water to obtain a solid mixture A; the sulfur atom precursor is selected from at least one of Na2SO4, Na2S, NaHSO3, Na2SO3, Na2S2O3, K2SO4, K2S, KHSO3, K2SO3, K2S2O3, H2SO4, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, α-naphthalenesulfonic acid, β-naphthalenesulfonic acid, 2-mercaptoethanol, dimethyl sulfone, phenyl vinyl sulfone, and sodium dodecyl sulfate; the sulfur atom precursor and activated carbon are mixed according to the theoretical doping amount of sulfur atom y%=m S / (m S +m 活性炭 )×100%=2-10% feed, where m S It refers to the mass of S element contained in the added sulfur atom precursor; (2) placing the solid mixture A in a vacuum oven to dry; then placing it in a tube furnace, calcining it at 500-800° C. for 3-5 hours under an inert atmosphere, and cooling it to room temperature to obtain a sulfur-doped activated carbon support; (3) adding a sulfur-doped activated carbon carrier to an appropriate amount of deionized water, stirring and dispersing the mixture evenly at room temperature (preferably stirring and dispersing for 1-3 hours) to obtain a suspension B; adding a palladium metal precursor compound to an appropriate amount of deionized water, heating the mixture to 60-80° C. and stirring the mixture for 1-3 hours to obtain a solution C; Then, the suspension B is heated to 60-80°C, and the solution C is added dropwise to the suspension B for 3-5 hours; the suspension B and the solution C are mixed so that the theoretical loading amount of Pd is x%=m Pd / (m Pd +m 硫掺杂活性炭载体 )×100%=3-10% feed, where m Pd refers to the mass of Pd element contained in solution C, m 硫掺杂活性炭载体 It refers to the mass of sulfur-doped activated carbon carrier contained in suspension B; (4) After being fully impregnated in step (3), add an appropriate amount of alkali solution to the suspension B, adjust the pH value of the suspension B to 8-11, and then stand for 1.5-2 hours; then heat to 60-80° C., slowly drop an appropriate amount of an aqueous solution containing a liquid phase reducing agent into the suspension B for full reduction; cool the suspension B, filter it, and repeatedly wash the filter cake with deionized water until the pH of the filtrate is neutral; dry the filter cake to obtain a sulfur-doped activated carbon-supported palladium metal catalyst.

2. The preparation method according to claim 1, characterized in that: In step (2), y is 2-7, preferably 5.

3. The preparation method according to claim 1, characterized in that: In step (2), the rate of heating to the calcination temperature is 1-5°C·min -1 The calcination temperature is 500-800°C, and the calcination time is 3-5h; more preferably, the heating rate is 3°C·min -1 The calcination temperature is 600℃ and the calcination time is 3h.

4. The preparation method according to claim 1, characterized in that: In step (3), the palladium metal precursor compound is at least one of tetrachloropalladic acid, sodium tetrachloropalladate, potassium tetrachloropalladate, palladium nitrate, and dichlorotetraamminepalladium.

5. The preparation method according to claim 1, characterized in that: In step (3), when preparing solution C, in addition to adding the palladium metal precursor compound and deionized water, a dispersant is also added, wherein the dispersant is at least one of polyvinyl pyrrolidone and polyethylene glycol, and the mass amount of the dispersant is 5-10% of the mass amount of the sulfur-doped activated carbon carrier.

6. The preparation method according to claim 1, characterized in that: In step (3), the x is 5-10, preferably 7.

5.

7. The preparation method according to claim 1, characterized in that: In step (4), the liquid phase reducing agent is at least one of sodium borohydride and hydrazine hydrate, and the molar ratio of the liquid phase reducing agent to the palladium element is 5-15:1; and the reduction time is 1-2h.

8. A sulfur-doped activated carbon-supported palladium metal catalyst for hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the sulfur-doped activated carbon-supported palladium metal catalyst as claimed in claim 8 in the hydrogenation synthesis of 1,3-dimethyl-2-imidazolidinone.

10. The use according to claim 9, characterized in that: The application comprises the following specific steps: adding 2-imidazolidinone, deionized water, a sulfur-doped activated carbon-supported palladium metal catalyst, and a formaldehyde solution into a reaction kettle in sequence, and performing a continuous hydrogenation reaction at 130-160° C., a hydrogen pressure of 1-5 MPa, and mechanical stirring to synthesize 1,3-dimethyl-2-imidazolidinone.

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