Catalyst for the preparation of dialkyl carbonates by coupling reaction of monohydric alcohol and CO2, its preparation and application, preparation of symmetrical dialkyl carbonates

Abstract

The present invention provides a catalyst for preparing dialkyl carbonates through the coupling reaction of a monohydric alcohol and CO2, a preparation method and application thereof, and a preparation method for symmetrical dialkyl carbonates, and relates to the technical field of organic synthesis. The catalyst of the present invention comprises an active component and a carrier; the active component is an oxide of an active metal; the active metal comprises cobalt, as well as gallium and / or indium; and the carrier comprises γ-Al2O3 or SiO2. The multiple components of the catalyst of the present invention interact with each other, which can effectively adjust the acidity and alkalinity of the catalyst. It is used for the "one-pot" reaction of a monohydric alcohol, carbon dioxide, and propargyl alcohol to prepare symmetrical dialkyl carbonates, and has high activity and high selectivity. The results of the examples show that the catalyst of the present invention has a conversion rate of 80 to 93% for monohydric alcohols and a selectivity for symmetrical dialkyl carbonates of 95 to 99%; the catalyst has good thermal stability and a long catalytic life, and its activity does not decrease significantly after continuous use for more than 360 hours.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a catalyst for preparing dialkyl carbonate by coupling reaction of monohydric alcohol and CO2, a preparation method and application thereof, and a preparation method of symmetrical dialkyl carbonate. Background Art

[0002] CO₂ is an environmentally friendly carbon-based feedstock characterized by abundant reserves, low cost, and recyclability. In organic synthesis, CO₂ can, to a certain extent, replace traditional CO and phosgene to produce various compounds and clean fuels through the formation of CN, CO, and C—C bonds and hydrogenation. Currently, industrial applications of CO₂ are limited, primarily in the production of urea (ammonia and CO₂), carbonates (epoxides and CO₂), polyurethanes (organic amines and CO₂), methanol (CO₂ and H₂), and salicylic acid (phenol and CO₂). This is primarily due to: 1) CO₂'s stability and difficulty in utilization; 2) complex catalytic systems, poor stability, and low efficiency; and 3) low chemical selectivity and economical efficiency of the reaction pathway. Currently, there are few reports on the efficient production of dialkyl carbonates by coupling CO₂ with monohydric alcohols. Although Zhang Qianxia et al. disclosed the preparation of dimethyl carbonate (DMC) by a "one-pot" reaction of 2-methyl-3-butyn-2-ol, methanol and CO2, the highest yield of DMC was only 37.3% (Zhang Qianxia et al., Multi-component series strategy to fix CO2 to prepare dimethyl carbonate and α-hydroxyketone, Science Bulletin, 2020, 65(31), 3429-3437). Summary of the Invention

[0003] The present invention provides a catalyst for preparing dialkyl carbonates through the coupling reaction of a monohydric alcohol and CO₂, a preparation method and application thereof, and a method for preparing symmetric dialkyl carbonates. The catalyst of the present invention is used to catalyze the three-component coupling reaction of a monohydric alcohol, CO₂, and propargyl alcohol to prepare symmetric dialkyl carbonates, exhibiting excellent catalytic activity and high product selectivity.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a catalyst for preparing dialkyl carbonate by coupling reaction of monohydric alcohol and CO2, characterized in that it comprises an active component and a carrier; the active component is an oxide of an active metal; the active metal comprises cobalt, gallium and / or indium; and the carrier comprises γ-Al2O3 or SiO2.

[0006] Preferably, the content of active metal in the catalyst is 0.5 to 20 wt%.

[0007] Preferably, the content of cobalt in the catalyst is 0.4-16 wt%, and the content of gallium and / or indium is 0.1-4%.

[0008] Preferably, the method for preparing a catalyst for preparing dialkyl carbonate by coupling reaction of monohydric alcohol and CO2 is characterized by comprising the following steps:

[0009] placing the carrier in a gallium nitrate and / or indium nitrate solution for a first impregnation, performing a first drying on the resulting impregnation system, and performing a first calcination on the resulting dried solid to form gallium and / or indium oxide on the carrier to obtain a first catalyst precursor;

[0010] placing the first catalyst precursor in a divalent cobalt metal salt solution for a second impregnation, performing a second drying on the resulting impregnation system, and performing a second calcination on the resulting dried solid to form cobalt oxide on the first catalyst precursor to obtain a second catalyst precursor;

[0011] The second catalyst precursor is mixed with a nitric acid solution and an H2O2 solution for modification, and the modified solid material is subjected to a third drying and a third calcination to obtain the catalyst for preparing dialkyl carbonate by the coupling reaction of monohydric alcohol and CO2.

[0012] Preferably, the first calcination is carried out in an air atmosphere, the temperature of the first calcination is 300-420° C., and the holding time is 2-5 hours;

[0013] The second calcination is carried out under nitrogen protection, the temperature of the second calcination is 500-540° C., and the holding time is 2-5 hours.

[0014] Preferably, the concentration of the nitric acid solution is 40-50wt%; the concentration of the H2O2 solution is 10-25wt%; the molar ratio of H2O2 in the H2O2 solution to HNO3 in the nitric acid solution is 1:(10-500); the molar ratio of H2O2 in the H2O2 solution to Co in the second catalyst precursor is 1:(5-300); and the modification time is 1-3h.

[0015] Preferably, the third calcination is carried out under nitrogen protection; the temperature of the third calcination is 440-460° C., and the holding time is 2-3 hours.

[0016] The present invention provides the use of the catalyst described in the above scheme or the catalyst prepared by the preparation method described in the above scheme in the coupling reaction of monohydric alcohol, CO2 and propargyl alcohol to prepare symmetrical dialkyl carbonate.

[0017] The present invention provides a method for preparing a symmetrical dialkyl carbonate, comprising the following steps: continuously introducing a monohydric alcohol having a structure shown in Formula 1 and a propargyl alcohol having a structure shown in Formula 2 into a fixed-bed reactor containing a catalyst, introducing CO2 gas into the fixed-bed reactor, and performing a coupling reaction to obtain a symmetrical dialkyl carbonate having a structure shown in Formula 3;

[0018] R 3 CH2OH Formula 1,

[0019] In formula 1 and formula 3, R 3 is hydrogen, alkyl or aromatic; in Formula 2, R 1 and R 2 are independently alkyl, alkenyl or phenyl, and R 1 and R 2 At least one of them is an alkyl group;

[0020] The catalyst is the catalyst described above or the catalyst prepared by the preparation method described in the above scheme;

[0021] The coupling reaction temperature is 100-180°C.

[0022] Preferably, the CO2 injection pressure is 1-6 MPa, and the mass space velocity of the monohydric alcohol is 0.05-2.0 h -1 ; The molar ratio of the monohydric alcohol to the propargyl alcohol is (1-4):1.

[0023] The present invention provides a catalyst for the production of dialkyl carbonates through the coupled reaction of a monohydric alcohol and CO2, comprising an active component and a support; the active component is an oxide of an active metal, including cobalt, gallium, and / or indium; and the support comprises γ-Al2O3 or SiO2. The catalyst's multiple components interact with each other, effectively regulating the catalyst's acidity and alkalinity. The catalyst exhibits high activity and selectivity for the one-pot reaction of a monohydric alcohol, carbon dioxide, and propargyl alcohol to produce symmetrical dialkyl carbonates. Results from the examples show that the catalyst achieves a conversion rate of 80-93% for monohydric alcohols and a selectivity of 95-99% for symmetrical dialkyl carbonates. The catalyst also exhibits excellent thermal stability and a long catalytic life, with no significant decrease in activity after continuous use for over 360 hours.

[0024] In addition, the catalyst of the present invention is used for the one-pot reaction of monohydric alcohol, carbon dioxide and propargyl alcohol to prepare symmetrical dialkyl carbonate. In addition to the symmetrical dialkyl carbonate, the main product also includes α-hydroxy ketone, which has high added value.

[0025] The present invention provides a method for preparing the catalyst, which has low operating conditions and temperature, simple preparation, low cost and good application prospects.

[0026] The invention provides a preparation method of symmetrical dialkyl carbonate, which uses a continuous flow reaction mode to achieve rapid reaction, high selectivity, quantitative conversion level and simple separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the fixed bed reactor of the present invention. DETAILED DESCRIPTION

[0028] The present invention provides a catalyst for preparing dialkyl carbonate by coupling reaction of monohydric alcohol and CO2, comprising an active component and a carrier; the active component is an oxide of an active metal; the active metal comprises cobalt, gallium and / or indium; and the carrier comprises γ-Al2O3 or SiO2.

[0029] In the present invention, when the active metals are cobalt and gallium, the active components are cobalt oxide and gallium oxide; similarly, when the active metals are cobalt and indium, the active components are cobalt oxide and indium oxide; when the active metals are cobalt, gallium and indium, the active components are cobalt oxide, gallium oxide and indium oxide.

[0030] In the present invention, the active metal content in the catalyst is preferably 0.5-20 wt%, more preferably 2-15 wt%, and even more preferably 5-10 wt%. The cobalt content in the catalyst is preferably 0.4-16 wt%, more preferably 2-14%, and even more preferably 4-8 wt%. The gallium and / or indium content is preferably 0.1-4%, more preferably 1-3%, and even more preferably 1.5-2.5%.

[0031] The catalyst of the present invention has multiple components that interact with each other and can effectively adjust the acidity and alkalinity of the catalyst. It is used for the "one-pot" reaction of monohydric alcohol, carbon dioxide and propargyl alcohol to prepare symmetrical dialkyl carbonate, and has high activity and high selectivity.

[0032] The present invention provides a method for preparing a catalyst for preparing dialkyl carbonate by coupling reaction of monohydric alcohol and CO2 as described in the above scheme, comprising the following steps:

[0033] placing the carrier in a gallium nitrate and / or indium nitrate solution for a first impregnation, performing a first drying on the resulting impregnation system, and performing a first calcination on the resulting dried solid to form gallium and / or indium oxide on the carrier to obtain a first catalyst precursor;

[0034] placing the first catalyst precursor in a divalent cobalt metal salt solution for a second impregnation, performing a second drying on the resulting impregnation system, and performing a second calcination on the resulting dried solid to form cobalt oxide on the first catalyst precursor to obtain a second catalyst precursor;

[0035] The second catalyst precursor is mixed with a nitric acid solution and an H2O2 solution for modification, and the modified solid material is subjected to a third drying and a third calcination to obtain the catalyst for preparing dialkyl carbonate by the coupling reaction of monohydric alcohol and CO2.

[0036] In the present invention, unless otherwise specified, all raw materials used are commercially available products well known in the art.

[0037] The present invention places the carrier in a gallium nitrate and / or indium nitrate solution for a first impregnation, performs a first drying on the obtained impregnation system, and performs a first calcination on the obtained dry solid to form gallium and / or indium oxides on the carrier to obtain a first catalyst precursor.

[0038] In the present invention, the particle size of the carrier is preferably 15 to 300 nm, more preferably 50 to 250 nm, and even more preferably 100 to 150 nm.

[0039] In the present invention, when the active component is cobalt-gallium oxide, a gallium nitrate solution is used; when the active component is cobalt-indium oxide, an indium nitrate solution is used; when the active component is cobalt-gallium-indium oxide, a gallium nitrate and indium nitrate solution is used. In the present invention, when a gallium nitrate or indium nitrate solution is used, the concentration of gallium or indium in the gallium nitrate or indium nitrate solution is preferably 0.01 to 0.05 g·mL -1 , more preferably 0.02 to 0.04 g·mL -1 When the solution is gallium nitrate and indium nitrate, the concentration of gallium in the solution is preferably 0.01 to 0.03 g·mL -1 The concentration of indium is preferably 0.01 to 0.03 g·mL -1 .

[0040] In the present invention, the amount of the gallium nitrate and / or indium nitrate solution is determined according to the gallium and / or indium content in the final catalyst. In the present invention, the gallium nitrate and / or indium nitrate solution is preferably added to a container containing the carrier, stirred evenly, and then the first impregnation is performed.

[0041] In the present invention, the first immersion time is preferably 2 to 6 hours, more preferably 3 to 5 hours; the first immersion is preferably performed under static conditions. In the present invention, the first drying temperature is preferably 90 to 150°C, more preferably 100 to 140°C, and even more preferably 120 to 130°C; the present invention has no particular requirements for the first drying time, preferably until the surface of the solid material is completely dry.

[0042] After the first drying is completed, the obtained solid material is preferably ground and then subjected to a first roasting.

[0043] In the present invention, the first calcination is preferably performed in an air atmosphere; the first calcination temperature is preferably 300-420°C, more preferably 320-400°C, and even more preferably 340-380°C; and the holding time is preferably 2-5 hours, more preferably 3-4 hours. During the first calcination process, the gallium nitrate and / or indium nitrate decompose into gallium and / or indium oxides.

[0044] After obtaining the first catalyst precursor, the present invention places the first catalyst precursor in a divalent cobalt metal salt solution for a second impregnation, performs a second drying on the obtained impregnation system, and performs a second calcination on the obtained dry solid to form cobalt oxide on the first catalyst precursor to obtain a second catalyst precursor.

[0045] In the present invention, the divalent cobalt metal salt solution is preferably a cobalt nitrate solution or a cobalt acetate solution; the concentration of the divalent cobalt metal salt solution is preferably 0.01 to 0.08 g·mL -1 , more preferably 0.02 to 0.06 g·mL -1 , more preferably 0.04 to 0.05 g·mL -1 In the present invention, the amount of the divalent cobalt metal salt solution is determined according to the cobalt content in the final catalyst.

[0046] In the present invention, the divalent cobalt metal salt solution is preferably added to the first catalyst precursor, stirred evenly, and then the second impregnation is performed.

[0047] In the present invention, the second immersion time is preferably 2 to 8 hours, more preferably 4 to 6 hours, and even more preferably 5 hours; the second immersion is preferably performed under static conditions. In the present invention, the second drying temperature is preferably 90 to 150°C, more preferably 100 to 140°C, and even more preferably 120 to 130°C; the present invention has no particular requirements for the second drying time, preferably until the surface of the solid material is completely dry.

[0048] After the second drying is completed, the obtained solid material is preferably ground and then subjected to a second roasting.

[0049] In the present invention, the second calcination is preferably carried out under nitrogen protection; the temperature of the second calcination is preferably 500-540°C, more preferably 520-530°C; and the holding time of the second calcination is preferably 2-5 hours, more preferably 3-4 hours. The second calcination under nitrogen protection can maintain the valence of cobalt and prevent the effect of calcination in an air atmosphere on the valence of cobalt. After the second calcination, cobalt oxide is formed on the first catalyst precursor, obtaining a second catalyst precursor.

[0050] After obtaining the second catalyst precursor, the present invention mixes the second catalyst precursor with a nitric acid solution and an H2O2 solution for modification, and performs a third drying and a third calcination on the modified solid matter to obtain the catalyst for preparing dialkyl carbonate by the coupling reaction of monohydric alcohol and CO2.

[0051] In the present invention, the concentration of the nitric acid solution is preferably 40-50wt%, more preferably 42-48wt%, and further preferably 44-46wt%; the molar ratio of H2O2 in the H2O2 solution to HNO3 in the nitric acid solution is preferably 1:(10-500), more preferably 1:(100-400), and further preferably 1:(200-300); the concentration of the H2O2 solution is preferably 10-25wt%, more preferably 13-22wt%, and further preferably 15-20wt%; the molar ratio of H2O2 in the H2O2 solution to Co in the second catalyst precursor is 1:(5-300), more preferably 1:(100-250), and further preferably 1:(160-220). In the present invention, the modification time is preferably 1-3h, more preferably 1.5-2.5h, and further preferably 2h. In the present invention, the modification is preferably carried out under static conditions. In the modification process of the present invention, a strong acid environment is used to adjust the valence state of part of the cobalt oxide, and the surface properties of the catalyst can also be adjusted and metal oxide oxygen vacancies can be produced to improve the activity of the catalyst. In the present invention, the temperature of the third drying is preferably 120-150°C, more preferably 130-140°C; the time of the third drying is preferably 1-3h, more preferably 1.5-2.5h. In the present invention, the third calcination is preferably carried out under nitrogen protection; the temperature of the third calcination is preferably 440-460°C, more preferably 445-455°C, and further preferably 450°C; the holding time is preferably 2-3h, more preferably 2.5h. In the present invention, the role of the third calcination is to treat the nitrate species formed in the oxidation process of hydrogen peroxide and concentrated nitric acid, so that it decomposes into the corresponding valence states (Co III ) in the form of metal oxides.

[0052] The present invention provides the use of the catalyst described in the above scheme or the catalyst prepared by the preparation method described in the above scheme in the coupling reaction of monohydric alcohol, CO2 and propargyl alcohol to prepare symmetrical dialkyl carbonate.

[0053] The present invention provides a method for preparing a symmetrical dialkyl carbonate, comprising the following steps: continuously introducing a monohydric alcohol having a structure shown in Formula 1 and a propargyl alcohol having a structure shown in Formula 2 into a fixed-bed reactor containing a catalyst, introducing CO2 gas into the fixed-bed reactor, and performing a coupling reaction to obtain a symmetrical dialkyl carbonate having a structure shown in Formula 3;

[0054] R3 CH2OH Formula 1,

[0055] In formula 1 and formula 3, R 3 is hydrogen, alkyl or aromatic; in Formula 2, R 1 and R 2 are independently alkyl, alkenyl or phenyl, and R 1 and R 2 At least one of them is an alkyl group;

[0056] The catalyst is the catalyst described in the above scheme or the catalyst prepared by the preparation method described in the above scheme;

[0057] The coupling reaction temperature is 100-180°C.

[0058] In Formula 1 and Formula 3 of the present invention, the R 3 is hydrogen, an alkyl group or an aromatic group; the alkyl group is preferably a linear alkyl group or a cycloalkyl group, and the number of carbon atoms of the linear alkyl group is preferably 1 to 22, more preferably 1 to 15, and further preferably 1 to 10; the number of carbon atoms of the cycloalkyl group is preferably 3 to 10, more preferably 4 to 8; in the embodiment of the present invention, it is specifically a cyclohexyl group; the aromatic group is preferably a benzyl group.

[0059] In Formula 2 of the present invention, the R 1 and R 2 are independently alkyl, alkenyl or phenyl, and R 1 and R 2 At least one of them is an alkyl group; the alkyl group is preferably a straight-chain alkyl group, more preferably a straight-chain alkyl group with 1 to 10 carbon atoms, and further preferably a straight-chain alkyl group with 1 to 5 carbon atoms, such as methyl, ethyl, and butyl; the alkenyl group preferably has 2 to 5 carbon atoms, and is more preferably an allyl group.

[0060] The present invention has no special requirements for the fixed bed reactor, and a fixed bed reactor well known in the art can be used. The structural diagram of the fixed bed reactor used in the present invention is shown in FIG. Figure 1 In the present invention, the catalyst is preferably placed in the constant temperature section of the fixed bed reactor. In the present invention, the particle size of the catalyst is preferably 10 to 80 meshes.

[0061] In the present invention, the mass space velocity of the monohydric alcohol is preferably 0.05 to 2.0 h -1 , more preferably 0.1 to 1.8 h -1 , more preferably 0.5 to 1.5 h, and even more preferably 1 to 1.2 h -1The molar ratio of the monohydric alcohol to the propargyl alcohol is preferably (1-4):1, more preferably (2-3):1. In the present invention, the monohydric alcohol and the propargyl alcohol are preferably introduced into the fixed bed reactor in the form of a liquid mixture; the liquid mixture is preferably obtained by mixing the monohydric alcohol, the propargyl alcohol, and a reaction medium. The reaction medium is preferably acetonitrile or N,N-dimethylacetamide (DMF); the molar concentration of the monohydric alcohol in the liquid mixture is preferably 1-8 mol / L, more preferably 3-6 mol / L.

[0062] In the present invention, the CO2 injection pressure is preferably 1-6 MPa, more preferably 2-5 MPa, and further preferably 3-4 MPa. In the present invention, the coupling reaction temperature is preferably 120-160°C, more preferably 130-150°C.

[0063] In the present invention, the equation for the reaction of monohydric alcohol, propargyl alcohol and CO2 is as follows:

[0064]

[0065] The present invention uses a continuous flow reaction mode to achieve rapid reaction, high selectivity, quantitative conversion level, and simple separation.

[0066] The catalyst for preparing dialkyl carbonate by coupling reaction of monohydric alcohol and CO2, its preparation method and application, and the preparation method of symmetric dialkyl carbonate provided by the present invention are described in detail below with reference to the examples. However, they should not be construed as limiting the scope of protection of the present invention.

[0067] Example 1

[0068] Prepare metal cation concentration to 0.025 g·mL -1 The metal solution was added to 10 mL of gallium nitrate solution in batches with continuous stirring until uniform. The mixture was allowed to soak for 5 hours and then dried at 120°C for 6 hours. The resulting solid was ground and calcined at 400°C in air for 5 hours to obtain the first catalyst precursor, Ga2O3 / γ-Al2O3.

[0069] Prepare metal cation concentration to 0.05 g·mL -1 10 mL of cobalt (II) nitrate solution was added to the above catalyst precursor Ga2O3 / γ-Al2O3 in batches and stirred to mix evenly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-Ga2O3 / γ-Al2O3.

[0070] To the second catalyst precursor CoO-Ga2O3 / γ-Al2O3, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.002 mL H2O2 (mass concentration 20 wt%) were added, respectively, where the molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -Ga2O3 / γ-Al2O3 (x=1.002), referred to as Co / Ga / Al.

[0071] Application Example 1

[0072] The catalyst of Example 1 was tableted and crushed, and 5 g of 40 mesh particles were taken and filled into the constant temperature section of the fixed bed reactor, and the rest of the reactor was filled with quartz sand. DMF was used as the reaction medium, and n-butanol (molar concentration 3 mol / L) and propargyl alcohol (R 1 =R 2 =Me) (molar concentration 2mol / L) mixed liquid material, using an infusion pump to continuously enter the reactor, carbon dioxide enters the system in gaseous form. The pressure is 3MPa, the reaction temperature is 120℃, and the mass space velocity of n-butanol is 0.55h -1 . Sampling and analysis were performed every 12 hours during the reaction, and the average value of the analysis results of three samples at different times was taken as the representative experimental value under each condition. Gas chromatography analysis showed that the conversion rate of n-butanol was 85%, the yield of di-n-butyl carbonate was 83.5%, and the yield of α-hydroxy ketone was 84.2%. After continuous use for 360 hours, the conversion rate of n-butanol was 82.3%, the yield of di-n-butyl carbonate was 79.6%, and the yield of α-hydroxy ketone was 81.2%, indicating that the catalyst of the present invention has good stability and a long catalytic life.

[0073] Application Examples 2 to 7

[0074] The catalyst of Example 1 was used, and the application steps were the same as those of Example 1. The specific reaction conditions are shown in Table 1.

[0075] Comparative Example 1

[0076] The only difference from Application Example 1 is that no catalyst is used and only quartz sand is filled. The specific reaction conditions are shown in Table 1.

[0077] Comparative Example 2

[0078] Reference 1 (Science Bulletin 2020, 65, 3429.) reported the results: ZnI2 and DBU catalysts.

[0079] Comparative Example 3

[0080] Reference 2 (Journal of Fuel Chemistry and Technology, 2023, 51, 304) reported the results: silver sulfadiazine and DBU catalyst.

[0081] The reaction conditions and results of the application examples and comparative examples are shown in Table 1.

[0082] Table 1 Reaction conditions and results of application examples and comparative examples

[0083]

[0084]

[0085]

[0086] Note: In Table 1, the molar ratio is the molar ratio of monohydric alcohol to propargyl alcohol.

[0087] As shown in Table 1, the catalyst of the present invention is used to catalyze the three-component coupling reaction of monohydric alcohol, CO2, and propargyl alcohol to prepare symmetrical dialkyl carbonates. The conversion rate of the monohydric alcohol is 80-93%, and the selectivity of the symmetrical dialkyl carbonate is 95-99%. It has the advantages of good catalytic activity and high product selectivity.

[0088] Example 2

[0089] Prepared with a gallium ion concentration of 0.025 g·mL -1 and indium ion concentration of 0.025 g·mL -1 The mixed metal solution was added to SiO2 (10 g, 20 nm particle size) in batches with continuous stirring until uniform. The mixture was immersed for 5 h and then dried at 120°C for 6 h. The resulting solid was ground and calcined at 400°C in air for 5 h to obtain the first catalyst precursor Ga2O3-In2O3 / SiO2.

[0090] Prepare metal cation concentration to 0.05 g·mL -1 10 mL of cobalt (II) nitrate solution was added to the catalyst precursor Ga2O3-In2O3 / SiO2 in batches and stirred to mix thoroughly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-Ga2O3-In2O3 / SiO2.

[0091] To the second catalyst precursor CoO-Ga2O3-In2O3 / SiO2, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.002 mL H2O2 (mass concentration 20 wt%) were added, respectively. The molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -Ga2O3-In2O3 / SiO2 (x=1.002), abbreviated as Co / Ga / In / Si.

[0092] Example 3

[0093] Prepare metal cation concentration to 0.025 g·mL -1 The metal solution was added to γ-Al2O3 (10 g, particle size 120 nm) in batches with continuous stirring until uniform. The mixture was impregnated for 5 hours and then dried at 120°C for 6 hours. The resulting solid was ground and calcined at 400°C in air for 5 hours to obtain the first catalyst precursor In2O3 / γ-Al2O3.

[0094] Prepare metal cation concentration to 0.11 g·mL -1 10 mL of cobalt(II) nitrate solution was added to the above catalyst precursor In2O3 / γ-Al2O3 in batches and stirred to mix evenly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-In2O3 / γ-Al2O3.

[0095] To the second catalyst precursor CoO-In2O3 / γ-Al2O3, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.002 mL H2O2 (mass concentration 20 wt%) were added, respectively. The molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -In2O3 / γ-Al2O3 (x=1.002), abbreviated as Co / In / Al.

[0096] Example 4

[0097] Prepared with a gallium ion concentration of 0.079 g·mL -1 and indium ion concentration of 0.02 g·mL -1The mixed metal solution was added to SiO2-γ-Al2O3 (10 g, particle size 120 nm) in batches with continuous stirring until uniform. The mixture was immersed for 5 hours and then dried at 120°C for 6 hours. The resulting solid was ground and calcined at 400°C in air for 5 hours to obtain the first catalyst precursor Ga2O3-In2O3 / γ-Al2O3.

[0098] Prepare metal cation concentration to 0.092 g·mL -1 10 mL of cobalt (II) nitrate solution was added to the catalyst precursor Ga2O3-In2O3 / γ-Al2O3 in batches and stirred to mix thoroughly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-Ga2O3-In2O3 / γ-Al2O3.

[0099] To the second catalyst precursor CoO-Ga2O3-In2O3 / γ-Al2O3, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.002 mL H2O2 (mass concentration 20 wt%) were added, wherein the molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -Ga2O3-In2O3 / γ-Al2O3 (x=1.002), referred to as Co / Ga / In / Al.

[0100] Example 5

[0101] Prepare metal cation concentration to 0.025 g·mL -1 The metal solution was added to 10 mL of gallium nitrate solution in batches with continuous stirring until uniform. The mixture was allowed to soak for 5 hours and then dried at 120°C for 6 hours. The resulting solid was ground and calcined at 400°C in air for 5 hours to obtain the first catalyst precursor, Ga2O3 / γ-Al2O3.

[0102] Prepare metal cation concentration to 0.05 g·mL -1 10 mL of cobalt (II) nitrate solution was added to the above catalyst precursor Ga2O3 / γ-Al2O3 in batches and stirred to mix evenly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-Ga2O3 / γ-Al2O3.

[0103] To the second catalyst precursor CoO-Ga2O3 / γ-Al2O3, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.006 mL H2O2 (mass concentration 20 wt%) were added, respectively. The molar ratio of H2O2 to HNO3 was 1:104, and the molar ratio of H2O2 to Co was 3:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in a nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -Ga2O3 / γ-Al2O3 (x=1.002), referred to as Co / Ga / Al.

[0104] Example 6

[0105] Prepare metal cation concentration to 0.057 g·mL -1 The metal solution was added to SiO2 (10 g, 20 nm particle size) in batches with continuous stirring until uniform. The mixture was allowed to soak for 5 h and then dried at 120°C for 6 h. The resulting solid was ground and calcined at 400°C in air for 5 h to obtain the first catalyst precursor, Ga2O3 / SiO2.

[0106] Prepare metal cation concentration to 0.167 g·mL -1 10 mL of cobalt (II) nitrate solution was added to the catalyst precursor Ga2O3 / SiO2 in batches and stirred to mix evenly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-Ga2O3 / SiO2.

[0107] To the second catalyst precursor CoO-Ga2O3 / SiO2, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.002 mL H2O2 (mass concentration 20 wt%) were added, respectively. The molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -Ga2O3 / SiO2 (x=1.002), abbreviated as Co / Ga / Si.

[0108] Example 7

[0109] Prepare metal cation concentration to 0.035 g·mL -1The metal solution was added to SiO2 (10 g, 20 nm particle size) in batches with continuous stirring until uniform. The mixture was impregnated for 5 h and then dried at 120°C for 6 h. The resulting solid was ground and calcined at 400°C in air for 5 h to obtain the first catalyst precursor, In2O3 / SiO2.

[0110] Prepare metal cation concentration to 0.24 g·mL -1 10 mL of cobalt (II) nitrate solution was added to the above catalyst precursor In2O3 / SiO2 in batches and stirred to mix evenly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under a nitrogen atmosphere for 5 hours to obtain the second catalyst precursor CoO-In2O3 / SiO2.

[0111] To the second catalyst precursor CoO-In2O3 / SiO2, 0.5 mL HNO3 (mass concentration 40 wt%) and 0.002 mL H2O2 (mass concentration 20 wt%) were added, respectively. The molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. Mix well and let it stand for 2 hours. Then bake at 120 ° C for 3 hours and calcine at 440 ° C in nitrogen atmosphere for 3 hours. The obtained solid material was ground to obtain the active catalyst CoO x -In2O3 / SiO2 (x=1.002), abbreviated as Co / In / Si.

[0112] Application Examples 7-12

[0113] The only difference from Application Example 1 is that the catalyst of Example 1 is replaced by the catalysts of Examples 2 to 7. The catalytic activities exhibited by different catalyst types are shown in Table 2.

[0114] Comparative Example 4

[0115] Preparation of Co / Al catalyst.

[0116] Prepare metal cation concentration to 0.11 g·mL -1 10 mL of cobalt (II) nitrate solution was added to γ-Al2O3 (10 g, particle size 120 nm) in batches. The mixture was stirred and mixed thoroughly. The mixture was allowed to stand for 5 hours and then baked at 120°C for 10 hours. The resulting solid was ground and calcined at 500°C under nitrogen atmosphere for 5 hours to obtain the catalyst precursor CoO / γ-Al2O3.

[0117] 0.5 mL of HNO3 (40 wt%) and 0.002 mL of H2O2 (20 wt%) were added to the precursor CoO / γ-Al2O3, respectively. The molar ratio of H2O2 to HNO3 was 1:313, and the molar ratio of H2O2 to Co was 1:219. The mixture was mixed evenly and allowed to stand for 2 hours. It was then baked at 120°C for 3 hours and calcined at 440°C under nitrogen atmosphere for 3 hours. The resulting solid material was ground to obtain the active catalyst CoO x / γ-Al2O3 (x=1.002), abbreviated as Co / Al.

[0118] Catalytic experiments were carried out using the Co / Al catalyst according to the steps of Application Example 1. The results are shown in Table 2.

[0119] Table 2 Reaction conditions and results of application examples and comparative examples

[0120]

[0121]

[0122] Reaction conditions: molar ratio of monohydric alcohol to propargyl alcohol: 3:2, molar concentration of monohydric alcohol in DMF: 3 mol / L; reaction pressure: 3 MPa; temperature: 120°C; mass space velocity of n-butanol: 0.55 h -1 .

[0123] As can be seen from the results in Table 2, the different types of catalysts of the present invention are used to catalyze the three-component coupling reaction of monohydric alcohol, CO2 and propargyl alcohol to prepare symmetrical dialkyl carbonates, and all show good catalytic activity and product selectivity. The interaction between different metals and with the support helps to effectively regulate the acid-base properties of the cobalt site, thereby helping to obtain high activity and high selectivity.

[0124] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. Use of a catalyst in the coupling reaction of a monohydric alcohol, CO2 and propargyl alcohol to prepare a symmetrical dialkyl carbonate, characterized in that: The catalyst comprises an active component and a carrier; the active component is an oxide of an active metal; the active metal comprises cobalt, gallium and / or indium; and the carrier comprises γ-Al2O3 or SiO2.

2. The use according to claim 1, characterized in that The content of active metal in the catalyst is 0.5-20 wt %.

3. The use according to claim 1, characterized in that The content of cobalt in the catalyst is 0.4-16 wt %, and the content of gallium and / or indium is 0.1-4%.

4. The use according to any one of claims 1 to 3, characterized in that The preparation method of the catalyst comprises the following steps: placing the carrier in a gallium nitrate and / or indium nitrate solution for a first impregnation, performing a first drying on the resulting impregnation system, and performing a first calcination on the resulting dried solid to form gallium and / or indium oxide on the carrier to obtain a first catalyst precursor; placing the first catalyst precursor in a divalent cobalt metal salt solution for a second impregnation, performing a second drying on the resulting impregnation system, and performing a second calcination on the resulting dried solid to form cobalt oxide on the first catalyst precursor to obtain a second catalyst precursor; The second catalyst precursor is mixed with a nitric acid solution and an H2O2 solution for modification, and the modified solid material is subjected to a third drying and a third calcination to obtain the catalyst.

5. The use according to claim 4, characterized in that The first calcination is carried out in an air atmosphere at a temperature of 300-420° C. and a holding time of 2-5 hours; The second calcination is carried out under nitrogen protection, the temperature of the second calcination is 500-540° C., and the holding time is 2-5 hours.

6. The use according to claim 4, characterized in that The concentration of the nitric acid solution is 40~50wt%; the concentration of the H2O2 solution is 10~25wt%, the molar ratio of H2O2 in the H2O2 solution to HNO3 in the nitric acid solution is 1:(10~500); the molar ratio of H2O2 in the H2O2 solution to Co in the second catalyst precursor is 1:(5~300); and the modification time is 1~3h.

7. The use according to claim 4, characterized in that The third calcination is carried out under nitrogen protection; the temperature of the third calcination is 440-460° C., and the holding time is 2-3 hours.

8. A method for preparing a symmetrical dialkyl carbonate, characterized in that: The method comprises the following steps: continuously introducing a monohydric alcohol having a structure shown in Formula 1 and a propargyl alcohol having a structure shown in Formula 2 into a fixed bed reactor containing a catalyst, introducing CO2 gas into the fixed bed reactor, and performing a coupling reaction to obtain a symmetrical dialkyl carbonate having a structure shown in Formula 3; R 3 CH2OH Formula 1, Formula 2, Formula 3; In formula 1 and formula 3, R 3 is hydrogen, alkyl or aromatic; in Formula 2, R 1 and R 2 are independently alkyl, alkenyl or phenyl, and R 1 and R 2 At least one of them is an alkyl group; The catalyst comprises an active component and a carrier; the active component is an oxide of an active metal; the active metal comprises cobalt, gallium and / or indium; the carrier comprises γ-Al2O3 or SiO2; The coupling reaction temperature is 100-180°C.

9. The preparation method according to claim 8, characterized in that The CO2 injection pressure is 1~6MPa, and the mass space velocity of the monohydric alcohol is 0.05~2.0h -1 ; The molar ratio of the monohydric alcohol to the propargyl alcohol is (1~4):

1.

10. The preparation method according to claim 8, characterized in that The content of active metal in the catalyst is 0.5-20 wt %.

11. The preparation method according to claim 8, characterized in that The content of cobalt in the catalyst is 0.4-16 wt %, and the content of gallium and / or indium is 0.1-4%.

12. The preparation method according to claim 8, 10 or 11, characterized in that: The preparation method of the catalyst comprises the following steps: placing the carrier in a gallium nitrate and / or indium nitrate solution for a first impregnation, performing a first drying on the resulting impregnation system, and performing a first calcination on the resulting dried solid to form gallium and / or indium oxide on the carrier to obtain a first catalyst precursor; placing the first catalyst precursor in a divalent cobalt metal salt solution for a second impregnation, performing a second drying on the resulting impregnation system, and performing a second calcination on the resulting dried solid to form cobalt oxide on the first catalyst precursor to obtain a second catalyst precursor; The second catalyst precursor is mixed with a nitric acid solution and an H2O2 solution for modification, and the modified solid material is subjected to a third drying and a third calcination to obtain the catalyst.

13. The preparation method according to claim 12, characterized in that The first calcination is carried out in an air atmosphere at a temperature of 300-420° C. and a holding time of 2-5 hours; The second calcination is carried out under nitrogen protection, the temperature of the second calcination is 500-540° C., and the holding time is 2-5 hours.

14. The preparation method according to claim 12, characterized in that The concentration of the nitric acid solution is 40~50wt%; the concentration of the H2O2 solution is 10~25wt%, the molar ratio of H2O2 in the H2O2 solution to HNO3 in the nitric acid solution is 1:(10~500); the molar ratio of H2O2 in the H2O2 solution to Co in the second catalyst precursor is 1:(5~300); and the modification time is 1~3h.

15. The preparation method according to claim 12, characterized in that The third calcination is carried out under nitrogen protection; the temperature of the third calcination is 440-460° C., and the holding time is 2-3 hours.

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