Manganese-based composite monatomic catalyst and method for preparing acetone through low-temperature oxidation of propane

Abstract

The manganese-based composite catalyst takes manganese as an active component, at least one of iron, cobalt, copper and nickel as a first auxiliary agent, at least one of carbon and nitrogen elements as a second auxiliary agent, and the manganese-based composite monatomic catalyst is prepared by mixing the manganese, the cobalt, the copper and the nickel. At least one of aluminum oxide, cerium oxide, zinc oxide, zirconium oxide and niobium pentoxide is used as a carrier. The manganese-based composite monatomic catalyst is used in a propane oxidation reaction with oxygen as an oxidizing agent, harmful substances such as a strong acid solvent and carbon monoxide do not need to be used in a matched mode in the using process, the manganese-based composite monatomic catalyst is environmentally friendly, acetone can be obtained in a high-efficiency catalytic reaction and high selectivity mode under the low-temperature condition, the yield of acetone can reach 45-55 mmol / g catalyst <-1 > h <-1 >, and the yield of acetone can reach 45-55 mmol / g catalyst <-1 > h <-1 >. The content of acetone in a liquid product can be up to 65%, and the catalyst has excellent stability and can be stably circulated for five times without obvious deactivation.

Description

Technical Field

[0001] The invention belongs to the field of catalysis and chemical engineering, and specifically relates to a manganese-based composite single-atom catalyst and a method for preparing acetone by low-temperature oxidation of propane. Background Art

[0002] Propane is a thermodynamically stable organic compound that often appears as an associated resource in the process of exploitation of resources such as oil, natural gas, and shale gas. Due to its low explosion limit and easy liquefaction under pressure, propane is usually stored and transported in high-pressure tanks in the form of liquefied petroleum gas (LPG). The storage and transportation costs are high, the safety risks are great, and it is not suitable for long-distance land transportation. With the continuous development of resources such as shale gas, the output of propane has increased year by year. However, except for propane dehydrogenation (PDH) technology, there are few ways to apply propane in industry. Propane dehydrogenation technology converts propane into propylene at 500-700°C. Not only is the investment cost high, but it must also integrate downstream industries that are highly dependent on water resources, such as polypropylene units. Due to these special limitations, my country's PDH units are usually built in the southeast coastal areas, and it is difficult to use resources in the main propane producing areas such as the northwest. Therefore, it is of great practical significance to develop propane utilization technology suitable for my country's resource endowment characteristics and realize the in-situ conversion and utilization of propane resources.

[0003] Using oxygen as an oxidant, it is an ideal approach to convert propane into liquid oxygen-containing compounds such as acetone and propanol through an oxidation reaction, especially to achieve this process at low temperatures. First of all, the system of this reaction process is simple and the equipment requirements are low, which is suitable for construction in inland areas of my country. Secondly, products such as acetone and propanol are liquids at room temperature and pressure. They are relatively safe and economical to store and transport, and have a wide range of uses. They are convenient for on-site use as chemical raw materials. However, propane is a thermodynamically stable low-chain alkane and usually requires high temperatures to activate. Under low temperature conditions, propane exhibits inertness in oxidation reactions, and the yield of the product is usually less than 1mmol. 产物 g 催化剂 -1 h -1, which is difficult to meet the needs of industrial production (Science, 2014, 343 (6176) 1232-1237; Nature Catalysis (2023) 6, 666–675; Nature Catalysis (2023) 6, 1052–1061; Nature Communications, 2022, 13 5065). To solve this problem, the low-temperature oxidation process of propane usually requires the use of strong acids such as fuming sulfuric acid and trifluoroacetic acid as reaction solvents (Nature Catalysis 2023, 6, 666–675, Science, 2014, 343 (6176) 1232-1237), or the addition of a large amount of carbon monoxide to the reaction system (J. Am. Chem. Soc. 2023, 145, 769-773). This special reaction system not only reduces the economic efficiency of the reaction process, but also causes problems in environmental pollution and safety, so it is difficult to put into industrial application. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and to provide a manganese-based composite single-atom catalyst having high selectivity and good stability for low-temperature oxidation of propane to acetone.

[0005] The manganese-based composite single-atom catalyst provided by the present invention is a manganese-based composite single-atom catalyst that uses manganese as an active component, at least one of iron, cobalt, copper, and nickel as a first auxiliary agent, at least one of carbon and nitrogen elements as a second auxiliary agent, and at least one of aluminum oxide, cerium oxide, zinc oxide, zirconium oxide, and niobium pentoxide as a carrier; based on the mass of the catalyst as 100%, the content of the active component is 0.1% to 1.5%, the content of the first auxiliary agent is 0.1% to 0.5%, and the content of the second auxiliary agent is 0.5% to 1%.

[0006] The preparation method of the above-mentioned manganese-based composite single-atom catalyst is as follows: dissolve the manganese precursor, the first auxiliary agent precursor, and the second auxiliary agent precursor in deionized water, stir and heat to 60-80°C, then add the carrier thereto and continue stirring and heating, stir until it becomes a viscous paste, take it out, cover it with plastic wrap, and then age, dry, grind, and vacuum calcine to obtain a manganese-based composite single-atom catalyst.

[0007] Furthermore, it is preferred that the manganese precursor is any one of manganese nitrate, manganese sulfate and manganese chloride.

[0008] Furthermore, it is preferred that the precursor of the first auxiliary agent iron is any one of ferric nitrate, ferric oxalate, and ammonium ferric citrate, the precursor of the first auxiliary agent cobalt is any one of cobalt nitrate, cobalt acetylacetonate, and cobalt oxalate, the precursor of the first auxiliary agent copper is copper nitrate or copper sulfate, and the precursor of the first auxiliary agent nickel is nickel nitrate or nickel oxalate.

[0009] Furthermore, it is preferred that the precursor of the second auxiliary carbon element is at least one of fructose, sucrose, maltose and oxalic acid, and the precursor of the second auxiliary nitrogen element is at least one of ethylenediamine, amino acid and dimethylimidazole.

[0010] Furthermore, in the method for preparing the manganese-based composite catalyst, preferably, the stirring speed is 500 to 800 r / min, and the stirring and heating time after adding the carrier is continuous for 1 to 3 hours.

[0011] Furthermore, in the method for preparing the manganese-based composite catalyst, it is preferred that the aging time is 8 to 12 hours, the drying temperature is 100 to 150° C., and the drying time is 4 to 8 hours.

[0012] Furthermore, in the method for preparing the manganese-based composite catalyst, preferably, the vacuum calcination temperature is 300 to 500° C. and the time is 1 to 4 hours.

[0013] The present invention also provides a method for preparing acetone by low-temperature oxidation of propane, which specifically comprises: adding the above-mentioned manganese-based composite single-atom catalyst and acetonitrile into a high-pressure reactor, sealing it, and then sequentially introducing propane and oxygen, wherein the pressure of the propane is 0.3-0.8 MPa, and the pressure of the oxygen is 0.5-1.5 MPa, and the reaction is stirred at 100-200° C. for 4-12 hours.

[0014] Furthermore, in the above method for preparing acetone by low-temperature oxidation of propane, the reaction is preferably stirred at 160-180° C. for 5-7 hours.

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. The catalyst of the present invention uses cheap manganese as an active ingredient, transition metal as an auxiliary agent, and doped with carbon and nitrogen elements. During the catalyst preparation process, the temperature during stirring is controlled to ensure full contact between the precursor and the carrier, so that the manganese precursor is uniformly adsorbed on the surface of the carrier. After subsequent drying and calcination, a manganese-based composite single-atom catalyst in which the active component and the auxiliary agent are highly dispersed on the carrier in the form of single atoms is obtained. The catalyst of the present invention has low cost, simple preparation method, and is easy to be applied in large-scale industry.

[0017] 2. The manganese-based composite single-atom catalyst of the present invention is used in the propane oxidation reaction with oxygen as the oxidant, and can achieve efficient catalytic reaction to obtain acetone under low temperature conditions of 100 to 200°C, and the acetone yield can reach 40 to 55 mmolg 催化剂 -1 h -1 The acetone content in the liquid product can reach up to 65%, with high selectivity for acetone. The catalyst has excellent stability and can be stably cycled for 5 times without obvious deactivation.

[0018] 3. The manganese-based composite single-atom catalyst of the present invention is used to catalyze the low-temperature oxidation of propane to produce acetone. During use, no strong acid solvents, carbon monoxide and other harmful substances need to be used, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the XRD diagram of the manganese-based composite single-atom catalyst and alumina in Examples 1, 2, and 3.

[0020] Figure 2 This is the spherical aberration corrected HAADF-STEM image of the manganese-based composite single-atom catalyst in Example 1. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0022] Example 1

[0023] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, iron as a first auxiliary agent, nitrogen as a second auxiliary agent, and aluminum oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 0.3%, the content of iron is 0.3%, and the content of nitrogen is 0.5%; the preparation method of the catalyst is as follows:

[0024] Weigh 16 mg of manganese nitrate, 22.12 mg of ferric nitrate nine hydrate, and 10.7 mg of ethylenediamine and dissolve them in 50 mL of deionized water. Heat to 60 ° C under stirring conditions, add 1 g of alumina powder, stir thoroughly at 60 ° C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80 ° C for 8 hours, take out and grind to fine powder, then place in a tubular furnace, heat to 400 ° C at a heating rate of 5 ° C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst. Figure 1 It can be seen that the XRD spectrum corresponding to the obtained catalyst is similar to that of alumina, indicating that no obvious metal particles are formed and the dispersion is good. Figure 2 Evenly distributed, bright and well-dispersed bright spots can be seen on the alumina support, indicating that the metal is dispersed at the atomic level on the surface of the alumina support.

[0025] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 170°C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected and the filtered liquid product was quantitatively analyzed in a gas chromatography-mass spectrometry instrument. The reaction results are shown in Table 1.

[0026] Example 2

[0027] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, iron as a first auxiliary agent, nitrogen as a second auxiliary agent, and aluminum oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 1%, the content of iron is 0.3%, and the content of nitrogen is 0.5%; the preparation method of the catalyst is as follows:

[0028] Weigh 30.2 mg of manganese sulfate, 22.12 mg of ferric nitrate nonahydrate, and 10.7 mg of ethylenediamine and dissolve them in 50 mL of deionized water. Heat to 60 ° C under stirring conditions, add 1 g of alumina powder, stir thoroughly at 60 ° C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80 ° C for 8 hours, take out and grind to fine powder, then place in a tube furnace, heat to 500 ° C at a heating rate of 5 ° C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst (see Figure 1 ).

[0029] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 160°C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected and the filtered liquid product was quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0030] Example 3

[0031] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, iron as a first auxiliary agent, nitrogen and carbon as second auxiliary agents, and aluminum oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 1.5%, the content of iron is 0.3%, the content of nitrogen is 0.5%, and the content of carbon is 0.7%; the preparation method of the catalyst is as follows:

[0032] Weigh 38.8 mg of manganese chloride, 22.12 mg of ferric nitrate nonahydrate, 10.7 mg of ethylenediamine, and 16.62 mg of sucrose and dissolve them in 50 mL of deionized water. Heat to 60 ° C under stirring conditions, add 1 g of alumina powder, stir thoroughly at 60 ° C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80 ° C for 8 hours, take out and grind to fine powder, then put in a tube furnace, heat to 350 ° C at a heating rate of 5 ° C / min under vacuum conditions, calcine at a constant temperature for 1 hour, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst (see Figure 1 ).

[0033] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 175 ° C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected, filtered, and quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0034] Example 4

[0035] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, copper as a first auxiliary agent, nitrogen as a second auxiliary agent, and cerium oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 0.3%, the content of copper is 0.4%, and the content of nitrogen is 0.5%; the preparation method of the catalyst is as follows:

[0036] Weigh 16 mg of manganese nitrate, 12.2 mg of copper nitrate, and 10.7 mg of ethylenediamine and dissolve them in 50 mL of deionized water. Heat to 60°C under stirring, add 1 g of cerium oxide powder, stir thoroughly at 60°C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80°C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 400°C at a heating rate of 5°C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0037] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 175 ° C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected, filtered, and quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0038] Example 5

[0039] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, cobalt and nickel as first additives, carbon as a second additive, and cerium oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 0.4%, the content of cobalt is 0.3%, the content of nickel is 0.4%, and the content of carbon is 0.7%; the preparation method of the catalyst is as follows:

[0040] Weigh 16 mg of manganese nitrate, 9.6 mg of cobalt nitrate, 17.5 mg of nickel acetylacetonate, and 16.62 mg of sucrose and dissolve them in 50 mL of deionized water. Heat to 60°C under stirring, add 1 g of cerium oxide powder, stir thoroughly at 60°C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80°C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 500°C at a heating rate of 5°C / min under vacuum conditions, calcine at a constant temperature for 1 hour, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0041] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 175 ° C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected, filtered, and quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0042] Example 6

[0043] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, cobalt as a first auxiliary agent, carbon as a second auxiliary agent, and zinc oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 1.5%, the content of cobalt is 0.3%, and the content of carbon is 1%; the preparation method of the catalyst is as follows:

[0044] Weigh 38.8 mg of manganese chloride, 9.6 mg of cobalt nitrate, 13.8 mg of fruit acid, and 11.87 mg of sucrose and dissolve them in 50 mL of deionized water. Heat to 60 ° C under stirring, add 1 g of zinc oxide powder, stir thoroughly at 60 ° C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80 ° C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 450 ° C at a heating rate of 5 ° C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0045] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 175 ° C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected, filtered, and quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0046] Example 7

[0047] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, cobalt as a first auxiliary agent, nitrogen as a second auxiliary agent, and zinc oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 1.5%, the content of cobalt is 0.3%, and the content of nitrogen is 0.6%; the preparation method of the catalyst is as follows:

[0048] Weigh 38.8 mg of manganese chloride, 9.6 mg of cobalt nitrate, and 39.6 mg of amino acid and dissolve them in 50 mL of deionized water. Heat to 60 ° C under stirring conditions, add 1 g of zinc oxide powder, stir thoroughly at 60 ° C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80 ° C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 400 ° C at a heating rate of 5 ° C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0049] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 175 ° C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected, filtered, and quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0050] Example 8

[0051] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, cobalt as a first auxiliary agent, nitrogen and carbon as second auxiliary agents, and zinc oxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 0.3%, the content of cobalt is 0.3%, the content of nitrogen is 0.5%, and the content of carbon is 0.4%; the preparation method of the catalyst is as follows:

[0052] Weigh 16 mg of manganese nitrate, 9.6 mg of cobalt nitrate, 10.7 mg of ethylenediamine, and 9.5 mg of maltose and dissolve them in 50 mL of deionized water. Heat to 60 ° C under stirring, add 1 g of zinc oxide, stir thoroughly at 60 ° C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80 ° C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 400 ° C at a heating rate of 5 ° C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0053] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 175 ° C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected, filtered, and quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0054] Example 9

[0055] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, iron as a first auxiliary agent, nitrogen as a second auxiliary agent, and niobium pentoxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 1%, the content of iron is 0.3%, and the content of nitrogen is 0.5%; the preparation method of the catalyst is as follows:

[0056] Weigh 30.2 mg of manganese sulfate, 7.2 mg of ferric nitrate nonahydrate, and 10.7 mg of ethylenediamine and dissolve them in 50 mL of deionized water. Heat to 60°C under stirring, add 1 g of niobium pentoxide powder, stir thoroughly at 60°C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80°C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 500°C at a heating rate of 5°C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0057] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 160°C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected and the filtered liquid product was quantitatively analyzed in a gas chromatography-mass spectrometer. The reaction results are shown in Table 1.

[0058] Example 10

[0059] The manganese-based composite single-atom catalyst of this embodiment uses manganese as an active component, iron as a first auxiliary agent, carbon as a second auxiliary agent, and niobium pentoxide as a carrier; based on the mass of the catalyst as 100%, the content of manganese is 0.6%, the content of iron is 0.3%, and the content of carbon is 0.6%; the preparation method of the catalyst is as follows:

[0060] Weigh 32 mg of manganese nitrate, 7.2 mg of ferric nitrate nonahydrate, and 14.25 mg of maltose and dissolve them in 50 mL of deionized water. Heat to 60°C under stirring, add 1 g of niobium pentoxide powder, stir thoroughly at 60°C for 1 hour, cover with plastic wrap, age for 12 hours, put in a drying oven at 80°C for 8 hours, take out and grind into fine powder, then place in a tubular furnace, heat to 500°C at a heating rate of 7°C / min under vacuum conditions, calcine at a constant temperature for 1.5 hours, cool naturally to room temperature and take out to obtain a manganese-based composite single atom catalyst.

[0061] 30 mg of manganese-based composite single-atom catalyst and 28 mL of acetonitrile were added to a 100 mL high-pressure reactor. After sealing, propane and oxygen were introduced in sequence. The pressure of propane was 0.6 MPa and the pressure of oxygen was 1.2 MPa. The reaction was stirred at 180°C for 6 h and the stirring speed was 600 r / min. The liquid product after the reaction was collected and the filtered liquid product was quantitatively analyzed in a gas chromatography-mass spectrometry instrument. The reaction results are shown in Table 1.

[0062] Table 1 Catalytic performance of different catalysts in the reaction

[0063] catalyst <![CDATA[Acetone yield (mmol 产物 g 催化剂 -1 h -1 )]]> Selectivity of acetone in liquid products Example 1 54.15 65.02％ Example 2 46.54 51.25％ Example 3 45.35 48.15％ Example 4 50.35 56.63％ Example 5 51.53 61.95％ Example 6 43.58 44.51％ Example 7 42.68 42.77％ Example 8 52.58 62.12％ Example 9 43.52 51.21％ Example 10 47.01 52.16％

[0064] The catalyst and catalytic reaction conditions of Example 1 were further used to test the stability of the catalyst. The results are shown in Table 2.

[0065] Table 2 Test results of catalyst cycle 5 times in Example 1

[0066]

[0067]

[0068] It can be seen from the experimental results in Tables 1 and 2 that the manganese-based composite single-atom catalyst of the present invention is used in the propane oxidation reaction with oxygen as the oxidant, and can achieve high efficiency catalytic reaction and high selectivity to obtain acetone under low temperature conditions, and the acetone yield can reach 45-55 mmol g 催化剂 -1 h -1 The acetone content in the liquid product can reach up to 65%, and the catalyst has excellent stability and can be stably cycled 5 times without obvious deactivation.

Claims

1. A manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone, characterized in that: The manganese-based composite single-atom catalyst uses manganese as an active component, at least one of iron, cobalt, copper, and nickel as a first auxiliary agent, at least one of carbon and nitrogen as a second auxiliary agent, and at least one of aluminum oxide, cerium oxide, zinc oxide, zirconium oxide, and niobium pentoxide as a carrier; based on 100% of the mass of the catalyst, the content of the active component is 0.1% to 1.5%, the content of the first auxiliary agent is 0.1% to 0.5%, and the content of the second auxiliary agent is 0.5% to 1%; The preparation method of the manganese-based composite single-atom catalyst is as follows: dissolving a manganese precursor, a first auxiliary agent precursor, and a second auxiliary agent precursor in deionized water, stirring and heating to 60-80° C., and then adding the carrier therein for a continuous The mixture is stirred and heated until it becomes a viscous paste, taken out and covered with plastic wrap, and then aged, dried, ground and vacuum calcined to obtain a manganese-based composite single-atom catalyst.

2. The manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone according to claim 1, characterized in that: The manganese precursor is any one of manganese nitrate, manganese sulfate and manganese chloride.

3. The manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone according to claim 1, characterized in that: The precursor of the first auxiliary agent iron is any one of ferric nitrate, ferric oxalate, and ammonium ferric citrate; the precursor of the first auxiliary agent cobalt is any one of cobalt nitrate, cobalt acetylacetonate, and cobalt oxalate; the precursor of the first auxiliary agent copper is copper nitrate or copper sulfate; and the precursor of the first auxiliary agent nickel is nickel nitrate or nickel oxalate.

4. The manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone according to claim 1, characterized in that: The precursor of the second auxiliary carbon element is at least one of fructose, sucrose, maltose and oxalic acid, and the precursor of the second auxiliary nitrogen element is at least one of ethylenediamine, amino acid and dimethylimidazole.

5. The manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone according to claim 1, characterized in that: In the preparation method of the manganese-based composite catalyst, the stirring speed is 500 to 800 r / min, and the stirring and heating time after the carrier is added is 1 to 3 hours.

6. The manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone according to claim 1, characterized in that: In the preparation method of the manganese-based composite catalyst, the aging time is 8 to 12 hours, the drying temperature is 100 to 150° C., and the drying time is 4 to 8 hours.

7. The manganese-based composite single-atom catalyst for low-temperature oxidation of propane to acetone according to claim 1, characterized in that: In the preparation method of the manganese-based composite catalyst, the vacuum calcination temperature is 300-500° C. and the time is 1-4 hours.

8. A method for preparing acetone by low temperature oxidation of propane, characterized in that: The manganese-based composite single-atom catalyst according to any one of claims 1 to 7 and acetonitrile are added into a high-pressure reactor, which is sealed, and propane and oxygen are introduced in sequence, wherein the pressure of propane is 0.3 to 0.8 MPa, and the pressure of oxygen is 0.5 to 1.5 MPa, and the reaction is stirred at 100 to 200° C. for 4 to 12 hours.

9. The method for preparing acetone by low temperature oxidation of propane according to claim 8, characterized in that: Stir the reaction at 160-180°C for 5-7 hours.

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