Catalyst with low noble metal content as well as preparation method and application of catalyst

Abstract

The invention relates to a low-noble-metal-content catalyst and a preparation method and application thereof, the low-noble-metal-content catalyst comprises a main catalyst and an oxide auxiliary agent, and the main catalyst comprises a transition metal, a noble metal co-catalyst and a structure auxiliary agent. The transition metal is a main active site; the addition of noble metal promotes the improvement of catalytic activity; the structural aid can inhibit agglomeration and deactivation of the catalyst and improve the activity and stability of the catalyst; the oxide can be activated to further improve the reaction activity. Through optimal combination of catalyst components, 99% of ether bond hydrogenolysis conversion rate of a model compound diphenyl ether is realized, and the hydrogenation depolymerization activity of substrates such as dealkalized lignin and polycarbonate plastics is higher than that of a commercial Ru-Al2O3 catalyst.

Description

Technical Field

[0001] The present invention relates to the technical field of organic catalysis, and in particular to a catalyst with low noble metal content, a preparation method and application thereof. Background Art

[0002] CO bond hydrogenolysis is an important method for depolymerizing polymers such as biomass and plastics into monomers. These inexpensive waste products are composed of monomers linked by CO and CC bonds, with CO bonds comprising approximately 70% of the monomers. Efficient CO bond hydrogenolysis can produce high-value-added fine chemicals (benzene and toluene), but the high CO bond energy makes this process extremely challenging.

[0003] Existing ether bond hydrogenolysis catalysts can be categorized into metal sulfides, carbides, nitrides, non-precious metal oxides, and precious metal-based catalysts. Sulfides are susceptible to sulfur etching, resulting in increased sulfur content in the product. Precious metal-based catalysts are expensive and exhibit low ether bond hydrogenolysis selectivity. Therefore, developing inexpensive catalysts for efficient ether bond hydrogenolysis is crucial for producing small molecules from biomass and polymers such as plastics. Summary of the Invention

[0004] To solve the above technical problems, the present invention improves the catalytic activity and stability of the catalyst through the synergistic effect of transition metals, precious metal co-catalysts, structural additives and oxide additives, uses trace amounts of precious metals, is low-priced, environmentally friendly, and suitable for large-scale applications.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a low-noble metal content catalyst, wherein the low-noble metal content catalyst comprises a main catalyst and an oxide promoter, wherein the main catalyst comprises a transition metal, a noble metal co-catalyst and a structural promoter.

[0007] The present invention uses transition metals as the main active sites, the addition of noble metals promotes the improvement of catalytic activity, the addition of structural additives can inhibit the agglomeration and deactivation of the catalyst, and the oxide additives can be activated after addition, further improving the catalytic activity. The synergistic effect of several components improves the activity of the catalyst in ether bond hydrogenolysis.

[0008] As a preferred technical solution of the present invention, the structural additive and the transition metal in the main catalyst form a dopant, and the noble metal co-catalyst is loaded outside the dopant.

[0009] As a preferred technical solution of the present invention, the main catalyst includes, by weight: 40-80 parts of transition metal, for example, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts or 80 parts, etc.; 0.01-1.0 parts of precious metal co-catalyst, for example, 0.01 parts, 0.02 parts, 0.05 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8, 0.9 parts or 1.0 parts, etc.; and 10-40 parts of structural additives, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts, etc.

[0010] Preferably, the mass ratio of the main catalyst to the oxide auxiliary agent is 1:(5-50), for example, it can be 1:5, 1:10, 1:20, 1:30, 1:40 or 1:50.

[0011] The present invention improves the activity and stability of the catalyst, reduces the amount of precious metal used, and improves the economic efficiency of the catalyst by preferably adjusting the content of each component in the low-noble metal content catalyst to be within the above range.

[0012] As a preferred technical solution of the present invention, the noble metal co-catalyst includes any one or a combination of at least two of ruthenium, platinum and palladium.

[0013] The structural auxiliary agent includes any one or a combination of at least two of aluminum, zinc and manganese.

[0014] The oxide auxiliary agent includes any one of zirconium oxide, cerium oxide and iron oxide, or a combination of at least two thereof, preferably zirconium oxide.

[0015] In a second aspect, the present invention provides a method for preparing the low noble metal content catalyst as described in the first aspect, the preparation method comprising the following steps:

[0016] (1) preparing a composite transition metal oxide doped with a structural additive by a coprecipitation method, and obtaining a first intermediate through a first reduction treatment and a second aging treatment;

[0017] (2) loading a noble metal co-catalyst on the first intermediate by an impregnation method, and obtaining the main catalyst through a second reduction treatment and a third aging process;

[0018] (3) The main catalyst is mixed with an oxide auxiliary agent to obtain the low noble metal content catalyst.

[0019] As a preferred technical solution of the present invention, the coprecipitation method includes dissolving a transition metal precursor and a structural additive precursor in a solvent, adding a precipitant to precipitate the transition metal and the structural additive, and sequentially performing first aging, solid-liquid separation, washing and drying.

[0020] Preferably, the transition metal precursor includes any one of cobalt nitrate, iron nitrate and nickel nitrate, or a combination of at least two thereof.

[0021] Preferably, the structural auxiliary agent precursor includes any one of aluminum nitrate, zinc nitrate and manganese nitrate, or a combination of at least two thereof.

[0022] Preferably, the solvent comprises deionized water.

[0023] Preferably, the precipitant is sodium hydroxide or ammonia water.

[0024] Preferably, the precipitant is added to adjust the pH of the solution to 8-10, for example, 8, 8.5, 9, 9.5 or 10.

[0025] Preferably, the first aging is stirring at room temperature for 10-20 hours, for example, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours.

[0026] Preferably, the washing comprises sequentially washing with deionized water and ethanol to remove residual ions on the surface of the first intermediate.

[0027] As a preferred technical solution of the present invention, the impregnation method includes dissolving a noble metal precursor in a solvent to obtain a noble metal precursor solution, dripping the noble metal precursor solution onto the first intermediate, impregnating the first intermediate, and then drying the first intermediate.

[0028] Preferably, the noble metal precursor includes any one or a combination of at least two of ruthenium nitrosyl nitrate, palladium nitrate tetrahydrate and chloroplatinic acid.

[0029] Preferably, stirring is performed during the impregnation process.

[0030] The present invention does not impose any specific limitation on the stirring time, as long as the metal precursor can be evenly loaded on the surface of the first intermediate.

[0031] As a preferred technical solution of the present invention, the temperature of the first reduction treatment is 400°C-800°C, for example, it can be 400°C, 500°C, 600°C, 700°C or 800°C.

[0032] Preferably, the first reduction treatment time is 2 h to 4 h, for example, 2 h, 2.5 h, 2.8 h, 3 h, 3.5 h, 3.8 h or 4 h.

[0033] Preferably, the temperature of the second reduction treatment is 400°C-800°C, for example, 400°C, 500°C, 600°C, 700°C or 800°C.

[0034] Preferably, the second reduction treatment time is 2 h to 4 h, for example, 2 h, 2.5 h, 2.8 h, 3 h, 3.5 h, 3.8 h or 4 h.

[0035] The reduction temperature and time of the catalyst of the present invention are preferably within the above ranges, so as to avoid the agglomeration of the catalyst while ensuring that the catalyst is fully reduced, thereby improving the catalytic activity and stability.

[0036] Preferably, the first reduction treatment and the second reduction treatment use hydrogen or a mixture of hydrogen and nitrogen as the reducing gas.

[0037] Preferably, the volume content of hydrogen in the reducing gas is 2-100%, for example, it can be 2%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%.

[0038] As a preferred technical solution of the present invention, the second aging and the third aging are performed by standing in a mixed atmosphere of oxygen and nitrogen.

[0039] Preferably, the volume content of oxygen in the mixed atmosphere is 1-5%, for example, 1%, 2%, 3%, 4% or 5%.

[0040] The present invention promotes catalyst stability through the second aging and the third aging, thereby preventing the catalyst from being violently oxidized by air and reducing catalytic activity.

[0041] In a third aspect, the present invention provides an application of the low-noble metal content catalyst as described in the first aspect, characterized in that the application comprises using the low-noble metal content catalyst for hydrogenolysis of ether bonds in polymers;

[0042] Preferably, the polymer comprises dealkalized lignin or polycarbonate plastic.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] (1) The low-noble-metal content catalyst provided by the present invention improves the ether bond hydrogenolysis activity through the synergistic effect of transition metals, noble metal co-catalysts, structural additives, and oxide additives, achieving an ether bond hydrogenolysis efficiency of 99% for model compounds such as diphenyl ether, 2-phenoxy-1-phenylethanol, and 2-phenoxyacetophenone. The hydrogenation depolymerization activity for substrates such as dealkalized lignin and polycarbonate plastics is 2.76 mmol·g -1 ·h -1 and 190.8mmol·g -1 ·h -1 , much higher than that of commercial Ru-Al2O3 catalyst.

[0045] (2) The low-noble-metal-content catalyst provided by the present invention has an extremely low noble-metal content, is inexpensive, does not involve sulfides, and is environmentally friendly.

[0046] (3) The low-noble metal content catalyst provided by the present invention can effectively improve the reaction activity by introducing cheap inert oxides as auxiliary agents, thereby further reducing costs. DETAILED DESCRIPTION

[0047] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0048] Example 1

[0049] This embodiment provides a low-precious metal content catalyst, which includes a main catalyst and zirconium oxide. The main catalyst includes, by weight, 65.78 parts of cobalt, 0.11 parts of ruthenium metal co-catalyst and 15.33 parts of aluminum structural additive. The mass ratio of the main catalyst to the oxide additive is 1:12.5, and the mass content of the ruthenium metal co-catalyst in the catalyst is 0.008%.

[0050] The catalyst is prepared by the following method:

[0051] (1) Cobalt nitrate and aluminum nitrate were dissolved in deionized water at a mass ratio of 1.6:1, sodium hydroxide was added as a precipitant to adjust the pH value to 8.5, and the mixture was stirred and aged at room temperature for 16 hours. The mixture was then washed with water and ethanol to remove residual ions. The mixture was dried at 80°C and reduced at 400°C under 5% H2 / N2 for 2 hours. The mixture was cooled to room temperature and aged in a 2% O2 / N2 atmosphere for 1 hour to obtain a first intermediate.

[0052] (2) 3.14 mg of ruthenium nitrosyl nitrate was dissolved in deionized water, added dropwise to 1 g of the first intermediate, stirred evenly, dried at 80°C, and reduced at 400°C under 5% H2 / N2 for 2 h. After the temperature was lowered to room temperature, the mixture was aged in a 2% O2 / N2 atmosphere for 1 h to obtain the main catalyst;

[0053] (3) Physically mixing the main catalyst and the zirconium oxide auxiliary agent in a mass ratio of 1:12.5 to obtain the low noble metal content catalyst.

[0054] Example 2

[0055] This embodiment provides a low-precious metal content catalyst, which includes a main catalyst and zirconium oxide. The main catalyst includes, by weight, 40 parts of cobalt, 0.01 parts of ruthenium metal co-catalyst and 10 parts of aluminum structural additive. The mass ratio of the main catalyst to the oxide additive is 1:5, and the mass content of the ruthenium metal co-catalyst in the catalyst is 0.002%.

[0056] The catalyst is prepared by the following method:

[0057] (1) Cobalt nitrate and aluminum nitrate were dissolved in deionized water at a mass ratio of 1.4:1, sodium hydroxide was added as a precipitant to adjust the pH value to 8.5, and the mixture was stirred and aged at room temperature for 16 hours. The mixture was then washed with water and ethanol to remove residual ions. The mixture was dried at 80°C and reduced at 400°C under 5% H2 / N2 for 4 hours. The mixture was cooled to room temperature and aged in a 2% O2 / N2 atmosphere for 1 hour to obtain a first intermediate.

[0058] (2) 0.32 mg of ruthenium nitrosyl nitrate was dissolved in deionized water, added dropwise to 1 g of the first intermediate, stirred evenly, dried at 80°C, and reduced at 600°C under 5% H2 / N2 for 2 h. After the temperature was lowered to room temperature, the mixture was aged in a 2% O2 / N2 atmosphere for 1 h to obtain the main catalyst;

[0059] (3) Physically mixing the main catalyst and the zirconium oxide auxiliary agent in a mass ratio of 1:5 to obtain the low noble metal content catalyst.

[0060] Example 3

[0061] This embodiment provides a low-precious metal content catalyst, which includes a main catalyst and zirconium oxide. The main catalyst includes, by weight, 80 parts of cobalt, 1.0 part of ruthenium metal co-catalyst and 40 parts of aluminum structural additive. The mass ratio of the main catalyst to the oxide additive is 1:50, and the mass content of the ruthenium metal co-catalyst in the catalyst is 0.02%.

[0062] The catalyst is prepared by the following method:

[0063] (1) Cobalt nitrate and aluminum nitrate were dissolved in deionized water at a mass ratio of 0.7:1, sodium hydroxide was added as a precipitant to adjust the pH value to 8.5, and the mixture was stirred and aged at room temperature for 16 hours. The mixture was then washed with water and ethanol to remove residual ions. The mixture was dried at 80°C and reduced at 800°C under 5% H2 / N2 for 3 hours. The mixture was cooled to room temperature and aged in a 2% O2 / N2 atmosphere for 1 hour to obtain a first intermediate.

[0064] (2) 31.4 mg of ruthenium nitrosyl nitrate was dissolved in deionized water, added dropwise to 1 g of the first intermediate, stirred evenly, dried at 80°C, and reduced at 400°C under 5% H2 / N2 for 2 h. After the temperature was lowered to room temperature, the mixture was aged in a 2% O2 / N2 atmosphere for 1 h to obtain the main catalyst;

[0065] (3) Physically mixing the main catalyst and the zirconium oxide additive in a mass ratio of 1:50 to obtain the low noble metal content catalyst.

[0066] Example 4

[0067] This embodiment provides a low-precious metal content catalyst, which is the same as Example 1 except that the transition metal is replaced by iron from cobalt, the mass of the transition metal is kept unchanged, and the cobalt nitrate in step (1) is replaced by iron nitrate.

[0068] Example 5

[0069] This embodiment provides a low-precious metal content catalyst, which is the same as Example 1 except that the transition metal is replaced by nickel from cobalt, the mass of the transition metal is kept unchanged, and the cobalt nitrate in step (1) is replaced by nickel nitrate.

[0070] Example 6

[0071] This embodiment provides a low-noble metal content catalyst, which is the same as that of Example 1 except that the weight portion of cobalt is 90 parts.

[0072] Example 7

[0073] This embodiment provides a low-noble metal content catalyst, which is the same as that of Example 1 except that the weight portion of cobalt is 30 parts.

[0074] Example 8

[0075] This embodiment provides a catalyst with low noble metal content. The catalyst with low noble metal content is the same as that in embodiment 1 except that the weight portion of the structural auxiliary agent is 5 parts.

[0076] Example 9

[0077] This embodiment provides a catalyst with low noble metal content. The catalyst with low noble metal content is the same as that in embodiment 1 except that the weight portion of the structural auxiliary agent is 50 parts.

[0078] Example 10

[0079] This embodiment provides a low-noble metal content catalyst, which is the same as that of Example 1 except that the weight portion of the noble metal co-catalyst is 0.005 parts.

[0080] Example 11

[0081] This embodiment provides a low-noble metal content catalyst, which is the same as that of Example 1 except that the weight portion of the noble metal co-catalyst is 1.5 parts.

[0082] Example 12

[0083] This embodiment provides a catalyst with a low noble metal content. The catalyst with a low noble metal content is the same as that in Example 1 except that the mass ratio of the main catalyst to the oxide auxiliary agent is 1:3.

[0084] Example 13

[0085] This embodiment provides a low-noble metal content catalyst, which is the same as that of Example 1 except that the mass ratio of the main catalyst to the oxide auxiliary agent is 1:60.

[0086] Example 14

[0087] This embodiment provides a low-noble metal content catalyst, which is the same as that of embodiment 1 except that the oxide auxiliary agent is cerium oxide.

[0088] Example 15

[0089] This embodiment provides a catalyst with low noble metal content. The catalyst with low noble metal content is the same as that in embodiment 1 except that the oxide auxiliary agent is iron oxide.

[0090] Example 16

[0091] This embodiment provides a low-noble metal content catalyst, which is the same as that of embodiment 1 except that the first reduction temperature is 300°C.

[0092] Example 17

[0093] This embodiment provides a low-noble metal content catalyst, which is the same as that of embodiment 1 except that the first reduction temperature is 900°C.

[0094] Example 18

[0095] This embodiment provides a low-noble metal content catalyst, which is the same as that of embodiment 1 except that the second reduction temperature is 300°C.

[0096] Example 19

[0097] This embodiment provides a low-noble metal content catalyst, which is the same as that of embodiment 1 except that the second reduction temperature is 900°C.

[0098] Comparative Example 1

[0099] This comparative example provides a catalyst, which is the same as Example 1 except that the catalyst does not include an oxide promoter.

[0100] Comparative Example 2

[0101] This comparative example provides a catalyst, which is the same as Example 1 except that the catalyst does not include a noble metal co-catalyst and an oxide promoter.

[0102] Comparative Example 3

[0103] This comparative example provides a catalyst, which is the same as Example 1 except that the catalyst does not include structural additives and oxide additives, and the weight percentage of the structural additives in the main catalyst is supplemented by transition metals.

[0104] Comparative Example 4

[0105] This comparative example provides a catalyst, which is the same as Example 1 except that the catalyst does not include transition metal and oxide promoter, and the weight percentage of transition metal in the main catalyst is supplemented by structural promoter.

[0106] Comparative Example 5

[0107] This comparative example provides a catalyst, which is the same as Example 1 except that the catalyst does not include a structural auxiliary agent and the weight percentage of the structural auxiliary agent in the main catalyst is supplemented by a transition metal.

[0108] Comparative Example 6

[0109] This comparative example provides a catalyst, which is the same as Example 1 except that the catalyst does not include a precious metal co-catalyst.

[0110] Comparative Example 7

[0111] This comparative example provides a catalyst, which is a commercial 1% Ru-Al2O3 catalyst.

[0112] Test Method

[0113] The catalysts of Examples 1-19 and Comparative Examples 1-7 were subjected to a catalytic performance test of ether bond hydrogenolysis of diphenyl ether. 1.07 g of diphenyl ether, a catalyst (0.02 g of the primary catalyst, and an oxide promoter were added according to the content settings in the Examples and Comparative Examples), and 50 mL of hexadecane solvent were loaded into a reactor. The reactor was then purged with 1 MPa of H2 for 6 times and the pressure was released to normal pressure. The reactor was then heated to 200 ° C. The reaction was then pressurized to 1 MPa with H2. Stirring (600 rpm) was then started, and the reaction continued for 1 hour. The product was analyzed by gas chromatography during the test, and the reaction conversion was tested. The test results are shown in Table 1.

[0114] The catalysts of Examples 1-19 and Comparative Examples 1-7 were tested for their catalytic performance in hydrogenolysis of the ether bond of 2-phenoxy-1-phenylethanol. 1.34 g of 2-phenoxy-1-phenylethanol, 0.02 g of the catalyst (the primary catalyst was added, with the oxide promoter added according to the content in the Examples and Comparative Examples), and 50 mL of hexadecane solvent were loaded into a reactor. The reactor was then purged with 1 MPa of H₂ for six times and the pressure was released to normal pressure. The reactor was then heated to 200° C. and pressurized to 1 MPa with H₂. Stirring was then initiated (600 rpm) and the reaction continued for 1 hour. The products were analyzed by gas chromatography-mass spectrometry to test the reaction conversion and selectivity. Conversion is the molar ratio of 2-phenoxy-1-phenylethanol conversion to the amount added, and ether bond hydrogenolysis selectivity is the molar ratio of the products ethylbenzene and cyclohexanol to all products. The test results are shown in Table 2.

[0115] The catalysts of Examples 1-19 and Comparative Examples 1-7 were tested for their catalytic performance in hydrogenolysis of the ether bond of 2-phenoxyacetophenone. 1.34 g of 2-phenoxyacetophenone, 0.02 g of the catalyst (the primary catalyst was added, with the oxide promoter added according to the content in the Examples and Comparative Examples), and 50 mL of hexadecane solvent were loaded into a reactor. The reactor was then purged with 1 MPa of H₂ six times and the pressure was released to atmospheric pressure. The reactor was then heated to 200° C. and pressurized with H₂ to 1 MPa. Stirring was then initiated (600 rpm) and the reaction continued for 1 hour. The products were analyzed by gas chromatography-mass spectrometry to determine reaction conversion and selectivity. Conversion is the molar ratio of 2-phenoxyacetophenone converted to the amount added, and ether bond hydrogenolysis selectivity refers to the molar ratio of the products ethylbenzene and cyclohexanol to all products. The test results are shown in Table 3.

[0116] The catalysts from Examples 1-19 and Comparative Examples 1-7 were tested for their catalytic performance in hydrogenolysis of ether bonds in dealkalized lignin. The primary catalyst was used in an amount of 50 mg, and the oxide adjuvant was added according to the amounts described in the Examples and Comparative Examples. The reaction temperature was 250°C, the reaction atmosphere was 1 MPa of hydrogen, the reaction time was 8 hours, and the reactant was 1 g of dealkalized lignin. The reaction mass activity was tested, and the test results are shown in Table 4.

[0117] The catalysts from Examples 1-19 and Comparative Examples 1-7 were tested for their catalytic performance in hydrogenolysis of ether bonds in polycarbonate plastic. The primary catalyst was used in an amount of 50 mg, and the oxide additive was added according to the amounts specified in the Examples and Comparative Examples. The reaction temperature was 250°C, the reaction atmosphere was 1 MPa of hydrogen, the reaction time was 8 hours, and the reactant was 1.5 g of polycarbonate. The reaction mass activity was tested, and the test results are shown in Table 5.

[0118] Test results.

[0119] Table 1

[0120]

[0121]

[0122] Table 2

[0123]

[0124]

[0125] Table 3

[0126]

[0127]

[0128] Table 4

[0129]

[0130]

[0131] Table 5

[0132]

[0133]

[0134] The test results show that:

[0135] (1) It can be seen from Examples 1 to 3 that the present invention, through the optimized combination of catalyst components, achieves a conversion rate of more than 82% for the catalytic hydrogenolysis of diphenyl ether and a conversion rate of more than 92% for the catalytic hydrogenolysis of 2-phenoxy-1-phenylethanol and 2-phenoxyacetophenone, and the selectivity of ether bond hydrogenolysis is more than 76%. The mass activity of hydrogenolysis of ether bonds in dealkalized lignin and polycarbonate is higher than that of the commercial 1% Ru-Al2O3 catalyst.

[0136] (2) It can be seen from Examples 1 and 4-15 that the present invention can achieve a better catalytic effect for ether bond hydrogenolysis by further optimizing the component content, the types of transition metals and oxide additives, among which cobalt as a transition metal has the best catalytic effect, and zirconium oxide as an oxide additive has the best catalytic effect.

[0137] (3) It can be seen from Example 1 and Examples 16-19 that the present invention can achieve a better ether bond hydrogenolysis catalytic effect by further optimizing the reduction temperature of the catalyst and avoid the agglomeration of active substances on the catalyst surface. When the reduction temperature is too low or too high, the catalytic activity of the catalyst decreases and the ether bond hydrogenolysis selectivity decreases.

[0138] (4) As can be seen from Example 1 and Comparative Examples 1-7, the present invention achieves a 99% ether bond hydrogenolysis conversion rate for diphenyl ether through the synergistic effect of multiple components, and the catalytic hydrogenolysis of 2-phenoxy-1-phenylethanol and 2-phenoxyacetophenone is above 88%. The lack of any of the four components will lead to a decrease in catalyst activity or selectivity. In addition, the catalyst of the present invention is much more effective in catalyzing the ether bond hydrogenolysis of these substances than the commonly used commercial 1% Ru-Al2O3 catalyst.

[0139] In summary, the present invention utilizes transition metal materials as the primary catalyst component, noble metals as co-catalysts, aluminum, zinc, and manganese, whose ionic radii are similar to cobalt, as structural additives, and inexpensive inert oxides as additional additives. These four components work synergistically to achieve efficient hydrogenolysis of ether bonds.

[0140] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A catalyst with low noble metal content, characterized in that: The low noble metal content catalyst comprises a main catalyst and an oxide promoter, wherein the main catalyst comprises a transition metal, a noble metal co-catalyst and a structural promoter.

2. The low noble metal content catalyst according to claim 1, characterized in that The structural auxiliary agent and the transition metal in the main catalyst form a dopant, and the noble metal co-catalyst is loaded outside the dopant.

3. The low noble metal content catalyst according to claim 1 or 2, characterized in that The main catalyst comprises, by weight, 40-80 parts of transition metal, 0.01-1.0 parts of noble metal co-catalyst and 10-40 parts of structural additive; Preferably, the mass ratio of the main catalyst to the oxide auxiliary agent is 1:(5-50).

4. The low noble metal content catalyst according to any one of claims 1 to 3, characterized in that The transition metal includes any one or a combination of at least two of cobalt, iron and nickel; Preferably, the noble metal co-catalyst comprises any one or a combination of at least two of ruthenium, platinum and palladium; Preferably, the structural additive comprises any one or a combination of at least two of aluminum, zinc and manganese; Preferably, the oxide auxiliary agent includes any one of zirconium oxide, cerium oxide and iron oxide, or a combination of at least two thereof, preferably zirconium oxide.

5. A method for preparing a low-noble metal content catalyst according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) preparing a composite transition metal oxide doped with a structural additive by a coprecipitation method, and obtaining a first intermediate through a first reduction treatment and a second aging treatment; (2) loading a noble metal co-catalyst on the first intermediate by an impregnation method, and obtaining the main catalyst through a second reduction treatment and a third aging process; (3) The main catalyst is mixed with an oxide auxiliary agent to obtain the low noble metal content catalyst.

6. The preparation method according to claim 5, characterized in that The co-precipitation method comprises dissolving a transition metal precursor and a structural additive precursor in a solvent, adding a precipitant to precipitate the transition metal and the structural additive, and sequentially performing a first aging, solid-liquid separation, washing, and drying; Preferably, the transition metal precursor comprises any one or a combination of at least two of cobalt nitrate, iron nitrate and nickel nitrate; Preferably, the structural auxiliary agent precursor includes any one of aluminum nitrate, zinc nitrate and manganese nitrate, or a combination of at least two thereof.

7. The preparation method according to claim 5 or 6, characterized in that: The impregnation method comprises dissolving a noble metal precursor in a solvent to obtain a noble metal precursor solution, dripping the noble metal precursor solution onto the first intermediate, impregnating the first intermediate, and then drying the first intermediate; Preferably, the noble metal precursor includes any one or a combination of at least two of ruthenium nitrosyl nitrate, palladium nitrate tetrahydrate and chloroplatinic acid.

8. The preparation method according to any one of claims 5 to 7, characterized in that The temperature of the first reduction treatment is 400° C.-800° C.; Preferably, the first reduction treatment time is 2h-4h; Preferably, the temperature of the second reduction treatment is 400°C-800°C; Preferably, the second reduction treatment time is 2h-4h; Preferably, the first reduction treatment and the second reduction treatment use hydrogen or a mixture of hydrogen and nitrogen as the reducing gas.

9. The preparation method according to any one of claims 5 to 8, characterized in that The second aging and the third aging are performed by leaving the sample to stand in a mixed atmosphere of oxygen and nitrogen.

10. Use of the low noble metal content catalyst according to any one of claims 1 to 4, characterized in that: The application includes using the low-noble metal content catalyst for hydrogenolysis of ether bonds in polymers; preferably, the polymer includes dealkalized lignin or polycarbonate plastics.

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