Preparation method of transition metal hydrotalcite-molecular sieve composite catalyst and application of transition metal hydrotalcite-molecular sieve composite catalyst in organic solid waste C-C bond breakage

Abstract

The invention discloses a preparation method of a transition metal hydrotalcite-molecular sieve composite catalyst and application of the transition metal hydrotalcite-molecular sieve composite catalyst in organic solid waste C-C bond breakage. The catalyst is represented by M-Al2O3 (at) C and has a specific flower-like morphology, M-Al2O3 represents Al2O3 loaded metal particles, M is one of Ni, Cu, Co, Fe, Zn, Pt, Rh, Pd, Ir, Mo, Mg and Sn, the mass ratio of M to (M-Al2O3 (at) C) is 10-25 wt.%, and C is one of USY, beta and ZSM-5 molecular sieves. Under the conditions of 250 DEG C, 4 MPa H2 and 30 h, the alkane yield after conversion of the C-C bond dimer is greater than 74%. And after the lignin reacts at 300 DEG C for 12 hours, the yield of cycloalkane is greater than 39%. And converting the plastic, cellulose and hemicellulose raw materials into more than 35% of alkane, more than 40% of ethanol and more than 67% of cyclopentane at 250 DEG C for 12 hours.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial catalysis and bioenergy conversion, and particularly relates to a novel catalyst and a preparation method for catalyzing the high-value utilization of C—C bonds in organic solid wastes such as lignin, cellulose, hemicellulose and plastics. Background Art

[0002] With the advancement of global carbon neutrality goals, achieving efficient conversion and recycling of carbon resources has become a research focus in green chemistry and energy chemical engineering. Organic solid wastes such as lignin (agricultural and forestry waste, papermaking waste, etc.), cellulose (agricultural and forestry waste, papermaking waste, etc.), plastics (polyethylene, polystyrene, etc.) and hemicellulose (furfural) contain a large number of stubborn C-C bonds, and their selective cleavage is considered to be the core step in opening up biomass refining, plastic waste recycling and polyhydroxy small molecule reconstruction. However, compared with C-H and C-O bonds, the bond energy of C-C single bonds is usually as high as 90-100 kcal / mol, and the dual thermodynamic and kinetic limitations in catalytic cleavage are significant. Traditional thermal cracking processes often need to be carried out at high temperatures of 450°C, resulting in complex product distribution, high energy consumption and low carbon efficiency, which is not conducive to fine product control. Therefore, the development of C-C bond selective cleavage strategies under mild conditions below 300°C has become a key scientific issue.

[0003] Transition metal catalysis has been gradually applied to C–C bond cleavage research in recent years because it can provide multiple electron transfer, σ bond activation and π coordination induction mechanism. For example, studies have shown that the mesoporous multifunctional Ru / NbOPO4 catalyst can achieve one-pot cleavage of 5-5' bonds and CO bonds and CC bonds in lignin raw materials, producing 124-153% of monocyclic hydrocarbons, which is 1.2-1.5 times the yield of existing nitrobenzene oxidation methods. This high activity is due to the Ru particles, NbO x The species and acid sites promote the dissociation of hydrogen, the strong adsorption of substrates and intermediates, and the partial protonation and activation of adsorbed substrates (Chem, 2019, 5, 1521-1536), respectively, proving the unique advantages of metal-acid bifunctional catalysts for C-C bond cleavage. The Pt / WO3 / Al2O3 catalytic system developed by Jones et al. can crack polyethylene into C8–C 20Alkanes, with a carbon yield exceeding 70%, and excellent linear hydrocarbon selectivity exceeding 80% (Chem Catalysis, 2022, 3320-3356). In the field of cellulose conversion, Liu et al. (ChemSusChem, 2023, 16) used Ru / Nb2O5 catalyst to treat cellulose hydrolysate at 190°C and a hydrogen pressure of 2 MPa. Through targeted C–C bond cleavage, they obtained C2–C4 alcohols such as ethanol, 1,2-propylene glycol, and n-butanol, with a total alcohol molar yield of 56%. The study indicates that the hydrogen transfer-cleavage-rearrangement pathway in this reaction system is synergistically regulated by bifunctional catalytic sites and is the key to achieving efficient product regulation.

[0004] Despite initial success, developing a universal catalyst system for the high-value utilization of C-C bonds in diverse organic solid wastes remains a significant challenge. C-C bond cleavage reactions between highly stable units like β-β in lignin and C-C bonds in the backbones of cellulose, hemicellulose, and polyolefin plastics still rely on precious metals and high hydrogen pressures. Furthermore, the structure-activity relationship of transition metal catalysts (such as Ni, Co, and Cu) in these reactions has yet to be systematically established. Molecular sieves offer tunable acidity and moderate pore size. Combining zeolites as additives with metal active sites creates hybrid catalytic systems that address the limitations of limited acid sites and their limited number in metal catalysts. The composition, morphology, surface defect structure, and electronic properties of layered double hydroxides (LDHs, also known as hydrotalcites) can be finely tuned through specific strategies. In catalytic applications, the anchoring and trapping effects exhibited by LDHs are crucial for improving reaction efficiency. The anchoring effect refers to the stabilization of catalytically active species through strong interactions between the LDH layers, reducing the likelihood of loss or aggregation and thus better retaining active sites. The "trap" formed by the interlayer structure of LDHs can accommodate and restrict the diffusion of reactant molecules within the interlayer space, allowing them to remain near the active sites longer, significantly increasing the probability of collision with the active centers and reaction. This "trap" effect helps improve the conversion rate and selectivity of catalytic reactions. Summary of the Invention

[0005] To address the shortcomings of existing technologies and utilize catalyst surface structure control strategies, this invention innovatively synthesizes a transition metal catalyst with abundant, tunable acidic sites and enhanced metal-site electrons. A hydrothermal method is used to in situ construct a molecular sieve-grown transition metal-hydrotalcite catalyst and apply it to C-C bond cleavage reactions of various C-C dimers and organic solid waste feedstocks.

[0006] The present invention provides a preparation method of a transition metal hydrotalcite-molecular sieve composite catalyst and its application in catalyzing the breaking of CC bonds of different types of organic solid wastes.

[0007] The present invention aims to improve the yield of chemicals prepared by catalyzing the cleavage of various types of C-C bonds by transition metal catalysts under mild conditions. It proposes a strategy of regulating the surface and interface structure of molecular sieves and develops a transition metal catalyst constructed with the assistance of an in situ growth method.

[0008] The technical solutions of the present invention are as follows:

[0009] A transition metal hydrotalcite-molecular sieve composite catalyst is represented by M-Al2O3@C, wherein M-Al2O3 represents Al2O3-loaded metal nanoparticles, M is one of Ni, Cu, Co, Fe, Zn, Pt, Rh, Pd, Ir, Mo, Mg, and Sn, the mass ratio of M / (M-Al2O3@C) is 10-25wt.%, and C represents one of USY, β, and ZSM-5 having a porous structure.

[0010] The preparation method of the transition metal hydrotalcite-molecular sieve composite catalyst of the present invention comprises the following steps:

[0011] a) weighing molecular sieves and a mixed solvent of deionized water and ethanol, mixing them in a container and ultrasonically treating them until no solid particles are present to obtain a uniform slurry; then adding a transition metal nitrate hydrate, and stirring until urea is completely dissolved;

[0012] b) transferring the suspension obtained in a) into a polytetrafluoroethylene-lined stainless steel autoclave and hydrothermally growing the suspension at 100-130° C. for 16-28 hours; after the reaction, filtering and separating the resulting blue precipitate, washing the precipitate with water and ethanol multiple times, and then drying the precipitate to obtain the precursor MAl-LDH@C;

[0013] c) MAl-LDH@C was calcined in air at 450-600°C for 4-7 hours. After cooling to room temperature, the calcined oxide was transferred to a tube furnace, introduced with 50% H2 / N2, and reduced at 400-600°C for 4-7 hours to obtain the M-Al2O3@C catalyst.

[0014] In the preparation method, the volume ratio of deionized water to ethanol is 2:1-1:3, and the urea content is 0.03-0.06 g / ml.

[0015] In the preparation method, the Si / Al ratio of the molecular sieve is 6, the Na2O content is 0.3%, and the concentration of the molecular sieve in the mixed solvent is 0.0147-0.0433 g / ml.

[0016] In the preparation method, the flow rate of H2 / N2 during the reduction process is 50ml / 50ml.

[0017] The invention discloses an application of the transition metal hydrotalcite-molecular sieve composite catalyst in breaking CC bonds of organic solid waste.

[0018] Application of transition metal hydrotalcite-molecular sieve composite catalyst in C-C bond breaking of organic solid waste, comprising the following steps:

[0019] a) After mixing the reaction substrate, catalyst, internal standard and reaction solvent, add them into the reaction kettle, replace the gas in the kettle with hydrogen three times before the reaction starts, fill the pressure in the kettle with hydrogen to the target pressure of 3-5

[0020] MPa at room temperature;

[0021] b) Increase the temperature of the reaction kettle to 150-250 DEG C, and start stirring, the reaction time is 5h-30h;

[0022] c) After the reaction is completed, stop stirring and reduce to room temperature, then release the pressure and open the kettle, separate the liquid product and the catalyst, and use mass spectrometry-gas chromatography to qualitatively and quantitatively analyze the liquid product.

[0023] Application of the transition metal hydrotalcite-molecular sieve composite catalyst in C-C bond breaking of organic solid waste.

[0024] Application of the transition metal hydrotalcite-molecular sieve composite catalyst in C-C bond breaking conversion, the C-C bond dimer used in the reaction is one of 2,2'-diphenol, 2,4-dihydroxyphenyl benzyl ketone, benzyl-4-hydroxyphenone, bibenzyl, 2,2'-methylene-bis-(4-methylphenol), 2-phenylphenol, diphenylmethane, benzhydrol, 2-methoxy-1,1'-biphenyl.

[0025] The application of the transition metal hydrotalcite-molecular sieve composite catalyst in C-C bond breaking, characterized in that the mass ratio of the composite catalyst to the substrate is 1:2-3:2; the reaction solvent is selected from one of n-hexane, isopropyl alcohol and n-pentane.

[0026] The application of the transition metal hydrotalcite-molecular sieve composite catalyst in C-C bond breaking, characterized in that the lignin solid waste in the solid waste raw material used in the reaction is one of waste bamboo, sawdust, straw, wheat straw and bagasse lignin, the plastic used is one of PET, PE, PC, PP, PPO and PS, the cellulose solid waste used is one of waste bamboo, sawdust, straw, wheat straw and bagasse lignin, and the hemicellulose used is one of waste bamboo, sawdust, straw, wheat straw and bagasse hemicellulose.

[0027] The application has the following advantages:

[0028] 1. The transition metal hydrotalcite-molecular sieve composite catalyst described in the application is prepared from conventional and inexpensive chemicals, has low cost, and the preparation process is simple and easy to operate, and consumes less time, energy and materials.

[0029] 2. The catalyst of the present invention has a significant new structural feature, namely, the metal is loaded on the surface of alumina nanoflowers grown on the surface of a porous molecular sieve.

[0030] 3. The catalyst of the present invention exhibits excellent CC bond breaking ability under mild conditions. Under the reaction conditions of 250°C, 4MPa, and 30h, the alkane yields of the various CC bond dimers after conversion are all >74%. After reacting at 300°C for 12h, the conversion rate of different lignin solid waste raw materials is >50%, and the cycloalkane yield is >39%; after reacting at 250°C for 12h, the conversion rate of different plastic solid waste raw materials is >60%, and the alkane product yield is >35%; the conversion rate of different cellulose solid waste raw materials is >80%, and the ethanol product yield is >40%; the conversion rate of different hemicellulose solid waste raw materials is >80%, and the cyclopentane product yield is >67%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the transmission electron microscope (TEM) image of the catalyst sample described in Example 4.

[0032] Figure 2 This is the XRD pattern of the catalyst sample described in Example 4. DETAILED DESCRIPTION

[0033] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0034] Example 1

[0035] Preparation of 10wt.%Ni-Al2O3@USY composite catalyst

[0036] a) Weigh 2.6 g of USY zeolite with a silicon-aluminum ratio of 6 and place it in 60 ml of a solution of deionized water and ethanol in a volume ratio of 2:1. Ultrasonic treatment is used until no solid particles are present to form a uniform slurry. After uniform mixing, 1.45 g of Ni(NO3)2·6H2O and 3.6 g of urea are added to the slurry and stirred until completely dissolved. The resulting mixture is sealed in a PTFE autoclave and maintained at 100°C for 16 hours. After cooling to room temperature, the resulting solid is filtered and washed three times with deionized water and ethanol.

[0037] After drying, the composite structure precursor NiAl-LDH@USY was obtained;

[0038] b) calcining the composite structure precursor NiAl-LDH@USY at 450°C in air atmosphere for 4 h (heating rate 5°C / min) to obtain NiO-Al2O3@USY;

[0039] c) 1 g of NiO-Al2O3@USY was placed in a tube furnace, introduced with H2 / N2 flow (both at a flow rate of 50 ml / min), and reduced at 450°C for 4 h at a heating rate of 2°C / min. Then, it was slowly cooled to room temperature using N2 as a protective gas to obtain a catalyst with a Ni loading of 10 wt.%.

[0040] Example 2

[0041] Preparation of 20wt.%Ni-Al2O3@USY composite catalyst

[0042] a) 1.2 g of USY zeolite with a silicon-aluminum ratio of 6 was weighed and placed in 60 ml of a solution of deionized water and ethanol in a volume ratio of 1:2, and ultrasonicated until no solid particles were present to form a uniform slurry; after uniform mixing, 1.45 g of Ni(NO3)2·6H2O and 2.4 g of urea were added to the slurry and stirred until completely dissolved; the resulting mixture was sealed in a PTFE autoclave and maintained at 110°C for 24 h; after completion, the mixture was cooled to room temperature, the resulting solid was filtered, and washed three times with deionized water and ethanol.

[0043] After drying, the composite structure precursor NiAl-LDH@USY was obtained.

[0044] b) The composite structure precursor NiAl-LDH@USY was calcined at 550℃ in air atmosphere for 6h (heating rate 5℃ / min) to obtain NiO-Al2O3@USY.

[0045] c) 1 g of NiO-Al2O3@USY was placed in a tube furnace, introduced with H2 / N2 flow (both at a flow rate of 50 ml / min), and reduced at 550°C for 6 h at a heating rate of 2°C / min. The mixture was then slowly cooled to room temperature using N2 as a protective gas to obtain a catalyst with a Ni loading of 20 wt.%.

[0046] Example 3

[0047] Preparation of 25wt.%Ni-Al2O3@USY composite catalyst

[0048] a) 0.88 g of USY zeolite with a silicon-aluminum ratio of 6 was weighed and placed in 60 ml of a solution of deionized water and ethanol in a volume ratio of 1:3, and ultrasonically treated to form a uniform slurry. After uniform mixing, 1.45 g of Ni(NO3)2·6H2O and 1.8 g of urea were added to the slurry and stirred until completely dissolved. The resulting mixture was sealed in a PTFE autoclave and maintained at 130°C for 28 h. After cooling to room temperature, the resulting solid was filtered and washed three times with deionized water and ethanol, and dried to obtain the composite structure precursor NiAl-LDH@USY.

[0049] b) Calcination of the composite structure precursor NiAl-LDH@USY in air atmosphere at 600 °C for 7 h (heating rate 5 °C / min) to obtain NiO-Al2O3@USY.

[0050] c) 1 g of NiO-Al2O3@USY was placed in a tube furnace, H2 / N2 flow (flow rate of both 50 ml / min) was passed and reduced at 600 °C for 7 h with a heating rate of 2 °C / min, then slowly cooled to room temperature using N2 as a protective gas to obtain a catalyst with a Ni loading of 25 wt.%.

[0051] Example 4

[0052] Preparation of 15 wt.% Ni-Al2O3@USY composite catalyst

[0053] a) 1.6 g of USY zeolite with a silica-alumina ratio of 6 was weighed and placed in a solution of 60 ml of deionized water and ethanol in a volume ratio of 1 : 1, mixed, and treated with ultrasonic waves until a homogeneous slurry was formed without solid particles; after mixing well, 1.45 g of Ni(NO3)2-6H2O and 3 g of urea were added to the slurry and stirred until completely dissolved; the resulting mixture was sealed in a polytetrafluoroethylene high-pressure reaction kettle and kept at 120 °C for 20 h; after the end, it was cooled to room temperature, the resulting solid was filtered and washed three times with deionized water and ethanol, and dried to obtain the composite structure precursor NiAl-LDH@USY.

[0054] b) Calcination of the composite structure precursor NiAl-LDH@USY in air atmosphere at 500 °C for 5 h (heating rate 5 °C / min) to obtain NiO-Al2O3@USY.

[0055] c) 1 g of NiO-Al2O3@USY was placed in a tube furnace, H2 / N2 flow (flow rate of both 50 ml / min) was passed and reduced at 500 °C for 1 h with a heating rate of 2 °C / min, then slowly cooled to room temperature using N2 as a protective gas to obtain a catalyst with a Ni loading of 15 wt.%.

[0056] Example 5

[0057] Preparation of 15 wt.% M-Al2O3@USY composite catalyst, M being one of Cu, Co, Fe, Zn, Pt, Rh, Pd, Ir, Mo, Mg, Sn.

[0058] a) 1.6 g of USY zeolite with a silicon-aluminum ratio of 6 was weighed and placed in 60 ml of a solution with a volume ratio of deionized water and ethanol of 1:1, and ultrasonically treated until no solid particles were present to form a uniform slurry; after uniform mixing, 5 mmol of metal nitrate hydrate and 3 g of urea were added to the slurry and stirred until completely dissolved; the resulting mixture was sealed in a polytetrafluoroethylene autoclave and maintained at 120° C. for 20 h; after completion, the mixture was cooled to room temperature, the resulting solid was filtered, washed three times with deionized water and ethanol, and dried to obtain a composite structure precursor.

[0059] b) calcining the composite structure precursor at 500° C. in air atmosphere for 5 h (heating rate 5° C. / min) to obtain metal-USY oxide.

[0060] c) 1 g of metal-USY oxide was placed in a tube furnace, introduced with H2 / N2 flow (both at a flow rate of 50 ml / min) and reduced at 500°C for 1 h at a heating rate of 2°C / min, and then slowly cooled to room temperature using N2 as a protective gas to obtain different metal catalysts.

[0061] Example 6

[0062] Preparation of 15wt.% Ni-Al2O3@β and 15wt.% Ni-Al2O3@ZSM-5 composite catalysts

[0063] a) Weigh 1.6 g of β or ZSM-5 zeolite with a silicon-aluminum ratio of 6 and place it in 60 ml of a solution with a volume ratio of 1:1 of deionized water and ethanol, and use ultrasonic treatment until there are no solid particles to form a uniform slurry; after mixing evenly, add

[0064] 1.45 g of Ni(NO3)2·3H2O and 3 g of urea were stirred until completely dissolved; the resulting mixture was sealed in a polytetrafluoroethylene autoclave and maintained at 120°C for 20 h. After cooling to room temperature, the resulting solid was filtered and washed three times with deionized water and ethanol. After drying, the composite structure precursors NiAl-LDH@β and NiAl-LDH@ZSM-5 were obtained.

[0065] b) The composite structure precursor was calcined at 500°C in air atmosphere for 5 h (heating rate 5°C / min) to obtain the corresponding metal-molecular sieve oxide.

[0066] c) 1 g of metal-molecular sieve oxide was placed in a tube furnace, introduced with H2 / N2 flow (both at a flow rate of 50 ml / min) and reduced at 500°C for 1 h at a heating rate of 2°C / min, and then slowly cooled to room temperature using N2 as a protective gas to obtain a catalyst with β and ZSM-5 as supports.

[0067] Example 7

[0068] C-C bond cleavage reaction of 2,2'-biphenol as a C-C bond dimer

[0069] a) 0.1 g of the catalyst obtained in Example 4, 0.1 g of the reactant, and 10 mL of a n-hexane solution containing 0.125 mol / L n-dodecane were added to a 50 mL autoclave;

[0070] b) The air in the autoclave was replaced with hydrogen three times, and then hydrogen was added to the autoclave until the initial pressure was 4 MPa. The temperature was raised to 250°C, the stirring rate was 320 r / min, and the reaction time was 30 h;

[0071] c) After the reaction is completed, stirring is stopped and the temperature is lowered to room temperature. The pressure is then released and the kettle is opened to separate the liquid product and the catalyst. The liquid product is qualitatively and quantitatively analyzed by mass spectrometry-gas chromatography to calculate the yield of each reaction product, the total monomer yield and the alkane selectivity. The calculation formula is as follows:

[0072]

[0073] Total monomer yield = ∑ yield of each product

[0074]

[0075] The internal standard selected in this technical solution is n-dodecane, and the substrate concentration is 0.01 g / ml.

[0076] The reaction results are shown in Table 1

[0077] Table 1. Results of 2,2'-biphenol conversion catalyzed by the catalyst described in Example 4

[0078]

[0079] The results show that a catalyst with a Ni loading of 15 wt.% can effectively catalyze the cleavage of carbon-carbon bonds and the hydrodeoxygenation of 2,2'-biphenol, an inert compound, into monocyclic alkanes at a relatively mild reaction temperature of 250°C for 30 hours. Compared with existing technologies, the low-temperature catalytic reduction activity is significantly improved.

[0080] Example 8

[0081] C-C bond cleavage reaction of 2,2'-biphenol

[0082] The implementation scheme is basically the same as that of Example 7, except that the catalyst used is the catalyst described in Example 1. The reaction results are shown in Table 2.

[0083] Table 2. Results of 2,2'-biphenol conversion catalyzed by the catalyst described in Example 1

[0084]

[0085] Example 9

[0086] C-C bond cleavage of 2,2'-dihydroxybiphenyl

[0087] The procedure was essentially the same as in Example 7 except that the catalyst used was the catalyst described in Example 2. The results of the reaction are shown in Table 3.

[0088] Table 3. Results of the conversion of 2,2'-dihydroxybiphenyl catalyzed by the catalyst described in Example 2

[0089]

[0090] Example 10

[0091] C-C bond cleavage of 2,2'-dihydroxybiphenyl

[0092] The procedure was essentially the same as in Example 7 except that the catalyst used was the catalyst described in Example 3. The results of the reaction are shown in Table 4.

[0093] Table 4. Results of the conversion of 2,2'-dihydroxybiphenyl catalyzed by the catalyst described in Example 3

[0094]

[0095] Example 11

[0096] C-C bond cleavage of 2,2'-dihydroxybiphenyl

[0097] The procedure was essentially the same as in Example 7 except that the catalyst used was the catalyst described in Example 5. The results of the reaction are shown in Table 5.

[0098] Table 5. Results of the conversion of 2,2'-dihydroxybiphenyl catalyzed by the catalyst described in Example 5

[0099]

[0100] Example 12

[0101] C-C bond cleavage of 2,2'-dihydroxybiphenyl

[0102] The procedure was essentially the same as in Example 7 except that the catalyst used was the catalyst described in Example 6. The results of the reaction are shown in Table 6.

[0103] Table 6. Results of the conversion of 2,2'-dihydroxybiphenyl catalyzed by the catalyst described in Example 6

[0104]

[0105] Example 13

[0106] C-C bond cleavage reaction of 2,2'-biphenol

[0107] The implementation scheme is basically the same as Example 7, except that the reaction temperature is adjusted from 250°C to 200°C or 150°C. The reaction results are shown in Table 7.

[0108] Table 7. Results of 2,2'-biphenol conversion using the catalyst described in Example 4

[0109]

[0110] Example 14

[0111] C-C bond cleavage reaction of 2,2'-biphenol

[0112] The implementation scheme is basically the same as Example 7, except that the reaction time is adjusted from 30 h to 5 h, 10 h, 15 h, 20 h and 25 h. The reaction results are shown in Table 8.

[0113] Table 8. Results of 2,2'-biphenol conversion catalyzed by the catalyst described in Example 4

[0114]

[0115] Example 15

[0116] C-C bond cleavage reaction of 2,2'-biphenol

[0117] The implementation scheme is basically the same as Example 7, except that the catalyst / substrate mass ratio is adjusted from 1:1 to 1:2 and 3:2. The reaction results are shown in Table 9.

[0118] Table 9. Results of 2,2'-biphenol conversion catalyzed by the catalyst described in Example 4

[0119]

[0120]

[0121] Example 16

[0122] The implementation scheme is basically the same as Example 7, except that the solvent used in the reaction is replaced by one of n-pentane and isopropanol from n-hexane. The reaction results are shown in Table 10.

[0123] Table 10. Results of 2,2'-biphenol conversion catalyzed by the catalyst described in Example 4

[0124]

[0125] Example 17

[0126] C-C bond cleavage reaction of different C-C bond dimers

[0127] The implementation is basically consistent with example 7, except that the reaction substrate is replaced by 0.1g of one of 2,4-dihydroxyphenyl benzyl ketone, benzyl-4-hydroxyphenone, bibenzyl, 2,2'-methylene-bis-(4-methylphenol), diphenylmethane, benzhydrol, 2-phenylphenol, 2-methoxy-1,1'-biphenyl, biphenyl, and the reaction results are shown in Table 11.

[0128] Table 11. Conversion results of different C-C bond dimers catalyzed by the catalyst described in Example 4

[0129]

[0130] Table 9 shows that under the reaction conditions described: 250℃, hydrogen pressure 4MPa, reaction time 30h, composite catalyst: substrate mass ratio 1:1, the Ni-based hydrotalcite-molecular sieve composite catalyst can efficiently catalyze the hydrogenolysis of β-1, α-5, α-1, 5-5 four types of C-C bond model compounds to generate monocyclic compounds, and the total monomer yield is >74%.

[0131] Example 18

[0132] C-C bond cleavage reaction of different lignins

[0133] The implementation is basically consistent with example 7, except that the reaction substrate is replaced by 0.1g of one of waste bamboo, wood chips, straw, wheat straw, and bagasse lignin, and the reaction conditions are changed to 300℃, 4MPa H2, 12h, and the reaction results are shown in Table 12.

[0134] Table 12. Conversion results of lignin catalyzed by the catalyst described in Example 4

[0135]

[0136] Tables 10 and 11 show that the transition metal-based hydrotalcite-molecular sieve composite catalyst has a strong catalytic depolymerization effect on common lignin, and the conversion rate is >50% and the naphthene yield is >39%.

[0137] Example 19

[0138] The implementation is basically consistent with example 7, except that the reaction substrate is replaced by 0.1g of one of plastic PE, PC, PP, PPO, PET, and PS, and the reaction conditions are changed to 250℃, 4MPa H2, 12h, and the reaction results are shown in Table 13.

[0139] Table 13. Conversion results of different plastics catalyzed by the catalyst described in Example 4

[0140]

[0141] The results show that the catalyst can efficiently catalyze the breaking of CC bonds in different plastics into alkanes at a relatively mild reaction temperature of 250°C for 12 hours. Compared with existing technologies, the low-temperature catalytic reduction activity is significantly improved.

[0142] Example 20

[0143] The implementation scheme is basically the same as Example 7, except that the reaction substrate is replaced with 0.1 g of waste bamboo, sawdust, rice straw, wheat straw, or bagasse cellulose, and the reaction conditions are changed to 250° C., 4 MPa H2, 12 h. The reaction results are shown in Table 14.

[0144] Table 14. Cellulose conversion results catalyzed by the catalyst described in Example 4

[0145]

[0146] Example 21

[0147] The implementation scheme is basically the same as Example 7, except that the reaction substrate is replaced with 0.1 g of waste bamboo, sawdust, rice straw, wheat straw, and bagasse hemicellulose, and the reaction conditions are changed to 250°C, 4 MPa H2, 12 h. The reaction results are shown in Table 15.

[0148] Table 15. Results of hemicellulose conversion catalyzed by the catalyst described in Example 4

[0149]

[0150] The results in Tables 14-15 show that the catalyst can efficiently catalyze the conversion of different celluloses and hemicelluloses at a relatively mild reaction temperature of 250°C for 12 hours. Compared with existing technologies, the low-temperature catalytic reduction activity is significantly improved.

[0151] The technical solutions disclosed and proposed by the present invention can be implemented by those skilled in the art by drawing on the content of this document and appropriately changing the conditions, routes, and other aspects. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, it is obvious that those skilled in the art can modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of the present invention to achieve the ultimate preparation technology. It is particularly important to point out that all similar substitutions and modifications that are obvious to those skilled in the art are considered to be included in the spirit, scope, and content of the present invention.

Claims

1. A transition metal hydrotalcite-molecular sieve composite catalyst, characterized in that: Expressed as M-Al2O3@C, where M-Al2O3 represents flower-shaped Al2O3 loaded with metal nanoparticles, M is one of Ni, Cu, Co, Fe, Zn, Pt, Rh, Pd, Ir, Mo, Mg, Sn, the mass ratio of M / (M-Al2O3@C) is 10-25wt.%, and C represents one of USY, β, ZSM-5 molecular sieves with a porous structure.

2. The method for preparing the transition metal hydrotalcite-molecular sieve catalyst according to claim 1, characterized in that: The steps include: a) weighing molecular sieves and a mixed solvent of deionized water and ethanol, mixing them in a container and ultrasonically treating them until no solid particles are present to obtain a uniform slurry; then adding the nitrate hydrate of the metal M and stirring the urea until it is completely dissolved; b) transferring the suspension obtained in a) into a polytetrafluoroethylene-lined stainless steel autoclave and hydrothermally growing the suspension at 100-130° C. for 16-28 h; After the reaction, the blue precipitate was separated by filtration, washed with water and ethanol several times, and then dried to obtain the flower-like precursor MAl-LDH@C; c) calcining MAl-LDH@C in an air atmosphere at 450-600°C for 4-7 hours; after cooling to room temperature, transferring the calcined metal-molecular sieve oxide to a tubular furnace, introducing 50% H2 / N2, and reducing at 450-600°C for 4-7 hours to obtain the M-Al2O3@C catalyst.

3. The preparation method according to claim 2, wherein: The volume ratio of deionized water to ethanol is 2:1-1:3, and the urea content is 0.03-0.06 g / ml.

4. The preparation method according to claim 2, wherein: The Si / Al ratio of the molecular sieve is 6, the Na2O content is 0.3%, and the concentration in the mixed solvent is 0.0147-0.0433 g / ml.

5. The preparation method according to claim 2, wherein the reduction The flow rate of H2 / N2 during the process is 50ml / 50ml.

6. Use of the transition metal hydrotalcite-molecular sieve composite catalyst according to claim 1 in the cleavage of C—C bonds in organic solid waste.

7. Use of the transition metal hydrotalcite-molecular sieve composite catalyst according to claim 6 in the cleavage of C—C bonds in organic solid waste, characterized in that: The steps include: a) the reaction substrate, catalyst, internal standard substance and reaction solvent are fully mixed and added to a reactor, and the gas in the reactor is replaced with hydrogen three times before the reaction starts, and the pressure in the reactor is filled with hydrogen to a target pressure of 3-5 MPa at room temperature; b) heating the reactor to 150-300°C and starting stirring. The reaction time is 5h-30h; c) After the reaction is completed, stirring is stopped and the temperature is lowered to room temperature, and then the pressure is released and the kettle is opened to separate the liquid product and the catalyst. The liquid product is qualitatively and quantitatively analyzed by mass spectrometry-gas chromatography.

8. Use of the transition metal hydrotalcite-molecular sieve composite catalyst in the cleavage of C—C bonds in organic solid waste as claimed in claim 6, characterized in that: The CC bond dimer is one of 2,2'-biphenol; 2,4-dihydroxyphenylbenzyl ketone; benzyl-4-hydroxybenzophenone; bibenzyl; 2,2'-methylene-bis-(4-methylphenol); 2-phenylphenol; diphenylmethane; benzhydrol; and 2-methoxy-1,1'-biphenyl.

9. Use of the transition metal hydrotalcite-molecular sieve composite catalyst in breaking C—C bonds of organic solid waste as claimed in claim 6, characterized in that: The mass ratio of the composite catalyst to the substrate is 1:2-3:2; the reaction solvent is n-hexane, and the internal standard substance is n-dodecane.

10. The use of the transition metal-based hydrotalcite-molecular sieve composite catalyst in C-C bond cleavage, characterized in that: The lignin solid waste in the solid waste raw materials used in the reaction is one of waste bamboo, sawdust, rice straw, wheat straw, and bagasse lignin; the plastic used is one of PET, PE, PC, PP, PPO, and PS; the cellulose solid waste used is one of waste bamboo, sawdust, rice straw, wheat straw, and bagasse lignin; and the hemicellulose used is one of waste bamboo, sawdust, rice straw, wheat straw, and bagasse hemicellulose.

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