A lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, its preparation method and application

Abstract

This invention discloses a lanthanide-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, its preparation method, and its applications. The catalyst comprises a support and an active component loaded on the support, wherein the support is attapulgite-based titanium silicate zeolite, and the active component is cobalt and a lanthanide metal. The catalyst of this invention is applied to the catalytic depolymerization of lignin to guaiacol. Under conditions of water, glycerol, and formic acid solvents, nitrogen atmosphere, and without the need for an additional hydrogen source, it can achieve 100% lignin conversion, with a guaiacol yield greater than 25% and a guaiacol-like product yield greater than 75%. It has the advantages of high economic efficiency and low metal loading, and can improve the catalyst's depolymerization ability and selectivity for lignin, showing good prospects for industrial application.

Description

Technical Field

[0001] This invention relates to the field of lignin depolymerization technology, and in particular to a lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, its preparation method, and its application. Background Technology

[0002] Biomass refers to any organic matter and its metabolic products produced by living organisms, and is the only renewable organic carbon resource in nature. Lignin, an amorphous polymer composed of phenylpropane units linked by C-C and CO bonds, is the main component of lignocellulose biomass. Converting lignin into biofuels and compounds can alleviate current energy pressures.

[0003] Catalytic depolymerization of lignin to obtain chemicals via pyrolysis, catalytic acid or alkaline hydrolysis, and hydrogenation is currently a hot research topic. Among these methods, hydrodeoxygenation is one of the most commonly used and effective methods for depolymerizing lignin into phenols and other chemical substances. Guaiacin is frequently found in lignin oil extracts and is characterized by the presence of methoxy and phenolic hydroxyl groups, typical of lignin.

[0004] The transition metal cobalt is inexpensive compared to precious metals and possesses good lignin CC / CO decomposition and hydrogenation capabilities, making it widely used in the catalytic conversion of lignin. However, its catalytic activity is still not ideal, and its selectivity for guaiacol is not high. Summary of the Invention

[0005] The main objective of this invention is to provide a lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst with stronger catalytic activity and higher selectivity for guaiacol, as well as its preparation method and application.

[0006] To achieve the above objectives, the present invention provides a lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, comprising a support and an active component supported on the support, wherein the support is attapulgite-based titanium silicate zeolite, and the active component is cobalt and lanthanide metals.

[0007] Furthermore, the cobalt content is 10 wt%, the lanthanide metal content is 1–10 wt%, and the balance is attapulgite-based titanium silicate zeolite.

[0008] Furthermore, the lanthanide metals are cerium, lanthanum, or samarium.

[0009] This invention also provides a method for preparing the above-mentioned lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, comprising the following steps:

[0010] S1. Add the acid-treated attapulgite to a tetrapropylammonium hydroxide aqueous solution and stir to obtain a colorless and transparent solution, denoted as solution A; add tetrabutyl titanate to isopropanol, mix well, then add a tetrapropylammonium hydroxide aqueous solution and stir to obtain a colorless and transparent solution, denoted as solution B.

[0011] S2. Mix solution A and solution B, stir first, then heat to remove alcohol, then add water and stir to age the mixture to obtain an aged mixture.

[0012] S3. The aged mixture is subjected to crystallization treatment, and the resulting product is washed, dried and calcined to obtain attapulgite-based titanium silicate zeolite.

[0013] S4. The precursor salt of cobalt, the precursor salt of lanthanides, the attapulgite-based titanium silicate zeolite and the solvent are mixed, stirred first, then the solvent is evaporated and dried, and finally calcined to obtain the lanthanide-modified cobalt / attapulgite-based titanium silicate zeolite catalyst.

[0014] Further, in step (1), the mass-volume ratio of acid-treated attapulgite, tetrabutyl titanate, and tetrapropylammonium hydroxide is 1g:0.1-0.5ml:2.5-5g.

[0015] Furthermore, in step (2), the stirring treatment time is 1 to 2 hours; the heating temperature for alcohol removal is 80 to 90°C and the time is 1 to 2 hours; the stirring aging treatment time is 12 to 24 hours.

[0016] Further, in step (3), the crystallization treatment conditions are a temperature of 150℃~200℃ and a time of 24~36h; the specific process of the calcination treatment is: heating to 550~700℃ in an air atmosphere at a heating rate of 1~5℃ / min, and then calcining at this temperature for 5~10h.

[0017] Further, in step (4), the stirring treatment is carried out at room temperature for 6 to 12 hours; the drying treatment is carried out at a temperature of 80 to 110°C for 12 to 24 hours.

[0018] Further, in step (4), the specific process of calcination is as follows: the temperature is raised to 500-700°C in an air atmosphere at a heating rate of 1-5°C / min, and then calcined at this temperature for 5-10 hours.

[0019] The present invention also provides the application of the above-mentioned lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst in the catalytic depolymerization of lignin to prepare guaiacol.

[0020] The present invention also provides a method for preparing guaiacol by depolymerization of lignin, comprising the following steps: adding lignin, water, glycerol, formic acid and the above-mentioned catalyst into a reactor, purging with nitrogen and then carrying out a sealed reaction.

[0021] Furthermore, the reaction conditions are: temperature 210–310℃, stirring rate 400–600 r / min, and time 1–24 h.

[0022] The catalyst of this invention uses attapulgite-based titanium silicate zeolite as a support, and cobalt and lanthanide metals (cerium, lanthanum and samarium) as active components, which can enhance the catalyst's ability to crack lignin. Attapulgite-based titanium silicate zeolite has uniform and ordered microporous channels, a large specific surface area and ion exchange performance. The regular pores, high thermal stability and structural defects of the molecular sieve can effectively disperse and anchor metals, and inhibit agglomeration and sintering.

[0023] Cobalt, a transition metal catalyst, possesses a unique structure and properties. Its low cost and suitable hydrogenation activity have led to its application in the hydrodeoxygenation of lignin. Cobalt-based metal catalysts exhibit excellent performance in cleaving CO / CC bonds and activating solvents. Lanthanides possess efficient oxygen storage and redox release properties. Metal interactions lead to the generation of oxygen vacancies, which can adsorb intermediate products in a specific manner. Simultaneously, the addition of lanthanides generates electron transfer between metals, enhancing the interaction between the metal and the support, thus improving the hydrogenation capacity of cobalt and the catalytic depolymerization efficiency of lignin.

[0024] The beneficial effects of this invention are reflected in:

[0025] The catalyst of this invention is applied to the catalytic depolymerization of lignin to prepare guaiacol. Under the conditions of water, glycerol and formic acid solvents, nitrogen atmosphere, and no additional hydrogen source, it can achieve 100% lignin conversion, with guaiacol yield greater than 25% and guaiacol-like product yield greater than 75%. It has high economic benefits, low metal loading, and can improve the catalyst's depolymerization ability and selectivity for lignin, showing good prospects for industrial application. Attached Figure Description

[0026] Figure 1 The image shows the XRD pattern of the attapulgite-based titanium silicate zeolite prepared in Example 1.

[0027] Figure 2 The image shows the FTIR spectrum of the attapulgite-based titanium silicate zeolite prepared in Example 1.

[0028] Figure 3 The N2 adsorption-desorption isotherm of the attapulgite-based titanium silicate zeolite prepared in Example 1 is shown.

[0029] Figure 4 The image shows the pore size distribution of the attapulgite-based titanium silicate zeolite prepared in Example 1.

[0030] Figure 5 The images show the electron paramagnetic resonance (EPR) patterns of the attapulgite-based titanium silicate zeolite, catalyst C1, and catalyst D1 prepared in Example 1.

[0031] Figure 6 The image shows the XRD pattern of the final product of step S3 in Comparative Example 5. Detailed Implementation

[0032] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0033] Unless otherwise specified, all raw materials used in the embodiments of the present invention are commercially available or obtainable by those skilled in the art; unless otherwise specified, all methods used in the embodiments of the present invention are methods mastered by those skilled in the art.

[0034] Example 1

[0035] Preparation of lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalysts

[0036] The catalyst prepared in this embodiment has a cobalt content of 10 wt% and a cerium content of 1 wt%, with the remaining component being attapulgite-based titanium silicate zeolite. The preparation method is as follows:

[0037] S1. Place 20g of attapulgite in 120mL of 3.5mol / L hydrochloric acid solution and treat at 170℃ for 12h. Then transfer it to a hydrothermal synthesis reactor and treat it hydrothermally at 180℃ for 72h. After centrifugation and washing, dry at 105℃ for 12h to obtain acid-treated attapulgite.

[0038] Mix 2.5g of tetrapropylammonium hydroxide with 15ml of deionized water, and then slowly add 2g of acid-treated attapulgite in batches at room temperature and stirring speed of 500r / min. Continue stirring at 400r / min for 2h to obtain a colorless and transparent solution, denoted as solution A.

[0039] Mix 2.5g of tetrapropylammonium hydroxide with 15ml of deionized water, then add an ester solution consisting of 0.5ml of tetrabutyl titanate and 10ml of isopropanol. Stir at 400 r / min for 1h at room temperature to obtain a colorless and transparent solution, denoted as solution B.

[0040] S2. Mix solution A and solution B, stir at 400 r / min for 1 h at room temperature, then stir at 400 r / min for 2 h at 80 °C to remove the alcohols generated and the added isopropanol. Add deionized water to make up to 30 ml, and age at 350 r / min for 24 h at room temperature to obtain an aged mixture.

[0041] S3. The aged mixture was transferred to a reaction vessel and crystallized at 180°C for 36 hours. The solid product was centrifuged, washed with deionized water, dried at 105°C for 12 hours, and finally calcined at 550°C for 6 hours in air at a heating rate of 3°C / min to obtain attapulgite-based titanium silicate zeolite.

[0042] S4. Add 0.4938g of cobalt nitrate hexahydrate to 50mL of deionized water and stir until homogeneous. Add 1g of attapulgite-based titanium silicate zeolite and stir until homogeneous. Then add 0.0310g of cerium nitrate hexahydrate. Stir at 400 r / min for 6 hours at room temperature, then evaporate the water at 80℃ and dry at 80℃ for 24 hours. Grind the dried solid into powder and calcine it at 500℃ in air at a heating rate of 5℃ / min for 10 hours to obtain the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, designated C1.

[0043] Example 2

[0044] Preparation of lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalysts

[0045] The catalyst prepared in this embodiment has a cobalt content of 10 wt% and a cerium content of 5 wt% as active components, with the remaining component being attapulgite-based titanium silicate zeolite as a support. The preparation method is as follows:

[0046] S1. Mix 3.0g of tetrapropylammonium hydroxide with 15ml of deionized water, and then slowly add 2g of acid-treated attapulgite (prepared by the same method as in Example 1) in batches at room temperature and stirring speed of 500r / min. Continue stirring at 400r / min for 2h to obtain a colorless and transparent solution, which is denoted as solution A.

[0047] Mix 3.0 g of tetrapropylammonium hydroxide with 15 ml of deionized water, then add an ester solution consisting of 0.6 ml of tetrabutyl titanate and 10 ml of isopropanol. Stir at 400 r / min for 1 h at room temperature to obtain a colorless and transparent solution, denoted as solution B.

[0048] S2. Mix solution A and solution B, stir at 400 r / min for 1.5 h at room temperature, then stir at 400 r / min for 1 h at 90 °C to remove the alcohols generated and the added isopropanol. Add deionized water to make up to 30 ml, and age at 350 r / min for 22 h at room temperature to obtain an aged mixture.

[0049] S3. The aged mixture was transferred to a reaction vessel and crystallized at 150°C for 32 hours. The solid product was centrifuged, washed with deionized water, dried at 105°C for 12 hours, and finally calcined at 600°C for 10 hours in air at a heating rate of 1°C / min to obtain attapulgite-based titanium silicate zeolite.

[0050] S4. Add 0.4938g of cobalt nitrate hexahydrate to 50mL of deionized water and stir until homogeneous. Add 1g of attapulgite-based titanium silicate zeolite and stir until homogeneous. Then add 0.1550g of cerium nitrate hexahydrate. Stir at 400 r / min for 12h at room temperature. Then evaporate the water at 80℃ and dry at 105℃ for 12h. Grind the dried solid into powder and calcine it at 500℃ in air at a heating rate of 3℃ / min for 6h to obtain the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, designated C2.

[0051] Example 3

[0052] Preparation of lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalysts

[0053] The catalyst prepared in this embodiment has an active component content of 10 wt% cobalt and 10 wt% cerium, with the remaining component being attapulgite-based titanium silicate zeolite. The preparation method is as follows:

[0054] S1. Mix 3.5g of tetrapropylammonium hydroxide with 15ml of deionized water, and then slowly add 2g of acid-treated attapulgite (preparation method is the same as in Example 1) in batches at room temperature and stirring speed of 500r / min. Continue stirring at 400r / min for 2h to obtain a colorless and transparent solution, which is denoted as solution A.

[0055] Mix 3.5g of tetrapropylammonium hydroxide with 15ml of deionized water, then add an ester solution consisting of 0.8ml of tetrabutyl titanate and 10ml of isopropanol. Stir at 400 r / min for 1h at room temperature to obtain a colorless and transparent solution, denoted as solution B.

[0056] S2. Mix solution A and solution B, stir at 400 r / min for 2 h at room temperature, then stir at 400 r / min for 1.5 h at 85 °C to remove the alcohols generated and the added isopropanol. Add deionized water to make up to 30 ml, and age at 350 r / min for 20 h at room temperature to obtain an aged mixture.

[0057] S3. The aged mixture was transferred to a reaction vessel and crystallized at 170°C for 28 hours. The solid product was centrifuged, washed with deionized water, dried at 105°C for 12 hours, and finally calcined at 650°C for 8 hours in air at a heating rate of 2°C / min to obtain attapulgite-based titanium silicate zeolite.

[0058] S4. Add 0.4938g of cobalt nitrate hexahydrate to 50mL of deionized water and stir until homogeneous. Add 1g of attapulgite-based titanium silicate zeolite and stir until homogeneous. Then add 0.3099g of cerium nitrate hexahydrate. Stir at 400 r / min for 8 hours at room temperature. Then evaporate the water at 80℃ and dry at 90℃ for 20 hours. Grind the dried solid into powder and calcine it at 550℃ in air at a heating rate of 4℃ / min for 8 hours to obtain the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, designated C3.

[0059] Example 4

[0060] Preparation of lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalysts

[0061] The catalyst prepared in this embodiment has a cobalt content of 10 wt% and a lanthanum content of 5 wt%, with the remaining component being attapulgite-based titanium silicate zeolite. The preparation method is as follows:

[0062] S1. Mix 4.5g of tetrapropylammonium hydroxide with 15ml of deionized water, and then slowly add 2g of acid-treated attapulgite (preparation method is the same as in Example 1) in batches at room temperature and stirring speed of 500r / min. Continue stirring at 400r / min for 2h to obtain a colorless and transparent solution, which is denoted as solution A.

[0063] Mix 4.5g of tetrapropylammonium hydroxide with 15ml of deionized water, then add an ester solution consisting of 0.9ml of tetrabutyl titanate and 10ml of isopropanol. Stir at 400 r / min for 1h at room temperature to obtain a colorless and transparent solution, denoted as solution B.

[0064] S2. Mix solution A and solution B, stir at 400 r / min for 1.5 h at room temperature, then stir at 400 r / min for 1 h at 90 °C to remove the alcohols generated and the added isopropanol. Add deionized water to make up to 30 ml, and age at 350 r / min for 18 h at room temperature to obtain an aged mixture.

[0065] S3. The aged mixture was transferred to a reaction vessel and crystallized at 200°C for 24 hours. The solid product was centrifuged, washed with deionized water, dried at 105°C for 12 hours, and finally calcined at 700°C for 5 hours in air at a heating rate of 4°C / min to obtain attapulgite-based titanium silicate zeolite.

[0066] S4. Add 0.4938g of cobalt nitrate hexahydrate to 50mL of deionized water and stir until homogeneous. Add 1g of attapulgite-based titanium silicate zeolite and stir until homogeneous. Then add 0.1169g of lanthanum nitrate hexahydrate. Stir at 400 r / min for 10h at room temperature. Then evaporate the water at 80℃ and dry at 100℃ for 15h. Grind the dried solid into powder and calcine it at 600℃ in air at a heating rate of 2℃ / min for 5h to obtain the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, designated C4.

[0067] Example 5

[0068] Preparation of lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalysts

[0069] The catalyst prepared in this embodiment has a cobalt content of 10 wt% and a samarium content of 5 wt%, with the remaining component being attapulgite-based titanium silicate zeolite. The preparation method is as follows:

[0070] S1. Mix 5.0g of tetrapropylammonium hydroxide with 15ml of deionized water, and then slowly add 2g of acid-treated attapulgite (preparation method is the same as in Example 1) in batches at room temperature and stirring speed of 500r / min. Continue stirring at 400r / min for 2h to obtain a colorless and transparent solution, which is denoted as solution A.

[0071] Mix 5.0 g of tetrapropylammonium hydroxide with 15 ml of deionized water, then add an ester solution consisting of 1.0 ml of tetrabutyl titanate and 10 ml of isopropanol. Stir at 400 r / min for 1 h at room temperature to obtain a colorless and transparent solution, denoted as solution B.

[0072] S2. Mix solution A and solution B, stir at 400 r / min for 2 h at room temperature, then stir at 400 r / min for 2 h at 80 °C to remove the alcohols generated and the added isopropanol. Add deionized water to make up to 30 ml, and age at 350 r / min for 16 h at room temperature to obtain an aged mixture.

[0073] S3. The aged mixture was transferred to a reaction vessel and crystallized at 190°C for 26 hours. The solid product was centrifuged, washed with deionized water, dried at 105°C for 12 hours, and finally calcined at 600°C for 9 hours in air at a heating rate of 5°C / min to obtain attapulgite-based titanium silicate zeolite.

[0074] S4. Add 0.4938g of cobalt nitrate hexahydrate to 50mL of deionized water and stir until homogeneous. Add 1g of attapulgite-based titanium silicate zeolite and stir until homogeneous. Then add 0.1478g of samarium nitrate hexahydrate. Stir at 400 r / min for 9h at room temperature. Then evaporate the water at 80℃ and dry at 100℃ for 14h. Grind the dried solid into powder and calcine it at 700℃ in air at a heating rate of 1℃ / min for 5h to obtain the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst, designated C5.

[0075] Comparative Example 1

[0076] Preparation of comparative catalysts

[0077] The catalyst in this comparative example was prepared using the same method as in Example 2, except that the addition of cerium nitrate hexahydrate was omitted. The final catalyst obtained was a cobalt content of 10 wt% and the remaining component was attapulgite-based titanium silicate zeolite, designated as D1.

[0078] Comparative Example 2

[0079] Preparation of comparative catalysts

[0080] The catalyst in this comparative example was prepared according to the same method as in Example 2, except that the addition of cerium nitrate hexahydrate was omitted and the amount of cobalt nitrate hexahydrate was adjusted to 0.7408 g, resulting in a catalyst with a cobalt content of 15 wt% and the remaining components being attapulgite-based titanium silicate zeolite, designated as D2.

[0081] Comparative Example 3

[0082] Preparation of comparative catalysts

[0083] The catalyst in this comparative example was prepared according to the same method as in Example 2, except that cerium nitrate hexahydrate was replaced with niobium oxalate hexahydrate, and the amount of niobium oxalate hexahydrate was 0.2895 g. The final catalyst obtained was a cobalt content of 10 wt%, a niobium content of 5%, and the remaining component being attapulgite-based titanium silicate zeolite, designated as D3.

[0084] Comparative Example 4

[0085] Preparation of comparative catalysts

[0086] The catalyst in this comparative example was prepared according to the same method as in Example 2, except that cerium nitrate hexahydrate was replaced with zirconium nitrate hexahydrate, and the amount of zirconium nitrate hexahydrate was 0.2353 g. The final catalyst obtained was a cobalt content of 10 wt%, a zirconium content of 5 wt%, and the remaining component was attapulgite-based titanium silicate zeolite, designated as D4.

[0087] Comparative Example 5

[0088] Preparation of comparative catalysts

[0089] The catalyst in this comparative example was prepared using the same method as in Example 2, except that the template agent tetrapropylammonium hydroxide was replaced with an equal amount of tetraethylammonium bromide. The resulting catalyst is designated as D5.

[0090] Experimental Example 1

[0091] Structural determination of attapulgite-based titanium silicate zeolite catalysts

[0092] The structural analysis of the attapulgite-based titanium silicate zeolite carrier prepared in Example 1 was performed, and the results are as follows:

[0093] See Figure 1 XRD patterns of attapulgite-based titanium silicate zeolite Figure 2 The peaks at θ = 7.9°, 8.8°, 23.1°, 23.9° and 24.4° correspond to the characteristic crystal planes (101), (200), (501), (303) and (313) of the MFI structure of titanium silicate zeolite, proving that titanium silicate zeolite materials can be successfully prepared using attapulgite as a silicon source.

[0094] See Figure 2 In the FTIR spectrum of attapulgite-based titanium silicate zeolite, at 3452 cm⁻¹ -1 The nearby broadband frequency band belongs to the stretching vibration of -OH from titanium silicate zeolite, while at 1631 cm⁻¹... -1 The distinct peak at 450 cm⁻¹ belongs to the -OH vibration of adsorbed water. Meanwhile, at 450 cm⁻¹... -1 The peak value at 1100 cm⁻¹ is attributed to the internal asymmetric Si-O-Si bending vibration, while at 1100 cm⁻¹... -1 and 798 cm -1The vibrational mode is related to the externally symmetrical Si-O-Si bond bending. For titanium silicate zeolite, 1229 cm⁻¹ -1 and 549 cm -1 The nearby bands belong to the double pentagonal ring vibrations of TiO4 and SiO4 in the MFI topology. Furthermore, at 983 cm⁻¹... -1 The nearby peaks correspond to the stretching vibrations of the Si-O-Ti bonds in the MFI topology. FTIR spectroscopy further confirms the successful synthesis of attapulgite-based titanium silicate zeolite with the MFI topology.

[0095] See Figure 3 According to the IUPAC classification, attapulgite-based titanium silicate zeolite exhibits type I and type IV isotherms and possesses a type H4 hysteresis loop. This indicates that the synthesized attapulgite-based titanium silicate zeolite possesses a composite pore structure consisting of ordered micropores and mesopores formed by zeolite layer stacking.

[0096] See Figure 4 Meanwhile, the specific surface area, pore volume, and pore size of attapulgite and attapulgite-based titanium silicate zeolite were measured. The results are shown in Figure 1. Compared with attapulgite raw material, attapulgite-based titanium silicate zeolite has a significantly increased specific surface area, and its pore size has changed from a mesoporous structure to an ordered micro-mesoporous structure, showing a pore size distribution concentrated at 2.1 nm. This further proves the existence of this microporous-mesoporous composite pore structure, which is beneficial to promoting the dispersion of active metals on the surface of the support and promoting reaction mass transfer.

[0097] Table 1

[0098]

[0099] Note: A1 is attapulgite; A2 is acid-treated attapulgite; A3 is attapulgite-based titanium silicate zeolite.

[0100] Electron paramagnetic resonance (EPR) analysis was performed on the attapulgite-based titanium silicate zeolite and C1 catalyst prepared in Example 1, as well as the D1 catalyst prepared in Comparative Example D1. The results are as follows:

[0101] See Figure 5 The EPR signal at g = 2.003 corresponds to the presence of oxygen vacancy sites. The signal intensity of the C1 catalyst is significantly greater than that of D1 and attapulgite-based titanium silicate zeolite, confirming that lanthanide metal doping promotes the formation of a large number of oxygen vacancy sites. These oxygen-rich vacancies can adsorb intermediate products in the reaction process in a specific manner, which is beneficial to promoting the formation of the target product.

[0102] The final product of step S3 in the preparation process of Comparative Example 5 was measured, and the results are as follows:

[0103] See Figure 6The XRD pattern did not show the structure of titanium silicate zeolite, indicating that the synthesis of attapulgite-based titanium silicate zeolite was unsuccessful after changing the template agent.

[0104] Experiment Example 2

[0105] Catalytic performance testing of lignin depolymerization catalyst in the preparation of guaiacol

[0106] Test method: Weigh 1g of lignin, 0.1-0.5g of catalyst, 10-30ml of water and glycerol, and 0.1-0.5ml of formic acid into a high-pressure reactor, where the volume ratio of water to glycerol is 1:1-6. Introduce an initial nitrogen pressure of 0.1-0.5MPa, then heat to 270-350℃ within 30 minutes, and react under sealed conditions at a stirring rate of 500r / min for 3-12 hours. After the reaction is complete, cool in water, then extract the reaction product with ethyl acetate. After standing and separating the layers, separate the ethyl acetate layer. Pass the ethyl acetate layer through a chromatography column containing anhydrous sodium sulfate to remove any remaining water. Finally, remove the ethyl acetate by rotary evaporation at 45℃ and 70r / min. Quantitatively analyze the rotary evaporation product. Specific reaction conditions and results are shown in Table 2.

[0107] Table 2

[0108]

[0109] The results above show that, without an additional hydrogen source, the catalyst of this invention can achieve complete lignin conversion in a water, glycerol and formic acid solvent system, achieving a 100% lignin conversion rate. Among these results, the yield of guaiacol exceeds 25%, and the yield of guaiacol derivatives exceeds 75%.

[0110] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A lanthanide-modified cobalt / attapulgite-based titanium silicate zeolite catalyst for catalyzing the depolymerization of lignin to prepare guaiacol, characterized in that, The zeolite comprises a support and an active component loaded on the support, wherein the support is attapulgite-based titanium silicate zeolite, and the active component is cobalt and lanthanide metals; the preparation method of the attapulgite-based titanium silicate zeolite includes the following steps: S1. Add the acid-treated attapulgite to a tetrapropylammonium hydroxide aqueous solution and stir to obtain a colorless and transparent solution, denoted as solution A; add tetrabutyl titanate to isopropanol, mix well, then add a tetrapropylammonium hydroxide aqueous solution and stir to obtain a colorless and transparent solution, denoted as solution B. S2. Mix solution A and solution B, stir first, then heat to remove alcohol, then add water and stir to age the mixture to obtain an aged mixture. S3. The aged mixture is subjected to crystallization treatment, and the resulting product is washed, dried and calcined to obtain attapulgite-based titanium silicate zeolite.

2. The lanthanide-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in claim 1, characterized in that, The cobalt content is 10 wt%, the lanthanide metal content is 1-10 wt%, and the balance is attapulgite-based titanium silicate zeolite.

3. The lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in claim 1 or 2, characterized in that, In step (1), the mass-volume ratio of acid-treated attapulgite, tetrabutyl titanate, and tetrapropylammonium hydroxide is 1g:0.1-0.5ml:2.5-5g.

4. The lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in claim 1 or 2, characterized in that, In step (2), the stirring treatment time is 1 to 2 hours; the heating temperature for alcohol removal is 80 to 90°C and the time is 1 to 2 hours; the stirring aging treatment time is 12 to 24 hours.

5. The lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in claim 1 or 2, characterized in that, In step (3), the crystallization treatment conditions are a temperature of 150℃~200℃ and a time of 24~36h; the specific process of the calcination treatment is: heating to 550~700℃ in an air atmosphere at a heating rate of 1~5℃ / min, and then calcining at this temperature for 5~10h.

6. The method for preparing the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst according to any one of claims 1 to 5, characterized in that, Includes the following steps: The precursor salt of cobalt, the precursor salt of lanthanides, the attapulgite-based titanium silicate zeolite and the solvent are mixed, stirred first, then the solvent is evaporated and dried, and finally calcined to obtain the lanthanide-modified cobalt / attapulgite-based titanium silicate zeolite catalyst.

7. The preparation method of the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in claim 6, characterized in that, The stirring treatment was carried out at room temperature for 6–12 hours; the drying treatment was carried out at 80–110°C for 12–24 hours.

8. The preparation method of the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in claim 6, characterized in that, The specific process of calcination is as follows: the temperature is raised to 500-700℃ in an air atmosphere at a rate of 1-5℃ / min, and then calcined at this temperature for 5-10 hours.

9. The application of the lanthanide metal-modified cobalt / attapulgite-based titanium silicate zeolite catalyst as described in any one of claims 1 to 5 in the catalytic depolymerization of lignin to prepare guaiacol.

10. A method for preparing guaiacol by depolymerization of lignin, characterized in that, Includes the following steps: Lignin, water, glycerol, formic acid, and the catalyst as described in any one of claims 1 to 5 are added to a reactor, and a sealed reaction is carried out after nitrogen is introduced.

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