Method for catalyzing selective hydrogenolysis of lignin monophenol

Abstract

The invention discloses a method for catalyzing selective hydrogenolysis of lignin monophenol. The invention relates to a method for catalyzing selective hydrogenolysis of lignin monophenol, which comprises the following steps: adding a biomass oil phenolic compound and a ruthenium-based catalyst into a reaction container, filling hydrogen under the conditions that the hydrogen pressure is 0.5-3.0 MPa, the reaction temperature is 100-200 DEG C and the reaction time is 1-5 hours, and reacting to prepare a saturated hydrogenation product. According to the method provided by the invention, the phenol compound is subjected to hydrodeoxygenation by using the ruthenium-based catalyst, so that the conversion of the phenol compound into the oxygen-containing compound with high added value is realized.

Description

Technical field:

[0001] The invention relates to the technical field of organic matter preparation, and in particular to a method for catalyzing the selective hydrogenolysis of lignin monophenols. Background technology:

[0002] With the shortage of fossil energy, the utilization of renewable resources has received more and more attention. As the only carbon-containing renewable energy, biomass energy has the advantages of being renewable, low pollution, and widely distributed. Lignin, as one of the three major components of biomass, has high carbon and hydrogen content and high calorific value, making it an ideal raw material for producing high-quality liquid biofuels. However, phenolic compounds contain functional groups such as hydroxyl and methoxyl groups, which affect the stability of bio-oil and have poor combustion efficiency.

[0003] Phenolic compounds can be converted into a variety of chemicals through catalytic cracking, catalytic hydrodeoxygenation and coordinated processing of hydrogen-rich feedstocks. However, due to the incompatibility of feedstocks and existing hydroprocessing catalysts, effective and stable hydrodeoxygenation of phenolic compounds is a challenging task. In addition to the high requirements for catalytic activity, the stability of hydrodeoxygenation catalysts is challenged due to the loss of active components, oxidation and deactivation caused by carbon deposition caused by long-term use. Therefore, constructing a catalyst with both high activity and high stability is crucial to reduce the conversion cost of biomass-derived phenolic feedstocks and improve the economic efficiency of the conversion process. Summary of the invention:

[0004] The present invention solves the problems existing in the prior art and provides a method for catalyzing the selective hydrogenolysis of lignin monophenol. The present invention aims at hydrogenating phenolic compounds. A supported catalyst (ruthenium-based catalyst) prepared under low metal loading exhibits high catalytic activity in the catalytic hydrogenation of phenolic compounds. The product and the catalyst are easy to separate, have high stability, and can be recycled, effectively solving the practical problems existing in current catalysts for hydrogenation and deoxygenation of phenolic compounds.

[0005] The first object of the present invention is to provide a ruthenium-based catalyst, which includes a modified carrier and an active metal component loaded on the carrier. The modified carrier is prepared by the following steps: adding an oxide carrier to deionized water and stirring evenly, adding a salt solution of a stabilizing metal dropwise, and calcining to obtain a modified carrier, wherein the stabilizing metal in the modified carrier basically exists in a single atom form.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned ruthenium-based catalyst, comprising the following steps:

[0007] (1) Preparation of modified carrier: Add the oxide carrier to deionized water and stir evenly, add the salt solution of stabilizing metal dropwise, stir completely and filter, and calcine to obtain the modified carrier, wherein the stabilizing metal is selected from Ce, Zr, W, and Nb, and the stabilizing metal exists substantially in the form of single atom after loading;

[0008] (2) adding deionized water to the modified support obtained in step (1) and mixing evenly to obtain a modified support solution, then dropping a solution containing a noble metal precursor into the modified support solution, stirring, filtering, drying, and calcining to obtain the ruthenium-based catalyst. The active metal in the ruthenium-based catalyst is mostly present in the form of ruthenium oxide after calcination and oxidation.

[0009] Preferably, in step (1), based on the total mass of the ruthenium-based catalyst, the mass fraction of the transition metal is 0.5-10 wt %. More preferably, the mass fraction of the transition metal is 1.0 wt %.

[0010] Preferably, in step (1), the oxide carrier is selected from one of γ-alumina, α-alumina, cerium dioxide, silicon dioxide, titanium dioxide, mesoporous alumina, molecular sieve MCM, and SBA-1.

[0011] Preferably, the calcination conditions in step (1) are: calcination temperature 300°C to 600°C, heating rate 4 to 6°C / min, and calcination time 2 to 5 hours. More preferably, the calcination temperature is 500°C, heating rate 5°C / min, and calcination time is 4 hours.

[0012] Preferably, in step (2), the precious metal is selected from one of Ru, Pd and Pt, and the mass fraction of the precious metal is 0.1-5.0 wt % based on the total mass of the ruthenium-based catalyst. More preferably, the mass fraction of the precious metal is 0.5 wt %.

[0013] Preferably, the calcination conditions in step (2) are: calcination temperature 300°C to 600°C, heating rate 4 to 6°C / min, calcination time 2 to 5 hours. More preferably, the calcination temperature is 500°C, heating rate 5°C / min, and calcination time 2 hours.

[0014] The third object of the present invention is to provide a method for catalyzing the selective hydrogenolysis of lignin monophenols, comprising the following steps: adding biomass oil phenol compounds and the ruthenium-based catalyst into a high-pressure reaction vessel, filling with hydrogen, the hydrogen pressure being 0.5 to 3.0 MPa, the reaction temperature being 100° C. to 200° C., the reaction time being 1 to 5 hours, and reacting to prepare a saturated hydrogenation product.

[0015] The method proposed by the present invention uses a ruthenium-based catalyst to carry out hydrogenation deoxygenation on phenolic compounds, thereby realizing the conversion of phenolic compounds into high value-added compounds.

[0016] Preferably, the bio-oil phenolic compound is selected from phenol, guaiacol, 4-propylphenol, methylguaiacol, and eugenol. More preferably, the bio-oil phenolic compound is eugenol containing multiple functional groups including methoxyl group, carbon-carbon double bond, and phenolic hydroxyl group.

[0017] Preferably, the reaction conditions are: hydrogen pressure 2.0 MPa, reaction temperature 180° C., and reaction time 2 h.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The preparation method of the catalyst provided by the present invention adopts a simple two-step impregnation method to prepare a supported catalyst. The catalyst obtained after calcination can directly perform the hydrodeoxygenation reaction of phenolic compounds without further reduction treatment.

[0020] 2. The method provided by the present invention can exhibit high catalytic activity at very low precious metal loading (<1.0wt%) and under relatively mild reaction conditions, and the catalyst has good performance in repeated use in the reactor. Description of the drawings:

[0021] Figure 1 This is the XRD diagram of the catalyst obtained in Example 1 of the present invention.

[0022] Figure 2 This is the HAADF-STEM image of the modified support and catalyst obtained in Example 1 of the present invention.

[0023] Figure 3 This is a stability test of the catalyst obtained in Example 11 of the present invention. Specific implementation method:

[0024] The following examples are provided to further illustrate the present invention, rather than to limit the present invention.

[0025] Unless otherwise defined, all professional terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the experimental materials and reagents herein are conventional commercial products in the art.

[0026] The ruthenium-based catalyst proposed by the present invention has a good catalytic efficiency immediately when the metal ruthenium loading is within 1.0wt%. 50mg of the ruthenium-based catalyst is added to the reactant solution, and the air in the reactor is replaced with hydrogen after sealing, and a certain amount of hydrogen is introduced. The reaction temperature is controlled at 100°C to 200°C, and samples are taken after the reaction for 0.5 to 5h, and the raw material conversion rate and the selectivity of each product are calculated.

[0027]

[0028]

[0029]

[0030] The reaction products were qualitatively analyzed by gas chromatography-mass spectrometry; the conversion rate, yield and selectivity of the reaction were quantitatively analyzed by gas chromatograph equipped with a hydrogen flame detector.

[0031] Example 1

[0032] Preparation of 0.5wt% Ru / CeAl catalyst by impregnation method: Dissolve γ-alumina with 20mL deionized water and stir thoroughly, then dissolve cerium nitrate hexahydrate with an appropriate amount of deionized water, add it dropwise to the alumina solution, stir at 80°C for 3h, filter, dry overnight in an oven at 80°C, and heat to 500°C at a rate of 5°C / min in an air atmosphere in a tube furnace, retain for 4h to obtain a CeAl carrier, wherein the mass ratio of Ru:Ce:Al2O3 is 0.5:1:98.5. The spherical aberration corrected transmission electron microscopy image of the CeAl carrier is shown in Figure 2 As shown in a, metal Ce is supported on the alumina carrier in the form of a single atom.

[0033] 1g of the carrier was dispersed in a certain volume of deionized water, and 0.25g of ruthenium trichloride aqueous solution containing 2.0wt% of metallic ruthenium was added dropwise, and stirred for 3h at 80℃, filtered, dried in an oven at 80℃ overnight, and then heated to 500℃ in a tube furnace at a heating rate of 5℃ / min and kept for 2h to obtain the target catalyst 0.5wt%Ru / CeAl. The X-ray diffraction spectrum of the catalyst is shown in Figure 1 The spherical aberration corrected transmission electron microscopy of the catalyst is shown in Figure 2 b shows the RuO2 particle lattice and CeO after calcination and oxidation. X single-atom structure.

[0034] Weigh 50 mg of the above target catalyst into a stainless steel autoclave, then add 0.164 g of eugenol and 10 mL of n-hexane into the autoclave. Seal the autoclave, replace the air in the autoclave with hydrogen, and fill it with 2.0 MPa of hydrogen after purging with hydrogen 7 times. Then heat to 180 ° C at a rate of 5 ° C / min, continue to react for 1 hour, stir at a rate of 700 rpm, and obtain eugenol hydrodeoxygenation product. The product yield is shown in Table 1. Among them, the alkane product is propyl cyclohexane, the alcohol product is a mixture of 4-propyl cyclohexanol and 2-methoxy-4-propyl cyclohexanol, and the phenolic compound is a mixture of propyl guaiacol and 4-propyl phenol.

[0035] Example 2

[0036] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the Ce content in the catalyst carrier is 0.5 wt %. The product yield is shown in Table 1.

[0037] Example 3

[0038] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the Ce content in the catalyst carrier is 10.0 wt %. The product yield is shown in Table 1.

[0039] Table 1. Catalytic hydrogenation activity of eugenol on catalysts with different Ce contents

[0040]

[0041]

[0042] Example 4

[0043] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the calcination temperature of the catalyst after impregnation with metal Ru is 300° C. The product yield is shown in Table 2.

[0044] Example 5

[0045] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the calcination temperature of the catalyst after impregnation with metal Ru is 400° C. The product yield is shown in Table 2.

[0046] Example 6

[0047] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the calcination temperature of the catalyst after impregnation with metal Ru is 600° C. The product yield is shown in Table 2.

[0048] Table 2. Catalytic hydrogenation activity of eugenol on Ru-based catalysts at different calcination temperatures

[0049]

[0050] Example 7

[0051] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that a 0.1wt% Ru / CeAl catalyst is prepared, wherein the mass ratio of Ru:Ce:Al2O3 is 0.1:0.1:98.8. The product yield is shown in Table 3.

[0052] Example 8

[0053] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that a 5wt% Ru / CeAl catalyst is prepared, wherein the mass ratio of Ru:Ce:Al2O3 is 5:10:85. The product yield is shown in Table 3.

[0054] Table 3. Catalytic hydrogenation activity of eugenol on catalysts with different Ru contents

[0055]

[0056] Example 9

[0057] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the reaction temperature is 150° C. The product yield is shown in Table 4.

[0058] Example 10

[0059] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the reaction temperature is 200° C. The product yield is shown in Table 4.

[0060] Table 4. Product yields of eugenol at different reaction temperatures

[0061]

[0062]

[0063] Embodiment 11

[0064] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the reaction time is 2.0 h. The product yield is shown in Table 5.

[0065] Example 12

[0066] The catalyst preparation method, feed amount and reaction conditions were the same as those in Example 1, except that the reaction time was 3.0 h. The product yields are shown in Table 5.

[0067] Embodiment 13

[0068] The catalyst preparation method, feed amount and reaction conditions were the same as those in Example 1, except that the reaction time was 5.0 h. The product yields are shown in Table 5.

[0069] Table 5. Product yields of eugenol hydrodeoxygenation at different reaction times

[0070]

[0071]

[0072] Figure 3 This is a stability experiment of 0.5wt% Ru / CeAl catalyst. Since the stability of the catalyst is very important for practical applications, in order to verify the reusability of 0.5wt% Ru / CeAl in the eugenol hydrogenation experiment, it can be seen from Table 5 that eugenol is completely converted into saturated hydrogenation (alkanes and alcohols) products within 2h of reaction time, so a catalyst recycling experiment was carried out with 2h as a reaction cycle. The eugenol hydrodeoxygenation reaction test was carried out by recycling the same catalyst for five consecutive cycles. At the end of each cycle, the catalyst was recovered by filtration and vacuum dried at 60°C for 12h. The amount of loss in the process of recovering the catalyst was compensated by adding fresh catalyst. Figure 3 The graph shows how the catalytic activity of 0.5wt% Ru / CeAl changes after five consecutive uses. As can be seen from the figure, after five cycles of the catalyst, the conversion rate of eugenol can reach 99.9%, and the yield of alcohol compounds remains above 90%, indicating that the catalyst has good stability.

[0073] Embodiment 14

[0074] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the hydrogen pressure is 1 MPa. The product yield is shown in Table 6.

[0075] Embodiment 15

[0076] The catalyst preparation method, feed amount and reaction conditions are the same as those in Example 1, except that the hydrogen pressure is 3 MPa. The product yield is shown in Table 6.

[0077] Table 6. Product yields of eugenol hydrodeoxygenation at different hydrogen pressures

[0078]

[0079]

[0080] Example 16

[0081] The catalyst preparation method, addition amount and reaction conditions were the same as those in Example 1. 1 mmol of lignin derivative compound was added to the reactor and reacted at 180° C. for 2 h. The catalytic hydrogenation activities of different compounds on 0.5 wt% Ru / CeAl are shown in Table 7.

[0082] Table 7. Catalytic hydrodeoxygenation activity of different lignin-derived compounds on Ru / CeAl catalyst

[0083]

[0084] Comparative Example 1

[0085] Preparation of 0.5wt% Ru / Al2O3 catalyst by impregnation method: In a tubular furnace, heat the temperature to 500°C at a heating rate of 5°C / min under air atmosphere and retain it for 4h. Disperse 1g of γ-alumina carrier in a certain volume of deionized water, add 0.25g of ruthenium trichloride aqueous solution containing 2.0wt% of metallic ruthenium, and continue stirring at 80°C for 3h, filter, dry in an oven at 80°C overnight, and then heat the temperature to 500°C at a heating rate of 5°C / min in a tubular furnace and retain it for 2h to obtain the target catalyst 0.5wt% Ru / Al2O3. In addition, the amount of feed and reaction conditions are the same as those in Example 1. The product yield is shown in Table 8.

[0086] Comparative Example 2

[0087] Preparation of 0.5wt% Ru / CeO2 catalyst by impregnation method: Cerium nitrate hexahydrate was heated to 500°C at a heating rate of 5°C / min in a tube furnace under air atmosphere and retained for 4h to obtain CeO2 carrier. 1g CeO2 carrier was dispersed in a certain volume of deionized water, 0.25g of ruthenium trichloride aqueous solution containing 2.0wt% metal ruthenium was added dropwise, and stirred for 3h at 80°C, filtered, dried in an oven at 80°C overnight, and then heated to 500°C at a heating rate of 5°C / min in a tube furnace and retained for 2h to obtain the target catalyst 0.5wt% Ru / CeO2. In addition, the amount of feed and reaction conditions were the same as those in Example 1. The product yield is shown in Table 8.

[0088] Comparative Example 3

[0089] Preparation of CeO2 / Al2O3 catalyst by impregnation method: Dissolve γ-alumina with 20 mL of deionized water and stir well, then dissolve cerium nitrate hexahydrate with an appropriate amount of deionized water, add dropwise to the alumina solution, stir at 80°C for 3 hours, filter, dry overnight in an oven at 80°C, and heat to 500°C at a heating rate of 5°C / min in an air atmosphere in a tube furnace, retain for 4 hours to obtain CeO2 / Al2O3, wherein the mass of Ce accounts for 1wt% of the mass of Al2O3. In addition, the amount of feed and reaction conditions are the same as those in Example 1. The product yield is shown in Table 8.

[0090] Table 8. Catalytic hydrogenation activity of eugenol on Ru catalysts supported on different supports

[0091]

[0092]

[0093] As can be seen from Table 1, the catalyst prepared by loading Ru on CeAl carrier has higher hydrodeoxygenation activity than the catalysts prepared by loading Ru on CeO2 and Al2O3 respectively, and the yields of cyclohexanol derivatives and alkane compounds obtained under the same reaction conditions are higher.

[0094] The description of the above embodiments is only used to help understand the technical solution and core ideas of the present invention. It should be pointed out that for technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention. These improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A ruthenium-based catalyst, characterized in that The ruthenium-based catalyst comprises a modified carrier and an active metal component loaded on the carrier. The modified carrier is prepared by the following steps: adding an oxide carrier into deionized water and stirring evenly, dripping a salt solution of a stabilizing metal, and calcining to obtain a modified carrier, wherein the stabilizing metal in the modified carrier basically exists in a single atom form.

2. The method for preparing a ruthenium-based catalyst according to claim 1, characterized in that: The following steps are involved: (1) Preparation of modified carrier: adding an oxide carrier to deionized water and stirring evenly, adding a salt solution of a stabilizing metal dropwise, stirring completely and filtering, and calcining to obtain a modified carrier, wherein the stabilizing metal is selected from one of Ce, Zr, W, and Nb, and the stabilizing metal is substantially present in a single atom form after loading; (2) adding deionized water to the modified support obtained in step (1) and mixing evenly to obtain a modified support solution, then dropping a solution containing a noble metal precursor into the modified support solution, stirring, filtering, drying, and calcining to obtain the ruthenium-based catalyst, wherein the active metal in the ruthenium-based catalyst exists in the form of ruthenium oxide.

3. The preparation method according to claim 2, characterized in that: In step (1), the mass of the stabilizing metal is 0.5 to 10.0 wt % based on the total mass of the ruthenium-based catalyst.

4. The preparation method according to claim 2 or 3, characterized in that: In step (1), the oxide carrier is selected from one of γ-alumina, α-alumina, cerium dioxide, silicon dioxide, titanium dioxide, mesoporous alumina, molecular sieve MCM, and SBA-1.

5. The preparation method according to claim 2 or 3, characterized in that: The calcination conditions in step (1) are: calcination temperature 300° C. to 600° C., heating rate 4 to 6° C. / min, and calcination time 2 to 5 h.

6. The preparation method according to claim 2 or 3, characterized in that: In step (2), the precious metal is selected from one of Ru, Pd and Pt, and the mass fraction of the precious metal is 0.1 to 5.0 wt % based on the total mass of the ruthenium-based catalyst.

7. The preparation method according to claim 2 or 3, characterized in that: The calcination conditions in step (2) are: calcination temperature 300° C. to 600° C., heating rate 4 to 6° C. / min, and calcination time 2 to 5 hours.

8. A method for catalyzing the selective hydrogenolysis of lignin monophenols, characterized in that: The following steps are involved: Add the biomass oil phenol compound and the ruthenium-based catalyst described in claim 1 into a reaction container, fill with hydrogen, the hydrogen pressure is 0.5-3.0MPa, the reaction temperature is 100°C-200°C, the reaction time is 1-5h, and the saturated hydrogenation product is prepared by reaction.

9. The method according to claim 8, characterized in that The bio-oil phenolic compound is selected from one of phenol, guaiacol, 4-propylphenol, methylguaiacol and eugenol.

10. The method according to claim 8, characterized in that The reaction conditions are: hydrogen pressure 2.0 MPa, reaction temperature 180°C, and reaction time 2 h.

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