Catalyst for preparing phenol and guaiacol through lignin depolymerization as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing phenol and guaiacol through lignin depolymerization as well as a preparation method and application of the catalyst. The catalyst comprises a carrier and active components loaded on the carrier, the carrier is activated carbon, and the active components are molybdenum, cobalt and ruthenium. The catalyst is applied to catalytic depolymerization of lignin to prepare phenol and guaiacol, 100% lignin conversion rate can be achieved in an absolute ethyl alcohol solvent in a nitrogen atmosphere under the condition that no extra hydrogen source is needed, the phenol yield is larger than 10%, the guaiacol yield is larger than 25%, the depolymerization capacity and selectivity of the catalyst to lignin can be improved, and the catalyst can be applied to preparation of phenol and guaiacol. Good industrial application prospects are realized.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a catalyst for preparing phenol and guaiacol by depolymerizing lignin, and a preparation method and application thereof. Background Art

[0002] Lignin is a renewable aromatic hydrocarbon resource. Different from hemicellulose and cellulose, which have specific structures, lignin is a natural macromolecule with a more complex structure. The unique aromatic backbone of lignin makes it unique among biopolymers and gives it potential value as an aromatic chemical raw material.

[0003] Studies have shown that natural lignin is an aromatic polymer composed of p-hydroxyphenylpropane (H), guaiacylpropane (G) and syringylpropane (S) units, randomly cross-linked and polymerized through ether bonds (β-O-4, α-O-4, 4-O-5) and CC bonds (β-β, β-5, β-1, 5-5), with a molecular weight of more than 10000u. Among them, the β-O-4 ether bond is the most important bond, accounting for 50% of the total bonds, while other bonds account for about 3-25% of the total bonds. Therefore, the key strategy for the high-value conversion of lignin relies on the effective cleavage of the CO bond to expose more active groups while maintaining the integrity of the aromatic ring. To date, the conversion of lignin into high-value-added phenolic monomers by thermochemical catalytic destruction of ether bonds is a current research hotspot.

[0004] Phenol and guaiacol are important fine chemical intermediates, which are widely used in the manufacture of agricultural chemicals, detergents, plastics, drugs, fragrances, dyes and plasticizers. However, their preparation processes are very complicated. Based on the structural characteristics of lignin, the development of specific functional catalysts, the use of hydrogenation depolymerization principle, the selective bond breaking depolymerization of lignin under mild conditions, and the preparation of phenol and guaiacol have important industrial application value. Summary of the invention

[0005] The main purpose of the present invention is to provide a catalyst capable of catalyzing the depolymerization of lignin to prepare phenol and guaiacol without an external hydrogen source, and a preparation method and application thereof.

[0006] To achieve the above object, the present invention provides a catalyst for preparing phenol and guaiacol by depolymerization of lignin, comprising a carrier and active components loaded on the carrier, wherein the carrier is activated carbon, and the active components are molybdenum, cobalt and ruthenium.

[0007] Furthermore, the content of molybdenum is 20-30wt%, the content of cobalt is 5-15wt%, the content of ruthenium is 1-5wt%, and the balance is activated carbon.

[0008] The present invention also provides a method for preparing the catalyst for preparing phenol and guaiacol by depolymerizing lignin, comprising the following steps: dissolving precursor salts of molybdenum, cobalt and ruthenium in anhydrous ethanol, adding activated carbon, and then heating and stirring until the ethanol is completely evaporated, then drying the remaining solid, grinding it into powder, and finally calcining it under a nitrogen atmosphere, and then cooling it to room temperature to obtain the catalyst for preparing phenol and guaiacol by depolymerizing lignin.

[0009] Furthermore, the temperature condition of the heating and stirring treatment is 80°C.

[0010] Furthermore, the drying conditions are a temperature of 105° C. and a time of 12 h.

[0011] Furthermore, the specific process of the calcination treatment is: heating to 550° C. at a heating rate of 2° C. / min, and then calcining at this temperature for 6 hours.

[0012] The present invention also provides the use of the catalyst in catalyzing the depolymerization of lignin to prepare phenol and guaiacol under the condition of using ethanol as solvent and without external hydrogen source.

[0013] The present invention also provides a method for preparing phenol and guaiacol by catalyzing the depolymerization of lignin, comprising the following steps: putting lignin, ethanol and the above catalyst into a reactor, and performing a sealed reaction under a nitrogen atmosphere.

[0014] Furthermore, the mass ratio of lignin, catalyst and ethanol solvent is 1:0.1-0.5:30-50.

[0015] Furthermore, the reaction conditions are temperature 200-290° C., stirring rate 450-550 r / min, and time 1-24 h.

[0016] The catalyst of the present invention uses activated carbon as a carrier and a mixture of molybdenum, cobalt and ruthenium as an active component, which can enhance the ability of the catalyst to crack lignin; the activated carbon has a well-developed internal void structure, a large surface area and a strong adsorption capacity, and can fully disperse the catalytic active components and adsorb reactant molecules; the molybdenum metal and its oxide have flexible and changeable valence states and a unique crystal structure, and show excellent CO bond selective breaking ability in the lignin depolymerization process, as well as a moderate hydrogenation deoxygenation function to avoid excessive hydrogenation of the benzene ring; the electronegativity of the cobalt atom is smaller than that of the molybdenum atom, and the cobalt atom added to the catalyst can donate electrons to the molybdenum active component, thereby improving the CO bond breaking ability and the adsorption capacity for oxygen-containing intermediates; ruthenium, as a classic catalyst with hydrogenation deoxygenation function, can fully activate the ethanol solvent and the CH / OH bond of lignin, generate an in-situ hydrogen source to combine with the lignin depolymerization reactive intermediate, and reduce coking in the reaction process; thus, the catalyst of the present invention has a very high selective bond breaking ability for lignin and a high yield of phenol and guaiacol.

[0017] The beneficial effects of the present invention are embodied in:

[0018] The catalyst of the invention is used for catalytic depolymerization of lignin to prepare phenol and guaiacol. Under the conditions of anhydrous ethanol solvent, a nitrogen atmosphere and no additional hydrogen source, a 100% lignin conversion rate can be achieved, a phenol yield of more than 10%, and a guaiacol yield of more than 25% can be achieved. The catalyst has the advantages of high economic benefits, low metal loading, and high cycle times, can improve the catalyst's depolymerization ability and selectivity for lignin, and has good industrial application prospects. DETAILED DESCRIPTION

[0019] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be noted that the following embodiments do not limit the protection scope of the present invention.

[0020] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods; unless otherwise specified, the methods used in the examples of the present invention are methods known to those skilled in the art. Among them, lignin was purchased from Sinopharm Chemical Reagent Co., Ltd. (brand ALDRICH, CAS No. 8068-05-1); activated carbon was purchased from Foshan Pers Carbon Material Technology Co., Ltd. (specific surface area: 1500m 2 / g; Model: PC-CH-1; Specification: 300 mesh).

[0021] Example 1

[0022] Preparation of catalyst for depolymerization of lignin to produce phenol and guaiacol

[0023] The specific preparation method is as follows:

[0024] 0.5406g(NH4)6Mo7O 24·4H2O, 0.6675g Co(NO3)2·6H2O, and 0.0846gRu(NO)(NO3)3 were added to 30mL of anhydrous ethanol and stirred to dissolve to form a uniform solution. Then, 2.0000g of activated carbon was added to the above solution, and stirring was continued at a temperature of 80°C and a rotation speed of 100r / min until the ethanol solvent was completely evaporated. Subsequently, the evaporated solid was dried at 105°C for 12h and then ground into a solid powder. The solid powder was placed in a tubular furnace, and under a nitrogen flow of 100mL / min, the temperature was increased from room temperature to 550°C at a heating rate of 2°C / min, and then calcined at a constant temperature of 550°C for 6h, and finally naturally cooled to room temperature to obtain a catalyst for depolymerization of lignin to prepare phenol and guaiacol with a molybdenum content of 20wt%, a cobalt content of 5wt%, and a ruthenium content of 1wt%, which was recorded as 20Mo5Co1Ru / C.

[0025] Example 2

[0026] Preparation of catalyst for depolymerization of lignin to produce phenol and guaiacol

[0027] The specific preparation method is as follows:

[0028] 2.2087g (NH4)6Mo7O 24 ·4H2O, 2.9635g Co(NO3)2·6H2O, and 0.6276gRu(NO)(NO3)3 were added to 30mL of anhydrous ethanol and stirred to dissolve to form a uniform solution. Then, 2.0000g of activated carbon was added to the above solution, and stirring was continued at a temperature of 80°C and a rotation speed of 100r / min until the ethanol solvent was completely evaporated. Subsequently, the evaporated solid was dried at 105°C for 12h and then ground into a solid powder; the solid powder was placed in a tubular furnace, and under a nitrogen flow of 100mL / min, the temperature was increased from room temperature to 550°C at a heating rate of 2°C / min, and then calcined at a constant temperature of 550°C for 6h and finally naturally cooled to room temperature to obtain a catalyst for depolymerization of lignin to prepare phenol and guaiacol with a molybdenum content of 30wt%, a cobalt content of 15wt%, and a ruthenium content of 5wt%, which was recorded as 30Mo15Co5Ru / C.

[0029] Example 3

[0030] Preparation of catalyst for depolymerization of lignin to produce phenol and guaiacol

[0031] The specific preparation method is as follows:

[0032] 1.4842g (NH4)6Mo7O 24·4H2O, 1.5932g Co(NO3)2·6H2O, and 0.3037gRu(NO)(NO3)3 were added to 30mL of anhydrous ethanol and stirred to dissolve to form a uniform solution. Then, 2.0000g of activated carbon was added to the above solution, and stirring was continued at a temperature of 80°C and a rotation speed of 100r / min until the ethanol solvent was completely evaporated. The evaporated solid was then dried at 105°C for 12h and then ground into a solid powder. The solid powder was placed in a tubular furnace, and under a nitrogen flow of 100mL / min, the temperature was increased from room temperature to 550°C at a heating rate of 2°C / min, and then calcined at a constant temperature of 550°C for 6h and finally naturally cooled to room temperature to obtain a catalyst for depolymerization of lignin to prepare phenol and guaiacol with a molybdenum content of 25wt%, a cobalt content of 10wt%, and a ruthenium content of 3wt%, which was recorded as 25Mo10Co3Ru / C.

[0033] Example 4

[0034] Preparation of catalyst for depolymerization of lignin to produce phenol and guaiacol

[0035] The specific preparation method is as follows:

[0036] 1.7770g (NH4)6Mo7O 24 ·4H2O, 2.0434g Co(NO3)2·6H2O, and 0.2168gRu(NO)(NO3)3 were added to 30mL anhydrous ethanol and stirred to dissolve to form a uniform solution. Then, 2.0000g activated carbon was added to the above solution, and stirring was continued at a temperature of 80°C and a rotation speed of 100r / min until the ethanol solvent was completely evaporated. Subsequently, the evaporated solid was dried at 105°C for 12h and then ground into a solid powder. The solid powder was placed in a tubular furnace, and under a nitrogen flow of 100mL / min, the temperature was increased from room temperature to 550°C at a heating rate of 2°C / min, and then calcined at a constant temperature of 550°C for 6h and finally naturally cooled to room temperature to obtain a catalyst for depolymerization of lignin to prepare phenol and guaiacol with a molybdenum content of 28wt%, a cobalt content of 12wt%, and a ruthenium content of 2wt%, which was recorded as 28Mo12Co2Ru / C.

[0037] Example 5

[0038] Preparation of catalyst for depolymerization of lignin to produce phenol and guaiacol

[0039] The specific preparation method is as follows:

[0040] 1.3029g (NH4)6Mo7O 24·4H2O, 1.2860g Co(NO3)2·6H2O, and 0.3879gRu(NO)(NO3)3 were added to 30mL of anhydrous ethanol and stirred to dissolve to form a uniform solution. Then, 2.0000g of activated carbon was added to the above solution, and stirring was continued at a temperature of 80°C and a rotation speed of 100r / min until the ethanol solvent was completely evaporated. Subsequently, the evaporated solid was dried at 105°C for 12h and then ground into a solid powder. The solid powder was placed in a tubular furnace, and under a nitrogen flow of 100mL / min, the temperature was increased from room temperature to 550°C at a heating rate of 2°C / min, and then calcined at a constant temperature of 550°C for 6h and finally naturally cooled to room temperature to obtain a catalyst for depolymerization of lignin to prepare phenol and guaiacol with a molybdenum content of 23wt%, a cobalt content of 8wt%, and a ruthenium content of 4wt%, which was recorded as 23Mo8Co4Ru / C.

[0041] Example 6

[0042] Preparation of catalyst for depolymerization of lignin to produce phenol and guaiacol

[0043] The specific preparation method is as follows:

[0044] 1.5337 g (NH4)6Mo7O 24 ·4H2O, 1.9752g Co(NO3)2·6H2O, and 0.3139gRu(NO)(NO3)3 were added to 30mL of anhydrous ethanol and stirred to dissolve to form a uniform solution. Then, 2.0000g of activated carbon was added to the above solution, and stirring was continued at a temperature of 80°C and a rotation speed of 100r / min until the ethanol solvent was completely evaporated. Subsequently, the evaporated solid was dried at 105°C for 12h and then ground into a solid powder. The solid powder was placed in a tubular furnace, and under a nitrogen flow of 100mL / min, the temperature was increased from room temperature to 550°C at a heating rate of 2°C / min, and then calcined at a constant temperature of 550°C for 6h and finally naturally cooled to room temperature to obtain a catalyst for depolymerization of lignin to prepare phenol and guaiacol with a molybdenum content of 25wt%, a cobalt content of 12wt%, and a ruthenium content of 3wt%, which was recorded as 25Mo12Co3Ru / C.

[0045] Comparative Example 1

[0046] The catalyst was prepared in the same manner as in Example 3 except that (NH4)6Mo7O 24 ·4H2O is added, and the dosage of the remaining active component precursor salt is adjusted to 1.1350gCo(NO3)2·6H2O and 0.2166gRu(NO)(NO3)3, and finally an activated carbon-supported cobalt-ruthenium catalyst with a cobalt content of 10wt% and a ruthenium content of 3wt% is obtained, which is recorded as 10Co3Ru / C.

[0047] Comparative Example 2

[0048] The catalyst of this comparative example was prepared in the same manner as in Example 3, except that the addition of Co(NO3)2·6H2O was omitted and the amount of the remaining active component precursor salt was adjusted to 1.2778 g (NH4)6Mo7O 24 ·4H2O and 0.2615g Ru(NO)(NO3)3, and finally an activated carbon-supported molybdenum-ruthenium catalyst with a molybdenum content of 25wt% and a ruthenium content of 3wt% was obtained, which was recorded as 25Mo3Ru / C.

[0049] Comparative Example 3

[0050] The catalyst of this comparative example was prepared in the same manner as in Example 3, except that the addition of Ru(NO)(NO3)3 was omitted and the amount of the remaining active component precursor salt was adjusted to 1.4151 g (NH4)6Mo7O 24 ·4H2O and 1.5182Co(NO3)2·6H2O, and finally an activated carbon-supported molybdenum-cobalt catalyst with a molybdenum content of 25wt% and a cobalt content of 10wt% was obtained, which was recorded as 25Mo10Co / C.

[0051] Comparative Example 4

[0052] This comparative example prepared the catalyst in the same manner as in Example 3 except that Ni(NO3)2·6H2O was used instead of (NH4)6Mo7O 24 ·4H2O, and the dosage of each active component precursor salt is adjusted to 3.9953g Ni(NO3)2·6H2O, 1.5934g Co(NO3)2·6H2O and 0.3044g Ru(NO)(NO3)3, and finally an activated carbon-supported nickel-cobalt-ruthenium catalyst with a nickel content of 25wt%, a cobalt content of 10wt% and a ruthenium content of 3wt% is obtained, which is recorded as 25Ni10Co3Ru / C.

[0053] Performance test of lignin depolymerization to produce phenol and guaiacol catalyzed by activated carbon supported molybdenum-cobalt-ruthenium catalyst

[0054] Test method: Weigh 1g of lignin, 0.1-0.5g of catalyst, and 30-50g of anhydrous ethanol, add them into a high-pressure reactor, fill with 1.0MPa of high-purity nitrogen, and then seal and react for 1-24h at 200-290℃ and a stirring rate of 450-550r / min. Then filter the reaction product to obtain a liquid product, and then add an extractant composed of acetone and ethyl acetate (mixed in a volume ratio of 1:2) to the liquid product for extraction. Then take out the extractant layer, and perform rotary evaporation on the extractant layer at 45℃ to remove the extractant. Finally, perform quantitative analysis on the rotary evaporation product.

[0055] The specific reaction conditions and results are shown in Table 1.

[0056] Table 1

[0057]

[0058]

[0059] From the above results, it can be concluded that in the absence of an additional hydrogen source, the catalyst of the present invention can achieve full conversion of lignin in an anhydrous ethanol solvent system, achieving a 100% lignin conversion rate, wherein the phenol yield exceeds 10% and the guaiacol yield exceeds 25%. The lignin conversion rate of the comparative example is less than 100%, wherein the phenol yield is less than 5% and the guaiacol yield is less than 10%.

[0060] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A catalyst for preparing phenol and guaiacol by depolymerization of lignin, characterized in that: The invention comprises a carrier and active components loaded on the carrier, wherein the carrier is activated carbon, and the active components are molybdenum, cobalt and ruthenium.

2. The catalyst for preparing phenol and guaiacol by depolymerization of lignin according to claim 1, characterized in that: The content of molybdenum is 20-30wt%, the content of cobalt is 5-15wt%, the content of ruthenium is 1-5wt%, and the balance is activated carbon.

3. The method for preparing a catalyst for preparing phenol and guaiacol by depolymerization of lignin according to claim 1, characterized in that: The following steps are involved: The precursor salts of molybdenum, cobalt and ruthenium are dissolved in anhydrous ethanol, activated carbon is added, and then heated and stirred until the ethanol is completely evaporated. The remaining solid is then dried and ground into powder, and finally calcined under a nitrogen atmosphere, and then cooled to room temperature to obtain the catalyst for depolymerizing lignin to prepare phenol and guaiacol.

4. The method for preparing a catalyst for preparing phenol and guaiacol by depolymerization of lignin according to claim 3, characterized in that: The temperature condition for the heating and stirring treatment was 80°C.

5. The method for preparing a catalyst for preparing phenol and guaiacol by depolymerization of lignin as claimed in claim 3, characterized in that: The drying conditions were 105°C and 12 h.

6. The method for preparing a catalyst for preparing phenol and guaiacol by depolymerization of lignin as claimed in claim 3, characterized in that: The specific process of the calcination treatment is: heating up to 550°C at a heating rate of 2°C / min, and then calcining at this temperature for 6 hours.

7. Use of the catalyst as claimed in claim 1 or 2 in catalyzing the depolymerization of lignin to prepare phenol and guaiacol under the condition of ethanol as solvent and without external hydrogen source.

8. A method for preparing phenol and guaiacol by catalytic depolymerization of lignin, characterized in that: The following steps are involved: Lignin, ethanol and the catalyst as claimed in claim 1 or 2 are placed in a reactor and sealed for reaction under a nitrogen atmosphere.

9. The method for preparing phenol and guaiacol by catalytic depolymerization of lignin as claimed in claim 8, characterized in that: The mass ratio of lignin, catalyst and ethanol solvent is 1:0.1-0.5:30-50.

10. The method for preparing phenol and guaiacol by catalytic depolymerization of lignin as claimed in claim 8 or 9, characterized in that: The reaction conditions are temperature 200-290° C., stirring speed 450-550 r / min, and time 1-24 h.

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