A method for preparing high value-added amino acids by using lignin in papermaking wastewater

Abstract

The present application relates to papermaking wastewater high-value utilization technical field, specifically to a kind of method for preparing high value-added amino acid using lignin in papermaking wastewater, comprising: first using acid to adjust the pH of papermaking black liquor to 5-9, then join lanthanum manganese composite oxide catalyst and pass in O2 Oxidative depolymerization reaction obtains p-coumaric acid solution;P-coumaric acid solution is added to ruthenium iron catalyst, ammonia and carried out in H2 Atmosphere ammonia addition reaction to obtain L-tyrosine and beta-tyrosine.The two-step catalytic reaction method provided by the present application prepares amino acid from lignin in papermaking wastewater, not only reduces the pollution of papermaking black liquor, but also improves its application added value.

Description

Technical Field

[0001] This invention relates to the field of high-value utilization technology of papermaking wastewater, specifically to a method for preparing high-value-added amino acids from lignin in papermaking wastewater. Background Technology

[0002] Papermaking wastewater, also known as black liquor, is wastewater generated during the pulping process in the papermaking industry. It contains high concentrations of organic pollutants and is difficult to treat, seriously impacting the healthy development of both the papermaking and environmental protection sectors. Effective utilization of organic matter in papermaking wastewater not only greatly benefits economic and social development but also promotes ecological and environmental protection.

[0003] The main organic matter in papermaking wastewater is lignin, which accounts for more than 60% of the total solids in papermaking black liquor. Therefore, the key to reducing black liquor pollution lies in how to utilize lignin in a high-value manner. However, currently, apart from a very small portion of lignin being used as a concrete water-reducing agent, more than 90% of lignin is directly fed into the alkali recovery boiler in the pulping process for concentration and incineration. Some lignin is even directly discharged into the natural environment, which not only pollutes the environment but also wastes this renewable resource.

[0004] Lignin is an important component of biomass resources, accounting for 25-35% of plant dry weight. It is a three-dimensional amorphous macromolecule formed by three phenylpropane structural units—p-coumarol, coniferyl alcohol, and sinapyl alcohol—linked by CO and C-C bonds. It is a large-scale renewable resource in nature that can provide aromatic ring structures. The efficient utilization of lignin in papermaking black liquor is of significant practical importance for reducing pollution from papermaking black liquor and improving the resource utilization of waste.

[0005] Amino acids are important organic compounds in biology, composed of amino (-NH2) and carboxyl (-COOH) functional groups and side chains attached to each amino acid. Amino acids are the most basic substances that constitute proteins in living organisms and are related to life activities. They are closely related to biological life processes and are mainly used in medicine as therapeutic drugs and for synthesizing polypeptide drugs. Tyrosine, 2-amino-3-p-hydroxyphenylpropionic acid, is a conditionally essential amino acid and a ketogenic and glucogenic amino acid. β-Tyrosine is a non-essential amino acid that, along with α-amino acids, forms various protein macromolecules. Tyrosine and β-tyrosine have been found to be used in bacterial antibiotics, anticancer drugs, etc. However, methods for preparing L-tyrosine and β-tyrosine from lignin in papermaking black liquor have not yet been publicly reported. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the deficiency in the prior art that there is no method for preparing L-tyrosine and β-tyrosine using lignin in papermaking black liquor as raw material, thereby providing a method for preparing high-value-added amino acids using lignin in papermaking wastewater.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for preparing high-value-added amino acids from lignin in papermaking wastewater includes: first adjusting the pH of papermaking black liquor to 5-9 with acid, then adding a lanthanum-manganese composite oxide catalyst and introducing O2 to carry out an oxidative depolymerization reaction to obtain a p-coumaric acid solution; adding a ruthenium-iron catalyst and ammonia water to the p-coumaric acid solution and carrying out an ammonium addition reaction in an H2 atmosphere to obtain L-tyrosine and β-tyrosine.

[0009] Preferably, the raw materials for the lanthanum-manganese composite oxide catalyst include water-soluble lanthanum salt, water-soluble manganese salt, and urea. Specifically, the water-soluble lanthanum salt can be lanthanum nitrate, lanthanum chloride, etc.; the water-soluble manganese salt can be manganese nitrate, manganese chloride, etc.; wherein, the molar ratio of lanthanum to manganese is 1:(0.1-10); the ratio of the total molar amount of lanthanum and manganese to the molar amount of urea is 1:(2-20), preferably 1:(2-15).

[0010] Preferably, the preparation process of the lanthanum-manganese composite oxide catalyst is as follows: first, water-soluble lanthanum salt, water-soluble manganese salt and urea are dissolved in water, then heated to 90-110℃ for 6-24h, cooled to room temperature, washed and dried, and finally calcined at 500-800℃ for 2-12h to obtain the catalyst.

[0011] Preferably, the ruthenium-iron catalyst is ruthenium-supported Fe2O3; wherein the ruthenium loading is 0.2%-2%.

[0012] Preferably, the preparation process of the ruthenium-iron catalyst is as follows: obtaining an Fe2O3 support; impregnating the Fe2O3 support with an equal volume of an aqueous solution of water-soluble ruthenium salt with a concentration of 50-500 mmol / L, then drying, calcining at 200-500℃ for 2-12 h, and finally reducing in an H2 atmosphere at 200-400℃ to obtain the ruthenium-iron catalyst;

[0013] Preferably, the preparation process of Fe2O3 support is as follows: Fe(NO3)3 and hexadecyltrimethylammonium bromide are dissolved in water at a molar ratio of (3-30):1, then the pH is adjusted to 9-12 with sodium hydroxide, and the solution is crystallized at 160-220℃ for 12-48h, cooled to room temperature, washed and dried to obtain the solution;

[0014] And / or, the aqueous solution of the water-soluble ruthenium salt is preferably an aqueous solution of RuCl3.

[0015] Preferably, the acid is an organic acid;

[0016] Preferably, the organic acid is at least one of formic acid, acetic acid, and oxalic acid.

[0017] Preferably, the papermaking black liquor is obtained from raw materials mainly composed of agricultural and forestry herbaceous plants through alkaline pulping.

[0018] Preferably, the molar ratio of NH3 in the ammonia water to p-coumaric acid in the p-coumaric acid solution is (10-100):1.

[0019] Preferably, the oxidative depolymerization reaction pressure is 0.1-1.0 MPa, the reaction temperature is 120-180℃, and the reaction time is 1-12 h;

[0020] And / or, the oxidative depolymerization reaction is followed by filtration.

[0021] Preferably, the ammonia addition reaction pressure is 0.5-2.0 MPa, the reaction temperature is 180-260℃, and the reaction time is 1-12 h;

[0022] And / or, the ammonia addition reaction is followed by filtration and freeze-drying.

[0023] The technical solution of this invention has the following advantages:

[0024] A method for preparing high-value-added amino acids from lignin in papermaking wastewater includes: first, adjusting the pH of papermaking black liquor to 5-9 with acid; then, adding a lanthanum-manganese composite oxide catalyst and introducing O2 to carry out an oxidative depolymerization reaction to obtain a p-coumaric acid solution; adding a ruthenium-iron catalyst and ammonia to the p-coumaric acid solution and carrying out an ammonium addition reaction in an H2 atmosphere to obtain L-tyrosine and β-tyrosine. This invention employs a heterogeneous catalytic reaction method, using ammonia as a nitrogen source, to convert lignin in papermaking wastewater into high-value-added L-tyrosine and β-tyrosine under mild conditions. Furthermore, the reaction process does not use expensive organic ammonia compounds, making the process simple, reducing environmental pollution, and significantly increasing the added value of papermaking wastewater. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1This is a flowchart illustrating the main technological process for preparing L-tyrosine and β-tyrosine from lignin in papermaking wastewater according to the present invention.

[0027] Figure 2 This is the nuclear magnetic resonance spectrum of L-tyrosine obtained in Example 13 of the present invention;

[0028] Figure 3 This is the nuclear magnetic resonance spectrum of β-tyrosine obtained in Example 13 of the present invention. Detailed Implementation

[0029] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0030] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0031] Example 1

[0032] Preparation of lanthanum-manganese composite oxide catalyst: La(NO3)3, Mn(NO3)2 and urea were weighed according to the molar ratio of lanthanum to manganese of 10:1 and the molar ratio of (La+Mn) to urea of ​​1:3 and dissolved in water. The mixture was then heated under reflux in an oil bath at 100°C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water and dried. Finally, it was calcined in a muffle furnace at 800°C for 6 h to obtain LaMn-A.

[0033] Example 2

[0034] Preparation of lanthanum-manganese composite oxide catalyst: La(NO3)3, Mn(NO3)2 and urea were weighed according to the molar ratio of lanthanum to manganese of 3:1 and the molar ratio of (La+Mn) to urea of ​​1:9 and dissolved in water. The mixture was then heated under reflux in an oil bath at 95°C for 18 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water and dried. Finally, it was calcined in a muffle furnace at 600°C for 8 h to obtain LaMn-B.

[0035] Example 3

[0036] Preparation of lanthanum-manganese composite oxide catalyst: La(NO3)3, Mn(NO3)2 and urea were weighed according to the molar ratio of lanthanum to manganese of 1:1 and the molar ratio of (La+Mn) to urea of ​​1:5 and dissolved in water. The mixture was then heated under reflux in an oil bath at 105℃ for 24h. After the reaction was completed, the mixture was cooled to room temperature, washed with water and dried. Finally, it was calcined in a muffle furnace at 500℃ for 4h to obtain LaMn-C.

[0037] Example 4

[0038] Preparation of lanthanum-manganese composite oxide catalyst: La(NO3)3, Mn(NO3)2 and urea were weighed according to the molar ratio of lanthanum to manganese of 1:5 and the molar ratio of (La+Mn) to urea of ​​1:15 and dissolved in water. The mixture was then heated under reflux in an oil bath at 90°C for 6 hours. After the reaction was completed, the mixture was cooled to room temperature, washed with water and dried. Finally, it was calcined in a muffle furnace at 700°C for 10 hours to obtain LaMn-D.

[0039] Example 5

[0040] Preparation of lanthanum-manganese composite oxide catalyst: La(NO3)3, Mn(NO3)2 and urea were weighed according to the molar ratio of lanthanum to manganese of 1:10 and the molar ratio of (La+Mn) to urea of ​​1:12 and dissolved in water. The mixture was then heated under reflux in an oil bath at 110°C for 15 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water and dried. Finally, it was calcined in a muffle furnace at 650°C for 2 h to obtain LaMn-E.

[0041] Example 6

[0042] Preparation of ruthenium-iron catalyst: Fe(NO3)3 and hexadecyltrimethylammonium bromide (CTAB) were dissolved in water at a molar ratio of 10:1. The pH was then adjusted to 10 with sodium hydroxide. The solution was transferred to a stainless steel reactor and crystallized in an oven at 180°C for 24 hours. After cooling to room temperature, the solution was washed and dried to obtain an Fe2O3 support. An equal volume of 250 mmol / L RuCl3 aqueous solution was impregnated in the Fe2O3 support. The solution was then dried, calcined at 250°C for 6 hours, and finally reduced in an H2 atmosphere at 300°C to obtain a ruthenium-iron catalyst with a Ru loading of 0.5%, denoted as Ru / Fe2O3-A.

[0043] Example 7

[0044] Preparation of ruthenium-iron catalyst: Fe(NO3)3 and hexadecyltrimethylammonium bromide (CTAB) were dissolved in water at a molar ratio of 15:1. The pH was then adjusted to 11 with sodium hydroxide. The solution was transferred to a stainless steel reactor and crystallized in an oven at 200°C for 36 hours. After cooling to room temperature, the solution was washed and dried to obtain an Fe2O3 support. An equal volume of 100 mmol / L RuCl3 aqueous solution was impregnated in the Fe2O3 support. The solution was then dried, calcined at 400°C for 8 hours, and finally reduced in an H2 atmosphere at 200°C to obtain a ruthenium-iron catalyst with a Ru loading of 1.5%, denoted as Ru / Fe2O3-B.

[0045] Example 8

[0046] Preparation of ruthenium-iron catalyst: Fe(NO3)3 and hexadecyltrimethylammonium bromide (CTAB) were dissolved in water at a molar ratio of 30:1. The pH was then adjusted to 12 with sodium hydroxide. The solution was transferred to a stainless steel reactor and crystallized in an oven at 160°C for 12 hours. After cooling to room temperature, the solution was washed and dried to obtain an Fe2O3 support. An equal volume of 400 mmol / L RuCl3 aqueous solution was impregnated in the Fe2O3 support. The solution was then dried, calcined at 500°C for 2 hours, and finally reduced in an H2 atmosphere at 250°C to obtain a ruthenium-iron catalyst with a Ru loading of 1.0%, denoted as Ru / Fe2O3-C.

[0047] Example 9

[0048] Preparation of ruthenium-iron catalyst: Fe(NO3)3 and hexadecyltrimethylammonium bromide (CTAB) were dissolved in water at a molar ratio of 3:1. The pH was then adjusted to 9 with sodium hydroxide. The solution was transferred to a stainless steel reactor and crystallized in an oven at 220°C for 48 hours. After cooling to room temperature, the solution was washed and dried to obtain an Fe2O3 support. An equal volume of 500 mmol / L RuCl3 aqueous solution was impregnated in the Fe2O3 support. The solution was then dried, calcined at 200°C for 10 hours, and finally reduced in an H2 atmosphere at 350°C to obtain a ruthenium-iron catalyst with a Ru loading of 2.0%, denoted as Ru / Fe2O3-D.

[0049] Example 10

[0050] Preparation of ruthenium-iron catalyst: Fe(NO3)3 and hexadecyltrimethylammonium bromide (CTAB) were dissolved in water at a molar ratio of 5:1. The pH was then adjusted to 10 with sodium hydroxide. The solution was transferred to a stainless steel reactor and crystallized in an oven at 200°C for 12 hours. After cooling to room temperature, the solution was washed and dried to obtain an Fe2O3 support. An equal volume of 300 mmol / L RuCl3 aqueous solution was impregnated in the Fe2O3 support. The solution was then dried, calcined at 350°C for 7 hours, and finally reduced in an H2 atmosphere at 400°C to obtain a ruthenium-iron catalyst with a Ru loading of 0.2%, denoted as Ru / Fe2O3-E.

[0051] Example 11

[0052] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0053] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 7 using formic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-C was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.3 MPa. The reaction was stirred at 140°C for 6 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0054] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-E and ammonia water were mixed evenly and placed in a sealed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 30:1. After H2 replacement and pressurization to 1.0 MPa, the reaction was stirred at 200℃ for 3 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0055] Example 12

[0056] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0057] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 8 using acetic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-E was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.5 MPa. The reaction was stirred at 160°C for 8 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0058] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-C and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 60:1. After H2 replacement and pressurization to 1.5 MPa, the reaction was stirred at 180℃ for 6 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0059] Example 13

[0060] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0061] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 5 using oxalic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-D was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.8 MPa. The reaction was stirred at 150°C for 12 h. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0062] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-D and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 40:1. After H2 replacement and pressurization to 1.2 MPa, the reaction was stirred at 220℃ for 5 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0063] Example 14

[0064] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0065] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 9 using acetic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-B was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.9 MPa. The reaction was stirred at 180°C for 3 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0066] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-B and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 80:1. After H2 replacement and pressurization to 0.8 MPa, the reaction was stirred at 210℃ for 4 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0067] Example 15

[0068] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0069] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 6 using oxalic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-A was added and mixed evenly. The mixture was placed in a closed reaction vessel, O2 was introduced and the pressure was increased to 0.4 MPa. The reaction was stirred at 130°C for 2 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0070] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-A and ammonia water were mixed evenly and placed in a sealed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 10:1. After H2 replacement and pressurization to 2.0 MPa, the reaction was stirred at 230℃ for 9 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0071] Example 16

[0072] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0073] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 7 using formic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-C was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.2 MPa. The reaction was stirred at 120°C for 5 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0074] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-D and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 70:1. After H2 replacement and pressurization to 0.5 MPa, the reaction was stirred at 190℃ for 12 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0075] Example 17

[0076] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0077] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 5 with acetic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-E was added and mixed evenly and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.1 MPa. The reaction was stirred at 130°C for 1 h. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0078] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-C and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 90:1. After H2 replacement and pressurization to 0.7 MPa, the reaction was stirred at 240℃ for 10 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0079] Example 18

[0080] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0081] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 8 using oxalic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-A was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 1.0 MPa. The reaction was stirred at 150°C for 7 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0082] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-E and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 50:1. After H2 replacement and pressurization to 1.6 MPa, the reaction was stirred at 180℃ for 8 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0083] Example 19

[0084] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0085] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 7 using formic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-B was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.7 MPa. The reaction was stirred at 160°C for 9 hours. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0086] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-A and ammonia water were mixed evenly and placed in a sealed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 100:1. After H2 replacement and pressurization to 1.9 MPa, the reaction was stirred at 260℃ for 7 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0087] Example 20

[0088] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0089] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 9 using acetic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-D was added and mixed evenly and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.6 MPa. The reaction was stirred at 180°C for 10 h. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0090] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-B and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 20:1. After H2 replacement and pressurization to 1.3 MPa, the reaction was stirred at 250℃ for 1 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0091] Comparative Example 1

[0092] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0093] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 11 with acetic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-C was added and mixed evenly and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.5 MPa. The reaction was stirred at 180°C for 10 h. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0094] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-E and ammonia water were mixed evenly and placed in a sealed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 20:1. After H2 replacement and pressurization to 1.3 MPa, the reaction was stirred at 250℃ for 1 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0095] Comparative Example 2

[0096] A method for preparing high-value-added amino acids from lignin in papermaking wastewater specifically includes the following steps:

[0097] 1) Oxidative depolymerization reaction: The pH of the papermaking black liquor was adjusted to 4 using acetic acid, and then the lanthanum-manganese composite oxide catalyst LaMn-B was added, mixed evenly, and placed in a closed reaction vessel. O2 was introduced and the pressure was increased to 0.8 MPa. The reaction was stirred at 180°C for 10 h. After the reaction was completed, the catalyst was filtered to obtain an aqueous solution containing p-coumaric acid.

[0098] 2) Ammonia addition reaction: The molar amount of p-coumaric acid in the p-coumaric acid aqueous solution was determined. The above p-coumaric acid aqueous solution, ruthenium iron catalyst Ru / Fe2O3-A and ammonia water were mixed evenly and placed in a closed reaction vessel. The molar ratio of NH3 to p-coumaric acid in the ammonia water was 30:1. After H2 replacement and pressurization to 1.4 MPa, the reaction was stirred at 250℃ for 1 h. After the reaction was completed, the catalyst was filtered and freeze-dried to obtain a product containing L-tyrosine and β-tyrosine.

[0099] Test Example 1

[0100] The products prepared in Examples 11-20 and Comparative Examples 1-2 were quantitatively analyzed by nuclear magnetic resonance spectroscopy. The composition of the products was analyzed and the yield of coumaric acid was calculated. The calculation formula is shown in Equation 1 below. The relevant test results are shown in Table 1.

[0101] Formula 1: P x =(I X ×N std ×M X ×m std ) / (I std ×N X ×M std ×m x )×P std ;

[0102] P x and P std The purity of the analyte and the internal standard are respectively, I X and I std The 1H-NMR response values ​​of the analyte and internal standard are respectively, N X and N std M represents the number of protons in the analyte and the test sample, respectively. x and M std The relative molecular masses of the analyte and the internal standard are m and m, respectively. x and m std It is the mass of the analyte and the internal standard that are precisely weighed.

[0103] Table 1. Yields of L-tyrosine and β-tyrosine in Examples 11-20 and Comparative Examples 1-2

[0104] L-tyrosine yield (%) β-Tyrosine yield (%) Example 11 5.6 3.8 Example 12 4.6 5.7 Example 13 6.5 4.2 Example 14 5.8 2.6 Example 15 3.2 6.2 Example 16 2.6 5.8 Example 17 1.2 7.9 Example 18 1.8 6.5 Example 19 3.1 4.7 Example 20 2.9 4.8 Comparative Example 1 - - Comparative Example 2 - -

[0105] According to the test results of Examples 11-20 in Table 1, neither Comparative Example 1 nor Comparative Example 2 produced the target products L-tyrosine and β-tyrosine under excessively high or low pH conditions. However, Examples 11-20 successfully prepared L-tyrosine and β-tyrosine from lignin in papermaking wastewater within a pH range of 5-9. Therefore, this invention effectively achieves its objective by controlling pH and the process, employing a heterogeneous catalytic reaction method, using ammonia as a nitrogen source, and utilizing lignin in papermaking wastewater under mild conditions. Furthermore, the preparation process does not use expensive organic ammonia compounds, is simple, reduces environmental pollution, and significantly increases the added value of papermaking wastewater.

[0106] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing high-value-added amino acids from lignin in papermaking wastewater, characterized in that, include: First, the pH of the papermaking black liquor is adjusted to 5-9 using acid. Then, a lanthanum-manganese composite oxide catalyst is added and O2 is introduced to carry out an oxidative depolymerization reaction to obtain a p-coumaric acid solution. A ruthenium-iron catalyst and ammonia are added to the p-coumaric acid solution, and an ammonia addition reaction is carried out in an H2 atmosphere to obtain L-tyrosine and β-tyrosine. The raw materials for the lanthanum-manganese composite oxide catalyst include water-soluble lanthanum salt, water-soluble manganese salt, and urea, wherein the molar ratio of lanthanum to manganese is 1:(0.1-10); and the ratio of the total molar amount of lanthanum and manganese to the molar amount of urea is 1:(2-20). The preparation process of the lanthanum-manganese composite oxide catalyst is as follows: first, water-soluble lanthanum salt, water-soluble manganese salt and urea are dissolved in water, then heated to 90-110℃ for 6-24 h, cooled to room temperature, washed and dried, and finally calcined at 500-800℃ for 2-12 h to obtain the catalyst. The ruthenium-iron catalyst is ruthenium-supported Fe2O3; wherein the ruthenium loading is 0.2%-2%; The preparation process of the ruthenium-iron catalyst is as follows: obtain Fe2O3 support; impregnate the Fe2O3 support with an equal volume of an aqueous solution of water-soluble ruthenium salt with a concentration of 50-500 mmol / L, then dry and calcine at 200-500℃ for 2-12 h, and finally reduce in H2 atmosphere at 200-400℃ to obtain the ruthenium-iron catalyst; The preparation process of the Fe2O3 support is as follows: Fe(NO3)3 and hexadecyltrimethylammonium bromide are dissolved in water at a molar ratio of (3-30):1, then the pH is adjusted to 9-12 with sodium hydroxide, and the solution is crystallized at 160-220℃ for 12-48h, cooled to room temperature, washed and dried to obtain the support. The papermaking black liquor is obtained from raw materials mainly composed of agricultural and forestry herbaceous plants through an alkaline pulping process.

2. The method according to claim 1, characterized in that, The acid is an organic acid; The organic acid is at least one of formic acid, acetic acid, and oxalic acid.

3. The method according to claim 1, characterized in that, The molar ratio of NH3 in the ammonia water to p-coumaric acid in the p-coumaric acid solution is (10-100):

1.

4. The method according to claim 1, characterized in that, The oxidative depolymerization reaction is carried out at a pressure of 0.1-1.0 MPa, a temperature of 120-180℃, and a duration of 1-12 h. And / or, the oxidative depolymerization reaction is followed by filtration.

5. The method according to claim 1, characterized in that, The ammonia addition reaction is carried out at a pressure of 0.5-2.0 MPa, a temperature of 180-260℃, and a duration of 1-12 h. And / or, the ammonia addition reaction is followed by filtration and freeze-drying.

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