阅读说明：本技术 一种木质素水热液化产物的检测方法 (Detection method of lignin hydrothermal liquefaction product ) 是由 王红军 郭同翠 郭月良 张剑 马文骥 李昊宸 陈鹏羽 闫秀懿 于 2019-02-25 设计创作，主要内容包括：本发明提供了一种木质素水热液化产物的检测方法,所述木质素水热液化产物的检测方法包括：(1)对木质素水热液化产物进行固相萃取预处理,得到洗脱后的溶液；(2)利用高效液相色谱对所述洗脱后的溶液进行定性分析；(3)将步骤(2)中分析所得到的色谱图与标准物质的色谱图进行对比分析,以确定产物的组成。本发明所提供的该木质素水热液化产物的检测方法首先通过固相萃取法富集木质素水热液化产物中的酚类化合物,然后用高效液相色谱进行检测,可以实现对水热液化产物进行快速准确的定性分析。(The invention provides a detection method of a lignin hydrothermal liquefaction product, which comprises the following steps: (1) carrying out solid phase extraction pretreatment on the lignin hydrothermal liquefaction product to obtain an eluted solution; (2) carrying out qualitative analysis on the eluted solution by using high performance liquid chromatography; (3) comparing the chromatogram obtained in the step (2) with the chromatogram of the standard substance to determine the composition of the product. According to the detection method of the lignin hydrothermal liquefaction product, provided by the invention, the phenolic compounds in the lignin hydrothermal liquefaction product are enriched by a solid-phase extraction method, and then the detection is carried out by using a high performance liquid chromatography, so that the hydrothermal liquefaction product can be rapidly and accurately qualitatively analyzed.)

1. The detection method of the lignin hydrothermal liquefaction product is characterized by comprising the following steps:

(1) carrying out solid phase extraction pretreatment on the lignin hydrothermal liquefaction product to obtain an eluted solution;

(2) carrying out qualitative analysis on the eluted solution by using high performance liquid chromatography;

(3) comparing the chromatogram obtained in the step (2) with the chromatogram of the standard substance to determine the composition of the product.

2. The method of claim 1, wherein prior to the solid phase extraction pretreatment of the hydrothermal lignin liquefaction product, the method further comprises:

and filtering the lignin hydrothermal liquefaction product by using a 0.22-micron filter membrane to remove solid impurities and prevent the blockage of a chromatographic column.

3. The method of claim 1, wherein the pre-processing comprises:

and (3) carrying out solid-phase extraction pretreatment on the lignin hydrothermal liquefaction product by using a washing agent and an eluent through an HLB (hydrophile-lipophile balance) solid-phase extraction column activated by distilled water, and collecting the eluted solution after pretreatment.

4. The method of claim 3, wherein the detergent comprises n-hexane or water.

5. The method of claim 4, wherein the detergent is n-hexane.

6. The method according to claim 3, wherein the pH value of the hydrothermal liquefaction product of lignin is not adjusted and is directly subjected to a solid phase extraction pretreatment operation.

7. The method according to claim 3, wherein in the pretreatment process, the addition amount of the lignin hydrothermal liquefaction product sample is 1mL, and the dosage of the eluent is 3-7 mL.

8. The method according to claim 7, wherein the amount of the eluent used in the pretreatment process is 4-6 mL.

9. The method of claim 3, wherein the eluent comprises methanol-water solution, methanol-dichloromethane solution, ethyl acetate, acetone, and tetrahydrofuran.

10. The method according to claim 9, wherein the eluent is a methanol-water solution, wherein the volume ratio of methanol to water is 9: 1.

11. The method according to claim 1 or 3, characterized in that the method further comprises:

the eluted solution was subjected to nitrogen blowing to concentrate it.

12. The method of claim 1, wherein the qualitative analysis of the eluted solution using high performance liquid chromatography comprises:

the high performance liquid chromatography adopts a C18 chromatographic column, the mobile phase is methanol and acetic acid aqueous solution or methanol-aqueous solution with the volume fraction of 1%, the flow rate is 0.8-1.2 mL/min, gradient elution is adopted, the temperature of a column incubator is 35-40 ℃, a diode array detector is adopted, the detection wavelength is 278-282 nm, and the detection time is 50-60 min.

13. The method according to claim 1 or 12, wherein the eluted solution is qualitatively analyzed by high performance liquid chromatography in a sample amount of 10 to 20 μ L.

14. The method of claim 12, wherein the mobile phase is methanol and 1% by volume aqueous acetic acid.

15. The method according to claim 12 or 14, wherein the gradient elution procedure is: uniformly increasing the volume content of the methanol in the mobile phase from 12.5-37.5% to 50% within 0-15 min; 15-50min, keeping the volume content of the methanol unchanged at 50%.

16. The method of claim 15, wherein the gradient elution procedure is: uniformly increasing the volume content of the methanol in the mobile phase from 25% to 50% within 0-15 min; 15-50min, keeping the volume content of the methanol unchanged at 50%.

17. The method of claim 1 or 12, further comprising:

if the retention time of the chromatographic peak in the product is consistent with that of the chromatographic peak of the corresponding standard substance, adding the corresponding standard solution into the lignin hydrothermal liquefaction product to obtain a standard solution; and performing high performance liquid chromatography analysis on the standard solution, and comparing the change of the chromatographic peak height of the product in the same retention time before and after standard addition to verify that the product contains corresponding standard substances.

Technical Field

The invention relates to a detection method of a lignin hydrothermal liquefaction product, and belongs to the technical field of biomass utilization.

Background

With the development of industrial technology, fossil energy products have been spread almost throughout the aspects of human life. In recent years, biomass has attracted attention as a carbon neutral energy source due to global energy crisis caused by competition for fossil energy and global warming and ocean acidification caused by carbon emission caused by the massive use of fossil energy. Nowadays, biomass energy is second to petroleum, coal and natural gas, and the total consumption of energy in the world is the fourth, while in developing countries, the consumption proportion of biomass energy can even reach more than 50%.

The lignin, the cellulose and the hemicellulose are three major components forming biomass lignocellulose, the mass content of the lignin, the cellulose and the hemicellulose is about 15-35%, the highest energy content of the three major components is about 40%, and the lignin is the largest renewable aromatic hydrocarbon raw material in the world and has the potential to replace petroleum to produce benzene, toluene, xylene and the like, so that the high-added-value conversion of the lignin has high economic feasibility.

Although lignin has great potential as a renewable energy source in the production of fuels and aromatic chemicals, lignin conversion technology presents great difficulties. The lignin has the characteristics of complex structural connection, easy condensation of active components in the thermochemical conversion process, poor selectivity of degradation products and the like, and is the main reason for preventing the lignin from being degraded into oligomer or micromolecule compounds which can be further converted.

Typical lignin depolymerization methods currently include microbial degradation, high temperature pyrolysis liquefaction, supercritical liquefaction, chemical catalytic depolymerization, photocatalytic depolymerization, co-liquefaction, electrochemical degradation, and the like. In recent years, the hydrothermal liquefaction technology uses supercritical (subcritical) water as a medium, and has gradually become one of the key research fields of green chemistry due to the characteristics of wide sources, low price, no toxicity, easy separation from products and the like, and is expected to convert lignin into a bio-based product, but many problems still need to be solved in the conversion process.

The lignin is decomposed into low molecular weight substances by hydrolysis, etherification, demethoxylation, alkylation and C-C bond cleavage in a hydrothermal medium, and the reactions are carried out while phenols are increased, and oxygen is decarboxylated by dehydration to produce H₂O and CO₂The removal of the reactants is complicated, and in order to increase the conversion and selectivity of lignin, it is necessary to analyze the hydrothermal liquefaction product of lignin to know the composition thereof. In order to meet the requirement, a method for detecting the complete lignin hydrothermal liquefaction product in an aqueous solution quickly and accurately needs to be established.

The hydrothermal liquefaction product of lignin is mainly phenolic compounds, and the existing analysis method of phenolic compounds generally comprises 4-aminoantipyrine spectrophotometry, gas chromatography, liquid chromatography and the like. Wherein, the 4-aminoantipyrine spectrophotometry has large solvent usage amount, long distillation time, poor enrichment effect and easy secondary pollution; the gas chromatography is used for measuring the phenols, liquid-liquid extraction and derivatization reaction are required for many times, and the operation process is complicated; the high performance liquid chromatography is suitable for detecting organic matters with larger molecular weight, high boiling point and poor thermal stability, makes up the defects of gas chromatography, can directly measure the phenolic compounds without derivatization reaction, and has good separation degree and high sensitivity. In addition, compared with the traditional liquid-liquid extraction method, the solid phase extraction method has the advantages of small using amount of organic solvent, small environmental pollution, no emulsification phenomenon, high automation degree, labor saving, high extraction efficiency and the like, and is widely applied to environmental analysis.

Therefore, providing a novel method for detecting a hydrothermal lignin liquefaction product has become a technical problem to be solved urgently in the field.

Disclosure of Invention

In order to solve the above disadvantages and shortcomings, the present invention provides a method for detecting a hydrothermal lignin liquefaction product. According to the detection method of the lignin hydrothermal liquefaction product, firstly, phenolic compounds in the lignin hydrothermal liquefaction product are enriched through a solid phase extraction method, and then, high performance liquid chromatography is used for detection, so that rapid and accurate qualitative analysis on the hydrothermal liquefaction product can be realized.

In order to achieve the above object, the present invention provides a method for detecting a hydrothermal lignin liquefaction product, wherein the method for detecting a hydrothermal lignin liquefaction product comprises:

(1) carrying out solid phase extraction pretreatment on the lignin hydrothermal liquefaction product to obtain an eluted solution;

(2) carrying out qualitative analysis on the eluted solution by using high performance liquid chromatography;

(3) comparing the chromatogram obtained in the step (2) with the chromatogram of the standard substance to determine the composition of the product.

According to a specific embodiment of the present invention, preferably, before the solid phase extraction pretreatment of the hydrothermal lignin liquefaction product, the method further comprises:

and filtering the lignin hydrothermal liquefaction product by using a 0.22-micron filter membrane to remove solid impurities and prevent the blockage of a chromatographic column.

According to a specific embodiment of the present invention, in the method, preferably, the pretreatment comprises:

and (3) carrying out solid-phase extraction pretreatment on the lignin hydrothermal liquefaction product by using a washing agent and an eluent through an HLB (hydrophile-lipophile balance) solid-phase extraction column activated by distilled water, and collecting the eluted solution after pretreatment.

According to a specific embodiment of the present invention, in the method, preferably, the detergent includes n-hexane or water; more preferably, the detergent is n-hexane.

According to the specific embodiment of the invention, in the method, compared with the influence of different pH values of the lignin hydrothermal liquefaction product, such as pH values of 2, 3 and 4 on the phenolic substances in the solid phase extraction, experimental results show that the pH value has little influence on the target substances and can be ignored, so that in the method, the solid phase extraction pretreatment operation can be preferably directly carried out on the lignin hydrothermal liquefaction product without adjusting the pH value.

According to the specific embodiment of the invention, in the method, preferably, the addition amount of the lignin hydrothermal liquefaction product sample is 1mL, and the dosage of the eluent is 3-7 mL; in a specific embodiment of the present invention, the amount of the eluent may be, for example, 3mL, 5mL and 7 mL;

in the method, the dosage of the eluent can be further determined according to the elution effect of the different dosages of the eluent on the phenolic substances in the solid-phase extraction, and more preferably, the dosage of the eluent is 4-6 mL; in a specific embodiment of the present invention, the amount of the eluent may be, for example, 5 mL.

According to an embodiment of the present invention, in the method, preferably, the eluent comprises methanol-water solution, methanol-dichloromethane solution, ethyl acetate, acetone and tetrahydrofuran; in the embodiment of the invention, in the methanol-dichloromethane solution, the volume ratio of methanol to dichloromethane can be 1: 1;

more preferably, the eluent is a methanol-water solution, wherein the volume ratio of methanol to water is 9: 1.

Wherein, when the eluent is a methanol-water solution and the volume ratio of methanol to water is 9:1, the eluent has the best elution effect on the phenolic substances in the solid phase extraction.

According to a specific embodiment of the present invention, in the method, after the eluted solution is qualitatively analyzed by high performance liquid chromatography, if a chromatographic peak height in a chromatogram is found to be small, the eluted solution may be preferably concentrated by nitrogen blowing.

According to a specific embodiment of the present invention, in the method, preferably, the qualitative analysis of the eluted solution by using high performance liquid chromatography comprises:

the high performance liquid chromatography adopts a C18 chromatographic column, the mobile phase is methanol and acetic acid aqueous solution or methanol-aqueous solution with the volume fraction of 1%, the flow rate is 0.8-1.2 mL/min, gradient elution is adopted, the temperature of a column incubator is 35-40 ℃, a diode array detector is adopted, the detection wavelength is 278-282 nm, and the detection time is 50-60 min.

In a specific embodiment of the present invention, the qualitative analysis of the eluted solution by high performance liquid chromatography may be performed according to the following specific steps:

the high performance liquid chromatography adopts C18 chromatographic column, mobile phase is methanol and 1% acetic acid water solution or methanol-water solution with flow rate of 0.8mL/min, gradient elution is adopted, column incubator is 40 deg.C, diode array detector is adopted, detection wavelength is 280nm, and detection time is 50 min.

According to an embodiment of the present invention, in the method, preferably, the sample volume for qualitative analysis of the eluted solution by high performance liquid chromatography is 10 to 20 μ L.

In a specific embodiment of the present invention, the eluted solution is qualitatively analyzed by high performance liquid chromatography in a sample amount of 10. mu.L.

According to a specific embodiment of the present invention, in the method, preferably, the mobile phase is methanol and 1% by volume of an aqueous acetic acid solution. In this case, the elution effect is good.

According to a specific embodiment of the present invention, in the method, preferably, the gradient elution procedure is: uniformly increasing the volume content of the methanol in the mobile phase from 12.5-37.5% to 50% within 0-15 min; 15-50min, keeping the volume content of the methanol unchanged at 50%;

more preferably, the gradient elution procedure is: uniformly increasing the volume content of the methanol in the mobile phase from 25% to 50% within 0-15 min; 15-50min, keeping the volume content of the methanol unchanged at 50%.

In the process of the gradient elution procedure, the volume content of methanol in the mobile phase is uniformly increased from 12.5-37.5% to 50% within 0-15min (the volume content of methanol reaches 50% in 15 min), wherein the volume content of methanol is 50% determined according to the following method:

comparing the elution effects when the volume contents of the methanol in the mobile phase are respectively 90%, 80%, 70%, 60%, 50%, 40%, 30%, 20% and 10% during isocratic elution, and determining that the optimal volume content of the methanol in the mobile phase is 50% during isocratic elution; and determining that the volume content of the methanol reaches 50 percent at 15min in the process of the gradient elution procedure.

Furthermore, in a particular embodiment of the invention, the initial volume content of methanol in the mobile phase may be, for example, 12.5%, 15.625%, 18.75%, 21.285%, 25%, 28.125%, 31.25%, 34.375% and 37.5%.

According to a particular embodiment of the present invention, preferably, the method further comprises:

if the retention time of the chromatographic peak in the product is consistent with that of the chromatographic peak of the corresponding standard substance, adding the corresponding standard solution into the lignin hydrothermal liquefaction product to obtain a standard solution; and performing high performance liquid chromatography analysis on the standard solution, and comparing the change of the chromatographic peak height of the product in the same retention time before and after standard addition to verify that the product contains corresponding standard substances.

Wherein, if the chromatographic peak height of the same retention time in the products before and after the standard addition is obviously increased, the product really contains the corresponding standard substance.

According to an embodiment of the present invention, in the method, the solid phase extraction recovery rate of each substance in the product can be calculated by comparing the response values of the same substance before and after the solid phase extraction.

According to a specific embodiment of the present invention, the solid phase extraction device and the high performance liquid chromatography device used in the method can be experimental devices conventionally used in the art.

According to the detection method of the lignin hydrothermal liquefaction product, firstly, a solid phase extraction device is adopted to separate and enrich the phenolic compounds in the hydrothermal liquefaction product (solid phase extraction pretreatment), so that the concentration of the phenolic compounds in the product is improved, and the detection of the next step is facilitated; secondly, the main substance phenolic compounds in the lignin hydrothermal liquefaction product are effectively analyzed by adopting a high performance liquid chromatography, and then the peak-out time of the product is compared with the peak-out time of a standard substance so as to carry out qualitative analysis on the product.

The method provided by the invention can provide technical support for resource utilization of lignin.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a specific process flow diagram of the detection method of the lignin hydrothermal liquefaction product provided in the embodiment of the invention.

Fig. 2a is a chromatogram obtained after washing with detergent water in the solid-phase extraction process of the hydrothermal lignin liquefaction product provided in example 1 of the present invention.

Fig. 2b is a chromatogram obtained after washing with n-hexane as a detergent in the solid-phase extraction process of the hydrothermal lignin liquefaction product provided in embodiment 1 of the present invention.

Fig. 3 is a chromatogram obtained after 5 eluents elute phenolic substances in the solid-phase extraction process of the hydrothermal lignin liquefaction product provided in example 2 of the present invention.

Fig. 4 is a chromatogram obtained after elution by different amounts of an eluent in a solid-phase extraction process of the hydrothermal lignin liquefaction product provided in example 3 of the present invention.

Fig. 5 is a chromatogram obtained after different gradient elution of the high performance liquid chromatography of the hydrothermal lignin liquefaction product provided in embodiment 4 of the present invention.

Figure 6 is a high performance liquid chromatography assay of the lignin hydrothermal liquefaction product provided in example 5 of the present invention.

Detailed Description

In order to clearly understand the technical features, objects and advantages of the present invention, the following detailed description of the technical solutions of the present invention will be made with reference to the following specific examples, which should not be construed as limiting the implementable scope of the present invention.