Method for rapidly quantifying content of mesophase in asphalt

Abstract

The invention discloses a method for rapidly quantifying the content of an intermediate phase in asphalt. The method comprises the following steps: S1, respectively measuring the content of quinoline insoluble in the intermediate phase asphalt and the content of quinoline insoluble in an intermediate phase asphalt raw material; s2, respectively measuring the content of the quinoline soluble filtrate of the mesophase pitch and the content of the quinoline soluble filtrate of the mesophase pitch raw material with the relative molecular weight within the range of 370-2000, so as to obtain the content of the quinoline-soluble mesophase in the mesophase pitch; and S3, calculating the content of the pitch mesophase according to the data measured in the step S1 and the step S2. Starting from the formation mechanism of the intermediate phase, the quinoline insoluble and the molecular weight of the quinoline insoluble in the sample are analyzed by adopting a chemical method, the measured crystal is high in accuracy and good in reproducibility, and the analysis is quick and simple.

Description

Technical Field

[0001] The present invention relates to the technical field of mesophase content monitoring and analysis, and in particular to a method for rapidly quantifying the mesophase content of asphalt. Background Art

[0002] Mesophase pitch is an important carbon material precursor. It is a liquid crystal with a distinct interface formed during the heat treatment of heavy aromatic hydrocarbons, exhibiting optical anisotropy. It can be used to prepare high-performance mesophase pitch-based carbon fibers, needle coke, mesophase carbon microspheres, and mesophase pitch-based carbon foams, finding wide applications in composite materials and battery electrode materials. Different products have varying requirements for the composition and size of the mesophase within the mesophase pitch, specifically the anisotropic structure and size.

[0003] At present, both domestic and foreign methods use microscopy to determine the mesophase content based on the characteristic extinction phenomenon of coke. For example, my country adopts the national standard "Determination of the Mesophase Content of Coking Asphalt Products by Light Reflection Microscopic Analysis". This method places the polished coke sample under a microscope, adjusts the focus, and rotates the stage. Red, yellow, and blue will appear to change alternately. The one that does not change color is defined as optically isotropic, otherwise it is anisotropic. The mesophase content of the sample is then calculated by the area method. This method is sensitive to color because it identifies the same and opposite components based on color during calculation. Different analysts have different color sensitivity and image clarity under the microscope, so the analysis results have large errors. At the same time, the sample is the selected block that is broken into the required particles, which is not representative and cannot truly reflect the mesophase content in the overall asphalt. Summary of the Invention

[0004] In response to the defects existing in the prior art, the purpose of the present invention is to provide a method for quickly quantifying the content of the mesophase in asphalt. Starting from the formation mechanism of the mesophase, a chemical method is used to analyze the quinoline insoluble matter and its molecular weight in the sample. The measured crystallization has high accuracy, good repeatability and reproducibility, and the analysis is quick and simple. It can solve the problems of the mesophase content measured by the imaging method failing to truly and accurately reflect the true quality of the product due to unrepresentative samples, large color recognition deviations and human errors.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for quickly quantifying the mesophase content of asphalt, comprising the following steps:

[0007] S1, respectively determining the quinoline insoluble content in mesophase asphalt and mesophase asphalt raw material;

[0008] S2, respectively measuring the content of the mesophase asphalt and the quinoline-soluble matter filtrate of the mesophase asphalt raw material with a relative molecular weight in the range of 370 to 2000, thereby obtaining the content of the mesophase soluble in quinoline in the mesophase asphalt;

[0009] S3, calculating the asphalt mesophase content based on the data measured in steps S1 and S2.

[0010] Preferably, in step S1:

[0011] Take 1-2 g of mesophase asphalt and mesophase asphalt raw material respectively and place them in a glass beaker, add quinoline at 60-90°C, heat and stir until smoke comes out of the cup mouth, continue heating for 20-60s, filter with No. 4 sand core funnel while hot, continue washing with quinoline at 60-90°C 2-3 times, then wash with cold stirring until the filter cake does not change color, then place the sand core funnel in an oven at 160-180°C for 15-20 minutes, then put it in a dryer to cool for 5-10 minutes and weigh it, so as to obtain the quinoline insoluble matter content in the mesophase asphalt and the mesophase asphalt raw material.

[0012] Preferably, in step S2:

[0013] The quinoline soluble filtrate of the mesophase asphalt and the mesophase asphalt raw material was obtained respectively, and the proportion of the relative molecular weight in the range of 370 to 2000 in the above filtrate was analyzed by gel chromatography. The molecular weight proportion obtained from the quinoline soluble filtrate of the mesophase asphalt raw material was used as the molecular weight background subtraction, thereby obtaining the mesophase content soluble in quinoline in the mesophase asphalt.

[0014] Preferably, the calculation formula for the content of the mesophase soluble in quinoline in the mesophase pitch is as follows:

[0015] QS=QS2-QS1

[0016] Where, QS is the content of mesophase soluble in quinoline in mesophase asphalt;

[0017] QS2 is the proportion of the quinoline-soluble filtrate of the mesophase pitch with a relative molecular weight range of 370 to 2000;

[0018] QS1 is the proportion of the quinoline soluble matter filtrate of the mesophase asphalt raw material with a relative molecular weight range of 370 to 2000.

[0019] Preferably, in step S3, the calculation formula for the asphalt mesophase content is as follows:

[0020] MP=QI2-QI1+QS

[0021] Where MP is the asphalt mesophase content;

[0022] QI2 is the quinoline insoluble content of the mesophase pitch;

[0023] QI1 is the quinoline insoluble content of the mesophase pitch feedstock;

[0024] QS is the content of mesophase soluble in quinoline in mesophase pitch.

[0025] The beneficial effects of the present invention are:

[0026] 1. To address the issues of unrepresentative samples, large color recognition deviations, and human error, which result in the inability of imaging methods to accurately and precisely reflect the true quality of the product, the present invention uses a chemical method based on the formation mechanism of the mesophase to quantify the mesophase content in the product. This method provides results with high accuracy, good reproducibility, and fast and simple analysis.

[0027] 2. The present invention adopts a chemical method to analyze the quinoline insoluble matter and molecular weight of the sample, which is relatively mature, has small error, fast speed, high accuracy, and high reproducibility and reproducibility of the analysis results. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to specific examples. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form.

[0029] The traditional method is microscopy, which is greatly affected by color and has large errors introduced by humans, such as the determination of clarity under the microscope, the uniformity of sampling, and the identification of color. These errors greatly reduce the accurate measurement of the mesophase content of the product and have no reference value for monitoring the quality of mesophase asphalt. In addition, the quantification time is long and requires the preparation of focal length films, microscopic observation, and software calculation.

[0030] To address the aforementioned issues, such as the inability of imaging methods to accurately and truly reflect the true quality of the product due to unrepresentative samples, large color recognition deviations, and human errors, the present invention utilizes a chemical method to quantify the mesophase content in the product, based on the mesophase formation mechanism. The results obtained by the method of the present invention are highly accurate, with good reproducibility and reproducibility, and the analysis is quick and simple.

[0031] The principle of the method for rapidly quantifying the mesophase content of asphalt provided by the present invention is as follows: when the mesophase asphalt is heated at 350°C to 450°C, the optically isotropic asphalt undergoes decomposition and polycondensation reactions to form liquid crystals with a condensed fused-ring aromatic structure as the main body. Under the action of surface tension, small mesophase spheres are formed. The small mesophase spheres have a large molecular weight and are usually insoluble in quinoline, and are called secondary quinoline insolubles. The individual small spheres continuously absorb isotropic substances from the mother liquor, and after growing, contacting, melting, rearranging, thickening, deforming and solidifying, they form anisotropic regions, i.e., mesophase components, with a relative molecular weight range of 370 to 2000. Therefore, the anisotropic components, i.e., the main component polymers of the mesophase, are mostly secondary quinoline insolubles, but a small portion has a structure similar to quinoline. According to the principle of like dissolves like, these polymers can be dissolved by quinoline.

[0032] Based on the above analysis principle, the present invention provides a method for rapidly quantifying the content of the mesophase in asphalt, which uses a chemical method to quantify the content of the mesophase in the product, specifically comprising the following steps:

[0033] S1, respectively determining the quinoline insoluble content in mesophase asphalt and mesophase asphalt raw material;

[0034] Specifically, 1 to 2 g of the intermediate phase asphalt and the intermediate phase asphalt raw material are respectively placed in a glass beaker, quinoline at 60 to 90°C is added, and the mixture is heated while stirring until smoke slightly comes out of the cup mouth. After continuing to heat for 20 to 60 seconds, the mixture is filtered while hot with a No. 4 sand core funnel (the No. 4 sand core funnel has been treated with constant weight), and the mixture is continued to be washed with quinoline at 60 to 90°C for 2 to 3 times, and then washed with cold stirring until the filter cake does not change color. After that, the sand core funnel is placed in an oven at 160 to 180°C for 15 to 20 minutes, and then placed in a dryer to cool for 5 to 10 minutes and weighed, thereby obtaining the quinoline insoluble content QI2 in the intermediate phase asphalt and the quinoline insoluble content QI1 in the intermediate phase asphalt raw material. Based on this, the content of secondary quinoline insoluble matter in the intermediate phase asphalt is obtained: QI2-QI1.

[0035] S2, respectively measuring the content of the mesophase asphalt and the quinoline-soluble matter filtrate of the mesophase asphalt raw material with a relative molecular weight in the range of 370 to 2000, thereby obtaining the content of the mesophase soluble in quinoline in the mesophase asphalt;

[0036] Since part of the mesophase can be dissolved in the quinoline insoluble matter, and the relative molecular weight of the mesophase ranges from 370 to 2000, the content of the mesophase soluble in quinoline is obtained by quantitatively measuring the relative molecular weight of the filtrate:

[0037] The quinoline soluble filtrates of the mesophase asphalt and the mesophase asphalt raw material are obtained respectively. Specifically, the filtrate obtained in the process of determining the quinoline insoluble matter in step S1 can be used, and the proportion of the relative molecular weight in the range of 370 to 2000 in the above two filtrates is analyzed by gel chromatography; the molecular weight proportion QS1 obtained from the quinoline soluble filtrate of the mesophase asphalt raw material is used as the molecular weight background subtraction, thereby obtaining the mesophase content soluble in quinoline in the mesophase asphalt, that is, QS=QS2-QS1, wherein QS is the mesophase content soluble in quinoline in the mesophase asphalt; QS2 is the proportion of the quinoline soluble filtrate of the mesophase asphalt with a relative molecular weight in the range of 370 to 2000; QS1 is the proportion of the quinoline soluble filtrate of the mesophase asphalt raw material with a relative molecular weight in the range of 370 to 2000.

[0038] The process of gel chromatography is as follows: 1 ml of the filtrate is taken and placed in a 10 ml volumetric flask, the volume is made up with tetrahydrofuran, 10 ul is injected into the injection port, and finally the relative molecular weight in the filtrate is in the range of 370 to 2000.

[0039] S3, calculating the asphalt mesophase content based on the data measured in step S1 and step S2; wherein the asphalt mesophase content includes the mesophase soluble in quinoline and secondary quinoline insoluble matter, and the content of the secondary quinoline insoluble matter is obtained by the difference between the quinoline insoluble matter content QI2 in the mesophase asphalt and the quinoline insoluble matter content QI1 in the mesophase asphalt raw material, i.e., QI2-QI1;

[0040] The calculation formula for the asphalt mesophase content is as follows:

[0041] MP=QI2-QI1+QS

[0042] Wherein, MP is the mesophase content of asphalt; QI2 is the quinoline insoluble content of mesophase asphalt; QI1 is the quinoline insoluble content of mesophase asphalt raw material; QS is the mesophase content soluble in quinoline in mesophase asphalt.

[0043] The method for rapid quantification of asphalt mesophase content of the present invention is further described below with reference to specific examples.

[0044] Example 1

[0045] The method for rapidly quantifying the asphalt mesophase content in this embodiment adopts the following steps:

[0046] Take 1-2g of special asphalt with a softening point of 280℃ and 1-2g of medium-temperature asphalt with a softening point of 60-80℃, which is a raw material for preparation, respectively, and place them in a 100ml glass beaker. Add 20-40ml of 60-90℃ quinoline, heat and stir on an electric furnace until smoke comes out of the cup mouth, continue heating for 20-60s, filter while hot (No. 4 sand core funnel has been treated with constant weight), continue washing with 10-20ml of 60-90℃ quinoline 2-3 times, then wash with 8-12ml of cold toluene until the filter cake does not change color, place the sand core funnel in a 160-180℃ oven and bake for 15-20min, then put it in a dryer and cool for 5-10mi n and then weighed to obtain the content of the intermediate phase insoluble in quinoline QI2-QI1=26.4%-2.4%=24%, that is, the content of the secondary quinoline insoluble matter; according to the simultaneous analysis of the two quinoline soluble filtrates by gel chromatography with a relative molecular weight range of 370-2000: 1 ml of the filtrate was drawn and placed in a 10 ml volumetric flask, the volume was made up with tetrahydrofuran, 10 ul was injected into the injection port, and finally the standard curve method was used to calculate the intermediate phase content soluble in quinoline QS=QS2-QS1=2.6%-0.1%=2.5%, and the final intermediate phase content MP=QI2-QI1+QS=26.5%, as shown in the table below;

[0047]

[0048]

[0049] As shown in the above table, the mesophase content measured by the method of this embodiment is close to the theoretical value, while the mesophase content measured by the traditional method is far lower than the theoretical value. It can be seen that the method of the present invention has a small error in measuring the mesophase content, a fast speed and a high accuracy.

[0050] Example 2

[0051] The method for rapidly quantifying the asphalt mesophase content in this embodiment adopts the following steps:

[0052] Take 1-2g of mesophase asphalt with a softening point of 170℃ and 1-2g of medium-temperature asphalt with a softening point of 60-80℃, respectively, place them in a 100ml glass beaker, add 20-40ml of 60-90℃ quinoline, heat and stir on an electric furnace until the mouth of the cup slightly smokes, continue heating for 20-60S, filter while hot (No. 4 sand core funnel has been treated with constant weight), continue washing with 10-20ml of 60-90℃ quinoline 2-3 times, then wash with 8-12ml of cold toluene until the filter cake does not change color, place the sand core funnel in a 160-180℃ oven for 15-20min, and then put it in a dryer for cooling. After 5 to 10 minutes of cooling, the weight was weighed to obtain the content of the intermediate phase insoluble in quinoline: QI2-QI1=55%-4%=51%, that is, the content of the secondary quinoline insoluble matter; at the same time, the two quinoline soluble filtrates were analyzed by gel chromatography to determine the proportion of the relative molecular weight range of 370 to 2000: 1 ml of the filtrate was drawn into a 10 ml volumetric flask, the volume was made up with tetrahydrofuran, 10 ul was injected into the injection port, and finally the standard curve method was used to calculate the intermediate phase content soluble in quinoline: QS=QS2-QS1=7%-1%=6%, and the final intermediate phase content MP=QI2-QI1+QS=57%, as shown in the table below;

[0053]

[0054] As shown in the above table, the mesophase content measured by the method of this embodiment is close to the theoretical value, while the mesophase content measured by the traditional method is far lower than the theoretical value. It can be seen that the method of the present invention has a small error in measuring the mesophase content, a fast speed and a high accuracy.

[0055] Example 3

[0056] The method for rapidly quantifying the asphalt mesophase content in this embodiment adopts the following steps:

[0057] Take 1-2g of mesophase asphalt with a softening point of 260℃ and 1-2g of medium-temperature asphalt with a softening point of 60-70℃, which is a raw material for preparation, respectively, and place them in a 100ml glass beaker. Add 20-40ml of quinoline at 60-90℃, heat and stir on an electric furnace until smoke comes out of the cup mouth, continue heating for 20-60S, filter while hot (No. 4 sand core funnel has been treated with constant weight), continue washing with 10-20ml of quinoline at 60-90℃ for 2-3 times, then wash with 8-12ml of cold toluene until the filter cake does not change color, place the sand core funnel in a 160-180℃ oven and bake for 15-20min, then put it in a dryer to cool After 5 to 10 minutes, the weight was weighed to obtain the content of the intermediate phase insoluble in quinoline: QI2-QI1=74%-6%=68%, that is, the content of the secondary quinoline insoluble matter; at the same time, the two quinoline soluble filtrates were analyzed by gel chromatography to determine the proportion of the relative molecular weight range of 370 to 2000: 1 ml of the filtrate was drawn and placed in a 10 ml volumetric flask, the volume was made up with tetrahydrofuran, 10 ul was injected into the injection port, and finally the standard curve method was used to calculate the intermediate phase content soluble in quinoline: QS=QS2-QS1=18%-2%=16%, and the final intermediate phase content MP=QI2-QI1+QS=84%, as shown in the table below;

[0058]

[0059] As shown in the above table, the mesophase content measured by the method of this embodiment is close to the theoretical value, while the mesophase content measured by the traditional method is far lower than the theoretical value. It can be seen that the method of the present invention has a small error in measuring the mesophase content, a fast speed and a high accuracy.

[0060] Example 4

[0061] The method for rapidly quantifying the asphalt mesophase content in this embodiment adopts the following steps:

[0062] Take 1-2g of mesophase asphalt with a softening point of 230℃ and 1-2g of medium-temperature asphalt with a softening point of 50-60℃, which is a raw material for preparation, respectively, and place them in a 100ml glass beaker. Add 20-40ml of 60-90℃ quinoline, heat and stir on an electric furnace until smoke comes out of the cup mouth, continue heating for 20-60S, filter while hot (No. 4 sand core funnel has been treated with constant weight), continue washing with 10-20ml of 60-90℃ quinoline 2-3 times, then wash with 8-12ml of cold toluene until the filter cake does not change color, place the sand core funnel in a 160-180℃ oven for 15-20min, and then put it in a dryer to cool for 5-10m in and then weighed to obtain the content of the intermediate phase insoluble in quinoline QI2-QI1=32.5%-0.5%=32%, that is, the content of secondary quinoline insoluble matter; at the same time, the two quinoline soluble filtrates were analyzed by gel chromatography for the proportion of relative molecular weight in the range of 370-2000: 1 ml of the filtrate was drawn and placed in a 10 ml volumetric flask, the volume was made up with tetrahydrofuran, 10 ul was taken and injected into the injection port, and finally the standard curve method was used to calculate the content of the intermediate phase soluble in quinoline QS=QS2-QS1=5.5%-0.1%=5.4%, and the final intermediate phase content MP=QI2-QI1+QS=37.4%, as shown in the table below;

[0063]

[0064] As shown in the above table, the mesophase content measured by the method of this embodiment is close to the theoretical value, while the mesophase content measured by the traditional method is much higher than the theoretical value. It can be seen that the method of the present invention has a small error in measuring the mesophase content, a fast speed and a high accuracy.

[0065] Example 5

[0066] The method for rapidly quantifying the asphalt mesophase content in this embodiment adopts the following steps:

[0067] Take 1-2g of special asphalt with a softening point of 110℃ and 1-2g of soft asphalt with a softening point of ≯30℃, which is a raw material for preparation, respectively, and place them in a 100ml glass beaker. Add 20-40ml of 60-90℃ quinoline, heat and stir on an electric furnace until smoke comes out of the cup mouth, continue heating for 20-60S, filter while hot (No. 4 sand core funnel has been treated with constant weight), continue washing with 10-20ml of 60-90℃ quinoline 2-3 times, then wash with 8-12ml of cold toluene until the filter cake does not change color, place the sand core funnel in a 160-180℃ oven and bake for 15-20min, then put it in a dryer and cool for 5-10mi n and then weighed to obtain the content of the intermediate phase insoluble in quinoline QI2-QI1=3.1%-0.1%=3%, that is, the content of secondary quinoline insoluble matter; at the same time, the two quinoline soluble filtrates were analyzed by gel chromatography for the proportion of relative molecular weight in the range of 370 to 2000: 1 ml of the filtrate was drawn and placed in a 10 ml volumetric flask, the volume was made up with tetrahydrofuran, 10 ul was taken and injected into the injection port, and finally the standard curve method was used to calculate the content of the intermediate phase soluble in quinoline QS=QS2-QS1=1.25%-0.05%=1.2%, and the final intermediate phase content MP=QI2-QI1+QS=4.2%, as shown in the table below;

[0068]

[0069] As shown in the above table, the mesophase content measured by the method of this embodiment is close to the theoretical value, while the mesophase content measured by the traditional method is much higher than the theoretical value. It can be seen that the method of the present invention has a small error in measuring the mesophase content, a fast speed and a high accuracy.

[0070] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, and all of these should be included in the scope of the claims of the present invention.

Claims

1. A method for rapid quantification of asphalt mesophase content, characterized in that: The following steps are involved: S1, respectively determining the quinoline insoluble content in mesophase asphalt and mesophase asphalt raw material; S2, respectively measuring the content of the mesophase asphalt and the quinoline-soluble matter filtrate of the mesophase asphalt raw material with a relative molecular weight in the range of 370 to 2000, thereby obtaining the content of the mesophase soluble in quinoline in the mesophase asphalt; S3, calculating the asphalt mesophase content based on the data measured in step S1 and step S2.

2. The method for preparing the method for rapidly quantifying the mesophase content of asphalt according to claim 1, characterized in that: In the step S1: Take 1-2 g of mesophase asphalt and mesophase asphalt raw material respectively and place them in a glass beaker, add quinoline at 60-90°C, heat and stir until smoke comes out of the cup mouth, continue heating for 20-60s, filter with a sand core funnel while hot, continue washing with quinoline at 60-90°C 2-3 times, then wash with cold stirring until the filter cake does not change color, then place the sand core funnel in an oven at 160-180°C for 15-20 minutes, then put it in a dryer to cool for 5-10 minutes and weigh it, so as to obtain the quinoline insoluble content in the mesophase asphalt and the mesophase asphalt raw material.

3. The preparation method of the method for rapidly quantifying the mesophase content of asphalt according to claim 2, characterized in that: In the step S2: The quinoline soluble filtrate of the mesophase asphalt and the mesophase asphalt raw material was obtained respectively, and the proportion of the relative molecular weight in the range of 370 to 2000 in the above filtrate was analyzed by gel chromatography. The molecular weight proportion obtained from the quinoline soluble filtrate of the mesophase asphalt raw material was used as the molecular weight background subtraction, thereby obtaining the mesophase content soluble in quinoline in the mesophase asphalt.

4. The method for preparing the method for rapidly quantifying the mesophase content of asphalt according to claim 3, wherein: The calculation formula for the content of the mesophase soluble in quinoline in the mesophase pitch is as follows: QS=QS2-QS1 Where QS is the content of mesophase soluble in quinoline in mesophase asphalt; QS2 is the proportion of the quinoline-soluble filtrate of the mesophase pitch with a relative molecular weight range of 370 to 2000; QS1 is the proportion of the quinoline soluble matter filtrate of the mesophase asphalt raw material with a relative molecular weight range of 370 to 2000.

5. The preparation method of the method for rapidly quantifying the mesophase content of asphalt according to claim 1, characterized in that: In step S3, the calculation formula for the asphalt mesophase content is as follows: MP=QI2-QI1+QS Where MP is the asphalt mesophase content; QI2 is the quinoline insoluble content of the mesophase pitch; QI1 is the quinoline insoluble content of the mesophase pitch feedstock; QS is the content of mesophase soluble in quinoline in mesophase pitch.

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