Asphalt four-component molecule distinguishing method based on quantum chemical calculation

Abstract

The invention discloses an asphalt four-component molecule distinguishing method based on quantum chemistry calculation. Comprising the following steps: establishing molecular models of asphaltene, colloid, aromatics and saturates; the HOMO-LUMO energy gap, the molecular weight, the sp2 hybridized carbon atom proportion, the average Mayer bond level and the Molecular Polarity Index (MPI) of the four component molecules are calculated by adopting a quantum chemistry calculation method, and the HOMO-LUMO energy gap, the molecular weight, the sp2 hybridized carbon atom proportion, the average Mayer bond level and the Molecular Polarity Index (MPI) of the four component molecules are calculated by adopting a quantum chemistry calculation method; through a Mayer key level, a saturated group component can be distinguished; the asphaltene component can be distinguished through the HOMO-LUMO energy gap and molecular weight; the aromatic component and the colloid component can be distinguished through the three indexes of MPI, the average Mayer bond level and the sp2 hybrid carbon atom proportion. According to the method, multiple indexes are subjected to statistical analysis and multi-aspect comparison, a feasible distinguishing method can be provided for the four components of the asphalt on the nanoscale scale, the efficiency and accuracy of distinguishing the components of the asphalt are expected to be improved, and theoretical guidance is provided for multi-scale research of the performance of the asphalt.

Description

Technical Field

[0001] The invention relates to a method for distinguishing four-component molecules of asphalt based on quantum chemical calculation, and belongs to the civil engineering industry. Background Art

[0002] Asphalt, as a key material for road construction and maintenance, plays an important role in modern transportation infrastructure. In recent years, quantum chemical calculation methods have shown great potential in the field of asphalt. This method can provide a deep understanding of the structure, properties and interactions of asphalt molecules, and can perform statistical analysis on specific properties, thus providing researchers with a nanoscale research tool. However, there are currently few studies on the application of quantum chemical calculations to the differentiation of asphalt components. In the research on the differentiation of asphalt components, the characteristics of some molecules are quite different from the components they belong to, and there is still a lack of methods to quantitatively distinguish the four components of asphalt at the nanoscale. Summary of the invention

[0003] The purpose of the present invention is to provide a method for distinguishing four-component molecules of asphalt based on quantum chemical calculation. The method collects and establishes molecular models of 21 asphaltene molecules, 21 colloid molecules, 13 aromatic components and 9 saturated components, and uses quantum chemical calculation methods to calculate the Mayer bond order, HOMO-LUMO energy gap, molecular weight, sp 2 The hybridized carbon atom ratio and MPI are used to establish a method for distinguishing the four components of asphalt based on quantum chemical calculations. The present invention can improve the efficiency and accuracy of asphalt component distinction, provide theoretical guidance for multi-scale research on asphalt performance, and solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides a method for distinguishing four-component molecules of asphalt based on quantum chemical calculation, which comprises the following steps:

[0005] Step 1: Collect and establish molecular models of 21 asphaltene, 21 colloid molecules, 13 aromatic components and 9 saturated components from literature and databases;

[0006] Step 2: Use Multiwfn software to calculate the HOMO-LUMO energy gap, molecular weight, sp 2 Hybridized carbon atom percentage, Mayer bond order and MPI;

[0007] Step 3: Statistically calculate the Mayer bond order, and you can find that the bond order of the saturated molecules is concentrated at 1.0. Therefore, by calculating the Mayer bond order, you can distinguish the saturated molecules from the four-component molecules.

[0008] Step 4: Draw a scatter plot using the calculated molecular weight and HOMO-LUMO energy gap dual indicators. The scatter plots representing the four components of asphalt clearly form three regions. All molecules with a HOMO-LUMO energy gap greater than 8eV are saturated molecules; all molecules with a HOMO-LUMO energy gap below 4eV and a molecular weight greater than 500g / mol are asphaltene molecules; therefore, asphaltene molecules can be distinguished by molecular weight and HOMO-LUMO energy gap;

[0009] Step 5: The calculated Mayer bond order and atomic charge show that the characteristics of some molecules in the collected aromatic fraction and colloid are obviously different from those of other molecules in the component. After analyzing the characteristics of the two components, these molecules are considered to belong to the other component respectively.

[0010] Step 6: Calculate the MPI and sp of the regrouped colloidal and aromatic molecules 2 Hybridized carbon atom percentage and average Mayer bond order, combined sp 2 The percentage of hybridized carbon atoms, the average Mayer bond order, and the MPI are plotted as scatter plots of colloids and aromatic molecules. It can be seen that aromatic molecules and colloid molecules can be distinguished based on the dividing line; the MPI range of colloids is 3-6.4 kcal / mol, the average Mayer bond order range is 0.975-1.075, and the sp 2 The proportion of hybridized carbon atoms ranges from 10% to 60%; the MPI of aromatic components ranges from 6.4 to 11.5 kcal / mol, the average Mayer bond order ranges from 1.075 to 1.2, and the sp 2 The proportion of hybridized carbon atoms ranges from 60% to 100%.

[0011] In particular, in step 5, the abnormal molecules in the colloid and aromatic components were judged by Mayer bond order and atomic charge. Overall, the relative frequency of π bonds in each molecule in the aromatic component was higher, while the relative frequency of σ bonds in the colloid component was higher. The atomic charge distribution diagram of the two components was drawn, and the peak value of the positive charge region of the colloid molecule was significantly higher than the peak value of the negative charge region.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] 1) A large number of four-component asphalt molecules were collected through literature and databases, and multiple indicators such as HOMO-LUMO energy gap, Mayer bond order and molecular weight were calculated using quantum chemical calculation methods, which can improve the accuracy of asphalt component differentiation.

[0014] 2) Using quantum chemical calculation methods to distinguish the four components of asphalt can provide a deep understanding of the molecular structure, properties and interactions of asphalt, and can provide theoretical guidance for multi-scale research on asphalt performance.

[0015] 3) The four components of asphalt are distinguished by quantum chemical calculation methods at the nanoscale, filling the current lack of quantitative standards for distinguishing the four components of asphalt at the nanoscale.

[0016] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is the Mayer bond order distribution diagram of the four components in the present invention;

[0018] Figure 2 It is a scatter plot of molecular weight and HOMO-LUMO energy gap in the present invention;

[0019] Figure 3 For the colloid and aromatic fraction of the present invention 2 The percentage of hybridized carbon atoms, average Mayer bond order and MPI scatter plot;

[0020] Figure 4 The invention provides a method and process for distinguishing the four component molecules of asphalt. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work are within the scope of protection of the present invention.

[0022] A method for distinguishing four-component molecules of asphalt based on quantum chemical calculations comprises the following steps:

[0023] Step 1: Collect and establish molecular models of 21 asphaltene, 21 colloid molecules, 13 aromatic components and 9 saturated components from literature and databases;

[0024] Step 2: Use Multiwfn software to calculate the HOMO-LUMO energy gap, molecular weight, sp 2 Hybridized carbon atom percentage, Mayer bond order and MPI;

[0025] Step 3: Calculate the Mayer bond order and make a relative frequency distribution diagram of the bond order of the four components of asphalt (such as Figure 1 ) It can be found that the bond orders of saturated molecules are all concentrated at 1.0, so the saturated molecules can be distinguished from the four-component molecules by calculating the Mayer bond order;

[0026] Step 4: Draw a scatter plot using the calculated molecular weight and HOMO-LUMO energy gap dual index (e.g. Figure 2), the scattered points representing the four components of asphalt clearly formed three regions. The molecules with HOMO-LUMO energy gap greater than 8eV are all saturated molecules; the molecules with HOMO-LUMO energy gap below 4eV and molecular weight greater than 500g / mol are all asphaltene molecules; therefore, asphaltene molecules can be distinguished by molecular weight and HOMO-LUMO energy gap;

[0027] Step 5: The calculated Mayer bond order and atomic charge show that the characteristics of some molecules in the collected aromatic fraction and colloid are obviously different from those of other molecules in the component. After analyzing the characteristics of the two components, these molecules are considered to belong to the other component respectively.

[0028] Step 6: Calculate the MPI and sp of the regrouped colloidal and aromatic molecules 2 Hybridized carbon atom percentage and average Mayer bond order, combined sp 2 The percentage of hybridized carbon atoms, the average Mayer bond order and the MPI are plotted as scatter plots of colloidal and aromatic components (e.g. Figure 3 ), it can be seen that the aromatic molecules and the colloid molecules can be distinguished by the dividing line; the MPI range of the colloid is 3-6.4 kcal / mol, the average Mayer bond order range is 0.975-1.075, and the sp 2 The proportion of hybridized carbon atoms ranges from 10% to 60%; the MPI of aromatic components ranges from 6.4 to 11.5 kcal / mol, the average Mayer bond order ranges from 1.075 to 1.2, and the sp 2 The proportion of hybridized carbon atoms ranges from 60% to 100%.

[0029] In particular, in step 5, the abnormal molecules in the colloid and aromatic components were judged by Mayer bond order and atomic charge. Overall, the relative frequency of π bonds in each molecule in the aromatic component was higher, while the relative frequency of σ bonds in the colloid component was higher. The atomic charge distribution diagram of the two components was drawn, and the peak value of the positive charge region of the colloid molecule was significantly higher than the peak value of the negative charge region.

[0030] It can be seen from the above embodiments that Figure 4 As shown in the figure, saturated fractions can be distinguished by Mayer bond order. If the Mayer bond order of a molecule is approximately equal to 1, it can be considered a saturated fraction molecule; asphaltenes can be distinguished by HOMO-LUMO energy gap and molecular weight. If the HOMO-LUMO energy gap of a molecule is in the range of 2.49-3.58 eV and the molecular weight is in the range of 500-2000 g / mol, it is considered an asphaltene molecule; colloidal and aromatic fractions can be distinguished by MPI, average Mayer bond order and sp 2 The MPI range of colloids is 3-6.4 kcal / mol, the average Mayer bond order range is 0.975-1.075, and the sp2 The proportion of hybridized carbon atoms ranges from 10% to 60%; the MPI of aromatic components ranges from 6.4 to 11.5 kcal / mol, the average Mayer bond order ranges from 1.075 to 1.2, and the sp 2 The proportion of hybridized carbon atoms ranges from 60% to 100%.

[0031] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for distinguishing four-component molecules of asphalt based on quantum chemical calculation, characterized in that: The steps include: Step 1: Collect and establish molecular models of 21 asphaltene, 21 colloidal molecules, 13 aromatic components, and 9 saturated components; Step 2: Use quantum chemical calculation methods to calculate the HOMO-LUMO energy gap, molecular weight, sp2 hybridized carbon atom ratio, Mayer bond order and MPI of the four-component molecules; Step 3: From the calculated Mayer bond order, it can be seen that the Mayer bond order of saturated molecules is concentrated at 1.0, so the molecules with a Mayer bond order of 1.0 can be considered to belong to the saturated group; Step 4: Draw a scatter plot using molecular weight and HOMO-LUMO energy gap as dual indicators. It can be observed that the scatter points representing the four components of asphalt clearly form three regions. All molecules with a HOMO-LUMO energy gap greater than 8eV are saturated molecules; all molecules with a HOMO-LUMO energy gap below 4eV and a molecular weight greater than 500g / mol are asphaltene molecules; the regions where the remaining colloid and aromatic molecules are located still partially overlap; Step 5: The calculated Mayer bond order and atomic charge show that the characteristics of some molecules in the collected aromatic fraction and colloid are obviously different from those of other molecules in the component. After analyzing the characteristics of the two components, these molecules are considered to belong to the other component respectively. Step 6: Calculate the MPI, sp2 hybridized carbon atom ratio and average Mayer bond order of the two component molecules after regrouping, and make a scatter plot of the colloid and aromatic components by combining the sp2 hybridized carbon atom ratio, average Mayer bond order and MPI. It can be seen that the aromatic components and the colloid molecules can be distinguished according to the dividing line; the MPI range of the colloid is 3-6.4kcal / mol, the average Mayer bond order range is 0.975-1.075, and the sp2 hybridized carbon atom ratio range is 10%-60%; the MPI range of the aromatic components is 6.4-11.5kcal / mol, the average Mayer bond order range is 1.075-1.2, and the sp2 hybridized carbon atom ratio range is 60%-100%.

2. A method for distinguishing four components of asphalt based on quantum chemical calculation according to claim 1, characterized in that: In step 5, the abnormal molecules in the colloid and aromatic components are judged by Mayer bond order and atomic charge. Overall, the relative frequency of π bonds in the aromatic component is higher, while the relative frequency of σ bonds in the colloid component is higher. The atomic charge distribution diagram of the two components is drawn, and the peak value of the positive charge region of the colloid molecule is significantly higher than the peak value of the negative charge region.

3. A method for distinguishing four components of asphalt based on quantum chemical calculation according to claim 1, characterized in that: In step 6, although the dipole moment and MPI can reflect the polarity of the molecule to a certain extent, the correlation between the two indicators is not high. After combining MPI and considering the abnormal molecules mentioned above, the dipole moment distribution of the colloid and aromatic molecules still has no obvious characteristics, and it is difficult to improve the accuracy of the original distinction. Therefore, MPI is selected as the distinction indicator of the two components.

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