Method for analyzing naphthalene compounds in distillates using a multidimensional gas chromatography system

Abstract

A method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, comprising: injecting a measurement sample into a first column through a sample inlet of the multidimensional gas chromatography system, separating the naphthalene-based compounds from other hydrocarbon compounds, and then, under the control of a center-cleavage module, injecting the naphthalene-based compounds into a second column and then into a first detector for analysis to obtain a sample detection spectrum; qualitative and quantitative analysis. The method of the present invention can simultaneously obtain the contents of 15 types of naphthalene-based compound monomers in a fraction through a single direct sample injection, and can particularly separate dimethylnaphthalene-based compounds. The method is simple, reliable, and highly reproducible.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum fraction detection, and specifically, to a method for analyzing naphthalene compounds in fractions by a multidimensional gas chromatography system.

Background Art

[0002] As the demand structure for petroleum products in the market has changed significantly so that the demand for gasoline and aviation kerosene has increased and the demand for diesel oil has decreased, the supply of naphtha cannot meet the demand. Currently, the excess of diesel oil has become the norm, and how to process the excess diesel oil into chemical raw materials or high-value-added power fuels has become an important challenge for increasing the economic benefits of refineries. The fractions at 160 to 400 °C, especially the aromatic hydrocarbons in catalytic cracking diesel oil, have a high content and potential as chemical raw materials.

[0003] Currently, a process route has been reported that reduces the diesel oil / gasoline ratio and increases the production of basic chemical raw materials such as benzene, toluene, and xylene by converting the polycyclic aromatic hydrocarbons abundantly contained in catalytic cracking diesel oil into light aromatic hydrocarbons. TIFF0007912151000001.tif11170

[0004] Furthermore, with the rapid development of high-grade aromatic polymerization materials, the focus of research on novel polymerization materials has shifted from aliphatic polymers to polymers with benzene rings in their chains, and then from those with benzene rings to polymers with naphthalene rings. As a result, there are reports of directly extracting high-value-added compounds from diesel fuel. Taking 2,6-dimethylnaphthalene (2,6-DMN), the most representative compound, as an example, it is an important raw material for synthesizing naphthalene-containing polymers. Polyethylene naphthalate, produced by polymerizing 2,6-naphthalenedicarboxylic acid (generated after its oxidation) with ethylene glycol, is a novel polyester-type material with excellent performance in heat resistance, mechanical properties, gas barrier properties, chemical stability, and radiation resistance. It is widely applied in industries such as electronic components, instruments, and insulating materials, and has very broad future application potential. TIFF0007912151000002.tif11170

[0005] Furthermore, aromatic hydrocarbons, as one of the main components of crude oil, contain a wealth of geochemical information. Generally, the distribution of aromatic hydrocarbons such as naphthalene compounds in crude oil and their carbon stable isotope composition are used to evaluate indicators such as the organic origin and thermal maturity of the crude oil. However, conventional chromatography-mass spectrometry is limited by the separation capability and column capacity of the chromatography column during analysis. Naphthalene compounds tend to form "co-deposit peaks," affecting the peak area integration results, and compounds with low content are susceptible to baseline noise and interference from other substances, making detection impossible. TIFF0007912151000003.tif16170

[0006] In conventional technology, TIFF0007912151000004.tif11170 discloses a method of pre-treating a diesel oil sample to separate it into two parts, saturated hydrocarbons and aromatic hydrocarbons, and then subjecting the aromatic hydrocarbon portion to one-dimensional chromatography to analyze the content of naphthalene compounds. A defect in this technique or a deficiency in the present invention is, TIFF0007912151000005.tif6114 is required, it is time-consuming, and the recovery rate is low. The problem with using TIFF0007912151000006.tif6114 is that it cannot separate 2,6-DMN from 2,7-DMN, and 1,3-DMN from 1,7-DMN, and furthermore, it cannot separate naphthalene compounds such as 1,5-DMN, 1,4-DMN, and 2,3-DMN. TIFF0007912151000007.tif16170 discloses that diesel fuel is pretreated and separated into two parts, saturated hydrocarbons and aromatic hydrocarbons, and the aromatic hydrocarbon portion is analyzed by complete two-dimensional chromatography. Any defects in the said technology or deficiencies in the present invention are, TIFF0007912151000008.tif6114 is required, it is time-consuming, and the recovery rate is low. The problem with using TIFF0007912151000009.tif6114 is that it cannot separate naphthalene compounds such as 2,6-DMN and 2,7-DMN, and 1,3-DMN and 1,7-DMN.

[0007] CN112630312A discloses a method for detecting polycyclic aromatic hydrocarbons in diesel fuel using complete two-dimensional gas chromatography-flame ionization detector, where sample pretreatment is not required and analysis is performed directly by complete two-dimensional chromatography. The drawback of this technique or the invention is that it is mainly used to measure the composition of polycyclic aromatic hydrocarbons and cannot effectively separate naphthalene compounds such as 2,6-DMN and 2,7-DMN, and 1,3-DMN and 1,7-DMN. [Overview of the project] [Problems that the invention aims to solve]

[0008] CN1344930A discloses a method for measuring carbon + heavy aromatic hydrocarbon composition, employing a capillary column with polydimethylsiloxane as the packing material, and disclosing that the measurement method can achieve complete separation of major components in the C9-C12 aromatic hydrocarbon fraction. The defects of this technology or the lack of support for the invention are that it employs a single nonpolar column, fails to achieve baseline separation of 10 dimethylnaphthalenes, and lacks examples to support the technical proposal of the patent. [Means for solving the problem]

[0009] To solve the above technical problems, the present invention aims to provide a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system. This method allows for the simultaneous acquisition of the content of multiple types of naphthalene compound monomers in a fraction through a single direct sample injection analysis, enables baseline separation of each compound, and provides high qualitative and quantitative accuracy.

[0010] To achieve the above objective, the present invention provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, the method comprising the following steps.

[0011] S1: The sample to be measured is placed through the sample inlet of the multidimensional gas chromatography system into a first column with dimethylpolysiloxane having a phenyl group content of 0-5% as the stationary phase, and separated into naphthalene compounds and other hydrocarbon compounds. Under the control of the central cleavage module, the naphthalene compounds are placed into a second column with methylpolysiloxane having 5-20% β-cyclodextrin added as the stationary phase, and then analyzed by placing them in the first detector to obtain the sample detection spectrum.

[0012] S2: The detection spectrum of the sample is compared with the retention time of a naphthalene-based compound standard obtained under the same chromatographic conditions, and a qualitative analysis is performed.

[0013] S3: Analyze external standard solutions of naphthalene compounds under the same chromatographic conditions, and quantitatively analyze the naphthalene compounds in the sample using the external standard method.

[0014] In the method for analyzing naphthalene compounds in distillation at 160-400°C using the multidimensional gas chromatography system described above, the first column preferably has a column length of 20-60 m, an inner diameter of 0.25-0.32 mm, and a flow rate of 0.8-2 mL / min, more preferably 1.1 mL / min.

[0015] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, the second column has a column length of 20 to 60 m, an inner diameter of 0.20 to 0.53 mm, and a flow rate of 2 to 4 mL / min. In the present invention, the second column is selected from columns capable of separating dimethylnaphthalene.

[0016] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, step S1 further includes placing the other hydrocarbon compounds into a third column under the control of a central cleavage module, and then placing them into a second detector for analysis.

[0017] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, in the multidimensional gas chromatography system, the sample inlet is in communication with the inlet of the first column, the outlet of the first column is in communication with the inlet of the central section module, the first outlet of the central section module is in communication with the inlet of the second column, the outlet of the second column is in communication with the first detector, the second outlet of the central section module is in communication with the inlet of the third column, and the outlet of the third column is in communication with the second detector.

[0018] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the central cutting module further includes a microfluidic control module, a carrier gas inlet, a damping column, and a solenoid valve.

[0019] Among them, the microfluidic control module includes a first port formed as an inlet of the central cutting module, a second port communicating with a first outlet of the central cutting module, and a third port communicating with a second outlet of the central cutting module.

[0020] The central cutting module has a switchable first operating state and second operating state. In the first operating state, the solenoid valve is in a closed state so that carrier gas passes through a first carrier gas pipeline and the second outlet and flows into a third column together with components flowing out of a first column, and the carrier gas inlet communicates with the second outlet through the first carrier gas pipeline.

[0021] In the second operating state, the solenoid valve is in an open state so that carrier gas passes through a second carrier gas pipeline and the first outlet and flows into a second column together with components flowing out of the first column, and the carrier gas inlet communicates with the first outlet through the second carrier gas pipeline.

[0022] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the switching time of the solenoid valve in the central cutting is on for 12 - 12.5 min, off for 14 - 14.5 min, on for 15.5 - 16.5 min, and off for 18.5 - 20 min. In the present invention, the cutting time of the multidimensional gas chromatography system can be reasonably controlled, naphthalene compounds can be effectively separated, and the accuracy and stability of the analysis method can be improved.

[0023] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the switching times of the solenoid valves in the center cut are 12.2 min on, 13.5 min off, 16.5 min on, 17.2 min off, 17.3 min on, 18.7 min off, 18.9 min on, 19.3 min off, 19.5 min on, and 19.9 min off.

[0024] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the temperature of the sample injection port is 280 to 310 °C, the sample injection volume is 0.1 to 1 μL, and the split ratio is 80:1 to 250:1.

[0025] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the third column is an immobilized hollow column without a stationary phase, having the same resistance as the second column, a column length of 0.5 to 3.0 m, an inner diameter of 0.10 to 0.32 mm, and a column flow rate of 2 to 4 mL / min.

[0026] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the first detector is a flame ionization detector.

[0027] In the method for analyzing naphthalene compounds in a fraction by the above-mentioned multidimensional gas chromatography system, preferably, the second detector is a thermal conductivity detector, a flame ionization detector, or none.

[0028] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, the carrier gas used in the multidimensional gas chromatography system is helium gas or nitrogen gas, and a programmed heating operation is employed, with programmed heating conditions including an initial temperature of 80 to 120°C, a primary heating rate of 1 to 3°C / min to raise the temperature to 130 to 150°C, a secondary heating rate of 0.5 to 2°C / min to raise the temperature to 170 to 190°C, and constant temperature for 5 to 20 minutes.

[0029] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, the external standard solution is preferably selected from standard solutions containing naphthalene, 1-methylnaphthalene, or 2-methylnaphthalene at concentrations of 0.1 wt% to 10 wt%. In the method of the present invention, by selecting a single external standard of one type of naphthalene compound, accurate and stable measurement results can be obtained, and the steps of the analytical method are greatly simplified.

[0030] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, the naphthalene compound includes one or more of naphthalene, methylnaphthalene, and dimethylnaphthalene (DMN).

[0031] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, the naphthalene compound includes one or more of the following: naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2-ethylnaphthalene, 1-ethylnaphthalene, 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, 1,7-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,6-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,3-dimethylnaphthalene, 1,2-dimethylnaphthalene, and 1,8-dimethylnaphthalene.

[0032] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, the fraction at 160-400°C is a fraction obtained by processing petroleum through petrochemical or coal chemical processes.

[0033] In the method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described above, preferably, the fraction includes at least one fraction from fractions at 160 to 400°C, and more preferably, at least one fraction from fractions at 200 to 250°C. The fraction is selected from coal tar, ethylene tar, catalytic cracking products, or aromatic hydrocarbons.

[0034] The analytical method of the present invention can be used in fields such as raw material evaluation for secondary processing of fractions and identification of oil sources in petroleum exploration and development.

[0035] The technical solution provided by the present invention has the following beneficial effects. This invention provides a chromatographic analysis method for the content of naphthalene compounds in a fraction using multidimensional gas chromatography. By selecting an appropriate chromatography column and rationally controlling the cleavage time, the method of this invention can simultaneously obtain the content of multiple types of naphthalene compound monomers in a fraction with a single direct sample injection, and can particularly separate dimethylnaphthalene compounds. The method is simple, reliable, and highly reproducible, and eliminates the problems of conventional one-dimensional chromatography and full two-dimensional chromatography analysis methods, such as sample pretreatment, complex steps, long analysis times, and the inability to separate dimethylnaphthalene compounds at baseline. [Brief explanation of the drawing]

[0036] [Figure 1] A schematic diagram of the structure of the multidimensional gas chromatography system used in the present invention. [Figure 2] Chromatogram of naphthalene compounds in diesel oil from Example 1. [Modes for carrying out the invention]

[0037] Explanation of symbols in Figure 1: 1. Sample inlet; 2. First column; 3. Center section module; 4. Second column; 5. First detector; 6. Third column; 7. Second detector.

[0038] In order to more clearly understand the constituent elements, objectives, and beneficial effects of the present invention, the technical proposal of the present invention will be described in detail below, but this will not limit the scope of the invention's applicability.

[0039] As shown in Figure 1, the multidimensional gas chromatography system used in each embodiment of the present invention includes a sample inlet 1, a first column 2, a central section module 3, a second column 4, a first detector 5, a third column 6, and a second detector 7.

[0040] Within this structure, the sample inlet 1 communicates with the inlet of the first column 2, the outlet of the first column 2 communicates with the inlet of the central section module 3, the first outlet of the central section module 3 communicates with the inlet of the second column 4, the outlet of the second column 4 communicates with the first detector 5, the second outlet of the central section module 3 communicates with the inlet of the third column 6, and the outlet of the third column 6 communicates with the second detector 7.

[0041] The central cutting module 3 further includes a microfluidic control module, a carrier gas inlet, a damping column, and a solenoid valve, the microfluidic control module includes a first port formed as an inlet of the central cutting module 3, a second port communicating with the first outlet, and a third port communicating with the second outlet, the central cutting module 3 has a switchable first operating state and a second operating state, in the first operating state the solenoid valve is closed and the carrier gas inlet is communicating with the second outlet via the first carrier gas pipeline so that the carrier gas passes through a first carrier gas pipeline and the second outlet and flows into the third column 6 together with the components flowing out of the first column 2, and the carrier gas inlet is communicating with the first outlet via the second carrier gas pipeline.

[0042] The present invention will be described below with reference to specific examples. [Examples]

[0043] Example 1 This example provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system. Specifically, the method is as follows:

[0044] A petrochemical catalytic cracking diesel oil was used as the analytical sample. The temperature of the sample inlet was 280°C, the sample injection volume was 0.1 μL, and the flow ratio was 150:1. Column 1 2 was a column with 0% phenyl group dimethylpolysiloxane as the stationary phase, with specifications of 15 m × 0.25 mm × 0.25 μm and a flow rate of 1.1 mL / min. The valve switching times for the central cutting module 3 were 12.2 min on, 13.5 min off, 16.5 min on, 17.2 min off, 17.3 min on, 18.7 min off, 18.9 min on, 19.3 min off, 19.5 min on, and 19.9 min off. The second column 4 preferably uses (20%-cyanopropyl-phenyl)-methylpolysiloxane with 10% β-cyclodextrin added as the stationary phase, with specifications of 60 m × 0.25 mm × 0.25 μm, and a column flow rate of 2.5 mL / min is maintained for 20 min, followed by 20 mL / min. 2 The flow rate is then reduced to 2.0 mL / min and maintained until the end of the analysis. The third column 6 is a hollow column without a stationary phase, with specifications of 1.5 m × 0.1 mm, and the column flow rate is maintained at 2.5 mL / min for 20 min, then reduced to 20 mL / min. 2 The flow rate is reduced to 2.0 mL / min and maintained until the end of the analysis. The first detector 5 is a flame ionization detector, and the second detector 7 is a thermal conduction detector. The chromatography system uses helium gas as the carrier gas and performs a programmed heating operation. The programmed heating conditions are as follows: initial temperature of 80°C, primary heating rate of 2°C / min to 140°C, then secondary heating rate of 1°C / min to 170°C, followed by 5 minutes of constant temperature maintenance. Under these conditions, the chromatogram of the naphthalene compound is shown in Figure 2.

[0045] A diesel oil solution with a 1-methylnaphthalene concentration of 5.02% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the results are shown in Table 1. The entire chromatographic quantitative analysis process took 1 hour. The external standard sample and the measured diesel oil sample were analyzed once again using the same chromatographic conditions to check the reproducibility of the method, and the results are shown in Table 1.

[0046] [Table 1]

[0047] As can be seen from Table 1, the minimum relative error between the two analysis results was 0%, and the maximum was 1.15%, indicating the good reproducibility of this method.

[0048] The accuracy of this method is examined using the standardized recovery rate of 2-methylnaphthalene. Furthermore, two samples of petrochemical catalytic cracking diesel oil were taken, and 1.56% 2-methylnaphthalene was added to one of them to create a standardized sample. The 2-methylnaphthalene content of both samples was measured according to the multidimensional analysis method described above. The ratio of the 2-methylnaphthalene content in the standardized sample minus the 2-methylnaphthalene content in the unstandardized sample to the theoretical value of the added 2-methylnaphthalene is the standardized recovery rate, which is 98.9%. As can be seen from this, the standardized recovery rate of the samples measured by this method is high, indicating good accuracy of the method.

[0049] This method can simultaneously detect the content of naphthalene compounds in catalytic cracking diesel oil, and as can be seen from the chromatogram, naphthalene compounds are essentially separated from the baseline. The method is simple, accurate, reliable, and suitable for the analysis of naphthalene compounds in catalytic cracking diesel oil.

[0050] Comparative Example 1 This comparative example provides an analytical method for naphthalene compounds in a fraction, specifically as follows:

[0051] According to the SH / T 0606-2005 method, aromatic hydrocarbon components were separated from the catalytically cracked diesel oil of Example 1 and used as analytical samples. The naphthalene compound content in the diesel oil aromatic hydrocarbons was analyzed by gas chromatography-flame ionization detector. A column with 0% phenyl-group dimethylpolysiloxane as the stationary phase was used, with specifications of 30 m × 0.25 mm × 0.25 μm, a sample injection volume of 1.0 μL, a sample inlet temperature of 300 °C, a flow ratio of 15:1, a carrier gas of helium, a flow rate of 1.5 mL / min, an initial column box temperature of 60 °C, held for 2 min, heated to 300 °C at 5 °C / min, and kept at constant temperature for 5 min. A diesel oil solution with a 1-methylnaphthalene concentration of 5.02% was prepared as an external standard solution by the standard addition method. Using the same chromatography conditions, the external standard sample and the measured diesel oil sample were analyzed, and the analytical results are shown in Table 2.

[0052] [Table 2]

[0053] As can be seen from Table 2, one-dimensional chromatography fails to achieve baseline separation of naphthalene compounds, and some dimethylnaphthalene compounds also leak out simultaneously, making baseline separation of all dimethylnaphthalene compounds impossible. The same method was used to analyze the measured diesel oil sample once to check the reproducibility of the method, and the results are shown in Table 2. As can be seen from Table 2, the minimum relative error between the two analysis results was 4.91%, and it could reach a maximum of 25%, indicating that the reproducibility of this method is poor.

[0054] The accuracy of this method will be examined using the standardized recovery rate of 2-methylnaphthalene. Furthermore, two samples of petrochemical catalytic cracking diesel oil were taken, and 1.56% 2-methylnaphthalene was added to one of them to create a standardized sample. The 2-methylnaphthalene content of both samples was measured according to the method of Comparative Example 1. The ratio of the value obtained by subtracting the 2-methylnaphthalene content of the unstandardized sample from the 2-methylnaphthalene content of the standardized sample to the theoretical value of the added 2-methylnaphthalene is the standardized recovery rate, which is 85.9%. As can be seen from this, the standardized recovery rate of the sample measured by the method of Comparative Example 1 was low, indicating that the pretreatment process resulted in the loss of information on the content of naphthalene compounds, leading to low measurement results.

[0055] Comparative Example 2 This comparative example provides an analytical method for naphthalene compounds in a fraction, specifically as follows:

[0056] Aromatic hydrocarbon components were separated from the catalytic cracking diesel oil of Example 1 according to the SH / T 0606-2005 method and used as analytical samples. The complete two-dimensional gas chromatography (GC×GC) system was manufactured by LECO, Inc. in the United States. The GC×GC system consisted of an Agilent 7890 gas chromatograph with a flame ionization detector (FID) and a two-nozzle thermal modulator, and the data processing system was Chroma TOF software. All columns are manufactured by Agilent Technologies, Inc. in the United States. The analytical conditions for the complete two-dimensional chromatography system are as follows: the one-dimensional chromatography column is a dimethylpolysiloxane with 0% phenyl groups as the stationary phase, measuring 50 m × 0.2 mm × 0.5 μm; the two-dimensional column is a (50%-phenyl-group)-methylpolysiloxane with 3 m × 0.1 mm × 0.1 μm; the heating program for the one-dimensional column is to hold at 80°C for 0.2 min, then raise the temperature to 310°C at a rate of 2°C / min and hold for 25 min; and the heating program for the two-dimensional column is to hold at 90°C for 0.2 min, then raise the temperature to 320°C at a rate of 2°C / min and hold for 25 min. The sample inlet temperature is 300°C, the sample injection volume is 1 μL, the flow split ratio is 50:1, the carrier gas is helium, the flow rate is 1.8 mL / min, the modulator temperature is 30°C higher than the one-dimensional furnace temperature, the modulation period is 10 s, and the hot blow time is 2.5 s.

[0057] A diesel oil solution with a 1-methylnaphthalene concentration of 5.02% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 3. The measured diesel oil sample was analyzed once using the same method to check the reproducibility of the method, and the results are shown in Table 3.

[0058] [Table 3]

[0059] As can be seen from Table 3, the minimum relative error between the two analysis results was 4.40%, and it could reach a maximum of 18.75%, indicating poor reproducibility of this method. Complete two-dimensional chromatography failed to achieve baseline separation of naphthalene compounds, and some dimethylnaphthalene compounds leached out simultaneously.

[0060] The accuracy of this method will be examined using the standardized recovery rate of 2-methylnaphthalene. Furthermore, two samples of petrochemical catalytic cracking diesel oil were taken, and 1.56% 2-methylnaphthalene was added to one of them to create a standardized sample. The 2-methylnaphthalene content of both samples was measured according to the method of Comparative Example 2. The ratio of the value obtained by subtracting the 2-methylnaphthalene content of the unstandardized sample from the 2-methylnaphthalene content of the standardized sample to the theoretical value of the added 2-methylnaphthalene is the standardized recovery rate, which is 86.3%. As can be seen from this, the standardized recovery rate of the sample measured by the method of Comparative Example 2 was low, indicating that the pretreatment process resulted in the loss of information on the content of naphthalene compounds, leading to low measurement results.

[0061] Example 2 This embodiment provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, specifically as follows:

[0062] A petrochemical straight-run diesel oil was used as the analytical sample. The temperature of the sample inlet was 290°C, the sample injection volume was 0.5 μL, and the flow ratio was 250:1. The first column 2 was a column with a stationary phase of dimethylpolysiloxane with 5% phenyl groups, with specifications of 60 m × 0.25 mm × 0.5 μm and a flow rate of 2 mL / min. The valve switching time for the central cutting module 3 was 12 min on, 14 min off, 16 min on, and 20 min off. The second column 4 was preferably a methylpolysiloxane with 5% β-cyclodextrin added as the stationary phase, with specifications of 50 m × 0.25 mm × 0.25 μm and a column flow rate of 4 mL / min. The third column 6 was a passivation-type hollow column without a stationary phase, with specifications of 1.28 m × 0.1 mm and a column flow rate of 4 mL / min. The first detector 5 is a flame ionization detector, and the second detector 7 is also a flame ionization detector. The chromatography system uses helium gas as a carrier gas and performs a programmed heating operation. The programmed heating conditions are as follows: the initial temperature is 90°C, the primary heating rate is 1°C / min to raise the temperature to 140°C, then the temperature is raised to 180°C at 1°C / min, and then kept at a constant temperature for 20 minutes.

[0063] A diesel oil solution with a naphthalene concentration of 0.10% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 4. The entire chromatographic quantitative analysis process took 2 hours.

[0064] [Table 4]

[0065] Comparative Example 3 This comparative example provides an analytical method for naphthalene compounds in a fraction, specifically as follows:

[0066] According to the SH / T 0606-2005 method, aromatic hydrocarbon components were separated from the catalytic cracking diesel oil of Example 1 and used as the analytical sample. The sample inlet temperature was 290°C, the sample injection volume was 0.5 μL, and the flow ratio was 250:1. A column with methylpolysiloxane with 8% β-cyclodextrin added as the stationary phase was preferred, with specifications of 50 m × 0.25 mm × 0.25 μm and a column flow rate of 4 mL / min. The detector was a flame ionization detector. The chromatography system used helium gas as the carrier gas and performed a programmed heating operation. The programmed heating conditions were as follows: initial temperature of 90°C, primary heating rate of 1°C / min to 140°C, then heating at 1°C / min to 220°C, followed by 50 min of constant temperature. The entire analytical process took 3.5 hours.

[0067] A diesel oil solution with a naphthalene concentration of 0.10% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatography conditions, and the analytical results are shown in Table 5.

[0068] [Table 5]

[0069] As can be seen from Table 5, when using a methylpolysiloxane column with 8% β-cyclodextrin added to a direct diesel oil aromatic hydrocarbon sample, both naphthalene compounds and some aromatic hydrocarbon compounds leached out, resulting in high analytical values.

[0070] Example 3 This embodiment provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, specifically as follows:

[0071] A petrochemical hydrogenated diesel oil was used as the analytical sample. The temperature of the sample inlet was 300°C, the sample injection volume was 1 μL, and the flow ratio was 80:1. The first column 2 was a dimethylpolysiloxane column with 3% phenyl groups, with specifications of 30 m × 0.32 mm × 0.25 μm and a flow rate of 0.8 mL / min. The valve switching times for the central cutting module 3 were 12.5 min on, 14.5 min off, 15.5 min on, and 18.5 min off. The second column 4 preferably used as a stationary phase of methylpolysiloxane with 15% β-cyclodextrin added, with specifications of 60 m × 0.32 mm × 0.5 μm and a column flow rate of 2 mL / min. The third column 6 was a passivation-type hollow column without a stationary phase, with specifications of 3.0 m × 0.15 mm and a column flow rate of 2 mL / min. The first detector 5 is a flame ionization detector, and the second detector 7 is absent (no detector is connected). The chromatography system uses helium gas as the carrier gas and performs a programmed heating operation. The programmed heating conditions are as follows: the initial temperature is 120°C, the primary heating rate is 3°C / min to 150°C, then the temperature is raised to 190°C at a rate of 2°C / min, and then kept at a constant temperature for 10 minutes.

[0072] A diesel oil solution with a 10.0% 1-methylnaphthalene concentration was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the results are shown in Table 6. The entire chromatographic quantitative analysis process took 1 hour. The external standard sample and the measured diesel oil sample were analyzed once again using the same chromatographic conditions to check the reproducibility of the method, and the results are shown in Table 6.

[0073] [Table 6]

[0074] As can be seen from Table 6, the minimum relative error between the two analysis results was 0.62%, and the maximum was 5.86%, indicating good reproducibility of this method.

[0075] The accuracy of this method is examined using the standardized recovery rate of 1-methylnaphthalene. Furthermore, two samples of petrochemical hydrogenated diesel oil were taken, and 53.65 mg / kg of 2-methylnaphthalene was added to one of them to create a standardized sample. The 1-methylnaphthalene content of both samples was measured according to the multidimensional analysis method described above. The ratio of the 1-methylnaphthalene content in the standardized sample minus the 1-methylnaphthalene content in the unstandardized sample to the theoretical value of the added 1-methylnaphthalene is the standardized recovery rate, which was 101.2%. As can be seen from this, the standardized recovery rate of the samples measured by this method was high, demonstrating the accuracy of the method.

[0076] Example 4 This embodiment provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, specifically as follows:

[0077] A petrochemical coking diesel oil was used as the analytical sample. The temperature of the sample inlet was 310°C, the sample injection volume was 0.2 μL, and the flow ratio was 200:1. The first column 2 was a dimethylpolysiloxane column with 4% phenyl groups, with specifications of 25 m × 0.32 mm × 0.25 μm and a flow rate of 1.5 mL / min. The valve switching times for the central cutting module 3 were 12.3 min on, 14.3 min off, 16.5 min on, and 19 min off. The second column 4 preferably used methylpolysiloxane with 20% β-cyclodextrin added as the stationary phase, with specifications of 50 m × 0.53 mm × 1 μm and a column flow rate of 3 mL / min. The third column 6 was a passivation-type hollow column without a stationary phase, with specifications of 2.5 m × 0.25 mm and a column flow rate of 3 mL / min. The first detector 5 is a flame ionization detector, and the second detector 7 is also a flame ionization detector. The chromatography system uses helium gas as a carrier gas and performs a programmed heating operation. The programmed heating conditions are as follows: the initial temperature is 90°C, the primary heating rate is 2°C / min to 140°C, then the temperature is raised to 180°C at a rate of 0.5°C / min, and then kept at a constant temperature for 10 minutes.

[0078] A diesel oil solution with a 2-methylnaphthalene concentration of 6.32% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 7. The entire chromatographic quantitative analysis process took 1 hour.

[0079] [Table 7]

[0080] Example 5 This embodiment provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, specifically as follows:

[0081] Fischer-Tropsch synthetic diesel oil from a certain company was used as the analytical sample. The sample inlet temperature was 300°C, the sample injection volume was 0.5 μL, and the flow ratio was 100:1. The first column 2 was a dimethylpolysiloxane column with 2% phenyl groups, specifications of 40 m × 0.25 mm × 1 μm, and a flow rate of 1.5 mL / min. The valve switching times for the central cutting module 3 were 12.1 min on, 14.4 min off, 16.1 min on, and 19.3 min off. The second column 4 preferably used a stationary phase of -50% phenyl-methylpolysiloxane with 11% β-cyclodextrin added, specifications of 20 m × 0.25 mm × 1 μm, and a column flow rate of 4 mL / min, held for 20 min, then 20 mL / min. 2 The flow rate is then reduced to 2.0 mL / min and maintained until the end of the analysis. The third column 6 is a passivation-type hollow column without a stationary phase, with specifications of 0.50 m × 0.1 mm, and a column flow rate of 4 mL / min. After being held for 20 min, the flow rate is reduced to 20 mL / min. 2The flow rate is reduced to 2.0 mL / min and maintained until the end of the analysis. The first detector 5 is a flame ionization detector, and the second detector 7 is a flame ionization detector. The chromatography system uses helium gas as the carrier gas and performs a programmed heating operation. The programmed heating conditions are as follows: the initial temperature is 80°C, the primary heating rate is 1.5°C / min to raise the temperature to 130°C, then it is raised to 170°C at a rate of 0.5°C / min, and then kept at a constant temperature for 5 minutes.

[0082] A diesel oil solution with a 1-methylnaphthalene concentration of 0.18% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 8. The entire chromatographic quantitative analysis process took 1 hour.

[0083] [Table 8]

[0084] Example 6 This embodiment provides a method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, specifically as follows:

[0085] A mixed aromatic hydrocarbon from a certain company is used as the analytical sample. The temperature of the sample inlet is 300°C, the sample injection volume is 0.5 μL, and the flow ratio is 100:1. The first column 2 is a column with 0% phenyl group dimethylpolysiloxane as the stationary phase, with specifications of 20 m × 0.53 mm × 0.25 μm and a flow rate of 1.5 mL / min. The valve switching time for the center cutting module 3 is 12 min on, 14 min off, 16 min on, and 20 min off. The second column 4 is preferably a column with 11% β-cyclodextrin added to (10%-cyanopropyl-30%phenyl)-methylpolysiloxane as the stationary phase, with specifications of 40 m × 0.25 mm × 0.25 μm and a column flow rate of 4 mL / min. The third column 6 is a passivation-type hollow column without a stationary phase, with specifications of 1.0 m × 0.1 mm and a column flow rate of 4 mL / min. The first detector 5 is a flame ionization detector, and the second detector 7 is a flame ionization detector. The chromatography system uses helium gas as a carrier gas and performs a programmed heating operation. The programmed heating conditions are as follows: the initial temperature is 80°C, the primary heating rate is 1.5°C / min to raise the temperature to 130°C, then it is raised to 170°C at a rate of 0.5°C / min, and then kept at a constant temperature for 5 minutes.

[0086] A diesel oil solution with a 1-methylnaphthalene concentration of 6.89% was prepared as an external standard solution using the standard addition method. The external standard sample and the measured diesel oil sample were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 9. The entire chromatographic quantitative analysis process took 1 hour.

[0087] [Table 9]

[0088] Comparative Example 4 This comparative example provides an analytical method for naphthalene compounds in a fraction, specifically as follows:

[0089] The sample of Example 6 was analyzed using the method described in the embodiment for carrying out the invention of CN1344930A. The chromatographic conditions were as follows: the stationary phase of the column was polydimethylsiloxane with specifications of 60 m × 0.25 mm × 0.5 μm, helium gas was used as the carrier gas, and a programmed heating operation was performed with an initial temperature of 100°C, then increased to 130°C at a heating rate of 5°C / min for 10 minutes, then increased to 200°C at a heating rate of 15°C / min for 15 minutes, and finally increased to 280°C at a heating rate of 20°C / min for 30 minutes. The vaporization chamber temperature was 250°C, the sample inlet temperature was 300°C, the flow splitting ratio was 100:1, and the column prepressure was 138 kPa. The analysis results are shown in Table 10.

[0090] [Table 10]

[0091] As can be seen from Table 10, the CN1344930A method fails to achieve baseline separation of naphthalene compounds, and some hydrocarbon compounds leach out along with the naphthalene compounds, resulting in inflated analytical results.

Claims

1. A method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, S1: The sample to be measured is placed through the sample inlet of the multidimensional gas chromatography system into a first column with dimethylpolysiloxane having a phenyl group content of 0-5% as the stationary phase, and separated into naphthalene compounds and other hydrocarbon compounds. Under the control of the central cleavage module, the naphthalene compounds are placed into a second column with methylpolysiloxane having 5-20% β-cyclodextrin added as the stationary phase, and then analyzed by placing them in the first detector to obtain a sample detection chromatogram; S2: The detection chromatogram of the sample is compared with the retention time of a naphthalene-based compound standard obtained under the same chromatographic conditions, and a qualitative analysis is performed; S3: Analyze external standard solutions of naphthalene compounds under the same chromatographic conditions, and quantitatively analyze the naphthalene compounds in the sample using the external standard method; A method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, which includes the following steps; The first column has a column length of 20 to 60 m, an inner diameter of 0.25 to 0.32 mm, and a flow rate of 0.8 to 2 mL / min; The second column has a column length of 20 to 60 m, an inner diameter of 0.20 to 0.53 mm, and a flow rate of 2 to 4 mL / min.

2. A method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 1, further comprising, in S1, introducing the other hydrocarbon compounds into a third column under the control of a central cutting module, and then introducing them into a second detector for analysis.

3. A method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system according to claim 2, wherein the sample inlet communicates with the inlet of the first column, the outlet of the first column communicates with the inlet of the central section module, the first outlet of the central section module communicates with the inlet of the second column, the outlet of the second column communicates with the first detector, the second outlet of the central section module communicates with the inlet of the third column, and the outlet of the third column communicates with the second detector.

4. The central cutting module further includes a microfluidic control module, a carrier gas inlet, a damping column, and a solenoid valve. Among these, the microfluidic control module includes a first port formed as an inlet of the central cutting module, a second port communicating with the first outlet of the central cutting module, and a third port communicating with the second outlet of the central cutting module. The central cutting module has a switchable first operating state and a second operating state. In the first operating state, the solenoid valve is closed so that the carrier gas passes through the first carrier gas pipeline and the second outlet of the central cutting module and flows into the third column together with the components flowing out from the first column, and the carrier gas inlet is in communication with the second outlet of the central cutting module via the first carrier gas pipeline. A method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 3, wherein, in the second operating state, the solenoid valve is in an open state so that the carrier gas passes through the second carrier gas pipeline and the first outlet of the central cutting module and flows into the second column together with the components that have flowed out from the first column, and the carrier gas inlet is in communication with the first outlet of the central cutting module via the second carrier gas pipeline.

5. The method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 4, wherein the switching time of the solenoid valve in the central cutting module is 12 to 12.5 min on, 14 to 14.5 min off, 15.5 to 16.5 min on, and 18.5 to 20 min off.

6. A method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the temperature of the sample inlet is 280 to 310°C, the sample injection volume is 0.1 to 1 μL, and the flow splitting ratio is 80:1 to 250:

1.

7. A method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 2, wherein the third column is a passivating hollow column having no stationary phase, the same resistance as the second column, a column length of 0.5 to 3.0 m, an inner diameter of 0.10 to 0.32 mm, and a column flow rate of 2 to 4 mL / min.

8. The method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the first detector is a flame ionization detector.

9. The method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 2, wherein the second detector is a thermal conduction detector or a flame ionization detector.

10. The carrier gas used in multidimensional gas chromatography systems is either helium or nitrogen gas. The programmed heating operation is employed under programmed heating conditions that include an initial temperature of 80-120°C, a primary heating rate of 1-3°C / min to raise the temperature to 130-150°C, a secondary heating rate of 0.5-2°C / min to raise the temperature to 170-190°C, and a constant temperature period of 5-20 minutes. A method for analyzing naphthalene compounds in a fraction using the multidimensional gas chromatography system described in claim 1.

11. The method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the external standard solution is selected from standard solutions having concentrations of naphthalene, 1-methylnaphthalene, or 2-methylnaphthalene of 0.1 wt% to 10 wt%.

12. The method for analyzing a naphthalene-based compound in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the naphthalene-based compound comprises one or more of naphthalene, methylnaphthalene, and dimethylnaphthalene.

13. The method for analyzing a naphthalene compound in a fraction using a multidimensional gas chromatography system according to claim 12, wherein the naphthalene compound comprises one or more of the following: naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2-ethylnaphthalene, 1-ethylnaphthalene, 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, 1,7-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,6-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, 2,3-dimethylnaphthalene, 1,2-dimethylnaphthalene, and 1,8-dimethylnaphthalene.

14. The method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the fraction comprises at least one fraction from fractions obtained at 160 to 400°C.

15. The method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system according to claim 14, wherein the fraction comprises at least one fraction from fractions obtained at 200 to 250°C.

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