Analysis of naphthalene compounds in fractions 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 in particular to a method for analyzing naphthalene-based compounds in fractions by a multidimensional gas chromatography system. [Background technology]

[0002] As the market demand for petroleum products changes dramatically, with demand for gasoline and aviation kerosene increasing and demand for diesel declining, naphtha supply is unable to meet demand. Currently, excess diesel is the norm, and how to process excess diesel into chemical feedstock or high-value-added power fuels is an important challenge for increasing refinery economic profits. The 160-400°C fraction, especially catalytic cracking diesel, has a high aromatic hydrocarbon content and potential as a chemical feedstock.

[0003] Currently, a process route has been reported that converts the polycyclic aromatic hydrocarbons abundant in catalytically cracked diesel oil into light aromatic hydrocarbons, thereby reducing the diesel oil / gasoline ratio and increasing the production of basic chemical raw materials such as benzene, toluene, and xylene. TIFF2025535481000002.tif11170

[0004] Furthermore, with the rapid development of high-grade aromatic polymeric materials, the focus of research on new polymeric materials has shifted from aliphatic high polymers to high polymers with benzene rings in the chain, and from those with benzene rings to high polymers with naphthalene rings. Therefore, there have been reports of directly extracting high-value-added compounds from diesel oil. Taking the most representative compound, 2,6-dimethylnaphthalene (2,6-DMN), as an example, as an important raw material for synthesizing naphthalene-containing polymers, the resulting 2,6-naphthalenedicarboxylic acid produced after oxidation is polymerized with ethylene glycol to produce polyethylene naphthalate, a novel polyester-type material with excellent heat resistance, mechanical properties, gas barrier properties, chemical stability, and radiation resistance. It is widely used in industries such as electronic components, instruments, and insulating materials, and has great potential for future applications. TIFF2025535481000003.tif11170

[0005] Furthermore, as one of the major components of crude oil, aromatic hydrocarbons contain a wealth of geochemical information. The distribution of aromatic hydrocarbons, such as naphthalene-based compounds, in crude oil and their stable carbon isotope composition are generally used to evaluate indicators of the organic origin and thermal maturity of crude oil. However, conventional chromatography-mass spectrometry is limited by the separation capacity and column capacity of the chromatography column during analysis, and naphthalene-based compounds and other compounds are prone to forming "co-entrained peaks," which affect the peak area integration results. Low-abundance compounds are prone to baseline noise and interference from other substances, making them difficult to detect. TIFF2025535481000004.tif16170

[0006] In the prior art, TIFF2025535481000005.tif11170 discloses that a diesel oil sample is pretreated and separated into two parts, saturated hydrocarbons and aromatic hydrocarbons, and the aromatic hydrocarbon part is subjected to one-dimensional chromatography to analyze the content of naphthalene-based compounds. The defects of this technology or the shortcomings of the present invention are as follows: TIFF2025535481000006.tif6114 is required, which is time-consuming and has a low recovery rate. TIFF2025535481000007.tif6114, it is not possible to separate 2,6-DMN from 2,7-DMN, 1,3-DMN from 1,7-DMN, and furthermore it is not possible to separate naphthalene compounds such as 1,5-DMN, 1,4-DMN, and 2,3-DMN. TIFF2025535481000008.tif16170 discloses that diesel oil is pre-treated and separated into two fractions, saturated hydrocarbons and aromatic hydrocarbons, and the aromatic hydrocarbon fraction is analyzed by full two-dimensional chromatography. The deficiencies of the art or the inadequacies of the present invention are as follows: TIFF2025535481000009.tif6114 is required, which is time-consuming and has a low recovery rate. The problem is that it is not possible to separate naphthalene compounds such as 2,6-DMN and 2,7-DMN, and 1,3-DMN and 1,7-DMN using TIFF2025535481000010.tif6114.

[0007] CN112630312A discloses a method for detecting polycyclic aromatic hydrocarbons in diesel oil using full two-dimensional gas chromatography-flame ionization detector, in which sample pretreatment is not required and the sample is directly analyzed by full two-dimensional chromatography. The drawback of this technology or the inadequacy of the present invention is that it is mainly used to measure the composition of polycyclic aromatic hydrocarbons, and cannot effectively separate naphthalene-based compounds such as 2,6-DMN and 2,7-DMN, 1,3-DMN and 1,7-DMN. Summary of the Invention [Problem to be solved by the invention]

[0008] CN1344930A discloses a method for determining the composition of carbon and heavy aromatic hydrocarbons, employing a capillary column packed with polydimethylsiloxane, and demonstrating that the method can achieve complete separation of the major components in the C9-C12 aromatic hydrocarbon fraction. The deficiencies of this technology or the inadequacies of the present invention are that it employs a single non-polar column, which fails to achieve baseline separation of the 10 dimethylnaphthalenes, and there are no examples to support the technical solution of this patent. [Means for solving the problem]

[0009] In order to solve the above technical problems, the present invention aims to provide a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, which can simultaneously obtain the contents of multiple naphthalene-based compound monomers in a fraction through a single direct sample injection analysis, achieve baseline separation of each compound, and achieve high accuracy in qualitative and quantitative analysis.

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

[0011] S1: The measurement sample is introduced into the first column, which uses dimethylpolysiloxane with a phenyl group content of 0 to 5% as the stationary phase, via the sample inlet of the multidimensional gas chromatography system. The naphthalene-based compounds are separated from other hydrocarbon-based compounds. Under the control of the center cleavage module, the naphthalene-based compounds are introduced into the second column, which uses methylpolysiloxane with 5 to 20% β-cyclodextrin as the stationary phase. The naphthalene-based compounds are then introduced into the first detector for analysis, and a sample detection spectrum is obtained.

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

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

[0014] In the above-mentioned method for analyzing naphthalene-based compounds in a fraction obtained at 160 to 400°C using a multidimensional gas chromatography system, the first column preferably 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, more preferably 1.1 mL / min.

[0015] In the above-mentioned method for analyzing naphthalene compounds in a fraction using a multidimensional gas chromatography system, the second column preferably 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 above-mentioned method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, S1 preferably further includes feeding the other hydrocarbon-based compounds into a third column under the control of a center-cleavage module, and then feeding them into a second detector for analysis.

[0017] In the above-mentioned method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, preferably, in the multidimensional gas chromatography system, the sample injection port is connected to the inlet of the first column, the outlet of the first column is connected to the inlet of the center cutting module, the first outlet of the center cutting module is connected to the inlet of the second column, the outlet of the second column is connected to the first detector, the second outlet of the center cutting module is connected to the inlet of the third column, and the outlet of the third column is connected to the second detector.

[0018] In the method for analyzing naphthalene-based compounds in a fraction using the above multidimensional gas chromatography system, the center cutting module preferably further includes a microfluidic control module, a carrier gas inlet, a damping column, and an electromagnetic valve.

[0019] Wherein, 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 center cutting module has a switchable first operating state and a second operating state, and in the first operating state, the solenoid valve is in a closed state and the carrier gas inlet is connected to the second outlet via the first carrier gas line so that the carrier gas passes through the first carrier gas line, the second outlet, and flows into the third column together with the components flowing out of the first column.

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

[0022] In the above-mentioned method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, the switching times of the solenoid valves during the center cut are preferably 12 to 12.5 minutes on, 14 to 14.5 minutes off, 15.5 to 16.5 minutes on, and 18.5 to 20 minutes off. By rationally controlling the cut times of the multidimensional gas chromatography system, the present invention can effectively separate naphthalene-based compounds and improve the accuracy and stability of the analytical method.

[0023] In the method for analyzing naphthalene-based compounds in a fraction using the above-mentioned multidimensional gas chromatography system, the switching times of the solenoid valve in the center disconnection are preferably 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 above-mentioned method for analyzing naphthalene-based compounds in fractions using a multidimensional gas chromatography system, the temperature of the sample injection port is preferably 280 to 310°C, the sample injection amount is 0.1 to 1 μL, and the split ratio is preferably 80:1 to 250:1.

[0025] In the above-mentioned method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, the third column is preferably a passivated 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.

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

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

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

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

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

[0031] In the above-described method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, the naphthalene-based compounds preferably include one or more of 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 above-mentioned method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, the fraction at 160 to 400°C is preferably a fraction at 160 to 400°C obtained by processing petroleum through a petrochemical or coal chemical process.

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

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

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

[0036] [Figure 1] FIG. 1 is a structural schematic diagram of a multidimensional gas chromatography system used in the present invention. [Figure 2] Chromatogram of naphthalene-based compounds in diesel oil in Example 1. DETAILED DESCRIPTION OF THE INVENTION

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

[0038] In order to make the features, objectives and beneficial effects of the present invention more clearly understood, the technical solution of the present invention will be described in detail below, but not to limit the scope of the present invention.

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

[0040] The sample injection port 1 is connected to the inlet of the first column 2, the outlet of the first column 2 is connected to the inlet of the central cutting module 3, the first outlet of the central cutting module 3 is connected to the inlet of the second column 4, the outlet of the second column 4 is connected to the first detector 5, the second outlet of the central cutting module 3 is connected to the inlet of the third column 6, and the outlet of the third column 6 is connected to 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 the 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 first and a second switchable operating state. In the first operating state, the solenoid valve is closed, and the carrier gas inlet is connected to the second outlet via the first carrier gas line, so that the carrier gas passes through the first carrier gas line and the second outlet to enter the third column 6 together with the components flowing out of the first column 2. In the second operating state, the solenoid valve is open, and the carrier gas inlet is connected to the first outlet via the second carrier gas line, so that the carrier gas passes through the second carrier gas line and the first outlet to enter the second column 4 together with the components flowing out of the first column 2.

[0042] The present invention will now be described with reference to specific examples. [Example]

[0043] Example 1 In this example, a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system is provided. Specifically, the method is as follows.

[0044] The analytical sample was a petroleum-based catalytically cracked diesel oil. The sample injection temperature was 280°C, the sample injection volume was 0.1 μL, and the split ratio was 150:1. The first column 2 was a column with a 0% phenyl group dimethylpolysiloxane stationary phase, with dimensions of 15 m x 0.25 mm x 0.25 μm and a flow rate of 1.1 mL / min. The valve switching times for the center 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 has a stationary phase of (20%-cyanopropyl-phenyl)-methylpolysiloxane with 10% β-cyclodextrin added, and has a size of 60 m × 0.25 mm × 0.25 μm. The column flow rate is 2.5 mL / min, held for 20 minutes, and then increased to 20 mL / min. 2 The third column 6 is a passivated hollow column without a stationary phase, with a size of 1.5 m x 0.1 mm. The column flow rate is maintained at 2.5 mL / min for 20 minutes, and then reduced to 2.0 mL / min. 2 The flow rate is then 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 conductivity detector. The chromatography system uses helium gas as the carrier gas and performs a programmed temperature ramp operation. The programmed temperature ramp conditions are an initial temperature of 80°C, a first ramp rate of 2°C / min to 140°C, a second ramp rate of 1°C / min to 170°C, and a constant temperature of 5 minutes. Figure 2 shows the chromatogram of naphthalene-based compounds under these conditions.

[0045] A diesel oil solution with a 5.02% 1-methylnaphthalene concentration was prepared as an external standard solution using the standard addition method. The external standard and the test diesel oil samples were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 1. The entire chromatographic quantitative analysis process took 1 h. The external standard and the test diesel oil samples were analyzed once using the same chromatographic conditions to examine 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 analytical results was 0% and the maximum was 1.15%, indicating good reproducibility of this method.

[0048] The accuracy of this method was examined using the standardized recovery rate of 2-methylnaphthalene. Two petroleum catalytic cracking diesel oil samples 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 using 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 was the standardized recovery rate, which was 98.9%. As can be seen, the standardized recovery rate of the samples measured using this method was high, demonstrating good accuracy.

[0049] This method can simultaneously detect the content of naphthalene-based compounds in catalytically cracked diesel oil, and as can be seen from the chromatogram, the naphthalene-based compounds basically achieve baseline separation. The method is simple, accurate, and reliable, and is suitable for the analysis of naphthalene-based compounds in catalytically cracked diesel oil.

[0050] Comparative Example 1 This comparative example provides a method for analyzing naphthalene-based compounds in a fraction, and is specifically as follows.

[0051] The aromatic hydrocarbon components in the catalytically cracked diesel oil of Example 1 were separated according to the SH / T 0606-2005 method and used as an analytical sample. The content of naphthalene-based compounds in the diesel aromatic hydrocarbons was analyzed using gas chromatography-flame ionization detection. A column with a 0% phenyl group dimethylpolysiloxane stationary phase was used, with dimensions of 30 m x 0.25 mm x 0.25 μm, a sample injection volume of 1.0 μL, a sample inlet temperature of 300°C, a split flow ratio of 15:1, helium as the carrier gas, and a flow rate of 1.5 mL / min. The column box was initially heated to 60°C, held for 2 minutes, then heated to 300°C at a rate of 5°C / min and held at a constant temperature for 5 minutes. 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. The analytical results are shown in Table 2.

[0052] [Table 2]

[0053] As can be seen from Table 2, one-dimensional chromatography cannot achieve baseline separation of naphthalene compounds, and some dimethylnaphthalene compounds are also eluted at the same time, making it impossible to achieve baseline separation of all dimethylnaphthalene compounds. Using the same method, a diesel oil sample was analyzed once to check the reproducibility of the method, and the results are shown in Table 2. As can be seen from Table 2, the smallest relative error between the two analytical results was 4.91%, with a maximum of 25%, indicating poor reproducibility of this method.

[0054] The accuracy of this method was examined using the standardized recovery rate of 2-methylnaphthalene. Two petroleum catalytic cracking diesel oil samples 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 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 was 85.9%. As can be seen, the standardized recovery rate of the sample measured using the method of Comparative Example 1 was low, indicating that the pretreatment process resulted in the loss of information about the content of naphthalene-based compounds, resulting in low measurement results.

[0055] Comparative Example 2 This comparative example provides a method for analyzing naphthalene-based compounds in a fraction, and is specifically as follows.

[0056] According to the SH / T 0606-2005 method, the aromatic hydrocarbon components in the catalytically cracked diesel oil of Example 1 were separated and used as an analytical sample. The fully two-dimensional gas chromatography (GC×GC) was manufactured by LECO, USA. The GC×GC system consisted of an Agilent 7890 gas chromatograph equipped with a flame ionization detector (FID) and a two-nozzle thermal modulator, and the data processing system was Chroma TOF software. All columns were manufactured by Agilent Technologies, USA. The analytical conditions for the fully two-dimensional chromatography system were as follows: the first-dimensional chromatography column was a 50m x 0.2mm x 0.5μm column with a 0% phenyl group dimethylpolysiloxane stationary phase; the second-dimensional column was a 3m x 0.1mm x 0.1μm column with a (50%-phenyl group)-methylpolysiloxane stationary phase; the heating program for the first-dimensional column was 80°C for 0.2 minutes, then increased to 310°C at 2°C / min and held there for 25 minutes; and the heating program for the second-dimensional column was 90°C for 0.2 minutes, then increased to 320°C at 2°C / min and held there for 25 minutes. The temperature of the sample injection port was 300°C, the sample injection volume was 1 μL, the split flow ratio was 50:1, the carrier gas was helium, the flow rate was 1.8 mL / min, the temperature of the modulator was 30°C higher than that of the one-dimensional furnace, and the modulation period was 10 s, except for the hot blow time of 2.5 s.

[0057] A diesel oil solution with a 5.02% 1-methylnaphthalene concentration was prepared as an external standard solution using the standard addition method. The external standard sample and the test diesel oil sample were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 3. The test diesel oil sample was analyzed once using the same method to examine 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 analytical results was 4.40% and the maximum could reach 18.75%, indicating the poor reproducibility of this method. Full two-dimensional chromatography could not achieve baseline separation of naphthalene-based compounds, and some dimethylnaphthalene-based compounds were coeluted.

[0060] The accuracy of this method was examined using the standardized recovery rate of 2-methylnaphthalene. Two petroleum catalytic cracking diesel oil samples 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 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 was 86.3%. As can be seen, the standardized recovery rate of the sample measured using the method of Comparative Example 2 was low, indicating that the pretreatment process resulted in the loss of information about the content of naphthalene-based compounds, resulting in low measurement results.

[0061] Example 2 This example provides a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, and is specifically as follows.

[0062] A petroleum straight-run diesel oil was used as the analytical sample. The sample injection port temperature was 290°C, the sample injection volume was 0.5 μL, and the split ratio was 250:1. The first column 2 was a column with a 5% phenyl group dimethylpolysiloxane stationary phase, with dimensions of 60 m x 0.25 mm x 0.5 μm and a flow rate of 2 mL / min. The valve switching time of the center-cutting module 3 was 12 min on, 14 min off, 16 min on, and 20 min off. The second column 4 preferably had a methylpolysiloxane stationary phase with 5% β-cyclodextrin added, with dimensions of 50 m x 0.25 mm x 0.25 μm and a column flow rate of 4 mL / min. The third column 6 was a passivated hollow column without a stationary phase, with dimensions of 1.28 m x 0.1 mm and a column flow rate of 4 mL / min. The first detector 5 is a hydrogen flame ionization detector, and the second detector 7 is a hydrogen flame ionization detector. The chromatography system uses helium gas as a carrier gas and performs a programmed temperature rise operation. The programmed temperature rise conditions are an initial temperature of 90°C, a primary temperature rise rate of 1°C / min to 140°C, then a temperature rise rate of 1°C / min to 180°C, and a constant temperature for 20 minutes.

[0063] A diesel oil solution with a 0.10% naphthalene concentration was prepared as an external standard solution using the standard addition method. The external standard sample and the test diesel oil sample were analyzed using the same chromatographic conditions. 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 a method for analyzing naphthalene-based compounds in a fraction, and is specifically as follows.

[0066] The aromatic hydrocarbon components in the catalytically cracked diesel oil of Example 1 were separated and used as the analytical sample according to the SH / T 0606-2005 method. The sample injection port temperature was 290°C, the sample injection volume was 0.5 μL, and the split ratio was 250:1. The column preferably used a methylpolysiloxane stationary phase containing 8% β-cyclodextrin, with dimensions of 50 m x 0.25 mm x 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 an initial temperature of 90°C, a primary heating rate of 1°C / min to 140°C, followed by a 50-minute constant temperature increase to 220°C at 1°C / min. The entire analysis process took 3.5 hours.

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

[0068] [Table 5]

[0069] As can be seen from Table 5, when a diesel aromatic hydrocarbon sample was directly passed through a methylpolysiloxane column containing 8% β-cyclodextrin, naphthalene compounds and some aromatic hydrocarbon compounds were both eluted, resulting in high analytical results.

[0070] Example 3 This example provides a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, and is specifically as follows.

[0071] A petroleum-hydrogenated diesel oil was used as the analytical sample. The sample injection temperature was 300°C, the sample injection volume was 1 μL, and the split ratio was 80:1. The first column 2 was a 3% phenyl group dimethylpolysiloxane column with dimensions of 30 m x 0.32 mm x 0.25 μm and a flow rate of 0.8 mL / min. The valve switching time of the center-cutting module 3 was 12.5 min on, 14.5 min off, 15.5 min on, and 18.5 min off. The second column 4 preferably had a stationary phase of methylpolysiloxane with 15% β-cyclodextrin added, dimensions of 60 m x 0.32 mm x 0.5 μm, and a column flow rate of 2 mL / min. The third column 6 was a passivated hollow column without a stationary phase, dimensions of 3.0 m x 0.15 mm, and a column flow rate of 2 mL / min. The first detector 5 is a hydrogen flame ionization detector, and there is no second detector 7 (no detector is connected). The chromatography system uses helium gas as the carrier gas and performs a programmed temperature increase operation. The programmed temperature increase conditions are an initial temperature of 120°C, a primary temperature increase rate of 3°C / min to 150°C, then a temperature increase rate of 2°C / min to 190°C, and 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 and the test diesel oil samples were analyzed using the same chromatographic conditions, and the analytical results are shown in Table 6. The entire chromatographic quantitative analysis process took 1 h. The external standard and the test diesel oil samples were analyzed once using the same chromatographic conditions to examine 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 analytical results was 0.62% and the maximum was 5.86%, indicating that the method has good reproducibility.

[0075] The accuracy of this method was examined using the standardized recovery rate of 1-methylnaphthalene. Two petroleum-hydrogenated diesel oil samples 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 using 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 was the standardized recovery rate, which was 101.2%. As can be seen, the standardized recovery rate of the samples measured using this method was high, demonstrating the good accuracy of the method.

[0076] Example 4 This example provides a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, and is specifically as follows.

[0077] The analytical sample was a petroleum-coked diesel oil. The sample injection temperature was 310°C, the sample injection volume was 0.2 μL, and the split ratio was 200:1. The first column 2 was a 4% phenyl group dimethylpolysiloxane column with dimensions of 25 m x 0.32 mm x 0.25 μm and a flow rate of 1.5 mL / min. The valve switching time of the center-cutting module 3 was 12.3 min on, 14.3 min off, 16.5 min on, and 19 min off. The second column 4 preferably had a stationary phase of methylpolysiloxane with 20% β-cyclodextrin added, with dimensions of 50 m x 0.53 mm x 1 μm and a column flow rate of 3 mL / min. The third column 6 was a passivated hollow column without a stationary phase, with dimensions of 2.5 m x 0.25 mm and a column flow rate of 3 mL / min. The first detector 5 is a hydrogen flame ionization detector, and the second detector 7 is a hydrogen flame ionization detector. The chromatography system uses helium gas as a carrier gas and performs a programmed temperature ramp operation. The programmed temperature ramp conditions are an initial temperature of 90°C, a primary ramp rate of 2°C / min to 140°C, then a ramp rate of 0.5°C / min to 180°C, and a constant temperature of 10 minutes.

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

[0079] [Table 7]

[0080] Example 5 This example provides a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, and is specifically as follows.

[0081] The analytical sample was a Fischer-Tropsch synthetic diesel oil from a certain company. The sample injection port temperature was 300°C, the sample injection volume was 0.5 μL, and the split flow ratio was 100:1. The first column 2 was a 2% phenyl dimethylpolysiloxane column with a 40 m x 0.25 mm x 1 μm diameter and a flow rate of 1.5 mL / min. The valve switching times for the center-cleavage 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 had a 50% phenyl-methylpolysiloxane stationary phase with 11% β-cyclodextrin added, a 20 m x 0.25 mm x 1 μm diameter and a column flow rate of 4 mL / min, followed by a 20-min hold and then a 20 mL / min hold. 2 The third column 6 is a passivated hollow column without a stationary phase, with a size of 0.50 m x 0.1 mm, and the column flow rate is 4 mL / min. After 20 minutes of retention, the flow rate is reduced to 2.0 mL / min. 2The flow rate is then reduced to 2.0 mL / min and maintained until the end of the analysis. The first detector 5 is a hydrogen flame ionization detector, and the second detector 7 is also a hydrogen flame ionization detector. The chromatography system uses helium gas as the carrier gas and performs a programmed temperature rise operation. The programmed temperature rise conditions are an initial temperature of 80°C, a primary temperature rise rate of 1.5°C / min to 130°C, then a temperature rise rate of 0.5°C / min to 170°C, and a constant temperature of 5 minutes.

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

[0083] [Table 8]

[0084] Example 6 This example provides a method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, and is specifically as follows.

[0085] The analytical sample is a mixed aromatic hydrocarbon from a certain company. The sample injection port temperature is 300°C, the sample injection volume is 0.5 μL, and the split ratio is 100:1. The first column 2 is a column with a 0% phenyl group dimethylpolysiloxane stationary phase, with dimensions of 20 m x 0.53 mm x 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 a (10%-cyanopropyl-30% phenyl)-methylpolysiloxane stationary phase with 11% β-cyclodextrin added, with dimensions of 40 m x 0.25 mm x 0.25 μm, and a column flow rate of 4 mL / min. The third column 6 is a passivated hollow column without a stationary phase, measuring 1.0 m x 0.1 mm, with 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 the carrier gas and performs a programmed temperature ramp operation. The programmed temperature ramp conditions are as follows: initial temperature 80°C, a primary ramp rate of 1.5°C / min to 130°C, then a ramp rate of 0.5°C / min to 170°C, and a constant temperature of 5 minutes.

[0086] A diesel oil solution with a 6.89% 1-methylnaphthalene concentration was prepared as an external standard solution using the standard addition method. The external standard sample and the test diesel oil sample were analyzed using the same chromatographic conditions. 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 a method for analyzing naphthalene-based compounds in a fraction, and is specifically as follows.

[0089] The sample of Example 6 was analyzed using the method described in the detailed description of the invention in CN1344930A. The chromatography conditions were as follows: the column stationary phase was polydimethylsiloxane, the dimensions were 60m x 0.25mm x 0.5μm, helium gas was used as the carrier gas, and a programmed heating operation was performed, with the initial temperature being 100°C, followed by a heating rate of 5°C / min to 130°C, where it remained for 10 minutes, then a heating rate of 15°C / min to 200°C, where it remained for 15 minutes, and finally a heating rate of 20°C / min to 280°C, where it remained for 30 minutes, the vaporizer temperature was 250°C, the sample injection port temperature was 300°C, the flow ratio was 100:1, and the pressure in front of the column was 138kPa. The analytical results are shown in Table 10.

[0090] [Table 10]

[0091] As can be seen from Table 10, the CN1344930A method cannot achieve baseline separation of naphthalene-based compounds, and some hydrocarbon-based compounds flow out together with naphthalene-based compounds, resulting in higher analytical results.

Claims

1. A method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, comprising: S1: The measurement sample is injected into the first column of the multidimensional gas chromatography system through the sample inlet, with dimethylpolysiloxane having a phenyl content of 0-5% as the stationary phase, to separate it into naphthalene-based compounds and other hydrocarbon-based compounds. Under the control of the center-cleavage module, the naphthalene-based compounds are injected into the second column of methylpolysiloxane containing 5%-20% β-cyclodextrin as the stationary phase, and then into the first detector for analysis, to obtain the sample detection spectrum; S2: Qualitative analysis is performed by comparing the sample detection spectrum with the retention time of a naphthalene compound standard obtained under the same chromatographic conditions; S3: Analyze an external standard solution of naphthalene-based compounds under the same chromatographic conditions, and quantitatively analyze the naphthalene-based compounds in the sample by the external standard method; A method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system, comprising the steps of:

2. 2. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein 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.

3. 2. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein 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.

4. 2. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 1, further comprising: in step S1, under the control of a center cutting module, feeding the other hydrocarbon-based compounds into a third column and then into a second detector for analysis.

5. 5. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 4, wherein in the multidimensional gas chromatography system, the sample injection port is connected to the inlet of a first column, the outlet of the first column is connected to the inlet of a center cutting module, the first outlet of the center cutting module is connected to the inlet of a second column, the outlet of the second column is connected to a first detector, the second outlet of the center cutting module is connected to the inlet of a third column, and the outlet of the third column is connected to a second detector.

6. the center cutting module further comprises a microfluidic control module, a carrier gas inlet, a damping column, and a solenoid valve; Wherein, 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; the center cutting module has a switchable first operating state and a switchable second operating state; In the first operating state, the solenoid valve is in a closed state, and the carrier gas inlet is in communication with the second outlet of the center cutting module via the first carrier gas line, so that the carrier gas passes through the first carrier gas line, the second outlet of the center cutting module, and flows into the third column together with the components flowing out of the first column; 6. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 5, wherein in the second operating state, the solenoid valve is in an open state, and the carrier gas inlet is in communication with the first outlet of the center cutting module via a second carrier gas line, so that the carrier gas passes through a second carrier gas line and the first outlet of the center cutting module and flows into the second column together with components flowing out of the first column.

7. 7. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 6, wherein the switching times of the solenoid valves in the center disconnection are 12 to 12.5 minutes on, 14 to 14.5 minutes off, 15.5 to 16.5 minutes on, and 18.5 to 20 minutes off.

8. 2. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the temperature of the sample injection port is 280 to 310°C, the sample injection amount is 0.1 to 1 μL, and the split ratio is 80:1 to 250:

1.

9. 5. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 4, wherein the third column is a passivated 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.

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

11. 5. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 4, wherein the second detector is a thermal conductivity detector, a flame ionization detector, or none.

12. The carrier gas used in the multidimensional gas chromatography system is helium gas or nitrogen gas. The programmed heating operation is adopted under the following conditions: initial temperature is 80-120°C, the first heating rate is 1-3°C / min, the temperature is raised to 130-150°C, the second heating rate is 0.5-2°C / min, the temperature is raised to 170-190°C, and the temperature is kept constant for 5-20 minutes. A method for analyzing naphthalene-based compounds in a fraction using the multidimensional gas chromatography system according to claim 1.

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

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

15. 15. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 14, wherein the naphthalene-based compounds include one or more of 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.

16. 2. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 1, wherein the fraction includes at least one fraction from 160 to 400°C.

17. The method for analyzing naphthalene-based compounds in a fraction using a multidimensional gas chromatography system according to claim 16, wherein the fraction includes at least one fraction at 200 to 250°C.

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