CN104749298A - Solid phase extraction column for separating different hydrocarbon components in diesel oil and application method - Google Patents

Abstract

The invention relates to a solid phase extraction column for separating different hydrocarbon components in diesel oil. The solid phase extraction column is composed of an upper solid phase extraction column and a lower solid phase extraction column that are communicated. The stationary phase of the upper solid phase extraction column is a mixture of silica gel and aluminum oxide, wherein the content of aluminum oxide is 1-40% by mass, the stationary phase of the lower solid phase extraction column is silver ion loaded silica gel subjected to water adding treatment, and on the basis of silica gel, the silver content of the stationary phase is 1-12% by mass, and the water content is 4-15% by mass. The column can be used for separation of olefin components in diesel oil, and can solve the problems of long time and low olefin recovery rate in separation of olefin from diesel oil.

Description

A solid-phase extraction column for separating different hydrocarbon components in diesel oil and its application method

technical field

The invention relates to a solid phase extraction column for separating different types of hydrocarbon components in hydrocarbon compounds and an application method thereof, specifically, a solid phase extraction column for separating different types of hydrocarbon components in diesel oil and the application of the column to separate diesel oil methods for the different types of hydrocarbon components in the chemical and for the compositional analysis of the separated olefin components.

Background technique

Olefins are one of the products in the process of diesel processing and have a great impact on the quality of diesel. Therefore, it is of great significance to fully characterize diesel oil and understand its olefin content, type and monomer composition to optimize diesel processing scheme and control product quality.

The structure and composition of diesel oil is complex, and the molecular weights of olefins and naphthenes are exactly the same. It is impossible to obtain accurate monomer information only by instruments. This requires a pretreatment process with high separation efficiency and small cross-components to obtain different In order to eliminate the mass overlap of olefins and cycloalkanes in mass spectrometry analysis, and then conduct in-depth analysis for each component. ["Analysis of olefins in secondary processed diesel oil" [J]. Analytical Chemistry, 1996, 24 (5): 530-534] reported the use of silica gel column to pre-separate secondary processed diesel samples into non-aromatics, aromatics and Colloidal three fractions, combined with bromine addition/field ionization mass spectrometry to determine the type and content of non-aromatic hydrocarbons. This method is cumbersome to operate and takes a long time to analyze.

In recent years, solid phase extraction technology has been widely used in the pretreatment of oil products. Utilizing the principle that the double bond of olefin can cooperate with Ag ⁺ to form a complex, while saturated hydrocarbon has almost no interaction with Ag ⁺ , the saturated hydrocarbon can be separated from the olefin. Xu Yanqin et al ["Determination of carbon number distribution of olefins in diesel oil by solid phase extraction-gas chromatography-time-of-flight mass spectrometry" [J]. Acta Petroleum Sinica, 2010, 24 (3): 431-436] loaded Ag ⁺ on silica Make an Ag-SiO ₂ solid phase extraction column, use n-pentane to wash out the saturated parts in the diesel sample, and then use benzene to wash out the mixed parts of aromatic hydrocarbons and olefins. The mixed fraction obtained by pre-separation was analyzed by gas chromatography/field ionization-time-of-flight mass spectrometry (GC-FI/TOF MS) to obtain the type and carbon number distribution information of olefins. Although this method can eliminate the mass overlap of olefins and cycloalkanes in mass spectrometry analysis, the pure olefin components are still not obtained, which interferes with the identification of olefin monomer molecules. In addition, using benzene as an eluent is not good for the health of the experimenter.

Bai Xue et al. [Types and distribution of olefins in catalytically cracked diesel oil and coked diesel oil[J]. Petroleum Refining and Chemical Industry, 2011, 42 (11): 76-79] proposed a double-column solid phase extraction method to separate catalytic cracked diesel oil and coked diesel oil , the upper column is filled with silica gel, and the lower column is filled with Ag-SiO ₂ , but the recovery rate of olefins in this method is low. The traditional one-dimensional gas chromatography-mass spectrometry is used to analyze the olefin components. The phenomenon of peak overlap and coelution is serious, and the qualitative and quantitative accuracy Poor sex.

Contents of the invention

The purpose of the present invention is to provide a solid phase extraction column for separating different hydrocarbon components in diesel oil and a method for separating different hydrocarbon components in diesel oil with the column, which can solve the problems of long time-consuming separation of olefins from diesel oil and low recovery rate of olefins .

Another object of the present invention is to provide a method for separating the above-mentioned separated olefin components by comprehensive two-dimensional gas chromatography, and then analyzing the monomer composition of the olefin components by time-of-flight mass spectrometry.

The solid phase extraction column provided by the present invention for separating different hydrocarbon components in diesel oil is composed of two upper and lower solid phase extraction columns, and the stationary phase of the upper solid phase extraction column is a mixture of silica gel and alumina. The aluminum content is 1-40% by mass, and the stationary phase of the lower solid-phase extraction column is silica gel loaded with silver ions after adding water. The silver content of the stationary phase calculated on the basis of silica gel is 1-12 mass%, and the water content is 4-15% quality%.

The invention adopts double-column solid-phase extraction method to separate aromatics, saturated hydrocarbons and olefins in diesel oil. The upper layer of the solid-phase extraction column uses a mixture of silica gel and alumina as the stationary phase, and the lower layer of the extraction column uses silica gel loaded with silver ions treated with water as the stationary phase. Phase, can effectively separate the olefin components in diesel oil, improve separation efficiency and olefin recovery rate. The separated olefin components are detected by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry, which can improve the detection rate of monomers contained in the olefin components and accurately determine the content of diolefins and cycloolefins in olefins.

Description of drawings

Figure 1 is a total ion flow chromatogram of catalytic cracking diesel oil olefin components in the method of the present invention.

Fig. 2 is the proton nuclear magnetic resonance spectrogram of the saturated hydrocarbon component of catalytic cracking diesel oil in the method of the present invention.

Fig. 3 is a total ion flow chromatogram of coked diesel oil olefin components in the method of the present invention.

Fig. 4 is the hydrogen nuclear magnetic resonance spectrogram of the coked diesel oil saturated hydrocarbon component in the method of the present invention.

Fig. 5 is a comprehensive two-dimensional chromatogram of coked diesel olefin components in the method of the present invention.

Detailed ways

The stationary phase filled in the upper extraction column of the solid phase extraction column of the present invention is SiO ₂ -Al ₂ O ₃ , and the stationary phase filled in the lower extraction column is Ag-SiO ₂ treated with water. The combination of the two stationary phases can not only ensure the separation of aromatics and olefins in diesel, but also improve the recovery rate of olefins. Using the above extraction stationary phase, using an appropriate extractant to wash the upper stationary phase that adsorbs aromatics and the lower stationary phase that adsorbs olefins and saturated hydrocarbons, can effectively separate aromatics, olefins, and saturated hydrocarbons in diesel. The eluent used has low toxicity and can be used The amount is small, which is convenient for post-processing, and at the same time avoids a large loss of samples. The obtained olefin components are determined by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry, which can improve the resolution of the olefin monomer components and obtain more accurate qualitative and quantitative results of the olefin monomers.

The solid-phase extraction provided by the present invention is composed of two connected solid-phase extraction columns, preferably connected by an adapter in the middle, and the adapter is a joint connecting the two extraction columns.

The mass ratio of the stationary phase contained in the upper layer/lower layer solid phase extraction column is 0.5˜1.5:1, preferably 0.8˜1.2:1.

The silica gel used in the preparation of the stationary phase in the present invention is preferably fine-pore silica gel used for chromatographic separation. If the pore size is too small, macromolecular substances will stay in the pores, resulting in sample loss and low recovery rate. If the pore size is too large, the separation effect will be poor. The specific surface area of the silica gel is 400-750m ² /g, preferably 500-650m ² /g, the pore volume is 0.35-0.90mL/g, preferably 0.35-0.5mL/g, and the pores with a pore diameter of 20-35nm account for the pore volume 40-65% of that. The specific surface area of the alumina is 80-250m ² /g, preferably 90-200m ² /g.

The upper layer of the solid phase extraction column of the present invention, that is, the stationary phase packed in the upper column is SiO ₂ -Al ₂ O ₃ , wherein the content of alumina is preferably 3-20% by mass. The lower layer of the solid-phase extraction column, that is, the stationary phase packed in the lower column is water-treated Ag-SiO ₂ , the silver content calculated based on silica gel is preferably 1.5-8% by mass, and the water content is preferably 5-10% by mass.

The preparation method of the above-mentioned SiO ₂ -Al ₂ O ₃ stationary phase is: drying the silica gel at 100-200°C for 3-8 hours to obtain activated silica gel, and calcining the alumina at 300-500°C, preferably 350-450°C for 2-6 hours. hours to obtain activated alumina. The activated silica gel and alumina are mixed evenly according to the required ratio to obtain the SiO ₂ -Al ₂ O ₃ stationary phase.

The preparation method of Ag- _SiO2 treated with water is as follows: add the silver salt solution into the silica gel, stir it evenly and let it stand for 1-24 hours, preferably 3-10 hours, so that the silver ions are evenly adsorbed on the surface of the silica gel, and dry at 100-200°C After 1-10 hours, the Ag-SiO ₂ stationary phase is obtained. Described silver salt is preferably silver nitrate. Take an appropriate amount of Ag-SiO ₂ stationary phase, add water to mix evenly, and let it stand for 12 to 24 hours to obtain Ag-SiO ₂ treated with water.

The method for separating different hydrocarbon components in diesel oil by solid phase extraction provided by the present invention comprises wetting the stationary phase of the solid phase extraction column described in the present invention with the first eluent, adding a diesel sample from the upper layer, and using the first eluent Rinse the solid phase extraction column, wash the saturated hydrocarbons and olefins to the lower column, separate the two columns, wash the upper column with the second eluent to extract aromatics, wash the lower column with the first eluent to extract saturated hydrocarbons, and then Flush the lower column with a third eluent to extract the olefins.

In the above method, the ratio of the added diesel oil sample to the total mass of the stationary phase is 1:20-70, preferably 1:40-70.

Before adding the diesel sample, the mass ratio of the first eluent to the stationary phase used to wet the solid phase extraction column is 0.5 to 3:1, and then add the diesel sample, the components in the diesel are adsorbed by the stationary phase and elute with the first eluent The volume ratio of the first eluent to the diesel sample used to flush saturated hydrocarbons and olefins to the lower column is 30-90:1, preferably 40-80:1. The volume ratio of the second eluent to the diesel sample used for flushing the upper column to extract aromatics is 30-100:1, preferably 30-70:1, and the volume ratio of the first eluent to the diesel sample used for flushing the lower column to extract saturated hydrocarbons is 20-90:1, preferably 30-60:1, the volume ratio of the third eluent used to extract olefins from the column under flushing to the diesel sample is 60-180:1, preferably 80-160:1.

The first eluent is selected from at least one of n-pentane, n-hexane, n-heptane and petroleum ether, and the second eluent is selected from methylene chloride, chloroform, benzene, ethanol, isopropanol and acetic acid at least one of ethyl esters, and the third eluent is selected from dichloromethane or a mixture of benzene and ethanol or isopropanol.

The second eluent is preferably a mixture of methylene chloride and ethanol with a mass ratio of 6-9:1, and the third eluent is preferably a mixture of methylene chloride and ethanol with a mass ratio of 2-5:1.

In the method of the present invention, the column extraction of olefins under flushing is preferably carried out in two steps, first flushing with dichloromethane, the volume ratio of dichloromethane to diesel sample used is 60-130:1, preferably 70-120:1, and then For flushing with a dichloromethane-ethanol solution with a ratio of 2-5:1, the volume ratio of the dichloromethane-ethanol solution to the diesel sample is 20-50:1, preferably 20-40:1.

Aromatic hydrocarbons, saturated hydrocarbons and olefin solutions separated by the above method are obtained by volatilizing the solvent to obtain the components. It is preferable to volatilize the solvent with a water bath or infrared irradiation, then take a test sample and add 1 mL of dichloromethane to dissolve it, and use ¹ HNMR and GC - MS analyzes the components to determine the content of cross-components (separated components) contained in each component and judge the separation effect. Gas chromatography-mass spectrometry (GC-MS) was used to determine the content of saturated hydrocarbons in the obtained aromatic components, and the content of aromatic hydrocarbons and paraffins in the olefin components, and ¹ H NMR was used to detect whether there were olefins in the saturated hydrocarbon components.

The preferred method for measuring olefins in diesel oil of the present invention comprises separating the olefins in diesel oil with the method of the present invention, taking a diesel sample and injecting it into a comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometer, and using a comprehensive two-dimensional gas chromatography according to the boiling point and polarity of the alkene After orthogonal separation, enter the time-of-flight mass spectrometry analysis to obtain the monomer composition of the olefinic component.

The diesel oil suitable for the method of the present invention is diesel oil containing olefins, such as catalytic cracking diesel oil, coking diesel oil or visbreaking diesel oil.

The present invention will be further described in detail below by examples, but the present invention is not limited thereto.

The silica gel used in the example is fine-pore silica gel produced by Qingdao Ocean Chemical Factory Branch, with a particle size of 0.150-0.074 mm, a pore volume of 0.36 mL/g, a specific surface area of 635 m ² /g, and pores with a pore diameter of 20-35 nm accounting for 10% of the pore volume. 56%.

Alumina is neutral alumina for column chromatography, produced by Sinopharm Chemical Reagent Co., Ltd. The particle size is 0.150-0.074mm, the specific surface area is 152m ² /g, and the weight loss on ignition is ≤8.0%.

The instrument used for the analysis is a quadrupole gas chromatography-mass spectrometer, model 7890GC/5975MS, with FID detector. Gas chromatography (GC) working conditions: injection volume 1uL, splitless injection, chromatographic column is DM-5MS capillary column, injection port temperature is 300°C, column oven temperature rise program is initial temperature 60°C, keep for 2min, and then The heating rate was increased to 300°C at a rate of 5°C/min and maintained for 6 minutes. Mass spectrometry (MS) working conditions: EI ionization mode, bombardment voltage 70eV, scanning range, ion source temperature 220°C.

The comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometer used, the model is Pegasus4D, the data is processed by LECOChroma TOF software, and the acquisition frequency is 100Hz.

Example 1

The silica gel stationary phase and silica gel-alumina stationary phase loaded with silver ions described in the present invention are prepared.

Dry fine-pore silica gel at 150°C for 5 hours to obtain activated silica gel (SG), which is stored in a desiccator for later use. Activated alumina (SAL) was obtained by calcining neutral alumina at 400°C for 4 hours. Weigh SG and SAL in proportion, mix them evenly, and prepare a certain mass fraction of silica gel-alumina stationary phase. Put in a desiccator for later use.

Take 3g of silver nitrate and dissolve it in 50g of water to make a solution, take 50g of silica gel, add the silica gel to the silver nitrate solution while stirring, after stirring evenly, let it stand for 5 hours, and dry at 150°C for 5 hours to obtain a silver solution with a silver content of 3.8% by mass. Ag- _SiO2 stationary phase (ASG). Take out a part and accurately weigh the mass, add a certain weight of distilled water, oscillate and shake well, and obtain the Ag-SiO ₂ stationary phase that has been treated with water.

Example 2

The aromatic hydrocarbons, olefins and saturated hydrocarbons in the catalytic cracking diesel oil are separated by the solid phase extraction method of the present invention.

The upper column of the solid phase extraction column was filled with 1.5 g of silica gel-alumina stationary phase with an alumina content of 15% by mass, and the lower column was filled with 1.5 g of Ag-SiO ₂ stationary phase (ASG-1) containing 8% by mass of water. Moisten with 1.5 mL of n-pentane, respectively.

Take 60 μL of catalytically cracked diesel oil with a distillation range of 180-350°C and add it to the column. Use 3 mL of n-pentane to wash the saturated hydrocarbon and olefin components to the lower column, and then separate the two columns. The upper column was washed with 4 mL of dichloromethane-ethanol solution with a volume ratio of 5:1 to obtain an aromatic hydrocarbon solution. The lower column was washed with 2 mL of n-pentane to obtain a saturated hydrocarbon solution, and then successively washed with 7 mL of dichloromethane and 2 mL of dichloromethane-ethanol solution with a volume ratio of 9:1 to obtain an olefin solution.

The solvent in the saturated hydrocarbon, olefin and aromatic components is evaporated by heating in a water bath. Using GC/MS analysis, the total ion current chromatogram of the olefin component is shown in Figure 1. The content of aromatics in the olefin component is 2.2% by mass, the content of paraffins is 1.33% by mass, and the content of saturated hydrocarbons in the aromatic component is 1.3% by mass. It shows that the content of the separated cross components in the separated main components is all lower than 5% by mass, which is within the allowable range of error.

The hydrogen nuclear magnetic resonance spectrum of the obtained saturated hydrocarbon components is shown in Figure 2, and there is no characteristic peak of olefins at the chemical shift 4-6, indicating that the saturated hydrocarbons basically do not contain olefins.

The recovery of olefins in the diesel fraction was determined by the spiked recovery of n-hexadecene. Take two identical diesel oil samples, one of which is added with a certain amount of n-hexadecene as a standard substance, and the two samples are separated by solid phase extraction according to the above method. The content of n-hexadecene was obtained by analysis. The ratio of the n-hexadecene content of the spiked part minus the n-hexadecene content of the unmarked part, and the theoretical value of the added n-hexadecene standard sample is the olefin recovery rate, and its value is 97.42 quality%.

The above results show that the method of the present invention has a small cross component (separated component) content in the separated components, a high recovery rate of olefins, and a good separation effect.

Example 3

In the upper column of the solid phase extraction column, the silica gel-alumina stationary phase with 1.5g alumina content of 15% by mass is packed, and the Ag-SiO stationary phase (ASG- ₂ ), respectively wetted with 1.5 mL of n-pentane.

Take 60 μL of catalytically cracked diesel oil with a distillation range of 180-350°C and add it to the column. Use 3 mL of n-pentane to wash the saturated hydrocarbon and olefin components to the lower column, and then separate the two columns. The upper column was washed with 4 mL of dichloromethane-ethanol solution with a volume ratio of 5:1 to obtain an aromatic hydrocarbon solution. The lower column was washed with 2 mL of n-pentane to obtain a saturated hydrocarbon solution, and then successively washed with 7 mL of dichloromethane and 2 mL of dichloromethane-ethanol solution with a volume ratio of 9:1 to obtain an olefin solution.

The solvent in the saturated hydrocarbon, olefin and aromatic components is evaporated by heating in a water bath. According to GC/MS analysis, the content of aromatics in the olefin component was 2.5% by mass, the content of paraffins was 3.83% by mass, the content of saturated hydrocarbon in the aromatic component was 0.8% by mass, and the content of cross components was all lower than 5% by mass.

The hydrogen nuclear magnetic resonance spectrum of the saturated hydrocarbon components shows that there is no characteristic peak of olefins at chemical shifts 4-6, indicating that the saturated hydrocarbons basically do not contain olefins.

The recovery rate of olefins measured by the standard addition recovery rate of n-hexadecene was 95.17% by mass.

Example 4

In the upper column of the solid phase extraction column, the silica gel-alumina stationary phase with a 1.5g alumina content of 15% by mass is packed, and the Ag-SiO _stationary phase (ASG-3 ), respectively wetted with 1.5 mL of n-pentane.

Take 60 μL of catalytically cracked diesel oil with a distillation range of 180-350°C and add it to the column. Use 3 mL of n-pentane to wash the saturated hydrocarbon and olefin components to the lower column, and then separate the two columns. The upper column was washed with 4 mL of dichloromethane-ethanol solution with a volume ratio of 5:1 to obtain an aromatic hydrocarbon solution. The lower column was washed with 2 mL of n-pentane to obtain a saturated hydrocarbon solution, and then successively washed with 7 mL of dichloromethane and 2 mL of dichloromethane-ethanol solution with a volume ratio of 9:1 to obtain an olefin solution.

The solvent in the saturated hydrocarbon, olefin and aromatic components is evaporated by heating in a water bath. According to GC/MS analysis, the content of aromatics in the olefin component was 1.7% by mass, the content of paraffins was 1.26% by mass, the content of saturated hydrocarbons in the aromatic component was 2.1% by mass, and the content of cross components were all lower than 5% by mass.

The hydrogen nuclear magnetic resonance spectrum of the saturated hydrocarbon components shows that there is no characteristic peak of olefins at chemical shifts 4-6, indicating that the saturated hydrocarbons basically do not contain olefins.

The recovery rate of olefins measured by the standard addition recovery rate of n-hexadecene was 96.53% by mass.

Example 5

In the upper column of the solid phase extraction column, the silica gel-alumina stationary phase with a 1.5g alumina content of 5% by mass is packed, and the Ag- _SiO stationary phase (ASG-1 ), wet with 1.5 mL of n-pentane, respectively.

Take 60 μL of catalytically cracked diesel oil with a distillation range of 180-350°C and add it to the column. Use 3 mL of n-pentane to wash the saturated hydrocarbon and olefin components to the lower column, and then separate the two columns. The upper column was washed with 4 mL of dichloromethane-ethanol solution with a volume ratio of 5:1 to obtain an aromatic hydrocarbon solution. The lower column was washed with 2 mL of n-pentane to obtain a saturated hydrocarbon solution, and then successively washed with 7 mL of dichloromethane and 2 mL of dichloromethane-ethanol solution with a volume ratio of 9:1 to obtain an olefin solution.

The solvent in the saturated hydrocarbon, olefin and aromatic components is evaporated by heating in a water bath. Using GC/MS analysis, the content of aromatics in the olefin component was 4.7% by mass, the content of paraffins was 2.22% by mass, the content of saturated hydrocarbons in the aromatic component was 1.1% by mass, and the content of cross components were all lower than 5% by mass.

The hydrogen nuclear magnetic resonance spectrum of the saturated hydrocarbon components shows that there is no characteristic peak of olefins at chemical shifts 4-6, indicating that the saturated hydrocarbons basically do not contain olefins.

The recovery rate of olefins determined by the standard addition recovery rate of n-hexadecene was 96.89% by mass.

Example 6

In the upper column of solid phase extraction, 1.5 g of silica gel-alumina stationary phase with an alumina content of 30 mass % was loaded, and in the lower column, 1.5 g of Ag-SiO stationary phase (ASG- ₁ ) with a water content of 8 mass % was filled, Moisten with 1.5 mL of n-pentane respectively.

Take 60 μL of catalytically cracked diesel oil with a distillation range of 180-350°C and add it to the column. Use 3 mL of n-pentane to wash the saturated hydrocarbon and olefin components to the lower column, and then separate the two columns. The upper column was washed with 4 mL of dichloromethane-ethanol solution with a volume ratio of 5:1 to obtain an aromatic hydrocarbon solution. The lower column was washed with 2 mL of n-pentane to obtain a saturated hydrocarbon solution, and then successively washed with 7 mL of dichloromethane and 2 mL of dichloromethane-ethanol solution with a volume ratio of 9:1 to obtain olefin components.

The solvent in the saturated hydrocarbon, olefin and aromatic components is evaporated by heating in a water bath. According to GC/MS analysis, the content of aromatics in the olefin component was 0.9% by mass, the content of paraffins was 2.22% by mass, the content of saturated hydrocarbons in the aromatic component was 3.8% by mass, and the content of cross components were all lower than 5% by mass.

The hydrogen nuclear magnetic resonance spectrum of the saturated hydrocarbon components shows that there is no characteristic peak of olefins at chemical shifts 4-6, indicating that the saturated hydrocarbons basically do not contain olefins.

The recovery rate of olefins measured by the standard addition recovery rate of n-hexadecene was 95.07% by mass.

Example 7

This example uses the solid phase extraction method of the present invention to separate aromatics, olefins and saturated hydrocarbons in coked diesel oil.

In the upper column of the solid phase extraction column, the silica gel-alumina stationary phase with a 1.5g alumina content of 15% by mass is packed, and the Ag-SiO stationary _phase (ASG-1 ), wet with 1.5 mL of n-pentane, respectively.

Take 50 μL of coked diesel oil with a distillation range of 180-350°C and add it to the column. Use 4 mL of n-pentane to wash the saturated hydrocarbon and olefin components to the lower column, and then separate the two columns. The upper column was washed with 3 mL of dichloromethane-ethanol solution with a volume ratio of 5:1 to obtain an aromatic hydrocarbon solution. The lower column was washed with 3 mL of n-pentane to obtain a saturated hydrocarbon solution, and then successively washed with 6 mL of dichloromethane and 2 mL of dichloromethane-ethanol solution with a volume ratio of 9:1 to obtain olefin components.

The solvent in the saturated hydrocarbon, olefin and aromatic components is evaporated by heating in a water bath. Using GC/MS analysis, the total ion current chromatogram of the olefin components is shown in Figure 3. The content of aromatics in the olefin component is 3.1% by mass, the content of paraffins is 1.22% by mass, the content of saturated hydrocarbons in the aromatic component is 1.8% by mass, and the content of cross components is all less than 5% by mass.

The hydrogen nuclear magnetic resonance spectrum of the saturated hydrocarbon components is shown in Figure 4, which shows that there are no characteristic peaks of olefins at chemical shifts 4-6, indicating that the saturated hydrocarbons basically do not contain olefins.

The recovery rate of olefins determined by the standard addition recovery rate of n-hexadecene was 96.82% by mass.

Comparative example 1

Separation of diesel components was performed with Ag- _SiO2 stationary phase without water treatment.

Separation of aromatics, olefins and saturated hydrocarbons in diesel oil by the method of Example 2, except that the stationary phase in the lower column is 1.5g Ag-SiO ₂ stationary phase (ASG) without adding water. Using GC/MS analysis, the content of aromatics in the saturated hydrocarbon component is 0%, the content of aromatics in the olefin component is 2.7 mass%, and the content of saturated hydrocarbons in the aromatics is 1.9 mass%, all lower than 5 mass%, within the error tolerance range However, the recovery rate of olefins measured by the spiked recovery rate of n-hexadecene was 83.64% by mass, indicating that some olefins combined with the stationary phase were not eluted, and the loss of olefins was relatively large.

Comparative example 2

The upper column is silica gel stationary phase and the lower column is Ag-SiO ₂ stationary phase without water treatment to separate the components in diesel oil.

Separation of aromatics, olefins and saturated hydrocarbons in diesel oil according to the method of Example 2, the difference is that the stationary phase in the upper column is 1.5g of silica gel (SG), and the stationary _phase in the lower column is 1.5g of Ag-SiO without adding water stationary phase (ASG). Using GC/MS analysis, the aromatic hydrocarbon content in the saturated hydrocarbon component is 2.8% by mass, the aromatic hydrocarbon content in the olefin component is 6.7% by mass, and the saturated hydrocarbon content in the aromatic hydrocarbon is 2.2% by mass. The recovery rate of olefins was 84.71% by mass. The results showed that some aromatics could not be effectively adsorbed by the silica gel stationary phase in the upper column, and were easily eluted together with saturated hydrocarbon components by low-polarity solvents, resulting in serious crossover between components. In addition, some olefins are combined with the stationary phase and are not eluted, and the loss of olefins is relatively large.

Example 8

This example is used to illustrate the analysis of olefin components by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry.

Adopt the olefin component that example 7 is separated to obtain, carry out comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry analysis to it, the comprehensive two-dimensional chromatogram that obtains is shown in Fig. 5, and each point represents a kind of olefin monomer in Fig. 5, records The type distribution of monomer olefins with different carbon numbers is shown in Table 1.

The above analysis results show that through two-dimensional chromatographic column separation, more than 1,000 olefin component peaks are identified, which is an order of magnitude higher than the more than 100 peaks obtained by GC/MS in Example 7, and the co-elution phenomenon is significantly reduced, which can be analyzed The qualitative and quantitative accuracy of cyclic olefins, diolefins and olefin monomers has been significantly improved.

Table 1

Claims (10)

1. the solid-phase extraction column of different hydrocarbon component in a Solid phase extraction separation diesel oil, be made up of upper and lower two solid-phase extraction columns communicated, the Stationary liquid of upper strata solid-phase extraction column is the potpourri of silica gel and aluminium oxide, wherein alumina content is 1 ~ 40 quality %, the Stationary liquid of lower floor's solid-phase extraction column is the silica gel of the load silver ion adding water treatment, Stationary liquid take silica gel as the silver content of benchmark is 1 ~ 12 quality %, and liquid water content is 4 ~ 15 quality %.

2., according to solid-phase extraction column according to claim 1, it is characterized in that the mass ratio of Stationary liquid contained by described upper strata/lower floor's solid-phase extraction column is 0.5 ~ 1.5:1.

3., according to solid-phase extraction column according to claim 1, it is characterized in that the specific surface area of described silica gel is 400 ~ 750m ²/ g, pore volume is 0.35 ~ 0.90mL/g, and the specific surface area of described aluminium oxide is 80 ~ 250m ²/ g.

4. the method for different hydrocarbon component in a Solid phase extraction separation diesel oil, comprise and soak solid-phase extraction column Stationary liquid according to claim 1 with the first eluant, eluent, diesel samples is added from upper strata, solid-phase extraction column is rinsed with the first eluant, eluent, after stable hydrocarbon and alkene are flushed to lower prop, separately twin columns, rinse upper prop with the second eluant, eluent and extract aromatic hydrocarbons, rinse lower prop with the first eluant, eluent and first extract stable hydrocarbon, then extract alkene with the 3rd eluant, eluent flushing lower prop; The first described eluant, eluent is selected from least one in n-pentane, normal hexane, normal heptane and sherwood oil, second eluant, eluent is selected from least one in methylene chloride, chloroform, benzene, ethanol, isopropyl alcohol and ethyl acetate, and the 3rd eluant, eluent is selected from the potpourri of methylene chloride or benzene and ethanol or isopropyl alcohol.

5. in accordance with the method for claim 4, it is characterized in that the ratio of diesel samples and Stationary liquid gross mass is 1:20 ~ 70.

6. in accordance with the method for claim 4, after it is characterized in that adding diesel samples, the mass ratio of wetting solid-phase extraction column the first eluant, eluent used and Stationary liquid is 0.5 ~ 3:1, volume ratio stable hydrocarbon and alkene being flushed to lower prop the first eluant, eluent used and diesel samples is 30 ~ 90:1, in flushing, the volume ratio of column extracting aromatic hydrocarbons the second eluant, eluent used and diesel samples is 30 ~ 100:1, the volume ratio of rinsing lower column extracting stable hydrocarbon the first eluant, eluent used and diesel samples is 20 ~ 90:1, the volume ratio of rinsing lower column extracting alkene the 3rd eluant, eluent used and diesel samples is 60 ~ 180:1.

7. in accordance with the method for claim 4, it is characterized in that the second described eluant, eluent be methylene chloride and ethanol mass ratio is the mixed liquor of 6 ~ 9:1, the 3rd eluant, eluent is methylene chloride and ethanol mass ratio is the mixed liquor of 2 ~ 5:1.

8. in accordance with the method for claim 6, it is characterized in that rinsing lower column extracting alkene carries out in two steps, first use dichloromethane rinse, the volume ratio of methylene chloride used and diesel samples is 60 ~ 130:1, rinse with the dichloromethane-ethanol solution that mass ratio is 2 ~ 5:1, the volume ratio of dichloromethane-ethanol solution used and diesel samples is 20 ~ 50:1 again.

9. in accordance with the method for claim 4, it is characterized in that described diesel oil is catalytic cracking diesel oil, coker gas oil or viscosity breaking diesel oil.

10. one kind measures the method for alkene in diesel oil, comprise by the olefin component in the method separation diesel oil of claim 4, get diesel samples and inject comprehensive two dimensional gas chromatography-time of-flight mass spectrometer, after carrying out orthogonal separation with comprehensive two dimensional gas chromatography according to the boiling point of alkene and polarity difference, enter flight time mass spectrum analysis, obtain the monomer composition of olefin component.