Method for analyzing olefin compounds based on epoxy three-membered ring reaction

Abstract

The invention relates to the technical field of crude oil component analysis, in particular to a method for analyzing olefin compounds based on epoxy three-membered ring reaction, which comprises the following steps: mixing an olefin-containing substance to be detected with a reaction reagent for derivatization reaction, the reaction reagent being metachloroperbenzoic acid; and carrying out mass spectrometry on the product of the derivatization reaction to obtain a mass spectrum, and deducing the number of double bonds of the olefin compound in the to-be-detected substance through the mass spectrum. The method can be used for high-sensitivity detection of olefin in complex matrixes such as petroleum product oil and the like, olefin molecules containing six double bonds can be identified, and identification of fine structures of the double bonds can be carried out on various types of olefin compounds. In the detection process, a catalyst and photocatalysis do not need to be additionally added, a good result can be generated only through one oxidizing reagent, a good detection effect can be achieved only through 5 minutes of reaction, detection is rapid and efficient, operation is easy, and selectivity is high.

Description

Technical Field

[0001] The present invention relates to the technical field of crude oil component analysis, and in particular to a method for analyzing olefin compounds based on epoxy three-membered ring reaction. Background Art

[0002] Olefins are important raw materials for modern organic chemical industry and key components of petroleum products. Their molecular and structural composition determines the properties of these products. Different carbon numbers, double bond positions, and linear / cyclic olefins all influence the anti-knock properties, stability, and overall stability of these products. Therefore, exploring the molecular and structural composition of olefins is crucial for process optimization, product quality improvement, and mechanism analysis in the petroleum refining industry.

[0003] In the characterization and analysis of petroleum product oils, there are problems such as high complexity of compound types and a large number of olefin types. There is a certain gap in the research on the structural composition of olefin compounds.

[0004] Traditional gas chromatography-mass spectrometry (GC-MS) is capable of detecting olefin compounds and identifying double bond positions, but is limited by carbon number and injection vaporization temperature, resulting in significant deficiencies in the range of olefin detection. In terms of double bond position detection, without derivatization (such as ozone decomposition), gas chromatography (GC) can only resolve terminal double bonds in the carbon chain and cannot detect all double bond positions. Existing derivatization methods have problems such as long derivatization times and susceptibility to interference from complex matrices. Therefore, high-sensitivity detection of olefins and identification of fine double bond structures pose challenges. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for analyzing olefin compounds based on epoxy three-membered ring reaction, which improves the ionization efficiency of olefins and further expands the analyzable range of olefins in petroleum omics.

[0006] The present invention provides a method for analyzing olefin compounds based on epoxy three-membered ring reaction, comprising the following steps:

[0007] The alkene-containing analyte is mixed with a reaction reagent to perform a derivatization reaction, wherein the reaction reagent is m-chloroperbenzoic acid;

[0008] The product of the derivatization reaction is subjected to mass spectrometry analysis to obtain a mass spectrum, and the number of double bonds of the olefin compound in the analyte is deduced from the mass spectrum.

[0009] Optionally, the alkene-containing analyte includes one or more alkene;

[0010] The olefin has 8 to 30 carbon atoms.

[0011] Optionally, the olefin-containing analyte is a petroleum product oil, an olefin-containing mixture or a pure olefin sample;

[0012] The petroleum product oil includes crude oil and / or secondary processed products of crude oil.

[0013] Optionally, the temperature of the derivatization reaction is 20-25° C., and the time of the derivatization reaction is 5-15 minutes.

[0014] Optionally, the alkene-containing analyte is obtained by the following method:

[0015] The components of petroleum oil products are separated to obtain saturates, aromatics, colloids and asphaltenes, among which olefins are retained in the saturates. The separated saturates are selected as the sample to be tested.

[0016] Optionally, during the mass spectrometry analysis, the product of the derivatization reaction dissociates.

[0017] Optionally, the parameters of the mass spectrometry analysis are:

[0018] The sample flow rate is 10-20 μL / min, the nebulizer gas flow rate is 10-20 Arb, the auxiliary gas flow rate is 5 Arb, the backflush gas flow rate is 0.1-1 Arb, the vaporization temperature is 200-300°C, the positive ion discharge current is 5 μA, and the negative ion discharge current is 5 μA; the ion transfer tube temperature is 200-300°C, the mass collection range is 100-800 Da, the collection time is 0.5-1 min, the RF lens voltage is 60%, the automatic gain control is 5.0e4, the isolation window is 0.1 Da, and the CID collision energy is between 5% and 35%.

[0019] Optionally, the mass spectrometry analysis is performed by low-resolution mass spectrometry, high-resolution mass spectrometry or ultra-high-resolution mass spectrometry.

[0020] Optionally, the ionization mode of the mass spectrometry analysis is electrospray ionization or atmospheric pressure chemical ionization.

[0021] Optionally, the ionization solvent for the mass spectrometry analysis is one or more of toluene, methanol, n-heptane, n-hexane, and isooctane.

[0022] Compared with the prior art, the analytical method for olefin compounds provided by the present invention uses meta-chloroperbenzoic acid as a derivatization reagent, developing for the first time a novel method for characterizing the molecular composition of all olefin components by combining an epoxidation reaction with ultrahigh-resolution spectroscopy (UHRMS). This method can achieve good detection under both APCI and ESI sources. This method can be used for high-sensitivity detection of olefins in complex matrices such as petroleum product oils, identifying olefin molecules containing six double bonds and enabling the identification of the fine double bond structure of various olefin compounds. The detection process does not require the addition of additional catalysts or photocatalysis; only a single oxidizing reagent is required to produce good results. The reaction takes only 5 minutes to achieve good detection results, resulting in rapid and efficient detection, simple operation, and high selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the mass spectrum of squalene detected in Example 1;

[0024] Figure 2 This is the DBE diagram of coal tar before and after reaction in Example 2. DETAILED DESCRIPTION

[0025] The present invention provides a method for analyzing olefin compounds based on epoxy three-membered ring reaction, comprising the following steps:

[0026] The alkene-containing analyte is mixed with a reaction reagent to perform a derivatization reaction, wherein the reaction reagent is m-chloroperbenzoic acid;

[0027] The product of the derivatization reaction is subjected to mass spectrometry analysis to obtain a mass spectrum, and the olefin compound in the analyte is detected through the mass spectrum, and the number of double bonds in the olefin compound is obtained.

[0028] The present invention uses meta-chloroperbenzoic acid as an epoxidation reagent to react with an olefin compound, and derivatizes the carbon-carbon double bond of the olefin into a compound containing an oxygen-hetero-tricyclic ring through a chemical derivatization reaction. Meta-chloroperbenzoic acid is used as an epoxidation reagent, which greatly enhances the detection sensitivity of the olefin molecule and the diagnostic ion. The generated oxygen-hetero-tricyclic ring can be dissociated under atmospheric pressure chemical ionization ultra-high resolution mass spectrometry (APCI UHRMS) conditions, thereby improving the ionization efficiency of the olefin, and can be used for subsequent mass spectrometry detection, thereby achieving highly sensitive characterization of olefin molecules in complex systems, significantly enhancing the accuracy of olefin detection, and greatly expanding the analyzable range of olefins in petroleum omics, without being restricted by boiling point and interference from complex matrices. The detection method is fast and efficient, highly selective, and has low sample consumption. It does not require additional instrument modifications and is easily implemented on unmodified commercial mass spectrometers.

[0029] The chemical reaction equations for the above derivatization reaction and dissociation are shown below:

[0030]

[0031] Wherein, R1, R2, R3, and R4 are groups other than double bonds in the olefin compound, and are independently selected from H, substituted or unsubstituted C1-C28 straight-chain or branched hydrocarbon groups.

[0032] The substitution may be one or more of halogen, C1-C10 alkoxy, hydroxyl and the like.

[0033] The hydrocarbon group includes but is not limited to alkyl, alkenyl, alkynyl and the like.

[0034] The number of carbon atoms in the hydrocarbon group is preferably 6 to 30, more preferably 8 to 15, and specifically can be 8, 9, 10, 11, 12, 13, 14 or 15.

[0035] The olefin may contain one or more double bonds, including but not limited to 2, 3, 4, 5, 6, 7, 8, 9 or 10. The double bond may be located at the α position, or at positions other than the α position, such as the 2-, 3-, or 4-positions.

[0036] In addition to m-chloroperbenzoic acid, the oxidizing agent used in the epoxidation reaction of the present invention can also be other oxidizing agents that can be used to form oxygen-three-membered rings.

[0037] In the present invention, the alkene-containing analyte may include one alkene or a mixture of multiple different alkene species.

[0038] Furthermore, the olefin-containing analyte may also include other hydrocarbons or aromatic compounds to form a mixture, including but not limited to other paraffinic compounds, cycloparaffinic compounds, olefinic compounds, and aromatic compounds such as aromatic ketones and aromatic ethers. Since the reaction reagent m-chloroperbenzoic acid does not react with other hydrocarbons or aromatic compounds, the presence of other hydrocarbons or aromatic compounds will not affect the detection of olefin compounds.

[0039] The olefin preferably has 8 to 30 carbon atoms.

[0040] The olefins include, but are not limited to, monoolefins with a C=C double bond at the α position, monoolefins with a C=C double bond at other positions, or polyolefins containing multiple C=C double bonds.

[0041] Preferably, the olefin-containing mixture is a petroleum product oil, an olefin-containing mixture or a pure olefin sample.

[0042] In some specific embodiments of the present invention, the olefin-containing mixture is a petroleum product oil, an olefin polymer, or a pure olefin sample.

[0043] The petroleum product oil includes crude oil and / or secondary processed products of crude oil.

[0044] Preferably, in the present invention, the oil product to be tested is pretreated before the derivatization reaction to separate the olefins in the oil product.

[0045] Optionally, the alkene-containing analyte is obtained by the following method:

[0046] The components of petroleum oil products are separated to obtain saturates, aromatics, colloids and asphaltenes, among which olefins are retained in the saturates. The separated saturates are selected as the sample to be tested.

[0047] In some specific embodiments, the components of a petroleum product are separated using the Petroleum and Natural Gas Industry Standard SY / T5119-2008 of the People's Republic of China (Analysis of Soluble Organic Matter in Rocks and Crude Oil Group Components) to separate saturates, aromatics, resins, and asphaltenes, with olefins retained in the saturates. The separated saturates are selected as the sample to be tested.

[0048] In some embodiments, the reaction reagent m-chloroperbenzoic acid is added to the reaction system in the form of a solution, wherein the solvent of the solution is preferably dichloromethane.

[0049] The concentration of the m-chloroperbenzoic acid solution is preferably 0.5-2 mg / mL, specifically 0.5, 1, 1.5, 2 mg / mL, or a range value with any of the above values ​​as the upper limit or lower limit.

[0050] Optionally, the temperature of the derivatization reaction is 20-25° C., specifically 20, 21, 22, 23, 24 or 25° C., or a range value with any of the above values ​​as the upper or lower limit.

[0051] Optionally, the derivatization reaction time is 5 to 15 minutes, specifically 5, 10 or 15 minutes, or a range value with any of the above values ​​as the upper or lower limit, and most preferably 5 minutes.

[0052] Optionally, after the reaction is completed, the reaction system is washed with acetonitrile to quench the reaction and remove m-chlorobenzoic acid, and the reaction system is purged with nitrogen to remove residual reagents. The epoxidation reaction product is dissolved in an ionizing solvent for dissociation.

[0053] Optionally, during the mass spectrometry analysis, the product of the derivatization reaction dissociates. The present invention can detect olefins directly by mass spectrometry through the derivatization reaction, thereby improving the sensitivity of olefin detection.

[0054] Optionally, the dissociation is collision-induced dissociation or high-energy collision dissociation.

[0055] Optionally, the parameters of the mass spectrometry analysis are:

[0056] The sample flow rate is 10-20 μL / min, the nebulizer gas flow rate is 10-20 Arb, the auxiliary gas flow rate is 5 Arb, the backflush gas flow rate is 0.1 Arb, the vaporization temperature is 200-300°C, the positive ion discharge current is 5 μA, and the negative ion discharge current is 5 μA; the ion transfer tube temperature is 200-300°C, the mass collection range is 100-800 Da, the collection time is 0.5-1 min, the RF lens voltage is 60%, the automatic gain control is 5.0e4, the isolation window is 0.1 Da, and the CID collision energy is between 5% and 35%.

[0057] Optionally, the parameters of the mass spectrometry analysis are:

[0058] The sample flow rate was 20 μL / min, the nebulizer gas flow rate was 20 Arb, the auxiliary gas flow rate was 5 Arb, the backflush gas flow rate was 0.1 Arb, the vaporization temperature was 300°C, the positive ion discharge current was 5 μA, and the negative ion discharge current was 5 μA; the ion transfer tube temperature was 300°C, the mass collection range was 100-800 Da, the collection time was 0.5 min, the RF lens voltage was 60%, the automatic gain control was 5.0e4, the isolation window was 0.1 Da, and the CID collision energy was between 5% and 35%.

[0059] Optionally, the mass spectrometry analysis is performed by low-resolution mass spectrometry, high-resolution mass spectrometry or ultra-high-resolution mass spectrometry.

[0060] Optionally, the ionization mode of the mass spectrometry analysis is a mass spectrometry ionization mode such as electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI).

[0061] Optionally, the ionization solvent for the mass spectrometry analysis is one or more ionization solvents suitable for ESI or APCI, such as toluene, methanol, n-heptane, n-hexane, isooctane, etc., and isooctane is most preferred under APCI ionization conditions.

[0062] The reaction reagent (meta-chloroperbenzoic acid), reaction time, and ionization solvent of the reaction product used in the present invention are all optimized conditions.

[0063] In some embodiments, a mass spectrometric analysis is first performed on an olefin-containing analyte to obtain a DBE versus carbon number distribution profile for CH, O1, and O2 compounds before the epoxidation reaction. An epoxidation reaction is then performed, followed by mass spectrometric analysis to obtain a DBE versus carbon number distribution profile for CH, O1, and O2 compounds after the epoxidation reaction.

[0064] The two mass spectra were analyzed and compared to obtain the analysis results of the olefin compounds in the mixture.

[0065] In the present invention, the analysis results include but are not limited to: confirmation of the number of carbon atoms in the olefin compound, confirmation of the number of double bonds in the olefin compound, etc.

[0066] To further illustrate the present invention, the following is a detailed description of the embodiments. However, it should be understood that these descriptions are only for the purpose of further illustrating the features and advantages of the present invention, rather than for limiting the scope of the invention.

[0067] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0068] Example 1

[0069] (1) Test samples

[0070] Squalene was used as a model compound.

[0071] Weigh 10 mg of m-chloroperbenzoic acid (mCBPA) and add it to 1 mL of dichloromethane (DCM) to make a 10 mg / mL solution, and dilute to 1 mg / mL.

[0072] (2) Epoxidation reaction

[0073] The model olefin compound was dissolved in 100 μL of DCM and mixed with mCPBA (1 molar equivalent of C=C bond). The reaction was allowed to proceed at room temperature for 10 min. The reaction system was then washed with acetonitrile to quench the reaction and remove m-chlorobenzoic acid. The reaction was purged with nitrogen to remove any residual reagents.

[0074] (3) APCI-Orbitrap mass spectrometry analysis

[0075] The epoxidation product was dissolved in 1 ml of isooctane and analyzed by APCI-Orbitrap mass spectrometry.

[0076] The parameters are as follows:

[0077] When using the APCI ionization source, the parameters were set as follows: both positive and negative modes were applicable, with a sample flow rate of 20 μL / min, a nebulizer gas flow rate of 15 Arb, an auxiliary gas flow rate of 5 Arb, a backflush gas flow rate of 0.1 Arb, a vaporization temperature of 300°C, a positive ion discharge current of 5 μA, and a negative ion discharge current of 5 μA. The ion transfer tube temperature was 300°C, the mass acquisition range was 100–800 Da, the acquisition time was 0.5 min, and the RF lens voltage was 60%.

[0078] Experimental results analysis:

[0079] The experimental results are as follows Figure 1 shown. Figure 1 This is the mass spectrum of squalene. Figure 1 The peaks at 427.3817, 443.3764, 459.3709, 475.3654, 491.3599, and 507.3545 are [C 30 H 50 +O+H] + 、[C 30 H 50 +2O+H] + 、[C 30 H 50 +3O+H] + 、[C 30 H 50 +4O+H] + 、[C 30 H 50 +5O+H] + 、[C 30 H 50 +6O+H] + The peak of squalene can be enhanced.

[0080] Example 2

[0081] (1) Sample pretreatment

[0082] Different oil samples were separated into four components using the method and steps of the Petroleum and Natural Gas Industry Standard SY / T 5119-2008 of the People's Republic of China (Analysis of Soluble Organic Matter in Rocks and Crude Oil Group Components), separating saturates, aromatics, resins and asphaltenes, among which olefins were retained in the saturates.

[0083] Weigh 10 mg of m-chloroperbenzoic acid (mCBPA) and add it to 1 mL of dichloromethane (DCM) to make a 10 mg / mL solution, and dilute to 1 mg / mL.

[0084] (2) Epoxidation reaction

[0085] The saturated fraction obtained above was mixed with mCPBA (0.5 mg). The reaction was allowed to react at room temperature for 10 min. The reaction system was washed with acetonitrile to quench the reaction and remove m-chlorobenzoic acid. The reaction was purged with nitrogen to remove residual reagents.

[0086] (3) APCI-Orbitrap mass spectrometry analysis

[0087] The epoxidation product was dissolved in 1 ml of isooctane and analyzed by APCI-Orbitrap mass spectrometry.

[0088] The parameters are as follows:

[0089] When using the APCI ionization source, the parameters were set as follows: both positive and negative modes were applicable, with a sample flow rate of 20 μL / min, a nebulizer gas flow rate of 15 Arb, an auxiliary gas flow rate of 5 Arb, a backflush gas flow rate of 0.1 Arb, a vaporization temperature of 300°C, a positive ion discharge current of 5 μA, and a negative ion discharge current of 5 μA. The ion transfer tube temperature was 300°C, the mass acquisition range was 100–800 Da, the acquisition time was 0.5 min, and the RF lens voltage was 60%.

[0090] Experimental results analysis:

[0091] The experimental results are as follows Figure 2 shown.

[0092] The epoxidation results of actual oil samples show CH compounds and oxygenates before and after the catalytic cracking slurry reaction. The figure shows a decrease in CH compounds and fewer oxygenates before the reaction. Compounds with carbon numbers between 10 and 30 and DBEs between 1 and 3 are essentially absent from the CH compounds before the reaction. However, compounds with carbon numbers between 10 and 30 and DBEs between 1 and 3 are detected in the O1 compounds after the reaction. These are linear olefins, primarily with carbon numbers between 10 and 30 and DBEs between 4 and 10. O1 compounds are detected both before and after the reaction, and are cyclic or biphenyl cyclic olefins. O2 compounds are primarily detected after the reaction, with carbon numbers between 13 and 25 and DBEs between 2 and 7. These are likely linear olefins containing two double bonds or biphenyl cyclic olefins. This demonstrates that this method can improve the sensitivity of olefin detection in petroleum. The results of the model compound analysis demonstrate its significant advantage for olefins with multiple double bonds.

[0093] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for analyzing olefin compounds based on epoxy three-membered ring reaction, comprising the following steps: The alkene-containing analyte is mixed with a reaction reagent to perform a derivatization reaction, wherein the reaction reagent is m-chloroperbenzoic acid; The product of the derivatization reaction is subjected to mass spectrometry analysis to obtain a mass spectrum, and the number of double bonds of the olefin compound in the analyte is deduced from the mass spectrum.

2. The method according to claim 1, characterized in that The alkene-containing analyte includes one or more alkene; The olefin has 8 to 30 carbon atoms.

3. The method according to claim 2, characterized in that The olefin-containing analyte is a petroleum product oil, an olefin-containing mixture or a pure olefin sample; The petroleum product oil includes crude oil and / or secondary processed products of crude oil.

4. The method according to claim 1, wherein The temperature of the derivatization reaction is 20-25° C., and the time of the derivatization reaction is 5-15 minutes.

5. The method according to claim 1, characterized in that The alkene-containing analyte is obtained by the following method: The components of petroleum oil products are separated to obtain saturates, aromatics, colloids and asphaltenes, among which olefins are retained in the saturates. The separated saturates are selected as the sample to be tested.

6. The method according to claim 1, characterized in that During the mass spectrometry analysis, the product of the derivatization reaction dissociates.

7. The method according to claim 6, characterized in that The parameters of the mass spectrometry analysis are: The sample flow rate is 10-20 μL / min, the nebulizer gas flow rate is 10-20 Arb, the auxiliary gas flow rate is 5 Arb, the backflush gas flow rate is 0.1-1 Arb, the vaporization temperature is 200-300°C, the positive ion discharge current is 5 μA, and the negative ion discharge current is 5 μA; the ion transfer tube temperature is 200-300°C, the mass collection range is 100-800 Da, the collection time is 0.5-1 min, the RF lens voltage is 60%, the automatic gain control is 5.0e4, the isolation window is 0.1 Da, and the CID collision energy is between 5% and 35%.

8. The method according to claim 1, characterized in that The mass spectrometry analysis is performed by low-resolution mass spectrometry, high-resolution mass spectrometry or ultra-high-resolution mass spectrometry.

9. The method according to claim 8, characterized in that The ionization mode of the mass spectrometry analysis is electrospray ionization or atmospheric pressure chemical ionization.

10. The method according to claim 8, characterized in that The ionization solvent for the mass spectrometry analysis is one or more of toluene, methanol, n-heptane, n-hexane, and isooctane.

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