A quantitative detection method for solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions.

Abstract

This invention provides a quantitative detection method for solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions, belonging to the field of in-situ electron analysis technology in mixed fluids. The quantitative detection method of this invention includes the following steps: mixing molybdic acid stock solution, stannous chloride solution, and water to obtain a standard heteropolyblue solution; measuring the absorbance at a wavelength of 973 nm; and plotting a standard curve of solvent electron quantity versus absorbance. The molybdic acid reaction solution and n-hexadecane are added separately to a quartz sample vial to construct a hydrocarbon-water interface system. The sealed quartz sample vial is heated at a constant temperature. After the reaction is complete, the absorbance of the molybdic acid reaction solution at a wavelength of 973 nm is measured, and the absorbance is substituted into the standard curve to obtain the solvent electron quantity. The method of this invention has a limit of quantitation of up to 0.2 mmol / L, and can accurately determine the solvent electron content over a wide concentration range, providing a reliable tool for the detailed study of electronic behavior in micro-interface reactions.

Description

Technical Field

[0001] This invention relates to the field of in-situ electronic analysis technology in mixed fluids, and in particular to a method for quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions. Background Technology

[0002] Solvated electrons, especially hydrated electrons (e - aq Hydrocarbons, as highly reactive reducing intermediates, are widely found in radiation chemistry, aqueous solution reactions, geological processes, and energy conversion systems. Recent studies have revealed that in confined interfaces or microdroplet environments, a large number of solvated electrons can be spontaneously generated at room temperature or even high temperatures due to effects such as charge separation, interfacial polarization, and localized ultra-high electric fields. Hydrocarbon-water interfaces, especially micro / nanoscale droplet systems formed under high temperature and high pressure conditions, are considered important sites for inducing solvated electron generation due to their enormous specific surface area and unique interfacial physicochemical environment. These interfacial electrons have potential key roles in petroleum cracking, geological hydrocarbon evolution, high-temperature hydrothermal synthesis, and emerging microdroplet chemistry.

[0003] However, direct and quantitative detection of solvent electrons induced by microdroplets at dynamic interfaces in high-temperature, high-pressure, multiphase mixed fluids has always been a major technical challenge in analytical chemistry and interface science. This is mainly limited by the following points: (1) Difficulty in in-situ detection under extreme conditions: Under high-temperature and high-pressure conditions, traditional electrochemical probes have poor stability and extremely short electron lifetimes (microseconds or even nanoseconds). Conventional spectroscopic methods (such as transient absorption spectroscopy) are difficult to perform in-situ and stable measurements. Most existing commercial instruments are not compatible with high-pressure sealed and high-temperature resistant optical windows and sample cells. (2) Complexity and instability of interfacial processes: The formation, aggregation, and movement of hydrocarbon-water interface microdroplets are dynamic processes. The electron yield induced by these processes is closely related to the size, distribution, interfacial tension, and temperature and pressure of the microdroplets. The signals are transient and spatially inhomogeneous, making them difficult to capture and integrate. (3) Lack of highly selective capture and signal transduction mechanisms: Solvent electrons are highly active and are easily consumed by impurities, quenchers, or their own decomposition in the system. Existing indirect detection methods (such as using nitro compounds, nitrogen oxides, etc. as probes) often lack selectivity, are easily affected by coexisting reducing substances, and the probe molecules themselves may decompose at high temperatures, leading to inaccurate quantification. (4) Lack of quantitative calibration system: In non-aqueous phases or mixed solvents, the yield, stability and reactivity of solvent electrons are significantly different from those in aqueous phases, and there is a lack of reliable quantitative standard methods and standard substances suitable for high temperature and high pressure multiphase systems.

[0004] Therefore, developing a method that can withstand high temperature and high pressure, selectively capture and stabilize interfacial solvent electrons, and accurately quantify them using conventional instruments is of great significance for revealing the electron generation mechanism of micro-interfaces and evaluating their chemical reactivity. It is also a key step in promoting the field from observation of phenomena to quantitative science. Summary of the Invention

[0005] The purpose of this invention is to provide a quantitative detection method for solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions, thereby solving the problem that existing technologies cannot effectively quantify electrons induced by microdroplets at the interface of hydrocarbon-water systems under high temperature and high pressure conditions.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for the quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions, comprising the following steps: 1) Molybdenum silicon powder and water are mixed to obtain a stock solution of molybdenum silicon; stannous chloride and hydrochloric acid are mixed to obtain a stannous chloride solution; 2) Mix molybdic acid stock solution, stannous chloride solution and water to obtain standard heteropolyblue solution. Use a UV spectrophotometer to measure the absorbance of standard heteropolyblue solution at a wavelength of 973 nm and plot a standard curve of solvent electron quantity and absorbance. The mass fraction of the standard heteropolyblue solution is 0.01–0.1%, corresponding to a solvent electron content of 0.219–2.19 mmol / L; 3) Mix the molybdenum silylate stock solution with water to obtain the molybdenum silylate reaction solution; add the molybdenum silylate reaction solution and n-hexadecane to a quartz sample vial, then seal it to construct a hydrocarbon-water interface system; 4) The sealed quartz sample bottle is heated at a constant temperature. During the heating process, a large number of microdroplets are generated at the hydrocarbon-water interface, which induces the generation of solvent electrons. After the reaction is completed, the absorbance of the molybdic acid reaction solution at a wavelength of 973 nm is measured with an ultraviolet spectrophotometer. The absorbance is substituted into the standard curve to obtain the amount of solvent electrons.

[0007] Preferably, the mass fraction of the molybdenum silicate stock solution in step 1) is 0.8~1.2%; the molybdenum silicate powder is dried molybdenum silicate powder, and the drying temperature is 110~130℃ for 1~3h.

[0008] Preferably, the stannous chloride solution in step 1) has a mass fraction of 1.8-2.2% and the hydrochloric acid concentration is 0.8-1.2 mol / L.

[0009] Preferably, the mass fraction of the molybdic acid stock solution is 1%, and the mass fraction of the stannous chloride solution is 2%.

[0010] Preferably, the volume ratio of the molybdic acid stock solution, stannous chloride solution and water in step 2) is 1~10:2:88~97; the absorbance of steps 2) and 4) is zeroed with deionized water.

[0011] Preferably, the volume ratio of the molybdic acid stock solution, stannous chloride solution, and water in step 2) includes 1:2:97, 1.5:2:96.5, 2:2:96, 2.5:2:95.5, and 10:2:88, respectively. The mass fractions of the standard heteropolyblue solution are 0.01%, 0.015%, 0.02%, 0.025%, and 0.1%, respectively, and the corresponding solvent electron amounts are 0.219 mmol / L, 0.329 mmol / L, 0.438 mmol / L, 0.548 mmol / L, and 2.19 mmol / L, respectively.

[0012] Preferably, the volume ratio of the molybdic acid stock solution, stannous chloride solution, and water in step 2) includes 1:2:97, 2:2:96, 4:2:94, 6:2:92, and 8:2:90, respectively, with mass fractions of the standard heteropolyblue solution of 0.01%, 0.02%, 0.04%, 0.06%, and 0.08%, respectively, and corresponding solvent electron amounts of 0.219 mmol / L, 0.438 mmol / L, 0.876 mmol / L, 1.314 mmol / L, and 1.752 mmol / L, respectively.

[0013] Preferably, the mass fraction of the molybdic acid reaction solution in step 3) is 0.08~0.12%; the volume ratio of the molybdic acid reaction solution to n-hexadecane is 2~3:0.4~0.6.

[0014] Preferably, the temperature of the constant temperature heating in step 4) is 160~400℃ and the time is 90~210min.

[0015] Preferably, the limit of quantitation of solvent electrons induced by microdroplets at the hydrocarbon-water interface can reach 0.2 mmol / L.

[0016] The beneficial effects of this invention are: 1) Achieving indirect quantitative detection of solvent electrons under high temperature and high pressure conditions: This invention uses molybdic acid as an electron indicator, taking advantage of its electron sensitivity and ability to capture electrons and reduce them to heteropolyblue. Combined with ultraviolet spectrophotometry for external standard quantification, it effectively solves the technical problem of the difficulty in directly quantifying solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions.

[0017] 2) High sensitivity and low limit of quantitation: The method of this invention has a limit of quantitation of solvent electrons as low as 0.2 mmol / L, which can accurately determine the content of solvent electrons over a wide concentration range, providing a reliable tool for the fine study of electronic behavior in micro-interface reactions.

[0018] 3) Simple operation and strong applicability: The detection process of this invention does not require complex in-situ devices. It can be completed by conventional heating equipment (such as a forced-air drying oven, hot and cold stage) and ultraviolet spectrophotometer. It is suitable for a wide temperature range of 160~400℃, which is convenient for promotion and application in laboratories and industrial scenarios. Attached Figure Description

[0019] Figure 1 The standard curve for solvent electron quantity and absorbance in Example 1; Figure 2 This is a color comparison diagram of the molybdic acid reaction solution before and after the reaction in Example 1. Detailed Implementation

[0020] This invention provides a method for the quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions, comprising the following steps: 1) Molybdenum silicon powder and water are mixed to obtain a stock solution of molybdenum silicon; stannous chloride and hydrochloric acid are mixed to obtain a stannous chloride solution; 2) Mix molybdic acid stock solution, stannous chloride solution and water to obtain standard heteropolyblue solution. Use a UV spectrophotometer to measure the absorbance of standard heteropolyblue solution at a wavelength of 973 nm and plot a standard curve of solvent electron quantity and absorbance. The mass fraction of the standard heteropolyblue solution is 0.01–0.1%, corresponding to a solvent electron content of 0.219–2.19 mmol / L; 3) Mix the molybdenum silylate stock solution with water to obtain the molybdenum silylate reaction solution; add the molybdenum silylate reaction solution and n-hexadecane to a quartz sample vial, then seal it to construct a hydrocarbon-water interface system; 4) The sealed quartz sample bottle is heated at a constant temperature. During the heating process, a large number of microdroplets are generated at the hydrocarbon-water interface, which induces the generation of solvent electrons. After the reaction is completed, the absorbance of the molybdic acid reaction solution at a wavelength of 973 nm is measured with an ultraviolet spectrophotometer. The absorbance is substituted into the standard curve to obtain the amount of solvent electrons.

[0021] In this invention, the mass fraction of the molybdenum silicate stock solution in step 1) is preferably 0.8-1.2%, more preferably 0.9-1.1%, and even more preferably 1%; the molybdenum silicate powder is dried molybdenum silicate powder, the drying temperature is preferably 110-130℃, more preferably 115-125℃, and even more preferably 120℃, and the drying time is preferably 1-3h, more preferably 1.5-2.5h, and even more preferably 2h.

[0022] In this invention, the mass fraction of the stannous chloride solution in step 1) is preferably 1.8-2.2%, more preferably 1.9-2.1%, and even more preferably 2%; the concentration of hydrochloric acid is preferably 0.8-1.2 mol / L, more preferably 0.9-1.1 mol / L, and even more preferably 1 mol / L.

[0023] In this invention, the specific process for obtaining a molybdenum silicon stock solution by mixing molybdenum silicon powder and water is as follows: The dried molybdenum silicon powder is dissolved in deionized water to obtain a molybdenum silicon solution; the molybdenum silicon solution is diluted with deionized water to obtain a molybdenum silicon stock solution; the mass fraction of the molybdenum silicon solution is 8-12%; and the mass fraction of the molybdenum silicon stock solution is 0.8-1.2%. The specific process for obtaining stannous chloride solution by mixing stannous chloride solution and hydrochloric acid is as follows: stannous chloride is dissolved in hydrochloric acid to obtain stannous chloride solution; the stannous chloride solution is diluted with hydrochloric acid to obtain stannous chloride solution; the mass fraction of stannous chloride solution is 18~22%, and the mass fraction of stannous chloride solution is 1.8~2.2%.

[0024] In this invention, the volume ratio of the molybdate stock solution, stannous chloride solution, and water in step 2) is preferably 1~10:2:88~97, more preferably 1:2:97, 1.5:2:96.5, 2:2:96, 2.5:2:95.5, or 10:2:88. The mass fractions of the standard heteropolyblue solution are 0.01%, 0.015%, 0.02%, 0.025%, and 0.1%, respectively, corresponding to solvent electron concentrations of 0.219 mmol / L, 0.329 mmol / L, 0.438 mmol / L, and 0.548 mmol / L, respectively. The volume ratios of the standard heteropolyblue solution are 1:2:97, 2:2:96, 4:2:94, 6:2:92, and 8:2:90, respectively, with mass fractions of 0.01%, 0.02%, 0.04%, 0.06%, and 0.08%, respectively, and corresponding solvent electron amounts of 0.219 mmol / L, 0.438 mmol / L, 0.876 mmol / L, 1.314 mmol / L, and 1.752 mmol / L, respectively.

[0025] In this invention, the absorbance of steps 2) and 4) is zeroed using deionized water.

[0026] In this invention, the mass fraction of the molybdenum silicate reaction solution in step 3) is preferably 0.08~0.12%, more preferably 0.09~0.11%, and even more preferably 0.1%; the volume ratio of the molybdenum silicate reaction solution to n-hexadecane is preferably 2~3:0.4~0.6, more preferably 2.2~2.8:0.45~0.55, and even more preferably 2.5:0.5.

[0027] In this invention, the presence of strong reducing substances (sulfites, stannous salts, or halides, etc.) in the silicomolybdic acid reaction solution may interfere with the quantitative process.

[0028] In this invention, the temperature of the constant temperature heating in step 4) is preferably 160~400℃, more preferably 200~350℃, and even more preferably 220~300℃. The constant temperature heating time is preferably 90~210min, more preferably 120~180min, and even more preferably 150~160min.

[0029] In this invention, the limit of quantification for solvent electrons induced by microdroplets at the hydrocarbon-water interface can reach 0.2 mmol / L.

[0030] In this invention, step 3) involves sealing the quartz sample bottle by putting a quartz cap on it and tightening the seal; step 4) involves placing the sealed quartz sample bottle in a heating device for constant temperature heating. The heating device is an external heating device, including a forced-air drying oven or a hot and cold stage.

[0031] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] In this embodiment, the forced-air drying oven is a DHG-9075A forced-air drying oven, and the ultraviolet spectrophotometer is a Lambda1050+ ultraviolet spectrophotometer.

[0033] Example 1

[0034] Preparation of molybdic acid stock solution: Place molybdic acid powder in a forced-air drying oven and dry at 120℃ for 2 hours. Place 1g of dried molybdic acid powder in a 100mL beaker, and dissolve it in 10mL of deionized water using a pipette. Then transfer the solution to a 100mL volumetric flask and finally dilute to 100mL with deionized water to obtain a 1% molybdic acid stock solution.

[0035] Preparation of stannous chloride solution: Place 2g of stannous chloride in a 100mL beaker, and dissolve it in 10mL of 1mol / L hydrochloric acid using a pipette. Then transfer the solution to a 100mL volumetric flask and finally dilute to 100mL with 1mol / L hydrochloric acid to obtain a 2% stannous chloride solution.

[0036] Plotting the standard curve: 1 mL, 1.5 mL, 2 mL, 2.5 mL, and 10 mL of molybdic acid stock solution were transferred to 100 mL volumetric flasks. 2 mL of stannous chloride solution was pipetted into each flask to reduce the molybdic acid. The flasks were then diluted to 100 mL with deionized water, yielding standard heteropolyblue solutions of 0.01%, 0.015%, 0.02%, 0.025%, and 0.1%, corresponding to solvent electron concentrations of 0.219 mmol / L, 0.329 mmol / L, 0.438 mmol / L, 0.548 mmol / L, and 2.19 mmol / L, respectively. The absorbance of the standard heteropolyblue solutions at 973 nm was measured using a UV spectrophotometer. The sample was zeroed with deionized water. A standard curve was plotted, showing the relationship between solvent electron concentration and absorbance. The equation for the standard curve was y = 2.195x - 0.463, where x is absorbance, y is solvent electron concentration, and R0 is the solvent electron concentration. 2 =0.9999.

[0037] Quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface: Transfer 10 mL of molybdic acid stock solution to a 100 mL volumetric flask, and then dilute to 100 mL with deionized water to obtain a 0.1% molybdic acid reaction solution.

[0038] In the reaction, 2.5 mL of molybdic acid reaction solution was first transferred to a quartz sample vial using a pipette, followed by 0.5 mL of n-hexadecane. The quartz sample vial was then capped with a quartz cap and tightened to create a hydrocarbon-water interface system. The sealed quartz sample vial was then placed in a forced-air drying oven, and the heating temperature was set to 160°C. Timing began after the temperature stabilized. During heating, a large number of microdroplets were generated at the hydrocarbon-water interface, inducing solvent electron generation. The reaction was stopped after 180 min. After the solution cooled, the reacted molybdic acid solution was extracted using a syringe, and the absorbance of the reacted molybdic acid reaction solution at a wavelength of 973 nm was measured using a UV spectrophotometer. The absorbance was zeroed with deionized water, and the solvent electron quantity was obtained by substituting the absorbance into the standard curve (standard curve equation).

[0039] The standard curves for solvent electron quantity and absorbance in Example 1 are as follows: Figure 1 As shown. The color comparison of the molybdic acid reaction solution before and after the reaction in Example 1 is shown below. Figure 2 As shown.

[0040] Example 2

[0041] The only difference between Example 2 and Example 1 is the plotting of the standard curve and the heating time of the sealed quartz sample bottle in the forced-air drying oven; the other process conditions are the same as in Example 1. Plotting the standard curve: Transfer 1 mL, 2 mL, 4 mL, 6 mL, and 8 mL of molybdic acid stock solution to 100 mL volumetric flasks, respectively. Use a pipette to transfer 2 mL of stannous chloride solution to reduce the molybdic acid. Then, dilute to 100 mL with deionized water to obtain standard heteropolyblue solutions of 0.01%, 0.02%, 0.04%, 0.06%, and 0.08%, respectively, corresponding to solvent electron concentrations of 0.219 mmol / L, 0.438 mmol / L, 0.876 mmol / L, 1.314 mmol / L, and 1.752 mmol / L. Measure the absorbance of the standard heteropolyblue solutions at 973 nm using a UV spectrophotometer. Zero the sample with deionized water and plot the standard curve of solvent electron concentration versus absorbance: y = 1.932x - 0.265, where x is absorbance, y is solvent electron concentration, and R0 is the solvent electron concentration. 2 =0.9999.

[0042] The sealed quartz sample vials were heated in a forced-air drying oven for 120 minutes.

[0043] Example 3

[0044] The only difference between Example 3 and Example 1 is the quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface; the other process conditions are the same as in Example 1.

[0045] Quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface: Transfer 9 mL of molybdic acid stock solution to a 100 mL volumetric flask, and then dilute to 100 mL with deionized water to obtain a 0.09% molybdic acid reaction solution.

[0046] In the reaction, 2.8 mL of molybdic acid reaction solution was first transferred to a quartz sample vial using a pipette, followed by 0.55 mL of n-hexadecane. The vial was then capped with a quartz cap and tightened to create a hydrocarbon-water interface system. The sealed quartz sample vial was then placed in a forced-air drying oven at 220°C. Timing was started after the temperature stabilized. During heating, numerous microdroplets were generated at the hydrocarbon-water interface, inducing solvent electron generation. The reaction was stopped after 150 min. After the solution cooled, the reacted molybdic acid solution was extracted using a syringe, and the absorbance at 973 nm was measured using a UV spectrophotometer. Zeroing was performed with deionized water, and the absorbance was substituted into a standard curve to obtain the solvent electron quantity.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for quantitative detection of solvent electrons induced by microdroplets at the hydrocarbon-water interface under high temperature and high pressure conditions, characterized in that, It includes the following steps: 1) Molybdenum silicon powder and water are mixed to obtain a stock solution of molybdenum silicon; stannous chloride and hydrochloric acid are mixed to obtain a stannous chloride solution; 2) Mix molybdic acid stock solution, stannous chloride solution and water to obtain standard heteropolyblue solution. Use a UV spectrophotometer to measure the absorbance of standard heteropolyblue solution at a wavelength of 973 nm and plot a standard curve of solvent electron quantity and absorbance. The mass fraction of the standard heteropolyblue solution is 0.01–0.1%, corresponding to a solvent electron content of 0.219–2.19 mmol / L; 3) Mix the molybdenum silylate stock solution with water to obtain the molybdenum silylate reaction solution; add the molybdenum silylate reaction solution and n-hexadecane to a quartz sample vial, then seal it to construct a hydrocarbon-water interface system; 4) The sealed quartz sample bottle is heated at a constant temperature. During the heating process, a large number of microdroplets are generated at the hydrocarbon-water interface, which induces the generation of solvent electrons. After the reaction is completed, the absorbance of the molybdic acid reaction solution at a wavelength of 973 nm is measured with an ultraviolet spectrophotometer. The absorbance is substituted into the standard curve to obtain the amount of solvent electrons.

2. The quantitative detection method according to claim 1, characterized in that, Step 1) The mass fraction of the molybdenum silicate stock solution is 0.8~1.2%; the molybdenum silicate powder is dried molybdenum silicate powder, and the drying temperature is 110~130℃ for 1~3h.

3. The quantitative detection method according to claim 1 or 2, characterized in that, In step 1), the stannous chloride solution has a mass fraction of 1.8-2.2%, and the hydrochloric acid concentration is 0.8-1.2 mol / L.

4. The quantitative detection method according to claim 3, characterized in that, The mass fraction of the molybdic acid stock solution is 1%, and the mass fraction of the stannous chloride solution is 2%.

5. The quantitative detection method according to claim 4, characterized in that, In step 2), the volume ratio of the molybdic acid stock solution, stannous chloride solution, and water is 1~10:2:88~97; the absorbance of steps 2) and 4) is zeroed with deionized water.

6. The quantitative detection method according to claim 5, characterized in that, In step 2), the volume ratios of the molybdic acid stock solution, stannous chloride solution, and water include 1:2:97, 1.5:2:96.5, 2:2:96, 2.5:2:95.5, and 10:2:

88. The mass fractions of the standard heteropolyblue solution are 0.01%, 0.015%, 0.02%, 0.025%, and 0.1%, respectively, and the corresponding solvent electron amounts are 0.219 mmol / L, 0.329 mmol / L, 0.438 mmol / L, 0.548 mmol / L, and 2.19 mmol / L, respectively.

7. The quantitative detection method according to claim 5, characterized in that, In step 2), the volume ratios of the molybdic acid stock solution, stannous chloride solution, and water include 1:2:97, 2:2:96, 4:2:94, 6:2:92, and 8:2:90, respectively. The mass fractions of the standard heteropolyblue solution are 0.01%, 0.02%, 0.04%, 0.06%, and 0.08%, respectively, and the corresponding solvent electron amounts are 0.219 mmol / L, 0.438 mmol / L, 0.876 mmol / L, 1.314 mmol / L, and 1.752 mmol / L, respectively.

8. The quantitative detection method according to any one of claims 4 to 7, characterized in that, Step 3) The mass fraction of the silicomolybdic acid reaction solution is 0.08~0.12%; the volume ratio of the silicomolybdic acid reaction solution to n-hexadecane is 2~3:0.4~0.

6.

9. The quantitative detection method according to claim 8, characterized in that, Step 4) The constant temperature heating is 160~400℃ and the time is 90~210min.

10. The quantitative detection method according to claim 9, characterized in that, The limit of quantitation for solvent electrons induced by microdroplets at the hydrocarbon-water interface can reach 0.2 mmol / L.

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