Liquid fuel bio-based component proportion detection method and device

Abstract

The invention relates to the field of liquid fuel detection, and discloses a liquid fuel bio-based component proportion detection method and device. The detection method comprises a graphite sample preparation step, a 14C test step and a bio-based component proportion calculation step. Wherein in the graphite sample preparation step, liquid fuel is converted into a graphite sample in a closed system through the steps of drug loading, sample oxidation, transfer purification and catalytic reduction, and then the activity of 14C is measured by using an accelerator mass spectrometer and the proportion of bio-based components in the liquid fuel is calculated. According to the invention, air carbon dioxide pollution is avoided, the detection precision and reliability are improved, and an efficient technical scheme is provided for liquid fuel quality control and renewable attribute evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of liquid fuel detection, in particular to a method and device for detecting the proportion of bio-based components in liquid fuel. BACKGROUND

[0002] The development and utilization of bio-based and fossil-based mixed liquid fuel has attracted widespread attention, and its quality control and renewable property assessment depend on accurate determination of the proportion of bio-based components. At present, based on the carbon-14 isotope, the main methods for detecting the proportion of bio-based components in liquid fuel include the direct liquid scintillation counting method and the liquid scintillation counting-benzene synthesis method. 14 The former is simple to operate, but is easily affected by sample color quenching, resulting in low detection accuracy. The latter converts sample carbon into benzene for detection, although it improves measurement accuracy, but is limited by the high measurement background and lower detection limit of the liquid scintillation counting method, and its measurement precision is still not ideal.

[0003] Accelerator mass spectrometry is another 14 C detection technology, and its detection limit is significantly lower than that of the liquid scintillation counting method, and is considered to be the most accurate 14 C detection technology. Accelerator mass spectrometry-graphitization method converts sample carbon into graphite for detection, which has been successfully applied in the determination of the blending ratio of bio-based fuel in solid fuel (such as biomass and coal). However, due to the complexity and volatility of the organic components of liquid fuel, it is difficult to efficiently and non-pollutingly convert sample carbon into graphite samples suitable for accelerator mass spectrometry detection, which limits the large-scale application of this technology in the field of liquid fuel bio-carbon detection. SUMMARY

[0004] To solve the above problems, the present application provides a method and device for detecting the proportion of bio-based components in liquid fuel.

[0005] The first aspect of the present application provides a method for detecting the proportion of bio-based components in liquid fuel. The method comprises the following steps: Graphite sample preparation step: preparing liquid fuel into a graphite sample; 14 C test step: detecting the 14 C activity of the graphite sample with an accelerator mass spectrometer; Bio-based component proportion calculation step: calculating the proportion of bio-based components in liquid fuel according to the 14 C activity of the graphite sample.

[0006] By converting liquid fuel into a graphite sample suitable for accelerator mass spectrometry analysis, and using the extremely high detection sensitivity of accelerator mass spectrometry, the method can accurately determine the proportion of bio-based components in liquid fuel.

[0007] Optionally, in the step of preparing the graphite sample, a liquid fuel graphite preparation device is used to prepare the liquid fuel into a graphite sample. The liquid fuel graphite preparation device comprises: an oxidation assembly; a condenser tube, which is in communication with the oxidation assembly; a catalytic reduction assembly, which is in communication with the condenser tube; and a vacuum pump, which is in communication with the catalytic reduction assembly and is in communication with the oxidation assembly and the condenser tube. The step of preparing the graphite sample comprises the following steps: The step of loading the reagents: the liquid fuel and the oxidant are placed in the oxidation assembly, and the reducing agent and the catalyst are placed in the catalytic reduction assembly. The oxidant used in the step of loading the reagents is used to provide oxygen atoms for the oxidation reaction. The oxidant can be, but is not limited to, a metal oxide type oxidant, such as copper oxide. The reducing agent used in the step of loading the reagents is used to reduce the carbon dioxide into graphite. The reducing agent can be, but is not limited to, zinc powder, zinc-titanium hydride mixed reagent. The catalyst used in the step of loading the reagents is used to catalyze the reduction reaction and provide a graphite growth bed. The catalyst can be, but is not limited to, iron or cobalt. The step of oxidizing the sample: the oxidation assembly is cooled in stages to fix the liquid fuel, the oxidation assembly and the vacuum pump are connected to exhaust the impure gas, and then the oxidation assembly is heated to oxidize the carbon in the liquid fuel into carbon dioxide gas. The step of transferring and purifying: the gas obtained in the step of oxidizing the sample is introduced into the condenser tube, the condenser tube is cooled to fix the carbon dioxide gas, the condenser tube and the vacuum pump are connected to exhaust the impure gas, and then the cooling temperature is increased to fix the water vapor while releasing the carbon dioxide gas. The step of catalytic reduction: the purified carbon dioxide gas obtained in the step of transferring and purifying is introduced into the catalytic reduction assembly, and the catalytic reduction assembly is heated to reduce the carbon dioxide gas into a graphite sample.

[0008] This series of steps constitutes a closed and continuous processing flow, which can effectively prevent the sample from being contaminated by air carbon dioxide and remove interfering impurities such as water, thereby ensuring the purity of the final graphite sample.

[0009] Optionally, in the step of oxidizing the sample, the liquid fuel is fixed at a first cooling temperature while the first impure gas is exhausted, and then the first cooling temperature is increased to a second cooling temperature to maintain the fixation of the liquid fuel at the second cooling temperature and release the second impure gas fixed at the first cooling temperature, the second impure gas including the carbon dioxide in the air. The first cooling temperature is lower than -60°C, and the second cooling temperature ranges from -78°C to -60°C. The condensing agent available for the first cooling temperature is liquid nitrogen, dry ice, liquid nitrogen-ethanol mixed slurry, or dry ice-ethanol mixed slurry; the condensing agent available for the second cooling temperature is liquid nitrogen-ethanol mixed slurry or dry ice-ethanol mixed slurry. By controlling the cooling temperature in stages, the liquid fuel can be effectively fixed to prevent its volatilization loss, and the impure gas in the system can be selectively removed to create a clean environment for the subsequent oxidation reaction.

[0010] Optionally, in the transfer purification step, the gas obtained by the sample oxidation step is fixed at a third cooling temperature while a third impurity gas is pumped out, and then the third cooling temperature is raised to a fourth temperature to maintain the fixed water vapor at the fourth cooling temperature and release the carbon dioxide gas fixed at the third cooling temperature. The third cooling temperature is lower than -78.5℃, and the fourth cooling temperature ranges from -60℃ to -10℃. The condensing agent available for the third cooling temperature is liquid nitrogen, liquid nitrogen-ethanol mixed slurry or dry ice-ethanol mixed slurry; the condensing agent available for the fourth cooling temperature is liquid nitrogen-ethanol mixed slurry, dry ice-ethanol mixed slurry or salt ice mixture. This temperature control strategy can efficiently separate and remove the impurity gas in the carbon dioxide gas, achieve the purification of the gas, and avoid the adverse effects of the impurity gas on the subsequent catalytic reduction reaction.

[0011] Optionally, in the sample oxidation step, the temperature of the heating oxidation assembly ranges from 700℃ to 900℃, and the time ranges from 2 to 7 hours; in the catalytic reduction step, the temperature of the heating catalytic reduction assembly ranges from 450℃ to 650℃, and the time ranges from 4 to 7 hours.

[0012] Optionally, the liquid fuel is a mixed liquid of bio-based fuel and fossil-based fuel. The method is suitable for accurate analysis of the bio-based content of such mixed fuel.

[0013] The second aspect of the present application provides a device for detecting the proportion of bio-based components in liquid fuel. The device is suitable for any of the above-mentioned methods for detecting the proportion of bio-based components in liquid fuel, and comprises a liquid fuel graphitization device and an accelerator mass spectrometer.

[0014] Optionally, the liquid fuel graphitization device comprises: an electric heating furnace for heating the oxidation assembly and the catalytic reduction assembly; an oxidation assembly comprising a sample tube and an oxidant tube; a transfer purification assembly connected to the oxidation assembly, the transfer purification assembly comprising a first valve, a condenser tube and a second valve; a catalytic reduction assembly connected to the transfer purification assembly, the catalytic reduction assembly comprising a catalytic tube and a reduction tube; and a vacuum pump connected to the catalytic reduction assembly.

[0015] Optionally, the first valve is arranged between the oxidation assembly and the condenser tube, and the second valve is arranged between the condenser tube and the catalytic reduction assembly. This valve layout facilitates independent vacuum control and gas passage management in the oxidation, purification and reduction stages.

[0016] Optionally, the liquid fuel graphitization device is a closed system. The closed system can avoid the introduction of external pollution (especially air carbon dioxide) during sample preparation, thereby ensuring the reliability of the measurement results. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1A flow chart of a method for detecting a bio-based component ratio of a liquid fuel is provided for a first embodiment of the present application.

[0018] Figure 2 A structural schematic diagram of a liquid fuel graphitization device is provided for some embodiments of the present application.

[0019] Figure 3 A bio-oil-toluene mixed fuel bio-based component ratio determination result is provided for a first embodiment of the present application.

[0020] Figure 4 A bio-oil-toluene mixed fuel bio-based component ratio determination result is provided for a first embodiment of the present application.

[0021] Figure 5 An aviation kerosene mixed fuel bio-based component ratio determination result is provided for a first embodiment of the present application.

[0022] Figure 6 An aviation kerosene mixed fuel bio-based component ratio determination result is provided for a first embodiment of the present application.

[0023] Reference signs: 100-liquid fuel graphitization device, 1-electric heating furnace, 2-oxidation assembly, 21-sample tube, 22-oxidant tube, 3-transfer purification assembly, 31-first valve, 32-condenser tube, 33-second valve, 4-catalytic reduction assembly, 41-catalytic tube, 42-reduction tube, 5-vacuum pump. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] <liquid fuel graphitization device 100> With reference to Figure 2 Some embodiments of the present application provide a liquid fuel graphitization device 100 for preparing a liquid fuel into a graphite sample suitable for accelerator mass spectrometry detection.

[0026] The device includes an electric heating furnace 1, an oxidation component 2, a transfer purification component 3, a catalytic reduction component 4, and a vacuum pump 5. The oxidation component 2 includes a sample tube 21 and an oxidant tube 22, used to oxidize carbon in liquid fuel to carbon dioxide. The transfer purification component 3, connected to the oxidation component 2, includes a first valve 31, a condenser tube 32, and a second valve 33, used to remove water vapor and impurities from the sample carbon dioxide gas and transfer the purified carbon dioxide. The catalytic reduction component 4, connected to the transfer purification component 3, includes a catalytic tube 41 and a reduction tube 42, used to reduce the purified sample carbon dioxide gas to graphite. The vacuum pump 5, connected to the catalytic reduction component 4, is used to evacuate the system pipelines to remove impurities and airborne carbon dioxide contamination. The electric heating furnace 1 can be moved below the oxidation component 2 and the catalytic reduction component 4, and can perform programmed temperature rise and multi-stage temperature adjustment to provide suitable reaction temperatures for the oxidation and catalytic reduction reactions.

[0027] <First Implementation Method> The first embodiment of this invention provides a method for detecting the proportion of bio-based components in liquid fuels. For example... Figure 1 As shown, the method includes graphite sample preparation step S1, 14 C. Test step S2 and bio-based component percentage calculation step S3.

[0028] Graphite sample preparation step S1: This step aims to convert the liquid fuel sample into solid graphite for subsequent high-precision accelerator mass spectrometry analysis. The entire process is carried out in a closed system to minimize contamination from external carbon sources such as airborne carbon dioxide. Graphite sample preparation step S1 can be performed in a manner such as... Figure 2 The liquid fuel graphitization apparatus 100 shown is used in the following sub-steps: Drug loading step S11: Prepare all necessary chemicals for the reaction. Place the oxidant in oxidant tube 22; its function is to provide oxygen atoms for the subsequent oxidation reaction. It should be noted that the oxidant can be a metal oxide type, such as copper oxide. In addition, other oxides that can provide an oxygen source and do not react violently with the system materials can also be considered, such as zinc powder or a zinc-titanium dihydrogen hydride mixture. Add a small amount of liquid fuel, such as 5 μL, to sample tube 21, and then invert it and place it at the bottom of oxidant tube 22. Inverting the tube ensures sufficient contact between the liquid fuel and the oxidant, allowing the oxidation reaction to proceed more thoroughly.

[0029] Next, a reducing agent is placed in the reduction tube 42, a catalyst is placed in the catalytic tube 41, and the catalytic tube 41 is placed in the bottom of the reduction tube 42. The reducing agent is used to reduce the carbon dioxide gas to elemental carbon (graphite), and optional reducing agents include zinc powder or a mixture of zinc and titanium dihydride, which provides a more active reduction environment. The catalyst is used to catalyze the reduction reaction and provide a bed for the growth of the graphite, and optional catalysts include iron powder or cobalt powder. It should be noted that other metals or alloys with similar catalytic activity can also be used.

[0030] The sample oxidation step S12: This step completely oxidizes the carbon elements in the liquid fuel into carbon dioxide gas. First, the liquid fuel is fixed at a first cooling temperature while the first impurities are pumped out. Specifically, a liquid nitrogen cold trap (below -60°C) is placed at the bottom of the oxidation assembly 2. The extremely low temperature of the liquid nitrogen can quickly freeze the added liquid fuel, preventing it from being lost due to evaporation. Subsequently, the first valve 31 and the second valve 33 are opened, and the vacuum pump 5 is started to pump out the impurities in the pipeline system. It should be noted that in addition to liquid nitrogen, other optional condensers include dry ice, liquid nitrogen-ethanol mixed slurry, or dry ice-ethanol mixed slurry.

[0031] After that, the first cooling temperature is raised to a second cooling temperature to maintain the fixed liquid fuel at the second cooling temperature and release the second impurities fixed at the first cooling temperature, including carbon dioxide in the air. Specifically, the liquid nitrogen cold trap at the bottom of the oxidation assembly 2 is replaced with a mixed condenser cold trap. This mixed condenser needs to provide a specific temperature range, for example -78°C ~ -40°C, which can continue to fix the liquid fuel to prevent evaporation, and is sufficient to release the air carbon dioxide and other impurities previously frozen by the liquid nitrogen cold trap, so that part of the impurities are pumped out by the vacuum pump 5. Optional mixed condensers include liquid nitrogen-ethanol mixed slurry or dry ice-ethanol mixed slurry, which can achieve the desired temperature by adjusting the proportion.

[0032] After the impurities are removed, the first valve 31 is closed, and the electric heating furnace 1 is moved under the oxidation assembly 2 to heat it. The heating conditions can be adjusted according to the type and amount of liquid fuel, for example, at a temperature of 700°C ~ 900°C for 2 ~ 7 hours. At this high temperature, the liquid fuel vapor reacts with the oxidant (such as copper oxide) to generate carbon dioxide gas. Since the first valve 31 has been closed, the carbon dioxide generated by the reaction is confined inside the oxidation assembly 2.

[0033] The transfer purification step S13: After the oxidation reaction is completed, the generated carbon dioxide gas needs to be transferred and purified to remove water vapor and other impurities that may be produced during the reaction. First, the second valve 33 is closed, and then the first valve 31 is opened. At this time, the gas stored in the oxidation assembly 2 diffuses to the transfer purification assembly 3 due to the pressure difference.

[0034] Next, the gas obtained by the sample oxidation step S12 is fixed at a third cooling temperature while a third impurity gas is pumped out. Specifically, a liquid nitrogen cold trap (lower than -78.5°C) is wrapped under the condenser tube 32, and the second valve 33 is opened. The low temperature of the liquid nitrogen can freeze the carbon dioxide gas in the condenser tube 32, while the remaining uncondensed impurity gas (such as oxygen, nitrogen, etc.) is pumped out by the vacuum pump 5. Then, the second valve 33 is closed. It should be noted that, in addition to liquid nitrogen, other condensing agents such as liquid nitrogen-ethanol mixed slurry or dry ice-ethanol mixed slurry can also be selected.

[0035] Finally, the third cooling temperature is raised to a fourth cooling temperature to maintain the fixed water vapor and release the carbon dioxide gas fixed at the third cooling temperature. Specifically, the liquid nitrogen cold trap under the condenser tube 32 is replaced with another mixed condensing agent cold trap, which can be set to a temperature range of -78°C to 0°C, and the optional mixed condensing agent includes but is not limited to liquid nitrogen-ethanol mixed slurry, dry ice-ethanol mixed slurry or salt ice mixture. The temperature range is higher than the sublimation point of carbon dioxide (-78.5°C) but lower than the freezing point of water. Therefore, the purified carbon dioxide gas is released, while the water vapor is fixed in the cold trap. In this way, the purification of carbon dioxide gas is achieved.

[0036] Catalytic reduction step S14: This step reduces the purified carbon dioxide gas into graphite. First, the vacuum pump 5 is closed and the second valve 33 is opened. A liquid nitrogen cold trap is wrapped under the catalytic reduction assembly 4. The purified carbon dioxide gas diffuses to the catalytic reduction assembly due to the pressure difference, and is captured by the liquid nitrogen cold trap in the catalytic reduction assembly 4. Subsequently, the second valve 33 is closed to completely seal the catalytic reduction assembly 4.

[0037] Then, the electric heating furnace 1 is moved under the catalytic reduction assembly 4 for heating. The heating condition is usually set to 450°C to 650°C for 1 to 7 hours, and a multi-stage temperature rising program can be used, for example, first maintained at 500°C for 4 hours, then raised to 550°C for 3 hours. Under the action of heating and catalyst (such as iron powder), carbon dioxide reacts with reducing agent (such as mixed reagent of zinc and titanium dihydride) to generate carbon atoms which deposit and grow on the surface of the catalyst to form a graphite sample suitable for accelerator mass spectrometry detection.

[0038] 14 C test step S2: The prepared graphite sample is taken out from the catalytic reduction assembly 4 and subjected to target pressing treatment to form a dense target sheet. Then the target sheet is sent into the accelerator mass spectrometer for testing. The accelerator mass spectrometer accurately measures the ratio of 14 C to 12 C in the sample through a series of processes such as atomic stripping, mass selection, acceleration, magnetic analysis and detector discrimination, thereby obtaining the14 C activity, usually in units of pMC (percent modern carbon).

[0039] Bio-based component ratio calculation step S3: Since the geological age of fossil fuels is far beyond the half-life of C (about 5730 years), the internal C has decayed almost completely, 14 C activity can be considered as 0 pMC. Therefore, the C activity of the mixed liquid fuel graphite sample is entirely derived from the bio-based component therein. The C activity of the bio-based component is similar to the level of C in the contemporary atmosphere (about 100 pMC). The proportion R (%) of the amount of bio-based carbon in the total carbon in the liquid fuel can be calculated according to the following formula: 14 14 14 14 14 (1) wherein, 14 C mixed is the measured C activity of the mixed fuel graphite sample, 14 C 14 is the C activity of the biomass source in the liquid fuel. biogenic C 14 The C activity of the biomass source can be obtained by performing the same sample preparation and measurement on a pure biomass source fuel, or calculated according to the biomass activity prediction model based on the biomass type, growth time, growth location, etc. of the pure biomass source fuel. If the pure biomass source fuel cannot be prepared and measured, or the information of the pure biomass source fuel is unknown, the average C activity value of the test atmosphere of the current year can also be directly used as an approximation. 14 C biogenic The C activity of the biomass source can be obtained by performing the same sample preparation and measurement on a pure biomass source fuel, or calculated according to the biomass activity prediction model based on the biomass type, growth time, growth location, etc. of the pure biomass source fuel. If the pure biomass source fuel cannot be prepared and measured, or the information of the pure biomass source fuel is unknown, the average C activity value of the test atmosphere of the current year can also be directly used as an approximation. 14 C

[0041] To verify the accuracy and reliability of the method, two experiments of determining the bio-based component ratio of mixed liquid fuels were performed in this embodiment. The specific parameters set in the graphite sample preparation step S1 are as follows: copper oxide was used as the oxidizing agent, with a dosage of 60-80 mg; zinc and titanium dihydride were used as the reducing agent, with a dosage of 60-70 mg of zinc and 20-30 mg of titanium dihydride; iron was used as the catalyst, with a dosage of 6-10 mg; liquid nitrogen cold traps were used to reach the first and third cooling temperatures, -76°C liquid nitrogen-ethanol mixed cold traps were used to reach the second cooling temperature, and -65°C liquid nitrogen-ethanol mixed cold traps were used to reach the fourth cooling temperature; the oxidation reaction heating condition was set to maintain at 900°C for 7 hours, and the catalytic reduction reaction heating was set to maintain at 500°C for 4 hours, and then to maintain at 550°C for 3 hours. Finally, the stored sample carbon dioxide gas was reduced to a graphite sample.

[0042] ​​​​​Bio-oil obtained from the hydrochemical catalytic pyrolysis of poplar wood was mixed with fossil-based toluene at a volume ratio of 1% to 20%. To accurately quantify the bio-carbon content in the mixed liquid fuels, the mass of the two fuels was first determined using a high-precision electronic balance, and then the actual bio-based component percentage was calculated based on the carbon content. Table 1 shows the mass ratio of each fuel and the bio-based component percentage in the six groups of bio-oil and toluene mixed fuels.

[0043] Table 1. Parameters of Bio-oil and Toluene Blended Fuel

[0044] like Figure 3 As shown in Table 2, the measured values ​​are very close to the actual values. In all samples, the absolute error of the proportion of bio-based components is less than 0.21%, and the relative error is less than 3.6%.

[0045] Table 2. Results and errors of the determination of the bio-based component ratio in the bio-oil and toluene blend fuel.

[0046] And, as Figure 4 As shown, the fitting curve equation between the measured value and the actual value is Y = 1.00748X + 0.03653, and the correlation coefficient R is... 2 The value is 0.9999, showing good linearity, especially when the proportion of bio-based components is higher than 5%, the stability of the assay is particularly outstanding.

[0047] Bio-based aviation kerosene and fossil aviation kerosene were mixed at a volume ratio of 1% to 50%. First, the mass of both fuels was measured using a high-precision electronic balance. Then, the actual percentage of bio-based components was calculated based on the carbon content. Table 3 shows the mass ratio of each fuel and the percentage of bio-based components in the five groups of bio-based and fossil aviation kerosene blends.

[0048] Table 3. Parameters of Blended Fuel of Bio-aviation Kerosene and Fossil Aviation Kerosene

[0049] like Figure 5 As shown in Table 4, the measured values ​​are close to the actual values. In all samples, the absolute error of the proportion of bio-based components is less than 0.7%, and the relative error is less than 3.73%.

[0050] Table 4. Results and errors of the determination of the proportion of bio-based components in aviation kerosene blended fuels.

[0051] And, as Figure 6As shown, the fitting curve equation between the measured value and the actual value is Y = 1.0152X + 0.0057, the correlation coefficient R is 0.9996, which shows good linearity, and again reflects the stability of the determination. 2 The value is 0.9996, which shows good linearity, and again reflects the stability of the determination.

[0052] The above experiments prove that the method has high accuracy and reliability in different types of liquid fuels and wide concentration range.

[0053] The present embodiment solves the problem that liquid fuels are difficult to be efficiently and pollution-free converted into graphite samples suitable for accelerator mass spectrometry detection due to their volatility and complex components by a closed graphite sample preparation process including drug loading, sample oxidation, transfer purification and catalytic reduction steps, supplemented by precise temperature and vacuum control strategy; combined with the high sensitivity detection of accelerator mass spectrometry, the precise determination of the proportion of bio-based components in the wide concentration range of 1% to 50% in mixed liquid fuels such as bio-oil-toluene, bio-based and fossil-based aviation kerosene is realized, which provides a high-reliability technical solution for quality control and renewable attribute evaluation of liquid fuels.

[0054] [Second embodiment] The present embodiment provides a liquid fuel bio-based component proportion detection device for realizing the liquid fuel bio-based component proportion detection method in the first embodiment. The device includes a liquid fuel graphitization device 100 and an accelerator mass spectrometer (not shown).

[0055] As shown in Figure 2 The liquid fuel graphitization device 100 includes an electric heating furnace 1, an oxidation assembly 2, a transfer purification assembly 3, a catalytic reduction assembly 4 and a vacuum pump 5. These assemblies are connected by pipelines to form a controllable closed system.

[0056] The electric heating furnace 1 is the heat source of the device. The electric heating furnace 1 can be moved and can be moved to the lower side of the oxidation assembly 2 and the catalytic reduction assembly 4 in turn to provide heating. The electric heating furnace 1 has the functions of programmed temperature rise and multi-stage temperature adjustment, which can accurately provide the reaction temperature required for oxidation reaction and catalytic reduction reaction and maintain the required reaction time.

[0057] The oxidation assembly 2 is used to complete the oxidation of liquid fuel, which includes a sample tube 21 and an oxidant tube 22. The sample tube 21 is used to contain a small amount of liquid fuel, and the oxidant tube 22 is used to contain an oxidant (such as copper oxide). The arrangement of the sample tube 21 inverted in the oxidant tube 22 is an important link to achieve complete reaction.

[0058] The transfer and purification assembly 3 is connected between the oxidation assembly 2 and the catalytic reduction assembly 4, and is responsible for gas transfer and purification. The transfer and purification assembly 3 includes a first valve 31, a condenser tube 32, and a second valve 33. The first valve 31 is arranged between the oxidation assembly 2 and the condenser tube 32, and is used to control the gas outlet of the oxidation assembly 2. The condenser tube 32 uses cold traps of different temperatures outside to achieve the removal of impurities and the fixation of water vapor. The second valve 33 is arranged between the condenser tube 32 and the catalytic reduction assembly 4, and is used to control the flow of gas to the catalytic reduction assembly 4. The use of valves and cold traps achieves precise control of the flow of gas and the purification process.

[0059] The catalytic reduction assembly 4 is the place where graphite is generated, and includes a catalytic tube 41 and a reduction tube 42. The catalytic tube 41 is placed with a catalyst (such as iron powder), and the reduction tube 42 is placed with a reducing agent (such as a mixed agent of zinc and titanium dihydride). The catalytic tube 41 is placed at the bottom of the reduction tube 42, which is conducive to the full contact of the gas with the catalyst and the reducing agent.

[0060] The vacuum pump 5 is connected to the catalytic reduction assembly 4, and is used to pump the entire system pipeline into a vacuum during the preparation of the graphite sample, and completely remove the pollution of air carbon dioxide and other impurities.

[0061] Specifically, the liquid fuel graphitization device 100 performs the following process for sample preparation of the liquid fuel: 60-80 mg of copper oxide is placed in the oxidant tube 22, and after 5 μL of the liquid fuel is added to the sample tube 21, the sample tube 21 is placed upside down at the bottom of the oxidant tube 22. 60-70 mg of zinc and 20-30 mg of titanium dihydride are placed in the reduction tube 42, and after 6-10 mg of iron is placed in the catalytic tube 41, the catalytic tube 41 is placed at the bottom of the reduction tube 42. Liquid nitrogen cold traps are sleeved at the bottom of the oxidation assembly 2 to fix the liquid fuel, the first valve 31, the second valve 33, and the vacuum pump 5 are opened to remove the impurities in the pipeline system, then the liquid nitrogen cold traps are replaced with -76°C liquid nitrogen-ethanol mixed cold traps, and the impurities previously fixed by the liquid nitrogen cold traps are released while the liquid fuel is fixed. The first valve 31 is closed, the electric heating furnace 1 is moved below the oxidation assembly 2 to heat the oxidation assembly 2, and the temperature is maintained at 900°C for 7 hours. After the oxidation is completed, the second valve 33 is closed, the first valve 31 is opened, and the gas generated by the oxidation reaction in the oxidation assembly 2 is released. Liquid nitrogen cold traps are sleeved below the condensation tube 32, the second valve 33 is opened to remove the impurities, the second valve 33 is closed, the liquid nitrogen-ethanol mixed cold traps at -65°C are replaced below the condensation tube 32 to fix the water vapor, and the purified sample carbon dioxide gas is released. The vacuum pump 5 is closed, the second valve 33 is opened, liquid nitrogen cold traps are sleeved below the catalytic reduction assembly 4, the purified sample carbon dioxide gas is captured into the catalytic reduction assembly 4, the second valve 33 is closed, the electric heating furnace 1 is moved below the catalytic reduction assembly 4 to heat the catalytic reduction assembly 4, the temperature is maintained at 500°C for 4 hours, then the temperature is increased to 550°C and maintained for 3 hours, and finally the sealed sample carbon dioxide gas is reduced to a graphite sample.

[0062] The present embodiment integrates a movable program-controlled electric heating furnace 1, an oxidation assembly 2 designed with an inverted sample tube 21, a transfer and purification assembly 3 based on the precise cooperation of valves and multi-temperature zone cold traps, and a catalytic reduction assembly 4 including a catalytic tube 41 and a reduction tube 42, to construct a compact closed liquid fuel graphitization device 100. Through the function partitioning of the assemblies and the sequential control of the process, the device realizes the continuous and automated completion of the liquid fuel oxidation, gas purification, and graphite deposition reduction processes in a single closed system without disassembling the assemblies in the middle, thereby greatly reducing the risk of air carbon dioxide pollution caused by manual operation, simplifying the operation process, and providing a hardware guarantee for obtaining high-purity graphite samples and ultimately realizing the high-precision and high-reliability detection of the bio-based component proportion of the liquid fuel.

[0063] The above is only an optional embodiment of the present application and does not limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for detecting a bio-based content ratio of a liquid fuel, characterized by, Includes the following steps: Graphite sample preparation steps: Prepare graphite samples from liquid fuel; 14 C Test procedure: The graphite sample is tested with an accelerator mass spectrometer to obtain the 14 C activity; Bio-based content fraction calculation step: the bio-based content fraction in the liquid fuel is calculated from the C activity of the graphite sample 14 C activity of the graphite sample.

2. The method for detecting the proportion of bio-based components in liquid fuels as described in claim 1, characterized in that, In the graphite sample preparation step, a liquid fuel graphitization apparatus is used to prepare the liquid fuel into the graphite sample. The liquid fuel graphitization device includes: Oxidation components; The condenser tube can be connected to the oxidation assembly; The catalytic reduction component can be connected to the condenser tube; A vacuum pump is available for connection to the catalytic reduction assembly, as well as to the oxidation assembly and the condenser. The graphite sample preparation steps include the following steps: Drug loading steps: Liquid fuel and the oxidant are placed in the oxidation assembly, and the reducing agent and catalyst are placed in the catalytic reduction assembly; Sample oxidation steps: The oxidation component is cooled in stages to fix the liquid fuel, the oxidation component is connected to the vacuum pump to remove impurities, and then the oxidation component is heated to oxidize the carbon in the liquid fuel into carbon dioxide gas. Transfer purification step: The gas obtained through the sample oxidation step is introduced into the condenser, the condenser is cooled to fix carbon dioxide gas, the condenser is connected to the vacuum pump to remove impurities, the cooling temperature is increased to fix water vapor, and carbon dioxide gas is released at the same time. Catalytic reduction step: The purified carbon dioxide gas obtained through the transfer purification step is introduced into the catalytic reduction component, and the catalytic reduction component is heated to reduce the carbon dioxide gas into the graphite sample.

3. The method of claim 2, wherein the liquid fuel bio-based content is determined by the method of ASTM D6866-10. In the sample oxidation step The liquid fuel is fixed at a first cooling temperature, while the first impurity gas is extracted. The first cooling temperature is then increased to a second cooling temperature to maintain the liquid fuel at the second cooling temperature and release the second impurity gas, which was fixed at the first cooling temperature, including carbon dioxide from the air. The first cooling temperature is below -60℃, and the second cooling temperature range is -78℃ to -60℃.

4. The method of claim 2, wherein the liquid fuel bio-based content is determined by the method of ASTM D6866-10. In the transfer and purification step The gas obtained through the sample oxidation step is fixed at a third cooling temperature, while a third impurity gas is evacuated. The third cooling temperature is then increased to a fourth cooling temperature to maintain the water vapor at the fourth cooling temperature and release the carbon dioxide gas fixed at the third cooling temperature. The third cooling temperature is below -78.5℃, and the fourth cooling temperature ranges from -60℃ to -10℃.

5. The method of claim 2, wherein the liquid fuel bio-based content is determined by the method of ASTM D6866-10. In the sample oxidation step, the temperature range of heating the oxidation component is 700℃~900℃, and the time range is 2~7 hours; in the catalytic reduction step, the temperature range of heating the catalytic reduction component is 450℃~650℃, and the time range is 4~7 hours.

6. The method of claim 1-5, wherein The liquid fuel is a mixture of bio-based fuel and fossil-based fuel.

7. A device for detecting the proportion of a bio-based component in a liquid fuel, characterized in that it comprises: This method is applicable to any of the liquid fuel bio-based component proportion detection methods as described in claims 1-6, including a liquid fuel graphitization device and an accelerator mass spectrometer.

8. The liquid fuel bio-based component proportion detection device as described in claim 7, characterized in that, The liquid fuel graphitization device includes: An electric heating furnace is used to heat the oxidation and catalytic reduction components; Oxidation assembly, including sample tube and oxidant tube; A transfer purification component is connected to the oxidation component, and the transfer purification component includes a first valve, a condenser, and a second valve. A catalytic reduction assembly is connected to the transfer purification assembly, and the catalytic reduction assembly includes a catalytic tube and a reduction tube; A vacuum pump is connected to the catalytic reduction assembly.

9. The liquid fuel bio-based component proportion detection device as described in claim 8, characterized in that, The first valve is disposed between the oxidation component and the condenser, and the second valve is disposed between the condenser and the catalytic reduction component.

10. The liquid fuel bio-based component proportion detection device as described in claims 7-9, characterized in that, The device is a closed system.

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