An online monitoring method for the amount of available hydrogen in an organic liquid hydrogen storage material

Abstract

The present invention discloses an online monitoring method for the amount of available hydrogen in an organic liquid hydrogen storage material, comprising the following steps: S1, the temperature t x , refractive index n x and density ρ x Determination of available hydrogen in organic liquids, S2, available hydrogen and refractive index n x and density ρ x Establishment of standard curve, S4, online monitoring of available hydrogen amount of unknown organic liquid hydrogen storage material; the present invention establishes for the first time an online real-time monitoring method for available hydrogen amount of organic liquid hydrogen storage material, the method is easy to operate and low in cost, can be directly arranged on the pipeline of hydrogenation, dehydrogenation test and production equipment of organic liquid hydrogen storage material, and can also be arranged in the delivery pipeline of filling station to realize online monitoring of available hydrogen amount of hydrogen storage material; it can be promoted and applied to monitoring scenarios of available hydrogen amount of various hydrogen storage materials; the online real-time monitoring method in the present invention is suitable for large-scale and continuous monitoring, the method is fast and has wide applicability.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogen storage, and in particular relates to an online monitoring method for the available hydrogen amount of an organic liquid hydrogen storage material. Background Art

[0002] Hydrogen is an efficient and clean energy source, and its storage and transportation are key issues affecting the large-scale application of hydrogen energy. Common hydrogen storage methods include high-pressure gaseous hydrogen storage, liquid hydrogen storage, metal hydrogen storage, and organic liquid hydride hydrogen storage. Organic liquid hydrogen storage is to fix hydrogen to hydrocarbons, alkynes, and certain unsaturated aromatic organic compounds through hydrogenation reactions, and form stable hydrogenated organic compound liquids, such as benzene-cyclohexane, methylbenzene-methylcyclohexane, etc. When it reaches the user end, the hydrogen-carrying organic liquid compound releases hydrogen through a catalytic reaction. The dehydrogenated organic liquid can continue to undergo hydrogenation reactions to store hydrogen, and then dehydrogenate again to release hydrogen for recycling. Organic liquid hydrogen storage materials have a high hydrogen storage mass and volume hydrogen storage density, and are liquid at room temperature and pressure. They can be stored and transported at room temperature and pressure like gasoline and diesel. Using existing gasoline and diesel transportation methods and gas station facilities, the storage and transportation process can be made safe and efficient, and the cost of large-scale utilization of hydrogen energy can be greatly reduced. The theoretical hydrogen storage mass of different organic liquid hydrogen storage materials is shown in Table 1 below:

[0003] Table 1 Theoretical hydrogen storage mass of different organic liquid hydrogen storage materials

[0004]

[0005] The actual amount of hydrogen available in organic liquid hydrogen storage materials is not the theoretical amount of hydrogen storage. During the hydrogenation and dehydrogenation reactions of the test or production of organic liquid hydrogen storage materials, the focus will be on monitoring the changes in the available hydrogen storage capacity of the material, and continuous monitoring is also required to determine the completion of the hydrogenation or dehydrogenation reaction of the material. In the application scenarios of the recycling of organic liquid hydrogen storage materials and refueling in hydrogen refueling stations, the available hydrogen capacity of liquid hydrogen storage materials is also an important economic evaluation indicator.

[0006] The existing method for detecting the hydrogen storage density of organic liquid hydrogen storage materials is the group standard T / CAB1038 2020 "Drainage Method for Measuring the Hydrogen Storage Density of Hydrogenated Liquid Organic Hydrogen Storage Carriers". This method needs to be carried out in a certain dehydrogenation reaction device and under certain reaction conditions. The principle is to collect the hydrogen released by the organic liquid material through catalytic dehydrogenation by drainage, and after measurement, convert it into the ratio of the mass of hydrogen to the mass of the organic liquid hydrogen storage material as the available hydrogen storage capacity; however, this method requires sampling for offline testing in the laboratory, and the single detection time is long, the operation is complicated and cumbersome, and continuous online monitoring is not possible. It cannot be popularized and applied in continuous production and testing processes, as well as in the application scenarios of filling stations; therefore, it is necessary to develop an accurate and online method for monitoring the available hydrogen content of organic liquid hydrogen storage materials. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an online monitoring method for the amount of available hydrogen in an organic liquid hydrogen storage material. The existing detection method needs to take samples for offline detection in the laboratory, and the single detection time is long, the operation is complicated and cumbersome, and continuous online monitoring cannot be performed. In the continuous production and test process, as well as in the application scenario of the filling station, it cannot be popularized and applied.

[0008] In order to solve the above problems existing in the prior art, the present invention is implemented through the following technical solutions:

[0009] An online monitoring method for the amount of available hydrogen in an organic liquid hydrogen storage material comprises the following steps:

[0010] S1, sample temperature t x , refractive index n x and density ρ x Determination: Turn on the infusion pump of the monitoring device to allow the organic liquid in the organic liquid hydrogen storage material to flow through the detector, and read and record the temperature t measured by the detector in the online monitoring device. x Value, refractive index n x Value and density ρ x Values, while reading the values, collect the organic liquids flowing out of the detectors respectively;

[0011] S2. Detection of the amount of available hydrogen in the organic liquid: pre-treating the organic liquid obtained in step S1, and then analyzing it using GC-MS to obtain the amount of available hydrogen in the organic liquid;

[0012] S3, available hydrogen volume and refractive index n x and density ρ xEstablishment of standard curve: According to the available hydrogen amount of organic liquid and the refractive index at standard temperature, establish the standard curve equation of available hydrogen amount and refractive index; according to the available hydrogen amount of organic liquid and the density at standard temperature, establish the standard curve equation of available hydrogen amount and density;

[0013] S4. Online monitoring of the available hydrogen amount of unknown organic liquid hydrogen storage materials: real-time reading of the temperature t measured by the detector in the online monitoring device x Value, refractive index n x Value and density ρ x The value is obtained by the curve in step S3 to obtain the real-time available hydrogen amount of the organic liquid, thereby realizing online real-time monitoring of the available hydrogen amount of the unknown organic liquid hydrogen storage material.

[0014] Furthermore, step S1 also includes measuring the refractive index n of the sample. x and density ρ x The step of performing calibration at a standard temperature, specifically, selecting a standard temperature, and performing calibration on the refractive index n obtained in step S1 x Value and density ρ x The value is corrected. At the same time, in step S3, the amount of available hydrogen and the corrected refractive index n x and density ρ x Establish a standard curve.

[0015] Furthermore, the conversion formula for refractive index at 20°C standard temperature is: n 20 =n x +0.0003×(t x -20), where n 20 is the refractive index at 20°C, n x The ambient temperature is t x The refractive index at 20℃ and the density ρ at standard temperature x Conversion formula: ρ 20 =ρ x +0.000008×(t x -20), where ρ 20 is the density at 20°C, ρ x The ambient temperature is t x The density at time.

[0016] Furthermore, the standard curve equation of available hydrogen and refractive index is W = 57.524n 20 2 -216.18n 20 +200.26, R 2 =0.9993, where 1.3100≤n 20≤1.5570; the standard curve equation of available hydrogen volume and density is W = -40.845ρ 20 +44.047, R 2 =0.9889, where n 20 >1.5570 or n 20 <1.310.

[0017] Furthermore, in step S1, the detector includes an online thermometer, an online refractometer and an online densitometer.

[0018] Furthermore, the refractive index measurement range of the online refractometer is 1.310-1.557.

[0019] Furthermore, the density measurement range of the online densitometer is 0.0000-2.0000 g / cm 3 .

[0020] Furthermore, in step S2, the specific method for pre-treating the organic liquid is as follows: aspirate the organic liquid into a volumetric flask, add an organic solvent, vortex mix, ultrasonicate for 5-10 minutes, then adjust the volume, and filter through a 0.22 μm filter membrane. The organic solvent is one of acetone, N,N-dimethylformamide, n-hexane and acetonitrile.

[0021] Further, in step S2, the chromatographic conditions of the GC-MS are as follows: the gas chromatograph is an Agilent 7890B system, column temperature: starting at 60°C, increasing at 30°C / min to 180°C, then increasing at 4°C / min to 250°C, and maintaining for 2.5 min, carrier gas: nitrogen, carrier gas flow rate: 0.8 mL / min; injection volume: 0.3 μL; chromatographic column model: DB-17MS or DB-5MS, 30m×0.25mm, 0.25μm or 60m×0.25mm, 0.25μm; the mass spectrometry conditions of the GC-MS are as follows: the mass spectrometer is an Agilent 5977A system, mass spectrometry ionization mode: EI ion source; mass scanning range: 40amu-350amu; detection mode: transmission line: 280°C; quadrupole temperature: 150°C; ion source temperature: 230°C; voltage: 70ev.

[0022] Furthermore, in step S2, the calculation formula for the amount of available hydrogen in the organic liquid is as follows:

[0023]

[0024] Wherein, w-represents the mass percentage of available hydrogen in the organic liquid hydrogen storage material; ω1-represents the area percentage of the organic liquid hydrogen storage material after adding 2H to the initial molecular weight in the mass spectrum; ω2-represents the area percentage of the organic liquid hydrogen storage material after adding 4H to the initial molecular weight in the mass spectrum; ω2n - represents the area percentage of the organic liquid hydrogen storage material in the mass spectrum after adding n×2H to the initial molecular weight; M 2H - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after 2H; M 4H - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after 4H; M 2nH - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after n×2H.

[0025] In the present invention, according to the different refractive indexes and densities of different organic liquid hydrogen storage materials after hydrogenation or dehydrogenation, the relationship between the refractive index, density and the available hydrogen content of the organic liquid hydrogen storage material is found, thereby determining the standard curve relationship between the available hydrogen content of the organic liquid hydrogen storage material and the refractive index and density within a certain range. According to the above standard curve relationship, the temperature t measured by the detector in the online monitoring device is read online in real time. x Value, refractive index n x Value and density ρ x The value is corrected to obtain the real-time available hydrogen amount of the organic liquid, thereby realizing the online real-time monitoring of the available hydrogen amount of the unknown organic liquid hydrogen storage material.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1) The present invention establishes for the first time an online real-time monitoring method for the available hydrogen amount of an organic liquid hydrogen storage material. The method is simple to operate and low in cost. It can be directly set on the pipeline of an organic liquid hydrogen storage material hydrogenation, dehydrogenation test and production device, or can be set in a delivery pipeline of a filling station to achieve online monitoring of the available hydrogen amount of the hydrogen storage material. It can be promoted and applied to the monitoring scenarios of the available hydrogen amount of various hydrogen storage materials.

[0028] 2) The online real-time monitoring method of the present invention is suitable for large-scale, continuous monitoring. The method is fast and widely applicable, and the reliability of the monitoring results is more than 95%. Therefore, it has certain application prospects in monitoring the amount of available hydrogen in organic liquid hydrogen storage materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a flow chart of the online real-time monitoring method of the present invention;

[0031] Figure 2is the standard curve equation of the available hydrogen amount and the refractive index at standard temperature of the present invention;

[0032] Figure 3 It is the standard curve equation of the available hydrogen amount and density at standard temperature in the present invention. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Unless otherwise specified, the reagents and equipment used in the present invention are all commercially available.

[0035] Example 1

[0036] An online monitoring method for the amount of available hydrogen in an organic liquid hydrogen storage material comprises the following steps:

[0037] S1, temperature t of 20 samples x , refractive index n x and density ρ x Determination: When the hydrogenation or dehydrogenation reaction of the organic liquid hydrogen storage material begins, connect the online monitoring device to the monitoring point, then turn on the infusion pump of the monitoring device to make the organic liquid flow through the detector, read and record the temperature t measured by the detector in the online monitoring device x Value, refractive index n x Value and density ρ x The detector includes an online thermometer, an online refractometer and an online density meter. The online thermometer is used to record the ambient temperature. The online refractometer (commercially available online refractometer or online refractive index sensor) has a refractive index measurement range of 1.310-1.557, and the online density meter has a density measurement range of 0.0000-2.0000 g / cm 3 ; While reading the value, collect 20 portions of organic liquid flowing out of the detector;

[0038] S2, refractive index n of 20 samples x and density ρ x Calibration at standard temperature: Select the standard temperature as 20°C and the refractive index n obtained in step S1 x Value and density ρ x The conversion formula of refractive index at standard temperature is: n 20 =n x +0.0003×(t x -20), where n20 is the refractive index at 20°C, n x The ambient temperature is t x The refractive index at standard temperature is ρ x Conversion formula: ρ 20 =ρ x +0.000008× (t x -20), where ρ 20 is the density at 20°C, ρ x The ambient temperature is t x Density at time

[0039] S3. Detection of available hydrogen content of 20 samples of organic liquid: The organic liquid obtained in step S1 is pretreated. The specific method of pretreatment of the organic liquid is as follows: 10-50 μL of the organic liquid is drawn into a 10 mL volumetric flask, an organic solvent is added, vortexed and mixed, and the volume is fixed after ultrasonication for 5-10 min, and then filtered through a 0.22 μm filter membrane. The organic solvent is one of acetone, N,N-dimethylformamide, n-hexane and acetonitrile; GC-MS is then used for analysis. The chromatographic conditions of the GC-MS are as follows: the gas chromatograph is an Agilent 7890B system, and the column temperature is: starting at 60°C, increasing by 30°C / min to 180°C, and then increasing by 4°C / min Increase to 250℃, maintain for 2.5min, carrier gas: nitrogen, carrier gas flow rate: 0.8mL / min; injection volume: 0.3μL; chromatographic column model: DB-17MS or DB-5MS, 30m×0.25mm, 0.25μm or 60m×0.25mm, 0.25μm; the mass spectrometry conditions of the GC-MS are as follows: the mass spectrometer is an Agilent 5977A system, the mass spectrometry ionization mode: EI ion source; mass scanning range: 40amu-350amu; detection mode: transmission line: 280℃; quadrupole temperature: 150℃; ion source temperature: 230℃; voltage: 70ev; the amount of available hydrogen in the organic liquid is obtained, and the calculation formula for the amount of available hydrogen in the organic liquid is as follows:

[0040]

[0041] Wherein, w-represents the mass percentage of available hydrogen in the organic liquid hydrogen storage material; ω1-represents the area percentage of the organic liquid hydrogen storage material after adding 2H to the initial molecular weight in the mass spectrum; ω2-represents the area percentage of the organic liquid hydrogen storage material after adding 4H to the initial molecular weight in the mass spectrum; ω 2n - represents the area percentage of the organic liquid hydrogen storage material in the mass spectrum after adding n×2H to the initial molecular weight; M 2H - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after 2H; M 4H- represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after 4H; M 2nH - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after n×2H;

[0042] The temperature t of the 20 samples x , refractive index n x and density ρ x and its correction value, the results of the available hydrogen content in the organic liquid measured by the 20 samples are shown in Table 2:

[0043] Table 2 Temperature t of 20 samples x , refractive index n x , density ρ x , and its correction value and available hydrogen amount result

[0044]

[0045]

[0046] S4, the amount of hydrogen available for 20 samples and the refractive index after correction n x and density ρ x Establishment of standard curve: According to the available hydrogen amount of organic liquid and the refractive index at standard temperature, establish the standard curve equation of available hydrogen amount and refractive index; the standard curve equation is W = 57.524n x 2 -216.18n x +200.26, R 2 =0.9993, where 1.3100≤n x ≤1.5570; according to the available hydrogen amount of the organic liquid and the density at standard temperature, a standard curve equation of available hydrogen amount and density is established, and the standard curve equation is W = -40.845ρ x +44.047, R 2 =0.9889, where n x >1.5570 or n x <1.310;

[0047] S5. Online monitoring of the available hydrogen amount of unknown organic liquid hydrogen storage materials: real-time reading of the temperature t measured by the detector in the online monitoring device x Value, refractive index n x Value and density ρ x The value is corrected by the method in step S2, and the real-time available hydrogen amount of the organic liquid is obtained through the curve in step S4, thereby realizing online real-time monitoring of the available hydrogen amount of the unknown organic liquid hydrogen storage material.

[0048] In this monitoring method, 12 groups of unknown samples were selected for real-time monitoring and measurement, and the available hydrogen amounts of the 12 groups of samples were determined by GC-MS to further verify the reliability of the real-time monitoring method of the present invention. The results are shown in Table 3:

[0049] Table 3 Comparison of the results of the real-time monitoring measurement of the present invention and the GC-MS method for measuring the amount of available hydrogen

[0050]

[0051] It can be seen from the results in Table 3 that the available hydrogen content of the samples measured by real-time monitoring of the present invention is almost the same as the available hydrogen content of the samples measured by the GC-MS method, indicating that the real-time monitoring results of the present invention are reliable and can be quickly used for online real-time monitoring of the available hydrogen content of unknown organic liquid hydrogen storage materials.

[0052] The above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention.

Claims

1. An online monitoring method for the amount of available hydrogen in an organic liquid hydrogen storage material, characterized in that: The steps include: S1, sample temperature t x , refractive index n x and density ρ x Determination: Turn on the infusion pump of the monitoring device to allow the organic liquid in the organic liquid hydrogen storage material to flow through the detector, and read and record the temperature t measured by the detector in the online monitoring device. x Value, refractive index n x Value and density ρ x Values, while reading the values, collect the organic liquids flowing out of the detectors respectively; S2. Detection of the amount of available hydrogen in the organic liquid: pre-treating the organic liquid obtained in step S1, and then analyzing it using GC-MS to obtain the amount of available hydrogen in the organic liquid; S3, available hydrogen volume and refractive index n x and density ρ x Establishment of standard curve: According to the available hydrogen amount of organic liquid and the refractive index at standard temperature, establish the standard curve equation of available hydrogen amount and refractive index; according to the available hydrogen amount of organic liquid and the density at standard temperature, establish the standard curve equation of available hydrogen amount and density; S4. Online monitoring of the available hydrogen amount of unknown organic liquid hydrogen storage materials: real-time reading of the temperature t measured by the detector in the online monitoring device x Value, refractive index n x Value and density ρ x The value is obtained by using the curve in step S3 to obtain the real-time available hydrogen amount of the organic liquid, thereby realizing online real-time monitoring of the available hydrogen amount of the unknown organic liquid hydrogen storage material; Step S1 also includes measuring the refractive index n of the sample. x and density ρ x The step of performing calibration at a standard temperature of 20°C is to calibrate the refractive index n obtained in step S1 at a standard temperature of 20°C. x Value and density ρ x The value is corrected. At the same time, in step S3, the amount of available hydrogen and the corrected refractive index n x and density ρ x Establish a standard curve; the conversion formula for refractive index at 20℃ standard temperature is: n 20 =n x +0.0003×(t x -20), where n 20 is the refractive index at 20°C, n x The ambient temperature is t x The refractive index at 20℃ and the density ρ at standard temperature x Conversion formula: ρ 20 =ρ x +0.000008×(t x -20), where ρ 20 is the density at 20°C, ρ x The ambient temperature is t x The density at time.

2. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 1, characterized in that: The standard curve equation of available hydrogen and refractive index is W=57.524n 20 2 -216.18n 20 +200.26, R 2 =0.9993, where 1.3100≤n 20 ≤1.5570; the standard curve equation of available hydrogen volume and density is W = -40.845ρ 20 +44.047, R 2 =0.9889, where n 20 >1.5570 or n 20 <1.

310.

3. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 1, characterized in that: In step S1, the detector includes an online thermometer, an online refractometer and an online densitometer.

4. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 3, characterized in that: The refractive index measuring range of the online refractometer is 1.310-1.

557.

5. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 3, characterized in that: The density measurement range of the online densitometer is 0.0000-2.0000 g / cm 3 .

6. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 1, characterized in that: In step S2, the specific method for pre-treating the organic liquid is as follows: aspirate the organic liquid into a volumetric flask, add an organic solvent, vortex mix, ultrasonicate for 5-10 minutes, then adjust the volume, and filter through a 0.22 μm filter membrane. The organic solvent is one of acetone, N,N-dimethylformamide, n-hexane and acetonitrile.

7. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 1, characterized in that: In step S2, the chromatographic conditions of the GC-MS are as follows: the gas chromatograph is an Agilent 7890B system, column temperature: starting at 60°C, increasing at 30°C / min to 180°C, then increasing at 4°C / min to 250°C, maintaining for 2.5 min, carrier gas: nitrogen, carrier gas flow rate: 0.8 mL / min; injection volume: 0.3 μL; chromatographic column model: DB-17MS or DB-5MS, 30m×0.25mm, 0.25μm or 60m×0.25mm, 0.25μm; the mass spectrometry conditions of the GC-MS are as follows: the mass spectrometer is an Agilent 5977A system, mass spectrometry ionization mode: EI ion source; mass scanning range: 40amu-350amu; detection mode: transmission line: 280°C; quadrupole temperature: 150°C; ion source temperature: 230°C; voltage: 70ev.

8. The method for online monitoring of the amount of available hydrogen in an organic liquid hydrogen storage material according to claim 1, characterized in that: In step S2, the calculation formula for the amount of available hydrogen in the organic liquid is as follows: ， Wherein, w-represents the mass percentage of available hydrogen in the organic liquid hydrogen storage material; ω1-represents the area percentage of the organic liquid hydrogen storage material after adding 2H to the initial molecular weight in the mass spectrum; ω2-represents the area percentage of the organic liquid hydrogen storage material after adding 4H to the initial molecular weight in the mass spectrum; ω 2n - represents the area percentage of the organic liquid hydrogen storage material in the mass spectrum after adding n×2H to the initial molecular weight; M 2H - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after 2H; M 4H - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after 4H; M 2nH - represents the initial molecular weight of the organic liquid hydrogen storage material plus the molecular weight after n×2H.

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