Method for determining trace sulfide in hydrogen for fuel cell based on electron cold trap preconcentration

Abstract

The invention belongs to the technical field of detection of sulfides in hydrogen for fuel cells, and provides a method for determining trace sulfides in hydrogen for fuel cells based on electron cold trap preconcentration. The method comprises the following steps: carrying out electron cold trap pre-concentration on a to-be-detected hydrogen sample for the fuel cell to obtain a pre-concentrated sample; sequentially performing chromatographic separation and mass spectrometry detection on the pre-concentrated sample to determine the type and concentration of the sulfide in the hydrogen sample for the fuel cell so as to complete the determination of the trace sulfide in the hydrogen for the fuel cell. The method disclosed by the invention has the advantages of high sensitivity, high accuracy, high repeatability, simplicity and convenience in operation and wide application, and is of great significance for improving the performance and the safety of the fuel cell.

Description

Technical Field

[0001] The present invention relates to the technical field of sulfide detection in hydrogen for fuel cells, and in particular to a method for determining trace sulfide in hydrogen for fuel cells based on electronic cold trap pre-concentration. Background Art

[0002] As a clean and efficient energy conversion technology, the performance and life of fuel cells are largely affected by the impurities in the fuel gas, especially the sulfide content. Sulfide is a type of substance that is highly toxic to fuel cell catalysts. Even at extremely low concentrations, it can cause the catalyst activity to decrease, thus affecting the performance and life of the cell. Therefore, accurate determination of sulfide in hydrogen for fuel cells is crucial to ensure the reliability and economy of fuel cells.

[0003] Pre-concentration technology is to enrich the substance to be tested in the sample so that its concentration reaches the detection range of the detection instrument, thereby realizing the detection of extremely low concentration substances. In the detection of sulfides in hydrogen for fuel cells, traditional pre-concentration technologies mainly include liquid nitrogen cold trap pre-concentration technology. This technology uses the extremely low temperature (about -196°C) provided by liquid nitrogen to capture sulfides in gas samples, and then achieves desorption of substances by rapid heating, so as to carry out subsequent analysis and detection. At present, liquid nitrogen cold trap pre-concentration technology has been widely used in environmental monitoring, industrial process control and other fields. In the detection of sulfides in hydrogen for fuel cells, liquid nitrogen cold trap pre-concentration technology is usually combined with gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS) technology to achieve high-sensitivity detection of sulfides. These technologies can provide ppb-level detection limits to meet the strict requirements of fuel cells for hydrogen purity.

[0004] Although the liquid nitrogen cold trap pre-concentration technology has shown certain advantages in sulfide detection, it still has some shortcomings. First, the operation of the liquid nitrogen cold trap requires a large amount of liquid nitrogen, which not only increases the operating cost, but also the storage and transportation of liquid nitrogen also pose certain safety hazards. Secondly, the low-temperature operating environment of the liquid nitrogen cold trap has high requirements on the thermal insulation performance of the equipment, which increases the difficulty of equipment design and manufacturing. In addition, the maintenance and operation of the liquid nitrogen cold trap are relatively complicated and require professional personnel to operate, which limits its application in rapid on-site detection and low-cost operation. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration. The method uses an electronic cold trap to replace the traditional liquid nitrogen cold trap, avoiding the use of liquid nitrogen, reducing operating costs and safety risks. The electronic cold trap pre-concentration technology provides a stable low-temperature environment through electronic refrigeration elements, achieves efficient enrichment and desorption of sulfides, and improves the sensitivity and accuracy of detection. In addition, the electronic cold trap pre-concentration technology is simple to operate and easy to maintain, suitable for rapid on-site detection and low-cost operation, and has broad application prospects.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration, comprising the following steps:

[0008] Pre-concentrating the hydrogen sample of the fuel cell to be tested by an electronic cold trap to obtain a pre-concentrated sample;

[0009] The pre-concentrated samples are sequentially subjected to chromatographic separation and mass spectrometry detection to determine the type and concentration of sulfides in the hydrogen sample for fuel cells, thereby completing the determination of trace sulfides in hydrogen for fuel cells.

[0010] Preferably, the conditions for electron cold trap pre-concentration are as follows: the trapping temperature is -45 to -55°C, the desorption temperature is 145 to 155°C, and the transmission line temperature is 95 to 105°C.

[0011] Preferably, the chromatographic separation uses a DB-Sulfur chromatographic column, the length of the DB-Sulfur chromatographic column is 40 to 70 m, the inner diameter is 0.32 to 0.53 mm, and the membrane thickness is 0.75 to 4.3 μm.

[0012] Preferably, the column temperature program for chromatographic separation is: maintain at 30-40°C for 5-7 min; then increase the temperature to 145-155°C at a heating rate of 3-7°C / min, maintain for 8-12 min; finally increase the temperature to 245-255°C at a heating rate of 8-12°C / min.

[0013] Preferably, the carrier gas for chromatographic separation is helium, and the carrier gas flow rate for chromatographic separation is 0.8-1.2 mL / min.

[0014] Preferably, the ion source concentration of mass spectrometry detection is 225-235° C., the quadrupole temperature of mass spectrometry detection is 145-155° C., and the solvent delay time of mass spectrometry detection is 2-4 min.

[0015] Preferably, the scanning range of mass spectrometry detection is 33-400 amu, and the scanning mode of mass spectrometry detection is full scan mode.

[0016] The beneficial effects of the present invention are:

[0017] The present invention provides a method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration, comprising the following steps: subjecting a hydrogen sample for fuel cells to be tested to electronic cold trap pre-concentration to obtain a pre-concentrated sample; subjecting the pre-concentrated sample to chromatographic separation and mass spectrometry detection in sequence to determine the type and concentration of sulfides in the hydrogen sample for fuel cells, and completing the determination of trace sulfides in hydrogen for fuel cells. The present invention uses electronic cold trap pre-concentration technology to concentrate the sample, thereby improving the detection sensitivity of sulfides, and the detection limit can reach the ppb level; at the same time, the present invention uses optimized gas chromatography and mass spectrometry conditions to achieve efficient separation and accurate quantification of sulfides, with a relative standard deviation (RSD) of less than 5%; under the specific detection method and conditions of the present invention, the correctness bias is less than 20%, and the method has good repeatability. The method of the present invention is simple to operate, suitable for online and offline detection of sulfides in hydrogen for fuel cells, suitable for rapid on-site detection, and can be extended to other fields requiring high-sensitivity detection of sulfides. In summary, the method of the present invention has the advantages of high sensitivity, high accuracy, high repeatability, simple operation and wide application, and is of great significance for improving the performance and safety of fuel cells. DETAILED DESCRIPTION

[0018] The present invention provides a method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration, comprising the following steps:

[0019] Pre-concentrating the hydrogen sample of the fuel cell to be tested by an electronic cold trap to obtain a pre-concentrated sample;

[0020] The pre-concentrated samples are sequentially subjected to chromatographic separation and mass spectrometry detection to determine the type and concentration of sulfides in the hydrogen sample for fuel cells, thereby completing the determination of trace sulfides in hydrogen for fuel cells.

[0021] In the present invention, a conventional dedicated sampling device in the art is used to collect hydrogen samples for fuel cells to ensure the representativeness and integrity of the samples, which are used as hydrogen samples for fuel cells to be tested.

[0022] In the present invention, electron cold trap preconcentration is carried out in an electron cold trap preconcentration system, and the conditions for electron cold trap preconcentration are as follows: the capture temperature is preferably -45 to -55°C, more preferably -47 to -53°C, and more preferably -50 to -51°C; the desorption temperature is preferably 145 to 155°C, more preferably 147 to 153°C, and more preferably 150 to 151°C; the transmission line temperature is preferably 95 to 105°C, more preferably 97 to 103°C, and more preferably 100 to 101°C.

[0023] In the present invention, chromatographic separation is carried out in a gas chromatograph, and the chromatographic separation adopts a DB-Sulfur chromatographic column, the length of the DB-Sulfur chromatographic column is 40 to 70 m, preferably 43 to 68 m, more preferably 45 to 65 m, and more preferably 48 to 62 m; the inner diameter of the DB-Sulfur chromatographic column is 0.32 to 0.53 mm, preferably 0.35 to 0.50 mm, more preferably 0.38 to 0.47 mm, more preferably 0.40 to 0.45 mm; the film thickness of the DB-Sulfur chromatographic column is 0.75 to 4.3 μm, preferably 1.0 to 4.0 μm, more preferably 1.5 to 3.5 μm, and more preferably 2 to 3 μm.

[0024] In the present invention, the column temperature program for chromatographic separation is preferably: maintaining at 30-40°C for 5-7min; then heating to 145-155°C at a heating rate of 3-7°C / min, maintaining for 8-12min; finally heating to 245-255°C at 8-12°C / min; further preferably: maintaining at 32-38°C for 5.5-6.5min; then heating to 147-153°C at a heating rate of 4-6°C / min, maintaining for 9-11min; finally heating to 247-253°C at 9-11°C / min; more preferably: maintaining at 35-36°C for 5.8-6min; then heating to 150-151°C at a heating rate of 4.5-5°C / min, maintaining for 9.5-10min; finally heating to 250-251°C at 9.5-10°C / min.

[0025] In the present invention, the carrier gas for chromatographic separation is preferably helium, and the carrier gas flow rate for chromatographic separation is preferably 0.8 to 1.2 mL / min, more preferably 0.9 to 1.1 mL / min, and even more preferably 0.95 to 1.0 mL / min.

[0026] In the present invention, mass spectrometry detection is carried out in a mass spectrometer, and the ion source concentration of mass spectrometry detection is preferably 225-235°C, more preferably 227-233°C, and more preferably 220-231°C; the quadrupole temperature of mass spectrometry detection is preferably 145-155°C, more preferably 147-153°C, and more preferably 150-151°C; the solvent delay time of mass spectrometry detection is preferably 2-4 min, more preferably 2.5-3.5 min, and more preferably 3-3.1 min.

[0027] In the present invention, the scanning range of mass spectrometry detection is preferably 33 to 400 amu, more preferably 50 to 380 amu, and even more preferably 70 to 360 amu; the scanning mode of mass spectrometry detection is preferably full scan mode.

[0028] In the present invention, after the mass spectrometry detection is completed, the type and content of sulfides are matched and quantitatively analyzed according to the mass spectrum library, the concentration of each sulfide is calculated, and compared with the chromatographic standard curve established with the standard gas, so as to determine the type and concentration of sulfides in the hydrogen sample for fuel cells, and complete the determination of trace sulfides in hydrogen for fuel cells.

[0029] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0030] Example 1

[0031] A 1L fuel cell hydrogen sample was collected using a dedicated sampling device to ensure the representativeness and integrity of the sample, and used as the fuel cell hydrogen sample to be tested; the fuel cell hydrogen sample to be tested was pre-concentrated through an electronic cold trap pre-concentration system, and the pre-concentration conditions were set as follows: the capture temperature was -50°C, the desorption temperature was 150°C, and the transmission line temperature was 100°C. After the pre-concentration was completed, a pre-concentrated sample with a volume of 500mL was obtained; a gas chromatograph was used to perform chromatographic separation on the pre-concentrated sample, and the chromatographic separation conditions were set as follows: a DB-Sulfur column was selected as the chromatographic column, with a length of 60m, an inner diameter of 0.32mm, and a film thickness of 4.2μm; the column temperature program was: the initial temperature was 35°C for 6min, and then 5°C / min to 150°C and hold for 10 min, and finally to 250°C at 10°C / min; the carrier gas is high-purity helium, and the carrier gas flow rate is 1.0 mL / min; a mass spectrometer is used to perform mass spectrometry detection on the sulfides obtained by chromatographic separation, and the conditions for mass spectrometry detection are set as follows: the ion source temperature is 230°C, the quadrupole temperature is 150°C, the solvent delay time is 3 min, the scanning range is 33-400 amu, and the scanning mode is full scan mode; after the mass spectrometry detection, the type and content of sulfides are matched and quantitatively analyzed according to the mass spectrum library, the concentration of each sulfide is calculated, and compared with the standard curve, the type and concentration of sulfides in the hydrogen sample for fuel cells are determined, and the determination of trace sulfides in hydrogen for fuel cells is completed.

[0032] In order to verify the accuracy of the method in Example 1, a calibration sample test was performed. In the same laboratory, using the same instrument, according to the same method, the results of the calibration samples with different contents and the relative deviation calculation results of the corresponding calibration sample target values ​​are shown in Table 1.

[0033] The calculation formula for accuracy is:

[0034]

[0035] Table 1 Results of determination of calibration samples with different contents

[0036]

[0037]

[0038]

[0039] In order to verify the precision of the method in Example 1 above, low concentration samples of sulfur-containing compounds were tested independently 7 times, and the relative standard deviation (RSD) of the results was calculated. The results are shown in Table 2.

[0040] Table 2 Test results and RSD calculation results for low concentration samples of sulfur compounds

[0041]

[0042] As can be seen from the above embodiments, the present invention provides a method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration, comprising the following steps: subjecting the hydrogen sample for fuel cells to be tested to electronic cold trap pre-concentration to obtain a pre-concentrated sample; subjecting the pre-concentrated sample to chromatographic separation and mass spectrometry detection in sequence to determine the type and concentration of sulfides in the hydrogen sample for fuel cells, and completing the determination of trace sulfides in hydrogen for fuel cells. The present invention uses electronic cold trap pre-concentration technology to concentrate the sample, thereby improving the detection sensitivity of sulfides, and the detection limit can reach the ppb level; at the same time, the present invention uses optimized gas chromatography and mass spectrometry conditions to achieve efficient separation and accurate quantification of sulfides, with a relative standard deviation (RSD) of less than 5%; under the specific detection method and conditions of the present invention, the accuracy bias is less than 20%, and the method has good repeatability. The method of the present invention is simple to operate, suitable for online and offline detection of sulfides in hydrogen for fuel cells, suitable for rapid on-site detection, and can be extended to other fields requiring high-sensitivity detection of sulfides. In summary, the method of the present invention has the advantages of high sensitivity, high accuracy, high repeatability, simple operation and wide application, and is of great significance for improving the performance and safety of fuel cells.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration, characterized in that: It includes the following steps: Pre-concentrating the hydrogen sample of the fuel cell to be tested by an electronic cold trap to obtain a pre-concentrated sample; The pre-concentrated samples are sequentially subjected to chromatographic separation and mass spectrometry detection to determine the type and concentration of sulfides in the hydrogen sample for fuel cells, thereby completing the determination of trace sulfides in hydrogen for fuel cells.

2. The method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration according to claim 1, characterized in that: The conditions for electron cold trap pre-concentration are as follows: trapping temperature is -45 to -55°C, desorption temperature is 145 to 155°C, and transmission line temperature is 95 to 105°C.

3. The method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration according to claim 1 or 2, characterized in that: The chromatographic separation adopts a DB-Sulfur chromatographic column, the length of the DB-Sulfur chromatographic column is 40-70m, the inner diameter is 0.32-0.53mm, and the film thickness is 0.75-4.3μm.

4. The method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration according to claim 3, characterized in that: The column temperature program for chromatographic separation is: maintain at 30-40°C for 5-7 minutes; then increase the temperature to 145-155°C at a heating rate of 3-7°C / min, maintain for 8-12 minutes; finally increase the temperature to 245-255°C at a heating rate of 8-12°C / min.

5. The method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration according to claim 4, characterized in that: The carrier gas for chromatographic separation is helium, and the carrier gas flow rate for chromatographic separation is 0.8-1.2 mL / min.

6. The method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration according to claim 5, characterized in that: The ion source concentration of mass spectrometry detection is 225-235° C., the quadrupole temperature of mass spectrometry detection is 145-155° C., and the solvent delay time of mass spectrometry detection is 2-4 min.

7. The method for determining trace sulfides in hydrogen for fuel cells based on electronic cold trap pre-concentration according to claim 6, characterized in that: The scanning range of mass spectrometry detection is 33-400 amu, and the scanning mode of mass spectrometry detection is full scanning mode.

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