Method for detecting chlorine content in trimethylaluminum

Abstract

The invention relates to the field of analysis and detection, in particular to a method for detecting the content of chlorine in trimethylaluminum, which comprises the following steps: S1) mixing trimethylaluminum solution to be detected and an alcohol solution of alkali in a protective gas atmosphere to obtain intermediate sample solution; in the alcoholic solution of the alkali, the alkali is selected from at least one of potassium hydroxide or sodium hydroxide, and the alcohol is selected from at least one of methanol or ethanol; and S2) carrying out titration detection on the intermediate sample solution by adopting a silver nitrate solution to obtain the chlorine content in the trimethylaluminum. The detection method provided by the invention is a new detection means added relative to the existing detection means, and the method is simple to operate and good in repeatability. The adding standard recovery rate is 94.80%-109.41%, the accuracy and precision requirements of the method are met, and the stability and reliability of the detection method are verified. According to the method for detecting the chlorine content in the trimethylaluminum, the experimental process is safe and controllable, and the price of required instruments is relatively low.

Description

Technical Field

[0001] The invention relates to the field of analysis and detection, in particular to a method for detecting the chlorine content in trimethylaluminum. Background Art

[0002] The photovoltaic industry is an important part of the modern energy system, and trimethylaluminum is playing an increasingly important role in the photovoltaic industry due to its unique chemical properties and reactivity. It can be used to synthesize photovoltaic materials, improve photoelectric conversion efficiency, and reduce costs and increase efficiency. The chlorine content in trimethylaluminum seriously affects its function and life, so the detection of chlorine in trimethylaluminum is very important. At present, ion chromatography is the main means of checking chlorine in trimethylaluminum. Its main disadvantage is that it is troublesome to handle samples and the detection cycle is long. Summary of the invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a method for detecting the chlorine content in trimethylaluminum. The detection method provided by the present invention can effectively determine a small amount or a large amount of chloride ion content in trimethylaluminum, and the operation is simple and fast with good repeatability.

[0004] The present invention provides a method for detecting the chlorine content in trimethylaluminum, comprising the following steps:

[0005] S1) under a protective gas atmosphere, mixing a trimethylaluminum test solution and an alkali alcohol solution to obtain an intermediate sample solution;

[0006] In the alcohol solution of the alkali, the alkali is selected from at least one of potassium hydroxide or sodium hydroxide, and the alcohol is selected from at least one of methanol or ethanol;

[0007] S2) titrating the intermediate sample solution with a silver nitrate solution to obtain the chlorine content in the trimethylaluminum.

[0008] The chloride ion content of trimethylaluminum in the trimethylaluminum test solution of the present invention is 0.005% to 10%. The present invention can detect the chloride ion content of 0.005% to 10% in trimethylaluminum, and the intermediate product of trimethylaluminum can also be detected.

[0009] The present invention detects the chlorine content in trimethylaluminum. First, the trimethylaluminum test solution and the alkali alcohol solution are mixed under a protective gas atmosphere. Specifically, the entire step S1) of the present invention needs to be carried out under a protective gas atmosphere, and the water and oxygen in the protective gas atmosphere are both less than 10 ppm; the protective gas is selected from at least one of nitrogen, helium, neon or krypton. Trimethylaluminum reacts violently with water or air, and it is easy to catch fire and explode, so the process of mixing the trimethylaluminum test solution and the alkali alcohol solution needs to be carried out in a protective gas atmosphere that removes water and oxygen.

[0010] The volume ratio of the trimethylaluminum test solution and the alkali alcohol solution of the present invention is (7-10):5; the mass concentration of the trimethylaluminum test solution is 0.1 g / mL-0.4 g / mL; and the molar concentration of the alkali in the alkali alcohol solution is 1.5 mol / L-2.5 mol / L.

[0011] The trimethylaluminum test solution of the present invention is a toluene solution of trimethylaluminum, and the mass ratio of toluene to trimethylaluminum in the toluene solution of trimethylaluminum is (3-13):1. The trimethylaluminum test solution of the present invention is obtained by mixing a trimethylaluminum test sample and toluene. The present invention uses toluene as a solvent for trimethylaluminum to reduce the severity of the reaction of trimethylaluminum in an alkali alcohol solution.

[0012] The present invention mixes the trimethylaluminum test solution and the alkali alcohol solution, and shakes while adding, so that a mixing reaction occurs immediately, and an intermediate sample solution is obtained when the smoke is dissipated. The trimethylaluminum in the trimethylaluminum test solution reacts with the alcohol in the alkali alcohol solution to release a large amount of heat, which eventually causes the solution to boil; and the alkali in the alkali alcohol solution prevents the chloride ions from volatilizing under high temperature acidic conditions.

[0013] After the intermediate sample solution is obtained in step S1), the present invention further includes diluting the intermediate sample solution with a weakly volatile organic solvent, wherein the weakly volatile organic solvent is selected from one or more of isopropanol, n-propanol, butanol and toluene. The present invention dilutes the intermediate sample solution with the weakly volatile organic solvent, which is less volatile than ethanol and can dilute the solution to cool it down. The volume ratio of the intermediate sample and the weakly volatile organic solvent of the present invention is 1:(3-5), preferably 1:(3.5-4.5). After the intermediate sample solution is obtained, the present invention further includes acidifying the intermediate sample solution with an acid; the acid is selected from at least one of nitric acid or sulfuric acid. The present invention acidifies the intermediate sample solution to prevent silver from precipitating under alkaline conditions. In certain embodiments of the present invention, after the intermediate sample solution is obtained, the intermediate sample solution is first diluted with the weakly volatile organic solvent, and then the intermediate sample solution is acidified with the acid.

[0014] After the intermediate sample solution is obtained, the present invention uses a silver nitrate solution to perform titration detection on the intermediate sample solution. Specifically, the intermediate sample solution is detected by an automatic potentiometric titrator using a silver nitrate solution. The present invention uses an electric potentiometric titrator for titration detection. Compared with ion chromatography, the automatic potentiometric titrator can directly titrate the sample, and the ion chromatography needs to eliminate the influence of the matrix; the ion chromatography needs to prepare and configure the working curve solution and draw the working curve each time, and the automatic potentiometric titrator only needs to calibrate the silver nitrate solution once / batch.

[0015] The present invention adopts silver nitrate solution for titration detection, and the concentration of the silver nitrate solution is 0.0009 mol / L~0.13 mol / L. In the present invention, silver nitrate solutions of different concentrations are used to titrate trimethylaluminum with different chlorine content ranges. Specifically, when the chlorine content in the trimethylaluminum is less than 0.05%, a silver nitrate solution with a concentration of 0.0009 mol / L to 0.003 mol / L is used for titration detection, and preferably a silver nitrate solution with a concentration of 0.001 mol / L is used for titration detection; when the chlorine content in the trimethylaluminum is 0.05 to 0.5%, a silver nitrate solution with a concentration of 0.009 mol / L to 0.013 mol / L is used for titration detection, and preferably a silver nitrate solution with a concentration of 0.01 mol / L is used for titration detection; when the chlorine content in the trimethylaluminum is greater than 0.5%, a silver nitrate solution with a concentration of 0.09 mol / L to 0.13 mol / L is used for titration detection, and preferably a silver nitrate solution with a concentration of 0.1 mol / L is used for titration detection.

[0016] Before the silver nitrate solution is used for titration detection, the silver nitrate solution needs to be calibrated. Specifically, the silver nitrate solution is calibrated by an automatic potentiometric titrator. The silver nitrate solution is calibrated by an automatic potentiometric titrator using a sodium chloride standard reagent and an aqueous solution of starch, and the sodium chloride standard reagent is calcined to a constant weight at 500° C. to 600° C. in advance.

[0017] For a silver nitrate solution with a nominal concentration of 0.09 mol / L to 0.13 mol / L, the concentration of the sodium chloride standard reagent in the aqueous solution of the sodium chloride standard reagent and starch is 0.004 to 0.005 g / mL, and the concentration of the starch in the aqueous solution of the sodium chloride standard reagent and starch is 0.0015 to 0.0025 g / mL. In certain embodiments of the present invention, a 0.1 mol / L silver nitrate solution is calibrated, 0.22 g of a sodium chloride standard reagent burned to a constant amount in a high temperature furnace at 500°C to 600°C is weighed, dissolved in 40 mL of water, 10 mL of starch solution (10 g / L) is added, and titrated with a 916 Ti-Touch automatic potentiometric titrator.

[0018] For a silver nitrate solution with a nominal concentration of 0.009 mol / L to 0.013 mol / L, the concentration of the sodium chloride standard reagent in the aqueous solution of the sodium chloride standard reagent and starch is 0.00028 to 0.00031 mol / L, and the concentration of the starch in the aqueous solution of the sodium chloride standard reagent and starch is 0.0015 to 0.0025 g / mL. In certain embodiments of the present invention, a 0.0011 mol / L silver nitrate solution is calibrated, 2 mL of a 0.1 mol / L sodium chloride standard solution is pipetted, 40 mL of water is added, 10 mL of a starch solution (10 g / L) is added, and titration is performed using a 916 Ti-Touch automatic potentiometric titrator.

[0019] For a silver nitrate solution with a nominal concentration of 0.0009 mol / L to 0.0013 mol / L, the concentration of the sodium chloride standard reagent in the aqueous solution of the sodium chloride standard reagent and starch is 0.00028 to 0.00031 mol / L, and the concentration of the starch in the aqueous solution of the sodium chloride standard reagent and starch is 0.0015 to 0.0025 g / mL. In certain embodiments of the present invention, a silver nitrate solution of 0.0011 mol / L is calibrated, 0.15 mL of a 0.1 mol / L sodium chloride standard solution is pipetted, 40 mL of water is added, 10 mL of a starch solution (10 g / L) is added, and titration is performed using a 916 Ti-Touch automatic potentiometric titrator.

[0020] The present invention uses silver nitrate solution to detect the intermediate sample solution, sets two equivalence points, the equivalence point is 10, and uses the second equivalence point as the result to perform titration with an automatic potentiometric titrator to obtain the chlorine content in trimethylaluminum.

[0021] The present invention provides a method for detecting the chlorine content in trimethylaluminum, comprising the following steps: S1) in a protective gas atmosphere, a trimethylaluminum test solution and an alkali alcohol solution are mixed to obtain an intermediate sample solution; in the alkali alcohol solution, the alkali is selected from at least one of potassium hydroxide or sodium hydroxide, and the alcohol is selected from at least one of methanol or ethanol; S2) the intermediate sample solution is titrated and detected with a silver nitrate solution to obtain the chlorine content in the trimethylaluminum. The method for detecting the chlorine content in trimethylaluminum provided by the present invention is a new detection method added to the existing detection means, and the method is simple to operate and has good repeatability. A spike recovery experiment is performed to obtain a recovery rate of 94.80% to 109.41%, which can determine that the detection method of the present invention meets the accuracy and precision requirements of the method, and verifies the stability and reliability of the detection method. In addition, the experimental process of the method for detecting the chlorine content in trimethylaluminum provided by the present invention is safe and controllable, and the price of the required instruments is relatively low. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a schematic diagram of the process for detecting the chlorine content in trimethylaluminum in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention discloses a method for detecting the chlorine content in trimethylaluminum. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0024] The embodiment of the present invention is according to Figure 1 The process described is used to detect the chlorine content in trimethylaluminum. Figure 1 The figure is a schematic diagram of the process for detecting the chlorine content in trimethylaluminum in an embodiment of the present invention.

[0025] The preparation work of the detection method of chlorine content in trimethylaluminum of the present invention is as follows:

[0026] 1.1 Instruments and reagents

[0027] (1) Instruments: 916 Ti-Touch automatic potentiometric titrator; silver electrode; glove box;

[0028] (2) Reagents: trimethylaluminum sample; silver nitrate (reference reagent); sodium chloride (reference reagent); potassium hydroxide (superior purity); ethanol (H2O≤30 ppm); 2-propanol (EP grade); toluene (H2O≤10 ppm); nitric acid (EP grade);

[0029] 1.2 Solution preparation and calibration

[0030] (1) Preparation and calibration of standard working solution

[0031] Preparation of 0.1 M silver nitrate solution: Weigh 17.5 g of silver nitrate, dissolve in 1000 mL of water, shake well, and store in a sealed brown bottle.

[0032] Calibration: Weigh 0.22 g of sodium chloride, a reference reagent burned to a constant weight in a high-temperature furnace at 550°C, dissolve it in 40 mL of water, add 10 mL of starch solution (10 g / L), and titrate using a 916 Ti-Touch automatic potentiometric titrator.

[0033] Preparation of 0.001 M silver nitrate solution: Pipette 10 mL of 0.1 M silver nitrate solution into a 1000 mL brown bottle, dilute to volume with water, and shake well.

[0034] Calibration: Pipette 0.15 mL of 0.1 M sodium chloride solution (prepared by burning the reference reagent sodium chloride to a constant amount in a high-temperature furnace at 550°C), add 40 mL of water, add 10 mL of starch solution (10 g / L), and titrate using a 916 Ti-Touch automatic potentiometric titrator.

[0035] (2) Preparation of chlorine standard solution

[0036] 5000 ppm chlorine standard: Weigh 8.2426 g of sodium chloride, a reference reagent burned to a constant weight in a high-temperature furnace at 550°C, dissolve in 40 mL of water, and make up to 1000 mL with water.

[0037] 100 ppm Chlorine Standard: Pipette 20 mL of 5000 ppm chlorine standard solution and dilute to 1000 mL with water.

[0038] 1.3 Cleaning utensils

[0039] Before the test, the 100 mL beaker was dried in a drying oven (120 °C, 2 h), cooled in a desiccator for 30 min, placed in a glove box, and then purged with argon.

[0040] The present invention will be further described below in conjunction with embodiments:

[0041] Example 1

[0042] For low chlorine products:

[0043] 1. In a glove box under argon atmosphere, use a pipette to take 7.5 mL of toluene and place it at the bottom of a 100 mL beaker. Add 2 g of trimethylaluminum sample and slowly add 5 mL of 2 M potassium hydroxide ethanol solution. After the smoke has dissipated, add 50 mL of 2-propanol.

[0044] 2. Take it out from the glove box and add 5 mL of nitric acid.

[0045] 3. Select 0.001 M silver nitrate solution, set two equivalence points on the instrument, the equivalence point is 10, and use the second equivalence point as the result to titrate with an automatic potentiometric titrator.

[0046] 4. The automatic potentiometric titrator showed that the chlorine content in trimethylaluminum was 35.6 ppm, and the ion chromatography showed that it was 38.2 ppm.

[0047] Example 2

[0048] For high chlorine intermediate products:

[0049] 1. In a glove box under argon atmosphere, use a pipette to take 7.5 mL of toluene and place it at the bottom of a 100 mL beaker. Add 1 g of trimethylaluminum sample and slowly add 5 mL of 2M potassium hydroxide ethanol solution. After the smoke has dissipated, add 50 mL of 2-propanol.

[0050] 2. Take it out from the glove box and add 5 mL of nitric acid.

[0051] 3. Select 0.1 M silver nitrate solution, set the instrument to an equivalence point of 10, and use an automatic potentiometric titrator for titration.

[0052] 4. The automatic potentiometric titrator showed that the chlorine content in trimethylaluminum was 2.11%, and the ion chromatography result was 2.07%.

[0053] The steps of Example 1 and Example 2 were repeated respectively, and the sample was subjected to a spike recovery experiment, and the recovery was obtained to be between 94.80% and 109.41%. The results are listed in Table 1. It can be determined that the detection method of the present invention meets the accuracy and precision requirements of the method, and the stability and reliability of the detection method are verified.

[0054] Table 1

[0055]

[0056] Comparative Example 1

[0057] Three samples with different chlorine contents were tested respectively. The specific steps are as follows:

[0058] 1. Under the protection of argon atmosphere in the glove box, use a pipette to take 1 g of trimethylaluminum sample into the PFA bottle and tighten the bottle cap.

[0059] 2. Take it out from the glove box, and in the fume hood, slowly loosen the bottle cap to stop the white smoke from the bottle mouth immediately, and allow trimethylaluminum to slowly oxidize in the air for 5 hours (until the white smoke stops). Open the bottle cap, slowly add 20 mL of pure water (the bottom layer of the sample is easily isolated by the surface oxide, resulting in incomplete oxidation, and this step is prone to fire), add 5 mL of nitric acid and heat to digest at 150℃ (without the bottle cap), and cool after dissolution.

[0060] 3. After appropriate dilution, chlorine was detected by ion chromatography. The recoveries of three samples with different chlorine contents were 48.26%, 62.31% and 75.24% respectively.

[0061] Table 2

[0062]

[0063] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for detecting the chlorine content in trimethylaluminum, characterized in that: The following steps are involved: S1) under a protective gas atmosphere, mixing a trimethylaluminum test solution and an alkali alcohol solution to obtain an intermediate sample solution; In the alcohol solution of the alkali, the alkali is selected from at least one of potassium hydroxide or sodium hydroxide, and the alcohol is selected from at least one of methanol or ethanol; S2) titrating the intermediate sample solution with a silver nitrate solution to obtain the chlorine content in the trimethylaluminum.

2. The detection method according to claim 1, characterized in that: In step S1), the volume ratio of the trimethylaluminum test solution and the alkali alcohol solution is (7-10):5; The mass concentration of the trimethylaluminum test solution is 0.1 g / mL to 0.4 g / mL; The molar concentration of the alkali in the alcoholic alkali solution is 1.5 mol / L to 2.5 mol / L.

3. The detection method according to claim 1, characterized in that: In step S1), the trimethylaluminum test solution is a toluene solution of trimethylaluminum.

4. The detection method according to claim 3, characterized in that: The mass ratio of toluene and trimethylaluminum in the trimethylaluminum test solution is (3-13):

1.

5. The detection method according to claim 3, characterized in that: In step S1), the water and oxygen in the protective gas atmosphere are both less than 10 ppm.

6. The detection method according to claim 1, characterized in that: In step S1), after obtaining the intermediate sample solution, the method further comprises diluting the intermediate sample solution with a weakly volatile organic solvent; the weakly volatile organic solvent is selected from one or more of isopropanol, n-propanol, butanol and toluene.

7. The detection method according to claim 5, characterized in that: The volume ratio of the intermediate sample liquid to the weakly volatile organic solvent is 1:(3-5).

8. The detection method according to claim 1, characterized in that: In step S1), after obtaining the intermediate sample solution, the method further includes acidifying the intermediate sample solution with an acid; The acid is selected from at least one of nitric acid and sulfuric acid.

9. The detection method according to claim 1, characterized in that: In step S2), the concentration of the silver nitrate solution is 0.001 mol / L~0.1 mol / L.

10. The detection method according to any one of claims 1 to 9, characterized in that: The chloride ion content of trimethylaluminum in the trimethylaluminum test solution is 0.005% to 10%.

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