Method for determining chlorine content of coal tar by using diatomite carrier

Abstract

The invention provides a coal tar chlorine content determination method by using a diatomite carrier, which comprises the following steps: carrying out first mixing on coal tar and diatomite to obtain a first sample; performing second mixing on the first sample and a first aldrin mixture, and covering a second aldrin mixture to obtain a second sample; sequentially carrying out first heat treatment, second heat treatment and third heat treatment on the second sample, and then cooling to obtain a burnt material; the temperature of the first heat treatment, the temperature of the second heat treatment and the temperature of the third heat treatment are sequentially increased; and dispersing the burnt material in a solvent, then filtering, washing, and testing the content of chloride ions. According to the method for determining the chlorine content in the coal tar by using the diatomite carrier, the diatomite is used as the carrier to determine the chlorine content in the coal tar, so that the uniform dispersity of a sample can be improved, the volatilization loss is reduced, the sample is prevented from coking or caking, the impurity interference is reduced, and the determination repeatability and stability are improved.

Description

Technical Field

[0001] The present application relates to the fields of chemical analysis and coal chemical industry, and in particular to a method for determining the chlorine content of coal tar using a diatomaceous earth carrier. Background Art

[0002] Coal tar is a black or dark brown viscous liquid with a pungent odor generated during coal distillation. It is one of the coal gas purification products condensed and separated during the cooling process of raw coal gas. Coal tar is a complex mixture of highly aromatic hydrocarbons, most of which are polycyclic and condensed ring compounds with or without side chains and heterocyclic compounds containing oxygen, sulfur and nitrogen, and contain a small amount of aliphatic hydrocarbons, cycloalkanes and unsaturated hydrocarbons, as well as coal dust, coke dust and pyrolytic carbon. The newly recovered coal tar also contains about 5% of water dissolved in various inorganic salts and other impurities. Due to the presence of extremely fine pyrolytic carbon particles, the water often forms a stable emulsion with the oil.

[0003] Since raw coal contains a small amount of chlorine, coal tar inevitably contains trace amounts of inorganic or organic chlorine, which may release chloride ions during the production and utilization process. Chloride ions have strong penetrating power and will rapidly reduce the pH value when adsorbed on the surface of equipment, causing acidification and corrosion of production equipment and pipelines. Therefore, it is necessary to accurately measure the chlorine content in coal tar and evaluate its impact on production equipment and pipelines as well as the next step of processing and utilization of products, so as to take corresponding measures.

[0004] The existing technical method for analyzing and detecting the chlorine content in coal tar is usually extraction separation, that is, using distilled water to extract the chlorine in the coal tar, and then using standard silver nitrate solution titration or ion chromatography to determine the chlorine in the solution, but the disadvantages are: 1. Distilled water and tar are difficult to mix evenly, and can only dissolve inorganic chlorides in the tar; 2. The extracted solution may contain color and organic matter, the color will affect the judgment of the silver nitrate titration end point, and the organic matter cannot be directly sampled into the ion chromatography.

[0005] The national standard GB / T 3558-2014 "Determination of chlorine in coal" specifies the determination of chlorine in solids such as coal and coke. The core of this method is to use the oxidation and decomposition of high-temperature melting to release the chlorine element in coal and convert it into a stable chloride form (such as sodium chloride). Therefore, it is feasible to apply this method to the determination of chlorine in coal tar, but there are the following problems: 1. Coal tar is liquid or semi-solid, and it cannot be fully contacted and mixed with the axelrodite mixture; 2. Coal tar contains more volatile and high molecular weight components than coal, and the relatively mild heating method cannot guarantee the complete decomposition and chlorine recovery rate. Summary of the invention

[0006] In view of this, the present application aims to provide a method for determining the chlorine content of coal tar using a diatomaceous earth carrier. Using diatomaceous earth as a carrier to determine the chlorine content in coal tar can improve the uniform dispersion of the sample, reduce volatilization loss, avoid sample coking or agglomeration, reduce interference from impurities, and improve the repeatability and stability of the determination.

[0007] To achieve the above purpose, the present application proposes a method for determining the chlorine content of coal tar using a diatomaceous earth carrier, comprising:

[0008] The coal tar and diatomaceous earth are first mixed to obtain a first sample;

[0009] The first sample and the first Eschka mixture are mixed for a second time and then covered with the second Eschka mixture to obtain a second sample;

[0010] The second sample is subjected to a first heat treatment, a second heat treatment and a third heat treatment in sequence, and then cooled to obtain a burnt product; the temperature of the first heat treatment, the temperature of the second heat treatment and the temperature of the third heat treatment are increased in sequence;

[0011] The burnt product was dispersed in a solvent, then filtered, washed, and tested for chloride ion content.

[0012] In some embodiments, the mass ratio of the coal tar to the diatomaceous earth is 1:(1-3).

[0013] In some embodiments, the first aishaka mixture and the second aishaka mixture both include light magnesium oxide and anhydrous sodium carbonate, and the mass ratio of the light magnesium oxide to the anhydrous sodium carbonate is (2-3):1.

[0014] In some embodiments, the mass ratio of the first Aishkar mixture to the first sample is (2-3):1.

[0015] In some embodiments, the mass ratio of the first Aishkar mixture to the second Aishkar mixture is (2-4):(1-3).

[0016] In some embodiments, the temperature of the first heat treatment is 100-150°C.

[0017] In some embodiments, the first heat treatment is performed for 30-60 minutes, and the heating rate of the first heat treatment is 10-20° C. / min.

[0018] In some embodiments, the temperature of the second heat treatment is 550-650°C.

[0019] In some embodiments, the second heat treatment is performed for 1-4 hours, and the heating rate of the second heat treatment is 10-20° C. / min.

[0020] In some embodiments, the temperature of the third heat treatment is 800-850°C.

[0021] In some embodiments, the third heat treatment is performed for 15-45 minutes, and the heating rate of the third heat treatment is 10-20° C. / min.

[0022] In some embodiments, the first heat treatment, the second heat treatment, and the third heat treatment are all performed in an air atmosphere.

[0023] In some embodiments, the first mixing and the second mixing are both performed in a first container, and the second sample is present in the first container.

[0024] In some embodiments, the first container comprises a crucible, such as one of a 30 mL-50 mL porcelain crucible.

[0025] In some embodiments, the solvent includes one of distilled water, deionized water, and purified water.

[0026] In some embodiments, the method of dispersing the burned material in a solvent, followed by filtering, washing, and testing the chloride ion content comprises:

[0027] transferring the burnt material into a second container to obtain a second container containing the burnt material;

[0028] flushing the wall of the first container with a solvent to obtain a mixed solution;

[0029] The mixed solution is poured into the second container containing the burning material, followed by stirring, heating, and filtering with filter paper by a pouring method to obtain a residue and a filtrate;

[0030] Washing the residue at least once with the hot solvent to obtain a first washing liquid and washed residue;

[0031] Subsequently, the washed residue is transferred into a funnel, and the filter paper and the washed residue are washed with the hot solvent until no chloride ions are present, thereby obtaining a second washing solution;

[0032] The filtrate, the first flushing liquid and the second flushing liquid are mixed, fixed to volume, and the chloride ion content is tested.

[0033] In some embodiments, the method for testing the chloride ion content comprises one of ion chromatography, potentiometric titration, and potassium thiocyanate titration.

[0034] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further includes the step of mixing the diatomaceous earth with the first aletrouvar mixture and then covering it with the second aletrouvar mixture as a blank value for determination.

[0035] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further includes the step of testing the chloride ion content multiple times in parallel and taking the average of the multiple chloride ion content test results as the final test value of the chlorine content in the coal tar.

[0036] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further comprises the step of adding a chlorine standard sample to the coal tar for testing.

[0037] In some embodiments, the coal tar is coal tar obtained by pyrolysis or gasification under an inert gas or carbon dioxide gas atmosphere.

[0038] The method for determining the chlorine content of coal tar using a diatomaceous earth carrier described in this application has significant advantages in using diatomaceous earth as a carrier to determine the chlorine content in coal tar. Specifically, using diatomaceous earth as a carrier to determine the chlorine content in coal tar has the following advantages compared to not using diatomaceous earth:

[0039] 1) Uniform dispersion of samples: Diatomaceous earth has a strong adsorption capacity. Evenly attaching coal tar to its surface helps to evenly disperse the sample, so that the coal tar can be fully decomposed when heated, thereby increasing the release rate of chlorine.

[0040] 2) Reduce volatilization loss: Coal tar is easy to volatilize at high temperature, and the adsorption effect of diatomaceous earth helps to fix the tar on the carrier surface, reducing the volatilization loss under high temperature conditions and ensuring a higher recovery rate of chlorine content in the measurement process.

[0041] 3) Avoid sample coking or agglomeration: Direct heating of coal tar may cause the sample to coke or agglomerate at high temperatures, affecting the release of chlorine. Diatomaceous earth can effectively adsorb and disperse tar, reduce such phenomena, and ensure complete decomposition of the sample.

[0042] 4) Reduce interference from impurities: Diatomaceous earth is chemically inert and will not react with components in coal tar, thus reducing the interference of impurities on the measurement results, making it particularly suitable for precise measurement by ion chromatography.

[0043] 5) Improve the repeatability and stability of the measurement: Fixing the sample with diatomaceous earth makes the sample processing conditions consistent, improves the repeatability of the experiment and the stability of the data, and is suitable for batch analysis and standardized operations.

[0044] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0045] The above-mentioned and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of embodiments in conjunction with the drawings.

[0046] Wherein:

[0047] Figure 1 It is a flowchart of a method for measuring the chlorine content of coal tar using a diatomite carrier shown for an exemplary embodiment of the present application. Detailed Description of the Embodiments

[0048] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the drawings. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and should not be construed as a limitation to the present application.

[0049] In the present application, the disclosure of a numerical range includes all values within the entire range and the disclosure of further sub-ranges, including the endpoints and sub-ranges given for these ranges.

[0050] In the present application, for raw materials, equipment, etc. involved, unless otherwise specified, they are all raw materials and equipment that can be obtained through commercial channels or prepared by known methods; for the methods involved, unless otherwise specified, they are all conventional methods.

[0051] When the term "and / or" is used in a list containing two or more items, it means that any one of the listed items can be used alone or in combination with any one or more of the listed items. For example, the expression "A and / or B" is intended to mean A or B or A and B, that is, it only means A, only means B, or means the combination of A and B.

[0052] In the present application, room temperature refers to 15 - 25 °C.

[0053] The inventors found that diatomite has excellent adsorption and dispersibility, can well adsorb liquid or semi-solid coal tar, and diatomite is in powder form with small particles and is easy to mix, can form a uniform mixture with coal tar, avoid the agglomeration phenomenon of coal tar, help improve the uniformity of the sample, and ensure that the results of chlorine analysis are more reproducible. At the same time, the main component of diatomite is silicon dioxide, which has good thermal stability and chemical inertness and will not interfere with subsequent ion chromatography analysis.

[0054] In addition, the composition of coal tar is complex and contains high molecular weight components, which may produce coking or incomplete decomposition during the heating process. The present application has improved the heating program to ensure complete decomposition of tar and the recovery rate of chlorine.

[0055] A method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to an embodiment of the present application is described below with reference to the accompanying drawings.

[0056] Figure 1 The present invention is a flowchart showing a method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to an exemplary embodiment of the present invention.

[0057] like Figure 1 As shown, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier in an embodiment of the present application comprises the following steps:

[0058] S101, performing a first mixing of coal tar and diatomaceous earth to obtain a first sample.

[0059] In some embodiments, the coal tar is coal tar obtained by pyrolysis or gasification under an inert gas or carbon dioxide gas atmosphere.

[0060] Exemplarily, the inert gas includes, but is not limited to, at least one of nitrogen, helium, and argon.

[0061] In some embodiments, the gasification temperature is 400-1000°C, including but not limited to 400°C, 600°C, 800°C, or 900°C.

[0062] In some embodiments, the gasification time is 30-60 min, including but not limited to 50 min, 30 min or 40 min, etc.

[0063] In some embodiments, the mass ratio of the coal tar to the diatomaceous earth is 1:(1-3).

[0064] Exemplarily, the mass ratio of the coal tar to the diatomaceous earth includes but is not limited to 1:1, 1:1.5, 1:2, 1:2.5 or 1:3, etc.

[0065] In the embodiments of the present application, the mass ratio of coal tar to diatomaceous earth is generally between 1:1 and 1:3, and can be adjusted according to the viscosity and volatility of the tar to ensure that the coal tar can be evenly attached to the surface of the diatomaceous earth.

[0066] In addition, if the mass ratio of the coal tar to the diatomaceous earth is less than 1:1, the amount of diatomaceous earth used is relatively small, and the mixture of coal tar and diatomaceous earth (i.e., the first mixture) may still be in a liquid state, affecting the uniform mixing of the first mixture and the first Eschka reagent; if the mass ratio of the coal tar to the diatomaceous earth is greater than 3:1, there may be too much diatomaceous earth, affecting the release of chlorine.

[0067] As a preferred example, the mass ratio of the coal tar to the diatomaceous earth is 1: 2. In this case, the tar can be completely dispersed to prevent the excessive carrier from affecting the release of chlorine, that is, to achieve a balanced state of complete dispersion of the tar and an appropriate amount of the carrier.

[0068] As an optional embodiment, the total mass of the coal tar and the diatomaceous earth can be controlled between 1-1.5 grams to ensure that an appropriate amount of chloride ions are obtained during ion chromatography detection.

[0069] In some embodiments, the first mixing is performed in a first container.

[0070] Exemplarily, the first container includes a crucible.

[0071] As an optional example, the first container is a porcelain crucible with a capacity of 30 mL-50 mL.

[0072] In some embodiments, the first mixing entails carefully blending the coal tar and diatomaceous earth.

[0073] As an optional example, coal tar and diatomaceous earth are first mixed, including: accurately weighing (0.3±0.05) g (weighed to 0.0002 g) of a general analytical test coal tar sample, putting it into a first container crucible containing 0.7 g (weighed to 0.01 g) of diatomaceous earth, and mixing carefully.

[0074] In the examples of the present application, the first sample is a diatomaceous earth-tar mixed sample.

[0075] S102, performing a second mixing on the first sample and the first Ehrlich card mixture obtained in step S101, and then covering the mixture with a second Ehrlich card mixture to obtain a second sample.

[0076] In some embodiments, the first aishkar mixture and the second aishkar mixture both include light magnesium oxide and anhydrous sodium carbonate.

[0077] In the embodiments of the present application, light magnesium oxide is an analytically pure reagent in powder form. Its function is to adsorb the acidic volatile substances produced during the decomposition process, making it easier for chloride ions to be released and fixed. Anhydrous sodium carbonate is an analytically pure reagent in powder form. Its function is to provide an alkaline environment to promote the decomposition of organic matter and the release of chlorine.

[0078] In some embodiments, in the first aishaka mixture and the second aishaka mixture, the mass ratio of the light magnesium oxide to the anhydrous sodium carbonate is (2-3):1.

[0079] Exemplarily, the mass ratio of the light magnesium oxide to the anhydrous sodium carbonate includes but is not limited to 2:1, 2.25:1, 2.5:1, 2.75:1 or 3:1, etc.

[0080] In the embodiments of the present application, the mass ratio of light magnesium oxide to anhydrous sodium carbonate is 2:1, which can provide a moderate alkaline environment, while improving the chemical stability during the melting process, facilitating sample processing and subsequent chlorine detection. However, since coal tar is a complex organic substance that may cause interference, the proportion of magnesium oxide can be appropriately increased to enhance the alkaline environment and reduce the generation of interfering by-products. It is generally recommended to maintain a ratio of 2:1, but a ratio of 3:1 can also be tried to enhance adsorption, and the specific ratio can be optimized based on preliminary experimental data.

[0081] As a preferred example, the first aishaka mixture and the second aishaka mixture are both mixtures of light magnesium oxide and anhydrous sodium carbonate in a mass ratio of (2-3):1. More preferably, the first aishaka mixture and the second aishaka mixture are exactly the same.

[0082] In some embodiments, the mass ratio of the first Aishkar mixture to the first sample is (2-3):1.

[0083] Exemplarily, the mass ratio of the first Aishkar mixture to the first sample includes but is not limited to 2:1, 2.25:1, 2.5:1, 2.75:1 or 3:1, etc.

[0084] In the embodiment of the present application, the mass ratio of the first Eschka mixture to the first sample is generally 2:1 to 3:1, which is more suitable, so as to ensure that the sample is fully reacted and avoid chlorine loss. Optionally, the experiment starts with a ratio of 3:1 to ensure sufficient reagent volume, and then fine-tune the ratio according to the analysis results to further optimize the recovery rate of chlorine and the measurement accuracy.

[0085] In some embodiments, the mass ratio of the first Aishkar mixture to the second Aishkar mixture is (2-4):(1-3).

[0086] Exemplarily, the mass ratio of the first Aishkar mixture to the second Aishkar mixture includes but is not limited to 2:1, 3:2, 4:1, 4:3 or 2:3, etc., preferably 3:2.

[0087] In some embodiments, the second mixing requires uniformly mixing the first sample and the first Eschka mixture obtained in step S101.

[0088] In some embodiments, the second mixing is performed in the first container, and the second sample is present in the first container, that is, the first Eschka mixture is added to the first container containing the first sample, and the two are second mixed to obtain the second sample.

[0089] As an optional example, step S102 is: evenly mix the first Eschka mixture with the first sample, and then evenly cover them with the second Eschka mixture to obtain a second sample.

[0090] S103, subjecting the second sample obtained in step S102 to a first heat treatment, a second heat treatment and a third heat treatment in sequence, followed by cooling to obtain a burnt product; the temperature of the first heat treatment, the temperature of the second heat treatment and the temperature of the third heat treatment are increased in sequence.

[0091] In the embodiments of the present application, the purpose of the first heat treatment is to remove volatile substances and moisture in the sample, the purpose of the second heat treatment is to promote the decomposition of tar and the release of chlorine, and the purpose of the third heat treatment is to ensure complete reaction of the sample and sufficient release of the chlorine element.

[0092] In some embodiments, the temperature of the first heat treatment is 100-150°C, including but not limited to 105°C, 125°C or 145°C, preferably 150°C.

[0093] In some embodiments, the first heat treatment time is 30-60 min, including but not limited to 50 min, 30 min or 40 min, etc.

[0094] In some embodiments, the heating rate of the first heat treatment is 10-20°C / min, including but not limited to 12.5°C / min, 15°C / min or 17.5°C / min.

[0095] In some embodiments, the temperature of the second heat treatment is 550-650°C, including but not limited to 575°C, 600°C or 625°C, preferably 600°C.

[0096] In some embodiments, the second heat treatment time is 1-4 hours, including but not limited to 2 hours, 3 hours or 3.5 hours.

[0097] In some embodiments, the heating rate of the second heat treatment is 10-20°C / min, including but not limited to 12.5°C / min, 15°C / min or 17.5°C / min.

[0098] In some embodiments, the temperature of the third heat treatment is 800-850°C, including but not limited to 805°C, 820°C or 840°C, preferably 850°C.

[0099] In some embodiments, the third heat treatment lasts for 15-45 minutes, including but not limited to 20 minutes, 30 minutes or 40 minutes.

[0100] In some embodiments, the total time of the first heat treatment, the second heat treatment and the third heat treatment is 2-6 hours, including but not limited to 3 hours, 4 hours or 5 hours.

[0101] In the embodiments of the present application, the burning temperature (i.e., the second heat treatment temperature and the third heat treatment temperature) should be controlled above 500°C, and an appropriate heating rate should be maintained to avoid incomplete decomposition or sudden boiling of the sample. The burning time is determined by the quality of the coal tar sample and the organic components. When the ashing is completed, the residue should be light gray or white, without obvious black or dark residue.

[0102] In some embodiments, the heating rate of the third heat treatment is 10-20°C / min, including but not limited to 12.5°C / min, 15°C / min or 17.5°C / min.

[0103] In some embodiments, the first heat treatment, the second heat treatment, and the third heat treatment are all performed in an air atmosphere.

[0104] In some embodiments, the first heat treatment, the second heat treatment and the third heat treatment are all performed in a muffle furnace, preferably a muffle furnace with a temperature control device, which can be heated to 1000° C. and is well ventilated.

[0105] S104, dispersing the burnt product obtained in step S103 in a solvent, then filtering, washing, and testing the chloride ion content.

[0106] In some embodiments, the solvent includes but is not limited to one of distilled water, deionized water, purified water, etc., preferably distilled water.

[0107] In some embodiments, the filtering method includes but is not limited to at least one of centrifugal separation, suction filtration, filter paper filtration, etc.

[0108] In some embodiments, the detergent used for washing is consistent with the solvent, including but not limited to one of distilled water, deionized water, purified water, etc., preferably distilled water, more preferably hot distilled water, such as 70-80°C distilled water, etc.

[0109] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further comprises the step of constant volume during the test of chloride ion content.

[0110] In the embodiments of the present application, the purpose of washing is to remove ash and ensure that there are no chloride ions in the filter residue.

[0111] As an optional method, the burning material is dispersed in a solvent, and then filtered, washed, and tested for chloride ion content, comprising the following steps:

[0112] (1) transferring the burned material into a second container to obtain a second container containing the burned material;

[0113] (2) flushing the wall of the first container with a solvent to obtain a mixed solution;

[0114] (3) pouring the mixed solution into the second container containing the burned material, stirring, heating, and filtering with filter paper to obtain a residue and a filtrate;

[0115] (4) washing the first residue at least once with the hot solvent to obtain a first washing liquid and a washed residue;

[0116] (5) then transferring the rinsed residue into a funnel, and then rinsing the filter paper and the rinsed residue with the hot solvent until no chloride ions are present, thereby obtaining a second rinse solution;

[0117] (6) The filtrate, the first flushing liquid and the second flushing liquid are mixed, fixed to volume, and tested for chloride ion content.

[0118] Exemplarily, the second container includes but is not limited to one of a beaker, a conical flask, a porcelain cup, etc., preferably a beaker.

[0119] Exemplarily, the temperature of the hot solvent is 70-80°C, preferably 70-80°C distilled water.

[0120] In some embodiments, the method for determining the absence of chloride ions in step (4) is: checking for turbidity using a silver nitrate solution.

[0121] Exemplarily, the silver nitrate solution may have a concentration of 10 g / L.

[0122] As an optional example, a 10 g / L silver nitrate solution is prepared by weighing 1 g of silver nitrate and dissolving it in 100 mL of water, and then adding several milliliters of nitric acid. For example, the nitric acid is dilute nitric acid.

[0123] In some embodiments, the method for testing the chloride ion content includes but is not limited to one of ion chromatography, potentiometric titration, and potassium thiocyanate titration, preferably ion chromatography.

[0124] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further includes the step of mixing the diatomaceous earth with the first aletrouvar mixture and then covering it with the second aletrouvar mixture as a blank value for determination.

[0125] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further includes the step of testing the chloride ion content multiple times in parallel and taking the average of the multiple chloride ion content test results as the final test value of the chlorine content in the coal tar.

[0126] In some embodiments, the method for determining the chlorine content of coal tar using a diatomaceous earth carrier further comprises the step of adding a chlorine standard sample to the coal tar for testing.

[0127] In some embodiments, the weight of each raw material is measured using an analytical balance, such as an analytical balance with a sensitivity of 0.1 mg.

[0128] The method for determining the chlorine content of coal tar using a diatomaceous earth carrier in the embodiment of the present application is based on an inorganic element analysis method of high-temperature melting decomposition and ion chromatography detection to quantitatively test the chlorine element in coal tar. This method has significant advantages in using diatomaceous earth as a carrier to determine the chlorine content in coal tar. Specifically, using diatomaceous earth as a carrier to determine the chlorine content in coal tar has the following advantages over not using diatomaceous earth:

[0129] 1) Uniform dispersion of samples: Diatomaceous earth has a strong adsorption capacity. Evenly attaching coal tar to its surface helps to evenly disperse the sample, so that the coal tar can be fully decomposed when heated, thereby increasing the release rate of chlorine.

[0130] 2) Reduce volatilization loss: Coal tar is easy to volatilize at high temperature, and the adsorption effect of diatomaceous earth helps to fix the tar on the carrier surface, reducing the volatilization loss under high temperature conditions and ensuring a higher recovery rate of chlorine content in the measurement process.

[0131] 3) Avoid sample coking or agglomeration: Direct heating of coal tar may cause the sample to coke or agglomerate at high temperatures, affecting the release of chlorine. Diatomaceous earth can effectively adsorb and disperse tar, reduce such phenomena, and ensure complete decomposition of the sample.

[0132] 4) Reduce interference from impurities: Diatomaceous earth is chemically inert and will not react with components in coal tar, thus reducing the interference of impurities on the measurement results, making it particularly suitable for precise measurement by ion chromatography.

[0133] 5) Improve the repeatability and stability of the measurement: Fixing the sample with diatomaceous earth makes the sample processing conditions consistent, improves the repeatability of the experiment and the stability of the data, and is suitable for batch analysis and standardized operations.

[0134] Certain features of the present technology are further illustrated in the following non-limiting examples.

[0135] Some of the instruments and raw materials involved in the following examples and comparative examples are as follows:

[0136] 1. Crucible: porcelain, capacity 30mL-50mL.

[0137] 2. Silver nitrate solution: 10 g / L. Weigh 1 g of silver nitrate and dissolve it in 100 mL of distilled water, then add 2 mL of 1 mol / L dilute nitric acid solution.

[0138] 3. Muffle furnace: equipped with temperature control device, can be heated to 1000℃, and has good ventilation.

[0139] 4. Electromagnetic stirrer: speed 500r / min, continuously adjustable, temperature can be increased.

[0140] 5. Analytical balance: sensitivity 0.1 mg.

[0141] 6. Ion Chromatograph: Ion Chromatograph model DIONEX AQ-1100 produced by Thermo Fisher Scientific.

[0142] 7. Diatomaceous earth: Diatomaceous earth produced by Tianjin Zhonglian Chemical Reagent Co., Ltd. is an analytically pure reagent (AR).

[0143] Example 1

[0144] The method for determining the chlorine content of coal tar using a diatomaceous earth carrier in this embodiment comprises the following steps:

[0145] Step 1: Determination of chlorine content in coal tar

[0146] The determination of chlorine content in coal tar includes the following steps:

[0147] (1) Accurately weigh (0.3±0.05) g (weighed to 0.0002 g) of the general analysis test coal tar sample, put it into a crucible containing 0.7 g (weighed to 0.01 g) of diatomaceous earth, and mix it carefully to obtain the first sample (i.e., the diatomaceous earth-tar mixed sample). Then weigh 3 g (weighed to 0.1 g) of the axelrodite mixture and mix it evenly with the first sample in the above crucible, and finally cover it evenly with 2 g of the axelrodite mixture to obtain the second sample.

[0148] The coal tar sample was bituminous coal from Hami, Xinjiang (the industrial analysis and elemental analysis are shown in Table 1 and Table 2, respectively). 2 Coal tar is obtained by pyrolysis at 600℃ for 30min under atmosphere. The Eschka mixture is a mixture of light magnesium oxide and anhydrous sodium carbonate in a mass ratio of 2:1. Diatomaceous earth, light magnesium oxide and anhydrous sodium carbonate are all analytically pure reagents (AR).

[0149] Table 1 Industrial analysis of coal tar samples (wt.%, ad)

[0150] coal M V A FC HM 5.37 44.79 4.08 45.76

[0151] Note: In Table 1, M is moisture, V is volatile matter, A is ash, FC is fixed carbon, and HM stands for Hami.

[0152] Table 2 Elemental analysis of coal tar samples (wt.%, ad)

[0153] coal C H O N S <![CDATA[Cl d ]]> HM 67.66 4.79 17.20 0.76 0.14 0.193

[0154] Note: HM in Table 2 stands for Hami.

[0155] (2) Place the crucible containing the second sample into a muffle furnace, half-open the furnace door, and gradually raise the furnace temperature from room temperature (25°C) to 150°C at a heating rate of 15°C in an air atmosphere, and keep it warm for 30 minutes to remove volatile substances and moisture in the sample; continue to raise the temperature to 600°C at a heating rate of 15°C and keep it warm for 3 hours to promote the decomposition of tar and the release of chlorine; finally, raise the temperature to 850°C at a heating rate of 15°C and keep it warm for 30 minutes to ensure complete reaction of the sample and sufficient release of chlorine element, thereby obtaining a burnt product, wherein the burnt product is placed in the crucible.

[0156] (3) The crucible containing the burnt material was taken out of the muffle furnace and cooled to room temperature (25°C). The burnt material in the crucible was transferred into a 250 mL beaker. The crucible wall was rinsed with 100 mL of distilled water and poured into the beaker. The beaker was placed on an electromagnetic stirrer and rapidly stirred at a speed of 500 r / min for 30 min and the temperature was raised to 80°C to obtain a mixed solution.

[0157] (4) The mixed solution obtained in step (3) is filtered with qualitative filter paper by decantation method to obtain residue and filtrate. Subsequently, the residue is rinsed twice with hot distilled water at 80°C to obtain a first rinse solution and a rinsed residue. The rinsed residue is then transferred into a funnel, and the qualitative filter paper and the rinsed residue are carefully rinsed with hot distilled water at 80°C until there is no chloride ion (no turbidity is detected by silver nitrate solution), to obtain a second rinse solution. Finally, the filtrate, the first rinse solution and the second rinse solution are fixed to 250 mL and the chloride ion content in the solution is determined by ion chromatograph.

[0158] (5) Accurately weigh 0.7g (weighed to 0.01g) of diatomaceous earth and put it into a crucible, then weigh 3g (weighed to 0.1g) of the first Eschka mixture and mix it evenly with the diatomaceous earth in the above crucible, and finally cover it evenly with 2g of the second Eschka mixture to obtain a sample. Subsequently, replace the "above crucible containing the second sample" in step (2) with "the above crucible containing the sample", repeat steps (2) to (4), and perform blank value determination to ensure the accuracy of the experimental results (blank value determination is to eliminate the influence of chlorine in Eschka reagent and diatomaceous earth). The blank value determination result is 0.7459wt%. After deducting the blank value determination result, the chloride ion content test calculation result of step (4) is 0.0876wt%.

[0159] (6) Step (1) to step (4) were repeated three times. The calculated results of the three chloride ion content tests were 0.0868 wt%, 0.0873 wt%, and 0.0889 wt%, respectively.

[0160] (7) The average value of the calculated results of four tests, 0.0877 wt %, was taken as the measured value of the final chlorine content in the coal tar to be tested in this example.

[0161] Step 2: Sample spike recovery chlorine experiment

[0162] Pipette 1 mL of 1 mg / mL chlorine standard and add it to the coal tar sample of step (1) of step 1, and repeat steps (1) to (6) for determination.

[0163] The spiked recovery rates were 93.45%, 104.08%, 101.28% and 96.29% respectively. It can be seen that the results of the chloride ion content in the coal tar sample tested by the method for determining the chlorine content of coal tar using the diatomaceous earth carrier of this embodiment meet the requirements of ion chromatography (ion chromatography requires that the method error for determining the chlorine content in water is within 10%).

[0164] Example 2 (Compared with Example 1, the coal tar sample is CO 2 obtained by gasification at 600℃ under atmosphere)

[0165] This embodiment is basically the same as Embodiment 1, except that:

[0166] In step 1:

[0167] In step (1), the coal tar sample is bituminous coal from Hami, Xinjiang, in CO 2 Coal tar obtained by gasification at 600℃ for 30min under atmosphere.

[0168] In step (5), the blank value measurement result is 0.8632wt%, and the chloride ion content test calculation result of step (4) is 0.1449wt%.

[0169] In step (6), steps (1) to (4) are repeated three times, and the calculated results of the three chloride ion content tests are 0.1415wt%, 0.1499wt%, and 0.1553wt%, respectively.

[0170] In step (7), the average value of the calculated results of four tests, 0.1479 wt %, is taken as the final measured value of the chlorine content in the coal tar to be tested.

[0171] In step 2:

[0172] The test spiked recoveries were 94.52%, 98.79%, 105.63% and 96.95% respectively.

[0173] Comparative Example 1

[0174] This comparative example is basically the same as Example 1, except that:

[0175] Excluding step 2 and steps (6)-(7) in step 1, and:

[0176] In step 1:

[0177] In step (1), diatomaceous earth is not contained. Specifically: Accurately weigh a general analytical test coal tar sample (bituminous coal from Hami, Xinjiang, N 2 Coal tar (1.0±0.05) g (weighed to 0.0002 g) obtained by pyrolysis at 600°C for 30 min under an atmosphere is placed in a crucible containing 3 g (weighed to 0.1 g) of a mixture of aliphatic carbs (due to the lack of adsorbent diatomaceous earth, the adsorption effect of the mixture of aliphatic carbs on coal tar is weak, and coal tar may agglomerate during mixing, resulting in poor dispersion effect), and mixed to obtain a first sample; then 2 g of the mixture of aliphatic carbs is evenly covered to obtain a second sample. The rest is the same as step (1) of Example 1.

[0178] In step (2), the heating program "from room temperature (25°C) to 150°C at a heating rate of 15°C and keeping warm for 30 minutes to remove volatile substances and moisture in the sample; continue to heat to 600°C at a heating rate of 15°C and keep warm for 3 hours to promote the decomposition of tar and the release of chlorine; finally, heat to 850°C at a heating rate of 15°C and keep warm for 30 minutes to ensure complete reaction of the sample and sufficient release of chlorine element" is replaced by heating from room temperature (25°C) to (680±20)°C and heating at this temperature for 3 hours.

[0179] Step (5) is: accurately weigh 3g (weighed to 0.1g) of Eschka mixture into a crucible, then cover it with 2g of Eschka mixture, then send the crucible into a muffle furnace, half-open the furnace door, gradually raise the furnace temperature from room temperature to (680±20)°C, and heat at this temperature for 3 hours. Then repeat steps (3) to (4) to perform blank value determination to ensure the accuracy of the experimental results (blank value determination is to eliminate the influence of chlorine in Eschka reagent). The blank value determination result is 0.3209wt%. After deducting the blank value determination result, the chloride ion content test calculation result of step (4) is 0.0593wt%, and the test calculation result is used as the measured value of the chlorine content in the coal tar of this comparative example.

[0180] Comparative Example 2

[0181] This comparative example is basically the same as Example 2, except that:

[0182] Excluding step 2 and steps (6)-(7) in step 1, and:

[0183] In step 1:

[0184] In step (1), diatomaceous earth is not contained. Specifically: Accurately weigh a general analytical test coal tar sample (bituminous coal from Hami, Xinjiang in CO 2 Coal tar (1.0±0.05) g (weighed to 0.0002 g) obtained by gasification at 600°C for 30 min under atmosphere was placed in a crucible containing 3 g (weighed to 0.1 g) of a mixture of acrylonitrile (due to the lack of adsorbent diatomaceous earth, the adsorption effect of the mixture of acrylonitrile on coal tar was weak, and coal tar may agglomerate during mixing, resulting in poor dispersion effect), and mixed to obtain the first sample; then 2 g of the mixture of acrylonitrile was evenly covered to obtain the second sample. The rest was the same as step (1) of Example 2.

[0185] In step (2), the heating program "from room temperature (25°C) to 150°C at a heating rate of 15°C and keeping warm for 30 minutes to remove volatile substances and moisture in the sample; continue to heat to 600°C at a heating rate of 15°C and keep warm for 3 hours to promote the decomposition of tar and the release of chlorine; finally, heat to 850°C at a heating rate of 15°C and keep warm for 30 minutes to ensure complete reaction of the sample and sufficient release of chlorine element" is replaced by heating from room temperature (25°C) to (680±20)°C and heating at this temperature for 3 hours.

[0186] Step (5) is: accurately weigh 3g (weighed to 0.1g) of Eschka mixture into a crucible, then cover it with 2g of Eschka mixture, then send the crucible into a muffle furnace, half-open the furnace door, gradually raise the furnace temperature from room temperature to (680±20)°C, and heat at this temperature for 3 hours. Then repeat steps (3) to (4) to perform blank value determination to ensure the accuracy of the experimental results (blank value determination is to eliminate the influence of chlorine in Eschka reagent). The blank value determination result is 0.4013wt%. After deducting the blank value determination result, the chloride ion content test calculation result of step (4) is 0.0689wt%, and the test calculation result is used as the measured value of the chlorine content in the coal tar of this comparative example.

[0187] By comparing Example 1 and Comparative Example 1, as well as Example 2 and Comparative Example 2, it can be seen that, under the same coal tar sample conditions, by adopting the determination method of the present application, the stronger adsorption capacity of diatomaceous earth increases the release rate of chlorine, reduces the volatilization loss of chlorine, ensures the complete decomposition of the coal tar sample, and improves the accuracy of the experimental results.

[0188] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0189] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0190] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for determining the chlorine content of coal tar using a diatomaceous earth carrier, characterized in that: include: The coal tar and diatomaceous earth are first mixed to obtain a first sample; The first sample and the first Eschka mixture are mixed for a second time and then covered with the second Eschka mixture to obtain a second sample; The second sample is subjected to a first heat treatment, a second heat treatment and a third heat treatment in sequence, and then cooled to obtain a burnt product; the temperature of the first heat treatment, the temperature of the second heat treatment and the temperature of the third heat treatment are increased in sequence; The burnt product was dispersed in a solvent, then filtered, washed, and tested for chloride ion content.

2. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The mass ratio of the coal tar to the diatomaceous earth is 1:(1-3).

3. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The first aishaka mixture and the second aishaka mixture both include light magnesium oxide and anhydrous sodium carbonate, and the mass ratio of the light magnesium oxide to the anhydrous sodium carbonate is (2-3):

1.

4. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The mass ratio of the first Aishkar mixture to the first sample is (2-3):1; and / or, The mass ratio of the first aishka mixture to the second aishka mixture is (2-4):(1-3).

5. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The temperature of the first heat treatment is 100-150° C.; and / or, The temperature of the second heat treatment is 550-650° C.; and / or, The temperature of the third heat treatment is 800-850°C.

6. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The time of the first heat treatment is 30-60 minutes, and the heating rate of the first heat treatment is 10-20° C. / min; and / or, The duration of the second heat treatment is 1-4 hours, and the heating rate of the second heat treatment is 10-20° C. / min; and / or, The duration of the third heat treatment is 15-45 min, and the heating rate of the third heat treatment is 10-20° C. / min; and / or, The first heat treatment, the second heat treatment and the third heat treatment are all performed in an air atmosphere.

7. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The first mixing and the second mixing are both performed in a first container, and the second sample is present in the first container.

8. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 7, characterized in that: The solvent includes one of distilled water, deionized water and purified water; and / or, The burning material is dispersed in a solvent, then filtered, washed, and tested for chloride ion content, including: transferring the burnt material into a second container to obtain a second container containing the burnt material; flushing the wall of the first container with a solvent to obtain a mixed solution; The mixed solution is poured into the second container containing the burning material, followed by stirring, heating, and filtering with filter paper by a pouring method to obtain a residue and a filtrate; Washing the residue at least once with the hot solvent to obtain a first washing liquid and washed residue; Subsequently, the washed residue is transferred into a funnel, and the filter paper and the washed residue are washed with the hot solvent until no chloride ions are present, thereby obtaining a second washing solution; The filtrate, the first flushing liquid and the second flushing liquid are mixed, fixed to volume, and the chloride ion content is tested.

9. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to claim 1, characterized in that: The method for testing the chloride ion content comprises one of ion chromatography, potentiometric titration and potassium thiocyanate titration; and / or, The method for determining the chlorine content of coal tar using a diatomaceous earth carrier further comprises the step of mixing the diatomaceous earth with the first aishkar mixture and then covering the mixture with the second aishkar mixture as a blank value for determination; and / or, The method for determining the chlorine content of coal tar using a diatomaceous earth carrier further comprises the steps of testing the chloride ion content multiple times in parallel and taking the average value of the chloride ion content test results multiple times as the final test value of the chlorine content in the coal tar; and / or, The method for determining the chlorine content of coal tar using a diatomaceous earth carrier also includes the step of adding a chlorine standard sample to the coal tar for testing.

10. The method for determining the chlorine content of coal tar using a diatomaceous earth carrier according to any one of claims 1 to 9, characterized in that: The coal tar is coal tar obtained by pyrolysis or gasification under an inert gas or carbon dioxide gas atmosphere.

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