A method for purifying toluene and its application

Abstract

This invention discloses a method for purifying toluene and its application. The method includes: catalytic conversion of toluene using a porous metal catalyst in an acidic environment below 60°C; and then mixing the converted liquid with an alkaline solution for separation to obtain purified toluene. This method converts non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene into smaller molecules or acidic substances, which are then removed by alkaline washing. When toluene is used in nitration reactions, it reduces the content of fatty acids and benzoic acids during the nitration process, preventing non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons from converting into carboxylic acid emulsion impurities during nitration, thus reducing the risk of emulsification in the nitration reaction.

Description

Technical Field

[0001] This invention relates to the technical field of toluene purification, and more specifically to a method for purifying toluene and its application. Background Technology

[0002] Toluene is the main raw material for the production of dinitrotoluene (DNT) and is widely used in explosives, polyurethane foam raw materials, and other organic synthesis intermediates. In industrial production, refining from petroleum cracking products is one of the important sources of toluene. Toluene refining involves removing and separating light and heavy components through distillation column purification. However, in distillation column purification, it is extremely difficult to completely remove non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbon impurities with boiling points close to toluene.

[0003] The non-aromatic hydrocarbons in toluene mainly include dimethylcyclohexane, n-octane, methylheptadiene, dimethylcyclohexene, ethylcyclohexene, and ethylcyclohexane. C8 / C9 aromatic hydrocarbons mainly include ethylbenzene, xylene, and trimethylbenzene. During nitration, non-aromatic hydrocarbons are easily oxidized to fatty acids under acidic conditions. C8 / C9 aromatic hydrocarbons, due to the influence of multiple methyl groups, are more reactive than toluene and readily undergo oxidation to form methylbenzoic acid compounds. Fatty acids and methylbenzoic acid impurities contain both hydrophilic and lipophilic groups. When toluene containing both non-aromatic and C8 / C9 aromatic hydrocarbons is used as a raw material, it easily causes the water and oil phases to form an emulsion during nitration, making phase separation impossible for subsequent processes, forcing plant shutdown and resulting in significant economic losses.

[0004] Therefore, it is essential to remove non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons with boiling points close to toluene. Currently, the existing technologies for removing non-aromatic compounds with boiling points close to toluene typically involve membrane separation (see patent application CN 114206813 A) and physical adsorption (see patent application CN 1403426A). Membrane separation requires high-quality membranes and has high separation costs; physical adsorption is limited to removing high-content, alkaline non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons, and its removal efficiency for other substances is not ideal. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is how to efficiently remove low contents of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons from toluene, reduce the emulsification risk of nitration reaction, and provide a solution to the above problem.

[0006] A method for purifying toluene, comprising:

[0007] Toluene is catalytically converted using a porous metal catalyst in an acidic environment below 60°C. The converted liquid is then mixed with an alkaline solution and separated to obtain purified toluene.

[0008] The porous material metal catalyst is a porous material loaded with a metal active component. The mass percentage of the metal active component in the porous material is 1% to 30%, preferably 5% to 15%. For example, the mass percentage of the metal active component in the porous material is 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, etc.

[0009] And / or, the average particle size of the catalyst is 4 to 16 μm, preferably 8 to 16 μm, for example: average particle size of 4 μm, 7 μm, 9 μm, 11 μm, 13 μm, 16 μm, etc.;

[0010] And / or, the specific surface area of ​​the catalyst is 500–800 m². 2 / g, for example: specific surface area of ​​500m² 2 / g、550m 2 / g、、600m 2 / g、650m 2 / g、700m 2 / g、750m 2 / g、800m 2 / g etc.

[0011] The active metal component includes one or more of tantalum, chromium, aluminum, zirconium, and molybdenum; typical but non-limiting combinations of the active metal component include combinations of tantalum, chromium, and aluminum; combinations of tantalum, zirconium, and molybdenum; combinations of zirconium, aluminum, and molybdenum; and combinations of tantalum, chromium, aluminum, zirconium, and molybdenum.

[0012] Preferably, the catalyst contains 0.5-10% tantalum, preferably 3-5%, for example, tantalum content of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; 0-5% chromium, preferably 0.5-2%, for example, 0.5%, 1%, 1.5%, 2%, etc.; and 0-5% aluminum, preferably 1-2%, for example, aluminum content of 0. 5%, 1%, 2%, 3%, 4%, 5%, etc.; zirconium content 0.5%–10%, preferably 1%–2.5%, for example: zirconium content 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; molybdenum content 0.5%–10%, preferably 4%–6.5%, for example: molybdenum content 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc. When calculating the percentage composition, the percentage content of the active ingredient refers to the mass of the metal element represented by the active component in the compound containing the active component. For example, if tantalum exists in the form of tantalum silicate, the percentage content of tantalum is calculated only based on the mass of "tantalum element" within it.

[0013] More preferably, the tantalum element is selected from any one or a combination of two or more of sodium tantalate, ammonium tantalate, tantalum oxalate, tantalum fluoride, or tantalum iodide; the chromium element is selected from any one or a combination of two or more of chromium nitrate, chromium sulfate, chromium chloride, potassium chromate, sodium chromate, or ammonium chromate; the aluminum element is selected from any one or a combination of two or more of aluminum chloride, aluminum sulfate, or aluminum nitrate; the zirconium element is selected from any one or a combination of two or more of zirconium nitrate, zirconium sulfate, basic ammonium zirconium carbonate, or zirconium oxychloride; and the molybdenum element is selected from any one or a combination of two or more of molybdenum nitrate, potassium molybdate, sodium molybdate, or ammonium molybdate.

[0014] And / or, the porous material includes one or more of diatomaceous earth, zeolite, porous alumina, and porous silica.

[0015] Preferably, the average particle size of the porous material is 3–16 μm; and / or, the specific surface area of ​​the porous material is 500–800 m². 2 / g.

[0016] The preparation process of the porous metal catalyst is as follows: a catalyst precursor is obtained by surface modification of polymer and metal ions using porous materials, and the catalyst precursor is sintered and activated to obtain the porous metal catalyst.

[0017] The surface modification process is as follows: the polymer raw material, the metal ion raw material, and the porous material are mixed to obtain a mixture, ammonia water is added dropwise to the mixture to adjust the pH to 8-11, the mixture is stirred and polymerized, the solid and liquid are separated, the mixture is washed with deionized water until neutral, and dried to obtain the catalyst precursor.

[0018] And / or, the sintering activation process is as follows: treatment at 350-450℃ for 2-3 hours in an inert gas environment;

[0019] And / or, the mass ratio of the effective substance to the porous material in the raw materials of the polymer is 1:(1-50);

[0020] And / or, the more metal ions the raw material contains, the more metal ions theoretically can be loaded in the porous material, and the better its performance. However, based on a comprehensive consideration of cost and performance, the mass ratio of the metal ions raw material to the porous material in this invention is preferably 1:(0.5~7); for example, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, etc.

[0021] And / or, the raw materials of the polymer include at least one of methylcyclohexanol, methylcyclohexylamine, methylaniline, diaminotoluene, and dopamine hydrochloride; the raw materials of the polymer are preferably TDA hydrogenation wastewater and dopamine hydrochloride; the TDA hydrogenation wastewater in this invention usually includes any one or more combinations of methylcyclohexanol, methylcyclohexylamine, methylaniline, and diaminotoluene in a total content of no more than 5%.

[0022] The dopamine hydrochloride undergoes a self-polymerization reaction under weakly alkaline conditions. During the reaction, the surface of the porous material is modified by the polymer, and metal ions are loaded into the porous material.

[0023] The inert gas includes any one or more of nitrogen, helium, argon, or carbon dioxide;

[0024] And / or, the temperature for stirring polymerization is 20–35°C, and the stirring polymerization time is 4–12 h.

[0025] The catalytic conversion process is as follows: toluene, porous metal catalyst and dilute acid are mixed to obtain a mixed system, stirred and reacted, and the layers are separated to obtain primary toluene;

[0026] And / or, the mixing and separation process is as follows: primary toluene is mixed with alkaline solution, stirred and washed, and then allowed to stand for separation to obtain purified toluene.

[0027] In the mixed system, the amount of catalyst added is 0.5-5% of the mass of toluene, preferably 2.5-5%, for example: the amount of catalyst added is 0.5%, 1%, 2%, 3%, 4%, 5% of the mass of toluene, etc.; and / or, the mass concentration of the dilute acid is 0.5-10 wt%, and the mass of the acid in the dilute acid is 1%-15% of the mass of toluene;

[0028] And / or, the dilute acid is any one or more of dilute nitric acid, dilute sulfuric acid, and dilute nitrous acid;

[0029] And / or, the temperature of the stirring reaction is 30–60°C, preferably 40–50°C;

[0030] And / or, the stirring reaction time is 3 to 15 minutes, preferably 5 to 10 minutes.

[0031] The alkaline solution is one or more of ammonia water, sodium hydroxide solution, and potassium hydroxide solution;

[0032] And / or, the pH value during the stirring and washing is 7.5 to 11, preferably 8 to 9;

[0033] And / or, the temperature during the stirring and washing process is 30–60°C, preferably 40–50°C;

[0034] And / or, the time for stirring and washing is 3 to 15 minutes, preferably 5 to 10 minutes.

[0035] The purified toluene obtained by the above treatment method is used as a raw material in the nitration reaction.

[0036] The technical solution of this invention has the following advantages:

[0037] 1. The method provided by this invention uses porous materials to prepare a catalyst. Toluene and the obtained catalyst are mixed in an acidic environment to obtain a mixed system. After filtering the mixed system to obtain solid particles, primary toluene is obtained. The primary toluene is then washed with alkali to obtain purified toluene. This invention's processing method converts non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene into small molecules such as carbon dioxide and water, or acidic substances such as fatty acids and benzoic acid. These are removed by alkaline washing to obtain purified toluene. When the purified toluene is used in a nitration reaction, the content of fatty acids and benzoic acid-like substances is reduced during the nitration process. This avoids the conversion of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons into carboxylic acid emulsion impurities during the nitration reaction, thus reducing the risk of emulsification in the nitration reaction.

[0038] 2. This invention achieves the purification of raw material toluene, and through temperature control, ensures that there is almost no loss of raw material toluene during the processing. Detailed Implementation

[0039] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0040] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0041] In the following examples, the toluene was obtained from the DNT section of the TDI production unit of Wanhua Chemical Group Co., Ltd., and the total amount of non-aromatic hydrocarbons and C8 / C9 aromatic compounds in the toluene was 302 ppm.

[0042] The TDA hydrogenation wastewater comes from the TDA section of the TDI production unit of Wanhua Chemical Group Co., Ltd., and includes 0.02% methylcyclohexanol, 0.01% methylcyclohexylamine, 0.01% methylaniline, and 0.01% diaminotoluene.

[0043] Example 1

[0044] 5.3g sodium tantalate, 2.1g chromium nitrate, and 4.5g aluminum nitrate were weighed and dissolved in 100g deionized water. The metal salts were fully dissolved under stirring. 30g porous silica was added, followed by 5g dopamine hydrochloride and 100g TDA hydrogenation wastewater. 15wt% ammonia was slowly added dropwise to adjust the pH to 9. Polymerization was carried out at 25℃ for 6 hours. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 400℃ under a nitrogen atmosphere for 2.5 hours, and then cooled to room temperature to obtain catalyst A. Catalyst parameters were measured using a Bettersize 2600 laser particle size analyzer, a Minix surface area and pore size analyzer, and an ARL-OPTIMX X-ray fluorescence analyzer. The X-ray fluorescence analysis used a 400W X-ray tube in a helium atmosphere. The average particle size of the catalyst was found to be 10μm, and the specific surface area was 760m². 2 / g, with tantalum content of 9.2%, chromium content of 0.89%, and aluminum content of 1.1%.

[0045] In a 1L mixed-stage reactor, 200g of toluene, 200g of 5% nitric acid solution, and 8g of catalyst A prepared according to the above steps were added. The mixture was stirred at 1100rpm at 40℃. After reacting for 10 minutes, the mixture was allowed to stand in a separator for 5 minutes to obtain primary toluene. The primary toluene was returned to the reactor and washed with 100mL of ammonia water, maintaining the pH at 9 and the temperature at 40℃ for 7 minutes with stirring. The purified toluene a was obtained after standing.

[0046] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene a was 35 ppm.

[0047] Example 2

[0048] 5.3g sodium tantalate, 1.5g zirconium nitrate, and 1.2g molybdenum nitrate were weighed and dissolved in 100g deionized water. The metal salts were fully dissolved under stirring. 30g zeolite was added, followed by 6g dopamine hydrochloride and 100g TDA hydrogenation wastewater. 15wt% ammonia was slowly added dropwise to adjust the pH to 8.5. Polymerization was carried out at 25℃ for 6 hours. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 350℃ under an argon atmosphere for 3 hours, and then cooled to room temperature to obtain catalyst B. The catalyst was tested and found to have an average particle size of 12μm and a specific surface area of ​​630m². 2 / g, tantalum content is 8.4%, zirconium content is 0.88%, and molybdenum content is 1.4%.

[0049] In a 1L mixed stirred tank reactor, 200g of toluene, 200g of a mixed solution of 1.0% nitric acid and 0.5% nitrous acid, and 10g of catalyst B prepared according to the above steps were added. The mixture was stirred at 1100rpm at 45℃. After reacting for 10 minutes, the mixture was allowed to stand in a separator for 5 minutes to obtain primary toluene. The primary toluene was returned to the reactor, washed with 100mL of ammonia water, maintaining the pH at 9, the temperature at 45℃, and the stirring and washing time for 7 minutes. The purified toluene b was obtained after standing.

[0050] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene b was 22 ppm.

[0051] Example 3

[0052] 5.3 g of sodium tantalate, 4.2 g of aluminum nitrate, and 3.2 g of molybdenum nitrate were weighed and dissolved in 100 g of deionized water. The metal salts were fully dissolved under stirring. 30 g of porous silica was added, followed by 7 g of dopamine hydrochloride and 100 g of TDA hydrogenation wastewater. 15 wt% ammonia was slowly added dropwise to adjust the pH to 9. Polymerization was carried out at 25 °C for 12 h. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 450 °C under a nitrogen and carbon dioxide atmosphere for 2 h, and then cooled to room temperature to obtain catalyst C. The catalyst was tested and found to have an average particle size of 16 μm and a specific surface area of ​​510 m². 2 / g, tantalum content is 8.9%, aluminum content is 1.1%, and molybdenum content is 5.7%.

[0053] In a 1L mixed-stage reactor, 200g of toluene, 200g of 5% sulfuric acid solution, and 8g of catalyst C prepared according to the above steps were added. The mixture was stirred at 1100rpm at 50℃. After reacting for 8 minutes, the mixture was allowed to stand in a separator for 5 minutes to obtain primary toluene. The primary toluene was returned to the reactor and washed with 100mL of ammonia water, maintaining the pH at 8.5, the temperature at 50℃, and the stirring and washing time for 7 minutes. The purified toluene c was then obtained after standing.

[0054] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene C was 46 ppm.

[0055] Example 4

[0056] 4.5 g of sodium tantalate and 3.1 g of molybdenum nitrate were dissolved in 100 g of deionized water and stirred until the metal salts were fully dissolved. 30 g of diatomaceous earth was added, followed by 6 g of dopamine hydrochloride and 100 g of TDA hydrogenation wastewater. 15 wt% ammonia was slowly added dropwise to the mixture to adjust the pH to 8.5. Polymerization was carried out at 25 °C for 6 h. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 400 °C under a helium atmosphere for 2.5 h, and then cooled to room temperature to obtain catalyst D. The catalyst was tested and found to have an average particle size of 14 μm, a specific surface area of ​​630 m² / g, a tantalum content of 7.6%, and a molybdenum content of 5.7%.

[0057] In a 1L mixed-stage reactor, 200g of toluene, 200g of 7% nitric acid solution, and 6g of catalyst D prepared according to the above steps were added. The mixture was stirred at 1100rpm at 35°C. After reacting for 10 minutes, the mixture was allowed to stand in a separator for 5 minutes to separate into primary toluene. The primary toluene was returned to the reactor and washed with 100mL of sodium hydroxide solution, maintaining the pH at 9 and the temperature at 40°C for 7 minutes with stirring. The purified toluene d obtained after standing was then collected.

[0058] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene d was 38 ppm.

[0059] Example 5

[0060] 0.4 g of sodium tantalate and 4.2 g of chromium nitrate were dissolved in 100 g of deionized water under stirring until the metal salts were fully dissolved. 30 g of porous alumina was added, followed by 6 g of dopamine hydrochloride and 100 g of TDA hydrogenation wastewater. 15 wt% ammonia was slowly added dropwise to adjust the pH to 10, and polymerization was carried out at 35 °C for 4 h. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 400 °C under a nitrogen atmosphere for 2.5 h, and then cooled to room temperature to obtain catalyst E. The catalyst was tested and found to have an average particle size of 4 μm and a specific surface area of ​​560 m². 2 / g, with a tantalum content of 0.5% and a chromium content of 2%.

[0061] In a 1L mixed-stage reactor, 200g of toluene, 200g of 15% nitric acid solution, and 5g of catalyst E prepared according to the above steps were added. The mixture was stirred at 1100rpm at 60℃. After reacting for 3 minutes, the mixture was allowed to stand in a separator for 5 minutes to obtain primary toluene. The primary toluene was returned to the reactor and washed with 100mL of ammonia water, maintaining the pH at 11, the temperature at 60℃, and the stirring and washing time for 15 minutes. The purified toluene e was obtained after standing.

[0062] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene was 77 ppm.

[0063] Example 6

[0064] 3.2g sodium tantalate, 10g chromium nitrate, 18g aluminum nitrate, 7.5g zirconium nitrate, and 5g molybdenum nitrate were weighed and dissolved in 200g deionized water. The metal salts were fully dissolved under stirring. 30g porous silica was added, followed by 12g dopamine hydrochloride and 100g TDA hydrogenation wastewater. 15wt% ammonia was slowly added dropwise to adjust the pH to 11. Polymerization was carried out at 20℃ for 6 hours. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 400℃ under a nitrogen atmosphere for 2.5 hours, and then cooled to room temperature to obtain catalyst F. The catalyst was tested and found to have an average particle size of 8μm and a specific surface area of ​​640m². 2 / g, with tantalum content of 5%, chromium content of 5%, aluminum content of 5%, zirconium content of 5%, and molybdenum content of 10%.

[0065] In a 1L mixed-stage reactor, 200g of toluene, 200g of 5% nitric acid solution, and 5g of catalyst F prepared according to the above steps were added. The mixture was stirred at 1100rpm at 30℃. After reacting for 15min, the mixture was allowed to stand in a separator for 5min to obtain primary toluene. The primary toluene was returned to the reactor, washed with 100mL of ammonia water, maintaining the pH at 7.5 and the temperature at 30℃ for 3min of stirring and washing. The purified toluene f was obtained after standing.

[0066] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene f was 20 ppm.

[0067] Example 7

[0068] The difference between this embodiment and Example 1 is that the polymer raw material used in the catalyst precursor is only dopamine hydrochloride, that is, TDA hydrogenation wastewater is replaced with water; otherwise, it is the same as Example 1. The catalyst was tested and found to have an average particle size of 10 μm and a specific surface area of ​​730 m². 2 / g, tantalum content is 9.0%, chromium content is 0.82%, and aluminum content is 0.99%.

[0069] After purification, a sample of toluene was taken and tested. The total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons was 39 ppm.

[0070] Example 8

[0071] The difference between this embodiment and Example 2 is that the amount of dopamine hydrochloride used as the polymer precursor in this embodiment is 0.6 g; otherwise, it is the same as in Example 2. The catalyst was tested and found to have an average particle size of 10 μm and a specific surface area of ​​520 m². 2 / g, with tantalum content of 4.4%, zirconium content of 0.48%, and molybdenum content of 0.81%.

[0072] After purification, a sample of toluene was taken and tested. The total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons was 66 ppm.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 4 is that the amount of catalyst D added in the 1L fully mixed batch reactor is 1g, while the rest is the same as in embodiment 4.

[0075] After purification, a sample of toluene was taken for testing, and the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons was 57 ppm.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that 200g of toluene and 200g of 5% nitric acid solution were added to a 1L mixed batch reactor, but the prepared catalyst A was not added. The stirring speed was controlled at 1100rpm at 40°C. The purified toluene j was obtained after standing.

[0078] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene j was 289 ppm.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that no supported metal salt was added during the catalyst preparation process, resulting in catalyst H. The purified toluene k obtained after standing was then processed.

[0081] The preparation process of catalyst H was as follows: 30g of the same porous silica as in Example 1 was added to 100g of deionized water, followed by 5g of dopamine hydrochloride and 100g of TDA hydrogenation wastewater. 15wt% ammonia was slowly added dropwise to the mixture to adjust the pH to 9, and polymerization was carried out at 25°C with stirring for 6 hours. The solid and liquid phases were separated, washed with deionized water until neutral, and dried to obtain the catalyst precursor. The catalyst precursor was calcined at 400°C under a nitrogen atmosphere for 2.5 hours, and then cooled to room temperature to obtain catalyst H. The catalyst H was tested and found to have an average particle size of 11μm and a specific surface area of ​​780m². 2 / g.

[0082] Sampling tests showed that the total content of non-aromatic hydrocarbons and C8 / C9 aromatic hydrocarbons in toluene K was 284 ppm.

[0083] Test example:

[0084] Weigh out 15g of concentrated nitric acid, 5g of water and 60g of concentrated sulfuric acid to make a mononitrated mixed acid. Add 14g of toluene purified in the examples and comparative examples and 36g of mononitrated mixed acid. Stir the mixture at 55°C for 10min and let it stand to separate into layers. The separation time is shown in Table 1 below.

[0085] Table 1

[0086] Stratification Time Example 1 41s Example 2 34s Example 3 48s Example 4 43s Example 5 79s Example 6 33s Example 7 46s Example 8 78s Example 9 65s Comparative Example 1 ＞180s Comparative Example 2 ＞180s

[0087] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for purifying toluene, characterized in that, include: Toluene is catalytically converted using a porous metal catalyst in an acidic environment below 60°C. The converted liquid is then mixed with an alkaline solution and separated to obtain purified toluene. The porous metal catalyst is a porous material supported on a metal active component, wherein the mass percentage of the metal active component in the porous material is 1-30%; the average particle size of the catalyst is 4-16 μm; and the specific surface area of ​​the catalyst is 500-800 m². 2 / g; the active metal component includes one or more of tantalum, chromium, aluminum, zirconium and molybdenum.

2. The processing method according to claim 1, characterized in that, The mass percentage of the metal active component in the porous material is 5-15%. And / or, the average particle size of the catalyst is 8–16 μm.

3. The processing method according to claim 2, characterized in that, The porous material includes one or more of diatomaceous earth, zeolite, porous alumina, and porous silica.

4. The processing method according to any one of claims 1-3, characterized in that, The preparation process of the porous metal catalyst is as follows: a catalyst precursor is obtained by surface modification of polymer and metal ions using porous materials, and the catalyst precursor is sintered and activated to obtain the porous metal catalyst.

5. The processing method according to claim 4, characterized in that, The surface modification process is as follows: the polymer raw material, the metal ion raw material, and the porous material are mixed to obtain a mixture, ammonia water is added dropwise to the mixture to adjust the pH to 8-11, the mixture is stirred and polymerized, the solid and liquid are separated, the mixture is washed with deionized water until neutral, and dried to obtain the catalyst precursor. And / or, the sintering activation process is as follows: treatment at 350-450℃ for 2-3 hours in an inert gas environment; And / or, the mass ratio of the effective substance to the porous material in the raw materials of the polymer is 1:(1-50); And / or, the mass ratio of the metal ion raw material to the porous material is 1:(0.5~7). And / or, the raw materials for the polymer include at least one of methylcyclohexanol, methylcyclohexylamine, methylaniline, diaminotoluene, and dopamine hydrochloride.

6. The processing method according to claim 5, characterized in that, The inert gas includes any one or more of nitrogen, helium, argon, or carbon dioxide; And / or, the temperature for stirring polymerization is 20–35°C, and the stirring polymerization time is 4–12 h.

7. The processing method according to any one of claims 1-3, characterized in that, The catalytic conversion process is as follows: toluene, porous metal catalyst and dilute acid are mixed to obtain a mixed system, stirred and reacted, and the layers are separated to obtain primary toluene; And / or, the mixing and separation process is as follows: primary toluene is mixed with alkaline solution, stirred and washed, and then allowed to stand for separation to obtain purified toluene.

8. The processing method according to claim 7, characterized in that, In the aforementioned mixture, the amount of catalyst added is 0.5% to 5% of the mass of toluene; And / or, the mass concentration of the dilute acid is 0.5 to 10 wt%, and the mass of the acid in the dilute acid is 1% to 15% of the mass of toluene; And / or, the dilute acid is any one or more of dilute nitric acid, dilute sulfuric acid, and dilute nitrous acid; And / or, the temperature of the stirred reaction is 30–60°C; And / or, the stirring reaction time is 3 to 15 minutes.

9. The processing method according to claim 8, characterized in that, In the aforementioned mixture, the amount of catalyst added is 2.5% to 5% of the mass of toluene; And / or, the temperature of the stirred reaction is 40–50°C; And / or, the stirring reaction time is 5 to 10 minutes.

10. The processing method according to claim 7, characterized in that, The pH value during the stirring and washing process is 7.5–11; And / or, the temperature during the stirring and washing process is 30–60°C; And / or, the time for the stirring and washing is 3 to 15 minutes.

11. The processing method according to claim 10, characterized in that, The pH value during the agitation and washing process is 8-9; And / or, the temperature during the stirring and washing process is 40–50°C; And / or, the time for the stirring and washing is 5 to 10 minutes.