A method and system for preparing quaternary ammonium salt modified heteropolyacid catalyst

Abstract

The invention provides a preparation method of a quaternary ammonium salt modified heteropoly acid catalyst: a tungsten-containing compound or a molybdenum-containing compound is mixed with an alkali solution and reacted to obtain a first reaction liquid; the first reaction liquid is vacuum concentrated and crystallized to obtain an intermediate liquid, the intermediate liquid is separated, the obtained crystals are dissolved by pure water, and a phosphoric acid compound is added after the crystals are dissolved to obtain a second reaction liquid; the second reaction liquid is subjected to salt ion removal treatment, and after desalination, a quaternary ammonium salt compound is added to obtain a third reaction liquid; the third reaction liquid is centrifuged and dried to obtain a quaternary ammonium salt modified heteropoly acid catalyst. The invention uses common tungsten-containing compounds and molybdenum-containing compounds as raw materials to prepare heteropoly acids, and the raw material sources are wide, the tungsten / molybdenum element content is high, and the raw material utilization rate is higher; on the basis of the preparation method, a preparation system for a quaternary ammonium salt modified heteropoly acid catalyst is also provided.

Description

Technical Field

[0001] The invention relates to a method for preparing a heteropolyacid catalyst, and in particular to a method and a system for preparing a quaternary ammonium salt modified heteropolyacid catalyst. Background Art

[0002] Heteropolyacid is a kind of solid proton acid with higher acid strength than concentrated sulfuric acid. It is a general term for oxygen-containing acids formed by condensation of oxides of at least one heteroatom among transition metal elements such as Mo, W, V and oxygen-containing acids of other elements such as P, Si, As, Ge, Ti, Ce, etc. The atomic ratio between the two is 2.5-12, preferably 9 or 12. It is divided into hexameric acid, nonameric acid and dodecaned acid. For example: phosphotungstic acid, silicotungstic acid, silicomolybdic acid, etc. The cage structure of heteropolyacid molecules is characterized by the fact that single molecules can freely enter and exit its cage structure during the catalytic reaction and present a pseudo-liquid phase state. Heteropolyacids have the properties of both proton acids and Lewis acids, with stable structures, easy solubility in water and a variety of organic solvents, especially in organic solvents, where their acid strength is higher, and they are easy to separate and recycle, so they can be used as catalysts for the polymerization of tetrahydrofuran (THF).

[0003] Heteropolyacids have a large solubility in polar solvents (such as water) and are difficult to recycle in polar reaction systems. Therefore, heteropolyacids are currently used as solid acids by loading and ion modification. Loading heteropolyacids on carriers such as SiO2, activated carbon, ion exchange resins or macroporous molecular sieves with high specific surface areas can enhance the stability of heteropolyacid catalysts in polar reaction systems and increase the specific surface area of ​​the catalyst.

[0004] The existing methods and processes for preparing quaternary ammonium salt-modified heteropolyacid catalysts mainly have the following technical defects: ① The quality of the produced catalyst is poor. Since the current preparation process has a long process flow, complex purification procedures, and requires repeated purification, the impurities in the obtained product are not completely removed and the product quality cannot be guaranteed; ② The existing process has a large amount of three wastes discharged. Since the current preparation process is complicated and fails to fully consider green and energy-saving technologies such as material recycling and zero emission, it not only greatly increases the consumption of materials and energy, but also causes the generation of a large amount of wastewater and waste salt, which is a high-energy-consuming and non-environmentally friendly process. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the present invention first provides a method for preparing a quaternary ammonium salt modified heteropolyacid catalyst, which is carried out according to the following steps:

[0006] Step 1: fully reacting a tungsten-containing compound or a molybdenum-containing compound with an alkali solution having a mass fraction of 5% to 40% to obtain a first reaction solution with a pH of 9 to 11, wherein the molar ratio of the tungsten-containing compound or the molybdenum-containing compound in the reactant to the alkali in the alkali solution is 1:1 to 1:5;

[0007] The tungsten-containing compound in step 1 of the present application is one or more of tungsten trioxide, ammonium paratungstate, and sodium paratungstate. The molybdenum-containing compound is one or more of molybdenum oxide, ammonium paramolybdate, and sodium paramolybdate. The alkali solution is one or more of sodium hydroxide and potassium hydroxide solution;

[0008] Step 2: Concentrate and crystallize the first reaction solution obtained in step 1 to obtain an intermediate solution with a solid-liquid ratio of 1:1 to 5:1; the intermediate solution obtained in step 2 is a concentrated solution of the solution containing sodium tungstate solution, the solution containing potassium tungstate solution, the solution containing sodium molybdate solution, or the solution containing potassium molybdate solution obtained after the reaction in step 1;

[0009] Step 3: After centrifuging the intermediate solution obtained in step 2, the mother solution and crystals are separated, and the crystals are dissolved in pure water to obtain a solution with a mass fraction of 5% to 30%. The target solute of the first reaction solution with high purity, i.e., sodium tungstate crystals, potassium tungstate crystals, sodium molybdate crystals, or potassium molybdate crystals, can be obtained by centrifugation.

[0010] Step 4, adding a phosphoric acid compound to the solution obtained in step 3 to react, controlling the molar ratio of tungsten or molybdenum to phosphorus to be 11-13:1, and obtaining a second reaction solution after sufficient reaction; the phosphoric acid compound in step 4 is one or more of phosphoric acid, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium phosphate, and potassium phosphate, and the main component of the second reaction solution obtained in step 4 is heteropolyacid phosphotungstate or phosphomolybdate.

[0011] Step 5, the second reaction solution obtained in step 4 is subjected to salt ion removal, and quaternary ammonium salt compounds are added in the second reaction solution after removing the salt ions, and the third reaction solution is obtained after fully reacting, wherein the quaternary ammonium salt compound addition amount and the mol ratio of heteropolyacid are 1~6:1. The salt ion removed in step 5 is mainly sodium ion or potassium ion, and in step 5, quaternary ammonium salt compounds are one or more of hexadecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, tetrabutyl ammonium chloride, hexadecyl trimethyl ammonium bromide, dodecyl trimethyl ammonium bromide and tetrabutyl ammonium bromide. The composition of the third reaction solution obtained after step 5 reaction ends is quaternary ammonium salt modified heteropolyacid catalyst solution, and according to the different materials added in the aforementioned steps, the third reaction solution is one or more of tetrabutyl modified phosphotungstic acid, tetrabutyl modified phosphomolybdic acid, hexadecyl trimethyl modified phosphotungstic acid, hexadecyl trimethyl modified phosphomolybdic acid, dodecyl trimethyl modified phosphotungstic acid and dodecyl trimethyl modified phosphomolybdic acid.

[0012] Step 6: Centrifuge and dry the third reaction solution to obtain a quaternary ammonium salt-modified heteropolyacid catalyst.

[0013] In addition, the present application also provides a preparation system for preparing a quaternary ammonium salt-modified heteropolyacid catalyst by the above method, comprising: a first reactor, a second reactor, a third reactor, and a fourth reactor arranged in sequence; a filter is arranged between the first reactor and the second reactor; a centrifugal device is arranged between the second reactor and the third reactor, the centrifugal mother liquor outlet of the centrifugal device is connected to the inlet of the second reactor, and the centrifugal crystal outlet of the centrifugal device is connected to the inlet of the third reactor; an ion removal device is arranged between the third reactor and the fourth reactor, the inlet of the ion removal device is connected to the third reactor, and the main feed liquid outlet of the ion removal device is connected to the inlet of the fourth reactor; a centrifugal washing device and a drying device are arranged in sequence after the fourth reactor.

[0014] The ion removal device of the present application is an ion exchange column or a bipolar membrane electrodialysis device.

[0015] Furthermore, when bipolar membrane electrodialysis equipment is used to remove ions, in order to achieve the recycling of materials, the outlet of the alkali solution of the ion removal device is connected to the inlet of the first reactor to achieve the reuse of the recovered sodium hydroxide / potassium hydroxide.

[0016] The preparation system of the present application improves the purity of materials in the reaction process through filters, centrifugal devices, ion removal devices, centrifugal washing equipment, etc.

[0017] Furthermore, in order to realize the recycling of pure water, the centrifugal washing liquid outlet of the centrifugal washing equipment is connected to the inlet of the pure water preparation system, the second reactor is connected to the cooler, and the cooler is connected to the vacuum pump through the storage tank. This process is used for condensation recovery of water vapor; the outlet of the condensed water in the storage tank is connected to the inlet of the pure water preparation system. The outlet of the pure water preparation system is connected to at least any inlet of the first reactor, the third reactor, and the centrifugal washing equipment.

[0018] In addition, the system also includes an exhaust gas purification system for recovering and purifying the exhaust gas generated by the first reactor.

[0019] The technical effects of the present invention are:

[0020] 1. The main raw materials used in the preparation method of the quaternary ammonium salt modified heteropolyacid catalyst provided by the present application, tungsten compounds and molybdenum-containing compounds, are common substances with a wide range of raw material sources. The present application uses processes such as concentration crystallization and centrifugation to prepare a quaternary ammonium salt modified heteropolyacid catalyst with a high tungsten or molybdenum content and a higher raw material utilization rate. The tungsten or molybdenum content in the quaternary ammonium salt modified heteropolyacid catalyst prepared by the present invention accounts for 27% to 71%, and the purity of the quaternary ammonium salt modified heteropolyacid catalyst prepared by the present invention can reach 99.99%.

[0021] 2. The preparation system provided in the present application is equipped with a pure water preparation system and an exhaust gas recovery system. The system can realize the recycling of materials, greatly reduce the consumption of auxiliary materials, reduce energy consumption indicators, greatly improve the process conversion rate and product yield, and avoid the emission of waste gas, wastewater and solid waste salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0023] In the figure, there are a first reactor 1, a second reactor 2, a third reactor 3, a fourth reactor 4, a filter 5, a cooler 11, a storage tank 12, a vacuum pump 13, a centrifugal device 6, an ion removal device 7, a centrifugal washing device 8, a drying device 9, a pure water preparation system 10, a delivery pump 14, and an exhaust gas recovery and purification system 15. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention and the drawings in the embodiments to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] The present application provides a method for preparing a quaternary ammonium salt modified heteropolyacid catalyst, comprising the following steps:

[0026] Step 1: fully reacting a tungsten-containing compound or a molybdenum-containing compound with an alkali solution having a mass concentration of 5% to 40% to obtain a first reaction solution with a pH of 9 to 11, wherein the molar ratio of the tungsten compound or the molybdenum compound in the reactant to the alkali in the alkali solution is 1:1 to 1:5;

[0027] Step 2: Concentrate and crystallize the first reaction solution obtained in step 1 to obtain an intermediate solution with a solid-liquid ratio of 1:1 to 5:1;

[0028] Step 3: Centrifuge the intermediate solution obtained in step 2 to separate the mother solution and crystals, and use pure water to dissolve the crystals to obtain a solution with a mass concentration of 5% to 30%;

[0029] Step 4: adding a phosphoric acid compound to the solution obtained in step 3 to react, controlling the molar ratio of tungsten or molybdenum to phosphorus to be 11-13:1, and obtaining a second reaction solution after sufficient reaction;

[0030] Step 5, removing salt ions from the second reaction solution obtained in step 4, and adding a quaternary ammonium salt compound to the second reaction solution after the salt ions are removed, and obtaining a third reaction solution after sufficient reaction, wherein the molar ratio of the quaternary ammonium salt compound added to the heteropolyacid is 1 to 6:1;

[0031] Step 6: Centrifuge and dry the third reaction solution to obtain a quaternary ammonium salt-modified heteropolyacid catalyst.

[0032] According to the present invention, in step 1, a tungsten-containing compound or a molybdenum-containing compound and an alkali solution are first used to obtain a first reaction solution. In the present invention, the tungsten-containing compound can be selected from one or more of tungsten trioxide, ammonium paratungstate, and sodium paratungstate. The molybdenum-containing compound can be selected from one or more of molybdenum oxide, ammonium paramolybdate, and sodium paramolybdate. The alkali solution can be selected from one or more of sodium hydroxide and potassium hydroxide solutions, wherein the mass concentration of the alkali solution can be selected from 5% to 40%, such as 5%, 10%, 20%, 40%, etc. The reaction conditions selected in step 1 can achieve sufficient reaction, such as the reaction temperature can be selected from 10°C to 100°C, and the reaction time can be adjusted according to actual conditions.

[0033] In some embodiments of the present invention, when the tungsten-containing compound in step one is one or more of tungsten trioxide, ammonium paratungstate, and sodium paratungstate, and the alkali solution is a sodium hydroxide solution, the first reaction liquid obtained by the reaction is a solution containing at least sodium tungstate; when the tungsten-containing compound in step one is one or more of tungsten trioxide, ammonium paratungstate, and sodium paratungstate, and the alkali solution is a potassium hydroxide solution, the first reaction liquid obtained by the reaction is a solution containing at least potassium tungstate; when the molybdenum-containing compound in step one is one or more of molybdenum oxide, ammonium paramolybdate, and sodium paramolybdate, and the alkali solution is a sodium hydroxide solution, the first reaction liquid obtained by the reaction is a solution containing at least sodium molybdate; when the molybdenum-containing compound in step one is one or more of molybdenum oxide, ammonium paramolybdate, and sodium paramolybdate, and the alkali solution is a potassium hydroxide solution, the first reaction liquid obtained by the reaction is a solution containing at least potassium molybdate;

[0034] According to the present invention, after the first reaction solution is obtained in step 1, the intermediate solution obtained in step 2 is a concentrated solution of the solution containing sodium tungstate solution or the solution containing potassium tungstate solution or the solution containing sodium molybdate solution or the solution containing potassium molybdate solution obtained after the reaction in step 1;

[0035] According to the present invention, in step three, the target solute of the first reaction solution can be obtained by centrifugation with high purity, namely, sodium tungstate crystals or potassium tungstate crystals or sodium molybdate crystals or potassium molybdate crystals.

[0036] According to the present invention, in step 4, a phosphoric acid compound is added to the solution obtained in step 3 for reaction, and a second reaction solution is obtained after sufficient reaction; the phosphoric acid compound in step 4 can be selected from one or more of phosphoric acid, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium phosphate, and potassium phosphate, and the main component of the second reaction solution obtained in step 4 is heteropolyacid phosphotungstate or phosphomolybdate.

[0037] According to the present invention, in step 5, the second reaction solution obtained in step 4 is subjected to salt ion removal, and a quaternary ammonium salt compound is added to the second reaction solution after the salt ions are removed, and a third reaction solution is obtained after sufficient reaction, wherein the salt ions removed in step 5 are mainly sodium ions or potassium ions, and the quaternary ammonium salt compound in step 5 can be selected from one or more of hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetrabutylammonium chloride, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and tetrabutylammonium bromide.

[0038] In an optional embodiment of the present invention, the component of the third reaction liquid obtained after the reaction in step five is a quaternary ammonium salt-modified heteropolyacid catalyst solution. Depending on the materials added in the previous steps, the third reaction liquid is one or more of tetrabutyl-modified phosphotungstic acid, tetrabutyl-modified phosphomolybdic acid, hexadecyltrimethyl-modified phosphotungstic acid, hexadecyltrimethyl-modified phosphomolybdic acid, dodecyltrimethyl-modified phosphotungstic acid, and dodecyltrimethyl-modified phosphomolybdic acid.

[0039] According to the present invention, in step six, the third reaction solution obtained in step five is centrifuged and dried to obtain a quaternary ammonium salt-modified heteropolyacid catalyst.

[0040] The present invention, by the above method, first prepares the first reaction solution, then carries out condensing crystallization, separation and purification, and obtains the high-purity first reaction solution after the high-purity crystal after separation is dissolved, then obtains the second reaction solution containing heteropoly acid salt phosphotungstate or phosphomolybdate after the high-purity first reaction solution and phosphoric acid compound are reacted, and the salt ions in the second reaction solution are removed and then quaternary ammonium salt compounds are added to obtain quaternary ammonium salt modified heteropoly acid catalyst solution, and finally by centrifugation, dry after available quaternary ammonium salt modified heteropoly acid catalyst. By the scheme of the application, the quaternary ammonium salt modified heteropoly acid catalyst prepared has high tungsten or molybdenum element content and higher raw material utilization.

[0041] Please refer to Figure 1 The present invention also provides a preparation system for a quaternary ammonium salt-modified heteropolyacid catalyst used in the above preparation method, comprising:

[0042] A first reactor 1, a second reactor 2, a third reactor 3, and a fourth reactor 4 are arranged in sequence; a filter 5 is arranged between the first reactor 1 and the second reactor 2; a centrifugal device 6 is arranged between the second reactor 2 and the third reactor 3, the centrifugal mother liquor outlet of the centrifugal device 6 is connected to the inlet of the second reactor 2, and the crystal outlet of the centrifugal device is connected to the inlet of the third reactor 3; an ion removal device 7 is arranged between the third reactor 3 and the fourth reactor 4, the inlet of the ion removal device 7 is connected to the third reactor 3, and the main feed liquid outlet of the ion removal device 7 is connected to the inlet of the fourth reactor 4; a centrifugal washing device 8 and a drying device 9 are arranged in sequence after the fourth reactor 4.

[0043] In the embodiment of the present invention, the first reactor 1, the second reactor 2, the third reactor 3, and the fourth reactor 4 are all provided with multiple feed ports, discharge ports, heat preservation devices, and stirring devices. The multiple inlets of the first reactor 1 are used to add tungsten-containing compounds or molybdenum-containing compounds and alkali solution, the temperature of the first reactor 1 is controllable, and the first reactor 1 is also provided with an exhaust gas outlet.

[0044] The principles of the second reactor 2, the third reactor 3, and the fourth reactor 4 are the same as those of the first reactor 1. In the first reactor 1, the second reactor 2, the third reactor 3, and the fourth reactor 4 which are arranged in sequence, materials at different steps in the reaction process pass through the first reactor 1, the second reactor 2, the third reactor 3, and the fourth reactor 4 in sequence.

[0045] The second reactor 2 is used for concentration and crystallization, and vacuum concentration and crystallization are performed. Therefore, the second reactor is connected to the cooler 11, and the cooler 11 is connected to the vacuum pump 13 through the storage tank 12. The vapor pressure in the second reactor is reduced by the vacuum pump, so that the crystallization temperature of the substance in the second reactor can be reduced, thereby achieving vacuum concentration and crystallization of crystals.

[0046] The filter 5 is used to filter the incompletely reacted or incompletely dissolved substances in the first reaction kettle 1 , and the centrifugal device 6 is used to separate the crystals and the mother liquor after crystallization in the second reaction kettle 2 .

[0047] The ion removal device 7 is used to remove metal salt ions, and the ion removal device 7 can be selected as an ion exchange column or a bipolar membrane electrodialysis.

[0048] The device in the above embodiment is applied to the preparation method of the quaternary ammonium salt modified heteropolyacid catalyst, and the implementation process is as follows:

[0049] Step 1: adding a tungsten-containing compound or a molybdenum-containing compound and an alkali solution with a mass concentration of 5% to 40% into a first reaction kettle 1, wherein the molar ratio of the tungsten compound or the molybdenum compound to the alkali in the alkali solution in the first reaction kettle 1 is 1:1 to 1:5, the reaction temperature is controlled at 10 to 100° C., and the reaction is stirred for 0.1 to 6 hours to obtain a first reaction solution with a pH of 9 to 11;

[0050] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The vacuum concentration temperature of the second reaction kettle 2 is controlled to be 90-150° C. The vacuum degree in the second reaction kettle 2 is controlled to be 0-100 kPa by the vacuum pump 13. After the vacuum concentration time is 0.5-5 h, an intermediate liquid with a solid-liquid ratio of 1:1-5:1 is obtained;

[0051] Step 3: adding the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquid and the crystals, returning the mother liquid to the second reaction kettle 2, and sending the crystals to the third reaction kettle 3, dissolving the crystals with pure water to obtain a solution with a mass concentration of 5% to 30%;

[0052] Step 4: Add a phosphoric acid compound to the third reaction kettle 3 containing the solution obtained in step 3, control the molar ratio of tungsten or molybdenum to phosphorus to be 11-13:1, control the reaction temperature of the third reaction kettle 3 to be 5-100° C., and control the reaction time to be 0.5-4 h to obtain a second reaction solution after sufficient reaction;

[0053] Step 5, passing the second reaction solution obtained in step 4 into an ion removal device 7 for salt ion removal treatment, removing the salt ions in the second reaction solution, and after desalination, sending the second reaction solution after the salt ions are removed into a fourth reactor 4; and adding a quaternary ammonium salt compound to the fourth reactor 4 containing the second reaction solution, so that the molar ratio of the quaternary ammonium salt compound to the heteropolyacid is 1-6:1, controlling the reaction temperature in the fourth reactor 4 at 5-80°C, the reaction time is 0.5-4h, and after fully stirring the reaction, obtaining a third reaction solution;

[0054] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain a quaternary ammonium salt-modified heteropolyacid catalyst.

[0055] Based on the above embodiments, in some embodiments of the present invention, the centrifugal washing liquid outlet of the centrifugal washing equipment 8 is connected to the inlet of the pure water preparation system 10, and the outlet of the pure water preparation system 10 is connected to at least any inlet of the first reactor, the third reactor, and the centrifugal washing equipment 8.

[0056] like Figure 1The centrifugal washing liquid outlet of the centrifugal washing equipment 8 is connected to the inlet of the pure water preparation system 10 , and the outlet of the pure water preparation system 10 is connected to the inlets of the first reactor 1 , the third reactor 3 , and the centrifugal washing equipment 8 .

[0057] Through this implementation scheme, the liquid after centrifugation becomes pure water after passing through the pure water preparation system 10. The pure water can be reused in the first reactor 1 to carry out the reaction of step one, the pure water can be reused in the third reactor 3 to carry out the reaction of step four, and the pure water can be reused in the centrifugal washing equipment 8 to carry out the centrifugal washing operation of step six.

[0058] Furthermore, the outlet of the condensed water in the storage tank 12 is connected to the inlet of the pure water preparation system 10, thereby realizing the recycling of the condensed water obtained after cooling the steam after low-pressure evaporation in the concentration and crystallization process of step 2.

[0059] The system can realize the recycling of materials, greatly reduce the consumption of auxiliary materials, realize the recycling of wastewater, and avoid the discharge of wastewater.

[0060] Furthermore, when the ion removal device 7 selects bipolar membrane electrodialysis, the alkali solution recovered in the process of removing salt ions can be reused in the first reactor 1 to react with the tungsten-containing compound or the molybdenum-containing compound. The water after centrifugal washing can be purified by a pure water preparation system. Thus, the recycling of materials is realized, the consumption of auxiliary materials is greatly reduced, the energy consumption index is reduced, the process conversion rate and product yield are greatly improved, and the discharge of wastewater and solid waste salt is avoided.

[0061] The present invention is illustrated below by using a specific preparation system to prepare a method for preparing a quaternary ammonium salt modified heteropolyacid catalyst.

[0062] Example 1

[0063] Step 1: 304 kg of ammonium paratungstate and 480 kg of sodium hydroxide solution with a mass concentration of 20% are added to the first reaction kettle 1, so that the molar ratio of the tungsten compound in the first reaction kettle 1 to the alkali in the sodium hydroxide solution is 1:2, the reaction temperature is controlled at 80°C, and the reaction is stirred for 2 hours to obtain 766 kg of the first reaction liquid with a pH of 10;

[0064] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 100° C. The vacuum degree in the second reaction kettle 2 is controlled to be 10 kPa through the vacuum pump 13. After vacuum concentration for 2 hours, an intermediate liquid with a solid-liquid ratio of 4:1 is obtained;

[0065] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 353 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals with pure water, and obtain 2353 kg of a solution with a mass concentration of 15%;

[0066] Step 4: Add 9.8 kg of phosphoric acid to the third reaction kettle 3 containing the solution obtained in step 3, control the molar ratio of tungsten to phosphorus to be 12:1, control the reaction temperature of the third reaction kettle 3 to be 25° C., and the reaction time to be 1 h. After sufficient reaction, 2363 kg of the second reaction liquid is obtained, which is the sodium phosphotungstate reaction liquid;

[0067] Step 5: Pass the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment to remove sodium ions in the second reaction liquid, and send the second reaction liquid after the sodium ions are removed into the fourth reactor 4; and add 96.6 kg of tetrabutylammonium bromide to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of tetrabutylammonium bromide to heteropolyacid is 3:1, control the reaction temperature in the fourth reactor 4 at 50°C, the reaction time is 1h, and after fully stirring the reaction, obtain 2460 kg of the third reaction liquid, which is the tetrabutyl modified phosphotungstic acid reaction liquid;

[0068] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into the centrifugal washing device 8 for centrifugation, and dried by the drying device 9 to obtain 360.3 kg of quaternary ammonium salt-modified heteropolyacid catalyst tetrabutyl-modified phosphotungstic acid.

[0069] Example 2

[0070] Step 1: 116 kg of ammonium heptamolybdate and 280 kg of a sodium hydroxide solution with a mass concentration of 20% are added to the first reaction kettle 1, so that the molar ratio of the molybdenum compound in the first reaction kettle 1 to the alkali in the sodium hydroxide solution is 1:2, the reaction temperature is controlled at 80° C., and the reaction is stirred for 2 hours to obtain 385 kg of a first reaction liquid with a pH of 10;

[0071] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 100° C. The vacuum degree in the second reaction kettle 2 is controlled to be 10 kPa through the vacuum pump 13. After vacuum concentration for 2 hours, an intermediate liquid with a solid-liquid ratio of 4:1 is obtained;

[0072] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 288 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals in pure water, and obtain 1920 kg of a solution with a mass concentration of 15%;

[0073] Step 4: Add 5.7 kg of phosphoric acid to the third reactor 3 containing the solution obtained in step 3, control the molar ratio of molybdenum to phosphorus to be 12:1, control the reaction temperature of the third reactor 3 to be 25 ° C, the reaction time to be 1 h, and obtain 1926 kg of the second reaction liquid after sufficient reaction, the second reaction liquid is sodium phosphomolybdate reaction liquid;

[0074] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment, removing the sodium ions in the second reaction liquid, and sending the second reaction liquid after the sodium ions are removed into the fourth reactor 4; and adding 67.6 kg of tetrabutylammonium bromide to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of tetrabutylammonium bromide to heteropolyacid is 3:1, controlling the reaction temperature in the fourth reactor 4 at 50 ° C, the reaction time is 1h, and after fully stirring the reaction, 1993 kg of the third reaction liquid is obtained, and the third reaction liquid is tetrabutyl modified phosphomolybdic acid reaction liquid;

[0075] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain 201.3 kg of quaternary ammonium salt-modified heteropolyacid catalyst tetrabutyl-modified phosphomolybdic acid.

[0076] Example 3

[0077] Step 1: 304 kg of ammonium paratungstate and 672 kg of potassium hydroxide solution with a mass concentration of 20% are added to the first reaction kettle 1, so that the molar ratio of the tungstate compound in the first reaction kettle 1 to the alkali in the potassium hydroxide solution is 1:2, the reaction temperature is controlled at 90°C, and the reaction is stirred for 2 hours to obtain 958 kg of the first reaction liquid with a pH of 10;

[0078] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 100° C. The vacuum degree in the second reaction kettle 2 is controlled to be 10 kPa through the vacuum pump 13. After vacuum concentration for 2 hours, an intermediate liquid with a solid-liquid ratio of 4:1 is obtained;

[0079] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 391 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals with pure water, and obtain 2607 kg of a solution with a mass concentration of 15%;

[0080] Step 4: Add 17.4 kg of dipotassium hydrogen phosphate to the third reaction kettle 3 containing the solution obtained in step 3, control the molar ratio of tungsten to phosphorus to be 12:1, control the reaction temperature of the third reaction kettle 3 to be 25° C., and the reaction time to be 1 h. After sufficient reaction, 2624 kg of the second reaction liquid is obtained, which is potassium phosphotungstate reaction liquid;

[0081] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal equipment 8 for salt ion removal treatment, removing potassium ions in the second reaction liquid, and sending the second reaction liquid after potassium ions are removed into the fourth reactor 4; and adding 96kg of hexadecyltrimethylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of hexadecyltrimethylammonium chloride to heteropolyacid is 3:1, controlling the reaction temperature in the fourth reactor 4 at 50°C, the reaction time is 1h, and after fully stirring the reaction, 2720kg of the third reaction liquid is obtained, and the third reaction liquid is the hexadecyltrimethyl modified phosphotungstic acid reaction liquid;

[0082] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain 372.9 kg of quaternary ammonium salt-modified heteropolyacid catalyst hexadecyltrimethyl modified phosphotungstic acid.

[0083] Example 4

[0084] Step 1: 116 kg of ammonium heptamolybdate and 392 kg of a potassium hydroxide solution with a mass concentration of 20% are added to the first reaction kettle 1, so that the molar ratio of the molybdenum compound to the alkali in the potassium hydroxide solution in the first reaction kettle 1 is 1:2, the reaction temperature is controlled at 90° C., and the reaction is stirred for 2 hours to obtain 497 kg of a first reaction liquid with a pH of 10;

[0085] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 100° C. The vacuum degree in the second reaction kettle 2 is controlled to be 10 kPa through the vacuum pump 13. After vacuum concentration for 2 hours, an intermediate liquid with a solid-liquid ratio of 4:1 is obtained;

[0086] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 167 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals in pure water, and obtain 1113 kg of a solution with a mass concentration of 15%;

[0087] Step 4: Add 5.7 kg of phosphoric acid to the third reactor 3 containing the solution obtained in step 3, control the molar ratio of molybdenum to phosphorus to be 12:1, control the reaction temperature of the third reactor 3 to be 25 ° C, the reaction time to be 1 h, and obtain 1119 kg of the second reaction liquid after sufficient reaction, the second reaction liquid is potassium phosphomolybdate reaction liquid;

[0088] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal equipment 8 for salt ion removal treatment, removing potassium ions in the second reaction liquid, and sending the second reaction liquid after the potassium ions are removed into the fourth reactor 4; and adding 67.2kg of hexadecyltrimethylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of hexadecyltrimethylammonium chloride to heteropolyacid is 3:1, controlling the reaction temperature in the fourth reactor 4 at 50°C, the reaction time is 1h, and after fully stirring the reaction, 1186kg of the third reaction liquid is obtained, and the third reaction liquid is the hexadecyltrimethyl modified phosphomolybdic acid reaction liquid;

[0089] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain 243.7 kg of quaternary ammonium salt-modified heteropolyacid catalyst hexadecyltrimethyl modified phosphomolybdic acid.

[0090] Example 5

[0091] Step 1: Add 232kg of tungsten trioxide and 400kg of 20% sodium hydroxide solution into the first reaction kettle 1, so that the molar ratio of tungsten trioxide in the first reaction kettle 1 to the alkali in the sodium hydroxide solution is 1:2, control the reaction temperature to 90°C, stir and react for 2h, and obtain 632kg of the first reaction liquid with a pH of 10;

[0092] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 100° C. The vacuum degree in the second reaction kettle 2 is controlled to be 10 kPa through the vacuum pump 13. After vacuum concentration for 2 hours, an intermediate liquid with a solid-liquid ratio of 4:1 is obtained;

[0093] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 294 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals in pure water, and obtain 1960 kg of a solution with a mass concentration of 15%;

[0094] Step 4: Add 13.7 kg of sodium phosphate to the third reaction kettle 3 containing the solution obtained in step 3, control the molar ratio of tungsten to phosphorus to be 12:1, control the reaction temperature of the third reaction kettle 3 to be 25° C., and the reaction time to be 1 h. After sufficient reaction, 1974 kg of the second reaction liquid is obtained, which is the sodium phosphotungstate reaction liquid;

[0095] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment, removing the sodium ions in the second reaction liquid, and sending the second reaction liquid after the sodium ions are removed into the fourth reactor 4; and adding 66kg of dodecyltrimethylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of dodecyltrimethylammonium chloride to heteropolyacid is 3:1, controlling the reaction temperature in the fourth reactor 4 at 50°C, the reaction time is 1h, and after fully stirring the reaction, 2040kg of the third reaction liquid is obtained, and the third reaction liquid is the dodecyltrimethyl modified phosphotungstic acid reaction liquid;

[0096] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into the centrifugal washing device 8 for centrifugation, and dried by the drying device 9 to obtain 296.7 kg of quaternary ammonium salt-modified heteropoly acid dodecyltrimethyl modified phosphotungstic acid.

[0097] Example 6

[0098] Step 1: 144 kg of molybdenum oxide and 560 kg of a potassium hydroxide solution with a mass concentration of 20% are added to the first reaction kettle 1, so that the molar ratio of the molybdenum compound to the alkali in the potassium hydroxide solution in the first reaction kettle 1 is 1:2, the reaction temperature is controlled at 90° C., and the reaction is stirred for 2 hours to obtain 704 kg of a first reaction liquid with a pH of 10;

[0099] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 100° C. The vacuum degree in the second reaction kettle 2 is controlled to be 10 kPa through the vacuum pump 13. After vacuum concentration for 2 hours, an intermediate liquid with a solid-liquid ratio of 4:1 is obtained;

[0100] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 238 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals with pure water, and obtain 1587 kg of a solution with a mass concentration of 15%;

[0101] Step 4: Add 17.1 kg of potassium phosphate to the third reactor 3 containing the solution obtained in step 3, control the molar ratio of molybdenum to phosphorus to be 12:1, control the reaction temperature of the third reactor 3 to be 25 ° C, the reaction time to be 1 h, and obtain 1604 kg of the second reaction liquid after sufficient reaction, the second reaction liquid is potassium phosphomolybdate reaction liquid;

[0102] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal equipment 8 for salt ion removal treatment, removing potassium ions in the second reaction liquid, and sending the second reaction liquid after the potassium ions are removed into the fourth reactor 4; and adding 66kg of dodecyltrimethylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of dodecyltrimethylammonium chloride to heteropolyacid is 3:1, controlling the reaction temperature in the fourth reactor 4 at 50°C, the reaction time is 1h, and after fully stirring the reaction, 1670kg of the third reaction liquid is obtained, and the third reaction liquid is the dodecyltrimethyl modified phosphomolybdic acid reaction liquid;

[0103] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain 210.3 kg of quaternary ammonium salt-modified heteropoly acid dodecyltrimethyl modified phosphomolybdic acid.

[0104] Example 7

[0105] Step 1: Add 232kg of tungsten trioxide and 1600kg of 5% sodium hydroxide solution into the first reaction kettle 1, so that the molar ratio of tungsten trioxide in the first reaction kettle 1 to the alkali in the sodium hydroxide solution is 1:1, control the reaction temperature at 100°C, stir the reaction for 6 hours, and obtain 1832kg of the first reaction liquid with a pH of 9;

[0106] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 90° C. The vacuum degree in the second reaction kettle 2 is controlled to be 50 kPa through the vacuum pump 13. After vacuum concentration for 3 hours, an intermediate liquid with a solid-liquid ratio of 1:1 is obtained;

[0107] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 294 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals in pure water, and obtain 5580 kg of a solution with a mass concentration of 5%;

[0108] Step 4: Add 12 kg of disodium hydrogen phosphate to the third reaction kettle 3 containing the solution obtained in step 3, control the molar ratio of tungsten to phosphorus to be 11:1, control the reaction temperature of the third reaction kettle 3 to be 5° C., and the reaction time to be 4 h. After sufficient reaction, 5892 kg of the second reaction liquid is obtained, which is the sodium phosphotungstate reaction liquid;

[0109] Step 5: Pass the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment to remove sodium ions in the second reaction liquid, and send the second reaction liquid after the sodium ions are removed into the fourth reactor 4; and add 22kg of dodecyltrimethylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of dodecyltrimethylammonium chloride to heteropolyacid is 1:1, control the reaction temperature in the fourth reactor 4 at 5°C, the reaction time is 4h, and after fully stirring the reaction, 5914kg of the third reaction liquid is obtained, and the third reaction liquid is the dodecyltrimethyl modified phosphotungstic acid reaction liquid;

[0110] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into the centrifugal washing device 8 for centrifugation, and dried by the drying device 9 to obtain 258.9 kg of quaternary ammonium salt modified heteropoly acid dodecyltrimethyl modified phosphotungstic acid.

[0111] Example 8

[0112] Step 1: 144 kg of molybdenum oxide and 280 kg of a sodium hydroxide solution with a mass concentration of 40% are added to the first reaction kettle 1, so that the molar ratio of the molybdenum compound to the alkali in the sodium hydroxide solution in the first reaction kettle 1 is 1:5, the reaction temperature is controlled at 100° C., and the reaction is stirred for 0.1 h to obtain 424 kg of a first reaction liquid with a pH of 11;

[0113] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 150° C. The vacuum degree in the second reaction kettle 2 is controlled to be 100 kPa through the vacuum pump 13. After vacuum concentration for 5 hours, an intermediate liquid with a solid-liquid ratio of 1:5 is obtained;

[0114] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 206 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals with pure water, and obtain 687 kg of a solution with a mass concentration of 30%;

[0115] Step 4: Add 13.7 kg of sodium phosphate to the third reactor 3 containing the solution obtained in step 3, control the molar ratio of molybdenum to phosphorus to be 13:1, control the reaction temperature of the third reactor 3 to be 100 ° C, the reaction time to be 0.5 h, and obtain 700 kg of the second reaction liquid after sufficient reaction, the second reaction liquid is sodium phosphomolybdate reaction liquid;

[0116] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment, removing the sodium ions in the second reaction liquid, and sending the second reaction liquid after the sodium ions are removed into the fourth reactor 4; and adding 81.1 kg of tetrabutylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of tetrabutylammonium chloride to heteropolyacid is 6:1, controlling the reaction temperature in the fourth reactor 4 at 80° C., the reaction time is 0.5 h, and after fully stirring the reaction, 781 kg of the third reaction liquid is obtained, and the third reaction liquid is tetrabutyl modified phosphomolybdic acid reaction liquid;

[0117] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain 213.8 kg of quaternary ammonium salt-modified heteropolyacid tetrabutyl-modified phosphomolybdic acid.

[0118] Example 9

[0119] Step 1: 311 kg of sodium paratungstate and 1120 kg of potassium hydroxide solution with a mass concentration of 5% are added to the first reaction kettle 1, so that the molar ratio of the tungsten compound in the first reaction kettle 1 to the alkali in the potassium hydroxide solution is 1:1, the reaction temperature is controlled at 100°C, and the reaction is stirred for 6 hours to obtain 1431 kg of the first reaction liquid with a pH of 9;

[0120] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 90° C. The vacuum degree in the second reaction kettle 2 is controlled to be 50 kPa through the vacuum pump 13. After vacuum concentration for 3 hours, an intermediate liquid with a solid-liquid ratio of 1:1 is obtained;

[0121] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 391 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals with pure water, and obtain 7820 kg of a solution with a mass concentration of 5%;

[0122] Step 4: Add 21.2 kg of potassium phosphate to the third reaction kettle 3 containing the solution obtained in step 3, control the molar ratio of tungsten to phosphorus to be 11:1, control the reaction temperature of the third reaction kettle 3 to be 50° C., and the reaction time to be 1 h. After sufficient reaction, 7841 kg of the second reaction liquid is obtained, which is potassium phosphotungstate reaction liquid;

[0123] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment, removing the sodium ions and potassium ions in the second reaction liquid, and sending the second reaction liquid after the sodium ions and potassium ions are removed into the fourth reactor 4; and adding 83.4 kg of dodecyl trimethyl ammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of dodecyl trimethyl ammonium chloride to the heteropolyacid is 1:1, controlling the reaction temperature in the fourth reactor 4 at 5 ° C, the reaction time is 4h, and after fully stirring the reaction, 7925 kg of the third reaction liquid is obtained, and the third reaction liquid is the dodecyl trimethyl modified phosphotungstic acid reaction liquid;

[0124] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into the centrifugal washing device 8 for centrifugation, and dried by the drying device 9 to obtain 310.7 kg of quaternary ammonium salt-modified heteropoly acid dodecyltrimethyl modified phosphotungstic acid.

[0125] Example 10

[0126] Step 1: 119 kg of sodium heptamolybdate and 160 kg of a potassium hydroxide solution with a mass concentration of 20% are added to the first reaction kettle 1, so that the molar ratio of the molybdenum compound in the first reaction kettle 1 to the alkali in the potassium hydroxide solution is 1:5, the reaction temperature is controlled at 100° C., and the reaction is stirred for 0.1 h to obtain 279 kg of a first reaction liquid with a pH of 11;

[0127] Step 2: After filtering the first reaction liquid in the first reaction kettle 1 through the filter 5, the first reaction liquid is sent to the second reaction kettle 2 for vacuum concentration and crystallization. The temperature of the reaction kettle 2 is controlled to be 150° C. The vacuum degree in the second reaction kettle 2 is controlled to be 100 kPa through the vacuum pump 13. After vacuum concentration for 5 hours, an intermediate liquid with a solid-liquid ratio of 1:5 is obtained;

[0128] Step 3: Add the intermediate liquid obtained in step 2 to the centrifugal device 6 for centrifugal separation to separate the mother liquor and 167 kg of crystals, return the mother liquor to the second reactor 2, send the crystals to the third reactor 3, dissolve the crystals with pure water, and obtain 557 kg of a solution with a mass concentration of 30%;

[0129] Step 4: Add 148.4 kg of potassium phosphate to the third reactor 3 containing the solution obtained in step 3, control the molar ratio of molybdenum to phosphorus to be 13:1, control the reaction temperature of the third reactor 3 to be 50 ° C, the reaction time to be 1 h, and obtain 7051 kg of the second reaction liquid after sufficient reaction, the second reaction liquid is potassium phosphomolybdate reaction liquid;

[0130] Step 5, passing the second reaction liquid obtained in step 4 into the salt ion removal device 8 for salt ion removal treatment, removing the sodium ions and potassium ions in the second reaction liquid, and sending the second reaction liquid after the sodium ions and potassium ions are removed into the fourth reactor 4; and adding 78.9 kg of tetrabutylammonium chloride to the fourth reactor 4 containing the second reaction liquid, so that the molar ratio of tetrabutylammonium chloride to heteropolyacid is 3.5:1, controlling the reaction temperature in the fourth reactor 4 at 80 ° C, the reaction time is 0.1h, and after fully stirring the reaction, 784 kg of the third reaction liquid is obtained, and the third reaction liquid is tetrabutyl modified phosphomolybdic acid reaction liquid;

[0131] Step 6: The third reaction liquid obtained in the fourth reaction kettle 4 is introduced into a centrifugal washing device 8 for centrifugation, and dried by a drying device 9 to obtain 201.3 kg of quaternary ammonium salt-modified heteropolyacid tetrabutyl-modified phosphomolybdic acid.

[0132] Table 1 Quaternary ammonium salt modified heteropoly acid obtained in each example

[0133]

[0134] It can be seen from Examples 1 to 10 that the main raw materials used in the preparation method of the quaternary ammonium salt-modified heteropolyacid catalyst provided by the present application, tungsten compounds and molybdenum-containing compounds, are common substances with a wide range of raw material sources. The present application uses processes such as concentration crystallization and centrifugation to prepare quaternary ammonium salt-modified heteropolyacid catalysts with high tungsten or molybdenum content and higher raw material utilization. The purity of the quaternary ammonium salt-modified heteropolyacid catalysts prepared in Examples 1 to 10 can reach 99.99%, and the content of tungsten or molybdenum in the prepared quaternary ammonium salt-modified heteropolyacid catalysts accounts for 27% to 71%, wherein the tungsten content in the quaternary ammonium salt-modified heteropolyacid catalyst prepared in Example 7 reaches 71.07%, and the tungsten content in the quaternary ammonium salt-modified heteropolyacid catalyst prepared in Example 9 reaches 71.06%.

[0135] The quaternary ammonium salt modified heteropoly acid catalyst was prepared by the method described in the embodiment of the present application for catalytic oxidation desulfurization experiment. The experimental introduction is as follows: 3g of quaternary ammonium salt modified heteropoly acid obtained in the above embodiment is used as a catalyst, 10ml of hydrogen peroxide is used as an oxidant, 100g of 1mm coking coal is used as a sample, and 400ml of water is used as a solvent. A high-sulfur coal catalytic oxidation desulfurization experiment is carried out. In the experiment, the reaction temperature is 25°C, the reaction pressure is normal pressure, the stirring speed is 100ram, and the sulfur content of the coal sample is detected after the reaction time of 0.5 hour. The obtained desulfurization efficiency data are shown in Table 2.

[0136] Table 2 Experimental results of catalytic oxidation of coal samples desulfurization using quaternary ammonium salt modified heteropoly acid catalysts in various examples

[0137]

[0138] The quaternary ammonium salt modified heteropoly acid catalyst was prepared by the method described in the present application to carry out a catalytic oxidation gasoline desulfurization experiment. The experimental introduction is as follows: 1g of the quaternary ammonium salt modified heteropoly acid obtained in the above embodiment is used as a catalyst, 5ml of hydrogen peroxide is used as an oxidant, 500ml of No. 95 gasoline is used as a sample, and 200ml of water is used as a solvent. A high-sulfur coal catalytic oxidation desulfurization experiment is carried out. In the experiment, the reaction temperature is 25°C, the reaction pressure is normal pressure, the stirring rate is 100ram, and the sulfur content in the gasoline is detected after the reaction time is 1 hour. The obtained desulfurization efficiency data are shown in Table 3 below.

[0139] Table 3 Results of the catalytic oxidation gasoline desulfurization experiments using quaternary ammonium salt modified heteropoly acid catalysts in various examples

[0140]

[0141] It can be seen from the experimental data of Table 3 and Table 4 that the quaternary ammonium salt modified heteropoly acid catalyst obtained in the embodiment of the present application shows good performance in catalytic oxidation desulfurization, and hexadecyl trimethyl modified phosphotungstic acid and hexadecyl trimethyl modified phosphomolybdic acid show higher desulfurization efficiency. Therefore, for different types of samples, it is necessary to select a suitable catalyst and optimize the reaction conditions to achieve the best desulfurization effect.

[0142] The quaternary ammonium salt modified heteropoly acid catalyst prepared by the method described in this application was used to carry out a polymerization reaction experiment of tetrahydrofuran (THF). The experiment is briefly described as follows: 10 g of the quaternary ammonium salt modified heteropoly acid catalyst synthesized by the method described in Examples 1 to 10 was added to 20 g of tetrahydrofuran, and the reaction was stirred for 4 hours at a temperature of 60±5°C, normal pressure~1MPa, and a stirring speed of 80rpm. After the reaction was completed, the product components were allowed to stand to separate from the catalyst, and the upper clear liquid was taken to detect the conversion rate and analysis amount of PTMEG by gel color. The analysis results are shown in Table 4.

[0143] Table 4 Experimental results of tetrahydrofuran (THF) polymerization using quaternary ammonium salt modified heteropolyacid catalysts in various examples

[0144]

[0145] It can be found from Table 4 that when the catalyst obtained in the embodiment of the present invention is used for tetrahydrofuran conversion, the conversion rate can reach 20% to 27.8%.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a quaternary ammonium salt modified heteropolyacid catalyst, characterized in that: The following steps are involved: Step 1: fully reacting a tungsten-containing compound or a molybdenum-containing compound with an alkali solution having a mass concentration of 5% to 40% to obtain a first reaction solution with a pH of 9 to 11, wherein the molar ratio of the tungsten compound or the molybdenum compound in the reactant to the alkali in the alkali solution is 1:1 to 1:5; Step 2: Concentrate and crystallize the first reaction solution obtained in step 1 to obtain an intermediate solution with a solid-liquid ratio of 1:1 to 5:1; Step 3: Centrifuge the intermediate solution obtained in step 2 to separate the mother solution and crystals, and use pure water to dissolve the crystals to obtain a solution with a mass concentration of 5% to 30%; Step 4: adding a phosphoric acid compound to the solution obtained in step 3 to react, controlling the molar ratio of tungsten or molybdenum to phosphorus to be 11-13:1, and obtaining a second reaction solution after sufficient reaction; Step 5, removing salt ions from the second reaction solution obtained in step 4, and adding a quaternary ammonium salt compound to the second reaction solution after the salt ions are removed, and obtaining a third reaction solution after sufficient reaction, wherein the molar ratio of the quaternary ammonium salt compound added to the heteropolyacid is 1 to 6:1; Step 6: Centrifuge and dry the third reaction solution to obtain a quaternary ammonium salt-modified heteropolyacid catalyst.

2. The preparation method of a quaternary ammonium salt modified heteropolyacid catalyst as claimed in claim 1, wherein The tungsten-containing compound is one or more of tungsten trioxide, ammonium paratungstate, and sodium paratungstate.

3. The preparation method of quaternary ammonium salt modified heteropolyacid catalyst as claimed in claim 1, characterized in that, The molybdenum-containing compound is one or more of molybdenum oxide, ammonium paramolybdate, and sodium paramolybdate.

4. The preparation method of quaternary ammonium salt modified heteropolyacid catalyst as claimed in claim 1, characterized in that, The alkali solution is one or more of sodium hydroxide solution and potassium hydroxide solution.

5. The preparation method of quaternary ammonium salt modified heteropolyacid catalyst as claimed in claim 1, characterized in that, The phosphate compound is one or more of phosphoric acid, disodium hydrogen phosphate, sodium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium phosphate, and potassium phosphate.

6. The preparation method of quaternary ammonium salt modified heteropolyacid catalyst as claimed in claim 1, characterized in that, The quaternary ammonium salt compound is one or more of hexadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, tetrabutylammonium chloride, hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide and tetrabutylammonium bromide.

7. A preparation system for the preparation method according to any one of claims 1 to 6, characterized in that: include: A first reaction kettle (1), a second reaction kettle (2), a third reaction kettle (3), and a fourth reaction kettle (4) are arranged in sequence; A filter (5) is arranged between the first reaction kettle (1) and the second reaction kettle (2); A centrifugal device (6) is arranged between the second reactor (2) and the third reactor (3), the centrifugal mother liquor outlet of the centrifugal device (6) is connected to the inlet of the second reactor (2), and the crystal outlet of the centrifugal device is connected to the inlet of the third reactor (3); An ion removal device (7) is arranged between the third reaction kettle (3) and the fourth reaction kettle (4), the inlet of the ion removal device (7) is connected to the third reaction kettle (3), and the main feed liquid outlet of the ion removal device (7) is connected to the inlet of the fourth reaction kettle (4); A centrifugal washing device (8) and a drying device (9) are sequentially arranged behind the fourth reaction kettle (4).

8. The preparation system of the quaternary ammonium salt modified heteropolyacid catalyst as claimed in claim 7, characterized in that, The centrifugal washing liquid outlet of the centrifugal washing device (8) is connected to the inlet of the pure water preparation system (10), and the outlet of the pure water preparation system (10) is connected to at least one inlet of the first reaction kettle, the third reaction kettle, and the centrifugal washing device (8).

9. The preparation system of the quaternary ammonium salt modified heteropolyacid catalyst according to claim 7, characterized in that, The outlet of the condensed water in the storage tank (12) is connected to the inlet of the pure water preparation system (10).

10. The preparation system of the quaternary ammonium salt modified heteropolyacid catalyst according to claim 7, characterized in that, The ion removal device (7) is an ion exchange column or bipolar membrane electrodialysis.

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