Preparation method of electronic grade sulfuric acid and device for preparing electronic grade sulfuric acid

Abstract

The invention relates to the field of electronic chemicals, and discloses a preparation method of electronic-grade sulfuric acid and a device for preparing the electronic-grade sulfuric acid. The preparation method of the electronic-grade sulfuric acid provided by the invention comprises the following steps: irradiating high-purity sulfur trioxide gas with electron beams, then absorbing the irradiated sulfur trioxide gas with ultrapure water, and then filtering the obtained crude sulfuric acid solution to obtain the electronic-grade sulfuric acid. The high-purity sulfur trioxide gas is irradiated by the electron beams generated under the action of the high-energy electric field, a small amount of air carried in the sulfur trioxide is utilized for ionization to generate the oxidizing agent, extra introduction of ultra-pure air and water vapor is not needed, the content of sulfur dioxide contained in the high-purity sulfur trioxide gas is effectively reduced, and no tail gas is generated.

Description

Technical Field

[0001] The invention relates to the field of electronic chemicals, and in particular to a method for preparing electronic-grade sulfuric acid and a device for preparing electronic-grade sulfuric acid. Background Art

[0002] Electronic grade sulfuric acid is mainly used for cleaning and etching silicon wafers, and can effectively remove impurity particles, inorganic residues and carbon deposits on the wafers. With the development of integrated circuits (ICs) towards large-scale, ultra-large-scale and extremely large-scale, the chip integration is getting higher and higher, the photolithography lines on the wafer surface are getting finer and finer, the replacement speed of ICs is getting faster and faster, and the quality requirements for sulfuric acid are becoming more and more stringent.

[0003] The production processes of ultrapure sulfuric acid include distillation and gas absorption. The distillation method is to heat the filtered ultrapure sulfuric acid to make it boil and vaporize, and then obtain electronic-grade products through distillation. The disadvantages of the distillation method are: first, the purity of the sulfuric acid product is not high enough, and generally only G1-G2 grade products can be produced; second, it is not suitable for large-scale production, generally only thousands of tons; third, it has high energy consumption and high production costs. The gas absorption method uses fuming sulfuric acid as a raw material to produce relatively pure gaseous sulfur trioxide, which is then absorbed by electronic-grade ultrapure water after purification, and then stripped and finely filtered by ultrapure air to produce electronic-grade sulfuric acid. The gas absorption method is the mainstream technology for large-scale industrial production of electronic-grade sulfuric acid at home and abroad.

[0004] In the process of preparing sulfuric acid by gas absorption method, the sulfur dioxide contained in the raw acid will inevitably evaporate together with the sulfur trioxide, and its presence will affect the quality of the finished acid. At present, the method of removing easily oxidized substances such as sulfur dioxide from electronic-grade sulfuric acid is aeration method, which uses ultrapure air or nitrogen to blow off the sulfur dioxide in sulfuric acid. It is necessary to add new equipment aeration tower, and the amount of high-purity air or high-purity nitrogen is large. The sulfur dioxide contained in the waste gas generated by the blow-off needs to be treated by tail gas. Adding a tail gas treatment system is also not conducive to cost control. Therefore, there is an urgent need for an electronic-grade sulfuric acid production process that can reduce production costs, reduce environmental pollution, and improve production efficiency while obtaining electronic-grade sulfuric acid. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems that in the process of preparing sulfuric acid by gas absorption method in the prior art, the process and equipment for removing sulfur dioxide evaporated together with sulfur trioxide are complicated, the amount of high-purity air or high-purity nitrogen is large, and the sulfur dioxide contained in the waste gas generated by stripping needs to be treated by tail gas. A method for preparing electronic-grade sulfuric acid and an apparatus for preparing electronic-grade sulfuric acid are provided. The method does not require the additional introduction of ultra-pure air and water vapor, and can effectively reduce the content of sulfur dioxide contained in high-purity sulfur trioxide gas, and no tail gas is generated.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing electronic-grade sulfuric acid, wherein the preparation method comprises the following steps: irradiating a high-purity sulfur trioxide gas raw material with an electron beam, then absorbing the obtained irradiated sulfur trioxide gas with ultrapure water, and then filtering the obtained crude sulfuric acid liquid to obtain the electronic-grade sulfuric acid.

[0007] The second aspect of the present invention provides a device for preparing electronic grade sulfuric acid, wherein the device comprises: an electron beam reactor, an absorption tower and an ultra-clean filter connected in sequence; wherein:

[0008] The electron beam reactor is used to irradiate the high-purity sulfur trioxide gas raw material with an electron beam to oxidize sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide;

[0009] The absorption tower is used to absorb the irradiated sulfur trioxide gas with ultrapure water to obtain crude sulfuric acid liquid;

[0010] The ultra-clean filter is used to filter the crude sulfuric acid liquid to remove particulate matter in the crude sulfuric acid liquid, thereby obtaining electronic grade sulfuric acid.

[0011] Through the above technical solution, the beneficial effects of the present invention are:

[0012] The present invention irradiates the high-purity sulfur trioxide gas raw material with an electron beam generated by the action of a high-energy electric field. A small amount of nitrogen, oxygen and water vapor contained in the high-purity sulfur trioxide gas raw material generates a large amount of ions, free radicals and excited atoms and other strong oxidizing substances under the action of irradiation. These strong oxidizing substances can oxidize a small amount of sulfur dioxide entrained in the sulfur trioxide into sulfur trioxide, and combine with a small amount of water to form sulfuric acid mist to enter the absorption section. The electron beam oxidation process is a dry process, which uses a small amount of air carried in the sulfur trioxide to ionize and generate an oxidant, and does not need to additionally introduce ultra-pure air and water vapor. The product is high-purity sulfur trioxide and a small amount of high-purity sulfuric acid mist, which effectively reduces the content of sulfur dioxide contained in the high-purity sulfur trioxide gas raw material, and no tail gas is generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram of an apparatus for preparing electronic grade sulfuric acid in a preferred embodiment of the present invention;

[0014] Figure 2 is a schematic structural diagram of an electron beam reactor in a preferred embodiment of the present invention;

[0015] Figure 3 It is a schematic structural diagram of an electron beam system in a preferred embodiment of the present invention.

[0016] Description of Reference Numerals

[0017] 1Electron beam reactor 2Reactor pipeline 101Scanning box exit window

[0018] 102 reactor entrance window 103 air layer 104 electron accelerator DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] A first aspect of the present invention provides a method for preparing electronic-grade sulfuric acid, wherein the preparation method comprises the following steps: irradiating a high-purity sulfur trioxide gas raw material with an electron beam, then absorbing the obtained irradiated sulfur trioxide gas with ultrapure water, and then filtering the obtained crude sulfuric acid liquid to obtain the electronic-grade sulfuric acid.

[0021] The present invention irradiates the high-purity sulfur trioxide gas raw material with an electron beam generated by the action of a high-energy electric field. A small amount of nitrogen, oxygen and water vapor contained in the high-purity sulfur trioxide gas raw material generates a large amount of ions, free radicals and excited atoms and other strong oxidizing substances under the action of irradiation. These strong oxidizing substances can oxidize a small amount of sulfur dioxide entrained in the sulfur trioxide into sulfur trioxide, and combine with a small amount of water to form sulfuric acid mist to enter the absorption section. The electron beam oxidation process is a dry process, which uses a small amount of air carried in the sulfur trioxide to ionize and generate an oxidant, and does not need to additionally introduce ultra-pure air and water vapor. The product is high-purity sulfur trioxide and a small amount of high-purity sulfuric acid mist, which effectively reduces the content of sulfur dioxide contained in the high-purity sulfur trioxide gas raw material, and no tail gas is generated.

[0022] According to the present invention, preferably, the irradiated electron energy is 0.6-1.5 MeV, preferably 0.8-1.2 MeV. The irradiated electron energy mainly affects the oxidizing ability of easily oxidized substances such as sulfur dioxide, and lower electron energy is insufficient to achieve the purification of sulfur trioxide. Appropriate electron energy can ensure sufficient generation of oxidants while avoiding electron energy loss.

[0023] According to the present invention, preferably, the irradiation method adopts 1-5 level irradiation, preferably 2-3 level irradiation.

[0024] According to the present invention, preferably, the irradiation process comprises: passing a high-purity sulfur trioxide gas raw material into an electron beam system;

[0025] The electron beam system comprises: a reactor pipeline and at least one electron beam reactor, and the electron beam reactor comprises: a power supply, an electron accelerator, a scanning box exit window and a reactor incident window.

[0026] According to the present invention, preferably, the window foil of the scanning box exit window and the window foil of the reactor entrance window are independently made of titanium, beryllium, aluminum, titanium aluminum alloy or titanium palladium alloy, preferably titanium palladium alloy. Selecting appropriate window foil materials of the scanning box exit window and the reactor entrance window can further reduce the metal ion content and the oxidizable substance content of the electronic grade sulfuric acid product, and can further increase the operating time of the window foil, especially the impact on the operating time of the window foil is more significant.

[0027] According to the present invention, preferably, the thickness of the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor are independently 20-150 μm, preferably 40-60 μm.

[0028] In the present invention, the scanning box exit window and the reactor incident window use a titanium-palladium alloy window foil with a certain thickness, which can have a lower energy loss rate and good durability. If the window foil is too thick, it will cause a large loss of electron energy and a decrease in oxidation ability.

[0029] According to the present invention, preferably, the distance between the window foil of the scanning box exit window and the window foil of the reactor incident window is 40-200 mm, preferably 60-100 mm. The distance between the window foil of the scanning box exit window and the window foil of the reactor incident window is the thickness of the air layer. A certain thickness of the air layer prevents the window foil of the scanning box exit window and the window foil of the reactor incident window from directly contacting the gas, thereby preventing the metal ions in the window foil from entering the sulfur trioxide, which is beneficial to the purification of sulfur trioxide; if it is too thick, it may cause a large loss of electron energy and a decrease in oxidation ability.

[0030] According to the present invention, preferably, the electron beam system comprises 2-5 electron beam reactors connected in parallel, preferably 2 or 3. By connecting 2 or 3 electron beam reactors in parallel, sulfur dioxide removal can be achieved more effectively. The number of electron beam reactors connected in parallel has an impact on the metal ion content, the oxidizable substance content and the running time of the window foil. Too little electron irradiation is not conducive to purification, and too much electron irradiation reduces the service life of the window foil and increases the pollution of metal ions.

[0031] According to the present invention, preferably, the filtration temperature is 10-70° C., preferably 10-30° C. When the filtration temperature meets this range, the filtration efficiency can be further improved.

[0032] According to the present invention, preferably, based on the total volume of the sulfur trioxide gas after the irradiation being 1 L, the amount of the ultrapure water used is 0.02-0.1 L.

[0033] According to the present invention, preferably, the method for preparing the high-purity sulfur trioxide gas raw material comprises the following steps: gasifying the oleum raw material for the first time, and then demisting and purifying the obtained sulfur trioxide-containing vapor to obtain the high-purity sulfur trioxide gas raw material. Preferably, the temperature of the first gasification is 140-170°C.

[0034] The present invention does not particularly limit the demisting method, for example, the demisting can be performed by condensation, and a demister can be used for condensation demisting. After the demister, droplets and soluble solid particles in the gas flow containing sulfur trioxide vapor can be removed. Then, purification is performed to remove metal ions. Preferably, the condensation temperature is 20-60°C, preferably 50-60°C.

[0035] When the condensation method is used for demisting, the purified material needs to be gasified for the second time. Preferably, the temperature of the second gasification is 140-170°C.

[0036] According to the present invention, preferably, the purification is performed using an ultrafiltration membrane.

[0037] According to the present invention, preferably, the pore size of the ultrafiltration membrane is 0.005-0.02 μm, preferably 0.008-0.01 μm. The purification device before the sulfur trioxide gas enters the electron beam system adopts an ultrafiltration system, which is mainly used to filter metal ions. The pore size of the ultrafiltration membrane mainly affects the filtering ability of metal ions. Too large pore size will bring more metal ion impurities. The pore size of the ultrafiltration membrane meets this range, which can effectively filter metal ions while ensuring the filtration speed.

[0038] In the present invention, the high-purity sulfur trioxide gas raw material includes SO 3 The content of SO is greater than or equal to 99.5wt%, 2 The content of is less than or equal to 0.4wt%, the content of ash is less than or equal to 0.05wt%, and the content of iron is less than or equal to 0.03wt%.

[0039] The second aspect of the present invention provides a device for preparing electronic grade sulfuric acid, wherein the device comprises: an electron beam system, an absorption tower and an ultra-clean filter connected in sequence; wherein,

[0040] The electron beam system is used to irradiate the high-purity sulfur trioxide gas raw material with an electron beam to oxidize sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide;

[0041] The absorption tower is used to absorb the irradiated sulfur trioxide gas with ultrapure water to obtain crude sulfuric acid liquid;

[0042] The ultra-clean filter is used to filter the crude sulfuric acid liquid to remove particulate matter in the crude sulfuric acid liquid, thereby obtaining electronic grade sulfuric acid.

[0043] According to the present invention, preferably, the device further comprises: a first evaporator, a demister and a precision filter which are connected in sequence; wherein the precision filter is connected to the electron beam system.

[0044] In the present invention, the first evaporator is used to heat and gasify the oleum raw material to evaporate sulfur trioxide-containing steam; the demister is used to further remove liquid impurities and solid impurities; and the precision filter is used to remove metal ions.

[0045] When the demister is a condensing demister, the device further comprises: a second evaporator disposed between the precision filter and the electron beam system. The second evaporator is used to perform a second gasification on the condensed sulfur trioxide-containing liquid to obtain a high-purity sulfur trioxide gas raw material.

[0046] According to the present invention, preferably, an ultrafiltration membrane is provided in the precision filter to remove metal ions; the pore size of the ultrafiltration membrane is 0.005-0.02 μm, preferably 0.008-0.01 μm.

[0047] According to the present invention, preferably, the electron beam system comprises: a reactor pipe and 2-5 electron beam reactors connected in parallel, preferably 2 or 3.

[0048] According to the present invention, preferably, Figure 2 As shown, the electron beam reactor comprises: a power supply, an electron accelerator 104, a scanning box exit window 101 and a reactor entrance window 102, and an air layer 103 is between the scanning box exit window 101 and the reactor entrance window 102. Among them, the electron accelerator is used to generate high-energy electrons, the scanning box exit window is used to guide the high-energy electrons into the reactor entrance window, and the reactor entrance window is used to guide the electrons to contact with the gas. The high-purity sulfur trioxide gas raw material transmitted in the reactor pipeline is irradiated by the parallel electron beam reactors in sequence.

[0049] According to the present invention, preferably, the window foil of the scanning box exit window and the window foil of the reactor incident window are independently made of titanium, beryllium, aluminum, titanium-aluminum alloy or titanium-palladium alloy, preferably titanium-palladium alloy.

[0050] According to the present invention, preferably, the thickness of the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor are independently 20-150 μm, preferably 40-60 μm.

[0051] According to the present invention, preferably, the distance between the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor is 40-200 mm, preferably 60-100 mm.

[0052] According to a specific embodiment of the present invention, an electron beam system including three electron beam reactors connected in parallel is as follows: Figure 3 As shown, a high-purity sulfur trioxide gas raw material is introduced into a reactor pipe 2 of an electron beam system, and three parallel electron beam reactors 1 irradiate the high-purity sulfur trioxide gas raw material in the reactor pipe 2 .

[0053] According to the present invention, preferably, a sulfuric acid circulation tank and a cooler which are interconnected are also provided between the absorption tower and the ultra-clean filter; wherein,

[0054] The sulfuric acid circulation tank is connected to the bottom of the absorption tower, and is used to store the crude sulfuric acid liquid flowing out from the bottom of the absorption tower; the cooler is respectively connected to the upper part of the absorption tower and the ultra-clean filter. The crude sulfuric acid liquid flowing out from the bottom of the absorption tower enters the sulfuric acid circulation tank, and after being cooled to 55-65°C by the cooler, it returns to the absorption tower from the upper part for circulation absorption. The concentration of the crude sulfuric acid liquid is monitored online, and after reaching the required concentration, it enters the ultra-clean filter to remove particulate matter in the crude sulfuric acid liquid.

[0055] According to the present invention, preferably, an intermediate storage tank is further provided between the cooler and the ultra-clean filter. After the crude sulfuric acid liquid reaches the required concentration (95-97wt%), it enters the intermediate storage tank, where it is stirred and cooled to 10-30°C before being sent to the ultra-clean filter.

[0056] According to the present invention, preferably, the device further comprises a finished product storage tank connected to the outlet of the ultra-clean filter. The electronic-grade sulfuric acid is finally obtained after the crude sulfuric acid liquid is filtered through the ultra-clean filter to remove residual particulate matter, and the final product electronic-grade sulfuric acid is extracted and stored in the finished product storage tank.

[0057] According to a preferred embodiment of the present invention, Figure 1 Electronic grade sulfuric acid is prepared in the device shown, and the specific preparation method includes the following steps:

[0058] S1, inputting oleum raw material into the first evaporator for evaporation to obtain sulfur trioxide-containing steam;

[0059] S2, passing the sulfur trioxide-containing vapor obtained in S1 through a demister and a precision filter in sequence, and then inputting the obtained condensed sulfur trioxide-containing liquid into a second evaporator for secondary evaporation to obtain a high-purity sulfur trioxide gas raw material;

[0060] S3, passing the high-purity sulfur trioxide gas raw material obtained in S2 into an electron beam system, oxidizing sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide by accelerating electrons to irradiate the gas in the pipeline, and obtaining irradiated sulfur trioxide gas;

[0061] S4, ultrapure water flows into the absorption tower through the sulfuric acid circulation tank, and the ultrapure water absorbs the irradiated sulfur trioxide gas in the absorption tower. The obtained crude sulfuric acid liquid enters the sulfuric acid circulation tank, and after being cooled by the cooler, it returns to the upper part of the absorption tower for circulation absorption. The crude sulfuric acid liquid is in countercurrent contact with the irradiated sulfur trioxide gas. The concentration of the crude sulfuric acid liquid is monitored online, and after reaching the required concentration, it is cooled by the cooler and then enters the intermediate storage tank;

[0062] S5. The crude sulfuric acid liquid is stirred and cooled in the intermediate storage tank, and then sent to the ultra-clean filter to remove the residual particulate matter and then taken out. The obtained electronic grade sulfuric acid product is stored in the finished product storage tank.

[0063] The present invention will be described in detail below through examples and comparative examples. In the following examples, unless otherwise specified, all methods are conventional methods; the reagents and materials used, unless otherwise specified, can be obtained from commercial sources. The determination methods involved in each example are as follows:

[0064] The content of oxidizable substances (sulfur dioxide) shall be determined in accordance with GB / T 41881-2022;

[0065] The metal ion content is determined in accordance with GB / T 41881-2022.

[0066] The following examples are used to illustrate the Figure 1 A method for producing electronic grade sulfuric acid in the apparatus shown.

[0067] Example 1

[0068] S1, inputting the industrial grade oleum raw material in the raw material storage tank into the first evaporator for evaporation at a temperature of 150° C. to obtain sulfur trioxide-containing steam;

[0069] S2, passing the sulfur trioxide-containing vapor obtained in S1 through a demister and a precision filter in sequence, the temperature in the demister being 55°C; then inputting the obtained condensed sulfur trioxide-containing liquid into a second evaporator for secondary evaporation, the evaporation temperature being 150°C, to obtain a high-purity sulfur trioxide gas raw material;

[0070] S3, passing the high-purity sulfur trioxide gas raw material obtained in S2 into an electron beam system, oxidizing sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide by accelerating electrons to irradiate the gas in the pipeline, and obtaining irradiated sulfur trioxide gas;

[0071] S4, absorbing the irradiated sulfur trioxide gas with ultrapure water in the absorption tower, taking the total volume of the irradiated sulfur trioxide gas as 1L, the amount of ultrapure water is 0.06L, the obtained crude sulfuric acid liquid enters the sulfuric acid circulation tank, is cooled to 60°C by the cooler, and then returns to the upper part of the absorption tower for circulation absorption, and the concentration of the crude sulfuric acid liquid is monitored by online concentration. When the concentration of the crude sulfuric acid liquid is 96wt%, the crude sulfuric acid liquid enters the intermediate storage tank;

[0072] S5. Stir and cool the crude sulfuric acid liquid in the intermediate storage tank, and send it to the ultra-clean filter after the temperature drops to 20°C, remove the residual particles, and then extract the electronic grade sulfuric acid product into the finished product storage tank; wherein,

[0073] In S2, an ultrafiltration membrane is provided in the precision filter, and the pore size of the membrane is 0.01 μm;

[0074] In S3, the irradiated electron energy is 1.2MeV, the window foil materials of the scanning box exit window and the reactor incident window are both titanium-palladium alloy, the window foil thickness is 45μm, the distance between the two layers of window foil (i.e., the thickness of the air layer) is 70mm, and the electron beam irradiation mode is 3-level irradiation (i.e., the electron beam system includes 3 parallel electron beam reactors).

[0075] Example 2

[0076] S1, inputting the industrial grade oleum raw material in the raw material storage tank into the first evaporator for evaporation at a temperature of 140° C. to obtain sulfur trioxide-containing steam;

[0077] S2, the sulfur trioxide-containing vapor obtained in S1 is passed through a demister and a precision filter in sequence, the temperature in the demister is 50°C; then the obtained condensed sulfur trioxide-containing liquid is input into a second evaporator for secondary evaporation, the evaporation temperature is 140°C, and a high-purity sulfur trioxide gas raw material is obtained;

[0078] S3, passing the high-purity sulfur trioxide gas raw material obtained in S2 into an electron beam system, oxidizing sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide by accelerating electrons to irradiate the gas in the pipeline, and obtaining irradiated sulfur trioxide gas;

[0079] S4, absorbing the irradiated sulfur trioxide gas with ultrapure water in the absorption tower, taking the total volume of the irradiated sulfur trioxide gas as 1L, the amount of ultrapure water is 0.02L, the obtained crude sulfuric acid liquid enters the sulfuric acid circulation tank, is cooled to 60°C by the cooler, and then returns to the upper part of the absorption tower for circulation absorption, and the concentration of the crude sulfuric acid liquid is monitored by online concentration. When the concentration of the crude sulfuric acid liquid is 96wt%, the crude sulfuric acid liquid enters the intermediate storage tank;

[0080] S5. Stir and cool the crude sulfuric acid liquid in the intermediate storage tank, and send it to the ultra-clean filter after the temperature drops to 10°C, remove the residual particles, and then extract the obtained electronic grade sulfuric acid into the finished product storage tank; wherein,

[0081] In S2, an ultrafiltration membrane is provided in the precision filter, and the pore size of the membrane is 0.008 μm;

[0082] In S3, the irradiated electron energy is 0.9MeV, the window foil materials of the scanning box exit window and the reactor incident window are both titanium-palladium alloy, the window foil thickness is 50μm, the distance between the two layers of window foil (i.e., the thickness of the air layer) is 90mm, and the electron beam irradiation mode is level 2 irradiation (i.e., the electron beam system includes two parallel electron beam reactors).

[0083] Example 3

[0084] S1, inputting the industrial grade oleum raw material in the raw material storage tank into the first evaporator for evaporation at a temperature of 170° C. to obtain sulfur trioxide-containing steam;

[0085] S2, the sulfur trioxide-containing vapor obtained in S1 is passed through a demister and a precision filter in sequence, the temperature in the demister is 60°C; then the obtained condensed sulfur trioxide-containing liquid is input into a second evaporator for secondary evaporation, the evaporation temperature is 170°C, and a high-purity sulfur trioxide gas raw material is obtained;

[0086] S3, passing the high-purity sulfur trioxide gas raw material obtained in S2 into an electron beam system, oxidizing sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide by accelerating electrons to irradiate the gas in the pipeline, and obtaining irradiated sulfur trioxide gas;

[0087] S4, absorbing the irradiated sulfur trioxide gas with ultrapure water in the absorption tower, taking the total volume of the irradiated sulfur trioxide gas as 1L, the amount of ultrapure water is 0.1L, the obtained crude sulfuric acid liquid enters the sulfuric acid circulation tank, is cooled to 60°C by the cooler, and then returns to the upper part of the absorption tower for circulation absorption, and the concentration of the crude sulfuric acid liquid is monitored by online concentration. When the concentration of the crude sulfuric acid liquid is 96wt%, the crude sulfuric acid liquid enters the intermediate storage tank;

[0088] S5. Stir and cool the crude sulfuric acid liquid in the intermediate storage tank, and send it to the ultra-clean filter after the temperature drops to 30°C, remove the residual particles, and then extract the electronic grade sulfuric acid product into the finished product storage tank; wherein,

[0089] In S2, an ultrafiltration membrane is provided in the precision filter, and the pore size of the membrane is 0.01 μm;

[0090] In S3, the irradiated electron energy is 0.8MeV, the window foil materials of the scanning box exit window and the reactor incident window are both titanium-palladium alloy, the window foil thickness is 60μm, the distance between the two layers of window foil (i.e., the thickness of the air layer) is 100mm, and the electron beam irradiation mode is 3-level irradiation (i.e., the electron beam system includes 3 parallel electron beam reactors).

[0091] Example 4

[0092] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S2, an ultrafiltration membrane was provided in the precision filter, and the pore size of the membrane was 0.02 μm, so as to obtain a finished electronic grade sulfuric acid.

[0093] Example 5

[0094] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the window foils of the scanning box exit window and the reactor entrance window were made of titanium aluminum alloy to obtain electronic grade sulfuric acid product.

[0095] Example 6

[0096] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the electron beam irradiation method was level 1 irradiation (ie, the electron beam system included two parallel electron beam reactors), to obtain electronic grade sulfuric acid product.

[0097] Example 7

[0098] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the energy of the irradiated electrons was 0.6 MeV, thereby obtaining electronic grade sulfuric acid product.

[0099] Example 8

[0100] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the thickness of the window foil was 100 μm, thereby obtaining a finished electronic grade sulfuric acid product.

[0101] Example 9

[0102] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the distance between the two layers of window foil (i.e., the thickness of the air layer) was 150 mm. Electronic grade sulfuric acid was obtained.

[0103] Example 10

[0104] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S2, an ultrafiltration membrane was provided in the precision filter, and the pore size of the membrane was 0.03 μm, so as to obtain a finished electronic grade sulfuric acid.

[0105] Embodiment 11

[0106] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the energy of the irradiated electrons was 0.3 MeV, thereby obtaining an electronic grade sulfuric acid product.

[0107] Example 12

[0108] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the window foils of the scanning box exit window and the reactor entrance window were made of iron-aluminum alloy to obtain finished electronic grade sulfuric acid.

[0109] Embodiment 13

[0110] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the thickness of the window foil was 200 μm, thereby obtaining a finished electronic grade sulfuric acid product.

[0111] Embodiment 14

[0112] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the distance between the two layers of window foil (i.e., the thickness of the air layer) was 300 mm. Electronic grade sulfuric acid was obtained.

[0113] Embodiment 15

[0114] Electronic grade sulfuric acid was produced according to the method of Example 1, except that in S3, the electron beam irradiation method was 6-level irradiation (ie, the electron beam system included 6 parallel electron beam reactors), to obtain electronic grade sulfuric acid product.

[0115] Test Case

[0116] The oxidizable substance content, metal ion content, and window foil operation time of the scanning box exit window and the reactor entrance window in the electronic grade sulfuric acid product prepared in each embodiment were measured respectively. The results are shown in Table 1.

[0117] Table 1

[0118]

[0119] Note: The unit of ppt is ng / L, and the unit of ppb is μg / L.

[0120] It can be seen from the results in Table 1 that the metal ion content and the easily oxidized substance content in the finished electronic-grade sulfuric acid products prepared in Examples 1-3 are both low, meeting the G4 electronic-grade sulfuric acid standard, and the window foil has a longer operating time.

[0121] In addition, both Example 4 and Example 10 increased the pore size of the ultrafiltration membrane. Compared with Example 1, the metal ion content in the finished electronic-grade sulfuric acid product increased significantly, and the easily oxidized material content also increased to a certain extent, indicating that the pore size of the ultrafiltration membrane mainly affects the filtration capacity of metal ions, and too large a pore size will bring more metal ion impurities; both Example 7 and Example 11 reduced the irradiated electron energy. Compared with Example 1, the easily oxidized material content in the finished electronic-grade sulfuric acid product increased significantly, and the metal ion content also increased to a certain extent, indicating that the irradiated electron energy mainly affects the oxidizing capacity for easily oxidized materials such as sulfur dioxide. Low electron energy is not enough to achieve the purification of sulfur trioxide; Example 5 and Example 12 both changed the window foil material. Compared with Example 1, the metal ion content in the electronic-grade sulfuric acid product prepared in Example 5 increased to a certain extent, and the window foil operation time was also shortened. The metal ion content and the easily oxidized oxide content in the electronic-grade sulfuric acid product prepared in Example 12 increased significantly, and the window foil operation time was also significantly shortened, indicating that the window foil material has a certain influence on the metal ion content, the easily oxidized oxide content and the window foil operation time, among which the influence on the window foil operation time is the most significant; Example 8 and Example 13 both increased the window foil The thickness of the window foil increases significantly compared with that of Example 1, and the content of easily oxidized substances in the finished electronic-grade sulfuric acid is also increased to a certain extent, indicating that the thickness of the window foil mainly affects the oxidizing ability of the electron beam, and a thicker window foil will reduce the emission energy of the electron beam and reduce the oxidizing ability; Examples 9 and 14 both increase the distance between the window foils, and compared with Example 1, the content of easily oxidized substances in the finished electronic-grade sulfuric acid is also increased to a certain extent, and the content of metal ions is also increased to a certain extent, indicating that the thickness of the air layer mainly affects the oxidizing ability of the electron beam, and a thicker air layer is not conducive to the purification of sulfur trioxide; Example 6 reduces the series connection of the window foils. The number of electron beam reactors connected in series is increased. Compared with Example 1, the metal ion content and the easily oxidized substance content in the electronic-grade sulfuric acid product prepared in Example 6 are increased. Example 15 increases the number of electron beam reactors connected in series. Compared with Example 1, the metal ion content and the easily oxidized substance content in the electronic-grade sulfuric acid product prepared in Example 15 are increased, and the operating time of the window foil is also shortened, indicating that the electron irradiation method has an impact on the metal ion content, the easily oxidized substance content and the operating time of the window foil. Too little electron irradiation is not conducive to purification, and too much electron irradiation reduces the service life of the window foil and increases the pollution of metal ions.

[0122] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing electronic grade sulfuric acid, characterized in that: The preparation method comprises the following steps: irradiating a high-purity sulfur trioxide gas raw material with an electron beam, absorbing the obtained irradiated sulfur trioxide gas with ultrapure water, and filtering the obtained crude sulfuric acid liquid to obtain the electronic grade sulfuric acid.

2. The preparation method according to claim 1, characterized in that: In the irradiation, the electron energy of the electron beam is 0.6-1.5 MeV, preferably 0.8-1.2 MeV.

3. The preparation method according to claim 1 or 2, characterized in that: The irradiation method adopts 1-5 level irradiation, preferably 2-3 level irradiation.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The irradiation process includes: introducing high-purity sulfur trioxide gas raw material into an electron beam system; Wherein, the electron beam system comprises: a reactor pipeline and at least one electron beam reactor, and the electron beam reactor comprises: a power supply, an electron accelerator, a scanning box exit window and a reactor incident window; Preferably, the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor are independently made of titanium, beryllium, aluminum, titanium-aluminum alloy or titanium-palladium alloy, preferably titanium-palladium alloy; Preferably, the thickness of the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor are independently 20-150 μm, preferably 40-60 μm; Preferably, the distance between the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor is 40-200 mm, preferably 60-100 mm; Preferably, the electron beam system comprises 2-5 electron beam reactors connected in parallel, preferably 2 or 3.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The filtration temperature is 10-70°C; Preferably, based on the total volume of the sulfur trioxide gas after the irradiation being 1 L, the amount of the ultrapure water used is 0.02-0.1 L.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The method for preparing the high-purity sulfur trioxide gas raw material comprises the following steps: gasifying the oleum raw material, and then demisting and purifying the obtained sulfur trioxide-containing vapor to obtain the high-purity sulfur trioxide gas raw material.

7. The preparation method according to claim 6, characterized in that: The purification is performed using an ultrafiltration membrane; Preferably, the pore size of the ultrafiltration membrane is 0.005-0.02 μm, preferably 0.008-0.01 μm.

8. A device for preparing electronic grade sulfuric acid, characterized in that: The device comprises: an electron beam system, an absorption tower and an ultra-clean filter which are connected in sequence; wherein, The electron beam system is used to irradiate the high-purity sulfur trioxide gas raw material with an electron beam to oxidize sulfur dioxide in the high-purity sulfur trioxide gas raw material into sulfur trioxide; The absorption tower is used to absorb the irradiated sulfur trioxide gas with ultrapure water to obtain crude sulfuric acid liquid; The ultra-clean filter is used to filter the crude sulfuric acid liquid to remove particulate matter in the crude sulfuric acid liquid, thereby obtaining electronic grade sulfuric acid.

9. The device according to claim 8, characterized in that The device further comprises: a first evaporator, a demister and a precision filter which are connected in sequence; wherein the precision filter is connected to the electron beam system; Preferably, the precision filter is provided with an ultrafiltration membrane, and the pore size of the ultrafiltration membrane is 0.005-0.02 μm, preferably 0.008-0.01 μm; Preferably, the electron beam system comprises: a reactor pipe and 2-5 electron beam reactors connected in parallel, preferably 2 or 3; Preferably, the electron beam reactor comprises: a power supply, an electron accelerator, a scanning box exit window and a reactor entrance window; Preferably, the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor are independently made of titanium, beryllium, aluminum, titanium-aluminum alloy or titanium-palladium alloy, preferably titanium-palladium alloy; Preferably, the thickness of the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor are independently 20-150 μm, preferably 40-60 μm; Preferably, the distance between the window foil of the exit window of the scanning box and the window foil of the incident window of the reactor is 40-200 mm, preferably 60-100 mm.

10. The device according to claim 8 or 9, characterized in that A sulfuric acid circulation tank and a cooler are also provided between the absorption tower and the ultra-clean filter. The sulfuric acid circulation tank is connected to the bottom of the absorption tower, and the cooler is connected to the upper part of the absorption tower and the ultra-clean filter respectively; Preferably, an intermediate storage tank is further provided between the cooler and the ultra-clean filter; Preferably, the device further comprises a finished product storage tank connected to the outlet of the ultra-clean filter.

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