VANADIUM-BASED CATALYST, ITS PRODUCTION METHOD, AND ITS APPLICATION

Abstract

Disclosed in the present invention are a vanadium-based catalyst, and a preparation method therefor and the use thereof. The vanadium-based catalyst comprises a carrier and a vanadium-based active material loaded on the carrier, wherein the vanadium-based catalyst is of a strip-shaped structure having a multi-petal-shaped cross section, the number of petals in the multi-petal-shaped cross section is at least three, and there are at least two through holes in the strip-shaped structure in the direction of length thereof; and the shape factor of the vanadium-based catalyst is 70-110. The vanadium-based catalyst of the present invention can be used in a wet sulfuric acid process, and the catalyst is low in terms of filling amount, can achieve a relatively high SO2 conversion rate and a relatively low bed pressure drop by means of a relatively low filling amount, is particularly applicable to the preparation of sulfuric acid by means of the cracking of waste acid in the case of a relatively high impurity content of a feed gas, and is greatly advantageous during long-period operation.

Description

Vanadium-based catalyst and its preparation method and application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202311366228.8 filed on October 20, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of catalyst preparation, and in particular to a vanadium-based catalyst and a preparation method and application thereof. Background Art

[0004] Most alkylation units utilize the sulfuric acid process, which produces a large amount of waste alkylation acid. The waste acid regeneration unit is an environmentally friendly device supporting the alkylation unit. The process primarily involves incinerating and cracking the waste sulfuric acid in a waste acid cracking furnace. The SO2 in the cracking gas is then converted to SO3 using a vanadium-based catalyst, ultimately producing commercial sulfuric acid. The regenerated sulfuric acid is then returned to the alkylation unit for recycling as a catalyst for the sulfuric acid alkylation reaction. However, the waste acid cracking gas contains a high level of dust, which can easily cause subsequent catalyst bed compaction.

[0005] Industrial sulfuric acid production primarily utilizes a catalytic system consisting of vanadium pentoxide as the primary catalyst, potassium sulfate, sodium sulfate, and cesium sulfate as co-catalysts, and diatomaceous earth as a support. This system is known as a vanadium-based catalyst. Existing research on improving the performance of vanadium-based catalysts has primarily focused on the active components, co-catalysts, supports, and preparation processes. However, research on the shape of vanadium-based catalysts is relatively limited.

[0006] Currently, the vanadium-based catalysts used in the sulfuric acid industry come in a variety of shapes, including cylindrical, flake, spherical, ring, and plum blossom shapes. In recent years, cylindrical, ring, and plum blossom shapes have been more commonly used. The Sulfuric Acid Handbook states that the approximate value of the catalyst layer resistance in production can also be calculated using the following formula: ΔP = 5494 × W 1.7 ×r 0.7 ×h, where W is the gas velocity, r is the gas density, and h is the catalyst loading height. 5494 is related to the particle shape parameters of the cylindrical catalyst layer. As can be seen, catalyst particle shape directly affects the flow and diffusion of the reactant gas, and thus the catalyst activity and bed pressure drop. Therefore, studying the relationship between the properties of vanadium-based catalysts and their particle shape is particularly important.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of large bed pressure drop of vanadium-based catalysts in the prior art and to provide a vanadium-based catalyst and its preparation method and application. To improve the performance of vanadium-based catalysts, so that they can achieve higher SO2 conversion rate and lower bed pressure drop with lower loading amount.

[0009] After extensive research, the inventors of the present invention found that the shape factor of the vanadium-based catalyst is affected by many factors, such as the outer diameter of the catalyst particles, the diameter of the internal openings, the number of internal openings, the porosity, and the packing density, and this shape factor in turn affects the activity and fluid dynamics properties of the vanadium-based catalyst.

[0010] In view of the characteristics of the industrial reactor of the sulfuric acid plant, the inventors of the present invention found that by controlling the shape factor of the vanadium-based catalyst, the reaction gas flow can be distributed more evenly between the beds and have a certain residence time, thereby improving the fluid mechanics properties of the catalyst while ensuring the SO2 conversion rate.

[0011] In order to achieve the above object, the present invention provides a vanadium-based catalyst in a first aspect, comprising a carrier and a vanadium-based active material supported on the carrier, wherein the vanadium-based catalyst is a strip structure having a multi-petal cross-section, wherein the number of petals of the multi-petal cross-section is at least 3, and the strip structure has at least 2 through holes along its length; the shape factor of the vanadium-based catalyst is 70-110;

[0012] In formula (1), is the shape factor;

[0013] f is the correction coefficient, f = A / B, A = 2.5*10 -4 , B is the number of petals in the multi-petal cross section;

[0014] ρ is the bulk density of the vanadium-based catalyst, in kg / m 3 ;

[0015] ε is the open porosity of the vanadium-based catalyst;

[0016] N is the number of through holes;

[0017] d is the aperture of the through hole, in m;

[0018] D is the outer diameter of the multi-petal cross section, in m.

[0019] The second aspect of the present invention provides a method for preparing a vanadium-based catalyst, the method comprising: kneading a vanadium-containing compound with diatomaceous earth, extruding a strip to form a strip structure having a multi-petal cross-section, wherein the multi-petal cross-section has at least three petals, and the strip structure has at least two through holes along its length; and then performing a first calcination to make its shape factor 70-110;

[0020] In formula (1), is the shape factor;

[0021] f is the correction coefficient, f = A / B, A = 2.5*10 -4 , B is the number of petals in the multi-petal cross section;

[0022] ρ is the bulk density of the vanadium-based catalyst, in kg / m 3 ;

[0023] ε is the open porosity of the vanadium-based catalyst;

[0024] N is the number of through holes;

[0025] d is the aperture of the through hole, in m;

[0026] D is the outer diameter of the multi-petal cross section, in m.

[0027] The third aspect of the present invention provides the use of the vanadium-based catalyst as described in the first aspect or the vanadium-based catalyst prepared by the preparation method described in the second aspect in the catalytic oxidation of SO2 to produce SO3.

[0028] The fourth aspect of the present invention provides a method for wet-process sulfuric acid production, comprising: contacting a raw gas with a vanadium-based catalyst under conditions where SO2 is catalytically oxidized to produce SO3, and then condensing the raw gas; wherein the raw gas contains SO2, O2 and water; and the vanadium-based catalyst is the vanadium-based catalyst described in the first aspect or the vanadium-based catalyst prepared by the preparation method described in the second aspect.

[0029] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0030] 1) Shape factor of the vanadium-based catalyst of the present invention When the vanadium content is 70-110, it can be used for catalytic oxidation of SO2 to generate SO3. The vanadium-based catalyst can achieve a higher SO2 conversion rate and a lower bed pressure drop at a lower loading amount.

[0031] 2) The vanadium-based catalyst of the present invention is an anti-blocking vanadium-based catalyst, which can be used for wet sulfuric acid production, and is particularly suitable for the cracking of waste acid with a high impurity content in the feed gas to produce sulfuric acid, and has great advantages for long-term operation. DETAILED DESCRIPTION

[0032] The endpoints of the ranges and any values ​​disclosed herein 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 endpoints of each range, the endpoints of each range and 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 to be specifically disclosed herein.

[0033] The first aspect of the present invention provides a vanadium-based catalyst, comprising a carrier and a vanadium-based active material supported on the carrier, wherein the vanadium-based catalyst is a strip structure having a multi-petal cross-section, wherein the multi-petal cross-section has at least three lobes, and the strip structure has at least two through holes along its length. The shape factor of the vanadium-based catalyst is 70-110;

[0034] In formula (1), is the shape factor;

[0035] f is the correction coefficient, f = A / B, A = 2.5*10 -4 , B is the number of petals in the multi-petal cross section;

[0036] ρ is the bulk density of the vanadium-based catalyst, in kg / m 3 ;

[0037] ε is the open porosity of the vanadium-based catalyst;

[0038] N is the number of through holes;

[0039] d is the aperture of the through hole, in m;

[0040] D is the outer diameter of the multi-petal cross section, in m.

[0041] According to the present invention, the bed pressure drop of the vanadium-based catalyst is closely related to the particle shape of the vanadium-based catalyst. The inventors of the present invention have found that the particle shape of the vanadium-based catalyst is affected by many factors such as the outer diameter of the catalyst particles, the diameter of the internal openings, the number of internal openings, the porosity, and the bulk density, and this shape factor in turn affects the activity and fluid dynamics properties of the vanadium-based catalyst. After extensive research, the inventors have found that the shape factor of the vanadium-based catalyst is When the shape factor is 70-110, it can be used to catalytically oxidize SO2 to generate SO3. The vanadium-based catalyst can achieve a higher SO2 conversion rate and a lower bed pressure drop at a lower loading amount. If the shape factor is too low, it will affect the distribution of the gas in the bed, resulting in too short a time for the gas to stay in the catalyst bed, which will affect the SO2 conversion rate and make the SO2 conversion rate lower. If it is too high, higher than 110, it will cause a high bed pressure drop, which will have a great impact on the smooth operation of the device.

[0042] Combined with the characteristics of the industrial reactor of the sulfuric acid plant, the present invention controls the shape factor of the vanadium-based catalyst while ensuring the SO2 conversion rate. The reaction gas flow is distributed more evenly between the beds and has a suitable residence time, which improves the fluid mechanics properties of the catalyst, significantly reduces the catalyst loading amount, reduces production costs, and reduces the bed pressure drop.

[0043] According to the present invention, when the catalyst filling volume in the reactor is consistent, the present invention controls the shape factor of the vanadium-based catalyst. Reduce bed pressure drop.

[0044] The vanadium-based catalyst of the present invention is an anti-blocking vanadium-based catalyst, which can be used for wet sulfuric acid production, and is particularly suitable for the production of sulfuric acid by cracking waste acid with a high impurity content in feed gas, and has great advantages for long-cycle operation.

[0045] According to the present invention, in the strip structure with a multi-petal cross-section, the cross-section of the multi-petal cross-section is a petal-shaped symmetrical structure, such as three petals, four petals, five petals, six petals, etc.; the strip structure is preferably a cylindrical strip.

[0046] According to the present invention, the correction coefficient f is related to the number of petals of the multi-petal cross-section. The more petals there are, the smaller the correction coefficient is, and the fewer petals there are, the larger the correction coefficient is.

[0047] According to the present invention, the outer diameter D of the multi-petal cross section refers to the longest straight-line distance from one edge to the other edge of the multi-petal cross section, or the diameter of the largest circumscribed circle of the multi-petal cross section when the cross section of the multi-petal cross section is a petal-shaped symmetrical structure.

[0048] According to the present invention, the aperture d of the through hole and the outer diameter D of the multi-petal cross section are both measured using a digital display vernier caliper.

[0049] According to the present invention, the method for determining the bulk density ρ of the vanadium-based catalyst adopts the method for determining the bulk density of fertilizer catalysts according to HG / T 4680-2014.

[0050] According to the present invention, the open porosity ε of the vanadium-based catalyst refers to the ratio of the internal open pore specific surface area to the total specific surface area of ​​the vanadium-based catalyst.

[0051] According to the present invention, the shape factor of the vanadium-based catalyst is The range is 70-110, for example, 70, 75, 80, 85, 90, 95, 100, 105, 110, and any value in the range consisting of any two values.

[0052] According to some preferred embodiments of the present invention, the shape factor of the vanadium-based catalyst is It is 80-100.

[0053] According to some embodiments of the present invention, the carrier includes diatomaceous earth; based on the total weight of the diatomaceous earth, the SiO2 content is not less than 90wt%, and the mass ratio of Fe2O3 to Al2O3 is 0.02-0.1:1.

[0054] According to the present invention, the SiO2 content is not less than 90wt%, for example, 90wt%, 90.1wt%, 90.2wt%, 90.3wt%, 90.4wt%, 90.5wt%, 90.6wt%, 90.7wt%, 90.8wt%, 90.9wt%, 91wt%, 91.5wt%, 92wt%, 92.5wt%, 93wt%, 93.5wt%, 94wt%, 94.5wt%, 95wt%, 95.5wt%, 96wt%, and any value in the range consisting of any two values, preferably 92-95wt%.

[0055] According to the present invention, the mass ratio of Fe2O3 to Al2O3 is 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, and any value in the range consisting of any two values, preferably 0.03-0.08:1.

[0056] According to some preferred embodiments of the present invention, based on the total weight of the diatomaceous earth, the SiO2 content is 92-95wt%, and the mass ratio of Fe2O3 to Al2O3 is 0.03-0.08:1.

[0057] According to the present invention, by controlling the mass ratio of Fe2O3 to Al2O3 and the Al2O3 content at the same time, the diatomite structure can be made more stable and have higher strength.

[0058] According to the present invention, the diatomaceous earth of the present invention has a stable structure and higher strength by simultaneously controlling the SiO2 content and the mass ratio of Fe2O3 to Al2O3. Therefore, the diatomaceous earth can be used as a carrier for preparing a catalyst. The prepared catalyst can still maintain a high strength when the average pore diameter is 100-400 nm, which can improve the conversion rate of SO2. This shows that using this diatomaceous earth as a carrier can make the vanadium-based catalyst have higher active material dispersibility.

[0059] According to some preferred embodiments of the present invention, the Al2O3 content is 2.5-4wt%, for example, 2.5wt%, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt%, 4wt%, and any value in the range consisting of any two values, preferably 2.8-3.5wt%.

[0060] According to some preferred embodiments of the present invention, the Fe2O3 content is not more than 0.3wt%, for example, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, and any value in the range consisting of any two values, preferably 0.1-0.3wt%.

[0061] The diatomaceous earth of the present invention has a high SiO2 content and a low impurity Fe2O3 content, and its strength and stability are higher than those of natural diatomaceous earth and commonly used diatomaceous earth.

[0062] The diatomaceous earth of the present invention has higher stability when meeting the above parameters.

[0063] According to some embodiments of the present invention, based on the total weight of the vanadium-based catalyst, the content of the diatomaceous earth is 60-75 wt%, for example, 60 wt%, 62 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, and any value in a range consisting of any two values, preferably 65-70 wt%.

[0064] In some embodiments of the present invention, the average particle size of the diatomaceous earth is 0.3-1 μm, for example, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, and any value in a range consisting of any two values, preferably 0.3-0.7 μm.

[0065] In some embodiments of the present invention, the diatomaceous earth is Melosomum diatomaceous earth.

[0066] In some embodiments of the present invention, the shell of the diatomaceous earth is a hollow cylinder, preferably connected by small spines on the periphery of the shell to form a chain-like group, and the holes on the cylinder surface are connected to the central hole.

[0067] According to the present invention, diatomaceous earth is formed into a hollow cylinder, which, from a mechanical perspective, has the best strength and is not easily brittle. During processing, it can better maintain its original shape. Therefore, as a carrier, it can form a group with well-developed pores, which has good strength and good mass and heat transfer.

[0068] In some embodiments of the present invention, the ignition loss of the diatomaceous earth is 0.01-3 wt%, preferably 0.015-1 wt%.

[0069] According to the present invention, the method for detecting the loss on ignition is as follows: using the burning weighing method: specifically: take a 10-gram sample, accurate to 0.0001 grams, place it in a porcelain crucible that has been burned to a constant weight, place it in a resistance heating furnace, slowly heat it to about 1000°C, keep the temperature constant for 15-20 minutes, take out the dry pot, place it in a desiccator, cool it to room temperature, and weigh it. Then, the obtained value is imported into the formula for calculation: loss on ignition = sample amount - net weight after burning.

[0070] In some embodiments of the present invention, the bulk density of the diatomaceous earth is 0.3-0.5 g / mL, preferably 0.35-0.45 g / mL.

[0071] The present invention adopts the flat plate bulk density method to measure the bulk density of diatomite.

[0072] According to some embodiments of the present invention, the ratio of the outer diameter D of the multi-petal cross-section to the aperture d of the through hole is 3-7:1, for example, 3:1, 3.5:1, 3.7:1, 4:1, 4.2:1, 4.5:1, 4.7:1, 5:1, 5.2:1, 5.5:1, 5.7:1, 6:1, 6.2:1, and any value in the range consisting of any two numerical values, preferably 4-6:1, and more preferably 4.5-5.7:1.

[0073] According to the present invention, by controlling the ratio of the outer diameter D of the multi-petal cross section to the aperture d of the through hole to meet the above range, the residence time of the airflow in the catalyst bed can be effectively prolonged.

[0074] According to some embodiments of the present invention, the ratio of the length L of the vanadium-based catalyst to the outer diameter D of the multi-petal cross-section is 1-1.5:1, for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, and any value in the range consisting of any two values, preferably 1-1.2:1.

[0075] According to the present invention, by controlling the ratio of the length L to the outer diameter D of the multi-petal cross section to meet the above range, the air flow is distributed more evenly in the catalyst bed.

[0076] According to some embodiments of the present invention, the number of petals of the multi-petal cross-section is 3-8, for example, 3, 4, 5, 6, 7, 8, preferably 5-6.

[0077] According to some embodiments of the present invention, the number N of the through holes is 2-7, for example, 2, 3, 4, 5, 6, 7, preferably 2-6.

[0078] According to some embodiments of the present invention, the through hole is cylindrical.

[0079] According to the present invention, the bed pressure drop can be further reduced by controlling the number and shape of the through holes as described above.

[0080] According to some embodiments of the present invention, the diameter d of the through hole is 3-5 mm, preferably 3-4 mm.

[0081] According to some embodiments of the present invention, the open porosity of the vanadium-based catalyst is 0.09-0.25, preferably 0.12-0.22.

[0082] According to some embodiments of the present invention, the bulk density of the vanadium-based catalyst is 400-550 kg / m 3 , preferably 450-500kg / m 3 .

[0083] According to some embodiments of the present invention, the strength of the vanadium-based catalyst is ≥70 N / cm, preferably 80-120 N / cm, and more preferably 90-120 N / cm.

[0084] In the present invention, the strength is expressed as radial crushing resistance, and the radial crushing resistance is measured using the method for measuring the crushing resistance of fertilizer catalyst particles in HG / T 2782-2011.

[0085] According to some embodiments of the present invention, the attrition rate of the vanadium-based catalyst is ≤5%.

[0086] In the present invention, the attrition rate is measured according to HG / T 2976-2011 Fertilizer Catalyst Attrition Rate, wherein the sample is dried at (120±5)°C for 2h.

[0087] According to some embodiments of the present invention, the mass ratio of the carrier to the vanadium-based active material is 60-75:6-8.5, for example, 60-75:6, 60-75:6.2, 60-75:6.5, 60-75:6.8, 60-75:7, 60-75:7.2, 60-75:7.5, 60-75:7.8, 60-75:8, 60-75:8.2, 60-75:8.5, and any value in the range consisting of any two values, preferably 65-70:6.5-8.

[0088] According to some embodiments of the present invention, the vanadium-based active material is vanadium pentoxide.

[0089] According to some embodiments of the present invention, the vanadium-based catalyst further comprises a potassium-containing compound supported on a carrier, preferably potassium sulfate.

[0090] According to some embodiments of the present invention, in the vanadium-based catalyst, the molar ratio of potassium to vanadium is 2-4:1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 3.9:1, 4:1, and any value in the range consisting of any two values, preferably 2.5-3.5:1.

[0091] In the present invention, the molar ratio of potassium to vanadium is also referred to as the potassium-vanadium ratio. A too small potassium-vanadium ratio will affect the activity of the vanadium-based catalyst, while a too large potassium-vanadium ratio will increase production costs.

[0092] In some embodiments of the present invention, based on the total weight of the vanadium-based catalyst, the content of potassium sulfate is 12-30 wt%, for example, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 25 wt%, 30 wt%, and any value in a range consisting of any two values, preferably 15-22 wt%.

[0093] According to some embodiments of the present invention, the vanadium-based catalyst further comprises a promoter supported on a carrier; the mass ratio of the carrier to the promoter is 60-75:3.5-10, for example, 60-75:3.5, 60-75:4, 60-75:4.5, 60-75:5, 60-75:5.5, 60-75:6, 60-75:6.5, 60-75:7, 60-75:7.5, 60-75:8, 60-75:8.5, 60-75:9, 60-75:9.5, 60-75:10, and any value in the range consisting of any two values, preferably 65-70:4-8.

[0094] In some embodiments of the present invention, the auxiliary agent is selected from one or more of sodium sulfate, rubidium sulfate, cesium sulfate, lanthanum oxide, cerium oxide and praseodymium oxide.

[0095] In the present invention, the adjuvant can further improve the low-temperature activity of the vanadium-based catalyst and reduce the activation temperature of the vanadium-based catalyst.

[0096] According to the present invention, the vanadium-based catalyst contains, in addition to the above-mentioned carrier, active component and auxiliary agent, a binder and other substances, wherein the binder is selected from montmorillonite, attapulgite and the like.

[0097] In some embodiments of the present invention, based on the total weight of the vanadium-based catalyst, the content of the binder is 0.5-2.5 wt%, for example, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, and any value in the range consisting of any two values, preferably 1-2 wt%.

[0098] The second aspect of the present invention provides a method for preparing a vanadium-based catalyst, the method comprising: kneading a vanadium-containing compound with diatomaceous earth, extruding a strip to form a strip structure having a multi-petal cross-section, wherein the multi-petal cross-section has at least three petals, and the strip structure has at least two through holes along its length; and then performing a first calcination to make its shape factor 70-110;

[0099] In formula (1), is the shape factor;

[0100] f is the correction coefficient, f = A / B, A = 2.5*10 -4 , B is the number of petals in the multi-petal cross section;

[0101] ρ is the bulk density of the vanadium-based catalyst, in kg / m 3 ;

[0102] ε is the open porosity of the vanadium-based catalyst;

[0103] N is the number of through holes;

[0104] d is the aperture of the through hole, in m;

[0105] D is the outer diameter of the multi-petal cross section, in m.

[0106] The inventors of the present invention have found that the shape factor of the vanadium-based catalyst When the shape factor is 70-110, it can be used to catalytically oxidize SO2 to generate SO3. The vanadium-based catalyst can achieve a higher SO2 conversion rate and a lower bed pressure drop at a lower loading amount. If the shape factor is too low, it will affect the distribution of the gas in the bed, resulting in too short a time for the gas to stay in the catalyst bed, which will affect the SO2 conversion rate and make the SO2 conversion rate lower. Too high, when it is higher than 110, will lead to a high bed pressure drop, which will have a great impact on the smooth operation of the device. It can provide a basis for the number of petals and opening conditions of catalyst molding. Before the catalyst is molded, it can be The formula is used to fit the required molding parameters, such as the outer diameter of the catalyst particles, the diameter of the inner openings, the number of the inner openings, etc.

[0107] According to the present invention, the shape factor of the vanadium-based catalyst is The range is 70-110, for example, 70, 75, 80, 85, 90, 95, 100, 105, 110, and any value in the range consisting of any two values.

[0108] According to some embodiments of the present invention, the shape factor of the vanadium-based catalyst is It is 80-100.

[0109] According to some embodiments of the present invention, the open porosity of the vanadium-based catalyst is 0.09-0.25, preferably 0.12-0.22.

[0110] According to some embodiments of the present invention, the bulk density of the vanadium-based catalyst is 400-550 kg / m 3 , preferably 450-500kg / m 3 .

[0111] According to some embodiments of the present invention, the ratio of the outer diameter D of the multi-petal cross section to the aperture d of the through hole is 3-7:1, preferably 4-6:1.

[0112] According to some embodiments of the present invention, the number of petals of the multi-petal cross-section is 3-8, preferably 5-6.

[0113] According to some embodiments of the present invention, the number N of the through holes is 2-7, preferably 2-6.

[0114] According to the present invention, the parameters and determination methods in formula (1) can refer to the previous description and will not be repeated here.

[0115] According to some embodiments of the present invention, the step of kneading the vanadium-containing compound and diatomaceous earth includes:

[0116] (1) separating and purifying the diatomaceous earth raw material and the dispersant together in a hydrocyclone separator, drying, and then performing a second calcination to obtain treated diatomaceous earth;

[0117] (2) neutralizing vanadium water prepared from potassium hydroxide and vanadium pentoxide with sulfuric acid to obtain a reaction product; then mixing the reaction product with the treated diatomaceous earth, an optional auxiliary agent, and an optional binder, and then kneading.

[0118] According to the present invention, a hydrocyclone separator is used to separate and purify diatomaceous earth raw materials, which can effectively remove impurities such as Fe2O3, Al2O3, CaO, MgO, and reduce the bulk density, thereby improving the purity of SiO2, with the SiO2 content reaching more than 90%, and improving the structural stability and support strength of the diatomaceous earth carrier.

[0119] According to the present invention, due to the great instability of natural diatomite quality due to geological causes, the structure of natural diatomite is unstable and uneven, and there are many impurities in natural diatomite, and the SiO2 content is low, resulting in insufficient support of the carrier for the active phase, and the catalyst strength cannot be guaranteed. Although the refined diatomite after the prior art treatment can be used as a carrier for vanadium-based catalysts, it is still impossible to solve the problem of the bed of vanadium-based catalysts being easily hardened. The treatment method provided by the present invention simultaneously controls the SiO2 content and the mass ratio of Fe2O3 to Al2O3 in the diatomite, making the diatomite structure more stable, with higher strength, and can be used as a carrier for preparing catalysts with higher active material dispersibility.

[0120] The present invention uses a physical process to treat diatomite, optimizes the iron-aluminum ratio in the diatomite, thereby avoiding the generation of wastewater by the acid washing method used in traditional refining. The high-temperature treatment of the second calcination makes the structure more stable, so that the treated diatomite has better plasticity, which not only improves the strength of the catalyst but also reduces the attrition rate of the catalyst, resulting in a longer screening cycle for the catalyst. At the same time, the particle shape factor under the same molding conditions is also lower than that before modification.

[0121] According to some embodiments of the present invention, the slurry inlet pressure of the hydrocyclone separator is 0.2-1MPa, for example, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1MPa, and any value in the range consisting of any two numerical values, preferably 0.3-0.8MPa; the classification fineness is 0.3-1μm, for example, 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, and any value in the range consisting of any two numerical values, preferably 0.3-0.7μm.

[0122] According to the present invention, the average particle size of the treated diatomaceous earth is 0.3-1 μm, preferably 0.3-0.7 μm, by controlling the slurry inlet pressure and the classification fineness of the hydrocyclone separator.

[0123] According to some embodiments of the present invention, the second calcination temperature is 350-500° C., preferably 350-450° C.; and the time is 1-2 h, preferably 1.2-2 h.

[0124] According to some embodiments of the present invention, the diatomaceous earth raw material is Mesophyllium diatomaceous earth.

[0125] Preferably, the silicon dioxide content of the diatomaceous earth is above 85%.

[0126] The diatomite raw material used in the present invention is natural straight chain algae, whose shell porosity is the highest among diatomite, and its pore volume, main pore diameter and specific surface area are larger than those of other species, especially the inner surface.

[0127] According to some embodiments of the present invention, the diatomaceous earth is selected from one or more of Zhejiang diatomaceous earth, Yunnan diatomaceous earth and Changbai diatomaceous earth.

[0128] According to some embodiments of the present invention, the shell of the diatomaceous earth raw material is a hollow cylinder, the shells are connected by small thorns on the periphery of the shell to form a chain-like group, and the holes on the cylinder surface are connected to the central hole.

[0129] According to some embodiments of the present invention, the SiO2 content in the treated diatomaceous earth is not less than 90wt%, preferably 92-95wt%; the mass ratio of Fe2O3 to Al2O3 is 0.02-0.1:1, preferably 0.03-0.08:1.

[0130] According to the present invention, the SiO2 content is not less than 90wt%, for example, 90wt%, 90.1wt%, 90.2wt%, 90.3wt%, 90.4wt%, 90.5wt%, 90.6wt%, 90.7wt%, 90.8wt%, 90.9wt%, 91wt%, 91.5wt%, 92wt%, 92.5wt%, 93wt%, 93.5wt%, 94wt%, 94.5wt%, 95wt%, 95.5wt%, 96wt%, and any value in the range consisting of any two values, preferably 92-95wt%.

[0131] According to the present invention, the mass ratio of Fe2O3 to Al2O3 is 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, and any value in the range consisting of any two values, preferably 0.03-0.08:1.

[0132] The inventors of the present invention have discovered that by controlling the mass ratio of Fe2O3 to Al2O3 and the Al2O3 content at the same time, the diatomaceous earth structure can be made more stable and have higher strength.

[0133] According to the present invention, the vanadium-based catalyst prepared using the treated diatomaceous earth as a carrier has high strength and is more likely to form a shape factor within the aforementioned range.

[0134] According to some preferred embodiments of the present invention, the Al2O3 content is 2.5-4wt%, for example, 2.5wt%, 2.8wt%, 3wt%, 3.2wt%, 3.5wt%, 3.8wt%, 4wt%, and any value in the range consisting of any two values, preferably 2.8-3.5wt%.

[0135] According to some preferred embodiments of the present invention, the Fe2O3 content is not more than 0.3wt%, for example, 0.05wt%, 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, and any value in the range consisting of any two values, preferably 0.1-0.3wt%.

[0136] The diatomaceous earth of the present invention has a high SiO2 content and a low impurity Fe2O3 content, and its strength and stability are higher than those of natural diatomaceous earth and commonly used diatomaceous earth.

[0137] The diatomaceous earth of the present invention has higher stability when meeting the above parameters.

[0138] According to some embodiments of the present invention, the dispersant is selected from one or more of sodium hexametaphosphate, sodium tripolyphosphate and sodium pyrophosphate.

[0139] According to the present invention, the addition of the dispersant is more conducive to removing impurities such as Fe2O3, improving the purity of SiO2, and ensuring the content of Al2O3.

[0140] According to some embodiments of the present invention, the dispersant is added in an amount of 1-5 wt % of the diatomaceous earth.

[0141] According to some embodiments of the present invention, in the vanadium water, the molar ratio of potassium to vanadium is 2-4:1, preferably 2.5-3.5:1.

[0142] According to some embodiments of the present invention, the mass ratio of the treated diatomaceous earth to the auxiliary agent is 60-75:3.5-10, preferably 65-70:4-8.

[0143] Preferably, the auxiliary agent is selected from one or more of sodium sulfate, rubidium sulfate, cesium sulfate, lanthanum oxide, cerium oxide and praseodymium oxide.

[0144] According to some embodiments of the present invention, the mass ratio of the treated diatomaceous earth to the binder is 60-75:0.5-2.5, preferably 65-70:1-2.

[0145] Preferably, the binder is selected from one or more of montmorillonite, attapulgite and methyl cellulose.

[0146] The inventors of this application have discovered that the presence of small amounts of impurities is unrelated to the activity of the catalyst, but is significantly associated with its mechanical strength and service life. Therefore, the present invention employs a kneading method to add a binder (e.g., montmorillonite) to the active component and carrier. This method more effectively combines the active component and carrier than conventional mixing and grinding methods, enhancing the carrier's strength and producing a catalyst with higher catalytic activity.

[0147] According to some embodiments of the present invention, the mass ratio of the diatomaceous earth to the vanadium-containing compound is 60-75:6-8.5, for example, 60-75:6, 60-75:6.2, 60-75:6.5, 60-75:6.8, 60-75:7, 60-75:7.2, 60-75:7.5, 60-75:7.8, 60-75:8, 60-75:8.2, 60-75:8.5, and any value in the range consisting of any two values, preferably 65-70:6.5-8.

[0148] According to some embodiments of the present invention, the vanadium-containing compound includes a compound containing pentavalent vanadium, preferably vanadium pentoxide.

[0149] According to some embodiments of the present invention, the temperature of the first calcination is 580-650° C., and the time is 1-2 hours.

[0150] According to some embodiments of the present invention, the first calcination is performed in an atmosphere of superheated water vapor.

[0151] According to some embodiments of the present invention, the temperature of the superheated steam is 120-150°C.

[0152] Preferably, the first calcination is carried out in a vertical tubular furnace, and saturated superheated water vapor at 120-150° C. is introduced at the calcination inlet, and the saturated superheated water vapor is continuously introduced throughout the entire calcination process.

[0153] The inventors have found through research that compared with calcination without humidified air, the pore size distribution can be shifted toward large pores during the first calcination process by humidified air. Therefore, the introduction of water vapor and humidified air during the calcination process has a pore-expanding effect on the carrier. The average pore size after pore expansion is about 150-500nm, which is conducive to the diffusion of reactant molecules in the pores to reach the active centers on the inner surface of the catalyst.

[0154] The third aspect of the present invention provides the use of the vanadium-based catalyst as described in the first aspect or the vanadium-based catalyst prepared by the preparation method described in the second aspect in the catalytic oxidation of SO2 to produce SO3.

[0155] According to the present invention, the shape factor of the vanadium-based catalyst of the present invention is When the vanadium content is 70-110, it can be used for catalytic oxidation of SO2 to generate SO3. The vanadium-based catalyst can achieve a higher SO2 conversion rate and a lower bed pressure drop at a lower loading amount.

[0156] A fourth aspect of the present invention provides a method for wet-process sulfuric acid production, comprising: contacting a raw gas with the vanadium-based catalyst described in the first aspect or the vanadium-based catalyst prepared by the preparation method described in the second aspect under conditions where SO2 is catalytically oxidized to produce SO3, and then condensing the raw gas; wherein the raw gas contains SO2, O2 and water.

[0157] The vanadium-based catalyst of the present invention can catalytically oxidize SO2 in the raw gas to generate SO3, and finally obtain concentrated sulfuric acid.

[0158] According to some embodiments of the present invention, the contacting is carried out in a fixed bed reactor, and the packing factor of the vanadium-based catalyst is below 700 L / (t·d), preferably 500-600 L / (t·d).

[0159] According to the present invention, the fixed bed reactor is an important device in the wet process sulfuric acid production device, and the lower the filling coefficient is, the lower the required filling amount is.

[0160] According to some embodiments of the present invention, the volume percentage of SO2 in the raw gas is 1-9%.

[0161] According to some embodiments of the present invention, the volume percentage of O2 in the raw gas is 2-22%. When the content of O2 and water is insufficient, they can be added as needed.

[0162] According to some embodiments of the present invention, the feed gas is spent acid cracking gas or acid gas.

[0163] According to some embodiments of the present invention, the inlet temperature of the feed gas is 370-440°C.

[0164] The present invention is described in detail below through preparation examples and examples, but the protection scope of the present invention is not limited to the following description.

[0165] In the following preparations, examples, and comparative examples, if no specific conditions are specified, conventional conditions or those recommended by the manufacturer were followed. Reagents or instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0166] The diatomite raw material is Changbai diatomite, wherein the SiO2 content is 84.18wt%, the Fe2O3 content is 1.14wt%, the Al2O3 content is 4.38wt%, the average particle size is 2.7μm, and the strength is 50N / cm.

[0167] The detection method of SiO2 content, Fe2O3 content and Al2O3 content in diatomite is based on the chemical composition analysis method of HG / T 2516-2013 sulfur dioxide oxidation catalyst for sulfuric acid production.

[0168] Average particle size: measured using an average particle size analyzer.

[0169] The average pore size and specific surface area of ​​the catalysts were determined by the BET method.

[0170] Catalyst strength: in accordance with HG / T 2782-2011 Determination of crushing resistance of fertilizer catalyst particles.

[0171] Preparation Example 1

[0172] The diatomite raw material was added to a hydrocyclone separator, and 2 wt% of the dispersant sodium hexametaphosphate was added to the diatomite raw material. The slurry feed pressure was controlled to 0.3 MPa and the classification fineness was 0.5 μm. Centrifugal impurities were removed. After the impurities were removed, the raw material was dried and calcined at 350° C. for 2 hours to obtain treated diatomite S1.

[0173] After testing, the SiO2 content of the treated diatomaceous earth S1 was 90.1wt%, the Fe2O3 content was 0.2wt%, the Al2O3 content was 3.2wt%, the mass ratio of Fe2O3 to Al2O3 was 0.06, the average particle size was 1μm, the ignition loss was 0.85%, and the bulk density was 0.42g / mL.

[0174] Preparation Example 2

[0175] The diatomite raw material is added to the hydrocyclone separator, and at the same time, 5wt% of the dispersant sodium hexametaphosphate is added to the diatomite raw material. The slurry feed pressure is controlled to 0.7MPa and the classification fineness is 0.3μm. Centrifugal impurities are removed. The raw material after impurities removal is dried and calcined at 400℃ for 1.2h to obtain the treated diatomite S2.

[0176] After testing, the SiO2 content of the treated diatomaceous earth S2 was 92wt%, the Fe2O3 content was 0.1wt%, the Al2O3 content was 3wt%, the mass ratio of Fe2O3 to Al2O3 was 0.03, the average particle size was 0.4μm, the ignition loss was 0.5%, and the bulk density was 0.32g / mL.

[0177] Example 1

[0178] 18.32 kg of potassium hydroxide and 8.5 kg of vanadium pentoxide were dissolved in water to prepare vanadium water with a vanadium pentoxide concentration of 210 g / L; 40.48 L of the vanadium water was neutralized with 8.89 L of concentrated sulfuric acid to obtain a mixed solution of V2O5 and K2SO4; the mixed solution was uniformly mixed with 0.68 kg of cesium sulfate, and then added to a kneader with 4.75 kg of sodium sulfate, 55 kg of the treated diatomaceous earth S1 obtained in Preparation Example 1, and 2.33 kg of montmorillonite, and fully kneaded. Water was added to make it a plastic material, and then extruded into a catalyst with five petals and four holes; then, after drying, calcined at 650°C for 1 hour by continuously introducing 120°C superheated steam at the calcination inlet to produce 100 kg of vanadium-based catalyst C1.

[0179] The vanadium-based catalyst C1 has a through-hole number N of 4, a through-hole diameter d of 0.003 m, an outer diameter D of 0.017 m in the five-petal cross section, an opening ratio ε of 0.124, a length of about 0.017 m, and a bulk density ρ of 490 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C1 is It is 88.

[0180] Example 2

[0181] 13.55 kg of potassium hydroxide and 7.1 kg of vanadium pentoxide are prepared into vanadium water with a vanadium pentoxide concentration of 210 g / L; 33.8 L of vanadium water is neutralized with 7.43 L of concentrated sulfuric acid to obtain a mixed solution of V2O5 and K2SO4; the mixed solution, 5.75 kg of sodium sulfate, 64 kg of treated diatomaceous earth S2 obtained in Preparation Example 2, and 1 kg of montmorillonite are added to a kneader and fully kneaded, water is added to make it a plastic material, and then it is extruded into a catalyst with five petals and two holes; then, after drying, 150°C superheated steam is continuously introduced into the calcination inlet at a temperature of 600°C and calcined for 1 hour to prepare 100 kg of vanadium-based catalyst C2.

[0182] The vanadium-based catalyst C2 has a through-hole number N of 2, a through-hole diameter d of 0.004 m, an outer diameter D of 0.015 m of the five-petal cross section, an opening ratio ε of 0.125, a length of about 0.018 m, and a bulk density ρ of 450 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C2 is It is 98.

[0183] Example 3

[0184] 15.7 kg of potassium hydroxide and 7.5 kg of vanadium pentoxide are prepared into vanadium water with a vanadium pentoxide concentration of 220 g / L; 34.1 L of vanadium water is neutralized with 7.85 L of concentrated sulfuric acid to obtain a mixed solution of V2O5 and K2SO4; the mixed solution, 1 kg of cerium oxide, 4.5 kg of sodium sulfate, 61.6 kg of treated diatomaceous earth S2 obtained in Preparation Example 2, and 1 kg of montmorillonite are added to a kneader and fully kneaded, water is added to make it a plastic material, and then it is extruded into a catalyst with six petals and three holes; then, after drying, 150°C superheated steam is continuously introduced into the calcination inlet at a temperature of 600°C and calcined for 1 hour to obtain 100 kg of vanadium-based catalyst C3.

[0185] The vanadium-based catalyst C3 has a through-hole number N of 3, a through-hole diameter d of 0.003 m, an outer diameter D of 0.015 m for the six-petal cross section, an open porosity ε of 0.12, a length of about 0.016 m, and a bulk density ρ of 470 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C3 is is 95.

[0186] Example 4

[0187] 15.1 kg of potassium hydroxide and 7.0 kg of vanadium pentoxide are prepared into vanadium water with a vanadium pentoxide concentration of 230 g / L; 30.43 L of vanadium water is neutralized with 7.32 L of concentrated sulfuric acid to obtain a mixed solution of V2O5 and K2SO4; the mixed solution, 0.65 kg of lanthanum oxide, 1 kg of cesium sulfate, 4.5 kg of sodium sulfate, 63.11 kg of treated diatomaceous earth S2 obtained in Preparation Example 2, and 0.5 kg of montmorillonite are added to a kneader and fully kneaded, water is added to make it a plastic material, and then it is extruded into a catalyst with five petals and two holes; then, after drying, 150°C superheated steam is continuously introduced into the calcination inlet at a temperature of 600°C and calcined for 1 hour to prepare 100 kg of vanadium-based catalyst C4.

[0188] The vanadium-based catalyst C4 has a through-hole number N of 2, a through-hole diameter d of 0.003 m, an outer diameter D of 0.014 m of the five-petal cross section, an opening ratio ε of 0.092, a length of about 0.02 m, and a bulk density ρ of 450 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C4 is It is 76.

[0189] Example 5

[0190] 15.1 kg of potassium hydroxide and 7.0 kg of vanadium pentoxide are prepared into vanadium water with a vanadium pentoxide concentration of 230 g / L; 30.43 L of vanadium water is neutralized with 7.32 L of concentrated sulfuric acid to obtain a mixed solution of V2O5 and K2SO4; the mixed solution, 0.65 kg of lanthanum oxide, 1 kg of praseodymium oxide, 4.5 kg of sodium sulfate, 63.11 kg of treated diatomaceous earth S2 obtained in Preparation Example 2, and 0.5 kg of montmorillonite are added to a kneader and fully kneaded, water is added to make it a plastic material, and then it is extruded into a catalyst with six petals and four holes; then, after drying, 150°C superheated steam is continuously introduced into the calcination inlet at a temperature of 600°C and calcined for 1 hour to prepare 100 kg of vanadium-based catalyst C5.

[0191] The vanadium-based catalyst C5 has a through-hole number N of 4, a through-hole diameter d of 0.004 m, an outer diameter D of 0.019 m of the six-petal cross section, an open porosity ε of 0.177, a length of about 0.019 m, and a bulk density ρ of 450 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C5 is It is 109.

[0192] Example 6

[0193] The vanadium-based catalyst C6 was prepared according to the method of Example 4, except that the catalyst was extruded into a four-petal, four-hole shaped catalyst.

[0194] The vanadium-based catalyst C6 has a through-hole number N of 4, a through-hole diameter d of 0.0025 m, an outer diameter D of 0.016 m, an opening ratio ε of 0.098, a length of about 0.018 m, and a bulk density ρ of 500 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C6 is is 80.

[0195] Example 7

[0196] The vanadium-based catalyst C7 was prepared according to the method of Example 4, except that the catalyst was extruded into a six-petal, three-hole shaped catalyst.

[0197] The vanadium-based catalyst C7 has a through-hole number N of 3, a through-hole diameter d of 0.0035 m, an outer diameter D of 0.017 m, an opening ratio ε of 0.127, a length of about 0.02 m, and a bulk density ρ of 500 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C7 is It is 78.

[0198] Example 8

[0199] The vanadium-based catalyst C8 was prepared according to the method of Example 4, except that the catalyst was extruded into a five-petal, six-hole shaped catalyst.

[0200] The vanadium-based catalyst C8 has a through-hole number N of 6, a through-hole diameter d of 0.0048 m, an outer diameter D of 0.025 m, an opening ratio ε of 0.22, a length of about 0.025 m, and a bulk density ρ of 500 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C8 is is 100.

[0201] Example 9

[0202] The vanadium-based catalyst C9 was prepared according to the method of Example 4, except that superheated water vapor was not introduced into the calcination inlet during calcination.

[0203] The bulk density of the vanadium-based catalyst C9 was 470 kg / m 3 The open porosity ε is 0.092 and the length is about 0.02m. According to formula (1), the shape factor of the vanadium-based catalyst C9 is It is 79.

[0204] Example 10

[0205] The vanadium-based catalyst C10 was prepared according to the method of Example 4, except that the treated diatomaceous earth S2 obtained in Preparation Example 2 was replaced by diatomaceous earth raw material (untreated); the rest was the same as Example 4.

[0206] The bulk density of the vanadium-based catalyst C10 was 440 kg / m 3 , the open porosity ε is 0.092, and the length is about 0.02m. According to formula (1), the shape factor of the vanadium-based catalyst C10 is is 75.

[0207] Example 11

[0208] The vanadium-based catalyst C11 was prepared according to the method of Example 4, except that the treated diatomaceous earth S2 obtained in Preparation Example 2 was replaced by diatomaceous earth raw material (untreated), and the diatomaceous earth was extruded into five petals and four holes; the rest was the same as Example 4.

[0209] The vanadium-based catalyst C10 has a through-hole number N of 4, a through-hole diameter d of 0.0032 m, an outer diameter D of 0.017 m of the five-petal cross section, an open porosity ε of 0.142, a length of about 0.02 m, and a bulk density ρ of 450 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst C10 is It is 107.

[0210] Comparative Example 1

[0211] The vanadium-based catalyst D1 was prepared according to the method of Example 4, except that the catalyst was extruded into four-petal, four-hole catalysts.

[0212] The vanadium-based catalyst D1 has a through-hole number N of 4, a through-hole diameter d of 0.002 m, an outer diameter D of 0.013 m, an opening ratio ε of 0.095, a length of about 0.015 m, and a bulk density ρ of 500 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst D1 is It is 141.

[0213] Comparative Example 2

[0214] The vanadium-based catalyst D2 was prepared according to the method of Example 4, except that it was extruded into a five-petal, one-hole catalyst.

[0215] The vanadium-based catalyst D2 has a through-hole number N of 1, a through-hole diameter d of 0.0025 m, an outer diameter D of 0.009 m in the five-petal cross section, an open porosity ε of 0.077, a length of about 0.009 m, and a bulk density ρ of 510 kg / m 3 According to formula (1), the shape factor of the vanadium-based catalyst D2 is It is 226.

[0216] Comparative Example 3

[0217] The vanadium-based catalyst D3 was prepared according to the method of Example 4, except that it was extruded into a five-petal, one-hole catalyst.

[0218] The vanadium-based catalyst D3 has a through-hole number N of 1, a through-hole diameter d of 0.01 m, an outer diameter D of 0.025 m of the five-petal cross section, and a bulk density ρ of 470 kg / m 3 , the opening ratio ε is 0.16, and the length is about 0.025m. According to formula (1), the shape factor of the vanadium-based catalyst D3 is It is 46.

[0219] Test Case

[0220] The catalysts obtained in Examples 1-11 and Comparative Examples 1-3 were loaded into the first bed of the SO2 converter in a waste acid cracking wet sulfuric acid production unit. When the operation was stable, a differential pressure gauge was used to detect the pressure drop of the bed to obtain the single bed pressure drop. As the reaction proceeded, when the pressure drop of the bed approached 2 kPa, the screening cycle was reached. The SO2 converter was an adiabatic reactor with a reactor diameter of 3500 mm. The reactor inlet gas velocity was 11802 Nm 3 / h; the intake gas composition was SO2: 5.34% (volume fraction), H2O: 7.87% (volume fraction), and the balance was air; the system pressure was atmospheric pressure. The results are shown in Table 1.

[0221] The SO2 single-layer conversion rate is calculated according to the following formula:

[0222] Where:

[0223] E——SO2 monolayer conversion rate, expressed in %;

[0224] ——the volume fraction of sulfur dioxide in the reactor inlet gas, expressed in %;

[0225] ——The volume fraction of sulfur dioxide in the reactor outlet gas, expressed in %.

[0226] The arithmetic mean of three consecutive measurement results is taken as the measurement result; the absolute difference between the three measurement results shall not exceed 1.0%.

[0227] Table 1

[0228] From the results in Table 1, it can be seen that the shape factors of the catalysts obtained by using Examples 1-11 of the present invention are Between 70-110, the filling volume is 21m 3 When the SO2 single-layer conversion rate is greater than 81%, the single-bed pressure drop is less than 0.9kPa.

[0229] Compared with Example 4, Examples 10 and 11, which did not treat the diatomaceous earth raw material, exhibited lower catalyst strength and shorter sieving cycles. In particular, Example 11, which had a greater number of through-holes, exhibited an even shorter sieving cycle. This demonstrates that treating the diatomaceous earth raw material can improve catalyst strength and sieving cycles.

[0230] The shape factor of the catalyst obtained in Comparative Example 1 When the loading amount is the same as that in Example 4, the SO2 single-layer conversion rate is only 79.2%, and the single-bed pressure drop is as high as 1.04 kPa.

[0231] The shape factor of the catalyst obtained in Comparative Example 2 When the SO2 conversion rate per layer is equal to that in Example 4, the loading amount is 30m 3 , the pressure drop of a single bed is as high as 1.2kPa.

[0232] The shape factor of the catalyst obtained in Comparative Example 3 The SO2 single layer conversion rate is only 75.0% when the loading amount is significantly greater than that of Example 4.

[0233] In summary, the shape factor of vanadium-based catalysts When the shape factor is between 70 and 110, the vanadium-based catalyst of the present invention can achieve a higher SO2 conversion rate and a lower bed pressure drop at a lower loading amount. Too low, below 70, will affect the distribution of gas in the bed, resulting in too short a time for gas in the catalyst bed, thus affecting the low conversion rate of SO2; if the shape factor Too high, above 110, will result in excessive bed pressure drop.

[0234] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A vanadium-based catalyst comprising diatomite as a carrier and a vanadium-based active material which comprises vanadium pentoxide supported on the carrier, wherein the vanadium-based catalyst has a strip-shaped structure with a multi-lobed cross-section, wherein the number of lobes in the multi-lobed cross-section is at least three, and at least two through holes are provided in the strip-shaped structure in the direction of its length, and the aspect ratio of the vanadium-based catalyst is in the range of 70-110; in formula (1) denotes the form factor; f denotes the correction factor; f=A / B, A=2.5∙10-4, B denotes the number of petals in a multi-petal cross-section; ρ denotes the bulk density of the vanadium-based catalyst, and the unit is kg / m3; ε denotes the aperture fraction of the vanadium-based catalyst; N denotes the number of specified through holes; d denotes the pore diameter of the through holes, and the unit of measurement is m; D denotes the outer diameter of the multi-lobed cross-section, and the unit is m.

2. The vanadium-based catalyst according to claim 1, wherein the shape factor of the vanadium-based catalyst is in the range of 80-100; and / or the SiO2 content is at least 90% by weight based on the total weight of the diatomite, and the weight ratio of Fe2O3 to Al2O3 is (0.02-0.1):1; preferably, the SiO2 content is 92-95% by weight based on the total weight of diatomite, and the weight ratio of Fe2O3 to Al2O3 is (0.03-0.08):1; Preferably, the support is included in an amount of 60-75 wt.%, more preferably 65-70 wt.%, based on the total weight of the vanadium-based catalyst.

3. A vanadium-based catalyst according to claim 1 or 2, wherein the ratio of the outer diameter D of the multi-lobed cross-section to the diameter d of the pores of the through holes is (3-7):1, preferably (4-6):1; and / or the ratio of the length L of the vanadium-based catalyst to the outer diameter D of the multi-lobed cross-section is (1-1.5):1, preferably (1-1.2):1; and / or the number of petals in the multi-petal cross-section is in the range of 3-8, preferably in the range of 5-6; and / or the number N of said through holes is in the range of 2-7, preferably in the range of 2-6; and / or through holes are cylindrical; and / or the diameter d of the pores of the through holes is in the range of 3-5 mm, preferably in the range of 3-4 mm; and / or the vanadium-based catalyst has a hole fraction in the range of 0.09-0.25, preferably in the range of 0.12-0.22; and / or the vanadium-based catalyst has a bulk density in the range of 400-550 kg / m3, preferably in the range of 450-500 kg / m3; and / or the vanadium-based catalyst has a strength greater than or equal to 70 N / cm, preferably in the range of 80-120 N / cm.

4. A vanadium-based catalyst according to any one of claims 1 to 3, wherein the weight ratio of the carrier to the active vanadium-based material is (60-75):(6-8.5), preferably (65-70):(6.5-8); and / or the vanadium-based catalyst further comprises a potassium-containing compound, preferably potassium sulfate, supported on a carrier; preferably, the molar ratio of the potassium element to the vanadium element in the vanadium-based catalyst is (2-4):1, more preferably (2.5-3.5):1; and / or the vanadium-based catalyst further comprises an auxiliary agent supported on a carrier; the weight ratio of said carrier to said auxiliary agent is (60-75):(3.5-10), preferably (65-70):(4-8); Preferably, the auxiliary agent is one or more substances selected from the group consisting of sodium sulfate, rubidium sulfate, cesium sulfate, lanthanum oxide, cerium oxide and praseodymium oxide.

5. A method for producing a vanadium-based catalyst according to any one of claims 1 to 4, comprising: mixing a vanadium-containing compound, which is vanadium pentoxide, with diatomite, extruding strips to form a strip-like structure with a multi-lobed cross-section, wherein the number of lobes in the multi-lobed cross-section is at least three, and in the strip-like structure at least two through holes are provided in the direction of its length; then carrying out a first calcination such that the shape factor of the vanadium-based catalyst is in the range of 70-110.

6. The method according to claim 5, wherein the step of mixing the vanadium-containing compound with diatomite comprises: (1) separating and purifying the diatomite raw material and the dispersing agent in a hydrocyclone separator, drying, and then carrying out secondary calcination to obtain processed diatomite; (2) carrying out a neutralization reaction of vanadium water obtained from potassium hydroxide and vanadium pentoxide with sulfuric acid to obtain a reaction product; mixing the reaction product with the treated diatomite and a possible auxiliary agent and a possible binder, and then stirring the mixture.

7. The method according to claim 6, wherein the hydrocyclone separator has a suspension feed pressure in the range of 0.2-1 MPa, preferably in the range of 0.3-0.8 MPa, and a separation size in the range of 0.3-1 μm, preferably in the range of 0.3-0.7 μm; and / or the second firing temperature is in the range of 350-500°C, preferably in the range of 350-450°C; the time is 1-2 hours, preferably 1.2-2 hours; and / or the diatomaceous starting material is melozira diatomite; and / or the SiO2 content in the treated diatomite is at least 90 wt.%, preferably in the range of 92-95 wt.%; the weight ratio of Fe2O3 to Al2O3 is (0.02-0.1):1, more preferably (0.03-0.08):1; and / or the dispersing agent is one or more substances selected from the group consisting of sodium hexametaphosphate, sodium tripolyphosphate and sodium pyrophosphate; preferably, the added amount of dispersing agent is 1-5 wt.% of diatomite; and / or the molar ratio of the potassium element to the vanadium element in vanadium water is (2-4):1, preferably (2.5-3.5):1; and / or the weight ratio of the treated diatomite to the auxiliary agent is (60-75):(3.5-10), preferably (65-70):(4-8); preferably the auxiliary agent is one or more substances selected from the group consisting of sodium sulfate, rubidium sulfate, cesium sulfate, lanthanum oxide, cerium oxide and praseodymium oxide; and / or the weight ratio of the treated diatomite to the binder is (60-75):(0.5-2.5), preferably (65-70):(1-2); preferably the binder is one or more selected from the group consisting of montmorillonite, attapulgite and methylcellulose.

8. The method according to any one of claims 5 to 7, wherein the weight ratio of said diatomite to said vanadium-containing compound is (60-75):(6-8.5), preferably (65-70):(6.5-8); and / or the temperature of the first calcination is in the range of 580-650°C, and the time is 1-2 hours; preferably, the first calcination is carried out in an atmosphere of superheated water vapor; more preferably, the temperature of the superheated water vapor is in the range of 120-150°C; and / or the form factor is in the range of 80-100; and / or the vanadium-based catalyst has a hole fraction in the range of 0.09-0.25, preferably in the range of 0.12-0.22; and / or the vanadium-based catalyst has a bulk density in the range of 400-550 kg / m3, preferably in the range of 450-500 kg / m3; and / or the ratio of the outer diameter D of the multi-lobed cross-section to the diameter d of the pores of the through holes is (3-7):1, preferably (4-6):1; and / or the number of petals in the multi-petal cross-section is in the range of 3-8, preferably in the range of 5-6; and / or the number N of said through holes is in the range of 2-7, preferably in the range of 2-6.

9. A method for producing sulfuric acid by a wet process, comprising: bringing the feed gas into contact with a vanadium-based catalyst according to any of claims 1-4 or a vanadium-based catalyst obtained by the method according to any of claims 5-8, under conditions of catalytic oxidation of SO2 to form SO3, then carrying out condensation, wherein the feed gas contains SO2, O2 and water.

10. The method according to claim 9, wherein the contacting is carried out in a fixed bed reactor and the loading factor of said vanadium-based catalyst is less than 700 l / (t∙day), preferably in the range of 500-600 l / (t∙day); and / or the feed gas has an SO2 content of 1 to 9 vol.%; and / or the feed gas is a waste acid decomposition gas or an acid gas; and / or the inlet temperature of said feed gas is in the range from 370 to 440°C.

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