A catalyst shaped body, a vanadium-phosphorus catalyst having the catalyst shaped body, and an application thereof

Abstract

The application discloses a catalyst shaped body, a vanadium-phosphorus catalyst with the catalyst shaped body and application of the catalyst shaped body, and the catalyst shaped body is a straight triangular prism cylinder, and the inside of the straight triangular prism cylinder is a straight triangular prism hollow structure; wherein, the outer side edges and the inner side edges of the straight triangular prism cylinder are respectively and independently a chamfer structure, the outer side surface of the straight triangular prism cylinder is a plane, a curved surface or a circular arc surface, and the inner side surface of the straight triangular prism cylinder is a plane. Compared with the existing catalyst shaped body scheme, the shaped body can more effectively reduce the catalyst bed pressure drop, improve the catalyst selectivity and maintain a lower abrasion possibility.

Description

Technical Field

[0001] This invention relates to catalyst molding bodies, and more particularly to a catalyst molding body, a vanadium-phosphorus catalyst having the catalyst molding body, and its applications. Background Technology

[0002] The structure and parameters of the catalyst prototyping body have a significant impact on catalytic reactions, for example, in the following aspects: (1) For strongly exothermic reactions (such as gas-phase selective oxidation of hydrocarbons), different catalyst prototyping bodies, especially the shape of the prototyping body, are of great significance to the heat distribution and stable operation of industrial plants; (2) For fixed-bed reactors, the prototyping parameters such as the shape of the catalyst prototyping body have a significant impact on the selectivity of catalyst activity and the pressure drop of the fixed-bed bed; (3) The inherent non-wear-resistant characteristics of non-wear-resistant materials (such as vanadium phosphorus oxide (VPO) materials) and the long-term stability requirements place certain requirements on the strength and wear resistance of the catalyst prototyping body.

[0003] Taking VPO molded bodies as an example, in the shape research of VPO molded bodies suitable for fixed-bed reactors, existing technologies have made many attempts. Early molded bodies used solid cylinders. With the attempts to reduce the pressure drop of VPO molded bodies in the bed, void-shaped irregular molded body schemes have been widely adopted: CN1061352A proposed a variety of void-shaped columnar or conical molded structures, such as hollow cylinders, cloverleaf shapes, star shapes, and spiral shapes, with an effective volume of 30-90%; CN1416367A proposed a hollow cylindrical structure, characterized by a height-to-continuous hole diameter ratio not exceeding 1.5 and a geometric surface area-to-geometric volume ratio of at least 2 mm². -1 The ratio of the geometric volume to the corresponding solid cylinder volume does not exceed 0.85.

[0004] However, existing catalyst profiles (especially VPO catalyst profiles) still suffer from problems such as low porosity, low lateral pressure strength, or poor wear resistance, which in turn lead to excessively high pressure drop in the catalyst bed and poor catalyst performance (e.g., selectivity, conversion, yield). Summary of the Invention

[0005] To overcome the problems existing in the prior art, the present invention provides a catalyst molding body, a vanadium-phosphorus catalyst having the catalyst molding body, and its application. Compared with existing catalyst molding body solutions (such as VPO catalyst molding bodies), it can more effectively reduce catalyst bed pressure drop, improve catalyst selectivity, and maintain a lower wear probability.

[0006] One of the objectives of this invention is to provide a catalyst molding body, which is a straight triangular prism-shaped cylinder with a hollow structure inside. The outer and inner edges of the straight triangular prism-shaped cylinder are each independently chamfered, the outer surface of the straight triangular prism-shaped cylinder is a plane, a curved surface or an arc surface, and the inner surface of the straight triangular prism-shaped cylinder is a plane.

[0007] In a preferred embodiment, the cross-section of the straight triangular prism-shaped cylinder is a triangular ring structure, which is composed of a triangular outer ring and a triangular inner ring, wherein each vertex of the triangular outer ring and the triangular inner ring is independently chamfered.

[0008] In a further preferred embodiment, the triangular outer ring includes three chamfered vertices I, which are connected in pairs by connecting lines I to form the triangular outer ring; and / or, the triangular inner ring includes three chamfered vertices II, which are connected in pairs by connecting lines II to form the triangular inner ring.

[0009] In a further preferred embodiment, the chamfered vertex I and chamfered vertex II at the same vertex of the triangular ring structure are concentric arcs with different diameters.

[0010] In a further preferred embodiment, the connecting line I is a straight line, a curve, or an arc, preferably a straight line or an arc, more preferably, the curve or arc is recessed toward the radial center of the triangular prism cylinder; and / or, the connecting line II is a straight line.

[0011] When the connecting line I is a straight line or an arc, it helps to reduce the difficulty of catalyst forming and the probability of wear. Preferably, when the connecting line I is an arc, the arc is externally tangent to the chamfered vertex I.

[0012] In a preferred embodiment, the three connecting lines I in the triangular outer ring are all the same in shape and size, for example, straight lines of equal length or arcs of equal arc length; and / or, the three connecting lines II in the triangular inner ring are straight lines of equal length.

[0013] Thus, the lines connecting the centers of the three chamfered vertices I form an equilateral triangle, and the lines connecting the centers of the three chamfered vertices II also form an equilateral triangle. The equilateral triangle has greater strength, which optimizes the lateral pressure strength of the molded body. Furthermore, due to its higher strength, this improves the porosity of the molded body compared to existing technologies.

[0014] In a preferred embodiment, the three chamfered vertices I are all arcs with a radius of R2, and the three chamfered vertices II are all arcs with a radius of R3, where R3 < R2.

[0015] In a further preferred embodiment, R3 / R2 = 0 to 0.8 (preferably not 0), preferably 0.2 to 0.6, for example 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 or 0.8.

[0016] In a preferred embodiment, the three circles containing the three chamfered vertices I are connected, tangent, or separated from each other in pairs.

[0017] In particular, the three circles containing the three chamfered vertices I are preferably externally tangent to each other in pairs. This is because the inventors have found through experimental research that the connection between the chamfered vertices I and the connecting line I is the most natural, has higher stability, and is less prone to wear.

[0018] In a further preferred embodiment, the three chamfered vertices I are inscribed in a circle with a radius of R1. Preferably, R1 = 2 to 6 mm, more preferably, R1 = 2 to 4 mm, for example, R1 = 2 mm, 3 mm, 4 mm, 5 mm or 6 mm.

[0019] The value of R1 can represent the size of the catalyst prototyping body to a certain extent. If R1 is too small, it can easily lead to a high bed pressure drop and high prototyping difficulty; if R1 is too large, the catalyst particle size will be large, the catalyst loading will be low, and the production capacity and overall reaction performance will be affected. In particular, when the prototyping body described in this invention is used for the gas-phase selective oxidation reaction of hydrocarbons, which is a strongly exothermic reaction, the reaction tube is usually relatively thin. If the catalyst prototyping body particles are large, it will lead to uneven loading, resulting in unstable gas flow, decreased reaction performance and poor controllability.

[0020] In a further preferred embodiment, the height of the straight triangular prism-shaped cylinder is h, wherein 1≤h / R1≤3, preferably 1.5≤h / R1≤2.5, for example, h / R1=1, 1.5, 2, 2.5 or 3.

[0021] If h / R1 is too large or too small, it will cause problems with the uniformity of catalyst loading, resulting in phenomena such as bridging, which may lead to catalyst deactivation or affect the catalytic effect.

[0022] In this invention, the catalyst molded body has the following structural features:

[0023] Feature 1) The molded body is a columnar structure with a hollow structure (through hole), and the cross-section of its vertical height maintains the same shape.

[0024] Feature 2) The cross-section of the outer side of the molded body is a closed shape. This shape has a structure similar to an equilateral triangle. The three vertices are each formed by a partial arc of a circle with a radius of R2. The three arcs are inscribed in a circle with a radius of R1 and are connected by three identical connecting lines I to form a closed shape.

[0025] Feature 3) The cross-section of the inner side of the molded body has the same structural characteristics as the cross-section of the outer side of the molded body in Feature 2). The cross-section of the inner side of the molded body has a similar equilateral triangle structure (equilateral triangles have better strength and can optimize the lateral pressure strength of the molded body). The three vertices are formed by a portion of the arc of three circles with a radius of R3. The three arc segments are connected by three connecting lines II to form a closed shape. The hollow structure (through hole) should be located within this closed shape and the entire cross-section should maintain a symmetrical structure.

[0026] Feature 4) The column height h of the molded body has a proportional relationship of 1≤h / R1≤3 with respect to the radius R1 in Feature 2).

[0027] Through experiments, the inventors found that if the inner cross-section of the catalyst in feature 3 is a circular structure, (1) the inconsistent wall thickness of the cylindrical shape leads to uneven strength and reduced lateral pressure strength; (2) when the molded body has the same porosity as the molded body described in this invention, this invention found that the lateral pressure strength of the molded body is significantly lower (lower than that of this invention), which easily causes the molded body to break; (3) if the lateral pressure strength of the molded body is first guaranteed to meet the requirements, then its porosity is lower (which can be understood as when the lateral pressure strength of the molded body is comparable to that of this invention, its porosity is significantly lower than that of this invention), and the bed pressure drop is higher.

[0028] In a preferred embodiment, the volume ratio of the hollow catalyst body having the straight triangular prism structure to its corresponding solid catalyst body is 40% to 85%, preferably 50% to 70%, for example 40%, 50%, 60%, 70%, 80% or 85%.

[0029] The corresponding solid catalyst molding body refers to a solid catalyst molding body with a cross-section resembling a triangular outer ring, that is, the hollow triangular prism-shaped structure of the catalyst molding body with the straight triangular prism-shaped hollow structure is filled. Compared with common hollow cylindrical catalysts, under similar dimensions and equal lateral pressure strength, the volume ratio range of the VPO molding body described in this invention is significantly smaller than that of a hollow cylinder, that is, it has a larger porosity, which is beneficial for producing a lower catalyst bed pressure drop and better diffusion characteristics.

[0030] In this invention, the bulk density of the catalyst molding body can be adjusted by adjusting the molding parameters as needed, typically 0.4 to 1.2 g / ml, preferably 0.5 to 0.9 g / ml, for example 0.4 g / ml, 0.6 g / ml, 0.8 g / ml, 1 g / ml or 1.2 g / ml.

[0031] In a preferred embodiment, the lateral compressive strength of the catalyst molding body is typically 5 to 100 N, preferably 10 to 60 N, for example 10 N, 12 N, 15 N, 18 N, 20 N, 25 N, 30 N, 40 N, 60 N, 80 N, or 100 N.

[0032] Insufficient lateral compressive strength can lead to strength problems, causing catalyst cracking during loading, transportation, and use, thus affecting catalyst performance. Conversely, higher lateral compressive strength indicates potentially higher catalyst density and lower porosity, which may affect catalyst performance due to diffusion issues during use. This invention can guarantee the required lateral compressive strength while improving porosity.

[0033] The existing technology presents a problem: if the required lateral pressure strength is guaranteed, the porosity will be lower; if a higher porosity is guaranteed, the lateral pressure strength may not be guaranteed. Therefore, the existing technology cannot currently achieve a way to increase the porosity while ensuring the lateral pressure strength. The catalyst described in this invention has a higher porosity compared to conventional molded bodies, and due to its good structural stability, the lateral pressure strength can meet the requirements and be guaranteed.

[0034] In a preferred embodiment, the catalyst molded body has a uniform wall thickness. This ensures consistent lateral compressive strength throughout the catalyst molded body, resulting in greater stability.

[0035] The catalyst prototyping described above can be prepared by tableting or extrusion. Preferably, the prototyping is more suitable for tableting. As is well known to those skilled in the art, the prototyping can be prepared by tableting using a single-punch or rotary tableting machine, with a corresponding mold installed in the cavity.

[0036] A second objective of this invention is to provide the application of the catalyst molding body described in one objective of this invention in the molding of catalysts for exothermic or strongly exothermic reactions, such as the application in the molding of catalysts for the gas-phase selective oxidation of hydrocarbons, specifically in the molding of vanadium phosphorus oxide (VPO) catalysts.

[0037] Gas-phase selective oxidation of hydrocarbons is an important class of catalytic oxidation reactions, one of the typical products of which is maleic anhydride. Maleic anhydride (MA) is a commonly used and important organic chemical raw material, and the third most consumed anhydride in the world. The earliest production method of maleic anhydride used benzene as a raw material, but due to environmental hazards and economic factors, the current mainstream production method uses n-butane as a raw material, employing different process routes including fixed-bed, fluidized-bed, and moving-bed processes. These processes each have their own characteristics, but generally, they all use the same type of vanadium-phosphorus oxide catalyst.

[0038] A third objective of this invention is to provide a vanadium phosphorus oxide (VPO) catalyst molded body having the shape of the molded body described in one objective of this invention.

[0039] Vanadium-containing oxides are often used as catalysts for selective oxidation reactions due to their excellent catalytic properties in redox reactions. Among them, vanadium phosphorus oxide (VPO) catalysts are the most effective catalysts to date for the selective oxidation of gas-phase hydrocarbons, especially the oxidation of n-butane to maleic anhydride. The preparation of VPO catalysts used in industry typically involves the following main steps: 1) obtaining VPO precursor powder through liquid-phase reaction and heat treatment; 2) forming VPO preforms of fixed shapes by molding methods such as tableting, extrusion, or spraying; 3) obtaining activated VPO preform catalysts by high-temperature calcination. VPO precursors can be obtained by aqueous or organic solvent methods. Early processes typically used pentavalent vanadium oxides, such as vanadium pentoxide (V₂O₅), in the presence of water and HCl, while the more mainstream method currently is the organic method. A common organic method involves the reflux reaction of pentavalent vanadium oxides and phosphoric acid in an organic solvent (such as primary alcohols) to obtain the precursor.

[0040] In a preferred embodiment, the components in the vanadium phosphate oxide (VPO) catalyst molded body include vanadium phosphate oxide (VPO) precursor powder.

[0041] In a further preferred embodiment, the vanadium-phosphorus-oxygen precursor powder is the main component of the catalyst, and its molecular formula can be expressed as general formula VP. x M y O z The expression is given, where M represents one or more co-catalytic element components. x ranges from 0.85 to 2, y ranges from 0 to 0.5, and z is the stoichiometric number satisfying the oxide molecular combination. A typical synthetic method is described in CN105413725A.

[0042] In a further preferred embodiment, before tableting, the vanadium phosphorus oxygen precursor powder is heat-treated at a temperature in the range of 110 to 300°C to make the powder properties more suitable for tableting.

[0043] In a preferred embodiment, the components in the vanadium phosphorus oxide (VPO) catalyst molded body further include a support and a molding aid.

[0044] In a further preferred embodiment, the support can be an oxide, a composite oxide, a molecular sieve, or a mixture thereof. When using a support, it is necessary to ensure that the distribution of the support and the active component is uniform to guarantee the homogeneity of the molded body. Due to the special properties of VPO catalysts, the molded body can also be prepared without the addition of a support.

[0045] In a further preferred embodiment, the molding aid includes lubricants, binders, pore-forming agents, etc. Adding a small amount facilitates the smooth production of the molded article and achieves the aforementioned characteristic requirements; the basic principle is well known to those skilled in the art. Common molding aids include graphite, stearic acid, starch, etc., and their addition amount is typically controlled to be 1-10% of the total mass by weight.

[0046] Before being used in selective oxidation reactions of hydrocarbons, the aforementioned VPO catalyst prototyping typically requires calcination activation. A typical activation method involves heating the prototyping to 380–550°C in an atmosphere containing one or more gases, including air, oxygen, inert gases such as nitrogen or argon, carbon oxides, water vapor, low-carbon hydrocarbons, and organophosphorus volatiles, to obtain a catalyst with ideal performance. The prototyping prepared using this invention is suitable for such typical activation methods and requires no special treatment.

[0047] The VPO catalyst profile prepared by the method described in this invention, after activation, is suitable for gas-phase selective oxidation of hydrocarbons, and is particularly suitable for use as a catalyst for the gas-phase oxidation of n-butane to maleic anhydride in a fixed-bed reactor.

[0048] Because the catalyst molding body has a high porosity, the bed pressure drop can be significantly reduced, preventing local overheating and facilitating the conduction of strongly exothermic reactions (selective oxidation of hydrocarbons).

[0049] The fourth objective of this invention is to provide the application of the vanadium phosphorus oxide (VPO) catalyst profile described in the third objective of this invention in the gas-phase selective oxidation reaction of hydrocarbons, especially in the gas-phase oxidation of n-butane to maleic anhydride in a fixed-bed reactor.

[0050] The vanadium phosphorus oxide (VPO) catalyst profile effectively reduces catalyst bed pressure drop and improves catalyst selectivity, while controlling the conversion rate within a reasonable range and increasing the overall yield. It can be used for the catalytic gas-phase oxidation of hydrocarbons to produce maleic anhydride.

[0051] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) The catalyst molding body has a high porosity, which can significantly reduce the bed pressure drop, prevent local overheating, and facilitate the strong exothermic reaction.

[0054] (2) The catalyst molding body can be used in vanadium phosphorus oxide (VPO) catalyst, which can effectively reduce the pressure drop of the catalyst bed and improve the catalyst selectivity. It can be used to catalyze the gas-phase oxidation of hydrocarbons to produce maleic anhydride. Attached Figure Description

[0055] Figure 1 The cross-section of the catalyst molded body described in Example 1 is shown, wherein the solid black lines represent the specific structure, and the dashed lines and shaded areas are used to illustrate its structural features.

[0056] exist Figure 1 In the diagram, 1-outer ring of a type of triangle, 11-beveled vertex I, 12-connecting line I, 2-inner ring of a type of triangle, 21-beveled vertex II, 22-connecting line II. Figure 1 In the diagram, R1 represents the radius of the circle tangent to the three chamfered vertices I, R2 represents the radius of the circle containing chamfered vertex I, and R3 represents the radius of the circle containing chamfered vertex II.

[0057] Figure 2 The cross-section of the catalyst molded body described in Example 3 is shown, where the solid black lines represent the specific structure, and the dashed lines and shaded areas are used to illustrate its structural characteristics. Figure 2 In the diagram, R1 represents the radius of the circle tangent to the three chamfered vertices I, R2 represents the radius of the circle containing chamfered vertex I, and R3 represents the radius of the circle containing chamfered vertex II.

[0058] Figure 3A cross-section of the catalyst molded body described in Comparative Example 1 is shown. Figure 1 In this diagram, R1 represents the radius of the circle containing the outer surface of the cylindrical shape, and R2 represents the radius of the circle containing the inner surface of the cylindrical shape. Detailed Implementation

[0059] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0060] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0061] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0062] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0063] Precursor preparation: 35.9 g of concentrated phosphoric acid (105% H3PO4) was slowly added to 15 g of isobutanol and mixed. The mixture was heated to 100 °C for 30 min with stirring, and then the solution was sealed and cooled. 25 g of vanadium pentoxide was added to a mixed solution of 200 ml isobutanol and 50 ml benzyl alcohol. The mixture was heated with stirring, and the previously prepared phosphoric acid solution was added dropwise to the mixed solution. After the addition was completed, the mixed solution was heated to reflux. After reflux for 12 h, the mixture was cooled and filtered, and washed with isobutanol. The resulting filter cake was dried under vacuum at 120 °C for 20 h to obtain the precursor.

[0064] Evaluation method for activated VPO catalyst: The catalyst profile was placed in a fixed-bed reactor with a reaction tube diameter of Φ21 mm. The feedstock was a mixture of n-butane and air with a molar concentration of 1.5%, and maleic anhydride was produced through a gas-phase catalytic reaction. Reaction conditions: space velocity of 1800 hr. -1 The reaction temperature was 420℃, and the reaction pressure was atmospheric pressure. The above evaluation methods are only used to evaluate and compare the performance of the catalyst and do not limit the applicable reaction conditions for the catalyst described in this invention.

[0065]

Example 1

[0066] The aforementioned precursor was heated to 260°C in air and held at that temperature for 6 hours. After cooling, 4% graphite additive was added, and the powder was pressed into tablets. Subsequently, the tablets were slowly calcined in a mixed gas of air / nitrogen / carbon dioxide / water vapor to 430°C for 6 hours to obtain an active VPO catalyst. The structure of the tablets is as follows: Figure 1 As shown, the specific parameters are shown in Table 1.

[0067] The prepared activated VPO catalyst was evaluated using the above evaluation method, and the results are shown in Table 1.

[0068]

Example 2

[0069] Repeat the process of Example 1, except that the structure of the molded body is as follows: Figure 2 As shown, the specific parameters are shown in Table 1.

[0070] The prepared activated VPO catalyst was evaluated using the above evaluation method, and the results are shown in Table 1.

[0071]

Example 3

[0072] The process of Example 1 was repeated, except that the parameters of the molded body were different (see Table 1), and the evaluation results are shown in Table 1.

[0073]

Example 4

[0074] The process of Example 1 was repeated, except that the parameters of the molded body were different (see Table 1), and the evaluation results are shown in Table 1.

[0075]

Example 5

[0076] The process of Example 2 was repeated, except that the parameters of the molded body were different (see Table 1), and the evaluation results are shown in Table 1.

[0077] Comparative Example 1

[0078] The process of Example 1 is repeated, except that the structure of the molded body is a hollow cylinder (e.g. Figure 3 (As shown in the figure), the specific parameters are shown in Table 1.

[0079] Table 1:

[0080]

[0081] As can be seen from the table above, the porosity of the forming agent in Examples 1 and 2 of this invention is significantly greater than that in Comparative Example 1 (and the porosity is increased while ensuring the lateral pressure strength). This significantly reduces the bed pressure drop and prevents localized overheating. Table 1 also clearly shows that the bed hot spots in Examples 1 and 2 are significantly lower than those in Comparative Example 1. Furthermore, Comparative Example 1 has a larger loading volume (because the hollow cylindrical catalyst in Comparative Example 1 has a low porosity, resulting in a relatively larger actual catalyst loading volume per unit volume, thus leading to a larger overall loading mass).

[0082] As can be seen from the table above, the catalyst prepared in the embodiments of the present invention can improve selectivity and increase actual yield, effectively improving catalyst performance.

[0083] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A catalyst profile for use in the gas-phase selective oxidation of hydrocarbons, comprising a straight triangular prism-shaped cylinder, wherein the interior of the straight triangular prism-shaped cylinder has a hollow structure in the form of a straight triangular prism; wherein, The outer and inner edges of the right triangular prism-shaped cylinder are each independently chamfered. The outer surface of the right triangular prism-shaped cylinder is flat, and the inner surface of the right triangular prism-shaped cylinder is flat. The cross-section of the right triangular prism-shaped cylinder is a triangular ring-like structure, which is composed of a triangular outer ring and a triangular inner ring. The triangular outer ring includes three chamfered vertices I, which are connected in pairs by connecting lines I, which are straight lines. The triangular inner ring includes three chamfered vertices II. Vertices II are connected in pairs by connecting line II to form the inner ring of the triangular ring structure, where connecting line II is a straight line; the chamfered vertices I and II at the same vertex of the triangular ring structure are concentric arcs with different diameters; the three circles containing the three chamfered vertices I are externally tangent to each other in pairs; the three chamfered vertices I are internally tangent to a circle with radius R1, where R1 = 2~6mm; the height of the right triangular prism cylinder is h, where 1≤h / R1≤3; the three chamfered vertices I are all arcs with radius R2, and the three chamfered vertices II are all arcs with radius R3.

2. The catalyst molded body according to claim 1, characterized in that, The three connecting lines I in the triangular outer ring are all the same in shape and size.

3. The catalyst molded body according to claim 1, characterized in that, R3 / R2 = 0.2~0.

8.

4. The catalyst molded body according to claim 1, characterized in that, R3 / R2 = 0.2~0.

6.

5. The catalyst molded body according to claim 1, characterized in that, R1 = 2~4mm.

6. The catalyst molded body according to claim 1, characterized in that, 1.5≤h / R1≤2.

5.

7. The catalyst molded body according to any one of claims 1 to 6, characterized in that, The volume ratio of the catalyst molding body having the straight triangular prism hollow structure to its corresponding solid catalyst molding body is 40%~85%; and / or, The lateral compressive strength of the catalyst molded body is 5~100N.

8. The catalyst molded body according to claim 7, characterized in that, The volume ratio of the catalyst molding body having the straight triangular prism hollow structure to its corresponding solid catalyst molding body is 50%~70%; and / or, The lateral compressive strength of the catalyst molded body is 10~60N.

9. The application of the catalyst molding body according to any one of claims 1 to 8 in the molding of catalysts for gas-phase selective oxidation reactions of hydrocarbons.

10. The application according to claim 9, in the forming of vanadium phosphorus oxygen catalyst.

11. A vanadium-phosphorus-oxygen catalyst molded body having the shape of the molded body according to any one of claims 1 to 8.

12. The vanadium-phosphorus-oxygen catalyst molded body according to claim 11, characterized in that, The components in the vanadium phosphorus oxygen catalyst molded body include vanadium phosphorus oxygen precursor powder.

13. The vanadium-phosphorus-oxygen catalyst molded body according to claim 12, characterized in that, The molecular formula of the vanadium phosphorus oxygen precursor powder is given by the general formula VP. x M y O z The expression is given by M, where M represents one or more co-catalytic element components, x ranges from 0.85 to 2, y ranges from 0 to 0.5, and z is the stoichiometric number of the oxide molecular combination.

14. The vanadium-phosphorus-oxygen catalyst molded body according to claim 12, characterized in that, The components in the vanadium phosphorus oxygen catalyst molded body further include a support and a molding aid.

15. The application of the vanadium-phosphorus-oxygen catalyst profile according to any one of claims 11 to 14 in the gas-phase selective oxidation reaction of hydrocarbons.

16. The application according to claim 15, in the gas-phase oxidation of n-butane to maleic anhydride in a fixed-bed reactor.

Images