A VPO catalyst and its application in the oxidation of n-butane to maleic anhydride

Abstract

The application discloses a VPO catalyst and application thereof in oxidation of n-butane to prepare dicanhydride. The method comprises the following steps: dissolving a mineralizer A and a template B in water, stirring and mixing, adding alcohol and vanadium in an oxidized state, heating and refluxing, adding phosphoric acid to continue the reaction, adding a silicon source, washing and drying the obtained solid, and calcining to remove the template to obtain a precursor; adding the precursor into small-molecule alcohol and water, and obtaining catalyst particles through pressing, demolding, drying, crushing and screening. The process method adopted by the application can realize protection of the VPO catalyst, reduce abrasion and activity reduction caused by catalyst coking, ensure accessibility of active centers through linear pores, ensure stable operation of the catalyst, and prolong the service life of the VPO catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysis technology, in particular to a VPO catalyst and its application in the oxidation of n-butane to maleic anhydride. BACKGROUND

[0002] Maleic anhydride, also known as maleic acid anhydride, is one of the three major organic anhydrides in the chemical industry, second only to phthalic anhydride and acetic anhydride, and is a very important organic chemical raw material, which has a wide application market in the petroleum industry, pharmaceutical intermediates, food processing and construction industries. In recent years, with the development of natural gas in China, the natural gas transportation facilities are more convenient, and natural gas has become the mainstream fuel gas, which has prompted n-butane to lose its main market, and the price of n-butane has dropped sharply. N-butane has the advantages of low price, relatively light pollution, and better atomic economy, which makes the oxidation of n-butane to maleic anhydride have better economic benefits. Compared with the past benzene method for preparing maleic anhydride, the device for preparing maleic anhydride by butane oxidation method has gradually increased in capacity and become the mainstream of the chemical industry.

[0003] Among the catalysts for the oxidation of n-butane to maleic anhydride, vanadium-phosphorus oxide (VPO) catalyst is proved to be the most effective catalyst for the oxidation of n-butane to maleic anhydride. Among the many preparation methods, the preparation of VPO catalyst by organic solvent is a simple method for preparing VPO catalyst for maleic anhydride. The organic solvent method synthesizes vanadium oxide compounds, phosphorus compounds and promoters in selected organic solvents such as esters, alcohols and aldehydes. After a period of reaction, a catalyst precursor containing VPO is generated. Then, after solid-liquid separation, washing, drying, calcination, and then pressing into a specific external shape of particles, the desired VPO catalyst is obtained. Before the butane oxidation reaction, the catalyst can be activated by gas to achieve the best catalytic effect.

[0004] Although VPO catalyst has been industrialized for many years and has been continuously improved, commercial VPO catalyst still has many by-products, which leads to serious coking phenomenon, catalyst damage and other problems, resulting in shortening of the service life of the catalyst. Therefore, research on extending the service life of VPO catalyst has been ongoing. SUMMARY

[0005] In view of the problems in the prior art, it is necessary to reduce catalyst wear and tear, reduce by-products, solve the problem of phosphorus loss during the use of VPO catalyst, which leads to the decline of catalytic performance and the increase of by-products, so as to prolong the service life of the catalyst during use. One of the purposes of the present application is to provide a VPO catalyst, which can obtain a longer catalytic life when used in the oxidation of n-butane to maleic anhydride. First, a VPO spherical catalyst with linear channels is prepared, as shown in FIG. 1. The VPO catalyst is prepared by the organic solvent method. The VPO catalyst is prepared by the following steps: (1) preparing a vanadium-phosphorus precursor; (2) preparing a VPO catalyst precursor; (3) preparing a VPO catalyst; (4) preparing a VPO catalyst with linear channels. Figure 1The preparation process is shown in the figure. In the preparation process, through the special combination of the mineralizing agent and the template agent, the template agent B will form a ball around the hydrophobic end due to the existence of the hydrophilic end and the hydrophobic end of the structure, and under the conditions of a certain temperature and humidity and a weak alkaline environment, the multiple hydrogen bond effects of the mineralizing agent make the template agent microspheres form long chains, and the silanization ability of the silicon source reagent enables it to realize the coating of the long chains into balls, and the subsequent long-chain organic molecules leave linear pores after high-temperature calcination, and the remaining part forms a spherical catalyst containing VPO active sites.

[0006] The linear pores can ensure that the subsequent VPO catalyst has sufficient specific surface area and accessible active sites after being loaded, ensure the catalytic activity of the catalyst, reduce the generation of by-products, and under the protection of silicon, greatly enhance the mechanical strength and wear resistance of the VPO catalyst, and also reduce the phosphorus loss rate of the VPO catalyst, so that the VPO catalyst has a longer service life.

[0007] The process method provided by the application has simple catalyst preparation, stable performance, high strength, long service life, simple preparation method, low cost, and is beneficial to large-scale industrial application.

[0008] To achieve the above application purposes, the specific technical solutions are as follows:

[0009] A preparation method of a spherical VPO catalyst with linear pores, the method comprising the following steps:

[0010] S1: Dissolve the mineralizing agent A and the template agent B in water, stir and mix, add alcohol and vanadium in the oxidation state, heat and reflux, add phosphoric acid for continuous reaction, then add a silicon source, wash and dry the obtained solid, and calcine to remove the template to obtain a precursor;

[0011] S2: Add the precursor to small-molecule alcohol and water, and through pressing, demolding, drying, crushing and sieving, catalyst particles are obtained.

[0012] In an embodiment of the application, the mineralizing agent A in S1 is a compound with multiple hydrogen bond effects on both sides of the molecular structure along the axis, preferably one or more of 2-amino-2-hydroxymethyl-1,3-propanediol, 3-amino phenol, 4-amino-5-methyl pyridine-2-alcohol, 6-amino-2-hydroxymethyl-n-1-hexanol, 6-amino-2-hydroxymethyl-n-hexane-1-alcohol, tromethamine, 4-dimethylamino-1-butanol, 2-hydroxymethyl amino ethanol, (S)-2-Boc-amino-1,4-butanediol.

[0013] In an embodiment of the present application, the template agent B in S1 is an organic ammonium salt, preferably one or more of tetraethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, cetyltrimethylammonium p-toluenesulfonate, octadecyltrimethylammonium chloride; preferably, the molar ratio of mineralizing agent A: template agent B = 1: (0.1-120); preferably, the molar ratio of template agent B: silicon source: water = 1: (1-100): (100-10000).

[0014] In an embodiment of the present application, the alcohol in S1 is a C1-C12 small molecule alcohol, preferably one or more of methanol, benzyl alcohol, ethanol, isobutyl alcohol, n-hexanol.

[0015] In an embodiment of the present application, the vanadium in oxidation state in S1 is a vanadium oxide compound, preferably one or more of vanadium dioxide, divanadium trioxide, divanadium pentoxide; preferably, the molar ratio of phosphorus element to vanadium element = 1: (0.1-100).

[0016] In an embodiment of the present application, the silicon source in S1 is a silicon compound, preferably one or more of neutral silica sol, fumed silica, white carbon black, tetraethyl orthosilicate, silicic acid, trimethylsilicic acid ester, silicon tetracetate; preferably, the molar ratio of vanadium element: alcohol: silicon element in S1 = 1: (0.1-100): (0.1-100).

[0017] In an embodiment of the present application, the stirring mixing in S1 is under constant temperature and humidity conditions; preferably, the temperature is 10-80℃, the humidity is 5-80%, and the time is 0.5-12h.

[0018] In an embodiment of the present application, the heating reflux temperature in S1 is 50-100℃, and the reflux time is 1-24h.

[0019] In an embodiment of the present application, the calcination temperature in S1 is 400-900℃, and the time is 2-10h.

[0020] In an embodiment of the present application, the VPO catalyst obtained in S1 is microscopically spherical with linear channels.

[0021] In an embodiment of the present application, the C1-C12 small molecule alcohol is added in S2, preferably one or more of methanol, ethanol, n-propanol, n-butanol, ethylene glycol, 1,4-butanediol, n-hexanol, lauryl alcohol; preferably, the mass ratio of alcohol to water is 1: (0.1-100); preferably, the total mass of alcohol and water accounts for 1-100% of the mass of the precursor.

[0022] In one embodiment of the present application, the particle size screened in S2 is 20-60 mesh.

[0023] Another object of the present application is to provide a spherical VPO catalyst with linear channels.

[0024] A spherical VPO catalyst with linear channels is prepared by the method described above, and the catalyst is microscopically spherical with linear channels.

[0025] Still another object of the present application is to provide a process for prolonging the service life of a VPO catalyst for the oxidation of n-butane to maleic anhydride.

[0026] A process for prolonging the service life of a VPO catalyst for the oxidation of n-butane to maleic anhydride, which uses the catalyst prepared by the method described above, or uses the catalyst described above, and the catalyst used in the process is microscopically spherical with linear channels.

[0027] In one specific embodiment of the present application, the oxidation of butane to maleic anhydride is carried out in a fixed bed reactor: the shaped VPO catalyst is loaded into a tubular reactor, butane mixed gas is introduced into the tubular reactor for catalyst activation, the gas is warmed for preheating, then the preheated mixed gas is introduced into the tubular reactor, after activation, the reaction temperature is raised, sampling of the reaction is started, the tail gas is connected to an online TCD detector for analysis of the results at different time points, thereby producing maleic anhydride products.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] (1) The VPO catalyst prepared by the present application has linear channels, compared with ordinary supported VPO catalysts, the active centers of the VPO catalyst prepared by the present application can be uniformly dispersed in the linear channels, the distribution is uniform, the transfer conversion rate is very good, and the catalytic performance of the catalyst is ensured.

[0030] (2) The VPO catalyst prepared by the present application is protected by silicon, which greatly reduces the wear and loss of phosphorus during use, can maintain high conversion in long-term operation, and greatly prolongs the service life of the catalyst.

[0031] (3) The process pipeline modification scheme designed by the present application is simple, requires small space, and can be implemented in industry. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a schematic diagram of the preparation of a VPO spherical catalyst with linear channels;

[0033] Figure 2SEM picture of VPO catalyst with linear channels prepared in the present invention;

[0034] Figure 3 TEM picture of VPO catalyst with linear channels prepared in the present invention. DETAILED DESCRIPTION

[0035] The present invention is further illustrated by the following examples, but the present invention is not limited to these examples.

[0036] Raw material information: 2-amino-2-hydroxymethyl-1,3-propanediol, ARK, 98%; cetyltrimethylammonium p-toluenesulfonate, 98%; vanadium pentoxide, 99.5%; benzyl alcohol, 99%; isobutyl alcohol, 99.5% chromatographic purity; tetraethyl orthosilicate, 99%; ethanol, 99.7% AR; phosphoric acid, 85% aqueous solution; 3-aminophenol, 99%; cetyltrimethylammonium bromide, 99%; cetyltrimethylammonium chloride, 99%; vanadium dioxide, 99%; tromethamine, 99.8%; methanol, 99.5%, n-hexanol, 99%, tetrapropylammonium hydroxide, 25% aqueous solution; tetraethylammonium hydroxide, 25% aqueous solution; silicic acid, 99.9%; 4-dimethyl-1-butanol, 99%; 2-hydroxy-aminoethanol, 99%. Beijing Innochem.

[0037] Analytical characterization: scanning electron microscope (SEM), model JEOL JSM-7800F; transmission electron microscope (TEM), model JEOL JEM-2100.

[0038] Example 1

[0039] First, 0.01 g of 2-amino-2-hydroxymethyl-l,3-propanediol and 4 g of cetyltrimethylammonium p-toluenesulfonate were dissolved in 500 mL of deionized water, and stirred for 0.5 h under the conditions of 20% humidity and 50°C. 18.1 g of V2O5 and 5.4 g of benzyl alcohol, 7.4 g of isobutyl alcohol, and 40 g of tetraethyl orthosilicate reagent were heated to 80°C and refluxed for 24 h, and then 19.6 g of phosphoric acid was added and reacted for 2 h. The resulting solid was suction filtered and washed with deionized water, and the remaining template was washed thoroughly. Then, drying was performed in an oven at 80°C for 12 h, and the dried sample was ground to obtain a powder with the template. Then, the obtained powder was placed in a muffle furnace and calcined at 500°C for 5 h to remove the hard template, thereby obtaining a spherical VPO catalyst having linear pores. 5 g of the catalyst precursor and 0.5 g of deionized water and 0.5 g of anhydrous ethanol were mixed uniformly by stirring, and the mixture was filled into a cylindrical mold and pressed for 10 min at 0.3 MPa to form a shape, and then dried in an oven at 100°C for 24 h after demolding. The VPO catalyst having linear pores was sieved to have a size of 20-60 mesh.

[0040] Example 2

[0041] First, 0.01 g of 2-amino-2-hydroxymethyl-l,3-propanediol and 4 g of cetyltrimethylammonium p-toluenesulfonate were dissolved in 500 mL of deionized water, and stirred for 0.5 h under the conditions of 20% humidity and 50°C. 18.1 g of V2O5 and 5.4 g of benzyl alcohol, 7.4 g of isobutyl alcohol, and 40 g of tetraethyl orthosilicate reagent were heated to 80°C and refluxed for 24 h, and then 19.6 g of phosphoric acid was added and reacted for 2 h. The resulting solid was suction filtered and washed with deionized water, and the remaining template was washed thoroughly. Then, drying was performed in an oven at 80°C for 12 h, and the dried sample was ground to obtain a powder with the template. Then, the obtained powder was placed in a muffle furnace and calcined at 500°C for 5 h to remove the hard template, thereby obtaining a spherical VPO catalyst having linear pores. 5 g of the catalyst precursor and 0.5 g of deionized water and 0.5 g of anhydrous ethanol were mixed uniformly by stirring, and the mixture was filled into a cylindrical mold and pressed for 10 min at 0.3 MPa to form a shape, and then dried in an oven at 100°C for 24 h after demolding. The VPO catalyst having linear pores was sieved to have a size of 20-60 mesh.

[0042] Example 3

[0043] First, 4.84 g tromethamine and 1.46 g cetyltrimethylammonium bromide were dissolved in 700 mL of deionized water, and stirred for 1 h at 80% humidity and 70°C. 1 g of V2O5 and 1.6 g of methanol, 18 g of n-hexanol, and 20 g of fumed silica were added, heated to 80°C and refluxed for 5 h, and 5 g of phosphoric acid was added and reacted for 2 h. The resulting solid was washed by suction filtration, and the remaining templates were washed thoroughly. The sample was then dried in an oven at 105°C for 12 h, and the dried sample was ground to obtain a powder with templates. The obtained powder was then calcined in a muffle furnace at 900°C for 2 h to remove the hard templates, and a spherical VPO catalyst having linear pores was obtained. 5 g of the catalyst precursor, 0.4 g of deionized water, and 4 g of anhydrous ethanol were mixed, and the mixture was filled into a cylindrical mold, and pressed at 0.3 MPa for 10 min to form a shape. After demolding, the sample was dried in an oven at 105°C for 24 h, and was crushed and sieved to obtain a VPO catalyst having linear pores with a size of 20-60 mesh.

[0044] Example 4

[0045] First, 0.01 g of 2-amino-2-hydroxymethyl-1,3-propanediol and 0.8 g of a tetrapropylammonium hydroxide aqueous solution were dissolved in 100 mL of deionized water, and stirred for 2.5 h at 30% humidity and 65°C. 0.83 g of VO2 and 2.24 g of methanol, 2.22 g of isobutanol, and 7.6 g of silica reagent were added, heated to 70°C and refluxed for 6 h, and 0.01 g of phosphoric acid was added and reacted for 2 h. The resulting solid was washed by suction filtration, and the remaining templates were washed thoroughly. The sample was then dried in an oven at 80°C for 12 h, and the dried sample was ground to obtain a powder with templates. The obtained powder was then calcined in a muffle furnace at 650°C for 5 h to remove the hard templates, and a spherical VPO catalyst having linear pores was obtained. 5 g of the catalyst precursor, 4 g of deionized water, and 0.04 g of anhydrous ethanol were mixed, and the mixture was filled into a cylindrical mold, and pressed at 0.3 MPa for 10 min to form a shape. After demolding, the sample was dried in an oven at 100°C for 24 h, and was crushed and sieved to obtain a VPO catalyst having linear pores with a size of 20-60 mesh.

[0046] Example 5

[0047] First, 0.01 g of 2-amino-2-hydroxymethyl-l,3-propanediol and 4 g of cetyltrimethylammonium p-toluenesulfonate were dissolved in 300 mL of deionized water, and stirred for 0.4 h under the conditions of 90% humidity and 100°C. 18.1 g of V2O5 and 5.4 g of benzyl alcohol, 7.4 g of isobutyl alcohol, and 40 g of tetraethyl orthosilicate reagent were heated to 75°C and refluxed for 2 h, and then 19.6 g of phosphoric acid was added and reacted for 2 h. The resulting solid was suction-filtered and washed with deionized water, and the remaining template was thoroughly washed. Subsequently, drying was performed in an oven at 80°C for 12 h, and the dried sample was ground to obtain a powder with the template. Subsequently, the obtained powder was placed in a muffle furnace, and calcined at 500°C for 2.5 h to remove the hard template, thereby obtaining a spherical VPO catalyst having linear pores. 5 g of the catalyst precursor and 0.02 g of deionized water and 0.03 g of anhydrous ethanol were stirred and uniformly mixed, and the mixture was filled into a cylindrical mold, and pressed for 10 min under 0.3 MPa to form a shape, and then taken out of the mold and dried in an oven at 100°C for 24 h. The dried product was crushed and sieved to obtain a VPO catalyst having linear pores with a size of 20-60 mesh.

[0048] Example 6

[0049] First, 0.01 g of 2-amino-2-hydroxymethyl-l,3-propanediol and 4 g of cetyltrimethylammonium p-toluenesulfonate were dissolved in 300 mL of deionized water, and stirred for 0.4 h under the conditions of 90% humidity and 100°C. 18.1 g of V2O5 and 5.4 g of benzyl alcohol, 7.4 g of isobutyl alcohol, and 40 g of tetraethyl orthosilicate reagent were heated to 75°C and refluxed for 2 h, and then 19.6 g of phosphoric acid was added and reacted for 2 h. The resulting solid was suction-filtered and washed with deionized water, and the remaining template was thoroughly washed. Subsequently, drying was performed in an oven at 80°C for 12 h, and the dried sample was ground to obtain a powder with the template. Subsequently, the obtained powder was placed in a muffle furnace, and calcined at 500°C for 2.5 h to remove the hard template, thereby obtaining a spherical VPO catalyst having linear pores. 5 g of the catalyst precursor and 0.02 g of deionized water and 0.03 g of anhydrous ethanol were stirred and uniformly mixed, and the mixture was filled into a cylindrical mold, and pressed for 10 min under 0.3 MPa to form a shape, and then taken out of the mold and dried in an oven at 100°C for 24 h. The dried product was crushed and sieved to obtain a VPO catalyst having linear pores with a size of 20-60 mesh.

[0050] Example 7

[0051] First, 0.91 g of 2-hydroxymethylaminoethanol and 1.36 g of hexadecyltrimethylammonium p-toluenesulfonate were dissolved into 450 mL of deionized water, and stirred for 12 h under the conditions of 30% humidity and 60°C. 0.16 g of V02 and 0.2 g of benzyl alcohol and 12.6 g of fumed silica were added, heated to 62°C and refluxed for 6 h, and then 0.1 g of phosphoric acid was added and reacted for 2 h. The generated solid was washed by suction filtration with deionized water, and the residual templates were washed thoroughly. Subsequently, drying was performed in an oven at 80°C for 12 h, and the dried sample was ground to obtain a powder with templates. Subsequently, the obtained powder was placed in a muffle furnace, calcined at 400°C for 10 h to remove the hard template, and a spherical VPO catalyst with linear pores was obtained. 5 g of the catalyst precursor, 1 g of deionized water, and 1 g of anhydrous ethanol were stirred and mixed uniformly, the mixture was filled into a cylindrical mold, and was pressed for 10 min under 0.3 MPa to form a shape. After demolding, it was placed in an oven and dried at 100°C for 24 h, and then was crushed and sieved to obtain a VPO catalyst with linear pores of 20-60 mesh.

[0052] Comparative Example 1

[0053] The ordinary VPO catalyst of the comparative example was prepared by using the existing disclosed VPO catalyst preparation method.

[0054] 18.1 g of V205 and 5.4 g of benzyl alcohol, 7.4 g of isobutyl alcohol were taken, heated to 100°C and refluxed for 3 h, and then 19.6 g of phosphoric acid was added and reacted for 3 h. The generated solid was washed by suction filtration with deionized water. Subsequently, drying was performed in an oven at 100°C for 12 h, and the dried sample was ground to obtain a powder. Subsequently, the obtained powder was placed in a muffle furnace, calcined at 500°C for 6 h to obtain a VPO catalyst; 5 g of the catalyst precursor, 6 g of deionized water, and 4 mL of anhydrous ethanol were stirred and mixed uniformly, the mixture was filled into a cylindrical mold, and was pressed for 10 min under 0.3 MPa to form a shape. After demolding, it was placed in an oven and dried at 100°C for 24 h, and then was crushed and sieved to obtain a shaped VPO catalyst of 20-60 mesh.

[0055] The oxidation of butane to maleic anhydride was carried out in a fixed bed reactor. The shaped VPO catalyst was loaded into a tubular reactor, with a packing height of 3 cm and a length-diameter ratio of 2. A custom-made butane mixed gas with a concentration of 1% was introduced into the tubular reactor to activate the catalyst. The gas was preheated at a rate of 25°C / h to 200°C, and then the preheated gas was introduced into the tubular reactor at a pressure of 0.15 MPa and a space velocity of 1000 h-1. After 24 h of activation, the reaction temperature was increased to 410°C, and sampling of the reaction was started. The tail gas was introduced into an online TCD detector for analysis of the results at different time points. The experimental results are as follows, which show that the service life of the catalyst of the present application is greatly extended. -1 The oxidation of butane to maleic anhydride was carried out in a fixed bed reactor. The shaped VPO catalyst was loaded into a tubular reactor, with a packing height of 3 cm and a length-diameter ratio of 2. A custom-made butane mixed gas with a concentration of 1% was introduced into the tubular reactor to activate the catalyst. The gas was preheated at a rate of 25°C / h to 200°C, and then the preheated gas was introduced into the tubular reactor at a pressure of 0.15 MPa and a space velocity of 1000 h-1. After 24 h of activation, the reaction temperature was increased to 410°C, and sampling of the reaction was started. The tail gas was introduced into an online TCD detector for analysis of the results at different time points. The experimental results are as follows, which show that the service life of the catalyst of the present application is greatly extended.

[0056]

[0057]

Claims

1. A process for the preparation of a spherical VPO catalyst having linear channels, characterized in that, The method comprises the following steps: S1: Dissolve the mineralizer A and the template B in water, mix by stirring, add alcohol and vanadium in oxidation state, heat to reflux, add phosphoric acid for continuous reaction, then add silicon source, wash and dry the obtained solid, and calcine to remove the template to obtain a precursor; S2: Add the precursor to small molecule alcohol and water, and obtain catalyst particles by pressing, demolding, drying, crushing and sieving; In S1, the mineralizer A is one or more of 2-amino-2-hydroxymethyl-1, 3-propanediol, 3-aminophenol, 4-amino-5-methylpyridine-2-ol, 6-amino-2-hydroxymethyl-n-1-hexanol, 6-amino-2-hydroxymethyl-n-hexane-1-alcohol, tromethamine, 4-dimethylamino-1-butanol, 2-hydroxymethylaminoethanol, (S)-2-Boc-amino-1, 4-butanol; In S1, the template B is an organic ammonium salt; In S1, the molar ratio of the mineralizer A to the template B is 1:(0.1-120); In S1, the molar ratio of the template B to the silicon source to water is 1:(1-100):(100-10000); In S1, the molar ratio of vanadium element to alcohol to silicon element is 1:(0.1-100):(0.1-100).

2. The method of claim 1, wherein, The template in S1 is one or more of tetraethylammonium bromide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium p-toluenesulfonate, and octadecyltrimethylammonium chloride; And / or, the alcohol in S1 is a C1-C12 small molecule alcohol; And / or, the vanadium in oxidation state in S1 is a vanadium oxide compound; And / or, the silicon source in S1 is a silicon compound.

3. The method of claim 2, wherein, The alcohol in S1 is one or more of methanol, benzyl alcohol, ethanol, isobutyl alcohol, and n-hexanol; And / or, the vanadium in oxidation state in S1 is one or more of vanadium dioxide, divanadium trioxide, and divanadium pentoxide; In S1, the molar ratio of phosphorus element to vanadium element is 1:(0.1-100); And / or, the silicon source in S1 is one or more of neutral silicon sol, fumed silica, white carbon black, tetraethyl orthosilicate, silicic acid, trimethylsilicic acid, and silicon tetracetate.

4. The method according to claim 1 or 2, characterized in that, The reflux temperature in S1 is 50-100℃, and the reflux time is 1-24h; And / or, the calcination temperature in S1 is 400-900℃, and the time is 2-10h.

5. The method according to claim 1 or 2, characterized in that, The VPO catalyst obtained in S1 is microscopically spherical with linear pores.

6. The method of claim 1, wherein, In S2, a C1-C12 small molecule alcohol is added; And / or, the particle size sieved in S2 is 20-60 mesh.

7. The method of claim 6, wherein, In S2, one or more of methanol, ethanol, n-propanol, n-butanol, ethylene glycol, 1, 4-butanediol, n-hexanol, and lauryl alcohol is added; In S2, the mass ratio of alcohol to water is 1:(0.1-100); In S2, the total mass of alcohol and water accounts for 1%-100% of the mass of the precursor.

8. A spherical VPO catalyst having linear channels, prepared by the method of any one of claims 1 to 7, characterized in that, The catalyst is microscopically spherical with linear pores.

9. A process for extending the life of a VPO catalyst for the oxidation of n-butane to maleic anhydride, said process using a catalyst prepared according to the method of any one of claims 1 to 7, or a catalyst according to claim 8, characterised in that, The catalyst used in the process is microscopically spherical with linear pores.

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