A shaped catalyst for the selective oxidation of n-butane and a process for its preparation

Abstract

The present application provides a shaped catalyst for selective oxidation of n-butane and a preparation method thereof. The shaped catalyst comprises an active component and a hydroxyl silicate, wherein the active component comprises vanadium phosphorus oxide. The present application also provides a method for preparing maleic anhydride by using the catalyst. In the preparation process of the catalyst, the hydroxyl silicate is added as a lubricant and a reinforcing agent, the mechanical strength of the shaped body of the catalyst after the hole expansion treatment is improved, various shaped bodies with stable structures are obtained, and the selective oxidation of n-butane can produce valuable products with high selectivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst synthesis, in particular, to a shaped catalyst for selective oxidation of n-butane and a preparation method thereof. BACKGROUND

[0002] With the development of oil refining and ethylene industry in China, it is an urgent problem to be solved to economically and rationally utilize more and more C4 hydrocarbons in recent years. The n-butane with high content in C4 hydrocarbons can be converted into maleic anhydride by selective oxidation. Maleic anhydride is a high value-added functional synthetic monomer, and high-performance materials can be obtained by further processing of maleic anhydride through a synthesis process.

[0003] Vanadium-phosphorus-oxide (VPO) catalyst is the most widely used industrial catalyst for the oxidation of n-butane to maleic anhydride. There are a large number of published literatures and patent technologies about the preparation method of VPO catalyst. Generally, an organic solvent method using a single or mixed system of isobutyl alcohol and benzyl alcohol as a solvent is adopted. The specific process is to disperse a vanadium source in an organic solvent, stir and heat to reflux for reaction, continuously add a phosphorus source during the process, and obtain a catalyst precursor by reflux. The catalyst precursor is activated by heat treatment in a certain atmosphere to obtain a catalyst substrate powder. The catalyst substrate powder is formed into a certain shape by a certain forming method.

[0004] Generally, such catalyst shaped bodies are loaded in a high-temperature fixed-bed tubular reactor for gas-solid selective oxidation reaction. For gas-solid catalytic oxidation reaction, the selectivity and rate of the reaction are greatly limited by the number of active sites on the surface of the catalyst and the rate of the reactant diffusing to the active sites. The diffusion of the reactant on the pore structure of the catalyst and the contact with the active sites become the limiting steps of the reaction, which requires the catalyst to have a suitable pore structure, so that the catalyst can play a role in more active sites inside the catalyst. More similar catalysts adopt the operation of expanding the pores of the shaped catalyst to improve the utilization rate of the active components of the catalyst. Higher specific surface area and pore volume are beneficial to the rapid conversion of the reactant on the catalyst, but after a high flow rate of gas flows through the catalyst under long-term high-temperature conditions, the catalyst must have high mechanical stability to reduce the powder falling, structure collapse and even the reduction of catalyst life and device failure as much as possible. However, the two most important properties of such catalyst shaped bodies, i.e. the optimal pore volume and the optimal mechanical strength, cannot be achieved simultaneously in one shaped body. The shaped body with high pore volume has low mechanical strength, and the shaped body with high mechanical strength often uses the method of increasing the catalyst forming pressure or the self-density of the catalyst to improve the mechanical strength of the catalyst, resulting in generally low pore volume.

[0005] The shaped catalyst is generally prepared by a punch forming method in the industry. Graphite is generally added as a lubricant during punch forming to reduce the cumulative scratches caused by the friction between the catalyst pellets and the inner cavity of the mold. Meanwhile, the graphite itself has a sheet-like ductility, which enhances the mechanical strength of the formed particles and thus plays a role in structural reinforcement. However, graphite powder has strong fluidity and is easy to be detached from the catalyst body and covered on the surface of the catalyst during the reaming operation of the shaped catalyst, which affects the performance of the catalyst. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a shaped catalyst for the selective oxidation of n-butane and a preparation method thereof. Compared with the catalyst forming body in the prior art, the present application forms an improved shaped catalyst by adding a certain amount of hydroxyl silicate as a lubricant and a structural reinforcing agent during the formation of catalyst substrate powder. The lateral impact pressure of the shaped catalyst is increased, and the overall mechanical strength of the catalyst is improved, which is beneficial to its long-period use in a high-temperature reactor. The catalyst has the characteristics of high raw material conversion rate and high selectivity and yield of the target product in the selective oxidation reaction of n-butane.

[0007] One of the objects of the present application is to provide a shaped catalyst for the selective oxidation of n-butane, which comprises an active component and a hydroxyl silicate, wherein the active component comprises vanadium phosphorus oxide.

[0008] Preferably, the active component can further comprise a metal additive selected from at least one of molybdenum, indium, niobium, bismuth, cobalt, zinc, iron, and tungsten.

[0009] In the shaped catalyst of the present application, the hydroxyl silicate is preferably at least one of aluminum hydroxyl silicate, magnesium hydroxyl silicate, copper hydroxyl silicate, and a natural mineral containing hydroxyl silicate.

[0010] The hydroxyl silicate can also be surface-modified.

[0011] Preferably, the content of the hydroxyl silicate in the shaped catalyst is 0.1-8wt%, more preferably 0.1-5wt%, and most preferably 0.6-4.8wt%. Specifically, the content of the hydroxyl silicate can be 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt%, 5.0wt%, 5.5wt%, 6.0wt%, 6.5wt%, 7.0wt%, 7.5wt%, 8wt%, etc.

[0012] Preferably, the shaped catalyst can further comprise a lubricant, which is preferably at least one of graphite, starch, and stearate.

[0013] The lubricant is preferably 0-10wt% of the shaped catalyst, more preferably 0-6wt%. Specifically, the lubricant content can be 0.01wt%, 0.1wt%, 0.5wt%, 1wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, 9.0wt%, 10.0wt% and the like of the shaped catalyst.

[0014] In the present application, the lateral impact strength of the shaped catalyst is 10-70N, preferably 20-60N.

[0015] The specific surface area of the shaped catalyst is 5-100m 2 / g, preferably 10-70m 2 / g.

[0016] The pore volume of the shaped catalyst is 0.10-0.20cm 3 / g, preferably 0.15-0.20cm 3 / g.

[0017] The second object of the present application is to provide a preparation method of the shaped catalyst, comprising the following steps:

[0018] S1, adding raw materials including active component sources to a liquid solvent for reaction;

[0019] S2, separating solid materials in the reaction product of step S1, and drying to obtain a catalyst precursor;

[0020] S3, heat treating the catalyst precursor, then shaping to obtain a green compact, and crushing the green compact after activation treatment to obtain a substrate powder of the shaped catalyst;

[0021] S4, mixing the substrate powder of the shaped catalyst with a pore expander, shaping again to obtain a catalyst green compact, and performing pore expansion treatment to obtain the shaped catalyst;

[0022] In the raw materials of step S1 and / or the catalyst precursor after heat treatment of step S3 and / or the substrate powder of the shaped catalyst of step S3, hydroxyl silicate is added.

[0023] In the preparation method of the present application, step S1 comprises the following steps:

[0024] S1-1) mixing part of the active component sources with the liquid solvent and heating;

[0025] S1-2) adding the remaining active component sources and continuing heating.

[0026] In step S1-1), the active component source includes a vanadium-containing compound, a phosphorus-containing compound, and an oxygen-containing compound.

[0027] The vanadium-containing compound, the phosphorus-containing compound, and the oxygen-containing compound are not particularly limited and can be any compound commonly used in the art for preparing vanadium phosphorus oxides.

[0028] In step S1-1), the liquid solvent is an organic alcohol, which is preferably at least one of isobutyl alcohol, isopropyl alcohol, sec-butyl alcohol, 2-methylbutyl alcohol, cyclohexylethanol, 2-ethyl 1-hexanol, and benzyl alcohol.

[0029] In step S1-1), the heating temperature is 80-140°C and the heating time is 0-5h; preferably, the heating temperature is 100-140°C and the heating time is 3-5h.

[0030] In step S1-2), the heating temperature is 100-140°C and the heating time is 3-24h; preferably, the heating temperature is 110-140°C and the heating time is 3-16h.

[0031] In step S1-1), the mixture of the partial active component source and the liquid solvent can also be added with the remaining active component source without heating.

[0032] In step S1-2), a hydroxyl silicate can be added.

[0033] The hydroxyl silicate is preferably at least one of aluminum hydroxyl silicate, magnesium hydroxyl silicate, copper hydroxyl silicate, and a natural mineral containing hydroxyl silicate.

[0034] The hydroxyl silicate can also be surface-modified, for example, to obtain a hydroxyl silicate with surface amino modification.

[0035] The size of the selected hydroxyl silicate is 20-2000nm, preferably 50-2000nm.

[0036] When the hydroxyl silicate is added in step S1-2), the amount of the hydroxyl silicate added is 0.1-15wt% of the vanadium-containing compound, preferably 0.15-10wt%, and more preferably 0.15-8.5wt%. Specifically, the amount of the hydroxyl silicate added can be 0.1wt%, 0.5wt%, 1wt%, 2.0wt%, 3.0wt%, 4.0wt%, 5.0wt%, 6.0wt%, 7.0wt%, 8.0wt%, 9.0wt%, 10.0wt%, 11.0wt%, 12.0wt%, 13.0wt%, 14.0wt%, 15.0wt%, etc. of the vanadium-containing compound.

[0037] Optionally, a metal assistant source can be added in step S1-2).

[0038] The metal elements in the metal promoter of the shaped catalyst include one or more of molybdenum, indium, niobium, bismuth, cobalt, zinc, iron and tungsten.

[0039] The metal promoter source can be an oxide, a salt, a nitrate, a carbonate, a bicarbonate, a sulfate, a phosphate, a hydrogen phosphate, a halide, or a complex thereof, such as an oxalate or an acetylacetone complex, of the metal element.

[0040] In the preparation method, the amounts of the vanadium compound, the phosphorus-containing compound and the oxygen-containing compound in the active component source are not particularly limited, and the amounts commonly used in the field of catalysts can be used.

[0041] In the preparation method, the amount of the metal promoter source is not particularly limited, and the amount commonly used in the field of catalysts can be used.

[0042] In the preparation method, in step S2, drying is performed at 60-150°C for 6-24h, and preferably at 100-120°C for 12-24h.

[0043] In the preparation method, in step S3, the catalyst precursor is heat treated, preferably at 120-300°C for 2-36h, and more preferably at 150-300°C for 4-7h.

[0044] In the preparation method, in step S3, the shaping treatment includes pressing the heat treated catalyst precursor to obtain a green compact, and the green compact has a bulk density of 0.8-1.6g / cm 3 , preferably 1.0-1.4g / cm 3 .

[0045] In the preparation method, in step S3, a hydroxyl silicate can be added to the heat treated catalyst precursor.

[0046] When the hydroxyl silicate is added to the heat treated catalyst precursor, the hydroxyl silicate is 0.05-8wt% of the catalyst precursor, and preferably 0.1-5wt%. Specifically, the hydroxyl silicate can be 0.05wt%, 0.1wt%, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt%, 5.0wt%, 5.5wt%, 6.0wt%, 6.5wt%, 7.0wt%, 7.5wt%, 8.0wt% or the like of the catalyst precursor.

[0047] When the hydroxyl silicate is added to the matrix powder of the shaped catalyst, the hydroxyl silicate is 0.1-8 wt% of the matrix powder of the shaped catalyst, preferably 0.1-5 wt%, and more preferably 0.6-4.8 wt%. Specifically, the hydroxyl silicate can be 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, 5.5 wt%, 6.0 wt%, 6.5 wt%, 7.0 wt%, 7.5 wt%, 8.0 wt% or the like of the matrix powder of the shaped catalyst.

[0048] In the preparation method of the present application, in step S3, a lubricant can be added,

[0049] The lubricant can be added before or after the heat treatment of the catalyst precursor, and the lubricant is 0.1-10 wt% of the catalyst precursor, preferably 0.1-6 wt%.

[0050] Alternatively, the lubricant can also be added to the matrix powder of the shaped catalyst, and the lubricant is 0.05-9 wt% of the matrix powder of the shaped catalyst, preferably 0.09-5.5 wt%.

[0051] The lubricant is graphite, starch, magnesium stearate or other stearate.

[0052] When the hydroxyl silicate and graphite are simultaneously added to the shaped catalyst, the mass ratio of the hydroxyl silicate to the graphite is preferably (10-90):(90-10), and more preferably (20-80):(80-20).

[0053] In the preparation method of the present application, in step S3, the activation treatment comprises placing the green block in an air and / or water vapor and / or nitrogen atmosphere, heating at a heating rate of 1-6 ℃ / min to 250-420 ℃, and then keeping for 0.5-8 h under the condition of changing or not changing the atmosphere; continuing to heat at a heating rate of 2-6 ℃ / min to 400-550 ℃, and continuing to keep for 3-8 h under the condition of changing or not changing the atmosphere; and then cooling to room temperature under the protection of adding or not adding inert gas to obtain the activated catalyst green block.

[0054] In the preparation method of the present application, in step S4, when tabletting or extrusion is used, the pore-expanding agent is 2-25 wt% of the matrix powder of the shaped catalyst, preferably 4-14 wt%, and more preferably 6-14%.

[0055] The pore-expanding agent is a polyhydroxy organic compound, and is preferably at least one of 1,1,1-trimethylolethane, trimethylolpropane, glycolic acid, salicylic acid, malic acid, tartaric acid, citric acid, and citric acid.

[0056] In step S4, when using extrusion molding, after the matrix powder of the molding catalyst is mixed with the pore expander, a binder and water can be added and the molding can be repeated.

[0057] Preferably, the binder is 1 to 4.5 wt% of the shaped catalyst matrix powder, the binder is 10 to 18 wt% of the added water, and the binder is cellulose and its derivatives.

[0058] The binder is cellulose and its derivatives. The cellulose and its derivatives are cellulose ethers, anionic cellulose derivatives, and nonionic cellulose derivatives, preferably at least one selected from methylcellulose, ethylcellulose, sodium carboxymethylcellulose, cellulose acetate, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxypropyl methylcellulose.

[0059] In the preparation method of the present invention, in step S4, the pore expansion treatment adopts a liquid medium contact method and a reduced pressure heating extraction method.

[0060] The liquid medium is selected from organic solvents with a polarity <5, preferably from at least one of diethyl ether, petroleum ether, ethyl acetate, acetone, propanol, isobutanol, n-butanol, dichloromethane, and p-xylene; the volume ratio of the liquid medium to the catalyst preform is (1-5):1, preferably (1-3):1.

[0061] The conditions for the vacuum heating extraction method include: a vacuum degree of 10... 2 ~10 5 Pa, heating temperature <150℃; time 1~24h.

[0062] A third objective of this invention is to provide a shaped catalyst obtained by the aforementioned preparation method.

[0063] The fourth objective of this invention is to provide a method for oxidizing n-butane to produce maleic anhydride, comprising oxidizing n-butane in the presence of a catalyst, wherein the catalyst is the molding catalyst described above or the molding catalyst obtained by the preparation method described above.

[0064] In the method for oxidizing n-butane to maleic anhydride, the reaction conditions include a reaction temperature of 370–430°C, preferably 390–420°C; a pressure of 0.01–0.2 MPa; and a total space velocity (GHSV) of 800–2500 h⁻¹ for the reaction mixture. -1 Preferably 1000-2200h -1 The volume fraction of n-butane is 1.5–2.0%.

[0065] The present application provides a kind of shaped catalyst for catalytic conversion of organic components in fixed bed reactor and its preparation method, more particularly, it relates to a shaped catalyst for selective oxidation of n-butane, which contains catalytic material in the catalyst structure, and a plurality of shaped bodies with stable structure are obtained by adding hydroxyl silicate as lubricant and reinforcing agent during catalyst preparation and calcination, and the selective oxidation of n-butane can produce valuable products with high selectivity.

[0066] Hydroxyl silicate has a good layered unit structure, and the interlayer is connected by hydrogen bond and van der Waals force, which is much smaller than the bond energy of ionic bond and covalent bond in each layer. It is easy to spread and dissociate in the direction parallel to the layer under high pressure. Its layered structure is very similar to that of graphite. When used as a lubricating material, hydroxyl silicate has a small friction coefficient and excellent friction and wear resistance, and has great application potential in the field of friction. At the same time, during the friction process, the hydroxyl silicate layer can spread on the surface of the catalyst particles, deposit, or react with the surface groups of the catalyst, and the rigid structure of the layer can ensure the stability of the pores formed by the secondary particles inside the catalyst. At the same time, under high temperature reaction, the rigid structure of the added hydroxyl silicate in the shaped catalyst can withstand the drastic change of temperature without being damaged, which is beneficial to the maintenance of the overall structure of the catalyst and the long-term use of the catalyst.

[0067] The catalyst provided by the present application is used in the fixed bed reactor for catalytic oxidation of butane, and the butane conversion rate can reach 84.9%, and the molar of maleic anhydride can reach 60.0%. Under the same reaction conditions, compared with vanadium-phosphorus-oxygen catalyst without adding hydroxyl silicate or vanadium-phosphorus-oxygen catalyst only adding hydroxyl silicate and not being treated by hole expansion, the butane conversion rate can be increased by 0.2-1.6%, the selectivity of maleic anhydride can be increased by 0.2-6.3%, and the weight yield of maleic anhydride can be increased by 0.3-5.5%. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 The shape structure of the shaped catalyst of the present application is shown in the figure.

[0069] Among them, a is a hollow cylinder; b is a three-petal flower-shaped hollow cylinder; c is a four-petal flower-shaped hollow cylinder; d is a five-petal flower-shaped hollow cylinder; e is a six-petal flower-shaped hollow cylinder; f is a seven-petal flower-shaped hollow cylinder. DETAILED DESCRIPTION

[0070] The present application will be specifically described below in combination with specific examples. It is necessary to point out here that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments of the present application made by those skilled in the art according to the content of the present application still belong to the protection scope of the present application.

[0071] The raw materials used in the examples and comparative examples, if not specifically defined, are disclosed in the prior art, for example, can be directly purchased or prepared according to the preparation method disclosed in the prior art.

[0072] In a preferred embodiment of the present application, the method for preparing the shaped body of catalyst for selective oxidation of n-butane can comprise the following steps:

[0073] S1, adding raw materials including sources of active components into a liquid solvent to react at a certain temperature for a period of time;

[0074] S2, extracting the liquid solvent therefrom, and drying the separated solid material at 60-150°C to prepare a catalyst precursor;

[0075] S3, heat treating the catalyst precursor, then shaping to obtain a green body, and then activating the green body in different atmospheres at 250-550°C, and finally crushing to prepare the catalyst substrate powder for selective oxidation of n-butane;

[0076] S4, mixing the obtained catalyst substrate powder with a certain amount of pore-expanding agent, shaping again, and then pore-expanding to obtain the shaped catalyst.

[0077] In the above technical solution, the sources of active components include vanadium-containing compounds, phosphorus-containing compounds, and oxygen-containing compounds, wherein the source of vanadium element is vanadium compounds, preferably at least one of ammonium metavanadate, vanadic oxide or organic acid vanadium; the source of phosphorus element is phosphorus-containing compounds, preferably at least one of vanadic oxide, phosphoric acid with different mass contents and pyrophosphoric acid. The oxygen-containing compound is preferably at least one of oxalic acid and vitamin C.

[0078] According to a more preferred embodiment of the present application, the step S1 comprises:

[0079] S1-1) adding a dispersion system containing part of the sources of active components into a liquid solvent and heating to a certain temperature;

[0080] S1-2) adding a dispersion system containing the remaining sources of active components to the reaction system of step S1-1) and continuing to heat to a certain temperature to obtain a reaction liquid containing precipitates.

[0081] In the above technical solution, the sources of active components include vanadium-containing compounds, phosphorus-containing compounds, and oxygen-containing compounds, wherein the source of vanadium element is vanadium compounds, preferably at least one of ammonium metavanadate, vanadic oxide or organic acid vanadium; the source of phosphorus element is phosphorus-containing compounds, preferably at least one of vanadic oxide, phosphoric acid with different mass contents and pyrophosphoric acid. The oxygen-containing compound is preferably at least one of oxalic acid and vitamin C.

[0082] In some specific embodiments, the vanadium-containing compounds and oxygen-containing compounds are first added to the liquid solvent in step S1-1).

[0083] Optionally, an auxiliary metal element substance is added in step S1-2).

[0084] In the technical solution, the metal elements in the metal auxiliary include one or more of molybdenum, indium, niobium, bismuth, cobalt, zinc, iron and tungsten, and the source is an oxide, nitrate, carbonate, bicarbonate, sulfate, phosphate, hydrogen phosphate, halide or complex of the added metal element, such as oxalate or acetylacetone complex.

[0085] According to the preparation method of the present application, the order of adding the metal auxiliary is not particularly limited, and the metal auxiliary or a solution thereof can be directly added to the dispersion system containing the source of the remaining active component in step S1-2), or directly added to the formed mixed reaction liquid, or added simultaneously.

[0086] In some specific embodiments, the reaction system of step S1-2) is cooled to 25-80℃, and an auxiliary metal element substance is added thereto, and the reaction is continued by heating and refluxing to obtain a reaction liquid containing precipitates.

[0087] Optionally, a certain amount of hydroxyl silicate is added to the dispersion system in step S1-2).

[0088] In the technical solution, the hydroxyl silicate is one or a mixture of two of aluminum hydroxyl silicate, magnesium hydroxyl silicate or copper hydroxyl silicate, such as magnesium aluminum silicate, and also includes natural mineral powder containing hydroxyl silicate or surface-modified hydroxyl silicate products.

[0089] According to a preferred embodiment of the present application, the liquid solvent in step S1-1) is not particularly limited, and a common solvent in the art can be selected according to the different catalyst reaction systems. According to some embodiments of the present application, for a catalyst for the oxidation of n-butane to produce succinic anhydride, the solvent is preferably an organic alcohol, and the organic alcohol is preferably at least one of isobutyl alcohol, isopropyl alcohol, sec-butyl alcohol, 2-methylbutyl alcohol, cyclohexylethanol, 2-ethyl-1-hexanol, and benzyl alcohol, and is particularly preferably a mixed solvent of isobutyl alcohol and benzyl alcohol in any molar ratio. In some specific embodiments, the molar ratio of isobutyl alcohol to benzyl alcohol is (100-85):(0-15).

[0090] According to a preferred embodiment of the present application, the method and conditions in step S1-1) are not particularly limited, and for example, the mixed liquid can be heated to 80-140℃.

[0091] According to a preferred embodiment of the present application, the reaction time of step S1-1) is 0-5h, and is preferably 3-5h.

[0092] According to a preferred embodiment of the present application, the method and conditions in step S1-2) are not particularly limited, for example, the reaction system of step S1-1) can be cooled to 25-80°C, and then a dispersion system containing the source of the remaining active component is added, and the reaction is continued by heating to 100-140°C.

[0093] According to a preferred embodiment of the present application, the reaction time of step S1-2) is 3-24h, preferably 3-16h.

[0094] According to a preferred embodiment of the present application, in step S2, the reaction liquid containing the precipitate is subjected to solid-liquid separation treatment, and the obtained solid precipitate is dried to obtain the catalyst precursor.

[0095] According to the preparation method of the present application, the treatment in step S2 is not particularly limited, for example, the reaction liquid containing the precipitate can be subjected to filtration or centrifugation treatment to obtain the precipitate, or the solid precipitate can be obtained by evaporating the solvent in the reaction liquid, and finally the catalyst precursor is dried at 60-150°C for 6-24h, preferably at 100-120°C for 12-24h.

[0096] According to a more preferred embodiment of the present application, step S3 can include:

[0097] S3-1) heat treatment of the catalyst precursor, followed by pressing to obtain a green body;

[0098] S3-2) activation treatment of the green body in an air and / or water vapor and / or nitrogen atmosphere to obtain an activated catalyst, and finally crushing to obtain a matrix powder of the shaped catalyst.

[0099] According to a preferred embodiment of the present application, the heat treatment is carried out at 120-300°C for 2-36h.

[0100] Optionally, the catalyst precursor is mixed with a lubricant before heat treatment, or the catalyst precursor is mixed with a lubricant before heat treatment, or the lubricant is mixed with the matrix powder of the shaped catalyst.

[0101] According to a preferred embodiment of the present application, the catalyst precursor is mixed with a lubricant to obtain a mixture, and then heated at a temperature of 120-300°C for 2-36h, and finally pressed into a green body with a certain shape.

[0102] In a more preferred embodiment, the vanadium-phosphorus-oxygen catalyst precursor powder is mixed with a lubricant, and then heated at a temperature of 150-300°C for 5-7h, and finally pressed into a cylindrical green body.

[0103] According to a preferred embodiment of the present application, the lubricant is 0.1-10 wt%, preferably 0.1-6 wt% of the catalyst precursor.

[0104] According to a preferred embodiment of the present application, the lubricant is 0.05-9 wt%, preferably 0.09-5.5 wt% of the matrix powder of the shaped catalyst.

[0105] In some specific embodiments, the lubricant comprises graphite, starch, magnesium stearate or other stearate.

[0106] According to the preparation method of the present application, for the lubricant and reinforcing agent in step S1-2) of procedure S1 and steps S3-1) and S3-2) of procedure S3, the size of the hydroxyl silicate is 20-2000 nm, preferably 50-2000 nm.

[0107] When the hydroxyl silicate is added in step S1-2), the amount of the hydroxyl silicate added is 0.1-15 wt%, preferably 0.15-10 wt%, more preferably 0.15-8.5 wt% of the vanadium-containing compound.

[0108] When the hydroxyl silicate is added in step S3-1), the amount of the hydroxyl silicate added is 0.05-8 wt%, preferably 0.1-5 wt% of the catalyst precursor.

[0109] When the hydroxyl silicate is added in step S3-2), the amount of the hydroxyl silicate added is 0.1-8 wt%, preferably 0.1-5 wt%, more preferably 0.6-4.8 wt% of the matrix powder of the shaped catalyst.

[0110] According to a preferred embodiment of the present application, the hydroxyl silicate with a certain size can be prepared in many ways, and various powders of hydroxyl silicate-containing ores such as serpentine can be directly purchased on the market, or hydrolysis and precipitation methods well known to those skilled in the art can be used for synthesis and subsequent surface modification.

[0111] According to the preparation method of the present application, the order of adding the hydroxyl silicate is not particularly limited, for example, a certain amount of hydroxyl silicate can be added in step S1-2) of procedure S1, a certain amount of hydroxyl silicate can be added in step S3-1) in the non-heat-treated catalyst precursor, a certain amount of hydroxyl silicate can be added in step S3-2) in the dry matrix powder, or a certain amount of hydroxyl silicate can be added in two or three of the above steps at the same time.

[0112] According to some embodiments of the present application, the catalyst precursor compact will change its bulk density greatly due to the formation of new phases from the decomposition of its components during the activation process, and the weight loss rate will be between 5% and 50%. Therefore, the catalyst precursor needs to be pressed into a compact with a higher bulk density. The bulk density of the compact is related to the weight loss rate of the catalyst after activation. According to some embodiments of the present application, the weight loss rate of the catalyst after activation is between 5% and 20% depending on the properties and composition of the precursor, and the bulk density of the compact is between 0.8 and 1.6 g / cm 3 , preferably between 1.0 and 1.4 g / cm 3 .

[0113] According to a preferred embodiment of the present application, the activation process comprises: placing the compact in an air and / or water vapor and / or nitrogen atmosphere, heating at a heating rate of 1-6°C / min to 250-420°C, and then keeping for a period of time under the condition of changing or not changing the atmosphere, preferably in the range of 0.5-8h; continuing to heat at a heating rate of 2-6°C / min to 400-550°C, and then keeping for a period of time under the condition of changing or not changing the atmosphere, preferably in the range of 3-8h; and then cooling the activated compact to room temperature under the protection of adding or not adding inert gas.

[0114] In a more preferred embodiment, the compact is first placed in an air atmosphere and heated at a heating rate of 2-4°C / min to 250-300°C, then the atmosphere is changed to a mixed atmosphere of 50% water vapor and 50% air, and heated at a heating rate of 2-6°C / min to a temperature below 435°C on the surface of the catalyst, and kept for 0.1-2h under this condition, then the atmosphere is changed to 100% nitrogen, and the calcination is continued for 5-8h under this atmosphere, and then cooled to room temperature under nitrogen protection to obtain the activated vanadium-phosphorus-oxygen catalyst matrix powder.

[0115] According to a preferred embodiment of the present application, step S4 can comprise:

[0116] S4-1) crushing the activated catalyst compact to obtain a catalyst matrix powder, mixing with a pore-expanding agent, and tabletting or extruding to obtain a catalyst rough compact;

[0117] S4-2) removing the pore-expanding agent from the rough compact to obtain the catalyst shaped body for selective oxidation of n-butane.

[0118] The catalyst molding method is not particularly limited, but due to the shape requirements of the catalyst molded body, tablet molding or extrusion molding is preferred. According to a preferred embodiment of the present application, the activated green compact in step S3 is crushed into particles of less than 20 mesh before tablet molding, and the crushed particles are sieved, wherein the weight ratio of particles between 20 and 40 mesh is 30 to 60%, and the weight ratio of particles below 40 mesh is 40 to 70%.

[0119] The change in the pore structure has a relatively important influence on the improvement of the catalyst activity, the conversion rate of raw materials, and the improvement of the selectivity of target products, and therefore, in an embodiment of the present application, the specific surface area of the catalyst is 5 to 100 m 2 / g; preferably 10 to 70 m 2 / g, and particularly preferably 10 to 50 m 2 / g; and the pore volume of the catalyst is 0.10 to 0.20 cm 3 / g, and preferably 0.15 to 0.20 cm 3 / g. Within this range, the surface of the catalyst is beneficial to the effective contact of reactant molecules with the active sites of the catalyst, and at the same time, is beneficial to the inhibition of the further peroxidation of the target product, thereby playing a role in improving the catalyst activity and the selectivity of the generated product.

[0120] According to a preferred embodiment of the present application, when tablet molding or extrusion molding is used, the pore expanding agent is 2 to 25 wt% of the molding catalyst matrix powder, preferably 4 to 14 wt%, and more preferably 6 to 14 wt%.

[0121] The pore expanding agent is a polyhydroxy organic compound, and includes one or more of 1,1,1-trimethylolethane, trimethylolpropane, glycolic acid, salicylic acid, malic acid, tartaric acid, citric acid, and citric acid, and is preferably one or more of 1,1,1-trimethylolethane, tartaric acid, and citric acid.

[0122] According to a preferred embodiment of the present application, when extrusion molding is used, the crushed catalyst particles are mixed with a certain amount of binder, pore expanding agent, and deionized water, the binder is 1 to 4.5 wt% of the molding catalyst matrix powder, the binder is 10 to 18 wt% of the mass of the added water, and the binder is cellulose and its derivatives.

[0123] The binder is cellulose and its derivatives. The cellulose and its derivatives are at least one of cellulose ether, anionic cellulose derivatives, and non-ionic cellulose derivatives, and are preferably at least one of methyl cellulose, ethyl cellulose, sodium carboxymethyl cellulose, cellulose acetate, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydroxypropyl methyl cellulose.

[0124] For the catalyst with binder, after removing the reaming agent, the binder should also be removed. The method can be used in the field, such as roasting under high temperature and nitrogen protection.

[0125] According to a preferred embodiment of the present application, the method of removing the reaming agent from the crude catalyst by using the liquid medium contact and the reduced pressure extraction operation.

[0126] According to a preferred embodiment of the present application, the liquid medium selected for the liquid medium contact should make the reaming agent slightly soluble in it, which is beneficial for the slow removal of the reaming agent from the catalyst structure, thereby avoiding the rapid collapse of the catalyst structure caused by the rapid removal of the reaming agent, and protecting the overall mechanical hardness and wear resistance of the catalyst. Generally, the solubility of the reaming agent in the liquid medium is required to be less than 8 g / 100 g. Therefore, the liquid medium suitable for the present application is selected from weakly polar organic solvents with polarity <5, including but not limited to one or more of acetone, propanol, diethyl ether, ethyl acetate, petroleum ether, isobutyl alcohol, n-butyl alcohol, dichloromethane and p-xylene, preferably one or more of acetone, dichloromethane and isobutyl alcohol.

[0127] According to the preparation method of the present application, the amount of the liquid medium is also an important factor affecting the removal effect of the reaming agent. The liquid medium should immerse the crude catalyst to be treated. In some specific embodiments, the volume ratio of the liquid medium to the crude catalyst is (1-5):1, preferably (1-3):1.

[0128] According to the previous experimental findings of the researchers, in the process of removing the reaming agent by contacting the catalyst shaped body with the liquid medium, part of the lubricant graphite will be separated from the crude catalyst along with the dissolution of the reaming agent, thereby causing the main structure to become relatively loose, and further affecting the overall mechanical hardness and wear resistance of the catalyst. However, when using hydroxyl silicate as the lubricant and reinforcing agent, the surface groups form a relatively obvious action with the shaped body, and are not easy to be removed along with the dissolution of the reaming agent, thereby being beneficial for maintaining the mechanical strength of the catalyst shaped body after reaming. In some specific embodiments, compared to using the same weight of graphite as the lubricant and reinforcing agent, the lateral impact strength of the catalyst shaped body using hydroxyl silicate is increased by 25-85%.

[0129] According to the preparation method of the present application, after the solvent impregnation of the shaped body, the liquid medium on the surface of the catalyst and part of the reaming agent remaining in the pores of the catalyst can be further removed by using the reduced pressure and heating extraction method. The vacuum degree of the reduced pressure operation is controlled at 10 2 ~10 5 Pa, and the heating temperature is <150°C; the reduced pressure operation time is 1-24 h, preferably 6-24 h.

[0130] The application relates to a preparation method of a catalyst for selective oxidation of n-butane, which comprises simultaneously adding a hydroxyl silicate as a lubricant and a structure reinforcing agent into a catalyst forming body, and performing a hole expanding operation to obtain a formed catalyst.

[0131] The formed body according to the embodiment has high and uniform mechanical strength. In some embodiments of the application, the lateral impact strength (S) of the catalyst forming body is 10N<=S<=70N, preferably 20N<=S<=60N, and more preferably 30N<=S<=50N.

[0132] According to another aspect of the application, a method for preparing maleic anhydride by oxidizing n-butane is provided, which comprises performing an oxidation reaction on n-butane in the presence of the vanadium-phosphorus-oxygen catalyst for preparing maleic anhydride by oxidizing n-butane. The catalyst provided by the application is used in a fixed bed reactor for catalyzing butane oxidation, and under the conditions of a reaction temperature of 370-430 DEG C, an air speed of 800-2500 h -1 -1, a butane volume fraction of 1.5-2.0%, a butane conversion rate of 84.9%, and a maleic anhydride yield of 60.0%. Under the same conditions, the catalytic performance of the vanadium-phosphorus-oxygen catalyst without adding the hydroxyl silicate is a butane conversion rate of 83.3% and a maleic anhydride yield of 55.9%, and the catalytic performance of the vanadium-phosphorus-oxygen catalyst with the hydroxyl silicate and without the hole expanding treatment is a butane conversion rate of 84.4% and a maleic anhydride yield of 53.4%. The conversion rate of n-butane can be increased by 1.6% at most, the selectivity of maleic anhydride can be increased by 6.3% at most, and the yield of maleic anhydride can be increased by 5.6% at most by using the formed catalyst of the application.

[0133] The specific surface area is measured by using an ASAP-2020 full-automatic specific surface area and pore size distribution instrument of Quantachrome Company of the United States.

[0134] The catalyst bulk density is measured by using a PH-702 vibration density instrument of Dalian Penghui Science and Technology Development Company.

[0135] The lateral impact strength of the catalyst is measured by using a ZQJ-III intelligent particle strength tester of Dalian Intelligent Tester Company.

[0136] The catalyst performance evaluation experiment was completed on a single tube reactor, wherein the reactor tube was 4 m long, the effective length was 3.6 m, the inner diameter of the tube was 25 mm, and a temperature measuring couple pipe with an outer diameter of 6 mm was arranged inside. The catalyst loading amount was 1200 mL, and the loading height was 3.3-3.6 m. Air and n-butane were metered by mass flow meters and then entered the reaction tube, a branch was arranged at the inlet to analyze the raw material gas composition by gas chromatography, the reaction gas was selectively oxidized to form the selective target product under the action of the activated catalyst, and a branch was arranged at the tail gas outlet to analyze the tail gas composition. Chromatographic analysis was performed by using a gas chromatograph of model 7890b of Agilent, USA. The data used in the following discussion are all data with a carbon balance of 98%-102%.

[0137] The n-butane selective oxidation reaction conditions were as follows: the reaction temperature was 370-430 ℃, preferably 390-420 ℃; the pressure was 0.01-0.2 MPa; the total air speed of the reaction raw material mixed gas was 800-2500 h -1 , preferably 1000-2200 h -1 ; and the volume fraction of n-butane was 1.5-2.0%.

[0138] The calculation of the raw material conversion rate and the selectivity of the generated product during the reaction was as follows:

[0139]

[0140]

[0141] The selectivity of maleic anhydride = 100%-S CO- S CO2 ;

[0142]

[0143]

[0144] Example 1

[0145] 960 mL of ethanol, 30 g of methyl ethanolamine, 60 g of amino silane coupling agent, and 600 g of a 10 wt% sodium silicate solution were added to a 3 L round-bottom flask, and mixed uniformly. An aluminum sulfate aqueous solution was added at 50 ℃, and the molar ratio of aluminum sulfate to sodium silicate was controlled to be 1:3. The mixture was stirred at 50 ℃ for 1 h, and then precipitated and filtered to obtain aluminum silicate. The obtained aluminum silicate particles were repeatedly washed with anhydrous ethanol for 3 times until the pH of the washing liquid was 7-8. The washed nano-aluminum silicate particles were dried in an oven at 80 ℃ for 10 h to obtain nano-hydroxy aluminum silicate particles with amino groups on the surface, and the particle size was 20-50 nm.

[0146] In a 20 L double glass reactor, 636 g of V2O5, 283 g of oxalic acid, 6750 mL of isobutyl alcohol and 750 mL of benzyl alcohol were added to form a mixed solution, heated to 100°C and heated for 3 h, 750 g of 105 wt% phosphoric acid was added dropwise, and 60 g of surface modified nano-hydroxyl aluminum silicate particles were added, heated to 100°C and stirred to reflux for 16 h, the V / P molar ratio of the raw materials was 1 / 1.15, the obtained precipitate was centrifuged and washed with anhydrous ethanol, and then dried at 60°C for 24 h. The dried catalyst precursor powder was heated at 250°C in air for 5 h, and then the powder was pressed into a cylindrical structure with a height of 3 mm and a diameter of 10 mm, and the bulk density of the structure was 1.32 g / cm 3 , the obtained catalyst precursor structure was heated to 275°C at a heating rate of 2.5°C / min in an air atmosphere, then the atmosphere was changed to a mixed atmosphere of 50% water vapor and 50% air, and maintained for 6 h, and then heated to a catalyst surface temperature of 435°C at a heating rate of 1°C / min under the operating conditions of an airspeed of 1500 h -1 , and maintained for 1 h, then the atmosphere was changed to 100% nitrogen, and continued to calcine for 6 h in this atmosphere, and then cooled to room temperature under nitrogen protection, to obtain the activated vanadium-phosphorus-oxygen catalyst. The catalyst was broken multiple times, and 1,1,1-trishydroxymethylethane was added at a mass ratio of 10 / 90 to the catalyst substrate powder, mixed uniformly, and then pressed into a hollow cylindrical catalyst with a ring-shaped cross section, the outer diameter of the catalyst structure was 5 mm, the height was 5 mm, and the inner diameter was 2 mm. After soaking in acetone for 21 h (catalyst bulk volume / solvent volume = 1 / 1.5), the obtained catalyst structure was dried at 60°C and a vacuum pressure of 10 3 Pa for 4 h, and the dried vanadium-phosphorus-oxygen catalyst for the oxidation of n-butane to maleic anhydride was obtained, the bulk density of the catalyst was 0.75 g / cm 3 , the specific surface area of the catalyst was 33.5 m 2 / g, the pore volume of the catalyst was 0.16 cm 3 / g, and the lateral impact strength of the catalyst was 48 N. The obtained catalyst was loaded into a single-tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0147] Comparative Example 1

[0148] Except that no surface modified nano-hydroxyl aluminum silicate particles were added during the reaction, and 60 g of graphite was added after the catalyst was calcined at 250°C in air (the amount of graphite added was 5.6% based on the total mass of the formed body), the other steps were the same as in Example 1, and the bulk density of the catalyst was 0.73 g / cm 3 , the specific surface area of the catalyst was 30.3 m 2 / g, and the pore volume of the catalyst was 0.15 cm 3 / g, and the lateral impact strength was 26 N. The obtained catalyst was packed into a single-tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0149] Example 2

[0150] In a 3L round bottom flask, 960 mL of ethanol, 30 g of methyl ethanolamine, 60 g of amino silane coupling agent, 600 g of 10 wt% sodium silicate solution were added and mixed uniformly, and aluminum sulfate aqueous solution and magnesium sulfate aqueous solution were added at 50°C, the molar ratio of aluminum sulfate, magnesium sulfate and sodium silicate was controlled to be 1:1:5, and stirred at 50°C for 1h, precipitated, filtered, and aluminum magnesium silicate was prepared; the aluminum magnesium silicate particles obtained by the above steps were repeatedly washed with anhydrous ethanol for 3 times until the pH of the washing liquid was 7-8; the washed nano aluminum silicate particles were placed in an oven at 80°C for drying for 10h, and nano hydroxy aluminum magnesium silicate particles with surface amino modification were obtained, and the particle size was 50-100 nm.

[0151] In a 20L double-layer glass reactor, 636g of V2O5, 283g of oxalic acid, 6750mL of a mixed solution of isobutyl alcohol and 750mL of benzyl alcohol were added, heated to 110°C and stirred for 3h, 783g of 105wt% phosphoric acid was added dropwise, and 46g of nano hydroxy aluminum magnesium silicate particles with surface amino modification were added, heated to 120°C and stirred for 16h, the molar ratio of V / P was 1 / 1.2, the obtained precipitate was centrifuged and washed with anhydrous ethanol, and then dried at 150°C for 12h. The dried catalyst precursor powder was heated in air at 250°C for 5h, and 1179g was obtained, and then the powder was pressed into a cylindrical structure with a height of 3mm and a diameter of 6mm, and the density of the structure was 1.36g / cm 3 , the obtained catalyst precursor structure was heated to 265°C at a heating rate of 2.5°C / min in an air atmosphere, then the atmosphere was changed to a mixed atmosphere of 50% water vapor and 50% air, and kept for 6h, and then heated to a catalyst surface temperature of 431°C at a heating rate of 2°C / min, and kept for 2h under this condition, then the atmosphere was changed to 100% nitrogen, and continued to calcine for 5h under this atmosphere, and then cooled to room temperature under nitrogen protection, and an activated vanadium-phosphorus-oxygen catalyst was obtained. The catalyst was broken repeatedly, and 1,1,1-trishydroxymethylethane was added in a mass ratio of 12 / 88 to the catalyst matrix powder, mixed uniformly, and then pressed into a hollow cylinder with a cross-section of a three-petal flower-shaped catalyst, and the outer diameter of the catalyst structure was 6mm, the height was 5mm, and the inner diameter was 2mm. After soaking in acetone for 21h (catalyst bulk volume / solvent volume=1 / 2), the obtained catalyst structure was dried for 4h under vacuum at 60°C and a vacuum pressure of 10 2 Pa, and the dried catalyst was used for the oxidation of n-butane to maleic anhydride, and the catalyst bulk density was 0.74g / cm3 with a specific surface area of 28.5 m 2 / g, the pore volume of the catalyst was 0.14 cm 3 / g, and the lateral impact strength was 35 N. The obtained catalyst was packed into a single tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0152] Comparative Example 2

[0153] Except that 46 g of graphite was added as a lubricant and reinforcing agent after the catalyst precursor was calcined in air at 250°C, the other steps were the same as in Example 2, and the catalyst bulk density was 0.73 g / cm 3 with a specific surface area of 28.7 m 2 / g, the pore volume of the catalyst was 0.15 cm 3 / g, and the lateral impact strength was 28 N. The obtained catalyst was packed into a single tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0154] Example 3

[0155] In a 3 L round bottom flask, 960 mL of ethanol, 30 g of methyl ethanolamine, 60 g of amino silane coupling agent, and 600 g of a 10 wt% sodium silicate solution were added and mixed uniformly. A copper sulfate aqueous solution was added at 50°C, and the molar ratio of copper sulfate to sodium silicate was controlled to be 1:6. The mixture was stirred at 50°C for 1 h, and then precipitated and filtered to obtain copper silicate. The copper silicate particles obtained by the above steps were repeatedly washed with anhydrous ethanol for 3 times until the pH of the washing solution was 7-8. The washed nano copper silicate particles were dried in an oven at 80°C for 10 h to obtain surface amino-modified nano copper hydroxyl silicate particles with a particle size of 100-200 nm.

[0156] In a 20 L double-layer glass reactor, 636 g of V2O5, 283 g of oxalic acid, 6750 mL of a mixed solution of isobutyl alcohol and 750 mL of benzyl alcohol, and 12 g of surface amino-modified nano copper hydroxyl silicate particles were added, heated to 120°C, and stirred for 2 h. 815 g of 105 wt% phosphoric acid was added dropwise, and the mixture was heated to 130°C and stirred for 16 h. The molar ratio of V / P was 1 / 1.25. The obtained precipitate was centrifuged and washed with anhydrous ethanol, and then dried at 120°C for 12 h. 82 g of graphite was added to the dried catalyst precursor powder 1160 g, and the mixture was uniformly mixed and heated in air at 250°C for 5 h. The powder was then pressed into a cylindrical structure with a height of 3 mm and a diameter of 13 mm. The density of the structure was 1.18 g / cm 3 . The obtained catalyst precursor structure was heated to 400°C at a heating rate of 2.5°C / min in an air atmosphere, and then the atmosphere was changed to a mixed gas atmosphere of 50% water vapor and 50% air, and maintained for 6 h. The space velocity was 1500 h -1The catalyst was activated under the following conditions: the temperature was raised to 424°C at a rate of 3°C / min, and the catalyst was kept at this temperature for 1.5 h. Then, the atmosphere was changed to 100% nitrogen, and the catalyst was calcined for another 6 h under this atmosphere. After that, the catalyst was cooled to room temperature under nitrogen protection. The activated vanadium-phosphorus-oxygen catalyst was obtained. The catalyst was broken into pieces several times to obtain 1115 g of catalyst substrate powder. The catalyst substrate powder was mixed with 1,1,1-trishydroxymethylethane in a mass ratio of 8 / 92, and then 27 g of methyl cellulose was added thereto. The mixture was mixed uniformly, and then 300 mL of an aqueous solution containing 5 g of methyl cellulose was slowly added to the mixture. The mixture was mixed into a clay-like substance by using a mixer, and then the clay-like substance was extruded into a hollow cylinder-shaped catalyst with a cross section in the shape of a four-petal flower. The extruded substance was cut into particles with an outer diameter of 6 mm, a height of 5 mm, and an inner diameter of 2 mm by using a roll mill. The particles were dried at 120°C for 24 h, and then were soaked in acetone for 15 h (catalyst bulk volume / solvent volume = 1 / 2). The obtained catalyst structure was dried at 60°C and 10 3 Pa for 6 h, and then was calcined at 400°C under nitrogen protection for 6 h to remove the binder. Thus, a vanadium-phosphorus-oxygen catalyst for the oxidation of n-butane to maleic anhydride was obtained. The bulk density of the catalyst was 0.72 g / cm 3 , the specific surface area of the catalyst was 25.7 m 2 / g, the pore volume of the catalyst was 0.17 cm 3 / g, and the lateral impact strength of the catalyst was 25 N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0157] Comparative Example 3

[0158] Except that the surface-amino-modified nano-hydroxyl copper silicate particles were not added, the other steps were the same as in Example 3. The bulk density of the catalyst was 0.72 g / cm 3 , the specific surface area of the catalyst was 27.2 m 2 / g, the pore volume of the catalyst was 0.14 cm 3 / g, and the lateral impact strength of the catalyst was 19 N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0159] Example 4

[0160] In a 20L double layer glass reactor, 636g of V2O5, 308g of vitamin C, 6750ml of isobutyl alcohol and 750ml of benzyl alcohol were added, and the mixture was heated to 130°C and stirred for 2h under reflux. 913g of 105wt% phosphoric acid was added dropwise, and 84g of commercially available hydroxyl aluminum silicate powder (with a particle size of 800-1000nm) was added. The mixture was heated to 130°C and stirred for 16h under reflux. The V / P molar ratio was 1 / 1.4. The obtained precipitate was centrifuged and washed with anhydrous ethanol, and then dried at 150°C for 12h. 12g of graphite was added to the dried catalyst precursor powder 1195g, and the mixture was heated at 250°C in air for 5h. The powder was then pressed into a cylindrical structure with a height of 3mm and a diameter of 5mm. The density of the structure was 1.36g / cm 3 . The obtained catalyst precursor structure was heated to 375°C at a heating rate of 6°C / min in an air atmosphere, and then the atmosphere was changed to a mixed atmosphere of 50% water vapor and 50% air, and maintained for 0.5h. The temperature was raised to 417°C at a heating rate of 4°C / min under an air speed of 1500h -1 . The atmosphere was changed to 100% nitrogen, and the calcination was continued for 6h. The activated vanadium-phosphorus-oxygen catalyst was obtained after cooling to room temperature under nitrogen protection. The catalyst was broken into pieces several times to obtain 1142g of catalyst matrix powder. The catalyst matrix powder was mixed with 1,1,1-trishydroxymethylethane in a mass ratio of 10 / 90, and then sieved and mixed uniformly. 27g of methyl cellulose was added to the mixture, and then mixed uniformly. A water solution of 5g of methyl cellulose in 300ml of water was slowly added to the mixed powder, and the mixture was mixed into a clay-like substance using a mixing machine. The clay-like substance was extruded into a hollow cylinder with a five-petal flower-shaped cross section to form a catalyst. The extruded material was cut into a granular shape with an outer diameter of 6mm, a height of 5mm, and an inner diameter of 2mm on a roll mill. The granular catalyst was dried at 120°C for 24h, and then soaked in acetone for 15h (catalyst bulk volume / solvent volume=1 / 1.5). The obtained catalyst structure was dried at 60°C and 10 3 Pa for 6h. The dried catalyst was calcined at 420°C under nitrogen protection for 6h to remove the binder, and a vanadium-phosphorus-oxygen catalyst for the oxidation of n-butane to maleic anhydride was obtained. The bulk density of the catalyst was 0.76g / cm 3 , the specific surface area was 31.0m 2 / g, the pore volume was 0.17cm 3 / g, and the lateral impact strength was 44N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0161] Comparative Example 4

[0162] The other steps are the same as in Example 4, the catalyst bulk density is 0.71 g / cm 3 , the specific surface area of the catalyst is 29.6 m 2 / g, the pore volume of the catalyst is 0.12 cm 3 / g, and the lateral impact strength is 20 N. The obtained catalyst is packed into a single-tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0163] Example 5

[0164] In a 20 L double-layer glass reactor, 636 g of V2O5, 308 g of vitamin C, 6750 mL of a mixed solution of isobutyl alcohol and 750 mL of benzyl alcohol are added, heated to 140°C and stirred to reflux for 3 hours, 783 g of 105 wt% phosphoric acid is added dropwise, and 47 g of commercially available hydroxyl magnesium silicate particles (with a particle size of about 1000 nm) are added, heated to 140°C and stirred to reflux for 10 h, the V / P feed molar ratio is 1 / 1.2, the obtained precipitate is centrifuged and washed with anhydrous ethanol, and then dried at 120°C for 12 h. The dried catalyst precursor powder is heated in air at 250°C for 5 h, and then the powder is pressed into a cylindrical structure with a height of 3 mm and a diameter of 6 mm, the density of the structure is 1.29 g / cm 3 , the obtained catalyst precursor structure is heated to 265°C at a heating rate of 1°C / min in an air atmosphere, then the atmosphere is changed to a mixed atmosphere of 50% water vapor and 50% air, and kept for 3 h, and then heated to a catalyst surface temperature of 435°C at a heating rate of 4°C / min, and kept for 1 h under this condition, then the atmosphere is changed to 100% nitrogen, and the calcination is continued for 6 h under this atmosphere, and then cooled to room temperature under nitrogen protection, to obtain the activated vanadium-phosphorus-oxygen catalyst. The catalyst is broken into pieces several times, and then mixed with 1,1,1-trishydroxymethylethane in a mass ratio of 12 / 88 to the mass of the catalyst substrate powder, and then sieved and mixed uniformly, and then pressed into a hollow cylinder with a ring-shaped cross section to form a shaped catalyst, the outer diameter of the shaped catalyst structure is 6 mm, the height is 5 mm, and the inner diameter is 2 mm. After soaking in acetone for 21 hours (catalyst bulk volume / solvent volume = 1 / 2), the obtained catalyst structure is dried for 4 h under vacuum at 60°C and a vacuum pressure of 10 2 Pa, to obtain a vanadium-phosphorus-oxygen catalyst for the oxidation of n-butane to maleic anhydride, the catalyst bulk density is 0.75 g / cm 3 , the specific surface area of the catalyst is 31.8 m 2 / g, the pore volume of the catalyst is 0.20 cm 3 / g, and the lateral impact strength is 39 N. The obtained catalyst is packed into a single-tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0165] Comparative Example 5

[0166] Except for the absence of a pore-expanding agent to expand the pores of the catalyst, the other implementation steps were the same as in Example 5, and the catalyst bulk density was 0.82 g / cm³. 3 Its specific surface area is 10.5 m². 2 / g, the catalyst has a pore volume of 0.11cm. 3 / g, with a lateral impact strength of 42N. The obtained catalyst was loaded into a single-tube fixed-bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0167] Example 6

[0168] A mixed solution of 636 g V₂O₅, 283 g oxalic acid, 6750 mL isobutanol, and 750 mL benzyl alcohol was added to a 20 L double-walled glass reactor. The mixture was heated to 100 °C and reacted for 3 h. Then, 750 g of 105 wt% phosphoric acid was added dropwise, and the mixture was heated to 140 °C and refluxed with stirring for 16 h. The V / P molar ratio was 1 / 1.15. The resulting precipitate was centrifuged, washed with anhydrous ethanol, and dried at 150 °C for 12 h. The dried catalyst precursor powder was heated in air at 250 °C for 5 h, and then pressed into a cylindrical structure with a height of 3 mm and a diameter of 10 mm. The density of this structure was 1.02 g / cm³. 3 The obtained catalyst precursor structure was heated to 405°C in air at a heating rate of 2°C / min, and then the atmosphere was replaced with a mixture of 75% water vapor and 25% air, and maintained for 1 h at a space velocity of 1500 h⁻¹. -1 Under the following operating conditions, the catalyst surface temperature was increased to 435°C at a heating rate of 4°C / min. This temperature was maintained for 1.5 hours, then the atmosphere was replaced with 100% nitrogen, and calcination continued for 6 hours. Subsequently, the temperature was lowered to room temperature under nitrogen protection, yielding 1058g of activated vanadium-phosphorus-oxygen catalyst. This catalyst was repeatedly crushed, and 33g of commercially available magnesium hydroxysilicate particles and 33g of graphite were added. 1,1,1-trimethylolethane (10 / 90 mass ratio to catalyst matrix powder) was added, sieved, and mixed thoroughly. The mixture was then pressed into a hollow cylindrical catalyst with a ring-shaped cross-section. The outer diameter of this catalyst structure was 5mm, the height was 5mm, and the inner diameter was 2mm. After soaking in acetone for 24 hours (catalyst volume / solvent volume = 1 / 1.5), the resulting catalyst structure was further calcined at 60°C and 10... 3 After drying under vacuum pressure of Pa for 6 hours, a vanadium-phosphorus-oxygen catalyst for the oxidation of n-butane to maleic anhydride was obtained, with a bulk density of 0.75 g / cm³. 3 Its specific surface area is 32.6 m². 2 / g, the catalyst has a pore volume of 0.15cm³. 3 / g, and the lateral impact strength was 35 N. The obtained catalyst was packed into a single-tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0169] Comparative Example 6

[0170] Except that no commercially available magnesium hydroxylsilicate particles were added to the catalyst substrate powder during the molding process, the other implementation steps were the same as in Example 6, and the catalyst bulk density was 0.74 g / cm 3 , the specific surface area was 32.3 m 2 / g, and the pore volume of the catalyst was 0.15 cm 3 / g, and the lateral impact strength was 31 N. The obtained catalyst was packed into a single-tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0171] Example 7

[0172] In a 20 L double-layered glass reactor, 636 g of V2O5, 283 g of oxalic acid, 6750 mL of a mixed solution of isobutanol and 750 mL of benzyl alcohol were added, heated to 100°C and reacted for 3 h, 783 g of 105 wt% phosphoric acid was added dropwise, heated to 140°C and stirred under reflux for 12 h, the V / P molar ratio of the raw materials was 1 / 1.2, and the obtained precipitate was centrifuged and washed with anhydrous ethanol, and then dried at 100°C for 20 h. The dried catalyst precursor powder was heated at 300°C in air for 3 h, obtaining 1138 g of catalyst precursor powder, 38 g of commercially available aluminum hydroxylsilicate particles and 19 g of graphite were added, and then the powder was pressed into a cylindrical structure with a height of 3 mm and a diameter of 13 mm, and the bulk density of the structure was 0.82 g / cm 3 , the obtained catalyst precursor structure was heated to 275°C at a heating rate of 2°C / min in an air atmosphere, then the atmosphere was changed to a mixed atmosphere of 75% water vapor and 25% air, and heated to a catalyst surface temperature of 435°C at a heating rate of 4°C / min, and kept for 1.5 h under this condition, then the atmosphere was changed to 100% nitrogen, and the calcination was continued for 5 h under this atmosphere, and then cooled to room temperature under nitrogen protection, obtaining the activated vanadium-phosphorus-oxygen catalyst. The catalyst was broken multiple times, and 1,1,1-trishydroxymethylethane was added and mixed uniformly at a mass ratio of 12 / 88 to the catalyst substrate powder, and then pressed into a hollow cylindrical catalyst with a ring-shaped cross section, the outer diameter of the catalyst structure was 5 mm, the height was 5 mm, and the inner diameter was 2 mm. After soaking in acetone for 24 h (catalyst bulk volume / solvent volume = 1 / 2), the obtained catalyst structure was dried for 4 h under vacuum at 60°C and a vacuum pressure of 10 3 Pa, obtaining the vanadium-phosphorus-oxygen catalyst for the oxidation of n-butane to maleic anhydride, and the catalyst bulk density was 0.75 g / cm 3 , and the specific surface area was 37.3 m2 / g, the pore volume of the catalyst was 0.16 cm 3 / g, the lateral impact strength was 32 N. The obtained catalyst was packed into a single tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0173] Example 8

[0174] Except that 57 g of commercially available hydroxyl aluminum silicate particles were added after the catalyst precursor powder was heated in air at 300°C, the other implementation steps were the same as in Example 7, and the catalyst bulk density was 0.71 g / cm 3 , the specific surface area was 32.8 m 2 / g, the pore volume of the catalyst was 0.15 cm 3 / g, the lateral impact strength was 39 N. The obtained catalyst was packed into a single tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0175] Comparative Example 7

[0176] Except that no hydroxyl silicate and graphite particles were added during the preparation of the catalyst, the other implementation steps were the same as in Example 7, and the catalyst bulk density was 0.68 g / cm 3 , the specific surface area was 27.6 m 2 / g, the pore volume of the catalyst was 0.13 cm 3 / g, the lateral impact strength was 16 N. The obtained catalyst was packed into a single tube fixed bed reactor for evaluation, and the catalytic performance is shown in Table 1.

[0177] Example 9

[0178] The catalysts prepared in Examples 1-7 and Comparative Examples 1-7 were used as selective oxidation catalysts for the oxidation of n-butane to maleic anhydride, and the catalyst performance was tested at a reaction temperature of 390-420°C. The catalytic results were analyzed by online gas chromatography, and the evaluation method used was but not limited to the above conditions.

[0179] Table 1 Catalytic performance of catalysts for selective oxidation of n-butane to maleic anhydride

[0180]

[0181] Any numerical values recited herein include all values from the lower value and up to the upper value. Values that are recited herein also include values that are "framed" by the recited values. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 25%, 30%, and 35% are expressly enumerated. All integer values are used "open ended" such that "50%" really means "50% to 50%". The same principle applies to ranges recited as being "between" two values. Discrete, non-integer values can be assumed within the stated ranges. These are only a few of the specific examples that are given. In the application, all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this application.

[0182] It should be noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present application. While the application has been described with reference to exemplary embodiments, it is understood that the words that have been used herein are words of description, and that they are being used under the descriptive and explanatory privilege intended to aid in the understanding of the application. Modifications can be made to the application in light of the teachings herein, and other steps can be added or deleted thereof without departing from the intended scope of the application. Although the application has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can effect a wide variety of modifications to the preferred embodiments of the application without departing from the scope of the intended application. While the preferred embodiments of the application have been made this description is illustrative and not restrictive. Various modifications can become apparent to those skilled in the art, and the present application is to be limited only by the scope of the appended claims.

Claims

1. A molded catalyst for the selective oxidation of n-butane, comprising an active component and a hydroxysilicate, wherein the active component comprises vanadium phosphorus oxide, and the hydroxysilicate is at least one selected from aluminum hydroxysilicate, magnesium hydroxysilicate, copper hydroxysilicate, and a natural mineral containing hydroxysilicate, wherein the hydroxysilicate comprises 0.1–8 wt% of the molded catalyst; the molded catalyst is prepared by the following steps: S1, adding raw materials, including the active component source, to a liquid solvent for reaction; S2, separating the solid material from the reaction product of step S1, drying it to obtain a catalyst precursor; S3, heat-treating the catalyst precursor, then molding it to obtain a billet, activating the billet, and then crushing it to obtain a matrix powder for the molded catalyst; S4, mixing the matrix powder for the molded catalyst with a pore-expanding agent, molding it again to obtain a catalyst preform, and performing pore-expanding treatment to obtain the molded catalyst, wherein... Hydroxysilicates are added to the raw materials in step S1 and / or the catalyst precursor after heat treatment in step S3 and / or the matrix powder of the shaped catalyst in step S3.

2. The molding catalyst according to claim 1, characterized in that: Optionally, the hydroxysilicate is surface-modified; and / or, The hydroxysilicate is 0.1–5 wt% of the molding catalyst; and / or, The active component includes a metal additive selected from at least one of molybdenum, indium, niobium, bismuth, cobalt, zinc, iron, and tungsten; and / or, The molding catalyst includes a lubricant.

3. The molding catalyst according to claim 2, characterized in that: The lubricant is at least one of graphite, starch, and stearate; The lubricant is 0-10 wt% of the molding catalyst.

4. The molding catalyst according to claim 3, characterized in that: The lubricant is 0-6 wt% of the molding catalyst.

5. The molding catalyst according to any one of claims 1 to 4, characterized in that: The lateral impact strength of the molded catalyst is 10–70 N; and / or, The specific surface area of ​​the shaped catalyst is 5-100 m². 2 / g; and / or, The pore volume of the shaped catalyst is 0.10–0.20 cm³. 3 / g.

6. The molding catalyst according to claim 5, characterized in that: The lateral impact strength of the molded catalyst is 20–60 N; and / or, The specific surface area of ​​the shaped catalyst is 10–70 m². 2 / g; and / or, The pore volume of the shaped catalyst is 0.15–0.20 cm³. 3 / g.

7. A method for preparing a shaped catalyst according to any one of claims 1 to 6, comprising the following steps: S1, raw materials, including the active component source, are added to a liquid solvent for reaction; S2, the solid material in the reaction product of step S1 is separated and dried to obtain the catalyst precursor; S3, the catalyst precursor is heat-treated, then shaped to obtain a billet, and the billet is activated and then crushed to obtain the matrix powder of the shaped catalyst. S4, the matrix powder of the shaped catalyst is mixed with the pore-expanding agent, and after being shaped again, a catalyst preform is obtained. The preform is then subjected to pore-expanding treatment to obtain the shaped catalyst. Hydroxysilicates are added to the raw materials in step S1 and / or the catalyst precursor after heat treatment in step S3 and / or the matrix powder of the shaped catalyst in step S3.

8. The preparation method according to claim 7, characterized in that... Step S1 includes: S1-1) Mix a portion of the active ingredient source with a liquid solvent and heat; S1-2) Add the remaining active ingredient source and continue heating; The active component sources include vanadium-containing compounds, phosphorus-containing compounds, and oxygen-containing compounds; Optionally, a metal additive source is added in step S1-2).

9. The preparation method according to claim 8, characterized in that: In step S1-1), the liquid solvent is an organic alcohol; In step S1-1), the heating temperature is 80-140℃ and the heating time is 0-5h; In steps S1-2), the heating temperature is 100-140℃ and the heating time is 3-24h; When hydroxysilicate is added in step S1-2), the hydroxysilicate is 0.1 to 15 wt% of the vanadium-containing compound.

10. The preparation method according to claim 9, characterized in that: The organic alcohol is at least one of isobutanol, isopropanol, sec-butanol, 2-methylbutanol, cyclohexylethanol, 2-ethyl-1-hexanol, and benzyl alcohol; In step S1-1), the heating temperature is 100-140℃ and the heating time is 3-5 hours; In steps S1-2), the heating temperature is 110-140℃ and the heating time is 3-16h; The hydroxysilicate is 0.15–10 wt% of the vanadium-containing compound.

11. The preparation method according to claim 7, characterized in that: In step S2, the product is dried at 60–150°C for 6–24 hours.

12. The preparation method according to claim 11, characterized in that: Dry at 100-120℃ for 12-24 hours.

13. The preparation method according to claim 7, characterized in that... In step S3: Heat treatment at 120–300℃ for 2–36 hours; The forming process includes pressing the heat-treated catalyst precursor into a billet, the billet having a bulk density of 0.8–1.6 g / cm³. 3 ; The activation process includes placing the catalyst block in an air and / or water vapor and / or nitrogen atmosphere, heating it to 250-420°C at a heating rate of 1-6°C / min, and then maintaining it for 0.5-8 hours with or without changing the atmosphere; continuing to heat it to 400-550°C at a heating rate of 2-6°C / min, and maintaining it for 3-8 hours with or without changing the atmosphere; and then cooling it to room temperature with or without adding inert gas to obtain the activated catalyst block.

14. The preparation method according to claim 13, characterized in that: The bulk density of the billet is 1.0–1.4 g / cm³. 3 .

15. The preparation method according to claim 7, characterized in that... In step S3: When hydroxysilicate is added to the heat-treated catalyst precursor, the hydroxysilicate is 0.05 to 8 wt% of the catalyst precursor; When hydroxysilicate is added to the matrix powder of the shaped catalyst, the hydroxysilicate is 0.1 to 8 wt% of the matrix powder of the shaped catalyst.

16. The preparation method according to claim 15, characterized in that: Hydroxysilicate is 0.1–5 wt% of the catalyst precursor; Hydroxysilicate constitutes 0.1–5 wt% of the shaped catalyst matrix powder.

17. The preparation method according to claim 7, characterized in that... In step S3: The lubricant is added before or after the heat treatment of the catalyst precursor, and the lubricant is 0.1 to 10 wt% of the catalyst precursor. Alternatively, the lubricant is added to the matrix powder of the shaped catalyst, wherein the lubricant is 0.05 to 9 wt% of the matrix powder of the shaped catalyst.

18. The preparation method according to claim 17, characterized in that: The lubricant is 0.1–6 wt% of the catalyst precursor; The lubricant is 0.09 to 5.5 wt% of the matrix powder of the shaped catalyst.

19. The preparation method according to claim 7, characterized in that... In step S4: The pore-expanding agent is 2-25 wt% of the shaped catalyst matrix powder; The pore-expanding agent is selected from at least one of 1,1,1-trimethylolethane, trimethylolpropane, glycolic acid, salicylic acid, malic acid, tartaric acid, and citric acid.

20. The preparation method according to claim 19, characterized in that: The pore-expanding agent is 4-14 wt% of the shaped catalyst matrix powder.

21. The preparation method according to claim 7, characterized in that: In step S4, when using extrusion molding, after mixing the matrix powder and pore expander of the molding catalyst, a binder and water are added before molding.

22. The preparation method according to claim 21, characterized in that: The binder is 1 to 4.5 wt% of the shaped catalyst matrix powder, the binder is 10 to 18 wt% of the added water, and the binder is cellulose and its derivatives.

23. The preparation method according to claim 7, characterized in that: In step S4, the pore enlargement process employs a liquid medium contact method and a depressurized heating extraction method.

24. The preparation method according to claim 23, characterized in that: The liquid medium is selected from organic solvents with a polarity <5; the volume ratio of the liquid medium to the catalyst preform is (1-5):1; and / or, The conditions for the vacuum heating extraction method include: a vacuum degree of 10. 2 ~10 5 Pa, heating temperature <150℃; time 1~24h.

25. The preparation method according to claim 24, characterized in that: The liquid medium is selected from at least one of diethyl ether, petroleum ether, ethyl acetate, acetone, propanol, isobutanol, n-butanol, dichloromethane, and p-xylene; the volume ratio of the liquid medium to the catalyst preform is (1-3):

1.

26. The shaped catalyst obtained by the preparation method according to any one of claims 7 to 25.

27. A method for oxidizing n-butane to maleic anhydride, comprising oxidizing n-butane in the presence of a catalyst, wherein the catalyst is a shaped catalyst according to any one of claims 1 to 6 or a shaped catalyst obtained by the preparation method according to any one of claims 7 to 25.

28. The method for producing maleic anhydride by oxidation of n-butane according to claim 27, characterized in that: The reaction temperature is 370–430℃; the pressure is 0.01–0.2 MPa; and the total space velocity of the reactant mixture is 800–2500 h⁻¹. -1 The volume fraction of n-butane is 1.5–2.0%.

29. The method for producing maleic anhydride by oxidation of n-butane according to claim 28, characterized in that: The reaction temperature is 390–420℃; the total space velocity of the reactant mixture is 1000–2200 h⁻¹. -1 .

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