CN110935479A - Catalyst for preparing maleic anhydride by n-butane oxidation and preparation method thereof - Google Patents
Catalyst for preparing maleic anhydride by n-butane oxidation and preparation method thereof Download PDFInfo
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- B01J27/14—Phosphorus; Compounds thereof
- B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J27/195—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with vanadium, niobium or tantalum
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Abstract
The invention discloses a preparation method of a catalyst for preparing maleic anhydride by oxidizing n-butane, which comprises the following steps: step S1, adding a vanadium source, a phosphorus source and a template agent into a liquid medium for reaction to prepare a maleic anhydride catalyst precursor through oxidation of n-butane, wherein the template agent is selected from one or more of polyethylene glycol oleate, alkylphenol ethoxylates and fatty alcohol polyoxyethylene ethers; and an optional step S2 of activating the catalyst precursor for preparing maleic anhydride by n-butane oxidation. The catalyst provided by the method is used in the catalytic reaction of preparing maleic anhydride by n-butane oxidation, and has high n-butane conversion rate and good maleic anhydride selectivity.
Description
Technical Field
The invention belongs to the field of catalyst synthesis, and particularly relates to a catalyst for preparing maleic anhydride by n-butane oxidation and a preparation method thereof.
Background
Maleic anhydride (maleic anhydride) is an important organic chemical raw material and a fine chemical product, is the third largest anhydride which is only second to phthalic anhydride and acetic anhydride in the world at present, is mainly used for producing thermosetting resin and unsaturated polyester resin, and is used in the fields of pesticides, medicines, coatings, printing ink, lubricating oil additives, papermaking chemicals, textile finishing agents, food additives, surfactants and the like. In addition, a series of widely used fine chemical products such as 1, 4-butanediol (GBL), Tetrahydrofuran (THF), maleic acid, fumaric acid, tetrahydrochysene anhydride and the like can be produced by using maleic anhydride as a raw material, the development and utilization prospects are very wide, and the application range of the maleic anhydride is continuously expanded at present.
The maleic anhydride production process mainly comprises a benzene catalytic oxidation method, an n-butane catalytic oxidation method and C4Olefin catalytic oxidation method and phthalic anhydride by-product method. In recent years, a process for producing maleic anhydride from low-cost carbon four-fraction (n-butane) as a raw material worldwide has become an absolute mainstream of maleic anhydride production. Since 2011, the conversion of the benzene oxidation method to the butane oxidation method is increasingly obvious, and the yield and the operating rate of the domestic device for preparing the maleic anhydride by the n-butane oxidation method exceed those of the benzene oxidation method. These factors greatly stimulate the demand of domestic enterprises for preparing the vanadium phosphorus oxide catalyst for preparing the maleic anhydride by the butane method.
Vanadium Phosphorus Oxide (VPO) catalysts are the most widely used industrial catalysts for the oxidation of n-butane to maleic anhydride. The surface property of the catalyst, the addition of the auxiliary agent, the activation method of the catalyst and the like all have obvious influence on the performance of the catalyst. Although the current production route using n-butane as a raw material dominates the production of maleic anhydride, the current catalyst for preparing maleic anhydride by oxidizing n-butane needs to further improve the activity and selectivity and increase the yield of maleic anhydride.
Disclosure of Invention
The invention aims to solve the technical problem of the prior art and provides a vanadium-phosphorus-oxygen catalyst for preparing maleic anhydride by oxidizing n-butane and a preparation method thereof. The catalyst provided by the method is used in the catalytic reaction of preparing maleic anhydride by oxidizing n-butane, and has high n-butane conversion rate and good maleic anhydride selectivity. The invention has simple process, lower cost and easy realization.
Therefore, the invention provides a preparation method of a catalyst for preparing maleic anhydride by n-butane oxidation, which comprises the following steps:
step S1, adding a vanadium source, a phosphorus source and a template agent into a liquid medium for reaction to prepare a maleic anhydride catalyst precursor through oxidation of n-butane, wherein the template agent is selected from one or more of polyethylene glycol oleate, alkylphenol ethoxylates and fatty alcohol polyoxyethylene ethers; wherein the molar ratio of the template agent to the vanadium element is 0.005-0.5, preferably 0.005-0.25;
and an optional step S2 of activating the catalyst precursor for preparing maleic anhydride by n-butane oxidation.
The second aspect of the invention provides a preparation method of a catalyst for preparing maleic anhydride by oxidizing n-butane, which comprises the following steps:
step A, adding a vanadium source into a liquid medium, heating and refluxing for reaction to obtain a first reaction system;
b, adding a phosphorus source, a template agent and an optional auxiliary agent into the first reaction system, and continuously heating and refluxing for reaction to obtain a second reaction system; preferably, the reaction system in the step A is cooled to 25-80 ℃, preferably 25-60 ℃, and then a phosphorus source, a template agent and an optional auxiliary agent are added;
step C, carrying out solid-liquid separation treatment on the second reaction system, and washing and drying the obtained precipitate to obtain a catalyst precursor;
and D, optionally activating the catalyst precursor.
According to the embodiment of the invention, a specific nonionic surfactant organic template agent is added in the preparation process of the catalyst precursor, so that the morphology and the specific surface area of precursor crystal grains are changed, the specific surface area of the activated catalyst is controlled and improved, and the activity of the catalyst in the selective oxidation reaction of catalytic butane and the selectivity of generating maleic anhydride are further improved. The inventor also finds that the change of the specific surface area of the precursor has important influence on the aspects of improving the activity of the catalyst, the butane conversion rate, the maleic anhydride selectivity and the like, the topological transformation of catalyst grains is realized in the activation process, the catalyst precursor with larger specific surface area has obvious influence on the specific surface area of the activated catalyst, and the specific surface area of the catalyst precursor is 5-50m2(ii)/g; preferably 20-40m2The catalyst precursor is preferably in the shape of a rose-shaped structure formed by aggregation of bent sheet-shaped laminates.
According to some preferred embodiments of the present invention, there is no particular limitation on the order of adding the phosphorous source and the templating agent, and the phosphorous source may be added first, the templating agent may be added first, the phosphorous source may be added first, or the templating agent may be added simultaneously, preferably the templating agent is added first and the phosphorous source is added later.
According to some preferred embodiments of the present invention, the template agent is selected from one or more of polyethylene glycol oleate, alkylphenol polyoxyethylene and fatty alcohol polyoxyethylene; preferably one or more selected from PEG-MO, PEG-DO series polyethylene glycol oleate, OP, TX series alkylphenol polyoxyethylene ether and AEO, MOA series fatty alcohol polyoxyethylene ether; more preferably from one or more of polyethylene glycol dioleate, polyoxyethylene ether of octylphenol, and polyoxyethylene ether of AEO 3.
According to some embodiments of the present invention, the templating agent suitable for use in the present invention is preferably a compound of PEG-MO, PEG-DO series polyethylene glycol oleate, OP, TX series alkylphenol ethoxylates, AEO, MOA series fatty alcohol ethoxylates. Polyoxyethylene ether of OP octyl phenol, AEO3 polyoxyethylene ether are preferred. The appearance of a catalyst precursor is changed by adding a specific type of nonionic surfactant as a template agent in the preparation process of the catalyst, so that the specific surface area of the activated catalyst is further improved.
According to some preferred embodiments of the present invention, the molar ratio of the vanadium source and the phosphorus source, calculated as elements, is 1 (0.8-4), preferably 1 (0.9-2), further preferably 1 (1-1.4), more preferably 1 (1.1-1.2); wherein the vanadium source is selected from one or more of vanadium oxide, vanadate and organic acid vanadium, and vanadium pentoxide is preferred; and/or the source of phosphorus comprises phosphoric acid and/or phosphorus pentoxide, preferably phosphoric acid, more preferably 85-105 wt% phosphoric acid.
According to some embodiments of the present invention, the feeding amounts of the vanadium element and the phosphorus element have important effects on the aspects of improving the activity of the catalyst and the selectivity of the maleic anhydride.
According to some preferred embodiments of the present invention, the liquid medium comprises an alcoholic solvent, preferably a mixed solvent of isobutanol and benzyl alcohol, more preferably the molar ratio of the isobutanol to the benzyl alcohol is (100-85): 0-15.
According to some preferred embodiments of the invention, the adjuvant is selected from one or more of indium, niobium, bismuth, cobalt, zinc, iron and tungsten; preferably, the molar ratio of the auxiliary agent to the vanadium element is (1-5): 100-300), preferably (2-3): 150-200).
According to some preferred embodiments of the present invention, in the research process, the inventors found that the performance of the catalyst can be significantly improved by adding the metal element as an auxiliary agent, and specifically, the activity and the selectivity of the generated maleic anhydride can be significantly improved, thereby improving the yield of the maleic anhydride. The effect is particularly remarkable when the tungsten element is added as an auxiliary metal element. In some preferred embodiments, under the same operation conditions, the conversion rate of butane is improved by 1.5-6.3% and the yield of maleic anhydride is improved by 1.5-9.5% compared with the catalyst without the tungsten element addition agent. When indium element is added as an additive metal element. Under the same operation condition, compared with the catalyst without the indium element addition agent, the conversion rate of butane is improved by 3.4-7.4%, and the yield of maleic anhydride is improved by 4.5-7.7%. When bismuth element is added as an additive metal element. Under the same operation condition, compared with the catalyst without the bismuth element addition agent, the selectivity of the generated maleic anhydride is improved by 4.5-6.8 percent, and the yield of the maleic anhydride is improved by 4.5-9.5 percent. When the niobium element is added as an additive metal element. Under the same operation condition, compared with the catalyst without the niobium element addition agent, the conversion rate of butane is improved by 3.5-6.3%, and the yield of maleic anhydride is improved by 2.8-6.1%.
According to some preferred embodiments of the present invention, by controlling the morphology of the catalyst precursor, the conversion of butane can be increased by 0 to 17%, such as 16.7%, the selectivity of the formation of maleic anhydride can be increased by 0 to 9%, such as 8.3%, and the molar yield of maleic anhydride can be increased by 0 to 13%, such as 12.3%, under the same operating conditions, while further promoting with a metal promoter.
According to some preferred embodiments of the present invention, specific substances of the auxiliary are not particularly limited, and a compound containing the above-mentioned auxiliary metal element may be selected, and for example, a metal salt or a metal oxide of the auxiliary metal element may be selected. In some specific embodiments, the promoter metal element species may be a carboxylate, nitrate, phosphate, oxide or chloride of the promoter metal element, preferably a nitrate, phosphate or oxide of the promoter metal element.
According to some preferred embodiments of the present invention, in step A, the reaction time is 0 to 5 hours, preferably 3 to 5 hours.
According to some preferred embodiments of the present invention, in step B, the reaction time is 3 to 24 hours, preferably 5 to 16 hours.
According to some preferred embodiments of the invention, in step C, the solid-liquid separation treatment is filtration or centrifugation; and/or the washing treatment is carried out in an alcohol solvent, preferably absolute ethyl alcohol; and/or the drying treatment is drying at 60-150 ℃, preferably 120 ℃, for 6-24h, preferably 12 h.
According to some preferred embodiments of the present invention, in step D, the catalyst precursor is placed in an air/butane atmosphere, heated to 380-; preferably, the catalyst precursor is placed in an air/butane atmosphere with an air/butane volume ratio of 98/2-99/1, preferably 98.2/1.8, and a space velocity of 500h-1-2000h-1Preferably 1000h-1Raising the temperature to 380 ℃ at the temperature raising rate of 2-4 ℃/min, keeping the temperature for 0-6h, preferably 3-6h, keeping the volume ratio of air/butane unchanged, and raising the space velocity to 1500h-1-2500h-1Preferably 2000h-1Raising the temperature to 400-430 ℃, preferably 420 ℃ at the speed of 4-6 ℃/min, keeping the temperature for 0-18h, and then reducing the temperature to room temperature in a nitrogen atmosphere to obtain the activated catalyst.
The invention also provides a catalyst prepared by the method, which comprises 20-30% by mass of vanadium, preferably 21-26% by mass of vanadium, 15-25% by mass of phosphorus, preferably 15-19% by mass of vanadium, phosphorus, oxygen and optional auxiliaries; and/or the molar ratio of the vanadium element to the phosphorus element on the surface of the catalyst is 1 (0.8-4), preferably 1 (1.5-3), and more preferably 1 (2-3).
In some preferred embodiments according to the invention, the vanadium and phosphorus in the catalyst are predominantly in the form of (VO)2P2O7Exists in the form of (1); preferably, the (VO)2P2O7Is a precursor VO (HPO) prepared by a liquid phase method in an organic solvent4)2·0.5H2O is obtained after activation in a certain atmosphere. In addition, the molar ratio of the vanadium element to the phosphorus element on the surface of the activated catalyst has important influence on the aspects of improving the activity of the catalyst, generating the selectivity of the maleic anhydride and the like.
In a further aspect, the present invention provides a use of n-butane to prepare maleic anhydride by oxidation, comprising subjecting n-butane to oxidation reaction in the presence of the catalyst prepared by the above method and the above catalyst for preparing maleic anhydride by oxidation of n-butane.
The catalyst prepared by the method has good reaction effect in preparing maleic anhydride by catalyzing butane oxidation, and the yield of the maleic anhydride is high. At the reaction temperature of 400 ℃ and the space velocity of 1500h-1Under the condition that the butane concentration is 1.8 percent, the butane conversion rate can reach 85.4 percent, the yield of the maleic anhydride is 62.4 percent, and the selectivity of the generated maleic anhydride is 73.5 percent; under the same conditions, the vanadium-phosphorus-oxygen catalyst without the template agent added in the precursor preparation process has the catalytic performance that the butane conversion rate is 76.9 percent, the yield of the maleic anhydride is 50.1 percent, the selectivity of the generated maleic anhydride is 65.2 percent, and better technical effects are obtained.
Drawings
FIG. 1 shows XRD spectra of a vanadium phosphorus oxide catalyst precursor without a templating agent added (a: comparative example 1) and a vanadium phosphorus oxide catalyst precursor with a templating agent added (b-g: examples 1-6) in some examples of the present invention.
FIG. 2 is an SEM image of an vanadium phosphorus oxide catalyst precursor without a templating agent added (a, h: comparative examples 1, 2) and a vanadium phosphorus oxide catalyst precursor with a templating agent added (b-g, i: examples 1-6) in some examples of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention easier to understand, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. The specific experimental methods not mentioned in the following examples are generally carried out according to conventional experimental methods.
In the present invention, the raw materials used in the examples are commercially available unless otherwise specified.
In the invention, the AEO (MOA) series fatty alcohol-polyoxyethylene ether has a general formula C12-14H25-29O (CH2CH2O)nH。
According to the invention, the morphology of the catalyst precursor is found through researchThe specific surface area of the catalyst is greatly influenced, and the catalytic performance of the catalyst after activation is further influenced. VPO catalyst from precursor phase VOHPO4·0.5H2O to the major active phase (VO)2P2O7The topological transformation occurs in the transformation process, and the original flaky precursor crystal grains are broken, so that the size of the crystal grains after the catalyst is activated and the exposed crystal faces of the crystal grains are greatly influenced by the morphology of the catalyst precursor particles, and the activity of the final catalyst and the selectivity of the generated product are further influenced.
According to the invention, the inventor unexpectedly discovers through research that: the surfactant molecular aggregate is used as a template, and the tailoring of the material structure can be realized through an interface assembly process between the surfactant molecular aggregate and an inorganic species. Various types of surfactants can be used as templating agents. Since surfactants can form micelles of various shapes, sizes and properties under appropriate conditions, the micelles of these different properties allow the structure of the final material to exhibit diversity. Wherein the specific kind of template agent is a surfactant which does not generate ions in an aqueous solution. The template agent does not exist in an ionic state in a solution, has good solubility in various solvents, is an amphiphilic structure molecule taking hydroxyl (-OH) or ether bond (R-O-R') as a hydrophilic group, and has certain hydrophilicity only by containing a plurality of groups because the hydrophilicity of the hydroxyl and the ether bond is weak, which is different from anionic and cationic surfactants which can exert the hydrophilicity only by one hydrophilic group. The template agent has good solubility in organic solvent, high stability in solution and is not easily affected by strong electrolyte inorganic salt, acid and alkali. Meanwhile, the template agent does not strongly adsorb on the surface of the material particles and can be well removed from the crystal grain cluster. The template agent utilizes the hydrogen bond effect to connect the surfactant and the inorganic precursor crystal nucleus, is favorable for controlling the growth of precursor particles through the interface effect, and further influences the appearance and the size of the inorganic precursor particles, thereby achieving the aim of promoting the catalytic performance of the catalyst by changing the specific surface area. The two hydrophilic groups of ether group and hydroxyl group in the molecule can be well matched with hemihydrateVOHPO4·0.5H2Water molecules on the O are hydrophilic and adsorbed on the surfaces of the dispersed particles to form a macromolecular hydrophilic film, so that a steric hindrance effect is generated, and the template agent with larger steric hindrance and good mutual solubility can reduce the agglomeration phenomenon of the product. During the subsequent refluxing process, the oriented crystallization makes the grain size to be kept small and the specific surface area of the product to be relatively large.
In some preferred embodiments of the present invention, the crystal phase detection is performed by using an X-ray diffractometer from parnacho, netherlands, and the specific surface area is determined by using a full-automatic specific surface area and pore size distributor from ASAP-2020, Quantachrome, usa, and the scanning electron microscope image is obtained on a Hitachi S-4800 cold field emission scanning electron microscope, and the acceleration voltage is 30 kV.
Example 1
A500 mL round bottom flask was charged with 5.0g V2O570mL of a mixed solution of isobutanol and 10mL of benzyl alcohol, heating and stirring the mixed solution until the mixed solution is refluxed for 3 hours, adding 6mL of octylphenol polyoxyethylene ether (OP-4) into the mixed solution, wherein the molar ratio of the template to vanadium is 0.14, adding 0.22g of tungsten chloride, continuously dropwise adding 7.6g of 85 wt% phosphoric acid, heating and stirring the mixed solution until the mixed solution is refluxed for 16 hours, centrifuging the obtained precipitate, washing the precipitate with 200mL of absolute ethyl alcohol for three times, and drying the precipitate at 120 ℃ for 12 hours. Pressing the dried catalyst precursor powder into a cylindrical structure with the height of 2mm and the diameter of 13mm, crushing the cylindrical structure into particles with the size of 20-40 meshes, and placing the particles in an air/butane atmosphere (the volume ratio of air to butane is 98.2/1.8, and the space velocity condition is 1000h-1) Heating to 380 deg.C at a heating rate of 2 deg.C/min, maintaining for 3 hr, maintaining the air/butane volume ratio, and increasing the space velocity to 2000 hr-1And continuously heating the temperature to 420 ℃ at the heating rate of 4 ℃/min, keeping the temperature for 5 hours under the condition, and then cooling the temperature to room temperature under the protection of nitrogen to obtain the activated vanadium-phosphorus-oxygen catalyst. The specific surface area of the catalyst precursor is 49.5m2The precursor morphology is a rose-shaped structure formed by aggregation of bent sheet-shaped laminates (figure 2e), and the thickness of the sheet layer is about 10nm (figure 2 i). The obtained catalyst was evaluated in a fixed bed microreactor with 1.8% butane feed for 1500h-1Is empty ofAt 400 deg.c, the catalyst conversion rate reaches 85.4%, the selectivity of maleic anhydride is 73.5% and the yield of maleic anhydride is 62.4%. 1.5% butane feed, 2000h-1At 400 ℃, the catalyst conversion rate reaches 83.4%, the maleic anhydride selectivity is 74.7%, and the yield of the maleic anhydride is 62.3%.
Comparative example 1
The procedure was as in example 1 except that OP-4 was not added as a templating agent. The specific surface area of the obtained catalyst precursor was 12.9m2The morphology of the precursor is a sheet structure close to a rhombus (figure 2 a). The obtained catalyst is evaluated by a fixed bed microreactor, 1.8 percent of butane is fed, and 1500 hours are carried out-1At 400 ℃, the catalyst conversion rate is 76.9%, the maleic anhydride selectivity is 65.2%, and the maleic anhydride yield is 50.1%.
Example 2
A500 mL round bottom flask was charged with 5.0g V2O570mL of a mixed solution of isobutanol and 10mL of benzyl alcohol, heating and stirring to reflux for 3 hours, adding 10mL of OP-10 to the mixed solution, wherein the molar ratio of the template to vanadium is 0.25, adding 0.08g of indium oxide, continuously dropwise adding 7.6g of 85 wt% phosphoric acid, heating and stirring to reflux for 16 hours, centrifuging the obtained precipitate, washing the precipitate with 200mL of absolute ethyl alcohol for three times, and drying the precipitate at 120 ℃ for 12 hours. Pressing the dried catalyst precursor powder into a cylindrical structure with the height of 2mm and the diameter of 13mm, crushing the cylindrical structure into particles with the size of 20-40 meshes, and placing the particles in an air/butane atmosphere (the volume ratio of air/butane is 98.2/1.8, and the space velocity condition is 1000h-1) Raising the temperature to 380 ℃ at the temperature raising rate of 2.5 ℃/min, keeping the temperature for 0h under the condition, keeping the volume ratio of air/butane unchanged, and raising the space velocity to 2000h-1And continuously heating the temperature to 420 ℃ at the heating rate of 6 ℃/min, keeping the temperature for 8 hours under the condition, and then cooling to room temperature under the protection of nitrogen to obtain the activated vanadium-phosphorus-oxygen catalyst. The specific surface area of the catalyst precursor was 37.4 m2The morphology is that of aggregates composed of bent sheet-like structures (as shown in FIG. 2 e). The obtained catalyst was evaluated in a fixed bed microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the conversion rate of the catalyst reachesTo 83.7 percent, the selectivity of the maleic anhydride is 68.4 percent, and the yield of the maleic anhydride is 57.3 percent.
Comparative example 2
The procedure was as in example 2 except that no templating agent OP-10 was added. The specific surface area of the obtained catalyst precursor was 16.2m2(ii)/g, the morphology is a flat sheet structure with a sheet thickness greater than 50nm (as shown in FIG. 2 h). The obtained catalyst was evaluated by a mini fixed bed reactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate is 81.1%, the maleic anhydride selectivity is 61.9%, and the maleic anhydride yield is 50.2%.
Example 3
84.7g V was added to a 3L round bottom flask2O5800mL of a mixed solution of isobutanol and 200mL of benzyl alcohol, heated under stirring to reflux for 3 hours, to which was added 10.0g of polyethylene glycol dioleate (PEG200DO) in a molar ratio of the template to vanadium of 0.05, 2.92g of bismuth phosphate, 86.7g of 105 wt% phosphoric acid was added dropwise and heated under stirring to reflux for 12 hours, and the resulting precipitate was dried at 120 ℃ for 12 hours after centrifugation and washing with absolute ethanol. Pressing the dried catalyst precursor powder into a cylindrical structure with the height of 4mm and the diameter of 13mm, crushing the cylindrical structure into particles with the size of 20-40 meshes, and then putting the cylindrical structure in an air/butane atmosphere (the volume ratio of air/butane is 98.2/1.8, and the space velocity condition is 1000h-1) Heating to 380 deg.C at a heating rate of 4 deg.C/min, maintaining for 6h, maintaining the air/butane volume ratio, and increasing the space velocity to 2000h-1And continuously heating the temperature to 420 ℃ at the heating rate of 6 ℃/min, keeping the temperature for 18h under the condition, and then cooling the temperature to room temperature under the protection of nitrogen to obtain the activated vanadium-phosphorus-oxygen catalyst. The morphology of the catalyst precursor is a cluster-like aggregate with irregular lamellar aggregation (as shown in figure 2f), and the specific surface area of the catalyst precursor is 28.3m2(ii) in terms of/g. The obtained catalyst was evaluated by a mini fixed bed reactor with 1.8% butane feed for 1500h-1At 410 ℃, the catalyst conversion rate reaches 78.9%, the maleic anhydride selectivity is 68.3%, and the maleic anhydride yield is 53.9%.
Comparative example 3
Except that polyethylene is not addedThe procedure of example 3 was repeated except for using alcohol dioleate (PEG200 DO). The specific surface area of the obtained catalyst was 7.8m2In terms of/g, the morphology was similar to that of the catalyst precursor described in comparative example 1. The obtained catalyst was evaluated by a mini fixed bed reactor with 1.8% butane feed for 1500h-1At 410 ℃, the catalyst conversion rate is 62.2%, the maleic anhydride selectivity is 68.2%, and the yield of the maleic anhydride is 42.4%.
Example 4
127.2g V was added to a 3L round bottom flask2O51350mL of a mixed solution of isobutanol and 150mL of benzyl alcohol, was heated and stirred to reflux for 4 hours, 15.0g of polyethylene glycol monooleate (PEG200MO) and 1.85g of niobium pentoxide were added thereto in a molar ratio of the template to vanadium of 0.03, 150g of 105 wt% phosphoric acid was added dropwise and heated and stirred to reflux for 20 hours, and the resulting precipitate was dried at 120 ℃ for 12 hours after being centrifuged and washed with absolute ethanol. Pressing the powder into sheet structure with height of 2mm and diameter of 25mm, pulverizing into 20-40 mesh granules, and placing in air/butane atmosphere (air/butane volume ratio 98.2/1.8, space velocity 1000h-1) Heating to 380 deg.C at a heating rate of 2 deg.C/min, maintaining for 4h, maintaining the air/butane volume ratio, and increasing the space velocity to 2000h-1And continuously heating the temperature to 420 ℃ at the heating rate of 6 ℃/min, keeping the temperature for 12 hours under the condition, and then cooling to room temperature under the protection of nitrogen to obtain the activated vanadium-phosphorus-oxygen catalyst. The specific surface area of the catalyst precursor was 25.1 m2The morphology is a curved lamellar structure (as shown in FIG. 2 c). The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 420 ℃, the catalyst conversion rate reaches 82.6%, the maleic anhydride selectivity is 67.4%, and the maleic anhydride yield is 55.7%.
Comparative example 4
The procedure was as in example 4 except that polyethylene glycol monooleate (PEG200MO) was not added. The specific surface area of the catalyst precursor is 11.7m2In terms of/g, the morphology was similar to that of the catalyst precursor described in comparative example 1. The resulting catalyst was evaluated in a fixed bed microreactor, 1.8% butane feed,1500h-1at 420 ℃, the catalyst conversion rate reaches 80.8%, the maleic anhydride selectivity is 67.3%, and the maleic anhydride yield is 54.4%.
Example 5
The procedure is as in example 1 except that the molar ratio of the template to vanadium is 0.3 instead of adding polyethylene glycol oleate (PEG200MO) and adding fatty alcohol-polyoxyethylene ether AEO 3. The specific surface area of the obtained catalyst precursor was 28.3m2In terms of/g (FIG. 2 b). The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate reaches 84.6%, the maleic anhydride selectivity is 70.2%, and the yield of the maleic anhydride is 59.4%.
Example 6
The procedure of example 4 was repeated except that the molar ratio of the template agent to vanadium was 0.005 except that polyethylene glycol oleate (PEG200MO) was not added but fatty alcohol-polyoxyethylene ether AEO7 was added. The specific surface area of the catalyst precursor is 20.7m2The morphology of the catalyst precursor is irregular lamellar aggregates (as shown in figure 2g), and the lamellar is cracked. The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate reaches 82.8%, the maleic anhydride selectivity is 67.5%, and the maleic anhydride yield is 55.9%.
Example 7
The procedure is as in example 1 except that no tungsten chloride is added. The specific surface area of the obtained catalyst precursor is 45.7m2(ii) in terms of/g. The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate reaches 79.1%, the maleic anhydride selectivity is 66.7%, and the maleic anhydride yield is 52.9%.
Example 8
The procedure was as in example 2 except that no indium oxide was added. The specific surface area of the obtained catalyst precursor is 45.7m2(ii) in terms of/g. The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate reaches 79.1%, the maleic anhydride selectivity is 66.7%, and the maleic anhydride yield is 52.9%.
Example 9
The procedure is as in example 3 except that no bismuth phosphate is added. The specific surface area of the obtained catalyst precursor was 27.9m2(ii) in terms of/g. The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 410 ℃, the catalyst conversion rate reaches 77.4%, the maleic anhydride selectivity is 63.8%, and the yield of the maleic anhydride is 49.4%.
Example 10
The procedure was as in example 4 except that niobium pentoxide was not added. The specific surface area of the obtained catalyst precursor was 35.6m2(ii) in terms of/g. The catalyst obtained was evaluated in a microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate reaches 80.3%, the maleic anhydride selectivity is 67.0%, and the maleic anhydride yield is 53.8%.
Comparative example 5
The procedure was as in example 1 except that no templating agent and no metal promoter were added. The specific surface area of the obtained catalyst precursor was 12.7m2(ii) in terms of/g. The obtained catalyst was evaluated in a fixed bed microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate is 76.3%, the maleic anhydride selectivity is 65.0%, and the maleic anhydride yield is 50.1%.
Comparative example 6
The procedure of example 1 was followed except that OP-4 was not added as a template and polyethylene glycol cetyl ether (Brij-56) was added as a template. The obtained catalyst was evaluated in a fixed bed microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate is 82.7%, the maleic anhydride selectivity is 70.0%, and the maleic anhydride yield is 57.9%.
Comparative example 7
The procedure of example 1 was followed except that OP-4 was not added as a templating agent, and instead polyethylene oxide-polypropylene oxide-polyethylene oxide (P123) was added as a templating agent. The obtained catalyst was evaluated by a fixed bed microreactor with 1.8% butane feed for 1500h-1At 400 ℃, the catalyst conversion rate is 79.7 percent, the maleic anhydride selectivity is 68.3 percent, and the yield of the maleic anhydride is 54.4 percent。
Comparative example 8
The procedure of example 5 was followed except that no fatty alcohol-polyoxyethylene ether AEO3 was added as a template, and polyethylene glycol cetyl ether (Brij-56) was added as a template. The obtained catalyst was evaluated in a fixed bed microreactor with 1.5% butane feed for 2000h-1At 400 ℃, the catalyst conversion rate is 82.1%, the maleic anhydride selectivity is 69.1%, and the maleic anhydride yield is 56.7%.
Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A preparation method of a catalyst for preparing maleic anhydride by n-butane oxidation comprises the following steps:
step S1, adding a vanadium source, a phosphorus source and a template agent into a liquid medium for reaction to prepare a maleic anhydride catalyst precursor through oxidation of n-butane, wherein the template agent is selected from one or more of polyethylene glycol oleate, alkylphenol ethoxylates and fatty alcohol polyoxyethylene ethers; wherein the molar ratio of the template agent to the vanadium element is 0.005-0.5, preferably 0.005-0.25;
and an optional step S2 of activating the catalyst precursor for preparing maleic anhydride by n-butane oxidation.
2. A preparation method of a catalyst for preparing maleic anhydride by oxidizing n-butane comprises the following steps:
step A, adding a vanadium source into a liquid medium, heating and refluxing for reaction to obtain a first reaction system;
b, adding a phosphorus source, a template agent and an optional auxiliary agent into the first reaction system, and continuously heating and refluxing for reaction to obtain a second reaction system; preferably, the reaction system in the step A is cooled to 25-80 ℃, preferably 25-60 ℃, and then a phosphorus source, a template agent and an optional auxiliary agent are added;
step C, carrying out solid-liquid separation treatment on the second reaction system, and washing and drying the obtained precipitate to obtain a catalyst precursor;
and D, optionally activating the catalyst precursor.
3. The method according to claim 1 or 2, wherein the template agent is selected from one or more of polyethylene glycol oleate, alkylphenol ethoxylates and fatty alcohol ethoxylates; preferably one or more selected from PEG-MO, PEG-DO series polyethylene glycol oleate, OP, TX series alkylphenol polyoxyethylene ether and AEO, MOA series fatty alcohol polyoxyethylene ether; more preferably from one or more of polyethylene glycol dioleate, polyoxyethylene ether of octylphenol, and polyoxyethylene ether of AEO 3.
4. The process according to any one of claims 1 to 3, wherein the molar ratio of the vanadium source to the phosphorus source, calculated as the elements, is 1 (0.8 to 4), preferably 1 (0.9 to 2), further preferably 1 (1 to 1.4), more preferably 1 (1.1 to 1.2); wherein the vanadium source is selected from one or more of vanadium oxide, vanadate and organic acid vanadium, and vanadium pentoxide is preferred; and/or the phosphorus source comprises phosphoric acid and/or phosphorus pentoxide, preferably phosphoric acid.
5. The method according to any one of claims 1 to 4, wherein the liquid medium comprises an alcoholic solvent, preferably a mixed solvent of isobutanol and benzyl alcohol, more preferably the molar ratio of the isobutanol to the benzyl alcohol is (100-85): 0-15.
6. The method according to any one of claims 1 to 5, wherein the auxiliary agent is selected from one or more of indium, niobium, bismuth, cobalt, zinc, iron and tungsten; preferably, the molar ratio of the auxiliary agent to the vanadium element is (1-5): 100-300), preferably (2-3): 150-200).
7. The process according to any one of claims 1 to 6, wherein in step A, the reaction time is 0 to 5 hours, preferably 3 to 5 hours; and/or in the step B, the reaction time is 3-24h, preferably 5-16 h.
8. The method according to any one of claims 1 to 7, wherein in step C, the solid-liquid separation treatment is filtration or centrifugation; and/or the washing treatment is carried out in an alcohol solvent, preferably absolute ethyl alcohol; and/or the drying treatment is drying at 60-150 ℃, preferably 120 ℃, for 6-24h, preferably 12 h.
9. The method as claimed in any one of claims 1 to 8, wherein in step D, the catalyst precursor is placed in an air/butane atmosphere, heated to 380-; preferably, the catalyst precursor is placed in an air/butane atmosphere with an air/butane volume ratio of 98/2-99/1, preferably 98.2/1.8, and a space velocity of 500h-1-2000h-1Preferably 1000h-1Raising the temperature to 380 ℃ at the temperature raising rate of 2-4 ℃/min, keeping the temperature for 0-6h, preferably 3-6h, keeping the volume ratio of air/butane unchanged, and raising the space velocity to 1500h-1-2500h-1Preferably 2000h-1Raising the temperature to 400-430 ℃, preferably 420 ℃ at the speed of 4-6 ℃/min, keeping the temperature for 0-18h, and then reducing the temperature to room temperature in a nitrogen atmosphere to obtain the activated catalyst.
10. A catalyst prepared according to the process of any one of claims 1 to 9, comprising vanadium, phosphorus, oxygen and optionally auxiliaries, the mass content of the vanadium element being from 20 to 30%, preferably from 21 to 26%, and the mass content of the phosphorus element being from 15 to 25%, preferably from 15 to 19%, based on the total parts by mass of the catalyst; and/or the molar ratio of the vanadium element to the phosphorus element on the surface of the catalyst is 1 (0.8-4), preferably 1 (1.5-3), and more preferably 1 (2-3).
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| US20020141927A1 (en) * | 1999-11-10 | 2002-10-03 | Yuichi Kamiya | Intercalation compound and a vanadium phosphorus mixed oxide and a process for the preparation thereof |
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| CN104607220A (en) * | 2013-11-05 | 2015-05-13 | 中国石油化工股份有限公司 | Vanadium-phosphorus oxide catalyst for preparing maleic anhydride through cyclohexane oxidation, and preparation method thereof |
| CN106582744A (en) * | 2015-10-19 | 2017-04-26 | 中国石油化工股份有限公司 | Preparation method of catalyst capable of increasing yield of maleic anhydride prepared through n-butane oxidation |
| CN108339558A (en) * | 2017-01-24 | 2018-07-31 | 中国石油化工股份有限公司 | A kind of vanadium-phosphor oxide catalyst and preparation method thereof for preparing cis-anhydride by n-butane oxidation |
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| US20020141927A1 (en) * | 1999-11-10 | 2002-10-03 | Yuichi Kamiya | Intercalation compound and a vanadium phosphorus mixed oxide and a process for the preparation thereof |
| WO2003006414A2 (en) * | 2001-07-12 | 2003-01-23 | Exxonmobil Chemical Patents Inc. | Producing maleic anhydride from a c4 stream in an oxygenate to olefin process |
| CN104607220A (en) * | 2013-11-05 | 2015-05-13 | 中国石油化工股份有限公司 | Vanadium-phosphorus oxide catalyst for preparing maleic anhydride through cyclohexane oxidation, and preparation method thereof |
| CN106582744A (en) * | 2015-10-19 | 2017-04-26 | 中国石油化工股份有限公司 | Preparation method of catalyst capable of increasing yield of maleic anhydride prepared through n-butane oxidation |
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