Oxidation catalysts, their preparation methods and applications, and methods for synthesizing acids from aldehydes

Abstract

This invention belongs to the field of catalyst technology, specifically relating to an oxidation catalyst, its preparation method and application, and a method for synthesizing acids from aldehydes. The catalyst comprises catalysts having the general formula Mo. 12 V a P b Cs c Q d O g The active component, wherein Q is selected from at least one of Cu, Sb, W, Ca, Te, K, Na, and Fe; a = 0.05–5.0; b = 0.5–6.0; c = 0.05–6.0; d = 0–6.0; g is a value determined by the total valence of the elements other than oxygen in the general formula; the XRD pattern of the catalyst includes: 2θ = 10.6°, 15.1°, 18.5°, 21.4°, 23.9°, 26.3°, 30.5°, 35.9°, 39.1°, 43.7°, 47.9°, 55.4°, and 62.4°; and the catalyst has open channels of 20–500 nm. The oxidation catalyst of the present invention is used for the synthesis of acids from aldehydes, with a long catalyst life and high product yield.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an oxidation catalyst, its preparation method and application, and a method for synthesizing acids from aldehydes. Background Technology

[0002] Methacrylic acid (MAA) is an important chemical raw material. It has two functional groups: carboxylic acid and carbon-carbon double bond. It can undergo chemical reactions such as esterification and polymerization to prepare various lipids and polymers, which are used in the production of plexiglass, resins, adhesives, polymer materials, coatings and other fields.

[0003] Currently, industrial production of methacrylic acid uses the acetone cyanohydrin method, the ethylene carbonylation method, and the isobutylene oxidation method. Among these, the acetone cyanohydrin method, due to the use of highly toxic HCN, does not conform to green environmental protection principles and is gradually being banned and phased out by the state. The isobutylene oxidation method has a shorter production route and is environmentally friendly, gradually becoming the mainstream production process for methacrylic acid. The catalyst for oxidizing methacrolein to methacrylic acid is the key technology in this process.

[0004] Currently, Mo-P heteropolyacid catalysts have better catalyst performance, with higher conversion and selectivity. However, due to the lack of stable crystal morphology, heteropolyacids have a shorter service life. Summary of the Invention

[0005] One of the technical problems to be solved by the present invention is that the catalyst used in the prior art for the oxidation of methacrolein to synthesize methacrylic acid has a short service life and low product yield. The present invention provides an oxidation catalyst that is used for the synthesis of acid from aldehydes, and has a long service life and high product yield.

[0006] The second technical problem to be solved by the present invention is that the preparation methods in the prior art are difficult to obtain catalysts with both large grains and large pores. The present invention provides a method for preparing the oxidation catalyst described in the present invention.

[0007] To achieve the objectives of this invention, a first aspect of this invention provides an oxidation catalyst comprising a catalyst having the general formula Mo. 12 V a P b Cs c Q d O gThe active component, wherein Q is selected from at least one of Cu, Sb, W, Ca, Te, K, Na, and Fe; a = 0.05–5.0; b = 0.5–6.0; c = 0.05–6.0; d = 0–6.0; g is a value determined by the total valence of the elements other than oxygen in the general formula; the XRD spectrum of the active component includes: 2θ = 10.6°, 15.1°, 18.5°, 21.4°, 23.9°, 26.3°, 30.5°, 35.9°, 39.1°, 43.7°, 47.9°, 55.4°, and 62.4°; and the catalyst has open channels of 20–500 nm.

[0008] A second aspect of the present invention provides a method for preparing the oxidation catalyst of the present invention, the method comprising:

[0009] (1) Molybdenum source, vanadium source, and phosphorus source are used to form an aqueous solution A; cesium source and Q source are used to form an aqueous dispersion B;

[0010] (2) Add aqueous dispersion B dropwise to aqueous solution A to perform the first mixing, and obtain the first mixture;

[0011] (3) Then, alcohol and long-chain organic acid are added for a second mixing to obtain a second mixture H;

[0012] (4) Crystallize and dry the second mixture H to obtain the active component;

[0013] (5) Optionally, the active component is mixed with the carrier raw material and then molded and calcined.

[0014] A third aspect of the present invention provides the application of the oxidation catalyst described herein in the synthesis of aldehydes into acids.

[0015] A fourth aspect of the present invention provides a method for synthesizing an acid from an aldehyde, the method comprising: contacting an aldehyde, an oxygen-containing gas, and an oxidation catalyst, wherein the oxidation catalyst includes the oxidation catalyst described in the present invention.

[0016] The oxidation catalyst provided by the present invention has a stable crystal morphology and large pores. According to a preferred embodiment of the present invention, the oxidation catalyst has the characteristics of large crystal grains and the advantage of having a Keggin structure.

[0017] The oxidation catalyst described in this invention is used for the synthesis of acids from aldehydes. It has a long catalyst life and a high product yield. Attached Figure Description

[0018] Figure 1 This is a scanning electron microscope (SEM) image of the oxidation catalyst prepared in Example 1 of the present invention;

[0019] Figure 2The image shows the XRD pattern of the active component of the oxidation catalyst prepared in Example 1 of this invention. Detailed Implementation

[0020] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] The first aspect of the present invention provides an oxidation catalyst comprising a catalyst having the general formula Mo 12 V a P b Cs c Q d O g The active component, wherein Q is selected from at least one of Cu, Sb, W, Ca, Te, K, Na, and Fe; a = 0.05–5.0; b = 0.5–6.0; c = 0.05–6.0; d = 0–6.0; g is a value determined by the total valence of the elements other than oxygen in the general formula; the XRD pattern of the active component includes: 2θ = 10.6°, 15.1°, 18.5°, 21.4°, 23.9°, 26.3°, 30.5°, 35.9°, 39.1°, 43.7°, 47.9°, 55.4°, and 62.4°; and the catalyst has open channels of 20–500 nm. The oxidation catalyst provided by this invention has a stable crystal morphology and open macropores.

[0022] According to a preferred embodiment of the present invention, in the XRD pattern of the active component of the oxidation catalyst, the grain size range calculated by 2θ = 10.6° is 20-50 nm.

[0023] According to a preferred embodiment of the present invention, the active component has a Keggin-type heteropolyacid structure with large-particle crystals, preferably with a grain size of 20-1000 nm, and the oxidation catalyst also has the advantages of large grains and Keggin structure.

[0024] In this invention, the active component can be loaded onto a support to form an oxidation catalyst. Preferably, the catalyst further includes a support on which the active component is loaded. This invention does not have a particular limitation on the type of support, which can be a conventional support in the art.

[0025] According to a preferred embodiment of the present invention, the support is selected from one or more of SiO2, Al2O3, ZrO2, and TiO2.

[0026] According to a preferred embodiment of the present invention, the catalyst comprises 20 to 90 parts by mass and 10 to 80 parts by mass of an active component, based on 100 parts by mass.

[0027] The oxidation catalysts possessing the aforementioned properties can all achieve the objectives of this invention. This invention does not particularly limit the preparation method of the oxidation catalysts. According to a preferred embodiment of this invention, this invention provides a method for preparing the oxidation catalysts, the method comprising:

[0028] (1) Molybdenum source, vanadium source, and phosphorus source are used to form an aqueous solution A; cesium source and Q source are used to form an aqueous dispersion B;

[0029] (2) Add aqueous dispersion B dropwise to aqueous solution A to perform the first mixing, and obtain the first mixture;

[0030] (3) Add a mixture of alcohol and long-chain organic acid C to the first mixture for a second mixing to obtain a second mixture H;

[0031] (4) Crystallize and dry the second mixture H to obtain the active component;

[0032] (5) Optionally, the active component is mixed with the carrier raw material and then molded and calcined.

[0033] According to a preferred embodiment of the present invention, the alcohol is a C1-C6 monohydric alcohol and / or polyhydric alcohol.

[0034] According to a preferred embodiment of the present invention, the alcohol is one or more selected from methanol, ethanol, 1-propanol, 2-propanol, 1,2-propanediol, 1,3-propanediol and glycerol, preferably one or more selected from ethanol, 1-propanol and 2-propanol; more preferably, the alcohol is a mixture of ethanol and 1-propanol, wherein the mass ratio of the two is 0.1-10:1.

[0035] According to a preferred embodiment of the present invention, the long-chain organic acid is a C8-C18 organic acid; preferably, the long-chain organic acid is one or more selected from oleic acid, linoleic acid, stearic acid, palmitic acid, octanoic acid, isooctanoic acid, arbutinic acid, n-decanoic acid, undecenoic acid, lauric acid, and tetradecanoic acid; more preferably, the long-chain organic acid is one or more selected from oleic acid, linoleic acid, stearic acid, and palmitic acid; more preferably, the long-chain organic acid is a mixture of oleic acid and stearic acid, wherein the mass ratio of the two is 1.5-5:1.

[0036] According to a preferred embodiment of the present invention, the mass ratio of the alcohol to the long-chain organic acid is 0.1-10:1.

[0037] In this invention, there is no particular limitation on the type of molybdenum source, which can be any molybdenum-containing substance conventional in the art. Preferably, the molybdenum source is selected from at least one of soluble molybdenum salts, and more preferably ammonium heptamolybdate.

[0038] In this invention, there is no particular limitation on the type of vanadium source, which can be any vanadium-containing substance conventional in the art. Preferably, the vanadium source is selected from at least one of soluble vanadium salts, and more preferably, ammonium metavanadate.

[0039] In this invention, there is no particular limitation on the type of phosphorus source, which can be any phosphorus-containing substance conventional in the art. Preferably, the phosphorus source is selected from phosphoric acid.

[0040] In this invention, there is no particular limitation on the type of cesium source, which can be any cesium-containing substance conventional in the art. Preferably, the cesium source is selected from at least one of soluble cesium salts, and more preferably cesium nitrate and / or cesium chloride.

[0041] In this invention, there is no particular limitation on the type of Q source, which can be an oxygen-containing salt and / or oxygen-containing salt hydrate corresponding to the Q element conventional in the art. Preferably, the Q source is selected from soluble salts of one or more elements selected from Cu, Sb, W, Ca, Te, K, Na and Fe.

[0042] In this invention, the soluble salt also includes hydrates of the soluble salt.

[0043] According to a preferred embodiment of the present invention, the amount of alcohol used is 10-50 parts by weight and the amount of long-chain organic acid used is 10-50 parts by weight relative to 100 parts by weight of the first mixture.

[0044] According to a preferred embodiment of the present invention, the solid content of aqueous solution A is 20-60% by weight.

[0045] According to a preferred embodiment of the present invention, the solid content of the aqueous dispersion B is 30-80% by weight.

[0046] According to a preferred embodiment of the present invention, the conditions for the first mixing include: a temperature of 20-95°C; and adjusting the stirring speed appropriately according to the mixing temperature; preferably, the stirring speed is 80-3000 r / min.

[0047] According to a preferred embodiment of the present invention, the conditions for the second mixing include: a temperature of 20-95°C; and a stirring speed that is adjusted reasonably according to the mixing temperature; preferably, the stirring speed is 80-3000 r / min.

[0048] According to a preferred embodiment of the present invention, the crystallization conditions include: a temperature of 70-150°C, and a crystallization time that is reasonably adjusted according to the crystallization temperature. Preferably, the crystallization time is 1-96 hours.

[0049] According to a preferred embodiment of the present invention, the roasting conditions include: a roasting temperature of 250-400°C, and a roasting time that is reasonably adjusted according to the roasting temperature. Preferably, the roasting time is 2-100 hours.

[0050] According to a preferred embodiment of the present invention, the carrier raw material is one or more of SiO2, Al2O3, ZrO2, TiO2 and their precursors.

[0051] According to a preferred embodiment of the present invention, the carrier material further includes a binder and graphite; preferably, the binder is selected from at least one of hydroxypropyl cellulose, silica sol, alumina sol, starch, microcrystalline cellulose and guar gum.

[0052] A third aspect of this invention provides the application of the oxidation catalyst described herein in the synthesis of acids from aldehydes. The oxidation catalyst described herein, when used for the synthesis of acids from aldehydes, exhibits a long catalyst life and high product yield.

[0053] According to a preferred embodiment of the present invention, the present invention provides an application of the oxidation catalyst described herein in the oxidation of methacrolein to synthesize methacrylic acid.

[0054] A fourth aspect of this invention provides a method for synthesizing acids from aldehydes. The method includes contacting an aldehyde, an oxygen-containing gas, and an oxidation catalyst, wherein the oxidation catalyst includes the oxidation catalyst described in this invention. The oxidation catalyst described in this invention is used for synthesizing acids from aldehydes, exhibiting a long catalyst life and high product yield.

[0055] According to a preferred embodiment of the present invention, the contact conditions include a temperature of 240–320°C, which is beneficial to improving product yield.

[0056] According to a preferred embodiment of the present invention, the contact conditions include: an aldehyde volume hourly space velocity of 60–120 mL·h. -1 ·g -1 This is beneficial for improving product yield.

[0057] In this invention, the oxidation catalyst described herein is particularly suitable for the oxidation of aldehydes to synthesize acids. Preferably, the aldehyde is one or more unsaturated aldehydes, which is beneficial for improving product yield.

[0058] According to a preferred embodiment of the present invention, the aldehyde is methacrolein and / or acrolein.

[0059] According to a preferred embodiment of the present invention, the oxygen-containing gas is air, oxygen, a mixture of oxygen and nitrogen, or a mixture of air and nitrogen.

[0060] The present invention will now be described in detail with reference to embodiments. It should be understood that the embodiments and examples described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0061] The catalyst evaluation method used in the following examples is as follows:

[0062] The reactant methacrolein was passed into a fixed-bed reactor packed with the analyte catalyst. The reaction product was absorbed with dilute acid at 0°C, followed by analysis using gas chromatography. During the analysis, the carbon balance was calculated, and data with a carbon balance between 95% and 105% were selected as valid data. The reaction conditions were as follows:

[0063] Reactor: Fixed-bed reactor, inner diameter 25.4 mm, length 750 mm;

[0064] Oxidation catalyst loading: 150 grams;

[0065] Reaction temperature: 300℃;

[0066] Reaction time: 300 hours;

[0067] Raw material volume ratio: Methacrolein:O2:water vapor:N2 = 1:3:5:18;

[0068] Methacrolein volume hourly space velocity: 90 mL·h -1 ·g -1 .

[0069] Example 1

[0070] (1) Mix 8.2 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 ·4H2O) was dissolved in 150ml of deionized water, and 7.0g of phosphoric acid solution (85wt%) was added dropwise. The mixture was heated to 80℃ and stirred continuously for 2 hours to obtain solution A; 16.5g of cesium nitrate and 5.8g of ferric nitrate were dissolved in 30ml of deionized water to obtain solution B;

[0071] (2) Add solution B dropwise to solution A, stir continuously for 3 hours, and finally add a mixture of 75 g of ethanol and 75 g of oleic acid, solution C, to obtain solution H.

[0072] (3) Transfer the mixture H to the crystallization vessel, heat it at 150°C for 96 hours, and then take it out and dry it to obtain the catalyst precursor.

[0073] (4) Take 100g of the obtained catalyst active component, 5g of hydroxypropyl cellulose, 40g of kaolin, 1.6g of graphite and 3.2g of deionized water and mix them evenly. Set the tableting pressure to 3kN using a tablet press and press to form a circular tablet with a diameter of 5mm and a thickness of 4mm. Finally, calcine at 360℃ for 20 hours to obtain the oxidation catalyst.

[0074] The catalyst obtained was evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0075] Figure 1 This is a scanning electron microscope (SEM) image of the oxidation catalyst prepared in Example 1 of this invention; Figure 1 It can be seen that the catalyst surface has open pores of 50-500 nm.

[0076] Figure 2 The image shows the XRD pattern of the active component of the oxidation catalyst prepared in Example 1 of this invention; Figure 2 As can be seen, the XRD spectrum of the active component of the present invention includes characteristic peaks at 2θ = 10.6°, 15.1°, 18.5°, 21.4°, 23.9°, 26.3°, 30.5°, 35.9°, 39.1°, 43.7°, 47.9°, 55.4°, and 62.4°, indicating that the active component has a typical Keggin structure; the grain size calculated from 2θ = 10.6° is 38.7 nm.

[0077] Example 2

[0078] (1) Mix 8.2 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 ·4H2O) was dissolved in 150ml of deionized water, and 7.0g of phosphoric acid solution (85wt%) was added dropwise. The mixture was heated to 80℃ and stirred continuously for 2 hours to obtain solution A; 16.5g of cesium nitrate and 3.4g of copper nitrate were dissolved in 30ml of deionized water to obtain solution B;

[0079] (2) Add solution B dropwise to solution A, stir continuously for 3 hours, and finally add a mixture of 75 g of ethanol and 75 g of oleic acid, solution C, to obtain solution H.

[0080] (3) Transfer the mixture H to the crystallization vessel, heat it at 150°C for 96 hours, and then take it out and dry it to obtain the catalyst precursor.

[0081] (4) Take 100g of the obtained catalyst active component, 5g of hydroxypropyl cellulose, 40g of kaolin, 1.6g of graphite and 3.2g of deionized water and mix them evenly. Set the tableting pressure to 3kN using a tablet press and press to form a circular tablet with a diameter of 5mm and a thickness of 4mm. Finally, calcine at 360℃ for 20 hours to obtain the oxidation catalyst.

[0082] The catalyst obtained was evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0083] Example 3

[0084] (1) Mix 8.2 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 ·4H2O) was dissolved in 150ml of deionized water, and 7.0g of phosphoric acid solution (85wt%) was added dropwise. The mixture was heated to 80℃ and stirred continuously for 2 hours to obtain solution A; 16.5g of cesium nitrate and 3.3g of calcium nitrate were dissolved in 30ml of deionized water to obtain solution B;

[0085] (2) Add solution B dropwise to solution A, stir continuously for 3 hours, and finally add a mixture of 75 g of ethanol and 75 g of oleic acid, solution C, to obtain solution H.

[0086] (3) Transfer the mixture H to the crystallization vessel, heat it at 150°C for 96 hours, and then take it out and dry it to obtain the catalyst precursor.

[0087] (4) Take 100g of the obtained catalyst active component, 5g of hydroxypropyl cellulose, 40g of kaolin, 1.6g of graphite and 3.2g of deionized water and mix them evenly. Set the tableting pressure to 3kN using a tablet press and press to form a circular tablet with a diameter of 5mm and a thickness of 4mm. Finally, calcine at 360℃ for 20 hours to obtain the oxidation catalyst.

[0088] The catalyst obtained was evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0089] Example 4

[0090] The difference compared to Example 1 is that,

[0091] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of ethanol and oleic acid (the mass ratio of ethanol to oleic acid is 2:1) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The catalyst obtained is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0092] Example 5

[0093] The difference compared to Example 1 is that,

[0094] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of ethanol and oleic acid (the mass ratio of ethanol to oleic acid is 1:2) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The catalyst obtained is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0095] Example 6

[0096] The difference compared to Example 1 is that,

[0097] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of ethanol and linoleic acid (the mass ratio of ethanol to linoleic acid is 1:1) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The catalyst obtained is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0098] Example 7

[0099] The difference compared to Example 1 is that,

[0100] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of ethanol and stearic acid (the mass ratio of ethanol to stearic acid is 1:1) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The catalyst obtained is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0101] Example 8

[0102] The difference compared to Example 1 is that,

[0103] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of ethanol and palmitic acid (the mass ratio of ethanol to palmitic acid is 1:1) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The catalyst obtained is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0104] Example 9

[0105] The difference compared to Example 1 is that,

[0106] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of 1-propanol and oleic acid (the mass ratio of 1-propanol to oleic acid is 1:1) is added to obtain mixture H. The remaining conditions are the same as in Example 1. The catalyst obtained is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0107] Example 10

[0108] The difference compared to Example 1 is that,

[0109] In step (2), solution B was added dropwise to solution A, and the mixture was stirred continuously for 3 hours. Finally, 150 grams of a mixture C of 2-propanol and oleic acid (the mass ratio of 1,2-propanediol to oleic acid was 1:1) was added to obtain mixture H. The remaining conditions were the same as in Example 1. The catalyst obtained was evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0110] Example 11

[0111] The difference compared to Example 1 is that,

[0112] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of methanol and oleic acid (methanol to oleic acid mass ratio of 1:1) is added to obtain mixture H. The remaining conditions are the same as in Example 1. The obtained catalyst is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0113] Example 12

[0114] The difference compared to Example 1 is that,

[0115] In step (2), solution B was added dropwise to solution A, and the mixture was stirred continuously for 3 hours. Finally, 150 g of a mixture C of 1,2-propanediol and oleic acid (the mass ratio of 2-propanediol to oleic acid was 1:1) was added to obtain mixture H. The remaining conditions were the same as in Example 1. The obtained catalyst was evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0116] Example 13

[0117] The difference compared to Example 1 is that,

[0118] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of a mixture C of glycerol and oleic acid (the mass ratio of glycerol to oleic acid is 1:1) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The obtained catalyst is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0119] Example 14

[0120] The difference compared to Example 1 is that,

[0121] In step (2), solution B was added dropwise to solution A, and the mixture was stirred continuously for 3 hours. Finally, a mixture of 75g of ethanol and 1-propanol (the mass ratio of ethanol to 1-propanol was 1:1) and 75g of oleic acid was added to obtain a mixture H. The remaining conditions were the same as in Example 1. The catalyst obtained was evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0122] Example 15

[0123] The difference compared to Example 1 is that,

[0124] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, a mixture C consisting of 75g of ethanol and 75g of a mixture of oleic acid and stearic acid (the mass ratio of oleic acid to stearic acid is 1:1) is added to obtain a mixed solution H. The remaining conditions are the same as in Example 1. The obtained catalyst is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0125] Comparative Example 1

[0126] The difference compared to Example 1 is that,

[0127] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of ethanol is added to obtain mixture H. The remaining conditions are the same as in Example 1. The obtained catalyst is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0128] Comparative Example 2

[0129] The difference compared to Example 1 is that,

[0130] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. Finally, 150 grams of oleic acid are added to obtain mixture H. The remaining conditions are the same as in Example 1. The obtained catalyst is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0131] Comparative Example 3

[0132] The difference compared to Example 1 is that,

[0133] In step (2), solution B is added dropwise to solution A, and the mixture is stirred continuously for 3 hours. The remaining conditions are the same as in Example 1. The obtained catalyst is evaluated using the catalyst evaluation method described in this invention, and the results are shown in Table 1.

[0134] Table 1

[0135]

[0136]

[0137] As shown in Table 1, compared with Comparative Examples 1-3, the oxidation catalysts of the present invention described in Examples 1-15 can effectively improve catalyst activity and lifetime, and have high conversion rates of methacrolein and high yields of methacrylic acid.

[0138] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An oxidation catalyst characterized by, The catalyst comprises an active component having the general formula Mo 12 V a P b Cs c Q d O g wherein Q is selected from at least one of Cu, Sb, W, Ca, Te, K, Na, Fe; a = 0.05-5.0; b = 0.5-6.0; c = 0.05-6.0; d = 0-6.0; g is a value determined by the total valence of the elements in the general formula except oxygen; the XRD spectrum of the active component comprises: 2θ = 10.6°, 15.1°, 18.5°, 21.4°, 23.9°, 26.3°, 30.5°, 35.9°, 39.1°, 43.7°, 47.9°, 55.4°, 62.4°; and the catalyst has open pores of 20-500 nm; the grain size calculated from the XRD spectrum of the active component at 2θ = 10.6° is in the range of 20-50 nm.

2. The catalyst of claim 1, wherein, The active component has a Keggin-type heteropoly acid structure with large particle crystallization, and the large particle has a grain size of 20-1000 nm; and / or The catalyst further comprises a carrier on which the active component is loaded.

3. The catalyst according to claim 2, wherein, The carrier is selected from one or more of SiO2, Al2O3, and ZrO2, and TiO2; and / or The catalyst comprises 20-90 parts by mass of the active component and 10-80 parts by mass of the carrier, per 100 parts by mass.

4. Use of the oxidation catalyst according to any one of claims 1-3 in the synthesis of aldehyde into acid.

5. The method of producing an oxidation catalyst according to any one of claims 1 to 3, characterized by, The method comprises: (1) forming an aqueous solution A from a molybdenum source, a vanadium source, and a phosphorus source; and forming an aqueous dispersion B from a cesium source and a Q source; (2) adding the aqueous dispersion B dropwise to the aqueous solution A to perform first mixing, to obtain a first mixed solution; (3) adding a mixed solution C of alcohol and long-chain organic acid to the first mixed solution to perform second mixing, to obtain a second mixed solution H; (4) performing crystallization and drying on the second mixed solution H to obtain the active component; (5) optionally, mixing the active component with a carrier raw material, and then performing shaping and calcination.

6. The preparation method according to claim 5, wherein, The alcohol is a C1-C6 monohydric alcohol and / or a polyhydric alcohol.

7. The production method according to claim 6, wherein The alcohol is one or more of methanol, ethanol, 1-propanol, 2-propanol, 1,2-propanediol, 1,3-propanediol, and glycerol.

8. The production method according to claim 7, wherein The alcohol is one or more of ethanol, 1-propanol, and 2-propanol.

9. The production method according to claim 8, wherein The alcohol is a mixture of ethanol and 1-propanol, and the mass ratio of the two is 0.1-10:

1.

10. The production method according to claim 5, wherein, The long-chain organic acid is a C8-C18 organic acid.

11. The production method according to claim 10, wherein The long-chain organic acid is one or more of oleic acid, linoleic acid, stearic acid, palmitic acid, octanoic acid, iso-octanoic acid, caprylic acid, n-decanoic acid, undecylenic acid, lauric acid, and myristic acid.

12. The production method according to claim 11, wherein The long-chain organic acid is one or more of oleic acid, linoleic acid, stearic acid, and palmitic acid.

13. The production method according to claim 12, wherein The long-chain organic acid is a mixture of oleic acid and stearic acid, and the mass ratio of the two is 1.5-5:

1.

14. The production method according to claim 5, wherein, The mass ratio of the alcohol to the long-chain organic acid is 0.1-10:

1.

15. The preparation method according to claim 5, wherein, The molybdenum source is selected from at least one of soluble molybdenum salts; and / or The vanadium source is selected from at least one of soluble vanadium salts; and / or The phosphorus source is selected from phosphoric acid; and / or The cesium source is selected from at least one of soluble cesium salts; and / or The Q source is selected from soluble salts of one or more elements of Cu, Sb, W, Ca, Te, K, Na, and Fe.

16. The preparation method according to claim 5, wherein, The amount of alcohol is 10-50 parts by weight, and the amount of long-chain organic acid is 10-50 parts by weight, relative to 100 parts by weight of the first mixed solution; and / or The solid content of the aqueous solution A is 20-60% by weight; and / or The solid content of the aqueous dispersion B is 30-80% by weight; and / or The conditions for the first mixing include a temperature of 20-95°C; and / or The conditions for the second mixing include a temperature of 20-95°C; and / or The crystallization conditions include: temperature of 70-150℃, time of 1-96h.

17. The production method according to claim 5, wherein, The calcination conditions include: calcination temperature of 250-400℃, and / or calcination time of 2-100h; and / or The carrier raw material is one or more of SiO2, Al2O3, ZrO2, TiO2 and their precursors.

18. A method of synthesizing an aldehyde synthesis acid, characterized by, The method includes: contacting an aldehyde, an oxygen-containing gas and an oxidation catalyst, the oxidation catalyst including the oxidation catalyst according to any one of claims 1-3.

19. The method of claim 18, wherein, The contacting conditions include: temperature of 240-320℃; and / or The volume space velocity of the aldehyde is 60-120 mL•h -1 •g -1 ; and / or The aldehyde is one or more of unsaturated aldehydes; and / or The oxygen-containing gas is air, oxygen, oxygen and nitrogen mixed gas or air and nitrogen mixed gas.

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