Catalyst for synthesis of acrylic acid, its preparation method and use

Abstract

The application discloses a catalyst for synthesizing acrylic acid, a preparation method and application thereof. The catalyst comprises an active component with a general formula of MO x / Mo3VO 11 , MO X is loaded on Mo3VO 11 crystal phase, and M is selected from one or more of Cu, W, Ni and Sb. The catalyst has the characteristics of high conversion rate, high acrylic acid yield and long service life in the application to the acrylic acid synthesis reaction.

Description

Technical Field

[0001] This invention belongs to the technical field of acrylic acid synthesis methods, specifically relating to a catalyst for synthesizing acrylic acid, its preparation method, and its application. Background Technology

[0002] Acrylic acid and its esters are widely used in construction, electronics, automotive industries and other fields, and are used to synthesize coatings, adhesives, water-absorbing resins and so on. Currently, the two-step oxidation method of propylene is used in industry to produce acrylic acid. (1) In the first reactor, under the action of Mo-Bi composite oxide catalyst, propylene is oxidized to acrolein; (2) In the second reactor, under the action of Mo-V composite oxide catalyst, acrolein is oxidized to acrylic acid, and byproducts such as CO, CO2, acetaldehyde and acetic acid are generated at the same time, and a large amount of heat is released.

[0003] Currently, the common method for preparing catalysts for acrylic acid synthesis involves preparing a solution of a metal compound, adding an insoluble oxide for evaporation, followed by calcination, pulverization, and molding. Patent CN104399483A discloses a catalyst for the oxidation of acrolein to acrylic acid, characterized by using Mo... 12 V a W b M c Si d O x Defined as follows: Mo, V, and W are the active components of the catalyst; the support Si is derived from mesoporous silica; the promoter M is selected from at least one of Cu, Fe, Sb, Ce, Co, and Ni; a, b, c, d, and x represent the atomic number of each element, with the atomic number of Mo being 12, the value of a for V being 2 to 6, the value of b for W being 1 to 3, the value of c for M being 0.1 to 3, the value of d for Si being 20 to 100, and the value of x for O being determined by the atomic number of the other elements.

[0004] In summary, the catalysts obtained by the above preparation methods usually lack stable crystal morphology or special pore size distribution, have short service life, low catalyst conversion and selectivity, and low product yield. Summary of the Invention

[0005] To address the problems of unreasonable pore size distribution and low product yield in the oxidation of acrolein to acrylic acid, existing technologies provide a catalyst for the synthesis of acrylic acid, its preparation method, and its application. The catalyst of this invention, used in the oxidation of acrolein to acrylic acid, features high acrylic acid yield and long service life.

[0006] The first aspect of this invention provides a catalyst for synthesizing acrylic acid, comprising a catalyst having the general formula MO. x / Mo3VO 11The active component, x, is the number of oxygen atoms that satisfy the partial reduction valence; wherein, M is selected from one or more of Cu, W, Ni, and Sb, preferably Ni.

[0007] Furthermore, MO x / Mo3VO 11 Refers to MO x Loaded on Mo3VO 11 Crystal phase.

[0008] Furthermore, in the catalyst, based on the mass of the active component, MO x The content is 0.1% to 12%, preferably 5% to 12%.

[0009] Furthermore, Mo3VO 11 It exhibits the characteristic of directional growth, and the peak intensity ratio of the characteristic peak 2θ = 24.9 (540 crystal plane) to 2θ = 22.2 (001 crystal plane) in its XRD spectrum is 0 to 0.65, preferably 0 to 0.45, and more preferably 0.10 to 0.40.

[0010] Furthermore, the catalyst further includes a support for loading the active component, preferably selected from one or more of SiO2, Al2O3, ZrO2 and TiO2.

[0011] Furthermore, based on 100 parts by mass of the catalyst, the catalyst comprises 20 to 90 parts by mass of the active component and 10 to 80 parts by mass of the support.

[0012] Furthermore, the catalyst has a hierarchical pore distribution, with the first-level pores having a diameter of 2 to 50 nm (excluding 50 nm micropores) and a pore volume accounting for 10% to 50% of the total pore volume, and the second-level pores having a diameter of 50 to 1000 nm and a pore volume accounting for 50% to 90% of the total pore volume.

[0013] Furthermore, the specific surface area of ​​the catalyst is 1–50 m². 2 / g, total pore volume: 0.001~0.1cm 3 / g, preferably 0.01~0.07cm 3 / g.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising the following steps:

[0015] (1) Dissolve V source and Mo source in water to obtain solution A, and mix alcohol, water and long-chain organic acid to obtain solution B;

[0016] (2) Add solution A dropwise to solution B, adjust the pH value, and obtain a suspension;

[0017] (3) The obtained suspension was dried and pulverized, and then calcined for the first time to obtain catalyst precursor I;

[0018] (4) Load M onto catalyst precursor I, dry and then pulverize to obtain catalyst precursor II;

[0019] (5) The obtained catalyst precursor II is mixed with the support raw material, shaped, and calcined for a second time to obtain the catalyst for synthesizing acrylic acid.

[0020] Further, in step (1), the V source and Mo source are selected from oxygen-containing salts and / or oxygen-containing salt hydrates of V and Mo elements, preferably including ammonium heptamolybdate and / or its hydrate, ammonium metavanadate and / or its hydrate. The V source and Mo source are fed in a Mo / V atomic ratio of 0.2 to 20, preferably 1 to 6.

[0021] Further, in step (1), the alcohol is a C1-C6 monohydric alcohol or polyhydric alcohol, preferably one or more of methanol, ethanol, 1-propanol, 2-propanol, 1,3-propanediol and glycerol, more preferably one or more of ethanol, 1-propanol and 2-propanol, and even more preferably a mixture of ethanol and 1-propanol, wherein the mass ratio of ethanol to 1-propanol is 0.1 to 10:1.

[0022] Further, in step (1), the long-chain organic acid is a C8-C18 organic acid, preferably one or more of 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 one or more of oleic acid, linoleic acid, stearic acid and palmitic acid, preferably a mixture of oleic acid and stearic acid, wherein the mass ratio of oleic acid to stearic acid is 1.5 to 5:1.

[0023] Further, in step (1), in the mixed solution B, the mass ratio of water to ethanol is 1:9 to 9:1, preferably 1:5 to 5:1; the mass ratio of long-chain organic acid to the total weight of water and ethanol is 2:8 to 8:2, preferably 2:6 to 6:2.

[0024] Further, in step (2), the mass ratio of the total organic matter in solution B to the molybdenum salt in solution A is 0.5 to 15:1. The total organic matter refers to the total mass of alcohols and long-chain organic acids.

[0025] Furthermore, in step (2), the pH adjustment agent can be one or more of ammonia, NaOH, and KOH, preferably ammonia. The concentration of the ammonia is 5wt% to 25wt%, and the pH of the suspension is 7 to 12.

[0026] Furthermore, in step (3), the drying temperature is 70-150℃ and the drying time is 24-96h.

[0027] Further, in step (3), the temperature of the first roasting is 350-700℃, the roasting time is 0.5-100h, and the roasting atmosphere is an inert atmosphere, air, a mixture of inert atmosphere / oxygen (inert gas volume percentage 50%-100%) or a mixture of inert atmosphere / air (inert gas volume percentage 5%-20%).

[0028] Further, in step (4), the M source can be a soluble compound. Preferably, the M source is selected from soluble oxygen-containing salts and / or oxygen-containing salt hydrates of one or more elements selected from Cu, W, Ni, and Sb. For example, the Cu source is selected from copper nitrate and / or its hydrate, the W source is selected from ammonium metatungstate and / or its hydrate, the Ni source is selected from nickel nitrate and / or its hydrate, and the Sb source is selected from antimony tartrate and / or its hydrate. The mass percentage concentration of the M source is 5 wt% to 45 wt%.

[0029] Furthermore, in step (4), the loading method is preferably equal volume impregnation.

[0030] Further, in step (5), the carrier raw material is selected from one or more of SiO2, Al2O3, ZrO2, TiO2, SiO2 precursor, Al2O3 precursor, ZrO2 precursor and TiO2 precursor.

[0031] Furthermore, in step (5), the molding method can be a method commonly used in the art, and a pore-forming agent and a lubricant can be added during the molding process. The types of pore-forming agents and lubricants are widely selectable, and commonly used types can all be used in this invention. For this invention, preferred pore-forming agents include hydroxypropyl cellulose and / or polyethylene glycol (PEG), and lubricants include graphite.

[0032] Furthermore, the mass ratio of catalyst precursor II: pore-forming agent: lubricant is 75-98: 0.5-15: 0.5-15.

[0033] Furthermore, in step (5), the temperature of the second calcination is 250-600℃, the calcination time is 0.5-100h, and the calcination atmosphere is a mixture of reducing gas (volume percentage 0.5%-4% or 75%-100%) and inert gas.

[0034] Furthermore, the temperature of the first firing is 15 to 130°C higher than the temperature of the second firing.

[0035] A third aspect of the present invention provides an application of the above-described catalyst in the synthesis of acrylic acid.

[0036] Furthermore, the application includes reacting the above-mentioned catalyst with acrolein at a reaction temperature of 240–320°C, preferably 265–295°C, and a volume hourly space velocity of 70–150 h⁻¹. -1 Preferably 90–115h -1 .

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The catalyst active component of the present invention includes MO. x / Mo3VO 11 MO X Mo3VO loaded with directionally grown 11 The crystalline phase, when applied in the synthesis reaction of acrylic acid, features high conversion rate, high acrylic acid yield, and long lifespan.

[0039] 2. This invention uses an induced growth method to obtain directionally grown Mo3VO4. 11 This can improve the selectivity of acrylic acid catalysts, MO x The load is beneficial to the stability of Mo3VO 11 The unique hierarchical pore distribution is beneficial for improving the conversion rate of the catalyst. Detailed Implementation

[0040] 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.

[0041] In this invention, the pore structure of the catalyst obtained by nitrogen adsorption-desorption test was determined using a Tristar-3000 from Mack Company, USA. The specific surface area was tested by the BET method, and the pore volume and pore distribution were tested by the BJH method.

[0042] In this invention, XRD patterns are measured by X-ray diffraction using a Broker ADVANCED 8 X-ray diffractometer (CuKa), with a scanning range of 2θ = 10-90° and a scanning speed of 5° / min, to determine the phase composition and relative content of crystal planes.

[0043] The catalyst evaluation methods used in the following examples and comparative examples are as follows:

[0044] The reactant acrolein was passed into a fixed-bed reactor packed with the catalyst to be tested. The reaction product was absorbed with dilute acid at 0°C, and then analyzed by gas chromatography. During the analysis, the carbon balance was calculated, and data with a carbon balance of 95%–105% were selected as valid data. The reaction conditions were as follows:

[0045] Reactor: Fixed-bed reactor, inner diameter 25.4 mm, length 750 mm;

[0046] Catalyst loading: 150 grams;

[0047] Reaction temperature: 270℃;

[0048] Reaction time: 1000 hours;

[0049] Raw material volume ratio: acrolein : air : water vapor = 1 : 3.2 : 2.1;

[0050] acrolein volume hourly space velocity: 105 h⁻¹ -1 .

[0051] Example 1

[0052] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 Dissolve 4H2O in 300mL of deionized water to obtain solution A; mix 100g of ethanol, 100g of deionized water and 600g of oleic acid evenly to obtain solution B;

[0053] (2) Solution A is added dropwise to solution B which is being stirred continuously, and then 25wt% ammonia solution is added dropwise until the pH value is 8;

[0054] (3) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 430°C for 4 hours to obtain catalyst precursor I.

[0055] (4) Add 390g of 25wt% nickel nitrate aqueous solution to 500g of catalyst precursor I powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0056] (5) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 385℃ for 20 hours in a mixed atmosphere of H2 / N2=3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0057] In the catalyst obtained in Example 1, the active component accounted for 67 parts and the support accounted for 33 parts.

[0058] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0059] Example 2

[0060] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 Dissolve 4H2O in 300mL of deionized water to obtain solution A; mix 100g of ethanol, 100g of deionized water and 600g of oleic acid evenly to obtain solution B;

[0061] (2) Solution A is added dropwise to solution B which is being stirred continuously, and then 25wt% ammonia solution is added dropwise until the pH value is 8;

[0062] (3) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 430°C for 4 hours to obtain catalyst precursor I.

[0063] (4) Add 304 g of 25 wt% copper nitrate aqueous solution to 500 g of catalyst precursor I powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0064] (5) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 385℃ for 20 hours in a mixed atmosphere with a volume ratio of H2 / N2 = 3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0065] In the catalyst obtained in Example 2, the active component accounted for 67 parts and the support accounted for 33 parts.

[0066] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0067] Example 3

[0068] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 Dissolve 4H2O in 300mL of deionized water to obtain solution A; mix 100g of ethanol, 100g of deionized water and 600g of oleic acid evenly to obtain solution B;

[0069] (2) Solution A is added dropwise to solution B which is being stirred continuously, and then 25wt% ammonia solution is added dropwise until the pH value is 8;

[0070] (3) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 430°C for 4 hours to obtain catalyst precursor I.

[0071] (4) Add 100g of 26.7wt% ammonium metatungstate aqueous solution to 500g of catalyst precursor powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0072] (5) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 385℃ for 20 hours in a mixed atmosphere with a volume ratio of H2 / N2 = 3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0073] In the catalyst obtained in Example 3, the active component accounted for 67 parts and the support accounted for 33 parts.

[0074] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0075] Example 4

[0076] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 Dissolve 4H2O in 300mL of deionized water to obtain solution A; mix 100g of ethanol, 100g of deionized water and 600g of oleic acid evenly to obtain solution B;

[0077] (2) Solution A is added dropwise to solution B which is being stirred continuously, and then 25wt% ammonia solution is added dropwise until the pH value is 8;

[0078] (3) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 430°C for 4 hours to obtain catalyst precursor I.

[0079] (4) Add 100g of a suspension of 25wt% Sb2O3 water to 500g of catalyst precursor powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0080] (5) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 385℃ for 20 hours in a mixed atmosphere with a volume ratio of H2 / N2 = 3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0081] In the catalyst obtained in Example 4, the active component accounted for 67 parts and the support accounted for 33 parts.

[0082] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0083] Example 5

[0084] The method of Example 1 is different in that the first calcination in step (3) is: calcination at 500°C in air for 4 hours;

[0085] In the catalyst obtained in Example 5, the active component accounted for 67 parts and the support accounted for 33 parts.

[0086] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0087] Example 6

[0088] The method of Example 1 is different in that the first calcination in step (3) is: calcination at 400°C in air for 4 hours;

[0089] In the catalyst obtained in Example 6, the active component accounted for 67 parts and the support accounted for 33 parts.

[0090] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0091] Example 7

[0092] The method is the same as in Example 1, except that the second calcination in step (5) is: calcination at 300°C for 20 hours in a mixed atmosphere of H2 / N2 = 3 / 97.

[0093] In the catalyst obtained in Example 7, the active component accounted for 67 parts and the support accounted for 33 parts.

[0094] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0095] Example 8

[0096] The method is the same as in Example 1, except that in step (4), 390 grams of 45wt% nickel nitrate aqueous solution is added to 500 grams of catalyst precursor I powder.

[0097] In the catalyst obtained in Example 8, the active component accounted for 68 parts and the support accounted for 32 parts.

[0098] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0099] Example 9

[0100] The method is the same as in Example 1, except that in step (4), 500 grams of 45wt% nickel nitrate aqueous solution is added to 500 grams of catalyst precursor I powder.

[0101] In the catalyst obtained in Example 9, the active component accounted for 69 parts and the support accounted for 31 parts.

[0102] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0103] Example 10

[0104] The difference from Example 8 is that 50g of ethanol and 50g of 1-propanol were used instead of 100g of ethanol.

[0105] In the catalyst obtained in Example 10, the active component accounted for 68 parts and the support accounted for 32 parts.

[0106] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0107] Example 11

[0108] The difference from Example 8 is that 400g of oleic acid and 200g of stearic acid were used instead of 600g of oleic acid.

[0109] In the catalyst obtained in Example 11, the active component accounted for 68 parts and the support accounted for 32 parts.

[0110] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0111] Comparative Example 1

[0112] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 Dissolve 4H2O in 300mL of deionized water to obtain solution A; add 25wt% ammonia solution dropwise until pH=8;

[0113] (2) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 430°C for 4 hours to obtain catalyst precursor I.

[0114] (3) Add 390g of 25wt% nickel nitrate aqueous solution to 500g of catalyst precursor I powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0115] (4) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 385℃ for 20 hours in a mixed atmosphere with a volume ratio of H2 / N2 = 3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0116] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0117] Comparative Example 2

[0118] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24Dissolve 4H2O in 300mL of deionized water to obtain solution A; mix 100g of ethanol and 100g of deionized water thoroughly to obtain solution B;

[0119] (2) Solution A is added dropwise to solution B which is being stirred continuously, and then 25wt% ammonia solution is added dropwise until the pH value is 8;

[0120] (3) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 430°C for 4 hours to obtain catalyst precursor I.

[0121] (4) Add 390g of 25wt% nickel nitrate aqueous solution to 500g of catalyst precursor I powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0122] (5) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 385℃ for 20 hours in a mixed atmosphere with a volume ratio of H2 / N2 = 3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0123] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0124] Comparative Example 3

[0125] (1) Mix 22.0 g of ammonium metavanadate (NH4VO3) and 100.0 g of ammonium heptamolybdate ((NH4)6Mo7O 24 Dissolve 4H2O in 300mL of deionized water to obtain solution A; mix 100g of ethanol, 100g of deionized water and 600g of oleic acid evenly to obtain solution B;

[0126] (2) Solution A is added dropwise to solution B which is being stirred continuously, and then 25wt% ammonia solution is added dropwise until the pH value is 8;

[0127] (3) The obtained suspension was transferred to an oven and dried at 80°C for 48 hours. The powder was then pulverized and calcined in air at 450°C for 4 hours to obtain catalyst precursor I.

[0128] (4) Add 390g of 25wt% nickel nitrate aqueous solution to 500g of catalyst precursor I powder, stir and grind evenly, then transfer to an oven to dry and pulverize to obtain catalyst precursor II;

[0129] (5) Take 100g of the obtained precursor II, 5g of hydroxypropyl cellulose, 40g of SiO2, 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 it at 450℃ for 4 hours in a mixed atmosphere with a volume ratio of H2 / N2 = 3 / 97 to obtain the catalyst for synthesizing acrylic acid.

[0130] The pore structure of the catalyst obtained by nitrogen adsorption-desorption testing is shown in Appendix Table 1. The peak intensity ratios of 2θ = 24.9 and 2θ = 22.2 obtained by XRD testing are shown in Table 2. The catalyst was evaluated using the aforementioned catalyst evaluation methods, and the results are shown in Table 3.

[0131] Table 1 shows the specific surface area, total pore volume, and pore ratio of the catalysts obtained in each example.

[0132]

[0133] Table 2 shows the XRD intensity values ​​and ratios of the catalysts obtained for each example at 2θ = 24.9 and 2θ = 22.2.

[0134] Example 1 228 1475 0.123 53.6 Example 2 227 1472 0.124 50.7 Example 3 225 1473 0.122 51.6 Example 4 226 1476 0.121 54.4 Example 5 229 1475 0.123 53.8 Example 6 230 1473 0.126 51.2 Example 7 227 1477 0.121 55.5 Example 8 224 1475 0.120 53.8 Example 9 233 1476 0.125 54.9 Example 10 439 1474 0.272 52.5 Example 11 552 1475 0.351 53.1 Comparative Example 1 830 1485 0.551 26.3 Comparative Example 2 839 1495 0.552 30.3 Comparative Example 3 831 1480 0.554 24.3

[0135] Table 3 shows the catalyst activity test results for each example.

[0136]

[0137]

[0138] The embodiments described above are merely detailed descriptions of the technical solutions of the present invention, but the present invention is not limited to the above embodiments, that is, the present invention does not depend on the steps described in the above embodiments to be implemented. In summary, any improvements made to the present invention by those skilled in the art, including the substitution of the raw materials and additives described in the present invention, the selection of specific implementation methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A catalyst for synthesizing acrylic acid, characterized in that, The catalyst comprises a catalyst having the general formula MO. x / Mo3VO 11 The active component, x, represents the number of oxygen atoms satisfying the partial reduction valence; where M is selected from one or more of Cu, W, Ni, and Sb; the active component is Mo3VO 11 It exhibits directional growth characteristics, and the peak intensity ratio of the characteristic peaks at 2θ=24.9 and 2θ=22.2 in the XRD pattern of the catalyst is 0.10~0.40; in the catalyst, based on the mass of the active component, MO x The content of the catalyst is 0.1%~12%; the catalyst has a hierarchical pore distribution, the first-level pore size is 2~50nm (excluding 50nm micropores), and the pore volume of the first-level pores accounts for 10%~50% of the total pore volume; the second-level pore size is 50~1000nm macropores, and the pore volume of the second-level pores accounts for 50%~90% of the total pore volume; the specific surface area of ​​the catalyst is 1~50m². 2 / g, total pore volume: 0.001~0.1cm 3 / g.

2. The catalyst for synthesizing acrylic acid according to claim 1, characterized in that: General formula MO x / Mo3VO 11 M in this context stands for Ni.

3. The catalyst for synthesizing acrylic acid according to claim 1, characterized in that: In the catalyst, MO is based on the mass of the active component. x The content is 5%~12%.

4. The catalyst for synthesizing acrylic acid according to claim 1, characterized in that: The catalyst includes a support on which the active component is loaded.

5. The catalyst for synthesizing acrylic acid according to claim 4, characterized in that: The support is selected from one or more of SiO2, Al2O3, ZrO2 and TiO2.

6. The catalyst for synthesizing acrylic acid according to claim 1, characterized in that: Based on 100 parts by mass of the catalyst, the catalyst comprises 20 to 90 parts by mass of an active component and 10 to 80 parts by mass of a support.

7. The catalyst for synthesizing acrylic acid according to claim 1, characterized in that: The total pore volume of the catalyst is 0.01~0.07 cm³. 3 / g.

8. A method for preparing the catalyst according to any one of claims 1-7, comprising the following steps: (1) Dissolve V source and Mo source in water to obtain solution A, and mix alcohol, water and long-chain organic acid to obtain solution B; (2) Solution A is added dropwise to solution B, and the pH value is adjusted to obtain a suspension; (3) The obtained suspension was dried and pulverized, and then calcined for the first time to obtain catalyst precursor I; (4) Load M onto catalyst precursor I, dry and then pulverize to obtain catalyst precursor II; (5) The obtained catalyst precursor II is mixed with the support raw material, shaped, and calcined for the second time to obtain the catalyst for synthesizing acrylic acid.

9. The preparation method according to claim 8, characterized in that: The V source comprises ammonium heptamolybdate and / or its hydrate, and the Mo source comprises ammonium metavanadate and / or its hydrate; and / or, The alcohol is a C1-C6 monohydric alcohol or polyhydric alcohol; and / or, The long-chain organic acid is a C8-C18 organic acid.

10. The preparation method according to claim 9, characterized in that: The alcohol is one or more of methanol, ethanol, 1-propanol, 2-propanol, 1,3-propanediol and glycerol; the long-chain organic acid is one or more of oleic acid, linoleic acid, stearic acid, palmitic acid, octanoic acid, isooctanoic acid, arbutinic acid, n-decanoic acid, undecenoic acid, lauric acid and tetradecanoic acid.

11. The preparation method according to claim 10, characterized in that: The alcohol is one or more of ethanol, 1-propanol, and 2-propanol; the long-chain organic acid is one or more of oleic acid, linoleic acid, stearic acid, and palmitic acid.

12. The preparation method according to claim 11, characterized in that: The alcohol is a mixture of ethanol and 1-propanol, wherein the mass ratio of ethanol to 1-propanol is 0.1 to 10:1; the long-chain organic acid is a mixture of oleic acid and stearic acid, wherein the mass ratio of oleic acid to stearic acid is 1.5 to 5:

1.

13. The preparation method according to claim 8, characterized in that: The alcohol is ethanol, and the mass ratio of water to ethanol is 1:9 to 9:1; the mass ratio of long-chain organic acid to the total weight of water and ethanol is 2:8 to 8:2; and / or, The pH of the suspension is 7-12; and / or, The mass ratio of the total organic matter in solution B to the Mo source in solution A is 0.5~15:

1.

14. The preparation method according to claim 13, characterized in that: The alcohol is ethanol, and the mass ratio of water to ethanol is 1:5 to 5:1; the mass ratio of long-chain organic acid to the total weight of water and ethanol is 2:6 to 6:

2.

15. The preparation method according to claim 8, characterized in that: The first calcination temperature is 350~700℃, the calcination time is 0.5~100h, and the calcination atmosphere is an inert atmosphere, air, a mixture of an inert atmosphere and oxygen, or a mixture of an inert atmosphere and air; and / or, The second calcination is carried out at a temperature of 250-600℃ for 0.5-100 hours, in a calcination atmosphere of a mixture of reducing and inert gases, wherein the volume percentage of the reducing gas is 0.5%-4%; and / or, The temperature of the first roasting is 15-130℃ higher than that of the second roasting.

16. The preparation method according to claim 8, characterized in that, The source M is a soluble oxygen-containing salt and / or oxygen-containing salt hydrate selected from one or more elements of Cu, W, Ni, and Sb.

17. The use of the catalyst for synthesizing acrylic acid according to any one of claims 1 to 7 in the synthesis of acrylic acid.

18. The application according to claim 17, characterized in that, The application includes reacting the catalyst with acrolein at a reaction temperature of 240–320°C and a volume hourly space velocity of 70–150 h⁻¹. -1 .

19. The application according to claim 18, characterized in that, The reaction temperature was 265–295 °C, and the volume hourly space velocity was 90–115 h⁻¹. -1 .

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