A catalyst for preparing acrylic acid, its preparation method and application

Abstract

The present invention discloses a catalyst for preparing acrylic acid, a preparation method thereof, and an application thereof. The catalyst of the present invention comprises a carrier and an active component, and the active component comprises oxides of Mo, V, W, and Ce. The pore size distribution of the catalyst is as follows: the pore volume of pores with a pore diameter < 10 nm accounts for 20.4% to 27.4% of the total pore volume, the pore volume of pores with a pore diameter of 10 to 40 nm accounts for 36.5% to 42.5% of the total pore volume, the pore volume of pores with a pore diameter > 40 nm and ≤ 100 nm accounts for 21.7% to 29.7% of the total pore volume, and the pore volume of pores with a pore diameter > 100 nm accounts for 7.4% to 13.4% of the total pore volume. This catalyst can effectively improve the yield of acrylic acid.

Description

Technical Field

[0001] The present invention relates to a catalyst for preparing acrylic acid, a preparation method thereof, and an application thereof in the oxidation of acrolein to acrylic acid. Background Art

[0002] Acrolein is the simplest unsaturated aldehyde and an important intermediate in chemical synthesis. The largest application field is the synthesis of methionine, which is widely used in the synthesis of important chemical products such as methylpyridine, pyridine, glutaraldehyde, and acrylic acid. It can also be used as an important raw material for the synthesis of 1,3-propanediol. Acrolein has active chemical properties and complex synthesis processes, and is mainly used as an intermediate in the production of acrylic acid. Propylene can be selectively oxidized to prepare acrolein, or acrolein can be used as an intermediate to continue oxidation to produce acrylic acid. The active component of the catalyst used for the oxidation of acrolein to acrylic acid is generally an oxide of the Mo-V series, and other elements for improving the performance of the catalyst are added, such as W, Fe, Co, Cu, Nb, Sb, etc.

[0003] In industrial production, in order to improve the acrylic acid yield, a higher space velocity or a higher concentration of acrolein raw material is adopted. However, due to the general performance of the acrylic acid catalyst, a large amount of heat is generated in some catalyst beds during the reaction process to form a high-temperature region, which easily causes over-oxidation and reduces the catalyst yield. At the same time, it will also cause an increase in the abrasion of the acrylic acid catalyst or even damage. US7220698 discloses a catalyst for catalytic gas-phase oxidation of acrolein and a method for producing acrylic acid by catalytic gas-phase oxidation using the catalyst. This method uses a catalyst with Mo-V as essential components, and by introducing a trace amount of catalyst poison into the catalyst preparation process, the hot spot of the catalyst reaction bed is controlled to inhibit the thermal degradation of the catalyst. The acrolein conversion rate can reach 98.8%, but the acrylic acid yield still needs to be further improved. CN1210511A discloses a method for producing acrolein and acrylic acid, in which the preparation method of the composite oxide catalyst adopted is to co-precipitate the mixed solution of each element component (including Fe, Co, Mo, V, Bi, Ni, etc.), dry it into powder, then form it by tableting and extrusion, and finally calcine to obtain the composite oxide catalyst. This method improves the catalyst yield to a certain extent and reduces the temperature of the hot spot part, but it cannot operate efficiently and stably for a long time under high load conditions. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a catalyst for preparing acrylic acid, a preparation method thereof, and an application thereof, and the catalyst can effectively improve the acrylic acid yield.

[0005] The first aspect of the present invention provides a catalyst for preparing acrylic acid. Among them, the catalyst comprises a carrier and an active component, and the active component comprises oxides of Mo, V, W, and Ce. The pore size distribution of the catalyst is as follows: the pore volume of pores with a pore diameter < 10 nm accounts for 20.4% - 27.4% of the total pore volume, the pore volume of pores with a pore diameter of 10 - 40 nm accounts for 36.5% - 42.5% of the total pore volume, the pore volume of pores with a pore diameter > 40 nm and ≤ 100 nm accounts for 21.7% - 29.7% of the total pore volume, and the pore volume of pores with a pore diameter > 100 nm accounts for 7.4% - 13.4% of the total pore volume.

[0006] Furthermore, for the catalyst, its pore size distribution is preferably as follows: the pore volume of pores with a pore diameter < 10 nm accounts for 22.4% - 25.4% of the total pore volume, the pore volume of pores with a pore diameter of 10 - 40 nm accounts for 36.5% - 40.5% of the total pore volume, the pore volume of pores with a pore diameter > 40 nm and ≤ 100 nm accounts for 23.7% - 27.7% of the total pore volume, and the pore volume of pores with a pore diameter > 100 nm accounts for 9.4% - 11.4% of the total pore volume.

[0007] Furthermore, the specific surface area of the catalyst is 8.8 ± 2.0 m 2 / g, the total pore volume is 0.03 ± 0.02 cm 3 / g, the average pore diameter is 12.5 ± 3.0 nm, and the initial pressure P / P0 of the hysteresis loop is 0.45 - 0.65.

[0008] Furthermore, in the temperature-programmed reduction curve (H2-TPR) measured by a fully automatic chemisorption instrument, the reduction temperature range of the catalyst is 365 - 395 °C.

[0009] Furthermore, the general formula of the active component is expressed as: V2O5·aMoO3·bWO3·cCeO2·dXO m ·eZO n . Wherein X is at least one selected from Ru, Os, Rh, Ir, Pd, and Pt, and Z is at least one selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba. a is the molar ratio of MoO3 to V2O5, and the value of a is 3.0 - 12.0; b is the molar ratio of WO3 to V2O5, and the value of b is 0.1 - 1.0; c is the molar ratio of CeO2 to V2O5, and the value of c is 0.1 - 1.0; d is the molar ratio of XO m to V2O5, and the value of d is 0.1 - 1.0; e is the molar ratio of ZO n to V2O5, and the value of e is 0.1 - 1.0; m and n are the number of moles of oxygen atoms required to satisfy the element valence in the active component.

[0010] Further, the carrier is selected from at least one of lithium oxide, magnesium oxide, aluminum oxide, zirconium dioxide, silicon dioxide, titanium dioxide, vanadium dioxide, diatomite, kaolin, and pumice.

[0011] Further, based on the weight of the catalyst, the carrier content is 10% to 60%, preferably 20% to 40%, and the content of the active component is 40% to 90%, preferably 60% to 80%.

[0012] The second aspect of the present invention provides a method for preparing a catalyst for acrylic acid, comprising the following steps:

[0013] (1) Mix the active element precursor with water to obtain a mixed solution I;

[0014] (2) Mix isopropylamine, polyethylene oxide, and water to obtain a mixed solution II, and mix the mixed solution II with the mixed solution I obtained in step (1) to obtain a mixed solution III;

[0015] (3) Mix the mixed solution III with the catalyst carrier, and obtain the catalyst through drying and calcination.

[0016] Further, in step (1), among the active element precursors, the V element-containing precursor is selected from at least one of ammonium metavanadate and vanadyl sulfate, and / or the Mo element-containing precursor is selected from at least one of ammonium molybdate and molybdenum oxide, and / or the Ce element-containing precursor is selected from at least one of cerium nitrate and ammonium cerium nitrate, and / or the X element-containing precursor and the Z element-containing precursor are both selected from salts containing the corresponding elements, such as at least one of nitrates, ammonium salts, carbonates, etc.

[0017] Further, in step (1), the amount of water added only needs to satisfy the full dissolution of the active element precursor.

[0018] Further, in step (2), the molecular weight of polyethylene oxide is 200 to 20,000, preferably 400 to 800; the mass ratio of isopropylamine to polyethylene oxide is 0.1 to 2.0:1, preferably 0.5 to 1.0:1. In the mixed solution II, the total mass ratio of isopropylamine and polyethylene oxide to water is (5 to 80):1, preferably (10 to 40):1.

[0019] Further, the mass ratio of the mixed solution II to the mixed solution I is 0.01 to 0.2:1, preferably 0.05 to 0.1:1.

[0020] Further, after the mixed solution II is mixed with the mixed solution I obtained in step (1), the pH of the solution is adjusted with an acid-base adjusting solution to obtain a mixed solution III. The acid-base adjusting solution is generally at least one of nitric acid, citric acid, formic acid solution, ammonia water, etc. The pH value of the mixed solution III is 3 to 6, preferably 4 to 5.

[0021] Further, the standing time of the mixed solution III is 1 to 48 hours, preferably 6 to 18 hours. The standing temperature of the mixed solution III is 30 to 90 °C, preferably 40 to 60 °C.

[0022] Further, an atmosphere containing oxygen, such as air, should be introduced during the standing stage of the mixed solution III.

[0023] Further, the drying and calcination are carried out in a conventional manner. Among them, the drying conditions are: the drying temperature is 60 to 150 °C, and the drying time is 1 to 48 hours. The calcination conditions are: the calcination temperature is 300 to 500 °C, and the calcination time is 1 to 72 hours. The calcination is carried out in an inert atmosphere or an oxygen-containing atmosphere.

[0024] The third aspect of the present invention also provides an application of the above catalyst or the catalyst prepared by the above method in the oxidation of acrolein to acrylic acid.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The catalyst for preparing acrylic acid of the present invention has the most suitable pore size distribution. The inventors have found that the catalyst with this specific pore size distribution can effectively improve the yield of acrylic acid.

[0027] The preparation method of the catalyst of the present invention uses isopropylamine and polyethylene oxide in combination, and strictly controls the addition sequence and control conditions of each mixed solution, etc. Each step cooperates with each other, so that the finally obtained catalyst has a high yield of acrylic acid. Description of the Drawings

[0028] Figure 1 It is the adsorption and desorption curve graph (nitrogen physical adsorption and desorption method) of the catalysts obtained in Comparative Example 1 and Example 1.

[0029] Figure 2 It is the curve graph of the change of the reduction peak intensity of the catalysts obtained in Comparative Example 1, Comparative Example 3, and Example 1 with temperature. Detailed Embodiments

[0030] In the present invention, the specific surface area, pore size and distribution of the catalyst are measured by the nitrogen physical adsorption and desorption method (instrument model: Tristar-3000, Micromeritics Instrument Corporation, USA). Among them, the sample needs to be heat-treated at 220 °C for 3 h, the test temperature is -196 °C, and the test environment is liquid nitrogen. The catalyst evaluation method of the present invention is as follows:

[0031] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0032] Catalyst filling amount: 2 g;

[0033] Reaction temperature: 270 °C;

[0034] Reaction time: 4 hours;

[0035] Volume ratio of raw materials: Acrolein: Air: Steam = 1:8:2;

[0036] Total space velocity of the feed gas: 2200 h -1 .

[0037] Using the catalyst of the present invention, at a total volume space velocity of 2200 h -1 the acrylic acid yield can reach over 91%, achieving good technical effects and can be used in the industrial production of acrylic acid.

[0038]

Comparative Example 1

[0039] 1. Mix the active element liquids of each component to obtain mixture I

[0040] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mol of Na2O are respectively dissolved in hot water at 80 °C. After mixing all the active component liquids evenly, stir and evaporate at 80 °C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g to obtain the active component mixture I.

[0041] 2. Obtain mixture II and adjust the pH value

[0042] Take 200 g of the above-mentioned active component mixture I, cool it to room temperature, and use nitric acid at 0.1 mol / L to adjust the pH value to 4.5. Place it in air at 50 °C for 12 hours to obtain mixture II.

[0043] 3. Mix mixture II with the carrier, dry and calcine

[0044] Mix the above-mentioned mixture II evenly with 50 g of alumina powder carrier, and after forming, obtain catalyst precursor I. Dry catalyst precursor I in an oven at 80 °C for 4 hours, and then calcine it in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0045] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3。

[0046] 4. Catalyst evaluation

[0047] The evaluation method is as follows:

[0048] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0049] Catalyst filling amount: 2 g;

[0050] Reaction temperature: 270 °C;

[0051] Reaction time: 4 hours;

[0052] Volume ratio of raw materials: Acrolein: Air: Steam = 1:8:2;

[0053] Total space velocity of the raw material gas: 2200 h -1 .

[0054] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0055]

Comparative Example 2

[0056] 1. Mixing of each component active element liquid to obtain mixed liquid I

[0057] Dissolve ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mol of Na2O in hot water at 80 °C. After mixing all the active component liquids evenly, stir and evaporate at 80 °C until the concentration of the active component V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g to obtain the active component mixed liquid I.

[0058] 2. Obtaining of mixed liquid II and adjusting the pH value

[0059] Mix 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80 °C. After complete dissolution, obtain mixture II. Mix mixture II with 200 g of the above-mentioned active component mixture I, stir until it reaches room temperature, use 0.1 mol / L ammonia water to adjust the pH value to 7, and place it under air conditions at 50 °C for 12 hours to obtain mixture III.

[0060] 3. Mix mixture III with the carrier and dry and calcine.

[0061] Mix the above-mentioned mixture III evenly with 50 g of alumina powder carrier. After forming, obtain catalyst precursor I. Dry catalyst precursor I in an oven at 80 °C for 4 hours, and then calcine it in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0062] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0063] 4. Catalyst evaluation

[0064] The evaluation method is as follows:

[0065] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0066] Catalyst filling amount: 2 g;

[0067] Reaction temperature: 270 °C;

[0068] Reaction time: 4 hours;

[0069] Volume ratio of raw materials: acrolein: air: water vapor = 1:8:2;

[0070] Total space velocity of raw material gas: 2200 h -1 .

[0071] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0072]

Comparative Example 3

[0073] 1. Mix the active element solutions of each component to obtain mixture I

[0074] Mix ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, and ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41) Cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 moles of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 moles of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 moles of Na2O are respectively dissolved in hot water at 80 °C. After mixing all the active component solutions evenly, it is stirred and evaporated at 80 °C until the concentration of the active components equivalent to V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g, obtaining the active component mixed solution I.

[0075] 2. Obtaining the mixed solution II and adjusting the pH value

[0076] 1.2 g of isopropylamine and 0.4 g of polyethylene oxide (molecular weight 600) are mixed in 10 ml of deionized water at 80 °C. After complete dissolution, the mixed solution II is obtained. The mixed solution II is mixed with 200 g of the above-mentioned active component mixed solution I, stirred to room temperature, and the pH value is adjusted to 4.5 using 0.1 mol / L nitric acid, and it is left standing for 12 hours under air conditions at 50 °C, obtaining the mixed solution III.

[0077] 3. Mixing the mixed solution III with the carrier and drying and calcining

[0078] The above-mentioned mixed solution III is mixed evenly with 50 g of alumina powder carrier, and after forming, the catalyst precursor I is obtained. The catalyst precursor I is dried in an oven at 80 °C for 4 hours, and then calcined in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0079] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0080] 4. Catalyst evaluation

[0081] The evaluation method is as follows:

[0082] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0083] Catalyst filling amount: 2 g;

[0084] Reaction temperature: 270 °C;

[0085] Reaction time: 4 hours;

[0086] Volume ratio of raw materials: acrolein: air: water vapor = 1:8:2;

[0087] Total space velocity of the raw material gas: 2200 h -1 .

[0088] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0089]

Example 1

[0090] 1. Mix the active element solutions of each component to obtain mixture I

[0091] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mol of Na2O are respectively dissolved in hot water at 80°C. After mixing all the active component solutions evenly, stir and evaporate at 80°C until the concentration of the active components in the mixed material solution is equivalent to 0.5 g / g of V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O, obtaining the active component mixture I.

[0092] 2. Obtain mixture III and adjust the pH value

[0093] Mix 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80°C. After complete dissolution, obtain mixture II. Mix mixture II with 200 g of the above-mentioned active component mixture I, stir to room temperature, and use 0.1 mol / L nitric acid to adjust the pH value to 4.5. Place it under air conditions at 50°C for 12 hours to obtain mixture III.

[0094] 3. Mix mixture III with the carrier, dry, and calcine

[0095] Mix the above-mentioned mixture III evenly with 50 g of alumina powder carrier, and after forming, obtain catalyst precursor I. Dry catalyst precursor I in an oven at 80°C for 4 hours, and then calcine it in a muffle furnace at 400°C for 4 hours to obtain a catalyst with the following composition:

[0096] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0097] 4. Catalyst evaluation

[0098] The evaluation method is as follows:

[0099] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0100] Catalyst loading: 2 g;

[0101] Reaction temperature: 270 °C;

[0102] Reaction time: 4 hours;

[0103] Volume ratio of raw materials: Acrolein: Air: Steam = 1:8:2;

[0104] Overall volume space velocity: 2200 h -1 .

[0105] For comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0106]

Example 2

[0107] 1. Mix the active element liquids of each component to obtain mixture I

[0108] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mol of Na2O are dissolved in hot water at 80 °C respectively. After mixing all the active component liquids evenly, stir and evaporate at 80 °C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g to obtain the active component mixture I.

[0109] 2. Obtain mixture III and adjust the pH value

[0110] Mix 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80 °C. After complete dissolution, obtain mixture II. Mix mixture II with 200 g of the above-mentioned active component mixture I, stir to room temperature, and adjust the pH value to 3 using 0.1 mol / L nitric acid. Place it in air at 50 °C for 12 hours to obtain mixture III.

[0111] 3. Mix mixture III with the carrier, dry and calcine

[0112] Mix the above-mentioned mixed solution III with 50 g of alumina powder carrier evenly, and obtain catalyst precursor I after forming. Dry the catalyst precursor I in an oven at 80 °C for 4 hours, and then calcine it in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0113] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0114] 4. Catalyst evaluation

[0115] The evaluation method is as follows:

[0116] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0117] Catalyst filling amount: 2 g;

[0118] Reaction temperature: 270 °C;

[0119] Reaction time: 4 hours;

[0120] Volume ratio of raw materials: acrolein: air: steam = 1:8:2;

[0121] Total volume space velocity: 2200 h -1 .

[0122] For easy comparison, the element composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0123]

Example 3

[0124] 1. Mix the active element solutions of each component to obtain mixed solution I

[0125] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41), Cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 moles of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 moles of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 moles of Na2O are respectively dissolved in hot water at 80 °C. After mixing all the active component solutions evenly, it is stirred and evaporated at 80 °C until the concentration of the active components equivalent to V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g, obtaining the active component mixed solution I.

[0126] 2. Obtaining the mixed solution III and adjusting the pH value

[0127] 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) are mixed in 10 ml of deionized water at 80 °C. After complete dissolution, the mixed solution II is obtained. The mixed solution II is mixed with 200 g of the above-mentioned active component mixed solution I, stirred to room temperature, and the pH value is adjusted to 5.5 using 0.1 mol / L nitric acid, and then left standing for 12 hours under air conditions at 50 °C to obtain the mixed solution III.

[0128] 3. Mixing the mixed solution III with the carrier, drying and calcining

[0129] The above-mentioned mixed solution III is mixed evenly with 50 g of alumina powder carrier, and after forming, the catalyst precursor I is obtained. The catalyst precursor I is dried in an oven at 80 °C for 4 hours, and then calcined in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0130] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0131] 4. Catalyst evaluation

[0132] The evaluation method is as follows:

[0133] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0134] Catalyst filling amount: 2 g;

[0135] Reaction temperature: 270 °C;

[0136] Reaction time: 4 hours;

[0137] Volume ratio of raw materials: acrolein: air: water vapor = 1:8:2;

[0138] Total space velocity of the raw material gas: 2200 h -1 .

[0139] For the convenience of comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0140]

Example 4

[0141] 1. Mix the active element liquids of each component to obtain mixture I

[0142] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mole of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mole of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mole of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mole of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mole of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mole of Na2O are respectively dissolved in hot water at 80°C. After mixing all the active component liquids evenly, stir and evaporate at 80°C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g to obtain the active component mixture I.

[0143] 2. Obtain mixture III and adjust the pH value

[0144] Mix 0.14 g of isopropylamine and 1.4 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80°C. After complete dissolution, obtain mixture II. Mix mixture II with 200 g of the above-mentioned active component mixture I, stir to room temperature, and use 0.1 mole / liter of nitric acid to adjust the pH value to 4.5. Place it under air conditions at 50°C for 12 hours to obtain mixture III.

[0145] 3. Mix mixture III with the carrier, dry, and calcine

[0146] Mix the above-mentioned mixture III evenly with 50 g of alumina powder carrier, and after forming, obtain catalyst precursor I. Dry catalyst precursor I in an oven at 80°C for 4 hours, and then calcine it in a muffle furnace at 400°C for 4 hours to obtain a catalyst with the following composition:

[0147] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0148] 4. Catalyst evaluation

[0149] The evaluation method is as follows:

[0150] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0151] Catalyst loading: 2 g;

[0152] Reaction temperature: 270 °C;

[0153] Reaction time: 4 h;

[0154] Volume ratio of raw materials: Acrolein: Air: Steam = 1:8:2;

[0155] Total space velocity of raw material gas: 2200 h -1 .

[0156] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0157]

Example 5

[0158] 1. Mix the active elements of each component to obtain mixture I

[0159] Dissolve ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mol of Na2O in hot water at 80 °C respectively. After mixing all the active component solutions evenly, stir and evaporate at 80 °C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g to obtain the active component mixture I.

[0160] 2. Obtain mixture III and adjust the pH value

[0161] Mix 1 g of isopropylamine and 0.5 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80 °C. After complete dissolution, obtain mixture II. Mix mixture II with 200 g of the above-mentioned active component mixture I, stir to room temperature, and adjust the pH value to 4.5 using 0.1 mol / L nitric acid. Place it in air at 50 °C for 12 hours to obtain mixture III.

[0162] 3. Mix mixture III with the carrier, dry, and calcine

[0163] Mix the above-mentioned mixed solution III with 50 g of alumina powder carrier evenly, and obtain catalyst precursor I after molding. Dry catalyst precursor I in an oven at 80 °C for 4 hours, and then calcine it in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0164] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5Na2O + 33 w% Al2O3.

[0165] 4. Catalyst evaluation

[0166] The evaluation method is as follows:

[0167] Reactor: Fixed-bed micro reactor, inner diameter 10 mm, reactor length 330 mm;

[0168] Catalyst filling amount: 2 g;

[0169] Reaction temperature: 270 °C;

[0170] Reaction time: 4 hours;

[0171] Volume ratio of raw materials: acrolein: air: water vapor = 1:8:2;

[0172] Total space velocity of raw material gas: 2200 h -1 .

[0173] For easy comparison, the element composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0174]

Example 6

[0175] 1. Mix the active element liquids of each component to obtain mixed solution I

[0176] Dissolve ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and potassium hydroxide (molecular formula: KOH) containing 0.05 mol of K2O in hot water at 80 °C respectively. After mixing all the active component liquids evenly, stir and evaporate at 80 °C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5K2O in the mixed material solution is 0.5 g / g to obtain active component mixed solution I.

[0177] 2. Obtaining Mixed Solution III and Adjusting pH Value

[0178] Mix 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80 °C. After complete dissolution, obtain Mixed Solution II. Mix Mixed Solution II with 200 g of the above-mentioned active component Mixed Solution I, stir until room temperature, and use 0.1 mol / L nitric acid to adjust the pH value to 4.5. Place it under air condition at 50 °C for 12 hours to obtain Mixed Solution III.

[0179] 3. Mixing Mixed Solution III with Carrier, Drying, and Calcining

[0180] Mix the above-mentioned Mixed Solution III evenly with 50 g of alumina powder carrier. After forming, obtain Catalyst Precursor I. Dry Catalyst Precursor I in an oven at 80 °C for 4 hours, and then calcine it in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0181] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·0.5K2O + 33 w% Al2O3.

[0182] 4. Catalyst Evaluation

[0183] The evaluation method is as follows:

[0184] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0185] Catalyst filling amount: 2 g;

[0186] Reaction temperature: 270 °C;

[0187] Reaction time: 4 hours;

[0188] Volume ratio of raw materials: acrolein: air: steam = 1:8:2;

[0189] Overall volume space velocity: 2200 h -1 .

[0190] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0191]

Example 7

[0192] 1. Mixing Active Element Liquids of Each Component to Obtain Mixed Solution I

[0193] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mole of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mole of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mole of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mole of CeO2, palladium nitrate (molecular formula: Pd(NO3)2) containing 0.1 mole of PdO, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mole of Na2O were separately dissolved in hot water at 80°C. After mixing all the active component solutions evenly, the mixture was stirred and evaporated at 80°C until the concentration of the active components in the mixed material solution was equivalent to 0.5 g / g of V2O5·6MoO3·0.5WO3·0.5CeO2·PdO·0.5Na2O, obtaining the active component mixed solution I.

[0194] 2. Obtaining mixed solution III and adjusting the pH value

[0195] 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) were mixed in 10 ml of deionized water at 80°C. After complete dissolution, mixed solution II was obtained. Mixed solution II was mixed with 200 g of the above-mentioned active component mixed solution I, stirred to room temperature, and the pH value was adjusted to 4.5 using 0.1 mol / L nitric acid. It was left standing for 12 hours under air conditions at 50°C to obtain mixed solution III.

[0196] 3. Mixing mixed solution III with the carrier, drying, and calcining

[0197] The above-mentioned mixed solution III was mixed evenly with 50 g of alumina powder carrier, and after forming, catalyst precursor I was obtained. Catalyst precursor I was dried in an oven at 80°C for 4 hours, and then calcined in a muffle furnace at 400°C for 4 hours to obtain a catalyst with the following composition:

[0198] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·PdO·0.5Na2O + 33 w% Al2O3.

[0199] 4. Catalyst evaluation

[0200] The evaluation method is as follows:

[0201] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0202] Catalyst filling amount: 2 g;

[0203] Reaction temperature: 270°C;

[0204] Reaction time: 4 hours;

[0205] Raw material volume ratio: acrolein: air: steam = 1:8:2;

[0206] Total volume space velocity: 2200 h -1 .

[0207] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0208]

Example 8

[0209] 1. Mix the active element liquids of each component to obtain mixture I

[0210] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mole of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mole of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mole of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mole of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.2 mole of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.05 mole of Na2O are respectively dissolved in hot water at 80°C. After all the active component liquids are mixed evenly, they are stirred and evaporated at 80°C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·2Rh2O3·0.5Na2O in the mixed material solution is 0.5 g / g, obtaining the active component mixture I.

[0211] 2. Obtain mixture III and adjust the pH value

[0212] 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) are mixed in 10 ml of deionized water at 80°C. After complete dissolution, mixture II is obtained. Mixture II is mixed with 200 g of the above-mentioned active component mixture I, stirred to room temperature, and the pH value is adjusted to 4.5 using 0.1 mol / L nitric acid. It is left standing for 12 hours under air conditions at 50°C to obtain mixture III.

[0213] 3. Mix mixture III with the carrier, dry, and calcine

[0214] The above-mentioned mixture III is mixed evenly with 50 g of alumina powder carrier, and after forming, catalyst precursor I is obtained. Catalyst precursor I is dried in an oven at 80°C for 4 hours, and then calcined in a muffle furnace at 400°C for 4 hours to obtain a catalyst with the following composition:

[0215] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·2Rh2O3·0.5Na2O + 33 w% Al2O3。

[0216] 4. Catalyst Evaluation

[0217] The evaluation method is as follows:

[0218] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0219] Catalyst filling amount: 2 g;

[0220] Reaction temperature: 270 °C;

[0221] Reaction time: 4 hours;

[0222] Volume ratio of raw materials: Acrolein: Air: Steam = 1:8:2;

[0223] Overall volume space velocity: 2200 h -1 .

[0224] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0225]

Example 9

[0226] 1. Mix the active element liquids of each component to obtain a mixed liquid I

[0227] Ammonium metavanadate (molecular formula: NH4VO3) containing 0.1 mol of V2O5, ammonium molybdate (molecular formula: (NH4)2MoO4) containing 0.6 mol of MoO3, ammonium tungstate (molecular formula: (NH4) 10 W 12 O 41 ) containing 0.05 mol of WO3, cerium nitrate (molecular formula: Ce(NO3)3) containing 0.05 mol of CeO2, rhodium nitrate (molecular formula: Rh(NO3)3) containing 0.05 mol of Rh2O3, and sodium hydroxide (molecular formula: NaOH) containing 0.2 mol of Na2O are respectively dissolved in hot water at 80 °C. After mixing all the active component liquids evenly, stir and evaporate at 80 °C until the concentration of the active components V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·2Na2O in the mixed material solution is 0.5 g / g to obtain the active component mixed liquid I.

[0228] 2. Obtain the mixed liquid III and adjust the pH value

[0229] Mix 0.5 g of isopropylamine and 1 g of polyethylene oxide (molecular weight 600) in 10 ml of deionized water at 80 °C. After complete dissolution, obtain mixture II. Mix mixture II with 200 g of the above-mentioned active component mixture I, stir to room temperature, use 0.1 mol / L nitric acid to adjust the pH value to 4.5, and place it under air conditions at 50 °C for 12 hours to obtain mixture III.

[0230] 3. Mix mixture III with the carrier, dry, and calcine

[0231] Mix the above-mentioned mixture III evenly with 50 g of alumina powder carrier. After forming, obtain catalyst precursor I. Dry catalyst precursor I in an oven at 80 °C for 4 hours, and then calcine it in a muffle furnace at 400 °C for 4 hours to obtain a catalyst with the following composition:

[0232] 67 w% V2O5·6MoO3·0.5WO3·0.5CeO2·0.5Rh2O3·2Na2O + 33 w% Al2O3.

[0233] 4. Catalyst evaluation

[0234] The evaluation method is as follows:

[0235] Reactor: Fixed-bed micro-reactor, inner diameter 10 mm, reactor length 330 mm;

[0236] Catalyst filling amount: 2 g;

[0237] Reaction temperature: 270 °C;

[0238] Reaction time: 4 hours;

[0239] Raw material volume ratio: acrolein: air: water vapor = 1:8:2;

[0240] Total volume space velocity: 2200 h -1 .

[0241] For easy comparison, the elemental composition of the catalyst and the evaluation results of the catalyst are listed in Table 1.

[0242] Table 1 Properties of the catalysts obtained in the examples and comparative examples

[0243]

[0244] Table 2 Evaluation results of the catalysts obtained in the examples and comparative examples

[0245]

[0246]

Claims

1. A catalyst for preparing acrylic acid, the catalyst comprising a carrier and an active component, the active component comprising oxides of Mo, V, W, and Ce, and the pore size distribution of the catalyst being as follows: the pore volume of pores with a pore diameter < 10 nm accounts for 20.4% - 27.4% of the total pore volume, the pore volume of pores with a pore diameter of 10 - 40 nm accounts for 36.5% - 42.5% of the total pore volume, the pore volume of pores with a pore diameter > 40 nm and ≤ 100 nm accounts for 21.7% - 29.7% of the total pore volume, and the pore volume of pores with a pore diameter > 100 nm accounts for 7.4% - 13.4% of the total pore volume; The general formula of the active component is expressed as: V2O5·aMoO3·bWO3·cCeO2·dXO m ·eZO n ; where X is at least one selected from Ru, Os, Rh, Ir, Pd, and Pt, and Z is at least one selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba; a is the molar ratio of MoO3 to V2O5, and the value of a ranges from 3.0 to 12.0; b is the molar ratio of WO3 to V2O5, and the value of b ranges from 0.1 to 1.0; c is the molar ratio of CeO2 to V2O5, and the value of c ranges from 0.1 to 1.0; d is the molar ratio of XO m to V2O5, and the value of d ranges from 0.1 to 1.0; e is the molar ratio of ZO n to V2O5, and the value of e ranges from 0.1 to 1.0; m and n are the number of moles of oxygen atoms required to satisfy the element valence in the active component.

2. The catalyst according to claim 1, characterized in that: For the catalyst, its pore size distribution is as follows: the pore volume of pores with a pore diameter < 10 nm accounts for 22.4% - 25.4% of the total pore volume, the pore volume of pores with a pore diameter of 10 - 40 nm accounts for 36.5% - 40.5% of the total pore volume, the pore volume of pores with a pore diameter > 40 nm and ≤ 100 nm accounts for 23.7% - 27.7% of the total pore volume, and the pore volume of pores with a pore diameter > 100 nm accounts for 9.4% - 11.4% of the total pore volume.

3. The catalyst according to claim 1, wherein: The specific surface area of the catalyst is 8.8 ± 2.0 m 2 / g, the total pore volume is 0.03 ± 0.02 cm 3 / g, the average pore diameter is 12.5 ± 3.0 nm, and the starting pressure P / P0 of the hysteresis loop is 0.45 to 0.

65.

4. The catalyst according to claim 1, characterized in that: In the temperature-programmed reduction curve measured by a full-automatic chemisorption instrument for the catalyst, the reduction temperature ranges from 365 to 395 °C.

5. The catalyst according to claim 1, characterized in that: The carrier is selected from at least one of lithium oxide, magnesium oxide, aluminum oxide, zirconium dioxide, silicon dioxide, titanium dioxide, vanadium dioxide, diatomaceous earth, kaolin, and pumice.

6. The catalyst according to claim 1, characterized in that: Based on the weight of the catalyst, the carrier content is 10% - 60%, and the content of the active component is 40% - 90%.

7. The catalyst according to claim 6, characterized in that: Based on the weight of the catalyst, the carrier content is 20% - 40%, and the content of the active component is 60% - 80%.

8. A method for preparing the catalyst according to any one of claims 1 - 7, comprising the following steps: (1) Mix the active element precursor with water to obtain a mixed solution I; (2) Mix isopropylamine, polyethylene oxide, and water to obtain a mixed solution II, and mix the mixed solution II with the mixed solution I obtained in step (1) to obtain a mixed solution III; (3) Mix the mixed solution III with the catalyst carrier, and after drying and calcination, obtain the catalyst.

9. The preparation method according to claim 8, characterized in that: In step (2), the molecular weight of polyethylene oxide is 200 - 20000; the mass ratio of isopropylamine to polyethylene oxide is 0.1 - 2.0:1; in the mixed solution II, the mass ratio of the total mass of isopropylamine and polyethylene oxide to the mass of water is (5 - 80):

1.

10. The preparation method according to claim 9, characterized in that: In step (2), the molecular weight of polyethylene oxide is 400 - 800; the mass ratio of isopropylamine to polyethylene oxide is 0.5 - 1.0:1; in the mixed solution II, the mass ratio of the total mass of isopropylamine and polyethylene oxide to the mass of water is (10 - 40):

1.

11. According to the preparation method described in claim 8, characterized in that: The mass ratio of the mixed solution II to the mixed solution I is 0.01 - 0.2:

1.

12. The preparation method according to claim 11, wherein: The mass ratio of the mixed solution II to the mixed solution I is 0.05 - 0.1:

1.

13. The preparation method according to claim 8, wherein: The standing time of the mixed solution III is 1 - 48 hours; the standing temperature of the mixed solution III is 30 - 90 °C.

14. The preparation method according to claim 13, characterized in that: The standing time of the mixed solution III is 6 - 18 hours; the standing temperature of the mixed solution III is 40 - 60 °C.

15. The preparation method according to claim 8, characterized in that: The drying conditions are as follows: the drying temperature is 60 to 150 °C, and the drying time is 1 to 48 hours; the calcination conditions are as follows: the calcination temperature is 300 to 500 °C, and the calcination time is 1 to 72 hours.

16. Use of the catalyst according to any one of claims 1-7 or the catalyst prepared by the method according to any one of claims 8-15 in the oxidation of acrolein to acrylic acid.

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