WO2021103894A1

WO2021103894A1 - Molybdenum-vanadium composite oxide catalyst, preparation method therefor and use thereof

Info

Publication number: WO2021103894A1
Application number: PCT/CN2020/123868
Authority: WO
Inventors: 翟夫朋; 李雪梅; 冯世强; 庄岩
Original assignee: 上海华谊新材料有限公司
Priority date: 2019-11-25
Filing date: 2020-10-27
Publication date: 2021-06-03
Also published as: CN110694635A

Abstract

Disclosed are a molybdenum-vanadium composite oxide catalyst, a preparation method therefor and a use thereof. In the catalyst, X is selected from Nb, Sb, Te, Zn, Ca, and Bi; Y is selected from Nd, La, Ce, W, and Cu; and Z is selected from Cd, Sr, Sb, B, and Ni; a=1-20; b=0.05-10; c=0-5; d=0.01-4; e=0.01-5; g=0.05-15; h=0.01-5; i=0-4; j=0-3; f and k are values that satisfy each atomic valence state; and m/n is 0.5-5. The catalyst is obtained by the following method: (1) dissolving precursor compounds Mo, V, W, Cu and X by using a predetermined ratio, and drying to obtain the following formula A particles: MoaVbWcCudXeOf; (2) dissolving precursor compounds Mo, V, Y and Z by using a predetermined ratio to obtain a solution B of the following formula: MogVhYiZjOk; and (3) dispersing the A particles into the solution B, drying, and roasting to obtain a catalyst. [MoaVbWcCudXeOf]m[MogVhYiZjOk]n

Description

Molybdenum vanadium composite oxide catalyst, its preparation method and application

Technical field

The invention relates to a molybdenum vanadium series composite metal oxide catalyst, which is used for the catalytic oxidation reaction of preparing acrylic acid by oxidation of acrolein. The catalyst of the present invention has good activity at a lower temperature, is beneficial to prolong the service life of the catalyst, and is very suitable for application in industrial devices. The invention also relates to a preparation method of the molybdenum-vanadium composite metal oxide catalyst and its use in the catalytic oxidation reaction of preparing acrylic acid by oxidation of acrolein.

Background technique

Acrylic acid is an important organic chemical product. In industry, it is mainly prepared from propylene through a two-step catalytic oxidation method, that is, propylene is oxidized to acrolein, and the generated aldehyde is further oxidized to generate acrylic acid. For the oxidation reaction of acrolein to acrylic acid, Mo-V series composite metal oxide catalysts have been extensively studied and used in industrial production equipment to obtain acrylic acid with high yields.

At present, many patents have been granted to the preparation methods of Mo-V series composite metal oxide catalysts, such as Chinese patents CN103769148A, CN103521234A, CN102451702B, CN104399483B, CN103894204B, CN101507927A, CN103721756A and CN104646014A. The catalysts described in these patents are mostly prepared by dissolving the precursor compound in water to form a solution, adding insoluble oxides or carriers, heating and stirring, and then evaporating to dryness, pulverizing, forming, and calcining.

However, the catalyst prepared by the above preparation method has the disadvantages of insufficient catalytic activity and low yield of acrylic acid.

In addition, some patents have been granted to the step-by-step preparation method of Mo-V series composite metal oxide catalysts. For example, Chinese patents CN104923247B and CN105080558B published two-phase mixing method for preparing catalysts; Chinese patents CN105664961A and CN108421550A published solid dry mixing methods. Preparation of the catalyst.

However, the catalyst prepared by the above preparation method has unavoidable shortcomings: one is the uneven distribution of the active phase, which leads to the local production of excessive carbon oxide during the catalytic reaction; the other is the excessive distribution of the effective active phase in the bulk phase, which leads to the utilization rate. Decrease, and affect the stability of the catalyst.

In view of the current state of the art, there is still a need in the art to develop a method for manufacturing a Mo-V-based composite oxide catalyst. The preparation method of the catalyst is highly designable, easy to control, and can effectively improve the utilization rate of the active components of the catalyst. The catalyst obtained by the method has high activity, selectivity and stability in the catalytic oxidation reaction of acrolein to prepare acrylic acid.

Summary of the invention

An object of the present invention is to provide a method for preparing a Mo-V composite metal oxide catalyst. The catalyst prepared by the method of the present invention has a controllable catalyst while maintaining or improving the catalytic activity and product selectivity of the catalyst. Distribution of active ingredients.

Another object of the present invention is to provide a Mo-V composite metal oxide catalyst prepared by the method of the present invention.

Another object of the present invention is to provide the use of the catalyst of the present invention in the production of acrylic acid from the oxidation of acrolein.

Therefore, one aspect of the present invention relates to a molybdenum-vanadium-based composite metal oxide catalyst, which has the following general formula:

[Mo _a V _b W _c Cu _d X _e O _f ] _m [Mo _g V _h Y _i Z _j O _k ] _n

among them,

X is a mixture of one or more of Nb, Sb, Te, Zn, Ca, and Bi in any ratio;

Y is a mixture of one or more of Nd, La, Ce, W, and Cu in any ratio;

Z is a mixture of one or more of Cd, Sr, Sb, B, and Ni in any ratio;

a=1-20;

b=0.05-10;

c=0-5;

d=0.1-4;

e=0.01-5;

g=0.05-15;

h=0.01-5;

i=0-4;

j=0-3;

f and k are values determined to satisfy the valence states of each atom;

m/n is 0.5-5;

The catalyst is prepared by the following method:

(1) The Mo, V, W, Cu, and X precursor compounds are dissolved in a predetermined ratio to obtain a solution, and dried to obtain solid particles of oxide A with the following general formula:

Mo _a V _b W _c Cu _d X _e O _f ;

(2) The precursor compounds of Mo, V, Y, and Z are dissolved in a predetermined ratio to obtain solution B. The ratio of the elements of Mo, V, Y, and Z meets:

Mo _g V _h Y _i Z _j O _k ;

(3) Disperse the solid particles of oxide A in solution B, dry, and calcinate to obtain a catalyst.

Another aspect of the present invention relates to a method for preparing the above-mentioned molybdenum-vanadium composite oxide catalyst, which includes the following steps:

Mo _a V _b W _c Cu _d X _e O _f ;

Mo _g V _h Y _i Z _j O _k ;

Another aspect of the present invention relates to the use of the above-mentioned catalyst in the oxidation reaction of acrolein to acrylic acid.

Detailed ways

The present invention generally relates to a method for controlling and designing the phase structure and active component distribution of the catalyst through a stepwise preparation method and improving the activity and selectivity of the catalyst. The step-by-step preparation method of the present invention is an immersion preparation method. It first prepares a part of the catalyst precursor by a direct mixing method, and then is dried and pulverized to obtain solid particles; and then prepares another part of the precursor solution to combine the precursor prepared in the previous step. The solid particles are added in an appropriate ratio and appropriate method, impregnated, and together form a catalyst precursor with controllable structure, high activity and high selectivity.

1. Composite metal oxide catalyst

The invention relates to a molybdenum vanadium series (Mo-V) composite metal oxide catalyst, which has the following general formula:

[Mo _a V _b W _c Cu _d X _e O _f ] _m [Mo _g V _h Y _i Z _j O _k ] _n

among them

X is a mixture of one or more of Nb, Sb, Te, Zn, Ca, and Bi in any ratio, preferably a mixture of one or more of Nb, Sb, Te, and Zn in any ratio, more It is preferably a mixture of one or more of Nb, Sb, and Te in any ratio, preferably Nb, Sb or a mixture thereof;

Y is a mixture of one or more of Nd, La, Ce, W, and Cu in any ratio, preferably a mixture of one or more of Nd, La, Ce, and W in any ratio, more preferably One or more of Nd, La, W, preferably La, W or a mixture thereof;

Z is a mixture of one or more of Cd, Sr, Sb, B, and Ni in any ratio, preferably a mixture of one or more of Cd, Sb, and Ni in any ratio, more preferably Sb, Ni or its mixture;

a=1-20, preferably 1.2-16, more preferably 1.4-12, preferably 1.5-10, preferably 1.6-8;

b=0.05-10, preferably 0.1-8, more preferably 0.15-6, preferably 0.2-4, preferably 0.25-2;

c=0-5, preferably 0.1-4, more preferably 0.5-3, preferably 0.8-2, preferably 1-1.5;

d=0.1-4, preferably 0.1-3.5, more preferably 0.3-3, preferably 0.5-2.0, preferably 0.8-1.5;

e=0.1-5, preferably 0.1-4.5, more preferably 0.5-4, preferably 0.8-3.5, preferably 1-3;

g=0.05-15, preferably 0.5-13, more preferably 1-12, preferably 2-11, preferably 3.5-10.5;

h=0.1-5, preferably 0.5-4.5, more preferably 0.8-4, preferably 1-3.5, preferably 1.3-2.6;

i=0-4, preferably 0.5-3, more preferably 0.8-2.5, preferably 1-2, preferably 1.2-1.8;

j=0-3, preferably 0.1-2.5, more preferably 0.2-2, preferably 0.3-1.2, preferably 0.4-0.8;

f and k are values determined to satisfy the valence states of each atom;

m/n is 0.5-5, preferably 0.8-4.5, more preferably 1-4, preferably 1.5-3.5, preferably 2-3.

In an example of the present invention, i and j are zero at the same time or not at the same time.

2. Preparation method of composite metal oxide catalyst

The inventors of the present invention found that if the Mo-V series composite metal oxide catalyst is prepared by the core impregnation method, the prepared catalyst activity is significantly better than the catalyst prepared by other methods (for example, the direct mixing method). After 8000 hours of operation, its selectivity and stability are significantly higher than that of the catalyst prepared by the solid dry blending method. The present invention is completed on the basis of this discovery. Therefore, the manufacturing method of the catalyst of the present invention includes:

(i) Preparation of catalyst "core" from precursor compounds

In the present invention, the term "precursor compound" refers to a water-soluble compound or oxide containing elements required for a catalyst.

The term "core" refers to a _{solid particle with the following general formula [Mo a} V _b W _c Cu _d X _e O _f ], which is a precursor compound containing the required metal elements through direct mixing, and then drying, roasting, and crushing And other steps are processed into solid particles suitable for addition to the next catalyst preparation process.

In an example of the present invention, the "core" of the catalyst is a Mo-V composite metal oxide containing vanadium, which is prepared by a direct mixing method, and the steps are as follows:

(a) Direct mixing

Depending on the method steps, the precursor compound may be water-soluble or water-insoluble. In an example of the present invention, water is used as the reaction medium, and therefore, the precursor compound is required to be water-soluble. Non-limiting examples of suitable precursor compounds include the ammonium salt of the metal molybdenum, the ammonium salt of vanadium, the ammonium salt of tungsten, and the nitrate salt of copper.

In a preferred embodiment of the present invention, ammonium heptamolybdate and the ammonium salt of the desired metal compound are used as precursors to prepare solutions respectively. The concentration of the formed aqueous solution is not particularly limited, as long as the amount of the metal element meets the proportioning requirements of the final catalyst, and the aqueous solution can be formed under this concentration condition (for example, by heating or without heating).

Subsequently, the mixed solution in which the desired metal compound ammonium salt is dissolved and the solution in which ammonium heptamolybdate is dissolved, for example, the mixed solution in which the desired metal compound ammonium salt is dissolved is added to the solution in which ammonium heptamolybdate is dissolved, also The solution in which ammonium heptamolybdate is dissolved can be added to the mixed solution in which the ammonium salt of the desired metal compound is dissolved.

The direct mixing step of the present invention may also optionally include a slurry aging step, that is, after obtaining the slurry mixture, heating and stirring the obtained slurry at a temperature higher than room temperature to lower than the boiling point of the solution. In a preferred embodiment of the present invention, the obtained slurry is heated and stirred for 0.2-6 hours at a temperature of 20-90°C, preferably at a temperature of 30-80°C, and more preferably at a temperature of 40-70°C. It is preferably 0.5-4 hours, more preferably 1-2 hours.

(b) Dry

The obtained slurry is transferred to a porcelain plate, and then placed in an oven to dry. The drying temperature is between 50-300°C, preferably between 80-200°C, and more preferably between 100-150°C; the drying time is between 1-48 hours, preferably 2-32 hours, more preferably 4- 24 hours. The dry atmosphere is not particularly limited. In an example of the present invention, the dry atmosphere is an inert gas (for example, nitrogen or argon) or air. The dried solid is then crushed to obtain core particles with a particle size of less than 2000 μm, preferably less than 1900 μm, more preferably less than 1800 μm, preferably less than 1700 μm, preferably less than 1600 μm.

In an example of the present invention, the catalyst "core" is selected from Mo _3.0 V _0.3 W _1.3 Sb _2.5 Cu _0.94 , Mo _1.6 V _0.7 Sb _2.5 Cu _0.9 , Mo _8.0 V _2.0 W _1.0 Sb _1.92 Cu _0.94 , Mo _4.2 V _0.7 W _1.3 Sb _2.5 Cu _0.9 , Mo _8.0 (V ₂ O ₅ ) _1.0 W _1.0 Sb _1.0 Cu _0.94 or a mixture of two or more thereof (the inner core is not marked with oxygen).

(ii) Preparation of catalyst "shell" precursor solution

According to the required composition of the catalyst "shell" [Mo _g V _h Y _i Z _j O _k ], the precursor compounds of the elements can be dissolved in proportion, and then directly mixed to form a solution.

In an example of the present invention, the required component is an ammonium salt of a compound containing a metal molybdenum element, an ammonium salt of a compound containing a metal vanadium element, an ammonium salt of a compound containing a metal tungsten element, and the like. Ammonium heptamolybdate and the ammonium salt of the desired metal compound are used as precursors to prepare solutions respectively, and then the mixed solution in which the desired metal compound ammonium salt is dissolved and the solution in which ammonium heptamolybdate is dissolved are mixed to form a solution. For example, the mixed solution with the desired metal compound ammonium salt dissolved is added to the solution with ammonium heptamolybdate dissolved to form a solution, or the solution with ammonium heptamolybdate dissolved is added to the mixed solution with the desired metal compound ammonium salt dissolved A solution is formed in the solution.

(iii) Put the solid powder of the catalyst "core" into the precursor solution of the catalyst "shell" for impregnation

Impregnating the solid powder into the solution is a conventional chemical reaction step. Those of ordinary skill in the art can easily perform appropriate addition operations based on their professional knowledge.

In an example of the present invention, the mixed solution in which the desired metal compound ammonium salt is dissolved and the solution in which ammonium heptamolybdate is dissolved are mixed to form a solution, and then the solid powder of the catalyst "core" prepared above is added to the above solution .

In a preferred embodiment of the present invention, the housing is selected from Mo _9.0 V _3.0 , Mo _10.4 V _2.6 W _1.3 , Mo _3.9 V _1.3 Sb _0.58 , Mo _7.8 V _2.6 Ni _0.5 , Mo _3.9 V _1.3 or two or more thereof More kinds of mixtures formed (the outer shell is not marked with oxygen).

The adding step of the present invention may optionally include a slurry aging step, that is, after adding solid powder to the solution, immersing, and forming a mixture, the resulting mixture slurry is heated and stirred at a temperature higher than room temperature to lower than the boiling point of the solution . In a preferred embodiment of the present invention, the obtained mixture slurry is heated and stirred at a temperature of 20-90°C, preferably at a temperature of 30-80°C, more preferably at a temperature of 40-70°C, for 0.2-6 hours, It is preferably 0.5-4 hours, more preferably 1-2 hours.

The obtained slurry is dried, for example, the obtained slurry is transferred to a porcelain plate, and then placed in an oven for drying. The drying temperature is between 50-300°C, preferably between 80-200°C, and more preferably between 100-150°C; the drying time is between 1-48 hours, preferably 2-32 hours, more preferably 4 -24 hours. The dry atmosphere is not particularly limited, and may be a conventional atmosphere in this field. In an example of the present invention, the dry atmosphere is an inert gas (for example, nitrogen or argon) or air.

(iv) Molding and baking

The method of the present invention also includes the step of calcining the solid obtained in the above step (iii) to form a catalyst. The solid obtained in the above steps can be calcined to form a catalyst by any method known in the art. For example, the obtained solid is heat-treated at a temperature of 200-800°C, preferably 300-700°C, more preferably 350-500°C, for 1-32 hours, preferably 2-24 hours , Better 4-12 hours.

In a preferred embodiment of the present invention, the method of the present invention includes crushing and sieving the solid obtained in step (iii), then mixing graphite powder into the obtained solid powder for grinding, and the amount of graphite powder added is based on the weight of the solid powder , 1-6% by weight, preferably 1.5-4% by weight, more preferably 2-3% by weight. Then the obtained solid powder mixture is compressed into tablets at a pressure of between 1-30 MPa, preferably between 2-20 MPa, and more preferably between 4-15 MPa, and then crushed and sieved into particles of a suitable mesh. Finally, heat treatment is performed at a temperature between 200-800°C, preferably between 300-700°C, and more preferably at a temperature between 350-500°C for 1-32 hours, preferably 2-24 hours, more preferably 4 -12 hours to obtain the catalyst.

In a preferred embodiment of the present invention, the "shell" of the Mo-V composite metal oxide catalyst of the present invention is selected from: Mo _3.9 V _1.3 Sb _0.58 O _c , Mo _3.0 V _1.0 W _0.2 O _c , Mo _9.0 V _3.0 O _c , Mo _3.0 V _1.0 Ce _0.02 O _c , Mo _3.0 V _1.0 O _c , Mo _2.0 V _1.0 O _c , Mo _3.0 V _2.0 O _c , Mo _9.9 V _3.3 O _c , one or more of them, the catalyst "core" is selected From: One or more of Mo _8.0 V _2.0 W _1.0 Sb _1.92 Cu _0.94 O _c , Mo _8.0 V _2.0 W _1.0 Cu _1.0 Ca _0.1 O _c , Mo _8.0 V _1.0 W _2.0 Cu _0.05 Sb _1.5 O _c , better Yes Mo _9.0 V _3.0 O _c , Mo _3.9 V _1.3 Sb _0.58 O _c , Mo _3.0 V _1.0 W _0.2 O _c , Mo _8.0 V _2.0 W _1.0 Sb _1.92 Cu _0.94 O _c , Mo _8.0 V _2.0 W _1.0 Cu _1.0 Ca _0.1 O _{A mixture formed by impregnating one or more of c} in any ratio, where the subscript c is a value determined by the oxidation state of the constituent elements.

3. Catalytic reaction experiment

The invention is based on that the Mo-V series composite metal oxide can be used as a catalyst for acrolein oxidation to prepare acrylic acid.

The method of using the Mo-V composite metal oxide of the present invention as a catalyst for acrolein oxidation to prepare acrylic acid (catalytic oxidation reaction) is not particularly limited, and may be a conventional method known in the art.

In an example of the present invention, in the catalytic oxidation reaction, the volume percentage composition of the raw gas is 2%-14% of acrolein, 0.5%-25% of oxygen, 1%-30% of steam, unreacted propylene and others. Organic matter

1.3%-1.5%, the rest is nitrogen, the reaction temperature is 200-300°C, the reaction pressure is normal pressure-0.02Mpa, and the space velocity is 900-8000h ^-1 .

In the present invention, the acrolein conversion rate, acrylic acid selectivity and yield are defined as follows:

Acrolein conversion rate (mol%) = 100× moles of reacted acrolein/moles of acrolein supplied

Acrylic acid selectivity (mol%) = 100 × moles of acrylic acid produced by the reaction/moles of acrolein that has been reacted

Acrylic acid yield (mol%) = 100 × moles of acrylic acid produced by the reaction / moles of acrolein supplied

The amount of product in the reaction mixture can be determined by any conventional method known in the art. In an example of the present invention, the reaction product distribution is analyzed by Shimadzu gas chromatograph. The oxidation reaction product gas is sampled through a ten-way valve, and pre-separated through a pre-column to separate low-boiling gas (including olefins, O ₂ , N ₂ , CO ₂ , CO, etc.) from high-boiling organic products, and then pass The six-way valve separates olefins, O ₂ , N ₂ , CO ₂ , and CO and passes TCD analysis and detection. The organic products are backflushed into a set of capillary chromatographic system and detected by FID detector. _{The standard gas containing N 2} , CO ₂ , CO, propylene and acetone was analyzed by sampling via a quantitative tube, and the average value of the peak area of each substance was obtained by multiple analyses, and the relative molar correction factor of each substance was measured. Then prepare standard solutions containing organic products such as acetone, acrolein and acrylic acid, and analyze multiple times. Take the average of the peak area of each substance, and use the absolute correction factor of acetone measured by the standard gas as a reference to calculate various organic products. The relative correction factor. After one injection, the molar percentage of each substance can be obtained. Since nitrogen does not participate in the reaction, its flow rate is constant. Associate all carbon-containing substances with nitrogen, calculate the molar amount of carbon-containing substances, and calculate it with the feed amount. The yield of each substance and the conversion rate of propylene can be calculated at the same time. Carbon balance, the data used in the following discussion are all data with a carbon balance between 95% and 105%.

The present invention will be further described by the following examples, but the protection scope is not limited by the examples.

Example 1

(i) Preparation of catalyst

Preparation of "core" Mo _3.0 V _0.3 W _1.3 Sb _2.5 Cu _0.94 (Oxygen element not marked)

(1) Preparation of solution A: add 75mL of distilled water to a 500mL beaker, heat to 60℃, and then add 0.54g ammonium metavanadate, stir at 100℃ for 30min, add 8.16g paramolybdic acid while heating to 100℃ Ammonium, stir at constant temperature for 10 minutes, then add 5.05 g of ammonium metatungstate, stir at constant temperature for 10 minutes, finally add 5.61 g of antimony trioxide, continue stirring at 100°C for 3 hours, and then cool to 60°C.

(2) Preparation of solution B: take 15mL of distilled water into a 100mL beaker, heat it to 60°C, then add 3.49g of copper nitrate and stir to dissolve.

(3) Mixing process: Add the prepared B solution to the above A solution, and continue to stir at 60°C for 10 minutes. Then take 49g of Si powder and add it to the above mixed solution, and continue to stir at constant temperature for 1 hour. Finally, it is transferred to a 150°C oven and dried overnight for 16 hours. The dried kernel is crushed into powder with a particle size of less than 200 meshes for use.

The "shell" Mo _9.0 V _3.0 solution is dipped into the "core" Mo _2.1 W _1.3 Sb _2.5 Cu _0.94 (oxygen is not marked)

(1) _{Preparation of Mo 9.9} V _3.3 solution: add 150 mL of distilled water to a 500 mL beaker, heat to 60°C, and then add 5.4 g of ammonium metavanadate, stir at 100°C for 30 minutes, and then add 24.45 g Ammonium paramolybdate, stir at constant temperature for 1 hour, and then lower the temperature to 60°C.

(2) Mixing process: Add the crushed core powder to the above-mentioned immersion liquid, and continue to stir for 10 minutes at 60°C. Then it was transferred to a 150°C oven and dried overnight for 16 hours.

(3) Granulation and roasting. The dried solid sample is crushed in a small steel pump, then 4% water and 3% graphite are added, and it is molded under a pressure of 20 Ma, and finally crushed to 10-20 mesh size particles, and then transferred to a tube furnace for roasting. After the temperature is raised to 380°C, it is calcined for 4 hours.

(ii) Catalytic reaction

The catalyst prepared above is used for the oxidation of acrolein to produce acrylic acid. The reaction conditions were: forming the catalyst filling amount 15mL, volume percent of the raw material gas is: acrolein, 7%, 9% oxygen, 15% water vapor, unreacted propylene and other organic matter 1.4%, the remainder being nitrogen gas, a space velocity of 1200h ^{- 1} .

The conversion of acrolein and the yield of acrylic acid were measured, and the results are shown in the table below.

Example 2

(i) Preparation of catalyst

Preparation of "core" Mo _1.6 V _0.7 Sb _2.5 Cu _0.94 (Oxygen element not marked)

(1) Preparation of solution A: add 200mL of distilled water to a 500mL beaker, heat to 60℃, then to 100℃, add 2.52g of ammonium metavanadate, stir at 100℃ for 30min, then add 8.7g of secondary molybdenum Ammonium acid, stir at constant temperature for 10 minutes, finally add 11.22g antimony trioxide, continue to stir at 100°C for 3h, and then cool to 60°C.

(2) Preparation of solution B: add 15 mL of distilled water to a 100 mL beaker, heat it to 60°C, then add 6.98 g of copper nitrate, and stir to dissolve.

(3) Mixing process: Add the prepared B solution to the above A solution, and continue to stir at 60°C for 10 minutes. Then take 98g of Si powder and add it to the above mixed solution, and continue to stir at constant temperature for 1 hour. Finally, it was transferred to an oven at 150℃ and dried overnight for 16h. The dried kernel was crushed into powder with a particle size of less than 200 mesh, and then transferred to a muffle furnace, baked at 380℃ in an air atmosphere for 4h, and the kernel was prepared for use.

"Shell" Mo _10.4 V _2.6 W _1.3 solution is dipped into "Inner core" Mo _1.6 V _0.7 Sb _2.5 Cu _0.94 (Oxygen is not marked)

(1) _{Preparation of Mo 10.4} V _2.6 W _1.3 solution: add 150mL distilled water to a 500mL beaker, heat to 60℃, and then add 4.68g ammonium metavanadate to 100℃ and stir for 30min at 100℃, then Add 28.25g of ammonium paramolybdate and 5.05g of ammonium metatungstate, stir at constant temperature for 1 hour, and then lower the temperature to 60°C.

(2) Mixing process: 59.6 g of the core powder calcined at 380°C was added to the above-mentioned impregnation solution, stirring was continued at 60°C for 10 minutes, and then transferred to an oven at 150°C for overnight drying for 16 hours.

(ii) Catalytic reaction

The catalyst prepared above is used for the oxidation of acrolein to produce acrylic acid. The reaction conditions were: forming the catalyst filling amount 15mL, volume percent of the raw material gas is: 7% acrolein, 10% oxygen, 16% water vapor, unreacted propylene and other organic matter 1.5%, the remainder being nitrogen gas, a space velocity of 1400h ^{- 1} .

Example 3

(i) Preparation of catalyst

Preparation of "core" Mo _8.0 V _2.0 W _1.0 Sb _1.92 Cu _0.94 (Oxygen element not marked)

(1) Preparation of solution A: add 150mL of distilled water to a 500mL beaker, heat to 60℃, then to 100℃, add 3.6g of ammonium metavanadate, stir at 100℃ for 30min, then add 21.74g of secondary molybdenum Ammonium acid, stir at constant temperature for 10 minutes, then add 3.88 g of ammonium metatungstate, stir at constant temperature for 10 minutes, finally add 4.31 g of antimony trioxide, continue stirring at 100°C for 3 hours, and then cool to 60°C.

The "shell" Mo _3.9 V _1.3 Sb _0.58 solution is dipped into the "core" Mo _8.0 V _2.0 W _1.0 Sb _1.92 Cu _0.94 (without oxygen standard) element)

(1) _{Preparation of Mo 3.9} V _1.3 Sb _0.58 solution: add 150mL distilled water to a 500mL beaker, heat to 60℃, then to 100℃, add 2.34g ammonium metavanadate, stir at 100℃ for 30min, then Add 10.6g of ammonium paramolybdate, stir at 100°C for 30min, then add 1.3g of antimony trioxide, stir at constant temperature for 1.5h, and finally cool to 60°C.

(2) Mixing process: Add the pulverized core powder to the shell impregnation solution, and continue to stir for 10 minutes at 60°C. Then it was transferred to a 150°C oven and dried overnight for 16 hours.

(ii) Catalytic reaction

The catalyst prepared above is used for the oxidation of acrolein to produce acrylic acid. The reaction conditions were: forming the catalyst filling amount 15mL, volume percent of the raw material gas: 7.5% acrolein, 11% oxygen, 10% water vapor, unreacted propylene and other organic matter 1.5%, the remainder being nitrogen gas, a space velocity of 1500h ^{- 1} .

Example 4

(i) Preparation of catalyst

Preparation of "core" Mo _4.2 V _0.7 W _1.3 Sb _2.5 Cu _0.94 (Oxygen element not marked)

(1) Preparation of solution A: add 200mL of distilled water to a 500mL beaker, heat to 60℃, and then to 100℃, add 2.52g of ammonium metavanadate, stir at 100℃ for 30min, and then add 22.82g of para-molybdenum Ammonium acid, stir at constant temperature for 10 minutes, then add 10.1 g of ammonium metatungstate, stir at constant temperature for 10 minutes, and finally add 11.22 g of antimony trioxide, continue stirring at 100°C for 3 hours, and then cool to 60°C.

(3) Mixing process: Add the prepared B solution to the above A solution, and continue to stir at 60°C for 10 minutes. Then take 98g of Si powder and add it to the above mixed solution, and continue to stir at constant temperature for 1 hour. Finally, it is transferred to a 150°C oven and dried overnight for 16 hours. The dried kernel is crushed into powder with a particle size of less than 200 meshes for use.

The "shell" Mo _7.8 V _2.6 Ni _0.5 solution is dipped into the "core" Mo _4.2 V _0.7 W _1.3 Sb _2.5 Cu _0.94 (the oxygen element is not marked) Vegetarian)

(1) _{Preparation of Mo 7.8} V _2.6 Ni _0.5 solution: add 150mL of distilled water to a 500mL beaker, heat to 60℃, and then add 4.68g of ammonium metavanadate to 100℃ and stir for 30min at 100℃, then Add 21.19g of ammonium paramolybdate, stir at constant temperature for 30 minutes, then add 2.24g of nickel nitrate, stir at 100°C for 30 minutes, and then cool to 60°C.

(2) Mixing process: Add 72.72g of the pulverized core powder to the above-mentioned immersion liquid, and continue to stir for 10 minutes at 60°C. Then it was transferred to a 150°C oven and dried overnight for 16 hours.

(ii) Catalytic reaction

The catalyst prepared above is used for the oxidation of acrolein to produce acrylic acid. The reaction conditions were: forming the catalyst filling amount 15mL, volume percent of the raw material gas is: 7% acrolein, 10% oxygen, 14% water vapor, unreacted propylene and other organic matter 1.3%, the remainder being nitrogen gas, a space velocity of 1300h ^{- 1} .

Example 5

(i) Preparation of catalyst

Preparation of "core" Mo _8.0 (V ₂ O ₅ ) _1.0 W _1.0 Sb _1.0 Cu _0.94 (Oxygen element not marked)

(1) Preparation of solution A: Take 200mL of distilled water and add it to a 500mL beaker, heat it to 60°C, and then add 5.6g of vanadium pentoxide, stir at 100°C for 30min, and then add 43.47g of secondary Ammonium molybdate, stir at constant temperature for 10 minutes, then add 7.77 g of ammonium metatungstate, stir at constant temperature for 10 minutes, finally add 4.49 g of antimony trioxide, continue stirring at 100°C for 3 hours, and then cool to 60°C.

(3) Mixing process: Add the prepared B solution to the above A solution, and continue to stir at 60°C for 10 minutes. Then take 93g of Si powder and add it to the above mixed solution, and continue to stir at constant temperature for 1 hour. Finally, it is transferred to a 150°C oven and dried overnight for 16 hours. The dried kernel is crushed into powder with a particle size of less than 200 meshes for use.

The "shell" Mo _3.9 V _1.3 solution is impregnated into the "core" Mo _8.0 (V ₂ O ₅ ) _1.0 W _1.0 Sb _1.0 Cu _0.94 (without oxygen element Vegetarian)

(1) _{Preparation of Mo 3.9} V _1.3 solution: add 100mL of distilled water to a 500mL beaker, heat to 60℃, then add 1.17g ammonium metavanadate, stir at 100℃ for 30min, then add 5.3 g Ammonium paramolybdate, stir at 100°C for 30min, and finally lower the temperature to 60°C.

(2) Mixing process: Take 40 g of the above-mentioned crushed core powder and add it to the shell impregnation solution, and continue to stir for 10 minutes at 60°C. Then it was transferred to a 150°C oven and dried overnight for 16 hours.

(ii) Catalytic reaction

The catalyst prepared above is used for the oxidation of acrolein to produce acrylic acid. The reaction conditions were: forming the catalyst filling amount 15mL, volume percent of the raw material gas is: acrolein, 7%, 9% oxygen, 15% water vapor, unreacted propylene and other organic matter 1.4%, the remainder being nitrogen gas, a space velocity of 1200h ^{- 1} . In the initial stage of the reaction, the reaction temperature was 247°C, the conversion of acrolein was 99.8%, and the yield of acrolein was 97.8%; after the reaction continued for 1000 hours, the reaction temperature was 249°C, the conversion of acrolein was 99.8%, and the yield of acrolein was 98.0%; after 3000 hours of continuous operation , Reaction temperature 250℃, acrolein conversion rate 99.8%, acrolein yield 98.1%

The conversion of acrolein and the yield of acrylic acid were measured after 8000 hours of continuous operation, and the results are shown in the following table.

Comparative example 1

(i) Preparation of catalyst

(1) Preparation of solution A: Take 150mL Watsons distilled water into a 500mL beaker, heat to 60℃, and then add 5.94g ammonium metavanadate, stir at 100℃ for 30min, then add 32.6g while heating to 100℃ Ammonium paramolybdate, stir at constant temperature for 10 minutes, then add 5.05 g of ammonium metatungstate, stir at constant temperature for 10 minutes, finally add 5.61 g of antimony trioxide, continue stirring at 100°C for 3 hours, and then cool to 60°C.

(3) Mixing process: Add the prepared B solution to the above A solution, and continue to stir at 60°C for 10 minutes. Then take 49g of Si powder and add it to the above-mentioned mixed slurry, and continue to stir at constant temperature for 1 hour.

(4) Granulation and roasting. The dried solid sample is crushed in a small steel pump, then 4% water is added, and the shape is formed under a pressure of 20 Ma. Finally, it is crushed to 10-20 mesh size particles, and then transferred to a tube furnace for roasting, and the temperature is programmed to 380 ℃ Afterwards, roasting for 4h.

(ii) Catalytic reaction

Comparative example 2

(i) Preparation of catalyst

Preparation of Mo _1.6 V _0.7 Sb _2.5 Cu _0.94 (Oxygen element not marked)

(3) Mixing process: Add the prepared B solution to the above A solution, and continue to stir at 60°C for 10 minutes. Then take 98g of Si powder and add it to the above mixed solution, and continue to stir at constant temperature for 1 hour. Finally, it is transferred to a 150°C oven and dried overnight for 16 hours. The dried solid is crushed into powder with a particle size of less than 200 meshes for use.

Preparation of Mo _10.4 V _2.6 W _1.3 (Oxygen element not marked)

Take 200mL of distilled water and add it to a 500mL beaker, heat it to 60℃, and then add 9.36g of ammonium metavanadate to 100℃, stir for 30min at 100℃, then add 56.5g of ammonium paramolybdate and 10.1g of metatungstic acid Ammonium was stirred at constant temperature for 1 hour, and finally transferred to a 150°C oven for overnight drying for 16 hours. The dried solid was crushed into powder with a particle size of less than 200 meshes for use.

Solid dry blend of Mo _1.6 V _0.7 Sb _2.5 Cu _0.94 and Mo _10.4 V _2.6 W _1.3 (Oxygen element not marked)

Take 33g Mo _1.6 V _0.7 Sb _2.5 Cu _0.94 and 17g Mo _10.4 V _2.6 W _{1.3 and} mix them evenly, then add 4% water and 3% graphite, shape them under 20Ma pressure, and finally crush them to 10-20 mesh size particles, then Transfer to a tube furnace for roasting, program the temperature to 380°C, and roast for 4 hours.

(ii) Catalytic reaction

The catalyst prepared above is used for the oxidation of acrolein to produce acrylic acid. The reaction conditions were: forming the catalyst filling amount 15mL, volume percent of the raw material gas is: acrolein, 7%, 9% oxygen, 15% water vapor, unreacted propylene and other organic matter 1.4%, the remainder being nitrogen gas, a space velocity of 1200h ^{- 1} . In the initial stage of the reaction, the reaction temperature was 255°C, the conversion of acrolein was 99.8%, and the yield of acrolein was 97.1%; after the reaction continued for 1000 hours, the reaction temperature was 258°C, the conversion of acrolein was 99.8%, and the yield of acrolein was 96.5%; after 3000 hours of continuous operation , The reaction temperature is 262℃, the conversion rate of acrolein is 99.8%, and the yield of acrolein is 95.7%

From the comparison of the above data, it can be seen that the impregnation preparation method proposed by the present invention is suitable for synthesizing Mo-V composite metal oxide catalysts, and the prepared catalyst activity is significantly better than the catalyst prepared by the direct mixing method; the reaction runs continuously for 8000h Afterwards, the selectivity and stability are significantly higher than that of the catalyst prepared by the solid dry blending method. The industrial application value of the inventive method is great.

Claims

A molybdenum vanadium composite metal oxide catalyst, the catalyst has the following general formula:

[Mo a V b W c Cu d X e O f ] m [Mo g V h Y i Z j O k ] n

among them,

X is a mixture of one or more of Nb, Sb, Te, Zn, Ca, and Bi in any ratio;

Y is a mixture of one or more of Nd, La, Ce, W, and Cu in any ratio;

Z is a mixture of one or more of Cd, Sr, Sb, B, and Ni in any ratio;

a=1-20;

b=0.05-10;

c=0-5;

d=0.1-4;

e=0.01-5;

g=0.05-15;

h=0.01-5;

i=0-4;

j=0-3;

f and k are values determined to satisfy the valence states of each atom;

m/n is 0.5-5;

The catalyst is prepared by the following method:

(1) The Mo, V, W, Cu, and X precursor compounds are dissolved in a predetermined ratio to obtain a solution, and dried to obtain solid particles of oxide A with the following general formula:

Mo a V b W c Cu d X e O f ;

(2) The precursor compounds of Mo, V, Y, and Z are dissolved in a predetermined ratio to obtain solution B. The ratio of the elements of Mo, V, Y, and Z meets:

Mo g V h Y i Z j O k ;

(3) Disperse the solid particles of oxide A in solution B, dry, and calcinate to obtain a catalyst.
The catalyst according to claim 1 or 2, characterized in that its manufacturing step (1) further comprises adding heat-conducting agent powder to the solution, and the heat-conducting agent is selected from the group consisting of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, and nitrogen. A mixture of one or more of boron oxide, silicon powder, silicon dioxide, and silicon carbide in any ratio.
The catalyst according to claim 1 or 2, characterized in that

X is a mixture of one or more of Nb, Sb, Te, and Zn in any ratio, more preferably a mixture of one or more of Nb, Sb, and Te in any ratio, preferably Nb, Sb or a mixture thereof ；

Y is a mixture of one or more of Nd, La, Ce, and W in any ratio, more preferably one or more of Nd, La, and W, preferably La, W or a mixture thereof;

Z is a mixture of one or more of Cd, Sb, and Ni in any ratio, more preferably Sb, Ni or a mixture thereof;

a=1.2-16, more preferably 1.4-12, preferably 1.5-10, preferably 1.6-8;

b=0.1-8, more preferably 0.15-6, preferably 0.2-4, preferably 0.25-2;

c=0.1-4, more preferably 0.5-3, preferably 0.8-2, preferably 1-1.5;

d=0.1-3.5, more preferably 0.3-3, preferably 0.5-2.0, preferably 0.8-1.5;

e=0.1-4.5, more preferably 0.5-4, preferably 0.8-3.5, preferably 1-3;

g=0.5-13, more preferably 1-12, preferably 2-11, preferably 3.5-10.5;

h=0.5-4.5, more preferably 0.8-4, preferably 1-3.5, preferably 1.3-2.6;

i=0.5-3, more preferably 0.8-2.5, preferably 1-2, preferably 1.2-1.8;

j=0.1-2.5, more preferably 0.2-2, preferably 0.3-1.2, preferably 0.4-0.8;

m/n is 0.8-4.5, more preferably 1-4, preferably 1.5-3.5, preferably 2-3.

i and j are zero at the same time or not at the same time.
The catalyst according to claim 1 or 2, characterized in that

The solid particles of oxide A are selected from Mo 3.0 V 0.3 W 1.3 Sb 2.5 Cu 0.94 , Mo 1.6 V 0.7 Sb 2.5 Cu 0.9 , Mo 8.0 V 2.0 W 1.0 Sb 1.92 Cu 0.94 , Mo 4.2 V 0.7 W 1.3 Sb 2.5 Cu 0.9 , Mo 8.0 (V 2 O 5 ) 1.0 W 1.0 Sb 1.0 Cu 0.94 or a mixture of two or more thereof;

The solution B is selected from Mo 9.0 V 3.0 , Mo 10.4 V 2.6 W 1.3 , Mo 3.9 V 1.3 Sb 0.58 , Mo 7.8 V 2.6 Ni 0.5 , Mo 3.9 V 1.3 or a mixture of two or more thereof.
A method for preparing the molybdenum-vanadium composite oxide catalyst according to any one of claims 1 to 4, which comprises the following steps:

(1) The Mo, V, W, Cu, and X precursor compounds are dissolved in a predetermined ratio to obtain a solution, and dried to obtain solid particles of oxide A with the following general formula:

Mo a V b W c Cu d X e O f ;

(2) The precursor compounds of Mo, V, Y, and Z are dissolved in a predetermined ratio to obtain solution B. The ratio of the elements of Mo, V, Y, and Z meets:

Mo g V h Y i Z j O k ;

(3) Disperse the solid particles of oxide A into solution B, dry, and calcinate to obtain a catalyst;

among them,

X is a mixture of one or more of Nb, Sb, Te, Zn, Ca, and Bi in any ratio;

Y is a mixture of one or more of Nd, La, Ce, W, and Cu in any ratio;

Z is a mixture of one or more of Cd, Sr, Sb, B, and Ni in any ratio;

a=1-20;

b=0.05-10;

c=0-5;

d=0.1-4;

e=0.01-5;

g=0.05-15;

h=0.01-5;

i=0-4;

j=0-3;

f and k are values determined to satisfy the valence state of each atom.
The method according to claim 5, characterized in that step (1) further comprises adding a thermal conductive agent powder to the solution, the thermal conductive agent is selected from the group consisting of aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon A mixture of one or more of powder, silicon dioxide, and silicon carbide in any ratio.
The method of claim 5 or 6, wherein

X is a mixture of one or more of Nb, Sb, Te, and Zn in any ratio, more preferably a mixture of one or more of Nb, Sb, and Te in any ratio, preferably Nb, Sb or a mixture thereof ；

Y is a mixture of one or more of Nd, La, Ce, and W in any ratio, more preferably one or more of Nd, La, and W, preferably La, W or a mixture thereof;

Z is a mixture of one or more of Cd, Sb, and Ni in any ratio, more preferably Sb, Ni or a mixture thereof;

a=1.2-16, more preferably 1.4-12, preferably 1.5-10, preferably 1.6-8;

b=0.1-8, more preferably 0.15-6, preferably 0.2-4, preferably 0.25-2;

c=0.1-4, more preferably 0.5-3, preferably 0.8-2, preferably 1-1.5;

d=0.1-3.5, more preferably 0.3-3, preferably 0.5-2.0, preferably 0.8-1.5;

e=0.1-4.5, more preferably 0.5-4, preferably 0.8-3.5, preferably 1-3;

g=0.5-13, more preferably 1-12, preferably 2-11, preferably 3.5-10.5;

h=0.5-4.5, more preferably 0.8-4, preferably 1-3.5, preferably 1.3-2.6;

i=0.5-3, more preferably 0.8-2.5, preferably 1-2, preferably 1.2-1.8;

j=0.1-2.5, more preferably 0.2-2, preferably 0.3-1.2, preferably 0.4-0.8;

m/n is 0.8-4.5, more preferably 1-4, preferably 1.5-3.5, preferably 2-3.

i and j are zero at the same time or not at the same time.
The use of the catalyst according to any one of claims 1 to 5 in the reaction of acrolein oxidation to acrylic acid.