Catalyst for preparing acrolein and acrylic acid by selective oxidation of propylene and method for preparing the same

Abstract

The application discloses a catalyst for preparing propenal and acrylic acid through selective oxidation of propylene, a preparation method of the catalyst and a preparation method of propenal and acrylic acid. a Fe b X c Y d Z e P f O j , wherein X is at least one selected from Mg, Co, Ni, Ca, Cu, Zn, Mn, Y is at least one selected from Nb, Sb and W, and Z is at least one selected from K, Rb, Na, Li and Cs. The catalyst is used in a reaction for preparing propenal and acrylic acid through selective oxidation of propylene, has the advantages of high total yield of propenal and acrylic acid, and good structural stability of the catalyst.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts, in particular, to a catalyst for preparing acrolein and acrylic acid by selective oxidation of propylene, a preparation method of the catalyst and a preparation method of acrolein and acrylic acid. BACKGROUND

[0002] The selective oxidation of olefins to produce unsaturated acids is an important chemical process. In industry, the olefins are first oxidized to produce unsaturated aldehydes, and then the unsaturated aldehydes are oxidized to produce unsaturated acids. This process is usually completed in two stages using two reactors and two catalysts under different reaction conditions. The first stage reaction mainly produces acrolein, and about 20% of acrylic acid. The active component of the catalyst is a complex Mo-Bi composite oxide system. The improvement of the catalyst is mainly from the activity and stability of the catalyst, such as adding transition metals to the active component to improve the activity and increase the yield of the product; adding rare earth elements to improve the redox capacity; adding Fe, Co, Ni and other elements to inhibit the sublimation of Mo, stabilize the active component of the catalyst, and improve the service life of the catalyst. In addition, due to the severe heat release phenomenon in the reaction, it is very important to control the reaction temperature of the catalyst bed. The formation of hot spots not only makes the reaction result worse, but also shortens the service life of the catalyst and affects the stable operation of the device.

[0003] It is generally believed that in the first step of the reaction process of producing acrolein by oxidation of propylene, the olefin is adsorbed on the surface of the catalyst, an α-H is removed by the metal oxide to form a free radical intermediate, and the product is formed by oxygen or nitrogen insertion. In this process, the catalyst undergoes a redox cycle, loses the oxygen atom involved in the insertion reaction, is reduced itself, is then re-oxidized by the oxygen in the reaction gas, and the active site oxygen atom is supplemented by oxygen migration. Therefore, the catalyst requires good oxygen migration ability to maintain the structure of the catalyst and the redox balance, and generally uses Mo, V, Bi, Te, Nb, Fe and other transition metal composite oxides (Catalysis Today 49 (1999) 141-153). In the selective oxidation reaction, the distance between the active sites has an important influence on the selective oxidation reaction, and it is generally believed that site isolation is beneficial to the selective oxidation reaction (AICHE J. 9 (1963), 755).

[0004] US4224187 and US4248803 propose to improve the conversion rate of olefins and the yield of target products by improving the composition of the catalyst and their proportion and the preparation method of the catalyst. For the selective oxidation of isobutylene, there is a problem of low reaction selectivity. The conversion rate of isobutylene is as high as 99%, but the total yield of methyl propyl aldehyde and methyl propyl acid is only 73.6%.

[0005] US6268529 proposes an oxidation catalyst for propylene, the conversion of propylene is 98.1%, the yield of propyl aldehyde is 65.3%, the yield of propionic acid is 20.8%, and the total yield of propyl aldehyde and propionic acid is 86.1%.

[0006] CN1564709A improves the performance of the catalyst by adding organic carboxylic acid to overcome the unevenness of the catalyst caused by the separation of metal salts in the preparation of the catalyst co-precipitation process. The catalyst is used for the selective oxidation of propylene, wherein the highest conversion of propylene is 98.12%, the highest selectivity of propyl aldehyde is 82.53%, and the total yield of propyl aldehyde and propionic acid is 91.05%.

[0007] CN1210511A, CN1283604A and CN1314331A control the reaction hot spot by arranging multiple catalyst layers with gradually increasing reactivity along the axial direction of the reactor from the inlet to the outlet of the reaction gas. However, the structural stability of the catalyst needs to be further improved. SUMMARY

[0008] In view of the low yield and low stability of the existing oxidation catalyst, the present application provides a new oxidation catalyst, which is used for the oxidation of olefins such as propylene to prepare propyl aldehyde and propionic acid, has the advantages of high total yield of propyl aldehyde and propionic acid, and good catalyst stability.

[0009] The first aspect of the present application provides a catalyst for the selective oxidation of propylene to prepare propyl aldehyde and propionic acid, the general formula of the catalyst is: a Fe b X c Y d Z e P f O j , wherein X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, Mn; Y is selected from at least one of Nb, Sb, W; Z is selected from at least one of K, Rb, Na, Li, Cs; a is the molar ratio of Bi to Mo, a is 0.1-0.6; b is the molar ratio of Fe to Mo, b is 0.1-0.5; c is the molar ratio of X to Mo, c is 0.2-1.0; d is the molar ratio of Y to Mo, d is 0.1-0.5; e is the molar ratio of Z to Mo, e is 0.01-0.06; f is the molar ratio of P to Mo, f is 0.1-0.6; j is the total number of oxygen atoms required to satisfy the valence of other elements; f / a is 0.8-1.2.

[0010] According to a preferred embodiment of the present application, a is 0.2-0.4; b is 0.2-0.4; c is 0.3-0.7; d is 0.2-0.4; e is 0.02-0.05; f is 0.2-0.5; and f / a is 0.9-1.1.

[0011] The catalyst of the present application has high oxidation activity and stable structure, and the problem of structure stability reduction caused by charge imbalance can be well avoided by introducing a small amount of P, thereby improving the stability of the catalyst.

[0012] The second aspect of the present application provides a preparation method of a catalyst for preparing propylene aldehyde and acrylic acid by selective oxidation of propylene, comprising refluxing a first solution containing Mo compound, P compound and Y compound, adjusting the pH value of the first solution to 0-3, adding a second solution containing Bi compound to form a first slurry, refluxing, mixing the first slurry with a third solution containing Fe compound, X compound and Z compound to form a second slurry, and drying and calcining.

[0013] According to a preferred embodiment of the present application, the preparation method comprises refluxing a first solution containing Mo compound, P compound and Y compound at 80-100℃ for 2-4h, adjusting the pH value of the first solution to 0-3, adding a second solution containing Bi compound to form a first slurry, refluxing at 80-100℃ for 2-4h. The first slurry is mixed with a third solution containing Fe compound, X compound and Z compound to form a second slurry, and the second slurry is dried and calcined.

[0014] The amount of each substance in the preparation method of the present application satisfies the general formula of the catalyst prepared: MoBi a Fe b X c Y d Z e P f O j , wherein X is at least one selected from Mg, Co, Ni, Ca, Cu, Zn and Mn; Y is at least one selected from Nb, Sb and W; Z is at least one selected from K, Rb, Na, Li and Cs; a is the molar ratio of Bi to Mo, a is 0.1-0.6; b is the molar ratio of Fe to Mo, b is 0.1-0.5; c is the molar ratio of X to Mo, c is 0.2-1.0; d is the molar ratio of Y to Mo, d is 0.1-0.5; e is the molar ratio of Z to Mo, e is 0.01-0.06; f is the molar ratio of P to Mo, f is 0.1-0.6; and j is the total number of oxygen atoms required to satisfy the valence of other elements. f / a is 0.8-1.2.

[0015] According to a preferred embodiment of the present application, a is 0.2-0.4.

[0016] According to a preferred embodiment of the present application, b is 0.2-0.4.

[0017] According to a preferred embodiment of the present application, c is 0.3-0.7.

[0018] According to a preferred embodiment of the present application, d is 0.2-0.4.

[0019] According to a preferred embodiment of the present application, e is 0.02-0.05.

[0020] According to a preferred embodiment of the present application, f is 0.2-0.5.

[0021] According to a preferred embodiment of the present application, f / a is 0.9-1.1.

[0022] The catalyst prepared by the aforementioned method of the present application can further improve the activity and selectivity of the catalyst.

[0023] According to the present application, the drying condition has no special requirement, and for the present application, the drying condition preferably includes that the temperature is 50-80℃. For example, 50℃, 60℃, 70℃, 80℃, and any value between them.

[0024] According to the present application, the drying time can be determined according to the drying temperature, and the drying time is preferably 1-16h. For example, 1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, and any value between them.

[0025] According to the present application, the calcination condition has no special requirement, and for the present application, the calcination condition preferably includes that the temperature is 400-650℃. For example, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, and any value between them.

[0026] According to the present application, the calcination time can be determined according to the calcination temperature, and the calcination time is preferably 1-12h. For example, 1h, 2h, 4h, 6h, 8h, 10h, 12h, and any value between them.

[0027] According to a preferred embodiment of the present application, the calcination atmosphere is inert atmosphere and / or O2-containing atmosphere. However, from the economic point of view, the calcination atmosphere is preferably air. Unless otherwise specified, the calcination atmosphere in the present application is air.

[0028] According to a preferred embodiment of the present application, the solution after mixing of each process is a homogeneous solution, a suspension or a mixture of solution and suspension.

[0029] According to the present application, a solid can be obtained by a step of concentration or the like, and for the present application, it is preferred to obtain the solid by evaporation concentration at 60 to 80°C.

[0030] According to a preferred embodiment of the present application, the amount of water used in the first solution and the second solution has a wide range of selection, for the purpose of fully dissolving the compounds.

[0031] According to a preferred embodiment of the present application, the Mo compound, the Y compound, the Bi compound, the Fe compound, the X compound, the Z compound and the P compound can be selected from nitrates, ammonium salts, sulfates, oxides, hydroxides, chlorides, acetates and the like.

[0032] According to a preferred embodiment of the present application, the Mo compound can be selected from, but not limited to, one or more of ammonium molybdate, molybdenum trioxide, molybdenum nitrate, molybdic acid and sodium molybdate.

[0033] According to a preferred embodiment of the present application, the Bi compound can be selected from, but not limited to, one or more of bismuth nitrate, bismuth suboxide, bismuth sulfate, bismuth chloride and bismuth acetate.

[0034] According to a preferred embodiment of the present application, the Fe compound can be selected from, but not limited to, one or more of iron nitrate, iron sulfate, iron chloride, iron oxide and ferrous sulfate.

[0035] According to a preferred embodiment of the present application, the X compound can be selected from, but not limited to, one or more of cobalt nitrate, cobalt sulfate, cobalt chloride, magnesium nitrate, magnesium sulfate, magnesium chloride, magnesium oxide, magnesium acetate, nickel nitrate, nickel sulfate, nickel chloride, calcium nitrate, calcium acetate, calcium chloride, copper nitrate, zinc nitrate and manganese nitrate.

[0036] According to a preferred embodiment of the present application, the Y compound can be selected from, but not limited to, one or more of niobium oxalate, niobium pentoxide, niobium pentachloride, niobium acid, niobyl nitrate, ammonium niobium oxalate, antimony nitrate, antimony tartrate, ammonium tungstate, tungsten trioxide, tungstic acid, sodium tungstate and ammonium metatungstate.

[0037] According to a preferred embodiment of the present application, the Z compound can be selected from, but not limited to, one or more of potassium nitrate, rubidium nitrate, sodium nitrate, sodium sulfate, sodium chloride, sodium acetate, sodium hydroxide, lithium nitrate and cesium nitrate.

[0038] According to a preferred embodiment of the present application, the P compound can be selected from, but not limited to, one or more of phosphoric acid, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, phosphorus pentoxide and phosphorus chloride.

[0039] Mo-Bi system composite oxide is an important catalytic system for olefin selective oxidation or ammoxidation, and Bi is considered as the active site of the first step of dehydrogenation. Bi salt is easy to form precipitate in neutral or alkaline environment, which will affect the dispersion of Bi in Mo-based composite oxide. The solubility product of BiPO4 is small, and it is not dissolved under acidic conditions, and can well fix Bi. P is easy to disperse in Mo oxide. Therefore, first disperse P in Mo, then anchor Bi under acidic conditions using the dispersed P, so that Bi is better dispersed in the composite oxide to form isolated active sites, which can well improve the performance of the catalyst.

[0040] The method of the present application is used for preparing propylene aldehyde by propylene oxidation, and has the advantages of high total yield of propylene aldehyde and propylene acid, and good stability of the catalyst structure.

[0041] The third aspect of the present application provides a catalyst obtained by the preparation method.

[0042] The components of the catalyst are represented by the general formula: MoBi a Fe b X c Y d Z e P f O j , wherein X is at least one selected from Mg, Co, Ni, Ca, Cu, Zn and Mn; Y is at least one selected from Nb, Sb and W; Z is at least one selected from K, Rb, Na, Li and Cs; a is the molar ratio of Bi to Mo, and a is 0.1-0.6; b is the molar ratio of Fe to Mo, and b is 0.1-0.5; c is the molar ratio of X to Mo, and c is 0.2-1.0; d is the molar ratio of Y to Mo, and d is 0.1-0.5; e is the molar ratio of Z to Mo, and e is 0.01-0.06; f is the molar ratio of P to Mo, and f is 0.1-0.6; j is the total number of oxygen atoms required to satisfy the valence of other elements. f / a is 0.8-1.2.

[0043] According to a preferred embodiment of the present application, a is 0.2-0.4; b is 0.2-0.4; c is 0.3-0.7; d is 0.2-0.4; e is 0.02-0.05; and f is 0.2-0.5. f / a is 0.9-1.1.

[0044] The catalyst of the present application has high oxidation activity, stable structure, dispersed P to anchor Bi, good dispersion of Bi, isolated active sites, and good activity and selectivity of the catalyst.

[0045] The fourth aspect of the present application provides a method for preparing propenal and acrylic acid, comprising reacting propylene with an oxidizing gas containing oxygen in the presence of a catalyst, wherein the catalyst is the catalyst described above or the catalyst obtained by the method described above.

[0046] According to the preferred embodiment of the present application, the oxidizing gas containing oxygen can be pure oxygen, oxygen-enriched air, but from the economic aspect, air is preferred.

[0047] According to the preferred embodiment of the present application, the reaction conditions include: temperature of 300-550°C, preferably 330-380°C.

[0048] According to the preferred embodiment of the present application, the reaction conditions include: pressure of 0.01-0.08 MPa (gauge pressure).

[0049] According to the preferred embodiment of the present application, propylene: air = 1: (6-8) in volume ratio.

[0050] According to the preferred embodiment of the present application, in order to make the reaction more stable and controllable, it is preferred to be carried out in the presence of dilution gas phase materials. The dilution gas phase materials are preferably water vapor.

[0051] According to the preferred embodiment of the present application, the reaction conditions include: propylene: air: optional water vapor = 1: (6-8): (0.5-5).

[0052] According to the preferred embodiment of the present application, the reaction conditions include: raw gas volume mass space velocity: 600-1200 mL / g·h.

[0053] The present application adopts pre-dispersing P component in Mo, and then using the combination of Bi and P to make the active component Bi well dispersed, thereby improving the performance of the catalyst. The catalyst of the present application is used for olefin oxidation, especially propylene oxidation to prepare propenal and acrylic acid, and has the advantages of high total yield of propenal and acrylic acid, and good stability of catalyst structure. DETAILED DESCRIPTION

[0054] In order to make the present application easier to understand, the present application will be described in detail below in combination with examples, which are only illustrative and do not limit the scope of application of the present application.

[0055] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the purposes of the application. The endpoints of the ranges and any values are provided as approximations only and are understood to be open-ended. Thus, the endpoints of the ranges and any values are not to be understood as being stated in a restrictive sense, unless otherwise specified in this disclosure.

[0056] The starting materials used in the examples and comparative examples of the present application, if not specifically defined, are either commercially available or can be prepared according to methods known in the art.

[0057] In the examples and comparative examples of the present application, the catalyst evaluation conditions are as follows:

[0058] Reactor: Fixed bed single tube reactor, inner diameter 26.0 mm, reactor length 800 mm

[0059] Catalyst: 200 g

[0060] Reaction temperature: 360°C

[0061] Reaction pressure: 0.03 MPa (gauge pressure)

[0062] Propylene: Air (molar ratio of raw material) = 1 : 7.2

[0063] Propylene: Water vapor = 1 : 1.8

[0064] Volume mass space velocity of raw gas: 1000 mL / g-h

[0065] The reaction product was absorbed with dilute acid at 0°C, and the product was analyzed by gas chromatography (Agilent 7890A). Carbon balance was calculated, and when the carbon balance was (95-105)%, it was effective data.

[0066] The propylene conversion, product yield, and selectivity were defined as:

[0067]

[0068]

[0069]

[0070]

Example 1

[0071] Ammonium molybdate corresponding to 1 mole of Mo, diammonium hydrogen phosphate corresponding to 0.3 mole of P and ammonium niobium oxalate corresponding to 0.2 mole of Nb were weighed into 3000 g of water to obtain solution 1. After refluxing at 90°C for 3 h, the pH value was adjusted to 2 using nitric acid. Bismuth nitrate corresponding to 0.3 mole of Bi was weighed into 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1. After refluxing at 80°C for 3 h, slurry 1 was obtained. Iron nitrate containing 0.3 mole of Fe, cobalt nitrate containing 0.5 mole of Co and rubidium nitrate containing 0.04 mole of Rb were dissolved in 200 g of water to obtain solution 3. Slurry 2 was obtained by mixing slurry 1 and solution 3. Concentration was carried out at 65°C to a thick paste, which was dried at 80°C for 6 h and then calcined at 550°C in air for 2 h to obtain catalyst MoBiFeCoNbRbP 0.3 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 P 0.3 O j .

[0072] [Example 2]

[0073] Ammonium molybdate corresponding to 1 mole of Mo, diammonium hydrogen phosphate corresponding to 0.1 mole of P and ammonium niobium oxalate corresponding to 0.2 mole of Nb were weighed into 3000 g of water to obtain solution 1. After refluxing at 90°C for 3 h, the pH value was adjusted to 2 using nitric acid. Bismuth nitrate corresponding to 0.12 mole of Bi was weighed into 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1. After refluxing at 80°C for 3 h, slurry 1 was obtained. Iron nitrate containing 0.3 mole of Fe, cobalt nitrate containing 0.5 mole of Co and rubidium nitrate containing 0.04 mole of Rb were dissolved in 200 g of water to obtain solution 3. Slurry 2 was obtained by mixing slurry 1 and solution 3. Concentration was carried out at 65°C to a thick paste, which was dried at 80°C for 6 h and then calcined at 550°C in air for 2 h to obtain catalyst MoBiFeCoNbRbP 0.12 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 P 0.1 O j .

[0074] [Example 3]

[0075] Ammonium molybdate corresponding to 1 mole of Mo, diammonium hydrogen phosphate corresponding to 0.6 mole of P and ammonium niobium oxalate corresponding to 0.2 mole of Nb were weighed into 3000 g of water to obtain solution 1, which was refluxed at 90°C for 3 h and then adjusted to pH 2 with nitric acid. Bismuth nitrate corresponding to 0.5 mole of Bi was weighed into 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1 and refluxed at 80°C for 3 h to obtain slurry 1. Iron nitrate containing 0.3 mole of Fe, cobalt nitrate containing 0.5 mole of Co and rubidium nitrate containing 0.04 mole of Rb were dissolved in 200 g of water to obtain solution 3. Slurry 1 and solution 3 were mixed to obtain slurry 2. Concentration was carried out at 65°C to a thick paste, which was dried at 80°C for 6 h and then calcined at 550°C in air for 2 h to obtain the catalyst MoBiFeCoRbP 0.5 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 P 0.6 O j .

[0076] [Example 4]

[0077] Ammonium molybdate corresponding to 1 mole of Mo, diammonium hydrogen phosphate corresponding to 0.3 mole of P, antimony tartrate corresponding to 0.1 mole of Sb and ammonium metatungstate corresponding to 0.4 mole of W were weighed into 3000 g of water to obtain solution 1, which was refluxed at 90°C for 3 h and then adjusted to pH 2 with nitric acid. Bismuth nitrate corresponding to 0.3 mole of Bi was weighed into 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1 and refluxed at 80°C for 3 h to obtain slurry 1. Iron nitrate containing 0.1 mole of Fe, cobalt nitrate containing 0.5 mole of Co, nickel nitrate containing 0.5 mole of Ni and potassium nitrate containing 0.01 mole of K were dissolved in 200 g of water to obtain solution 3. Slurry 1 and solution 3 were mixed to obtain slurry 2. Concentration was carried out at 65°C to a thick paste, which was dried at 80°C for 6 h and then calcined at 550°C in air for 2 h to obtain the catalyst MoBiFeCoNiSbWP 0.3 Fe 0.1 Co 0.5 Ni 0.5 Sb 0. 1W 0.4 K 0.01 P 0.3 O j .

[0078] [Example 5]

[0079] Ammonium molybdate corresponding to 1 mole of Mo, diammonium hydrogen phosphate corresponding to 0.3 mole of P and ammonium metatungstate corresponding to 0.1 mole of W were weighed into 3000 g of water to obtain solution 1, which was refluxed at 90°C for 3 h and then adjusted to pH 2 with nitric acid. Bismuth nitrate corresponding to 0.3 mole of Bi was weighed into 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1 and refluxed at 80°C for 3 h to obtain slurry 1. Iron nitrate containing 0.5 mole of Fe, magnesium nitrate containing 0.2 mole of Mg, rubidium nitrate containing 0.03 mole of Rb and sodium nitrate containing 0.03 mole of Na were dissolved in 200 g of water to obtain solution 3. Slurry 2 was obtained by mixing slurry 1 and solution 3. Concentration was carried out at 65°C to a thick paste, which was dried at 80°C for 6 h and then calcined at 550°C in air for 2 h to obtain catalyst MoBiFeMgRbNaP 0.3 Fe 0.5 Mg 0.2 W 0.1 Rb 0.03 Na 0.03 P 0.3 O j .

[0080] Example 6

[0081] Ammonium molybdate corresponding to 1 mole of Mo, diammonium hydrogen phosphate corresponding to 0.45 mole of P and ammonium niobium oxalate corresponding to 0.2 mole of Nb were weighed into 3000 g of water to obtain solution 1, which was refluxed at 90°C for 3 h and then adjusted to pH 2 with nitric acid. Bismuth nitrate corresponding to 0.5 mole of Bi was weighed into 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1 and refluxed at 80°C for 3 h to obtain slurry 1. Iron nitrate containing 0.3 mole of Fe, cobalt nitrate containing 0.5 mole of Co and rubidium nitrate containing 0.04 mole of Rb were dissolved in 200 g of water to obtain solution 3. Slurry 2 was obtained by mixing slurry 1 and solution 3. Concentration was carried out at 65°C to a thick paste, which was dried at 80°C for 6 h and then calcined at 550°C in air for 2 h to obtain catalyst MoBiFeCoRbP 0.5 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 P 0.45 O j .

[0082] Comparative Example 1

[0083] Solution 1 was prepared by dissolving ammonium molybdate (equivalent to 1 mol Mo) and ammonium niobate oxalate (equivalent to 0.2 mol Nb) in 3000 g of water and refluxing at 90 °C for 3 h, followed by adjusting the pH to 2 with nitric acid. Solution 2 was prepared by dissolving bismuth nitrate (equivalent to 0.3 mol Bi) in 150 ml of 10% nitric acid and adding it to solution 1, followed by reflux at 80 °C for 3 h. Solution 3 was prepared by dissolving ferric nitrate (containing 0.3 mol Fe), cobalt nitrate (containing 0.5 mol Co), and rubidium nitrate (containing 0.04 mol Rb) in 200 g of water. Slurry 1 and solution 3 were mixed to obtain slurry 2. The slurry was concentrated to a viscous paste at 65 °C, dried at 80 °C for 6 h, and then calcined in air at 550 °C for 2 h to obtain the catalyst MoBi. 0.3 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 O j .

[0084] Comparative Example 2

[0085] Solution 1 was prepared by dissolving ammonium molybdate (equivalent to 1 mol Mo), diammonium hydrogen phosphate (equivalent to 0.5 mol P), and ammonium niobium oxalate (equivalent to 0.2 mol Nb) in 3000 g of water and refluxing at 90 °C for 3 h. The pH was then adjusted to 2 with nitric acid. Solution 2 was prepared by dissolving bismuth nitrate (equivalent to 0.3 mol Bi) in 150 ml of 10% nitric acid and adding it to solution 1. The mixture was then refluxed at 80 °C for 3 h to obtain slurry 1. Solution 3 was prepared by dissolving ferric nitrate (equivalent to 0.3 mol Fe), cobalt nitrate (equivalent to 0.5 mol Co), and rubidium nitrate (equivalent to 0.04 mol Rb) in 200 g of water. Slurry 2 was prepared by mixing slurry 1 and solution 3. The mixture was concentrated to a viscous paste at 65 °C, dried at 80 °C for 6 h, and then calcined in air at 550 °C for 2 h to obtain catalyst MoBi. 0.3 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 P 0.5 O j .

[0086] Comparative Example 3

[0087] Ammonium molybdate, 0.3 mole P of diammonium hydrogen phosphate and 0.2 mole Nb of ammonium niobium oxalate corresponding to 1 mole Mo were dissolved in 3000 g of water to obtain solution 1, which was refluxed at 90°C for 3 h and adjusted to pH 5 with nitric acid. Bismuth nitrate corresponding to 0.3 mole Bi was dissolved in 150 ml of 10% nitric acid to obtain solution 2, which was added to solution 1 and refluxed at 80°C for 3 h to obtain slurry 1. Iron nitrate, 0.5 mole Co of cobalt nitrate and 0.04 mole Rb of rubidium nitrate corresponding to 0.3 mole Fe were dissolved in 200 g of water to obtain solution 3. Slurry 1 and solution 3 were mixed to obtain slurry 2. Concentration at 65°C to a thick paste, drying at 80°C for 6 h and calcination at 550°C in air for 2 h gave the catalyst MoBiCoFeNbRbP 0.3 Fe 0.3 Co 0.5 Nb 0.2 Rb 0.04 P 0.3 O j .

[0088] The obtained catalyst was evaluated and tested, and the results are shown in Table 1.

[0089] Table 1

[0090]

Claims

1. A catalyst for the selective oxidation of propylene to prepare acrolein and acrylic acid, said catalyst having the general formula: MoBi a Fe b X c Y d Z e P f O j Where X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of Nb, Sb, and W; Z is selected from at least one of K, Rb, Na, Li, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.6; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.2 to 1.0; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; f is the molar ratio of P to Mo, with a value of 0.1 to 0.6; j is the total number of oxygen atoms required to satisfy the valence of other elements; f / a is 0.8 to 1.

2. The catalyst is prepared by the following method: refluxing a first solution containing Mo compound, P compound and Y compound, and then adjusting the pH of the first solution to 0~3; A second solution containing a Bi compound is added to form a first slurry, which is then refluxed. The first slurry is mixed with a third solution containing Fe compound, X compound, and Z compound to form a second slurry; then dried and calcined.

2. The catalyst according to claim 1, characterized in that: The values ​​of a are 0.2 to 0.4; the values ​​of b are 0.2 to 0.4; the values ​​of c are 0.3 to 0.7; the values ​​of d are 0.2 to 0.4; the values ​​of e are 0.02 to 0.05; the values ​​of f are 0.2 to 0.5; and the value of f / a is 0.9 to 1.

1.

3. A method for preparing a catalyst for the selective oxidation of propylene to acrolein and acrylic acid, comprising refluxing a first solution containing a Mo compound, a P compound and a Y compound, and then adjusting the pH of the first solution to 0-3; A second solution containing a Bi compound is added to form a first slurry, which is then refluxed. The first slurry is mixed with a third solution containing Fe compound, X compound, and Z compound to form a second slurry; then dried and calcined. The feed amounts of each substance satisfy the requirement that the catalyst prepared has the general formula: MoBi a Fe b X c Y d Z e P f O j Where X is selected from at least one of Mg, Co, Ni, Ca, Cu, Zn, and Mn; Y is selected from at least one of Nb, Sb, and W; Z is selected from at least one of K, Rb, Na, Li, and Cs; a is the molar ratio of Bi to Mo, with a value of 0.1 to 0.6; b is the molar ratio of Fe to Mo, with a value of 0.1 to 0.5; c is the molar ratio of X to Mo, with a value of 0.2 to 1.0; d is the molar ratio of Y to Mo, with a value of 0.1 to 0.5; e is the molar ratio of Z to Mo, with a value of 0.01 to 0.06; f is the molar ratio of P to Mo, with a value of 0.1 to 0.6; j is the total number of oxygen atoms required to satisfy the valence of other elements; and f / a is 0.8 to 1.

2.

4. The preparation method according to claim 3, characterized in that: The first solution was refluxed at 80-100℃ for 2-4 hours.

5. The preparation method according to claim 3, characterized in that: The first slurry is refluxed at 80~100℃ for 2~4 hours.

6. The preparation method according to claim 3, characterized in that: Drying conditions include: a temperature of 50–80°C and a time of 1–16 hours; and / or, The roasting conditions include a temperature of 400~650℃ and a time of 1~12h.

7. The catalyst obtained by the preparation method according to any one of claims 3 to 6.

8. A method for preparing acrolein and acrylic acid, comprising reacting propylene with an oxygen-containing oxidizing gas in the presence of a catalyst, wherein, The catalyst is the catalyst according to claim 1 or 2 or the catalyst obtained by any one of the preparation methods according to claims 3 to 6.

9. The method for preparing acrolein and acrylic acid according to claim 8, characterized in that, The reaction is carried out in the presence of a dilutive gaseous material.

10. The method for preparing acrolein and acrylic acid according to claim 9, characterized in that, The dilutive gaseous material is water vapor.

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