Composite oxide catalyst, preparation method thereof, and method for preparing nitrile compounds

Abstract

The present invention discloses a composite oxide catalyst and its preparation method and application. The catalyst of the present invention comprises silicon dioxide and an active component represented by the following general formula: Mo 11.0 Bi b Fe c D d E e O x , wherein D is selected from at least one of Li, Na, K, Rb and Cs; E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W and Nb, wherein b is in the range of 0.1 to 5.0; c is in the range of 0.1 to 5.0; d is in the range of 0.1 to 5.0; e is in the range of 0.1 to 5.0; x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst; the lattice oxygen migration rate of the composite oxide catalyst is similar to that of α-Bi2Mo3O 12 The lattice oxygen migration rate of the catalyst of the present invention is fast, and when used in the production of nitrile compounds, it has the advantages of high raw material conversion rate, high yield of product nitrile compounds, and stable catalyst performance.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, in particular to a low-carbon olefin ammoxidation catalyst and a preparation method thereof, and a method for producing nitrile compounds. Background Art

[0002] Currently, the industrial production of propylene to unsaturated nitriles via ammoxidation generally adopts the Sohio fluidized bed process. The catalyst is the core of this technology. From the perspective of the main elements of the catalyst, it can be mainly classified into Mo-Bi and Sb-Fe series, among which Mo-Bi series catalysts occupy a major position. In recent years, the research and performance improvement of catalysts have also been mainly carried out around them, and a rich theoretical foundation has been formed, such as oxidation-reduction cycle, active site isolation, lattice defects and interphase synergy.

[0003] CN103769129A discloses a fluidized bed catalyst for ammonia oxidation to produce unsaturated nitrile and its preparation method. The catalyst is supported by silica sol and contains the following active component represented by the general formula: Mo 12 Bi a Fe b Ni c X d Y e Z f Q g K h TiO x , wherein: X is at least one selected from Mg, Co, Ca, Be, Cu, Zn, Pb, Mn or Te; Y is at least one selected from La, Ce or Sm; Z is at least one selected from Rb, Li or Cs; Q is at least one selected from Sb, Nb or Ta; T is at least one selected from Be, Ca or Ba; a is in the range of 0.1 to 6.0; b is in the range of 0.1 to 10.0; c is in the range of 0.1 to 10.0; d is in the range of 0.1 The invention relates to a catalyst comprising a catalyst having a molecular weight of 100 nm and a molecular weight of 100 nm. The catalyst comprises ...

[0004] In addition, when using existing catalysts to produce acrylonitrile through ammoxidation of propylene, there are problems such as low propylene conversion rate and low acrylonitrile yield. Summary of the Invention

[0005] In response to the above-mentioned problems existing in the prior art, the present invention provides a new composite oxide catalyst and a preparation method thereof, and a method for preparing nitrile compounds. The active components of the composite oxide catalyst of the present invention are relatively simple, and the lattice oxygen migration rate of the catalyst is fast. When used to produce nitrile compounds, it has the advantages of high raw material conversion rate, high yield of product nitrile compounds, and stable catalyst performance.

[0006] The first aspect of the present invention provides a composite oxide catalyst comprising silicon dioxide and an active component represented by the following general formula: Mo 11.0 Bi b Fe c D d E e O x , wherein D is selected from at least one of Li, Na, K, Rb and Cs; E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W and Nb, wherein b is in the range of 0.1 to 5.0; c is in the range of 0.1 to 5.0; d is in the range of 0.1 to 5.0; e is in the range of 0.1 to 5.0; and x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst;

[0007] The lattice oxygen migration rate of the composite oxide catalyst is similar to that of α-Bi2Mo3O 12 Compared with the lattice oxygen migration rate of α-Bi2Mo3O, the lattice oxygen migration rate of α-Bi2Mo3O is increased by 1.5 to 4.5 times. 12 The CAS number is 13595-85-2.

[0008] According to some embodiments of the present invention, after 20 in-situ pulse reactions of light olefins, the light olefin conversion rate decreases by less than 3.7 percentage points, preferably less than 2.8 percentage points, using the light olefin ammoxidation catalyst of the present invention after supplementation with lattice oxygen. In the present invention, the decrease is 2.8 percentage points, for example, from 90% to 87.2%, a difference of 2.8 percentage points.

[0009] According to some embodiments of the present invention, preferably, the preparation process of the composite oxide catalyst includes: adding a molybdenum precursor in multiple portions to form a co-precipitation slurry, and adjusting the pH value of the slurry with an inorganic base.

[0010] According to some embodiments of the present invention, preferably, the plurality of portions is 2 or more, preferably 2 to 5 portions.

[0011] According to some embodiments of the present invention, preferably, the pH value is 2 to 12, preferably 3.5 to 9.0.

[0012] According to some embodiments of the present invention, preferably, the carrier additive is selected from at least one of potassium hydroxide, calcium hydroxide, magnesium hydroxide, cobalt hydroxide, nickel hydroxide, zirconium hydroxide, and ammonium hydroxide, preferably ammonium hydroxide. In the present invention, the carrier additive can be added in solid form or in liquid form after being dissolved in a liquid. In a more preferred embodiment, the carrier additive is an aqueous ammonium hydroxide solution.

[0013] According to some embodiments of the present invention, preferably, the weight of the carrier is 25 to 65 weight %, preferably 35 to 65 weight %, of the weight of the catalyst.

[0014] A second aspect of the present invention provides a method for preparing a composite oxide catalyst, comprising: (1) dissolving a Mo precursor to obtain a solution I, and dividing the solution I into a plurality of portions uniformly by weight;

[0015] (2) dissolving a Bi precursor, a Fe precursor, a D precursor, and an E precursor to obtain a solution II, wherein D is selected from at least one of Li, Na, K, Rb, and Cs; and E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W, and Nb;

[0016] (3) preparing a solution III containing a carrier;

[0017] (4) The first portion of solution I is mixed with solution III, and then solution II is added to obtain a coprecipitation slurry. The remaining portions of solution I are then added sequentially at equal intervals, and the slurry pH is adjusted with an inorganic base, dried, and calcined.

[0018] According to some embodiments of the present invention, preferably, the multiple portions in step (1) are 2 or more portions, preferably 2 to 5 portions.

[0019] According to some embodiments of the present invention, preferably, step (4) is performed at intervals of the same time, which is 5 to 60 minutes, preferably 8 to 35 minutes.

[0020] According to some embodiments of the present invention, preferably, the solution containing a carrier, wherein the carrier may be silicon dioxide or the like, preferably, the solution III containing the carrier is silica sol.

[0021] According to some embodiments of the present invention, preferably, the temperature when adjusting the pH value of the slurry with the inorganic base is constant, preferably, the temperature is 30-180°C, more preferably 60-150°C.

[0022] According to some embodiments of the present invention, preferably, the pH value is 2 to 12, preferably 3.5 to 9.0.

[0023] According to some embodiments of the present invention, preferably, the calcination conditions include: a temperature of 500-680°C, preferably 550-650°C.

[0024] According to some embodiments of the present invention, preferably, the calcination conditions include: a time of 0.2 to 4 hours, preferably 0.5 to 2.5 hours.

[0025] According to some embodiments of the present invention, the active component precursor may be a soluble salt of the active component, for example, the soluble salt of Mo may be but is not limited to (NH4)6Mo7O 24 For another example, the soluble salt of Bi may be, but is not limited to, Bi(NO 3 ) 3 .

[0026] According to some embodiments of the present invention, preferably, the carrier additive is selected from at least one of potassium hydroxide, calcium hydroxide, magnesium hydroxide, cobalt hydroxide, nickel hydroxide, zirconium hydroxide, and ammonium hydroxide, preferably ammonium hydroxide. In the present invention, the carrier additive can be added in solid form or in liquid form after being dissolved in a liquid. In a more preferred embodiment, the carrier additive is an aqueous ammonium hydroxide solution.

[0027] According to some embodiments of the present invention, preferably, the amount of the active component precursor is such that in the prepared composite oxide catalyst, the active component has the general formula of Mo 11.0 Bi b Fe c D d E e O x , wherein D is selected from at least one of Li, Na, K, Rb and Cs; E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W and Nb, wherein the value range of b is 0.1 to 5.0; the value range of c is 0.1 to 5.0; the value range of d is 0.1 to 5.0; the value range of e is 0.1 to 5.0; and x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst.

[0028] According to some embodiments of the present invention, preferably, the weight of the carrier is 25 to 65 weight %, preferably 35 to 65 weight %, of the weight of the catalyst.

[0029] According to a specific embodiment of the present invention, the preparation method may include but is not limited to:

[0030] (1) dissolving a Mo-containing precursor to obtain a solution I, and evenly dividing the solution I into multiple portions by weight;

[0031] (2) dissolving a Bi precursor, an Fe precursor, a D precursor, and an E precursor (i.e., elements other than Mo) to obtain a solution II, wherein D is selected from at least one of Li, Na, K, Rb, and Cs; and E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W, and Nb;

[0032] (3) Weighing the required amount of carrier silica sol solution III;

[0033] (4) mixing the first portion of solution I with solution III while stirring, then adding solution II to obtain a coprecipitation slurry, then adding the remaining equal portions of solution I at equal intervals, and finally adjusting the pH value of the slurry with at least one inorganic base under constant temperature conditions;

[0034] (5) The slurry is spray-dried and calcined at 500-680°C for 0.2-4.0 hours to obtain a catalyst

[0035] The third aspect of the present invention provides a composite oxide catalyst obtained according to the above preparation method, wherein the composite oxide catalyst comprises silicon dioxide and an active component represented by the following general formula: Mo 11.0 Bi b Fe c D d E e O x , wherein D is selected from at least one of Li, Na, K, Rb and Cs; E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W and Nb, wherein b is in the range of 0.1 to 5.0; c is in the range of 0.1 to 5.0; d is in the range of 0.1 to 5.0; e is in the range of 0.1 to 5.0; and x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst;

[0036] The lattice oxygen migration rate of the composite oxide catalyst is similar to that of α-Bi2Mo3O 12 Compared with the lattice oxygen migration rate of α-Bi2Mo3O, the lattice oxygen migration rate of α-Bi2Mo3O is increased by 1.5 to 4.5 times. 12 The CAS number is 13595-85-2.

[0037] According to some embodiments of the present invention, after 20 in-situ pulse reactions of light olefins, the light olefin ammoxidation catalyst of the present invention is used to perform another pulse reaction after supplementing lattice oxygen, and the decrease in the light olefin conversion rate is less than 3.7 percentage points, preferably less than 2.8 percentage points.

[0038] According to some embodiments of the present invention, preferably, the weight of the carrier is 25 to 65 weight %, preferably 35 to 65 weight %, of the weight of the catalyst.

[0039] A fourth aspect of the present invention provides a method for preparing nitrile compounds, comprising: contacting a light olefin feedstock, ammonia and air to carry out an ammoxidation reaction in the presence of the above-mentioned composite oxide catalyst or the composite oxide catalyst obtained according to the above-mentioned preparation method.

[0040] According to some embodiments of the present invention, preferably, the light olefin raw material is propylene and / or isobutylene.

[0041] According to some embodiments of the present invention, preferably, the molar ratio of the light olefin feedstock, ammonia and air is 1:1.05-1.3:9.2-9.8.

[0042] According to some embodiments of the present invention, preferably, the reaction conditions include: a temperature of 420-440°C.

[0043] According to some embodiments of the present invention, preferably, the reaction conditions include: a reaction pressure of 0.06 to 0.14 MPa.

[0044] According to some embodiments of the present invention, preferably, the propylene loading (WWH) of the catalyst is 0.06 to 0.10 h -1 .

[0045] According to some embodiments of the present invention, the nitrile compound may be, but is not limited to, acrylonitrile, methacrylonitrile, and the like.

[0046] Beneficial effects of the present invention:

[0047] In the preparation process, the present invention adopts the method of adding molybdenum precursor (molybdenum salt) in batches to form a coprecipitation slurry and adjusting the pH value of the slurry to 2.0-12.0 with the optimal pH value of 3.5-9.0, thereby improving the lattice oxygen migration rate and stability of the catalyst and having a good stability compared with α-Bi2Mo3O 12 (CAS: 13595-85-2, also known as Alpha-Bi2Mo3O 12 ) compared to the lattice oxygen migration rate. Using the composite oxide catalyst of the present invention, after 20 in-situ pulse reactions with light olefins, followed by a second pulse reaction after replenishing lattice oxygen, the light olefin conversion rate decreased by less than 3.7 percentage points, preferably less than 2.8 percentage points.

[0048] As demonstrated in the subsequent examples of the present invention, the activity of the catalyst of the present invention was evaluated in a fluidized bed reactor with an inner diameter of 38 mm, wherein the catalyst loading was 400 g, the reaction temperature was 435°C, the air:propylene molar ratio was 9.7:1, the ammonia:propylene molar ratio was 1.25:1, the reaction pressure was 0.085 MPa, and the propylene load (WWH) was 0.06 h -1 Under the conditions of , the propylene conversion rate is greater than 98%, and the acrylonitrile single-pass yield reaches more than 83%, achieving good results. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The propylene conversion rate of the catalyst of Example 1 of the present invention after 20 light olefin pulses in situ and the catalyst of Example 1 after 20 light olefin pulses and then fully replenishing lattice oxygen and then pulsed with light olefins again 20 times is shown in each pulse.

[0050] Figure 2 For α-Bi2Mo3O 12 Compared with the lattice oxygen migration rate of the catalyst of Example 1, the catalyst of Comparative Example 1 and the catalyst of Comparative Example 2, the lattice oxygen migration rate of Alpha-Bi2Mo3O 12 α-Bi2Mo3O 12 . DETAILED DESCRIPTION

[0051] In order to make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are only for illustration and do not limit the scope of application of the present invention.

[0052] The test method of the present invention and the equipment used in the test are as follows:

[0053] Unless otherwise specified, the raw materials used in the examples and comparative examples are all publicly available in the prior art, and can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0054] (1) In the present invention, the definitions of propylene conversion, acrylonitrile selectivity and per pass yield are as follows:

[0055]

[0056]

[0057]

[0058]

[0059] (2) The catalyst in-situ pulse test was carried out on a chemical adsorption device equipped with a gas chromatograph. The catalyst sample loading amount was 0.3 g, the pulse gas quantitative loop was 0.25 ml, and the pulse interval time was 11 min. An inert gas was used as the carrier gas, preferably nitrogen, argon and helium, and most preferably helium. The tail gas was detected for composition changes using a hydrogen flame ionization detector FID and a thermal conductivity TCD detector. Before the catalyst sample was tested, a blank experiment was performed. The temperature was programmed to 380-450 ° C. Before the pulse reaction began, an inert gas was purged for 2 hours, followed by 20 pulses of light olefin gas. Then, 10% O2 pulse gas was passed through to measure the number of moles of O2 consumed in each pulse. Until there was no obvious change in the number of O2 moles in the last few times, it was considered that the catalyst had fully replenished the lattice oxygen available for the reaction. The lattice oxygen migration rate of the catalyst available for the reaction is represented by the symbol ν, with the unit being mol / g·min, ν = the number of moles of O2 consumed in each pulse / (catalyst mass × interval time),

[0060] The conversion of light olefins per pulse is defined as follows:

[0061] Conversion rate of light olefins (%) = number of moles of light olefins removed in each pulse reaction / number of moles of light olefins in a blank experiment under the same conditions × 100.

[0062] Unless otherwise specified, percentages and concentrations in the Examples and Comparative Examples are percentages by weight.

[0063] [Example 1]

[0064] 778.0 g (NH4)6Mo7O 24 Solution (I) was obtained by dissolving 189.6 g of Bi(NO₃)₃·5H₂O, 645.2 g of Ni(NO₃)₂·6H₂O, 9.7 g of RbNO₃, 306.2 g of Fe(NO₃)₃·9H₂O, 197.1 g of Mg(NO₃)₂·6H₂O, 123.8 g of Nd(NO₃)₃·6H₂O, and 16.4 g of Ca(NO₃)₃·4H₂O in 215 g of water. Solution (II) was obtained by weighing 1560 g of a silica sol solution (III) having a silicon content of 40%. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining two portions of solution (I) were then added at intervals of 15 minutes. The slurry was then heated to 80°C and stirred. The pH value was adjusted to 6.0 with a 10% dilute ammonia solution. The prepared slurry was formed into microspheres and dried in a spray dryer. Finally, it was calcined in a rotary calciner at 590°C for 2 hours to obtain a Mo-containing slurry. 11.0 Bi 1.0 Fe1.9 Ni 5.5 Mg 1.9 Rb 0.2 Ca 0.2 Nd 0.7 O x The catalyst comprises 37.5% by weight of the carrier.

[0065] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 4.1 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then subjected to 20 more propylene pulses. The propylene conversion rate decreased by 2.1 percentage points. The results are shown in Table 1.

[0066] [Example 2]

[0067] 1025.0 g (NH4)6Mo7O 24 ·4H2O was dissolved in 1438 g of water to obtain solution (I). Solution (I) was evenly divided into three equal portions by weight, each weighing 821.0 g. 380.7 g of Bi(NO3)3·5H2O, 743.8 g of Ni(NO3)2·6H2O, 506.3 g of Fe(NO3)3·9H2O, 143.8 g of Pr(NO3)3·6H2O, and 4.3 g of CrO3 were dissolved in 385 g of water by heating to obtain solution (II). 1920 g of a silica sol solution (III) having a silicon content of 40% was weighed. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitation slurry. The remaining two portions of solution (I) were then added at intervals of 15 minutes. The slurry was then heated to 75°C and stirred, and the pH was adjusted to 6.5 using a 1% aqueous KOH solution. The prepared slurry was formed into microspheres and dried in a spray dryer, and finally calcined in a rotary calciner at 600 ° C for 2 hours to obtain a Mo- 11.0 Bi 1.5 Fe 2.4 Ni 4.8 K 0.1 Pr 0.6 Cr 0.1 O x The catalyst comprises 35.9% by weight of the carrier.

[0068] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 3.4 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then subjected to 20 more propylene pulses. The propylene conversion rate decreased by 2.6 percentage points, as shown in Table 1.

[0069] [Example 3]

[0070] 921.6 g (NH4)6Mo7O 24 Solution (I) was obtained by dissolving 189.4 g of Bi(NO₃)₃·5H₂O, 457.9 g of Ni(NO₃)₂·6H₂O, 6.8 g of CsNO₃, 341.6 g of Fe(NO₃)₃·9H₂O, 241.6 g of Mg(NO₃)₂·6H₂O, and 176.2 g of Nd(NO₃)₃·6H₂O in 220 g of water. Solution (II) was obtained by dissolving 1785 g of a silica sol solution (III) having a silicon content of 40%. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining two portions of solution (I) were then added at intervals of 15 minutes. The slurry was then heated to 60°C and stirred. 4.3 g of Ca(OH)2 powder was added and the pH value was adjusted to 5.5 with a 10% dilute ammonia solution. The prepared slurry was formed into microspheres and dried in a spray dryer. Finally, it was calcined in a rotary calciner at 620°C for 1.5 hours to obtain a Mo-containing slurry. 11.0 Bi 0.8 Fe 1.8 Ni 3.3 Mg 2.0 Cs 0.1 Ca 0.1 Nd 0.8 O x The catalyst comprises 38.5% by weight of the carrier.

[0071] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 2.5 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 2.8 percentage points, as shown in Table 1.

[0072] [Example 4]

[0073] 1010.6 g (NH4)6Mo7O 24Solution (I) was obtained by dissolving 267.4 g of Bi(NO₃)₃·5H₂O, 543.8 g of Ni(NO₃)₂·6H₂O, 482.4 g of Fe(NO₃)₃·9H₂O, 169.2 g of Mg(NO₃)₂·6H₂O, 168.7 g of La(NO₃)₃·6H₂O, 13.8 g of CsNO₃, and 3.1 g of CrO₃ in 216 g of water. Solution (II) was obtained by weighing 1960 g of a silica sol solution (III) having a silicon content of 40%. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining two portions of solution (I) were then added at intervals of 15 minutes. The slurry was then heated to 90°C and stirred. 5.5 g of Co(OH)2 powder was added and the pH value was adjusted to 7.0 with a 10% dilute ammonia solution. The prepared slurry was formed into microspheres and dried in a spray dryer. Finally, it was calcined in a rotary calciner at 600°C for 1.5 hours to obtain a Mo-containing slurry. 11.0 Bi 1.1 Fe 2. 3Ni 3.6 Mg 1.3 Co 0.1 Cs 0.1 La 0.7 Cr 0.1 O x The catalyst comprises 37.7% by weight of the carrier.

[0074] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 3.1 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 2.6 percentage points, as shown in Table 1.

[0075] [Example 5]

[0076] 985.4 g (NH4)6Mo7O 24·4H2O was dissolved in 1130 g of water to obtain solution (I). Solution (I) was evenly divided into three equal portions by weight, each containing 705.1 g. 364.8 g of Bi(NO3)3·5H2O, 571.8 g of Ni(NO3)2·6H2O, 278.6 g of Mg(NO3)2·6H2O, 156.2 g of Zr(NO3)4·5H2O, 453.7 g of Fe(NO3)3·9H2O, 168.3 g of Ce(NO3)3·6H2O, 276.1 g of Pr(NO3)3·6H2O, and 10.2 g of RbNO3 were dissolved in 265 g of water by heating to obtain solution (II). 2045 g of a silica sol solution (III) having a silicon content of 40% was weighed. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining two portions of solution (I) were then added at intervals of 15 minutes. The slurry was then heated to 110°C and stirred. The pH value was adjusted to 4.5 with a 10% dilute ammonia solution. The prepared slurry was formed into microspheres and dried in a spray dryer. Finally, it was calcined in a rotary calciner at 590°C for 2 hours to obtain a composition of Mo 11.0 Bi 1. 5Fe 2.2 Ni 3.9 Mg 2.1 Ce 0.8 Rb 0.1 Pr 1.3 Zr 0.7 O x The catalyst comprises 35.6% by weight of the carrier.

[0077] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared with the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 3.8 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 1.8 percentage points, as shown in Table 1.

[0078] [Example 6]

[0079] The method of Example 1 is followed, except that the molybdenum precursor is divided into two equal parts, namely:

[0080] 778.0 g (NH4)6Mo7O 24Solution (I) was obtained by dissolving 189.6 g of Bi(NO₃)₃·5H₂O, 645.2 g of Ni(NO₃)₂·6H₂O, 9.7 g of RbNO₃, 306.2 g of Fe(NO₃)₃·9H₂O, 197.1 g of Mg(NO₃)₂·6H₂O, 123.8 g of Nd(NO₃)₃·6H₂O, and 16.4 g of Ca(NO₃)₃·4H₂O in 215 g of water. Solution (II) was obtained by weighing 1560 g of a silica sol solution (III) having a silicon content of 40%. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining portion of solution (I) was then added. The slurry was then heated to 80°C and stirred. The pH value was adjusted to 6.0 with a 10% dilute ammonia solution. The prepared slurry was formed into microspheres and dried in a spray dryer. Finally, it was calcined in a rotary calciner at 590°C for 2 hours to obtain a composition of Mo 11.0 Bi 1.0 Fe 1.9 Ni 5.5 Mg 1.9 Rb 0.2 Ca 0.2 Nd 0.7 O x The catalyst comprises 37.5% by weight of the carrier.

[0081] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 3.2 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then subjected to 20 more propylene pulses. The propylene conversion rate decreased by 2.6 percentage points. The results are shown in Table 1.

[0082] [Example 7]

[0083] The method of Example 1 is followed, except that the molybdenum precursor is divided into five parts, namely:

[0084] 778.0 g (NH4)6Mo7O 24·4H2O was dissolved in 1045 g of water to obtain solution (I). Solution (I) was evenly divided into five equal portions by weight, each containing 364.6 g. 189.6 g of Bi(NO3)3·5H2O, 645.2 g of Ni(NO3)2·6H2O, 9.7 g of RbNO3, 306.2 g of Fe(NO3)3·9H2O, 197.1 g of Mg(NO3)2·6H2O, 123.8 g of Nd(NO3)3·6H2O, and 16.4 g of Ca(NO3)3·4H2O were dissolved in 215 g of water by heating to obtain solution (II). 1560 g of a silica sol solution (III) having a silicon content of 40% was weighed. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining four portions of solution (I) were then added. The slurry was then heated to 80°C and stirred. The pH value was adjusted to 6.0 with a 10% dilute ammonia solution. The prepared slurry was dried in a spray dryer to form microspheres, and finally calcined in a rotary calciner at 590°C for 2 hours to obtain a composition of Mo 11.0 Bi 1.0 Fe 1.9 Ni 5.5 Mg 1.9 Rb 0.2 Ca 0.2 Nd 0.7 O x The catalyst comprises 37.5% by weight of the carrier.

[0085] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 2.7 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then subjected to 20 more propylene pulses. The propylene conversion rate decreased by 2.8 percentage points. The results are shown in Table 1.

[0086] [Example 8]

[0087] The method of Example 1 was followed, except that a 10% dilute ammonia solution was used to adjust the pH to 3.5.

[0088] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 1.8 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 2.5 percentage points, as shown in Table 1.

[0089] [Example 9]

[0090] The method of Example 1 was followed, except that a 10% dilute ammonia solution was used to adjust the pH to 9.0, and gelation occurred in the slurry during the adjustment process.

[0091] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 The lattice oxygen migration rate of the catalyst increased by 1.6 times compared to the lattice oxygen migration rate of the catalyst. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 2.4 percentage points, as shown in Table 1.

[0092] [Example 10]

[0093] The method of Example 1 was followed, except that a 10% dilute ammonia solution was used to adjust the pH to 2.0.

[0094] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 The lattice oxygen migration rate of the catalyst increased by 1.5 times compared to the lattice oxygen migration rate of the catalyst. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 2.8 percentage points, as shown in Table 1.

[0095] [Example 11]

[0096] The method of Example 1 was followed, except that the slurry was subsequently heated to 150° C. and stirred.

[0097] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 The lattice oxygen migration rate of the catalyst increased by 1.5 times compared to the lattice oxygen migration rate of the catalyst. After 20 propylene in-situ pulses, the catalyst was oxygenated and then pulsed with 20 more propylene pulses. The propylene conversion rate decreased by 3.7 percentage points, as shown in Table 1.

[0098] [Comparative Example 1]

[0099] The method of Example 1 is the same, except that the molybdenum precursor is not divided into multiple parts, that is:

[0100] 778.0 g (NH4)6Mo7O 24·4H2O was dissolved in 1045 g of water to obtain solution (I). 189.6 g of Bi(NO3)3·5H2O, 645.2 g of Ni(NO3)2·6H2O, 9.7 g of RbNO3, 306.2 g of Fe(NO3)3·9H2O, 197.1 g of Mg(NO3)2·6H2O, 123.8 g of Nd(NO3)3·6H2O, and 16.4 g of Ca(NO3)3·4H2O were dissolved in 215 g of water by heating to obtain solution (II). 1560 g of silica sol solution (III) having a silicon content of 40% was weighed. Solution (I) and solution (III) were mixed, and solution (II) was added to obtain a precipitate slurry. The slurry was then heated to 80°C and stirred, and the pH was adjusted to 6.0 with a 10% dilute ammonia solution. The prepared slurry was formed into microspheres and dried in a spray dryer, and finally calcined in a rotary calciner at 590°C for 2 hours to obtain a Mo- 11.0 Bi 1.0 Fe 1.9 Ni 5.5 Mg 1.9 Rb 0.2 Ca 0.2 Nd 0.7 O x The catalyst comprises 37.5% by weight of the carrier.

[0101] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 1.4 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then subjected to 20 more propylene pulses. The propylene conversion rate decreased by 3.8 percentage points. The results are shown in Table 1.

[0102] [Comparative Example 2]

[0103] The method of Example 1 was followed, except that the pH value of the coprecipitation slurry was not adjusted with an inorganic base, that is:

[0104] 778.0 g (NH4)6Mo7O 24Solution (I) was obtained by dissolving 189.6 g of Bi(NO₃)₃·5H₂O, 645.2 g of Ni(NO₃)₂·6H₂O, 9.7 g of RbNO₃, 306.2 g of Fe(NO₃)₃·9H₂O, 197.1 g of Mg(NO₃)₂·6H₂O, 123.8 g of Nd(NO₃)₃·6H₂O, and 16.4 g of Ca(NO₃)₃·4H₂O in 215 g of water. Solution (II) was obtained by weighing 1560 g of a silica sol solution (III) having a silicon content of 40%. The first portion of solution (I) was mixed with solution (III), and then solution (II) was added to obtain a precipitated slurry. The remaining two portions of solution (I) were then added at intervals of 15 minutes. The slurry was then heated to 80°C and stirred. The pH value of the slurry was then 1.4. The prepared slurry was dried in a spray dryer for micro-sphere formation and finally calcined in a rotary calciner at 590°C for 2 hours to obtain a Mo-containing slurry. 11.0 Bi 1.0 Fe 1.9 Ni 5.5 Mg 1.9 Rb 0.2 Ca 0.2 Nd 0.7 O x The catalyst comprises 37.5% by weight of the carrier.

[0105] The lattice oxygen migration rate of the obtained catalyst is similar to that of α-Bi2Mo3O 12 Compared to the lattice oxygen migration rate of the catalyst, the lattice oxygen migration rate increased by 0.5 times. After 20 propylene in-situ pulses, the catalyst was oxygenated and then subjected to 20 more propylene pulses. The propylene conversion rate decreased by 4.7 percentage points. The results are shown in Table 1.

[0106] Test Example 1

[0107] The catalysts prepared in Examples 1 to 11 and Comparative Examples 1 to 2 were used to carry out the ammoxidation of propylene to produce acrylonitrile under the following conditions. The results are shown in Table 1.

[0108] The reactor and process conditions are as follows:

[0109] φ38 mm fluidized bed reactor

[0110] Reaction temperature 435℃

[0111] Reaction pressure 0.085MPa

[0112] Catalyst loading 400g

[0113] Catalyst propylene loading (WWH) 0.06 hours -1

[0114] The raw material ratio (molar): propylene / ammonia / air = 1 / 1.25 / 9.7.

[0115]

[0116] Test Example 2

[0117] The catalyst of Example 1 was pulsed with light olefins 20 times, and then the catalyst was pulsed again after being fully supplemented with oxygen, for a total of 20 pulses. The propylene conversion rate of each pulse was Figure 1 .

[0118] Test Example 3

[0119] With α-Bi2Mo3O 12 Compared with the lattice oxygen migration rate of 8 pulses, the lattice oxygen migration rate of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 is increased by a multiple of 1 / 2. Figure 2 In the figure, Alpha-Bi2Mo3O 12 α-Bi2Mo3O 12 .

[0120] from Figure 1 and Figure 2 It can be seen that the catalyst lattice oxygen migration rate of Example 1 is relatively high, and after 20 propylene pulses, the propylene conversion rate decreases slightly.

[0121] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, under the technical enlightenment provided by the present invention, as common knowledge in the art, other equivalent variations and improvements can be made, which should also be considered as the scope of protection of the present invention.

Claims

1. A method for preparing a composite oxide catalyst, comprising: (1) dissolving the Mo precursor to obtain solution I, and then dividing the solution I into multiple portions uniformly by weight; (2) dissolving a Bi precursor, a Fe precursor, a D precursor, and an E precursor to obtain a solution II, wherein D is selected from at least one of Li, Na, K, Rb, and Cs; and E is selected from at least one of Ca, Mg, La, Ce, Pr, Nd, Zr, Te, Sb, Ni, Cr, W, and Nb; (3) preparing a solution III containing a carrier; (4) The first portion of solution I is mixed with solution III, and then solution II is added to obtain a coprecipitation slurry. The remaining portions of solution I are then added sequentially at equal intervals, and the slurry pH is adjusted with an inorganic base, dried, and calcined in sequence. The multiple portions in step (1) are 2 to 5 portions; The pH value is 2 to 9; The temperature when inorganic alkali is used to adjust the pH value of the slurry is 60~150℃; The composite oxide catalyst comprises a carrier and an active component represented by the following general formula: Mo 11.0 Bi b Fe c D d E e O x , where b is in the range of 0.1~5.0; c is in the range of 0.1~5.0; d is in the range of 0.1~5.0; e is in the range of 0.1~5.0; and x is the total number of oxygen atoms required to satisfy the valence of each element in the catalyst.

2. The preparation method according to claim 1, characterized in that Step (4) is performed at the same interval, which is 5 to 60 minutes; and / or, the temperature when the inorganic base is used to adjust the pH value of the slurry is constant; And / or, the calcination conditions include: a temperature of 500-680° C.; and a calcination time of 0.2-4 hours.

3. The preparation method according to claim 2, characterized in that Step (4) is performed at the same interval, which is 8 to 35 minutes; And / or, the pH value is 3.5-9.0; And / or, the calcination conditions include: a temperature of 550-650° C.; and a calcination time of 0.5-2.5 hours.

4. The preparation method according to any one of claims 1 to 3, characterized in that The inorganic base is selected from at least one of potassium hydroxide, calcium hydroxide, magnesium hydroxide, cobalt hydroxide, nickel hydroxide, zirconium hydroxide and ammonium hydroxide.

5. The preparation method according to claim 4, characterized in that: The inorganic base is ammonium hydroxide.

6. The preparation method according to any one of claims 1 to 3, characterized in that The support comprises silica.

7. A composite oxide catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. The composite oxide catalyst according to claim 7, characterized in that The lattice oxygen migration rate of the composite oxide catalyst is similar to that of α-Bi2Mo3O 12 Compared with the lattice oxygen migration rate of α-Bi2Mo3O, the lattice oxygen migration rate of α-Bi2Mo3O is increased by 1.5~4.5 times. 12 The CAS number is 13595-85-2.

9. The composite oxide catalyst according to claim 7 or 8, characterized in that The weight of the carrier is 25 to 65% by weight of the catalyst.

10. The composite oxide catalyst according to claim 9, characterized in that The weight of the carrier is 35 to 65% by weight of the catalyst.

11. A method for preparing a nitrile compound, comprising: In the presence of the composite oxide catalyst according to any one of claims 7 to 10 or the composite oxide catalyst obtained by the preparation method according to any one of claims 1 to 6, a light olefin raw material, ammonia and air are contacted to carry out an ammoxidation reaction.

12. The method according to claim 11, characterized in that The light olefin raw material is propylene and / or isobutylene; and / or, the molar ratio of the light olefin feedstock, ammonia, and air is 1:1.05-1.3:9.2-9.8; And / or, the reaction conditions include: temperature of 420-440° C., reaction pressure of 0.06-0.14 MPa; And / or, the propylene loading of the light olefin catalyst is 0.06~0.10 h -1 .

Images