WO2021066411A1 - Catalyst for ammoxidation of propylene, preparation method therefor, and method for ammoxidation of propylene using same - Google Patents

Abstract

The present invention relates to a catalyst for ammoxidation of propylene, a method for preparing same, and a method for ammoxidation of propylene using same. In particular, an embodiment of the present invention provides a catalyst for ammoxidation of propylene exhibiting high activity in an ammoxidation reaction of propylene and also having a high amorphous phase content.

Description

Catalyst for ammoxidation of propylene, method for preparing the same, and method for ammoxidation of propylene using the same

Cross-reference with related application(s)

This application claims the benefit of priority based on Korean Patent Application No. 10-2019-0121172 filed September 30, 2019 and Korean Patent Application No. 10-2020-0124245 filed September 24, 2020. All contents disclosed in the literature are included as part of this specification.

The present invention relates to a catalyst for ammoxidation of propylene, a method for preparing the same, and a method for ammoxidation of propylene using the same.

The ammoxidation process of propylene is based on a reduction reaction of reacting ammonia and propylene and a mechanism of reoxidation by oxygen, the conversion rate of the reactant (i.e., propylene), and the selectivity of the reaction product (i.e., acrylonitrile). And catalysts of various compositions to increase the yield have been studied.

Specifically, since the Mo(molybdenum)-Bi(bismuth) oxide catalyst was presented, catalysts to which metals having various oxidation states were added have been studied in order to increase the catalytic activity and stability. As a result, depending on the type or amount of metal added, the yield of acrylonitrile is improved compared to the initial study.

However, despite the diversification of the catalyst composition, studies on its structure and physical properties were insufficient, and thus the conversion rate of the reactant (i.e., propylene) and the selectivity of the reaction product (i.e., acrylonitrile) were remarkable during the ammoxidation of propylene. There was a limit to the height of it.

Specifically, it is common to obtain a catalyst having a secondary particle structure in which metal oxide particles and silica particles are aggregated by co-precipitation of a metal precursor having a desired composition and a nano silica sol, followed by spray drying and firing.

However, the catalyst having the secondary particle structure inevitably has high crystallinity while going through the spray drying process during the manufacturing process. As such, a catalyst having high crystallinity may be easily cracked or crushed by a high temperature applied during the reaction, and Mo or the like may be eluted from the inside to the surface, thereby deteriorating catalyst performance.

The present invention is to provide a catalyst for ammoxidation of propylene that maintains a high level of catalytic activity while inhibiting Mo elution during ammoxidation reaction of propylene.

Specifically, one embodiment of the present invention provides a catalyst for ammoxidation of propylene, exhibiting high activity against ammoxidation reaction of propylene, and having a high content of an amorphous phase.

The catalyst of the embodiment may exhibit high activity against the ammoxidation reaction of propylene and a high content of the amorphous phase, so that the catalytic activity may be maintained at a high level while Mo elution during the ammoxidation reaction of propylene is suppressed.

Therefore, by using the catalyst of one embodiment, it is possible to convert propylene at a higher ratio and to produce acrylonitrile at a higher yield.

1 schematically shows a catalyst prepared using a spray drying method.

2 schematically shows a catalyst according to the embodiment.

3 shows the results of XRD analysis of the catalyst of an example to be described later.

4 shows the results of XRD analysis of the catalyst of a comparative example to be described later.

In the present invention, various transformations can be applied and various embodiments may be provided, and specific embodiments will be illustrated and described in detail. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

In addition, terms including ordinal numbers such as first and second to be used hereinafter may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude the possibility of preliminary exclusion.

Hereinafter, a catalyst for ammoxidation of propylene according to the embodiment will be described in detail with reference to the drawings.

Catalyst for ammoxidation of propylene

In one embodiment of the present invention,

Including a metal oxide represented by the following formula (1);

In X-ray diffraction analysis by Cu Cα, a first peak with an intensity of A appears within the range of 2θ of 26.3±0.5°, and a second peak with an intensity of B within the range of 28.3±0.5°,

The intensity ratio (A/B) of the first peak to the second peak is 1.5 or more,

A catalyst for ammoxidation of propylene is provided:

[Formula 1]

In Formula 1,

A and B are different, and each independently is one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba,

C is one or more elements of Li, Na, K, Rb, and Cs,

D is one or more elements of Cr, W, B, Al, Ca, and V,

Wherein a to f, x, and y are the mole fractions of atoms or groups of atoms,

a is 0.1 to 7, b is 0.1 to 7, provided that the sum of a and b is 0.1 to 7,

c is 0.1 to 10, d is 0.01 to 5, e is 0.1 to 10, f is 0 to 10,

x is 11 to 14, and y is a value that can be determined by the respective oxidation numbers of Mo, Bi, Fe, A, B, C, and D.

As mentioned above, as a catalyst for ammoxidation of propylene, a catalyst having a secondary particle structure prepared through coprecipitation and spray drying of a metal precursor and a nano silica sol is known.

The catalyst having the secondary particle structure has a problem in that the metal oxide particles are evenly distributed inside and outside, but contain almost no pores, so that the adsorption amount of reactants per unit volume is small, and the reaction activity is low.

On the other hand, the catalyst having the secondary particle structure inevitably has high crystallinity while going through the spray drying process in the manufacturing process. As such, a catalyst having high crystallinity may be easily cracked or crushed by a high temperature applied during the reaction, and Mo or the like may be eluted from the inside to the surface, thereby deteriorating catalyst performance.

On the other hand, the catalyst of the embodiment has a high content of amorphous phosphorus phase while exhibiting high activity against the ammoxidation reaction of propylene, and thus the catalytic activity can be maintained at a high level while Mo elution is suppressed during the ammoxidation reaction of propylene. .

Here, the amorphous phase exhibiting high activity against the ammoxidation reaction of propylene may be a complex oxide phase of molybdenum (Mo) and dissimilar metals, such as a CoMoO _{4 phase.}

Specifically, when X-ray diffraction (XRD) analysis of the catalyst of the embodiment, the first peak of intensity B appears within the range of 2θ of 26.3±0.5°, and the intensity within the range of 2θ of 28.3±0.5°. A second peak of B may appear.

Here, the first peak may appear by a complex oxide phase of molybdenum (Mo) and a dissimilar metal, such as a CoMoO _{4 phase.} In addition, the second peak may appear by a molybdenum (Mo) oxide phase, that is, a MoO _{3 phase.}

The complex oxide phase of molybdenum (Mo) and dissimilar metals exhibits activity against propylene ammoxidation, whereas the MoO ₃ phase has no activity against propylene ammoxidation.

The catalyst of the secondary particle structure is prepared from a slurry in which a silica sol and a metal oxide precursor are heterogeneously mixed, _{the content of the MoO 3} phase, which is an inert phase, is relatively high, and the intensity ratio of the first peak to the second peak ( A/B) may be less than 1.5. Accordingly, Mo elution occurs during the ammoxidation reaction of propylene, and catalytic activity may decrease.

On the other hand, the catalyst of the embodiment has a relatively high content of the phase of the complex oxide of a dissimilar metal, which is an active phase, and an intensity ratio (A/B) of the first peak to the second peak is 1.5 or more, Specifically, it may be 2.0 or more, more specifically 2.5 or more, such as 3.0 or more.

A more detailed description will be described later, but the catalyst of the embodiment may be prepared using an impregnation method. When a transparent solution in a very uniform state is supported on silica, the metal components are well bonded to each other, and the _{probability of forming the MoO 3} phase alone is very low.

In particular, since the large surface area of the carrier itself is utilized, the dispersibility of active phases such _{as FeMoO 3} and Bi ₂ MoO _{6 as well as CoMoO 4 is greatly improved.} Although the XRD peak intensity tends to decrease when the dispersibility is improved, the XRD pattern is formed in a state in which the peak of _{CoMoO 4} is considerably developed because the amount of Mo and Co added for metal oxide formation in the above embodiment is large. Can be.

Accordingly, the catalyst of the exemplary embodiment may maintain a high level of catalytic activity while inhibiting Mo elution during ammoxidation reaction of propylene compared to the catalyst having the secondary particle structure.

On the other hand, a catalyst that does not contain heterogeneous metals other than Bi, such as a catalyst containing only Mo and Bi as metal components, cannot form a complex oxide phase of molybdenum (Mo) and dissimilar metals, and thus XRD During the analysis, the first peak cannot appear.

In other words, since the catalyst that does not contain heterogeneous metals other than Bi contains _{only the inert phase and crystalline MoO 3} phase, Mo elution occurs during the ammoxidation reaction of propylene, and catalytic activity may decrease.

Hereinafter, the catalyst of the embodiment will be described in detail.

D50 particle size, pore volume and BET specific surface area of catalyst

The catalyst of the embodiment may provide an effective surface area capable of participating in the reaction as well as the external surface area, including a large number of bulky pores.

Specifically, the catalyst of the embodiment may have a D50 particle diameter of 10 to 300 μm, include pores having a volume of ^{0.3 to 1.3 cm 3} /g, and have a BET specific surface area of ^{50 to 300 m 2 /g.}

The BET specific surface area and the volume of pores provided by the catalyst of the embodiment are improved compared to the catalyst of the secondary particle structure, and thus, while converting propylene at a higher ratio, acrylonitrile with higher selectivity and yield Can be obtained.

Within the range presented above, as the pore volume included in the catalyst of the embodiment increases, the BET specific surface area of the catalyst including the same may increase. However, when the volume of pores included in the catalyst of the embodiment is too large, the content of the metal oxide is relatively reduced, and thus catalytic activity may decrease.

Accordingly, it is possible to control the BET specific surface area and pore volume, etc., by comprehensively considering the properties desired as the catalyst of the embodiment.

For example, the catalyst of one embodiment has a lower limit of D50 particle size of 10 µm or more, 20 µm or more, 30 µm or more, or 45 µm or more, and an upper limit of 300 µm or less, 280 µm or less, 260 µm or less, 240 µm or less , 220 μm or less, or 200 μm or less.

In addition, the catalyst of one embodiment, while having a pore volume of 0.3 cm ³ /g or more, 0.35 cm ³ /g or more, 0.4 cm ³ /g or more, 0.45 cm ³ /g or more, or 0.5 cm ³ /g or more, 1.3 It can be cm ³ /g or less, 1.2 cm ³ /g or less, 1.1 cm ³ /g or less, and 1.0 cm ³ /g or less.

In addition, the catalyst of the embodiment is 50 m ² /g or more, 70 m ² /g or more, 90 m ² /g or more, 110 m ² /g or more, or 120 m ² /g, while 300 m ² /g Hereinafter, it may have a BET specific surface area of ^{270 m 2} /g or less, 240 m ² /g or less, 210 m ² /g or less, or 180 m ^{2 /g or less.}

Metal oxide

On the other hand, even if it has the same structure as the catalyst of the embodiment, if the type and content of the components constituting the metal oxide do not satisfy the above formula (1), the active sites of the catalyst having insufficient or excessively high density for ammoxidation of propylene are formed. Can be.

Accordingly, it is necessary to satisfy the type and content of the metal oxide to satisfy the formula (1). For example, the metal oxide may be represented by the following Formula 1-1, and as a synergistic effect of the metal components contained therein, it may be advantageous to increase the active point for the ammoxidation reaction of propylene:

[Formula 1-1]

In Formula 1-1, the definitions of x, a to e, and y are as described above.

If you want to directly measure the composition and content of the metal oxide, it can be measured using measuring equipment such as ICP (Inductively Coupled Plasma).

Catalyst structure

As mentioned above, a generally known catalyst for ammoxidation of propylene is prepared through coprecipitation and spray drying, and is provided in a secondary particle structure in which metal oxide nanoparticles and silica nanoparticles are aggregated (FIG. 1).

This is because, instead of evenly distributed inside and outside of the metal oxide particles, a portion that can participate in the ammoxidation reaction of propylene is limited to the outer surface portion (i.e., the surface of the secondary particles), and provides a small surface area. The amount of ammonia desorbed from the catalyst surface during ammoxidation reaction is large.

On the other hand, the catalyst of the embodiment may be prepared by an impregnation method, and thus may be provided in a structure in which a metal oxide is supported on a silica carrier (FIG. 2).

For example, a silica carrier may be immersed in a metal precursor solution prepared to satisfy a stoichiometric molar ratio of a desired metal oxide, and the metal precursor solution may be impregnated in the silica carrier.

Thereafter, when the solvent (i.e., water) is removed through the drying process, the metal precursor remains on the pore walls of the silica carrier, and the metal precursor is oxidized in the firing process to form a film that continuously coats the pore walls of the silica carrier. have.

The catalyst of one embodiment prepared as described above may further include a silica carrier supporting the metal oxide.

In this case, the catalyst of the embodiment may include a silica carrier including second pores; An inner coating layer that continuously coats the walls of the second pores and includes a metal oxide represented by Chemical Formula 1; And first pores located inside the second pores and occupying an empty space excluding the inner coating layer.

The catalyst having the above structure may be more durable than a catalyst prepared with the same composition through coprecipitation and spray drying even if the classification process is not performed as a post-treatment after manufacture.

In addition, by evenly supporting the metal oxide in the inner pores of the silica carrier, the portion capable of participating in the ammoxidation reaction of propylene is extended to not only the outer surface portion (i.e., the surface of the catalyst) but also the inner surface (pores). have.

Specifically, the catalyst of the embodiment may have an egg-shell structure.

To this end, the silica carrier may include a non-porous core portion; And a porous shell portion positioned on the surface of the non-porous core and including second pores.

More specifically, the porous shell includes a concave portion and a convex portion of a surface, and the concave portion has the second pores open to the surface of the porous shell. It may be formed.

Accordingly, the catalyst of the embodiment may include a coating layer that continuously coats the concave portions and the convex portions of the porous shell and includes a metal oxide represented by Chemical Formula 1; And first pores occupying an empty space excluding the coating layer in the concave portion of the silica carrier.

The catalyst structure of the embodiment can be confirmed through an electron microscope such as a scanning electron microscope (SEM).

Metal oxide: weight ratio of silica carrier

When the catalyst of one embodiment further includes the silica carrier, the weight ratio of the metal oxide and the silica carrier is 10:90 to 15:95, specifically 20:80 to 50:50, such as 15:85 to 35 It can be set as :65 (metal oxide: silica carrier).

Within this range, the catalyst of the embodiment may have high selectivity of acrylonitrile with high activity.

If the weight ratio of the metal oxide and the silica carrier is to be measured directly, it can be measured using a measuring device such as ICP (Inductively Coupled Plasma).

Method for producing a catalyst for ammoxidation of propylene

In another embodiment of the present invention, preparing a first precursor solution containing a Mo precursor,

Fe precursor; And preparing a second precursor solution comprising a precursor of one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba,

Bi precursor; A precursor of one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba different from the second precursor solution; And preparing a third precursor solution comprising a precursor of one or more elements of Li, Na, K, Rb, and Cs,

Mixing the first to third precursor solutions so that the molar ratio of the metal satisfies the stoichiometric molar ratio of Formula 1 below,

Supporting a mixture of the first to third precursor solutions on a silica carrier,

Drying the silica carrier on which the mixture of the first to third precursor solutions is supported, and

There is provided a method comprising the step of firing the dried material:

[Formula 1]

In Formula 1, the definitions of x, a to e, and y are as described above.

The manufacturing method of the above embodiment corresponds to the method of manufacturing the catalyst of the above embodiment by using an impregnation method.

Hereinafter, descriptions overlapping with those described above will be omitted, and the manufacturing method of the embodiment will be described step by step.

Manufacturing process of the first aqueous precursor solution

The step of preparing the first precursor solution may be a step of dissolving the Mo precursor in water at 50 to 90° C. to prepare an aqueous solution including water and the Mo precursor.

In the step of preparing the first aqueous precursor solution, an additive including citric acid, oxalic acid, or a mixture thereof may be used.

In the catalyst manufacturing process using coprecipitation and spray drying, the additive functions as a strength modifier. However, in the above embodiment, the additive makes the first precursor solution transparent, so that a mixture precursor in a completely dissolved state can be prepared.

When the additive is added, the weight ratio of the molybdenum precursor and the additive may satisfy 1:0.1 to 1:1, specifically 1:0.2 to 1:0.7, and the solubility of the molybdenum precursor increases within this range. It can be, but is not limited thereto.

Manufacturing process of the second precursor solution

The step of preparing the second precursor solution may include, in water at 20 to 50° C., an Fe precursor; And it may be a step of dissolving a second precursor including one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba. Optionally, a precursor further comprising a D precursor (D = one or more elements of Cr, W, B, Al, Ca, and V) may be further dissolved.

Here, it is possible to select the type and amount of the precursor in consideration of the composition of the metal oxide in the final catalyst.

For example, an aqueous solution including water, an Fe precursor, and a Co precursor may be prepared in consideration of the metal oxide composition that satisfies Chemical Formula 1-1.

Manufacturing process of the third precursor solution

The step of preparing the third precursor solution may include a Bi precursor in nitric acid at 20 to 50° C.; A precursor of one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba different from the second precursor solution; And it may be a step of dissolving a precursor of one or more elements of Li, Na, K, Rb, and Cs.

Also here, the type and amount of the precursor may be selected in consideration of the composition of the metal oxide in the final target catalyst.

For example, a solution including nitric acid, a Bi precursor, a Ni precursor, and a K precursor may be prepared in consideration of the metal oxide composition that satisfies Formula 1-1.

Precursor solution mixing process

The processes of preparing the first to third precursor solutions are each independent, and the order of preparation is not limited.

However, in consideration of the characteristics of each metal, the mixing of the first to third precursor solutions includes mixing the second and third precursor solutions, and a mixture of the second and third precursor solutions It may include dropping into the first precursor solution.

In addition, when the first to third precursor solutions are mixed, the mixing ratio may be controlled so that the molar ratio of metals satisfies the stoichiometric molar ratio of Chemical Formula 1, specifically, Chemical Formula 1-1.

Precursor mixed solution loading process

After preparing a mixture of the first to third precursor solutions, it may be supported on a silica carrier.

Here, silica with a particle size of 10 to 200 μm, a pore size of 20 to 25 nm, a pore volume of 1 to 3 cm ³ /g according to the nitrogen adsorption method, and a BET specific surface area of 250 to 300 m ^{2 /g (} SiO ₂ ) particles may be added to the mixture of the first to third precursor solutions and mixed, so that the mixture of the first to third precursor solutions is supported in the pores of the silica carrier.

Specifically, the step of supporting the mixture of the first to third precursor solutions on the silica carrier includes first mixing the silica carrier and the first to third precursor solutions within a temperature range of 20 to 30°C. And secondary mixing the first mixture within a temperature range of 70 to 90°C, and the first and second mixing times may be independently set to 1 to 3 hours.

However, this is an example and is not particularly limited as long as it is a condition that allows the mixture of the first to third precursor solutions to be sufficiently supported on the silica carrier.

Drying and firing process

Thereafter, the silica carrier on which the mixture of the first to third precursor solutions is supported is dried for 5 to 12 hours in a temperature range of 100 to 120° C., and then calcined for 1 to 6 hours in a temperature range of 500 to 700° C. To finally obtain a catalyst.

However, the drying and firing conditions are only examples, and a condition capable of sufficiently removing the solvent from the pores of the carrier and oxidizing the metal precursor is sufficient.

The structure of the catalyst thus formed is as described above.

Propylene ammoxidation method

In another embodiment of the present invention, there is provided a method for ammoxidation of propylene, comprising reacting propylene and ammonia in the presence of the catalyst of the above-described embodiment in a reactor.

The catalyst of the embodiment has high activity and stability at high temperature, and is used for ammoxidation reaction of propylene to increase the conversion rate of propylene, selectivity and yield of acrylonitrile.

For matters other than the catalyst of the embodiment, it is possible to refer to matters generally known in the art, and a detailed description thereof will be omitted.

Hereinafter, embodiments of the present invention will be described in more detail in the following examples. However, the following examples are merely illustrative of embodiments of the invention, and the contents of the present invention are not limited by the following examples.

Example 1

(1) Manufacturing process of precursor solution

Mo precursor ((NH ₄ ) ₆ Mo ₇ O ₂₄ ) 4.24 g was dissolved in 85° C. water, and 3 g of oxalic acid or citric acid was added thereto to prepare a Mo precursor solution.

Independently, by dissolving 2.5 g of Fe precursor (Fe(NO ₃ ) ₂ ·9H ₂ O) and 3.5 g of Co precursor (Co(NO ₃ ) ₂ ·6H ₂ O) in water at room temperature, the precursor of Fe and Co A mixed solution was prepared.

Also independently, in a mixture of Bi precursor (Bi(NO ₃ ) ₃ ·5H ₂ O) 1.46 g, Ni precursor (Ni(NO ₃ ) ₂ ·6H ₂ O) 0.58 g, and K precursor (KNO _{3) 0.2 g} By adding 2 g of nitric acid, a mixed solution of Bi, Ni, and K precursors was prepared.

The Fe and Co precursor mixture solution and the Bi, Ni, and K precursor mixture solution are mixed while stirring, and then added dropwise to the Mo precursor solution to mix Mo, Bi, Fe, Ni, Co and K precursors. A solution was obtained.

In the precursor mixture solution, the total amount of water is 45 g.

(2) Supporting process of precursor solution in silica carrier (using impregnation method)

Silica (SiO _{2 with a} particle size of 50-150 ㎛, a pore size of 10-25 ㎚, a pore volume of 1 to 3 cm ³ /g according to the nitrogen adsorption method, and a BET specific surface area of 500-600 m ^{2 /g)} ) Particles were used as carriers.

Into the Mo, Bi, Fe, Ni, Co, and K precursor mixed solution, the silica carrier (13)g was added, and the mixture was sequentially stirred at room temperature and 80°C for 2 hours, respectively, and the Mo, The mixed solution of Bi, Fe, Ni, Co, and K precursors was sufficiently supported.

(3) Manufacturing process of a catalyst supporting a metal oxide in a silica carrier

Thereafter, the silica carrier carrying the Mo, Bi, Fe, Ni, Co, and K precursor mixture solution was recovered and dried in an oven at 110° C. for 12 hours, and then maintained at a temperature of 580° C. in a tubular kiln in a nitrogen atmosphere. By heat treatment for a period of time, the catalyst of Example 1 was obtained on which 25% by weight of a metal oxide (however, the mole fraction of Mo in the metal oxide was 12) was supported.

(4) Process of ammoxidation of flophyllene

In order to activate the catalyst, 0.2 g of the catalyst of Example 1 was charged into the reactor filled with 0.05 g of quartz fiber.

As described above, the internal pressure of the reactor filled with the quartz fiber and the catalyst was maintained at atmospheric pressure (1 atm), and the internal temperature of the reactor was raised at a temperature increase rate of 5°C, while nitrogen and ammonia gas were flowed as a pretreatment process. Accordingly, the temperature inside the reactor reached 400° C., which is the temperature at which the ammoxidation reaction is possible, so that sufficient pretreatment was performed.

In the reactor where the pretreatment was completed, air was supplied together with propylene and ammonia as reactants, and the ammoxidation process of propylene was performed. At this time, the supply amount of the reactant is composed to be a volume ratio of propylene: ammonia: air = 1:1.1:2 = 1.5 to 1:4:3, and the total weight hourly space velocity (WHSV) of propylene, ammonia, and air. ^{) Was set} to be 1 h -1.

After completion of the ammoxidation reaction, the product was recovered and analyzed using various equipment to confirm whether acrylonitrile was well produced.

The analysis method, analysis result, etc. will be described in detail in the experimental examples described later.

Examples 2 to 4

(1) catalyst manufacturing process (using the impregnation method)

A precursor solution was prepared according to the composition shown in Table 1 below, and the silica carrier shown in Table 2 was used, but the rest were the same as in Example 1 to prepare each of the catalysts of Examples 2 to 4.

(2) Process of ammoxidation of flophyllene

In addition, instead of the catalyst of Example 1, each catalyst of Examples 2 to 4 was used to perform the ammoxidation process of flophyllene, and the product was recovered, and analysis was performed in the same manner as in Example 1.

Comparative Example 1

(1) Catalyst manufacturing process (using spray drying after coprecipitation)

First, 200 g of Mo precursor (Ammonium Molybdate) was dissolved in 200 g of water at 85° C., 270 g of silica sol was added thereto, stirred, and heated to about 50° C. to prepare Solution A.

Independently, Bi precursor (Bi(NO ₃ ) ₃ ·5H ₂ O) 69.4 g, Co precursor (Co(NO ₃ ) ₂ ·6H ₂ O) 165 g, Fe precursor (Fe(NO ₃ ) ₂ ·9H ₂ O) 115 g, and Ni precursor (Ni(NO ₃ ) ₂ ·6H ₂ O) 10 g, K precursor (KNO ₃ ) 10 g of nitric acid was added to a mixture of 17.5 g and heated to 50° C. to prepare solution B. .

The solutions A and B were mixed while stirring to obtain an aqueous slurry, and the mixed aqueous slurry of the solutions A and B was dried at 150° C. using a rotary nozzle spray dryer. The thus obtained solid dried product was calcined at 580° C. for 3 hours to obtain a catalyst of Comparative Example 1.

(2) Process of ammoxidation of flophyllene

The catalyst of Comparative Example 1 was used instead of the catalyst of Example 1, and the ammoxidation process of flophyllene was performed in the same manner as in Example 1.

After completion of the ammoxidation reaction of Comparative Example 1, the product was recovered and analyzed in the same manner as in Example 1.

Comparative Example 2

(1) catalyst manufacturing process (using the impregnation method)

A precursor solution was prepared according to the composition shown in Table 1 below, and the silica carrier shown in Table 2 was used, but the rest were the same as in Example 1 to prepare a catalyst of Comparative Example 2.

(2) Process of ammoxidation of flophyllene

In addition, after performing the ammoxidation process of flophyllene using the catalyst of Comparative Example 2 instead of the catalyst of Example 1, the product was recovered, and analysis was performed in the same manner as in Example 1.

In Table 1, Mo is (NH ₄ ) ₆ Mo ₇ O ₂₄ , Bi is Bi(NO ₃ ) ₃ ·5H ₂ O, Co is Co(NO ₃ ) ₂ ·6H ₂ O, and Fe is Fe( NO ₃ ) ₂ ·9H ₂ O, Ni is Ni(NO ₃ ) ₂ ·6H ₂ O, and K is KNO ₃ . Also, the omitted unit is g.

Meanwhile, the input amount of the raw material in Table 1 is calculated in consideration of the target composition of Table 2, that is, the stoichiometric molar ratio of the final metal oxide and the content of the metal oxide. If you want to directly measure the metal oxide composition and content of Table 2, it can be measured using a measuring device such as ICP (Inductively Coupled Plasma, Inductively Coupled Plasma).

Experimental Example 1: Catalyst Analysis

Each catalyst of Example 1 and Comparative Example 1 was analyzed according to the following analysis method:

XRD main peak intensity ratio : For each catalyst of Example 1 and Comparative Example 1, diffraction analysis (X-Ray Diffraction, XRD) using Cu Kα X-ray was performed, and the analysis results are shown in FIG. 3. (Example 1) and Fig. 4 (Comparative Example 1) respectively.

In common in FIGS. 3 (Example 1) and 4 (Comparative Example 1), main peaks appear at 26.3±0.5° and 28.3±0.5°. The peak intensity at 26.3±0.5° is referred to as A, and the peak intensity at 28.3±0.5° is referred to as B, and the peak intensity ratio of A/B for each catalyst was calculated, and the calculated values are shown in Table 1. .

BET specific surface area : For each catalyst of Example 1 and Comparative Example 1, nitrogen gas under liquid nitrogen temperature (77 K) using a BET specific surface area measuring device (manufacturer: BEL Japan, device name: BELSORP-mino X) The specific surface area was evaluated from the adsorption amount, and the evaluation results are shown in Table 1.

Pore volume : Using an apparatus according to ASTM D4641 (manufacturer: BEL Japan, device name: BELSORP-mino X), the pore volume in each catalyst of Example 1 and Comparative Example 1 was measured, and the measurement results are shown in Table 1. .

Catalyst structure : It can be confirmed through an electron microscope such as a scanning electron microscope (SEM).

1) In Examples 1 to 4 and Comparative Examples 1 to 4 and 1 of Comparative Example 1, XRD peak intensity characteristics, pore volume, and BET specific surface area characteristics may be related to a method of preparing a catalyst.

Specifically, the catalyst of Comparative Example 1 formed a relatively large number of crystalline phases through co-precipitation and spray drying processes, resulting in high crystallinity.

In addition, the catalyst of Comparative Example 1 has a secondary particle structure that hardly contains pores while undergoing co-precipitation and spray drying processes, and the effective surface area capable of participating in the reaction is limited to the external surface area.

On the other hand, in the catalysts of Examples 1 to 4, relatively large amounts of amorphous phases were formed while being prepared by the impregnation method, resulting in low crystallinity.

In addition, the catalysts of Examples 1 to 4 have a structure including a large number of large pores while being prepared by an impregnation method, and an effective surface area capable of participating in the reaction has been expanded into pores.

In fact, upon X-ray diffraction (XRD) analysis of the catalysts of Examples 1 to 4 and Comparative Example 1, the first peak of intensity B appears within the range of 2θ of 26.3±0.5° by the _{CoMoO 4 phase, and MoO} The second peak of intensity B appeared within the range of 2θ of 28.3±0.5° by _{three phases.}

The CoMoO ₄ phase is an active phase for propylene ammoxidation, and the MoO ₃ phase is an inactive phase. Accordingly, it can be seen that the higher the XRD peak intensity ratio (A/B), the lower the crystallinity and the lower the activity of the catalyst.

In this context, the catalyst of Comparative Example 1 has an XRD peak intensity ratio (A/B) of only 1.47, which is evaluated as having high crystallinity and low activity. On the other hand, the catalysts of Examples 1 to 4 satisfies a range in which the XRD peak intensity ratio (A/B) is high, and thus it is evaluated to have low crystallinity and high activity.

In addition, compared to Comparative Example 1, it was confirmed that the pore volume contained in the catalysts of Examples 1 to 4 was large, and had a wider BET specific surface area.

2) Comparison of Examples 1 to 4 and Comparative Example 2

Meanwhile, in Examples 1 to 4 and Comparative Example 1, the XRD peak intensity characteristics, pore volume, and BET specific surface area characteristics may be related to the composition of the metal oxide in the catalyst.

Specifically, although the catalyst of Comparative Example 2 was prepared by the impregnation method, only _{a peak due to MoO 3} as an inactive phase was formed, and no peak due to an active phase was formed due to the influence of a metal oxide containing only Mo and Bi.

On the other hand, the catalysts of Examples 1 to 4, while being prepared by the impregnation method, under the influence of a metal oxide containing not only Mo and Bi but also a number of suitable metal components, in contrast to the peak due to the _{inactive phase MoO 3, the active phase} (In particular, CoMoO ₄ ) formed a wider peak area.

In addition, it was evaluated that the catalysts of Examples 1 to 4 were uniformly coated on the pore walls of the silica carrier by _{CoMoO 4, an active phase and a crystalline phase, thereby securing an appropriate pore volume and a BET specific surface area.}

Experimental Example 2: Analysis of ammoxidation product

Each ammoxidation product of Examples 1 to 4 and Comparative Examples 1 and 2 was prepared using chromatography (Gas chromatography, manufacturer: Agilent, device name: GC6890N) equipped with FID (Flame Ionization Detector) and TCD (thermal conductivity detector). Analyzed.

Specifically, as FID, products such as ethylene (ehthlene), hydrogen cyanide, acetaldehyde, acetonitrile, and acetonitrile were analyzed, and as TCD _{, NH 3} , O ₂ , Gas products such as CO and CO ₂ were analyzed to determine the number of moles of propylene reacted in Example 1 and Comparative Example 1 and the number of moles of ammoxidation product, respectively.

By substituting the number of moles of propylene supplied in addition to the analysis results according to the following 1, 2, and 3, the conversion of propylene, the selectivity and yield of acrylonitrile, a product of the ammoxidation of propylene, are calculated, It is described in Table 2.

[Equation 1]

[Equation 2]

[Equation 3]

The catalyst of Comparative Example 1 was prepared through coprecipitation and spray drying, and as a result, the effective surface area (BET specific surface area) capable of participating in the reaction was limited to the outer surface portion, and _{the formation of CoMoO 4} , an active phase and amorphous, was suppressed.

Accordingly, the catalyst of Comparative Example 1 has low activity due to a narrow effective surface area and low active phase content, and may be easily cracked or broken due to high crystallinity. In particular, when the catalyst is cracked or broken due to high temperature during ammoxidation reaction of propylene, Mo or the like is eluted from the inside of the catalyst to the surface, and catalyst performance may be deteriorated.

In fact, in the reaction using the catalyst of Comparative Example 1, it was confirmed that the conversion rate of propylene was 56.5%, and the yield of acrylonitrile was only 33.7%.

Meanwhile, although the catalyst of Comparative Example 2 was prepared by the impregnation method, effective active phases capable of participating in the reaction, especially active phase (CoMoO ₄ ), were formed under the influence of metal oxides containing only Mo and Bi as metal components. Can't be

In fact, in the reaction using the catalyst of Comparative Example 2, it was confirmed that the conversion rate of propylene and the yield of acrylonitrile were lower than that of Comparative Example 1.

On the other hand, the catalysts of Examples 1 to 4, as a result of being prepared by the impregnation method, have a large effective surface area (BET specific surface area) capable of participating in the reaction, and the formation of the _{active phase, CoMoO 4, is increased.}

Accordingly, the catalysts of Examples 1 to 4 have high activity due to the large effective surface area and high active phase content, and may not be broken or broken even at high temperatures applied during the ammoxidation reaction of propylene.

In fact, during the reaction using the catalysts of Examples 1 to 4, the conversion rate of propylene was found to be as high as 70% or more, and the yield of acrylonitrile was as high as 60% or more.

Overall, a catalyst having a metal oxide composition satisfying the above-described Formula 1 and having a XRD main peak intensity ratio (A/B) of 1.5 or more can significantly improve the conversion of propylene and the yield of acrylonitrile during ammoxidation reaction It is evaluated as being.

Claims (20)

1. Including a metal oxide represented by the following formula (1);

   In X-ray diffraction analysis by Cu Cα, a first peak with an intensity of A appears within a range of 2θ of 26.3±0.5°, and a second peak of intensity B within a range of 28.3±0.5°

   The intensity ratio (A/B) of the first peak to the second peak is 1.5 or more,

   Catalyst for ammoxidation of propylene:

   [Formula 1]

   

   In Formula 1,

   A and B are different, and each independently is one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba,

   C is one or more elements of Li, Na, K, Rb, and Cs,

   D is one or more elements of Cr, W, B, Al, Ca, and V,

   Wherein a to f, x, and y are the mole fractions of atoms or groups of atoms,

   a is 0.1 to 7, b is 0.1 to 7, provided that the sum of a and b is 0.1 to 7,

   c is 0.1 to 10, d is 0.01 to 5, e is 0.1 to 10, f is 0 to 10,

   x is 11 to 14, and y is a value that can be determined by the respective oxidation numbers of Mo, Bi, Fe, A, B, C, and D.
2. The method of claim 1,

   The catalyst,

   In X-ray diffraction analysis by Cu Cα, the intensity ratio (A/B) of the first peak to the second peak is 3.0 or more,

   Catalyst for ammoxidation of propylene.
3. The method of claim 1,

   The BET specific surface area of the catalyst is,

   That is 50 to 300 m ² /g,

   Catalyst for ammoxidation of propylene.
4. The method of claim 1,

   The pore volume in the catalyst is,

   That is from 0.3 to 1.3 cm ³ /g,

   Catalyst for ammoxidation of propylene.
5. The method of claim 1,

   The metal oxide,

   It is represented by the following formula 1-1,

   Catalyst for ammoxidation of propylene:

   [Formula 1-1]

   

   In Formula 1-1,

   The definitions of x, a to e and y are the same as in claim 1.
6. The method of claim 1,

   The catalyst,

   It further comprises a silica carrier supporting the metal oxide;

   Catalyst for ammoxidation of propylene.
7. The method of claim 6,

   The weight ratio of the metal oxide and the silica carrier is 15:85 to 35:65,

   Catalyst for ammoxidation of propylene.
8. Preparing a first precursor solution containing a Mo precursor,

   Fe precursor; And preparing a second precursor solution containing at least one element of Ni, Mn, Co, Zn, Mg, Ca, and Ba,

   Bi precursor; A precursor of one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba different from the second precursor solution; And preparing a third precursor solution comprising a precursor of one or more elements of Li, Na, K, Rb, and Cs,

   Mixing the first to third precursor solutions so that the molar ratio of the metal satisfies the stoichiometric molar ratio of Formula 1 below,

   Supporting a mixture of the first to third precursor solutions on a silica carrier,

   Drying the silica carrier on which the mixture of the first to third precursor solutions is supported, and

   Comprising the step of firing the dried material,

   Method for producing a catalyst for ammoxidation of propylene:

   [Formula 1]

   

   In Formula 1,

   A and B are different, and each independently is one or more elements of Ni, Mn, Co, Zn, Mg, Ca, and Ba,

   C is one or more elements of Li, Na, K, Rb, and Cs,

   D is one or more elements of Cr, W, B, Al, Ca, and V,

   Wherein a to f, x, and y are the mole fractions of atoms or groups of atoms,

   a is 0.1 to 7, b is 0.1 to 7, provided that the sum of a and b is 0.1 to 7,

   c is 0.1 to 10, d is 0.01 to 5, e is 0.1 to 10, f is 0 to 10,

   x is 11 to 14, and y is a value that can be determined by the respective oxidation numbers of Mo, Bi, Fe, A, B, C, and D.
9. The method of claim 8,

   In the step of preparing the first precursor solution,

   To add citric acid, oxalic acid or a mixture thereof as an additive,

   Method for producing a catalyst for ammoxidation of propylene.
10. The method of claim 8,

    The step of preparing the first precursor solution,

    That is carried out at 50 to 90 °C,

    Method for producing a catalyst for ammoxidation of propylene.
11. The method of claim 8,

    The step of preparing the second precursor solution,

    In the step of preparing an aqueous solution containing water, an Fe precursor and a Co precursor,

    Method for producing a catalyst for ammoxidation of propylene.
12. The method of claim 8,

    The step of preparing the third precursor solution,

    In the step of preparing a solution containing nitric acid, a Bi precursor, a Ni precursor, and a K precursor,

    Method for producing a catalyst for ammoxidation of propylene.
13. The method of claim 8,

    The step of preparing the second precursor solution and the step of preparing the second precursor solution, each independently,

    Which is carried out at 20 to 50 °C,

    Method for producing a catalyst for ammoxidation of propylene.
14. The method of claim 8,

    Mixing the first to third precursor solutions,

    Mixing the second and third precursor solutions, and

    Including the step of dropping the mixture of the second and third precursor solution to the first precursor solution,

    Method for producing a catalyst for ammoxidation of propylene.
15. The method of claim 8,

    The step of supporting the mixture of the first to third precursor solutions on the silica carrier,

    First mixing the silica carrier and the first to third precursor solutions within a temperature range of 20 to 30 °C, and

    Including the step of secondary mixing the first mixture within a temperature range of 70 to 90 ℃,

    Method for producing a catalyst for ammoxidation of propylene.
16. The method of claim 8,

    The first and second mixing, each independently,

    Which is carried out for 1 to 3 hours,

    Method for producing a catalyst for ammoxidation of propylene.
17. The method of claim 8,

    Drying the silica carrier on which the mixture of the first to third precursor solutions is supported,

    To be carried out within a temperature range of 100 to 120 ℃,

    Method for producing a catalyst for ammoxidation of propylene.
18. The method of claim 8,

    Drying the silica carrier on which the mixture of the first to third precursor solutions is supported,

    Which is carried out for 5 to 12 hours,

    Method for producing a catalyst for ammoxidation of propylene.
19. The method of claim 8,

    The step of firing the dried material,

    It is to be carried out within a temperature range of 500 to 700 ℃,

    Method for producing a catalyst for ammoxidation of propylene.
20. In the reactor, comprising the step of reacting propylene and ammonia in the presence of the catalyst of claim 1,

    Method for ammoxidation of propylene.

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