KR20220014701A - Ammoxidation catalyst for propylene, manufacturing method of the same catalyst, ammoxidation methode using the same catalyst - Google Patents

Abstract

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. Specifically, in one embodiment of the present invention, provided is a catalyst for ammoxidation of propylene in which a metal oxide of a specific composition is supported on a silica carrier and the amount of ammonia adsorption in a supported state is improved.

Description

Catalyst for ammoxidation of propylene, manufacturing method thereof, and ammoxidation method of propylene using the same

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.

Acrylonitrile (AN) is not only used as one of the raw materials of ABS resin, but also can be applied to various chemical products, so demand and production are increasing worldwide.

Such acrylonitrile can be prepared through the ammoxidation reaction of propylene. The ammoxidation reaction of propylene includes a reduction reaction of ammonia and propylene and a reoxidation reaction by oxygen. In order to control the heat generated during these reactions, a fluidized bed reactor is generally used.

As a catalyst for the ammoxidation of propylene, since Mo (molybdenum)-Bi (bismuth) oxide catalysts have been proposed, catalysts to which metals having various oxidation states are added have been proposed. However, despite the diversification of the catalyst composition, research on the structure and physical properties thereof is insufficient, and there is a limit in increasing the yield of acrylonitrile.

Specifically, the sol-gel method is widely known as a method for preparing a catalyst for ammoxidation of propylene, which corresponds to a method in which a metal precursor solution and silica sol are co-precipitated, and the co-precipitation product is spray-dried and then calcined.

According to this sol-gel method, a catalyst having a secondary particle structure in which metal oxide particles and silica particles are aggregated is prepared, but the binding force of the primary particles constituting the secondary particles is weak, so that it is worn out in the fluid reactor or split into primary particles. It is easy to lose catalytic activity. Moreover, since the sites that can participate in the ammoxidation reaction of propylene are limited to the outer surface portion (i.e., the surface of secondary particles) and provide a small surface area, the amount of ammonia desorbed from the catalyst surface during the ammoxidation reaction of propylene is reduced. many.

Therefore, when using the catalyst prepared by the sol-gel method, it is necessary to continuously add (make-up) the catalyst during the ammoxidation reaction of propylene, and even if it is added, there is a limit in increasing the yield of acrylonitrile.

The present invention is to provide a catalyst for ammoxidation of propylene capable of maximizing the adsorption capacity of ammonia within an appropriate range during the ammoxidation reaction of propylene, and to prepare acrylonitrile in a higher yield using this catalyst .

Specifically, in one embodiment of the present invention, there is provided a catalyst for ammoxidation of propylene in which a metal oxide of a specific composition is supported on a silica carrier, and the amount of ammonia adsorption in the supported state is improved.

The catalyst of one embodiment may be prepared by an impregnation method in which a metal oxide having a specific composition is supported on a silica carrier. This may indicate an improved ammonia adsorption capacity compared to the catalyst prepared by the sol-gel method.

Therefore, when using the catalyst of one embodiment, acrylonitrile can be mass-produced in high yield without additional supply of catalyst during the ammoxidation process of propylene in the fluidized bed reactor.

1 schematically shows a catalyst prepared by a sol-gel method.
2 schematically shows a catalyst according to the embodiment.

Since the present invention can apply various transformations and can have various embodiments, specific embodiments will be illustrated and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Also, terms including an ordinal number such as first, second, etc. to be used below 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. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, “particle diameter Dv” means the particle diameter at the v% point of the cumulative volume distribution according to the particle diameter. That is, D50 is the particle size at the 50% point of the cumulative volume distribution according to the particle size, D90 is the particle size at the 90% point of the cumulative volume distribution according to the particle size, and D10 is the particle size at the 10% point of the cumulative volume distribution according to the particle size. is the size

In addition, "pore diameter" may mean the length of a straight line passing through the center of the pore. In addition, the silica carrier may include a plurality of pores, and in this case, the average diameter may be obtained by arithmetic average of the diameters of the plurality of pores.

Meanwhile, in the initial stage of the catalytic reaction, a process in which reactants are chemically adsorbed on the catalyst surface is required, and the active point and surface area of the catalyst are directly related to the adsorption capacity and the resulting chemical reaction. Also, chemisorption on the catalyst surface tends to increase with increasing temperature, although the rate of adsorption is slower than that of physisorption.

In this regard, ammonia temperature elevated desorption (NH ₃ -TPD), which measures the degree of acid site strength of the catalyst by the degree of desorption (TPD: Temperature Programmed Desorption) of ammonia (NH ₃ ) is widely known. In the present invention, the ammonia (NH ₃ ) adsorption amount of the catalyst and the carrier can be measured using the ammonia temperature elevation desorption method (NH ₃ -TPD).

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

Catalyst for ammoxidation of propylene

In one embodiment of the present invention, the metal oxide represented by the following formula (1) is supported on a silica carrier, and the ammonia adsorption amount measured by ammonia elevated temperature desorption method (NH ₃ -TPD) is 0.43 mmol/g to 5 mmol/g, A catalyst for the ammoxidation of propylene is provided.

[Formula 1] Mo ₁₂ Bi _a Fe _b A _c B _d C _e D _f O _x

In Formula 1, A is at least one of Ni, Mn, and Co; B is one or more of Zn, Mg, Ca, and Ba; C is one or more of Li, Na, K, Rb, and Cs; D is one or more of Cr, W, B, Al, Ca, and V; Wherein a to f and x are each a fraction of an atom or group, a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 10, e is 0.01 to 2, , f is 0 to 10, and x is 24 to 48.

A commonly known catalyst for ammoxidation of propylene is prepared by a sol-gel method and provided in a secondary particle structure in which metal oxide nanoparticles and silica nanoparticles are aggregated ( FIG. 1 ).

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

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

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

Thereafter, when the solvent (ie, water) is removed through the drying process, the metal precursor remains on the pore wall of the silica carrier, and as the metal precursor is oxidized in the firing process, a film continuously coating the pore wall of the silica carrier can be formed. have.

The catalyst of one embodiment prepared as described above may have less fine powder content and superior durability than a catalyst prepared with the same composition by the sol-gel method, even if a classification process is not performed as a post-processing after preparation.

In addition, the catalyst of one embodiment is a catalyst by controlling the metal oxide composition to further include a metal that forms an active site at a suitable level for the ammoxidation reaction of propylene, as well as Mo and Bi, which are known to increase the activity of the ammoxidation reaction. activity can be further increased.

In particular, in the catalyst of one embodiment, the site that can participate in the ammoxidation reaction of propylene by evenly supporting the metal oxide in the internal pores of the silica carrier is not only the external surface part (ie, the surface of the catalyst) but also its internal surface (pores) ) has the advantage of being extended to

Accordingly, the catalyst of one embodiment has a site capable of adsorbing ammonia gas and propylene gas in comparison to a catalyst prepared by a sol-gel method in a supported state in which the metal oxide is supported on the silica carrier. can be many

Specifically, the catalyst of one embodiment has an adsorption amount of ammonia of 0.43 to 5 mmol/g measured by an ammonia-temperature elevated desorption method (NH ₃ -TPD).

As such, the catalyst having improved ammonia adsorption capacity may contribute to increasing the conversion rate of propylene during ammoxidation of propylene and ultimately improving the yield of acrylonitrile.

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

Ammonia Adsorption Amount of Catalyst

In the initial stage of the catalytic reaction, a process in which reactants are chemically adsorbed on the catalyst surface is required, and the active site and surface area of the catalyst are directly related to the adsorption capacity and the resulting chemical reaction.

Also, chemisorption on the catalyst surface tends to increase with increasing temperature, although the rate of adsorption is slower than that of physisorption.

In this regard, ammonia temperature elevated desorption (NH ₃ -TPD), which measures the degree of acid site strength of the catalyst by the degree of desorption (TPD: Temperature Programmed Desorption) of ammonia (NH ₃ ) is widely known.

For example, after pretreatment at 400 ° C. for about 1 hour, NH ₃ is adsorbed at about 100 ° C. with 10% NH ₃ /He (50 cc/min) for 1 hour, and physical adsorption while flowing He at the same temperature Remove the NH ₃ , and measure the desorbed NH ₃ while raising the temperature to 800 ° C. (b).

Thereafter, by obtaining the difference between the initial adsorption amount (a) and the desorption amount (b) of NH ₃ , the adsorption amount of NH ₃ remaining on the catalyst surface can be obtained.

The catalyst of one embodiment may have an adsorption amount of ammonia measured by the above method of 0.05 mmol/g or more. As such, the catalyst having excellent ammonia adsorption capacity contributes to increasing the conversion rate of propylene and the selectivity of acrylonitrile during ammoxidation of propylene, and ultimately improving the yield of acrylonitrile.

For example, in the catalyst of one embodiment, the adsorption amount of ammonia is 0.43 mmol/g or more, 0.44 mmol/g or more, or 0.45 mmol/g or more, and 5 mmol/g or less, 4 mmol/g or less, 3 mmol/g or less, It may be 2 mmol/g or less, or 1 mmol/g or less.

Pore Diameter and BET Specific Surface Area of Catalyst

The catalyst of one embodiment may have a BET specific surface area of 100 m ² /g or more while including pores having a diameter of 4 nm or more in a state in which a metal oxide of a specific composition is supported on a silica carrier. As a result, compared to the catalyst prepared by the sol-gel method, a site capable of adsorbing ammonia gas and propylene gas may be significantly increased.

As described above, in the catalyst prepared by the sol-gel method, the site capable of participating in the ammoxidation reaction of propylene is limited to the outer surface portion (ie, the surface of secondary particles), whereas the catalyst of one embodiment is the ammoxidation of propylene. The surface area that can participate in the reaction extends not only to the outer surface portion (ie, the surface of the catalyst), but also to its inner surface (pores).

For example, the catalyst of one embodiment has a diameter of 4 nm or more, 4.1 nm or more, 4.2 nm or more, 4.3 nm or more, 4.4 nm or more, or 4.5 nm or more, and 40 nm or less, 35 nm or less, 30 nm or less, 25 It may include pores of less than or equal to 20 nm, or less than or equal to 16 nm.

In addition, the catalyst of one embodiment has a BET specific surface area of 100 m ² /g or more, 102 m ² /g or more, 104 m ² /g or more, 106 m ² /g or more, 108 m ² /g or more, or 110 m ² /g or more, 300 m ² /g or less, 290 m ² /g or less, 280 m ² /g or less, or 270 m ² /g or less.

Composition of metal oxides

On the other hand, even if it has the same structure as the catalyst of the one embodiment, if the types and contents of the components constituting the metal oxide do not satisfy Formula 1 above, the active point of the catalyst insufficient or too dense for ammoxidation of propylene is formed can be

Accordingly, the type and content constituting the metal oxide needs to satisfy Chemical Formula 1 above.

In particular, when the metal oxide is represented by the following Chemical Formula 1-1, the effect of increasing the conversion rate by increasing the movement speed of lattice oxygen of molybdenum of Fe, partial oxidation reaction characteristics of propylene due to the formation of a complex oxide of Ni and Zn with molybdenum With the synergistic effect of increasing the AN selectivity by dispersing the active sites of the complex oxide containing molybdenum of K and increasing the AN selectivity, the activity in the ammoxidation reaction of propylene can be higher:

[Formula 1-1]

Mo ₁₂ Bi _a Fe _b Ni _c Zn _d K _e O _x

In Formula 1-1, a to e, and x are each an atom or fraction of an atomic group, a is 0.1 to 5, specifically 0.1 to 2.0, b is 0.1 to 5, specifically 0.5 to 3.0, c is 0.01 to 10, specifically 1 to 10, d is 0.01 to 10, specifically 1 to 10, e is 0.01 to 2, specifically 0.01 to 1.0, and x is 24-48, specifically It may be 28 to 45 days.

Metal oxide: weight ratio of carrier

The catalyst of one embodiment may include the metal oxide and the silica carrier in a weight ratio of 15:85 to 35:65, specifically 20:80 to 35:65 (metal oxide:silica carrier).

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

silica carrier

The pore diameter of the silica carrier may be one having pores having a diameter of 4 to 40 nm.

Specifically, the diameter is 4 nm or more, 4.2 nm or more, 4.4 nm or more, 4.6 nm or more, 4.8 nm or more, or 5 nm or more, and 40 nm or less, 35 nm or less, 30 nm or less, 25 nm or less, or 20 or less When a silica carrier including pores is used, a catalyst exhibiting the above-described pore characteristics and ammonia adsorption amount can be implemented.

The D50 particle diameter of the silica carrier may be in the range of 50 to 150 μm. Specifically, the silica carrier has a lower limit of 50 μm or more, 51 μm or more, 53 μm or more, or 55 μm or more of the D50 particle size, and an upper limit of 150 μm or less, 130 μm or less, 110 μm or less, or 90 μm or less. can do.

catalyst structure

The catalyst of one embodiment may include a silica carrier including a second pore; an inner coating layer continuously coating the wall surfaces of the second pores and including the metal oxide represented by Chemical Formula 1; and a first pore located inside the second pore and occupying an empty space excluding the inner coating layer.

Here, the diameter of the second pores may be 4 to 40 nm, and the first pores may be determined according to the amount of the metal oxide supported in the second pores.

In view of such a supported structure, as compared to a catalyst prepared by a sol-gel method, it may be a catalyst having a small content of fine powder, excellent durability, and high activity.

Accordingly, when using the catalyst of one embodiment, acrylonitrile can be obtained in high yield without additional supply of catalyst during the ammoxidation process of propylene in the fluidized bed reactor.

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

For this purpose, as the silica carrier, a non-porous core portion; and a porous shell portion located on the surface of the non-porous core and including second pores having a diameter of 2 to 30 nm.

Specifically, the porous shell includes a concave portion and a convex portion of the surface, and the concave portion is formed by opening the second pores to the surface of the porous shell. it could be

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

In the catalyst of one embodiment, the lower limit of the D50 particle size is 30 µm or more, 35 µm or more, 40 µm or more, or 45 µm or more, and the upper limit is 200 µm or less, 190 µm or less, 180 µm or less, 170 µm or less, 160 It can be made into micrometer or less, or 150 micrometers or less.

Method for preparing a catalyst for ammoxidation of propylene

In another embodiment of the present invention, there is provided a method for preparing the catalyst of the embodiment described above using an impregnation method.

As briefly described above, the catalyst of one embodiment may be prepared through a series of processes of supporting a metal precursor solution on the silica carrier using an impregnation method, drying and calcining.

More specifically, as a method for preparing the catalyst of the embodiment,

preparing a first precursor solution comprising a Mo precursor;

preparing a second precursor solution comprising a Fe precursor and an A precursor (A=at least one element of Ni, Mn, and Co);

A third precursor solution comprising a Bi precursor, a B precursor (B=one or more of Zn, Mg, Ca, and Ba), and a C precursor (C=one or more of Li, Na, K, Rb, and Cs) manufacturing steps,

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

calcining the dried material;

A process for preparing a catalyst for the ammoxidation of propylene is provided:

[Formula 1]

Mo ₁₂ Bi _a Fe _b A _c B _d C _e D _f O _x

In Formula 1, A is at least one of Ni, Mn, and Co; B is one or more of Zn, Mg, Ca, and Ba; C is one or more of Li, Na, K, Rb, and Cs; D is one or more of Cr, W, B, Al, Ca, and V; Wherein a to f and x are each a fraction of an atom or group, a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 10, e is 0.01 to 2, , f is 0 to 10, and x is 24 to 48.

Hereinafter, a description overlapping with the above will be omitted, and the catalyst preparation process of the embodiment will be described in detail.

Process for preparing the first precursor solution

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

The temperature range is sufficient as long as the temperature is sufficient to dissolve the Mo precursor.

In addition, in the step of preparing the first precursor solution, at least one of a water-soluble chelating agent including citric acid, oxalic acid, tartaric acid, hydrogen peroxide, or a combination thereof may be added.

The additive functions as a strength control agent in the catalyst manufacturing process by the sol-gel method, but in one embodiment, it 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 1:10, specifically 1:0.2 to 1:4, and the solubility of the molybdenum precursor increases within this range. can, but is not limited thereto.

Manufacturing process of the second precursor solution

The preparing of the second precursor solution may be a step of dissolving the Fe precursor and the A precursor (A = at least one element of Ni, Mn, and Co) in water at 20 to 50 °C. Optionally, a precursor further comprising a D precursor (D=one or more of Cr, W, B, Al, Ca, and V) may be further dissolved.

Here, the type and blending amount of the Fe precursor, the A precursor, and the D precursor may be selected 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 Ni precursor may be prepared in consideration of the metal oxide composition satisfying Chemical Formula 1-1.

Manufacturing process of third precursor solution

In the step of preparing the third precursor solution, in nitric acid at room temperature, a Bi precursor, a B precursor (B=at least one element of Zn, Mg, Ca, and Ba), and a C precursor (C=Li, Na, K, dissolving one or more of Rb, and Cs).

Here, the type and blending amount of the Bi precursor, the B precursor, and the C precursor may be selected in consideration of the composition of the metal oxide in the final catalyst.

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

Processes of preparing the first to third precursor solutions are each independent, and the manufacturing order is not limited.

Supporting process of the first to third precursor solution mixture in a carrier

When mixing the first to third precursor solutions, 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.

Thereafter, a mixture of the first to third precursor solutions may be supported on a silica carrier. This includes mixing a mixture of the first to third precursor solutions and a mixture of the silica carrier at 20 to 30° C. for 1 to 3 hours, and mixing the mixture at 20 to 30° C., 70 to 90 It may include the step of further mixing at ℃ for 1 to 3 hours.

In such a supporting process, when a silica carrier including pores having a diameter of 4 to 40 nm is used, the mixture of the first to third precursor solutions may be continuously distributed on the pore wall of the silica carrier.

Drying process of the carrier on which the mixture of the first and second precursor solutions is supported

The drying of the silica carrier on which the mixture of the first to third precursor solutions is supported may be dried in an oven at atmospheric pressure or vacuum dried sequentially up to about 10 mbar using a rotary evaporator. .

Whichever method is used, the solvent (ie, water) is removed while the mixture of the first to third precursor solutions is continuously distributed on the pore wall surface of the silica carrier, and only the first to third precursors remain. can

Final firing process

Thereafter, the calcining of the dried material may be performed at 500 to 700° C. for 2 to 8 hours.

Specifically, the first to third precursors may be oxidized in a state in which they are continuously distributed on the wall surface of the pores of the silica carrier, and may be converted into the metal oxide of Chemical Formula 1 (more specifically, Chemical Formula 1-1).

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

Method for ammoxidation of propylene

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

The catalyst of one embodiment has high activity and high temperature stability, and may be used for ammoxidation of propylene to increase propylene conversion, acrylonitrile selectivity, and yield.

For matters other than the catalyst of the embodiment, reference may be made to matters generally known in the art, and further 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 content of the present invention is not limited by the following examples.

Example 1

(1) Preparation process of precursor solution

30 g of Mo precursor (Ammonium Molybdate) was dissolved in 205 g of water at 80 ° C., and 4.54 g of citric acid was added thereto to prepare a Mo precursor solution.

Independently, by dissolving 4.04 g of Fe precursor (Iron nitrate) and 2.1 g of Ni precursor (Nickel nitrate) in 40 g of water at room temperature, a mixed solution of Fe and Ni precursor was prepared.

In addition, independently mixed with 10 g of water, 3.47 g of Bi precursor (Bismuth nitrate), 0.637 g of Zn precursor (Zinc nitrate), 0.433 g of K precursor (Potassium nitrate), and 15 g of nitric acid, Bi, Zn, And a K precursor mixed solution was prepared.

The Fe and Ni precursor mixed solution; and the Bi, Zn, and K precursor mixed solutions were each dropwise dropped into the Mo precursor solution to obtain a Mo, Bi, Fe, Ni, Zn, and K precursor mixed solution.

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

Silica (SiO ₂ ) particles having a particle diameter of 60 μm, an average pore diameter of 5.5 nm, a pore volume of 1.2 cm ³ /g according to nitrogen adsorption method, and a BET specific surface area of 688 m ² /g are used as a carrier did

The silica carrier was added to the Mo, Bi, Fe, Ni, Zn, and K precursor mixed solution, and stirred at room temperature and 80 ° C. for 2 hours, respectively, in the internal pores of the silica carrier, the Mo, Bi, The Fe, Ni, Zn, and K precursor mixed solution was sufficiently supported.

(3) Manufacturing process of a catalyst in which a metal oxide is supported in a silica carrier

Thereafter, the silica carrier on which the Mo, Bi, Fe, Ni, Zn, and K precursor mixed solution was supported was recovered, dried in an oven at 110 ° C. for 12 hours, and maintained at a temperature of 580 ° C. in a nitrogen atmosphere tubular kiln. After heat treatment for 6 hours, the catalyst of Example 1 was obtained.

(4) Ammoxidation process of propylene

In order to activate the catalyst, 0.2 g of the catalyst of Example 1 was filled in the reactor in which 0.05 g of quartz wool was filled.

As such, the internal pressure of the reactor filled with the quartz fiber and the catalyst was maintained at normal pressure (1 atm), and while the internal temperature of the reactor was increased at a temperature increase rate of 5 ° C./min, nitrogen and ammonia gas were flowed as a pretreatment process. Accordingly, the internal temperature of the reactor was made to reach 400° C., which is the temperature at which the ammoxidation reaction is possible, so that sufficient pretreatment was performed.

In this way, air was supplied along with propylene and ammonia as reactants to the reactor in which the pretreatment was completed, and the ammoxidation process of propylene was performed. At this time, the feed amount of the reactant is configured so that the volume ratio of propylene: ammonia: air = 1: 1.0 to 2.0: 1.0 to 4.0, and the total weight hourly space velocity (WHSV) of propylene, ammonia, and air is 1 h It was made to become ^-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 to be described later.

Example 2

A catalyst of Example 2 was prepared in the same manner as in Example 1, except that the amount of Fe precursor and Ni precursor among the precursors was changed.

Specifically, 5.7 g of an Fe precursor (Iron nitrate) and 8.3 g of a Ni precursor (Nickel nitrate) were used.

In addition, after performing the ammoxidation process of propylene by using the catalyst of 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.

Example 3

A catalyst of Example 3 was prepared in the same manner as in Example 1, except that the amount of Bi precursor, Fe precursor, and Ni precursor among the precursors was changed.

Specifically, 5.2 g of a Bi precursor (Bismuth nitrate), 7.5 g of an Fe precursor (Iron nitrate), and 10.4 g of a Ni precursor (Nickel nitrate) were used.

In addition, the ammoxidation process of propylene by using the catalyst of Example 3 instead of the catalyst of Example 1 was performed, the product was recovered, and analysis was performed in the same manner as in Example 1.

Example 4

A catalyst of Example 4 was prepared in the same manner as in Example 1, except that the silica carrier was changed.

Specifically, a silica carrier having a BET specific surface area of about 500 to 510 m ² /g and an average pore diameter of about 4 to 5 nm was used.

In addition, the ammoxidation process of propylene was performed using the catalyst of Example 4 instead of the catalyst of Example 1, and the product was recovered and analyzed in the same manner as in Example 1.

Example 5

A catalyst of Example 5 was prepared in the same manner as in Example 1, except that the silica carrier was changed.

Specifically, a silica carrier having a BET specific surface area of about 350 to 400 m ² /g and an average pore diameter of about 12 to 14 nm was used.

In addition, the ammoxidation process of propylene was performed using the catalyst of Example 5 instead of the catalyst of Example 1, and the product was recovered and analyzed in the same manner as in Example 1.

Example 6

A catalyst of Example 6 was prepared in the same manner as in Example 1, except that the amount of Bi precursor, Fe precursor, Ni precursor, Zn precursor, and K precursor among the precursors was changed.

Specifically, 6.9 g of Bi precursor (Bismuth nitrate), 8.6 g of Fe precursor (Iron nitrate), 6.2 g of Ni precursor (Nickel nitrate), 1.3 g of Zn precursor (Zinc nitrate), and 0.722 g of K precursor (Potassium nitrate) were used. did

In addition, after performing the ammoxidation process of propylene by using the catalyst of Example 6 instead of the catalyst of Example 1, the product was recovered and analyzed in the same manner as in Example 1.

Example 7

A catalyst of Example 7 was prepared in the same manner as in Example 1, except that the amount of Bi precursor among the precursors was changed.

Specifically, a catalyst of Example 7 was prepared in the same manner as in Example 1, except that 10.394 g of Bi precursor (Bismuth nitrate) was used.

In addition, after performing the ammoxidation process of propylene by using the catalyst of Example 7 instead of the catalyst of Example 1, the product was recovered and analyzed in the same manner as in Example 1.

Comparative Example 1

(1) Catalyst manufacturing process (sol-gel method)

First, 16 g of Mo precursor (Ammonium Molybdate) and 1.1 g of Oxalic acid were added to 10 g of distilled water and heated to about 50° C. to prepare a Mo precursor solution.

Independently, in 5 g of water at room temperature, Bi precursor (Bismuth nitrate) 1.73 g, Fe precursor (Iron nitrate) 2.01 g, Ni precursor (Nickel nitrate) 0.6533 g, Zn precursor (Zinc nitrate) 0.3159 g, K precursor ( Potassium nitrate) 0.2148 g was dissolved to prepare a mixed solution of Bi, Fe, Ni, Zn, and K precursors.

the Mo precursor solution; and the Bi, Fe, Ni, Zn, and K precursor mixture solution was mixed with stirring, and then 42.4 g of silica sol (LUDOX AS 40, content: 40 %, Grace) was added thereto and stirred, followed by a rotating disk type. Spray drying was performed at 120 °C (inlet) and 230 °C (outlet) conditions using a spray dryer (device name: BUCHI mini spray dryer).

The powder thus obtained was calcined at 580° C. for 3 hours to finally obtain the catalyst of Comparative Example 1.

(3) Ammoxidation process of propylene

The catalyst of Comparative Example 1 was used instead of the catalyst of Example 1, and the ammoxidation process of propylene 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

Silica sol (LUDOX AS 40, solid content: 40 %, Grace) 34 g, Bi precursor (Bismuth nitrate) 2.1 g, Fe precursor (Iron nitrate) 3.7 g, Zn precursor (Zinc nitrate) 0.63 g, K precursor (Potassium nitrate) ) A catalyst of Comparative Example 2 was prepared in the same manner as in Comparative Example 1, except that 0.36 g was used.

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

Comparative Example 3

In 5 g of water at room temperature, Bi precursor (Bismuth nitrate) 1.15 g, Ce precursor (Cerium nitrate) 0.25 g, Fe precursor (Iron nitrate) 4.5 g, Ni precursor (Nickel nitrate) 8.78 g, Mg precursor (Magnesium nitrate) 4.91 g, 0.14 g of Rb precursor (Rubidium nitrate) was added to prepare a mixed solution of Bi, Ce, Fe, Ni, Mg, and Rb precursor.

the Mo precursor solution; and the Bi, Ce, Fe, Ni, Mg and Rb precursor mixture solution was mixed with stirring, and then 42.4 g of silica sol (LUDOX AS 40, content: 40 %, Grace) was added thereto and stirred, followed by a rotating disk. Spray drying was performed at 120 °C (inlet) and 230 °C (outlet) conditions using a type spray dryer (device name: BUCHI mini spray dryer).

The powder thus obtained was calcined at 580° C. for 3 hours to finally obtain the catalyst of Comparative Example 3.

In addition, after performing the ammoxidation process of propylene by using the catalyst of Comparative Example 3 instead of the catalyst of Comparative Example 1, the product was recovered and analyzed in the same manner as in Comparative Example 1.

Comparative Example 4

First, 15 g of Mo precursor (Ammonium Molybdate) and 2.7 g of Oxalic acid were added to 20 g of distilled water and heated to about 50 °C, thereby preparing a Mo precursor solution.

Independently, in 10 g of water at room temperature, Bi precursor (Bismuth nitrate) 2.43 g, Fe precursor (Iron nitrate) 3.73 g, Ni precursor (Nickel nitrate) 7.2 g, Zn precursor (Zinc nitrate) 2.1 g, Mn precursor ( Dissolve 0.89 g of Manganese nitrate), 0.61 g of La precursor (Lanthanum nitrate), 0.06 g of Pr precursor (Praseodymium nitrate), 0.29 g of K precursor (Potassium nitrate) and 0.14 g of Cs precursor (Cesium nitrate). , Zn, and K precursor mixed solutions were prepared.

the Mo precursor solution; and the Bi, Fe, Ni, Zn, Mn, La, Pr, K and Cs precursor mixture solution was mixed with stirring, and then 42 g of silica sol (LUDOX AS 40, content: 40 %, Grace) was added thereto. After stirring, spray drying was performed at 120 °C (inlet) and 230 °C (outlet) conditions using a rotary disk-type spray dryer (device name: BUCHI mini spray dryer).

The powder thus obtained was calcined at 580° C. for 3 hours to finally obtain the catalyst of Comparative Example 4.

In addition, after performing the ammoxidation process of propylene by using the catalyst of Comparative Example 4 instead of the catalyst of Comparative Example 1, the product was recovered and analyzed in the same manner as in Comparative Example 1.

Comparative Example 5

Comparative Example 5 except that silica sol (LUDOX AS 40, solid content: 40%, Grace) 71 g, Mo precursor 9 g, Bi precursor (Bismuth nitrate) 49 g was used, and the rest was the same as Comparative Example 1 of the catalyst was prepared.

In addition, after performing the ammoxidation process of propylene by using the catalyst of Comparative Example 5 instead of the catalyst of Comparative Example 1, the product was recovered and analyzed in the same manner as in Comparative Example 1.

Experimental Example 1: Catalyst Analysis

Each catalyst of Examples and Comparative Examples was analyzed according to the following analysis method, and the analysis results are shown in Table 1 below. For reference, each metal oxide composition of Examples and Comparative Examples and the mixing ratio with the carrier are also shown in Table 1 below:

BET specific surface area : BET specific surface area for each catalyst of Examples and Comparative Examples was measured using a BET specific surface area measuring instrument (manufacturer: BEL Japan, instrument name: BELSORP_Mini).

Specifically, in the device, the adsorption amount up to the relative pressure (P/P0) 1 was measured under the liquid nitrogen temperature (77K), and the desorption amount up to the relative pressure (P/P0) 0.03 was also measured. These measurements were applied to the BJH equation to determine the pore volume, diameter, and surface area of the catalyst.

Ammonia adsorption amount : Ammonia adsorption amount for each catalyst of Examples and Comparative Examples was measured using a device capable of measurement by ammonia temperature elevation desorption method (NH ₃ -TPD) (manufacturer: Micromeritics, device name: Autochem Ⅱ 2920). .

Specifically, the U-shaped quartz tube in the device is filled with about 0.1 g of catalyst, the U-shaped reactor is connected to the device, and then the temperature is raised from room temperature at a temperature increase rate of 10° C./min using helium gas (50 cc/min). After raising the temperature to about 400 °C, the pretreatment was carried out while maintaining the temperature at 400 °C for about 1 hour. This is to remove organic matter remaining in the catalyst.

After the pretreatment is finished, NH ₃ is adsorbed (a) for 1 hour at about 100 ℃ with 10% NH ₃ /He (50 cc/min). While flowing He at the same temperature, the physically adsorbed NH ₃ was removed, and the temperature was raised to 800° C. to measure the desorbed NH ₃ (b).

Thereafter, by obtaining the difference between the initial adsorption amount (a) and the desorption amount (b) of NH ₃ , the adsorption amount of NH ₃ remaining on the catalyst surface could be obtained.

quite Catalyst Analysis Results metal oxide composition and
Mixing ratio with carrier pore
diameter
(nm) BET
specific surface area
(m ² /g) Ammonia adsorption
(mmol/g) Example 1 impregnation Mo ₁₂ Bi _0.5 Fe _0.7 Ni _0.5 Zn _0.15 K _0.3 O _y : 25wt%,
SiO ₂ : 75wt% 6.4 269.91 0.66 Example 2 impregnation Mo ₁₂ Bi _0.5 Fe _1.0 Ni _2.0 Zn _0.15 K _0.3 O _y : 25wt%,
SiO ₂ : 75wt% 7.3 239.55 0.61 Example 3 impregnation Mo ₁₂ Bi _0.75 Fe _1.3 Ni _2.5 Zn _0.3 K _0.5 O _y : 25wt%,
SiO ₂ : 75wt% 7.7 221.5 0.60 Example 4 impregnation Mo ₁₂ Bi _0.5 Fe _0.7 Ni _0.5 Zn _0.15 K _0.3 O _y : 25wt%,
SiO ₂ : 75wt% 5.1 203.8 0.50 Example 5 impregnation Mo ₁₂ Bi _0.5 Fe _0.7 Ni _0.5 Zn _0.15 K _0.3 O _y : 25wt%,
SiO ₂ : 75wt% 15.0 115.3 0.49 Example 6 impregnation Mo ₁₂ Bi ₁ Fe _1.5 Ni _1.5 Zn _0.3 K _0.5 O _y : 25wt%,
SiO ₂ : 75wt% 6.4 265.1 0.64 Example 7 impregnation Mo ₁₂ Bi _1.5 Fe _1.5 Ni _1.5 Zn _0.3 K _0.5 O _y : 25wt%,
SiO ₂ : 75wt% 6.3 267.8 0.64 Comparative Example 1 sol-gel method Mo ₁₂ Bi _0.5 Fe _0.7 Ni _0.5 Zn _0.15 K _0.3 O _y : 50wt%,
SiO ₂ : 50wt% 13.6 35.8 0.14 Comparative Example 2 sol-gel method Mo ₁₂ Bi _0.6 Fe _1.3 Ni _0.5 Zn _0.3 K _0.5 O _y : 25wt%,
SiO ₂ : 75wt% 13.8 34.6 0.14 Comparative Example 3 sol-gel method Mo _12.4 Bi _0.32 Ce _0.08 Fe _1.52 Ni _6.51 Mg _2.62 Rb _0.13 : 25wt%,
SiO ₂ : 75wt% 7.2 168 0.42 Comparative Example 4 sol-gel method Mo ₁₂ Bi _0.7 Fe _1.3 Ni _5.5 Zn ₁ Mn _0.5 La _0.2 Pr _0.02 K _0.4 Cs _0.1O x: 30wt%;
SiO ₂ : 70wt% 12.8 39.6 0.16 Comparative Example 5 sol-gel method Bi ₂ O ₃ MoO ₃ : 30wt%,
SiO ₂ : 70wt% 6.5 275 0.28

Experimental Example 2: Analysis of ammoxidation products of propylene

Each ammoxidation product of Examples and Comparative Examples was analyzed using chromatography (Gas chromatography, manufacturer: Agilent machine name: HP 6890 N) equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD).

Specifically, products such as ethylene (ehthlene), hydrogen cyanide, acetaldehyde, acetonitrile, acroleing, and acrylonitrile were analyzed by FID, and TCD was analyzed. By analyzing gas products such as NH ₃ , O ₂ , CO and CO ₂ and unreacted propylene, the number of moles of propylene reacted in Examples and Comparative Examples and the number of moles of ammoxidation products were obtained.

By substituting the number of moles of propylene supplied along with the analysis result according to the following 1, 2, and 3, the conversion rate of propylene, the selectivity and yield of acrylonitrile, which is an ammoxidation product of propylene, are calculated, and the calculated values are Table 2 shows.

[Equation 1]

Conversion of propylene (%)

=100*(number of moles of ammoxidation of reacted propylene)/(number of moles of supplied propylene)

[Equation 2]

Selectivity of acrylonitrile (%)

=100*(number of moles of acrylonitrile produced)/(number of moles of reacted propylene)

[Equation 3]

Yield of acrylonitrile (%)

=100*(number of moles of acrylonitrile produced)/(number of moles of propylene supplied)

Ammoxidation products of propylene Propylene conversion (%) transference number (%) Selectivity (%) Acrylonitrile CO+CO ₂ Acrylonitrile CO+CO ₂ Example 1 76.6 57.9 7.6 75.5 9.9 Example 2 81.8 60.7 7.7 74.3 9.4 Example 3 80.7 64.0 6.5 79.2 8.1 Example 4 72.0 56.1 5.1 77.9 7.1 Example 5 77.6 55.3 11.9 71.3 15.4 Example 6 81.4 61.1 6.1 75.1 7.5 Example 7 80.6 60.5 10.1 75.0 12.5 Comparative Example 1 68.3 50.5 5.9 73.3 8.7 Comparative Example 2 64.2 48.6 3.9 75.8 6.1 Comparative Example 3 76.0 52.3 10.5 68.8 13.8 Comparative Example 4 13.5 8.0 1.6 59.5 11.5 Comparative Example 5 11.3 5.7 1.2 50.5 10.3

evaluation

In Table 2, it can be seen that the catalysts of Examples 1 to 7 have significantly higher conversion rates of propylene and higher yields of acrylonitrile compared to the catalysts of Comparative Examples 1 to 5.

Specifically, looking at Tables 1 and 2 above, the catalysts of Examples 1 to 7 prepared by the impregnation method adsorbed a large amount of ammonia compared to the catalysts of Comparative Examples 1 to 5 prepared by the sol-gel method. , it can be seen that it contributed to increasing the yield of acrylonitrile according to the ammoxidation reaction of propylene.

In particular, when comparing Example 3 and Comparative Example 2 in which the metal oxide composition and the mixing ratio of the carrier (silica) were the same in Table 1, the BET specific surface area of Example 3 was significantly larger, and more ammonia was adsorbed.

Looking at Table 2, it is confirmed that in Example 3, in which more ammonia was adsorbed, the conversion rate of propylene and the yield of acrylonitrile were improved compared to Comparative Example 2.

In addition, Comparative Example 2 and Even in Comparative Example 1 having a higher silica content while having a similar metal oxide composition, the same results as in Comparative Example 2 were obtained.

On the other hand, in the case of Comparative Examples 3 to 5, the BET specific surface area was improved compared to Comparative Example 2 by changing the metal oxide composition and/or changing the compounding ratio with the carrier (silica). However, it was prepared by the sol-gel method, and the adsorption amount of ammonia was still inferior to that of Examples 1 to 7.

According to the metal oxide, Comparative Example 5 containing only Mo and Bi as active metals; And in the case of Comparative Example 4 containing La, Pr, K, Cs, etc., it was confirmed that the conversion rate of propylene and the yield of acrylonitrile were significantly lowered compared to Examples 1 to 7 under the influence of the active metal.

In the case of Comparative Example 4 using Mg and Rb as active metals, the conversion rate of propylene was at the same level as in Examples 1 to 7, but the catalytic activity decreased due to the influence of the active metal, and the yield of acrylonitrile was significantly reduced confirmed to have been

In this regard, the metal oxide composition needs to satisfy the above-mentioned formula 1 (eg, formula 1-1), and when this metal oxide exhibits an adsorption amount of ammonia of 0.43 mmol/g or more in a state supported on a silica carrier, propylene It can be seen that it is possible to improve the conversion rate of propylene and the yield of acrylonitrile during the ammoxidation reaction of

Claims (20)

A metal oxide represented by the following formula (1) is supported on a silica carrier,
Ammonia adsorption amount measured by ammonia elevated temperature desorption method (NH ₃ -TPD) is 0.43 mmol/g to 5 mmol/g,
Catalysts for the ammoxidation of propylene:
[Formula 1]
Mo ₁₂ Bi _a Fe _b A _c B _d C _e D _f O _x
In Formula 1,
A is at least one of Ni, Mn, and Co;
B is one or more elements of Zn, Mg, Ca, and Ba;
C is one or more of Li, Na, K, Rb, and Cs,
D is one or more of Cr, W, B, Al, Ca, and V,
Wherein a to f and x are each a fraction of an atom or group, a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 10, e is 0.01 to 2, , f is 0 to 10, and x is 24 to 48.
According to claim 1,
The catalyst is
Ammonia adsorption amount measured by the ammonia elevated temperature desorption method (NH ₃ -TPD) is 0.45 mmol/g or more to 1 mmol/g,
Catalyst for the ammoxidation of propylene.
According to claim 1,
The catalyst is
BET specific surface area of 100 to 300 m ² /g,
Catalyst for the ammoxidation of propylene.
According to claim 1,
The metal oxide is
Which is represented by the following formula 1-1,
Catalysts for the ammoxidation of propylene:
[Formula 1-1]
Mo ₁₂ Bi _a Fe _b Ni _c Zn _d K _e O _x
In Formula 1-1, each definition of a to e, and x is the same as in claim 1.
According to claim 1,
The weight ratio of the metal oxide and the silica carrier will be 15:85 to 35:65,
Catalyst for the ammoxidation of propylene.
According to claim 1,
The catalyst is
a silica carrier including a second pore;
an inner coating layer continuously coating the wall surfaces of the second pores and including the metal oxide represented by Chemical Formula 1; and
A first pore located inside the second pore and occupying an empty space excluding the inner coating layer;
Catalyst for the ammoxidation of propylene.
According to claim 1,
The silica carrier,
Which comprises pores having a diameter of 4 to 40 nm,
Catalyst for the ammoxidation of propylene.
According to claim 1,
The catalyst is
Which comprises pores having a diameter of 4 to 16 nm,
Catalyst for the ammoxidation of propylene.
The method of claim 1,
The catalyst is
D50 particle size of 30 to 150 μm,
Catalyst for the ammoxidation of propylene.
preparing a first precursor solution comprising a Mo precursor;
preparing a second precursor solution comprising a Fe precursor and an A precursor (A=at least one element of Ni, Mn, and Co);
A third precursor solution comprising a Bi precursor, a B precursor (B=one or more of Zn, Mg, Ca, and Ba), and a C precursor (C=one or more of Li, Na, K, Rb, and Cs) precursors manufacturing steps,
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
calcining the dried material;
Method for preparing a catalyst for the ammoxidation of propylene:
[Formula 1]
Mo ₁₂ Bi _a Fe _b A _c B _d C _e D _f O _x
In Formula 1,
A is at least one of Ni, Mn, and Co;
B is one or more elements of Zn, Mg, Ca, and Ba;
C is one or more of Li, Na, K, Rb, and Cs,
D is one or more of Cr, W, B, Al, Ca, and V,
Wherein a to f and x are each a fraction of an atom or group, a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 10, e is 0.01 to 2, , f is 0 to 10, and x is 24-48.
11. The method of claim 10,
The first precursor solution is
Which further comprises one or more of a water-soluble chelating agent comprising citric acid, oxalic acid, tartaric acid, hydrogen peroxide, or a combination thereof,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
The first precursor solution is
To prepare an aqueous solution containing water and Mo precursor,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
The step of preparing the first precursor solution,
Which is carried out at 50 to 90 ℃,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
In the step of preparing the second precursor solution,
To prepare an aqueous solution containing water, a Fe precursor and a Ni precursor,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
The step of preparing the second precursor solution,
Which is carried out at 20 to 50 ℃,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
In the step of preparing the third precursor solution,
To prepare a solution containing nitric acid, a Bi precursor, a Zn precursor, and a K precursor,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
The step of supporting a mixture of the first to third precursor solutions on a silica carrier comprises:
mixing the mixture of the first to third precursor solutions and the mixture of the silica carrier at 20 to 30° C. for 1 to 3 hours, and
Which comprises the step of further mixing the material mixed at 20 to 30 ℃ of the mixture at 70 to 90 ℃ for 1 to 3 hours,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
Drying the silica carrier on which the mixture of the first to third precursor solutions is supported includes:
The silica carrier on which the mixture of the first to third precursor solutions is supported is dried at 90 to 130° C. for 10 to 15 hours,
A method for producing a catalyst for the ammoxidation of propylene.
11. The method of claim 10,
The step of calcining the dried material,
Which is carried out for 4 to 8 hours at 500 to 700 ℃,
A method for producing a catalyst for the ammoxidation of propylene.
In a 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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