Ammonia oxidation catalyst for propylene, method for manufacturing the catalyst, ammonia oxidation method using the catalyst

Abstract

The present disclosure relates to an ammoxidation catalyst for propylene, a method for manufacturing the ammoxidation catalyst, and an ammoxidation method of propylene using the ammoxidation catalyst. Specifically, in one embodiment of the present disclosure, a catalyst having a structure in which a metal oxide is supported on a silica carrier, having a narrow particle size distribution and excellent attrition resistance is provided.

Description

TECHNICAL FIELD

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0087104, filed July 14, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

[0003] The present disclosure relates to an ammoxidation catalyst for propylene, a method of manufacturing the catalyst, and an ammoxidation method of propylene using the catalyst. BACKGROUND

[0004] Acrylonitrile can be prepared by an ammoxidation reaction of propylene.

[0005] Specifically, the ammoxidation reaction of propylene includes a reduction reaction of ammonia and propylene and a re-oxidation reaction of oxygen, and a fluidized bed reactor is generally used to control the heat generated during these reactions.

[0006] Since molybdenum (Mo)-bismuth (Bi) oxide catalysts were proposed as ammoxidation catalysts for propylene, catalysts added with metals having different oxidation states have been proposed. However, although the compositions of the catalysts are various, research on their structures and physical properties is not sufficient, and thus, improvement in acrylonitrile yield is limited.

[0007] Specifically, a sol-gel method is widely known as a method of preparing an ammoxidation catalyst for propylene, which corresponds to a method of co-precipitating a metal precursor solution and a silica sol and spray-drying the co-precipitated product, and then calcining.

[0008] According to the sol-gel method, a catalyst in which metal oxide particles and silica particles are aggregated in a secondary particle structure is prepared. Since the particles constituting the secondary particles have weak binding force, these particles are broken or split into primary particles in a fluid reactor, and thus, easily lose their catalytic activity. Therefore, when a catalyst prepared by the sol-gel method is used, it is necessary to continuously supplement the catalyst during the ammoxidation reaction of propylene, and even if the catalyst is added, improvement in acrylonitrile yield is limited.

[0009] Also, the catalyst prepared by the sol-gel method can already contain a large amount of fine powder before being introduced into the fluid reactor. In the process of spray-drying the co-precipitated product of the metal precursor solution and the silica sol, the product cannot be aggregated into an appropriate size, and thus, fine powder can be generated. Therefore, the catalyst prepared by the sol-gel method has a problem of inherently low productivity and high manufacturing cost. SUMMARY

[0010] TECHNICAL PROBLEM

[0011] The present application provides an ammoxidation catalyst for propylene, which has a low content of fine powder and excellent durability, and by using which a higher yield of acrylonitrile can be produced.

[0012] Technical Solution

[0013] Specifically, in one embodiment of the present disclosure, a catalyst having a structure in which a metal oxide having a specific composition is supported on a silica support having a pore diameter and an apparent density each controlled within a specific range is provided.

[0014] Advantageous Effects

[0015] The catalyst of one embodiment can be prepared by an impregnation method, and can have a lower content of fine powder and excellent durability compared to a catalyst prepared by a sol-gel method.

[0016] Further, depending on the composition of the metal oxide and the pore diameter and the apparent density of the silica support, the catalyst can exhibit improved durability while having a more uniform particle size distribution.

[0017] Therefore, when the catalyst of one embodiment is used, in the ammoxidation of propylene in a fluidized bed reactor, a high yield of acrylonitrile can be produced on a large scale without additional supply of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A catalyst having a secondary particle structure prepared by using a coprecipitation method is schematically shown.

[0019] Figure 2 A catalyst according to one embodiment is schematically shown. DETAILED DESCRIPTION

[0020] Since the present application can be modified in various ways and has various embodiments, specific embodiments thereof will be shown by way of example and will be described in detail. However, it is not intended to limit the present application to the specific form disclosed, and it should be understood that the present application includes all modifications, equivalents, and substitutions within the idea and technical scope of the present application. In describing the present application, if it is determined that a detailed description of related art will obscure the gist of the present application, a detailed description thereof will be omitted.

[0021] Also, the terms used below include ordinal numbers such as first, second, etc. which can be used to describe various elements, but the elements are not limited to these terms. The above terms are used only to distinguish one component from another component. For example, a first component can be referred to as a second component, and similarly, a second component can also be referred to as a first component without departing from the scope of the present application.

[0022] The singular form "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," "including," or "has," "having," when used in this specification, specify the presence of stated features, numbers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0023] Hereinafter, "particle size Dv" means a particle size at a v% point in a cumulative volume distribution according to particle size. That is, D50 is a particle size at a 50% point in a cumulative volume distribution according to particle size, D90 is a particle size at a 90% point in a cumulative volume distribution according to particle size, and D10 is a particle size at a 10% point in a cumulative volume distribution according to particle size.

[0024] Hereinafter, "particle size Dv" means a particle size at a v% point in a cumulative volume distribution according to particle size. That is, D50 is a particle size at a 50% point in a cumulative volume distribution according to particle size, D90 is a particle size at a 90% point in a cumulative volume distribution according to particle size, and D10 is a particle size at a 10% point in a cumulative volume distribution according to particle size.

[0025] Ammonia oxidation catalyst for propylene

[0026] In one embodiment of the present disclosure, an ammoxidation catalyst for propylene is provided, including: a silica support including pores having a diameter of 2 nm to 15 nm and having an apparent density of 0.25 g / cc to 1.0 g / cc; and a metal oxide supported on the silica support and containing molybdenum (Mo), bismuth (Bi), and a hetero-metal.

[0027] The ammoxidation catalyst for propylene generally known in the art can be prepared by a sol-gel method, and is provided as a secondary particle structure in which metal oxide nanoparticles and silica nanoparticles are aggregated. Figure 1 ).

[0028] Such a structure can be a structure in which metal oxide particles are uniformly distributed inside and outside but have no internal pores, and a site capable of participating in the ammoxidation reaction of propylene can be limited to the outer surface portion.

[0029] In contrast, the catalyst of one embodiment can be prepared by an impregnation method, and thus is provided as a structure in which a metal oxide is supported on a silica support. Figure 2 ).

[0030] For example, the silica support can be immersed in an aqueous metal precursor solution prepared to have a stoichiometric molar ratio of a metal oxide required, and the aqueous metal precursor solution can be impregnated in the silica support.

[0031] Afterwards, when the solvent (i.e., water) is removed through a drying process, the metal precursor can remain on the pore walls of the silica support, and the metal precursor can be oxidized during a calcination process, thereby forming a film that continuously coats the pore walls of the silica support.

[0032] The catalyst of one embodiment prepared as described above can have a narrower particle size distribution than a catalyst prepared by a sol-gel method with the same composition, even without a classification process as a post-treatment after preparation, and can have a smaller content of fine powder.

[0033] Specifically, since the catalyst of one embodiment includes a silica support having a pore diameter and an apparent density in appropriate ranges of 2 nm to 15 nm and 0.25 g / cc to 1.0 g / cc, respectively, it is possible to improve durability while further reducing the content of fine powder.

[0034] Also, the catalyst of one embodiment can further improve catalytic activity by a metal oxide including Mo and Bi known to improve ammonia oxidation reaction activity, and a metal forming an active site for an ammonia oxidation reaction of propylene at an appropriate level.

[0035] Therefore, when the catalyst of one embodiment is used, a high yield of acrylonitrile can also be obtained in an ammonia oxidation process of propylene performed in a fluidized bed reactor without additionally supplying a catalyst.

[0036] Hereinafter, the catalyst of one embodiment will be described in more detail.

[0037] Pore size of the silica support

[0038] The pore diameter of the silica support can refer to the average size of the pores in the particle, and can also refer to the Dp value at the dVp / dDp maximum point in the dVp / dDp curve obtained by the BJH calculation formula in the nitrogen isothermal desorption curve at a liquid nitrogen temperature. In the above, Dp can refer to the pore diameter of the particle, and Vp can refer to the pore volume of the particle.

[0039] When the pore diameter of the silica support becomes too small to be less than 2 nm, impregnation of the metal oxide into the pores of the silica support cannot be uniformly performed, and thus the activity of the final catalyst can be reduced, and the resulting unimpregnated metal oxide can be dissociated to form fine powder.

[0040] On the contrary, when the pore diameter of the silica support becomes too large to be more than 15 nm, the final catalytic activity can be high, but since the pore diameter is large, the apparent density and the durability can be reduced, and thus the catalyst can be easily abraded and micronized in the fluidized bed reactor.

[0041] Therefore, even when a silica support having a pore diameter less than 2 nm, which is too small, and a silica support having a pore diameter greater than 15 nm, which is too large, is used, the catalyst must be continuously supplemented in the mass production of acrylonitrile, but there is still a limit to improving the yield of acrylonitrile even after the catalyst is supplemented.

[0042] Therefore, in one embodiment of the present disclosure, the pore diameter of the silica support can be limited to a range of 2 nm to 15 nm.

[0043] The pore diameter of the silica support can be controlled in a range of 2 nm to 30 nm depending on the physical properties required for the final catalyst.

[0044] Specifically, when the composition and the loading amount of the metal oxide are the same, as the pore diameter of the silica support on which the metal oxide is loaded decreases in a range of 2 nm to 15 nm, the amount of fine powder of the final catalyst can decrease and the particle size distribution can become uniform.

[0045] For example, the pore diameter of the silica support can be controlled in a range of 15 nm or less, 14 nm or less, 13 nm or less, or 12 nm or less while being 2 nm or more.

[0046] Apparent density of the silica support

[0047] Generally, the apparent density can refer to a value obtained by measuring the weight (W1) of a porous body contained in a container having a constant volume of 3 cc and dividing the weight by the constant volume 3 cc of the container.

[0048] When the D50 particle diameter of the silica support is the same, the apparent density tends to decrease as the pore diameter increases.

[0049] When the pore diameter of the silica support becomes large, and thus the apparent density becomes too small to be less than 0.25 g / cc, the final catalytic activity can become high, but the apparent density and the durability can become low, and thus the catalyst can be easily abraded and micronized in the fluidized bed reactor.

[0050] On the contrary, when the pore diameter of the silica support becomes small, and thus the apparent density becomes too large to be more than 1.0 g / cc, the impregnation of the metal oxide into the pores of the silica support cannot be uniformly performed, and thus the activity of the final catalyst can decrease, and the unimpregnated metal oxide resulting therefrom can be dissociated to form fine powder.

[0051] Therefore, even when a silica support having an apparent density less than 0.25 g / cc, which is too small, and a silica support having an apparent density greater than 1.0 g / cc, which is too large, is used, the catalyst must be continuously supplemented in the mass production of acrylonitrile, but there is still a limit to improving the yield of acrylonitrile even after the catalyst is supplemented.

[0052] The apparent density of the silica support can be controlled in the range of 0.25 g / cc to 1.0 g / cc according to the physical properties required for the final catalyst.

[0053] Specifically, when the composition and the loading amount of the metal oxide are the same, as the apparent density of the silica support on which the metal oxide is loaded increases in the range of 0.25 g / cc to 1.0 g / cc, the amount of fine powder of the final catalyst can be reduced.

[0054] For example, the apparent density of the silica support can be 0.25 g / cc or more, 0.27 g / cc or more, 0.29 g / cc or more, or 0.3 g / cc or more, while being 1.0 g / cc or less.

[0055] D50 particle size of the silica support

[0056] The D50 particle diameter of the silica support can be in the range of 50 μm to 150 μm.

[0057] Specifically, the lower limit of the D50 particle diameter of the silica support can be 50 μm or more, 51 μm or more, 53 μm or more, or 55 μm or more, while the upper limit of the D50 particle diameter can be 150 μm or less, 110 μm or less, 90 μm or less, or 75 μm or less.

[0058] Ammonia desorption amount of the silica support

[0059] At the initial stage of the catalytic reaction, a process in which a reactant is chemisorbed on the surface of the catalyst is required, and the active site and the surface area of the catalyst are directly related to the adsorption capacity and the chemical reaction that occurs.

[0060] In addition, as the temperature increases, the chemisorption on the surface of the catalyst tends to increase, although the adsorption rate is slower than the physical adsorption rate.

[0061] In this regard, an ammonia temperature-programmed desorption (NH3-TPD) method, which measures the strength of the acid site of the catalyst according to the temperature-programmed desorption (TPD) degree of ammonia (NH3), is well known.

[0062] For example, after pre-treatment at 400℃ for about 1 hour, NH3 can be adsorbed at about 100℃ for 1 hour with 5% NH3 / He (50 cc / min), and the physically adsorbed NH3 can be removed at the same temperature while He is flowing, after which the desorbed NH3 can be measured while the temperature is increased to 800℃.

[0063] Since the amount of desorption of ammonia (NH3) measured by the ammonia temperature programmed desorption (NH3-TPD) method is 1.3 mmol / g or less, 1.2 mmol / g or less, 1.1 mmol / g or less, or 1.00 mmol / g or less (but greater than 0 mmol / g), the silica support can have excellent adsorption capacity.

[0064] This can be a factor in reducing the amount of ammonia desorbed from the silica support and the catalyst including the silica support during the ammoxidation of propylene, increasing the propylene conversion rate, and the acrylonitrile selectivity and yield.

[0065] Composition of the metal oxide

[0066] Meanwhile, even if the catalyst has the same structure as the catalyst of one embodiment, a small amount of active sites can be formed or, conversely, active sites can be formed at excessively high density depending on the type and content of the components constituting the metal oxide.

[0067] In this regard, it is necessary to form appropriate active sites by adding a foreign metal instead of a metal oxide containing only Mo and Bi as active metals.

[0068] Specifically, in the catalyst of one embodiment, the type and content of the metals constituting the metal oxide can satisfy Chemical Formula 1:

[0069] [Chemical Formula 1]

[0070] Mo 12 Bi a Fe b A c B d C e O x

[0071] In Chemical Formula 1,

[0072] A is at least one element among Ni, Mn, Co, Zn, Mg, Ca, and Ba,

[0073] B is at least one element among Li, Na, K, Rb, and Cs,

[0074] C is at least one element among Cr, W, B, Al, Ca, and V, and

[0075] a to e and x are the proportions of atoms or atomic groups, respectively, in which a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 2, e is 0 to 10, and x is 24 to 48.

[0076] Specifically, when the metal oxide is represented by the following Chemical Formula 1-1, due to the synergistic effect of the effect of improving the conversion rate by increasing the moving rate of the lattice oxygen of Fe molybdenum, the effect of improving the propylene partial oxidation reaction performance by forming a composite oxide with Co molybdenum, and the effect of improving the AN selectivity by dispersing the active sites of the composite oxide containing K molybdenum, the activity of the ammoxidation reaction of propylene can become higher:

[0077] [Chemical Formula 1-1]

[0078] Mo 12 Bi a Fe b Co c K d O x

[0079] In Chemical Formula 1-1, a to d and x are the proportions of atoms or atomic groups, respectively, wherein 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 2, specifically 0.01 to 1.0, and x is 24 to 48, specifically 28 to 45.

[0080] Weight ratio of the metal oxide : support

[0081] The catalyst of one embodiment can include a metal oxide and a silica support in a weight ratio of 15:85 to 35:65, specifically 20:80 to 35:65 (metal oxide: silica support).

[0082] Within the above range, the catalyst of one embodiment can have high selectivity for acrylonitrile as well as high activity.

[0083] Structure of the catalyst

[0084] The catalyst of one embodiment can have the following structure, including: a silica support including a second pore; an inner coating layer continuously coating a wall surface of the second pore and containing a metal oxide represented by Chemical Formula 1; and a first pore located inside the second pore and occupying an empty space other than the inner coating layer.

[0085] Herein, the diameter of the second pore can be 2 nm to 15 nm, and the first pore can be determined according to the amount of the metal oxide loaded in the second pore.

[0086] In terms of such a loaded structure, the catalyst can have a small amount of fine powder, excellent durability, and high activity, compared to a catalyst prepared by a sol-gel method.

[0087] Therefore, when the catalyst of one embodiment is used, a high yield of acrylonitrile can be obtained in the process of the ammoxidation of propylene in a fluidized bed reactor without additional supply of the catalyst.

[0088] Specifically, the catalyst of one embodiment can have an egg-shell structure.

[0089] To this end, the silica support can include: a non-porous core portion; and a porous shell portion located on a surface of the non-porous core portion and including second pores having a diameter of 2 nm to 30 nm.

[0090] Specifically, the porous shell can include a concave portion and a convex portion of a surface, in which the concave portion is formed by opening the second pores to the surface of the porous shell.

[0091] Therefore, the catalyst of one embodiment can have a structure including: a coating layer which continuously coats the concave portion and the convex portion of the porous shell and contains the metal oxide represented by Chemical Formula 1; and first pores which occupy empty spaces in the concave portion of the silica support other than the coating layer.

[0092] D50 particle size and homogeneity of the particle size distribution of the final catalyst

[0093] The catalyst of one embodiment has a uniform particle size distribution and a less content of fine powder with respect to D50 when the metal oxide is supported on the silica support.

[0094] Specifically, since the ratio of [the difference between the D90 particle size and the D10 particle size] to the D50 particle size is 2.0 or less, the catalyst of one embodiment can have a D50 particle size of 30 μm to 200 μm and exhibit a narrow particle size distribution.

[0095] More specifically, the lower limit of the D50 particle size of the catalyst of one embodiment can be 30 μm or more, 35 μm or more, 40 μm or more, or 45 μm or more, and the upper limit of the D50 particle size can be 200 μm or less, 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, or 150 μm or less.

[0096] Further, since the ratio of [the difference between the D90 particle size and the D10 particle size] to the D50 particle size is less than 2.0, or is 1.7 or less, 1.5 or less, 1.3 or less, or 1.0 or less, the catalyst of one embodiment can exhibit a narrow particle size distribution.

[0097] In other words, the uniformity of the particle size distribution exhibited by the catalyst of one embodiment can be supported by the fact that the D10 particle diameter and the D90 particle diameter satisfy the following Equation 1-1 in comparison with the D50 particle diameter:

[0098] [Equation 1]

[0099] (D90-D10) / D50≤2.0

[0100] [Equation 1-1]

[0101] (D90-D10) / D50≤1.0

[0102] Amount of attrition loss of the catalyst

[0103] Attrition of particles can refer to a phenomenon in which solid particles are decomposed by mechanical and chemical processes. Particle attrition can be divided into two types: abrasion and chipping, both of which can occur simultaneously.

[0104] Specifically, in a fluidized bed process, catalyst particles are abraded and micronized, and thus it is necessary to continuously supplement the catalyst with the amount of attrited catalyst particles, which can affect the economic feasibility of the entire process.

[0105] ASTM 9797-00 method is known as a standard for measuring particle attrition. This method corresponds to the following method for measuring abrasion resistance (attrition loss rate) using the following equation: a vertical inner tube having an inner diameter of 35 mm and a height of 710 mm is filled with 50 g of catalyst (W0), N2 gas is flowed at 10 L / min, and the amount of catalyst collected in a fine filter (W) is measured after 5 hours.

[0106] Abrasion resistance (attrition loss rate) (%) = (W0) / W X 100

[0107] Since the abrasion resistance (attrition loss rate) measured according to the ASTM 9797-00 method is 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less, the catalyst of one embodiment can have a very small amount of loss and excellent abrasion resistance.

[0108] Accordingly, the catalyst of one embodiment exhibits excellent abrasion resistance compared to a catalyst prepared according to a sol-gel method, and can produce acrylonitrile in a higher yield during the ammoxidation reaction of propylene in a fluidized bed reactor without additional supply of the catalyst.

[0109] Method for manufacturing an ammonia oxidation catalyst for propylene

[0110] In another embodiment of the present disclosure, a method of manufacturing the catalyst of the above-described one embodiment by using an impregnation method is provided.

[0111] As briefly described above, the catalyst of one embodiment can be manufactured by a series of processes of loading a metal precursor aqueous solution on a silica support by an impregnation method, followed by drying and calcination.

[0112] More specifically, a method of manufacturing the catalyst of one embodiment is provided, including the steps of:

[0113] preparing a first precursor aqueous solution including a Mo precursor,

[0114] preparing a second precursor aqueous solution including a Bi precursor and a heterometal precursor;

[0115] loading a mixture of the first precursor aqueous solution and the second precursor aqueous solution on a silica support including pores having a diameter of 2 nm to 15 nm and having an apparent density of 0.25 g / cc to 1.0 g / cc,

[0116] drying the silica support on which the mixture of the first precursor aqueous solution and the second precursor aqueous solution is loaded, and

[0117] calcining the dried material.

[0118] Hereinafter, the description overlapping with the above will be omitted, and the manufacturing process of the catalyst of one embodiment will be described in detail.

[0119] Process for preparing the first aqueous precursor solution

[0120] In the step of preparing the first precursor aqueous solution, an additive including citric acid, oxalic acid, or a mixture thereof can be added.

[0121] These additives can function as a strength adjuster in the catalyst manufacturing process using coprecipitation and spray drying, but in one embodiment, these additives can function to make the first precursor aqueous solution transparent.

[0122] When the additive is added, the weight ratio of the Mo precursor and the additive can satisfy 1:0.1 to 1:1, specifically 1:0.2 to 1:0.7, and within this range, the solubility of the Mo precursor can increase, but is not limited thereto.

[0123] Process for preparing the second aqueous precursor solution

[0124] The second precursor aqueous solution including the remaining metal precursors other than the Mo precursor included in the first precursor aqueous solution can be prepared.

[0125] Specifically, the step of preparing the second precursor aqueous solution can be a step of preparing a second precursor aqueous solution including a Bi precursor, a Fe precursor, an A precursor (A = at least one element among Ni, Mn, Co, Zn, Mg, Ca, and Ba), and a B precursor (B = at least one element among Li, Na, K, Rb, and Cs).

[0126] More specifically, in the step of preparing the second precursor aqueous solution, the kind of the metal precursor other than the Mo precursor can be selected in consideration of the composition of the metal oxide required in the final catalyst.

[0127] For example, in consideration of the composition of the metal oxide satisfying the above Chemical Formula 1-1, a second precursor aqueous solution including a Bi precursor, a Fe precursor, a Co precursor, and a K precursor can be prepared.

[0128] Here, a second precursor aqueous solution further including a C precursor (at least one element among Cr, W, B, Al, Ca, and V) can also be prepared.

[0129] Mixture of the first and second aqueous precursor solutions

[0130] The processes of preparing the first precursor aqueous solution and the second precursor aqueous solution are independent of each other, and there is no limitation on the preparation sequence.

[0131] However, the mixture of the first precursor aqueous solution and the second precursor aqueous solution can be prepared such that the molar ratio of the metals satisfies the stoichiometric molar ratio of the following Chemical Formula 1:

[0132] [Chemical Formula 1]

[0133] Mo 12 Bi a Fe b A c B d C e O x

[0134] In Chemical Formula 1,

[0135] A is at least one element among Ni, Mn, Co, Zn, Mg, Ca, and Ba,

[0136] B is at least one element among Li, Na, K, Rb, and Cs,

[0137] C is at least one element among Cr, W, B, Al, Ca, and V, and

[0138] a to e and x are the proportions of atoms or atomic groups, respectively, in which a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 2, e is 0 to 10, and x is 24 to 48.

[0139] Process for loading the mixture of the first and second aqueous precursor solutions onto a support

[0140] The first precursor aqueous solution and the second precursor aqueous solution can be mixed and then loaded on the silica support.

[0141] Here, the silica support including the second pores described above can be added to the mixture of the first precursor aqueous solution and the second precursor aqueous solution, and thus the mixture of the first precursor aqueous solution and the second precursor aqueous solution can be loaded in the pores of the silica support.

[0142] Specifically, the size of the D50 of the silica support on which the metal oxide is not loaded above can be 20 μm to 400 μm.

[0143] Process for drying the support loaded with the mixture of the first and second aqueous precursor solutions Final calcination process

[0144] The step of drying the silica support on which the mixture of the first precursor aqueous solution and the second precursor aqueous solution is loaded above can include the steps of first vacuum drying the silica support on which the mixture of the first precursor aqueous solution and the second precursor aqueous solution is loaded above at 120 mbar to 160 mbar, and second vacuum drying the material after the first vacuum drying at 30 mbar to 50 mbar to obtain the silica support on which the mixture of the first precursor aqueous solution and the second precursor aqueous solution is loaded above.

[0145] Specifically, the first vacuum drying can be performed at 60 °C to 80 °C for 1 hour to 2 hours, and the second vacuum drying can be performed at 80 °C to 100 °C for 15 minutes to 45 minutes. Thus, the solvent (i.e., water) can be removed, and only the first precursor and the second precursor can remain on the wall surface of the pores of the silica support.

[0146] Although calcination can be immediately performed on the material on which the second vacuum drying has been completed, the material can be subjected to third drying at a standard pressure in order to effectively remove the solvent (i.e., water) remaining after the second vacuum drying.

[0147] Specifically, the third drying can be performed at 100 °C to 120 °C for 20 hours to 30 hours.

[0148] However, this is merely an example, and can not be specifically limited as long as the process is performed under a drying condition in which the solvent (i.e., water) is removed to obtain a support on which the first precursor and the second precursor are loaded above.

[0149] Method for ammonia oxidation of propylene

[0150] Finally, the dried material, i.e., the support on which the first precursor and the second precursor are loaded, can be calcined at a temperature range of 500°C to 700°C for 2 hours to 5 hours to finally obtain the catalyst.

[0151] However, the drying and calcination conditions are only examples, respectively, and it is enough as long as the solvent can be sufficiently removed from the inner pores of the support and the metal precursor can be oxidized.

[0152] Examples

[0153] In another embodiment of the present disclosure, there is provided a method of ammoxidation of propylene, comprising a step of reacting propylene and ammonia in the presence of the catalyst of one embodiment as described above in the reactor.

[0154] The catalyst of one embodiment can have high temperature stability as well as high activity, and can be used for the ammoxidation of propylene to improve the conversion of propylene and the selectivity and yield of acrylonitrile.

[0155] For matters other than the catalyst of the one embodiment, matters well known in the art can be referred to, and thus further detailed description thereof will be omitted.

[0156] Hereinafter, the embodiments of the present disclosure will be described in more detail through the following embodiments. However, the following embodiments are provided only for the purpose of illustrating the present disclosure, and thus the present disclosure is not limited thereto.

[0157] Examples 2 to 7 1

[0158] (1) Preparation process of precursor solution

[0159] 10.59 g of Mo precursor ((NH4)6Mo7O 24 ) and 5.3 g of citric acid were added to distilled water, and mixed to prepare a Mo precursor solution.

[0160] Separately, 1.82 g of Bi precursor (Bi(NO3)3·5H2O), 9.49 g of Co precursor (Co(NO3)2·6H2O), 2.99 g of Fe precursor (Fe(NO3)2·9H2O), and 0.35 g of K precursor (KNO3) were added to distilled water, and 2.29 g of nitric acid (HNO3) was added thereto and mixed to prepare a mixed solution of Bi, Fe, Co, and K precursors.

[0161] The Mo precursor solution; and the mixed solution of Bi, Fe, Co, and K precursors were mixed to complete a mixed solution of Mo, Bi, Fe, Co, and K precursors.

[0162] In the mixed solution of the precursors, the total amount of distilled water was 45.74 g.

[0163] (2) Process of loading the precursor solution in the silica support (using an impregnation method)

[0164] Silica particles (SiO2, D60-120A(N), AGC Si-Tech Co., Ltd.) having pores with an average diameter of 12 nm, an apparent density of 0.32 g / cc, and a D50 particle size of 70 μm were used as the support.

[0165] 18.30 g of the silica support was added to the mixed solution of Mo, Bi, Fe, Co, and K precursors, and was stirred at room temperature and 80°C for 2 hours each, so that the mixed solution of Mo, Bi, Fe, Ni, Co, and K precursors was sufficiently loaded in the pores of the silica support.

[0166] (3) Process of drying and calcining the silica support on which the precursor solution was loaded above

[0167] After that, the silica support on which the mixed solution of Bi, Fe, Co, and K precursors was loaded above was recovered and put into a rotary vacuum drier. Then, first vacuum drying was performed at a pressure of 140 mbar and a temperature of 70°C for 1 hour and 40 minutes, and second vacuum drying was performed at a pressure of 40 mbar and a temperature of 90°C for 30 minutes.

[0168] The material that had completed the second vacuum drying was recovered, put into an oven, and third drying was performed at a standard pressure and a temperature of 110°C for 24 hours, and heat treatment was performed in an air atmosphere box-type calcination furnace while maintaining a temperature of 580°C for 3 hours, to finally obtain the catalyst of Example 1.

[0169] (4) Process of ammoxidation of propylene

[0170] In a tubular reactor having an inner diameter of 3 / 8 inch, 0.05 g of quartz wool was filled for activation of the catalyst, and 0.2 g of the catalyst of Example 1 was filled into the reactor.

[0171] The internal pressure of the reactor filled with the quartz wool and the catalyst was maintained at a standard pressure (1 atm), and nitrogen and ammonia were flowed in while increasing the internal temperature of the reactor at a temperature increase rate of 10°C / min as a pretreatment process. Thus, after the internal temperature of the reactor reached 400°C at which the ammoxidation reaction can be performed, 15 minutes were maintained under a reducing gas atmosphere to secure sufficient pretreatment.

[0172] The air as a reactant was supplied together with propylene and ammonia into the reactor in which the pretreatment was completed, and the ammoxidation process of propylene was performed. At this time, the supply amount of the reactants was set to achieve a volume ratio of propylene:ammonia:air = 0.8:1.2:8, and the total weight hourly space velocity (WHSV) of propylene, ammonia, and air was set to 1.54 h -1 .

[0173] After the ammoxidation reaction was completed, the product recovered was analyzed using various instruments to determine whether acrylonitrile was sufficiently produced.

[0174] The analysis method, analysis results, and the like will be described in detail in the experimental examples described later.

[0175] Comparative Example 1

[0176] Each catalyst of Examples 2 to 7 was prepared in the same manner as Example 1, except that the precursor solution was prepared according to the composition shown in Table 1 below and the silica support shown in Table 2 below was used.

[0177] Further, the ammoxidation process of propylene was performed by using each catalyst of Examples 2 to 7 instead of the catalyst of Example 1, and then the product recovered was analyzed in the same manner as Example 1.

[0178] Comparative Examples 2 and 3

[0179] (1) Preparation process of catalyst (after co-precipitation, spray drying was used)

[0180] First, 10.59 g of Mo precursor ((NH4)6Mo7O 24 ) and 5.3 g of citric acid were added to distilled water, and mixed to prepare a Mo precursor solution.

[0181] Separately, 1.82 g of Bi precursor (Bi(NO3)3·5H2O), 9.49 g of Co precursor (Co(NO3)2·6H2O), 2.99 g of Fe precursor (Fe(NO3)2·9H2O), and 0.35 g of K precursor (KNO3) were added to distilled water, and 1.13 g of nitric acid (HNO3) was added thereto and mixed so as to prepare a mixed solution of Bi, Fe, Co, and K precursors.

[0182] After the Mo precursor solution; and the mixed solution of Bi, Fe, Co, and K precursors were mixed, 22.53 g of silica sol (LUDOX AS 40, solid content: 40%, Grace) was added thereto and stirred, and then spray-dried using a disc-type spray dryer at a condition of 120°C (inlet) and 230°C (outlet).

[0183] The obtained powder was calcined at 580°C for 3 hours, and a catalyst of Comparative Example 1 was finally obtained.

[0184] (3) Ammoxidation process of propylene

[0185] The ammoxidation process of propylene was performed in the same manner as in Example 1, except that the catalyst of Comparative Example 1 was used instead of the catalyst of Example 1.

[0186] After the ammoxidation reaction of Comparative Example 1 was completed, the obtained product was recovered and analyzed in the same manner as in Example 1.

[0187] Comparative Example 4

[0188] Each catalyst of Comparative Examples 2 and 3 was prepared in the same manner as in Example 1, except that a precursor solution was prepared according to the composition shown in Table 1 below and a silica support shown in Table 2 below was used.

[0189] Further, the ammoxidation process of propylene was performed by using each catalyst of Comparative Examples 2 and 3 instead of the catalyst of Example 1, and then the obtained product was recovered and analyzed in the same manner as in Example 1.

[0190] Comparative Example 5

[0191] The catalyst of Comparative Example 4 was prepared in the same manner as in Comparative Example 1, except that a precursor solution was prepared according to the composition shown in Table 1 below and a silica support shown in Table 2 below was used.

[0192] Further, the ammoxidation process of propylene was performed by using the catalyst of Comparative Example 4 instead of the catalyst of Comparative Example 1, and then the obtained product was recovered and analyzed in the same manner as in Comparative Example 1.

[0193] Experimental Example 1 : Analysis of the silica support

[0194] The catalyst of Comparative Example 5 was prepared in the same manner as in Example 1, except that a silica support shown in Table 1 below was used and a loading process was performed considering the composition of metal oxides shown in Table 2 below and the mixing ratio thereof with the silica support.

[0195] Further, the ammoxidation process of propylene was performed by using the catalyst of Comparative Example 5 instead of the catalyst of Example 1, and then the obtained product was recovered and analyzed in the same manner as in Example 1.

[0196] [Table 1]

[0197]

[0198] In Table 1 above, Mo is (NH4)6Mo7O 24 , Bi is Bi(NO3)3.5H2O, Fe is Fe(NO3)2.9H2O, Co is Co(NO3)2.6H2O, Ni is Ni(NO3)2.6H2O, and K is KNO3.

[0199] [Table 2]

[0200]

[0201] Apparent density

[0202] Each of the silica supports used in the examples and comparative examples was analyzed according to the following analysis methods and the results of the analysis thereof are shown in Table 3 below:

[0203] Average diameter of the pores : The sample was added to a 3 cm 3 (cc) container in a free-falling method, after which an amount of the sample was added or subtracted so that the surface of the sample in the container was in line with the surface of the container. Then, the weight of the sample in the container was weighed and divided by the volume of the container to obtain the apparent density of the sample.

[0204] D50 particle size : The pore diameter was measured using a BET specific surface area measuring device (manufactured by BEL Japan, device name: BELSORP_Mini), using the adsorption amount measured at a liquid nitrogen temperature (77 K) until the relative pressure (P / P0) was 1 and the desorption amount measured until 0.03, according to the BJH formula.

[0205] Ammonia (NH3) desorption amount : The Dv can be measured by using a laser diffraction method. Specifically, each of the silica supports of the examples and comparative examples was introduced into a particle size measuring device (Microtrac, Blue wave) using a laser diffraction method, and then the particle size distribution was obtained by measuring the difference in the diffraction pattern according to the particle size when the particle passed through a laser beam. In the measuring device, the D50 value was obtained by calculating the particle size at the point where the cumulative volume distribution according to the particle size reached 50%.

[0206] Experimental Example 2: Analysis of the catalyst About 0.1 g of the catalyst was filled into a U-shaped quartz tube, after which the U-shaped reactor was connected to the device, and then using helium (50 cc / min) at a temperature increase rate of 10°C / min, the temperature was increased from room temperature to about 400°C, and then maintained at 400°C for about 1 hour to perform pretreatment. This is to remove the residual organic matter in the catalyst.

[0207] After the pretreatment, NH3 was adsorbed at about 100°C for 1 hour using 5% NH3 / He (50 cc / min). Physically adsorbed NH3 was removed by flowing He at the same temperature, and desorbed NH3 was measured when the temperature was raised to 800°C.

[0208] [Table 3]

[0209]

[0210] Measurement of D10, D50 and D90

[0211] Each catalyst of the examples and comparative examples was analyzed according to the following analysis methods, and the results of the analysis thereof are shown in Table 4 below. As a reference, the content and composition of the active material (metal oxide), the apparent density and average pore diameter of the support are also shown in Table 4 below:

[0212] Experimental Example 3: Analysis of the ammonia oxidation product of propylene Dv can be measured using a laser diffraction method. Specifically, each catalyst of the examples and comparative examples was introduced into a particle size measuring device (Microtrac, Blue wave) using a laser diffraction method, and then a particle size distribution was obtained by measuring a difference in a diffraction pattern according to the particle size when a particle passes through a laser beam. In the measuring device, the particle diameter at the points where the cumulative volume distribution according to the particle diameter reaches 10%, 50%, and 90% was calculated, thereby obtaining the values of D10, D50, and D90, and a particle size distribution ((D90-D10) / D50 value) was output.

[0213] Abrasion resistance (attrition loss rate): According to ASTM9797-00 method, by filling 50 g of catalyst (W0) into a vertical inner tube having an inner diameter of 35 mm and a height of 710 mm, N2 gas was flowed at 10 L / min, and the weight (W) of the catalyst collected in a fine filter was measured after 5 hours, the abrasion resistance (attrition loss rate) was measured using the following formula.

[0214] Abrasion resistance (attrition loss rate) (%) = (W0) / W X 100

[0215] [Table 4]

[0216]

[0217] In Table 4 above, the catalysts of Examples 1 to 7 showed a narrower particle size distribution and a smaller attrition rate compared to the catalysts of Comparative Examples 1 to 5.

[0218] Specifically, the impregnation method used to prepare the catalysts of Examples 1 to 7 can be an advantageous method for forming a structure in which metal oxides are supported on a silica support so as to prepare a catalyst having a narrow particle size distribution and excellent attrition resistance, compared to the catalysts of Comparative Example 1 and Comparative Example 4 prepared by a sol-gel method.

[0219] However, the catalysts of Comparative Example 2 and Comparative Example 3 were prepared by an impregnation method, but showed a wide particle size distribution and a high attrition loss rate.

[0220] Since the catalyst of Comparative Example 2 used a silica support having a small pore diameter of 1.5 nm, a large amount of metal oxides were not impregnated into the small pores of the silica support during the support process, and contained a large amount of fine powder formed of the unimpregnated metal oxides, a wide particle size distribution and poor attrition resistance were obtained.

[0221] Meanwhile, each of the catalysts of Comparative Example 3 used a silica support having a large pore diameter of 16 nm, was easily micronized, and had a low apparent density and durability.

[0222] The catalyst of Comparative Example 5 was also prepared by an impregnation method, but showed a wide particle size distribution and a high attrition loss rate.

[0223] The catalyst of Comparative Example 5 used a silica support having a pore diameter and an apparent density within the appropriate ranges, respectively, but showed a wide particle size distribution and poor attrition resistance under the influence of metal oxides containing only Mo and Bi as active metals.

[0224] In contrast, the catalysts of Examples 1 to 7 showed a narrow particle size distribution and excellent attrition resistance due to the use of a silica support having a pore diameter and an apparent density within the appropriate ranges of 2 nm to 15 nm and 0.3 g / cc to 1.0 g / cc, respectively, and the support of metal oxides further containing Mo and Bi as well as active metal components such as Fe, Co, K, etc.

[0225] Specifically, the catalysts of Examples 1 to 7 showed a uniform particle size distribution of (D90-D10) / D50 of 2 or less, specifically 0.85 or less, and thus showed an attrition loss rate of 10% or less, specifically 5% or less, according to the ASTM 9797-00 method.

[0226] ​

[0227] Each of the ammoxidation products of the examples and comparative examples was analyzed using a chromatograph (gas chromatograph manufactured by Agilent, machine name: HP 6890 N) equipped with a flame ionization detector (FID) and a thermal conductivity detector (TCD).

[0228] Specifically, products such as ethylene, hydrogen cyanide, acetaldehyde, acetonitrile, acrylonitrile, etc. were analyzed by FID, and gaseous products such as NH3, O2, CO, CO2, and unreacted propylene were analyzed by TCD to determine the number of moles of reacted propylene and the number of moles of ammoxidation products in the examples and comparative examples, respectively.

[0229] The number of moles of supplied propylene was applied to Formulas 1, 2, and 3 below together with the analysis results to calculate the conversion of propylene and the selectivity and yield of the ammoxidation product of propylene, acrylonitrile, of propylene, and the resulting values are shown in Table 5.

[0230] For reference, the content and composition of the active material (metal oxide), the apparent density and average pore diameter of the support are also shown in Table 5 below:

[0231] [Formula 1]

[0232] Conversion of propylene (%) = 100 * (number of moles of propylene of ammoxidation reaction) / (number of moles of supplied propylene)

[0233] [Formula 2]

[0234] Selectivity of acrylonitrile (%) = 100 * (number of moles of produced acrylonitrile) / (number of moles of reacted propylene)

[0235] [Formula 3]

[0236] Yield of acrylonitrile (%) = 100 * (number of moles of produced acrylonitrile) / (number of moles of supplied propylene)

[0237] [Table 5]

[0238]

[0239] In Table 5 above, the catalysts of Examples 1 to 7 have very high conversion of propylene and very high selectivity and yield of acrylonitrile compared to the catalysts of Comparative Examples 1, 2, 4, and 5.

[0240] In consideration of the results of Table 4 above in combination, it can be understood that the preparation of a catalyst having a narrow particle size distribution and excellent attrition resistance contributes to a significant increase in the conversion of propylene, the selectivity and yield of acrylonitrile.

[0241] However, the catalyst of Comparative Example 3 was prepared by using a silica support having a large pore diameter of 16 nm, and thus has high catalytic activity. Therefore, in the reaction carried out on a laboratory scale, the conversion of propylene, the selectivity and yield of acrylonitrile can be improved, as shown in Table 4 above.

[0242] However, since the pore diameter of the silica support is large, the apparent density and durability are reduced, and thus the catalyst is easily abraded and micronized in a fluidized bed reactor. Therefore, in the mass production of acrylonitrile, the catalyst needs to be continuously supplemented, and even if the catalyst is added, there is a limit to improving the yield of acrylonitrile.

[0243] Therefore, in the mass production of acrylonitrile, with reference to the examples, it is possible to improve the catalytic stability by controlling the pore diameter, apparent density, etc. of the silica support within the range of one embodiment described above, and it is possible to adjust the conversion of propylene and the selectivity and yield of acrylonitrile to the desired range.

Claims

1. An ammoxidation catalyst for propylene, comprising: a silica support including pores having a diameter of 2 nm to 15 nm, wherein the silica support has an apparent density of 0.25 g / cc to 1.0 g / cc and a D50 particle diameter of 50 μm to 150 μm; and a metal oxide represented by the following Chemical Formula 1 and supported on the silica support, [Chemical Formula 1] Mo 12 Bi a Fe b A c B d C e O x in the Chemical Formula 1, A is at least one element among Ni, Mn, Co, Zn, Mg, Ca, and Ba, B is at least one element among Li, Na, K, Rb, and Cs, C is at least one element among Cr, W, B, Al, Ca, and V, a to e and x are the proportions of atoms or atomic groups, respectively, a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 2, e is 0 to 10, and x is 24 to 48, wherein the D10 particle diameter, the D50 particle diameter, and the D90 particle diameter of the ammoxidation catalyst satisfy the relationship of Equation 1: [Equation 1] (D90-D10) / D50 ≤ 2.0, wherein the ammoxidation catalyst comprises: a silica support including second pores; an inner coating layer that continuously coats a wall surface of the second pores and contains the metal oxide represented by the Chemical Formula 1; and first pores located inside the second pores and occupying empty spaces other than the inner coating layer.

2. The ammonia oxidation catalyst of claim 1, wherein, The silica support includes pores having a diameter of 2 nm to 13 nm.

3. The ammonia oxidation catalyst of claim 1, wherein, The silica support has an apparent density of 0.3 g / cc to 1.0 g / cc.

4. The ammonia oxidation catalyst of claim 1, wherein, The silica support has an ammonia (NH3) desorption amount of 1.3 mmol / g or less but more than 0, measured by an ammonia temperature programmed desorption (NH3-TPD) method.

5. The ammonia oxidation catalyst of claim 1, wherein, The Chemical Formula 1 is the following Chemical Formula 1-1: [Chemical Formula 1-1] Mo 12 Bi a Fe b Co c K d O x in the Chemical Formula 1-1, a to d and x each have the same definition as in claim 1.

6. The ammonia oxidation catalyst of claim 1, wherein, The weight ratio of the metal oxide to the silica support is 15:85 to 35:

65.

7. The ammonia oxidation catalyst of claim 1, wherein, The ammoxidation catalyst has a wear resistance with a wear loss rate of 10% or less according to an ASTM 9797-00 method. 8.A method of manufacturing an ammoxidation catalyst for propylene according to claim 1, comprising the steps of: preparing a first aqueous precursor solution containing a Mo precursor; preparing a second aqueous precursor solution containing a Bi precursor and a hetero-metal precursor; supporting a mixture of the first aqueous precursor solution and the second aqueous precursor solution on a silica support including pores having a diameter of 2 nm to 15 nm, wherein the silica support has an apparent density of 0.25 g / cc to 1.0 g / cc and a D50 particle diameter of 50 μm to 150 μm; drying the silica support on which the mixture of the first aqueous precursor solution and the second aqueous precursor solution is supported; and calcining the dried material.

9. The manufacturing method according to claim 8, wherein, In the preparation of the second aqueous precursor solution, the second aqueous precursor solution contains a Bi precursor, a Fe precursor, an A precursor, and a B precursor, wherein A is at least one element among Ni, Mn, Co, Zn, Mg, Ca, and Ba, and B is at least one element among Li, Na, K, Rb, and Cs.

10. The manufacturing method according to claim 8, wherein, In the preparation of the second aqueous precursor solution, the second aqueous precursor solution contains a Bi precursor, a Fe precursor, a Co precursor, and a K precursor.

11. The manufacturing method according to claim 8, wherein, In the preparation of the second aqueous precursor solution, the second aqueous precursor solution further contains a C precursor, C being at least one element among Cr, W, B, Al, Ca, and V.

12. The manufacturing method according to claim 8, wherein, The metal molar ratio of the mixture of the first aqueous precursor solution and the second aqueous precursor solution satisfies the stoichiometric molar ratio of the following Chemical Formula 1: [Chemical Formula 1] Mo 12 Bi a Fe b A c B d C e O x In the Chemical Formula 1, A is at least one element among Ni, Mn, Co, Zn, Mg, Ca, and Ba, B is at least one element among Li, Na, K, Rb, and Cs, C is at least one element among Cr, W, B, Al, Ca, and V, a to e and x are the proportions of atoms or atomic groups, respectively, a is 0.1 to 5, b is 0.1 to 5, c is 0.01 to 10, d is 0.01 to 2, e is 0 to 10, and x is 24 to 48.

13. The manufacturing method of claim 8, wherein, The drying of the silica support on which the mixture of the first aqueous precursor solution and the second aqueous precursor solution is loaded includes the steps of: first vacuum drying of the silica support on which the mixture of the first aqueous precursor solution and the second aqueous precursor solution is loaded at 120 mbar to 160 mbar, and second vacuum drying of the material after the first vacuum drying at 30 mbar to 50 mbar.

14. The manufacturing method according to claim 13, further comprising the step of third drying of the material after the second vacuum drying at an atmospheric pressure.

15. The manufacturing method of claim 8, wherein, The calcination of the dried material is performed at 500°C to 700°C.

16. An ammoxidation method of propylene, comprising the step of reacting propylene and ammonia in the presence of the ammoxidation catalyst according to claim 1 in a reactor.

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