Molded catalyst and manufacturing method therefor

Abstract

The present invention relates to a molded catalyst and a manufacturing method therefor and, more specifically, to a manufacturing method for a molded catalyst capable of sufficiently expressing coating strength, improving or maintaining catalytic activity even with a small amount of catalytically active metal, minimizing the use of a catalyst coating solution, and being reusable, thereby reducing the loss of the catalyst coating solution, and to a molded catalyst manufactured by the manufacturing method.

Description

Molding catalyst and its manufacturing method

[0001] The present invention relates to a molded catalyst and a method for producing the same, and more particularly, to an economical method for producing a molded catalyst, which is a catalyst having excellent activity in various reactions, by coating one or more metal oxides or metals on various molded bodies such as beads, pellets, and honeycombs, while sufficiently exhibiting the strength of the coating, and improving or maintaining the catalytic activity even with a small amount of catalytically active component, reducing the loss of a coating solution during the catalyst coating process, and producing a molded catalyst without a separate powder catalyst production process, and a molded catalyst produced by the method.

[0002] Catalysts play a crucial role in the industrial production of chemicals. They typically accelerate or slow the chemical transformation of other substances without altering themselves. Catalysts are particularly crucial, as over 90% of all industrially produced chemicals require catalysts in their manufacturing processes. Catalysts are used in diverse industries, including petrochemicals, oil refining, petrochemicals, automobiles, environmental, energy, and gas, and their commercial market is steadily growing.

[0003] In the case of catalysts that are generally used, they are mostly composed of a catalyst carrier and a catalytically active metal supported on the surface of the catalyst carrier, and the catalyst is designed and optimized for application to provide selectivity and reactivity suitable for the required process.

[0004] Such catalysts are manufactured in powder form by mixing a catalyst carrier and a catalytically active metal through various methods such as impregnation, coprecipitation, ion exchange, hydrothermal synthesis, and melting. The manufactured powder catalyst is then manufactured by mixing various additives and extruding it into various shapes through a multi-stage injection molding method. However, the injection molding method is not only a very complicated manufacturing process, but also uses a large amount of powder catalyst and has difficulties in performing production, installation, and maintenance work due to the large amount of dust generated during the manufacturing process.

[0005] Recently, in order to reduce the pressure drop in the catalyst layer and increase the surface area of ​​the catalyst, a catalyst-containing material is coated on the channel surface inside a ceramic or metal molded body in the shape of a bead or honeycomb using dip coating, wash coating, or spray coating. For these ceramic or metal molded body-based coating catalysts, the adhesion between the catalyst and the molded body is a very important factor, and the adhesion can be determined by the molded body surface treatment method, the catalyst coating solution preparation method, the coating method, the drying and firing methods, etc.

[0006] Korean Patent No. 10-0807730 discloses a method for forming an adhesive layer on the interface between a molded body and a catalyst using atomic vapor deposition (ALD) or chemical vapor deposition (CVD) to form a material identical to the catalyst or a material having the same surface properties as the catalyst as the catalyst, in order to increase the adhesive strength between the molded body and the catalyst. Korean Patent No. 10-1403698 discloses a method for manufacturing a metal molded body catalyst by contacting a mixed solution containing a precursor and a precipitant of a metal catalyst with a metal molded body to form a metal precipitate on the metal molded body, and then heat-treating the metal molded body to uniformly disperse and support metal nanoparticles and enhance the bonding strength between the catalyst support layer and the surface of the metal molded body.

[0007] In addition, Korean Patent Publication No. 2023-0103587 provides a method of evenly distributing a catalyst coating solution on the surface of a molded body by deeply penetrating the catalyst coating solution into the surface of the molded body using an ultrasonic method, and then fixing the catalyst coating solution to the surface of the molded body at a constant and uniform thickness using an air knife combined with an infrared lamp.

[0008] However, these prior technologies have limitations in ease of use and commerciality because they require expensive reaction equipment or are performed under vacuum, and it is difficult to evenly distribute the catalyst coating solution on the surface of a molded body to obtain a catalyst coating layer having a uniform and constant thickness, or the coating strength between the catalyst coating layer and the molded body is still weak, and there are problems with a lot of loss of the catalyst coating solution.

[0009] Due to these problems, when one or more metal oxides or metals are directly coated onto a shaped body such as a bead, pellet, or honeycomb, the coating may not adhere well to the shaped body, or even if coated, the coating may easily detach, resulting in reduced catalyst activity and physical durability. This phenomenon is particularly pronounced when two or more components are chemically bonded to form composite metal oxides or metals directly on the surface of the shaped body.

[0010] In order to solve the above-mentioned problem, the present invention provides an economical method for manufacturing a molded catalyst, which can sufficiently exhibit coating strength by directly forming one or more types of metal oxides or metals on a molded body without forming a separate metal oxide or metal powder, while also improving or maintaining catalytic activity with a small amount of catalytically active ingredient and reducing loss of catalyst coating liquid, and a molded catalyst manufactured by the above-mentioned manufacturing method.

[0011] [Prior Art Literature]

[0012] [Patent Document]

[0013] (Patent Document 1) Korean Patent No. 10-0807730 (Published: October 1, 2007)

[0014] (Patent Document 2) Korean Patent No. 10-1403698 (Published: February 7, 2013)

[0015] (Patent Document 3) Korean Patent Publication No. 2023-0103587 (Published: July 7, 2023)

[0016] The main purpose of the present invention is to solve the above-mentioned problems, and to provide a method for producing a molded catalyst capable of sufficiently expressing coating strength, improving or maintaining catalytic activity with a small amount of catalytically active metal, minimizing the use of a catalyst coating solution, and reducing the loss of the catalyst coating solution, and a molded catalyst produced by the above-mentioned method.

[0017] In order to achieve the above object, one embodiment of the present invention provides a method for manufacturing a molded catalyst, comprising: (a) a step of immersing a molded body in a coating solution containing a catalyst component to form a wet layer containing a catalyst component on the surface of the molded body; (b) a step of immersing the molded body on which the wet layer has been formed in a fixing solution in which at least one compound selected from the group consisting of LiOH, NaOH, KOH, NH4OH, and (NH2)2CO(urea) is dissolved to fix the wet layer on the surface of the molded body; and (c) a step of heat-treating the molded body on which the wet layer has been fixed on the surface to form a coating layer of a catalyst component on the surface of the molded body.

[0018] In a preferred embodiment of the present invention, the molded body of step (a) may be surface-treated with an acid and / or a base, and the acid may be at least one selected from the group consisting of HCl, HNO3, H2SO4, HF, H3PO4, and organic acids, and the base may be at least one selected from the group consisting of basic substances such as LiOH, NaOH, KOH, NH4OH, and NaBH4.

[0019] In a preferred embodiment of the present invention, the coating solution of step (a) may further include a first additive selected from the group consisting of methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, refined starch, dextrin, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, and polyethylene glycol; and / or at least one second additive selected from polyhydric alcohols.

[0020] In a preferred embodiment of the present invention, the first additive may be contained in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the catalyst carrier component, and the second additive may be contained in an amount of 0.5 to 90 parts by volume based on 100 parts by volume of the catalyst carrier component.

[0021] In a preferred embodiment of the present invention, it may be characterized in that after immersion of the coating liquid in step (a), an air blow process for removing excess coating liquid is further included.

[0022] In a preferred embodiment of the present invention, the solvent of the coating solution of step (a) and the solvent of the fixing solution of step (b) may be independently at least one selected from water, methanol, ethanol, isopropanol, and glycol.

[0023] In a preferred embodiment of the present invention, the fixing solution of step (b) may be maintained at 20°C to 50°C, and the heat treatment of step (c) may include a drying step of 40°C to 120°C and a calcination step of 350°C to 700°C.

[0024] In a preferred embodiment of the present invention, the method for producing a molded catalyst according to the present invention may further include, in addition to steps (a) to (c), a step of (d) loading a catalytically active material onto a coating layer of a molded body; and a step of (e) drying and / or calcining the molded body loaded with the catalytically active material to produce a molded body loaded with the catalytically active material.

[0025] In addition, the present invention provides a molded catalyst having a coating layer of a catalyst component formed on the surface of a molded body, characterized in that it is manufactured by including the steps of: (a) immersing a molded body in a coating solution containing a catalyst component to form a wet layer containing a catalyst component on the surface of the molded body; (b) immersing the molded body on which the wet layer has been formed in a fixing solution in which at least one compound selected from the group consisting of LiOH, NaOH, KOH, NH4OH, and (NH2)2CO is dissolved to fix the wet layer on the surface of the molded body; and (c) heat-treating the molded body on which the wet layer has been fixed to the surface to form a coating layer of a catalyst component on the surface of the molded body.

[0026] In a preferred embodiment of the molded catalyst of the present invention, it may be characterized in that it is manufactured by further including: (d) a step of loading a catalytically active material onto a coating layer of a molded body; and (e) a step of drying and / or calcining the molded body loaded with the catalytically active material to manufacture a molded body loaded with the catalytically active material.

[0027] According to the present invention, a method for manufacturing a molded catalyst is provided in which a catalyst component is coated on the surface of a pre-molded molded body without manufacturing a powder catalyst to manufacture a molded catalyst, thereby improving the adhesion between the molded body and the carrier coating layer, thereby having the effect of sufficiently exhibiting the mechanical strength of the final manufactured molded catalyst.

[0028] In addition, when the first additive and / or the second additive of the present invention is used, the use of the coating solution is minimized, and the remaining coating solution and / or fixing solution used for catalyst coating can be reused, thereby reducing unnecessary material loss in the manufacturing process of the molded catalyst, and even if only a small amount of expensive catalytically active components and components constituting the coating layer are used, the catalytic activity can be significantly improved, thereby enabling economical mass production of the molded catalyst.

[0029] Figure 1 is a flowchart schematically illustrating a method for manufacturing a molded catalyst according to one embodiment of the present invention.

[0030] Figure 2 is a photograph of the bead state after sintering of Example 13 and Comparative Example 5 of the present invention.

[0031] Figure 3 is a photograph of the bead state after sintering of Example 14 and Comparative Example 6 of the present invention.

[0032] [Explanation of symbols]

[0033] 100: Molded body

[0034] 200: Coating solution

[0035] 300: Wet layer

[0036] 400: Fixative solution

[0037] 500: Catalytic component coating layer

[0038] 1000: Molding catalyst

[0039] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

[0040] The terms “comprising,” “including,” or “having” used in this specification indicate the presence of features, values, steps, operations, components, parts, or combinations thereof described in the specification, and do not exclude the possibility that other features, values, steps, operations, components, parts, or combinations thereof that are not mentioned may be present or added.

[0041] The reactions and mixing described below can be carried out at room temperature and pressure unless otherwise specified, and can be carried out under typical reaction and mixing conditions without additional additions. However, this should not be interpreted in a way that deviates from matters clearly understood by those skilled in the art.

[0042] The present invention relates to a method for producing a molded catalyst, comprising the steps of: (a) immersing a molded body in a coating solution containing a catalyst component to form a wet layer containing a catalyst component on the surface of the molded body; (b) immersing the molded body on which the wet layer has been formed in a fixing solution to fix the wet layer on the surface of the molded body; and (c) heat-treating the molded body on which the wet layer has been fixed on the surface to form a coating layer of a catalyst component on the surface of the molded body; and to a molded catalyst produced by the method.

[0043] Hereinafter, with reference to the attached drawings, a method for manufacturing a molded catalyst according to the present invention and a molded catalyst manufactured by the method will be described in detail. Figure 1 is a flowchart schematically illustrating a method for manufacturing a molded catalyst according to one embodiment of the present invention.

[0044] Referring to FIG. 1, the method for manufacturing a molded catalyst according to the present invention first immerses a molded body (100) in a coating solution (200) containing a catalyst component so that a wet layer (300) containing the catalyst component is formed on the surface of the molded body [step (a)].

[0045] The above coating solution (200) contains a catalyst component, and the catalyst component contained in the coating solution may be at least one selected from a catalytically active substance that promotes a reaction, a precursor of the catalytically active substance, a carrier material capable of supporting the catalytically active substance, or a precursor of the carrier material. For example, the catalyst component may be a salt compound or complex containing a metal element, and specifically, may be at least one selected from a metal nitrate, a metal sulfate, a metal phosphate, a metal halogen salt, a metal alkoxide salt, a metal oxynitrate, a metal hydroxide, a metal acetate salt, a metal alkyl salt, a metal hydrate, and the like. The content of the catalyst component in the entire coating solution is 1 mmol mL. -1 ~ 100 mmol mL -1 may be, preferably 5 mmol mL -1 ~ 10 mmol mL -1 It could be.

[0046] In the above coating layer, the catalyst component may be dissolved or dispersed in a solvent, and the solvent may be used without limitation as long as it is a solvent capable of dissolving or dispersing the catalyst component. For example, water such as distilled water or purified water, alcohol such as methanol, ethanol, isopropanol, glycol, etc. may be used, and preferably water.

[0047] The above-mentioned wet layer is formed by a dip coating method in which the molded body is immersed in a coating liquid so that the coating liquid penetrates into the inside of the molded body. At this time, dip coatings in which the molded body is dipped in the coating liquid to form a wet layer (300) having a coating liquid component on the surface of the molded body can be controlled by adjusting the coating temperature and time according to the type, concentration, and amount of the coating liquid and the molded body. For example, the temperature of the coating liquid during the dipping can be 20°C to 40°C, and the time can be performed for 0.5 to 4 hours. In addition, several coating processes can be repeatedly performed so that the coating layer can be formed on the surface of the molded body with a desired thickness and strong adhesive strength.

[0048] If necessary, a first additive that binds the catalyst component to the surface of the molded body and provides cohesion and viscosity may be added to the coating solution. The first additive prevents the catalyst component contained in the wet layer formed on the surface of the molded body in the fixing step described below from being eluted into the fixing solution. Any organic additive that can improve the adhesion of the catalyst component to the surface of the molded body and prevent the catalyst component in the wet layer from being eluted into the fixing reaction solution in the fixing step may be applied without limitation as the first additive, and examples thereof may be selected from methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, refined starch, dextrin, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyethylene glycol, and the like, and in terms of forming a uniform wet layer, methyl cellulose, polyvinyl alcohol, polyethylene glycol, and the like are preferable, and methyl cellulose and polyvinyl alcohol are more preferable.

[0049] When the molded body having the wet layer formed due to the addition of the first additive is immersed in a fixing solution to perform a fixing process, the catalyst component of the wet layer is not eluted into the fixing solution, thereby preventing loss of the catalyst component. In addition, the fixing solution may not be contaminated, thereby making the method for manufacturing the molded catalyst economical and simple.

[0050] The first additive may be contained in the coating solution in an amount of 0.05 parts by weight or more and 10 parts by weight or less, preferably 1 to 3 parts by weight, relative to 100 parts by weight of the catalyst carrier component. If the additive is contained in an amount of less than 0.05 parts by weight relative to 100 parts by weight of the catalyst carrier component, the first additive may have difficulty performing its role, and if it exceeds 10 parts by weight relative to 100 parts by weight of the catalyst carrier component, problems may occur in the reduction of the content of the catalyst component and the fixation step due to the excessive amount of additive.

[0051] Meanwhile, the coating solution may further include one or more second additives selected from polyhydric alcohols, for example, glycerol, ethylene glycol, propylene glycol, etc., or waxes and lubricants, in order to suppress shrinkage or peeling of the coating layer that may occur during the drying process described below. The second additive may be contained in an amount of 0.5 to 90 parts by volume based on 100 parts by volume of the catalyst carrier component, and the additive in the above content range acts to form a uniform coating layer without deteriorating the properties of the catalyst.

[0052] The molded body coated with the above coating solution can use a molded body of various shapes depending on the reaction to which the molding catalyst is applied, and specifically, can be in the shape of a bead, pellet, felt, mat, mesh, foam, foil, honeycomb, pin, etc., and the molded body material can also use a metal or ceramic depending on the reaction to which it is applied, and specifically, can be one or more types of metal oxides such as alumina, silica, zirconia, ceria, silicon carbide, cordialite, a ceramic material, or various metal materials.

[0053] In one embodiment, when the molded catalyst according to the present invention is applied to an ammonia decomposition reaction, the molded material is preferably alumina, silica, etc. in terms of reaction efficiency, and the shape thereof is preferably a bead shape or a honeycomb shape.

[0054] In addition, the molded body may be subjected to chemical surface treatment using a surface treatment agent such as an acid and / or a base to uniformly disperse the catalyst support component on the surface by forming a polar functional group such as a hydroxyl group and an unstable surface state. At this time, the acid that can be used for the surface treatment of the molded body may be at least one selected from the group consisting of HCl, HNO3, H2SO4, HF, H3PO4, organic acids, etc., and the organic acids are not limited thereto, but may be, for example, acetic acid, formic acid, lactic acid, citric acid, acrylic acid, sulfonic acid, carboxylic acid, etc. The base may be at least one selected from the group consisting of a base solution containing LiOH, NaOH, KOH, NH4OH, and NaBH4, and may be preferably KOH or NH4OH.

[0055] In the present invention, a dip coating method is applied to form a coating layer on the surface of a molded article. This allows for the formation of a uniform and thin coating layer on the surface of even complexly structured articles, and facilitates control of the coating amount. Furthermore, the use of the first and / or second additives minimizes coating liquid loss while simultaneously enabling continuous use of the coating liquid, thereby enabling the economical mass production of molded catalysts.

[0056] In addition, in the present invention, the strength of the coating layer is increased by removing the excess coating liquid of the wet layer remaining on the surface of the molded body after immersing the coating liquid, and in order to secure an appropriate thickness of the coating liquid layer, the strength and time of the air blow for removing the excess coating liquid can be controlled, or the viscosity of the coating liquid can be controlled according to the additive content.

[0057] Thereafter, the molded body (100) in which the wet layer (300) is formed by the above-described dip coating is immersed in a fixing solution (400) to perform fixation of the wet layer [step (b)].

[0058] The above step (b) can strongly bind the catalytic component contained in the wet layer (300) to the surface of the molded body by fixing the wet layer on the surface of the molded body created in step (a) using a fixing solution (400).

[0059] At this time, the fixation can be performed by immersing the molded body on which the wet layer is formed in a fixation solution of 20°C to 60°C for 30 minutes to 4 hours, preferably 1 hour to 3 hours. When the fixation is performed within the temperature range and for the time, a coating layer with a uniform and strong bond is formed, and the problem of the wet layer being excessively exposed to the reaction solution, causing the components contained in the wet layer to be dissolved, preventing the formation of the coating layer from being performed properly, and the problem of the reaction solution being contaminated and making it impossible to reuse.

[0060] As the above-mentioned fixing solution (400), a compound that enables the wet layer of the catalyst component contained in the coating solution to be fixed to the surface of the molded body can be applied without limitation as long as it is dissolved in a solvent, and specifically, it can be one type of solution selected from the group consisting of LiOH, NaOH, KOH, NH4OH and (NH2)2CO (urea), and in terms of ease of fixing and cost, it can be preferably NaOH or KOH.

[0061] The solvent of the above fixing solution may be used without limitation as long as it is a solvent that can dissolve LiOH, NaOH, KOH, NH4OH and (NH2)2CO, and examples thereof include water such as distilled water, purified water, etc.; alcohol such as methanol, ethanol, isopropanol, etc.; glycol, etc., and preferably water. The concentration of compounds such as LiOH, NaOH, KOH, NH4OH, (NH2)2CO in the fixing solution is 0.5 mol L. -1 ~ 4 mol L -1 may be, preferably 0.75 mol L -1 ~ 1.25 mol L -1 It could be.

[0062] Thereafter, the molded body with the above-mentioned wet layer fixed is heat-treated to form a catalyst component coating layer (500) on the surface of the molded body (100) [step (c)].

[0063] In the step (b), the molded body, which has been immersed in the fixing solution and in which the fixation of the wet layer has been performed, is separated from the fixing solution, and in the step (c), the fixed wet layer is heat-treated. The heat treatment may further include a drying step in detail. That is, the solvent in the fixing solution can be completely removed through drying. The drying can be performed for a predetermined time, for example, 4 hours to 48 hours, at 40°C to 120°C, and can be performed using a conventional method such as hot air, constant temperature and humidity, etc. When the drying temperature is within the above range, the fixed wet layer can be sufficiently dried, and the phenomenon of the dried wet layer being detached due to excessive drying or a rapid reaction of the components contained in the wet layer can be prevented.

[0064] Thereafter, the heat treatment of the above-mentioned molded body can be varied in consideration of the unique glass transition temperature of the molded body or catalyst carrier component, but in order to obtain a molded body having a support coating layer formed without cracks, it can be preferably fired at 350°C to 700°C for a predetermined time in an oxidizing atmosphere. The heat treatment time can vary depending on conditions such as the firing temperature, coating amount, size and quantity of the molded body, but can be, for example, 2 to 6 hours.

[0065] If the heat treatment temperature is less than 350°C, a problem may arise in which the additives contained in the dried wet layer are not properly removed due to the low sintering temperature, and if it exceeds 700°C, excessive deformation of the coating layer and the shape of the molded body may occur due to the excessive sintering temperature. In addition, rapid temperature changes during the heat treatment process cause rapid combustion and oxidation of the additives, which causes cracks and detachment in the formation of the coating layer, significantly reducing the strength of the coating layer. Therefore, it is preferable to manufacture by gradually increasing the temperature by 5°C or less per minute.

[0066] If the formed coating layer is made of a catalytically active material, it can be applied as a molded catalyst, and has the effects of high strength properties and low catalyst manufacturing cost according to the present invention. If the coating layer is made of a carrier material rather than a catalytically active material, a step (d) of supporting a catalytically active material on the coating layer of the molded body may be further included.

[0067] In the above step (d), any method that can support the catalytically active material on the molded body on which the coating layer (500) is formed can be applied without limitation, and specifically, the method can be a hydrothermal synthesis method, a co-precipitation method, an impregnation method, a mechanical mixing method, a deposition method, etc., and preferably, the method can be an impregnation method, etc.

[0068] In one embodiment, the impregnation among the above-mentioned supporting methods may be performed by dissolving a catalytically active substance or a precursor thereof in a solvent, then evenly dispersing the solution on a carrier coating layer, and evaporating the solvent. At this time, the solvent may be used without limitation as long as it can evenly disperse the catalytically active substance precursor, and examples thereof include water, methanol, ethanol, propanol, butanol, acetone, and the like, and the content thereof may be used without limitation as long as it can evenly disperse the catalytically active substance.

[0069] At this time, the catalytically active material may be a compound or mixture containing various metal elements depending on the reaction to which the molded catalyst (1000) is applied, and examples thereof may include transition metal elements such as platinum, palladium, ruthenium, cobalt, nickel, copper, zinc, and tungsten, and alkali metals and alkaline earth metals such as lithium, rubidium, magnesium, and calcium.

[0070] The content of the catalytically active material to be supported varies depending on the reaction applied, but may be 0.1 wt% or more and 40 wt% or less, and preferably 10 wt% or less, based on the total weight of the molded body.

[0071] Thereafter, if necessary, a step (e) of manufacturing a molded body loaded with a catalytically active material by drying and / or calcining the molded body loaded with the catalytically active material may be further performed.

[0072] The drying in the above step (e) can be performed at 50°C to 120°C for a predetermined period of time, for example, 2 hours to 48 hours, and can be performed using a conventional method such as an oven, hot air, or constant temperature and humidity.

[0073] Although it may vary depending on the situation, if the drying temperature is below 50°C, the solvent used in the deposition process cannot be sufficiently removed due to the low drying temperature, and if it exceeds 120°C, the solvent used in the deposition process may rapidly evaporate due to the excessive drying temperature, causing the coating layer to collapse, so it is desirable to maintain the above temperature range.

[0074] The above-described dried molded body can be subjected to sintering. The sintering can be varied in consideration of the unique sintering temperature depending on the type of molded body. However, in order to obtain a molded catalyst (1000) without catalyst cracking, the sintering can be preferably performed at 300°C to 500°C for a predetermined period of time in an oxidizing atmosphere. The sintering time can vary depending on conditions such as the sintering temperature, the amount of support, the size and quantity of the molded body, and the like. However, for example, the sintering time can be 1 to 4 hours.

[0075] The above-mentioned sintering temperature range is desirable to avoid problems such as insufficient stabilization of the catalytic components and activity-enhancing components due to low sintering temperatures, or reduced dispersion of the catalytic active components and activity-enhancing components and deformation of the molded body due to high sintering temperatures. In addition, since rapid temperature changes during the sintering process can cause cracks and pores in the molded body and the coating layer formed on the surface of the molded body, significantly reducing the strength, it is desirable to manufacture the molded body by gradually increasing the temperature at a rate of 10°C or less per minute.

[0076] In addition, the present invention provides a molded catalyst having a coating layer of a catalyst component formed on the surface of a molded body, characterized in that it is manufactured by including the steps of: (a) immersing a molded body in a coating solution containing a catalyst component to form a wet layer containing a catalyst component on the surface of the molded body; (b) immersing the molded body on which the wet layer has been formed in a fixing solution in which at least one compound selected from the group consisting of LiOH, NaOH, KOH, NH4OH, and (NH2)2CO is dissolved to fix the wet layer on the surface of the molded body; and (c) heat-treating the molded body on which the wet layer has been fixed to the surface to form a coating layer of a catalyst component on the surface of the molded body.

[0077] The above catalyst component may be at least one selected from a catalytically active substance, a precursor of the catalytically active substance, a carrier material capable of supporting the catalytically active substance, or a precursor of the carrier material, and the molded catalyst of the present invention may be manufactured by a manufacturing method further including, as described above, (d) a step of supporting the catalytically active substance on a coating layer of a molded body; and (e) a step of drying and / or calcining the molded body supporting the catalytically active substance to produce a molded body supporting the catalytically active substance. Other details according to the manufacturing method are the same as described above, so repeated description is omitted.

[0078] The molded catalyst (1000) manufactured by the manufacturing method according to the present invention can sufficiently exhibit coating strength by improving the adhesion between the molded body and the coating layer, and the uniformity of the coating layer is improved while reducing the loss of the catalyst coating liquid through the use of the first additive and / or the second additive. In addition, when the coating layer of the molded catalyst (1000) manufactured by the manufacturing method according to the present invention is made of a carrier material, a catalytically active material is supported on the formed coating layer, so that the catalytic activity can be significantly improved even with only a small amount of the catalytically active material.

[0079] Hereinafter, the present invention will be described in more detail by way of preferred embodiments to aid understanding; however, the following embodiments are merely illustrative of the present invention, and the scope of the present invention is not limited to the following embodiments.

[0080] <Example 1>

[0081] A solution was prepared by dissolving 4 mmol (1.7544 g) of Ce(NO3)3ㆍ6H2O (Sigma, 99%) and 2 mmol (0.8661 g) of La(NO3)3ㆍ6H2O (Sigma, 99%) in 10 mL of deionized water as catalyst components, and 1 g of methyl cellulose as a first additive was dissolved in 10 mL of deionized water and 30 mL of ethanol (99.9%). 11 mL of the solution was taken and added to the solution of the catalyst components, and 5 mL of glycerol was additionally mixed to prepare a coating solution.

[0082] Afterwards, 15 g of alumina beads (average diameter 3 mm) were dip-coated in the prepared coating solution at room temperature for 60 minutes, and then fixed by immersing in a fixing solution of 20 mL of 1 M KOH at room temperature for 30 to 120 minutes. After the fixing was completed, the fixed alumina beads were dried in an oven at 60°C for 24 hours, and then heat-treated at 600°C (heating condition, 5°C / min) for 6 hours. Afterwards, 12 g of heat-treated alumina beads were suspended in a solution of 1.5 wt.% Ruthenium nitrosyl nitrate solution (15.2586 mL) diluted with 50 mL of deionized water, and the solvent was evaporated at 80°C and 400 mbar. The resulting solution was dried in an oven at 100°C for 24 hours, and then calcined at 350°C (heating rate, 10°C / min) for 2 hours to produce a Ru / La-Ce / Al2O3 molded catalyst.

[0083] <Examples 2 and 3>

[0084] Ru / La-Ce / ZrO2 and Ru / La-Ce / SiO2 molded catalysts were manufactured in the same manner as in Example 1, except that SiO2 gel beads (average diameter 1.8 mm) and ZrO2 pellets (3 mm in diameter x 5 mm in height, cylindrical) molded bodies surface-treated by immersing in 1 M KOH for 1 hour instead of alumina beads before immersing in the coating solution under the conditions in Table 1 were used, and the time for fixing the wet layer by immersing in the 1 M KOH fixing solution was changed to 2 hours.

[0085] <Examples 4 to 6>

[0086] It was manufactured in the same manner as Example 1, but instead of KOH, LiOH, NaOH, and NH4OH were used as the fixing solution, respectively.

[0087] <Examples 7 to 9>

[0088] In Example 1, a molded catalyst was manufactured in the same manner as described above, except that polyvinyl alcohol (manufacturer: Sigma Aldrich, average molecular weight: 89,000 to 98,000), polyethylene glycol (manufacturer: Sigma Aldrich, average molecular weight: 400), and silica sol (manufacturer: Sigma Aldrich, model name: Ludox®-AS40) were used instead of methyl cellulose as the first additive.

[0089] <Examples 10 to 12>

[0090] A molded catalyst was manufactured using the same method as Example 1, but using different catalyst components.

[0091] In order to prepare a coating solution composition corresponding to each example, 6 mmol of Mg(NO3)2ㆍ6H2O, 6 mmol of Y(NO3)3ㆍ6H2O, and 6 mmol of Pr(NO3)3ㆍ6H2O were added to 10 mL of deionized water to prepare a solution in which the catalyst component was dissolved, and 11 mL of a solution in which 1 g of methyl cellulose as the first additive was dissolved in 10 mL of deionized water and 30 mL of ethanol (99.9%) was taken and added to the solution in which the catalyst component was dissolved, and then 5 mL of glycerol was additionally added to prepare each coating solution.

[0092] <Example 13>

[0093] It was manufactured in the same manner as Example 1, except that the concentration of the catalyst component was four times that of the catalyst component of Example 1.

[0094] <Example 14>

[0095] In Example 13, only Ce(NO3)3ㆍ6H2O was used instead of La(NO3)3ㆍ6H2O as a catalyst component, and the number of moles of Ce(NO3)3ㆍ6H2O was made equal to the sum of the number of moles of Ce(NO3)3ㆍ6H2O and La(NO3)3ㆍ6H2O in Example 13.

[0096] <Example 15>

[0097] As per the conditions in Table 1, the molded body was manufactured in the same manner as in Example 1, except that pretreatment was performed by immersing it in a 1 M KOH solution for 1 hour.

[0098] <Example 16>

[0099] It was manufactured in the same manner as Example 1, except that methyl cellulose, the first additive component, was not added to the coating solution of Example 1.

[0100] <Example 17>

[0101] A molding catalyst was manufactured in the same manner as in Example 1, except that the second additive was not used in the coating solution.

[0102] <Example 18>

[0103] A molding catalyst was prepared in the same manner as in Example 1, except that ethylene glycol (manufacturer: Sigma Alrich) was used instead of glycerol as the second additive.

[0104] Comparative Examples 1 to 3

[0105] Each molded body was surface treated by immersing 15 g each of alumina beads (average diameter 3 mm), SiO2 gel beads (average diameter 1.8 mm), and ZrO2 pellets (3 mm in diameter x 5 mm in height, cylindrical) in 20 mL of 1 M KOH as a surface treatment agent at room temperature for 60 minutes. In addition, 3 g La-CeO x A uniform paste was prepared by mixing powder, 0.3 g glycerol, 0.3 g polyvinyl butyral, and 1 mL to 3 mL 1-butanol and stirring for 10 minutes with a stirrer. 15 g of each surface-treated molded body was added to the prepared paste and operated in a planetary mill at 500 RPM for 10 minutes to coat the paste on the surface of the molded body.

[0106] The powder-coated molded body was dried in an oven for 24 hours, and then heat-treated at 600 ℃ (heating rate, 5 ℃ / min) for 6 hours. Afterwards, the heat-treated alumina beads were suspended in a solution of 1.5 wt.% Ruthenium nitrosyl nitrate solution (15.2586 mL) diluted with 50 mL of deionized water, and the solvent was evaporated at 80 ℃ and 400 mbar. Then, the resulting product was dried in an oven at 100 ℃ for 24 hours, and calcined at 350 ℃ (heating rate, 10 ℃ / min) for 2 hours to obtain Ru / La-Ce / Al2O3-powder and Ru / La-Ce / SiO2-powder. and Ru / La-Ce / ZrO2-powder Each molding catalyst was manufactured.

[0107] Comparative Example 4

[0108] It was manufactured in the same manner as Example 1, except that the fixation step was performed using 20 mL of deionized water instead of the fixation solution, as in the conditions of Table 1.

[0109] <Comparative Examples 5 and 6>

[0110] Comparative examples 5 and 6 were manufactured in the same manner as examples 13 and 14, respectively, but the fixing step was omitted.

[0111] Comparative Example 7

[0112] A solution was prepared by dissolving 3.202 g La(NO3)3ㆍ6H2O and 6.4865 g Ce(NO3)3ㆍ6H2O in 100 mL of deionized water, suspending 15 g of alumina beads (average diameter 3 mm) and evaporating the solvent at 80°C and 400 mbar. The molded body containing the catalyst component was dried in an oven at 100°C for 24 hours and then heat-treated at 500°C for 3 hours. Afterwards, 12 g of heat-treated alumina beads were suspended in a solution of 1.5 wt.% Ruthenium nitrosyl nitrate solution (15.2586 mL) diluted with 50 mL of deionized water, and the solvent was evaporated at 80°C and 400 mbar. The resulting solution was dried in an oven at 100°C for 24 hours and calcined at 350°C (heating rate, 10°C / min) for 2 hours to produce the Ru / La-Ce / Al2O3 molded catalyst.

[0113] [Table 1]

[0114]

[0115] <Experimental Example 1: Mechanical Properties and Component Analysis of Molded Catalysts>

[0116] To measure the mechanical strength of the molded catalyst, a fracture strength tester was used to measure the maximum stress measured when stress was applied vertically to each molded catalyst more than 10 times. The cross-section of the molded catalyst was made into a circle with the radius of the catalyst, and the compressive strength was calculated, and the average value was used as a representative value. The calculation formula used is as follows.

[0117]

[0118] In order to measure the detachment of the coating layer, a ceramic material container was filled with a constant weight of the molded catalyst before Ru loading to about 70% of the cross-sectional area of ​​the container using a shaker, and the container was shaken for 1 to 3 hours at 250 RPM so that the molded catalyst could collide violently inside the container. After the powder that fell off from the molded body was sieved and removed, the weight was measured, and the difference between the initial weight of the molded catalyst and the weight after shaking was calculated to calculate the detachment rate of the coating using the following formula.

[0119]

[0120] In order to measure the components of the manufactured bead catalyst, the bead catalyst before Ru was loaded was uniformly and finely ground into powder, and then qualitative and quantitative analysis was performed using XRF (X-ray fluorescence).

[0121] <Experimental Example 2: Performance Measurement of Ammonia Decomposition Catalyst>

[0122] The ammonia decomposition reaction was performed using the molded catalysts manufactured in the examples and comparative examples, and the ammonia conversion rate was measured. The measurement was performed at atmospheric pressure and an ammonia space velocity of 3000 mL / g. cat. Hydrogen, nitrogen, and unreacted ammonia gas generated after the ammonia decomposition reaction were measured using gas chromatography under the conditions of / h and reaction temperatures of 350 ℃, 400 ℃, 450 ℃, 500 ℃, and 550 ℃, and the ammonia conversion rate was calculated based on the equation below.

[0123]

[0124] <Desorption rate of the molding catalyst>

[0125] In order to confirm the effect of fixing the coating layer of the molded catalyst manufacturing method according to the present invention, the molded catalyst manufactured by the slurry coating of Comparative Examples 1 to 3 and the same molded body as in Comparative Examples 1 to 3 were used, and the desorption rate of the molded catalysts of Examples 15, 2, and 3, which are molded catalysts manufactured by the method of the present invention, was measured as in Experimental Example 1, and the results are shown in Table 2 below.

[0126] [Table 2]

[0127]

[0128] As shown in Table 2 above, the Al2O3 beads and ZrO2 pellets were found to have no delamination in the molded catalyst manufactured by the method of the present invention, and it was confirmed that the delamination rate of the SiO2 gel beads was lowered compared to the existing slurry coating method. In this way, it was confirmed that when the molded catalyst is manufactured by the manufacturing method of the present invention regardless of the type of molded body, the fixation of the coating layer of the molded catalyst is greatly increased, and the delamination rate of the coating layer can be lowered compared to the existing slurry coating.

[0129] <Types of fixing solutions and the influence of fixing treatment>

[0130] In order to see the effect according to the type of fixing solution, the results of the removal rate of examples using the same manufacturing method except that only the type of fixing solution was changed are shown in Table 3 below, and Table 4 shows the results of applying the catalyst manufactured in the manufacturing method of the molded catalyst of Example 1, Example 6 and Comparative Example 4 to the ammonia conversion reaction in Experimental Example 2.

[0131] [Table 3]

[0132]

[0133] [Table 4]

[0134]

[0135] It was confirmed that LiOH, KOH, NaOH, and NH4OH, as the fixing solution of the present invention, did not cause detachment of the coating layer. In addition, referring to Table 4, it was confirmed that in the case of Comparative Example 4, which did not use the fixing solution of the present invention but used water, the reaction activity in the ammonia decomposition reaction was low, and it was confirmed that Example 1, which used an alkali metal hydroxide as the fixing solution, showed the highest activity.

[0136] Comparative Examples 5 and 6 differ from Examples 13 and 14 only in that a fixing step was not performed. However, as can be seen in Figures 2 and 3, Comparative Examples 5 and 6 exhibited a phenomenon in which the beads were broken after sintering. This confirmed that a fixing step using a fixing solution is necessary in the production of a molded catalyst.

[0137] <Influence of catalyst component type>

[0138] In order to see the desorption rate of the coating layer when the catalyst component was different, the desorption rate of the molded catalyst of examples using the same manufacturing method except for the different catalyst component was measured, and the results are shown in Table 5.

[0139] [Table 5]

[0140]

[0141] Referring to Table 5, it was confirmed that even when the type of catalyst component is a composite component of La-Ce or a single component such as Mg, Y, Pr, or Ce, the detachment of the coating layer is suppressed when the fixation step is included according to the manufacturing method of the present invention.

[0142] <Effect of the first additive>

[0143] In order to confirm the effect of the first additive of the present invention, the detachment rates of Examples 1 and 16, which differ only in the presence or absence of the first additive added to the coating solution, were measured, and the results are shown in Table 6.

[0144] [Table 6]

[0145]

[0146] As shown in Table 6 above, in Example 16 where the first additive was not used, no detachment of the coating layer was observed, confirming that the detachment rate of the coating layer in the present invention is determined at the fixation stage. On the other hand, when the first additive was not used, it was visually observed that a precipitate of the catalyst component La-Ce was generated in the fixation solution. This is believed to be because when the La-Ce of the wet layer was immersed in the fixation solution, it was eluted into the fixation solution and reacted with KOH, etc. in the fixation solution to precipitate.

[0147] In order to confirm the dissolution into such a fixing solution, the contents of Al, La and Ce in the molded catalysts manufactured in Examples 1 and 16 were measured by XRF, and the results are shown in Table 7.

[0148] [Table 7]

[0149]

[0150] It was found that the contents of La and Ce in Example 1, in which the first additive was added to the coating solution, were higher than in Example 16, in which the first additive was not used. Through this, it was confirmed that the first additive prevented the catalyst component from being eluted into the fixing solution during the fixing step.

[0151] The above Examples 7 to 9 are cases where polyvinyl alcohol, polyethylene glycol, and silica sol were used as the first additive, respectively. In Examples 7 to 9, as in Example 1, no precipitation due to the dissolution of the catalyst component into the fixing solution was observed.

[0152] <Effect of the second additive>

[0153] In order to confirm the effect of the second additive of the present invention, when comparing Examples 17 and 18, in the case of Example 17 where the second additive was not used, it can be seen that some shrinkage or peeling of the coating layer was observed during the drying process of the fixed alumina beads after the fixation was completed, compared to Examples 1 and 18 where glycerol or ethylene glycol was used. Accordingly, it was confirmed that the second additive prevents shrinkage of the coating layer during the drying process of the coating layer after fixation, thereby improving the uniformity of the final fired coating layer.

[0154] <Effect of surface treatment>

[0155] The compressive strength of the molded catalysts manufactured in Examples 1 and 15, which differ only in the performance of surface treatment, was measured, and the results of the ammonia conversion reaction performed in the same manner as in Experimental Example 2 using the catalyst are shown in Table 8.

[0156] [Table 8]

[0157]

[0158] The molded catalyst of Example 15, which was surface-treated in advance with 1 M KOH, showed a compressive strength of 99.3% of that of Example 1, which was not significantly different from that of Example 1, but the ammonia conversion rate at a low temperature of 350°C was significantly different, reaching about 1.45 times. This shows that although treating the surface of the molded body in advance with acid or base during the manufacture of the molded catalyst does not help improve the strength of the molded catalyst, it can be advantageous when considering the catalytic efficiency.

[0159] <Catalytic activity of the molded catalyst according to the manufacturing method of the present invention>

[0160] In order to compare the catalytic activity in an actual reaction of a catalyst manufactured by the method for manufacturing a molded catalyst of the present invention, the ammonia decomposition reaction of Experimental Example 2 was performed using the catalyst manufactured in Comparative Example 7 and Example 1, in which a coating layer was formed by impregnation, and the results were measured and shown in Table 9.

[0161] [Table 9]

[0162]

[0163] It was confirmed that the molded catalyst manufactured in Example 1 showed a higher ammonia conversion rate over the entire experimental temperature range compared to the molded catalyst of Comparative Example 7. In the case of Example 1, the amount of precursors of cerium and lanthanum included in the coating solution was only about 27% of that of Comparative Example 7, and also, since the dip coating method was followed when forming the coating layer (less than 10% of the coating solution was consumed based on one coating), the amount of cerium and lanthanum used was significantly lower than that of the molded catalyst of Comparative Example 7, so the specific surface area of ​​the La-Ce coating layer would have an absolutely higher value in Comparative Example 7, and when the same amount of Ru was supported, it was expected that the ammonia conversion rate would be higher in Comparative Example 7 because Ru would be better dispersed. However, the experimental results showed that Example 1 showed a higher conversion rate.

[0164] From this, it was confirmed that the manufacturing method according to the present invention can manufacture a highly efficient catalyst through the synergistic effect of the mutual bonding of the composite oxide layer of La-Ce and alumina while reducing the amount of a relatively expensive coating layer such as La-Ce.

[0165] While the present invention has been described with reference to the above-described embodiments, various embodiments may be constructed within the spirit and scope of the present invention. Accordingly, the scope of the present invention is defined by the appended claims and their equivalents, and is not limited to the specific embodiments described herein.

Claims

1. (a) A step of immersing a molded body in a coating solution containing a catalyst component to form a wet layer containing a catalyst component on the surface of the molded body; (b) The molded body on which the above wet layer is formed is treated with LiOH, NaOH, KOH, NH 4 OH and (NH 2 ) 2 A step of fixing a wet layer on the surface of a molded body by immersing the molded body in a fixing solution in which one or more compounds selected from the group consisting of CO are dissolved; and (c) A method for manufacturing a molded catalyst, comprising the step of heat-treating a molded body having a wet layer fixed on the surface to form a coating layer of a catalyst component on the surface of the molded body.

2. In paragraph 1, A method for producing a molded catalyst, characterized in that the molded body of step (a) is surface-treated with an acid and / or a base.

3. In paragraph 2, The above acid is HCl, HNO 3 , H 2 SO 4 , HF, H 3 PO 4 and at least one selected from the group consisting of organic acids, wherein the base is LiOH, NaOH, KOH, NH 4 OH and NaBH 4 A method for producing a molded catalyst, characterized in that it comprises at least one selected from the group consisting of:

4. In paragraph 1, A method for producing a molding catalyst, characterized in that the coating solution of step (a) further comprises at least one first additive selected from the group consisting of methyl cellulose, hydroxyethyl cellulose, sodium carboxymethyl cellulose, refined starch, dextrin, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, and polyethylene glycol; and / or at least one second additive selected from polyhydric alcohols.

5. In paragraph 4, A method for producing a molded catalyst, characterized in that the first additive is contained in an amount of 0.05 to 10 parts by weight based on 100 parts by weight of the catalyst carrier component, and the second additive is contained in an amount of 0.5 to 90 parts by volume based on 100 parts by volume of the catalyst carrier component.

6. In paragraph 4, A method for producing a molded catalyst, characterized in that the coating solution of step (a) contains 0.05 to 10 parts by weight of the first additive with respect to 100 parts by weight of the catalyst carrier component, and 0.5 to 90 parts by volume of the second additive with respect to 100 parts by volume of the catalyst carrier component.

7. In paragraph 1, A method for manufacturing a molded catalyst, characterized in that after immersion in the coating liquid of step (a) above, an air blow process for removing excess coating liquid is further included.

8. In paragraph 1, A method for producing a molded catalyst, characterized in that the fixing solution of step (b) is maintained at 20°C to 50°C.

9. In paragraph 1, A method for producing a molded catalyst, characterized in that the heat treatment in step (c) includes a drying step of 40°C to 120°C and a calcination step of 350°C to 700°C.

10. In paragraph 1, (d) a step of loading a catalytically active material onto the coating layer of the molded body; and (e) A method for producing a molded catalyst, characterized in that it further includes a step of drying and / or calcining a molded body loaded with a catalytically active material to produce a molded body loaded with a catalytically active material. 11.(a) A step of immersing a molded body in a coating solution containing a catalyst component to form a wet layer containing a catalyst component on the surface of the molded body; (b) The molded body on which the above wet layer is formed is treated with LiOH, NaOH, KOH, NH 4 OH and (NH 2 ) 2 A step of fixing a wet layer on the surface of a molded body by immersing the molded body in a fixing solution in which one or more compounds selected from the group consisting of CO are dissolved; and (c) a step of forming a coating layer of a catalyst component on the surface of a molded body by heat-treating a molded body having a wet layer fixed on the surface; A molded catalyst having a coating layer of a catalyst component formed on the surface of a molded body, characterized in that it is manufactured including the step of forming a coating layer of a catalyst component on the surface of the molded body.

12. In paragraph 11, (d) a step of loading a catalytically active material onto the coating layer of the molded body; and (e) A molded catalyst characterized in that a coating layer of a catalytic component is formed on the surface of the molded body, characterized in that the molded body is manufactured by further including a step of drying and / or calcining the molded body loaded with the catalytically active substance to manufacture the molded body loaded with the catalytically active substance.

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