KR20230168573A - Zeolite-based catalyst for manufacturing acrylic acid and method for manufacturing same - Google Patents

Abstract

This application provides a zeolite-based catalyst for producing acrylic acid and a method for producing the same.

Description

Zeolite-based catalyst for producing acrylic acid and method for producing the same {ZEOLITE-BASED CATALYST FOR MANUFACTURING ACRYLIC ACID AND METHOD FOR MANUFACTURING SAME}

This application claims the benefit of the filing date of Korean Patent Application No. 10-2022-0068916 filed with the Korea Intellectual Property Office on June 7, 2022, the entire contents of which are included in this specification.

This application relates to a zeolite-based catalyst for producing acrylic acid and a method for producing the same.

Due to the rise in international oil prices and regulations on carbon emissions due to global climate agreements, the production of high value-added chemical products from sustainable and reusable biomass resources is receiving great attention by moving away from chemical products from existing petroleum fuels.

In particular, lactic acid produced from biomass-based sugar is receiving great attention as a material that can replace propylene, a raw material for acrylic acid or polyacrylic acid, which is currently widely used in paints, adhesives, etc. In the case of lactic acid, the carboxyl group (-COOH) and the hydroxyl group (-OH) are adjacent to each other in the chemical structure, so when the hydroxyl group is selectively removed using a solid acid catalyst, it has the same composition and physical properties as current petroleum-derived acrylic acid. It is possible to convert it into a compound. However, it is very difficult to produce acrylic acid with high selectivity because acetaldehyde is produced rapidly through decarboxylation, which occurs as a competitive reaction. In addition, a coking reaction occurs due to the polymerization of lactic acid and acrylic acid that occurs during the reaction, causing carbon deposition, and the catalyst activity easily decreases during long-term reaction.

According to a recent report, a calcium phosphate-silica composite oxide catalyst with a mixture of acid and base points of appropriate strength (Korean Patent Publication No. 10-2011-0022235) and a zeolite with exchanged alkali ions (KBr-ZSM-5 or KBr-Beta zeolite) has been reported. However, these catalysts have high short-term selectivity, but in order to suppress side reactions, lactic acid esters in which the carboxyl group of lactic acid is protected from decarboxylation are used as reactants, or when used for a long time, the activity of the catalyst is lowered and the final acrylic acid yield is low, resulting in low efficiency of the synthesis process. However, there is a problem of low economic feasibility.

In particular, previously reported zeolite-based catalysts with excellent selectivity use bromine precursor, a hazardous chemical, as a catalyst synthesis material, or use a complex ion exchange process (NaOH treatment) in hydrothermally synthesized zeolite material and introduce a phosphate group as a catalytic active material. The disadvantage is that the synthesis method is difficult and the catalyst durability is low.

Republic of Korea Patent Publication No. 10-2011-0022235

The present application seeks to provide a zeolite-based catalyst for producing acrylic acid and a method for producing the same.

The exemplary embodiment of the present application is a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ ,

The zeolite-based catalyst for producing acrylic acid contains impurities,

The impurity provides a Na ⁺ -substituted zeolite-based catalyst for producing acrylic acid, wherein the impurity contains more than 0 parts by weight and less than or equal to 3 parts by weight based on 100 parts by weight of the zeolite-based catalyst for producing acrylic acid.

In addition, another embodiment of this application is,

Preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor;

Aging the solution at a temperature of 3°C to 30°C for 8 to 23 hours;

After maturing the solution, performing hydrothermal synthesis to produce a product;

After filtering the product, washing the filtered product with a solvent; and

A method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid is provided, including the step of drying and calcining the product after washing with the solvent.

In addition, another embodiment of the present application includes the step of producing acrylic acid by dehydrating a lactic acid compound in the presence of a catalyst for producing acrylic acid,

The catalyst for producing acrylic acid provides a method for producing acrylic acid, wherein the Na ⁺ is a zeolite-based catalyst for producing acrylic acid substituted.

The zeolite-based catalyst for producing acrylic acid according to an exemplary embodiment of the present application is manufactured through a hydrothermal synthesis process using Na ⁺ ions, and does not use expensive organic structural derivatives such as conventional TPA (tetrapropylammonium), so it is a zeolite-based catalyst. It can reduce manufacturing costs and has the feature of preventing contamination due to washing water containing unreacted organisms.

In addition, the zeolite-based catalyst for producing acrylic acid according to an exemplary embodiment of the present application is directly manufactured in the form of a Na ⁺ substituted zeolite-based catalyst and does not require a separate conventional ion exchange process, thereby simplifying the manufacturing process of the zeolite-based catalyst. You can.

In addition, when the zeolite-based catalyst for acrylic acid production according to an exemplary embodiment of the present application is applied to an acrylic acid production process using a lactic acid compound, it has the feature of showing high acrylic acid selectivity.

Figures 1 and 5 show a scanning electron microscope (SEM) image of the zeolite-based catalyst of Example 1 as an exemplary embodiment of the present application.
Figure 2 is a diagram showing a scanning electron microscope (SEM) image of the zeolite-based catalyst of Example 6, as an exemplary embodiment of the present application.
Figure 3 is a diagram showing the results of XRD (X-Ray Diffraction) analysis of the zeolite-based catalyst of Example 1, as an exemplary embodiment of the present application.
Figure 4 is a diagram showing the results of XRD (X-Ray Diffraction) analysis of the zeolite-based catalyst of Example 2 as an exemplary embodiment of the present application.
Figure 6 is a diagram showing the catalyst conversion rate and acrylic acid selectivity according to the results of manufacturing acrylic acid using the zeolite-based catalyst of Example 4, Comparative Example 7, and Examples 7 to 11.
Figure 7 is a diagram showing the results of activity measured at 4-hour intervals for a total of 16 hours by the initial wet impregnation (IWI) method of Comparative Example 9.
Figure 8 is a diagram showing the results of XRD (X-Ray Diffraction) analysis of the zeolite-based catalyst of Example 1 and Comparative Example 10.
Figure 9 is a diagram showing the results of XRD (X-Ray Diffraction) analysis of the zeolite-based catalysts of Comparative Examples 11 to 14.

Hereinafter, this application will be described in more detail.

In this specification, when a member is said to be located “on” another member, this includes not only the case where a member is in contact with another member, but also the case where another member exists between the two members.

In this specification, when a part “includes” a certain component, this means that it may further include other components rather than excluding other components unless specifically stated to the contrary.

In this specification, “p to q” means “p to q or less.”

As described above, if the hydroxyl group of bio-derived lactic acid is removed through a dehydration reaction, it can be converted into acrylic acid monomer for the synthesis of super absorbent polymer (SAP). This acrylic acid has the advantage of contributing to carbon neutrality by replacing acrylic acid in petroleum-derived propylene with a bio-derived monomer. However, during the dehydration reaction of the hydroxyl group of lactic acid, acetaldehyde is produced quickly through decarbonylation, which occurs as a competitive reaction, making it difficult to control reaction selectivity, and coking reaction due to polymerization of lactic acid and acrylic acid that may occur during the reaction. There is a problem that the catalyst is severely deactivated. To date, various solid acid catalysts based on complex metal oxides have been developed, but there are few catalysts that have high catalytic selectivity and stability while maintaining high catalytic activity under high space velocity conditions. Accordingly, the present application seeks to provide a zeolite-based catalyst for producing acrylic acid that simultaneously satisfies the above-mentioned conditions such as selectivity, stability, and activity, and a method for producing the same.

Zeolite is a general term for crystalline aluminosilicates, and its chemical composition has the general formula M _2/n O·Al ₂ O ₃ ·xSiO ₂ ·yH ₂ O (n is the valency of the cation M, x is a number of 2 or more, y can be expressed as the amount of adsorbed moisture. The skeleton of zeolite consists of the constituent elements Si and Al having a four-coordinate structure and being connected through oxygen atoms, and the crystal structure and pore structure are different depending on the connection type.

The structure of zeolite is classified by a three-letter structural code defined by the International Zeolite Association (IZA), and is disclosed in books published by IZA and on the Web. The types of zeolite structures are increasing every year, reaching 176 types as of 2007. Among them, there are about 10 types of zeolites that are industrially produced.

Hereinafter, a method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid of the present application will first be described.

<Na ⁺ Method for producing zeolite-based catalyst for producing substituted acrylic acid>

A method for producing a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ according to an exemplary embodiment of the present application includes preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor; Aging the solution at a temperature of 3°C to 30°C for 8 to 23 hours; After maturing the solution, performing hydrothermal synthesis to produce a product; After filtering the product, washing the filtered product with a solvent; and drying and calcining the product after washing with the solvent. That is, in this specification, the Na ⁺ -substituted zeolite-based catalyst for producing acrylic acid refers to a Na ⁺ -substituted zeolite-based catalyst used in the production of acrylic acid.

When using the method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to the present application, the manufacturing cost of the zeolite-based catalyst can be reduced because expensive organic structure derivatives are not used, and the washing water containing unreacted organisms can be reduced. It has the feature of preventing contamination. In addition, since the separate ion exchange process required in the conventional manufacturing method is unnecessary, the manufacturing process of the zeolite-based catalyst can be simplified. In addition, by maturing the solution under the above conditions, the prepared catalyst has excellent catalytic activity.

In one embodiment of the present application, after filtering the product, the step of washing the filtered product with a solvent means washing the product with a solvent within a range where the pH of the filtrate maintains basicity. You can.

That is, the method for producing a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ according to an exemplary embodiment of the present application includes the steps of preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor; Aging the solution at a temperature of 3°C to 30°C for 8 to 23 hours; After maturing the solution, performing hydrothermal synthesis to produce a product; After filtering the product, washing the filtered product with a solvent within a range where the pH of the filtrate remains basic; and drying and calcining the product after washing with the solvent.

In an exemplary embodiment of the present application, after filtering the product, the step of washing the filtered product with a solvent means washing the product with a solvent within a range where the pH of the filtrate is maintained at neutral; , after washing the product with a solvent within a range where the pH of the filtrate remains neutral, the step of dry impregnating the product washed with the solvent with a Na precursor may be further included.

That is, in one embodiment of the present application, after filtering the product, the step of washing the filtered product with a solvent is to wash the product with a solvent within a range where the pH of the filtrate is maintained at neutral. refers to a step of washing the product with a solvent within a range where the pH of the filtrate remains neutral, and before drying and calcining the product washed with the solvent. A step of dry impregnation with Na precursor may be further included.

In other words, the method for producing a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ according to an exemplary embodiment of the present application includes the steps of preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor; Aging the solution at a temperature of 3°C to 30°C for 8 to 23 hours; After maturing the solution, performing hydrothermal synthesis to produce a product; After filtering the product, washing the filtered product with a solvent within a range where the pH of the filtrate remains neutral; Dry impregnating the product washed with the solvent with a Na precursor; and drying and calcining the product dry-impregnated with the Na precursor.

In an exemplary embodiment of the present application, the step of dry impregnating the product washed with the solvent with a Na precursor includes the steps of supporting the product washed with the solvent in a solution containing the Na precursor; And it may include drying the supported product.

In an exemplary embodiment of the present application, the solvent may have a pH of 3 to 9, preferably, a pH of 5.5 to 7.5 at 25°C.

In an exemplary embodiment of the present application, the solvent may be alcohol, water (tap water), an aqueous alkali metal solution, or purified water, and preferably purified water. The alkali metal may be Na, K, Rb, Cs, etc.

In an exemplary embodiment of the present application, the Na precursor may be one or more selected from the group consisting of sodium salts bonded to the conjugated conjugate base anion of an inorganic acid or organic acid.

The Na precursor is a sodium salt combined with the conjugate base anion of an inorganic acid or organic acid, more specifically, Na ₂ O, NaF, NaCl, NaBr, NaI, Na ₂ SO ₄ , Na ₂ S, Na ₂ CO ₃ , NaNO ₃ , NaOH , NaHCO ₃ and Na ₂ HPO ₄ .

That is, in an exemplary embodiment of the present application, the Na precursor is Na ₂ O, NaF, NaCl, NaBr, NaI, Na ₂ SO ₄ , Na ₂ S, Na ₂ CO ₃ , NaNO ₃ , NaOH, NaHCO ₃ and Na ₂ HPO ₄ It may be one or more selected from the group consisting of.

Additionally, in this specification, a method commonly used in the field may be used as a method of dry impregnating the Na precursor.

In this specification, “pH” is a value indicating the degree of acidity or alkalinity of water, and specifically refers to the index of hydrogen ion concentration. Based on 25°C, a pH value of 7 is neutral, and a pH value of less than 7 is neutral. In this case, it is defined as acidic, and in cases where the pH value is greater than 7, it is defined as basic.

As used herein, “filtrate” refers to a liquid obtained by filtering the product produced through hydrothermal synthesis, and the filtrate includes the product synthesized through hydrothermal synthesis of the present application.

That is, in this specification, washing the product with a solvent within the range where the pH of the filtrate is maintained at "neutral" or "basic" means filtering the product produced through hydrothermal synthesis and then washing the product with a solvent. This means that a solvent is used within a range that can maintain the pH of the filtrate at "neutral" or "basic" during the washing process.

A method for producing a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ according to an exemplary embodiment of the present application includes preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor.

The Si/Al molar ratio of the solution containing the Na ⁺ -containing inorganic alkali salt, silica precursor, and alumina precursor may be 15 to 50, more preferably 20 to 35, and 20 is most preferable.

If the Si/Al molar ratio is less than 15, it is difficult to synthesize a zeolite-based catalyst through a process that does not use expensive organic structure derivatives such as TPA (tetrapropylammonium), and if the Si/Al molar ratio is more than 50, Al Because the content is small, it is difficult to synthesize a zeolite-based catalyst, and the possibility of quartz impurities being formed to the extent of interfering with the performance of the catalyst increases, so it is necessary to use a solution containing the inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor. The Si/Al molar ratio is preferably 15 to 50.

The step of preparing a solution containing an inorganic alkali salt, a silica precursor, and an alumina precursor includes preparing a first solution containing an inorganic alkali salt containing Na ⁺ and a silica precursor; Preparing a second solution containing an alumina precursor; And it may include mixing the first solution and the second solution. When preparing a solution by mixing the inorganic alkali salt containing Na ⁺ , the silica precursor, and the alumina precursor at the same time, the inorganic alkali salt containing Na ⁺ , the silica precursor, and the alumina precursor are not uniformly mixed due to gelation, resulting in the desired catalyst. This is undesirable because the structure may not be formed. Therefore, in an exemplary embodiment of the present application, it is more preferable to prepare the first solution containing the inorganic alkali salt containing Na ⁺ and the silica precursor and the second solution containing the alumina precursor separately and then mix them. .

The silica precursor may include one or more selected from tetraethylorthosilicate, silica gel, colloidal silica, sodium silicate, natural silica, fumed silica, and synthetic silica, but is not limited thereto.

The alumina precursor may include, but is not limited to, one or more selected from aluminum alkoxide, sodium aluminate, aluminum sulfate, boehmite, and aluminum hydroxide. To better induce Si-O-Al bonding kinetically, it is more preferable that the alumina precursor contains sodium aluminate.

The inorganic alkali salt containing Na ⁺ may play a role in promoting crystallization of zeolite. The inorganic alkali salt containing Na ⁺ may be sodium hydroxide, but is not limited thereto.

The method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to an exemplary embodiment of the present application includes the step of aging the solution and then performing hydrothermal synthesis.

More specifically, the method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to an exemplary embodiment of the present application includes the steps of aging the solution at a temperature of 3°C to 30°C for 8 to 23 hours; And after aging the solution, it includes performing hydrothermal synthesis to produce a product.

In an exemplary embodiment of the present application, the step of maturing the solution may be performed at a temperature of 3°C to 30°C for 8 hours to 23 hours, and at a temperature of 3°C to 30°C for 10 hours to 15 hours. It can be performed at a temperature of 4°C to 25°C for 10 to 12 hours. When the solution is aged under the above temperature and time conditions, the mixed solution can form crystal nuclei, and the crystallization rate can be increased in the subsequent hydrothermal synthesis step to increase crystallinity and purity. If hydrothermal synthesis is performed directly without performing the solution maturation step, it is not preferable because impurity phases such as keatite or quartz may be generated to the extent of interfering with the performance of the catalyst. In addition, if the temperature conditions are exceeded, the solution may not be matured, and if the time conditions are exceeded, amorphous silica and quartz, which are impurities, may be generated to the extent of interfering with the activity of the catalyst.

In an exemplary embodiment of the present application, the hydrothermal synthesis may be performed under static conditions without a separate stirring process, or the hydrothermal synthesis may be performed together with a stirring process. In particular, it is more preferable to perform hydrothermal synthesis while stirring the aged solution because the crystallization rate increases and the time required for hydrothermal synthesis can be reduced.

The hydrothermal synthesis may be performed at a temperature of 165°C to 195°C, and may be performed at a temperature of 175°C to 185°C. When the above temperature conditions are met, the purity of the Na ⁺ -substituted zeolite catalyst can be improved. Additionally, the hydrothermal synthesis may be performed for 20 to 28 hours, or may be performed for 22 to 26 hours. If the hydrothermal synthesis time is less than 20 hours, crystals of the Na ⁺ -substituted zeolite catalyst cannot be sufficiently formed. In addition, if the hydrothermal synthesis time exceeds 28 hours, it is not preferable because excessive reaction may cause the formation of a quartz phase to the extent of interfering with the performance of the catalyst.

The method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to an exemplary embodiment of the present application includes the steps of filtering the product and then washing the product with a solvent within a range where the pH of the filtrate maintains basicity. Includes. Here, the product refers to a material manufactured through the hydrothermal synthesis step.

According to an exemplary embodiment of the present application, a small amount of Na can be left on the surface of the zeolite-based catalyst by washing the product with a solvent within a range where the pH of the filtrate maintains basicity. In particular, the small amount of unremoved Na can act as a base point on the surface of the zeolite-based catalyst, thereby improving the selectivity of acrylic acid during the production process of acrylic acid using the zeolite-based catalyst.

When the product is washed with a solvent until the pH of the filtrate becomes neutral, Na residues that may act as base points are completely removed, and acrylic acid selectivity may rapidly decrease. In addition, if there is no step of washing the product with a solvent, excess Na remains on the catalyst surface, and the acid/base point distribution within the catalyst collapses due to excessive base points. In this case, 2,3-pentanedione, a side reaction, may be generated rather than acrylic acid, so acrylic acid selectivity may be reduced.

That is, when the product is washed with a solvent within a range where the pH of the filtrate maintains basicity, the selectivity of acrylic acid can be improved during the production process of acrylic acid using a zeolite-based catalyst without any additional steps.

A method for producing a zeolite-based catalyst for producing acrylic acid according to an exemplary embodiment of the present application includes the steps of filtering the product and washing the product with a solvent within a range where the pH of the filtrate is maintained at neutral; And after washing the product with a solvent within a range where the pH maintains the neutrality of the filtrate, the step may include dry impregnating the product washed with the solvent with a Na precursor. Here too, the product refers to a material manufactured through the hydrothermal synthesis step.

When washing with a solvent until the pH of the filtrate becomes neutral, the safety and efficiency of the washing process can be increased. However, as described above, Na residues that can act as base points are completely removed, and the acrylic acid selectivity rapidly decreases. There are problems that can be reduced. However, this problem can be solved through dry impregnation of the Na precursor into the product. In addition, when the product is dry impregnated with a Na precursor, it is easier to control the ratio of Na ₂ O in the catalyst after the calcination step, which has the advantage of making it easier to manufacture a catalyst with desired performance. The problems that arise when there is no washing step with a solvent are the same as described above.

The method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to an exemplary embodiment of the present application includes the steps of drying and calcining the product after washing with the solvent. That is, it includes the step of drying and calcining the product after washing with the above-described solvent to prepare a Na ⁺ -substituted zeolite-based catalyst. More specifically, after filtering the product, washing with a solvent within a range where the pH of the filtrate maintains basicity; or filtering the product and then washing it with a solvent within a range where the pH of the filtrate remains neutral; and dry impregnating the product with a Na precursor followed by drying and firing.

That is, after filtering the product, the product is washed with a solvent within a range where the pH of the filtrate remains basic, followed by drying and calcining, or after filtering the product, the pH of the filtrate is neutral. washing the product with a solvent within the range maintained; and dry impregnating the product with a Na precursor followed by drying and firing.

In an exemplary embodiment of the present application, the drying and firing may use methods known in the art. For example, the drying may be performed at a temperature of 50°C to 150°C for 1 hour to 48 hours, and may be performed at a temperature of 60°C to 100°C for 5 hours to 36 hours, but is not limited thereto. In addition, the firing may be performed in an air atmosphere at a temperature of 300°C to 1,000°C for 1 hour to 10 hours, and may be performed in an air atmosphere at a temperature of 400°C to 600°C for 1.5 hours to 8 hours. It is not limited to this.

Conventionally, when producing a zeolite-based catalyst (ZSM-5) substituted with cations (Na ^+, etc.), an organic structural derivative such as TPA was essentially used to induce the crystal structure of ZSM-5, and after producing ZSM-5, the cation (Na ⁺ etc.) exchange process was essential, but according to an exemplary embodiment of the present application, Na ⁺ substituted zeolite-based catalyst was directly synthesized without using a separate organic structure derivative such as TPA, etc., without a separate ion exchange process. can do. In particular, according to an exemplary embodiment of the present application, Na + of the zeolite-based catalyst may be introduced from an inorganic alkali salt, an alumina precursor, etc. Therefore, in an exemplary embodiment of the present application, it is more preferable that the inorganic alkali salt is sodium hydroxide or the alumina precursor is sodium aluminate.

In addition, another embodiment of the present application provides a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid, which is prepared by the above production method.

Hereinafter, the zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid of the present application will first be described.

<Na ⁺ Zeolite-based catalyst for producing substituted acrylic acid>

An exemplary embodiment of the present application is a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ , wherein the zeolite-based catalyst for producing acrylic acid contains impurities, and the impurities are in an amount exceeding 0 parts by weight and 3 parts by weight based on 100 parts by weight of the zeolite-based catalyst for producing acrylic acid. A zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid is provided, which includes the following:

The zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to the present application may be manufactured by the method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to the present application.

As described above, the zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid produced by the above-mentioned manufacturing method, which reduces the manufacturing cost of the zeolite-based catalyst and can prevent contamination due to washing water, is manufactured by a simpler manufacturing process than the existing process.

In addition, compared to the catalyst prepared by the ion exchange process, the Na ⁺ -substituted zeolite-based catalyst for producing acrylic acid according to the present application may generate some impurities such as quartz, as shown in the part indicated by a in FIG. 5, but the catalyst It does not occur to the extent that it interferes with performance. Rather, as the content of impurities such as some quartz satisfies the above-mentioned range, the problem of lowering the activity of catalysts due to the presence of unexchanged protons in the cation exchange process does not occur as in the existing method, and the activity of the catalyst increases. It has excellent effects.

In an exemplary embodiment of the present application, the impurity is more than 0 parts by weight and 3 parts by weight or less, preferably more than 0 parts by weight and less than 2 parts by weight, more preferably 0 parts by weight, based on 100 parts by weight of the zeolite catalyst for producing acrylic acid. It may contain more than 1 part by weight, more preferably more than 0 part by weight and less than 0.02 parts by weight. In other words, when the cation exchange process is performed as in the existing method, impurities on quartz may occur that cannot be confirmed, but in the catalyst of the present application, impurities on quartz exist within the above content range and do not interfere with the activity of the catalyst. Rather, the activity of the catalyst can be increased by omitting the cation exchange process.

Additionally, due to the presence of impurities in the quartz phase, it can be confirmed that the catalyst was manufactured by the manufacturing method according to the present application.

In an exemplary embodiment of the present application, the Si/Al molar ratio of the zeolite-based catalyst for producing acrylic acid may be 15 to 50, more preferably 20 to 35, and most preferably 20. The Si/Al molar ratio of the zeolite-based catalyst for producing acrylic acid may affect the acid site concentration of the zeolite-based catalyst. More specifically, as the Si/Al molar ratio of the zeolite-based catalyst decreases, the Al content increases and the Na content for charge balance increases, so the acid sites of the zeolite-based catalyst may increase. At this time, the high acid site concentration of the zeolite-based catalyst can increase catalyst activity and selectivity. However, if the Si/Al molar ratio of the zeolite-based catalyst is excessively reduced, synthesis of the zeolite-based catalyst may not be possible, so it is necessary to appropriately adjust the Si/Al molar ratio.

If the Si/Al molar ratio of the zeolite-based catalyst for producing acrylic acid is less than 15, it may be difficult to synthesize the zeolite-based catalyst through a process that does not use expensive organic structural derivatives such as TPA (tetrapropylammonium). In addition, when the Si/Al molar ratio of the zeolite-based catalyst for acrylic acid production exceeds 50, the synthesis of the zeolite-based catalyst may be difficult due to the relatively low Al content, and quartz impurities are formed to the extent of interfering with the performance of the catalyst. It is undesirable because it can happen.

In an exemplary embodiment of the present application, the Na/Al molar ratio of the zeolite-based catalyst for producing acrylic acid may be 1.1 to 2.5, 1.2 to 2.5, more preferably 1.2 to 1.5. When the zeolite-based catalyst is neutral, Na exists only in the form of an extraframework cation for the charge balance of the zeolite structure, so the theoretical molar ratio of Na/Al is 1. However, according to an exemplary embodiment of the present application, during the manufacturing process of the zeolite-based catalyst for producing acrylic acid, the zeolite-based catalyst can be adjusted to be basic by washing with a solvent within the range where the pH of the filtrate maintains basicity. Accordingly, the zeolite-based catalyst can be adjusted to basicity. Zeolite-based catalysts can be manufactured so that additional Na is present in the catalyst in addition to Na for Al charge balancing. The additional Na may be converted to sodium oxide (NaOx) during the zeolite-based catalyst manufacturing process and may exist on the catalyst surface, which may act as an additional base point and play a role in improving reaction selectivity.

If the Na/Al molar ratio of the zeolite-based catalyst for producing acrylic acid is less than 1.1, it may be difficult to form additional base points on the surface of the catalyst. In addition, when the Na/Al molar ratio of the zeolite-based catalyst for producing acrylic acid exceeds 2.5, the Na content becomes excessively high, causing a problem of clogging the pores in the catalyst, or changing the acid/base point ratio of the catalyst, which may actually increase the catalyst's activity. This is not advisable as it may fall.

In an exemplary embodiment of the present application, the crystal size of the zeolite-based catalyst for producing acrylic acid may be 10 nm to 3,000 nm, 10 nm to 900 nm, and 900 nm to 3,000 nm. More specifically, the zeolite-based catalyst for producing acrylic acid may be in the form of clusters of crystals with a size of 10 nm to 900 nm, crystals with a size of 900 nm to 3,000 nm, etc. According to an exemplary embodiment of the present application, a catalyst can be manufactured with relatively small-sized crystals, and thus the reaction activity and selectivity can be increased by enhancing the molecular diffusion rate.

In an exemplary embodiment of the present application, the zeolite-based catalyst for producing acrylic acid may be Na ⁺ substituted MFI zeolite, Na ⁺ substituted Beta zeolite, or Na ⁺ substituted Y zeolite, more preferably Na ⁺ is a substituted MFI zeolite. In the present application, the Na ⁺ -substituted MFI zeolite may be described as Na ⁺ -substituted ZSM-5.

The zeolite-based catalyst for producing acrylic acid of the present application includes Na ₂ O on the surface of the zeolite-based catalyst for producing acrylic acid, and the Na ₂ O may act as an active site of the catalyst.

Whether the activity of the zeolite-based catalyst for producing acrylic acid is due to Na ₂ O can be confirmed by checking the Na ₂ O remaining on the surface of the catalyst at pH = 7.

In an exemplary embodiment of the present application, the Na ₂ O is added to the surface of the zeolite-based catalyst for producing acrylic acid in an amount of 0.01 parts by weight to 3 parts by weight, preferably 1 part by weight to 2 parts by weight, based on 100 parts by weight of the zeolite-based catalyst for producing acrylic acid. parts, more preferably 1.5 to 2 parts by weight. When the above content is satisfied, the acrylic acid selectivity of the catalyst is more excellent.

In an exemplary embodiment of the present application, the Na ₂ O is generated in the process of calcining the Na precursor, and the Na precursor may be one or more selected from the group consisting of NaNO _3, NaOH, NaHCO ₃ and Na ₂ HPO ₄ However, it is not limited to this.

In addition, another embodiment of the present application includes the step of producing acrylic acid by dehydrating a lactic acid compound in the presence of a catalyst for producing acrylic acid, wherein the catalyst for producing acrylic acid is a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ A method for producing acrylic acid is provided.

The method for producing acrylic acid according to an exemplary embodiment of the present application may use a method known in the art, except for using the zeolite-based catalyst for producing acrylic acid of the present application described above.

For example, the dehydration reaction of the lactic acid compound may use a continuous reaction or a batch reaction using a fixed bed reactor. In the reaction method using the fixed reactor, the product can be continuously produced by filling the fixed reactor with the zeolite-based catalyst for producing acrylic acid and continuously supplying the lactic acid compound to the reactor for reaction.

In addition, the lactic acid compound may include a material having both a hydroxyl group (-OH) and a carboxyl group (-COOH), and may include at least one selected from L-form lactic acid compounds and D-form lactic acid compounds. You can.

Additionally, the dehydration reaction of the lactic acid compound can be performed at a temperature of 200°C to 500°C, preferably 250°C to 380°C and a pressure of normal pressure to 5 bar. In addition, the liquid hourly space velocity (LHSV) of the lactic acid compound may be 0.05 hr ^-1 to 1.0 hr ^-1 , preferably 0.10 hr ^-1 to 0.80 hr ^-1 , but is not limited thereto.

Additionally, the dehydration reaction of the lactic acid compound may be performed for 1 hour to 32 hours, and may be performed for 2 hours to 28 hours, but is not limited thereto.

Hereinafter, in order to explain the present application in detail, examples will be given in detail. However, the embodiments according to the present application may be modified into various other forms, and the scope of the present application is not to be construed as being limited to the embodiments described in detail below. The embodiments of the present application are provided to more completely explain the present application to those with average knowledge in the art.

<Example>

Lactic acid solution (in water 85 wt%), LUDOX® AS-40 Colloidal silica (40 wt% suspension in H ₂ O), sodium hydroxide (reagent grade 98%, ≥ pellets - anhydrous), TPAOH (tetrapropylammonium hydroxide, 25 wt%) ), NaOH, NaNO ₃ , KNO ₃ , KF, KCl, KBr, and KI were purchased through Sigma Aldrich. The sodium aluminate reagent was purchased and used through Daejeong Chemical.

<Example 1>

First, a first solution was prepared by adding colloidal silica to an aqueous solution of sodium hydroxide (half of total distilled water) with the Si/Al molar ratio set to 25 and stirring for 3 hours. A second solution was prepared by adding sodium aluminate to distilled water (half of the total distilled water) and stirring for 3 hours. The second solution was slowly poured into the first solution and stirred for 3 hours. Afterwards, the mixed solution was aged for 12 hours at a temperature of 4°C to 25°C. Finally, hydrothermal synthesis was performed for 24 hours in a hydrothermal synthesis machine at rest.

Afterwards, the catalyst was vacuum filtered, washed with purified water until the pH of the filtrate was 9 to 10, dried for a day, and then calcined at 550°C for 4 hours to prepare the catalyst.

The finally prepared catalyst was named “Na_ZSM-5_25_syn”.

<Example 2>

The same procedure as Example 1 was performed, except that the Si/Al molar ratio was adjusted to 35. The finally prepared catalyst was named “Na_ZSM-5_35_syn”.

<Example 3>

The same procedure as Example 1 was performed, except that the Si/Al molar ratio was adjusted to 50. The finally prepared catalyst was named “Na_ZSM-5_50_syn”.

<Example 4>

The same procedure as Example 1 was performed, except that the Si/Al molar ratio was adjusted to 20. The finally prepared catalyst was named “Na_ZSM-5_20_syn”.

<Example 5>

The same procedure as Example 1 was performed, except that the Si/Al molar ratio was adjusted to 15. The finally prepared catalyst was named “Na_ZSM-5_15_syn”.

<Example 6>

The hydrothermal synthesis was performed in the same manner as Example 4, except that instead of performing it in a stationary state, it was performed while stirring at a speed of 100 rpm. The finally prepared catalyst was named “Na-ZMS-5_20_Stiring”.

<Comparative Example 1>

Hydrogen foam ZSM-5 was manufactured by firing ammonium foam ZSM-5 (Si/Al molar ratio: 15) purchased through Zeolyst® at 550°C for 4 hours in an air atmosphere. Afterwards, it was placed in a 0.5M NaNO ₃ aqueous solution purchased from Sigma Aldrich and exchanged four times for 1 hour at 80°C. The finally prepared catalyst was named “Na_ZSM-5_15_com”.

<Comparative Example 2>

A catalyst was prepared by subjecting “Na_ZSM-5_15_com” of Comparative Example 1 to ion exchange with a 0.5M KF aqueous solution at 80°C for 1 hour and then calcining it at 550°C for 4 hours in an air atmosphere. The finally prepared catalyst was named “KF_ZSM-5_15_com”.

<Comparative Example 3>

A catalyst was prepared by subjecting “Na_ZSM-5_15_com” of Comparative Example 1 to ion exchange with a 0.5M KCl aqueous solution at 80°C for 1 hour and then calcining it at 550°C for 4 hours in an air atmosphere. The finally prepared catalyst was named “KCl_ZSM-5_15_com”.

<Comparative Example 4>

A catalyst was prepared by performing ion exchange on “Na_ZSM-5_15_com” of Comparative Example 1 with a 0.5M KI aqueous solution at 80°C for 1 hour and then calcining it at 550°C for 4 hours in an air atmosphere. The finally prepared catalyst was named “KI_ZSM-5_15_com”.

<Comparative Example 5>

A catalyst was prepared by subjecting “Na_ZSM-5_15_com” of Comparative Example 1 to ion exchange with an aqueous KNO ₃ solution at 80°C for 1 hour and then calcining it at 550°C for 4 hours in an air atmosphere. The finally prepared catalyst was named “KNO ₃ _ZSM-5_15_com”.

<Comparative Example 6>

In order to prepare ZSM-5 with a structural derivative, TPAOH was additionally added to the mixed solution of the first and second solutions, and after calcination, it was placed in a 0.5M NaNO ₃ aqueous solution and exchanged four times for 1 hour at 80°C. Except for the process, the same procedure as Example 4 was performed. The finally prepared catalyst was named “Na_ZSM-5_20_TPAOH”.

<Comparative Example 7>

The hydrothermally synthesized catalyst was vacuum filtered and then washed with purified water until the pH of the filtrate reached 7. The same procedure as Example 4 was performed. The finally prepared catalyst was named “Na-ZSM-5_20_neutral”.

<Comparative Example 8>

Hydrogen foam Beta was manufactured by firing ammonium foam Beta (Si/Al molar ratio: 12.5) purchased through Zeolyst® at 550°C for 4 hours in an air atmosphere. Afterwards, it was placed in a 0.5M NaNO ₃ aqueous solution purchased from Sigma Aldrich and exchanged four times for 1 hour at 80°C. The finally prepared catalyst was named “Na-Beta zeolite”.

<Example 7>

The above comparison, except that the hydrothermally synthesized catalyst was vacuum filtered, washed with purified water until the pH of the filtrate reached 7, and NaNO ₃ (0.5 wt%) was forcibly inserted into the catalyst pores through dry impregnation. The same procedure as Example 7 was performed. The finally prepared catalyst was named “Na-ZSM-5_20_neutral_0.5 wt%”.

<Example 8>

The above comparison, except that the hydrothermally synthesized catalyst was vacuum filtered, washed with purified water until the pH of the filtrate reached 7, and NaNO ₃ (1.0 wt%) was forcibly inserted into the catalyst pores through dry impregnation. The same procedure as Example 7 was performed. The finally prepared catalyst was named “Na-ZSM-5_20_neutral_1.0 wt%”.

<Example 9>

The hydrothermally synthesized catalyst was vacuum filtered, washed with purified water until the pH of the filtrate reached 7, and NaNO ₃ (2.0 wt%) was forcibly inserted into the catalyst pores through dry impregnation. The same procedure as Example 7 was performed. The finally prepared catalyst was named “Na-ZSM-5_20_neutral_2.0 wt%”.

<Example 10>

The above comparison, except that the hydrothermally synthesized catalyst was vacuum filtered, washed with purified water until the pH of the filtrate reached 7, and NaNO ₃ (3.0 wt%) was forcibly inserted into the catalyst pores through dry impregnation. The same procedure as Example 7 was performed. The finally prepared catalyst was named “Na-ZSM-5_20_neutral_3.0 wt%”.

<Example 11>

The hydrothermally synthesized catalyst was vacuum filtered, washed with purified water until the pH of the filtrate reached 7, and NaNO ₃ (5.0 wt%) was forcibly inserted into the catalyst pores through dry impregnation. The same procedure as Example 7 was performed. The finally prepared catalyst was named “Na-ZSM-5_20_neutral_5.0 wt%”.

<Comparative Example 9>

A catalyst was prepared by forcibly inserting NaNO ₃ (2.0 wt%) into the catalyst pores of “Na_ZSM-5_15_com” of Comparative Example 1 through dry impregnation and then calcining it at 550°C for 4 hours in an air atmosphere. The finally prepared catalyst was named “Na-ZSM-5_15_com_2.0 wt%”.

<Comparative Example 10>

The catalyst of Comparative Example 10 was prepared in the same manner as Example 1, except that the mixed solution was aged for 24 hours at a temperature of 4°C to 25°C.

The finally prepared catalyst was named “Na_ZSM-5_25_syn(aging, 24hr)”.

<Comparative Example 11>

After the aging process in Example 1, the catalyst of Comparative Example 11 was prepared in the same manner as Example 1, except that hydrothermal synthesis was performed for 12 hours in a stopped state in the hydrothermal synthesizer.

The finally prepared catalyst was named “Na_ZSM-5_25_syn (12hr)”.

<Comparative Example 12>

After the aging process in Example 1, the catalyst of Comparative Example 12 was prepared in the same manner as Example 1, except that hydrothermal synthesis was performed for 18 hours in a stopped state in the hydrothermal synthesizer.

The finally prepared catalyst was named “Na_ZSM-5_25_syn (18hr)”.

<Comparative Example 13>

After the aging process in Example 1, the catalyst of Comparative Example 13 was prepared in the same manner as Example 1, except that hydrothermal synthesis was performed for 30 hours in a stopped state in the hydrothermal synthesizer.

The finally prepared catalyst was named “Na_ZSM-5_25_syn (30hr)”.

<Comparative Example 14>

After the aging process in Example 1, the catalyst of Comparative Example 14 was prepared in the same manner as Example 1, except that hydrothermal synthesis was performed for 48 hours in a stopped state in the hydrothermal synthesizer.

The finally prepared catalyst was named “Na_ZSM-5_25_syn (48hr)”.

<Experimental Example 1> Analysis of structure and characteristics of zeolite-based catalyst

A scanning electron microscope (SEM) image of the zeolite-based catalyst of Example 1 is shown in FIG. 1, and a scanning electron microscope (SEM) image of the zeolite-based catalyst of Example 6 is shown in FIG. 2. shown in As shown in the results of Figures 1 and 2 below, it can be confirmed that the zeolite-based catalyst according to an exemplary embodiment of the present application is in the form of clusters of crystals with a size of 10 nm to 3,000 nm.

In addition, the XRD (X-Ray Diffraction) analysis results of the zeolite-based catalyst of Example 1 are shown in Figure 3, and the XRD (X-Ray Diffraction) analysis results of the zeolite-based catalyst of Example 2 are shown in Figure 4 It was. As shown in the results of Figures 3 and 4 below, it can be confirmed that the zeolite-based catalyst for producing acrylic acid according to an exemplary embodiment of the present application is a zeolite with a pure MFI crystal structure without any impurities.

<Experimental Example 2> Component analysis of zeolite catalyst

For the zeolite-based catalysts of Example 4, Comparative Example 7, Comparative Example 9, and Comparative Example 13, the content of Al and Na in the catalyst was measured by ICP-OES (inductively coupled plasma-optical emission), and the Na/Al molar ratio is shown in Table 1 below.

Na/Al (molar ratio) Example 4 1.36 Comparative Example 7 1.05 Example 7 1.09 Example 8 1.2 Example 9 2.04 Example 10 2.30 Example 11 2.45

As shown above, the zeolite-based catalyst according to an exemplary embodiment of the present application adjusts the zeolite-based catalyst to basicity during the purified water washing process or washes with purified water within the range where the pH of the filtrate remains neutral during the purified water washing process. , It can be confirmed that by dry impregnating the product with a Na precursor, a zeolite-based catalyst can be manufactured so that additional Na is present in the zeolite-based catalyst in addition to Na for Al charge balancing.

In addition, when the Na/Al molar ratio of the zeolite-based catalyst for producing acrylic acid exceeds 2.5, the Na content becomes excessively high, and as shown in the experimental results of the acrylic acid production process below, the acid point/base point ratio of the catalyst changes and the catalyst You can see that the activity is decreasing.

<Experimental Example 3> Preparation of acrylic acid

A quartz tube with an outer diameter of 1 cm in a down flow fixed bed reactor was filled with 0.8 g of the catalysts of each example and comparative example, and then flowed at 25 cc/h using N ₂ as a mobile phase gas. After raising the temperature of the quartz tube to 325°C, an aqueous lactic acid solution (10 wt%) was placed in the syringe of the syringe pump, supplied at LHSV 0.64h ^-1 , and reaction was performed for 16 hours. The product was collected in liquid form through a chiller and analyzed by GC.

The conversion rate of the aqueous lactic acid solution was calculated by Equation 1 below, and the selectivity of the product (acrylic acid) was calculated by Equation 2 below. Additionally, the yield of the product (acrylic acid) was calculated using Equation 3 below.

[Equation 1]

Conversion rate (%) = (number of moles of carbon in the reacted lactic acid compound) / (number of moles of carbon in the supplied lactic acid compound) Х 100

[Equation 2]

Selectivity (%) = (carbon moles of produced acrylic acid) / (carbon moles of reacted lactic acid compounds) Х 100

[Equation 3]

Yield (%) = Conversion rate (%) Х Selectivity (%) / 100

The analysis device and analysis conditions applied in this application are as follows.

1) Scanning Electrone Microscope (SEM)

Equipment used: GEMINI500

Analysis method: After loading the catalyst sample into a fixed cell, apply Pt coating to prevent damage to the electron beam, and then check by zooming in and out using an electron microscope.

2) XRD (X-Ray Diffraction)

Equipment used: X'Pert-3 System (PHILIPS)

Analysis method: After loading the catalyst sample into the fixed cell, the analysis angle is measured at 5°~60°, time per step is 30, and scan step size is 0.02.

3) ICP-OES (inductively coupled plasma-optical emission)

Equipment used: Jobin Yvon Ultima 2

Analysis method: Completely dissolve the catalyst sample in a high-concentration acid solution to form a solution, then dilute it and quantify the amount of elements using ICP equipment.

The results were as shown in Table 2 below.

catalyst Acrylic acid selectivity (%) transference number(%) Example 1 72 72 Example 2 65 61 Example 3 63 54 Example 4 81 79 Example 5 57 57 Example 6 60 60 Comparative Example 1 12 11 Comparative Example 2 33 31 Comparative Example 3 19 17 Comparative Example 4 14 12 Comparative Example 5 39 35 Comparative Example 6 13 13 Comparative Example 7 24 24 Comparative Example 8 10 10 Example 7 62 60 Example 8 61 59 Example 9 71 70 Example 10 57 52 Example 11 54 48 Comparative Example 9 52 52 Comparative Example 10 44 40 Comparative Example 11 28 27 Comparative Example 12 32 29 Comparative Example 13 38 35 Comparative Example 14 30 26

As shown in the above results, it can be confirmed that the examples according to the exemplary embodiment of the present application exhibit significantly higher acrylic acid selectivity compared to the comparative examples. In the zeolite-based catalysts of the comparative example, the activity of the catalysts may be reduced due to the presence of unexchanged protons during the cation exchange process. However, in an example according to an exemplary embodiment of the present application, during the manufacturing process of the zeolite-based catalyst, the Na ⁺ -substituted zeolite-based catalyst is directly synthesized without using a separate organic structure derivative and without a separate ion exchange process, or by dry impregnation. Since the Na precursor is injected through the sintering process, protons do not exist even after the calcination process, and the activity of the catalyst can be increased.

Additionally, when comparing Example 4 and Comparative Example 6, it can be seen that the zeolite-based catalyst synthesized by adding an organic structure derivative as in Comparative Example 6 does not show significant activity in the dehydration reaction of lactic acid compounds.

In addition, when comparing Example 4 and Comparative Example 7, when the zeolite-based catalyst shows basicity as in Example 4, Na ₂ O remains on the surface of the catalyst, and this Na ₂ O acts as an active site for the catalyst. It can be confirmed that the performance of the catalyst can be improved.

Additionally, when comparing Examples 4 and 6, it can be seen that it is more preferable in terms of selectivity of acrylic acid to perform the hydrothermal synthesis of the zeolite-based catalyst production process under static conditions without a separate stirring process.

As shown above, the zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to an exemplary embodiment of the present application is manufactured by a hydrothermal synthesis process using Na ⁺ ions, thereby reducing the cost of expensive organic substances such as conventional TPA (tetrapropylammonium). Since structural derivatives are not used, the manufacturing cost of zeolite-based catalysts can be reduced, and contamination due to washing water containing unreacted organisms can be prevented.

In addition, the zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ according to an exemplary embodiment of the present application is directly manufactured in the form of a zeolite-based catalyst substituted with Na ⁺ and does not require a separate conventional ion exchange process, so the zeolite-based catalyst The manufacturing process can be simplified.

In addition, when the Na ⁺ -substituted zeolite-based catalyst for acrylic acid production according to an exemplary embodiment of the present application is applied to an acrylic acid production process using a lactic acid compound, it has the feature of showing high acrylic acid selectivity.

In addition, specifically, the content of Na precursor remaining on the surface of the catalysts of Example 4, Comparative Example 7, and Examples 7 to 11 was confirmed at pH = 7, and acrylic acid was produced using the catalysts. The conversion rate and acrylic acid selectivity of the catalysts of Example 4 and Examples 7 to 11 were confirmed. The results are shown in Figure 6.

As shown in Figure 6, when comparing the selectivity and conversion rates of Example 4, which is a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ of the present application, and the catalysts of Comparative Example 7 and Examples 7 to 11, the conversion rates are similar. It was confirmed that the acrylic acid selectivity of Example 4 was the best.

In addition, from the results of Examples 7 to 11, it was confirmed that acrylic acid selectivity was high even when the Na precursor was forcibly inserted into the catalyst pores through dry impregnation. For reference, if the Na precursor is forcibly inserted into the catalyst pores through dry impregnation, the catalyst will contain Na ₂ O as a result of calcination.

In addition, from the results of Examples 7 to 11, the Na ₂ O is 0.01 to 3 parts by weight based on 100 parts by weight of the zeolite catalyst for producing acrylic acid, more specifically, the Na ₂ O is contained in 100 parts by weight of the zeolite catalyst for producing acrylic acid. It was confirmed that when 1 to 2 parts by weight of O was included, the conversion rate and acrylic acid selectivity of the catalyst were excellent.

That is, from the results of Examples 7 to 11 where other conditions were the same except for the content of Na ₂ O contained in the catalyst, 0.01 to 3 parts by weight of Na ₂ O was found based on 100 parts by weight of the zeolite-based catalyst for producing acrylic acid. Examples 7 to 11 are excellent in catalyst conversion rate and acrylic acid selectivity, especially in Comparative Examples 7 to 9 in which 1 to 2 parts by weight of Na ₂ O is contained based on 100 parts by weight of zeolite-based catalyst for producing acrylic acid. It can be seen that the catalyst conversion rate and acrylic acid selectivity are superior.

That is, since the Na ⁺ -substituted zeolite-based catalysts for acrylic acid production in Examples 1 to 6 also contain Na ₂ O as a result of firing, the Na ₂ O content is 0.01 to 3 parts by weight based on 100 parts by weight of the zeolite-based catalyst for acrylic acid production. Examples 7 to 9 included are excellent in catalyst conversion rate and acrylic acid selectivity, especially when Na ₂ O is included in 1 to 2 parts by weight based on 100 parts by weight of zeolite-based catalyst for acrylic acid production, catalyst conversion rate and acrylic acid selection The explanation that the degree is superior can be applied.

Comparative Example 9 refers to a catalyst in which a Na precursor was forcibly inserted through dry impregnation into a catalyst that underwent a cation exchange process as before.

In this regard, the activity results of Comparative Example 9 measured by the initial wet impregnation (IWI) method at 4-hour intervals for a total of 16 hours were shown in FIG. 7.

7, in the case of a catalyst in which a Na precursor was forcibly inserted through dry impregnation into a catalyst that underwent a cation exchange process as in Comparative Example 9, the selectivity for acrylic acid was high, but the selectivity for acetaldehyde, a side reactant, was also high (about 40%). It was confirmed that it was high.

That is, the Na ⁺ -substituted zeolite-based catalyst for acrylic acid production prepared by the production method of the present application has high selectivity for acrylic acid and has excellent effects with low selectivity (about 20%) for acetaldehyde, a side reactant.

In addition, organic structural derivatives such as TPA are essentially used, and a cation (Na ⁺ etc.) exchange process is not necessarily required after manufacturing ZSM-5, which has advantages in terms of process efficiency and process cost.

In addition, there is an advantage of reducing the synthesis time because no additional process due to dry impregnation is required during the manufacturing process of the zeolite-based catalyst according to an exemplary embodiment of the present application.

In Comparative Example 10, the maturation time of the solution exceeds the maturation time of the method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to an exemplary embodiment of the present application. As shown in Figure 8, when comparing the XRD (X-Ray Diffraction) analysis results of Comparative Example 10 with the XRD (X-Ray Diffraction) analysis results of Example 1, it was confirmed that there was no difference in catalyst structure in terms of ZSM-5. . Nevertheless, from the above experimental example, it was confirmed that the acrylic acid selectivity (%) of Comparative Example 10 was significantly lower than that of Example 1. This means that amorphous silica and quartz, which are impurities, were generated to the extent of interfering with the activity of the catalyst.

Comparative Examples 11 to 14 have different hydrothermal synthesis times compared to Example 1, and depending on the hydrothermal synthesis time, the content of impurities is excessively high (Comparative Examples 11 and 12) or the impurities are used in the zeolite-based catalyst for producing acrylic acid. It contains about 5 parts by weight based on 100 parts by weight (hereinafter expressed as containing 5% of impurities) (Comparative Examples 13 and 14), and the impurities contained in the zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ of the present application It corresponds to a catalyst that exceeds the content.

This can be confirmed through Figure 9. Specifically, Comparative Examples 11 and 12, as shown in FIG. 9, have an excessively large content of impurities, making it difficult to observe the peak corresponding to ZSM-5 through XRD (X-Ray Diffraction) analysis, which does not indicate the activity of the catalyst. It means that it is difficult. In addition, in the case of Comparative Examples 13 and 14 containing 5% of impurities, it can be seen that there is a relatively small difference in catalyst structure in terms of ZSM-5, as shown in FIG. 9. However, from the above experimental examples, Comparative Examples 13 and 14 It was confirmed that the acrylic acid selectivity (%) of was significantly lower than that of Example 1. This means that amorphous silica and quartz, which are impurities, were generated to the extent of interfering with the activity of the catalyst.

In conclusion, the method for producing the Na ⁺ -substituted zeolite-based catalyst for the production of acrylic acid of the present application has excellent effects in terms of process efficiency and cost, and the Na ⁺ -substituted zeolite-based catalyst for the production of acrylic acid of the present application is a zeolite-based catalyst for the production of acrylic acid. The catalyst performance is excellent. In addition, the Na ⁺ -substituted zeolite-based catalyst for the production of acrylic acid of the present application can be prepared by the method for producing the Na ⁺ -substituted zeolite-based catalyst for the production of acrylic acid of the present application.

Claims (16)

As a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ ,
The zeolite-based catalyst for producing acrylic acid contains impurities,
A zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ , wherein the impurities include more than 0 parts by weight and up to 3 parts by weight based on 100 parts by weight of the zeolite-based catalyst for producing acrylic acid. In claim 1,
A zeolite-based catalyst for producing acrylic acid substituted with Na ^{+ ,} wherein the Si/Al molar ratio of the zeolite-based catalyst for producing acrylic acid is 15 to 50. In claim 1,
A zeolite-based catalyst for producing acrylic acid substituted with Na ^{+ ,} wherein the Na/Al molar ratio of the zeolite-based catalyst for producing acrylic acid is 1.1 to 2.5. The method according to claim 1, wherein the zeolite-based catalyst for producing acrylic acid is Na ⁺ -substituted MFI zeolite, Na ⁺ -substituted Beta zeolite, or ^{Na +} -substituted Y zeolite. In claim 1,
A zeolite-based catalyst for producing acrylic acid substituted with Na + , which includes Na ₂ O on the surface of the zeolite-based catalyst for producing acrylic acid, and wherein the Na ₂ ^O acts as an active site of the catalyst. In claim 5,
The Na ₂ O is contained on the surface of the zeolite-based catalyst for acrylic acid production in ^an amount of 0.01 parts by weight to 3 parts by weight based on 100 parts by weight of the zeolite-based catalyst for producing acrylic acid. Preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor;
Aging the solution at a temperature of 3°C to 30°C for 8 to 23 hours;
After maturing the solution, performing hydrothermal synthesis to produce a product;
After filtering the product, washing the filtered product with a solvent; and
A method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid according to any one of claims 1 to 6, comprising drying and calcining the product after washing with the solvent. In claim 7,
After filtering the product, the step of washing the filtered product with a solvent means washing the product with a solvent within a range where the pH of the filtrate maintains basicity. Na ⁺ -substituted acrylic acid production. Method for producing zeolite-based catalyst. In claim 7,
After filtering the product, the step of washing the filtered product with a solvent means washing the product with a solvent within a range where the pH of the filtrate is maintained at neutral,
A method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid, further comprising the step of dry impregnating the product with a Na precursor after washing the product with a solvent within a range where the pH of the filtrate is maintained at neutrality. . In claim 9,
A method for producing a zeolite-based catalyst for producing Na + -substituted acrylic acid, wherein the ^Na precursor is at least one selected from the group consisting of sodium salts bonded to the conjugated conjugate base anion of an inorganic acid or organic acid. In claim 7,
The step of preparing a solution containing an inorganic alkali salt containing Na ⁺ , a silica precursor, and an alumina precursor,
Preparing a first solution containing an inorganic alkali salt containing Na ⁺ and a silica precursor;
Preparing a second solution containing an alumina precursor; and
A method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid, comprising the step of mixing the first solution and the second solution. In claim 7,
The silica precursor is a Na ⁺ -substituted zeolite for producing acrylic acid containing at least one selected from tetraethylorthosilicate, silica gel, colloidal silica, sodium silicate, natural silica, fumed silica, and synthetic silica. Method for producing catalyst. In claim 7,
The alumina precursor is a method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid, wherein the alumina precursor includes at least one selected from aluminum alkoxide, sodium aluminate, aluminum sulfate, boehmite, and aluminum hydroxide. In claim 7,
A method for producing a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ , wherein the inorganic alkali salt containing Na ⁺ is sodium hydroxide. In claim 7,
A method for producing a zeolite-based catalyst for producing Na ⁺ -substituted acrylic acid, wherein the hydrothermal synthesis is performed at a temperature of 165°C to 195°C for 20 to 28 hours. Comprising the step of producing acrylic acid by dehydrating a lactic acid compound in the presence of a catalyst for producing acrylic acid,
A method for producing acrylic acid, wherein the catalyst for producing acrylic acid is a zeolite-based catalyst for producing acrylic acid substituted with Na ⁺ according to any one of claims 1 to 6.