阅读说明：本技术 颗粒均匀度优异的丝光沸石及其制造方法 (Mordenite having excellent particle uniformity and method for producing same ) 是由 千永恩 金练昊 李昌奎 于 2019-07-29 设计创作，主要内容包括：本发明涉及一种颗粒均匀度优异的丝光沸石及其制造方法,所述方法包括以下步骤：提供溶解有二氧化硅前体的水溶液；提供溶解有结构诱导物质及氧化铝前体的水溶液；提供溶解有表面活性剂的水溶液；混合所述二氧化硅碱性悬浊液和氧化铝水溶液并搅拌,以制造二氧化硅-氧化铝水溶液；在所述二氧化硅-氧化铝水溶液中添加表面活性剂水溶液,以制造沸石合成组合物；使所述沸石合成组合物凝胶化；以及进行结晶化。(The invention relates to mordenite with excellent particle uniformity and a manufacturing method thereof, wherein the method comprises the following steps: providing an aqueous solution having a silica precursor dissolved therein; providing an aqueous solution having dissolved therein a structure-inducing substance and an alumina precursor; providing an aqueous solution having a surfactant dissolved therein; mixing the silica alkaline suspension and the alumina aqueous solution and stirring to prepare a silica-alumina aqueous solution; adding an aqueous surfactant solution to the aqueous silica-alumina solution to produce a zeolite synthesis composition; gelling the zeolite synthesis composition; and performing crystallization.)

1. A process for the manufacture of mordenite which comprises the steps of:

dissolving a pH adjusting substance and a silica precursor in water to provide a silica alkaline suspension;

dissolving a structure-inducing substance and an alumina precursor in water to provide an aqueous solution;

dissolving a surfactant in water to provide an aqueous solution;

mixing the silica alkaline suspension and the alumina aqueous solution and stirring to prepare a silica-alumina aqueous solution;

adding an aqueous surfactant solution to the aqueous silica-alumina solution to produce a zeolite synthesis composition;

gelling the zeolite synthesis composition; and

crystallization is carried out.

2. The method for producing mordenite according to claim 1, wherein the alkaline aqueous solution is produced by adding the pH adjusting substance to water, and the silica alkaline suspension is obtained by adding a silica precursor to the alkaline aqueous solution and dissolving the silica precursor.

3. The method of manufacturing mordenite zeolite of claim 2, wherein the pH adjusting substance is added in an amount such that the pH of the aqueous alkaline solution is in the range of 12 to 14.

4. A process for the manufacture of mordenite zeolite as claimed in claim 2, wherein the mordenite zeolite is treated with a catalyst such as silica in a solvent such as water or air₂Is 0.15 to 0.35, the pH-adjusting substance is added.

5. The method for producing mordenite zeolite according to claim 1, wherein said pH adjusting substance is at least one selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide and ammonium hydroxide.

6. The method for producing mordenite of claim 1, wherein said silica alkali suspension has a content such that a mole number of silica is 0.01 to 0.1 with respect to a mole number of water included in the whole zeolite synthesis composition.

7. The method of claim 1 wherein the silica precursor is added at a rate of 0.1 to 1 g/min with agitation.

8. The method of manufacturing mordenite of claim 1, wherein said silica precursor is at least one selected from fumed silica, precipitated silica, colloidal silica, sodium silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, borosilicate, and fluorosilicate.

9. The method of manufacturing mordenite of claim 2, wherein, after the silica precursor is added, stirring is carried out for 1 to 200 hours to dissolve the silica precursor.

10. The method of claim 1, wherein the aqueous alumina solution is produced by adding a structure-inducing substance and an alumina precursor to water and stirring.

11. The method of claim 10, wherein the structure inducing substance and the alumina precursor are added to water separately or simultaneously and at a rate of 1 to 10 g/min.

12. A process for the manufacture of mordenite zeolite as claimed in claim 1, wherein the silica is used in such a molar ratio (SiO) relative to alumina₂/Al₂O₃) The alumina precursor is added at a content ranging from 5 to 50.

13. The method of claim 1, wherein the alumina precursor is at least one selected from the group consisting of sodium aluminate, sodium aluminum sulfate and aluminum.

14. The method of manufacturing mordenite zeolite of claim 1, wherein said structure-inducing substance is added in a content ranging from 1/100 to 1/10 moles with respect to 1 mole of silica.

15. The method of claim 1, wherein the structure-inducing substance is at least one selected from the group consisting of tetramethylammonium bromide, tetramethylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium hydroxide, and tetraethylammonium tetrafluoroborate.

16. The method of manufacturing mordenite zeolite of claim 1, wherein the aqueous surfactant solution is manufactured by adding a surfactant to water having a temperature of 20 ℃ to 80 ℃ under stirring.

17. The method of manufacturing mordenite zeolite of claim 1, wherein said surfactant is added so that the concentration in the aqueous surfactant solution is from 0.01 to 0.1 mole.

18. The method of claim 1, wherein the surfactant is at least one selected from the group consisting of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride and cetylpyridinium chloride.

19. The method of claim 1 wherein said mixing is carried out by adding an aqueous alumina solution to the alkaline suspension of silica at a rate of 1 to 10 cc/min.

20. The method of manufacturing mordenite of claim 19, wherein, in said mixing, after completion of the addition of the aqueous alumina solution, stirring is further performed for 1 to 72 hours.

21. The method of making mordenite zeolite of claim 1, wherein, in the step of making the zeolite synthesis composition, the aqueous surfactant solution is added to the aqueous silica-alumina solution at a rate of 1 to 10 cc/min.

22. The method of manufacturing mordenite of claim 1, wherein the gelling is performed by stirring at a temperature of 20 to 60 ℃ for 1 to 120 hours.

23. A process for the manufacture of mordenite zeolite according to claim 1, wherein the crystallization is carried out by carrying out the reaction at a temperature of 140 to 210 ℃.

24. A process for the manufacture of mordenite of any of claims 1 to 23, wherein the crystallisation is carried out in the presence of seed crystals.

25. A mordenite zeolite excellent in uniformity, which is a secondary particle obtained by aggregating primary particles having micropores inside, wherein mesopores are present between particles of the secondary particle, and when the size of arbitrarily selected 10 particles (100 particles in total) is measured in each of 10 scanning electron microscope images taken at an acceleration voltage of 5.0kV and a magnification of 50000, the mordenite zeolite has 90% or more of particles having a particle size within a most distributed particle size region (10nm units) ± 30 nm.

Technical Field

The present invention relates to a mordenite having excellent particle uniformity and a method for producing the same.

Background

In recent years, as the demand for development of functional materials has been gradually increased, the necessity for development of new materials that add new functions to materials having excellent physical properties has been increasing.

Organic-inorganic nanoporous materials or porous organic-inorganic hybrid materials, organic metal frameworks or porous inorganic porous materials have characteristics of structural diversity, a large number of active sites, a wide specific surface area and pore volume, and thus are widely used for catalysts, adsorbents, membranes, drug delivery materials, electronic materials, and the like. These porous substances have the highest utilization as catalysts and adsorbents and are classified into microporous substances (<2nm), mesoporous substances (2-50nm), and macroporous substances (>50nm) according to the sizes of their pores.

Zeolites, which are one of representative microporous substances, are formed of Crystalline aluminum silicate (alumina silicate) and are characterized by high specific surface area and pore volume and uniform micropores, and thus are widely used for catalyst reactions of selecting the size or shape of molecules, such as Friedel-crafts Acylation, Friedel-crafts Alkylation, Claisen-Schmidt Reaction, and the like.

In the art, attempts to achieve desired functions and functionalities by controlling the pore distribution and surface of zeolites have been continuously made.

For example, KR2011-0019804 (published 2009, 08/21) relates to a method for producing an organic-inorganic hybrid nanoporous body, an organic-inorganic hybrid nanoporous body obtained by the method, and uses thereof, wherein a method for producing a porous body by using tris (C) is provided₁-C₇) Method for producing aluminum organic-inorganic hybrid nanoporous material of pure zeolite MTN structure having high crystallinity using alkyl-1, 3, 5-benzenetricarboxylate as organic ligand, and aluminum organic-inorganic hybrid nanoporous materialAn adsorbent using the same or a heterogeneous catalyst, and the like.

On the other hand, JP2005-254236 (published 22/09/2005) relates to a mordenite-type zeolite alkylation catalyst, in which a mordenite-type zeolite catalyst having a controlled large pore structure, a catalyst composite including the same, and a method of manufacturing the catalyst composite are provided.

Disclosure of Invention

Technical problem to be solved

As a result of repeated studies on the relationship between the particle uniformity of the mordenite type zeolite catalyst and the catalyst activity, it was confirmed that the more uniform the size of the catalyst particles, the more the catalyst activity increased. Accordingly, the present invention provides a method for producing a mordenite-type zeolite catalyst excellent in particle uniformity, and provides a catalyst obtained thereby.

Technical scheme

The invention relates to a method for preparing mordenite, which comprises the following steps: dissolving a pH adjusting substance and a silica precursor in water to provide a silica alkaline suspension; dissolving a structure-inducing substance and an alumina precursor in water to provide an aqueous solution; dissolving a surfactant in water to provide an aqueous solution; mixing the silica alkaline suspension and the alumina aqueous solution and stirring to prepare a silica-alumina aqueous solution; adding an aqueous surfactant solution to the aqueous silica-alumina solution to produce a zeolite synthesis composition; gelling the zeolite synthesis composition; and performing crystallization.

The pH adjusting substance may be added to water to produce an alkaline aqueous solution, and a silica precursor may be added to the alkaline aqueous solution and dissolved to obtain the silica alkaline suspension.

The pH adjusting substance may be added in such an amount that the pH of the alkaline aqueous solution is 12 or more.

Can be made to oppose SiO₂Is 0.15 to 0.35, the pH-adjusting substance is added.

The pH adjusting substance may be at least one selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and ammonium hydroxide.

The silica alkaline suspension may have a content such that the mole number of silica is 0.01 to 0.1 with respect to the mole number of water included in the entire zeolite synthesis composition.

The silica precursor may be added at a rate of 0.1 to 1 g/min with stirring.

The silica precursor may be at least one selected from the group consisting of fumed silica, precipitated silica, colloidal silica, sodium silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, borosilicate, and fluorosilicate.

After the silica precursor is added, the silica precursor may be dissolved by stirring for 1 to 200 hours.

The aqueous alumina solution can be produced by adding a structure-inducing substance and an alumina precursor to water and stirring.

The structure-inducing substance and the alumina precursor may be added to water separately or simultaneously and added at a rate of 1 to 10 g/min.

The molar ratio of silica to alumina (SiO)₂/Al₂O₃) The alumina precursor is added at a content ranging from 5 to 50.

The alumina precursor may be at least one selected from the group consisting of sodium aluminate, sodium aluminum sulfate and aluminum.

The structure-inducing substance may be added in a content ranging from 1/100 to 1/10 moles with respect to 1 mole of silica.

The structure inducing substance may be at least one selected from the group consisting of tetramethylammonium bromide, tetramethylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium hydroxide, and tetraethylammonium tetrafluoroborate.

The aqueous surfactant solution may be manufactured by adding the surfactant to water having a temperature of 20 ℃ to 80 ℃ with stirring.

The surfactant may be added in such a manner that the concentration in the aqueous surfactant solution is 0.01 to 0.1 mol.

The surfactant may be at least one selected from the group consisting of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride and cetylpyridinium chloride.

The mixing may be performed by adding the aqueous alumina solution to the silica alkaline suspension at a rate of 1 to 10 cc/min.

In the mixing, stirring may be further performed for 1 to 72 hours after the addition of the alumina aqueous solution is completed.

In the manufacturing step of the zeolite synthesis composition, the surfactant may be added to the aqueous silica-alumina solution at a rate of 1 to 10 cc/min.

The gelation may be performed by stirring at a temperature of 20 to 60 ℃ for 1 to 120 hours.

The crystallization may be performed by performing the reaction at a temperature of 140 to 210 ℃.

The crystallization may be carried out in the presence of a seed crystal.

Another aspect of the present invention provides a mordenite having excellent uniformity, which is a mordenite having secondary particles in which primary particles having micropores therein are aggregated, wherein the secondary particles have mesopores between particles, and wherein when the size of arbitrarily selected 10 particles (100 particles in total) is measured in each of 10 Scanning Electron Microscope (SEM) images taken at an acceleration voltage of 5.0kV and a magnification of 50000, the mordenite has 90% or more of particles having a particle size within a most distributed particle size region (10nm units) ± 30 nm.

Advantageous effects

According to the present invention, it is possible to produce mordenite having excellent uniformity of particle size, and further, it is possible to produce mordenite having various ranges of particle sizes while maintaining the uniformity as described above.

By using a catalyst manufactured using the mordenite having a uniform particle size provided by the present invention, catalyst activity can be improved.

Drawings

Fig. 1 is a Scanning Electron Microscope (SEM) image of a sample of mordenite obtained in example 1 taken at the magnification described.

Fig. 2 to 4 are SEM images of a sample of the mordenite obtained in example 1, taken at a magnification of 50000, and are graphs showing the results of arbitrarily selecting 10 particles in each image and measuring the particle size.

Fig. 5 is an SEM image of a sample of the mordenite obtained in comparative example 1 taken at the magnification described.

Fig. 6 to 8 are SEM images of a sample of the mordenite obtained in comparative example 1, taken at a magnification of 50000, and are graphs showing the results of arbitrarily selecting 10 particles in each image and measuring the particle size.

Fig. 9 is a graph showing a size distribution in 10 μm units among the particle sizes measured from fig. 2 to 4 and 6 to 8.

Fig. 10 shows the results of testing the catalyst activity using catalysts manufactured from the mordenite obtained in example 1, comparative example 1 and comparative example 2.

Fig. 11 is an SEM image of a sample of the mordenite obtained in comparative example 2 taken at the magnification described.

Fig. 12 is an SEM image of a sample of the mordenite obtained in comparative example 2 taken at a magnification of 50000.

FIG. 13 is a graph showing FT-IR analysis results of acid centers analyzed by In-situ Pyridine (In-situ Pyridine) adsorption experiments of mordenite obtained In example 1, comparative example 1 and comparative example 2.

Fig. 14 is a SEM image of the samples of mordenite obtained in examples 2 to 4 taken at a magnification of 50000, which is a graph shown together with the SEM image of the sample of example 1.

Fig. 15 is an SEM image of samples of the mordenite obtained in examples 5 to 7 taken at a magnification of 50000.

Best mode for carrying out the invention

The present invention relates to a mordenite and a method for preparing the same, and more particularly to a method for preparing a mordenite having excellent particle uniformity.

The present inventors have confirmed that when a silica alkaline suspension in which a silica precursor is dissolved and an alumina aqueous solution in which a structure-inducing substance and an alumina precursor are dissolved are separately produced and mixed, the particle size of mordenite can be uniformly formed by controlling the mixing conditions, and have completed the present invention.

First, an alkaline suspension of silica in which a silica precursor is dissolved is prepared. The silica alkaline suspension is a mixed solution in which a silica precursor is dispersed in an alkaline aqueous solution.

To produce the silica alkaline suspension, first, an alkaline pH adjuster is added to water to increase the pH, thereby producing an alkaline aqueous solution. Silica precursors are not readily soluble in low pH solutions. Therefore, in order to enhance the dissolution of the silica precursor, it is preferable to produce an alkaline aqueous solution by adding an alkaline pH adjusting substance as described above. The added pH adjusting substance provides cations into the zeolite synthesis composition solution, thereby also playing a role of inducing crystallization of the zeolite in the step of crystallization.

Therefore, when the alkaline pH-adjusting substance is not included in the solution, the silica precursor is not easily dissolved due to low pH, and the content of cations in the solution becomes low, which may result in a decrease in the yield of the final zeolite and low crystallinity.

In order to improve the solubility of the silica precursor as described above and to provide a sufficient amount of cations for forming crystals, it is preferable to add the pH adjusting substance so that the pH of the alkaline aqueous solution is 12 or more, specifically, in the range of 12 to 14. When the pH of the alkaline aqueous solution is less than 12, the silica precursor is not easily dissociated in the alkaline solution and does not participate in the reaction, and in the final crystallization process, silica crystals may be generated as impurities of the sample. As an example, relative to 1 mol of SiO₂The pH adjusting substance is added at a molar ratio of 0.15 to 0.35, whereby an alkaline suspension of silica having a pH range as described above can be obtained.

The pH adjusting substance is not limited thereto, and examples thereof include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and ammonium hydroxide, and any one of these may be added alone, or two or more of these may be added in combination.

The silica alkaline suspension of the present invention includes a silica precursor. The silica precursor is added to an alkaline aqueous solution obtained by adding a pH adjusting substance to water and dispersed, thereby producing an alkaline suspension of silica. That is, the silica precursor is added to an alkaline aqueous solution, and stirred until the silica precursor is completely dissolved, thereby obtaining an alkaline suspension of silica. This ensures uniform dispersibility of the silica precursor in the alkaline aqueous solution, and further enables production of a zeolite having high uniformity.

When the silica precursor is added to the alkaline aqueous solution, it is preferably added slowly. The silica precursor starts to be dissolved while being added to the alkaline aqueous solution, however, when a large amount of silica precursor is added at a time, the silica precursor is aggregated and dissolved at a non-uniform rate, and the viscosity of the solution itself becomes high. Further, the viscosity of the solution becomes high, which leads to a decrease in the physical stirring speed, and may cause a secondary uneven dissolution caused by such a decrease in the stirring speed. Repeating the process as described above causes difficulty in completely dissolving the silica precursor in the alkaline aqueous solution, and the time required to form a solution in which the silica precursor is uniformly dispersed also becomes long.

For the above reasons, the silica precursor is added to the aqueous alkali solution at a rate of preferably 0.1 to 1 g/min, more preferably 0.3 to 0.8 g/min.

Preferably, the Silica precursor is added in such a manner that the Mole Ratio of Silica with respect to Water included in the entire composition, that is, in such a manner that the Silica-to-Water Mole Ratio (Silica-to-Water Mole Ratio) is in the range of 0.01 to 0.1. The silica-water molar ratio may preferably be from 0.03 to 0.08, most preferably from 0.05 to 0.07. The silica-water molar ratio is a factor for adjusting the uniformity and viscosity of the silica alkaline aqueous solution, and when the above numerical value range is satisfied, the generation of zeolite crystals having a crystal size within a certain range can be induced, and the uniformity of the crystals can be improved.

The silica precursor is also suitable for use in the present invention as long as it is generally used for the production of zeolite, and may include, for example, one or more selected from fumed silica, precipitated (precipitated) silica, colloidal silica, sodium silicate, tetramethyl orthosilicate, tetraethyl orthosilicate, borosilicate, and fluorosilicate, although not limited thereto. As the silica precursor, silica in a dissolved state such as silica sol (Ludox) silica can also be used, but precipitated silica is more preferably used in terms of easiness of controlling the reaction rate, economy, and the like.

The basic suspension is produced on the premise that the silica precursor is added to an alkaline aqueous solution to which a pH adjusting substance is added, but the alkaline suspension may be produced by adding the silica precursor and the pH adjusting substance at the same time, and the alkaline suspension may be produced by adding the silica precursor after the pH adjusting substance is added, that is, before the pH adjusting substance is completely dissolved, to change the pH of the solution to alkaline and dissolve the silica precursor

In this case, the method of adding the pH adjusting substance and the silica precursor to the water may be performed in the same manner as the method of adding the silica precursor to the alkaline aqueous solution, and thus, a detailed description thereof will be omitted.

In the process of adding the silica and the pH adjuster, it is preferable to add the silica and the pH adjuster while stirring because the silica and the pH adjuster are dissolved in water. For example, the stirring may be performed at a speed of 100 to 800 rpm. If the stirring speed is too slow, the solution may not be sufficiently mixed, and the dispersion uniformity in the solution may be reduced, and if the stirring speed is too fast, the solution may splash, and therefore, the stirring speed is preferably in the above range.

Further, even after the addition of the silica and the pH adjusting substance is completed, it is preferable to continuously stir the silica and the pH adjusting substance at the stirring speed in the above-described range in order to completely dissolve the silica and the pH adjusting substance.

In this case, the further stirring may vary depending on the amounts of silica and the pH adjusting substance to be added, but is preferably performed until the silica and the pH adjusting substance are completely dissolved. For example, the further stirring may be carried out at a stirring speed of 100 to 800rpm for 1 hour or more. When the stirring time is too short, the dissociation of the silica precursor is insufficient, and the uniformity of the solution may be reduced. On the other hand, the longer the stirring time, the more the uniformity of the solution is preferably improved, and therefore, the longer the stirring time, the more the industrial economy may be deteriorated. More preferably, it may be carried out for 120 hours or less.

Next, a step of preparing an aqueous solution in which an alumina precursor and a structure-inducing substance are dissolved is included.

The alumina precursor is also suitable for use in the present invention as long as it is generally used in the manufacture of zeolites, and may be selected from, for example, sodium aluminate, sodium aluminum sulfate and aluminum. Any one of these alumina precursors may be used alone, or two or more of them may be mixed and used.

The amount of the alumina precursor used may be determined according to the silica-alumina molar ratio of the zeolite to be obtained. For example, the silica-alumina molar ratio (SiO)₂/Al₂O₃Mole Ratio) is in the range of 5 to 50, but is not limited thereto.

On the other hand, the structure-inducing substance is also suitable for use in the present invention as long as it can be used in the synthesis of mordenite, and examples thereof include tetramethylammonium bromide, tetramethylammonium chloride, tetramethylammonium hydroxide, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium hydroxide, tetraethylammonium tetrafluoroborate, and the like. Any of these structure-inducing substances may be used alone, or two or more of them may be mixed and used.

The degree of crystallinity depends on the concentration of the structure-inducing substance in the solution used to synthesize the zeolite crystals to be obtained, and the size of the crystals may vary depending on the amount of the structure-inducing substance. Therefore, the amount of the structure-inducing substance to be used can be determined according to the crystallinity and size of the zeolite to be obtained. However, when the structure-inducing substance is used in an excessively small amount, crystals may not be formed, and it is preferable to use 1/100 moles or more based on 1 mole of silica, but the invention is not limited thereto. The upper limit of the amount of the structure-inducing substance to be used may be adjusted depending on the size of the crystal, and 1/10 mol or less is preferably used for economical efficiency and high purity of the crystal, but the structure-inducing substance is not limited thereto.

The alumina precursor and the structure-inducing substance are dissolved in water to produce an alumina aqueous solution. The alumina precursor and the structure-inducing substance are added to water, and stirred until these are completely dissolved in water, whereby an alumina aqueous solution can be obtained. The alumina precursor and the structure-inducing substance are completely dissolved in water, so that a uniformly dispersed alumina aqueous solution can be obtained, whereby the particle uniformity of the zeolite can be ensured.

In order to manufacture the uniformly dispersed alumina aqueous solution as described above, it is preferable that the alumina precursor and the structure-inducing substance are slowly added to water. In this case, the alumina precursor and the structure-inducing substance may be added simultaneously, or any one of them may be added first, and then, continuously or after a certain time interval. More specifically, the alumina precursor and the structure-inducing substance may be added at a rate of 1 to 10 g/min.

In the process of adding the alumina precursor and the structure-inducing substance, it is preferable to add the alumina precursor and the structure-inducing substance while stirring because the alumina precursor and the structure-inducing substance can be dissolved in water. In this case, the stirring may be performed under the same conditions as those in the process of producing the silica alkali suspension.

Further, it is preferable that the stirring is continued even after the addition of the alumina precursor and the structure-inducing substance is completed for the complete dissolution of the alumina precursor and the structure-inducing substance. The stirring after the completion of the addition may vary depending on the amounts of the alumina precursor and the structure-inducing substance to be added, but is preferably performed while completely dissolving the alumina precursor and the structure-inducing substance, and may be performed, for example, for 15 minutes to 1 hour. The stirring completion time may be a time at which it is confirmed that there is no undissolved and remaining substance and the solution is transparent when visually confirmed, and may be confirmed, for example, about 1 hour after the end of the addition.

Next, a step of preparing an aqueous solution in which a surfactant is dissolved is included.

The surfactant forms micelles between the mordenite particles having micropores formed by the structure-inducing substance or adheres to the surfaces of the particles in an ion form in an ion-bound form to increase the intervals between the particles, thereby inducing mesopores. Examples of such surfactants include cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, and cetylpyridinium chloride, and these may be used alone or in combination of two or more.

The surfactant is also prepared as an aqueous solution dissolved in water. In the case where the surfactant exists in the form of an aqueous solution, it is diluted in water and stirred so as to be uniformly dispersible, and the surfactant existing in the form of powder is stirred so as to be a uniform solution in the form of an aqueous solution. At this time, the surfactant preferably has a concentration range of 0.01 to 0.1 mol.

In order to uniformly disperse the surfactant in water, it is preferable to stir at a certain temperature for a predetermined time. Specifically, the surfactant may be diluted or dissolved in a temperature range of normal temperature (20 ℃) to 80 ℃ while being stirred in water, and at this time, may be treated at a stirring speed of 30 to 500rpm for 10 minutes to 24 hours.

The stirring temperature is preferably a temperature range from room temperature to 80 ℃ because the solubility in water varies depending on the surfactant, and a uniform aqueous solution can be obtained when the mixture is heated. More preferably, it may be heated at a temperature ranging from 20 to 100 deg.c, and further preferably, it may be heated at a temperature ranging from 30 to 80 deg.c.

On the other hand, if the stirring speed is too slow, it takes a long time to stir, and if the stirring speed is too fast, the uniformity of the particle size may be reduced when the surfactant-generated foam is added to the gel, and therefore, as described above, it is preferable to perform the treatment at a stirring speed of 30 to 500 rpm. The stirring speed is more preferably 50 to 450rpm, still more preferably 100 to 400rpm, and still more preferably 200 to 400 rpm.

Further, the stirring time may vary depending on the solubility of the surfactant and the treatment temperature, but the stirring treatment may be carried out for 10 minutes to 24 hours as described above to form a uniform dispersion state. For example, it may be 1 hour to 24 hours, 3 hours to 20 hours, 5 hours to 20 hours, 7 hours to 15 hours, or the like.

The silica alkaline suspension, the alumina aqueous solution and the surfactant aqueous solution prepared as described above were mixed. In this case, in order to produce a zeolite having a high uniformity of particle size, silica, alumina, a pH adjusting substance, a structure inducing substance, and a surfactant should be uniformly dispersed in the zeolite synthesis composition.

For this purpose, in the present invention, it is preferable to add one of the silica alkaline suspension and the alumina aqueous solution slowly with stirring.

The order of addition is not particularly limited, but a solution having a low viscosity is gradually added to a solution having a high viscosity to slowly decrease the viscosity of the entire solution, so that the uniformity of the particle size can be more improved. Therefore, it is more preferable to add other solutions having low viscosity dropwise to the silica aqueous solution having high viscosity. Further, when the surfactant aqueous solution is added in a state where a uniform silica/alumina mixed aqueous solution is prepared, a sample having a certain silica/alumina ratio as a whole can be uniformly obtained.

During the addition of the aqueous alumina solution to the silica alkali suspension, the addition may be carried out slowly, for example, in a dropwise manner. More specifically, the aqueous alumina solution may be added at a rate of 10 cc/min or less. The addition rate is preferably not particularly limited because the slower the addition, the more uniform dispersibility can be secured, but is more preferably 1.0 cc/min or more from the viewpoint of productivity. More preferably, it may be added at a rate of 1.0 to 7 cc/min, and still more preferably, it may be added at a rate of 2.0 to 4.5 cc/min.

By completing the mixing by the method described above, a silica-alumina aqueous solution can be obtained, and a step of further stirring the silica-alumina aqueous solution can be included as necessary. Further stirring is performed for 1 hour or more, specifically, 1 hour to 72 hours, in order to more uniformly disperse the zeolite synthesis composition. For example, it may be 2 hours to 60 hours, 2 hours to 48 hours, 3 hours to 36 hours, or the like.

To the aqueous silica-alumina solution prepared as described above, an aqueous surfactant solution was added. Preferably, the surfactant aqueous solution is also slowly added for uniform dispersion, and is not particularly limited, but may be added at a rate of 10 cc/min or less, for example, in a rate range of 1 to 8 cc/min, 2 to 7 cc/min, 3 to 5 cc/min, or the like.

Thus, a uniformly dispersed zeolite synthetic composition can be obtained, and the obtained zeolite synthetic composition is gelled and crystallized, thereby obtaining a mordenite having a uniform particle size.

Gelling the zeolite synthesis composition. The gelation may be carried out for 2 hours or more. Gelation can be carried out in the range of normal temperature (20 ℃) to 60 ℃ and in the range of 1 hour to 120 hours. Gelation was carried out by stirring in the temperature and time condition ranges as described above. At this time, the stirring speed may be determined according to the kind of the surfactant under the condition that no foam is generated, and the stirring may be generally performed in the range of 50 to 1000 rpm. The foam is formed at a higher stirring speed exceeding the above range, which causes the unevenness in the gel to be increased.

The gelled zeolite synthesis composition is reacted at a temperature of 140 to 210 ℃, preferably at a temperature of 150 to 190 ℃, whereby zeolite crystals can be produced. Since the crystallization temperature is related to the crystallization rate and the crystal size, when the crystallization temperature is high, the crystallization rate is decreased and the crystal size is increased, and the crystallization reaction temperature can be determined in consideration of this.

On the other hand, the crystallization is not necessarily limited thereto, but may be performed for 24 hours or more, for example, from 24 hours to 100 hours, from 48 hours or more to 96 hours, or from 48 hours to 84 hours.

According to the method of the present invention as described above, the raw material substances are previously prepared in the state of a dissolved aqueous solution, and these are slowly mixed, whereby a zeolite synthesis composition in which the respective raw material substances are uniformly dispersed can be obtained, and by producing mordenite crystals using this composition, a zeolite having a uniform crystal size can be obtained. That is, according to the process of the present invention, the crystal size of the primary particles of mordenite is uniform, and the secondary particles formed by using the surfactant can also be formed to be uniform in size.

On the other hand, in the present invention, a surfactant is included in addition to the structure-inducing substance, and the mordenite structure having micropores formed by the structure-inducing substance forms larger micelles at the periphery of the surfactant, so that mesopores can be formed between mordenite crystals. Thus, it is possible to obtain mordenite of a hierarchical structure in which the secondary particles formed by agglomeration of the primary particles have both micropores formed in the primary particles and mesopores formed between the particles.

Further, mordenite seed crystals (seed) may be further added in the present invention. Although these mordenite seed crystals are not particularly limited, they may be added together in the step of producing the aqueous surfactant solution, and may also be added together in the step of adding the aqueous surfactant solution to the aqueous silica-alumina solution. Further, the seed crystal may be added in the gelation step.

Further, one or more binders selected from alumina, silica-alumina and/or the respective precursors may be added to the mordenite-type zeolite material to form a catalyst. The catalyst according to the invention may be suitable for the conversion of aromatic hydrocarbons.

The catalyst may further comprise one or more zeolites selected from BEA, EUO, FAU, FER, MEL, MFI, MFS, MOR, MTT, MTW and TON. In particular, when BEA, FAU, MFI, or the like is added, the zeolite induces cracking (cracking) or the like, and thus induces cracking of olefins generated in the catalyst reaction, and prevents deposition of carbon substances on the catalyst, and thus an effect of extending the life of the catalyst can be expected.

In addition, the catalyst may further include a metal component including one or more elements selected from transition metals and noble metals. The transition metal may be one or more selected from groups 6 to 14, and the noble metal may be one or more selected from groups 8 to 11 on the periodic table. Preferably, the metal component may be one or more selected from rhenium, nickel, molybdenum, platinum, and tin.

Since the zeolite obtained by the present invention is excellent in the uniformity of the primary particles and the secondary particles, when used as a catalyst, it can obtain a catalyst activity superior to or equal to that obtained when a zeolite having a smaller average particle size is used. The catalyst activity can be further improved.

These results have been conventionally considered that when the average particle size of zeolite is small, the diffusion rate can be increased and the catalyst activity is excellent, and therefore, it is considered that controlling the particle size is an important factor for controlling the diffusion rate, but it can be confirmed by the present invention that the catalyst activity can be improved as the uniformity of the crystal size of zeolite is higher than these average particle sizes.

Detailed Description

The present invention will be described more specifically below with reference to examples. The following examples are intended to specifically illustrate the present invention, and therefore, the present invention is not limited thereto.

Example 1

After 2.67g of NaOH had been completely dissolved in 60ml of water (pH about 13), 17.96g of precipitated silica were slowly added over 30 minutes. During the addition, stirring was performed at 500rpm, and after the entire addition, further stirring was performed at the same speed for 1 hour, thereby completely dissolving the precipitated silica and NaOH. Thus, an alkaline suspension of silica was obtained.

2.12g of sodium aluminate and 1.85g of tetraethylammonium bromide (TEABr) as structure-inducing substance were slowly added to 20ml of water over 2 minutes. Stirring was carried out at 200rpm during the addition and further stirring was carried out at the same speed for 30 minutes after the entire addition, thereby completely dissolving the sodium aluminate and the structure-inducing substance. Thereby obtaining an aqueous alumina solution.

4.2g of cetyltrimethylammonium chloride (CTAC) was added to 14ml of water at normal temperature (25 ℃). Stirring was carried out at 300rpm during the addition and further for 3 hours after the complete addition, thereby completely diluting CTAC. Thereby obtaining an aqueous surfactant solution.

While stirring the silica alkali suspension, the alumina aqueous solution was added dropwise to the silica alkali suspension over 10 minutes. After the addition was completed, stirring was further performed for 3 hours to produce a silica-alumina aqueous solution.

Next, the aqueous surfactant solution was added dropwise to the aqueous silica-alumina solution over 5 minutes to manufacture a mordenite synthesis composition.

For the mordenite synthesis composition obtained, gelling was carried out at a temperature of 30 ℃ for 2 hours to produce a gelled product.

Next, the gel was loaded in a synthesis vessel and reacted in an oven at a temperature of 180 ℃ for 72 hours to effect crystallization, thereby forming mordenite crystals.

After completion of the crystallization process, the synthesis vessel was taken out of the oven and filtered after forced cooling in running tap water, and the filtrate was obtained after washing with 2L of water.

After washing, the filtrate was put into an oven and dried at 60 ℃ for 12 hours or more to obtain a sample.

The sample obtained was heated at 1 ℃ per minute and after drying at 110 ℃ for 2 hours, it was sintered at 550 ℃ for 5 hours to obtain a mordenite sample in the Na form.

The samples were collected and photographed by SEM at prescribed magnifications (1k, 5k, 10k, and 20 k). The results are shown in fig. 1.

Further, for the manufactured mordenite crystals, 10 samples were collected and each sample was photographed with SEM at a magnification of 50k, and shown in fig. 2 to 4. 10 particles were arbitrarily selected from the respective SEM photographs of fig. 2 to 4, and the size of each particle was measured, and the results thereof are shown together.

Further, the measured size of each particle was confirmed in a unit of 10nm in number, and the result thereof is shown in fig. 9.

Comparative example 1

Zeolite having the product name CBV21A (silica/alumina ratio 20, provided in ammonium form and specific surface area 500 m) sold by Zeolyst²(g) samples were photographed by SEM at predetermined magnifications (1k, 5k, 10k and 20 k). The results are shown in fig. 5.

Further, for the manufactured mordenite crystals, 10 samples were collected and each sample was photographed with SEM at a magnification of 50k, and they are shown in fig. 6 to 8. 10 particles were arbitrarily selected from the SEM photographs of fig. 6 to 8, and the size of each particle was measured, and the results thereof are shown together.

Further, the measured size of each particle was confirmed in a unit of 10nm in number, and the result thereof is shown in fig. 9.

Evaluation of particle uniformity

As can be seen from fig. 9, in the mordenite produced according to example 1, crystals having a particle size of 90-100nm were distributed in the most proportion and in addition, consisted of crystals having a particle size within the above range of size ± 30 nm. On the other hand, it can be seen that the mordenite of the comparative example in which crystals having a particle size in the range of 60 to 200nm were distributed without being inferior, and thus the uniformity of particles was low.

It can be seen that mordenite with higher particle uniformity can be produced according to the method of the present invention.

Evaluation of catalyst Activity

The MOR catalysts using the mordenite of example 1, comparative example 1 and comparative example 2 were used to evaluate catalyst activity.

The mordenite of comparative example 2 was a zeolite sold by Zeolyst under the product name CP7176 (silica/alumina ratio 20, provided in ammonium form, BET specific surface area 540 m)²Per gram) of sample.

Evaluation of the catalyst activity was carried out as follows, increasing to 400 ℃ at a rate of 3.33 ℃ per minute, at 1% O₂/N₂After drying under gas conditions for 90 minutes, conversion to H takes place at the same temperature₂Gas and reduced for 120 minutes.

The sample catalyst that ended the reduction was cooled at a rate of 10 ℃ per minute and evaluated starting from 350 ℃.

Feed (Feed) toluene and C9 Aromatic hydrocarbon (C9 Aromatic) were mixed in a mass ratio of 50:50 and used.

At this time, the reaction product was collected at each temperature, and then subjected to composition analysis by GC analysis.

The activity characteristics of each catalyst are shown in table 1 below.

[ TABLE 1 ]

Further, the results of the catalyst activity evaluation for each catalyst are shown in fig. 10. As can be seen from fig. 10, the catalyst of example 1 showed higher conversion in all the intervals of the reaction temperature even at the same reaction temperature. As can be seen from the table 1, there is no great difference in all physical property evaluation results except for the crystal size and the micropore surface area. In particular, the crystal size of comparative example 1 and comparative example 2 was smaller than that of example, but the catalyst activity was relatively poor, which is different from the conventional knowledge that the catalyst activity was excellent when the particle size of the catalyst was small. This is because the zeolite used in the catalyst produced by the process of the present invention has a uniform particle size distribution, and therefore, when the mordenite has a uniform particle size distribution, even if the particle size is large, more excellent catalyst activity can be obtained.

Analysis of acid centers

The acid centers were analyzed by FT-IR analysis according to In situ Pyridine (In-situ Pyridine) adsorption experiments.

Each of samples H of example 1, comparative example 1 and comparative example 2 was pelletized to form 25mg of pellets.

The pellets were mounted In an In-situ cell and dried for 3 hours at 500 ℃ under vacuum by a pre-treatment process. Next, 0.5. mu.l of pyridine was injected.

The injected pyridine is vaporized and passed through the pellet sample. At this time, the amount of pyridine adsorbed on the sample was analyzed by FT-IR to quantify it.

Pyridine (Pyridine) was used as the adsorbent for the total acid amount, 2, 6-Di-t-butylpyridine (2,6-Di-tert Butyl Pyridine, 2,6-DTBPy) was used as the adsorbent for the external surface acid amount, and the internal acid amount was calculated as the difference between the total acid amount and the external surface acid amount. For the external surface acid amount, the same method as measuring the total acid amount was performed except that the adsorbent material was changed.

[ TABLE 2 ]

	Comparative example 1	Comparative example 2	Example 1
				Acid content of outer surface	128	148	134
Internal acid amount	480	325	352
				Total acid amount	608	473	486

As is clear from the results of the acid center analysis shown in table 2, even if the amount of acid in example 1 is small, it is understood from the results of the catalyst activity evaluation shown in fig. 10 that the performance is better when comparative example 1 and example 1 are compared. These results show that there is a greater correlation in terms of uniformity of the particles with catalyst activity than the effect of the amount of acid. On the other hand, although the amount of acid of comparative example 2 is similar as compared with example 1, it is understood from the result of fig. 10 that the catalyst activity is further lowered, which is judged as a difference that the crystal shape itself of the catalyst particle of comparative example 2 is not uniform and the catalyst particle size is not uniform as shown in fig. 11 and 12. From the above results, it is understood that improvement of uniformity of zeolite contributes to improvement of diffusion speed of each particle, and thus, catalyst activity can be increased, but the change of physical properties of zeolite does not contribute to increase of catalyst activity.

Proportion of octahedral skeleton to tetrahedral skeleton

The ratio of the tetrahedral structure and the octahedral structure included in the samples of example 1, comparative example 1, and comparative example 2 was measured by solid aluminum nuclear magnetic resonance analysis.

The presence of tetrahedral structure (Td) indicates the presence of Al within the zeolite framework and the octahedral structure (Od) indicates the presence of Al within the pores but not within the framework.

The larger the amount of Al present in the skeleton means that, among Al included in the sample, the more Al is available to act on the acid center, and means that the purity of the sample is high.

The solid aluminum nmr analysis was performed by the following method.

The samples of each of example 1, comparative example 1, and comparative example 2 were ground in a mortar and uniformly mixed to prepare measurement samples.

For each measurement sample, an experiment was performed under a rotation (spinning) condition of 12kHz at 600MHz using a 4mm rotor (rotor). The Pulse (Pulse) was 0.5. mu.s, and the delay time (delay time) was set to 5 seconds.

The structure of the thus obtained solid aluminum nmr analysis is shown in fig. 13.

Among peaks (peak) appearing under the conditions, those appearing at 53ppm were regarded as aluminum tetrahedrons (Td), those appearing at 0ppm as aluminum octahedrons (Oh), and the integration was performed and the values were shown.

Next, the ratio of the tetrahedral structure and the octahedral structure was measured, and the results thereof are shown in table 3.

[ TABLE 3 ]

	Comparative example 1	Comparative example 2	Example 1
				Oh/Td	0.22	0.19	0.19

According to said table 3, the relatively lower the proportion of al (oh) existing in the form of oxide inside the pores or on the surface of the particles outside the framework, as compared to al (td) taken into the interior of the framework, the higher the purity of the sample, and it can be considered as zeolite with well-controlled acid centers. Thus, the lower the Oh/Td ratio, the higher the purity, and this can be referred to as a zeolite with well-controlled acid centers.

Example 2 to example 4

A mordenite synthesis composition was prepared and a gelled product was prepared in the same manner and under the same conditions as in example 1.

The gelated mass was loaded in a synthesis vessel and reacted in an oven at temperatures of 160 c (example 2), 170 c (example 3) and 175 c (example 4), respectively, for 72 hours to crystallize, thereby forming mordenite crystals.

The size of the mordenite crystals obtained in each example was measured in the same manner as in example 1, and the results thereof are shown in Table 4.

Further, for the mordenite crystals obtained in each example, 10 samples were collected, and each sample was photographed with SEM at a magnification of 50k, which is shown in fig. 14. The mordenite crystals obtained in example 1 are also shown together in figure 14.

FIG. 4 shows a schematic view of a drawing

Example No. 2	Example 2	Example 3	Example 4	Example 1
					Crystal size (nm)	59	60	81	105.4

From the results of examples 2 to 4, it was confirmed that the uniformity of the pellets was maintained even if the crystallization temperature was changed when the process conditions and synthesis variables were the same. On the other hand, as is clear from table 4 and fig. 14, the crystal size of the mordenite zeolite tends to increase as the crystallization temperature increases, and the crystal size sharply increases at the crystallization temperatures of 175 ℃ (example 4) and 180 ℃ (example 1). This is because the crystallization is completed faster as the crystallization temperature increases, and the crystal grows rapidly to form a large crystal. From the above results, it is understood that the mordenite-type zeolite having a uniform crystal size can be obtained according to the process of the present invention, and in this case, the crystal size can be controlled by adjusting the crystallization temperature.

Example 5 to example 7

Mordenite crystals were formed in the same manner as in example 1, except that the amount of the structure-inducing substance (TEABr) used was respectively adjusted as shown in examples 5 to 7 of the following table 5. Further, regarding the mordenite crystals obtained in each of examples 5 to 7, a photograph was taken with SEM at a magnification of 50k, and this is shown in fig. 15.

[ TABLE 5 ]

	Example 1	Example 5	Example 6	Example 7
					Amount of TEABr used (g)	1.85	2.31	3.47	4.62
Crystal size (nm)	105	66	56	44

From the results of example 1, example 5 to example 7, it was confirmed that the uniformity of particles was maintained even if the amount of the structure-inducing substance used was changed when the process conditions and synthesis variables were the same. On the other hand, as can be seen from table 5, as the amount of the structure-inducing substance used increases, only the size of the crystals differs, and as the amount of the structure-inducing substance used increases, the seed crystal (seed) is rapidly formed, and the amount of the small-sized particles used increases, and therefore, even if crystallization is performed at the same temperature, the single crystallization of the small particles is simultaneously completed, and the small crystals are formed in a plurality of growth directions. Therefore, from these results, it can be understood that the mordenite-type zeolite having a uniform crystal size can be obtained according to the process of the present invention, and in this case, the crystal size can be controlled by adjusting the amount of the structure-inducing substance used.