Catalyst for synthesis of dimethyl ether from syngas, method for manufacturing the same, and method for synthesizing dimethyl ether using the same

Abstract

A method of making a catalyst for the synthesis of dimethyl ether from syngas includes making a mesoporous ferrierite (FER), and co-precipitating precursors of mesoporous ferrierite and Cu-Zn-Al based oxides (CZA) to obtain a mixed CZA / mesoFER catalyst.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2021-0055653, filed on April 29, 2021, with the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to catalysts for synthesizing dimethyl ether from syngas consisting of carbon monoxide (CO), carbon dioxide (CO2), and hydrogen (H2), methods for manufacturing the catalysts, and methods for synthesizing dimethyl ether using the catalysts. Background Technology

[0004] Due to the rapid development of the chemical industry, atmospheric substances such as CO2, CO, CH4, and NO have increased. x As the concentration of harmful substances such as phosphorus increases, various metal catalysts are actively researching methods to utilize these harmful substances.

[0005] In this process, highly reactive noble metals can be used as metal catalysts, but this is uneconomical. In contrast, the relatively inexpensive CZA catalyst, composed of copper, zinc, and alumina, can successfully convert carbon monoxide (CO) and also efficiently synthesize methanol used in various chemical industries.

[0006] Furthermore, since methanol is converted to dimethyl ether (DME) in an acid catalyst, CZA and the acid catalyst can be synthesized into a mixed catalyst, and this reaction can be represented by reaction schemes 1 and 2.

[0007] [Reaction Scheme 1]

[0008] CO + 2H₂ → CH₃OH

[0009] [Reaction Scheme 2]

[0010]

[0011] On the other hand, following the conversion of carbon monoxide to dimethyl ether, methyl acetate (MA) can be synthesized from dimethyl ether via carbonylation, and ethanol can be synthesized via hydrogenation of methyl acetate. This reaction can be represented by reaction schemes 3 to 5.

[0012] [Reaction Scheme 3]

[0013] 2CO + 4H2 → CH3OCH3 + H2O

[0014] [Reaction Scheme 4]

[0015] CH3OCH3 + CO → CH3COOCH3

[0016] [Reaction Scheme 5]

[0017] CH3COOCH3 + H2→ CH3OH + C2H5OH

[0018] The above reaction is very eco-friendly and economical because ethanol as well as methanol can be selectively synthesized through conversion of carbon monoxide. In addition, since DME and MA synthesized during the reaction are each used as a fuel or an intermediate for various pharmaceutical chemicals, carbon monoxide can be more effectively recovered by controlling these processes. SUMMARY

[0019] The present disclosure provides a catalyst capable of synthesizing dimethyl ether from synthesis gas, which has excellent catalytic activity, increased reactivity due to active mass transfer, and has excellent carbon monoxide (CO) conversion and dimethyl ether (DME) selectivity.

[0020] The present disclosure provides a method for preparing a catalyst.

[0021] The present disclosure provides a method for preparing dimethyl ether (DME) from synthesis gas using a catalyst.

[0022] According to one embodiment, a method for forming a catalyst for synthesizing dimethyl ether from synthesis gas includes preparing a catalyst, the method including preparing a mesoporous ferrierite (FER), and co-precipitating a precursor of the mesoporous ferrierite and Cu-Zn-Al-based oxide (CZA) to obtain a mixed CZA / mesoFER catalyst.

[0023] The preparation of the mesoporous ferrierite can include preparing a ferrierite, leaching silicon from the ferrierite, and performing hydrothermal synthesis of a precursor mixed solution.

[0024] The preparation of the ferrierite can include adding a silica source, an alumina source, and a ferrierite seed to an alkaline aqueous solution to prepare a precursor mixed solution, and synthesizing the ferrierite by hydrothermal synthesis of the precursor mixed solution.

[0025] The amount of addition of the ferrierite seed can be about 2 wt% to about 30 wt% based on the total weight of the prepared ferrierite.

[0026] The hydrothermal synthesis of the precursor mixed solution can be performed at about 120°C to about 180°C for about 96 hours to about 168 hours.

[0027] The silicon leaching of the ferrierite can be performed by adding an organic template material and the ferrierite to an alkaline aqueous solution and stirring at about 10°C to about 80°C for about 1 hour to about 15 hours.

[0028] The organic template material can be a linear organic compound having 15 to 30 carbons and at least one nitrogen.

[0029] The organic templating material can include cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, ammonium dodecyl sulfate, or a combination thereof.

[0030] The organic templating material can be added in an amount of about 10 to about 50 parts by weight based on 100 parts by weight of the magnesium zeolite.

[0031] The hydrothermal synthesis of the silicon leached magnesium zeolite can be performed at about 120 °C to about 180 °C for about 48 hours to about 96 hours.

[0032] The hydrothermal synthesis of the silicon leached magnesium zeolite can further include ion exchanging the Na-type zeolite produced by the hydrothermal synthesis of the silicon leached magnesium zeolite with cations to produce an NH3-type zeolite.

[0033] The hydrothermal synthesis of the silicon leached magnesium zeolite can further include calcining the ion exchanged zeolite at about 450 °C to about 650 °C for about 3 hours to about 6 hours to convert the ion exchanged zeolite to an H-type zeolite.

[0034] The co-precipitation can include preparing a first solution including the mesoporous magnesium zeolite, preparing a second solution including a copper precursor, a zinc precursor, and an aluminum precursor, and preparing a third solution including a basic precipitating agent, and adding the second solution and the third solution to the first solution to perform the co-precipitation.

[0035] The molar ratio of Cu:Zn:Al in the second solution can be (about 10 to about 5):(about 5 to about 1): 1.

[0036] The copper precursor can include an acetate, a hydroxide, a nitrate, or a combination thereof of copper, the zinc precursor can include an acetate, a hydroxide, a nitrate, or a combination thereof of zinc, and the aluminum precursor can include an acetate, a hydroxide, a nitrate, or a combination thereof of aluminum.

[0037] The basic precipitating agent can include sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, or a combination thereof.

[0038] During the co-precipitation, the second solution and the third solution can be added dropwise to the first solution to co-precipitate the mesoporous magnesium zeolite and precursors of a Cu-Zn-Al based oxide (CZA).

[0039] The co-precipitation can be performed at a temperature of about 65 °C to about 75 °C and a pH less than or equal to about 7.

[0040] The co-precipitation can further include allowing the produced precipitate crystals to grow for about 1 hour to about 2 hours.

[0041] The co-precipitation can further include calcining the produced precipitate at about 200 °C to about 600 °C for about 2 hours to about 6 hours.

[0042] According to another embodiment, the mixed CZA / mesoFER catalyst includes a mesoporous ferrierite and a Cu-Zn-Al-based oxide supported on the mesoporous ferrierite.

[0043] The Cu-Zn-Al-based oxide can include CuO of about 40 wt% to about 60 wt%, ZnO of about 35 wt% to about 45 wt%, and Al2O3 of about 5 wt% to about 15 wt%, based on the total weight of the Cu-Zn-Al-based oxide.

[0044] The mixed CZA / mesoFER catalyst can include the Cu-Zn-Al-based oxide of about 0.1 parts by weight to about 5 parts by weight, based on 1 part by weight of the mesoporous ferrierite.

[0045] The mesoporous ferrierite can have a Si / Al ratio of about 5 to about 30.

[0046] The mesoporous ferrierite can have mesopores of about 80% to about 30% by volume and of about 10 nm to about 70 nm in size.

[0047] According to another embodiment, a method for preparing dimethyl ether includes selectively preparing dimethyl ether through a conversion reaction of synthesis gas using a mixed CZA / mesoFER catalyst.

[0048] In the method for preparing dimethyl ether, the synthesis gas can include hydrogen (H2) and carbon monoxide (CO) in a molar ratio of about 1:2.5 to about 1:7.5, and can include carbon monoxide of about 8 mol% to about 30 mol% based on the total amount of the synthesis gas.

[0049] The catalyst of the present disclosure has excellent catalytic activity, increased reactivity due to active mass transfer, and excellent carbon monoxide (CO) conversion and dimethyl ether (DME) selectivity. Accordingly, the catalyst can capture harmful gases inevitably generated, make it into synthesis gas, and then use it to synthesize dimethyl ether and methyl acetate (MA), which are used as fuel, ultimately easily converting harmful substances while selectively synthesizing useful substances, which can lay the foundation for a continuous chemical process in which useful substances can be easily synthesized, and at the same time, can solve environmental problems and create great economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A graph showing the results of XRD measurement of the mixed CZA / mesoFER catalyst in Experiment 3.

[0051] Figure 2 A graph showing the results of N2 adsorption measurement of the mixed CZA / mesoFER catalyst in Experiment 3.

[0052] Figure 3 FIG. 4 is a graph showing the results of N2O chemisorption measurement of the mixed CZA / mesoFER catalyst in Experiment 3.

[0053] Figure 4 FIG. 5 is a graph showing the results of N2O chemisorption measurement of the mixed CZA / mesoFER catalyst in Experiment 4.

[0054] Figure 5A 、 5B FIGS. 6 and 7 show graphs of the results of XPS measurement of the mixed CZA / mesoFER catalyst in Experiment 4. DETAILED DESCRIPTION

[0055] Advantages and features of the present disclosure and methods of accomplishing the same can be understood more readily by reference to the following examples described in detail below. However, the examples should not be construed as limiting the present disclosure. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. Further, unless explicitly stated otherwise, terms defined in commonly used dictionaries should not be ideally or overly construed.

[0056] Further, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0057] In addition, the singular includes the plural unless otherwise specified.

[0058] The method of preparing a catalyst according to one embodiment includes preparing a mesoporous ferrierite (FER), and co-precipitating a precursor of the mesoporous ferrierite and a Cu-Zn-Al-based oxide (CZA) to obtain a mixed CZA / mesoFER catalyst. The catalyst can be used as a catalyst for synthesizing dimethyl ether from synthesis gas.

[0059] For example, the preparation of the mesoporous ferrierite can include preparing a ferrierite, leaching silicon from the ferrierite, and performing hydrothermal synthesis of a precursor mixed solution.

[0060] As the ferrierite, a commercially available ferrierite can be used, or a ferrierite synthesized using a commercially available ferrierite as a seed crystal can be used.

[0061] For example, when the ferrierite is synthesized, the preparation of the ferrierite can include adding a source of silicon dioxide, a source of aluminum oxide, and ferrierite seeds to an alkaline aqueous solution to prepare a precursor mixed solution, and synthesizing the ferrierite by hydrothermal synthesis of the precursor mixed solution.

[0062] The basic aqueous solution can be a basic hydroxide aqueous solution, including sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, or a combination thereof.

[0063] The silica source can include silica sol, silica gel, silica gel, silicon hydroxide, fumed silica, precipitated silica, sodium silicate, tetraalkyl orthosilicate, or a combination thereof.

[0064] The aluminum source can include sodium aluminate (NaAlO2), AICI3, AI2(SO4)3, aluminum hydroxide (AI(OH)3), kaolin, clay, or a combination thereof.

[0065] The silica source and the aluminum source can be added in a molar ratio of about 5: 1 to about 30: 1, for example, about 10: 1. When the molar ratio of silica / aluminum source is less than about 5, the amount of acid sites used as reaction points can be too small, and the reactivity can be severely reduced. When the molar ratio of silica / aluminum source is greater than about 30, aluminum is excessively embedded in the offretite structure, and the strength of the acid spot can be weakened or the offretite characteristic crystal itself can not be formed. In one embodiment, "about" a value can mean exactly the value or greater or less than the value within the tolerance, error, or margin that can be recognized by those of ordinary skill in the art due to measurement or process variation.

[0066] As the offretite seed crystal, a commercial offretite can be used, and the amount of addition of the offretite seed crystal can be about 2 wt% to about 30 wt%, for example, about 2 wt% to about 25 wt%, or about 7 wt% to about 24 wt%, based on the total weight of the offretite finally prepared. When the amount of the offretite seed crystal is less than about 2 wt%, there can be no significant difference in the physical properties thereof from those of the offretite used as an existing seed crystal. When the amount of the seed crystal exceeds about 30 wt%, the concentration of aluminum defect points can increase, resulting in reduced catalyst performance and accelerated deactivation.

[0067] Optionally, a structural derivative material that plays a key role in the formation of the offretite specific framework structure and an organic template material that induces specific physical properties can be additionally added to the precursor mixed solution.

[0068] The organic template material can be a linear organic compound containing 15 to 30 carbons and at least one nitrogen.

[0069] For example, the organic template material can include 10 to 30 carbons, 10 or more carbons forming a chain bond, and can be a material including an ionic moiety. For example, the organic template material can include cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, ammonium dodecyl sulfate, or a combination thereof.

[0070] The structural derivative material can be a nitrogen-containing heterocyclic compound, including pyrrolidine, piperidine, or a combination thereof.

[0071] The addition amount of the structure derivative material can be about 0.2 to about 2.0 mol parts, for example, about 0.8 to about 1.0 mol parts, based on 1 mol part of the silica source. When the amount of the structure derivative material is less than about 0.2 mol parts, the magnesium zeolite structure itself can not be formed, and when it exceeds about 2.0 mol parts, the amount of acid sites generated after synthesis can decrease, and thus the catalyst reactivity can also decrease.

[0072] The organic template material and the structure derivative material can be added in a molar ratio of about 0.01:1 to about 0.5:1. If the amount of the organic template material is too large, the crystal structure of the magnesium zeolite itself is damaged, and synthesis can be difficult.

[0073] The hydrothermal synthesis of the precursor mixed solution can be performed at about 120℃ to about 180℃ for about 96 hours to about 168 hours. If the hydrothermal synthesis temperature is less than about 120℃, the crystallinity of the synthesized magnesium zeolite can decrease, and if it exceeds about 180℃, the particle size of the synthesized catalyst can increase and mesopores can not be formed. If the hydrothermal synthesis time is less than about 96 hours, the crystallinity of the synthesized magnesium zeolite can decrease, and if it exceeds about 168 hours, the crystal size of the synthesized magnesium zeolite can become too large and mesopores can not be formed.

[0074] The silicon leaching of the magnesium zeolite can be performed by adding the organic template material and the magnesium zeolite to an alkaline aqueous solution and stirring the resultant.

[0075] As the magnesium zeolite, a commercial magnesium zeolite or a magnesium zeolite synthesized from a seed crystal can be used, and the magnesium zeolite can be various types, including cations, such as Na-type, NH3-type, and H-type, without limitation.

[0076] During the silicon leaching, the organic template material that plays a key role in forming a specific framework of the magnesium zeolite can be added to the alkaline aqueous solution.

[0077] As the organic template material, a chain-type carbon material including about 10 to 30 carbons can be used. For example, the organic template material can include cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate, ammonium dodecyl sulfate, or a combination thereof.

[0078] During the silicon leaching, the addition amount of the organic template material can be about 10 to about 50 parts by weight, for example, about 20 to about 40 parts by weight, based on 100 parts by weight of the magnesium zeolite. If the amount of the organic template material is less than about 10 parts by weight, the silicon leaching can not be performed, and if it exceeds about 50 parts by weight, the silicon can be excessively leached, and the magnesium zeolite structure itself can be damaged.

[0079] The silicon leaching can be performed at about 10°C to about 80°C for about 1 hour to about 15 hours, for example, at about 25°C to about 70°C or room temperature for about 3 hours to about 12 hours. When the temperature of the silicon leaching is less than about 10°C, the silicon is not sufficiently leached, and thus mesopores can not be properly formed. When the temperature of the silicon leaching exceeds about 70°C, the crystallinity can be reduced and the defect points can increase due to excessive leaching of the silicon. When the time of the silicon leaching is less than about 3 hours, the silicon is not sufficiently leached, and thus mesopores can not be properly formed. When the time of the silicon leaching exceeds about 12 hours, the crystallinity is reduced and the defect points increase due to excessive leaching of the silicon.

[0080] The silicon leaching process introduces irregular pores by randomly creating a large number of defect points by attacking the already synthesized zeolite structure of the ferrierite using an organic material including a long carbon chain. A large amount of carbon components can form pores by being embedded in the ferrierite framework and then being controlled. In addition, the damaged defect points are made into the ferrierite structure again through the hydrothermal synthesis process, but the pores already formed are not destroyed.

[0081] Through the silicon leaching, mesopores having a suitable size can be easily and uniformly introduced into the smooth plate-shaped ferrierite structure, thereby causing an increase in the specific surface area and more effectively co-precipitating Cu.

[0082] After the re-hydrothermal synthesis of the silicon-leached ferrierite and the optional ion exchange, an H-type mesoporous ferrierite can finally be prepared.

[0083] The re-hydrothermal synthesis of the silicon-leached ferrierite can be performed at about 120°C to about 180°C for about 48 hours to about 96 hours. If the re-hydrothermal synthesis temperature is less than about 120°C, the crystallinity of the synthesized ferrierite can be reduced, and if it exceeds about 180°C, the particle size of the synthesized catalyst can increase and mesopores can not be formed. If the re-hydrothermal synthesis time is less than about 48 hours, the crystallinity of the synthesized ferrierite can be reduced, and if it exceeds about 96 hours, the crystal size of the synthesized ferrierite can become too large and mesopores can not be formed.

[0084] In this case, the synthesized zeolite can be a Na-type zeolite, and the NH3-type zeolite can be prepared by ion exchanging the Na-type zeolite with a cation.

[0085] As an example, the ion exchange includes immersing the Na-type zeolite in an aqueous ammonium nitrate (NH4NO3) solution repeatedly 3 to 6 times, and stirring the resultant at about 60°C to about 80°C for 3 hours or more to exchange it into NH4 + ion type, and thus a process of preparing an NH3-type zeolite.

[0086] Further, the method can additionally include removing impurities, structural derivative residues, and organic template residues included in the synthesized zeolite by washing the ion-exchanged zeolite with distilled water, drying at a high temperature, or calcining at a high temperature.

[0087] For example, the high-temperature calcination can convert the ion-exchanged zeolite into an H-type zeolite by calcining the ion-exchanged zeolite at about 450℃ to about 650℃ for about 3 hours to about 6 hours. If the calcination reaction temperature is less than 450℃, removal of the ammonium ion can be insufficient, thus OH bonds (Brønsted acid sites) can not be sufficiently generated, and if it exceeds about 650℃, the ferrierite structure itself can collapse. If the time is less than about 3 hours, removal of the ammonium ion can be insufficient, such that OH bonds (Brønsted acid sites) can not be sufficiently generated, and if it exceeds about 6 hours, the ferrierite structure itself can collapse.

[0088] The co-precipitation can include preparing a first solution including the mesoporous ferrierite zeolite, preparing a second solution including copper, zinc, and aluminum precursors, preparing a third solution including a basic precipitant, and adding the second solution and the third solution to the first solution to co-precipitate them.

[0089] For example, after dispersing the prepared mesoporous ferrierite zeolite in an aqueous solution, a mixed solution of metal precursors including copper, zinc, and aluminum precursors and an aqueous alkali solution are simultaneously dropped and stirred in the zeolite aqueous solution, and the resulting product is subsequently stirred to prepare a mixed CZA / mesoFER catalyst.

[0090] The first solution can be an aqueous suspension solution prepared by mixing the prepared nanosheet ferrite zeolite with an aqueous solution.

[0091] The metal precursors of the copper, zinc, and aluminum precursors in the second solution can include acetate, hydroxide, nitrate, or a combination thereof as a precursor of each metal. For example, the copper precursor can include an acetate, hydroxide, nitrate, or a combination thereof of copper, the zinc precursor can include an acetate, hydroxide, nitrate, or a combination thereof of zinc, and the aluminum precursor can include an acetate, hydroxide, nitrate, or a combination thereof of aluminum.

[0092] The molar ratio of Cu:Zn:Al in the second solution can be (about 10 to about 5):(about 5 to about 1): 1, for example (about 8 to about 6):(about 4 to about 2): 1, or about 7:3:1. If the molar ratio of copper (Cu) is less than about 5, the reactivity can decrease due to insufficient formation of Cu as a reaction site, and if the molar ratio of copper (Cu) exceeds about 10, the reactivity can decrease or rapidly deactivate due to severe aggregation of Cu. If the molar ratio of zinc (Zn) is less than about 1, the hydrophobicity of the catalyst weakens, side reactions can proceed due to water produced during the reaction, and the reactivity can decrease, and if the molar ratio of zinc (Zn) exceeds about 5, the stability of the reaction site Cu can weaken. If the molar ratio of aluminum (Al) is too small, the selectivity of the final product dimethyl ether can decrease, and if it is too large, the stability of the reaction site Cu can weaken.

[0093] In the third solution, the basic precipitant can include sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, or a combination thereof.

[0094] When preparing the first solution to the third solution, the second solution and the third solution can be added dropwise to the first solution to co-precipitate. The co-precipitation can be performed at a temperature of about 65°C to about 75°C and a pH of about 7 or less. By introducing the third solution including the basic precipitant, the pH of the solution in which the precursor solution is dissolved can be adjusted.

[0095] After the second solution including the metal precursor is completely consumed, a process of growing crystals for about 1 to about 2 hours can be additionally included. Further, the method can additionally include a process of washing, drying, and calcining the mixed CZA / mesoFER catalyst, optionally after co-precipitation.

[0096] The drying can be performed by heating the precipitate at a temperature of about 100°C or more, for example, about 100°C to about 150°C for one or more days, and the calcination can be performed by heat treating at about 200°C to about 600°C for about 2 hours to about 6 hours. If the calcination temperature is less than about 200°C, a portion of the metal precursor remains on the surface, and the production of byproducts can increase. When the temperature exceeds about 600°C, the surface acidity of the solid acid catalyst changes according to the change in the oxidation state of the metal oxide, so the production of byproducts such as CO2 can increase.

[0097] The mixed CZA / mesoFER catalyst according to another embodiment includes a mesoporous Mg-based zeolite and a Cu-Zn-Al-based oxide supported on the mesoporous Mg-based zeolite.

[0098] Due to the large specific surface area of the mesoporous ferrierite, the mixed CZA / mesoFER catalyst more widely disperses a large amount of Cu compared to the commercial FER, so that the reaction site Cu in the dimethyl ether conversion reaction of synthesis gas is more uniformly and stably introduced. That is, the mixed CZA / mesoFER catalyst has a high Cu dispersibility, is easily reduced, and has a large Cu metal specific surface area, so that the production process of DME can be improved through the conversion reaction of CO.

[0099] The Cu-Zn-Al-based oxide can include about 40 wt% to about 60 wt% of CuO, about 35 wt% to about 45 wt% of ZnO, and about 5 wt% to about 15 wt% of Al2O3, based on the total weight of the Cu-Zn-Al-based oxide. If the amount of CuO is less than about 40 wt%, a productivity reduction phenomenon occurs due to a decrease in the active site for methanol synthesis, and when it exceeds about 60 wt%, it is difficult to form a suitable catalyst structure with other metals, so that reactivity can be reduced. If the amount of ZnO is less than about 35 wt%, it can be difficult to form a suitable porous material with CuO and Al2O3, and if it exceeds about 45 wt%, the reaction rate for methanol synthesis due to reduction of the active ingredient CuO can be reduced. If the amount of Al2O3 is less than about 5 wt%, it can be difficult to form a structure that is advantageous for the activity of the Cu-Zn-Al-based oxide, and if it exceeds about 15 wt%, reactivity can be reduced due to a decrease in the active site for methanol synthesis.

[0100] The mixed CZA / mesoFER catalyst can include about 0.1 parts by weight to about 5 parts by weight, for example, about 0.5 parts by weight to about 4 parts by weight, of the Cu-Zn-Al-based oxide based on 1 part by weight of the mesoporous ferrierite. If the amount of the Cu-Zn-Al-based oxide is less than about 0.1 parts by weight, the activity of the methanol synthesis reaction can be reduced, and the yield of the entire process can be reduced due to an increase in the conversion rate to CO2, and if it exceeds about 5 parts by weight, the conversion rate to dimethyl ether can be reduced due to a decrease in the active site of the solid acid catalyst.

[0101] The Si / Al molar ratio of the mesoporous ferrierite can be about 5 to about 30. If the Si / Al molar ratio of the mesoporous ferrierite is less than about 5, the amount of acid sites used as reaction sites can be too small to significantly reduce reactivity, and if it exceeds about 30, aluminum can be excessively embedded in the ferrierite structure, and, conversely, the strength of the acid sites can be weakened or the ferrierite characteristic crystal itself can not be formed.

[0102] The mesoporous ferrierite zeolite can include mesopores of about 80 vol% to about 30 vol% based on the total pore volume, and can include, for example, about 70 vol% to about 80 vol% of mesopores of about 30 nm to about 50 nm in size. If the size of the mesopores is less than about 10 nm, the mass transfer capacity can not be improved, and if it exceeds about 70 nm, the crystallinity of the catalyst itself can be reduced. When the volume of the mesopores is less than about 30 vol% based on the total pore volume, the mass transfer capacity can not be improved, and when it exceeds about 80 vol%, the crystallinity of the catalyst itself can be reduced.

[0103] The catalyst of the present disclosure has Brønsted acid sites of copper (Cu) and ferrierite (FER) as reaction points, such that carbon monoxide (CO) reacts with hydrogen (H2) on Cu to be converted into methanol, and the methanol is converted into dimethyl ether (DME) at the Brønsted acid sites of the ferrierite. Specifically, the FER provides reaction points for the conversion of methanol into dimethyl ether, and serves as a carrier in which Cu as a carbon monoxide reaction point is dispersed.

[0104] In particular, since the catalyst contains mesoporous FER, catalytic activity can be significantly increased, and mass transfer is more active, and reactivity is also increased. Specifically, by introducing mesopores in the ferrierite, the physical properties of the ferrierite can be improved, and at the same time, the dispersion of Cu can be increased to prevent Cu particles from agglomerating or easily oxidizing. These effects can result in an increase in CO conversion and an increase in DME selectivity.

[0105] Accordingly, the catalyst can successfully convert synthesis gas composed of carbon monoxide (CO), carbon dioxide (CO2), and hydrogen (H2) into dimethyl ether. Furthermore, dimethyl ether can be easily converted into methyl acetate (MA), an important chemical raw material. At this time, CO and CO2 that react are representative environmental pollutants that are generated after chemical reactions occur at many industrial sites such as steel mills and factories, and are harmful gases that are emitted into the atmosphere. Accordingly, the catalyst captures the harmful gases that are inevitably generated, makes them into synthesis gas, and then uses it to synthesize DME / MA that is used as fuel, ultimately easily converting harmful substances and selectively synthesizing useful substances, which can lay the foundation for a continuous chemical process that exists, and at the same time, solve environmental problems and create great economic benefits.

[0106] The method for preparing dimethyl ether according to another embodiment can selectively prepare dimethyl ether through a conversion reaction of synthesis gas using a mixed CZA / mesoFER catalyst.

[0107] In the process for preparing dimethyl ether, the synthesis gas can include hydrogen (H2) and carbon monoxide (CO) in a molar ratio of about 1:2.5 to about 1:7.5, and can include about 8 mol% to about 30 mol% of carbon monoxide based on the total amount of the synthesis gas. When the synthesis gas includes carbon monoxide in a molar ratio of less than about 2.5, the final dimethyl ether production rate can decrease, and when including carbon monoxide in a molar ratio of more than 7.5, the carbon monoxide conversion rate can decrease. In addition, when the synthesis gas includes carbon monoxide in a molar ratio of less than about 8 mol%, the final dimethyl ether production rate can decrease, and when including carbon monoxide in a molar ratio of more than 30 mol%, the carbon monoxide conversion rate can decrease.

[0108] Hereinafter, specific embodiments of the present disclosure are presented. However, the following described embodiments are for the purpose of specific illustration or explanation of the present disclosure, and the scope of the present disclosure is not limited thereto.

[0109] [Experiment 1: Synthesis of mixed CZA / mesoFER catalyst]

[0110] 1) Synthesis of mesoporous ferrierite

[0111] 1-1) Synthesis of precursor ferrierite by seed synthesis of commercial ferrierite

[0112] A commercial ferrierite (molar ratio of Si / Al: about 10) was used as a seed and added to an alkaline silica solution and completely dissolved therein by stirring for a predetermined period of time. Subsequently, an alumina precursor was added thereto and then completely stirred to perform hydrothermal synthesis at 160°C for 4 days. Herein, the fraction of the added commercial ferrierite seed is advantageously in the range of 5 wt% to 30 wt%. After completion of the seed synthesis by hydrothermal synthesis, the synthesis was completed by washing, drying, and calcination.

[0113] 1-2) Silicon leaching

[0114] The catalyst synthesized by seed synthesis using the commercial ferrierite seed in 1-1) was dissolved in an alkaline aqueous solution in which CTAB was dissolved to perform silicon leaching. Herein, after dissolving 3 g of CTAB in 200 ml of a 0.25 M NaOH aqueous solution, 6 g of the seed-synthesized ferrierite was added thereto and then stirred at room temperature for 3 hours. After stirring, the synthesized catalyst was washed and dried to obtain a powder-type silicon-leached ferrierite particle.

[0115] 1-3) Re-hydrothermal synthesis

[0116] The silicon-leached catalyst prepared in 1-2) was added to the basic silica solution of 1-1), and again the alumina source was added thereto, and then stirred, and again the hydrothermal synthesis was performed. Herein, after performing the re-hydrothermal synthesis at 160°C for 4 days as in 1-1), washing, drying and calcination were performed to obtain a Na-type ferrierite zeolite re-hydrothermally synthesized after silicon leaching.

[0117] 1-4) Ion Exchange

[0118] The Na-type ferrierite zeolite prepared in 1-3) was dissolved in a solution in which 1M ammonium precursor was dissolved, and then stirred at 80°C for 3 hours, and subsequently washed and dried to perform ion exchange. The dried catalyst was ion exchanged again, a total of six times of ion exchange, and then calcined, finally obtaining an H-type mesoporous ferrierite zeolite, which is called mesoFER.

[0119] 2) Coprecipitation

[0120] The prepared mesoporous ferrierite zeolite was used for coprecipitation of Cu / ZnO / Al2O3, and for this process, a first solution, a second solution and a third solution were prepared.

[0121] A first solution including a ferrierite zeolite support was prepared by dissolving 1 g of each of the synthesized mesoporous ferrierite zeolite and the commercial ferrierite zeolite in 200 ml of distilled water.

[0122] A second solution of Cu:Zn:Al in a molar ratio of 7:3:1 was prepared by completely dissolving copper nitrate, zinc nitrate and aluminum nitrate in 200 ml of distilled water.

[0123] A third solution was prepared by completely dissolving 7 g of ammonium carbonate in 200 ml of distilled water as a basic precipitant having a pH of 7 or more.

[0124] The second solution and the third solution were simultaneously dropped into the first solution at an appropriate rate, and at the same time, the first solution was maintained at 75°C and pH 7. The second solution was completely dropped into the first solution, and then aged while being maintained at 75°C and pH 7 for 1 hour. After the aging, the precipitate therein was washed and dried, and then calcined at 350°C for 3 hours to complete the mixed CZA / mesoFER synthesis.

[0125] The synthesized products were called CZA / mesoFER and CZA / CFER according to the FER support used. CZA / mesoFER and CZA / CFER were synthesized by performing coprecipitation in mesoFER, i.e., mesoporous ferrierite zeolite and commercial ferrierite zeolite, respectively.

[0126] (Example 1)

[0127] A CZA / mesoFER catalyst was prepared according to Experiment 1.

[0128] (Comparative Example 1)

[0129] A CZA / CFER catalyst was prepared according to Experiment 1.

[0130] [Experiment 2: Conversion reaction experiment of synthesis gas to dimethyl ether]

[0131] 0.4 g of the synthesized mixed CZA / mesoFER was loaded in a 3 / 8 inch fixed bed reactor as a catalyst for the conversion reaction of synthesis gas to dimethyl ether. Before the reaction, reduction was performed for 5 hours at 350°C under normal pressure using a mixed gas of H2 / N2=5 / 95. After the reduction, a reaction experiment was performed using synthesis gas including carbon monoxide and carbon dioxide (CO / CO2 / N2 / H2=21 / 9 / 4 / 66 and CO / CO2 / N2 / H2 / CH4=8 / 8 / 2 / 60 / 22) in which the reaction pressure was 50 bar and the space velocity was fixed at 5000 L / kg 催化剂 / h. In order to verify the reactivity according to the temperature, the dimethyl ether synthesis reaction was each performed for 10 hours at 220°C, 250°C, 270°C, 290°C and also for 40 hours at a fixed temperature of 270°C.

[0132] The products from the reaction were analyzed with respect to composition by gas chromatography, and the analysis results were used to calculate the carbon monoxide conversion rate during the synthesis of synthesis gas, the methanol and dimethyl ether selectivity, the dimethyl ether yield, etc. in the dimethyl ether synthesis. In addition, in the conversion reaction of dimethyl ether to methyl acetate, the dimethyl ether conversion rate, the methyl acetate selectivity, the deactivation rate, etc. were calculated. The deactivation rate was defined as the average conversion rate from the maximum point of the conversion rate to the end point thereof.

[0133] The synthesis reaction of synthesis gas to dimethyl ether is summarized in Tables 1 to 3.

[0134] (Table 1)

[0135]

[0136] (Table 2)

[0137]

[0138] (Table 3)

[0139]

[0140] Referring to Tables 1 to 3, Example 1 in which co-precipitation was performed in a mesoporous magnesio-alumino-silicate zeolite exhibited improved catalytic activity and high DME productivity regardless of changes in the reaction conditions.

[0141] [Experiment 3: Physical / structural analysis of mixed CZA / mesoFER catalysts]

[0142] To detect the physical / structural properties of the synthesized mixed CZA / mesoFER catalysts, XRD, N2adsorption, and TEM were performed, and the results are shown in Figures 1 to 3 , respectively. In addition, the BET specific surface area results measured by using N2adsorption are shown in Table 4.

[0143] By XRD analysis, while the XRD diffraction pattern specific to the ferrierite and the diffraction pattern of Cu were observed, and by the BET specific surface area results, it was found that the area changed according to the characteristics of the support ferrierite. In addition, by the TEM images, the structure of the support ferrierite affecting the specific surface area change was visualized and clearly confirmed.

[0144] [Experiment 4: Chemical characterization analysis of mixed CZA / mesoFER catalysts]

[0145] The synthesized mixed CZA / mesoFER catalysts were analyzed with respect to chemical properties by performing N2O-chemisorption, XPS, NH3-TPD, and H2-TPR, and the results are shown in Figure 4 and 5, and Table 4, respectively.

[0146] After the N2O-chemisorption analysis, the chemisorption pattern of N2O and Cu was detected to quantitatively obtain the area and dispersion of Cu on the CZA / mesoFER. After performing XPS, the relative ratio of Cu, Zn, and Al metals on the CZA / mesoFER catalyst was measured. As for the NH3-TPD analysis, after NH3 was sufficiently adsorbed in the acid sites on the CZA / mesoFER at 100℃, the temperature was increased up to 450℃, and the amount of adsorbed NH3 was measured. After measuring the area of the TPD pattern obtained after the analysis, this area was used to quantitatively obtain the acid sites on each CZA / mesoFER catalyst. In addition, the H2-TPR analysis was performed to detect the reducibility of the CZA / mesoFER and the stability of the Cu species using H2. Herein, by increasing the temperature up to 400℃ while a gas of H2 / Ar = 5 / 95 was continuously flowed, the TPR spectrum was obtained, and then, by sufficiently using a gas of O2 / He = 1 / 99 again, sufficient oxidation was performed again, and reduction was also performed again under the same conditions. After the analysis, two consecutive reduction temperatures were examined to investigate the ease with which the Cu species was reduced in each support FER, and whether the reducibility thereof was maintained even after oxidation.

[0147] (Table 4)

[0148]

[0149] Referring to Table 4, although the same amount of metal precursors were co-precipitated in the same manner according to the type of the support ferrierite, the overall catalyst properties tended to change. The most significant difference was found in the distribution of the reaction site Cu, i.e. in the mesoporous ferrierite with mesopores, due to the unique structure, a wider pore volume and higher Cu dispersion were observed than in the case of the commercially available ferrierite support, and thus a wider Cu surface area per catalyst weight. According to the properties of the support ferrierite, the catalyst after loading itself exhibited a large specific surface area overall, and even after XPS analysis, a relatively large amount of Cu species was found. However, the number of acid sites in the ferrierite support for the final conversion of synthesis gas into DME was greater than the number of acid sites in the CZA / CFER co-precipitated Cu / ZnO / Al203of the commercially available FER. In addition, as a result of H2-TPR, the degree of reduction of Cu was similar in CZA / CFER and CZA / mesoFER. Therefore, the superior reactivity of CZA / mesoFER was entirely due to the dispersion of Cu and the increase in pore volume and pore size due to the mesoporous structure as a physical property of the catalyst.

[0150] As a result, Cu / ZnO / Al203co-precipitation on a mesoporous ferrierite support formed an excellent mixed CZA / mesoFER, and the reaction sites were optimized, and thus a high DME production rate was confirmed.

[0151] While the present disclosure has been described and illustrated with respect to what are presently considered to be the example embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments. Rather, the disclosure is intended to cover various modifications and equivalent arrangements. The disclosure also includes combinations of the example embodiments in whole or part. The disclosure also includes all of the steps, features, compositions and methods referred to or indicated in the specification, including any two or more, regardless of whether otherwise described, and including those referred to or indicated in the following numbered clauses.

Claims

1. A method of manufacturing a catalyst for synthesizing dimethyl ether from syngas, comprising the steps of: preparing mesoporous ferrierite FER; and co-precipitating precursors of mesoporous ferrierite and Cu-Zn-Al based oxide CZA to obtain a mixed CZA / mesoFER catalyst; wherein the preparation of the mesoporous ferrierite comprises the steps of: adding a silica source, an alumina source, and ferrierite seeds to an aqueous alkaline solution to prepare a precursor mixed solution; synthesizing the ferrierite by hydrothermal synthesis of the precursor mixed solution, wherein the hydrothermal synthesis of the precursor mixed solution is performed at 120℃ to 180℃ for 96 hours to 168 hours; silicon leaching the ferrierite by adding an organic template material and the ferrierite to an aqueous alkaline solution and stirring at 10℃ to 80℃ for 1 hour to 15 hours; and adding the silicon-leached ferrierite and the alumina source to an aqueous silica solution and performing hydrothermal synthesis, wherein the hydrothermal synthesis is performed at 120℃ to 180℃ for 48 hours to 96 hours. 2.The method of claim 1, wherein the ferrierite seeds are added in an amount of 2 wt% to 30 wt% based on the total weight of the prepared ferrierite. 3.The method of claim 1, wherein the organic template material is a linear organic compound having 15 to 30 carbons and at least one nitrogen. 4.The method of claim 1, wherein the organic template material comprises cetyltrimethylammonium bromide, sodium dodecyl sulfate, ammonium dodecyl sulfate, or a combination thereof. 5.The method of claim 1, wherein the organic template material is added in an amount of 10 to 50 parts by weight based on 100 parts by weight of the ferrierite. 6.The method of claim 1, wherein the hydrothermal synthesis of the silicon-leached ferrierite further comprises ion-exchanging a Na-type zeolite prepared by the hydrothermal synthesis of the silicon-leached ferrierite with cations to prepare an NH3-type zeolite. 7.The method of claim 6, wherein the hydrothermal synthesis of the silicon-leached ferrierite further comprises calcining the ion-exchanged zeolite at 450℃ to 650℃ for 3 hours to 6 hours to convert the ion-exchanged zeolite to an H-type zeolite. 8.The method of claim 1, wherein the co-precipitation comprises the steps of: preparing a first solution comprising the mesoporous ferrierite; preparing a second solution comprising a copper precursor, a zinc precursor, and an aluminum precursor; preparing a third solution comprising an alkaline precipitant; and adding the second solution and the third solution to the first solution to perform the co-precipitation. 9.The method of claim 8, wherein a molar ratio of Cu:Zn:Al in the second solution is (10-5):(5-1):

1. 10.The method of claim 8, wherein the copper precursor comprises an acetate, a hydroxide, a nitrate, or a combination thereof of copper, the zinc precursor comprises an acetate, a hydroxide, a nitrate, or a combination thereof of zinc, and the aluminum precursor comprises an acetate, a hydroxide, a nitrate, or a combination thereof of aluminum. 11.The method of claim 8, wherein the basic precipitant comprises sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, or a combination thereof. 12.The method of claim 8, wherein the second solution and the third solution are added dropwise to the first solution to co-precipitate the precursors of the mesoporous ferrierite and the Cu-Zn-Al-based oxide during the co-precipitation. 13.The method of claim 8, wherein the co-precipitation is performed at a temperature of 65℃ to 75℃ and a pH of less than or equal to 7. 14.The method of claim 8, wherein the co-precipitation further comprises allowing the prepared precipitate to grow crystals for 1 hour to 2 hours. 15.The method of claim 8, wherein the co-precipitation further comprises calcining the prepared precipitate at 200℃ to 600℃ for 2 hours to 6 hours. 16.A mixed CZA / mesoFER catalyst manufactured by the method of any one of claims 1-15, comprising a mesoporous ferrierite, and a Cu-Zn-Al-based oxide supported on the mesoporous ferrierite. 17.The mixed CZA / mesoFER catalyst of claim 16, wherein the Cu-Zn-Al-based oxide comprises 40 wt% to 60 wt% of CuO, 35 wt% to 45 wt% of ZnO, and 5 wt% to 15 wt% of Al 2 O 3 based on the total weight of the Cu-Zn-Al-based oxide. 18.The mixed CZA / mesoFER catalyst of claim 16, wherein the mixed CZA / mesoFER catalyst comprises 0.1 parts by weight to 5 parts by weight of the Cu-Zn-Al-based oxide based on 1 part by weight of the mesoporous ferrierite. 19.The mixed CZA / mesoFER catalyst of claim 16, wherein the mesoporous ferrierite has a Si / Al ratio of 5 to 30. 20.The mixed CZA / mesoFER catalyst of claim 16, wherein the mesoporous ferrierite has 80 vol% to 30 vol% of mesopores having a size of 10 nm to 70 nm. 21.A method for synthesizing dimethyl ether, comprising selectively synthesizing dimethyl ether by a conversion reaction of synthesis gas using the mixed CZA / mesoFER catalyst of claim 16. 22.The method of claim 21, wherein in the method for synthesizing dimethyl ether, the synthesis gas comprises hydrogen and carbon monoxide in a molar ratio of 1:2.5 to 1:7.5, and the synthesis gas comprises 8 mol% to 30 mol% of carbon monoxide based on the total amount of the synthesis gas.

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