KR100711320B1 - Hybrid catalyst for preparing dimethylether and process for the preparation of dimethylether using the same - Google Patents

Abstract

The present invention relates to a hybrid catalyst for preparing dimethyl ether and a method for producing dimethyl ether using the same, including hydrogen, carbon monoxide and carbon dioxide in the presence of a hybrid catalyst physically bonded to a specific methanol synthesis catalyst and a methanol dehydration catalyst using a binder. It provides a hybrid catalyst for the production of dimethyl ether and a method for producing dimethyl ether, characterized in that the synthesis gas to be reacted in one step under a reaction temperature of 150 ~ 400 ℃ and a reaction pressure of 20 ~ 150kg / ㎠.

According to the present invention, in the production of dimethyl ether from a synthesis gas mainly composed of hydrogen and carbon monoxide, by using a specific hybrid catalyst, it is possible to use an economical and efficient process using only one-step direct reaction without going through the conventional two-step reaction. There is an advantage that can be prepared dimethyl ether.

Dimethyl ether, one step reaction, direct synthesis, hybrid catalyst, syngas

Description

Hybrid catalyst for preparing dimethyl ether and method for preparing dimethyl ether {Hybrid catalyst for preparing dimethylether and process for the preparation of dimethylether using the same}

1 is a process flowchart of preparing dimethyl ether through a one-step direct reaction using a synthesis gas as a raw material according to one embodiment of the present invention.

※ Explanation of code about main part of drawing ※

100: dimethyl ether production reactor

200: separator

10: feedstock

20: reaction product mixed gas

30: dimethyl ether

40: unreacted syngas

The present invention relates to a hybrid catalyst for preparing dimethyl ether and a method for producing dimethyl ether using the same. More specifically, in the production of dimethyl ether using synthetic gas, dimethyl ether can be produced through economical and efficient process by simply simplifying the existing two or more reaction steps in one step using a specific hybrid catalyst. The present invention relates to a hybrid catalyst for preparation and a method for preparing dimethyl ether using the same.

Representative conventional techniques for preparing dimethyl ether from syngas include synthesizing methanol using a methanol synthesis catalyst and then preparing dimethyl ether using a methanol dehydration catalyst.

Dimethyl ether is a compound that is attracting attention recently because it can be used as an aerosol propellant, a substitute for diesel fuel, and an intermediate of chemical reactions because its physical and chemical properties are similar to or superior to those of LPG.

The main method for producing dimethyl ether on an industrial scale is to dehydrate methanol using a dehydration catalyst in a fixed bed reactor, and distillate the product to recover high purity dimethyl ether.

In other words, the production process of dimethyl ether up to now had to go through two or more steps of converting syngas into methanol and then converting methanol into dimethyl ether.

In the case of two or more reaction processes, there are problems in that two or more reactors must be operated and the entire reaction must be stopped when one reaction is stopped. In addition, there is a disadvantage in that expensive equipment and operation costs due to the use of two or more reactors have to be paid.

In particular, in the prior art, in the production of dimethyl ether from syngas according to the reaction mechanism shown in the following reaction schemes 1 to 3, the research and development on the technology for producing and using a catalyst composition having activity mainly for production of methanol and dehydration of methanol Has been made.

CO ₂ + 3H ₂ → CH ₃ OH + H ₂ O

2CH ₃ OH → CH ₃ -O-CH ₃ + H ₂ O

CO + H ₂ O → CO ₂ + H ₂

The reactions shown in Schemes 1 and 3 above are catalyzed by a catalyst active for methanol formation from syngas, whereas the reaction shown in Scheme 2 is catalyzed by a catalyst active for methanol dehydration.

Here, the formation of the combined methanol and dimethylether products is limited by chemical equilibrium. In other words, DME synthesis reaction in the synthesis gas is exothermic reaction, the number of moles is reduced. For this reason, there is a disadvantage in that a high pressure is maintained while isothermally reacting by continuously removing the heat generated by the reaction.

As a solution to this problem, Korean Patent No. 289222 discloses a method for preparing a fuel grade dimethyl ether from methanol through a gas phase reaction in a fixed bed reactor, but the method is at least two-step. Due to the above reaction step, the process is complicated and economically disadvantageous.

In addition, Korean Patent No. 241083 discloses a method for preparing dimethyl ether from syngas through a one-step reaction in a slurry reactor, but the method requires the catalytic reaction to proceed under a slurry in a liquid state. This is very demanding and there is a limit to applying it on an industrial scale.

The present invention has been extensively researched to solve the above problems, and as a result, in the production of dimethyl ether using a synthesis gas mainly composed of hydrogen and carbon monoxide as a raw material, the conventional two or more reaction processes are directly reacted in one step. A hybrid catalyst for preparing dimethyl ether that can be carried out was found, and the present invention was completed based on this.

Accordingly, an object of the present invention is to provide a hybrid catalyst for producing dimethyl ether and a method for producing the same, which exhibit a high conversion rate from syngas to methanol and can facilitate the dehydration reaction of methanol.

Another object of the present invention is to provide a method for economically and efficiently preparing dimethyl ether through a one-step direct reaction using the hybrid catalyst.

According to one aspect of the present invention for achieving the above and other objects,

(a) coprecipitation of salts of Cu, Zn, Al, Mn and Ga to prepare a methanol synthesis catalyst;

(b) heat treating γ-alumina at a temperature of 180 to 360 ° C. to produce a methanol dehydration catalyst; And

(c) mixing and molding the methanol synthesis catalyst and the methanol dehydration catalyst together with a binder having an average particle diameter of 10 to 100 nm;

Provided is a method for producing a mixed catalyst for producing dimethyl ether, comprising a.

Here, the binder is preferably selected from the group consisting of carbon black, graphite, pitch and coal tar.

According to another aspect of the present invention, there is provided a hybrid catalyst for preparing dimethyl ether prepared according to the above method.

According to another aspect of the present invention, in the presence of the hybrid catalyst, a synthesis gas containing hydrogen, carbon monoxide and carbon dioxide is reacted in one step at a reaction temperature of 150 to 400 ° C. and a reaction pressure of 20 to 150 kg / cm 2. There is provided a process for producing dimethyl ether.

Here, the reaction is carried out in a fixed bed reactor or a fluidized bed reactor in the gas phase, when the reaction is carried out in a fluidized bed reactor is preferably carried out at a space velocity of 1000 ~ 10000hr ^-1 .

The volume ratio of H ₂ / CO in the synthesis gas is preferably 0.5 to 3.0, and the content of carbon dioxide is 3 to 10% by volume.

The method further includes the step of separating and recovering dimethyl ether after the reaction, wherein the unreacted syngas obtained in the separation and recovery process can be recovered and recycled.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As described above, in the present invention, in synthesizing dimethyl ether using syngas as a feedstock, unlike the conventional method of synthesizing methanol and then synthesizing it back into dimethyl ether, the syngas under a specific hybrid catalyst according to the present invention. In the present invention, a method of preparing dimethyl ether through a direct reaction using only one reactor is provided.

In general, when two processes are separately applied, a methanol synthesis catalyst should be used in a methanol synthesis process and a methanol dehydration catalyst should be used in a methanol dehydration process. However, in the present invention, dimethyl ether may be synthesized at a high conversion rate through a one-step direct synthesis process. Use a hybrid catalyst.

The most important point in the preparation of dimethyl ether catalyst is that the high conversion rate in syngas should be used for methanol synthesis and the dehydration reaction of methanol should be performed smoothly. In addition, these two reactions should have low deactivation while maintaining high conversion and selectivity.

That is, the hybrid catalyst used in the one-step direct synthesis reaction of the present invention should have both a methanol synthesis active point and a methanol dehydration active point.

To this end, in the present invention, first, a salt of Cu, Zn, Al, Cr, Mn and Ga is co-precipitated using a coprecipitation method to prepare a methanol synthesis catalyst. Preferably, when using the coprecipitation method, the temperature is preferably prepared by coprecipitation under constant conditions of 80 ° C, pH 6-9, and stirring speed 300-600 rpm, but is not particularly limited thereto.

Herein, the component ratios of Cu, Zn, Al, Cr, Mn and Ga in the methanol synthesis catalyst are 22.6 to 67.8: 13.5 to 40.6: 2.3 to 6.7: 10.4 to 31.2: 3.8 to 75: 0.9 to 2.7 by weight. It is most suitable for combining with methanol dehydration catalyst and water gas conversion.

Although the particle diameter of the said methanol synthesis catalyst is not specifically limited, It is preferable to grind | pulverize so that it may have an average particle diameter of about 10-100 micrometers.

Next, γ-Al ₂ O ₃ is heat treated at a temperature of 180 to 360 ° C. to prepare a methanol dehydration catalyst. The heat treatment temperature is to remove unnecessary components or lubricants remaining in the pores of the catalyst in the preparation of γ-Al ₂ O ₃ is preferably carried out under the conditions described above.

Although the particle diameter of the methanol dehydration catalyst is not particularly limited, it is preferable to use it by grinding to have an average particle diameter of about 10 to 100㎛.

Finally, the hybrid catalyst according to the present invention is prepared by mixing and molding a methanol synthesis catalyst prepared as described above and a methanol dehydration catalyst together with a binder having an average particle diameter of about 10 to 100 nm.

The binder may be selected from the group consisting of carbon black, graphite, pitch, and coal tar.

Here, the average particle diameter of the binder is preferably 10 to 100 nm, preferably 20 to 30 nm in that different catalysts are mixed well. Another reason is preferable in terms of increasing the contact area between the dehydration catalyst and the synthesis catalyst and inducing the smooth movement of the charge in the catalyst during the reaction.

The content of the methanol synthesis catalyst, the methanol dehydration catalyst and the binder in the hybrid catalyst is not particularly limited, but is preferably 40 to 80%: 20 to 50%: 1 to 10% by weight.

The hybrid catalyst of the present invention prepared as described above not only exhibits high conversion to methanol, but also facilitates the dehydration reaction of methanol, and is excellent in stability.

Hereinafter, a process for preparing dimethyl ether using the hybrid catalyst of the present invention will be described.

1 is a process flowchart of preparing dimethyl ether through a one-step direct reaction using a synthesis gas as a raw material according to one embodiment of the present invention.

Referring to FIG. 1, first, a reactor 100 in which a hybrid catalyst of the present invention is filled with a synthetic gas feedstock 10 including hydrogen, carbon monoxide, and carbon dioxide under a pressure of about 20 to 150 kg / cm 2. ) The internal temperature of the reactor 100 is maintained at a high temperature of about 150 ~ 400 ℃ to operate, and dimethyl ether is produced through a catalytic reaction.

The volume ratio of H ₂ / CO in the syngas supplied as the feedstock 10 is preferably about 0.5 to 3.0. When the volume ratio of H ₂ / CO is less than 0.5, the reactivity of the DME synthesis is reduced due to the lack of H ₂ , and when it exceeds 3.0, the CO conversion rate is increased but productivity is decreased due to the lack of CO.

In addition, the content of carbon dioxide in the synthesis gas is preferably 3 to 10% by volume. When the content of the carbon dioxide is less than 3% by volume, the activity of the catalyst is lowered due to the slow initial reaction, and when the amount of carbon dioxide exceeds 10% by volume, the CO ₂ gas covers a large number of active sites, resulting in poor reactivity. Occurs.

Here, the reaction pressure and the reaction temperature of the dimethyl ether production process is 20 ~ 150kg / ㎠ and 150 ~ 400 ℃, respectively, is most suitable in terms of economic efficiency compared to the reaction.

The reaction can be carried out in both a fixed bed reactor or a fluidized bed reactor in the gas phase. When the reaction is carried out in a fluidized bed reactor it is most suitable in terms of the efficiency of the process is carried out at a space velocity of 1000 to 10000hr ^-1 .

Next, the reaction product mixed gas 20 containing dimethyl ether generated by direct reaction in the first stage of the reactor 100 is transferred to the separator 200 at the rear stage.

Dimethyl ether (30) is separated from the separator (200), subjected to a series of separation / purification processes according to a conventional method, and cooled to be transferred to a storage tank or a supply facility.

On the other hand, the remaining unreacted syngas 40 recovered during this separation is combined with the feedstock stream 10 and re-injected into the dimethylether production reactor 100.

As described above, according to the present invention, there is an advantage that can reduce the device cost and operating cost by simplifying the existing two or more steps of the production process of dimethyl ether in one step. In addition, the amount of carbon dioxide generated can be reduced by separating carbon dioxide from the reaction product mixed gas and re-injecting it as the first step of the synthesis process.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

Example 1

The hybrid catalyst for direct synthesis of dimethyl ether was prepared by preparing a synthesis catalyst and a dehydration reaction catalyst, respectively, and then adding and molding carbon black when mixing them.

(A) The following metal hydrates were used for the preparation of the methanol synthesis catalyst (Cu / Zn / Al / Cr / Mn / Ga). Cu (NO ₃ ) ₂ 3H ₂ O 38.5% by weight, Zn (NO ₃ ) ₂ 6H ₂ O 33.7% by weight, Al (NO ₃ ) ₃ · 9H ₂ O 8.9% by weight, Cr (NO ₃ ) ₃ · 9H 10.7% by weight of ₂ O, 6.8% by weight of Mn (NO ₃ ) ₂ , and 1.4% by weight of Ga (NO ₃ ) ₃ .6H ₂ O were added to distilled water to prepare an aqueous solution. Next, 100% by weight of Na ₂ CO ₃ · 10H ₂ O was made into an aqueous solution and used as a precipitant. The precipitate obtained therefrom is washed several times with distilled water and then water is removed. These precipitates are dried at 80 to 120 ° C. and then calcined to 220 to 500 ° C. The dried precipitates were broken into small pieces of 20 to 100 µm to prepare a methanol synthesis catalyst of the present invention.

(B) As a methanol dehydration catalyst, gamma -alumina was used after heat treatment at a temperature of about 180 to 360 ° C for 12 hours.

(C) The methanol synthesis catalyst obtained in the step (A) and the dehydration catalyst obtained in the step (B) were crushed into small pieces, respectively, and then filtered through a sieve of 400 to 635 mesh, and the two catalysts passed through the mesh were (A) 75 wt% and ( B) 21 wt% and 4 wt% of carbon black having an average particle diameter of about 50 nm were added, mixed and molded to prepare a hybrid catalyst of the present invention.

Example 2

The hybrid catalyst for direct synthesis of dimethyl ether was prepared by preparing a synthesis catalyst and a dehydration reaction catalyst, respectively, and then adding and molding graphite when mixing them.

(A) The following metal hydrates were used for the preparation of the methanol synthesis catalyst (Cu / Zn / Al / Cr / Mn / Ga). Cu (NO ₃ ) ₂ 3H ₂ O 47.7 wt%, Zn (NO ₃ ) ₂ 6H ₂ O 26.4 wt%, Al (NO ₃ ) ₃ 9H ₂ O 11.8 wt%, Cr (NO ₃ ) ₃ 9H 7.9% by weight of ₂ O, 4.5% by weight of Mn (NO ₃ ) ₂ , and 1.7% by weight of Ga (NO ₃ ) ₃ .6H ₂ O were added to distilled water to prepare an aqueous solution. Next, 100% by weight of Na ₂ CO ₃ · 10H ₂ O was made into an aqueous solution and used as a precipitant. The precipitate obtained therefrom is washed several times with distilled water and then water is removed. These precipitates are dried at 80 to 120 ° C. and then calcined to 220 to 500 ° C. The dried precipitates were broken into small pieces of 20 to 100 µm to prepare a methanol synthesis catalyst of the present invention.

(B) As a methanol dehydration catalyst, gamma -alumina was used after heat treatment at a temperature of about 180 to 360 ° C for 12 hours.

(C) The methanol synthesis catalyst obtained in the step (A) and the dehydration catalyst obtained in the step (B) were crushed into small pieces, respectively, and then filtered through a sieve of 400 to 635 mesh, and the two catalysts passed through the mesh were (A) 75 wt% and ( B) 21 wt% and 4 wt% of graphite having an average particle diameter of about 50 nm were added, mixed and molded to prepare a hybrid catalyst of the present invention.

Comparative Example 1

Hybrid catalysts for direct synthesis of dimethyl ether were prepared by preparing a synthetic catalyst and a dehydration catalyst, respectively, as follows, and then molding them without using a specific binder when mixing them.

(A) The following metal hydrates were used for the preparation of the methanol synthesis catalyst (Cu / Zn / Al / Cr / Mn / Ga). Cu (NO ₃ ) ₂ 3H ₂ O 39.8% by weight, Zn (NO ₃ ) ₂ 6H ₂ O 35.7% by weight, Al (NO ₃ ) ₃ · 9H ₂ O 14.5% by weight, Cr (NO ₃ ) ₃ · 9H ₂ O 4.7 _{wt%, Mn (NO 3) 2} 3.8% by weight, and _{Ga (NO 3) 3 · 6H} 2 O 1.5 % by weight to put in distilled water was prepared in an aqueous solution. Next, 100% by weight of Na ₂ CO ₃ · 10H ₂ O was made into an aqueous solution and used as a precipitant. The precipitate obtained therefrom is washed several times with distilled water and then water is removed. These precipitates are dried at 80 to 120 ° C. and then calcined to 220 to 500 ° C. The dried precipitates were broken into small pieces of 20 to 100 µm to prepare a methanol synthesis catalyst.

(B) As a methanol dehydration catalyst, gamma -alumina was used after heat treatment at a temperature of about 180 to 360 ° C for 12 hours.

(C) The methanol synthesis catalyst obtained in the step (A) and the dehydration catalyst obtained in the step (B) were each crushed small and filtered through a sieve of 400 to 635Mesh, and the two catalysts passed through the mesh were (A) 68% by weight and ( B) A mixed catalyst was prepared by mixing and molding 32% by weight.

As described above, the mixed catalysts obtained in Examples 1 and 2 and Comparative Example 1 were charged in a fixed bed reactor for synthesizing dimethyl ether, and synthesis gas containing 58%, 39%, and 3% of hydrogen, carbon monoxide, and carbon dioxide, respectively, by volume. The reaction was carried out using as a feedstock. Here, the reaction temperature of the dimethyl ether synthesis reaction was 260 ℃ and the reaction pressure was 50kg / ㎠.

The reaction product mixture gas obtained therefrom was separated and recovered according to a conventional procedure to obtain dimethyl ether. The conversion, selectivity, and productivity of dimethyl ether through the reaction were measured, and the results are shown in Table 1 below. .

Binder % Conversion Selectivity (%) Productivity gmol / Kg-cat. hr Comparative Example 1 - 37.50 70.96 13.18 Example 1 Carbon black 63 67.41 22.41 Example 2 black smoke 70.55 67.03 22.6

As shown in Table 1, when the hybrid catalyst according to the present invention is used, it can be seen that dimethyl ether can be prepared with excellent conversion, selectivity, and productivity through a one-step direct reaction.

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, and the hybrid catalyst for preparing dimethyl ether according to the present invention and a method for preparing dimethyl ether using the same are not limited thereto. It is apparent that modifications and improvements are possible by those skilled in the art within the technical idea.

As described above, according to the present invention, by manufacturing the dimethyl ether through a one-step direct reaction it is possible to reduce the equipment cost and operating cost. In addition, in the process of recovering and re-injecting unreacted materials, the amount of carbon dioxide generated may be significantly reduced compared to the existing process. In addition, it is possible to replace the carbon dioxide introduced as a raw material with carbon dioxide that is re-introduced as a whole, there is a raw material saving effect.

All simple modifications and variations of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

Claims (7)

(a) coprecipitation of salts of Cu, Zn, Al, Mn and Ga to prepare a methanol synthesis catalyst; (b) heat treating γ-alumina at a temperature of 180 to 360 ° C. to produce a methanol dehydration catalyst; And (c) mixing and molding the methanol synthesis catalyst and the methanol dehydration catalyst together with a binder having an average particle diameter of 10 to 100 nm; Method for producing a mixed catalyst for the production of dimethyl ether comprising a. The method of claim 1, wherein the binder is selected from the group consisting of carbon black, graphite, pitch, and coal tar. A hybrid catalyst for preparing dimethyl ether prepared according to the method of claim 1 or 2. The dimethyl ether, characterized in that the synthesis gas containing hydrogen, carbon monoxide and carbon dioxide in the presence of the hybrid catalyst according to claim 3 under a reaction temperature of 150 ~ 400 ℃ and a reaction pressure of 20 ~ 150kg / ㎠ Manufacturing method. The method of claim 4, wherein the reaction is carried out in a fixed bed reactor or a fluidized bed reactor in a gas phase, and when the reaction is performed in a fluidized bed reactor, a method for preparing dimethyl ether, characterized in that the reaction is performed at a space velocity of 1000 to 10000hr ^-1 . . The method of claim 4, wherein the volume ratio of H ₂ / CO in the synthesis gas is 0.5 to 3.0, and the content of carbon dioxide is 3 to 10% by volume. The method of claim 4, wherein the method further comprises the step of separating and recovering dimethyl ether after the reaction, wherein the unreacted syngas obtained in the separation and recovery process is recovered and recycled (dimethyl), characterized in that for recycling (recycle) Method for preparing ether.

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