KR102307624B1 - Catalyst for production of hydrocarbon oxide using a support having a core-shell structure with enhanced thermal stability, preparation method thereof, and preparation method of hydrocarbon oxide using the same - Google Patents

Abstract

The present invention relates to a catalyst for producing hydrocarbon oxide using a catalyst carrier having a core-shell structure with improved thermal stability, a method for preparing the same, and a method for producing an oxidized hydrocarbon using the same, wherein the catalyst carrier is SiC having high thermal conductivity By including in the shell to suppress the sintering of the catalyst metal even after the synthesis of oxidized hydrocarbons, the life of the catalyst can be extended.

Description

Catalyst for producing oxidized hydrocarbon using a carrier having a core-shell structure with improved thermal stability, a method for preparing the same, and a method for producing an oxidized hydrocarbon using the same PREPARATION METHOD THEREOF, AND PREPARATION METHOD OF HYDROCARBON OXIDE USING THE SAME}

The present invention relates to a catalyst for producing hydrocarbon oxide using a catalyst carrier having a core-shell structure with improved thermal stability, a method for preparing the same, and a method for producing an oxidized hydrocarbon using the same, specifically The present invention relates to a catalyst for producing an oxidized hydrocarbon having a core and a shell structure with a small specific surface area and supporting a metal on a catalyst carrier including SiC in the shell, a method for preparing the same, and a method for producing an oxidized hydrocarbon using the same.

The present invention relates to a catalyst containing a metal, for example, silver, which is used for producing an oxidized hydrocarbon from a hydrocarbon and molecular oxygen or oxygen-containing mixed gas in a gas phase reaction, and a method for producing such a catalyst. It is a known and customary means for the epoxidation of hydrocarbons, for example alkylene, using so-called supported catalysts in which a metal such as silver is attached to a support. Since these supported catalysts are industrially used for 3 to 4 years, the catalyst life is very important. It is known that the main factor of deactivation of catalysts for oxidative hydrocarbon synthesis reaction is sintering of active metals such as silver. This sintering phenomenon is caused by the reaction heat generated on the catalyst surface. If it is not removed, a hot spot is partially created on the catalyst surface, which causes sintering of the active metal. When the active metal is sintered (the size of the active metal is larger) decreases the area of active metal that is exposed, which leads to a decrease in catalytic activity.

In the present invention, a catalyst for oxidized hydrocarbon production using a catalyst carrier having a core-shell structure with increased thermal stability was developed. For the core, an inorganic material with a small specific surface area, for example, α-alumina (α-Al ₂ O ₃ ) is used, and for the shell, silicon carbide (SiC) with excellent thermal conductivity and an inorganic material such as θ-alumina, α-alumina or a mixture thereof was used. The thermal conductivity of α-Al ₂ O ₃ is 30 W/mK, and the thermal conductivity of SiC is 360 to 490 W/mK. Since SiC has a thermal conductivity 12 times higher than that of alumina, the heat of reaction can be effectively dispersed. Accordingly, when the thermal stability of the catalyst carrier is increased, it is possible to effectively suppress the sintering of the active metal. Accordingly, the present invention provides a method of suppressing Ag sintering while maintaining a high hydrocarbon conversion rate and oxidized hydrocarbon selectivity by efficiently using a catalyst carrier with improved thermal stability.

An object of the present invention is to improve the thermal stability of a catalyst for synthesizing an oxidized hydrocarbon from a hydrocarbon by improving the thermal properties of a carrier on which the catalyst is supported.

In order to achieve the above object, the present invention

A catalyst for producing hydrocarbon oxide in which a metal and a cocatalyst are supported on a catalyst carrier having a core-shell structure,

The shell comprises 20 to 40% by weight of SiC,

Components of the core and the shell are each independently selected from the group consisting of silica, alumina, zirconia, and titania. It provides a catalyst for producing oxidized hydrocarbons.

Also, the present invention

(a) mixing and stirring the precursor of the catalyst metal component and ethylenediamine;

(b) absorbing the precursor solution of the catalyst metal component and the cocatalyst in the catalyst carrier having a core-shell structure according to the present invention;

(c) drying the catalyst carrier on which the precursor solution has been absorbed; and

(d) provides a method for preparing a catalyst for producing oxidized hydrocarbons, comprising the step of heat-treating the catalyst carrier at 250° C. under an air flow.

In addition, the present invention provides a method for producing an oxidized hydrocarbon, comprising the step of introducing the catalyst for producing an oxidized hydrocarbon of the present invention into a reactor, and then reacting it with a mixed gas containing hydrocarbon and oxygen.

In the prior art, there is no technique for improving the thermal stability of the catalyst carrier by synthesizing two inorganic materials into one carrier having a core-shell structure and adding SiC to the shell. In the present invention, SiC is introduced into the shell of the catalyst carrier having a core-shell structure in an optimal content, thereby increasing the thermal conductivity of the catalyst carrier to suppress sintering of the active metal, thereby increasing the thermal stability of the catalyst.

1 is a schematic diagram of a catalyst carrier having a core-shell structure containing SiC in a shell according to an embodiment of the present invention.
2 is Ag supported on a core-shell structure catalyst carrier not containing SiC according to Comparative Example 1 of the present invention, and SiC according to Example 1 supported on a core-shell structure catalyst carrier containing 30 wt% This is an SEM image after the synthesis reaction of ethylene oxide using Ag and Ag supported on a core-shell structure catalyst carrier containing 50 wt% of SiC according to Comparative Example 2.

Conventionally, the use of Ag metal as a catalyst for synthesizing ethylene oxide from ethylene and α-Al ₂ O ₃ as a carrier is well known and widely used. The ethylene oxide synthesis reaction and the side reaction, the complete oxidation reaction, are reactions with a large calorific value. Therefore, as the reaction proceeds, sintering of Ag by the heat of reaction tends to occur.

In the present invention, as a means for increasing the thermal stability of the catalyst carrier in order to suppress such sintering, an inorganic material with a small specific surface area is used for the core and SiC and an inorganic material are added to the shell and then the core is coated with a core-shell structure. of the catalyst carrier was developed. In addition, in the present invention, a catalyst for oxidized hydrocarbon production in which a metal and a cocatalyst are supported on the catalyst carrier has been developed.

In one embodiment, the present invention provides

A catalyst for producing hydrocarbon oxide in which a metal and a cocatalyst are supported on a catalyst carrier having a core-shell structure,

The shell comprises 20 to 40% by weight of SiC,

Components of the core and the shell are each independently selected from the group consisting of silica, alumina, zirconia, and titania. It provides a catalyst for producing oxidized hydrocarbons. In one embodiment, the oxidized hydrocarbon is an alkylene oxide.

In one embodiment, the core of the present invention is an aggregate of the component particles and the core is surrounded by the component particles of the shell, and the average diameter of the particles of the shell to the average diameter of the particles of the core is from 1:80 to 1: 150 or 1:90 to 1:130.

In the present invention, when the SiC content in the shell is lower than 20 wt%, the effect of increasing the thermal stability of the catalyst is insignificant, and when the SiC content is higher than 40 wt%, the oxidized hydrocarbon yield is reduced.

In one embodiment, the catalyst carrier of the present invention has a specific surface area of 0.8 to 1.0 m 2 /g.

In one embodiment, the metal supported on the catalyst carrier of the present invention is at least one selected from the group consisting of Ag, Pd and Pt.

In one embodiment, the cocatalyst of the present invention is at least one selected from the group consisting of Cs, Re, Mo, Li, Zr and W.

In one embodiment, the component of the core of the invention is α-alumina (α-Al ₂ O ₃ ).

In one embodiment, the component of the shell of the present invention is θ-alumina, α-alumina, or mixtures thereof.

In one embodiment, the SiC content of the shell of the present invention is 25 to 30% by weight.

In one embodiment, the present invention provides

(a) mixing and stirring the precursor of the catalyst metal component and ethylenediamine;

(b) absorbing the precursor solution of the catalyst metal component and the cocatalyst into the catalyst carrier having a core-shell structure of the present invention;

(c) drying the catalyst carrier on which the precursor solution has been absorbed; and

(d) provides a method for preparing a catalyst for producing oxidized hydrocarbons, comprising the step of heat-treating the catalyst carrier at 250° C. under an air flow.

In one embodiment, the catalyst metal component in step (b) is at least one selected from the group consisting of Ag, Pd and Pt.

In one embodiment, the cocatalyst in step (b) is at least one selected from the group consisting of Cs, Re, Mo, Li, Zr and W.

In one embodiment, the present invention provides a method for producing an oxidized hydrocarbon, comprising the step of introducing the catalyst for producing an oxidized hydrocarbon of the present invention into a reactor, and reacting it with a mixed gas comprising hydrocarbon and oxygen.

In one embodiment, according to the above method, a mixed gas comprising ethylene and oxygen is reacted with the catalyst of the present invention at a temperature of 200 to 250 ° C and a ^{gas hourly space velocity (GHSV) of 3000 to 5000 h -1 to prepare ethylene oxide} can do. In another embodiment, according to the above method, propylene oxide may be prepared by reacting a mixed gas containing propylene and oxygen with the catalyst of the present invention at 200 to 430° C. and atmospheric pressure.

In one embodiment, the mixed gas may further include chlorohydrocarbons such as chloromethane, dichloromethane, chloroethane, and ethylene dichloride (EDC).

In one embodiment, the mixed gas comprises 1 to 5 ppm of ethylene dichloride (EDC).

In one embodiment, the mixed gas uses nitrogen and methane as a balance gas.

In one embodiment, the present invention provides a catalyst composition in which Ag is supported on a catalyst carrier having a core-shell structure of the present invention, wherein 15 to 25% by weight of silver (Ag), 100 to 600 ppm of rhenium (Re), and 50 to 400 ppm It provides a catalyst composition comprising molybdenum (Mo) of 400 to 1000 ppm cesium (Cs) and 1 to 300 ppm lithium (Li).

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Example 1 : Synthesis of alumina carrier with core-shell structure

(1) Boehmite (aluminium oxide hydroxide) and 30 wt% of SiC were added to distilled water (100ml) and stirred.

(2) To the mixed solution from (1) was added nitric acid (1.5 ml).

(3) α-alumina (α-Al ₂ O ₃ ) was added to the mixture from (2) and stirred at room temperature for 30 minutes.

(4) After adding aqueous ammonia (15 ml) to the mixed solution from (3), the mixture was stirred at room temperature for 30 minutes to gelation.

(5) The synthesized carrier from (4) was sieved and dried in an oven (80) for 24 hours.

(6) The dried carrier was calcined at 1100° C. for 10 hours under air flow to obtain _{a catalyst carrier having a core-shell structure (α-Al 2} O ₃ /SiC+θ-alumina and α-alumina mixture). prepared.

Comparative Example 1

_{A catalyst carrier having a core-shell structure (a mixture of α-Al 2} O ₃ /θ-alumina and α-alumina) was prepared in the same manner as in Preparation Example 1 except that SiC was not added.

Comparative Example 2

_{A catalyst carrier having a core-shell structure (a mixture of α-Al 2} O ₃ /SiC+θ-alumina and α-alumina) was prepared in the same manner as in Preparation Example 1, except that 50% by weight of SiC was added.

Experimental Example 1 : Ag supported on a catalyst carrier having a core-shell structure

(1) Silver oxalate (silver oxalate) powder 7g was put in distilled water (7ml) was stirred while cooling to 5 ℃.

(2) 3.5 ml of 92% by weight of ethylenediamine (8% by weight is H ₂ O) was added with respect to the total weight of the solution from (1) and stirred while cooling to 5°C.

(3) Re ₂ O ₇ (37.4 mg) and (NH ₄ ) ₆ Mo ₇ O ₂₄ ? 4H ₂ O (3.7 mg) were respectively dissolved in a mixed solution (1 ml) of ethylenediamine and aqueous ammonia.

(4) LiNO ₃ (28 mg) and Cs ₂ CO ₃ (18.3 mg) were each dissolved in distilled water (1 ml).

(5) The solutions of Re, Mo, Li, and Cs of (3) and (4) were put into the stirred solution of (2) and stirred while cooling to 5°C.

(6) All of the precursor solution completed in (5) was absorbed into 15 g of the catalyst carrier having a core-shell structure prepared in Example 1 and Comparative Examples 1 and 2.

(7) The catalyst carrier absorbing the precursor solution was dried under reduced pressure.

(8) The catalyst carrier dried under reduced pressure was heat-treated at 250° C. for 10 minutes under an air stream. The finished (Re, Mo, Li, Cs)Ag/(?-Al ₂ O ₃ /SiC+θ-alumina and ?-alumina mixture) catalyst contains 20 wt% of silver (Ag), and 360 ppm of rhenium It contains (Re), contains 100 ppm of molybdenum (Mo), contains 750 ppm of cesium (Cs), and contains 140 ppm of lithium (Li).

Experimental Example 2 : Synthesis of ethylene oxide

The oxidative dehydrogenation reaction for synthesizing ethylene oxide from ethylene used a fixed bed catalyst reactor, and after adding the catalysts prepared in Example 1 and Comparative Examples 1 and 2 above, the reaction temperature was 200 to 250° C. and GHSV (Gas Hourly Space Velocity) ) The synthesis reaction of ethylene oxide was carried out under the conditions of ^{3500h -1.}

As a reactant with the catalyst, a mixed gas containing 15 to 30 vol% of ethylene and 1 to 5 ppm of ethylene dichloride (EDC) was used.

Ag was supported according to Experimental Example 1 on the carrier prepared according to Example 1 and Comparative Examples 1 and 2, and ethylene oxide was synthesized according to Experimental Example 2 using each of the three supported catalysts. Ag particle sizes are shown in Table 1 below.

In addition, the SEM image after supporting Ag according to Experimental Example 1 on the carrier prepared according to Example 1 and Comparative Examples 1 and 2, and ethylene oxide synthesis reaction according to Experimental Example 2 using each of the three supported catalysts. is shown in FIG. 2 .

Table 1 shows that Ag was supported on an alumina carrier having a core-shell structure in which SiC was added to the shell (Example 1 and Comparative Example 2) and an alumina carrier having a core-shell structure in which SiC was not added to the shell (Comparative Example 1). Shows the results of applying as a catalyst to the ethylene oxide synthesis reaction. Although there is no difference in the ethylene oxide synthesis reaction results (ethylene conversion rate, ethylene oxide selectivity, ethylene oxide yield) of the catalyst carrying Ag on the catalyst carrier of Comparative Example 1 and Example 1, the Ag particle size after the synthesis reaction was added with SiC. The case of Example 1 was 50 nm smaller.

In addition, as shown in the SEM image result of FIG. 2 , it was confirmed that Ag sintering could be suppressed by adding SiC to the catalyst carrier because the particle size of Ag after the reaction was smaller in Example 1 than in Comparative Example 1.

However, in the case of Comparative Example 2 in which the SiC content was 50% by weight, the ethylene conversion rate was reduced, and thus the ethylene oxide yield was reduced. Therefore, it can be seen that when the content of SiC in the catalyst carrier is 30 wt% in the ethylene oxide synthesis reaction, there is a positive effect of increasing the thermal stability of the catalyst without affecting the ethylene oxide yield.

As described above in detail a specific part of the content of the present invention, for those of ordinary skill in the art, it is clear that this specific description is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Accordingly, it is intended that the substantial scope of the present invention be defined by the appended claims and their equivalents.

Claims (15)

A catalyst for producing hydrocarbon oxide in which a metal and a cocatalyst are supported on a catalyst carrier having a core-shell structure,
A component of the core is α-alumina (α-Al ₂ O ₃ ),
The component of the shell is a mixture of θ-alumina and α-alumina,
The shell comprises 20 to 40% by weight of SiC, a catalyst for producing oxidized hydrocarbons. The catalyst for producing oxidized hydrocarbons according to claim 1, wherein the catalyst carrier has a specific surface area of 0.8 to 1.0 m 2 /g. The catalyst for producing an oxidized hydrocarbon according to claim 1, wherein the metal supported on the catalyst carrier is at least one selected from the group consisting of Ag, Pd and Pt. According to claim 1, wherein the cocatalyst is Cs, Re, Mo, Li, Zr, and at least one selected from the group consisting of W, the catalyst for producing an oxidized hydrocarbon. delete delete The catalyst for producing an oxidized hydrocarbon according to claim 1, wherein the SiC content of the shell is 25 to 30% by weight. (a) mixing and stirring the precursor of the catalyst metal component and ethylenediamine;
(b) absorbing the precursor solution of the catalyst metal component and the cocatalyst into the catalyst carrier having a core-shell structure according to claim 1;
(c) drying the catalyst carrier on which the precursor solution has been absorbed; and
(d) a method for producing a catalyst for producing an oxidized hydrocarbon according to claim 1, comprising the step of heat-treating the catalyst carrier at 250° C. under an air flow. The method of claim 8, wherein the catalyst metal component is at least one selected from the group consisting of Ag, Pd and Pt. The method of claim 8, wherein the cocatalyst is at least one selected from the group consisting of Cs, Re, Mo, Li, Zr and W. 9. A method for producing an oxidized hydrocarbon, comprising the step of adding the catalyst for producing an oxidized hydrocarbon prepared by the method according to claim 8 into a reactor, and reacting it with a mixed gas containing hydrocarbon and oxygen. 12. The method of claim 11, wherein the mixed gas is chloromethane (chloromethane), dichloromethane (dichloromethane), chloroethane (chloroethane) and ethylene dichloride (ethylene dichloride, EDC) further comprising a chlorohydrocarbon selected from the group consisting of The method for producing an oxidized hydrocarbon. The method of claim 12, wherein the mixed gas contains 1 to 5 ppm of ethylene dichloride (EDC). The method of claim 11, wherein the mixed gas uses nitrogen and methane as balance gases. A catalyst composition in which Ag is supported on the catalyst carrier according to claim 1, wherein the catalyst composition comprises 15 to 25 wt% of silver (Ag), 100 to 600 ppm of rhenium (Re), 50 to 400 ppm of molybdenum (Mo), 400 to 1000 ppm of cesium (Cs) and 1 to 300 ppm of lithium (Li).

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