KR20170047938A - Silica alumina aerogel catalysts for producing p-xylene and method for manufacturing p-xylene using the smae - Google Patents

Abstract

Disclosed are a silica alumina aerogel catalyst for producing paraxylene, a production method thereof, and a method for producing paraxylene using the catalyst. The specific surface area of the silica alumina aerogel catalyst ranges from 300 to 500 m^2/g, and the average pore size thereof is 20-30 nm, thereby ensuring high conversion rates for dimethylfuran for a short reaction period in the production of paraxylene from biomass-derived dimethylfuran, while enabling the production of paraxylene with high selectivity.

Description

Technical Field [0001] The present invention relates to a silica alumina airgel catalyst for producing para-xylene, and a method for producing p-xylene,

A silica alumina airgel catalyst for the production of para-xylene and a process for its preparation and a process for preparing para-xylene using the catalyst are disclosed herein.

Lignocellulose, such as wood and herbal oil, is composed of cellulose, hemicellulose and lignin. Cellulose, which is composed of glucose, is converted to a bioalcohol fuel by a biological process Can be converted into various chemical products. In the case of glucose, various chemical reforming reactions can also be converted into transportation fuels. For example, 5-hydroxymethylfurfural may be obtained through a dehydration reaction, and then converted to 2,5-dimethylfuran by hydrogen deoxygenation.

Since 2,5-dimethylfuran has high octane number and energy density, it is attracting attention as a next-generation transportation fuel replacing bioethanol. In recent years, technologies for producing alternative fuels for petroleum as well as fuels for transportation from biomass have attracted much attention. 2,5-Dimethylfuran is used as a catalyst for producing polyester, polyethylene terephthalate (PET), resin ) Polymer products and para-xylene which is used as a solvent for the production of paints.

However, conventionally, in the production of paraxylene, there is a problem that the catalyst is difficult to recycle using a homogeneous catalyst such as a metal triplate, or the reactivity is very low by using activated carbon treated with an acid catalyst as a heterogeneous catalyst. In addition, when a zeolite-based solid acid catalyst is used, the reaction time is very long due to low activity (> 24 hr), which results in inefficiency.

Korean Patent Publication No. 2011-0066933

In one aspect, the present disclosure aims to provide a silica alumina aerogel catalyst for the production of para-xylene with a high specific surface area and a high yield of mesopores.

In another aspect, the present disclosure aims at providing a process for preparing the silica alumina airgel catalyst for the production of para-xylene.

In another aspect, the present disclosure provides a process for preparing para-xylene from dimethylfuran derived from biomass, obtaining a high dimethyl furan conversion over a short reaction time and producing a highly selective para-xylene .

In one aspect, the technique disclosed herein provides a silica alumina airgel catalyst for the preparation of para-xylene having a specific surface area of 300 to 500 m ² / g and an average pore size of 20 to 30 nm.

In one exemplary embodiment, the silica (SiO ₂₎ of the catalyst the molar ratio of aluminum oxide (Al ₂ O ₃₎ is from 1: 2 to 10: 1.

In an exemplary embodiment, the catalyst may be one used in the process for preparing paraxylene from biomass-derived dimethylfuran.

In another aspect, the technique disclosed herein is a method for preparing a silica alumina airgel catalyst for the production of para-xylene, comprising the steps of: (1) preparing a silica alumina gel by a sol-gel method; And (2) adding a supercritical fluid to the gel prepared in the step (1), followed by drying and calcining to obtain an aerosol. The present invention also provides a method for producing a silica alumina aerogel catalyst for producing para-xylene.

In an exemplary embodiment, the supercritical fluid in step (2) may be supercritical carbon dioxide.

In another aspect, the techniques disclosed herein provide a process for preparing paraxylene by reacting dimethylfuran with ethylene in the presence of the catalyst and an organic solvent.

In an exemplary embodiment, the temperature and pressure conditions of the reaction may be from 200 to 300 DEG C and from 20 to 30 bar ethylene initial pressure.

In an exemplary embodiment, the organic solvent may be polar aprotic organic solvents.

In an exemplary embodiment, the polar aprotic organic solvent may be one or more selected from the group consisting of 1,4-dioxane and tetrahydrofuran.

In one aspect, the technique disclosed herein is effective to provide a silica alumina aerogel catalyst for the production of para-xylene with a high specific surface area and a high yield of mesopores.

In another aspect, the techniques disclosed herein are effective in providing a process for preparing the silica alumina airgel catalyst for the production of para-xylene.

In another aspect, the technique disclosed herein is a method for producing paraxylene from dimethylfuran derived from biomass, which method comprises obtaining a high dimethylfuran conversion rate over a short reaction time and producing a high selectivity para xylene .

Figure 1 illustrates the conversion pathway of 2,5-dimethylfuran to para-xylene in accordance with one embodiment of the present disclosure.
FIG. 2 shows the results of nitrogen adsorption analysis of a silica alumina airgel catalyst according to an embodiment of the present invention.
3 shows the pore size analysis results of the silica alumina airgel catalyst according to one embodiment of the present invention.
4 shows the conversion of dimethylfuran to para-xylene using various solid acid catalysts in one experimental example of the present specification.
Figure 5 shows the results of a comparison of the activity of silica alumina airgel catalysts having various silica alumina ratios in one experimental example of the present specification.
6 shows the results of comparing the activities of silica alumina airgel catalysts using various organic solvents in one experimental example of the present specification.

Hereinafter, the present invention will be described in detail.

In one aspect, the technique disclosed herein provides a silica alumina airgel catalyst for the preparation of para-xylene having a specific surface area of 300 to 500 m ² / g and an average mesopore size of 20 to 30 nm.

Usually, the pore size is classified into micropores of 2 nm or less, mesopores of 2 to 50 nm, and macropores of 50 nm or more. In the present specification, the average pore size means an average value of the mesopore diameter of the catalyst calculated from the nitrogen adsorption isotherm at 77 K by the BJH method.

In an exemplary embodiment, the mesopore volume may be 1.0 to 1.4 cm < ³ > / g. Accordingly, during the production of para-xylene, contact between the active sites of the catalyst and the reactants or mass transfer of the reactants and products can be smoothly suppressed, and the selectivity and conversion rate can be increased.

The silica alumina airgel catalyst according to the present invention has an average mesopore size, a mesopore volume, and a specific surface area as described above, so that the conversion and selectivity can be greatly increased when dimethylfuran is produced from para-xylene.

In one exemplary embodiment, the silica (SiO ₂₎ of the catalyst the molar ratio of aluminum oxide (Al ₂ O ₃₎ is from 1: 2 to 10: 1. More specifically, the molar ratio of silica to alumina may be 0.5 to 3, 0.5 to 2, 1 to 3, or 1 to 2, and the effect of producing a remarkably high yield of para-xylene with the molar ratio have.

In an exemplary embodiment, the catalyst may be one used in the process for preparing paraxylene from biomass-derived dimethylfuran.

In another aspect, the technique disclosed herein is a method for preparing a silica alumina airgel catalyst for the production of para-xylene, comprising the steps of: (1) preparing a silica alumina gel by a sol-gel method; And (2) adding a supercritical fluid to the gel prepared in the step (1), followed by drying and calcining to obtain an aerosol. The present invention also provides a method for producing a silica alumina aerogel catalyst for producing para-xylene.

Supercritical fluid is a supercritical fluid in which the material is in a critical state where the two states of the liquid and the gas can not be distinguished from each other and when the vapor pressure is under a temperature and pressure higher than its critical point, Which means the fluid in the fluid.

In an exemplary embodiment, the supercritical fluid in step (2) may be supercritical carbon dioxide.

In an exemplary embodiment, the drying in the step (2) may be carried out at 65 to 75 캜 and 12 to 14 MPa to prepare a catalyst having specific surface area and mesopore growth.

In an exemplary embodiment, drying in step (2) is carried out by raising the temperature to 3 to 10 캜 / min from 500 캜 to 700 캜 and drying for 3 to 6 hours, followed by calcination, whereby the specific surface area and mesopore A catalyst can be produced.

In another aspect, the technique disclosed herein provides a method for producing para-xylene by addition cyclization and dehydration reaction by reacting dimethylfuran with ethylene in the presence of the catalyst and an organic solvent.

In an exemplary embodiment, the temperature and pressure conditions of the reaction may be from 200 to 300 DEG C and from 20 to 30 bar ethylene initial pressure. The ethylene initial pressure refers to the pressure when ethylene gas is injected.

In an exemplary embodiment, the reaction time may be 6 hours or less, specifically 1 to 6 hours.

In an exemplary embodiment, the organic solvent has the effect of obtaining a high dimethylfuran conversion rate and a high selectivity of para-xylene for a short reaction time in the production of para-xylene by using a polar aprotic organic solvent .

In an exemplary embodiment, the polar aprotic organic solvent may be one or more selected from the group consisting of ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethylsulfoxide, 1,4-dioxane and tetrahydrofuran, In the production efficiency of para-xylene, it is preferably at least one selected from the group consisting of 1,4-dioxane and tetrahydrofuran.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Examples 1-5.

AlCl ₃ and TEOS (98%) were used as precursors to produce silica alumina airgel catalysts with various silica alumina ratios. First, AlCl ₃ was dissolved in 61 mL of methanol, then TEOS was added, and the mixture was stirred for about 30 minutes. The mixing amount of AlCl ₃ and TEOS was controlled according to the final silica alumina ratio shown in Table 1. In the case of the catalyst having Si / Al molar ratio of 1, 24.88 g of AlCl _{3 as} compared with 21.41 ml of TEOS was used. Then, 18 mL of a 61% nitric acid aqueous solution was added, and the mixture was stirred for about 30 minutes. Then, 7.2 mL of water was added, and the mixture was stirred for about 1 hour. The silica alumina sol was then gelled by slowly injecting propylene oxide (PO). In the case of the gel, after aging for 2 days, the trapped methanol in the gel was removed through supercritical CO ₂ drying at 70 ° C and 13 MPa. Thereafter, the temperature was raised to 5O < 0 > C / minute to 600 < 0 > C and calcined by keeping it for 5 hours. Through these steps, a silica alumina airgel catalyst with mesopores was produced.

Table 1. Analysis of acid sites by pyridine IR measurement of silica alumina airgel catalyst

As a result, it was confirmed that the catalyst of Example 2 exhibits the best specific surface area and mesopore structure (see FIGS. 2 and 3). As a result, it was confirmed that a catalyst having a molar ratio of silica to alumina of 1 was suitable for a high yield p-xylene catalyst.

Comparative Examples 1 to 7

Zeolite H-BETA (Zeolyst, Comparative Example 1), H-ZSM-5 (Zeolyst, Comparative Example 2), HY (Zeolyst, Comparative Example 3) as a solid acid catalyst having a silica alumina composition, ) And amorphous silica alumina SA (manufactured by Sigma Aldrich, Comparative Example 7) were used. Zirconium oxide (Zr-P, Comparative Example 4), tungsten-zirconium oxide (WZ, Comparative Example 5), and sulfuric acid-treated zirconia (SZ, Comparative Example 6) were prepared. Table 2 shows the pore structure characteristics and the acid concentration of the catalysts used.

Table 2. Nitrogen adsorption and ammonia TPD analysis of catalysts

Experimental Example 1. Preparation of para-xylene using a catalyst

A high-pressure autoclave equipped with a 160 mL impeller was used for the conversion of dimethylfuran to para-xylene. 0.15 g of each of the catalysts of Example 2 and Comparative Examples 1 to 7 was introduced and 0.7 M of 2,5-dimethylfuran (98% purity, Alfa Aesar product, manufactured by Mitsubishi Gas Chemical Company) mixed with 30 mL of n-heptane ) Was added to the reactor. Thereafter, the air contained in the reactor was exhausted with nitrogen, the ethylene gas was filled up to 20 bar, the impeller was rotated at 300 rpm, and the reaction temperature was increased to 250 ° C while stirring. After reaching the reaction temperature, the reaction was maintained for 4 hours and the reaction products were analyzed by GC. The results of the experiment are shown in FIG.

As a result, it was confirmed that the silica alumina airgel catalyst SAA-57 (Example 2) exhibits remarkably high dimethyl furan conversion and high p-xylene yield. Compared with the zirconia-based solid acid catalysts, Comparative Examples 4, 5 and 6 showed very low activity, and H-Beta (Comparative Example 1) and unfused silica alumina catalyst (Comparative Example 7) .

On the other hand, the zeolite-based solid acid catalysts H-ZSM-5 (Comparative Example 2) and H-Y (Comparative Example 3) showed comparatively high activity but lower activity than SAA-57.

Thus, it can be seen that silica alumina airgel catalysts with a Si / Al molar ratio of 1 and a specific surface area of 300 to 500 m ² / g and an average pore size of 20 to 30 nm provide significantly higher paraxylene yields there was.

Experimental Example 2. Preparation of para-xylene using silica alumina airgel catalyst having various silica alumina ratios

0.15 g of each of the catalysts prepared in Examples 1 to 5 was introduced and 1 M of 2,5-dimethylfuran mixed with 30 mL of 1,4-dioxane as a solvent was added to the reactor . Then, the air contained in the reactor was exhausted with nitrogen, the ethylene gas was filled up to 30 bar, the attached impeller was operated at 300 rpm and stirred, and the reaction temperature was increased to 250 ° C. After reaching the reaction temperature, the reaction was maintained for 6 hours, and the reaction products were analyzed by GC. The results of the experiment are shown in FIG.

As a result, it was found that the dimethylfuran conversion and p-xylene yield were greatly affected by the Si / Al molar ratio of the silica alumina aerogels. The p-xylene yield was significantly higher in the SAA-57 (Example 2) catalyst with a Si / Al molar ratio of 1, and the Si / Al molar ratio increased to 2.33 (Examples 3) to 9 (Example 5) The tendency was to decrease.

Experimental Example 3. Preparation of para-xylene according to solvent

1M 2,5-dimethylfuran mixed with 30 mL of 1,4-dioxane, tetrahydrofuran (THF), normal heptane, or isopropanol (IPA) solvent was injected and 0.15 g of the catalyst prepared in Example 2 Were introduced into the reactor. Then, the air contained in the reactor was exhausted with nitrogen, the ethylene gas was filled up to 30 bar, and the attached impeller was operated at 300 rpm to increase the reaction temperature to 250 ° C while stirring. After reaching the reaction temperature, the reaction was maintained for 6 hours, and the reaction products were analyzed by GC. The results of the experiment are shown in Fig.

As a result, it was found that the conversion of dimethylfuran and the yield of p-xylene were greatly influenced by the type of the solvent used in the reaction. The yield of para-xylene was higher when 1,4-dioxane, a polar aprotic solvent, was used than when using non-polar aprotic solvent, normal heptane. In addition, when isopropanol which is a polar quantum solvent was used, a very low p-xylene yield was obtained.

Accordingly, the yield of para-xylene varies depending on the reaction solvent even in the use of the same catalyst, and in this specification, the present invention relates to a process for producing para-xylene which suppresses side reactions by applying a polar aprotic solvent, It was found that the conversion efficiency was improved and the production efficiency of para-xylene was improved.

EXPERIMENTAL EXAMPLE 4 Preparation of para-xylene according to temperature and initial pressure change of ethylene

Paraxylene was prepared in the same manner as in Experimental Example 1 using the catalyst of Example 2 and para-xylene was prepared at various temperatures of 200 to 300 占 폚 and initial pressure of ethylene of 20 to 30 bar, Were compared. 1,4-Dioxane was used as a solvent, and the products were analyzed after 4 hours of reaction, and the results are shown in Table 3 below.

As a result, it was found that the dimethylfuran conversion (X _DMF ) and the p-xylene yield (Y _{p -xylene} ) were greatly influenced by the reaction temperature and the initial ethylene pressure. Specifically, as the reaction temperature was increased from 200 ° C to 250 ° C, the changes in the dimethylfuran conversion and p-xylene yield were markedly increased, and as the reaction temperature was increased from 200 ° C to 300 ° C, the conversion of dimethylfuran and para- While the yield increased, the para - xylene selectivity tended to decrease with increasing side reaction at 300 ℃. In addition, the initial ethylene pressure increased from 20 bar to 30 bar, indicating a slight increase in dimethyl furan conversion and para-xylene yield.

As a result, it was confirmed that the preferable reaction temperature and initial ethylene pressure in the production efficiency of para-xylene were 200 to 300 ° C and 20 to 30 bar.

Table 3.

Having described specific portions of the present invention in detail, it will be apparent to those skilled in the art that this specific description is only a preferred embodiment and that the scope of the present invention is not limited thereby. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (9)

A silica alumina aerogel catalyst for the preparation of para-xylene having a specific surface area of 300 to 500 m ² / g and an average pore size of 20 to 30 nm.
The method according to claim 1,
Silica in said catalyst (SiO _2): The molar ratio of aluminum oxide (Al ₂ O ₃₎ is from 1: 2 to 10: 1, p-xylene for preparing silica-alumina airgel catalyst.
The method according to claim 1,
Wherein the catalyst is used in a process for producing para-xylene from biomass-derived dimethylfuran.
A process for producing a silica alumina airgel catalyst for the production of para-xylene according to any one of claims 1 to 3,
(1) preparing a silica alumina gel by a sol-gel method; And
(2) adding a supercritical fluid to the gel prepared in the step (1), and drying and calcining to obtain an aerosol.
5. The method of claim 4,
Wherein the supercritical fluid in step (2) is supercritical carbon dioxide.
A process for producing para-xylene by reacting dimethylfuran with ethylene in the presence of the catalyst according to any one of claims 1 to 3 and an organic solvent.
The method according to claim 6,
Wherein the temperature and pressure conditions of said reaction are ethylene initial pressures of 200 to 300 DEG C and 20 to 30 bar.
The method according to claim 6,
Wherein the organic solvent is a polar aprotic organic solvent.
9. The method of claim 8,
Wherein the polar aprotic organic solvent is at least one selected from the group consisting of 1,4-dioxane and tetrahydrofuran.

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