KR102055284B1 - Heterogeneous catalyst for methanol carbonylation, synthesis method for heterogeneous catalyst, and method for producing acetic acid using heterogeneous catalyst - Google Patents

Abstract

In the heterogeneous catalyst for the carbonylation reaction of methanol of the present invention, a method for preparing the same, and a method for preparing acetic acid, the heterogeneous catalyst for the carbonylation reaction of methanol provides an active substance of rhodium (Rh) and Lewis acid point. Aluminum (Al) is fixed to the mesoporous carbon, characterized in that it contains at least 0.5 parts by weight or more of rhodium and 1 to 5 parts by weight of aluminum relative to 100 parts by weight of mesoporous carbon.

Description

Heterogeneous catalysts for the carbonylation reaction of methanol, a method for preparing a heterogeneous catalyst and a method for preparing acetic acid

The present invention relates to a heterogeneous catalyst for the carbonylation reaction of methanol, a method for producing a heterogeneous catalyst, and a method for producing acetic acid. More specifically, the productivity of acetic acid can be improved through carbonylation of methanol. A heterogeneous catalyst for the carbonylation reaction of methanol, a process for producing a heterogeneous catalyst and a process for producing acetic acid.

Commercially prepared acetic acid production methods can be broadly classified into methods using carbonylation reaction of methanol, ethylene oxidation reaction and ethane oxidation reaction. Among them, a method of using a carbonylation reaction of methanol in a liquid phase is a typical method, and it is known that 60% or more of acetic acid supply in the world is manufactured using a carbonylation reaction of methanol. The carbonylation reaction of methanol uses carbon monoxide and methanol as a reactant, and can be classified into a characteristic commercialization process according to the active metal and reaction phase used.

The Monsanto process, which was invented in the early 1960s, uses rhodium (Rhodium, Rh) as the active metal, a catalyst having a carbonyl group (-CO) and an iodine group (-I) as a functional group on rhodium. Precursors are used (US Pat. No. 3,769,329). The Cativa process invented in the 1990s is a homogeneous catalytic reaction similar to the Monsanto process, but uses iridium (Iri) as a reaction active material, and at least a certain amount of methyl acetate as a reactant to suppress the production of methyl. In addition, there is an advantage that the productivity of acetic acid is significantly improved over the existing process (European Patent EP752406). Both the Monsanto process and the Cativa process have characteristics of homogeneous catalysis, which have the advantage of showing high conversion of methanol and high selectivity of acetic acid, whereas Rh and Ir are adsorbed and dissolved with the product. Due to the occurrence of leaching, there is a technical and economic disadvantage such as low productivity of acetic acid because excessive energy consumption is required in the process for separating the resultant and the catalyst.

In order to solve this problem, recently, a liquid acetic acid production process that has been subjected to heterogenous catalysis of a homogeneous catalyst has begun to be developed, and an acetica process is representative. Acetica process uses Rh ions as the active material of the catalytic reaction, and carbonylation reaction of methanol using a poly 4-vinyl pyridine (P4VP) as a support to prepare a heterogeneous catalyst (US registration) Patent US5,364,964, US 5,576,458).

In the case of the acetica process, it is easy to reuse the catalyst and recover the catalyst from the resultant product, but it has been reported that the conversion rate of methanol and the selectivity of acetic acid are relatively low due to the low content of rhodium which is a reactive active ingredient per catalyst. have.

In addition, methyl acetate may be obtained as a by-product by carbonylation of methanol. The initial methylacetate hydrolysis process was developed at a polyvinyl alcohol manufacturing plant, but this method uses a liquid strong acid catalyst such as hydrochloric acid or sulfuric acid during hydrolysis. Since it must be accompanied by a multi-stage separation and purification process for separating and separating the reactants, there are disadvantages in that the cost of investment or operating cost is high.

Recently, a process of proceeding the reaction and distillation in the same distillation column by using reactive distillation technology has been developed. However, the reaction proceeds in the gaseous phase and the liquid phase, so that the material transfer efficiency is low and the volume of the reaction part is relatively large. There is this. In addition, due to the difficulty of catalyst packaging (packaging) has a disadvantage of high equipment investment costs, expensive catalysts are easily worn (Korea Patent Publication No. 10-2000-00397888).

One object of the present invention is to provide a heterogeneous catalyst for the carbonylation reaction of methanol, which can solve the disadvantage of the conventional homogeneous catalyst and improve the productivity of acetic acid.

Another object of the present invention is to provide a method for preparing a heterogeneous catalyst.

It is still another object of the present invention to provide a method for preparing acetic acid using the heterogeneous catalyst to improve productivity.

Heterogeneous catalyst for the carbonylation reaction of methanol for one purpose of the present invention is rhodium (Rh) and aluminum (Al) providing a Lewis acid point is immobilized in mesoporous carbon, but mesoporous nitriding It is characterized by containing at least 0.5 parts by weight or more of rhodium and 1 to 5 parts by weight of aluminum relative to 100 parts by weight of carbon.

In one embodiment, the weight ratio (Al / Rh) of aluminum and rhodium may be 0.5 to 2.5.

In one embodiment, with respect to 100 parts by weight of mesoporous carbon nitride in the heterogeneous catalyst, rhodium is 2 to 5 parts by weight, aluminum is included in 1.25 to 3 parts by weight, the weight ratio of aluminum and rhodium (Al / Rh) May be 0.5 to 1.5.

In one embodiment, the specific surface area of mesoporous carbon nitride in the heterogeneous catalyst is 600 to 2,000 m ² / g, the average pore size of the pores contained in the mesoporous carbon may be 2 nm to 10 nm. .

In one embodiment, the heterogeneous catalyst causes the conversion of methanol to acetic acid in the carbonylation of methanol to be at least 94 carbon mole% or more.

In one embodiment, the aluminum of the heterogeneous catalyst is converted to acetic acid by hydrolysis by reverse esterification of methyl acetate produced as an intermediate by-product in the carbonylation reaction of methanol.

In one embodiment, the heterogeneous catalyst allows the yield of acetic acid produced by carbonylating methanol to be at least 57% or higher.

In one embodiment, the hexamethylenetetramine self-polymerizes the porous silica template using a porous silica template, hexamethylenetetramine, an aluminum precursor, and a rhodium precursor of the heterogeneous catalyst, thereby restructuring carbon and nitrogen. Mesoporous carbon may be formed, and rhodium and aluminum derived from an aluminum precursor and a rhodium precursor may be formed by immobilization on the mesoporous carbon.

A method for producing a heterogeneous catalyst for the carbonylation reaction of methanol for another object of the present invention, using a porous silica template, hexamethylenetetramine, aluminum precursor and rhodium precursor, hex to the porous silica template Methylenetetramine is self-polymerized to cause restructuring of carbon and nitrogen to form mesoporous carbon nitride; And removing the porous silica template, wherein aluminum and rhodium are immobilized on the mesoporous carbon in the step of forming the mesoporous carbon.

In one embodiment, the step of forming the mesoporous carbon nitride may be performed by heat treatment at a temperature of 600 to 900 ℃ under a nitrogen atmosphere.

In one embodiment, the forming of the mesoporous carbon nitride may include preparing a mixed aqueous solution in which a porous silica template, hexamethylenetetramine, an aluminum precursor, and a rhodium precursor are dispersed in distilled water; Drying the mixed aqueous solution under reduced pressure; And heat-treating the reduced pressure dried material to cause restructuring of carbon and nitrogen.

In one embodiment, the aluminum precursor and the rhodium precursor are mixed so that the weight ratio (Al / Rh) of aluminum and rhodium is 0.5 to 2.5, and the meso group formed by the self polymerization of hexamethylenetetramine in the step of forming the mesoporous carbon nitride. Rhodium may be 0.5 to 5 parts by weight, and aluminum may be immobilized to 1 to 5 parts by weight based on 100 parts by weight of the carbonaceous carbon.

In one embodiment, the porous silica template has a specific surface area of 200 m ² / g or more, an average pore size of 4 nm or more, and the mesoporous carbon nitride formed by self polymerization of hexamethylenetetramine with respect to the porous silica template. The specific surface area is 600 to 2,000 m ² / g, and the average pore size of the pores included in the mesoporous carbon nitride may be 2 nm to 10 nm.

According to another aspect of the present invention, a method of preparing acetic acid includes rhodium (Rh), which is an active material, and aluminum (Al), which provides a Lewis acid point, in which mesoporous carbon is immobilized to 100 parts by weight of mesoporous carbon nitride. Converting methanol to acetic acid by performing a carbonylation reaction on methanol using carbon monoxide in the presence of a heterogeneous catalyst containing at least 0.5 parts by weight or more of rhodium and 1 to 5 parts by weight of aluminum. .

In one embodiment, the step of converting methanol may be performed by injecting a carbon monoxide-containing gas into a solution containing methanol to react at a temperature of 150 to 200 ℃. At this time, the carbon monoxide may be injected into the solution containing the methanol at a pressure of 10 to 70 bar.

In one embodiment, in the step of converting methanol, the aluminum of the catalyst may be converted to acetic acid by hydrolysis by reverse esterification of methyl acetate produced as an intermediate by-product in the carbonylation reaction of methanol.

According to the heterogeneous catalyst for the carbonylation reaction of methanol, the method for preparing the heterogeneous catalyst, and the method for preparing acetic acid, rhodium as the active material and aluminum as the promoter have both a large specific surface area and a meso-scale pore size. Since it is immobilized in the mesoporous carbon nitride having, the properties of carbon nitride having abundant internal electron retention and the interaction between aluminum and rhodium can be enhanced to increase dispersibility of aluminum and rhodium. The strong interaction between rhodium and mesoporous carbon nitride can suppress the phenomenon of rhodium which is an active substance in the carboxylation reaction, and prevent the catalyst from being deactivated due to self aggregation. Accordingly, it is possible to improve the stability of the catalyst and securing the performance of the long-term catalyst.

In addition, the heterogeneous catalyst according to the present invention has the advantage that it can be easily separated and recovered from the product after the reaction through a simple separation process such as filtration, the process in the liquid phase reaction to synthesize acetic acid from the carbonylation reaction of methanol and carbon monoxide Effective hydrolysis of methyl acetate produced as a by-product can be carried out to improve the selectivity with acetic acid. Therefore, there is an advantage that can provide excellent selectivity to acetic acid with a high conversion of methanol in the manufacturing process of acetic acid.

1 is a graph showing methanol conversion and acetic acid selectivity when using heterogeneous catalysts according to Examples 1 and 6 and Comparative Examples 2 and 3 according to the present invention.
2 is a graph showing methanol conversion and acetic acid selectivity when using heterogeneous catalysts according to Examples 1 to 5 and Comparative Examples 1 and 4 according to the present invention.

Hereinafter, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprises" or "having" are intended to indicate that there is a feature, step, operation, component, part, or combination thereof described on the specification, and one or more other features or steps. It is to be understood that the present invention does not exclude, in advance, the possibility of the presence or the addition of an operation, a component, a part, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Heterogeneous Catalyst

The heterogeneous catalyst for carbonylation of methanol of the present invention includes mesoporous carbon nitride in which rhodium (Rh) and aluminum (Al) are immobilized. The heterogeneous catalyst for the carbonylation reaction of methanol according to the present invention is a solid compound, the solid compound can be defined as a heterogeneous catalyst by the catalyst of the carbonylation reaction of liquid methanol, the carbonylation reaction is Occurs on the surface of the heterogeneous catalyst.

Mesoporous carbon, which is a support on which rhodium and aluminum are immobilized in a heterogeneous catalyst, has a form in which meso-scale pores are interconnected three-dimensionally, and is represented by Chemical Formula C ₃ N ₄ , It is a carbon material containing nitrogen in which carbon and nitrogen form covalent bonds. Mesoporous carbon nitride includes all cases having alpha (α), beta (β), cubic, pseudocubic, or graphite. Since mesoporous carbon nitride has a high nitrogen content, it has a high internal electron mobility. Meso-scale means a size included in the range of 2 nm to 50 nm, the average pore size of the mesoporous carbon in the present invention may be 2 nm or more.

Mesoporous carbon nitride has a specific surface area of at least 600 m ² / g or more. Mesoporous carbon nitride has a ratio of 600 m ² / g to 2,000 m ² / g in order to maximize the dispersibility of rhodium and aluminum and to ensure the catalytic reactivity so that the carbonylation reaction can occur stably on the surface of the heterogeneous catalyst. It is desirable to have a surface area. More preferably, the graphite mesoporous carbon having a specific surface area of 800 m ² / g to 1,500 m ² / g as mesoporous carbon has increased binding strength with active metal components due to the presence of abundant base point. Since the stability of the catalyst is increased, it is used as a support for the heterogeneous catalyst of the present invention. At this time, the graphite mesoporous carbon nitride preferably has an average pore size of 2 nm to 10 nm.

In the heterogeneous catalyst according to the present invention, rhodium acts as an active material of the carbonylation reaction of methanol to become a catalyst for substantially carbonylating methanol on the surface of the heterogeneous catalyst, and aluminum is a promoter of the carbonylation reaction. Play a role.

Since aluminum is immobilized on mesoporous carbon and included in the heterogeneous catalyst, the Lewis acid point of the heterogeneous catalyst is increased, and the catalytic activity of the heterogeneous catalyst according to the present invention is improved due to the increase of the acid point. In addition, the use of heterogeneous catalysts with increased acidity can enhance the retro-esterification of methyl acetate even under the same reaction conditions. Reverse esterification of methyl acetate may improve the selectivity of acetic acid. Even if methyl acetate is produced as an intermediate by-product, hydrolyzate may be hydrolyzed, so acetic acid may be additionally produced, thereby simplifying the reaction process and the separation process.

At this time, the mesoporous carbon becomes a support on which rhodium and aluminum are immobilized, so that rhodium and aluminum interact strongly with the mesoporous carbon so that rhodium and aluminum are evenly distributed in a network structure in which pores of mesoporous carbon nitride are formed. Can be. This makes it possible to easily separate the product of the carbonylation reaction and the heterogeneous catalyst using a simple separation process such as filtration, to prevent or minimize the leaching of rhodium into the reaction product, and to prevent self-aggregation of rhodium. It can prevent, and can ensure the stability of a heterogeneous catalyst and long-term catalyst performance.

With respect to 100 parts by weight of mesoporous carbon nitride in the heterogeneous catalyst according to the present invention, the immobilized rhodium content is contained at least 0.5 parts by weight or 5 parts by weight or less. Preferred at If the content of rhodium is less than 0.5 parts by weight, there is a problem that the catalytic reaction occurs insignificantly because the active material is too small, at least 0.5 parts by weight or more is included. More preferably, the content of rhodium is 2 parts by weight or more based on 100 parts by weight of mesoporous carbon nitride.

However, since the rhodium itself is an expensive metal, when introduced in excess of 5 parts by weight, the production of the catalyst is expensive, and thus the productivity of the catalyst production and the production of acetic acid may be lowered. Do.

Most preferably, the content of rhodium may be 2 to 3 parts by weight based on 100 parts by weight of mesoporous carbon nitride.

In addition, with respect to 100 parts by weight of mesoporous carbon nitride in the heterogeneous catalyst of the present invention, the content of immobilized aluminum may be 1 to 5 parts by weight. If the aluminum content is less than 1 part by weight, the effect of increasing the acid point in the carbonylation reaction of methanol is minimal, resulting in low methanol conversion and acetic acid selectivity. Therefore, the aluminum content should be at least 1 part by weight based on 100 parts by weight of mesoporous carbon nitride. In addition, when the aluminum content is more than 5 parts by weight, the problem of Rh activity decreases due to interaction with Rh, an active metal component of the catalyst, and the adsorption to the base point of carbon nitride selectively, thereby reducing the dispersibility of Rh. There is a problem.

In this case, the weight ratio (Al / Rh) of aluminum and rhodium immobilized in the heterogeneous catalyst according to the present invention may be 0.5 to 2.5. Preferably, the weight ratio (Al / Rh) of aluminum and rhodium may be 0.5 to 1.25.

Method for producing heterogeneous catalyst

The heterogeneous catalyst according to the present invention described above can be produced using a template of silica as a template. The silica mold is formed inside the carbon nitride when the heterogeneous catalyst is formed by carburization using a source capable of forming carbon nitride and a rhodium precursor or an aluminum precursor, and the silica mold is selectively removed through an extraction process. This allows the carbon nitride to have mesoporosity.

In order to prepare a heterogeneous catalyst by using a silica template, a carbon nitride support and a silica template prepared using a rhodium precursor, an aluminum precursor, and a hexamethylenetetramine as a source of carbon are contained in a relatively high base point. do.

As the rhodium precursor or the aluminum precursor, ammonium salts, acetates, hydroxides, nitrates, halides, phosphates, perchlorates, sulfates and the like of metals may be used, and these may be used alone or in combination of two or more. At this time, in order to enhance the activity of the heterogeneous catalyst according to the present invention, the weight ratio (Al / Rh) of aluminum and rhodium is set within the range of 0.5 to 2.5, the content of rhodium is 2 weight based on 100 parts by weight of mesoporous carbon nitride It is good to be more than a wealth.

As a silica mold, it is preferable to use a specific surface area of at least 200 m ² / g or more, and a pore size of the silica mold having a particle diameter of 4 nm or more. By producing mesoporous carbon nitride using such a silica template, the mesoporous carbon can be provided with pores having an average pore size of 2 nm to 10 nm, and the specific surface area of the mesoporous carbon nitride is 600 m ^2. / g to 2,000 m ² / g. As an example of a silica template, SBA-15, KIT-6, MCM-41, FSM-16, etc. can be used.

For example, in a state in which a silica mold solution is prepared by mixing a silica mold with distilled water, a rhodium precursor, an aluminum precursor, and hexamethylenetetramine may be mixed with the silica template solution.

A rhodium precursor, an aluminum precursor, hexamethylenetetramine, and a silica mold are mixed to heat the catalyst under a nitrogen (N ₂ ) atmosphere in a state where aluminum, rhodium, and hexamethylenetetramine are uniformly disposed in the silica mold to prepare a catalyst precursor. .

Heat treatment may be performed at 600 to 900 ℃. In one example, it is heated to 600 to 900 ℃ at a temperature increase rate of 1 to 4 ℃ / min in a nitrogen atmosphere, and maintained at 600 to 900 ℃ for 5 hours.

In this heat treatment process, hexamethylenetetramine self-polymerizes to form carbon nitride through rearrangement of carbon and nitrogen, and rhodium and aluminum derived from rhodium precursor and aluminum precursor are immobilized on carbon nitride.

At this time, since the silica template is included in the carbon nitride, an extraction process of the silica template to remove the silica template is performed. The extraction process may use a strong basic solution or a strong acid solution. For example, in the extraction process, an aqueous sodium hydroxide solution can be used, and the aqueous sodium hydroxide solution can be used by dissolving 2 M sodium hydroxide in 75 to 100% by weight of distilled water.

According to the above process, a heterogeneous catalyst according to the present invention which is in the form of a powder in solid form and described above can be prepared.

How to prepare acetic acid

In the method for producing acetic acid according to the present invention, the heterogeneous catalyst described above is used.

As a reactant for preparing acetic acid, methanol and carbon monoxide may be used, and iodomethane (CH ₃ I) and distilled water may be used as an activation promoter. For example, as a liquid reactant, methanol, methane iodide and distilled water may be mixed in a molar ratio of 10:10:10 to 80:50:50.

The carbonylation reaction to produce acetic acid is carried out at reaction temperature conditions in the range of 150 to 250 ° C. and pressure conditions in the range of 10 to 70 bar. Performing within these reaction temperature and pressure conditions may improve the reaction rate and the selectivity of acetic acid.

Hereinafter, the preparation and characteristics of the heterogeneous catalyst according to the present invention will be described in more detail with reference to specific examples. In the following, the mesoporous heterogeneous catalyst prepared by the nano-replication method using a silica template using SBA-15 is represented by Al (x) Rh (y) -mpg-C ₃ N ₄ , where mpg represents mesoporous graphitic. It is shown that aluminum is x parts by weight and rhodium is y parts by weight based on 100 parts by weight of the mesoporous carbon nitride.

Example 1 Al (1.25) Rh (2.0) -mpg-C ₃ N ₄  Preparation of Heterogeneous Catalyst

After mixing 3 g of SBA-15 with 160 mL of distilled water, 10.2 g of hexamethylenetetramine, 0.45 g of Al (NO ₃ ) ₃ and 0.65 g of Rh (NO ₃ ) ₃ were added to the SBA-15 solution. It stirred at the speed of 180 rpm per minute in the thermostat conditions maintained 60 degreeC. After confirming that hexamethylenetetramine, aluminum nitrate and rhodium nitrate were completely dissolved in distilled water, drying under reduced pressure was performed at 65 ° C.

Thereafter, the resultant was poured into an 80 ° C. circulation dryer and dried for about 12 hours. The obtained dried product was added to a quartz reactor, and heat treatment was performed while flowing nitrogen gas at a flow rate of 50 mL / min.

After the heat treatment, the silica mold was removed using a 2 M NaOH solution, followed by filtration and washing with distilled water, dried in an oven at 80 ° C. for 12 hours, and finally, black powdery Al (1.25). A heterogeneous catalyst of Example 1 prepared according to Preparation Example 1 of Rh (2.0) -mpg-C ₃ N ₄ was prepared.

Examples 2-6

0.65 g of Rh (NO ₃₎ for ₃ Al (NO _{3) 3} with 0.54 g of using, and is through the preparation of a heterogeneous catalyst according to Preparation Example 1 is substantially the same method of Example 2 Al, except that A heterogeneous catalyst of (1.5) Rh (2.0) -mpg-C ₃ N ₄ was obtained.

Also, except that Al (NO ₃ ) ₃ was used as 0.72 g, 0.90 g and 1.08 g, the same method as in Example 3 to 5 was carried out in the same manner as in the preparation of the heterogeneous catalyst according to Preparation Example 1. Al (2.0) Rh (2.0) -mpg-C ₃ N ₄ , Al (2.5) Rh (2.0) -mpg-C ₃ N ₄ , and Al (3.0) Rh (2.0) -mpg-C ₃ N ₄ heterogeneous system A catalyst was obtained.

In addition, the 0.0.81 g Rh (NO ₃₎ for ₃ Al (NO _{3) 3} except that the 0.45 g is through the preparation of a heterogeneous catalyst according to Preparation Example 1 and in substantially the same manner, the exemplary The heterogeneous catalyst of Al (1.25) Rh (2.5) -mpg-C ₃ N ₄ of Example 6 was obtained.

Comparative Examples 1 to 4

Rh (2.0) -mpg-C ₃ N ₄ heterogeneous catalyst of Comparative Example 1, in which only rhodium was immobilized, was subjected to the method according to Preparation Example 1 except that Al (NO ₃ ) ₃ was not used. Got it.

In addition, Al (1.25) Rh (1.0) -mpg- of Comparative Example 2, except that 0.45 g of Al (NO ₃ ) ₃ and 0.33 g of Rh (NO ₃ ) ₃ were used. A C ₃ N ₄ heterogeneous catalyst was obtained.

Al (1.25) Rh (1.5) -mpg-C ₃ of Comparative Example 3 was subjected to substantially the same process as that for preparing the heterogeneous catalyst of Comparative Example 2, except that 0.49 g of Rh (NO ₃ ) ₃ was used. An N ₄ heterogeneous catalyst was obtained and Al (1.0) Rh of Comparative Example 4 was obtained by the method according to Preparation Example 1, except that 0.36 g of Al (NO ₃ ) ₃ and 0.65 g of Rh (NO ₃ ) ₃ were used. (2.0) -mpg-C ₃ N ₄ heterogeneous catalyst was obtained.

Characteristic 1: Nitrogen adsorption / desorption and BET / BJH pore analysis

For each of the heterogeneous catalysts according to Examples 1 to 6 and Comparative Examples 1 to 4 prepared above, nitrogen adsorption / desorption and BJH (Barret-Joyner-Halenda) pore size analysis were performed.

Nitrogen adsorption / desorption isotherm curves were obtained at 77 K using Trimeri 3020 (trade name) of Micromeritics (Company name), and the specific surface area of the catalyst was obtained from Brunaure-Emmett-Teller (BET) and BJH equations. Pore volume, average pore size were calculated. The results are shown in Table 1 below.

division Catalyst name Al / Rh
Weight ratio Specific surface area
(m ² / g) Pore volume
(cm ³ / g) Average pore size (nm) Example 1 Al (1.25) Rh (2.0) -mpg-C ₃ N ₄ 0.625 1502 0.83 2.7 Example 2 Al (1.5) Rh (2.0) -mpg-C ₃ N ₄ 0.75 861 0.55 3.0 Example 3 Al (2.0) Rh (2.0) -mpg-C ₃ N ₄ 1.00 822 0.44 2.6 Example 4 Al (2.5) Rh (2.0) -mpg-C ₃ N ₄ 1.25 843 0.48 2.8 Example 5 Al (3.0) Rh (2.0) -mpg-C ₃ N ₄ 1.50 884 0.55 3.0 Example 6 Al (1.25) Rh (2.5) -mpg-C ₃ N ₄ 0.50 1011 0.56 2.7 Comparative Example 1 Rh (2.0) -mpg-C ₃ N ₄ 0 832 0.74 3.8 Comparative Example 2 Al (1.25) Rh (1.0) -mpg-C ₃ N ₄ 1.25 935 0.52 2.7 Comparative Example 3 Al (1.25) Rh (1.5) -mpg-C ₃ N ₄ 0.833 918 0.51 2.7 Comparative Example 4 Al (1.0) Rh (2.0) -mpg-C ₃ N ₄ 0.50 990 0.61 2.9

Referring to Table 1, it can be seen that the specific surface area of the heterogeneous catalyst according to Examples 1 to 6 is 800 m ² / g or more, and the pore volume also has a value in the range of 0.44 to 0.83 cm ³ / g. You can check it.

Characterization 2: Evaluation of Catalyst Performance in Acetic Acid Manufacturing Process

Carbonylation of methanol and carbon monoxide from acetic acid was carried out in a 125 mL batch autoclave equipped with a Pyrex vessel. The reactants used in the carbonylation reaction include 10.9 mL of methanol (MeOH, methanol), 10 mL of reaction co-catalyst (MeI, methyl iodide), 2.7 mL of distilled water and 0.4 g of heterogeneous catalyst. Was used. In order to prepare an atmosphere of the reaction under high pressure, the reaction product was prepared by injecting carbon monoxide as a reactant to 40 bar in the form of a mixed gas at a molar ratio of 90:10 with nitrogen as an internal standard. At this time, the molar reference composition of the reactants used was fixed to MeOH: MeI: distilled water = 46: 28: 26, MeI / MeOH = 0.6 and distilled water / MeOH = 0.6. After stirring the reactants and the promoter at a speed of 100 rpm, the temperature inside the reactor was raised to reach 160 ℃, the stirring speed was increased to 300 rpm and the temperature was terminated when the temperature reached 190 ℃, the reaction temperature The carbonylation reaction was performed for 3 hours later. The results are shown in Table 2 below, FIGS. 1 and 2. Each of the catalysts identified in Table 2 was used as a 0.4 g heterogeneous catalyst, and the "other" materials in selectivity were mainly methane and propionic acid, and the acetate yield was "methanol conversion x acetic acid selectivity". The result calculated by

division Catalyst name Methanol
Conversion rate
(mole%) Selectivity (mol%) Acetic acid yield
(mole%) Acetic acid Methyl acetate
And others Example 1 Al (1.25) Rh (2.0) -mpg-C ₃ N ₄ 94.5 60.5 39.5 57.1 Example 2 Al (1.5) Rh (2.0) -mpg-C ₃ N ₄ 95.1 60.7 39.3 57.7 Example 3 Al (2.0) Rh (2.0) -mpg-C ₃ N ₄ 95.5 65.2 34.8 62.3 Example 4 Al (2.5) Rh (2.0) -mpg-C ₃ N ₄ 95.8 64.3 35.7 61.7 Example 5 Al (3.0) Rh (2.0) -mpg-C ₃ N ₄ 96.0 63.9 36.1 61.4 Example 6 Al (1.25) Rh (2.5) -mpg-C ₃ N ₄ 94.8 61.1 38.9 57.9 Comparative Example 1 Rh (2.0) -mpg-C ₃ N ₄ 92.9 59.8 40.2 55.6 Comparative Example 2 Al (1.25) Rh (1.0) -mpg-C ₃ N ₄ 92.2 50.5 49.5 46.6 Comparative Example 3 Al (1.25) Rh (1.5) -mpg-C ₃ N ₄ 91.9 51.2 48.8 47.1 Comparative Example 4 Al (1.0) Rh (2.0) -mpg-C ₃ N ₄ 90.3 49.9 50.1 45.1

Referring to Table 1, Figures 1 and 2 together with Table 1, the weight ratio of Al / Rh is in the range of 0.5 to 2.5 and the rhodium content to maintain 2 parts by weight compared to 100 parts by weight of mesoporous carbon nitride When the carbonylation reaction was performed using Examples 1 to 5, the conversion of methanol as a reactant was confirmed to be converted to at least 94 mol% or more, and the selectivity of acetic acid was found to be 60 mol% or more. It can be seen that the catalytic activity is very excellent.

On the other hand, as shown in Table 2 and Figure 1, in the case of Comparative Examples 2 and 3 immobilized to less than 2 parts by weight with respect to 100 parts by weight of mesoporous carbon, although aluminum is fixed together with rhodium as a promoter However, it can be confirmed that the selectivity and yield to acetic acid is low by comparing the catalyst activity and the heterogeneous catalyst of Example 1. In addition, in the case of Comparative Example 4 in which the aluminum content in the network of carbon nitride was 1 part by weight or less based on 100 parts by weight of mesoporous carbon nitride, the selectivity to acetic acid was low as compared with the activity of the catalyst of Example 1 You can check it.

In addition, as shown in Table 2 and FIG. 2, when each of the heterogeneous catalysts of Examples 1 to 5 in which rhodium is 2 parts by weight and aluminum is 1.25, 1.5, 2.0, 2.5, and 3.0 parts by weight, The conversion was as high as 94.5 mol%, and the selectivity of acetic acid was 60.5 mol% or more, indicating excellent catalyst activity. In particular, it can be seen that it shows better activity compared to the heterogeneous catalyst according to Comparative Example 1, which does not contain aluminum. That is, in the present invention, it is possible to confirm the effect of increasing the catalytic activity by immobilizing aluminum as a promoter in the mesoporous carbon nitride.

Particularly, in Example 3, when the rhodium content was 2 parts by weight and the catalyst, which increases the acid point of the catalyst, was 2 parts by weight of aluminum, the conversion rate of methanol was 95.5 mol%, and the selectivity of acetic acid was 65.2 mol%. The highest yield of total acetic acid was observed, confirming the optimum catalyst composition.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

Claims (17)

The active materials rhodium (Rh) and aluminum (Al), which provide a Lewis acid point, are immobilized in mesoporous carbon,
100 parts by weight of mesoporous carbon nitride, rhodium is 2 to 5 parts by weight, aluminum is included in 1.25 to 3 parts by weight, the weight ratio (Al / Rh) of aluminum and rhodium is 0.5 to 1.5,
The aluminum is converted to acetic acid by hydrolysis by reverse esterification of methyl acetate produced as an intermediate by-product in the carbonylation reaction of methanol,
The conversion of methanol to acetic acid in the carbonylation reaction of methanol is at least 94 carbon mol% or more,
Characterized in that the yield of acetic acid produced by carbonylating methanol is at least 57% or more,
Heterogeneous catalyst for the carbonylation reaction of methanol.
delete delete The method of claim 1,
The specific surface area of mesoporous carbon nitride is 600 to 2,000 m ² / g,
The average pore size of the pores contained in the mesoporous carbon nitride, characterized in that 2 nm to 10 nm,
Heterogeneous catalyst for the carbonylation reaction of methanol.
delete delete delete The method of claim 1,
Hexamethylenetetramine self-polymerizes the porous silica mold using a porous silica template, hexamethylenetetramine, an aluminum precursor and a rhodium precursor to restructure carbon and nitrogen to form mesoporous carbon nitride.
Rhodium and aluminum derived from an aluminum precursor and a rhodium precursor are formed by immobilization on mesoporous carbon nitride,
Heterogeneous catalyst for the carbonylation reaction of methanol.
delete delete delete delete delete Rhodium (Rh), which is an active material, and aluminum (Al), which provides a Lewis acid point, are immobilized to mesoporous carbon, and include 2 to 5 parts by weight of rhodium with respect to 100 parts by weight of mesoporous carbon, and 1.25 of aluminum. Converting methanol to acetic acid by performing a carbonylation reaction on methanol using carbon monoxide in the presence of a heterogeneous catalyst containing 3 to 3 parts by weight and having a weight ratio of aluminum to rhodium (Al / Rh) of 0.5 to 1.5. Including,
In the step of converting methanol, the aluminum of the catalyst is characterized in that the methyl acetate produced as an intermediate by-product in the carbonylation reaction of methanol is converted to acetic acid by reverse esterification by hydrolysis.
Method of manufacturing acetic acid.
The method of claim 14,
Converting the methanol
Injecting a carbon monoxide-containing gas into a solution containing methanol to react at a temperature of 150 to 200 ℃,
Method of manufacturing acetic acid.
The method of claim 15,
Characterized in that the carbon monoxide is injected at a pressure of 10 to 70 bar,
Method of manufacturing acetic acid.
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