KR101086730B1 - Mixed metal oxide catalyst for conversion of ethanol to acetaldehyde by dehydrogenation and Preparing method of the same - Google Patents

Abstract

The present invention relates to a mixed metal oxide catalyst for dehydrogenation for synthesizing acetaldehyde from ethanol and a method for preparing the same, and more particularly, to an oxide catalyst including a copper-chromium-metal element, wherein the copper, It contains chromium and metal elements in specific molar ratios. Since the catalyst of the present invention has high conversion and high selectivity in preparing acetaldehyde from ethanol, acetaldehyde can be produced in high yield.

Ethanol, acetaldehyde, conversion, selectivity

Description

Mixed metal oxide catalyst for conversion of ethanol to acetaldehyde by dehydrogenation and Preparing method of the same} for synthesis of acetaldehyde from ethanol

The present invention relates to a mixed metal oxide catalyst containing copper, chromium and metal elements in a specific molar ratio used in a dehydrogenation reaction process for synthesizing acetaldehyde from ethanol and a method for producing the same.

Acetaldehyde is an organic compound represented by the chemical formula CH ₃ CHO and is a liquid flammable substance with an irritating odor. The acetaldehyde has a specific gravity of 0.7893 (16 ° C.), a boiling point of 20.8 ° C., a melting point of -123.3 ° C., a flash point of -37.8 ° C., a flash point of 185 ° C., a combustion range of 4 to 57% by volume, and are dissolved in water, alcohol, and ether at an arbitrary ratio. It is usually mixed with organic liquids, has high chemical reactivity, and is used as an important intermediate for various synthesis.

As a method of industrially synthesizing acetaldehyde, the "step of preparing acetaldehyde from ethylene" described in German Patent No. 1,190,451 is used. The process for preparing acetaldehyde from ethylene disclosed in the German patent is a method of obtaining acetaldehyde by oxidizing ethylene in the presence of platinum chloride, an aqueous solution of copper chloride and oxygen, the process is methyl chloride, ethyl chloride, acet chloride There is a problem of producing a lot of return byproducts such as aldehydes.

On the other hand, the process of synthesizing acetaldehyde from ethanol is free from the disadvantages of the process of preparing acetaldehyde from ethylene, which produces return by-products. The process of synthesizing acetaldehyde from ethanol is divided into dehydrogenation and oxidative dehydrogenation. The dehydrogenation is a reaction that removes hydrogen from ethanol in the presence of a catalyst to obtain acetaldehyde. Simple and has the advantage of producing hydrogen that can be used in other processes, but the conversion rate is low. In contrast, the oxidative dehydrogenation reaction is a reaction in which ethanol is oxidized in the presence of a catalyst and oxygen and hydrogen is removed to obtain acetaldehyde. The conversion is high, but many by-products are generated, resulting in low selectivity of acetaldehyde and oxygen and water. The process is complicated because it must be removed.

Representative catalysts for the dehydrogenation of ethanol include the copper-chromium catalyst described in US Pat. No. 1,977,750. The copper-chromium catalyst has a conversion rate of 35 to 50% at a reaction temperature of 260 to 290 ° C. Although the process is simple, when the conversion rate is high, there is a problem that the selectivity of acetaldehyde is decreased due to the increase in the amount of ethyl acetate or acetic acid produced. Therefore, considering the industrial scale, increasing the selectivity is a very economically important problem.

Accordingly, the present inventors, while studying a catalyst for the dehydrogenation reaction process for synthesizing acetaldehyde from ethanol, using an alkali metal or an alkaline earth metal in a copper-chromium catalyst or a copper-chromium catalyst supported on a support , The catalyst with high selectivity was completed while maintaining the conversion rate of the copper-chromium catalyst. That is, by neutralizing by adding alkali metal or alkaline earth metal, which is a base, to the acid point scattered on a copper-chromium catalyst or a copper-chromium catalyst supported on a support, which produces a by-product, the by-product is suppressed to improve selectivity. It can be increased. Accordingly, an object of the present invention is to provide a mixed metal oxide catalyst for dehydrogenation for synthesizing acetaldehyde from ethanol.

The present invention for achieving the above object relates to a mixed metal oxide catalyst for the dehydrogenation reaction for synthesizing acetaldehyde from ethanol, 1: 0.01 ~ 0.5: 0.001 ~ 0.25 molar ratio of copper, chromium, and alkali or alkaline earth metal It characterized by including as.

In addition, the present invention relates to a method for producing the mixed metal oxide catalyst for the dehydrogenation reaction, the first step of adding distilled water to the copper precursor and chromium precursor, stirring and dissolving to prepare a mixed solution; Adding and stirring an aqueous sodium carbonate solution to the mixed solution to co-precipitate a copper-chromium compound; Calcining the copper-chromium compound; Adding an alkali metal compound or an alkaline earth metal compound to the calcined copper-chromium compound to prepare a mixture; And five steps of firing the mixture.

The catalyst according to the present invention is neutralized by adding an alkali metal or alkaline earth metal as a base to an acid point interspersed with a copper-chromium-based catalyst or a copper-chromium-based catalyst supported on a support, which serves to generate a byproduct. Since the chromium-based catalyst exhibits high selectivity while maintaining the conversion rate shown, it can be usefully used in the dehydrogenation process for synthesizing acetaldehyde from ethanol.

Hereinafter, the present invention will be described in more detail.

The present invention relates to an oxide catalyst for the dehydrogenation reaction for synthesizing acetaldehyde from ethanol, comprising copper, chromium, and alkali metal or alkaline earth metal in a molar ratio of 1: 0.01 to 0.5: 0.001 to 0.25.

When the molar ratio of the copper, chromium, and alkali metal or alkaline earth metal is out of the range, the stability of the catalyst may be reduced and the life of the catalyst may be shortened, or the selectivity to acetaldehyde may be reduced. It is preferable.

The alkali metal may include Na or K, and the alkaline earth metal may include Mg, Ca, Sr, or Ba.

In addition, the oxide catalyst of the present invention may further include at least one support selected from Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO ₂ and TiO ₂ .

When the oxide catalyst is supported on the support, the oxide catalyst for the dehydrogenation reaction of the present invention is 20 to 95% by weight of the oxide catalyst and 5 to 80% by weight of the support, more preferably the oxide catalyst 25 ~ 80% by weight and 20 to 75% by weight of the support is preferably included. In this case, if the amount of the support is less than 5% by weight based on the total weight, the selectivity may drop, and when the amount of the support is 80% by weight or more, the content of the oxide catalyst may be relatively small, so that there may be a problem in that the effect of being supported on the support may not be seen. It is preferable to use within the said range.

Referring to the method for producing the oxide catalyst for dehydrogenation reaction of the present invention will be described.

Adding distilled water to the copper precursor and the chromium precursor, followed by stirring and dissolving to prepare a mixed solution; Adding and stirring an aqueous sodium carbonate solution to the mixed solution to co-precipitate a copper-chromium compound; Calcining the copper-chromium compound; Adding an alkali metal compound or an alkaline earth metal compound to the calcined copper-chromium compound to prepare a mixture; And five steps of firing the mixture.

In addition, in the present invention, in the step ₂ , at least one support selected from Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO _2, and TiO ₂ may be further added to the mixed solution in addition to an aqueous sodium carbonate solution.

The copper precursor may be copper nitrate, copper sulfate, copper oxide, fatty acid copper, and the like, and the chromium precursor may be chromium nitrate, chromium sulfate, chromium oxide, fatty acid chromium, and the like, but is not particularly limited. Copper nitrate The chromium precursor is preferably used chromium nitrate.

The firing temperature of the three steps and the five steps is preferably carried out at 200 ~ 500 ℃, more preferably 250 ~ 450 ℃.

In the above-described oxide catalyst for dehydrogenation of the present invention, when acetaldehyde is synthesized from ethanol, the acetaldehyde selectivity is 90% or more, preferably 90 to 99.9%, so that acetaldehyde can be obtained in high yield.

Hereinafter, the present invention will be described in more detail based on examples. However, the scope of the present invention is not limited by the following examples.

Example 1 Cu _One Cr _0.1 Ba _0.01 Preparation of oxide catalyst for dehydrogenation reaction represented by oxide

To a beaker add 48.32 g (200.0 mmol) of copper nitrate (Cu (NO ₃ ) ₂ 3H ₂ O) and 8.000 g (20.00 mmol) of chromium nitrate (Cr (NO ₃ ) ₃ 9H ₂ O), followed by 360 g of After adding distilled water, the mixture was stirred and dissolved to prepare a mixed solution. Separately, 360 g of distilled water was added to 29.26 g (276.0 mmol) of sodium carbonate (Na ₂ CO ₃ ), followed by stirring and dissolving to prepare an aqueous sodium carbonate solution. The mixed solution and sodium carbonate aqueous solution were slowly added to a 1000 ml beaker with stirring to make the pH of 8.0 ± 0.1, and the temperature was maintained at 55 ± 1 ° C. The resulting precipitate was filtered, washed with distilled water, dried at 100 ° C. for 12 hours, and calcined at 400 ° C. for 5 hours to obtain a copper-chromium compound. 0.5227 g (2.000 mmol) of barium nitrate (Ba (NO ₃ ) ₂ ) was added to the copper-chromium compound prepared by the above method, dried at 100 ° C. for 12 hours, and then calcined at 400 ° C. for 5 hours. An oxide catalyst for dehydrogenation reaction was prepared in which the molar ratio of: Cr: Ba is 1: 0.1: 0.01.

Example 2 Cu _One Cr _0.1 Ba _0.02 with oxide Preparation of Oxide Catalyst for Dehydrogenation Reaction

In the same manner as in Example 1, 1.045 g (4.000 mmol) of barium nitrate was added to prepare an oxide catalyst for a dehydrogenation reaction having a molar ratio of Cu: Cr: Ba of 1: 0.1: 0.02.

Example 3 Cu _One Cr _0.1 Ba _0.04 Preparation of oxide catalyst for dehydrogenation reaction represented by oxide

In the same manner as in Example 1, 2.091 g (8.000 mmol) of barium nitrate was added to prepare an oxide catalyst for a dehydrogenation reaction having a molar ratio of Cu: Cr: Ba of 1: 0.1: 0.04.

Example 4 Cu _One Cr _0.1 K _0.01 Preparation of oxide catalyst for dehydrogenation reaction represented by oxide

In the same manner as in Example 1, 0.2022 g (2.000 mmol) of potassium nitrate (KNO ₃ ) was added instead of barium nitrate to obtain an oxide catalyst for a dehydrogenation reaction having a molar ratio of Cu: Cr: K of 1: 0.1: 0.01. Prepared.

Example 5 Cu _One Cr _0.1 K _0.03 Preparation of oxide catalyst for dehydrogenation reaction represented by oxide

In the same manner as in Example 4, but 0.6066 g (6.000 mmol) of potassium nitrate was added to prepare an oxide catalyst for the dehydrogenation reaction with a molar ratio of Cu: Cr: K of 1: 0.1: 0.03.

Example 6 Alumina (Al ₂ O ₃ ) Supported Cu _One Cr _0.1 Ba _0.2 Preparation of oxide catalyst for dehydrogenation reaction represented by oxide

7.248 g (30.00 mmol) of copper nitrate and 1.200 g (3.000 mmol) of chromium nitrate were added to a beaker, followed by addition of 54 g of distilled water, followed by stirring and dissolving to prepare a mixed solution. Separately, 54 g of distilled water was added to 4.388 g (41.40 mmol) of sodium carbonate (Na ₂ CO ₃ ), followed by stirring and dissolving to prepare an aqueous sodium carbonate solution. The mixed solution and sodium carbonate aqueous solution were slowly added to a 500 ml beaker with stirring to have a pH of 8.0 ± 0.1, 6.089 g of alumina (Al ₂ O ₃ ) was added to the beaker, and the temperature of the solution was 55 ± 1 ° C. Was maintained. The resulting precipitate was filtered, washed with distilled water, dried at 100 ° C. for 12 hours, and calcined at 400 ° C. for 5 hours to obtain a copper-chromium compound supported on alumina. 1.568 g (6.000 mmol) of barium nitrate (Ba (NO ₃ ) ₂ ) was added to the copper-chromium compound supported on the alumina, dried at 100 ° C. for 12 hours, and calcined at 400 ° C. for 5 hours to form Cu: Cr. An oxide catalyst for the dehydrogenation reaction supported on alumina having a molar ratio of: Ba of 1: 0.1: 0.2 was prepared. In addition, the prepared catalyst is 36.7 wt% of an oxide catalyst represented by Cu ₁ Cr _0.1 Ba _0.2 oxide and 63.3 wt% of alumina, based on the total weight.

Comparative Example 1: Cu _One Cr _0.1 Preparation of oxide catalyst represented by oxide

48.32 g (200.0 mmol) of copper nitrate and 8.000 g (20.00 mmol) of chromium nitrate were added to a beaker, followed by 360 g of distilled water, followed by stirring and dissolving to prepare a mixed solution. Separately, 360 g of distilled water was added to 29.26 g (276.0 mmol) of sodium carbonate, followed by stirring and dissolving to prepare an aqueous sodium carbonate solution. The mixed solution and sodium carbonate aqueous solution were slowly added to a 1000 ml beaker with stirring to make the pH of 8.0 ± 0.1, and the temperature was maintained at 55 ± 1 ° C. The resulting precipitate was filtered, washed with distilled water, dried at 100 ° C. for 12 hours, and calcined at 400 ° C. for 5 hours to prepare an oxide catalyst having a molar ratio of Cu: Cr: 1: 0.1.

Comparative Example 2: Cu Supported on Alumina _One Cr _0.1 Preparation of oxide catalyst represented by oxide

54 g of distilled water was added to 7.248 g (30.00 mmol) of copper nitrate and 1.200 g (3.000 mmol) of chromium nitrate, followed by stirring to dissolve. Separately, 54 g of distilled water was added to 4.388 g (41.40 mmol) of sodium carbonate, followed by stirring to dissolve it. The mixed solution and sodium carbonate aqueous solution were slowly added to a 500 ml beaker with stirring to have a pH of 8.0 ± 0.1, 6.089 g of alumina (Al ₂ O ₃ ) was added to the beaker, and the temperature of the solution was 55 ± 1 ° C. Was maintained. The resulting precipitate was filtered, washed with distilled water, dried at 100 ° C. for 12 hours, and calcined at 400 ° C. for 5 hours to prepare an oxide catalyst supported on alumina having a Cu: Cr molar ratio of 1: 0.1.

Experimental Example 1 Comparative Analysis of Conversion Rate and Selectivity of Catalysts

Each catalyst prepared in Examples and Comparative Examples, after crushing, was fractionated to a size of 425 ~ 850 ㎛. 0.50 g of the fractionated catalyst was stirred with 1.5 g of diluent sea sand, and then charged into a stainless steel reactor having an outer diameter of 0.5 inch, and 100 mL / min under a 5 mol% H ₂ / Ar mixed gas atmosphere. It was reduced at 200 ℃ for 3 hours at a flow rate of. And the dehydrogenation reaction which synthesize | combines acetaldehyde from ethanol was performed at 270 degreeC. At this time, ethanol (95% by volume) was fed to the stainless steel reactor in ethanol vapor state at a flow rate of 0.15 ml / min using a liquid pump. The product was analyzed by gas chromatography (Gas Chromatography) and the results are shown in Table 1 below.

division % Conversion Selectivity (%) Example 1 39 92 Example 2 39 94 Example 3 32 95 Example 4 39 96 Example 5 33 97 Example 6 42 92 Comparative Example 1 39 89 Comparative Example 2 39 81

As shown in Table 1, as a result of comparing the conversion and selectivity of the catalyst prepared in Examples 1, 2, 3 and Comparative Example 1 in the reaction of synthesizing acetaldehyde from ethanol at 270 ℃, barium content was Increasing, it can be seen that the selectivity increases while maintaining the conversion rate.

And, as a result of comparing the conversion and selectivity of the catalyst prepared in Examples 4, 5 and Comparative Example 1 in the reaction of synthesizing acetaldehyde from ethanol at 270 ℃, if the potassium content is increased, the conversion is maintained as it is As you can see the selectivity increases.

And, in the case of the catalyst of Example 6 and Comparative Example 2 supported on the support, the conversion and selectivity in the reaction of synthesizing acetaldehyde from ethanol at 270 ℃ as a result, the conversion and selectivity of the catalyst of Example 6 It can be seen that better.

Claims (8)

An oxide catalyst for dehydrogenation reaction for synthesizing acetaldehyde from ethanol, comprising copper, chromium and alkali metal or alkaline earth metal in a molar ratio of 1: 0.01 to 0.5: 0.001 to 0.25. The oxide catalyst for dehydrogenation of claim 1, wherein the alkali metal comprises Na or K, and the alkaline earth metal includes Mg, Ca, Sr, or Ba. The oxide catalyst for dehydrogenation of claim 1, further comprising at least one support selected from Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO _2, and TiO ₂ . The oxide catalyst for dehydrogenation reaction according to claim 3, wherein the support contains 5 to 80% by weight based on the total weight of the catalyst. The oxide catalyst for dehydrogenation according to any one of claims 1 to 4, wherein the catalyst has a selectivity of 90% or more when synthesizing acetaldehyde from ethanol. Adding distilled water to the copper precursor and the chromium precursor, followed by stirring and dissolving to prepare a mixed solution; Adding and stirring an aqueous sodium carbonate solution to the mixed solution to co-precipitate a copper-chromium compound; Calcining the copper-chromium compound; Adding an alkali metal compound or an alkaline earth metal compound to the calcined copper-chromium compound to prepare a mixture; And Calcining the mixture; Method for producing an oxide catalyst for dehydrogenation reaction comprising a. The dehydrogenation reaction of claim 6, wherein the step ₂ further comprises adding at least one support selected from Al ₂ O ₃ , SiO ₂ , ZrO ₂ , CeO ₂ and TiO ₂ in addition to the aqueous sodium carbonate solution. Method for producing an oxide catalyst for use. The method of claim 6, wherein the copper precursor is copper nitrate, and the chromium precursor is chromium nitrate.