Method for producing acetaldehyde and catalyst for producing acetaldehyde

Abstract

The present invention addresses the problem of providing a method for producing acetaldehyde which is capable of preventing the generation of chlorine-based compounds and has a relatively high selectivity and providing a catalyst for producing acetaldehyde.　This problem is solved by a method for producing acetaldehyde according to the present invention which comprises a step for bringing a catalyst into contact with a raw material gas containing ethanol and oxygen, where the catalyst includes an oxide containing elemental molybdenum, elemental bismuth, and an elemental alkali metal.

Description

Method for producing acetaldehyde and catalyst for producing acetaldehyde

[0001] This invention relates to a method for producing acetaldehyde and a catalyst for producing acetaldehyde.

[0002] Currently, the main method for producing acetaldehyde is palladium chloride (PdCl). ２ ) and copper chloride (CuCl ２ One example is the Wacker oxidation method, which uses a catalyst to oxidize ethylene and obtain acetaldehyde (for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2000-26354

[0004] However, the Wacker oxidation method described in Patent Document 1 has the problem of generating chlorine-based compounds such as hydrochloric acid (HCl).

[0005] In view of the above problems, the objective is to provide a method for producing acetaldehyde and a catalyst for producing acetaldehyde that can prevent the generation of chlorine-based compounds and has relatively high selectivity.

[0006] The present invention relates to a method for producing acetaldehyde, comprising the step of contacting a catalyst with a raw material gas containing ethanol and oxygen, wherein the catalyst contains an oxide containing molybdenum, bismuth, and alkali metal elements.

[0007] The acetaldehyde production catalyst according to the present invention is an acetaldehyde production catalyst for synthesizing acetaldehyde from ethanol and oxygen, and comprises an oxide containing molybdenum, bismuth, and alkali metal elements.

[0008] According to the present invention, it is possible to provide a method for producing acetaldehyde that can prevent the generation of chlorine-based compounds and has relatively high selectivity, as well as a catalyst for producing acetaldehyde.

[0009] The following describes specific embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0010] <Method for producing acetaldehyde> The method for producing acetaldehyde in this embodiment involves a catalyst and ethanol (CH4). ３ CH ２ OH) and oxygen (O ２ The process involves contacting a raw material gas containing ) with a catalyst, wherein the catalyst contains molybdenum (Mo), bismuth (Bi), and alkali metal elements (hereinafter referred to as "M"). Ｉ It contains oxides that also contain (also known as ).

[0011] The acetaldehyde production method of this embodiment involves contacting a catalyst with a raw material gas containing ethanol and oxygen to oxidize ethanol and produce acetaldehyde, without the use or generation of chlorine compounds. Therefore, unlike the Wacker oxidation method, which generates chlorine compounds, the acetaldehyde production method of this embodiment can prevent the generation of chlorine compounds. Furthermore, the acetaldehyde production method of this embodiment is an exothermic reaction and is highly energy-efficient.

[0012] (Catalyst) In the above method of producing acetaldehyde by oxidizing ethanol, carbon dioxide, ethylene, ethyl acetate, etc. may be produced in addition to acetaldehyde. In order to increase the ratio of the amount of acetaldehyde produced (in moles) to the total amount (in moles) of the compounds produced (hereinafter also referred to as the acetaldehyde selectivity), the selection of a catalyst is important.

[0013] The catalyst is composed of Mo, Bi, and M, from the viewpoint of increasing acetaldehyde selectivity. Ｉ Contains oxides containing alkali metal elements. Ｉ This refers to the Group 1 elements excluding hydrogen (H), such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

[0014] From the viewpoint of increasing the selectivity of acetaldehyde, the above oxide preferably contains potassium or cesium as an alkali metal element, and more preferably contains cesium.

[0015] From the perspective of increasing the acetaldehyde selectivity, the molar ratio of molybdenum element, bismuth element, and alkali metal element (Mo:Bi:M Ｉ ) is preferably 1: 0.01 or more and 1 or less: 0.001 or more and 0.2 or less, more preferably 1: 0.03 or more and 0.9 or less: 0.002 or more and 0.18 or less, and still more preferably 1: 0.05 or more and 0.8 or less: 0.003 or more and 0.15 or less.

[0016] From the perspective of increasing the acetaldehyde selectivity, the above-mentioned oxide preferably further contains at least one element selected from the group consisting of iron element (Fe), cobalt element (Co), antimony element (Sb), copper element (Cu), and vanadium element (V) in addition to molybdenum element, bismuth element, and alkali metal element.

[0017] From the perspective of increasing the acetaldehyde selectivity, the molar ratio of molybdenum element and iron element (Mo:Fe) is preferably 1: 0 or more and less than 0.7, more preferably 1: 0 or more and 0.5 or less, and still more preferably 1: 0 or more and 0.3 or less

[0018] From the perspective of increasing the acetaldehyde selectivity, the molar ratio of molybdenum element and cobalt element (Mo:Co) is preferably 1: 0 or more and less than​​​​​​​​From the viewpoint of increasing the selectivity of acetaldehyde, the molar ratio (Mo:V) of molybdenum and vanadium is preferably 1:0 or more and 0.01 or less, more preferably 1:0 or more and 0.008 or less, and even more preferably 1:0 or more and 0.005 or less.

[0022] The above oxide is, for example, Mo ａ Bi ｂ M Ｉ ｃ Fe ｄ Co ｅ Sb ｆ Cu ｇ V ｈ O ｘ It can be written as follows. Here, O represents the element oxygen. Also, M Ｉ is an alkali metal element (e.g., Li, Na, K, and Cs), preferably K or Cs, and more preferably Cs. Also, a, b, c, d, e, f, g, and h are Mo, Bi, M, respectively. Ｉ The atomic ratios of Fe, Co, Sb, Cu, and V are shown. Also, x represents Mo, Bi, and M. Ｉ This is the atomic ratio of oxygen determined stoichiometrically by the oxidation states of Fe, Co, Sb, Cu, and V.

[0023] The above Mo ａ Bi ｂ M Ｉ ｃ Fe ｄ Co ｅ Sb ｆ Cu ｇ V ｈ O ｘIn this, a:b:c:d:e:f:g:h are preferably 1:0.01 or more and 1 or less:0.001 or more and 0.2 or less:0 or more and less than 0.7:0 or more and less than 1:0 or more and 0.1 or less:0 or more and 0.02 or less:0 or more and 0.01 or less, more preferably 1:0.03 or more and 0.9 or less:0.002 or more and 0.18 or less:0 or more and 0.5 or less:0 or more and 0.9 or less:0 or more and 0.08 or less:0 or more and 0.015 or less:0 or more and 0.008 or less, and even more preferably 1:0.05 or more and 0.8 or less:0.003 or more and 0.15 or less:0 or more and 0.3 or less:0 or more and 0.8 or less:0 or more and 0.05 or less:0 or more and 0.01 or less:0 or more and 0.005 or less.

[0024] The above oxide may be used as a catalyst either by using the oxide as is or by supporting the oxide on a support. The support is not particularly limited as long as it does not inhibit the reaction between ethanol and oxygen, for example, silicon oxide (SiO₂ ｘ (x is the atomic ratio of O determined stoichiometrically by the oxidation state of Si), aluminum oxide (AlO) ｘ ), or aluminum-silicon oxide (Al ａ Si Ｂ O ｘ ) are examples. Here, from the viewpoint of increasing the contact efficiency between the oxide and the raw material gas containing ethanol and oxygen, the carrier is preferably porous.

[0025] (Raw material gas) The raw material gas is ethanol (CH4). ３ CH ２ OH) and oxygen (O ２ ) contains. Here, oxygen oxidizes ethanol to acetaldehyde (CH ３ This generates CHO. That is, the raw material gas containing ethanol and oxygen that comes into contact with the catalyst becomes a gas containing acetaldehyde according to the following reaction equation (R1): CH ３ CH ２ OH + (1 / 2)O ２ → CH ３ CHO + H ２ O... (R1)

[0026] From the viewpoint of efficiently oxidizing ethanol and increasing the selectivity of acetaldehyde, the molar ratio of oxygen to ethanol in the raw material gas is preferably in the range of 0.50, which is the stoichiometric ratio, and slightly more than that, preferably 0.50 or more, more preferably 0.52 or more, even more preferably 0.55 or more, and also preferably 1.0 or less, more preferably 0.90 or less, and even more preferably 0.80 or less.

[0027] From the viewpoint of efficiently oxidizing ethanol and increasing the selectivity for acetaldehyde, the oxygen concentration in the raw material gas is preferably 1.0% by volume or more, more preferably 3.0% by volume or more, even more preferably 5.0% by volume or more, and also preferably 15.0% by volume or less, more preferably 12.5% ​​by volume or less, and even more preferably 10.0% by volume or less.

[0028] Furthermore, the raw material gas may contain water vapor to increase the selectivity for acetaldehyde. From the viewpoint of increasing the selectivity for acetaldehyde, the concentration of water vapor in the raw material gas is preferably 5.0% by volume or more, more preferably 10.0% by volume or more, even more preferably 25.0% by volume or more, and also preferably 90.0% by volume or less, more preferably 75.0% by volume or less, and even more preferably 60.0% by volume or less.

[0029] (Method of contact) There are no particular restrictions on the method of contacting the catalyst with the raw material gas containing ethanol and oxygen. The raw material gas containing ethanol and oxygen may be introduced into the reaction vessel in which the catalyst is placed, or the catalyst may be placed in the reaction vessel in which the raw material gas containing ethanol and oxygen has been introduced.

[0030] (Contact Temperature) The temperature at which the catalyst is brought into contact with the raw material gas containing ethanol and oxygen is preferably 250°C or higher, more preferably 275°C or higher, even more preferably 300°C or higher, and also preferably 400°C or lower, more preferably 375°C or lower, and even more preferably 350°C or lower, from the viewpoint of increasing the selectivity of acetaldehyde.

[0031] (Contact pressure) The pressure at which the catalyst is brought into contact with the raw material gas containing ethanol and oxygen is preferably 0.1 MPa or higher, more preferably 0.2 MPa or higher, even more preferably 0.3 MPa or higher, and also preferably 2.0 MPa or lower, more preferably 1.5 MPa or lower, and even more preferably 1.0 MPa or lower, from the viewpoint of increasing the selectivity of acetaldehyde.

[0032] <Catalyst for Acetaldehyde Production> The catalyst for acetaldehyde production in this embodiment is a catalyst for synthesizing acetaldehyde from ethanol and oxygen, and contains an oxide containing molybdenum, bismuth, and alkali metal elements, and is the same as the catalyst described in the method for producing acetaldehyde in the above embodiment.

[0033] The present invention includes the following embodiments: [1] A method for producing acetaldehyde, comprising the step of contacting a catalyst with a raw material gas containing ethanol and oxygen, wherein the catalyst contains an oxide containing molybdenum, bismuth, and an alkali metal element. [2] The method for producing acetaldehyde according to [1], wherein the molar ratio of molybdenum, bismuth, and alkali metal elements in the oxide is 1:0.01 or more and 1 or less:0.001 or more and 0.2 or less. [3] The method for producing acetaldehyde according to [1] or [2], wherein the oxide contains potassium or cesium as an alkali metal element. [4] The method for producing acetaldehyde according to any one of [1] to [3], wherein the oxide contains cesium as an alkali metal element. [5] The method for producing acetaldehyde according to any one of [1] to [4], wherein the oxide further contains at least one element selected from the group consisting of iron, cobalt, antimony, copper, and vanadium. [6] The method for producing acetaldehyde according to any one of [1] to [5], wherein the molar ratio of oxygen to ethanol in the raw material gas is 0.50 or more and 1.0 or less. [7] The method for producing acetaldehyde according to any one of [1] to [6], wherein the oxygen concentration in the raw material gas is 1.0% by volume or more and 15.0% by volume or less. [8] The method for producing acetaldehyde according to any one of [1] to [7], wherein the raw material gas further contains water vapor. [9] A catalyst for producing acetaldehyde for synthesizing acetaldehyde from ethanol and oxygen, comprising an oxide containing molybdenum, bismuth, and alkali metal elements.

[0034] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples.

[0035] (Comparative Example 1) 1-1. Preparation of Catalyst I Catalyst I containing an oxide with 0.7 iron atoms per 1 molybdenum atom was prepared by the following method. First, ammonium molybdate [(NH ４ ) ６Mo ７ O ２４ 4H ２ 53g of [O] was dissolved in 60.1g of warm water to obtain solution A. Also, iron(III) nitrate [Fe(NO] ３ ) ３ 9H ２ 80.8 g of [O] was dissolved in 92.7 g of warm water to obtain solution B. Next, while stirring solution A, solution B was added to solution A, and then 25% aqueous ammonia was added to neutralize it and obtain a slurry. The obtained slurry was dried in an air-flow dryer, and the resulting dried product was calcined at 500°C for 20 hours under an airflow to obtain powdered catalyst I.

[0036] 1-2. Catalyst I, in powder form, was compressed into tablets using a hydraulic press. The resulting molded bodies were crushed and sieved to a size of 1-2 mm to obtain crushed catalyst I. 1.4 g of the crushed material was packed into an 8 mm inner diameter SUS reaction tube equipped with a 3 mm outer diameter sheath tube for measuring the internal temperature.

[0037] 1-3. Using a gas flow meter for preparing the raw material gas, nitrogen gas was flowed through the reaction tube filled with the catalyst at a rate of 35.7 mL (0°C, 0.1013 MPa (hereinafter also referred to as "standard conditions")) / min, and a mixed gas of 21 vol% oxygen and 79 vol% nitrogen was flowed at a rate of 59.6 mL (standard conditions) / min. Furthermore, 55.0 mL (standard conditions) / min of nitrogen gas was bubbled into ethanol, which had been kept warm at a liquid temperature of 50°C, to entrain 16.7 mL (standard conditions) / min of ethanol, thus creating the raw material gas. The total gas flow rate of the raw material gas was 167 mL (standard conditions) / min. The molar ratio of oxygen to ethanol in the raw material gas was 0.75.

[0038] 1-4. Reaction Preparation The reaction tube filled with the above catalyst was heated in an electric tubular furnace until the temperature inside the catalyst layer (hereinafter also referred to as "catalyst layer temperature") reached 50°C, and the raw material gas was circulated through it. Under the circulation of the raw material gas, the temperature inside the catalyst layer was raised to 150°C and maintained at that temperature.

[0039] 1-5. Analysis of Raw Material Gas The gas discharged from the reaction tube filled with the above catalyst was introduced into the following columns 1 and 2 of an inline gas chromatography system (GL Sciences Co., Ltd., Agilent 990 micro GC), and the GC area values ​​of the ethanol-derived peaks in the raw material gas were recorded. The analytical conditions are shown below. Column 1 Carrier gas: Helium Injection temperature: 100°C Column used: MOLSIEVE 5A 1m × 0.3mm ID ST Column temperature: 120°C Pressure: 180kPa Detector: Thermal conductivity detector (TCD) Column 2 Carrier gas: Helium Injection temperature: 100°C Column used: COX UM 1m × 0.8mm ID ST Column temperature: 110°C Pressure: 200kPa Detector: Thermal conductivity detector (TCD)

[0040] 1-6. Acetaldehyde Production Reaction Next, under the flow of the raw material gas, the temperature inside the catalyst layer was raised to 300°C, and the acetaldehyde production reaction was carried out (the temperature inside the catalyst layer during the reaction, i.e., the contact temperature, was 300°C). The gas linear velocity, calculated from the flow rate of the raw material gas and the cross-sectional area of ​​the catalyst packed bed relative to an empty column, was 6.4 cm / second under standard conditions. One hour after the temperature inside the catalyst layer reached 300°C, the gas discharged from the above reaction tube was introduced into columns 1 and 2 of an in-line gas chromatography system (GL Sciences Co., Ltd., Agilent 990 micro GC), respectively, and the GC area values ​​of ethanol and peaks derived from each product in the post-reaction gas were recorded. The same analytical conditions as described above were used.

[0041] 1-7. Calculation of Reaction Results Using the GC area values ​​obtained from the analysis of the raw material gas and the post-reaction gas, the ethanol conversion rate was calculated using the following formula (C1), and the selectivity of each product was calculated using the following formula (C2). Here, in calculating the selectivity of each product, a corrected area value was used, obtained by dividing the GC area value of each product by the ratio of the thermal conductivity of each product to ethanol. (Ethanol conversion rate) = [(GC area value of raw material gas - GC area value of post-reaction gas) / GC area value of raw material gas] × 100 ... (C1) (Selectivity of each product) = (Corrected area value of each product in the post-reaction gas / Synthesis corrected area value of all products in the post-reaction gas) × 100 ... (C2)

[0042] 1-8. Reaction Results of Catalyst I The ethanol conversion rate of Catalyst I was 97.5%, the acetaldehyde selectivity was 68.2%, the carbon dioxide selectivity was 9.3%, the ethylene selectivity was 21.3%, and the ethyl acetate selectivity was 1.2%.

[0043] (Comparative Example 2) 2-1. Preparation of Catalyst II Catalyst II containing an oxide with 0.7 bismuth atoms per 1 molybdenum atom was prepared by the following method. First, ammonium molybdate [(NH ４ ) ６ Mo ７ O ２４ 4H ２ 105.9 g of [O] was dissolved in 400 g of warm water to obtain solution A. Also, bismuth nitrate [Bi(NO) ３ ) ３ ・5H ２ 485.1 g of [O] was dissolved in 121.3 g of 70% by mass nitric acid to obtain solution B. Next, while stirring solution A, 400 mL of solution B was added to solution A to obtain a slurry. The obtained slurry was dried in an air-jet dryer, and the resulting dry product was calcined at 500°C for 20 hours under an airflow to obtain catalyst II.

[0044] 2-2. Reaction Results of Catalyst II The reaction results were obtained using Catalyst II in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst II was 93.6%, the acetaldehyde selectivity was 95.1%, the carbon dioxide selectivity was 1.2%, the ethylene selectivity was 3.5%, and the ethyl acetate selectivity was 0.2%.

[0045] (Comparative Example 3) 3-1. Preparation of Catalyst III Catalyst III containing an oxide with one cobalt atom per molybdenum atom was prepared by the following method. First, ammonium molybdate [(NH ４ ) ６ Mo ７ O ２４ 4H ２ 88.3 g of [O] was dissolved in 500 g of warm water to obtain solution A. Also, cobalt nitrate [Co(NO) ３ ) ２ 6H ２ 145.5 g of [O] was dissolved in 500 g of warm water to obtain solution B. Next, while stirring solution B, solution A, which had been heated to 80°C, was added dropwise over 5 minutes, and then 25% by mass aqueous ammonia was added to neutralize it and obtain a slurry. The obtained slurry was dried in an air-flow dryer, and the resulting dry product was calcined at 500°C for 20 hours under an airflow to obtain catalyst III.

[0046] 3-2. Reaction Results of Catalyst III The reaction results were obtained using Catalyst III in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst III was 63.2%, the acetaldehyde selectivity was 95.6%, the carbon dioxide selectivity was 0.8%, the ethylene selectivity was 3.3%, and the ethyl acetate selectivity was 0.4%.

[0047] (Example 1) 4-1. Preparation of Catalyst IV Catalyst IV containing an oxide with 0.7 atoms of bismuth and 0.04 atoms of cesium per atom of molybdenum was prepared by the following method. First, cesium nitrate [CsNO] ３ An aqueous solution of cesium nitrate was obtained by dissolving 0.13 g of cesium nitrate in 2.3 g of water. Then, 2.0 g of the aqueous solution of cesium nitrate was added dropwise to 4.0 g of catalyst II, impregnated, and left to dry in air at room temperature (approximately 25°C) for 24 hours. The resulting dried material was calcined in air at 500°C for 4 hours to obtain catalyst IV.

[0048] 4-2. Reaction Results of Catalyst IV The reaction results were obtained using Catalyst IV in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst IV was 25.8%, the acetaldehyde selectivity was 99.4%, the carbon dioxide selectivity was 0.1%, the ethylene selectivity was 0.2%, and the ethyl acetate selectivity was 0.3%.

[0049] (Example 2) 5-1. Preparation of Catalyst V A catalyst V containing an oxide containing 0.08 atoms of bismuth, 0.02 atoms of cesium, 0.2 atoms of iron, and 0.6 atoms of cobalt per 1 atom of molybdenum was prepared by the following method. First, 331 g of ammonium molybdate [(NH ４ ) ６ Mo ７ O ２４ ・4H ２ O] was dissolved in 374.8 g of warm water to obtain Solution A. Also, 151.5 g of iron(III) nitrate [Fe(NO ３ ) ３ ・9H ２ O], 327.4 g of cobalt nitrate [Co(NO ３ ) ２ ・6H ２ O], and 5.9 g of cesium nitrate [CsNO ３ ] were dissolved in 150 g of warm water, and 72.8 g of bismuth nitrate [Bi(NO ３ )<​​​​​​​​​​​​​​​​​​331 g of [O] was dissolved in 374.8 g of warm water to obtain Solution A. Also, 151.5 g of iron(III) nitrate [Fe(NO ３ ), ３ ·9H ２ O], 327.4 g of cobalt nitrate [Co(NO ３ ), ２ ·6H ２ O], and 1.5 g of cesium nitrate [CsNO ３ were dissolved in 150 g of warm water, and 72.8 g of bismuth nitrate [Bi(NO ３ ), ３ ·5H ２ O] was further dissolved therein to obtain Solution B. Next, while stirring Solution A, Solution B was added to Solution A, and 25% by mass aqueous ammonia was further added for neutralization to obtain a slurry. The dried product obtained by drying the resulting slurry with a pneumatic dryer was calcined at 515 °C for 6 hours under an air stream to obtain Catalyst VI.

[0052] 6-2. Reaction Results of Catalyst VI Using Catalyst VI, reaction results were obtained in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst VI was 84.3%, the acetaldehyde selectivity was 97.4%, the carbon dioxide selectivity was 0.7%, the ethylene selectivity was 1.8%, and the ethyl acetate selectivity was 0.1%.

[0053] (Example 4) 7-1. Preparation of Catalyst VII A catalyst VII containing an oxide containing 0.08 atoms of bismuth, 0.04 atoms of cesium, 0.2 atoms of iron, 0.6 atoms of cobalt, and 0.04 atoms of antimony per 1 atom of molybdenum was prepared by the following method. First, 331 g of ammonium molybdate [(NH ４ ), ６ Mo ７ O ２４ ·4H ２ O] was dissolved in 374.8 g of warm water to obtain Solution A. Also, 151.5 g of iron(III) nitrate [Fe(NO ３ ), ３ ·9H ２ O], 327.4 g of cobalt nitrate [Co(NO ３ ), ２ ·6H ２ O], and cesium nitrate [CsNO ３Dissolve 14.6 g in 150 g of warm water to obtain a solution, and then add bismuth nitrate [Bi(NO) ３ ) ３ ・5H ２ 72.8 g of [O] was dissolved to obtain solution B. Next, while stirring solution A, solution B was added to solution A, and then 25% by mass aqueous ammonia was added to neutralize it and obtain a slurry. 100 parts by mass of the dried product obtained by drying the obtained slurry in an air-jet dryer, 9 parts by mass of silica alumina fiber (manufactured by Isolite Industries, trade name, RFC400-SL), and 2.5 parts by mass of antimony trioxide (Sb ２ O ３ A mixture of the above was calcined at 545°C for 6 hours under an airflow to obtain catalyst VII.

[0054] 7-2. Reaction Results of Catalyst VII The reaction results were obtained using Catalyst VII in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst VII was 58.9%, the acetaldehyde selectivity was 99.6%, the carbon dioxide selectivity was 0.1%, the ethylene selectivity was 0.2%, and the ethyl acetate selectivity was 0%.

[0055] (Example 5) 8-1. Preparation of Catalyst VIII Catalyst VIII containing an oxide with 0.08 atoms of bismuth, 0.04 atoms of cesium, 0.2 atoms of iron, 0.6 atoms of cobalt, and 0.008 atoms of copper per atom of molybdenum was prepared by the following method. First, ammonium molybdate [(NH ４ ) ６ Mo ７ O ２４ 4H ２ 331 g of [O] was dissolved in 374.8 g of warm water to obtain solution A. Also, iron(III) nitrate [Fe(NO] ３ ) ３ 9H ２ O] 151.5g, cobalt nitrate [Co(NO] ３ ) ２ 6H ２ [O] 327.4g, Cesium nitrate [CsNO] ３ ] 14.6 g, and copper nitrate [Cu(NO ３ ) ２ 3H ２ Dissolve 12g of [O] in 150g of warm water to obtain a solution, and then add bismuth nitrate [Bi(NO)３ ) ３ ・5H ２ 72.8 g of [O] was dissolved to obtain solution B. Next, while stirring solution A, solution B was added to solution A, and then 25% by mass aqueous ammonia was added to neutralize it and obtain a slurry. The obtained slurry was dried in an air-flow dryer, and the resulting dried product was calcined at 515°C for 6 hours under an airflow to obtain catalyst VIII.

[0056] 8-2. Reaction Results of Catalyst VIII The reaction results were obtained using Catalyst VIII in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst VIII was 62.8%, the acetaldehyde selectivity was 98.4%, the carbon dioxide selectivity was 0.6%, the ethylene selectivity was 0.9%, and the ethyl acetate selectivity was 0.1%.

[0057] (Example 6) 9-1. Preparation of Catalyst IX Catalyst IX containing an oxide with 0.08 atoms of bismuth, 0.11 atoms of cesium, 0.2 atoms of iron, 0.6 atoms of cobalt, and 0.004 atoms of vanadium per atom of molybdenum was prepared by the following method. First, ammonium molybdate [(NH ４ ) ６ Mo ７ O ２４ 4H ２ O] 331g, ammonium vanadate [NH ４ VO ３ 0.9 g, 28.7 g of 67.5% by mass nitric acid, and cesium nitrate [CsNO] ３ 39.5 g of [Fe(NOx] was dissolved in 374.8 g of warm water to obtain solution A. Also, iron(III) nitrate [Fe(NOx] ３ ) ３ 9H ２ O] 151.5 g and cobalt nitrate [Co(NO] ３ ) ２ 6H ２ Dissolve 327.4 g of [O] in 150 g of warm water to obtain a solution, and then add bismuth nitrate [Bi(NO) ３ ) ３ ・5H ２72.8 g of [O] was dissolved to obtain solution B. Next, while stirring solution A, solution B was added to solution A, and then 25% by mass aqueous ammonia was added to neutralize it and obtain a slurry. The obtained slurry was dried in an air-flow dryer, and the resulting dried product was calcined at 515°C for 6 hours under an airflow to obtain catalyst IX.

[0058] 9-2. Reaction Results of Catalyst IX The reaction results were obtained using Catalyst IX in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst IX was 32.2%, the acetaldehyde selectivity was 99.3%, the carbon dioxide selectivity was 0.3%, the ethylene selectivity was 0.3%, and the ethyl acetate selectivity was 0.1%.

[0059] (Example 7) 10-1. Preparation of Catalyst X Catalyst X containing an oxide with 0.08 atoms of bismuth, 0.06 atoms of cesium, 0.2 atoms of iron, 0.6 atoms of cobalt, and 0.004 atoms of vanadium per atom of molybdenum was prepared by the following method. First, ammonium molybdate [(NH4] ４ ) 6Mo ７ O ２４ 4H ２ O] 331g, ammonium vanadate [NH ４ VO ３ 0.9 g, 28.7 g of 67.5% by mass nitric acid, and cesium nitrate [CsNO] ３ 23.4 g was dissolved in 374.8 g of warm water to obtain solution A. Also, iron(III) nitrate [Fe(NO ３ ) ３ 9H ２ O] 151.5 g and cobalt nitrate [Co(NO] ３ ) ２ 6H ２ Dissolve 327.4 g of [O] in 150 g of warm water to obtain a solution, and then add bismuth nitrate [Bi(NO) ３ ) ３ ・5H ２ 72.8 g of [O] was dissolved to obtain solution B. Next, while stirring solution A, solution B was added to solution A, and then 25% by mass aqueous ammonia was added to neutralize it and obtain a slurry. The obtained slurry was dried in an air-flow dryer, and the resulting dried product was calcined at 515°C for 6 hours under an airflow to obtain catalyst X.

[0060] 10-2. Reaction Results of Catalyst X The reaction results were obtained using catalyst X in the same manner as in Comparative Example 1. The ethanol conversion rate of catalyst X was 45.8%, the acetaldehyde selectivity was 99.0%, the carbon dioxide selectivity was 0.4%, the ethylene selectivity was 0.5%, and the ethyl acetate selectivity was 0.1%.

[0061] (Example 12) 11-1. Preparation of Catalyst XI Catalyst XI containing an oxide with 0.7 atoms of bismuth and 0.04 atoms of potassium per atom of molybdenum was prepared by the following method. First, potassium nitrate [KNO ３ A potassium nitrate aqueous solution was obtained by dissolving 0.06 g of [the substance] in 2.3 g of water. Furthermore, 2.0 g of the potassium nitrate aqueous solution was added dropwise to 4.0 g of catalyst II, allowing it to impregnate the material. The mixture was then left to stand in air at room temperature (approximately 25°C) for 24 hours to dry. The resulting dried material was calcined in air at 500°C for 4 hours to obtain catalyst XI.

[0062] 4-2. Reaction Results of Catalyst XI The reaction results were obtained using Catalyst XI in the same manner as in Comparative Example 1. The ethanol conversion rate of Catalyst XI was 24.5%, the acetaldehyde selectivity was 98.5%, the carbon dioxide selectivity was 1.5%, the ethylene selectivity was 0%, and the ethyl acetate selectivity was 0%.

[0063] Table 1 summarizes the relationship between the composition of catalysts I to XI and the selectivity of the obtained acetaldehyde, carbon dioxide, ethylene, and ethyl acetate products in Comparative Examples 1 to 3 and Examples 1 to 7 and Example 12.

[0064]

[0065] As is clear from Table 1, Catalyst II (Comparative Example 2), an oxide containing only molybdenum and bismuth, had a low acetaldehyde selectivity of 95.1%, indicating it was insufficient for industrial use. In contrast, Catalysts IV to XI (Examples 1 to 7, Example 12), which contain oxides containing molybdenum, bismuth, and cesium or potassium, had high acetaldehyde selectivity of 97% or more, indicating they were suitable for industrial use. Furthermore, Catalyst I (Comparative Example 1), an oxide containing only molybdenum and iron, and Catalyst III (Comparative Example 3), an oxide containing only molybdenum and cobalt, had low acetaldehyde selectivity of 68.2% and 95.6%, respectively, indicating they were insufficient for industrial use.

[0066] (Example 8) 11-1. Reaction results of catalyst X when the contact temperature is changed (300°C → 348°C) Using catalyst X, the reaction results were obtained in the same manner as in Comparative Example 1, except that the temperature inside the catalyst layer (i.e., the contact temperature) during the acetaldehyde generation reaction was 348°C. Under these reaction conditions, the ethanol conversion rate of catalyst VII was 97.0%, the acetaldehyde selectivity was 98.7%, the carbon dioxide selectivity was 1.0%, the ethylene selectivity was 0.3%, and the ethyl acetate selectivity was 0%.

[0067] (Example 9) 12-1. Preparation of raw material gas Using a gas flow meter, nitrogen gas was flowed through a reaction tube filled with catalyst at a rate of 55.3 mL (standard conditions) / min, and a mixed gas of 21 vol% oxygen and 79 vol% nitrogen was flowed at a rate of 40 mL (standard conditions) / min. Furthermore, 55.0 mL (standard conditions) of nitrogen gas was bubbled into ethanol, which had been kept warm at a liquid temperature of 50°C, to entrain 16.7 mL (standard conditions) of ethanol, thus creating the raw material gas. The total gas flow rate of the raw material gas was 167 mL (standard conditions) / min. The molar ratio of oxygen to ethanol (oxygen / ethanol) in the raw material gas was 0.50.

[0068] 12-2. Reaction Results of Catalyst X When the Raw Material Gas and Contact Temperature are Changed The above raw material gas (oxygen / ethanol molar ratio of 0.50) was prepared using catalyst X, and the reaction results were obtained in the same manner as in Comparative Example 1, except that the temperature inside the catalyst layer for the acetaldehyde generation reaction was set to 348°C. Under these reaction conditions, the ethanol conversion rate of catalyst X was 88.9%, the acetaldehyde selectivity was 99.3%, the carbon dioxide selectivity was 0.4%, the ethylene selectivity was 0.3%, and the ethyl acetate selectivity was 0%.

[0069] (Example 10) 13-1. Preparation of raw material gas Using a gas flow meter, nitrogen gas was flowed through a reaction tube filled with catalyst at a rate of 15.8 mL (standard conditions) / min, and a mixed gas of 21 vol% oxygen and 79 vol% nitrogen was flowed at a rate of 79.5 mL (standard conditions) / min. Furthermore, 55.0 mL (standard conditions) of nitrogen gas was bubbled into ethanol, which had been kept warm at a liquid temperature of 50°C, and 16.7 mL (standard conditions) of ethanol was entrained to form the raw material gas. The total gas flow rate of the raw material gas was 167 mL (standard conditions) / min. The molar ratio of oxygen to ethanol in the raw material gas was 1.0.

[0070] 13-2. Reaction Results of Catalyst X When the Raw Material Gas and Contact Temperature are Changed The above raw material gas (oxygen / ethanol molar ratio of 1.0) was prepared using catalyst X, and the reaction results were obtained in the same manner as in Comparative Example 1, except that the temperature inside the catalyst layer for the acetaldehyde generation reaction was set to 349°C. Under these reaction conditions, the ethanol conversion rate of catalyst X was 97.7%, the acetaldehyde selectivity was 98.1%, the carbon dioxide selectivity was 1.5%, the ethylene selectivity was 0.3%, and the ethyl acetate selectivity was 0%.

[0071] (Example 11) 14-1. Preparation of raw material gas Using a gas flow meter, nitrogen gas was flowed at 59.6 mL (standard conditions) / min through a reaction tube filled with catalyst. Furthermore, a water-ethanol mixture, prepared by mixing 54.3 mL of water and 10 mL of ethanol, was flowed at 0.11 mL / min using a plunger pump and vaporized by passing it through a SUS tube heated to 120°C with a tape heater, resulting in a flow of 90.7 mL (standard conditions) / min of water vapor and 16.7 mL (standard conditions) / min of ethanol. Finally, a mixed gas of 21 vol% oxygen and 79 vol% nitrogen was added at 59.6 mL (standard conditions) / min, and the flow of nitrogen gas, which had been flowing at 59.6 mL (standard conditions) / min, was stopped to use it as the raw material gas. The total gas flow rate of the raw material gas was 167 mL (standard conditions) / min. The molar ratio of oxygen to ethanol in the raw material gas was 0.75.

[0072] 14-2. Reaction Results of Catalyst X When the Raw Material Gas is Changed The reaction results were obtained in the same manner as in Comparative Example 1, except that the above raw material gas (addition of water vapor) was prepared using catalyst X and the reaction was carried out. Under these reaction conditions, the ethanol conversion rate of catalyst X was 17%, and no peaks other than unreacted ethanol and acetaldehyde were detected in the GC chromatogram, and acetaldehyde was obtained quantitatively.

[0073] Table 2 summarizes the relationship between the composition of the raw material gas, the temperature inside the catalyst layer during the reaction (contact temperature), and the selectivity of the obtained products, acetaldehyde, carbon dioxide, ethylene, and ethyl acetate, in Examples 8 to 11.

[0074]

[0075] As is clear from Table 2, in Examples 8 to 10, even when the molar ratio of oxygen to ethanol in the raw material gas was varied between 0.50 and 1.0, the selectivity of acetaldehyde was 98% or higher, a value sufficient for industrial use. The oxygen concentration in the raw material gas at that time was between 5% and 10%. Furthermore, from Example 11, when the raw material gas contained 54% by volume of water vapor, acetaldehyde was obtained quantitatively (i.e., the acetaldehyde selectivity was 100%), and a high selectivity suitable for industrial use was obtained.

Claims

The process includes a step of contacting a catalyst with a raw material gas containing ethanol and oxygen, A method for producing acetaldehyde, wherein the catalyst comprises an oxide containing molybdenum, bismuth, and alkali metal elements. 　 The method for producing acetaldehyde according to claim 1, wherein the molar ratio of molybdenum, bismuth, and alkali metal elements in the oxide is 1:0.01 or more and 1 or less:0.001 or more and 0.2 or less. 　 The method for producing acetaldehyde according to claim 1 or 2, wherein the oxide contains potassium or cesium as an alkali metal element. 　 The method for producing acetaldehyde according to claim 1 or 2, wherein the oxide contains cesium as an alkali metal element. 　 The method for producing acetaldehyde according to claim 1 or 2, wherein the oxide further contains at least one element selected from the group consisting of iron, cobalt, antimony, copper, and vanadium. 　 The method for producing acetaldehyde according to claim 1 or 2, wherein the molar ratio of oxygen to ethanol in the raw material gas is 0.50 or more and 1.0 or less. 　 The method for producing acetaldehyde according to claim 1 or 2, wherein the oxygen concentration in the raw material gas is 1.0% by volume or more and 15.0% by volume or less. 　 The method for producing acetaldehyde according to claim 1 or 2, wherein the raw material gas further comprises water vapor. A catalyst for producing acetaldehyde, for synthesizing acetaldehyde from ethanol and oxygen, A catalyst for acetaldehyde production, comprising an oxide containing molybdenum, bismuth, and alkali metal elements.

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