Acetone Production Method

Abstract

The purpose of the present invention is to provide an acetone production method for producing acetone in a stable manner using ethanol and water as starting materials, while maintaining a high space-time yield. The present invention is a method for producing acetone comprising a step for synthesizing acetone by bringing water into contact with ethanol in the presence of a catalyst, wherein the step for synthesizing acetone involves using a reaction gas containing ethanol, water, and oxygen as a starting material, with the oxygen concentration in the reaction gas being 0.1 mol% to 10 mol%.

Description

[Technical Field]

[0001] The present invention relates to a method for producing acetone from ethanol, water, and oxygen. [Background technology]

[0002] Several reports have been published on the synthesis of acetone from ethanol and water. For example, Patent Document 1 reports a study using a catalyst made of iron and zirconium at a reaction temperature of 400°C or higher. Patent Document 2 reports a method for producing acetone from ethanol and water using a catalyst containing iron, zinc, and an alkali metal and / or alkaline earth metal, with the molar ratio of the alkali metal and / or alkaline earth metal to zinc being 0.2 to 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-209059 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-240913 Summary of the Invention [Problem to be solved by the invention]

[0004] Several methods for producing acetone from ethanol and water, including the above-mentioned method, are known. However, none of these methods can be said to be capable of stably producing acetone while maintaining a high space-time yield, and there is room for improvement.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing acetone from ethanol and water, which can stably produce acetone while maintaining a high space-time yield. [Means for solving the problem]

[0006] As a result of extensive research aimed at solving the above problems, the present inventors have found that, when acetone is produced from ethanol and water, if a predetermined concentration of oxygen is contained in the reaction gas, acetone can be produced stably even under conditions of a high space-time yield.

[0007] That is, the present invention is as follows. [1] A method for producing acetone, comprising the step of synthesizing acetone by contacting ethanol with water in the presence of a catalyst, The method for producing acetone, wherein the step of synthesizing acetone uses a reaction gas containing ethanol, water, and oxygen as a raw material, and the oxygen concentration in the reaction gas is 0.1 mol % to 10 mol %.

[0008] [2] The method for producing acetone according to [1], wherein the molar ratio of water to ethanol is 0.50 or more and 10 or less.

[0009] [3] The method for producing acetone according to [1] or [2], wherein the molar ratio of oxygen to ethanol is 0.01 or more and less than 1.4.

[0010] [4] The method for producing acetone according to any one of [1] to [3], wherein the total of the vaporization energy of the water and the ethanol per mole of the ethanol is 700 kW or less.

[0011] [5] The method for producing acetone according to any one of [1] to [4], wherein the catalyst contains at least a transition metal element excluding rare earth elements and / or a rare earth element.

[0012] [6] The method for producing acetone according to any one of [1] to [5], wherein the temperature at which the ethanol and water are brought into contact with each other is 250°C to 600°C.

[0013] [7] The space velocity of the reaction gas is 100 h -1 ~10000h -1 The method for producing acetone according to any one of [1] to [6], wherein

[0014] [8] The method for producing acetone according to any one of [1] to [7], wherein the ethanol includes ethanol derived from biomass. [Effects of the Invention]

[0015] The method for producing acetone according to the present disclosure can stably produce acetone using ethanol and water as raw materials while maintaining a high space-time yield. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure will be described in detail below. A combination of two or more of the preferred embodiments of the present disclosure described below is also a preferred embodiment of the present disclosure. In this specification, the term "X to Y" indicating a range means "X or more and Y or less."

[0017] [Method for producing acetone according to the present disclosure]

[0018] <Catalyst> There are no particular limitations on the catalyst used in the production method of the present disclosure, as long as it can produce acetone from ethanol and water, but a catalyst that provides a high acetone yield is preferred.

[0019] The catalyst of the present disclosure is not particularly limited, but examples thereof include a metal oxide containing a metal element, a support containing a metal element, and a support supporting a simple metal element or a metal oxide. The metal oxide may be an oxide of one type of metal element, or a composite oxide containing two or more types of metal elements. Examples of composite metal oxides include those with crystalline structures such as spinel, perovskite, magnetoplumbite, and garnet, amorphous oxides, and oxides having both crystalline and amorphous portions. Examples of the carrier include activated carbon, silica, alumina, silica-alumina, zeolite, silica-calcia, zirconia, ceria, magnesia, and diatomaceous earth. The catalyst referred to here means the catalyst in a state before the start of the reaction.

[0020] The metal elements contained in the catalyst of the present disclosure preferably include transition metal elements excluding rare earth elements and / or rare earth elements. The transition metal elements excluding rare earth metal elements contained in the catalyst of the present disclosure are preferably metal elements of Groups 3, 4, 8, 11 and 12 of the periodic table, more preferably zirconium, iron, copper and zinc. The rare earth metal element contained in the catalyst of the present disclosure is preferably lanthanum, praseodymium, or neodymium, and more preferably lanthanum. The catalyst of the present disclosure preferably contains copper and / or iron, zirconium, and further contains a transition metal element and / or a rare earth element excluding rare earth elements other than copper, iron, and zirconium, and more preferably contains copper and / or iron, zirconium, and further contains zinc or lanthanum.

[0021] The content of metal elements contained in the catalyst of the present disclosure is preferably 0.1 to 95 mass % relative to the total amount of the catalyst, more preferably 30 to 90 mass %, even more preferably 50 to 87 mass %, and particularly preferably 60 to 87 mass %. In another preferred embodiment of the catalyst of the present disclosure, the content of metal elements contained in the catalyst is 1 to 75 mass %. The content of the metal elements contained in the catalyst of the present disclosure means the content of the metal elements in the catalyst before the start of the reaction. The content of metal elements can be measured by X-ray fluorescence analysis (XRF), and the specific measurement method that can be used is the method described in JIS K0119:2008.

[0022] The shape of the catalyst and carrier used in the method for producing acetone of the present disclosure is not particularly limited, and examples thereof include spherical, pellet, honeycomb, ring, and granular shapes. The size of the catalyst used in the method for producing acetone of the present disclosure is not particularly limited, but the average particle size of the catalyst is preferably 1 mm to 12 mm, more preferably 3 mm to 10 mm. When the average particle size of the catalyst is within the above range, the catalyst can be easily packed into the reaction tube and the pressure loss in the catalyst layer can be reduced, thereby achieving energy savings such as reduced power costs for the blower. The average particle size of the catalyst can be measured by measuring the particle sizes of 100 randomly sampled catalyst particles with a vernier caliper and calculating the average value. Here, the particle size of the catalyst refers to the diameter of the catalyst in the case of a spherical catalyst, and the diameter of the circumscribing sphere of the catalyst in the case of other shapes.

[0023] <Contact of ethanol, water, and oxygen> The method for producing acetone disclosed herein includes a step of synthesizing acetone by contacting ethanol with water (hereinafter, the contact may also be referred to as a reaction) in the presence of a catalyst (hereinafter, the step of synthesizing acetone may also be referred to as a reaction step).

[0024] In the method for producing acetone disclosed herein, oxygen (hereinafter sometimes referred to as molecular oxygen), ethanol, and water are used as raw materials in the reaction step, and the ethanol and water are brought into contact with each other in the presence of a catalyst in an oxygen-containing atmosphere, thereby producing a reaction product containing acetone, hydrogen, and carbon dioxide.

[0025] The method for producing acetone according to the present disclosure is not particularly limited and may be either a batch method or a continuous method, but from the viewpoint of productivity, a continuous method is preferred.

[0026] The method for producing acetone according to the present disclosure is preferably a gas phase reaction. Examples of reaction formats for gas phase reactions include a fixed bed, a moving bed, and a fluidized bed, but the more convenient fixed bed format is preferred.

[0027] When the acetone production method of the present disclosure is a fixed bed type, the reaction gas (hereinafter sometimes referred to as raw material gas) before contact with the catalyst may be a mixture of ethanol, water (sometimes referred to as steam), and oxygen, which is supplied to the reactor and brought into contact with the catalyst; any two of ethanol, water, and oxygen may be mixed in advance and the remaining one supplied separately to the reactor; or gaseous ethanol, steam, and molecular oxygen may each be supplied separately to the reactor; it is preferable to mix any two of ethanol, water, and oxygen in advance and supply the remaining one separately to the reactor; and it is more preferable to mix ethanol and water in advance and supply oxygen separately to the reactor. Here, the reaction gas usually refers to the gas at the inlet of the reactor.

[0028] When the method for producing acetone according to the present disclosure is a gas-phase catalytic reaction, it may be a normal single-flow method or a recycle method.

[0029] The ethanol of the present disclosure may be in the form of gas or mist, but is preferably in the form of gas, which can be obtained, for example, by heating liquid ethanol in a vaporizer. The water of the present disclosure may be in the form of gas or mist, but is preferably in the form of gas. Gaseous water can be obtained by heating water in, for example, an evaporation device. The raw material gas may contain oxygen (molecular oxygen) and may also contain inert gases such as nitrogen and helium in addition to oxygen. Here, the raw material gas includes all gases supplied to the reactor.

[0030] The concentration of ethanol contained in the raw material gas is preferably 3 mol % or more, more preferably 5 mol % or more, and particularly preferably 8 mol % or more. A concentration of 3 mol % or more allows for efficient production of acetone. The concentration of ethanol contained in the raw material gas is preferably 66 mol% or less, more preferably 50 mol% or less, even more preferably 30 mol% or less, and particularly preferably 10 mol% or less. By being 66 mol% or less, a sufficient amount of oxygen can be allowed to coexist with ethanol. That is, the concentration of ethanol contained in the raw material gas is preferably 3 to 66 mol %, more preferably 3 to 50 mol %, still more preferably 5 to 30 mol %, and particularly preferably 8 to 10 mol %.

[0031] The concentration of water contained in the raw material gas is preferably 20 mol% or more, more preferably 30 mol% or more, even more preferably 33 mol% or more, and particularly preferably 35 mol% or more. A concentration of 20 mol% or more allows for efficient production of acetone. The concentration of water contained in the raw material gas is preferably 80 mol% or less, more preferably 59 mol% or less, even more preferably 50 mol% or less, and particularly preferably 44 mol% or less. By keeping the concentration at 80 mol% or less, the total vaporization energy of water and ethanol per mole of ethanol can be kept low, allowing acetone to be produced at low cost. That is, the water concentration in the raw material gas is preferably an amount that results in a water concentration in the raw material gas of 20 mol % to 80 mol %, more preferably 30 mol % to 80 mol %, even more preferably 33 mol % to 59 mol %, particularly preferably 35 mol % to 50 mol %, and most preferably 35 mol % to 44 mol %. When the water concentration in the raw material gas is in this range, a higher acetone yield can be obtained.

[0032] In the raw material gas used in the method for producing acetone of the present disclosure, the molar ratio of water to ethanol is preferably 0.5 or more, more preferably 2.5 or more, and even more preferably 3.5 or more. A molar ratio of water to ethanol of 0.5 or more is preferable because it increases the acetone selectivity. In addition, in the raw material gas used in the method for producing acetone of the present disclosure, the molar ratio of water to ethanol is preferably not more than 10, more preferably not more than 7.0, and even more preferably not more than 4.5. When the molar ratio of oxygen to ethanol is not more than 10, the total vaporization energy of water and ethanol per mole of ethanol can be kept low, which is preferable because acetone can be produced at low cost. That is, the molar ratio of water to ethanol in the raw material gas used in the method for producing acetone of the present disclosure is preferably 0.5 to 10, more preferably 0.5 to 7.0, even more preferably 2.5 to 7.0, and particularly preferably 3.5 to 4.5.

[0033] The raw material gas used in the method for producing acetone of the present disclosure preferably has a total vaporization energy of 700 kW or less for 1 mole of ethanol and water. More preferably, it is 350 kW or less, and even more preferably, it is 150 kW or less. The lower the total vaporization energy of 1 mole of ethanol and water, the lower the cost at which acetone can be synthesized. However, because the reaction proceeds more efficiently by vaporizing water, it is preferable that the total vaporization energy of 1 mole of ethanol and water exceeds 0. Furthermore, the total vaporization energy of water and ethanol per mole of ethanol is usually 75 kW or more.

[0034] The ethanol used as the feed gas is not particularly limited, and examples thereof include ethanol obtained by the hydration reaction of ethylene and bioethanol made from biomass materials, such as sugar-based materials such as sugarcane, starch-based materials such as grains, and cellulose-based materials such as plants.

[0035] The ethanol used in the feed gas preferably contains bioethanol. The content of bioethanol contained in 100% by mass of ethanol used in the feed gas (also referred to as bioethanol content) is preferably 50% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more.

[0036] The bioethanol content can be measured as follows. 1. The ethanol used as raw gas is burned and converted entirely into carbon dioxide. 2. Carbon dioxide is separated and purified using a vacuum line. 3. The carbon dioxide produced from ethanol is completely reduced with hydrogen using iron as a catalyst to produce graphite. 4. NEC Corporation 14 Using a C-AMS measurement device, we investigated the properties of graphite derived from ethanol. 14 C concentration and 13 C concentration ratio ( 14 C / 13 C). 5. Oxalic acid (hereinafter referred to as the standard sample) provided by the National Institute of Standards (NIST) in the same year as the raw material ethanol was produced was also measured using the same methods as above 1 to 4. 14 C concentration and 13 C concentration ratio ( 14 C / 13 C). 6. Graphite derived from raw material ethanol 14 C / 13 The value of C of the standard sample 14 C / 13 The bioethanol content is obtained by dividing the value by the C value and multiplying the result by 100.

[0037] The concentration of molecular oxygen contained in the raw material gas is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, even more preferably 0.7 mol% or more, and particularly preferably 1 mol% or more. A concentration of 0.1 mol% or more is preferable because it can suppress a temperature drop in the catalyst layer due to the endothermic reaction between ethanol and water and improve the yield of acetone. The concentration of molecular oxygen contained in the raw material gas is preferably 10 mol% or less, more preferably 7.5 mol% or less, even more preferably 7 mol% or less, and particularly preferably 5 mol% or less. A concentration of 10 mol% or less is preferable because it can prevent the generated acetone and ethanol from being burned by oxygen, thereby reducing the acetone yield, and also because it allows the generated hydrogen to be selectively burned, thereby obtaining acetone in high yield.

[0038] The concentration of molecular oxygen contained in the raw material gas is preferably 0.1 mol % to 10 mol %, more preferably 0.5 mol % to 7.5 mol %, even more preferably 0.7 mol % to 7 mol %, and particularly preferably 1 mol % to 5 mol %. By setting the concentration in the above range, excess oxygen can be suppressed from burning ethanol or acetone, and the temperature distribution in the catalyst layer can be reduced, thereby improving the yield of acetone, which is preferable.

[0039] In the raw material gas used in the method for producing acetone of the present disclosure, the molar ratio of oxygen to ethanol is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more. A molar ratio of oxygen to ethanol of 0.01 or more is preferred because it suppresses a decrease in the temperature of the catalyst layer and improves the acetone yield. In addition, in the raw material gas used in the method for producing acetone of the present disclosure, the molar ratio of oxygen to ethanol is preferably 1.4 or less, more preferably 0.8 or less, and even more preferably 0.3 or less. When the molar ratio of oxygen to ethanol is 1.4 or less, combustion of ethanol and acetone can be suppressed and the acetone yield does not decrease, which is preferable. That is, the molar ratio of oxygen to ethanol in the raw material gas used in the method for producing acetone of the present disclosure is preferably 0.01 to 1.4, more preferably 0.05 to 0.8, and even more preferably 0.1 to 0.3.

[0040] The reaction pressure in the reaction step of the method for producing acetone according to the present disclosure can be reduced pressure, normal pressure, or increased pressure, but is preferably 0.07 MPa to 0.2 MPa, and more preferably 0.1 MPa to 0.15 MPa.

[0041] In the reaction step of the production method of the present disclosure, the temperature at which ethanol, water, and oxygen are brought into contact, i.e., the reaction temperature between ethanol and water, is preferably 250° C. to 600° C., more preferably 300° C. to 550° C., even more preferably 330° C. to 500° C., still more preferably 350° C. to 450° C., particularly preferably 365° C. to 435° C., and most preferably 365° C. to 415° C. By carrying out the reaction at such a reaction temperature, the decrease in catalytic activity over time tends to be suppressed. In the method for producing acetone disclosed herein, the reaction temperature between ethanol and water is carried out using a catalyst, and therefore the reaction temperature of the ethanol and water herein refers to the average temperature of the catalyst layer, which is the average value measured at 10 or more points at equal intervals in the gas flow direction from the inlet to the outlet of the catalyst layer.

[0042] Regarding the temperature difference inside the catalyst layer in the method for producing acetone according to the present disclosure, the temperature difference between the hottest location and the coldest location inside the catalyst layer is preferably 100°C or less, more preferably 70°C or less, and even more preferably 50°C or less.

[0043] In the disclosed method for producing acetone, the space velocity of the reaction gas is 100 h -1 ~10000h -1 It is preferable that the temperature is 300 h. -1 ~9000h -1 and more preferably, 500h -1 ~8000h -1 and particularly preferably 900h -1 ~6000h -1 and most preferably 2500h -1 ~5000h -1Generally, the higher the space velocity of the reactant gas, the more difficult it is to sufficiently advance the reaction. By using the method for producing acetone of the present disclosure, the reaction of synthesizing acetone from ethanol can be sufficiently advanced even when the space velocity of the reactant gas is high. Therefore, by carrying out the reaction at such a space velocity of the reactant gas, it is possible to produce more acetone per unit time.

[0044] In the disclosed acetone production method, the space-time yield is 300 kg / (m 3 ·h) or more, and more preferably 575 kg / (m 3 ·h) or more, and more preferably 775 kg / (m 3 ·h) or more.

[0045] In the present invention, the reason why acetone can be stably produced while maintaining a high space-time yield is presumed to be mainly due to the following (1) and (2). (1) When producing acetone from ethanol and water, the by-product hydrogen reacts with oxygen in the reaction gas to form water, which generates heat and offsets the heat absorbed when acetone is produced from ethanol and water (this contributes to the stable progress of the reaction that produces acetone from ethanol and water). (2) The reaction gas contains a moderate concentration of molecular oxygen, so that most of the molecular oxygen is used to burn hydrogen (because molecular oxygen hardly burns ethanol or acetone, most of the ethanol contained in the reaction gas is used to react with water. In addition, most of the acetone produced can be recovered as a product). However, it goes without saying that such a mechanism is merely speculation and does not limit the technical scope of the present invention.

[0046] <Other processes> The method for producing acetone according to the present disclosure may include steps other than the reaction step, such as a purification step and a catalyst regeneration step.

[0047] In the acetone production method of the present disclosure, the higher the ethanol conversion rate, acetone selectivity, and acetone yield, the better. However, the ethanol conversion rate is preferably 89% or more, and the acetone selectivity and acetone yield are both preferably 50% or more. The conversion rate of ethanol, the selectivity and yield of acetone can be determined by the methods described in the examples below.

[0048] [Acetone production apparatus of the present disclosure] The production apparatus for carrying out the acetone production method of the present disclosure is preferably a fixed-bed reactor. Alternatively, the production apparatus may be a fixed-bed reactor connected to a vaporizer for obtaining a raw material gas. The material of the production equipment is not particularly limited, but is preferably stainless steel, and typical examples of stainless steel include austenitic stainless steel such as SUS304, SUS304L, SUS316, and SUS316L of the Japanese Industrial Standards (hereinafter also referred to as JIS).

[0049] [Uses of acetone according to the present disclosure] The use of acetone produced by the acetone production method of the present disclosure is not particularly limited, but it can be suitably used as a raw material for producing isopropyl alcohol. The acetone produced by the acetone production method of the present disclosure can be hydrogenated by a known method, for example, to produce isopropyl alcohol. This method for producing isopropyl alcohol, which includes a step of producing acetone by the acetone production method of the present disclosure and a step of hydrogenating the obtained acetone to produce isopropyl alcohol, also constitutes one aspect of the present invention. [Example]

[0050] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the invention by making appropriate modifications within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0051] (Synthesis Example 1) 629 g of zinc nitrate hexahydrate, 562 g of zirconium nitrate dihydrate, 1700 g of iron nitrate nonahydrate, 32.8 g of cesium nitrate, and 1545 g of 28 wt% aqueous ammonia were added to 3800 g of purified water and stirred for 20 hours to obtain a starting material mixture. The resulting starting material mixture was dried in a drum dryer at 150 °C, and the dried product was crushed and sieved to 150 μm or smaller to obtain a catalyst precursor powder. The resulting catalyst precursor powder was calcined in an air atmosphere at 450 °C for 4 hours to obtain a catalyst powder. 500 g of the resulting catalyst powder, 5 g of hydroxyethyl cellulose, and 100 g of water were placed in an extruder and formed into a cylindrical shape with a diameter of 6 mm and a length of 6 mm to obtain a pre-calcined catalyst compact. The resulting pre-calcined catalyst compact was calcined in an air atmosphere at 450 °C for 4 hours to obtain a catalyst (FeZnZrO catalyst: Fe2ZnZrO6).

[0052] (Synthesis Example 2) 498 g of lanthanum nitrate hexahydrate, 308 g of zirconium nitrate dihydrate, 1000 g of copper nitrate trihydrate, and 926 g of 85 wt% potassium hydroxide were added to 1500 g of purified water and stirred for 20 hours to obtain a starting material mixture. The resulting starting material mixture was filtered, and the filtration residue was washed with purified water until the pH of the filtrate was within the range of 6 to 8. The washed filtration residue was placed in a dryer at 120 °C and dried for 20 hours. The resulting dried product was then crushed and sieved to 150 μm or smaller to obtain a catalyst precursor powder. The resulting catalyst precursor powder was calcined in an air atmosphere at 450 °C for 4 hours to obtain a catalyst powder. 500 g of the resulting catalyst powder, 5 g of hydroxyethyl cellulose, and 100 g of water were placed in an extruder and formed into a cylindrical shape with a diameter of 6 mm and a length of 6 mm to obtain a pre-calcined catalyst molded body. The obtained pre-calcined catalyst molded body was calcined in an air atmosphere at 450°C for 4 hours to obtain a catalyst (CuLaZrO catalyst: Cu2La2ZrO7).

[0053] Example 1 Acetone production using the catalyst synthesized in Synthesis Example 1 was carried out using a U-shaped SUS316 reactor (outer diameter 25.6 mm, inner diameter 21.6 mm). 140 g of catalyst was packed into a U-shaped SUS reactor tube with a 3 mm outer diameter SUS thermometer protection tube inserted at the center. The length of the packed catalyst layer was 340 mm. The catalyst-packed reactor tube was placed in a molten salt bath, and nitrogen was supplied at 5.2 L / min (equivalent to 0°C and 1 atmospheric pressure). The molten salt bath was heated to 375°C and maintained at this temperature for 30 minutes. Subsequently, nitrogen, ethanol, and water (steam) were supplied as reaction gases at 5.0 L / min (equivalent to 0°C and 1 atmospheric pressure), 1.0 L / min (equivalent to 0°C and 1 atmospheric pressure), and 4.0 L / min (equivalent to 0°C and 1 atmospheric pressure), respectively, to carry out the reaction. One hour after the start of the reaction gas supply, the flow rates of ethanol and water were maintained at 1.0 L / min (0°C, 1 atm equivalent) and 4.0 L / min (0°C, 1 atm equivalent), respectively. The nitrogen flow rate was reduced to 4.0 L / min (0°C, 1 atm equivalent), and air was supplied at 1.0 L / min (0°C, 1 atm equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured. The total vaporization energy of water and ethanol per mole of ethanol was also calculated. Here, the ethanol conversion rate, acetone selectivity, and acetone yield were calculated using equations (1), (2), and (3).

[0054]

number

[0055]

number

[0056]

number

[0057] [ka]

[0058] The acetone yield in equation (3) is evaluated based on the amount of carbon in the acetone produced relative to the total carbon in the ethanol supplied to the reactor inlet. Therefore, the maximum acetone yield is 75%. The reactor outlet gas was introduced into an absorption bottle filled with pure water placed in an ice-water bath, and the components captured by the water were quantified by gas chromatography. Components not captured in the absorption bottle were quantified by introducing the absorption bottle outlet gas into a gas chromatograph. The flow rates of each component contained in the reactor outlet gas were calculated from these analytical values, and the ethanol conversion, acetone selectivity, and acetone yield were calculated using the above equations (1), (2), and (3). The temperature of the catalyst layer was measured at 34 points at 10 mm intervals from the inlet to the outlet of the catalyst layer, and the average of these temperatures was calculated as the average catalyst layer temperature (°C). The vaporization energy of water and ethanol per mole of ethanol was calculated from the gas flow rate at the reactor inlet and the reaction temperature using the chemical process simulator COCO / ChemSep.

[0059] Example 2 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 4.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 0.05 L / min (0 ° C., 1 atmospheric pressure equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0060] Example 3 Except for changing the ethanol used to biomass-derived ethanol, the reaction was carried out in the same manner as in Example 1. Two hours after the start of the reaction, the ethanol conversion rate, acetone selectivity, and acetone yield were measured.

[0061] Example 4 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 2.5 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 4.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 2.5 L / min (0 ° C., 1 atmospheric pressure equivalent). The ethanol conversion, acetone selectivity, and acetone yield were measured two hours after the start of the reaction.

[0062] Example 5 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 0.23 L / min (0 ° C., 1 atmospheric pressure equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0063] Example 6 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 2.0 L / min (0 ° C., 1 atmospheric pressure equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0064] Example 7 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0.1 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 0.5 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 0.2 L / min (0 ° C., 1 atmospheric pressure equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0065] Example 8 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and after 1 hour from the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 5.0 L / min (0°C, 1 atmosphere equivalent), 1.0 L / min (0°C, 1 atmosphere equivalent), and 12.0 L / min (0°C, 1 atmosphere equivalent), respectively, and air was supplied at 2.0 L / min (0°C, 1 atmosphere equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured. However, due to the large amount of water, the total vaporization energy of water and ethanol per mole of ethanol was high, making it impossible to produce acetone inexpensively. Furthermore, it was found that insufficient vaporization could pose a risk of electrical leakage from the vaporization device due to water leakage. Therefore, the reaction was stopped.

[0066] Example 9 The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 4.0 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 4.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent). The ethanol conversion, acetone selectivity, and acetone yield were measured two hours after the start of the reaction.

[0067] Example 10 The reaction was carried out in the same manner as in Example 1, except that the catalyst used was changed to the catalyst synthesized in Synthesis Example 2, the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 4.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 0.05 L / min (0 ° C., 1 atmospheric pressure equivalent). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0068] Example 11 The catalyst used was changed to the catalyst synthesized in Synthesis Example 2, the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 3.8 L / min (0 ° C, 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C, 1 atmospheric pressure equivalent), and 4.0 L / min (0 ° C, 1 atmospheric pressure equivalent), respectively, and air was supplied at 1.2 L / min (0 ° C, 1 atmospheric pressure equivalent). The reaction was carried out in the same manner as in Example 1. Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0069] (Comparative Example 1) 140 g of the catalyst synthesized in Synthesis Example 1 was packed into the same U-shaped SUS reactor tube as in Example 1. The reactor tube packed with the catalyst was placed in a molten salt bath, and nitrogen was supplied at 5.2 L / min (equivalent to 0°C and 1 atmospheric pressure). The molten salt bath was heated to 375°C and maintained at this temperature for 30 min. Thereafter, nitrogen, ethanol, and water (water vapor) were supplied at 5.0 L / min (equivalent to 0°C and 1 atmospheric pressure), 1.0 L / min (equivalent to 0°C and 1 atmospheric pressure), and 4.0 L / min (equivalent to 0°C and 1 atmospheric pressure), respectively, to carry out the reaction. The ethanol conversion rate and acetone yield were measured 2 hours after the start of the reaction using the same method as in Example 1.

[0070] (Comparative Example 2) The ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0 L / min (0°C, 1 atmosphere), 1.0 L / min (0°C, 1 atmosphere), and 4.0 L / min (0°C, 1 atmosphere), respectively, and air was supplied at 7.5 L / min (0°C, 1 atmosphere). However, due to the mixing ratio of each gas in the mixture containing ethanol, oxygen, etc., there was a risk of explosion, so the reaction was stopped.

[0071] (Comparative Example 3) The reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol, and one hour after the start of the reaction gas supply, the flow rates of nitrogen, ethanol, and water were set to 0.23 L / min (0 ° C., 1 atmospheric pressure equivalent), 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), and 1.0 L / min (0 ° C., 1 atmospheric pressure equivalent), respectively, and air was supplied at 0 L / min (0 ° C., 1 atmospheric pressure equivalent). The ethanol conversion, acetone selectivity, and acetone yield were measured two hours after the start of the reaction.

[0072] [Table 1]

[0073] The molar percentages of the reaction gas, the total vaporization energy of water and ethanol per mole of ethanol, and the reaction results are shown in Table 1. As can be seen from Table 1, when molecular oxygen was contained in the reaction gas, the average catalyst layer temperature was high, the reaction was possible with a high ethanol conversion rate, and the selectivity for the product acetone was excellent. In other words, it was revealed that acetone could be produced stably while maintaining a high space-time yield. Note that the molar percentages of the reaction gas in Table 1 are the molar percentages of each gas contained in the reaction gas after the start of air supply for Examples 1 to 11 and Comparative Example 2.

Claims

1. A method for producing acetone, comprising a step of synthesizing acetone by contacting ethanol with water in the presence of a catalyst, In the step of synthesizing acetone, a reaction gas containing ethanol, water, and oxygen is used as a raw material, and the oxygen concentration in the reaction gas is 0.1 mol % to 10 mol %.

2. 2. The method for producing acetone according to claim 1, wherein the molar ratio of water to ethanol is 0.50 or more and 10 or less.

3. 3. The method for producing acetone according to claim 1, wherein the molar ratio of oxygen to ethanol is 0.01 or more and less than 1.

4.

4. 3. The method for producing acetone according to claim 1, wherein a total of vaporization energies of the water and the ethanol per mole of the ethanol is 700 kW or less.

5. 3. The method for producing acetone according to claim 1, wherein the catalyst contains at least a transition metal element excluding rare earth elements and / or a rare earth element.

6. 3. The method for producing acetone according to claim 1, wherein the temperature at which the ethanol and water are brought into contact with each other is 250°C to 600°C.

7. The space velocity of the reaction gas is 100 h －１ ~10,000h －１ 3. The method for producing acetone according to claim 1 or 2,

8. 3. The method for producing acetone according to claim 1 or 2, wherein the ethanol includes ethanol derived from biomass.

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