Method for producing acetone

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

Acetone Production Method

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

[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.

[0003] JP 2009-209059 A JP 2012-240913 A

[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.

[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 a step of synthesizing acetone by contacting ethanol with water in the presence of a catalyst, 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 vaporization energy of the water and the ethanol per 1 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 ~10,000h －１ The method for producing acetone according to any one of [1] to [6],

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

[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.

[0016] The present disclosure will be described in detail below. Note that a combination of two or more of the individual preferred embodiments of the present disclosure described below is also a preferred embodiment of the present disclosure. Note that in this specification, the range "X to Y" means "at least X and at most Y."

[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, and any catalyst that can produce acetone from ethanol and water will do, but those that provide a high acetone yield are preferred.

[0019] The catalyst of the present disclosure is not particularly limited, and examples thereof include metal oxides containing metal elements, carriers containing metal elements, and carriers supporting simple metal elements or metal oxides. The metal oxide may be an oxide of a single metal element, or a composite oxide containing two or more metal elements. Examples of composite metal oxides include those with crystalline structures such as spinel, perovskite, magnetoplumbite, and garnet, as well as amorphous oxides and those having both crystalline and amorphous portions. Examples of carriers include activated carbon, silica, alumina, silica-alumina, zeolite, silica-calcia, zirconia, ceria, magnesia, and diatomaceous earth. Note that the term "catalyst" used here refers to the catalyst in its state before the start of the reaction.

[0020] The metal elements contained in the catalyst of the present disclosure preferably include transition metal elements and / or rare earth elements excluding rare earth elements. The transition metal elements excluding rare earth 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 elements contained in the catalyst of the present disclosure are preferably lanthanum, praseodymium, and neodymium, more preferably lanthanum. The catalyst of the present disclosure preferably contains copper and / or iron, zirconium, and further contains transition metal elements and / or rare earth elements excluding rare earth elements other than copper, iron, and zirconium. More preferably, the catalyst contains copper and / or iron, zirconium, and further contains zinc or lanthanum.

[0021] The content of the metal element contained in the catalyst of the present disclosure is preferably 0.1% by mass to 95% by mass, more preferably 30% by mass to 90% by mass, even more preferably 50% by mass to 87% by mass, and particularly preferably 60% by mass to 87% by mass, relative to the total amount of the catalyst. Another preferred embodiment of the catalyst of the present disclosure is one in which the content of the metal element contained in the catalyst is 1 to 75% by mass. The content of the metal element contained in the catalyst of the present disclosure here refers to the content of the metal element in the catalyst before the start of the reaction. The content of the metal element can be measured by X-ray fluorescence analysis (XRF). A 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 acetone production method of the present disclosure is not particularly limited, and examples include spherical, pellet, honeycomb, ring, and granular shapes. The dimensions of the catalyst used in the acetone production method of the present disclosure are not particularly limited, but the average particle size of the catalyst is preferably 1 mm to 12 mm, and more preferably 3 mm to 10 mm. Having the average particle size of the catalyst within the above range facilitates packing the catalyst into the reaction tube and reduces pressure loss in the catalyst layer, 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 to the diameter of the circumscribed sphere of the catalyst in the case of other shapes.

[0023] <Contact of Ethanol, Water, and Oxygen> The method for producing acetone according to the present disclosure includes a step of synthesizing acetone by contacting ethanol with water in the presence of a catalyst (hereinafter, the contact may also be referred to as a reaction) (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 system, the reaction gas (hereinafter sometimes referred to as a feed 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 even 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 gaseous or mist form, but is preferably in gaseous form. Gaseous ethanol can be obtained, for example, by heating liquid ethanol in a vaporizer. Furthermore, the water of the present disclosure may be in gaseous or mist form, but is preferably in gaseous form. Gaseous water can be obtained, for example, by heating water in a vaporizer. The raw material gas only needs to contain oxygen (molecular oxygen), and may 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 feed 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. Furthermore, the concentration of ethanol contained in the feed 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. A concentration of 66 mol% or less allows for a sufficient amount of oxygen to coexist with ethanol. That is, the concentration of ethanol contained in the feed gas is preferably 3 to 66 mol%, more preferably 3 to 50 mol%, even more preferably 5 to 30 mol%, and particularly preferably 8 to 10 mol%.

[0031] The water concentration contained in the feed 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 water concentration of 20 mol% or more allows for efficient production of acetone. Furthermore, the water concentration contained in the feed 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. A water concentration of 80 mol% or less can reduce the total vaporization energy of water and ethanol per mole of ethanol, allowing for low-cost production of acetone. In other words, the water concentration contained in the feed gas is preferably an amount that results in a water concentration 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%. A water concentration within this range allows for a higher acetone yield.

[0032] In the feed gas used in the acetone production method 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 acetone selectivity. Furthermore, in the feed gas used in the acetone production method of the present disclosure, the molar ratio of water to ethanol is preferably 10 or less, more preferably 7.0 or less, and even more preferably 4.5 or less. A molar ratio of oxygen to ethanol of 10 or less is preferable because it can reduce the total vaporization energy of water and ethanol per mole of ethanol, allowing acetone to be produced at low cost. That is, the molar ratio of water to ethanol in the feed gas used in the acetone production method 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 acetone production method of the present disclosure preferably has a total vaporization energy of water and ethanol per mole of ethanol of 700 kW or less. 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 water and ethanol per mole of ethanol, 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 water and ethanol per mole of ethanol 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 in the raw gas is burned and all of it is converted into carbon dioxide. 2. The carbon dioxide is separated and purified using a vacuum line. 3. The carbon dioxide produced from the ethanol is reduced in its entirety with hydrogen using iron as a catalyst to produce graphite. 4. NEC Corporation １４ Using a C-AMS measurement device, the graphite derived from ethanol １４ C concentration and １３ C concentration ratio ( １４ C / １３ 5. The same method as above 1 to 4 was used to measure oxalic acid (hereinafter also referred to as the standard sample) from the same year that the raw material ethanol was produced, provided by the National Institute of Standards (NIST). １４ C concentration and １３C concentration ratio ( １４ C / １３ C) is measured. 6. Graphite derived from raw material ethanol １４ C / １３ The value of C is １４ C / １３ The value divided by the C value is multiplied by 100 to obtain the bioethanol content.

[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 acetone yield. Furthermore, 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 suppress a decrease in acetone yield due to combustion of the produced acetone and ethanol with oxygen, and it can obtain acetone in a high yield by selectively combusting the produced hydrogen.

[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 within 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.

[0039] In the feed gas used in the acetone production method 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 preferable because it suppresses a temperature drop in the catalyst layer and improves the acetone yield. Furthermore, in the feed gas used in the acetone production method 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. A molar ratio of oxygen to ethanol of 1.4 or less is preferable because it can suppress the combustion of ethanol and acetone and does not reduce the acetone yield. That is, the molar ratio of oxygen to ethanol in the feed gas used in the acetone production method 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 any of reduced pressure, normal pressure, and 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, even more preferably 350°C to 450°C, particularly preferably 365°C to 435°C, and most preferably 365°C to 415°C. Reaction at such a reaction temperature tends to suppress the decrease in catalytic activity over time. Since the acetone production method of the present disclosure uses a catalyst for the reaction, the reaction temperature between ethanol and water referred to here means the average temperature of the catalyst layer. Furthermore, the average temperature of the catalyst layer 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 acetone production method of the present disclosure, the space velocity of the reaction gas is 100 h －１ ~10,000h －１ It is preferable that the temperature is 300 h. －１ ~9000h －１ and more preferably 500 h －１ ~8000h －１ and particularly preferably 900h －１ ~6000h －１ and most preferably 2500h －１ ~5000h －１ Generally, 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] The reason why acetone can be stably produced while maintaining a high space-time yield in the present invention is believed 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 endothermic heat generated when acetone is produced from ethanol and water (this contributes to the stable progress of the reaction that produces acetone from ethanol and water); and (2) because the reaction gas contains a moderate concentration of molecular oxygen, most of the molecular oxygen is used to combust hydrogen (because molecular oxygen hardly combusts 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 these mechanisms are merely speculations and do not limit the technical scope of the present invention.

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

[0047] In the acetone production method of the present disclosure, the higher the ethanol conversion rate, acetone selectivity, and yield, the better, but the ethanol conversion rate is preferably 89% or higher, and the acetone selectivity and acetone yield are both preferably 50% or higher. The ethanol conversion rate, acetone selectivity, and acetone yield values ​​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. The production apparatus may also be a fixed-bed reactor connected to a vaporizer for obtaining a raw material gas. The material of the production apparatus is not particularly limited, but stainless steel is preferred. Representative examples of stainless steel include austenitic stainless steels such as SUS304, SUS304L, SUS316, and SUS316L according to the Japanese Industrial Standards (hereinafter also referred to as JIS).

[0049] [Uses of Acetone of 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. Such a 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.

[0050] The present invention will be explained in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is of course 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 pure 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 resulting dried product was then pulverized and sieved to 150 μm or less to obtain a catalyst precursor powder. The resulting catalyst precursor powder was calcined for 4 hours in an air atmosphere at 450°C 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 molded 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 resulting pre-calcined catalyst molded body was calcined for 4 hours in an air atmosphere at 450°C to obtain a catalyst (FeZnZrO catalyst:Fe ２ ZnZrO ６ ) was obtained.

[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 pure 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 pure 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, and then the resulting dried product was crushed and sieved to 150 μm or less 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 molded 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 at 450°C for 4 hours in an air atmosphere to obtain a catalyst (CuLaZrO catalyst: Cu ２ La ２ ZrO ７ ) was obtained.

[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 atmosphere equivalent) and 4.0 L / min (0°C, 1 atmosphere equivalent), respectively. The nitrogen flow rate was reduced to 4.0 L / min (0°C, 1 atmosphere equivalent), and air was supplied at 1.0 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. The total vaporization energy of water and ethanol per mole of ethanol was also calculated. The ethanol conversion, acetone selectivity, and acetone yield were calculated using equations (1), (2), and (3).

[0054]

[0055]

[0056] The reaction for synthesizing acetone from ethanol and water is represented by the following reaction formula (4).

[0057]

[0058] The acetone yield in equation (3) is evaluated by the amount of carbon in the acetone produced relative to the total carbon contained 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 containing pure water placed in an ice-water bath, and the components captured by the water were quantified using a gas chromatograph. 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 equations (1), (2), and (3) above. 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 rates 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) A reaction was carried out in the same manner as in Example 1, except that the ethanol used was changed to biomass-derived ethanol. 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). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[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 discontinued.

[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). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[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). The ethanol conversion, acetone selectivity, and acetone yield were measured two hours after the start of the reaction.

[0068] Example 11 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 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). 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 SUS U-shaped reaction tube as in Example 1. The reaction 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). Two hours after the start of the reaction, the ethanol conversion, acetone selectivity, and acetone yield were measured.

[0072]

[0073] The mole 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 mole percentages of the reaction gas in Table 1 are the mole 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, 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 %.

2. 2. The method for producing acetone according to claim 1, wherein a 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 or 2, wherein a 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 or 2, 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 or 2, 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 or 2, wherein the temperature at which the ethanol and water are contacted is 250° C. to 600° C.

7. The space velocity of the reaction gas is 100 h －１ ~10000h －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.