High yield and low cost production of acrolein or acrylic acid from isopropanol

Abstract

Acrolein is produced by selectively oxidizing isopropanol over a first mixed metal oxide catalyst in the presence of oxygen in the gas phase. The first mixed metal oxide catalyst comprises oxides of molybdenum and bismuth. Acrylic acid is produced by selectively oxidizing acrolein over a second mixed metal oxide catalyst in the presence of oxygen in the gas phase. The second mixed metal oxide catalyst has a different composition than the first mixed metal oxide catalyst.

Description

[Technical Field]

[0001] The present invention relates to a process for selectively oxidizing isopropanol to produce acrolein, and further to a process for selectively oxidizing the produced acrolein to produce acrylic acid. [Background technology]

[0002] Various processes for preparing acrylic acid are known in the art. Most commercially available acrylic acid is produced using fossil fuel-derived raw materials such as propylene.

[0003] Most commercially available isopropanols are produced via the hydration of propylene derived from fossil fuels, or via the hydrogenation of acetone, a byproduct of phenol production. Small amounts of acetone are produced from carbohydrates such as starch and glucose via the conventional acetone-butanol-ethanol (ABE) fermentation process. Therefore, it is more economically preferable to produce acrylic acid directly from propylene.

[0004] The increasing demand for bio-derived carbon in chemical products is driving increased research efforts to improve the effectiveness of intentional production of isopropanol from non-food biomass such as sugarcane or crop residues. However, there is still a need for methods to produce acrolein and / or acrylic acid from biomass-derived raw materials. [Overview of the Initiative]

[0005] The present invention relates to a method for preparing acrolein from isopropanol, and further to a method for producing acrylic acid from acrolein.

[0006] According to one aspect of the present invention, the method comprises selectively oxidizing isopropanol on a first mixed metal oxide catalyst in the presence of oxygen in the gas phase to produce acrolein, wherein the first mixed metal oxide catalyst comprises oxides of molybdenum and bismuth.

[0007] Another aspect of the present invention further comprises selectively oxidizing acrolein on a second mixed metal oxide catalyst in the presence of oxygen in the gas phase, wherein the second mixed metal oxide catalyst has a different composition from the first mixed metal oxide catalyst. [Modes for carrying out the invention]

[0008] As used herein, the terms “a,” “an,” “the,” “at least one,” and “one or more” are interchangeable. The terms “comprise,” “include,” and “contain,” and their variations, are not limited in meaning when they appear herein and in the claims. For example, a mixture containing a polymerization inhibitor can be interpreted as meaning that the mixture contains at least one polymerization inhibitor.

[0009] Where used herein, when a numerical range is given by an endpoint, it includes all numbers contained within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). For the purposes of the present invention, it should be understood, in accordance with what those skilled in the art would understand, that a numerical range is intended to include and support all possible subranges that may fall within that range. For example, the range 1 to 100 is intended to convey 1.1 to 100, 1 to 99.99, 1.01 to 99.99, 40 to 6, 1 to 55, etc.

[0010] Where used herein, such enumeration in the claims, including any enumeration of numerical ranges and / or numerical values, can be read as including the term “about,” where “about” means numerical ranges and / or numerical values ​​that are substantially the same as those enumerated herein.

[0011] Unless otherwise specified or implicit from the context, all parts and percentages are by weight, and all test methods are as of the filing date of this application. For the purposes of U.S. patent practice, the content of any referenced patent, patent application, or patent application publication is incorporated by reference in its entirety (or the equivalent U.S. version thereof is incorporated by reference in like manner) with respect to specific definitions of disclosure (to the extent not inconsistent with any definitions specifically provided in this disclosure) and general knowledge in the relevant technical field.

[0012] One aspect of the present invention relates to a method for producing acrolein from isopropanol.

[0013] In the process of the present invention, isopropanol is selectively oxidized on a first mixed metal oxide catalyst in the presence of oxygen in the gas phase.

[0014] The first mixed metal oxide catalyst is a solid catalyst containing oxides of molybdenum (Mo) and bismuth (Bi). The first mixed metal oxide catalyst may also contain at least one additional element selected from iron (Fe), cobalt (Co), nickel (Ni), or combinations thereof. When the first mixed metal oxide catalyst contains at least one additional element, molybdenum and bismuth are the major metal elements present. Preferably, the first mixed metal oxide catalyst contains at least 40 wt%, such as at least 50 wt%, at least 60 wt%, or at least 70 wt% of molybdenum and bismuth based on the total weight of the metals in the first mixed metal oxide catalyst.

[0015] The first mixed metal oxide catalyst can be any commercially available catalyst used for the oxidation of propylene to acrolein.

[0016] The yield of acrolein based on the isopropanol feedstock is preferably greater than 60%, and the mass ratio of propionic acid, a by-product of the reaction, to acrolein is preferably less than 0.002.

[0017] Acetone can be formed as a byproduct of the oxidation reaction of isopropanol to acrolein. To reduce the amount of acetone formed, the oxygen level in the first reactor may be increased. Alternatively, the reactor temperature may be adjusted to be favorable for the production of acrolein.

[0018] Another aspect of the present invention relates to the production of acrylic acid from isopropanol. The process of the present invention for producing acrylic acid from isopropanol is a two-step process. In the first step, isopropanol is selectively oxidized on a first mixed metal oxide catalyst to form acrolein as described above.

[0019] Next, in the second step, acrolein is selectively oxidized on a second mixed metal oxide catalyst in the presence of oxygen in the gas phase, and the second mixed metal oxide catalyst has a composition different from that of the first mixed metal oxide catalyst.

[0020] The second mixed metal oxide catalyst is a solid catalyst containing oxides of molybdenum (Mo) and vanadium (V). The second mixed metal oxide catalyst may also contain at least one additional element selected from tungsten (W), copper (Cu), iron (Fe), antimony (Sb), and phosphorus (P). When the second mixed metal oxide catalyst contains at least one additional element, molybdenum and vanadium are the main metal elements present. Preferably, the second mixed metal oxide catalyst contains at least 40% by weight, for example, at least 50% by weight, at least 60% by weight, or at least 70% by weight of molybdenum and vanadium based on the total weight of the metals in the second mixed metal oxide catalyst.

[0021] The second mixed metal oxide catalyst can be any commercially available mixed metal oxide catalyst used for the oxidation of acrolein to acrylic acid.

[0022] The yield of acrylic acid based on the isopropanol feed is preferably greater than 70%, and the mass ratio of propionic acid, which is a byproduct of the reaction, to acrylic acid is preferably less than 0.001.

[0023] In the selective oxidation reaction to form acrolein and / or acrylic acid, oxygen can be present in the form of purified oxygen, oxygen in air, or lattice oxygen of a mixed metal oxide catalyst. Preferably, the oxygen is from air or from the lattice oxygen of the mixed metal oxide catalyst.

[0024] In either the selective oxidation of isopropanol to produce acrolein or the selective oxidation of acrolein to produce acrylic acid, steam can be added to assist the reaction.

[0025] Purification of acrolein and / or acrylic acid can be achieved by one or more techniques known in the art, such as absorption, extraction, fractional distillation, or melt crystallization using water or an organic solvent.

[0026] Preferably, isopropanol is produced from biomass-derived feedstocks. For example, isopropanol can be produced via bioconversion. For example, isopropanol can be formed by isopropanol - butanol - ethanol (IBE) fermentation.

[0027] Both plants and animals, like all living organisms, contain a certain amount of carbon 14 ( 14 C), which is produced in the atmosphere and fixed by plants during photosynthesis. 14 The ratio of 12 C to -12 C is in the range of 1 to 1.5×10 14 Carbon 14 is a radioactive substance with a half-life of approximately 5700 years. Thus, biomass-derived feedstocks contain the same 12 C to -12 ratio as living organisms, i.e., approximately 1 to 1.5×10

[0028] Preferably, the acrolein and / or acrylic acid produced by the process of the present invention contains at least 0.5×10 -13 of 14C 12 This includes the ratio to C. More preferably, the acrolein and / or acrylic acid produced by the process of the present invention contains at least 0.75 × 10⁻¹⁶. -13 of 14 C 12 This includes the ratio to C. More preferably, the acrolein and / or acrylic acid produced by the process of the present invention contains at least 0.8 × 10 -13 of 14 C 12 Includes the ratio to C. Most preferably, the feedstock used in the process of the present invention is supplied entirely from biomass-derived materials. 14 C 12 The ratio to C is the same as that found in nature, i.e., approximately 1 to 1.5 × 10 -12 That is the case. [Examples]

[0029] The following examples illustrate the present invention, but are not intended to limit its scope.

[0030] I. Examples of the present invention: Oxidation of isopropanol to acrolein To produce acrylic acid, isopropanol was oxidized primarily to acrolein in a first-stage reactor. The catalyst used in the first-stage reactor was a mixed oxide catalyst of Mo and Bi, hereafter abbreviated as R1 catalyst. In this example, 10 mL of the Mo and Bi-based R1 catalyst from Nippon Kayaku Co. (Tokyo, Japan) was packed into a first-stage tubular reactor made of stainless steel (SS) with an outer diameter (OD) of 1 / 2 inch (1.27 cm), which was heated in a fluidized sand reactor. The reactor was heated to the desired reactor temperature in a fluidized gas mixture of 171.80 sccm of air and 38.2 sccm of N2, and then a liquid mixture containing isopropanol and deionized water was injected at a rate of 3.22 g / h for isopropanol and at a rate of 0.96 g / h for water.

[0031] The product mixture from the first-stage reactor (abbreviated as R1 effluent) was collected and analyzed. The R1 effluent first flowed through Trap 1, a 100–500 mL stainless steel container wrapped in a 1 / 4-inch (0.635 cm) copper coil connected to a recirculation chiller set to 0–1°C. The gas escaping from Trap 1 flowed through Trap 2, a second trap immersed in water / ice, and third and fourth traps (Traps 3A and 3B) immersed in a dry ice / isopropanol mixture. Trap 2 primarily functioned as a protective trap to prevent large amounts of water or acrylic acid from entering the dry ice / isopropanol trap, as water / acrylic acid could freeze and increase pressure within the dry ice / isopropanol trap. The trap collection time was typically 2–4 hours. To prevent polymer formation, 6–12 grams of inhibitor solution were injected into Trap 2, Traps 3A and 3B before sample collection. Trap 2 recovered only very small amounts of material in most cases. 0.2% by weight of hydroquinone in ethanol was used as the inhibitor solution.

[0032] Off-gas from dry ice / isopropanol traps were analyzed online by gas chromatography with a thermal conductivity detector and a 5 Å molecular sieve / silica gel column. The main gaseous components of the off-gas typically included nitrogen, oxygen, unreacted propylene, carbon monoxide, and carbon dioxide. The liquids recovered from trap 1 and trap 2 (if present) were combined into a single sample and labeled as the T-1 sample. The liquids recovered from trap 3A and trap 3B were labeled as the T-3A and T-3B samples, respectively. The T-1, T-3A, and T-3B samples were sent for offline analysis by gas chromatography with a flame ionization detector and a capillary column (DB-FFAP 123-3232E). The conversion rate of propylene, the mass balance of carbon, and the analysis of acrylic acid, acrolein, acetaldehyde, propionaldehyde, propionic acid, acetic acid, and CO2 were performed. x The yields of major or by-products such as (CO and CO2) are calculated using the following formula: Isopropanol conversion rate (%) = (Number of moles of isopropanol supplied - Number of moles of isopropanol in R1 waste) / Number of moles of isopropanol supplied. Carbon mass balance (%) = (Total amount of carbon from molecules in R1 emissions including CO2, CO, propylene, acetaldehyde, acrolein, acetic acid, propionic acid, and acrylic acid) / (Total amount of carbon from supplied isopropanol) * 100.

[0033] The yields of acrolein, acetaldehyde, and acrylic acid after the second-stage reactor, as well as the carbon mass balance, were calculated using the following formula: Product yield (%) = (moles of product in R1 effluent) / moles of isopropanol supplied * 100

[0034] The tests were conducted at two different reaction vessel temperatures (327°C and 347°C). In Example 1, the vessel temperature was 327°C, the peak bed temperature was 330°C, resulting in a conversion rate of 99.3% and a carbon mass balance of 104.3%. In Example 2, the vessel temperature was 347°C, the peak bed temperature was 358°C, resulting in a conversion rate of 100% and a carbon mass balance of 111.1%. The results are listed in Table 1. With nearly complete conversion of isopropanol, the yield of acrolein reached 63.7%.

[0035] [Table 1] CO x =CO+CO2;Ald=acetaldehyde;Ace=acetone;PP=propylene;Acro=acrolein;Allyl=allyl alcohol;HAc=acetic acid;PA=propionic acid AA=acrylic acid

[0036] II. Comparative Example: One-step oxidation of isopropanol on Mo,V oxide catalysts The oxidation of isopropanol was carried out in a single step on a Mo,V-based oxide catalyst. The experiment was the same as in Example 1, except that isopropanol was directly oxidized on a commercially available catalyst from Nippon Kayaku Co., which mainly contains Mo and V.

[0037] Comparative Example 1 was carried out at a tank temperature of 320°C and a peak bed temperature of 319°C, resulting in a 100% conversion rate and a carbon mass balance of 93.5%. Comparative Example 2 was carried out at a tank temperature of 330°C and a peak bed temperature of 333°C, resulting in a 100% conversion rate and a carbon mass balance of 89.9%. In the comparative examples, the main product was propylene, and the yield of acrylic acid was less than 10%. The PA / AA mass ratio was 0.046, which was about 50 times that of Example 1.

[0038] [Table 2]

[0039] III. Examples of the present invention: Oxidation of isopropanol to acrylic acid The oxidation of isopropanol to acrylic acid was carried out in two steps. First, isopropanol was oxidized mainly to acrolein in a first-stage reactor (in this case, a tubular reactor). The catalyst used in the first-stage reactor was a Mo and Bi-based mixed oxide catalyst, hereafter abbreviated as the R1 catalyst. In this example, 10 mL of the Mo and Bi-based R1 catalyst from Nippon Kayaku Co. (Tokyo, Japan) was mixed with 10 mL of 1 / 8 inch (0.32 cm) of Denstone™ 57 beads (Saint-Gobain Norpro, Stow, OH), and then placed into a first-stage tubular reactor made of stainless steel (SS) with an outer diameter (OD) of 2.54 cm (1 inch) (inner diameter (ID) of 0.834 inches (2.11 cm)).

[0040] The product mixture from the first-stage reactor (abbreviated as R1 effluent) was sent to the second-stage reactor, which was heated by an electric heating tape in a 1 / 4-inch (0.635 cm) SS tube. The surface temperature was controlled to approximately 170 ± 10°C.

[0041] The second-stage reactor contains a Mo-V mixed oxide catalyst (abbreviated as R2 catalyst). In this example, 10 mL of commercially available Mo-V R2 catalyst was packed into the feed inlet side of a U-shaped SS tube with an outer diameter (OD) of 1 / 2 inch (1.27 cm). The other end of the U-tube was packed with Denstone® beads. The U-tube was placed in a fluidized sand furnace, and the catalyst bed was immersed in the sand. Air was used to pump the catalyst at 3.3–3.5 SCFM (standard cubic feet / min) (0.093–0.099 m³). 3 The sand was fluidized at a flow rate of ( / min). By maintaining a high airflow rate, the temperature difference within the tank was controlled to less than 3°C. The tank temperature was adjusted to achieve the desired conversion from acrolein to acrylic acid. The effluent from the second stage reactor was referred to as R2 effluent.

[0042] First, the first-stage reactor was heated to over 305°C in a clamshell electric furnace with a fluidized gas mixture of 171.80 sccm of air and 38.2 sccm of N2. The second-stage reactor was heated to 270°C. All gas flow rates were measured under standard temperature (0°C) and standard pressure (101.3 kPa) conditions. Isopropanol was mixed with deionized water (78.0 wt% of isopropanol) and injected into the SS mixer vessel at a rate of 0.073 mL / min when the reactor reached the desired temperature. The SS mixer vessel was heated to 160-170°C, and steam was supplied to the reactor by supplying air / nitrogen.

[0043] R2 effluent was collected and analyzed. The R2 effluent first flowed through Trap 1, a 100–500 mL stainless steel container wrapped in a 1 / 4-inch (0.635 cm) copper coil connected to a recirculating chiller set to 0–1°C. The gas escaping from Trap 1 flowed through Trap 2, a second trap immersed in water / ice, and then through third and fourth traps (Traps 3A and 3B) immersed in a dry ice / isopropanol mixture. Trap 2 primarily functioned as a protective trap to prevent large amounts of water or acrylic acid from entering the dry ice / isopropanol trap, as water / acrylic acid could freeze and increase pressure within the dry ice / isopropanol trap. Trap collection times were typically 2–4 hours. To prevent polymer formation, 6–12 grams of inhibitor solution were injected into Traps 2, 3A, and 3B before sample collection. Trap 2 collected very little material in most cases. A 0.2% by weight hydroquinone solution in ethanol was used as the inhibitor solution.

[0044] Off-gas from dry ice / isopropanol traps were analyzed online by gas chromatography with a thermal conductivity detector and a 5 Å molecular sieve / silica gel column. The main gaseous components of the off-gas typically included nitrogen, oxygen, unreacted propylene, carbon monoxide, and carbon dioxide. The liquids recovered from trap 1 and trap 2 (if present) were combined into a single sample and labeled as the T-1 sample. The liquids recovered from trap 3A and trap 3B were labeled as the T-3A and T-3B samples, respectively. The T-1, T-3A, and T-3B samples were sent for offline analysis by gas chromatography with a flame ionization detector and a capillary column (DB-FFAP 123-3232E). The conversion rate of propylene, the mass balance of carbon, and the analysis of acrylic acid, acrolein, acetaldehyde, propionaldehyde, propionic acid, acetic acid, and CO2 were performed. x The yields of major or by-products such as (CO and CO2) are calculated using the following formula: Isopropanol conversion rate (%) = (Number of moles of isopropanol supplied - Number of moles of isopropanol in R1 waste) / Number of moles of isopropanol supplied. Carbon mass balance (%) = (Total amount of carbon from molecules in R1 emissions including CO2, CO, propylene, acetaldehyde, acrolein, acetic acid, propionic acid, and acrylic acid) / (Total amount of carbon from supplied isopropanol) * 100

[0045] The yields of acrolein, acetaldehyde, and acrylic acid after the second-stage reactor, as well as the carbon mass balance, were calculated using the following formula: Product yield (%) = (moles of product in R2 effluent) / moles of isopropanol supplied * 100

[0046] The tests were conducted at different second-stage reactor temperatures while maintaining a constant temperature in the first-stage reactor, as shown in the reaction conditions in Table 3. Table 3 also includes the oxygen-to-isopropanol ratio (O2 / IPA). The results are listed in Table 4. The carbon mass balance was adjusted to 99% by controlling the isopropanol supply rate. Nearly complete conversion of isopropanol resulted in an acrylic acid yield exceeding 70%. The propionic acid yield was very low, approximately 0.07%, which resulted in a PA / AA mass ratio of approximately 0.0009.

[0047] [Table 3]

[0048] [Table 4] Fmd = Formaldehyde

[0049] IV. Comparative Example: Oxidation of 1-propanol to acrolein Similar to Example 1, 1-propanol (Sigma Aldrich, purity over 99.5%) was used instead of isopropanol. The catalyst used in the first-stage reactor was a Mo- and Bi-based mixed oxide catalyst, hereafter abbreviated as R1 catalyst. In this example, 10 mL of the Mo- and Bi-based R1 catalyst from Nippon Kayaku Co. (Tokyo, Japan) was packed into a 1-inch outer diameter (OD) stainless steel (SS) first-stage tubular reactor, which was heated in a clamshell electric furnace. The reactor was heated to the desired reactor temperature in a fluid gas mixture of 208.00 sccm of air and 38.2 sccm of N2, and then a liquid mixture containing 1-propanol and deionized water was injected at a rate of approximately 3.29 g / h for isopropanol and approximately 0.92 g / h for water.

[0050] The product mixture from the first-stage reactor (abbreviated as R1 effluent) was collected and analyzed. The R1 effluent first flowed through Trap 1, a 100–500 mL stainless steel container wrapped in a 1 / 4-inch (0.635 cm) copper coil connected to a recirculation chiller set to 0–1°C. The gas escaping from Trap 1 flowed through Trap 2, a second trap immersed in water / ice, and third and fourth traps (Traps 3A and 3B) immersed in a dry ice / isopropanol mixture. Trap 2 primarily functioned as a protective trap to prevent large amounts of water or acrylic acid from entering the dry ice / isopropanol trap, as water / acrylic acid could freeze and increase pressure within the dry ice / isopropanol trap. The trap collection time was typically 2–4 hours. To prevent polymer formation, 6–12 grams of inhibitor solution were injected into Trap 2, Traps 3A and 3B before sample collection. Trap 2 recovered only very small amounts of material in most cases. 0.2% by weight of hydroquinone in methanol was used as the inhibitor solution.

[0051] Off-gases from dry ice / isopropanol traps were analyzed online by gas chromatography with a thermal conductivity detector and a 5 Å molecular sieve / silica gel column. The main gaseous components of the off-gases typically included nitrogen, oxygen, unreacted propylene, carbon monoxide, and carbon dioxide. The liquids recovered from trap 1 and trap 2 (if present) were combined into a single sample and labeled as the T-1 sample. The liquids recovered from trap 3A and trap 3B were labeled as the T-3A and T-3B samples, respectively. The T-1, T-3A, and T-3B samples were sent for offline analysis by gas chromatography with a flame ionization detector and a capillary column (Restek MXT-1701). Alternatively, the R1 effluent was sent to an online analyzer in a heat-trace 1 / 8-inch SS tube for analysis of formaldehyde by-products.

[0052] The conversion rate of propylene, the carbon mass balance, and acrylic acid, acrolein, acetaldehyde, formaldehyde, propionic acid, acetic acid, CO2 x The yields of major or by-products such as (CO and CO2) are calculated using the following formula: 1-propanol conversion rate (%) = (Number of moles of 1-propanol supplied - Number of moles of 1-propanol in R1 waste) / Number of moles of 1-propanol supplied. Carbon balance (%) = (Total amount of carbon from molecules in R1 emissions including CO2, CO, propylene, formaldehyde, acetaldehyde, acrolein, acetic acid, propionic acid, and acrylic acid) / (Total amount of carbon from supplied 1-propanol) * 100.

[0053] The yields of acrolein, acetaldehyde, and acrylic acid after the second stage reactor, as well as the carbon balance, were calculated using the following formula. Product yield (%) = (moles of product in R1 effluent) / moles of isopropanol supplied * 100

[0054] The tests were conducted using two similar reactor setting temperatures (250°C and 245°C–249°C) and different operating times. The results are listed in Table 5. The yield of acrolein was less than 25%, which is significantly lower than when isopropanol is used as the feedstock. In addition, the yield of PA was much higher than the yield of AA, or the combined yield of "acrolein and AA".

[0055] [Table 5] Note: PT = Peak Temperature, MB = Mass Balance, Ald = Acetaldehyde, Fmd = Formaldehyde, PP = Propylene, HAc = Acetic Acid, PA = Propionic Acid, AA = Acrylic Acid.

[0056] V. Comparative example: Oxidation of 1-propanol to acrylic acid Similar to Example 2, 1-propanol was used instead of isopropanol as the feedstock to be oxidized to acrylic acid in two steps. First, 1-propanol was oxidized mainly to acrolein in the first-stage reactor, in this case a tubular reactor. The catalyst used in the first-stage reactor was a Mo and Bi mixed oxide catalyst, hereafter abbreviated as R1 catalyst. In this example, 10 mL of the Mo and Bi R1 catalyst from Nippon Kayaku Co. (Tokyo, Japan) was mixed with 10 mL of 1 / 8 inch (0.32 cm) Denstone™ 57 beads (Saint-Gobain Norpro, Stow, OH), and then placed into a first-stage tubular reactor made of stainless steel (SS) with an outer diameter (OD) of 2.54 cm (1 inch) (inner diameter (ID) of 0.834 inches (2.11 cm)).

[0057] The product mixture from the first-stage reactor (abbreviated as R1 effluent) was sent to the second-stage reactor, which was heated by an electric heating tape in a 1 / 4-inch (0.635 cm) SS tube. The surface temperature was controlled to approximately 170 ± 10°C.

[0058] The second-stage reactor contains a Mo-V mixed oxide catalyst (abbreviated as R2 catalyst). In this example, 10 mL of commercially available Mo-V R2 catalyst was packed into the feed inlet side of a U-shaped SS tube with an outer diameter (OD) of 1 / 2 inch (1.27 cm). The other end of the U-tube was packed with Denstone® beads. The U-tube was placed in a fluidized sand furnace, and the catalyst bed was immersed in the sand. Air was used to pump the catalyst at 3.3–3.5 SCFM (standard cubic feet / min) (0.093–0.099 m³). 3 The sand was fluidized at a flow rate of ( / min). By maintaining a high airflow rate, the temperature difference within the tank was controlled to less than 3°C. The tank temperature was adjusted to achieve the desired conversion from acrolein to acrylic acid. The effluent from the second stage reactor was referred to as R2 effluent.

[0059] First, the first-stage reactor was heated to over 250°C in a clamshell electric furnace with a fluidized gas mixture of 208.00 sccm of air and 38.2 sccm of N2. The second-stage reactor was heated to 300°C. All gas flow rates were measured under standard temperature (0°C) and standard pressure (101.3 kPa) conditions. 1-Propanol was mixed with deionized water (78.1 wt% isopropanol) and injected into the SS mixer vessel at a rate of 0.083 mL / min when the reactor reached the desired temperature. The SS mixer vessel was heated to 160-170°C, and steam was supplied to the reactor by supplying air / nitrogen.

[0060] R2 effluent was collected and analyzed. The R2 effluent first flowed through Trap 1, a 100–500 mL stainless steel container wrapped in a 1 / 4-inch (0.635 cm) copper coil connected to a recirculation chiller set to 0–1°C. The gas escaping from Trap 1 flowed through Trap 2, a second trap immersed in water / ice, and then through third and fourth traps (Traps 3A and 3B) immersed in a dry ice / isopropanol mixture. Trap 2 primarily functioned as a protective trap to prevent large amounts of water or acrylic acid from entering the dry ice / isopropanol trap, as water / acrylic acid could freeze and increase pressure within the dry ice / isopropanol trap. Trap collection times were typically 2–4 hours. To prevent polymer formation, 6–12 grams of inhibitor solution were injected into Traps 2, 3A, and 3B before sample collection. Trap 2 collected very little material in most cases. A 0.2% by weight hydroquinone solution in methanol was used as the inhibitor solution.

[0061] Off-gases from dry ice / isopropanol traps were analyzed online by gas chromatography with a thermal conductivity detector and a 5 Å molecular sieve / silica gel column. The main gaseous components of the off-gases typically included nitrogen, oxygen, unreacted propylene, carbon monoxide, and carbon dioxide. The liquids recovered from trap 1 and trap 2 (if present) were combined into a single sample and labeled as the T-1 sample. The liquids recovered from trap 3A and trap 3B were labeled as the T-3A and T-3B samples, respectively. The T-1, T-3A, and T-3B samples were sent for offline analysis by gas chromatography with a flame ionization detector and a capillary column (Restek MXT-1701).

[0062] Alternatively, the R2 emissions were sent to an online analyzer in a heat-trace 1 / 8-inch SS tube for analysis of formaldehyde by-products.

[0063] The conversion rate of propylene, the carbon mass balance, and acrylic acid, acrolein, formaldehyde, acetaldehyde, propionic acid, acetic acid, CO2 x The yields of major or by-products such as (CO and CO2) are calculated using the following formula: 1-propanol conversion rate (%) = (Number of moles of 1-propanol supplied - Number of moles of 1-propanol in R2 waste) / Number of moles of 1-propanol supplied. Carbon balance (%) = (Total amount of carbon from molecules in R2 emissions including CO2, CO, propylene, formaldehyde, acetaldehyde, acrolein, acetic acid, propionic acid, and acrylic acid) / (Total amount of carbon from supplied 1-propanol) * 100

[0064] The yields of acrolein, formaldehyde, acetaldehyde, and acrylic acid after the second stage reactor, as well as the carbon balance, were calculated using the following formula. Product yield (%) = (moles of product in R2 effluent) / moles of 1-propanol supplied * 100

[0065] The experiment was conducted with the second-stage reactor temperature set to 300°C and the first-stage reactor temperature slightly varied. The results are listed in Table 6. The carbon mass balance was adjusted to 99% by adjusting the yield of acetic acid, which can be affected by methanol added to the trap. With nearly complete conversion of 1-propanol, the yield of acrylic acid was only 20.4%, while the yield of PA was high at 4.71%. The PA / AA mass ratio was 0.225, which is considerably higher than 0.001, as shown in the product from isopropanol as the feedstock.

[0066] [Table 6] Note: PT = Peak temperature, IPA = Isopropanol, Fmd = Formaldehyde, Ald = Acetaldehyde, PP = Propylene, HAc = Acetic acid, PA = Propionic acid, AA = Acrylic acid. The invention described in the original claims of this application is listed below. [1] A method for producing acrolein, comprising selectively oxidizing isopropanol on a first mixed metal oxide catalyst in the presence of oxygen in the gas phase, A method wherein the first mixed metal oxide catalyst comprises molybdenum and bismuth oxides. [2] The method according to [1], wherein the mass ratio of propionic acid to acrolein is less than 0.002. [3] The method according to [1], further comprising selectively oxidizing the acrolein on a second mixed metal oxide catalyst in the presence of oxygen in the gas phase, wherein the second mixed metal oxide catalyst has a different composition from the first mixed metal oxide catalyst. [4] The method according to [3], wherein the second mixed metal oxide catalyst comprises molybdenum and vanadium oxides. [5] The method according to [4], wherein the second mixed metal oxide catalyst further comprises at least one additional element selected from the group consisting of tungsten, copper, iron, antimony, and phosphorus. [6] The method according to any one of [1] to [5], wherein the first mixed metal oxide catalyst further comprises at least one additional element selected from the group consisting of iron, cobalt, and nickel. [7] The method according to any one of [1] to [6], wherein the oxygen is in the form of purified oxygen, air, or lattice oxygen of the mixed metal oxide. [8] The method according to any one of [1] to [7], wherein the isopropanol is produced from a biomass-derived raw material. [9] The acrolein is at least 0.5 × 10 -13 of, 12 For C 14 A method according to any of [1] to [8], having a ratio of C.

[10] The method according to any one of [3] to [9], wherein the mass ratio of propionic acid to acrylic acid is less than 0.001.

[11] The method according to any one of [1] to

[10] , wherein the isopropanol is selectively oxidized in the presence of water vapor.

[12] The method according to any one of [3] to

[11] , wherein the acrolein is selectively oxidized in the presence of water vapor.

[13] The method according to [1] or [2], further comprising recovering acrolein by one or more techniques selected from absorption, extraction, fractional distillation and melt crystallization using water or an organic solvent.

[14] The method according to any one of [3] to

[12] , further comprising recovering acrylic acid by one or more techniques selected from absorption, extraction, fractional distillation and melt crystallization using water or an organic solvent.

Claims

1. To produce acrolein, isopropanol is selectively oxidized on a first mixed metal oxide catalyst in the presence of oxygen in the gas phase. In the presence of oxygen in the gas phase, the acrolein is selectively oxidized on a second mixed metal oxide catalyst. A method including, The first mixed metal oxide catalyst comprises molybdenum and bismuth oxides, The second mixed metal oxide catalyst has a different composition from the first mixed metal oxide catalyst. The second mixed metal oxide catalyst comprises molybdenum and vanadium oxides, The second mixed metal oxide catalyst further comprises at least one additional element selected from the group consisting of tungsten, copper, iron, antimony, and phosphorus. method.

2. The method according to claim 1, wherein the mass ratio of propionic acid to acrolein is less than 0.

002.

3. The method according to claim 1 or 2, wherein the first mixed metal oxide catalyst further comprises at least one additional element selected from the group consisting of iron, cobalt, and nickel.

4. The method according to any one of claims 1 to 3, wherein the oxygen exists in the form of purified oxygen, air, or lattice oxygen of the mixed metal oxide.

5. The method according to any one of claims 1 to 4, wherein the isopropanol is produced from a biomass-derived raw material.

6. The acrolein is at least 0.5 × 10 －１３ of, １２ For C １４ The method according to any one of claims 1 to 5, having a ratio of C.

7. The method according to any one of claims 1 to 6, wherein the mass ratio of propionic acid to acrylic acid is less than 0.

001.

8. The method according to any one of claims 1 to 7, wherein the selective oxidation of the isopropanol occurs in the presence of water vapor.

9. The method according to any one of claims 1 to 8, wherein the selective oxidation of the acrolein occurs in the presence of water vapor.

10. The method according to claim 1 or 2, further comprising recovering acrolein by one or more techniques selected from absorption, extraction, fractional distillation and melt crystallization using water or an organic solvent.

11. The method according to any one of claims 1 to 9, further comprising recovering acrylic acid by one or more techniques selected from absorption, extraction, fractional distillation and melt crystallization using water or an organic solvent.

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