Process for the production of propylene

Abstract

A method for producing propylene of one embodiment of the present application includes a reaction step in which fresh feedstock and recycled feedstock are supplied to a reactor to obtain a crude product, a gas-liquid separation step in which the crude product is separated into a gas phase and a liquid phase, a propylene recovery step in which propylene is recovered from the gas phase, and a recycling step in which the recycled feedstock is recovered from the liquid phase.

Description

Technical Field

[0001] This invention relates to a method for manufacturing propylene. Background Technology

[0002] Non-patent document 1 describes a method for producing propylene using ethanol as a raw material.

[0003] Existing technical documents

[0004] Non-patent literature

[0005] Non-patent literature 1: Iwamoto, M. et al., Pulse and IR study on the reaction pathways for the conversion of ethanol to propene over scandium-loaded indiumoxide catalysts, ACS Catal., 4(10), 3463-3469, 2014 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, as mentioned above, the existing technology suffers from the problem of low carbon-based yield of propylene.

[0008] One objective of this invention is to provide a method for manufacturing propylene that can improve the carbon-based yield of propylene.

[0009] means for solving problems

[0010] To address the aforementioned problem, one aspect of the present invention provides a method for producing propylene comprising the following steps: a reaction step, wherein a fresh feedstock comprising ethanol and acetone and a recycled feedstock comprising acetone are fed into a reactor and reacted to obtain a crude product; a gas-liquid separation step, wherein the crude product is separated into a gas phase comprising propylene and a liquid phase comprising acetone; a propylene recovery step, wherein propylene is recovered from the gas phase; and a recycling step, wherein the recycled feedstock is recovered from the liquid phase.

[0011] Invention Effects

[0012] According to one aspect of the present invention, the carbon-based yield of propylene can be increased. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating a method for manufacturing propylene according to one aspect of the present invention.

[0014] Figure 2 This is the process flow diagram used in the process simulation of Example 1. Detailed Implementation

[0015] The following is for reference Figure 1 A method for producing propylene according to one aspect of the present invention will be described in detail. Figure 1 This is a schematic diagram illustrating an example of the apparatus used in a method for producing propylene according to one aspect of the present invention. The method for producing propylene according to one aspect of the present invention includes the following steps: a reaction step, wherein a fresh feedstock comprising ethanol and acetone and a recycled feedstock comprising acetone are fed into a reactor and reacted to obtain a crude product; a gas-liquid separation step, wherein the crude product is separated into a gas phase comprising propylene and a liquid phase comprising acetone; a propylene recovery step, wherein propylene is recovered from the gas phase; and a recycling step, wherein the recycled feedstock is recovered from the liquid phase. The recycled feedstock recovered in the recycling step is fed into the reaction step.

[0016] (Reaction process)

[0017] The reaction process involves feeding fresh feedstock containing ethanol and acetone, and recycled feedstock containing acetone, into a reactor and reacting them to obtain a crude product. For example, the reaction process is described in... Figure 1 The process takes place in a reactor, where fresh and recycled feedstocks are supplied.

[0018] In this specification, "fresh feedstock" refers to feedstock newly supplied to the reactor from outside the reaction system. Fresh feedstock can be purchased feedstock or feedstock recovered from a reaction system different from this reaction system. Fresh feedstock can be biomass feedstock. Additionally, "recycled feedstock," as described later, refers to feedstock recovered from the liquid phase separated in the gas-liquid separation process and containing at least acetone. Furthermore, "feedstock" refers to a mixture of fresh feedstock and other components supplied to the reactor (including recycled feedstock). There are no particular limitations on ethanol; for example, ethanol from biomass, ethanol produced from carbon dioxide and hydrogen, and ethanol produced from waste gas containing hydrogen and carbon dioxide separated in the propylene recovery process described later can be used. These ethanols can be used alone or in combination of two or more.

[0019] Carbon oxides used as feedstock for ethanol can be, for example, carbon oxides produced by biomass decomposition, carbon oxides produced from fossil fuels, carbon oxides generated during the use of fossil resources as energy, carbon oxides generated during the manufacture of steel or chemical products, carbon oxides produced using plastics as feedstocks, and carbon dioxide recovered from the air. These carbon oxides can be used alone or in combination of two or more. Hydrogen used as feedstock for ethanol can be, for example, hydrogen from fossil fuels and / or hydrogen produced by the electrolysis of water. There are no particular restrictions on acetone; for example, acetone obtained through fermentation and / or acetone produced using aromatic peroxides as feedstocks can be used. It should be noted that, in addition to ethanol and acetone, fresh and recycled feedstocks may contain at least one component selected from the group consisting of oxygenated hydrocarbons such as isopropanol and acetaldehyde, and water. In the case where fresh feedstocks contain oxygenated hydrocarbons such as isopropanol and acetaldehyde, there are no particular restrictions; oxygenated hydrocarbons such as isopropanol and acetaldehyde obtained through fermentation or oxygenated hydrocarbons such as isopropanol and acetaldehyde from fossil fuels can be used.

[0020] In the reaction process, the molar ratio of acetone in the fresh feedstock supplied to the reactor to ethanol in the fresh feedstock is preferably 0.010 or more, more preferably 0.25 or more, and even more preferably 0.30 or more. Furthermore, this molar ratio is preferably 1.70 or less, more preferably 1.60 or less, and even more preferably 1.50 or less. By keeping this molar ratio within such a range, the carbon-based yield of propylene can be further improved. Here, the carbon-based yield of propylene is the ratio of the number of moles of carbon in the propylene recovered in the propylene recovery process to the total number of moles of carbon in the oxygen-containing hydrocarbons such as ethanol, acetone, isopropanol, and acetaldehyde in the fresh feedstock supplied to the reactor.

[0021] The molar ratio of the total acetone to the total ethanol contained in the fresh feed and recycled feed supplied to the reactor is preferably 0.010 or more, more preferably 0.25 or more, and even more preferably 0.30 or more. Furthermore, this molar ratio is preferably 1.7 or less, more preferably 1.60 or less, and even more preferably 1.50 or less.

[0022] The crude product obtained in the reaction process contains at least propylene and acetone, and may also contain ethanol and / or isopropanol. The crude product obtained in the reaction process may contain low-boiling-point components (such as acetaldehyde) with a boiling point lower than that of acetone.

[0023] From the viewpoint of increasing the carbon-based yield of propylene, the carbon-based propylene concentration in the crude product at the reactor outlet is preferably 5% or more, more preferably 10% or more, and even more preferably 15% or more. Here, the carbon-based propylene concentration is the ratio of the number of moles of carbon contained in the propylene at the reactor outlet to the total number of moles of carbon contained in the product gas at the reactor outlet, excluding the inactive components supplied from the crude product to the reactor.

[0024] From the viewpoint of increasing the carbon-based yield of propylene, the carbon-based acetone concentration in the crude product at the reactor outlet is preferably 1% or more, more preferably 5% or more, and even more preferably 10% or more. Here, the carbon-based acetone concentration is the ratio of the number of moles of carbon contained in the acetone at the reactor outlet to the total number of moles of carbon contained in the product gas at the reactor outlet, excluding the inactive components supplied to the reactor from the crude product.

[0025] In the reaction process, it is preferable to also supply water to the reactor. During the reaction process, when ethanol undergoes a dehydration reaction, ethylene is sometimes generated as a byproduct. However, by supplying water to the reactor, the generation of ethylene as a byproduct can be reduced. As a result, the carbon-based yield of propylene can be improved. The amount of water supplied to the reactor is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more, relative to 100 mol% of the total mass of ethanol and acetone.

[0026] In the reaction process, it is preferable to vaporize ethanol and acetone and then supply them to the reactor to contact the catalyst. The catalyst can be any catalyst used to produce propylene from ethanol and acetone. For example, a catalyst can be used that comprises 50% by mass and less than 100% by mass of zirconium oxide (A), and 0% by mass and less than or equal to 50% by mass of component (B) (wherein the total mass of components (A) and (B) is 100% by mass). Component (B) is at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, calcium, strontium, barium, scandium, yttrium, cerium, titanium, vanadium, chromium, copper, silver, gold, gallium, germanium, and tin.

[0027] The element as component (B) can be in its elemental form or in its oxide form. When the element is in oxide form, the mass of component (B) is the mass of the element contained in the oxide, excluding the mass of oxygen. Component (B) can be at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, calcium, strontium, barium, scandium, yttrium, titanium, vanadium, chromium, copper, silver, gold, gallium, germanium, and tin.

[0028] The feedstock and catalyst can come into contact in the reactor, or the feedstock can be fed into the reactor after contact with the catalyst. The feedstock can be a liquid or a gas. As an example of a method for contacting the feedstock with the catalyst, one can exemplify a method of heating the feedstock to vaporize it and then feeding the vaporized feedstock into a reactor pre-filled with catalyst.

[0029] A reactor is any reactor that allows the feedstock to come into contact with the catalyst. Examples of reactors include fixed-bed reactors, fluidized-bed reactors, and batch reactors. Furthermore, from the viewpoint of heat of reaction, a reactor can be an adiabatic reactor, an isothermal reactor, or a heat exchange reactor.

[0030] The reaction temperature is preferably 270℃~700℃, more preferably 300℃~650℃, and even more preferably 350℃~550℃.

[0031] The reaction pressure is preferably 10 kPa to 100,000 kPa, more preferably 100 kPa to 1,000 kPa.

[0032] From the viewpoint of stabilizing the gas composition supplied to the reaction process and stabilizing the operating conditions of the reactor, one embodiment of the propylene production method of the present invention preferably further includes a dehydration step of separating water from the crude product obtained in the reaction process. In the dehydration step, it is preferable to remove 10% or more of water relative to the molar number of acetone contained in the fresh raw material, more preferably 30% or more of water.

[0033] (Gas-liquid separation process)

[0034] The gas-liquid separation process is a process that separates the crude product obtained in the reaction process into a gas phase containing propylene and a liquid phase containing acetone. For example, in... Figure 1 The process takes place in a gas-liquid separator, where the crude product obtained in the reactor is fed to the gas-liquid separator.

[0035] In the gas-liquid separation process, any method capable of separating most of the propylene in the crude product into a gas phase and most of the acetone into a liquid phase is acceptable. Therefore, the gas phase may contain a small amount of acetone. In addition, the liquid phase may contain not only acetone, but also ethanol, and low-boiling-point components with boiling points lower than acetone (such as dissolved gas components like propylene and acetaldehyde).

[0036] There are no particular limitations on the method for separating the crude product into a gas phase containing propylene and a liquid phase containing acetone; for example, methods such as separation by pressure or cooling can be cited. In the case of separation by cooling, the cooling temperature can be set, for example, to a temperature at which more than 50% of acetone is present in the liquid phase and more than 50% of propylene is present in the gas phase, depending on the pressure within the system.

[0037] (Propylene recovery process)

[0038] The propylene recovery process is a process of recovering propylene (referred to as product propylene) from the gas phase separated in the gas-liquid separation process. In the propylene recovery process, propylene can be recovered by any one of the following (i) to (iii).

[0039] (i) The gas phase is recovered and used directly as the product propylene.

[0040] (ii) The condensed components containing propylene are recovered by pressurizing the gas phase as propylene product.

[0041] (iii) Distill the condensate obtained in (ii) to recover the product propylene.

[0042] (ii) For example in Figure 1 The process takes place in the booster, where the gas phase separated in the gas-liquid separator is supplied to the booster. (iii) For example, in Figure 1 The process is carried out in a propylene distillation column, where the condensate obtained in (ii) is fed to the propylene distillation column, and the condensate is distilled to separate the product propylene and waste oil. From the viewpoint of improving the purity of the recovered propylene, it is preferable to purify and recover propylene by at least one of (ii) and (iii), and more preferably by purifying and recovering propylene by method (iii).

[0043] There are no particular restrictions on the pressure in (ii), as long as it is the pressure required for propylene condensation. If the pressure is low, less electrical power is required for compression, and if the pressure is high, the amount of propylene condensation increases. Therefore, it is preferable to select an appropriate pressure for each device.

[0044] There are no particular restrictions on the distillation in (iii), and existing propylene distillation technologies such as naphtha cracking units, propane dehydrogenation and catalytic cracking processes can be used.

[0045] The condensate may contain oxygen-containing hydrocarbons such as acetaldehyde and acetone. In the propylene recovery process, it is preferable to further recover the condensate containing oxygen-containing hydrocarbons such as acetaldehyde and acetone. Preferably, the recovered liquid phase is supplied to at least one process selected from the group consisting of a reaction process, a gas-liquid separation process, and a recycling process. By recycling not only the oxygen-containing hydrocarbons such as acetaldehyde and acetone contained in the recycled feedstock, but also the oxygen-containing hydrocarbons such as acetaldehyde and acetone contained in the condensate, the carbon-based yield of propylene can be improved. Furthermore, in the propylene recovery process, the residue remaining after distillation of the condensate obtained in (ii), i.e., the liquid phase containing oxygen-containing hydrocarbons such as acetaldehyde and acetone, is further recovered. This liquid phase may be supplied to at least one process selected from the group consisting of a reaction process, a gas-liquid separation process, and a recycling process.

[0046] The carbon-based yield of propylene obtained in the propylene recovery process is preferably 30 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, and even more preferably 55 mol% or more. The higher the upper limit of the carbon-based yield of propylene obtained in the propylene recovery process, the better; for example, it can be 92 mol% or less, 85 mol% or less, 80 mol% or less, or 75 mol% or less.

[0047] Additionally, hydrogen (H2) and carbon dioxide (CO2) can be recovered separately from the gas phase, which is the residue remaining after pressurization in (ii). For example, a pressure swing adsorption (PSA) device can be used to separate the waste gas containing hydrogen (H2) and carbon dioxide (CO2) and recover the hydrogen as a product.

[0048] The recovered propylene can be used as a raw material for polypropylene, propylene oxide, aromatic hydrocarbons and aromatic alcohols, and their manufacturing methods are also included within the scope of this invention.

[0049] (Recycling process)

[0050] The recycling process is a process of recovering a recycled feedstock containing acetone from the liquid phase separated in the gas-liquid separation process. The recycled feedstock recovered in the recycling process is then fed into the reaction process. Examples of methods for recovering the recycled feedstock from the liquid phase include, for example, distilling the liquid phase and recovering the recycled feedstock. The recycled feedstock may also contain oxygenated hydrocarbons such as ethanol, acetaldehyde, and isopropanol, preferably ethanol and / or isopropanol. The recycling process, for example, is... Figure 1 The process takes place in a recirculating feedstock distillation column. The liquid phase separated in the gas-liquid separator is fed into the recirculating feedstock distillation column, and the recirculated feedstock recovered in the recirculating feedstock distillation column is fed into the reactor. Water is discharged from the recirculating feedstock distillation column. By recycling the acetone-containing feedstock to the reaction process in this way, the carbon-based yield of propylene can be improved.

[0051] There are no particular restrictions on the distillation conditions of the recirculating feed distillation column; distillation of the recirculating feed distillation column can be carried out under any conditions.

[0052] There are no particular restrictions on the method of supplying recycled feedstock to the reaction process. It can be supplied to the reactor after being premixed with fresh feedstock, or fresh feedstock and recycled feedstock can be supplied to the reactor separately.

[0053] Furthermore, one embodiment of the propylene manufacturing method of the present invention preferably further includes the step of recovering a low-boiling-point component with a boiling point lower than acetone from the liquid phase, and feeding the low-boiling-point component to at least one step selected from the group consisting of a reaction step, a gas-liquid separation step, and the recycling step. The low-boiling-point component includes, for example, acetaldehyde. By recycling not only the acetone-containing recycled feedstock but also the low-boiling-point component in this way, the carbon-based yield of propylene can be improved.

[0054] This invention is not limited to the embodiments described above. Various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

[0055] Example

[0056] [Simulation Example 1]

[0057] The simulation of the propylene manufacturing process including the following steps (1) to (4) was performed to calculate the theoretical yield.

[0058] (1) Reaction process

[0059] Liquid ethanol and liquid acetone (0.5 mol of liquid acetone relative to 1 mol of liquid ethanol) as fresh feedstock, and 0.7 mol of acetone relative to 1 mol of said liquid ethanol as recycled feedstock, are vaporized and fed into a reactor. The reactor is filled with a catalyst containing 1 part by mass of zirconium oxide (A) and 0.009 parts by mass of calcium (B). The ethanol and acetone supplied to the reactor are brought into contact with the catalyst.

[0060] (2) Gas-liquid separation process

[0061] The crude product recovered from the reactor outlet is cooled, and the high-boiling-point components are condensed, thereby separating them into a liquid phase containing acetone and a gaseous phase containing propylene.

[0062] (3) Propylene recovery process

[0063] Extract the gas phase separated in the gas-liquid separation process and recover propylene.

[0064] (4) Recycling process

[0065] A portion of the water is separated from the liquid phase in the gas-liquid separation process, and a recycled feed consisting of 0.7 moles of acetone relative to 1 mole of ethanol in the fresh feed is supplied to the reactor.

[0066] (Calculation of the theoretical value of yield)

[0067] Assume that the concentration of carbon-based propylene in the crude product at the reactor outlet under steady-state conditions is 35%.

[0068] Based on the assumed molar ratio of ethanol to acetone in the fresh feedstock, the molar ratio of acetone in the recycled feedstock to ethanol in the fresh feedstock, and the concentration of propylene in the crude product, as described above, the theoretical yield is calculated using the following formula (I).

[0069] Y = X / 100 × (Fe + Fa + Ra) / (Fe + Fa) × 100 Equation (I) Y: Yield of propylene

[0070] X: Concentration of carbon-based propylene in the crude product at the reactor outlet.

[0071] Fe: The number of moles of carbon in the ethanol contained in the fresh raw material.

[0072] Fa: The number of moles of carbon in acetone contained in the fresh raw material.

[0073] Ra: The number of moles of carbon in acetone, an oxygen-containing hydrocarbon, contained in the recycled feedstock.

[0074] Equation (I) represents the theoretical yield under the premise of no loss of fresh or recycled feedstock. That is, it calculates the yield when the total number of moles of carbon (Fe+Fa+Ra) supplied to the reactor is the same as the total number of moles of carbon at the reactor outlet.

[0075] The theoretical yield is calculated as shown in equation (II) below, and is assumed to be 56%.

[0076] 56=0.35×{1×2+(0.7+0.5)×3} / (1×2+0.5×3)×100 Equation (II)

[0077] [Simulation Comparison Example 1]

[0078] In step (1) of the above-described simulation example 1, but excluding steps (2) to (4), when 1.2 moles of liquid acetone are supplied as fresh feed relative to 1 mole of liquid ethanol for the liquid acetone in step (1), the carbon-based propylene concentration in the crude product at the reactor outlet is 35%. That is, the theoretical yield is assumed to be 35%.

[0079] [Preparation Example 1]

[0080] The particle size of zirconia (manufactured by Daiichi Rare Element Chemical Industry Co., Ltd., RC-100) was adjusted to 0.3 mm to 0.6 mm. In 5.00 g of the zirconia with adjusted particle size, a solution containing 0.0889 g of calcium acetate monohydrate and 1.11 g of ultrapure water (Millipore water) was added little by little while permeating, thereby obtaining a pore-filled body. The pore-filled body was held in air at 120 °C for 3 hours and then held in air at 500 °C for 2 hours, thereby obtaining Catalyst A.

[0081] [Example 1 (One-Pass Experiment)]

[0082] 1.25 g of Catalyst A was filled into a quartz reaction tube. A mixed gas with a molar ratio of ethanol / acetone / water / nitrogen of 8 / 4 / 74 / 14 was supplied to the reaction tube at a rate of 96 mL / min, and the reaction was carried out under the conditions of 0.2 MPa-G and 450 °C. The gas and liquid discharged from the gas outlet of the reaction tube 1.5 hours after the start of the reaction were collected and analyzed by gas chromatography to determine the product composition. The product composition is expressed as (moles of carbon in the product) / (moles of carbon in the raw material compounds supplied to the reaction) × 100 (%), with propylene being 26.1%, ethylene being 11.5%, CO2 being 9.3%, acetone being 29.0%, and IPA being 1.8%. As other components, when the component appearing as a peak other than the above compounds on gas chromatography is 1-pentene, the product composition of other components is 1.5%.

[0083] [Example 1 (Simulation)]

[0084] Based on the following settings, the material balance with recycle and the material balance without recycle were obtained through process simulation.

[0085] ■ As Figure 2 shown, the process flow was set to a process including a reaction process, a gas-liquid separation process, an acetone (ACT) recovery process, a compression process, a CO2 separation / water separation process, a C2 removal process, and a C3 removal process.

[0086] ■ The acetone recovery process (recycle raw material recovery process) includes the flash evaporation of the aqueous phase containing acetone.

[0087] ■ Regarding the material balance at the outlet of the reaction process, refer to the material balance calculated from the gas chromatography results of Example 1. Regarding the balance of carbon components, it is assumed that hexane is generated and the balance is met.

[0088] ■ Regarding the hydrogen balance and the oxygen balance, it is assumed that water and hydrogen are generated.

[0089] The simulation results are shown in Table 1. The results at reactor inlet G1 and reactor outlet G2 are consistent with the material balance of the feedstock and reactor outlet from the single-experiment results. The results at G3 after the C3 removal process and G4 after acetone recovery (after recycling feedstock recovery) are simulation results.

[0090] Simulation results show that, under steady-state conditions, the amount of acetone from the fresh feedstock can be reduced by recycling a portion of the recovered acetone-water solution after gas-liquid separation back to the reaction process. With acetone recycling, the propylene yield is 35.9%.

[0091] [Comparative Example 1]

[0092] Simulation results show that without recycling a portion of the recovered acetone-water solution after gas-liquid separation, the acetone yield from the fresh feedstock cannot be reduced. Without acetone recycling, the propylene yield is 25.7%.

[0093] Table 1

[0094]

[0095] Industrial practicality

[0096] This invention can be used in a method for manufacturing propylene.

Claims

1. A method for producing propylene, wherein, The method for manufacturing propylene includes the following steps: The reaction process involves feeding fresh feedstock containing ethanol and acetone and recycled feedstock containing acetone into a reactor and reacting them to obtain a crude product. A gas-liquid separation process in which the crude product is separated into a gas phase containing propylene and a liquid phase containing acetone; A propylene recovery process, wherein propylene is recovered from the gas phase; and The recycling process involves recovering the recycled feedstock from the liquid phase. In the reaction process, the molar ratio of the total acetone to the total ethanol contained in the fresh feed and recycled feed supplied to the reactor is 0.25 or more and 1.7 or less.

2. The method for producing propylene as described in claim 1, wherein, In the reaction process, the molar ratio of acetone to ethanol in the fresh feed supplied to the reactor is 0.010 to 1.

7.

3. The method for producing propylene as described in claim 1 or 2, wherein, The method for manufacturing propylene further includes the following steps: A low-boiling-point component with a boiling point lower than acetone is recovered from the liquid phase and supplied to at least one process selected from the group consisting of the reaction process, the gas-liquid separation process, and the recycling process.

4. The method for producing propylene as described in claim 1 or 2, wherein, The propylene recovery process includes the following steps: Further recover the condensed component containing acetone and supply the condensed component to at least one process selected from the group consisting of the reaction process, the gas-liquid separation process and the recycling process.

5. The method for producing propylene as described in claim 1 or 2, wherein, The recycled feedstock includes ethanol and / or isopropanol.

6. The method for producing propylene as described in claim 1 or 2, wherein, The method for producing propylene further includes: A dehydration process for separating water from the crude product obtained in the reaction process.

7. The method for producing propylene as described in claim 1 or 2, wherein, Water is also supplied to the reactor during the reaction process.

8. The method for producing propylene as described in claim 7, wherein, In the reaction process, the water supplied to the reactor is 10 mol% or more relative to the total amount of ethanol and acetone supplied to the reactor (100 mol%).

Images