Method for producing 2,5-dimethyl-2,4-hexadiene and method for producing p-xylene

Abstract

To provide a method for efficiently producing 2,5-dimethyl-2,4-hexadiene, which is useful for the production of p-xylene, using raw materials readily available from biomass. [Solution] A method for producing 2,5-dimethyl-2,4-hexadiene, comprising a condensation reaction step of reacting at least one first raw material selected from the group consisting of isobutene and tert-butyl alcohol with isobutyraldehyde in the presence of a catalyst, wherein the catalyst is a catalyst obtained by acid treatment of a catalyst precursor containing niobium oxide.

Description

[Technical Field]

[0001] The present invention relates to a method for producing 2,5-dimethyl-2,4-hexadiene and a method for producing p-xylene. [Background technology]

[0002] p-xylene is an industrially useful substance as a raw material for terephthalic acid, which is an intermediate raw material for polyester fibers and PET resin. As a method for producing p-xylene, for example, Patent Document 1 discloses a method for producing p-xylene from raw materials containing ethylene. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-79815 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, there has been a growing demand for a shift in chemical manufacturing methods from those using petroleum-derived raw materials to those using raw materials readily available from biomass.

[0005] The present invention aims to provide a method for producing 2,5-dimethyl-2,4-hexadiene, which is useful for the production of p-xylene, using readily available raw materials from biomass. Furthermore, the present invention aims to provide a method for producing p-xylene, which is readily available from biomass. [Means for solving the problem]

[0006] The present invention relates, for example, to the following [1] to [5]. [1] The method comprises a condensation reaction step in which at least one first starting material selected from the group consisting of isobutene and tert-butyl alcohol is reacted with isobutyraldehyde in the presence of a catalyst to obtain 2,5-dimethyl-2,4-hexadiene. A method for producing 2,5-dimethyl-2,4-hexadiene, wherein the catalyst is a catalyst obtained by acid treatment of a catalyst precursor containing niobium oxide. [2] The manufacturing method according to [1], wherein the catalyst is a calcined product of the catalyst precursor impregnated with an acidic solution. [3] An impregnation step in which the catalyst precursor is impregnated with an acidic solution, A calcination step to obtain the catalyst by calcining the catalyst precursor impregnated with the acidic solution, The manufacturing method according to [1] or [2], further comprising: [4] The method for producing the acidic solution according to [2] or [3], wherein the acidic solution comprises at least one inorganic acid selected from the group consisting of hydrochloric acid, phosphoric acid, and sulfuric acid. [5] The first step is to obtain 2,5-dimethyl-2,4-hexadiene by the manufacturing method described in any one of [1] to [4], A second step involves obtaining p-xylene by the cyclization dehydrogenation reaction of 2,5-dimethyl-2,4-hexadiene, A method for producing p-xylene, comprising the same components. [Effects of the Invention]

[0007] The present invention provides a method for producing 2,5-dimethyl-2,4-hexadiene, which is useful for the production of p-xylene, using readily available raw materials from biomass. Furthermore, the present invention provides a method for producing p-xylene, which is available using readily available raw materials from biomass. [Modes for carrying out the invention]

[0008] Preferred embodiments of the present invention will be described in detail below.

[0009] (Method for producing 2,5-dimethyl-2,4-hexadiene) The method for producing 2,5-dimethyl-2,4-hexadiene according to this embodiment comprises a condensation reaction step in which at least one first raw material selected from the group consisting of isobutene and tert-butyl alcohol is reacted with isobutyraldehyde in the presence of a catalyst to obtain 2,5-dimethyl-2,4-hexadiene.

[0010] In this embodiment, the catalyst used in the condensation reaction step is a catalyst obtained by acid treatment of a catalyst precursor containing niobium oxide.

[0011] According to the manufacturing method of this embodiment, 2,5-dimethyl-2,4-hexadiene, which is useful for the production of p-xylene, can be efficiently obtained from a first raw material readily available from biomass and isobutyraldehyde.

[0012] In the manufacturing method of this embodiment, it is believed that an unsaturated alcohol is produced by the condensation of isobutene and isobutyraldehyde, and that 2,5-dimethyl-2,4-hexadiene is formed by the dehydration reaction of the unsaturated alcohol. Furthermore, it is believed that tert-butyl alcohol is converted to isobutene by the dehydration reaction, and then converted to 2,5-dimethyl-2,4-hexadiene in the same manner as described above.

[0013] The condensation reaction step involves the reaction of a first raw material (at least one selected from the group consisting of isobutene and tert-butyl alcohol) with a second raw material (isobutyraldehyde) to obtain 2,5-dimethyl-2,4-hexadiene, and this reaction is carried out in the presence of the catalyst described above. The catalyst can also be described as a catalyst that promotes the reaction between the first and second raw materials.

[0014] The first raw material may be isobutene, tert-butyl alcohol, or a mixture of isobutene and tert-butyl alcohol.

[0015] The first raw material may be, for example, derived from biomass. For example, isobutene can be easily obtained by a dehydration reaction of isobutanol obtained by fermentation of glucose. In addition, tert-butyl alcohol can be easily obtained by a hydration reaction of isobutene.

[0016] The second raw material may be, for example, derived from biomass. For example, isobutyraldehyde can be easily obtained by a dehydrogenation reaction of isobutanol obtained by fermentation of glucose.

[0017] The catalyst may be a solid catalyst.

[0018] The condensation reaction step may be carried out, for example, by bringing a mixture of the first raw material and the second raw material into contact with the catalyst. In the condensation reaction step, the mixture in a liquid state (mixed liquid) may be brought into contact with the catalyst, or the mixture in a gaseous state (mixed gas) may be brought into contact with the catalyst. From the viewpoint of facilitating the reaction at the preferable reaction temperature described later, it is preferable to bring the mixed gas into contact with the catalyst. That is, the reaction in the condensation reaction step is preferably a gas-solid catalytic reaction.

[0019] The molar ratio of the second raw material to the first raw material (C2 / C1) may be, for example, 0.01 or more, and from the viewpoint of further suppressing side reactions, it may be 0.02 or more, 0.03 or more, or 0.05 or more. In addition, the molar ratio of the second raw material to the first raw material (C2 / C1) may be, for example, 10 or less, and from the viewpoint of further improving the yield of the target product, it may be 5 or less, 3 or less, or 1 or less.

[0020] The condensation reaction step may be carried out, for example, by allowing a mixture of the first raw material and the second raw material to flow through a flow reactor filled with the catalyst, or may be carried out in a batch mode.

[0021] The reaction conditions in the condensation reaction step are not particularly limited, and conditions that result in the formation of 2,5-dimethyl-2,4-hexadiene may be appropriately selected.

[0022] The reaction temperature in the condensation reaction step (for example, the temperature inside the reactor where the mixture and the catalyst are brought into contact) may be, for example, 100°C or higher, 120°C or higher, 150°C or higher, or 200°C or higher. Alternatively, the reaction temperature may be, for example, 400°C or lower, 350°C or lower, 320°C or lower, or 300°C or lower.

[0023] The reaction pressure in the condensation reaction step (for example, the pressure inside the reactor where the mixture and catalyst are brought into contact) may be, for example, atmospheric pressure, or it may be higher than atmospheric pressure. Furthermore, the reaction pressure may be, for example, 10 MPa-G or less, or it may be 5 MPa-G or less, 3 MPa-G or less, or 1 MPa-G or less.

[0024] In the condensation reaction step, the WHSV (the mass ratio of the mixture of the first and second raw materials to the catalyst packed in the reactor) is, for example, 0.1h. -1 The above is sufficient, 1h -1 More than 2 hours -1 or more, or 3 hours -1 The above is also acceptable. Furthermore, WHSV can be, for example, 50h -1 The following may be used, 30h -1 Below, 20 hours -1 The following or 10 hours -1 The following is also acceptable.

[0025] <Catalyst> The catalyst of this embodiment is obtained by acid-treating a catalyst precursor containing niobium oxide.

[0026] The catalyst precursor may be a solid containing niobium oxide (Nb2O5). The shape of the catalyst precursor is not particularly limited and may be, for example, powder, granules, or lumps.

[0027] The catalyst precursor may have niobium oxide as its main component (for example, 80% or more by mass, 90% or more by mass, 95% or more by mass, 97% or more by mass, or 99% or more by mass).

[0028] The catalyst precursor may further contain other components besides niobium oxide. Examples of other components include aluminum, silicon, and magnesium. The content of the other components may be, for example, 20% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, or 1% by mass or less.

[0029] The acid treatment of the catalyst precursor may be carried out by, for example, an impregnation step of impregnating the catalyst precursor with an acidic solution and a calcination step of calcining the catalyst precursor impregnated with the acidic solution. In other words, the catalyst of this embodiment may be, for example, a calcined product of a catalyst precursor impregnated with an acidic solution. Furthermore, the manufacturing method of this embodiment may further include, for example, an impregnation step and a calcination step.

[0030] In the impregnation step, the catalyst precursor may be either dropped with an acidic solution or immersed in an acidic solution.

[0031] The acidic solution preferably contains an inorganic acid. Examples of inorganic acids include hydrochloric acid, phosphoric acid, sulfuric acid, and nitric acid. From the viewpoint of further improving catalytic activity, the acidic solution preferably contains at least one inorganic acid selected from the group consisting of hydrochloric acid, phosphoric acid, and sulfuric acid, and more preferably contains hydrochloric acid.

[0032] The acidic solution is preferably an aqueous solution.

[0033] The concentration of the inorganic acid in the acidic solution may be, for example, 0.1 mol / L or higher, or 0.2 mol / L or higher, 0.3 mol / L or higher, or 0.5 mol / L or higher. Alternatively, the concentration of the inorganic acid in the acidic solution may be, for example, 15 mol / L or lower, or 10 mol / L or lower, or 5 mol / L or lower.

[0034] The catalyst precursor impregnated with an acidic solution in the impregnation process may be subjected to the calcination process as is, or it may be subjected to the calcination process after undergoing washing and drying processes.

[0035] The washing step may be a step of washing the catalyst precursor after the impregnation step with water. The washing method is not particularly limited and may be, for example, filtration washing.

[0036] The drying step may be a step of removing at least a portion of the moisture contained in the catalyst precursor after the impregnation step and the washing step. The drying method is not particularly limited and may be, for example, heat drying, vacuum drying, etc.

[0037] The drying temperature in the drying process may be, for example, 40°C or higher, or 50°C or higher. The drying temperature may also be, for example, 200°C or lower, or 150°C or lower, 120°C or lower, or 100°C or lower. The drying time in the drying process may be, for example, 12 hours or more, or 16 hours or more. The drying time may also be, for example, 100 hours or less, or 75 hours or less, 50 hours or less, or 25 hours or less.

[0038] In the firing process, the catalyst precursor, which has undergone the impregnation process (and, if applicable, the washing and drying processes), is fired.

[0039] The firing temperature in the firing process may be, for example, 200°C or higher, or 250°C or higher. The firing temperature may also be, for example, 600°C or lower, or 500°C or lower, 400°C or lower, or 350°C or lower. The firing time in the firing process may be, for example, 0.5 hours or more, or 1 hour or more, or 2 hours or more. The firing time may also be, for example, 10 hours or less, or 5 hours or less.

[0040] The catalyst in this embodiment may contain elements derived from the acid used in the acid treatment. For example, if hydrochloric acid is used for the acid treatment, the catalyst may contain chlorine atoms. If phosphoric acid is used for the acid treatment, the catalyst may contain phosphorus atoms. If sulfuric acid is used for the acid treatment, the catalyst may contain sulfur atoms.

[0041] When hydrochloric acid is used for acid treatment, the chlorine atom content in the catalyst may be, for example, 0.1% by mass or more, or 0.2% by mass or more. Alternatively, when hydrochloric acid is used for acid treatment, the chlorine atom content in the catalyst may be, for example, 3% by mass or less, 2% by mass or less, 1% by mass or less, or 0.5% by mass or less. By adjusting the acid treatment conditions so that the chlorine atom content falls within the above range, the above-mentioned effects are more pronounced.

[0042] When phosphoric acid is used for acid treatment, the phosphorus atom content in the catalyst may be, for example, 0.5% by mass or more, or 1% by mass or more, 2% by mass or more, or 3% by mass or more. Alternatively, when phosphoric acid is used for acid treatment, the phosphorus atom content in the catalyst may be, for example, 20% by mass or less, or 15% by mass or less, 10% by mass or less, or 7% by mass or less. By adjusting the acid treatment conditions so that the phosphorus atom content falls within the above range, the above-mentioned effects are more pronounced.

[0043] When sulfuric acid is used for acid treatment, the sulfur atom content in the catalyst may be, for example, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 2% by mass or more. Alternatively, when sulfuric acid is used for acid treatment, the sulfur atom content in the catalyst may be, for example, 15% by mass or less, 10% by mass or less, 7% by mass or less, or 5% by mass or less. By adjusting the acid treatment conditions so that the sulfur atom content falls within the above range, the above-mentioned effects can be more significantly achieved.

[0044] The chlorine (Cl), phosphorus (P), and sulfur (S) content in the catalyst is measured by ICP emission spectrometry.

[0045] In the condensation reaction step, a reaction product containing 2,5-dimethyl-2,4-hexadiene is obtained. The reaction product may further contain components other than 2,5-dimethyl-2,4-hexadiene. For example, the reaction product may further contain unreacted raw materials (e.g., isobutene, tert-butyl alcohol, isobutyraldehyde) and by-products (e.g., 2,5-dimethyl-1,4-hexadiene, 2,5-dimethyl-1,5-hexadiene, 2,5-dimethyl-2,5-hexadiene, etc.).

[0046] The reaction product obtained in the condensation reaction step may be used as is in the method for producing p-xylene described later, or it may be purified to increase the content of 2,5-dimethyl-2,4-hexadiene before being used in the method for producing p-xylene described later. The purification method is not particularly limited and may be a known method such as distillation purification or column purification.

[0047] According to the manufacturing method of this embodiment, 2,5-dimethyl-2,4-hexadiene, which is useful for the production of p-xylene, can be efficiently obtained from raw materials readily available from biomass.

[0048] (Method for producing p-xylene) The method for producing p-xylene according to this embodiment comprises a first step of obtaining 2,5-dimethyl-2,4-hexadiene by the above-described production method, and a second step of obtaining p-xylene by a cyclization dehydrogenation reaction of 2,5-dimethyl-2,4-hexadiene.

[0049] According to the method for producing p-xylene of this embodiment, p-xylene can be efficiently obtained from raw materials that are readily available from biomass.

[0050] The first step may be a step of carrying out the manufacturing method described above. The first step may also be a step of obtaining a reaction product containing 2,5-dimethyl-2,4-hexadiene, or a step of obtaining a purified product by purifying the reaction product.

[0051] In the second step, the cyclization dehydrogenation of 2,5-dimethyl-2,4-hexadiene may be carried out by known methods.

[0052] The second step may be, for example, a step of carrying out a cyclization dehydrogenation reaction of 2,5-dimethyl-2,4-hexadiene in the presence of a known catalyst for cyclization dehydrogenation. Examples of catalysts for cyclization dehydrogenation include Pt / silica, PtSn / silica, and PtSn / MgAl2O4. Note that Pt / silica refers to a catalyst in which Pt is supported on a silica support, PtSn / silica refers to a catalyst in which Pt and Sn are supported on a silica support, and PtSn / MgAl2O4 refers to a catalyst in which Pt and Sn are supported on an MgAl2O4 support.

[0053] The reaction conditions for the cyclization dehydrogenation reaction are not particularly limited and may be appropriately selected from known reaction conditions.

[0054] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Examples]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0056] (Example 1) (1) Preparation of catalyst 5 g of niobium oxide (catalyst JRC-NBO1, reference catalyst of the Catalysis Society of Japan) was added to 100 mL of 1 mol / L hydrochloric acid and stirred at room temperature for 2 hours. After that, the mixture was filtered and washed, and the resulting solid was dried at 60°C for 24 hours, followed by calcination at 300°C for 3 hours to obtain catalyst A. The chlorine atom content in catalyst A was 0.2% by mass. (2) Preparation of 2,5-dimethyl-2,4-hexadiene 3g of catalyst A was packed into a reaction tube with an inner diameter of 10mm. The reaction temperature was set to 250°C, and 2.3g / h of isobutanal and 143mL / min of isobutene (molar ratio of the second raw material to the first raw material (C2 / C1) was 0.089) were supplied to the reaction tube, and WHSV was reacted for 7.3h.-1 , a condensation reaction was carried out at normal pressure. One hour after the start of the reaction, the reaction product recovered from the outlet of the reaction tube was analyzed by gas chromatography, and the conversion rate (mass%) of isobutanal and the yield (mass%) of 2,5-dimethyl-2,4-hexadiene were determined. The results are shown in Table 1.

[0057] (Example 2) (1) Preparation of catalyst To 100 mL of 1 mol / L phosphoric acid, 5 g of niobium oxide (Catalyst Society of Japan reference catalyst JRC-NBO1) was added, and the mixture was stirred at room temperature for 2 hours. Thereafter, the mixture was filtered and washed, and the obtained solid was dried at 60°C for 24 hours, and then calcined at 300°C for 3 hours to obtain Catalyst B. The content of phosphorus atoms in Catalyst B was 5.0 mass%. (2) Production of 2,5-dimethyl-2,4-hexadiene A condensation reaction was carried out in the same manner as in Example 1, except that Catalyst B was used instead of Catalyst A. One hour after the start of the reaction, the reaction product recovered from the outlet of the reaction tube was analyzed by gas chromatography, and the conversion rate (mass%) of isobutanal and the yield (mass%) of 2,5-dimethyl-2,4-hexadiene were determined. The results are shown in Table 1.

[0058] (Example 3) (1) Preparation of catalyst To 100 mL of 1 mol / L sulfuric acid, 5 g of niobium oxide (Catalyst Society of Japan reference catalyst JRC-NBO1) was added, and the mixture was stirred at room temperature for 2 hours. Thereafter, the mixture was filtered and washed, and the obtained solid was dried at 60°C for 24 hours, and then calcined at 300°C for 3 hours to obtain Catalyst C. The content of sulfur atoms in Catalyst C was 3.1 mass%. (2) Production of 2,5-dimethyl-2,4-hexadiene A condensation reaction was carried out in the same manner as in Example 1, except that Catalyst C was used instead of Catalyst A. One hour after the start of the reaction, the reaction product recovered from the outlet of the reaction tube was analyzed by gas chromatography, and the conversion rate (mass%) of isobutanal and the yield (mass%) of 2,5-dimethyl-2,4-hexadiene were determined. The results are shown in Table 1.

[0059] (Comparative Example 1) The condensation reaction was carried out in the same manner as in Example 1, except that niobium oxide (catalyst JRC-NBO1, reference catalyst of the Catalysis Society of Japan) was used instead of catalyst A. The reaction product recovered from the outlet of the reaction tube 1 hour after the start of the reaction was analyzed by gas chromatography to determine the conversion rate (mass%) of isobutanal and the yield (mass%) of 2,5-dimethyl-2,4-hexadiene. The results are shown in Table 1.

[0060] [Table 1]

Claims

1. The process comprises a condensation reaction step in which at least one first starting material selected from the group consisting of isobutene and tert-butyl alcohol is reacted with isobutyraldehyde in the presence of a catalyst to obtain 2,5-dimethyl-2,4-hexadiene. A method for producing 2,5-dimethyl-2,4-hexadiene, wherein the catalyst is a catalyst obtained by acid treatment of a catalyst precursor containing niobium oxide.

2. The manufacturing method according to claim 1, wherein the catalyst is a calcined product of the catalyst precursor impregnated with an acidic solution.

3. An impregnation step in which the catalyst precursor is impregnated with an acidic solution, A calcination step to obtain the catalyst by calcining the catalyst precursor impregnated with the acidic solution, The manufacturing method according to claim 1, further comprising the above.

4. The production method according to claim 2 or 3, wherein the acidic solution comprises at least one inorganic acid selected from the group consisting of hydrochloric acid, phosphoric acid, and sulfuric acid.

5. A first step to obtain 2,5-dimethyl-2,4-hexadiene by the manufacturing method described in claim 1, A second step involves obtaining p-xylene by the cyclization dehydrogenation reaction of 2,5-dimethyl-2,4-hexadiene, A method for producing p-xylene, comprising the same components.

Images