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

Abstract

This method for producing 2,5-dimethyl-2,4-hexadiene comprises a condensation reaction step for reacting isobutyraldehyde and at least one type of first feedstock selected from the group consisting of isobutene and tert-butyl alcohol in the presence of a catalyst so as to obtain 2,5-dimethyl-2,4-hexadiene, wherein the catalyst is a catalyst obtained by acid-treating a catalyst precursor containing niobium oxide.

Description

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

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

[0002] p-Xylene is an industrially useful substance as a raw material for terephthalic acid, an intermediate raw material for polyester fibers and PET resins. For example, Patent Document 1 discloses a method for producing p-xylene from a raw material containing ethylene.

[0003] JP 2011-79815 A

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

[0005] An object of the present disclosure is to provide a method for producing 2,5-dimethyl-2,4-hexadiene, which is useful for producing p-xylene, and which can efficiently produce 2,5-dimethyl-2,4-hexadiene using raw materials that are readily available from biomass. Another object of the present disclosure is to provide a method for producing p-xylene, which can efficiently obtain p-xylene using raw materials that are readily available from biomass.

[0006] The present disclosure relates to, for example, the following [1] to [5]. [1] 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 to obtain 2,5-dimethyl-2,4-hexadiene, wherein the catalyst is obtained by acid-treating a catalyst precursor containing niobium oxide. [2] The production method according to [1], wherein the catalyst is a calcined product of the catalyst precursor impregnated with an acidic solution. [3] The production method according to [1] or [2], further comprising 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 to obtain the catalyst. [4] The production method according to [2] or [3], wherein the acidic solution contains at least one inorganic acid selected from the group consisting of hydrochloric acid, phosphoric acid, and sulfuric acid. [5] A method for producing p-xylene, comprising: a first step of obtaining 2,5-dimethyl-2,4-hexadiene by the production method according to any one of [1] to [4]; and a second step of obtaining p-xylene by cyclodehydrogenation of the 2,5-dimethyl-2,4-hexadiene.

[0007] According to the present disclosure, there is provided a method for producing 2,5-dimethyl-2,4-hexadiene, which is useful for producing p-xylene, and which can efficiently produce 2,5-dimethyl-2,4-hexadiene using raw materials that are readily available from biomass. Also, according to the present disclosure, there is provided a method for producing p-xylene, which can efficiently obtain p-xylene using raw materials that are readily available from biomass.

[0008] Preferred embodiments of the present disclosure 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 of the present embodiment includes 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-treating a catalyst precursor containing niobium oxide.

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

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

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

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

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

[0016] The second raw material may be derived from, for example, biomass. For example, isobutyraldehyde can be easily obtained by dehydrogenation 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 contacting a mixture of the first raw material and the second raw material with a catalyst. In the condensation reaction step, a liquid mixture (liquid mixture) may be contacted with the catalyst, or a gaseous mixture (gas mixture) may be contacted with the catalyst. From the viewpoint of easily carrying out the reaction at a suitable reaction temperature described below, it is preferable to contact the gas mixture 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 (C ２ / C １ ) may be, for example, 0.01 or more, and from the viewpoint of further suppressing side reactions, 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 (C ２ / C １ ) 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 flowing a mixture of the first and second raw materials through a flow reactor filled with a catalyst, or may be carried out batchwise.

[0021] The reaction conditions in the condensation reaction step are not particularly limited, and may be appropriately selected under conditions under which 2,5-dimethyl-2,4-hexadiene is formed.

[0022] The reaction temperature in the condensation reaction step (e.g., the temperature in a reactor in which the mixture is brought into contact with the catalyst) may be, for example, 100° C. or higher, 120° C. or higher, 150° C. or higher, or 200° C. or higher. 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 (e.g., the pressure in a reactor in which the mixture and the catalyst are brought into contact) may be, for example, atmospheric pressure or a pressure higher than atmospheric pressure. The reaction pressure may be, for example, 10 MPa-G or less, 5 MPa-G or less, 3 MPa-G or less, or 1 MPa-G or less.

[0024] The WHSV (mass ratio of the mixture of the first raw material and the second raw material to the catalyst charged in the reactor) in the condensation reaction step is, for example, 0.1 h －１ It may be 1 h or more. －１ That's 2 hours －１ or more or 3 hours －１ The WHSV may be, for example, 50h －１ may be less than 30 h －１ Below, 20 hours －１ Less than or equal to 10 hours －１ It may be the following:

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

[0026] The catalyst precursor is niobium oxide (Nb ２ O ５ The shape of the catalyst precursor is not particularly limited, and may be, for example, powder, granules, or lumps.

[0027] The catalyst precursor may be composed primarily of niobium oxide (for example, 80% by weight or more, 90% by weight or more, 95% by weight or more, 97% by weight or more, or 99% by weight or more).

[0028] The catalyst precursor may further contain components other than niobium oxide. Examples of the other components include aluminum, silicon, magnesium, etc. 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, for example, by 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. That is, the catalyst of this embodiment may be, for example, a calcined product of the catalyst precursor impregnated with the acidic solution. Furthermore, the production method of this embodiment may further include, for example, the impregnation step and the calcination step.

[0030] In the impregnation step, the acidic solution may be added dropwise to the catalyst precursor, or the catalyst precursor may be immersed in the 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 the 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 more, 0.2 mol / L or more, 0.3 mol / L or more, or 0.5 mol / L or more, or 15 mol / L or less, 10 mol / L or less, or 5 mol / L or less.

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

[0035] The washing step may be a step of washing the catalyst precursor with water after the impregnation step. 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 water contained in the catalyst precursor that has been subjected to the impregnation step and the washing step. The drying method is not particularly limited, and may be, for example, heat drying, drying under reduced pressure, or the like.

[0037] The drying temperature in the drying step may be, for example, 40°C or higher, or may be 50°C or higher. The drying temperature may 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 step may be, for example, 12 hours or higher, or 16 hours or higher. The drying temperature may be, for example, 100 hours or lower, or 75 hours or lower, 50 hours or lower, or 25 hours or lower.

[0038] In the calcination step, the catalyst precursor that has been subjected to the impregnation step (and optionally further to the washing step and drying step) is calcined.

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

[0040] The catalyst of this embodiment may contain elements derived from the acid used in the acid treatment. For example, when the acid treatment is performed using hydrochloric acid, the catalyst may contain chlorine atoms. When the acid treatment is performed using phosphoric acid, the catalyst may contain phosphorus atoms. When the acid treatment is performed using sulfuric acid, the catalyst may contain sulfur atoms.

[0041] When hydrochloric acid is used for the acid treatment, the content of chlorine atoms in the catalyst may be, for example, 0.1% by mass or more, or 0.2% by mass or more. Furthermore, when hydrochloric acid is used for the acid treatment, the content of chlorine atoms 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 conditions for the acid treatment so that the content of chlorine atoms falls within the above range, the above-mentioned effects are more pronounced.

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

[0043] When sulfuric acid is used for the acid treatment, the content of sulfur atoms 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. Furthermore, when sulfuric acid is used for the acid treatment, the content of sulfur atoms 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 conditions for the acid treatment so that the content of sulfur atoms falls within the above range, the above-mentioned effects are more pronounced.

[0044] The contents of chlorine atoms (Cl), phosphorus atoms (P) and sulfur atoms (S) in the catalyst are 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 may further contain 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 below-described method for producing p-xylene, or may be purified to increase the content of 2,5-dimethyl-2,4-hexadiene before being used in the below-described method for producing p-xylene. The purification method is not particularly limited, and may be a known method such as distillation purification or column purification.

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

[0048] (Method for Producing p-xylene) The method for producing p-xylene of this embodiment includes 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 cyclodehydrogenation 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 easily available from biomass.

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

[0051] In the second step, the cyclodehydrogenation reaction of 2,5-dimethyl-2,4-hexadiene may be carried out by a known method.

[0052] The second step may be, for example, a step of carrying out cyclodehydrogenation of 2,5-dimethyl-2,4-hexadiene in the presence of a known cyclodehydrogenation catalyst. Examples of the cyclodehydrogenation catalyst include Pt / silica, PtSn / silica, and PtSn / MgAl. ２ O ４ Pt / silica refers to a catalyst in which Pt is supported on a silica carrier, PtSn / silica refers to a catalyst in which Pt and Sn are supported on a silica carrier, and PtSn / MgAl ２ O ４ is MgAl ２ O ４ 1 shows a catalyst in which Pt and Sn are supported on a support.

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

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

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

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

[0057] Example 2 (1) Catalyst Preparation 5 g of niobium oxide (Catalyst JRC-NBO1, Catalysis Society Reference Catalyst) was added to 100 mL of 1 mol / L phosphoric acid and stirred at room temperature for 2 hours. The mixture was then filtered and washed, and the resulting solid was dried at 60°C for 24 hours and then calcined at 300°C for 3 hours to obtain Catalyst B. The phosphorus atom content 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. 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 of isobutanal (mass%) and the yield of 2,5-dimethyl-2,4-hexadiene (mass%). The results are shown in Table 1.

[0058] Example 3 (1) Catalyst Preparation 5 g of niobium oxide (Catalyst JRC-NBO1, Catalysis Society Reference Catalyst) was added to 100 mL of 1 mol / L sulfuric acid and stirred at room temperature for 2 hours. The mixture was then filtered and washed, and the resulting solid was dried at 60°C for 24 hours and then calcined at 300°C for 3 hours to obtain Catalyst C. The sulfur atom content in Catalyst C was 3.1% by 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. 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 of isobutanal (% by mass) and the yield of 2,5-dimethyl-2,4-hexadiene (% by mass). The results are shown in Table 1.

[0059] Comparative Example 1 A condensation reaction was carried out in the same manner as in Example 1, except that niobium oxide (Catalyst Society reference catalyst JRC-NBO1) was used instead of catalyst A. The reaction product recovered from the outlet of the reaction tube one 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]

Claims

1. 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 to obtain 2,5-dimethyl-2,4-hexadiene, wherein the catalyst is obtained by treating a catalyst precursor containing niobium oxide with an acid.

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

3. The method according to claim 1, further comprising: 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 to obtain the catalyst.

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

5. A method for producing p-xylene, comprising: a first step of obtaining 2,5-dimethyl-2,4-hexadiene by the production method according to claim 1; and a second step of obtaining p-xylene by a cyclodehydrogenation reaction of the 2,5-dimethyl-2,4-hexadiene.

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