JP5375054B2 - Method for producing furan compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for highly efficiently producing a furan compound by stably converting a furfural compound by suppressing the activity of a catalyst from lowering with time in the production of the furan compound from the furfural compound. <P>SOLUTION: The method for producing the furan compound includes the step of subjecting a furfural compound raw material to a decarbonylation reaction in the presence of a catalyst containing at least one element selected from Zr and Hf and at least one metallic element selected from among the elements of groups 8, 9, and 10. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a furan compound from a furfural compound.

  Furan is a useful intermediate chemical that can be used as a raw material for production such as tetrahydrofuran, pyrrole, and thiophene, and is produced by decarbonylation of furfural. Since furfural is usually produced from pentozan, which is a hemicellulose component contained in plants, not from petroleum-derived raw materials, the derived furan is also classified as a chemical product derived from plant raw materials, not from petroleum raw materials.

Although a method for producing furan from furfural has been known for a long time (such as Patent Document 1), as a method for efficiently obtaining a chemical product from plant-derived raw materials, a method for producing furan by a decarbonylation reaction using a catalyst in particular. Research and development has been conducted on (Patent Document 2, Non-Patent Document 1). There are two known methods for producing furan from furfural by decarbonylation reaction. One is a method using an oxide catalyst such as Zn—Cr—Mn and Zn—Cr—Fe composite oxide (eg, Patent Document 3), and the other is a method using a supported noble metal catalyst. Since the latter method shows activity even at a relatively low reaction temperature, a method for producing furan by a liquid phase reaction (Patent Document 4, Non-Patent Document 2) employing the latter method has been proposed. Further, in the latter method as in the former method, a method for producing furan by gas phase flow reaction (Patent Document 2, Non-Patent Document 1, Patent Document 5) has also been proposed.
US Patent No. 2,337,027 U.S. Pat. No. 4,780,552 U.S. Pat. No. 2,374,149 U.S. Pat. No. 3,257,417 U.S. Pat. No. 3,223,714 Tianranqi Huagon 2002, 27, 9 Biomass, 16 (1988), 89

  The problem with the method of producing furan in a single step by the decarbonylation reaction of furfural in the presence of a catalyst is that the activity of the catalyst greatly decreases with time when the reaction is carried out continuously. The reason why the activity of the catalyst decreases with time is not necessarily clear. If the catalytic activity decreases with time, the conversion rate of furfural decreases and the amount of furan produced per unit time decreases, thereby reducing the efficiency of the industrial process. In addition, problems such as separation / recovery and disposal of unreacted furfural or recycling use also occur.

  If the activity of the catalyst decreases greatly over time, in order to maintain furfural conversion and stably produce furan, it must be compensated by increasing the amount of catalyst for a while or raising the reaction temperature for a while. Must not. If the frequency of catalyst replacement and regeneration treatment increases, the operation of the industrial process becomes difficult. For these reasons, in order to produce furan stably and highly efficiently, a catalyst with less activity reduction has been demanded.

  Conventionally, many techniques relating to regeneration of a catalyst in which a decrease in activity is suppressed or a deactivated catalyst have been proposed. For example, in a liquid phase reaction, a reaction is conventionally performed by using a catalyst in which a metal such as Pd or Pt is supported on carbon, and in a gas phase flow reaction, a catalyst in which a metal such as Pd or Pt is supported on an alumina carrier is used. . However, the catalyst life is still not sufficient, and it is not always satisfactory in terms of economy for industrial implementation. In addition, when the activity of the catalyst is reduced, regeneration may be performed by firing treatment or the like. In the case of a support such as activated carbon and silica that has been proposed when the decarbonylation reaction of the furfural compound is performed in the liquid phase, the support burns under the regeneration treatment conditions when the regeneration is performed by the firing treatment, or the carrier metal is sintered. There is a problem that the pores of the carrier are blocked, and it is difficult to obtain the original activity.

  Therefore, an object of the present invention is to provide a method for producing a furan compound with high efficiency by stably converting the furfural compound in producing a furan compound from the furfural compound.

  As a result of intensive studies on a catalyst for producing a furan compound by decarbonylation reaction of a furfural compound, the present inventors have found that at least one element selected from Zr and Hf, and at least selected from 8, 9, and 10 groups. When the decarbonylation reaction of the furfural compound is carried out in the presence of a catalyst containing one kind of metal element, it was found that a furan compound can be obtained with high efficiency and stability over a long period of time, and the following inventions have been achieved.

In the present invention, a furfural compound raw material represented by the following general formula (1) is vaporized in advance to form a gaseous raw material, and the gaseous raw material is contacted with a catalyst containing Zr 2 and Pd or Pt for decarbonylation. It is a manufacturing method of a furan compound provided with the process made to react. Here, "the general formula (1) furfural compound materials represented by" the whole material as reference (100 mass%), the general formula (1) furfural compounds represented by, preferably at least 95 wt% More preferably, it means 98% by mass or more, particularly preferably 99% by mass or more. By using such a catalyst for the decarbonylation reaction of the furfural compound raw material, the catalytic activity is reduced little over time, and a high furfural conversion rate and a high furan selectivity are maintained over a long period of time. In addition, a furan compound can be produced with high efficiency. Moreover, since the amount of coke adhering to the catalyst is reduced, the catalyst can be used continuously for a long period of time, and the frequency of catalyst regeneration and replacement can be reduced.

In the present invention, the catalyst contains Pd or Pt , and particularly preferably contains Pd. By using a catalyst containing such a preferable form of metal element, the decarbonylation reaction can be carried out more efficiently.

As described above, in the present invention, the decarbonylation step is a step in which a gaseous raw material of a furfural compound vaporized in advance is brought into contact with the catalyst to perform the decarbonylation reaction (hereinafter referred to as “gas phase flow reaction”). is there.) it is. By contacting the vaporized furfural compound raw material with the catalyst, the decarbonylation reaction can be carried out more efficiently.

  In the present invention, the catalyst contains 0.01% by mass or more and 50% by mass or less of at least one element selected from Group 1, 2, 6, and 13 elements when the total mass of the catalyst is 100% by mass. It is preferable that By including such an element, the performance and stability of the catalyst can be improved.

  In the present invention, the decarbonylation reaction of the furfural compound raw material is carried out using a specific catalyst, so that the catalytic activity is little decreased over time, and a high furfural conversion rate and a high furan selectivity are maintained over a long period of time. Thus, it becomes possible to produce a furan compound stably and with high efficiency. In addition, since the amount of coke adhering to the catalyst decreases, the catalyst can be used continuously for a long period of time, reducing the frequency of catalyst regeneration and replacement, and reducing the frequency of active component sintering and finer in catalyst regeneration by calcination. It is possible to prevent deterioration of the catalyst due to hole blockage.

Details of the present invention will be described below.
The present invention is a method for producing a furan compound, comprising a step of decarbonylating a furfural compound raw material in the presence of a specific catalyst. Hereinafter, a furfural compound and a furan compound will be described first.

<Furfural compound>
It does not restrict | limit especially as a raw material furfural compound used with the manufacturing method of the furan compound of this invention, A well-known furfural compound can be used. The furfural compound refers to a compound represented by the following general formula (1).

In the general formula (1), R ¹ , R ² and R ³ may be the same or different, for example, hydrogen, an aliphatic hydrocarbon group which may have a functional group, or a functional group. Various functional groups such as an aromatic hydrocarbon group, a hydroxyl group, and an aldehyde group that may have a group may be mentioned, and specific examples include —H, —CH ₂ OH, —CH ₃ , —CHO, and the like. It is done. Specific examples of the furfural compound include hydroxymethylfurfural, 2-methylfurfural, 3-methylfurfural, furfuryl dialdehyde, and furfural. Of these, furfural is particularly preferable.

<Furan compound>
The furan compound obtained by the method for producing a furan compound of the present invention is not particularly limited, and is a known furan compound. The furan compound refers to a compound represented by the following general formulas (2) to (6).

R ⁴ , R ⁵ and R ⁶ may be the same or different, for example, hydrogen, an aliphatic hydrocarbon group which may have a functional group, or a functional group. Various functional groups, such as an aromatic hydrocarbon group and a hydroxyl group, are mentioned, and specifically, —H, —CH ₂ OH, —CH ₃ , —CHO and the like can be mentioned. Specific examples of the furan compound include 2-methylfuran, 3-methylfuran, furan, dihydrofuran, furfuryl alcohol, tetrahydrofuran, and tetrahydrofurfuryl alcohol, and furan is particularly preferable.

<Furfural compound raw material>
In the present invention, the furfural compound raw material is decarbonylated in the presence of a specific catalyst. Here, the furfural compound raw material contains 95% by mass or more, more preferably 98% by mass or more, particularly preferably 99% by mass or more of the furfural compound, based on the whole raw material (100% by mass). It means being.

  Although the manufacturing method of a raw material is not specifically limited, It can obtain by hydrothermal treatment of the plant-derived raw material or hydrolysis with an acid.

  In the present invention, the furfural compound raw material is decarbonylated in the presence of a catalyst containing at least one element selected from Zr and Hf and at least one metal element selected from Groups 8, 9, and 10. A compound is obtained. By using such a catalyst, in producing a furan compound from a furfural compound, a decrease in catalytic activity over time is suppressed, and a high furfural conversion rate and a high furan selectivity are maintained over a long period of time. In addition, a furan compound can be produced with high efficiency.

  The purity of the furfural compound is as described in the definition of the furfural compound raw material, but by removing impurities contained in the furfural compound raw material, the activity degradation of the catalyst of the present invention over time is further suppressed, A furan compound can be produced more stably and efficiently. Of the impurities contained in the furfural compound raw material, a high effect can be obtained by reducing sulfur or sulfur compounds, nitrogen compounds, and various acids. Particularly in a gas phase flow reaction, when a catalyst containing at least one element selected from Zr and Hf and at least one metal element selected from Groups 8, 9, and 10 is used, a furfural compound or Since furan compounds rarely coke on the catalyst, these impurities can accumulate directly on the catalyst or block the reaction site. A furan compound can be produced with high efficiency.

Although the form of sulfur or sulfur compound contained in the furfural compound raw material is not particularly limited, examples of the valence include a sulfur component of S ⁰ , S ²⁻ or S ⁶⁺ (SOx). More specifically, an amino acid such as cysteine, a protein containing the amino acid, a thiol group, a sulfhydryl group, a sulfide group, a compound having a disulfide group, an aromatic ring compound having S as a skeleton, sulfuric acid, sulfonic acid and salts thereof, Sulfurous acid and sulfite, or complex salts may be mentioned. The amount of sulfur or sulfur compound contained in the furfural compound raw material is usually 50 ppm or less, preferably 30 ppm or less, more preferably 20 ppm or less, more preferably 10 ppm or less, particularly preferably 6.0 ppm or less as the concentration of sulfur. . By subjecting the furfural compound raw material in which these sulfur-containing components are controlled to a sulfur concentration of 50 ppm or less to the decarbonylation reaction step, the decrease in the activity of the catalyst of the present invention over time is further reduced. The method for analyzing the amount of sulfur or sulfur compound contained in the furfural compound raw material is not particularly limited, and can be quantified as the elemental sulfur concentration by, for example, combustion-absorption-ion chromatography.

The form of the nitrogen compound contained in the furfural compound raw material is not particularly limited, but examples of the valence include nitrogen components of N ^3−, N ⁵⁺ , and N ³⁺ . More specifically, ammonia, amines and salts thereof, various amino acids, proteins, aromatic ring compounds having N as a skeleton, nitric acid and nitrate, nitrous acid and nitrite, or complex salts. The amount of the nitrogen compound contained in the furfural compound raw material is usually 50 ppm or less, preferably 30 ppm or less, more preferably 20 ppm or less, still more preferably 10 ppm or less, and particularly preferably 4.0 ppm or less as the concentration of nitrogen atoms. By subjecting the furfural raw material in which these nitrogen-containing components are controlled to a nitrogen concentration of 50 ppm or less to the decarbonylation reaction step, the decrease in activity over time of the catalyst of the present invention is further reduced. Although the analysis method of the quantity of the nitrogen compound contained in a furfural compound raw material is not specifically limited, For example, it can quantify as a nitrogen element density | concentration by a combustion decomposition-chemiluminescence method.

  The form of the acid component contained in the furfural compound raw material is not particularly limited, and examples thereof include inorganic acids such as sulfuric acid, sulfonic acid, and nitric acid, and organic acids having a sulfone group and a carboxyl group, such as furansulfonic acid and furancarboxylic acid. It is done. The amount of the acid component contained in the furfural compound raw material is usually 2 mgKOH / g or less, preferably 1 mgKOH / g or less, more preferably 0.50 mgKOH / g or less, further preferably 0.25 mgKOH / g or less, particularly preferably as an acid value. Is 0.10 mg KOH / g or less. By using the furfural compound raw material in which these acid components are controlled to 2 mgKOH / g or less in the decarbonylation reaction step, the decrease in the activity of the catalyst of the present invention over time is further reduced. Although the measuring method of an acid value is not specifically limited, The neutralization titration method can be used. Specifically, the acid value can be measured by diluting furfural with ethanol and titrating with 0.01 N potassium hydroxide aqueous solution.

  These furfural compounds are usually colorless and transparent. Accordingly, the color tone of the furfural compound raw material is usually 500 or less, preferably 300 or less, and more preferably 300 or less, more preferably 300 or less, when calculated based on the YI (Yellowness Index) value of the APHI (American Public Health Association) standard color solution. Is 100 or less, particularly preferably 50 or less. These color tones can be analyzed and calculated by transmission measurement using a color difference meter.

The method for removing impurities from the furfural compound raw material is not particularly limited, but it can be removed by distillation purification or impurity adsorption removal. The conditions for purifying about 400 g of furfural raw material by distillation under reduced pressure are exemplified. Using a Vigreux tube with an inner diameter of 18 mm and a height of 245 mm as a rectification column, after charging the furfural raw material into a 1 L flask, replacing the system with nitrogen, heating the furfural raw material in the flask with an oil bath, and then reducing the pressure inside the system. Distill. The temperature of the furfural raw material is 75 ° C, the steam temperature is 55 ° C, the pressure in the system is 1.2 x 10 ³ Pa, about 13% by mass of the total amount is removed as the first fraction, and about 25% by mass of the total amount is removed as the residue. Thus, about 250 g of purified furfural can be obtained.

It is also possible to separate and remove impurities by adsorption. The adsorbent in that case is not particularly limited, but is a porous material such as activated carbon, ion exchange resin, ion exchange zeolite or silica, or a metal, a noble metal, or a carrier such as silica, alumina, zeolite or activated carbon. Those supported on are preferably used. A plurality of adsorbents may be used simultaneously. As a method of adsorption removal, an adsorbent may be put into the raw material and separated by filtration after a certain treatment time, or the adsorbent may be packed in a column in advance and the raw material may be circulated. Moreover, it is also mentioned as a preferable method that a raw material and an adsorbent are charged during distillation purification and a raw material purified by distillation is obtained while removing impurities by adsorption. As the adsorbent at that time, in addition to the substances listed above, alkali hydroxides such as NaOH effective for removing acid components, alkali carbonates such as Na ₂ CO _{3 and the} like are also preferably used. Furthermore, after removing impurities using an adsorbent, further purification by distillation is preferably performed to remove impurities that could not be removed by adsorption or impurities derived from the adsorbent. Further, adsorption removal may be performed after distillation purification.

  The conditions for storing the furfural compound raw material in which impurities are reduced by purification or the like are not particularly limited, but it is preferable to store in an atmosphere shielded from oxygen and light. The concentration of oxygen in the storage atmosphere is usually 20% or less, preferably 10% or less, more preferably 5% or less, and particularly preferably 1% or less.

<Decarbonylation catalyst>
In the present invention, the decarbonylation reaction of the furfural compound raw material is carried out in the presence of a catalyst containing at least one element selected from Zr and Hf and at least one metal element selected from Groups 8, 9, and 10. The furan compound is obtained.

  At least one element selected from Zr and Hf is preferably added to or supported on a carrier supporting at least one metal element selected from Group 8, 9, and 10 or a part or all of the carrier component Configure. Preferably, a substance containing at least one element selected from Zr and Hf is used as a carrier supporting at least one metal element selected from Groups 8, 9, and 10.

The form of at least one element selected from Zr and Hf is not particularly limited, and examples thereof include phosphate, sulfate, hydroxide, hydrated oxide, oxide, and composite oxide. Examples of phosphates and sulfates include Zr ₃ (PO ₄ ) ₄ , ZrP ₂ O ₇ , Zr (SO ₄ ) ₂ .4H ₂ O, and the like. Examples of the hydroxide, hydrated oxide, and oxide include ZrO (OH) ₂ , ZrO ₂ , and HfO ₂ . _{Other, ZrSiO 4, ZrO 2 -SiO 2} , ZrO 2 -TiO 2, ZrO 2 -Al composite oxide such as 2 _{O 3.} Of these, a complex oxide such as ZrSiO _4, a complex oxide such as ZrO ₂ —SiO ₂ , ZrO ₂ —TiO ₂ , ZrO ₂ —Al ₂ O ₃ and a single oxide such as ZrO ₂ and HfO ₂ are preferable. More preferable examples include single oxides such as ZrO ₂ and HfO ₂ , and particularly preferable examples include ZrO ₂ . There are no particular restrictions on the crystal form of ZrO ₂ , but usually monoclinic, metastable tetragonal, tetragonal
A monoclinic system, a metastable tetragonal system or a tetragonal system, more preferably a monoclinic system or a metastable tetragonal system, and particularly preferably a monoclinic system or a metastable tetragonal system. It is an oblique system.

As for the surface acid basicity of the support containing at least one element selected from Zr and Hf, the maximum acid strength is usually −3 or more, preferably 1.5 or more, if expressed by the Hammett function H _0. preferably 3.3 or more and still more preferably 4.0 or more, and particularly preferably 6.8 or more, the strongest point _H 0, max is usually 0 to 15, preferably 5 to 10.

  A catalyst containing at least one element selected from Zr and Hf and at least one metal element selected from Groups 8, 9, and 10 is more effective in a gas phase flow reaction than in a liquid phase reaction. To do. Since the catalyst containing at least one element selected from Zr and Hf is weak but has surface acid basicity, in a liquid phase reaction in which a high concentration of furfural compound is present, it reacts with a carbonyl group, Tishchenko reaction, By causing a Cannizzzaro reaction, by-products such as ester dimers are formed. In addition, sludge-like polymers, etc. that are generated by heating a high-concentration furfural compound for a long time, regardless of the catalytic reaction, physically adhere to the catalyst, thereby dispersing the catalyst and performing the desired decarbonylation reaction. In comparison with a catalyst made of a non-polar carrier such as carbon, the degree is much higher in a catalyst made of a polar carrier such as a catalyst containing at least one element selected from Zr and Hf. .

  Therefore, making the surface acid-base characteristics of the catalyst containing at least one element selected from Zr and Hf as described above produces a furan compound stably and efficiently over a long period of time, particularly in a gas-phase flow reaction. From the viewpoint of

Examples of the carrier supporting at least one metal element selected from Group 8, 9, and 10 include phosphates, sulfates, hydroxides, and hydrous hydroxides containing at least one element selected from Zr and Hf. things, oxides, other composite _{oxide, SiO 2, TiO 2, Al} 2 O 3, MgO, SiO 2 -Al 2 O 3, MgO-Al 2 O 3 or the like alone oxide or composite oxide, zeolite Porous oxides, oxides having mesopores, and activated carbon. When these carriers do not contain at least one element selected from Zr and Hf, these carriers and a compound containing Zr and Hf elements are physically mixed, or at least selected from Zr and Hf are added to these carriers. After adding or supporting one element, it can be used as a carrier for supporting at least one metal element selected from Groups 8, 9, and 10.

The surface area of the carrier is not particularly limited, but is usually 1 m ² / g or more and 1000 m ² / g or less, preferably 10 m ² / g or more and 500 m ² / g or less, more preferably 20 m ² / g or more and 200 m ² / g or less. . The pore volume of the carrier is not particularly limited, but is usually 0.1 ml / g or more and 5 ml / g or less, preferably 0.2 ml / g or more and 3 ml / g or less. When the surface area and pore volume of the support are small, the furfural compound is not sufficiently converted and it is not efficient because it is necessary to recover the unreacted furfural compound. If the surface area or pore volume of the support is too large, at least one element selected from Zr and Hf is not preferable because the effect of suppressing a decrease in the activity of the catalyst over time is reduced.

  As a method for adding or supporting at least one element selected from Zr and Hf to the carrier, when supporting at least one metal element selected from Group 8, 9, and 10 is simultaneously selected from Zr and Hf. A method of adding a solution in which at least one elemental compound is dissolved is preferably used. Further, after supporting at least one metal element selected from Groups 8, 9, and 10 on a carrier, a solution in which a compound of at least one element selected from Zr and Hf is dissolved may be added. Further, at least one metal element selected from Group 8, 9, 10 or a substance on which they are supported is added to or supports a substance containing at least one element selected from Zr, Hf, or physical mixing The target catalyst may be obtained by mixing by such means as above.

  Examples of the compound used when adding at least one element selected from Zr and Hf include metal alkoxides, oxynitrates and oxysulfates, and preferably oxynitrates. After at least one element selected from Zr and Hf is added, moisture and liquid components may be removed, dried, and fired in a gas containing oxygen.

  The reason why the catalyst containing at least one element selected from Zr and Hf is preferable is that these components are inactive with respect to the furfural compound and the furan compound, and at least one selected from Group 8, 9, and 10 This is because a side reaction hardly occurs in the conversion of the furfural compound into the furan compound by the metal element. The selectivity of the furan compound of the catalyst containing at least one element selected from Zr and Hf is usually 90% or more, and the yield of the furan compound can be obtained to the maximum.

  Further, since the surface of the substance containing at least one element selected from Zr and Hf has an appropriate acid-base property or an acid-base dual function, excessive adsorption of a furfural compound or a furan compound, Reaction is avoided. Further, for the same reason, an undesirable reaction such as polymerization of these compounds can be avoided, so that a situation where coke accumulates on the catalyst surface due to polymerization or the like can be prevented. As a result, a catalytically active site effective for the decarbonylation reaction of the furfural compound continues to act for a long time. Taking the continuous reaction in the gas-phase flow for 10 hours as an example, the conversion rate of the furfural compound is maintained at 90% or more of the initial value, so that the furan compound can be produced efficiently and stably.

  The amount of at least one element selected from Zr and Hf in the catalyst is usually from 0.001 to 90% by mass, preferably from 1 to 85% by mass, based on the mass of the entire catalyst (100% by mass). % Or less, more preferably 5% by mass or more and 85% by mass or less, and particularly preferably 10% by mass or more and 75% by mass or less.

  If the amount of at least one element selected from Zr and Hf is too small, the effect of suppressing a decrease in the activity of the catalyst over time is reduced, which is not preferable. On the other hand, if the amount of at least one element selected from Zr and Hf is too large, the furfural compound is not sufficiently converted, and recovery of unreacted furfural compound is required, which is not efficient.

  The at least one metal element selected from Groups 8, 9, and 10 is not particularly limited, but preferably includes Ni, Ru, Ir, Pd, and Pt, and more preferably includes Ru, Ir, Pd, and Pt. More preferred are Pd and Pt, and particularly preferred is Pd. By using at least one metal element selected from these groups 8, 9, and 10 as a catalyst component, it becomes possible to convert a furfural compound into a furan compound with high selectivity, and efficiently produce a furan compound. be able to. These metal elements are usually used as a supported metal catalyst by being supported on the carrier as described above.

  The content of at least one metal element selected from Groups 8, 9, and 10 depends on the type of metal and carrier and cannot be generally specified, but is usually 0 based on the mass of the entire catalyst (100% by mass). .01 mass% to 100 mass%, preferably 0.05 mass% to 50 mass%, more preferably 0.1 mass% to 20 mass%, particularly preferably 0.5 mass% to 5 mass%. It is. If the content of at least one metal element selected from Groups 8, 9, and 10 is low, the furfural compound raw material will not be converted sufficiently, and it will be necessary to recover unreacted furfural compound. In addition, the efficiency is reduced in recovering the metal from the used catalyst. On the other hand, if the content of at least one metal element selected from Group 8, 9, or 10 is too large, the effect of suppressing the time-dependent decrease in activity of the catalyst is small with at least one element selected from Zr and Hf. Therefore, it is not preferable.

  The catalyst carrying at least one metal element selected from these groups 8, 9, and 10 can contain a component (hereinafter referred to as a modification aid) for improving the performance and stability of the catalyst. Examples of the modification aid include Group 1 metals and their ions, Group 2 metals and their ions, Group 6 metals and their ions, Group 13 metals and their ions. Preferred are Group 1 metals and their ions, Group 2 metals and their ions, Group 6 metals and their ions, and particularly preferred are Group 1 metals and their ions. Specifically, metals and ions of Cs, Rb, K, Na, and Li, particularly preferably metals and ions of K and Na. These metals and ions may be used in combination. Depending on the type of at least one metal element selected from Groups 8, 9, and 10, the catalyst life can be further improved by adding these modification aids to the catalyst, and the furan compound can be produced more efficiently. Is possible.

  At least one metal element selected from Group 8, 9, and 10 that can provide a great effect when using these modification aids is Ni, Ru, Ir, Pd, Pt, more preferably Pd, Pt, and particularly preferably Pd.

  The form of the catalyst for these modification aids is not particularly limited, and examples thereof include metal metals, carboxylates, carbonates, phosphates, nitrates, sulfates, hydroxides, oxides, and complex oxides. Includes carbonates, nitrates, hydroxides, oxides, and complex oxides. These modification aids can be added in advance to the above-mentioned carrier, or can be added after at least one metal element selected from Groups 8, 9, and 10 is supported on the carrier. Further, it may be compounded or alloyed with at least one metal element selected from groups 8, 9, and 10. Preferably, when supporting at least one metal element selected from Group 8, 9, and 10 on the above carrier, these modification aids are simultaneously added to form a composite.

Specific examples of modification assistants added simultaneously when supporting at least one metal element selected from Group 8, 9, and 10 are Cs (CH ₃ COO), Rb (CH ₃ COO), K ( _{CH 3 COO), Na (CH} 3 COO), Li (CH 3 COO), CsNO 3, RbNO 3, KNO 3, NaNO 3, LiNO 3, Cs 2 CO 3, Rb 2 CO 3, K 2 CO 3, Na ₂ CO ₃ , Li ₂ CO ₃ , CsOH, RbOH, KOH, NaOH, LiOH, more preferably CsNO ₃ , KNO ₃ , NaNO ₃ , LiNO ₃ , Cs ₂ CO ₃ , K ₂ CO ₃ , Na ₂ CO ₃ , Li ₂ CO ₃ , CsOH, KOH, NaOH, LiOH, more preferably KNO ₃ , NaNO ₃ , K ₂ CO ₃ , Na ₂ CO ₃ , KOH, N aOH.

  Although the content of these modification aids depends on the type of metal and carrier, it cannot be said unconditionally, but based on the total mass of the catalyst (100% by mass), usually 0.01% by mass to 50% by mass, Preferably they are 0.05 mass% or more and 20 mass% or less, More preferably, they are 0.1 mass% or more and 10 mass% or less, Most preferably, they are 0.5 mass% or more and 5 mass% or less.

  If the content of the modification aid is too small, the effect of suppressing the decrease in the activity of the catalyst over time is reduced, which is not preferable. Moreover, when there is too much quantity of a modification adjuvant, a furfural compound will not fully convert, but collection | recovery etc. of an unreacted furfural compound will be needed, and it is not efficient.

  A method for supporting at least one metal element selected from Group 8, 9, and 10 on the carrier is not particularly limited, and examples include an ion exchange method, an impregnation supporting method, a pore filling method, an incipient-wetness method, and a spray supporting method. It is done. The carrier may be fired in advance in a gas atmosphere containing oxygen. The firing temperature is usually 200 ° C. or higher and 1200 ° C. or lower, preferably 300 ° C. or higher and 1000 ° C. or lower, more preferably 400 ° C. or higher and 800 ° C. or lower, and particularly preferably 500 ° C. or higher and 700 ° C. or lower.

  In carrying at least one metal element selected from Group 8, 9, 10 on the carrier by ion exchange or impregnation, etc., the metal raw material used is usually at least one selected from Group 8, 9, 10 Water-soluble salts such as chlorides and nitrates of these metal elements, or acidic solutions thereof are used. Water-soluble raw materials that do not contain halogen elements such as nitrates, ammine complex nitrates, and ammine nitro compounds are preferred.

  After supporting at least one metal component selected from Group 8, 9, and 10 on the carrier by an ion exchange method or an impregnation supporting method, moisture and liquid components are removed by filtration, centrifugal drainage, and drying. Thereafter, firing in air or the like is also suitably performed. The firing temperature is usually 200 ° C. or higher and 1000 ° C. or lower, preferably 250 ° C. or higher and 800 ° C. or lower, more preferably 300 ° C. or higher and 600 ° C. or lower. It is also preferable to perform firing while charging a tube and circulating a gas containing oxygen.

  Furthermore, by reacting the catalyst with a reducing agent in the liquid phase, or by charging a tube and circulating a gas containing hydrogen or alcohol and treating it under a reducing gas stream, at least selected from the group 8, 9, 10 One metal component can be reduced to activate the catalyst. Examples of the reducing agent used for the reduction in the liquid phase include formalin, hydrazine, hydroxylamine, hydroxyacetone, ethanol, formic acid, oxalic acid, and hydrogen, and preferably formalin and hydrazine. Examples of the reducing gas include hydrogen, ammonia, carbon monoxide, and nitric oxide, and preferably hydrogen. The temperature during the treatment with the reducing gas is usually 100 ° C. or higher and 900 ° C. or lower, preferably 150 ° C. or higher and 570 ° C. or lower, particularly preferably 200 ° C. or higher and 500 ° C. or lower. These reduction treatments may be performed immediately before being subjected to the decarbonylation reaction of the furfural compound. Moreover, you may carry out by the same reactor as the reactor which performs the decarbonylation reaction of a furfural compound.

<Decarbonylation reaction>
The reaction form of the decarbonylation reaction in the present invention is not particularly limited, and either batch reaction or continuous flow reaction can be carried out, but it is preferable to use the continuous flow reaction form industrially. The decarbonylation reaction can be carried out in either a liquid phase reaction or a gas phase flow reaction. In the gas phase flow reaction, the reaction is carried out by bringing a gas furfural compound raw material into contact with a solid catalyst or the like. preferable. The reason for this is that the concentration of the furfural compound per unit volume is reduced, so that side reactions that adversely affect the condensation and polymerization of the furfural compound and the yield of the furan compound are suppressed. Further, the gas phase flow reaction has an advantage that the catalyst can be easily replaced and regenerated by devising the reactor. For example, by making the reactor a fixed bed type, it is possible to regenerate by calcination without removing the catalyst from the reactor, and by providing multiple fixed bed reactors in parallel, one reactor Since the decarbonylation reaction of the furfural compound can be carried out in another reactor while the catalyst is regenerated or exchanged, the furan compound can be produced continuously.

  In the case of a gas-phase flow reaction, usually a gas containing a furfural compound raw material is continuously supplied to a fixed bed tube reactor loaded with a catalyst, and the reaction proceeds to the catalyst in the reactor to obtain a furan compound. It is done. The furfural compound raw material is preferably used as a gas in a vaporizer provided in advance. The vaporization method is not particularly limited, and examples thereof include a method of gas bubbling hydrogen, an inert gas or the like to the liquid furfural compound raw material, a method by spray vaporization, and the like. When an inert gas or the like is used as gas bubbling or accompanying gas as required, the purity of the accompanying gas such as inert gas used is usually 95 vol% or more, preferably 99 vol% or more, more preferably 99.9 vol% or more, Especially preferably, it is 99.99 vol% or more.

  In the decarbonylation reaction of a furfural compound using the catalyst containing at least one element selected from Zr and Hf and at least one metal element selected from Groups 8, 9, and 10 of the present invention, a reaction initiator It is preferably used to coexist hydrogen. The amount of hydrogen to be entrained is not particularly limited, but is usually 0.01 or more and 4 or less, preferably 0.02 or more and 2 or less, more preferably 0.04 or more and 1 or less, particularly preferably 0, in the molar ratio with the furfural compound. 0.06 or more and 0.5 or less. When the amount of hydrogen is small, the furfural compound raw material is not sufficiently converted, and it is not efficient because it is necessary to recover unreacted furfural compound. When the amount of hydrogen is too large, the product of hydrocracking of the furfural compound increases, and the produced furan compound causes undesired reactions sequentially, resulting in a decrease in the yield of the furan compound. The purity of the hydrogen gas used at that time is usually 99% or more, preferably 99.9% or more, more preferably 99.99% or more, and particularly preferably 99.999% or more. Further, depending on the catalyst, water vapor can be accompanied.

  The supply amount of the furfural compound is usually 0.0001 mol / h or more and 50000 mol / h or less, preferably 0.001 mol / h or more and 10,000 mol / h or less, more preferably 0.01 mol / h or more with respect to 1 mol of the noble metal responsible for the catalytic activity. It is 5000 mol / h or less. The supply amount of the furfural compound is usually 1 mmol / h or more and 3000 mmol / h or less, preferably 10 mmol / h or more and 1500 mmol / h or less, more preferably 20 mmol / h or more and 500 mmol / h or less with respect to 1 g of the catalyst weight.

  The residence time is usually from 0.001 seconds to 10 seconds, preferably from 0.01 seconds to 5 seconds, more preferably from 0.05 seconds to 2 seconds, and particularly preferably from 0.1 seconds to 1 second. When the amount of catalyst metal or catalyst relative to the supply amount of furfural compound is small, or when the residence time is short, the furfural compound raw material is not fully converted, and it is not efficient because recovery of unreacted furfural compound is required. . In addition, when the amount of catalyst metal or the amount of catalyst relative to the supply amount of furfural compound is large or the residence time is long, the generated furan compound causes a sequential reaction, resulting in a decrease in the yield of the furan compound. is there. However, when a continuous reaction for a long time is performed, an excessive amount of the catalyst may be preliminarily charged in anticipation of a decrease in the activity of the catalyst. The reaction temperature is usually 170 ° C. or higher and 450 ° C. or lower, preferably 180 ° C. or higher and 380 ° C. or lower, more preferably 200 ° C. or higher and 340 ° C. or lower, and particularly preferably 230 ° C. or higher and 300 ° C. or lower. If the reaction temperature is low, the furfural compound raw material is not sufficiently converted, and it is not efficient because recovery of the unreacted furfural compound is required. On the other hand, if the reaction temperature is too high, the generated furan compound causes a sequential reaction, resulting in a decrease in the yield of the furan compound, which is not preferable. When the reaction pressure is expressed in absolute pressure, it is usually 0.01 MPa or more and 3 MPa or less, preferably 0.05 MPa or more and 2 MPa or less, and more preferably 0.1 MPa or more and 1 MPa or less. When the reaction pressure is low, the furan compound may be lost when the produced furan compound is separated.

  In the case of a liquid phase reaction, a catalyst containing a furfural compound raw material and at least one element selected from Zr and Hf and at least one metal element selected from Groups 8, 9, and 10 is charged into a reactor and stirred. When the boiling point of the furan compound produced by the reaction at an appropriate temperature is low, the furan compound can be collected from the gas phase. The reaction temperature is usually 120 ° C. or higher and 250 ° C. or lower, preferably 140 ° C. or higher and 230 ° C. or lower, particularly preferably 155 ° C. or higher and 220 ° C. or lower. When the reaction pressure is expressed in absolute pressure, it is usually 0.1 MPa or more and 1 MPa or less, preferably 0.15 MPa or more and 0.6 MPa or less, and more preferably 0.2 MPa or more and 0.3 MPa or less. High-boiling polar solvents such as gamma butyl lactone, N-methylpyrrolidone, triglyme and tetraglyme may be used, or liquid additives such as water may be used. A basic additive such as potassium carbonate, sodium carbonate or calcium acetate is also preferably used. By-product purge removal and catalyst addition or replacement can be performed as necessary. It is also preferable to continuously supply the furfural compound raw material.

  When continuously supplying the furfural compound raw material with reduced impurities to the decarbonylation reactor, the purification device for reducing impurities and the decarbonylation reactor are connected, and the furfural compound raw material is purified by distillation or adsorption removal and purified. The decarbonylation reactor is preferably fed to the reactor. In the case of distillation purification, it is effective not only to remove impurities having a high boiling point but also to remove impurities having a low boiling point and supply them to the decarbonylation reactor.

  The obtained furan compound is separated from by-produced carbon monoxide and by-products and hydrogen introduced as a reaction initiator, and then purified by an operation such as distillation. The separated hydrogen can be recycled and reused, and can also be used effectively for other purposes together with carbon monoxide.

  In the method of the present invention, particularly when a catalyst containing a specific metal such as Pt is used, in the conversion reaction of the furfural compound to the furan compound in the presence of hydrogen, the furfural compound or the produced furan compound is hydrogenated. And hydrogenolysis to produce ethane, ethylene, propane, propylene, butane, butene, propanol, butanol, tetrahydrofuran, 2-methylfuran, and 2-methyltetrahydrofuran. Therefore, the method of the present invention is also useful as a method for producing these ethane, ethylene, propane, propylene, butane, butene, propanol, butanol, tetrahydrofuran, 2methylfuran, and 2methyltetrahydrofuran from the furfural compound.

  By using the catalyst of the present invention, a furan compound having a very low impurity content can be obtained. The purity of the furan compound obtained is usually 99% or more. In the catalyst of the present invention, since a polymerization reaction or the like on the catalyst surface is avoided, the ratio of by-products due to the polymerization reaction or the like contained in the obtained furan compound is extremely low. The obtained furan compound is colorless and transparent, and is 50 or less when calculated by a number based on the YI (Yellowness Index) value of an APHI (American Public Health Association) standard color solution.

  Since the furan compound obtained by the present invention has a very small impurity content, it is useful as various resin raw materials and additives. For the same reason, it is useful as an intermediate for synthesizing derivatives, and a synthesis reaction using a furan compound as a raw material can be carried out efficiently. For example, if the obtained furan compound is a furan compound of the general formula (2), it can be converted to a furan compound of the general formula (6) by a hydrogenation reaction using a catalyst, or by a partial hydrogenation reaction. It can convert into the furan compound of General formula (3)-(5). Moreover, it can convert into diols, such as 1, 4- butanediol, and lactones, such as a gamma butyrolactone, combining hydration etc.

  By using the catalyst of the present invention, when producing a furan compound from a furfural compound, the amount of coke adhering to the catalyst is reduced and the catalyst can be used continuously for a long period of time. Reduce. There are no particular limitations on the catalyst regeneration method and regeneration treatment when the catalyst is deactivated. For example, it is possible to restore the catalyst performance by performing treatment at a high temperature with a gas containing oxygen and removing impurities and coke adhering to the catalyst surface. Further, the catalyst performance can be restored by removing impurities and coke adhered to the catalyst surface by washing with an organic solvent such as alcohol and drying. After removing impurities and coke, the same reduction treatment as in the catalyst preparation is performed before being subjected to the decarbonylation reaction of the furfural compound again. In other words, the metal responsible for catalytic activity can be reduced by reacting with a reducing agent in the liquid phase, or by processing a gas containing hydrogen or alcohol through a tube and processing in a reducing gas stream. It is suitably performed. These series of regeneration treatments may be carried out with the catalyst loaded in the reactor for carrying out the decarbonylation reaction. In this case, it is preferable to provide a plurality of reactors for decarbonylation in advance. While the catalyst loaded in one reactor is regenerated, a furan compound can be continuously produced by carrying out the decarbonylation reaction of the furfural compound with the catalyst loaded in another reactor.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples unless it exceeds the gist. The purity of the furfural compound as a raw material for the furfural compound is estimated from the GC peak area ratio, and the sulfur concentration and the nitrogen concentration are measured by the combustion-absorption-ion chromatography method (combustion device: manufactured by Mitsubishi Chemical Corporation, sample combustion device, QF, respectively). -02, analyzer: Nippon Dionex, ion chromatography DX-500), combustion decomposition-chemiluminescence method (Mitsubishi Chemical Corporation, trace nitrogen analyzer, TN-10). The acid value of the furfural compound raw material was measured by diluting the furfural compound raw material with ethanol and then titrating with a 0.01N potassium hydroxide aqueous solution.

Example 1
<Change over time in furfural conversion: 1 mass% Pd catalyst supported on zirconia>
Commercially pelleted zirconia (surface area: 99 m ^{2 /} g, PV: 0.35 ml / g) is pulverized and sieved to a particle size of 500 μm to 1000 μm, and fired at 600 ° C. for 6 hours under an air stream of about 100 ml / min. did. To 5.00 g of this calcined zirconia, 0.50 g of a Pd nitrate solution ([Pd (NO ₃ ) ₄ ] ²⁻ ) (Pd: 9.98 mass%, HNO ₃ : 18.8 mass%) was diluted with distilled water. Using the prepared solution, Pd was impregnated by an incipient-wetness method. After removing the water in a hot water bath, it was dried at 120 ° C. for 6 hours under a nitrogen stream of about 30 ml / min. Further, it was calcined at 500 ° C. for 4 hours under an air stream of about 50 ml / min to obtain a 1% by mass Pd catalyst (1% by mass Pd / ZrO ₂ ) supported on zirconia.

As a raw material for the decarbonylation reaction, the commercially available reagent furfural A was used without any particular purification. At this time, the furfural purity of the furfural raw material was 99% or more, and the impurity concentration was a sulfur concentration of 23.1 ppm and a nitrogen concentration of 4.9 ppm. A glass reaction tube having an inner diameter of 8 mm was charged with 1.00 g of a zirconia-supported 1% by mass Pd catalyst obtained by the above-described method, and the temperature was increased at 13 ° C./min under a flow of 10 Nml / min of hydrogen. After the temperature of the catalyst layer reached 260 ° C., the catalyst layer was kept under a hydrogen stream at the same temperature for about 10 minutes. Thereafter, the composition of the gas to be circulated was changed to hydrogen 0.84 Nml / min and nitrogen 32.0 Nml / min. The raw material furfural was vaporized through a vaporizer heated to 170 ° C. and fed at a flow rate of 36.22 mmol / h to initiate the reaction. At this time, W / F was 28 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 4 mol _furfural / h · g _Pd , and the hydrogen / furfural ratio was 0.06. The reaction pressure was 0.1 MPa in absolute pressure. A portion of the distillate gas from the reaction tube outlet was introduced into the GC and quantitatively analyzed for furan, carbon monoxide, and other products. The furfural conversion rate and the furan selectivity were calculated from the following equations.

Furfural conversion rate (%)
= [1- {Furfural remaining amount after reaction (mol) / Furfural supply amount (mol)}] × 100

Franc selection rate (%)
= {Furan yield (%) / furfural conversion (%)} × 100
= [{Furan production amount (mol) / furfural feed amount (mol)} × 100 (%) / furfural conversion (%)] × 100

  When a 1% by mass Pd catalyst supported on zirconia was used, the furfural conversion rate 1.1 hours after the start of the reaction was 99%, and the furfural conversion rate 6.3 hours after the start of the reaction was 93%. The average furan selectivity in the 6.3 hour reaction was 98%. After the reaction for 6.3 hours, supply of furfural was stopped, and the temperature was lowered to room temperature under a gas stream of hydrogen 0.84 Nml / min and nitrogen 32.0 Nml / min. When the catalyst was taken out from the reaction tube and its weight was measured, a 0.04 g weight increase was observed due to impurities derived from the furfural raw material and coke adhesion caused by the reaction.

(Comparative Example 1)
<Change in furfural conversion over time: alumina-supported 1% by mass Pd catalyst>
The reaction was carried out in the same manner as in Example 1 except that an alumina-supported 1% by mass Pd catalyst (1% by mass Pd / Al ₂ O ₃ ) was used as the catalyst. The alumina-supported 1% by mass Pd catalyst is obtained by pulverizing and sieving a commercially available pellet-like γ-Al ₂ O ₃ (surface area: 174 m ^{2 /} g, PV: 0.37 ml / g) as an alumina carrier to a particle size of 500 μm to 1000 μm. The same procedure as in Example 1 except that the zirconia-supported 1% by mass Pd catalyst was used.

  When an alumina-supported 1% by mass Pd catalyst was used, the furfural conversion rate 1.1 hours after the start of the reaction was 91%, and the furfural conversion rate 6.3 hours after the start of the reaction was reduced to 65%. . The average furan selectivity in the 6.3 hour reaction was 98%. Further, the catalyst weight increase due to adhesion of impurities derived from furfural raw material after the reaction for 6.3 hours and coke generated by the reaction was 0.17 g.

(Example 2)
<Change over time in furfural conversion: 1 mass% Pd-1 mass% K catalyst supported on zirconia>
Commercially pelleted zirconia (surface area: 99 m ^{2 /} g, PV: 0.35 ml / g) is pulverized and sieved to a particle size of 500 μm to 1000 μm and calcined at 600 ° C. for 6 hours under an air stream of about 100 ml / h. did. To 5.00 g of this calcined zirconia, 0.50 g of a Pd nitrate solution ([Pd (NO ₃ ) ₄ ] ²⁻ ) (Pd: 9.98 mass%, HNO ₃ : 18.8 mass%) and KNO ₃ 0.0. Pd and K were impregnated by an incipient-wetness method using a solution obtained by diluting and dissolving 13 g with distilled water. After removing the water in a hot water bath, it was dried at 120 ° C. for 6 hours under a nitrogen stream of about 30 ml / min. Further, it is calcined at 500 ° C. for 4 hours under an air stream of about 50 ml / min, and then reduced at 450 ° C. for 2 hours under a hydrogen stream of about 75 ml / min to give a zirconia-supported 1 mass% Pd-1 mass% K catalyst. (1 wt% Pd-1 mass% K / ZrO ₂₎ was obtained.

The reaction was carried out in the same manner as in Example 1 except that 0.75 g of the zirconia-supported 1% by mass Pd-1% by mass K catalyst was used. At this time, W / F was 21 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 5 mol _furfural / h · g _Pd , and the hydrogen / furfural ratio was 0.06. The reaction pressure was 0.1 MPa in absolute pressure.

  When a zirconia-supported 1% by mass Pd-1% by mass K catalyst was used, the furfural conversion rate 1.1 hours after the start of the reaction was 100%, and the furfural conversion rate 6.3 hours after the start of the reaction was It was 96%. The average value of furan selectivity in the 6.3 hour reaction was 99%. After the reaction for 6.3 hours, supply of furfural was stopped, and the temperature was lowered to room temperature under a gas stream of hydrogen 0.84 Nml / min and nitrogen 32.0 Nml / min. When the catalyst was taken out from the reaction tube and its weight was measured, an increase in weight of 0.03 g was observed due to impurities derived from the furfural raw material and adhesion of coke produced by the reaction.

(Comparative Example 2)
<Change over time in conversion rate of furfural: alumina-supported 1 mass% Pd-1 mass% K catalyst>
The reaction was performed in the same manner as in Example 2 except that 1.00 g of alumina-supported 1% by mass Pd-1% by mass K catalyst (1% by mass Pd-1% by mass K / Al ₂ O ₃ ) was used. Alumina-supported 1% by mass Pd-1% by mass K catalyst is a particle size of 500 μm to 1000 μm of commercially available pellet-like γ-Al ₂ O ₃ (surface area: 174 m ^{2 /} g, PV: 0.37 ml / g) as an alumina carrier. The catalyst was prepared in the same manner as the zirconia-supported 1% by mass Pd-1% by mass K catalyst of Example 2 except that the crushed and sieved material was used. At this time, W / F was 28 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 4 mol _furfural / h · g _Pd , and the ratio of hydrogen / furfural was 0.06. The reaction pressure was 0.1 MPa in absolute pressure.

  When using an alumina-supported 1% by mass Pd-1% by mass K catalyst, the furfural conversion rate after 1.1 hours from the start of the reaction was 100%, and the furfural conversion rate after 6.3 hours from the start of the reaction was 89%. Declined. The average furan selectivity in the 6.3 hour reaction was 98%. Moreover, the weight increase of the catalyst by the adhesion of the coke produced by the impurity derived from the furfural raw material after reaction for 6.3 hours, or reaction was 0.11g.

(Comparative Example 3)
<Time-dependent change in furfural conversion: Silica-supported 1 mass% Pd-1 mass% K catalyst>
The reaction was carried out in the same manner as in Example 2 except that 0.75 g of silica-supported 1% by mass Pd-1% by mass K catalyst (1% by mass Pd-1% by mass K / SiO ₂ ) was used. The silica-supported 1% by mass Pd-1% by mass K catalyst uses Carriat Q-50 (surface area: 79 m ^{2 /} g, PV: 1.01 ml / g, particle size: 0.85 mm to 1.70 mm) as a silica support. The catalyst was prepared in the same manner as the zirconia-supported 1% by mass Pd-1% by mass K catalyst of Example 2. At this time, W / F was 21 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 5 mol _furfural / h · g _Pd , and the hydrogen / furfural ratio was 0.06. The reaction pressure was 0.1 MPa in absolute pressure.

  When using a silica-supported 1% by mass Pd-1% by mass K catalyst, the furfural conversion 1.1 hours after the start of the reaction was 85%, and the furfural conversion 6.3 hours after the start of the reaction was 52%. Declined. The average furan selectivity in the 6.3 hour reaction was 98%. Further, the catalyst weight increase due to adhesion of impurities derived from furfural raw materials after the reaction for 6.3 hours and coke generated by the reaction was 0.05 g.

(Example 3)
<Change over time in furfural conversion: 1 mass% Pd catalyst supported on zirconia>
The catalyst prepared in the same manner as in Example 1 was reduced under a hydrogen stream of about 75 ml / min at 450 ° C. for 2 hours to obtain a zirconia-supported 1% by mass Pd catalyst (1% by mass Pd / ZrO ₂ ).

As a raw material for the decarbonylation reaction, a commercially available reagent, furfural B, which had been purified by distillation was used. At this time, the furfural purity of the furfural raw material was 99% or more, and the impurity concentration was a sulfur concentration of 1.3 ppm, a nitrogen concentration of 1.5 ppm, and an acid value of 0.072 mgKOH / g. A glass reaction tube having an inner diameter of 8 mm was charged with 0.75 g of the above-mentioned 1% by mass Pd catalyst supporting zirconia, and the temperature was raised at 14 ° C./min under a flow of 10 Nml / min of hydrogen. After the temperature of the catalyst layer reached 275 ° C., it was kept under a hydrogen stream at the same temperature for about 10 minutes. Thereafter, the composition of the gas to be circulated was changed to hydrogen 6.6 Nml / min and nitrogen 26.3 Nml / min. The raw material furfural was vaporized through a vaporizer heated to 170 ° C. and fed at a flow rate of 36.22 mmol / h to initiate the reaction. At this time, W / F was 21 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 5 mol _furfural / h · g _Pd , and the ratio of hydrogen / furfural was 0.5. The reaction pressure was 0.1 MPa in absolute pressure.

  When the furfural raw material was continuously reacted on a 1% by mass Pd catalyst supported on zirconia and decarbonylation was carried out, the furfural conversion rate after 2 hours from the start of the reaction was 100% and the furan selectivity was 96%. It was. The furfural conversion rate after 50 hours from the start of the reaction was 62%, and the furan selectivity was 97%. After the reaction for 64 hours, the furfural supply was stopped, and the temperature was lowered to room temperature under a gas stream of hydrogen 6.6 Nml / min and nitrogen 26.3 Nml / min. When the catalyst was taken out from the reaction tube and its weight was measured, a 0.04 g weight increase was observed due to impurities derived from the furfural raw material and coke adhesion caused by the reaction.

(Comparative Example 4)
<Change in furfural conversion over time: alumina-supported 1% by mass Pd catalyst>
The reaction was performed in the same manner as in Example 3 except that 1.00 g of an alumina-supported 1% by mass Pd catalyst (1% by mass Pd / Al ₂ O ₃ ) was used. An alumina-supported 1% by mass Pd catalyst was prepared by the following method.

Commercially available spherical γ-alumina (surface area: 231 m ^{2 /} g, PV: 0.55 ml / g) was calcined at 300 ° C. for 3 hours under an air stream. About 10 g of this calcined alumina was absorbed in a desiccator filled with water for about one week. Using a solution in which about 13 g of moisture-absorbed alumina (about 10 g when dried) was dissolved in 0.3 g of tetraamminepalladium (II) nitrate ([Pd (NH ₃ ) ₄ ] (NO ₃ ) ₂ ) in 10 g of distilled water. Then, Pd was impregnated by an impregnation method. After removing water with a rotary evaporator, it was dried at 120 ° C. for 3 hours under an air stream of about 100 ml / min. Further, it was calcined at 520 ° C. for 2 hours under an air stream of about 100 ml / min to obtain an alumina-supported 1 mass% Pd catalyst.

In this reaction, W / F was 28 g _Cat · h / mol _furfural , the supplied furfural per supported metal amount was 4 mol _furfural / h · g _Pd , and the hydrogen / furfural ratio was 0.5. The reaction pressure was 0.1 MPa in absolute pressure.

  When the furfural raw material was continuously reacted on an alumina-supported 1% by mass Pd catalyst and decarbonylation was performed, the furfural conversion after 2 hours from the start of the reaction was 93% and the furan selectivity was 97%. It was. The furfural conversion after 50 hours from the start of the reaction decreased to 44%, and the furan selectivity was 97%. Further, the catalyst weight increase due to adhesion of impurities derived from furfural raw materials after the reaction for 63 hours and coke generated by the reaction was 0.25 g.

Example 4
<Change over time in furfural conversion: 2 mass% Pt catalyst supported on zirconia>
Commercially pelleted zirconia (surface area: 99 m ^{2 /} g, PV: 0.35 ml / g) is pulverized and sieved to a particle size of 500 μm to 1000 μm, and fired at 600 ° C. for 6 hours under an air stream of about 100 ml / min. did. Incipient-wetness using a solution obtained by diluting 1.93 g of Pt nitrate solution ([Pt (NO ₃ ) ₄ ] ²⁻ ) (Pt: 5.17% by mass) with distilled water to 5.00 g of this calcined zirconia. Pt was impregnated by the method. After removing the water in a hot water bath, it was dried at 120 ° C. for 6 hours under a nitrogen stream of about 30 ml / min. Further, it was calcined at 500 ° C. for 4 hours under an air stream of about 50 ml / min, and then reduced at 450 ° C. for 2 hours under a hydrogen stream of about 75 ml / min to obtain a zirconia-supported 2 mass% Pt catalyst (2 mass% Pt / ZrO ₂ ).

The reaction was performed in the same manner as in Example 3 except that 1.00 g of the 2% by mass Pt catalyst supported on zirconia was used. At this time, W / F was 28 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 2 mol _furfural / h · g _Pt and the ratio of hydrogen / furfural was 0.5. The reaction pressure was 0.1 MPa in absolute pressure.

  When the furfural raw material was continuously reacted on a zirconia-supported 2% by mass Pt catalyst and decarbonylation was performed, the furfural conversion rate after 2 hours from the start of the reaction was 73% and the furan selectivity was 85%. It was. Main by-products were propane, propylene, butane, butene and the like, and the ratio of propane, propylene, butane and butene in the product was 11% in total. 50 hours after the start of the reaction, the furfural conversion was 79%, and the furan selectivity was 94%. Main by-products were propane, propylene, butane, butene and the like, and the proportion of propane, propylene, butane and butene in the product was 4% in total. After the reaction for 64 hours, the furfural supply was stopped, and the temperature was lowered to room temperature under a gas stream of hydrogen 6.6 Nml / min and nitrogen 26.3 Nml / min. When the catalyst was taken out of the reaction tube and the weight was measured, a 0.05 g weight increase was observed due to impurities derived from the furfural raw material and coke adhesion caused by the reaction.

(Comparative Example 5)
<Change in furfural conversion over time: alumina-supported 2% by mass Pt catalyst>
The reaction was performed in the same manner as in Example 3 except that 1.00 g of alumina-supported 2% by mass Pt catalyst (2% by mass Pt / Al ₂ O ₃ ) was used as the catalyst. The alumina-supported 2% by mass Pt catalyst is obtained by pulverizing and sieving a commercially available pellet-like γ-Al ₂ O ₃ (surface area: 174 m ^{2 /} g, PV: 0.37 ml / g) as an alumina support to a particle size of 500 μm to 1000 μm. It was prepared in the same manner as the zirconia-supported 2% by mass Pt catalyst of Example 4 except that the fraction was used. At this time, W / F was 28 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 2 mol _furfural / h · g _Pt and the ratio of hydrogen / furfural was 0.5. The reaction pressure was 0.1 MPa in absolute pressure.

  When the furfural raw material was continuously reacted on an alumina-supported 2% by mass Pt catalyst and decarbonylation was performed, the furfural conversion rate after 2 hours from the start of the reaction was 99% and the furan selectivity was 95%. It was. Main by-products were propane, propylene, butane, butene and the like, and the proportion of propane, propylene, butane and butene in the product was 4% in total. The furfural conversion after 50 hours from the start of the reaction decreased to 92%, and the furan selectivity was 96%. The main by-products were propane, propylene, butane, butene, etc., and the proportion of propane, propylene, butane, butene in the product was 3% in total. Moreover, the weight increase of the catalyst by the adhesion of the coke produced by the impurity derived from the furfural raw material and reaction after implementing reaction for 50 hours was 0.18g.

(Example 5)
<Durability test: 1 mass% Pd-1 mass% K catalyst supported on zirconia>
As a raw material for the decarbonylation reaction of furfural, a product obtained by distilling and purifying a commercially available reagent furfural B was used. At this time, the furfural purity of the furfural raw material was 99% or more, and the impurity concentration was a sulfur concentration of 1.3 ppm, a nitrogen concentration of 1.5 ppm, and an acid value of 0.072 mgKOH / g. Zirconia-supported 1% by mass Pd-1% by mass K catalyst (0.30 g) prepared by the method of Example 2 was charged into a glass reaction tube having an inner diameter of 8 mm, and the temperature was raised at 14 ° C./min under a flow of 10 Nml / min of hydrogen. . After the temperature of the catalyst layer reached 285 ° C., the catalyst layer was kept under a hydrogen stream at the same temperature for about 10 minutes. Thereafter, the composition of the gas to be circulated was changed to 2.2 Nml / min for hydrogen and 39.6 Nml / min for nitrogen. The raw material furfural was vaporized through a vaporizer heated to 170 ° C. and fed at a flow rate of 12.07 mmol / h to initiate the reaction. At this time, W / F was 25 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 4 mol _furfural / h · g _Pd , and the ratio of hydrogen / furfural was 0.5. The reaction pressure was 0.1 MPa in absolute pressure.

  When the furfural raw material is continuously reacted on a zirconia-supported 1% by mass Pd-1% by mass K catalyst and decarbonylation is performed, the furfural conversion rate after 10 hours from the start of the reaction is 100%, and the furan selectivity. Was 98%. The furfural conversion rate after 50 hours from the start of the reaction was 96%, and the furan selectivity was 98%. After 100 hours from the start of the reaction, the furfural conversion was 94% and the furan selectivity was 98%. After 150 hours from the start of the reaction, the furfural conversion was 94%, and the furan selectivity was 98%. 200 hours after the start of the reaction, the furfural conversion was 94% and the furan selectivity was 98%. After 70 hours from the start of the reaction, the change with time in the furfural conversion rate and the change with time in the furan selectivity were not observed. After the reaction for 200 hours, the furfural supply was stopped, and the temperature was lowered to room temperature under a gas stream of hydrogen 2.2 Nml / min and nitrogen 39.6 Nml / min. When the catalyst was taken out from the reaction tube and its weight was measured, an increase in weight of 0.02 g was observed due to impurities derived from the furfural raw material and adhesion of coke produced by the reaction.

(Example 6)
<Durability test: 2 mass% Pt catalyst supported on zirconia>
As a raw material for the decarbonylation reaction of furfural, a product obtained by distillation purification of the commercially available reagent furfural B was used. At this time, the furfural purity of the furfural raw material was 99% or more, and the impurity concentration was a sulfur concentration of 1.3 ppm, a nitrogen concentration of 1.5 ppm, and an acid value of 0.072 mgKOH / g. The reaction was carried out in the same manner as in Example 5 except that 0.50 g of zirconia-supported 2% by mass Pt catalyst (2% by mass Pt / ZrO ₂ ) prepared by the method of Example 4 was used. At this time, W / F was 41 g _Cat · h / mol _furfural , the supply furfural per supported metal amount was 1.2 mol _furfural / h · g _Pt , and the hydrogen / furfural ratio was 0.5. The reaction pressure was 0.1 MPa in absolute pressure.

  When the furfural raw material was continuously reacted on a zirconia-supported 2% by mass Pt catalyst and decarbonylation was performed, the furfural conversion after 10 hours from the start of the reaction was 81% and the furan selectivity was 89%. It was. Main by-products were propane, propylene, butane, butene and the like, and the ratio of propane, propylene, butane and butene in the product was 9% in total. The furfural conversion rate after 50 hours from the start of the reaction was 80%, and the furan selectivity was 92%. Main by-products were propane, propylene, butane, butene and the like, and the ratio of propane, propylene, butane and butene in the product was 7% in total. The furfural conversion rate after 98 hours from the start of the reaction was 84%, and the furan selectivity was 93%. The main by-products were propane, propylene, butane, butene, etc., and the proportion of propane, propylene, butane, butene in the product was 5% in total. After 150 hours from the start of the reaction, the furfural conversion was 86%, and the furan selectivity was 94%. The main by-products were propane, propylene, butane, butene, etc., and the proportion of propane, propylene, butane, butene in the product was 5% in total. 200 hours after the start of the reaction, the furfural conversion was 83% and the furan selectivity was 94%. The main by-products were propane, propylene, butane, butene, etc., and the proportion of propane, propylene, butane, butene in the product was 5% in total. Up to 120 hours after the start of the reaction, the furfural conversion rate increased with time, the proportion of by-products decreased with the passage of the reaction time, and the furan selectivity increased. After 120 hours from the start of the reaction, the change in furfural conversion with time and the change with time in furan selectivity were hardly observed. After the reaction for 200 hours, the furfural supply was stopped, and the temperature was lowered to room temperature under a gas stream of hydrogen 2.2 Nml / min and nitrogen 39.6 Nml / min. When the catalyst was taken out from the reaction tube and its weight was measured, an increase in weight of 0.03 g was observed due to impurities derived from the furfural raw material and adhesion of coke produced by the reaction.

(Comparative Example 6)
A 200 ml flask was charged with 1.00 g of the same catalyst used in Example 1 and 60.0 g of the same furfural as used in Example 1, and 32.0 Nml of nitrogen gas was passed through the flask. The flask was heated using an oil bath, and the liquid phase temperature was controlled at 150 ° C. to initiate the liquid phase decarbonylation reaction of furfural. When the furan production rate was determined by quantifying the concentration of furan accompanying nitrogen gas over time, the furan production rate was 10 mmol / h or less. The furan concentration after 6.3 hours from the start of the reaction was 90% or less of the furan concentration after 1.1 hours from the start of the reaction, and it was found that the catalyst activity decreased with time.

  From the comparison between Example 1 and Comparative Example 1, when a catalyst containing Zr was used, the decrease in the catalyst activity over time was smaller than when a catalyst containing no Zr was used, and a high furfural conversion rate and a high furan selectivity were obtained. Therefore, it was found that the furan compound can be produced stably and efficiently. In addition, it was found that the catalyst containing Zr has less adhesion of impurities derived from the furfural raw material after the reaction for a certain period of time and the coke produced by the reaction than the catalyst not containing Zr.

  Comparison between Example 2 and Comparative Examples 2 and 3 shows that when a catalyst containing Zr is used, a decrease in the catalyst activity with time is small compared to when a catalyst containing no Zr is used, and a high furfural conversion rate and a high furan selection are obtained. Since the rate was maintained, it was found that the furan compound can be produced stably and efficiently. In addition, it was found that the catalyst containing Zr has less adhesion of impurities derived from the furfural raw material after the reaction for a certain period of time and the coke produced by the reaction than the catalyst not containing Zr.

  From the comparison between Example 3 and Comparative Example 4, when the catalyst containing Zr was used, the decrease in the catalyst activity with time was small compared with the case of using the catalyst not containing Zr, and a high furfural conversion rate and a high furan selectivity were obtained. Therefore, it was found that the furan compound can be produced stably and efficiently. In addition, it was found that the catalyst containing Zr has less adhesion of impurities derived from the furfural raw material after the reaction for a certain period of time and the coke produced by the reaction than the catalyst not containing Zr.

  From the comparison between Example 4 and Comparative Example 5, when the catalyst containing Zr was used, the catalyst activity decreased with time less than when the catalyst containing no Zr was used, and a high furfural conversion rate and a high furan selectivity were maintained. Therefore, it has been found that the furan compound can be produced stably and with high efficiency. In addition, it was found that the catalyst containing Zr has less adhesion of impurities derived from the furfural raw material after the reaction for a certain period of time and the coke produced by the reaction than the catalyst not containing Zr.

  From the results of Example 5 and Example 6, when a catalyst containing Zr was used, the catalyst activity was little decreased with time, and high furfural conversion and high furan selectivity were maintained over a long period of time. It can be seen that the furan compound can be produced with high efficiency.

  From the comparison between Example 1 and Comparative Example 6, it can be seen that when the zirconia-supported 1% by mass Pd catalyst is used, the reaction efficiency is higher when the reaction is performed in the gas phase flow system than when the reaction is performed in the liquid phase. In addition, the decrease in the activity of the catalyst over time is small, and the furan compound can be produced stably and efficiently.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the present invention can be modified as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and a method for producing a furan compound accompanying such a change is also included in the technical scope of the present invention. Must be understood.

Claims (3)

A step of vaporizing a furfural compound raw material represented by the following general formula (1) into a gaseous raw material, and bringing the gaseous raw material into contact with a catalyst containing Zr and Pd or Pt for a decarbonylation reaction; And a method for producing a furan compound.

(In General Formula (1), R ^{1 to} R ³ are hydrogen, an aliphatic hydrocarbon group that may have a functional group, an aromatic hydrocarbon group that may have a functional group, a hydroxyl group, and an aldehyde. Any one of the groups may be the same or different.) The catalyst contains 0.01% by mass or more and 50% by mass or less of at least one element selected from Group 1, 2, 6, and 13 elements when the mass of the entire catalyst is 100% by mass. 2. A method for producing a furan compound according to 1 . 3. The method for producing a furan compound according to claim 1, wherein the furfural compound raw material is any one of hydroxymethylfurfural, 2-methylfurfural, 3-methylfurfural, furfuryldialdehyde, and furfural. .