Deoxygenation catalyst, and method for producing sulfide compound by deoxygenation of sulfoxide compound using same

Abstract

The present invention provides a deoxygenation catalyst that can be used in a deoxygenation reaction of a sulfoxide compound, and a method for producing a sulfide compound by deoxygenation of a sulfoxide compound using the same. The present invention relates to a deoxygenation catalyst that includes iron phosphide nanoparticles. Preferably, the iron phosphide nanoparticles are rod-shaped particles, and the maximum length of the rod-shaped particles in the long axis direction is less than 100 nm. The deoxygenation catalyst is preferably a deoxygenation catalyst for sulfoxide compounds.

Description

Catalyst for Deoxygenation and Method for Producing Sulfide Compound by Deoxygenation of Sulfoxide Compound Using the Same

[0001] The present invention relates to a catalyst for deoxygenation and a method for producing a sulfide compound by deoxygenation of a sulfoxide compound using the same.

[0002] The deoxygenation reaction of sulfoxide compounds is an important reaction in the fields of organic synthesis and pharmaceutical chemistry. Catalysts used in the deoxygenation reaction of sulfoxide compounds have also been developed (Patent Documents 1 and 2). On the other hand, especially the deoxygenation reaction of sulfoxides using hydrogen molecules as a reducing agent is a reaction process with excellent environmental compatibility because the reducing agent is non-toxic and inexpensive, and the by-products after the reaction are only water. In the past ten years or so, catalyst development has been carried out to promote this reaction with high efficiency.

[0003] Conventionally, metals such as platinum, ruthenium, nickel, and cobalt have been used in the developed catalysts (Patent Document 2 and Non-Patent Documents 1 to 7). However, these metals have problems such as being expensive, rare, and highly toxic.

[0004] Iron can be cited as a metal that can solve the above problems. Iron is inexpensive, abundantly present in the earth's crust, and has low toxicity to living organisms and the environment, making it an extremely attractive catalyst material.

[0005] JP 2012-121845 A, JP 2015-211932 A

[0006] “Hydrodeoxygenation of sulfoxides to sulfides by a Pt and MoOx co-loaded TiO2 catalyst”, Abeda Sultana Touchy, S. M. A. Hakim Siddiki et al., Green Chem., 2016, 18, pp. 2554-2560“Platinum-supporting hollandite-type vanadium-chromium mixed oxides as efficient heterogeneous catalysts for deoxygenation of sulfoxides under atmospheric H2 pressure”, Tsubasa Uematsu, Yoshiyuki Ogasawara et al., Catalysis Science & Technology, 2017, 7, pp. 1912-1920“Mild Deoxygenation of Sulfoxides over Plasmonic Molybdenum Oxide Hybrid with Dramatic Activity Enhancement under Visible Light”, Yasutaka Kuwahara, Yukihiro Yoshimura et al., J. Am. Chem. Soc, 2018, Vol.140, Issue 29, pp. 9203-9210.“Hydrogenation of Sulfoxides to Sulfides under Mild Conditions Using Ruthenium Nanoparticle Catalysts”, Takato Mitsudome, Yusuke Takahashi et al., Angew. Chem. International Edition, 2014, Volume 53, Issue 32, pp.8348-8351 "Phosphorus-Alloying as a Powerful Method for Designing Highly Active and Durable Metal Nanoparticle Catalysts for the Deoxygenation of Sulfoxides: Ligand and Ensemble Effects of Phosphorus", Hiroya Ishikawa, Sho Yamaguchi et al., JACS Au 2022, 2, 2, pp. 419-427 "Nickel phosphide nanoalloy catalyst for the selective deoxygenation of sulfoxides to sulfides under ambient H2 pressure", Shu Fujita, Sho Yamaguchi et al., Org. Biomol. Chem., 2020, 18, pp.8827-8833 "Efficient hydrodeoxygenation of sulfoxides into sulfides under mild conditions using heterogeneous cobalt-molybdenum catalysts", Kaiyue Yao, Ziliang Yuan et al., Green Chem., 2020, 22, pp.39-43.

[0007] However, iron-based catalysts have problems such as difficulty in controlling the reaction system to be applied as a catalyst, and no iron-based catalyst that can be used in the deoxygenation reaction of sulfoxide compounds has been developed. Therefore, the development of an iron-based catalyst that can efficiently promote the deoxygenation reaction of sulfoxide compounds is required.

[0008] An object of the present invention is to provide a deoxygenation catalyst that can be used in the deoxygenation reaction of sulfoxide compounds and a method for producing a sulfide compound by deoxygenating a sulfoxide compound using the same.

[0009] The inventors of this invention conducted extensive research to solve the above problems and found that the above problems could be solved by using nano-iron phosphide particles synthesized by the solvothermal method. Based on this finding, they furthered their research and completed the present invention.

[0010] The present invention encompasses the following inventions: [1] A deoxygenation catalyst comprising nanoiron phosphide particles. [2] The deoxygenation catalyst according to [1], wherein the nanoiron phosphide particles are rod-shaped particles, and the maximum length in the longitudinal direction of the rod-shaped particles is less than 100 nm. [3] The deoxygenation catalyst according to [1] or [2], which is a sulfoxide compound deoxygenation catalyst. [4] The deoxygenation catalyst according to any one of [1] to [3], further comprising a carrier, comprising a composite composed of the nanoiron phosphide particles and the carrier, wherein the carrier is at least one selected from the group consisting of polymers, chalcogen compounds, metal compounds, metals, and solid carbon materials. [5] The deoxygenation catalyst according to [4], wherein the carrier comprises TiO2. [6] The deoxygenation catalyst according to any one of [1] to [5], wherein the nanoiron phosphide particles are Fe2P. [7] A method for producing a sulfide compound, comprising deoxygenating a sulfoxide compound in a hydrogen atmosphere in the presence of a deoxygenating catalyst described in any of [1] to [6] to obtain a sulfide compound. [8] The method for producing a sulfide compound according to [7], wherein the sulfoxide compound is heated during the reaction. [9] The method for producing a sulfide compound according to [8], wherein the heating temperature is less than 200°C.

[10] The method for producing a sulfide compound according to any of [7] to [9], wherein the reaction is carried out in the presence of a solvent.

[0011] The present invention provides a deoxygenation catalyst that can be used in the deoxygenation reaction of sulfoxide compounds, and a method for producing sulfide compounds by deoxygenating sulfoxide compounds using the same. Furthermore, the deoxygenation catalyst of the present invention is particularly suitable for use as a deoxygenation catalyst for sulfoxide compounds in the deoxygenation reaction of sulfoxide compounds.

[0012] Furthermore, nano-ferric phosphate particles obtained by the manufacturing method of the present invention (hereinafter referred to as "nano-Fe") xWhen used as a deoxygenation catalyst, it can carry out the deoxygenation reaction of sulfoxide compounds under mild conditions, thereby producing sulfide compounds.

[0013] Furthermore, the nano-phosphated iron particles of the present invention, the composite containing the nano-phosphated iron particles and a carrier, and the deoxygenation catalyst are low in toxicity and highly safe because they use iron, which is also present in living organisms, as a metal source. Moreover, since the nano-phosphated iron particles of the present invention do not contain precious metals and contain only iron as a metallic element, they are industrially advantageous in terms of cost due to the large amount of iron present on Earth (reserves).

[0014] Furthermore, the deoxygenation catalyst of the present invention is a solid catalyst and is easy to recover after use. Moreover, the deoxygenation catalyst of the present invention can selectively deoxygenate many types of sulfoxide compounds to produce sulfide compounds, exhibiting excellent substrate selectivity.

[0015] Figure 1 shows a transmission electron microscope (TEM) image of the nanoiron phosphide particles obtained in Example 1-1. Figure 2 shows the measurement results of powder X-ray diffraction of the nanoiron phosphide particles obtained in Example 1-1, indicating the peak position of the crystal plane corresponding to Fe2P.

[0016] The embodiments of the present invention will be described below. However, the present invention is not limited to the embodiments described below. In this specification, the nano-ferric phosphide particles of the present invention are collectively referred to as "nano-Fe x It is also written as "P" (where x represents 1 or 2). In this specification, a sulfoxide compound means a compound in which two carbon atoms are bonded to a sulfinyl group (-S (=O)-). In this specification, a sulfide compound means an organic compound in which a divalent sulfur (-S-) is substituted with two organic groups. In this specification, the upper and lower limits of numerical ranges (such as the size of nano-ferrous phosphide particles, the amount of a certain component (material such as a compound) used, temperature, pressure, or values ​​and physical properties calculated from each numerical range) can be combined as appropriate.

[0017] In this specification, "atmospheric conditions" means an atmospheric oxygen concentration of approximately 21%. Furthermore, the nano-ferric phosphide particles of the present invention exhibit excellent stability under conditions where oxygen is present. The oxygen concentration under conditions where oxygen (O2) is present is not particularly limited and may be approximately 21% of the atmospheric oxygen concentration, or it may be approximately 22% to 100%. The nano-ferric phosphide particles of the present invention exhibit excellent atmospheric stability and can maintain a low-valence state under conditions where oxygen is present, regardless of the oxygen concentration.

[0018] One embodiment of the present invention relates to a deoxygenation catalyst containing nano-iron phosphide particles. One embodiment of the present invention is the use of a deoxygenation catalyst for producing a sulfide compound from a sulfoxide compound.

[0019] The deoxygenation catalyst of the present invention is preferably a deoxygenation catalyst for sulfoxide compounds. By using the deoxygenation catalyst containing nano-ferric phosphide particles of the present invention, only oxygen atoms can be selectively removed from the sulfinyl group of the sulfoxide compound, converting the sulfinyl group into a sulfide group.

[0020] The following describes the use of nano-phosphate iron particles as a deoxygenation catalyst.

[0021] The shape of the nano-ferrous phosphide particles of the present invention is not particularly limited, but rod-shaped particles are preferred. The rod-shaped particles only need to have recognizable long and short axes, and include those that do not strictly have a rod shape. The morphology of the rod-shaped particles can be confirmed, for example, by TEM observation.

[0022] In the rod-shaped particles, the length in the longitudinal direction (maximum length in the longitudinal direction) is preferably less than 100 nm, more preferably 90 nm or less, and even more preferably 80 nm or less. Depending on the embodiment, it may be 70 nm or less, 60 nm or less, 50 nm or less, or 40 nm or less. Being within this range allows for stable existence in a low-valence state in the atmosphere, increases the surface area of ​​a single particle, and further enhances catalytic activity. In one embodiment, for example, the maximum length in the longitudinal direction of the rod-shaped particles is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more.

[0023] The length along the long axis of a rod-shaped particle (maximum length along the long axis) represents the arithmetic mean of the lengths along the long axis (maximum length along the long axis) of any 100 particles observed in electron microscopy. The number of particles measured may be 200 or 500, if necessary.

[0024] One embodiment of this invention is a deoxygenation catalyst in which the nano-iron phosphide particles are rod-shaped particles, and the maximum length of the rod-shaped particles in the longitudinal direction is less than 100 nm.

[0025] When the nano-iron phosphide particles of the present invention are rod-shaped particles, the cross-sectional shape of the surface having a short axis (bottom surface) is not particularly limited, but may be hexagonal, for example. The shape of the bottom surface is not particularly limited and may be flat, have irregularities, or have only convex portions.

[0026] In the rod-shaped particles, the length in the short axis direction (maximum length in the short axis direction) is not particularly limited as long as it is shorter than the length in the long axis direction (maximum length in the long axis direction). For example, if the cross-sectional shape of the surface having the short axis (bottom surface) is hexagonal, the length in the short axis direction (maximum length) is the length of the diagonal, which is the longest length in the cross-section. The length in the short axis direction (maximum length) is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less. Depending on the embodiment, it may be 20 nm or less, or 10 nm or less. When the objective is to be able to exist stably in a low-valence state in the air, to increase the surface area of ​​a single particle, and to increase catalytic activity, the length in the short axis direction (maximum length) is preferably longer, and may be 1 nm or more, 5 nm or more, or 9 nm or more. The length in the short axis direction (maximum length) means the arithmetic mean of the diagonal lengths, which are the longest lengths in the cross-section of the surface having the short axis (bottom surface) of any 100 particles observed in electron microscope observation. If necessary, the number of particles to be measured may be set to 200, 500, or 600.

[0027] In the rod-shaped particles, the aspect ratio (length in the long axis direction : length in the short axis direction) is not particularly limited, but is preferably 100:1 to 100:95, more preferably 100:5 to 100:75, and even more preferably 100:10 to 100:50. The aspect ratio can be calculated from the values ​​obtained from the length in the long axis direction and the length in the short axis direction of the rod-shaped particles.

[0028] The size of the nano-ferrous phosphide particles of the present invention can be adjusted by adjusting the selection and concentration of the raw material compound, heating temperature, heating conditions (stirring speed, etc.), reaction time, etc., in the method for producing nano-ferrous phosphide particles described later.

[0029] In one embodiment, the nano-iron phosphide particles used in the deoxygenation catalyst of the present invention have peaks at diffraction angles of 48.3° and 32.7° (2θ ± 0.5°) in powder X-ray diffraction measurements using CuKα rays. When measured by X-ray photoelectron spectroscopy (XPS), Fe2p 3 / 2In the spectrum, the iron atoms present have peaks in the range of 706.0 to 707.5 eV.

[0030] The nano-phosphated iron particles of the present invention have iron atoms in a low-valence state (metallic state) and exhibit excellent stability under atmospheric conditions. "Valence" is a number that represents the ability of an atom of an element to bond with an amount of atoms of other elements. The iron (Fe) atoms contained in the nano-phosphated iron particles of the present invention are in a low-valence state.

[0031] In one embodiment, the nano-iron phosphide particles of the present invention have peaks at diffraction angles of 48.3° and 32.7° (2θ ± 0.5°) in powder X-ray diffraction measurements using CuKα rays. The diffraction angles may also be 2θ ± 0.2°, 2θ ± 0.5°, or 2θ ± 0.8°.

[0032] For powder X-ray diffraction analysis (XRD) using CuKα rays, known X-ray diffractometers can be used. Commercially available X-ray diffractometers can be used (for example, the fully automated multi-purpose X-ray diffractometer (product name "Philips X'PERT MPD diffractometer," manufactured by Philips Japan, Ltd.)).

[0033] The nano-iron phosphide particles used in the deoxygenation catalyst of the present invention are in a low-valence state and possess the property of being able to stably maintain the compound structure under atmospheric conditions (hereinafter also referred to as "atmospheric stability"). Therefore, the crystal structure can be measured by X-ray diffraction under conditions in which oxygen is present.

[0034] The nano-iron phosphide particles used in the deoxygenation catalyst of the present invention preferably have a peak at 46.3° in the powder X-ray diffraction measurement.

[0035] The nano-ferric phosphide particles used in the deoxygenation catalyst of the present invention have peaks at diffraction angles of 32.7°, 46.3°, and 48.3° in the X-ray diffraction pattern using CuKα rays (hereinafter also referred to as the "XRD pattern"), which correspond to the (011) plane, (112) plane, and (211) plane crystal plane of FeP, respectively.

[0036] In one embodiment, the deoxygenation catalyst of the present invention includes a deoxygenation catalyst containing nano-iron phosphide particles made of Fe2P. The nano-iron phosphide particles made of Fe2P are in a low-valence state and have atmospheric stability. Furthermore, since the deoxygenation catalyst of the present invention does not contain platinum, ruthenium, nickel, and cobalt, it is advantageous in terms of cost and biosafety.

[0037] Another embodiment includes nano-iron phosphide particles having peaks at 40.2°, 52.1°, and 54.6° in the powder X-ray diffraction measurement. Furthermore, the nano-iron phosphide particles may have a peak at 43.8°. Yet another embodiment includes nano-iron phosphide particles made of Fe2P. The nano-iron phosphide particles made of Fe2P are in a low-valence state and have atmospheric stability, and compared to FeP, the ratio of low-valence iron atoms to phosphorus atoms is higher, and it is thought that they have higher catalytic activity.

[0038] The peaks that the nano-phosphate iron particles of the present invention have at diffraction angles of 40.2°, 43.8°, 52.1°, and 54.6° in the CuKα-ray XRD pattern correspond to the (111) plane, (201) plane, (002) plane and / or the (300) plane and (112) plane, respectively. Furthermore, it is preferable that Fe2P has peaks at diffraction angles of 44.2° and 47.3°.

[0039] The fact that the peaks at the aforementioned diffraction angles can be identified as Fe2P and FeP is also evident from the JCPDS cards in the International Centre for Diffraction Data (ICDD) database (Powder Diffraction File, Level 4 plus) (Fe2P is File 51-0943; FeP is File 39-0809).

[0040] The nano-phosphated iron particles of the present invention can maintain a low-valence state of iron atoms without oxidation in the atmosphere. The low-valence state of iron atoms in the nano-phosphated iron particles of the present invention can be confirmed, for example, by measurement using X-ray photoelectron spectroscopy (XPS). In the XPS measurement results, the vertical axis represents photoelectron intensity, and the horizontal axis represents binding energy (unit: eV). "Low-valence iron atoms" refers to the Fe2p state measured by X-ray photoelectron spectroscopy (XPS). 3 / 2 In the spectrum, this means that the iron atoms contained in the nano-phosphate iron particles have peaks in the range of 706.0 to 707.5 eV.

[0041] XPS can use a known X-ray photoelectron spectroscopy analyzer. The X-ray photoelectron spectroscopy analyzer may be a commercially available product (for example, an X-ray photoelectron analyzer (product name "KRATOS ULTRA2", manufactured by Shimadzu Corporation), a photoelectron spectrometer (model number "JPS-9030", manufactured by JEOL Ltd.), a scanning X-ray photoelectron spectroscopy analyzer (model number "PHI Quantera II", manufactured by ULVAC-PHI, Inc.), etc.). AlKα rays, MgKα rays, AgLα rays, etc., can be used as excitation sources. Fe2p 3 / 2 The spectrum can be measured, for example, by XPS analysis using an X-ray photoelectron analyzer (product name "KRATOS ULTRA2", manufactured by Shimadzu Corporation) with AlKα rays as the excitation source.

[0042] The nano-phosphated iron particles of the present invention are stable under atmospheric conditions because the iron atoms contained in the nano-phosphated iron particles are in a low-valence state. In other words, the iron atoms constituting the nano-phosphated iron particles of the present invention can remain in a low-valence state with catalytic activity without changing their state over time under atmospheric conditions. In this respect, it differs from the prior art.

[0043] The valency of iron atoms in the nano-phosphate iron particles of the present invention can be analyzed, for example, by X-ray absorption fine structure (XAFS). Specifically, by irradiating a metal atom with high-intensity X-rays, preferably high-intensity X-rays with continuously changing energy, the inner-shell electrons of the metal atom are excited to energy levels above the unoccupied orbitals. The excited metal atom then emits photoelectrons with kinetic energy corresponding to the difference between the excitation energy of the incident X-rays and the binding energy of the inner-shell electrons. A fine structure appears near the absorption edge in the X-ray absorption spectrum of the metal atom, and by analyzing this, the electronic state of the metal atom can be determined. Within the energy range of such XAFS, the fine structure that appears near the absorption edge, around several tens of eV, is called the X-ray Absorption Near Edge Structure (XANES). On the other hand, within the energy range of XAFS, the modulated structure that extends from the absorption edge to an energy level approximately 1000 eV higher is called the Extended X-ray Absorption Fine Structure (EXAFS). EXAFS is a vibrational structure resulting from the interaction between excited electrons and scattered electrons from nearby atoms. The radial distribution function obtained by the Fourier transform contains information about the local structure of the metal atom (surrounding atomic species, number of coordinating atoms, interatomic distances).

[0044] In the nanophosphate iron particles of the present invention, the presence of iron atoms in a low-valence state can also be confirmed from the X-ray Absorption Near Edge Structure (XANES).

[0045] Since the iron atoms contained in the nano-reduced iron particles of the present invention exist in a low valence state, in the XANES spectrum obtained by XANES measurement at the K absorption edge of Fe atoms, the rise of the peak is the same as that of the peak of the iron foil (Fe foil). In other words, the fact that the iron atoms constituting the nano-reduced iron particles of the present invention exist in a low valence state can be confirmed by the fact that in the XANES spectrum obtained by the above XANES measurement, the rise of the peak is the same as that of the peak of the iron foil (Fe foil). The iron foil (Fe foil) is zero-valent Fe as a metal. In one embodiment, in the XANES spectrum obtained by XANES measurement at the K absorption edge of Fe atoms, the ratio of (spectral intensity of nano-Fe x P at 7110 eV) / (spectral intensity of Fe foil at 7110 eV) is 0.910 to 1.000, and examples thereof include a deoxidation catalyst containing nano-reduced iron particles and a composite. "eV" represents the energy of the incident X-ray. The method for measuring the XANES spectrum can be, for example, as described in International Publication No. 2023-200015, using the Si(111) monochromator of Spring-8 at the large synchrotron radiation facility "Spring-8" (beamlines BL01B1, BL14B2, 1 Koto 1, Koto, Sayo-gun, Hyogo 679-5198), and performing the measurement by the transmission method at room temperature. The measurement time can be set, for example, to 120 sec for Fe foil and 600 sec for nano-Fe x P.

[0046] In the nano-reduced iron particles and the composite of the above-described embodiment, at two points of the spectral intensity at 7110 eV and the spectral intensity at 7111 eV, the ratio of (spectral intensity of nano-Fe nano-Fe x P) / (spectral intensity of Fe foil) is preferably 0.930 to 1.000, more preferably 0.950 to 1.000, and even more preferably 0.970 to 1.000. At the above two points, nano-Fe xThe fact that the ratio of the spectral intensity of P to that of Fe foil is almost the same means that the peak rise times for nano-ferric phosphide particles and Fe foil are the same. The fact that the peak rise times for nano-ferric phosphide particles and Fe foil are the same means that the nano-ferric phosphide particles are in a low-valence state.

[0047] When measured by XPS, the XPS results indicate that at least the surface of the nano-ferrous phosphide particles can maintain a low valence state. If the XANES measurement results match the XPS measurement results, it can be said that the two measurement results support each other, and that the iron atoms contained in the nano-ferrous phosphide particles can maintain a low valence state not only on the surface but also throughout the entire particle, including the interior.

[0048] For XANES measurements of the K absorption edge of Fe atoms, known measuring devices (for example, X-ray absorption spectrometers (device names "QuantumLeapH2000" (for measurements under air), "QuantumLeaV210" (for measurements under vacuum), both manufactured by Canon Inc.)) or known measuring facilities (large synchrotron radiation facility "SPring-8"; beamlines BL01B1, BL14B2, 1-1 Koto, Sayo-cho, Sayo-gun, Hyogo Prefecture 679-5198) can be used.

[0049] In the Fe2p spectrum obtained from XPS, low-valence Fe atoms have a peak in the range of 706.7–707.0 eV. This is shown in Appendix B. Chemical States Tables for Fe 2p in Handbook of X-ray Photoelectron Spectroscopy: A Reference Book of Standard Spectra for Identification and Interpretation of XPS Data (Eds.: J. Chastain), Published by Perkin-Elmer Corporation, Electronics Division, Eden Prairie, MN, 1992.

[0050] One embodiment involves Fe2p in X-ray photoelectron spectroscopy (XPS). 3 / 2 In the spectrum, the iron atoms contained in the nano-ferric phosphide particles have a peak in the range of 706.0 to 707.5 eV, and in the XANES spectrum obtained by XANES measurement of the K absorption edge of the Fe atom, (nano-Fe x An example of a deoxygenation catalyst is one which contains nano-iron phosphide particles in which the value (ratio) of (spectral intensity of P at 7110 eV) / (spectral intensity of Fe foil at 7110 eV) is 0.910 to 1.000. The ratio of spectral intensities of the XANES spectrum is preferably 0.930 to 1.000, more preferably 0.950 to 1.000, and even more preferably 0.970 to 1.000. Furthermore, in the nano-iron phosphide particles of the above embodiment, at two points, the spectral intensities of 7110 eV and 7111 eV, (nano-Fe x The ratio of (spectral intensity of P) / (spectral intensity of Fe foil) is preferably 0.930 to 1.000, more preferably 0.950 to 1.000, and even more preferably 0.970 to 1.000.

[0051] In the nano-iron phosphide particles of the present invention, the ratio of phosphorus atoms to iron atoms determined by scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectroscopy (EDX) compositional analysis is preferably P:Fe = 20%:80% to 80%:20%, more preferably 30%:70% to 70%:30%, and even more preferably 35%:65% to 65%:35%, as this is superior in terms of enhancing catalytic activity or atmospheric stability.

[0052] The ratio of phosphorus atoms to iron atoms in the nano-phosphated iron particles of the present invention can be adjusted by controlling the degree of iron phosphating. x In P, adjustments can be made, such as increasing the amount of compounds where x is 1, or increasing the amount of compounds where x is 2. In one embodiment, nano-Fe xIn P, x is 1 or 2. The nano-iron phosphide particles include at least one of FeP and Fe2P, and preferably both. In another embodiment, nano-Fe x In P, x is 1. In another embodiment, nano-Fe x At P, x is 2.

[0053] One way to adjust the degree of iron phosphating is to adjust the heating temperature in the manufacturing method of nano-phosphorus iron particles (for example, by increasing the heating temperature by 10°C or extending the reaction time by 1 hour), thereby adjusting the degree of phosphating, such as by promoting iron phosphating. Conversely, to suppress phosphating and limit the progression of phosphating, the ratio of phosphorus atoms to iron atoms can be adjusted by changing the heating temperature and other conditions (for example, by decreasing the heating temperature by 10°C or shortening the reaction time by 1 hour).

[0054] In the nano-phosphate iron particles of the present invention, the relative abundance of phosphorus atoms and iron atoms can be evaluated by elemental analysis (elemental mapping). Known energy-dispersive X-ray spectroscopy (EDX) can be used for elemental analysis (elemental mapping). Known measuring devices can be used for EDX. Commercially available measuring devices can include transmission electron microscopes equipped with Super-X energy-dispersive X-ray spectroscopy (EDX) detectors (single-atom analysis transmission electron microscope, trade name "Titan Cubed G2 60-300", acceleration voltage: 300 kV, manufactured by FEI (now Thermo Fisher Scientific (US))).

[0055] Furthermore, while EDX is a method for observing a single particle, it is also possible to observe multiple (large quantities of) nano-ferric phosphide particles as a whole, as can be seen under a microscope, and evaluate the relative abundance of phosphorus atoms to iron atoms. One such method is inductively coupled plasma emission spectroscopy (ICP-AES). Known measuring devices can be used for ICP-AES. Commercially available measuring devices (ICP emission spectrometers, product name "Optima 8300" (measurement method: multi-wavelength simultaneous multi-element analysis scanning photometric analysis, software: Winlab32), manufactured by PerkinElmer Co., Ltd., etc.) can be used.

[0056] In one embodiment, the ratio of phosphorus atoms to iron atoms obtained by ICP-AES is preferably P:Fe = 20%:80% to 80%:20%, more preferably 30%:70% to 70%:30% and even more preferably 35%:65% to 65%:35% because it is superior in terms of further enhancing catalytic activity or atmospheric stability.

[0057] In one embodiment, in the nano-iron phosphide particles of the present invention, the ratio of phosphorus atoms to iron atoms is in a range close to that of the ratio evaluated by ICP-AES (e.g., sequential type) and the ratio evaluated by EDX. The fact that the two values ​​are close means that there are no excess phosphorus atoms attached to the nano-iron phosphide particles.

[0058] The nano-iron phosphide particles used in the deoxygenation catalyst of the present invention not only exhibit excellent atmospheric stability but also maintain their structure even when heated, demonstrating excellent thermal stability. Maintaining the structure means maintaining a low-valence state. The nano-iron phosphide particles and composites of the present invention can be recovered after being used as a deoxygenation catalyst by heating. Therefore, the nano-iron phosphide particles and composites of the present invention exhibit excellent thermal stability.

[0059] The nano-ferric phosphide particles and composites used in the deoxygenation catalyst of the present invention can maintain their activity after use as a deoxygenation catalyst and are recoverable. The recovery method is not particularly limited, and known methods such as filtration can be used. Another embodiment of the present invention relates to a method for producing nano-ferric phosphide particles.

[0060] As one embodiment, the method for producing nano-phosphate iron particles of the present invention involves mixing a phosphorus compound, an iron compound that serves as an iron source (preferably an iron carbonyl compound), and a surfactant under heating, wherein the iron compound (preferably an iron carbonyl compound) is composed of Fe(CO)5 and Fe3(CO) 12 A manufacturing method is one in which at least one is selected from the group consisting of the following, and does not use 1-octadecene.

[0061] Conventional techniques include methods for producing nanometal particles using 1-octadecene as an essential component ("Triphenyl Phosphite as the Phosphorus Source for the Scalable and Cost-Effective Production of Transition Metal Phosphides", Chemistry of Materials, Junfeng Liu et al., 2018, 30, pp 1799-1807). However, the present inventors have confirmed that nanoiron particles obtained by the production method using 1-octadecene cannot be obtained in an amount that exhibits sufficient catalytic activity. Therefore, the method for producing nanoiron phosphide particles of the present invention does not use 1-octadecene.

[0062] By not using 1-octadecene, the resulting nano-ferric phosphide particles and composites containing them exhibit excellent catalytic activity and can be used as deoxygenation catalysts. The method for producing nano-ferric phosphide particles of the present invention does not require other additives such as 1-octadecene.

[0063] In the method for producing nano-ferrous phosphide particles of the present invention, a phosphorus ester compound is preferred as the phosphorus compound used as the phosphating agent.

[0064] Examples of phosphite ester compounds include triphenyl phosphite, diphenyl mono(2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, tritolyl phosphite (tri-o-tolyl phosphite, tri-m-tolyl phosphite, tri-p-tolyl phosphite), trixylyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, tris(2,6-dimethylphenyl) phosphite, tris(2-t-butylphenyl) phosphite, tris(2-t-butyl-5-methylphenyl) phosphite, trimethyl phosphite, triethyl phosphite, tripropyl phosphite, and triisopropyl phosphite. Aryl phosphates such as phenyl monodecyl phosphite, diphenyl mono(tridecyl) phosphite, tritlyl phosphite, trixylyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, tris(2,6-dimethylphenyl) phosphite, tris(2-t-butylphenyl) phosphite, and tris(2-t-butyl-5-methylphenyl) phosphite are preferred, triaryl phosphates such as triphenyl phosphite, tritlyl phosphite, trixylyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, tris(2,6-dimethylphenyl) phosphite, tris(2-t-butylphenyl) phosphite, and tris(2-t-butyl-5-methylphenyl) phosphite are more preferred, and triphenyl phosphite is even more preferred. The phosphorus compound may be used alone or in combination of two or more.

[0065] Examples of the surfactant include alkylamines. While the alkylamine is not particularly limited, examples include alkylamines having an alkyl group with 1 to 20 carbon atoms. Alkylamines may be used individually or in combination of two or more.

[0066] The alkyl group of the alkylamine may be linear, branched, or cyclic. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, tert-pentyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl (isohexyl), 1-ethylbutyl, 2-ethylbutyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,4-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, and 3,3-dimethylbutyl. Examples include ethylbutyl group, 1-ethyl-2-methylpropyl group, 1,1,2-trimethylpropyl group, n-heptyl group, 2-methylhexyl group, n-octyl group, isooctyl group, tert-octyl group, 2-ethylhexyl group, 3-methylheptyl group, n-nonyl group, isononyl group, 1-methyloctyl group, 2-ethylheptyl group, n-decyl group, 1-methylnonyl group, n-undecyl group, 1,1-dimethylnonyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-eicosyl group, n-cyclopentyl group, n-cyclopentylmethyl group, cyclohexyl group, and cyclohexylmethyl group.

[0067] The alkyl group may have substituents or may be unsubstituted. The number of substituents can be changed according to the number of carbon atoms in the alkyl group, and may be 1 to 10, 1 to 5, or 1 to 3. Examples of substituents include halogen atoms, cyano groups (nitrile groups), lower alkyl groups, halo-lower alkyl groups, hydroxy-lower alkyl groups, hydroxyl groups, halo-lower alkoxy groups, etc. One embodiment is a method for producing nano-ferric phosphide particles in which the surfactant is n-hexadecylamine.

[0068] The amount of surfactant used may be 0.05 to 20 equivalents (molar equivalents), 0.1 to 15 equivalents, or 0.5 to 13 equivalents relative to the amount of phosphorus compound used.

[0069] The mixing of the phosphorus compound, the iron compound (preferably an iron carbonyl compound), and the surfactant under heating (hereinafter also referred to as the "mixing step") is not particularly limited and can be carried out using known methods and apparatus.

[0070] In the method for producing nano-iron phosphide particles of the present invention, a phosphorus compound, an iron compound (preferably an iron carbonyl compound), and a surfactant are mixed under heating. The heating temperature in the mixing step is preferably 80 to 280°C, more preferably 90 to 250°C, and even more preferably 100 to 220°C. The heating temperature may also be less than 200°C or less than 180°C as milder conditions. For example, the heating temperature may be 90°C or higher and less than 180°C. The heating temperature can be appropriately changed depending on the desired degree of phosphating of the nano-iron phosphide particles.

[0071] In the manufacturing method of the present invention, iron carbonyl compounds are preferred as the iron compound. Examples of iron carbonyl compounds include Fe(CO)5 and Fe3(CO) 12 Preferably, Fe3(CO) 12 This is more preferable. The iron carbonyl compound can be produced by known methods. For example, Fe3(CO) 12 This can be obtained by known methods such as heating Fe2(CO)9 in an organic solvent. The heating apparatus and temperature can be any known method and are not particularly limited. As iron compounds other than iron carbonyl compounds, iron(II) acetate (Fe(CH3CO2)2) can be used. When using iron compounds other than iron carbonyl compounds, it is necessary to reduce the iron once. The reduction treatment as a pretreatment is not particularly limited and known methods can be used. The iron compound may be used alone or two or more in combination. As the iron compound, Fe3(CO) 12It is a solid, and unlike Fe(CO)5, it does not require injection by hot injection in the manufacturing method of nanoiron phosphide particles, making it easy to handle. Also, Fe3(CO) 12 Compared to Fe(CO)5, it is superior in terms of safety for the human body. Furthermore, in the method for producing nano-ferrous phosphide particles of the present invention, it is preferable not to use Fe(CO)5 as an iron carbonyl compound from the standpoint of safety for the human body, ease of availability, and the fact that Fe(CO)5 is a liquid at atmospheric pressure (1 atm), is highly volatile, and sublimes, requiring injection into the reaction system by hot injection, which presents handling problems.

[0072] The mixing step is preferably carried out under stirring, as this promotes the reaction and makes it easier to produce the nano-iron phosphide particles of the present invention. In one embodiment, the mixing step is preferably carried out under vacuum conditions or an argon atmosphere, as this makes it easier to produce the nano-iron phosphide particles of the present invention.

[0073] The reaction time in the mixing step is not particularly limited and can be appropriately changed depending on the desired degree of phosphating of the nanoiron phosphide particles. The reaction time is preferably 10 to 120 minutes, more preferably 15 to 90 minutes, and even more preferably 20 to 80 minutes.

[0074] Following the mixing step, the resulting mixture may be further heated (hereinafter also referred to as "heating step [2]"). Heating step [2] is preferably carried out under an argon atmosphere.

[0075] The heating temperature in the heating step [2] is not particularly limited as long as it is higher than the mixing step, but is preferably 90 to 380°C, more preferably 120 to 350°C, and even more preferably 180 to 330°C. The heating temperature in the heating step [2] can be appropriately changed depending on the desired degree of phosphating of the nano-iron phosphide particles. The heating temperature in the heating step [2] may be 5°C or more higher than that of the mixing step, or 10°C or more higher.

[0076] The heating rate when raising the temperature to the temperature of the heating step [2] after mixing the iron carbonyl compound is not particularly limited and can be appropriately changed depending on the desired degree of phosphating of the nano-phosphated iron particles. For example, the heating rate can be set low in order to allow the reaction to proceed slowly. The heating rate is preferably 5 to 150°C / min, more preferably 10 to 100°C / min, and even more preferably 15 to 90°C / min.

[0077] The reaction time in the heating step [2] is not particularly limited and can be appropriately changed depending on the desired degree of phosphating of the nano-iron phosphide particles. The reaction time is preferably 10 to 600 minutes, more preferably 15 to 540 minutes, and even more preferably 20 to 420 minutes.

[0078] The present invention's method for producing nano-iron phosphide particles preferably further includes a washing step. An organic solvent can be used as the washing solution in the washing step. The organic solvent is not particularly limited and is similar to the organic solvent used in the above-described method for producing the composite. One organic solvent may be used alone, or two or more may be used in combination. When two or more organic solvents are used in combination, the mixing ratio is not particularly limited, but for example, chloroform and acetone can be used in a volume ratio of 1:1. The washing step may involve using the organic solvent to centrifuge the product obtained after the heating step.

[0079] After the washing process, if necessary, the material may be vacuum-dried to obtain powdered nano-ferrous phosphide particles.

[0080] Another embodiment of the present invention relates to a deoxygenation catalyst comprising a composite comprising any of the above-described nano-iron phosphide particles and a carrier. Another embodiment is a deoxygenation catalyst comprising a composite in which the carrier contains TiO2, which has excellent catalytic activity as a deoxygenation catalyst.

[0081] The nano-ferric phosphide particles of the present invention exhibit excellent adsorption capacity, and therefore are not limited to specific carriers. When used as a composite in reduction reactions, they are effective as deoxygenation catalysts. The reason for their excellent adsorption capacity is not entirely clear, but it is thought that their nano-size and stability under atmospheric conditions may be contributing factors.

[0082] In the composite of the present invention, the iron atoms contained in the nano-phosphate iron particles are in a low-valence state, and the nano-phosphate iron particles are stable under atmospheric conditions. Therefore, unlike the conventional technology, where catalytically active iron particles must be synthesized on a support and used instantaneously immediately after synthesis, or where reduction pretreatment under high temperature and high pressure is essential for using the iron catalyst in a reduction reaction, the nano-phosphate iron particles of the present invention do not have these requirements. Thus, unlike the conventional technology, where the type of support was limited by the usage conditions of the iron particles as an iron catalyst, one of the advantageous effects of the present invention is that when the composite is used as a deoxygenation catalyst, the type of support used in combination with the nano-phosphate iron particles is not limited. In this way, the reason why the support must be limited is eliminated, and there is no special circumstance that catalytic activity cannot be obtained if the support is not limited, so the type of support is not limited in the composite of the present invention, and many types can be used. On the other hand, from the viewpoint of excellent catalytic activity, the support preferably contains TiO2, and in addition to TiO2, or in place of TiO2, other supports other than TiO2 (hereinafter also referred to as "other supports") can be used further. The reason why the catalytic activity is superior when the support contains TiO2 is thought to be as follows: When nano-iron phosphide particles are supported on TiO2, hydrogen molecules (H2) are activated on the particle surface, generating hydrogen atoms. These hydrogen atoms move from the surface of the nano-iron phosphide particles to the TiO2 (spillover), reducing a portion of the TiO2 and creating oxygen vacancies on the TiO2 surface. When a sulfoxide coordinates to these oxygen vacancies, the oxygen atoms of the sulfoxide are abstracted into the oxygen vacancies, generating sulfides, and the oxygen vacancies disappear. In other words, it is presumed that this reaction proceeds through the repeated formation of oxygen vacancies on the TiO2 surface and the deoxygenation reaction of sulfoxides by the oxygen vacancies. TiO2 is more easily reduced than other metal oxides, and the formation of oxygen vacancies occurs easily. It is presumed that this reducing property of TiO2 is the reason why the composite containing nano-iron phosphide particles and TiO2 exhibits superior catalytic activity compared to other supports.

[0083] In the composite of the present invention, the type of other carrier is not limited as long as it can be used as a support capable of supporting nano-iron phosphide particles. The other carrier is preferably liquid or solid at room temperature, and more preferably solid. In other embodiments, the other carrier may not have catalytic activity on its own. By using nano-iron phosphide particles together with a carrier containing TiO2, aggregation of the nano-iron phosphide particles can be effectively suppressed, and the composite can be recovered more easily. In particular, by combining nano-iron phosphide particles made of Fe2P with a carrier containing TiO2, the catalytic activity as a deoxygenation catalyst for sulfoxide compounds is further enhanced, and aggregation of nano-iron phosphide particles can be suppressed more effectively.

[0084] Examples of other carriers include at least one selected from the group consisting of polymers, chalcogen compounds, metal compounds, metals, and solid carbon materials. These other carriers may be used individually or in combination of two or more. Commercially available carriers may also be used.

[0085] The polymer may be either a natural polymer or a synthetic polymer. Examples of natural polymers include organic natural polymers such as natural rubber, protein, starch, and cellulose; and inorganic natural polymers such as quartz, mica, and feldspar. Examples of synthetic polymers include organic synthetic polymers such as polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, polyvinyl chloride, polyvinylpyrrolidone, polyethylene glycol (PEG), polypropylene glycol (PPG), polyethylene terephthalate (PET), polyester, polyethylene, polypropylene, polystyrene, polyurethane, polyethyleneimine, polyethersulfone, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polyvinylidene fluoride, polylactic acid, epoxy resins, fluororesins (PTFE (polytetrafluoroethylene), PFA, FEP, PCTFE, ETFE, ECTFE, etc.), nylon resins, polyamides, polyimides, and rubbers (silicone rubber, nitrile rubber, butyl rubber, butadiene rubber, etc.); and inorganic synthetic polymers such as glass and silica gel. The synthetic polymer may be a homopolymer composed of one type of monomer, or a copolymer composed of two or more types of monomers. The polymer may be a thermoplastic resin or a thermosetting resin. The weight-average molecular weight (Mw) of the polymer is not particularly limited and may be an oligomer or polymer of 1,000 to less than 10,000, a polymer of 10,000 to less than 1,000,000, or an ultra-high molecular weight polymer of 1,000,000 to 7,000,000. The weight-average molecular weight refers to the weight-average molecular weight in terms of polystyrene, determined by gel permeation chromatography (GPC).

[0086] A chalcogen compound refers to a compound containing a Group 16 element (oxygen, sulfur, selenium, tellurium, polonium, livermorium). The Group 16 element contained in the chalcogen compound may be a single element or two or more elements. The chalcogen compound is not particularly limited, and H2X 1 O4(X 1 = chalcogens excluding tellurium), H6TeO6, H2X 2 O3(X 2Examples include compounds having the structure of (= chalcogen) or salts thereof, compounds represented by MX3 (wherein M is Ti, Zr, Hf, V, Nb, Ta, Mo, or W, and X is S or Se), and metal chalcogenides represented by MPX3 (wherein M is Mg, V, Mn, Fe, Co, Ni, Zn, Cd, or In, and X is S or Se).

[0087] Examples of metal compounds are not particularly limited, but include oxides of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y, Si, Fe, Ti, Al, Mg, Co, Ni, Mn, Cr, Mo, W, V, Zn, and Sn, their solid solutions, and their composite oxides. Specifically, examples include SiO2, TiO2, and Al2O3. In this invention, metalloids of the periodic table such as "Si" are included in the definition of metal.

[0088] Examples of metals include Fe and metal alloys (such as stainless steel). The aforementioned metals can be used as metal carriers.

[0089] Examples of solid carbon materials include silicon carbide (SiC), activated carbon, graphite, diamond, fullerene, carbon nanotubes, graphene, and amorphous carbon.

[0090] The shape and size of the support can be changed depending on the form of use and are not particularly limited. For example, the support may be a sheet, film, or plate. The size of the support may be nanoscale, and may be 1 μm or larger, 1 mm or larger, or 1 cm or larger. The support may be, for example, a nanosheet (for example, with a thickness of about 1 nm to 100 nm).

[0091] The composite of the present invention contains iron atoms in a low-valence state, is stable under atmospheric conditions, and exhibits catalytic activity as a deoxygenation catalyst.

[0092] The composite of the present invention is not particularly limited and can be manufactured depending on the type of carrier. One embodiment is a method for manufacturing the composite in which nano-iron phosphide particles are placed or fixed on a carrier. The method for fixing the nano-iron phosphide particles on the carrier is not particularly limited and may be, for example, heat treatment or compression treatment. The heat treatment temperature may be, for example, 100°C or less. The carrier may be, for example, a solid carrier (e.g., in the form of a sheet) that is sufficiently larger than the nano-iron phosphide particles.

[0093] Because the nano-ferric phosphide particles of the present invention have excellent adsorption capacity, the method of supporting them on known carriers is not particularly limited and can be used. Another embodiment is a method for producing a composite, in which the nano-ferric phosphide particles are dispersed in an organic solvent, and the carrier is added to the organic solvent and stirred to obtain a composite. In any of the methods for producing the composite, there are no particular limitations, and for example, heat treatment may be performed. The heat treatment temperature may be, for example, 150°C or lower, or 120°C or lower.

[0094] The organic solvent used in the method for producing the composite is not particularly limited, and polar or non-polar organic solvents can be used. One organic solvent may be used alone, or two or more may be used in combination.

[0095] Organic solvents used in the method for producing the complex include, for example, non-aromatic hydrocarbon solvents (e.g., alkanes such as pentane, hexane, heptane, octane, nonane, decane, dodecane, isododecane, and tridecane; cycloalkanes such as cyclohexane and methylcyclohexane; decahydronaphthalene; and liquid paraffin); aromatic hydrocarbon solvents (e.g., benzene, toluene, xylene, diethylbenzene, mesitylene, tetralin, indene, naphthalene, and methylnaphthalene); halogenated hydrocarbon solvents (e.g., dichloromethane, dichloroethane, chloroform, and chlorobenzene); alcohol solvents (e.g., monohydric alcohols such as ethanol, propanol, 1-butanol, 2-butanol, 1-heptanol, 2-heptanol, 3-heptanol, 1-hexanol, 2-hexanol, benzyl alcohol, and oleyl alcohol; and polyhydric alcohols such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, and glycerin); Ether solvents (e.g., diethyl ether, diisopropyl ether, methyl t-butyl ether, diisoamyl ether), ethylene glycol derivatives (e.g., monoglime (ethylene glycol dimethyl ether), methyl cellosolve, diethyl cellosolve, diglime, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, triglime, tetraglime, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, ethylene glycol monobenzyl ether, ethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, poly(ethylene glycol) monomethyl ether), propylene glycol derivatives (e.g., 3-hexanolpropylene glycol monopropyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether), 1,1-dimethoxycyclohexane, phenethole, veratrol, dioxane, tetrahydrofuran); Ester solvents (e.g., ethyl acetate, butyl acetate, isopropyl acetate, 3-methoxy-3-methylbutyl acetate, dimethyl carbonate, diethyl malonate, ethylene carbonate, propylene carbonate, γ-butyrolactone, α-acetyl-γ-butyrolactone);Examples include ketone solvents (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, acetophenone, propiophenone, isophorone); sulfur-containing solvents (e.g., dimethyl sulfoxide, sulfolane, diphenyl sulfide); and nitrogen-containing solvents (e.g., amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylacrylamide, N,N-dimethylacetacetamide, N,N-diethylformamide, N,N-diethylacetamide, hexamethylphosphoramide, methylpyrrolidone, etc.; amine solvents such as triethanolamine; nitrile solvents such as acetonitrile and benzonitrile; nitro solvents such as nitrobenzene and o-nitrotoluene; quinoline, tetrahydroquinoline, dimethylimidazolidinone, etc.).

[0096] Another embodiment of the present invention relates to a reduction catalyst comprising any of the aforementioned nano-iron phosphide particles.

[0097] In one embodiment, the deoxygenation catalyst of the present invention comprises nanoiron phosphide particles and a carrier, wherein the nanoiron phosphide particles and the carrier (preferably a carrier containing TiO2) constitute a composite. Another embodiment is a deoxygenation catalyst comprising a composite, wherein the nanoiron phosphide particles are made of Fe2P and the carrier contains TiO2. The deoxygenation catalyst of the present invention may also consist of the composite.

[0098] The present invention will be described below using the deoxygenation catalyst in the production of sulfide compounds as an example. One embodiment is a deoxygenation catalyst containing any of the above-mentioned nano-ferric phosphide particles. Another embodiment is a deoxygenation catalyst containing any of the above-mentioned nano-ferric phosphide particles and a support, wherein the nano-ferric phosphide particles and the support constitute a composite.

[0099] One embodiment of this method involves deoxygenating a sulfoxide compound in a hydrogen atmosphere in the presence of the aforementioned composite deoxygenation catalyst to obtain a sulfide compound. The support in the composite is preferably a support containing TiO2, as it exhibits excellent catalytic activity.

[0100] Examples of the aforementioned sulfoxide compounds include sulfoxide compounds represented by the following general formula (1); sulfoxide compounds represented by the general formula (2), etc. 1 -SO-R 2 (1) (wherein, R 1 and R 2 R represents a hydrocarbon group which may have substituents, or a heterocyclic group which may have substituents and in which carbon atoms constituting the heterocycle are bonded to the sulfur atom shown in the formula, either identical or different. 1 and R 2 These atoms may bond to each other, forming a heterocycle that may be substituted, along with the sulfur atoms shown in the formula.

[0101] R 3 -SO-R 5 -S-R 4 (2) (wherein, R 3 and R 4 R 1 and R 2 It has the same meaning as R 5 (This represents a divalent hydrocarbon group which may have substituents.)

[0102] R 1 and R 2 Examples of hydrocarbon groups in this context include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and groups formed by the bonding of two or more of these groups.

[0103] Examples of the aliphatic hydrocarbon group include alkyl groups having 1 to 20 carbon atoms (preferably 1 to 10), such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-decyl, and n-dodecyl groups; alkenyl groups having 2 to 20 carbon atoms (preferably 2 to 10), such as vinyl, allyl, and 1-butenyl groups; and alkynyl groups having 2 to 20 carbon atoms (preferably 2 to 10), such as ethynyl and propynyl groups. The aliphatic hydrocarbon group may be linear or branched.

[0104] Examples of the alicyclic hydrocarbon group include cycloalkyl groups with 3 to 20 members (preferably 3 to 15 members, more preferably 5 to 8 members) such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, and cyclooctyl group; cycloalkenyl groups with 3 to 20 members (preferably 3 to 15 members, more preferably 5 to 8 members) such as cyclopentenyl group and cyclohexenyl group; perhydronaphthalene-1-yl group, norbornyl group, adamantyl group, and tetracyclo[4.4.0.1 2,5 1. 7,10 Examples include bridged cyclic hydrocarbon groups such as the dodecane-3-yl group.

[0105] Examples of aromatic hydrocarbon groups include aromatic hydrocarbon groups having about 6 to 14 carbon atoms (preferably 6 to 10), such as phenyl and naphthyl groups. In this specification, R 1 and R 2 If the hydrocarbon group in a given molecule has an aromatic ring, it is included in the category of aromatic hydrocarbon groups.

[0106] Hydrocarbon groups formed by the bonding of an aliphatic hydrocarbon group and an alicyclic hydrocarbon group include, for example, cycloalkyl-alkyl groups such as cyclopentylmethyl, cyclohexylmethyl, and 2-cyclohexylethyl (for example, C 3~12 Cycloalkyl-C 1~4 Examples include alkyl groups, etc.

[0107] A hydrocarbon group formed by the bonding of an aliphatic hydrocarbon group and an aromatic hydrocarbon group may have an aralkyl group (for example, C7~18 Aralkyl groups, alkyl-substituted aryl groups (for example, 1 to 4 carbon atoms) 1~4 (An alkyl-substituted phenyl group or naphthyl group, etc.), aryl-substituted C 2~10 Examples include alkenyl groups (for example, 2-phenylvinyl group).

[0108] R 1 and R 2 The hydrocarbon group in may have various substituents, such as halogen atoms, oxo groups, hydroxyl groups, substituted oxy groups (e.g., alkoxy groups having 1 to 6 carbon atoms, aryloxy groups having 6 to 14 carbon atoms, aralkyloxy groups having 7 to 15 carbon atoms, acyloxy groups, etc.), carboxyl groups, substituted oxycarbonyl groups (alkoxycarbonyl groups having 1 to 6 carbon atoms, aryloxycarbonyl groups having 6 to 14 carbon atoms, aralkyloxycarbonyl groups having 7 to 15 carbon atoms), cyano groups, nitro groups, acyl groups, substituted or unsubstituted amino groups (hydrocarbon group-substituted amino groups, acyl group-substituted amino groups, unsubstituted amino groups, etc.), sulfo groups, azo groups, azide groups, heterocyclic groups, etc. The hydroxyl group and carboxyl group may be protected with protecting groups commonly used in the field of organic synthesis. Furthermore, heterocyclic rings with aromatic or non-aromatic attributes may be fused to the rings of alicyclic hydrocarbon groups and aromatic hydrocarbon groups. Furthermore, the number of substituents can be appropriately selected depending on the structure of the compound; for example, it may be 1 to 6, 1 to 4, or 1 to 3.

[0109] R 1 and R 2 The heterocycles constituting the heterocyclic group in this include aromatic heterocycles and non-aromatic heterocycles. Examples of such heterocycles include heterocycles containing an oxygen atom as a heteroatom, heterocycles containing a sulfur atom as a heteroatom, heterocycles containing a nitrogen atom as a heteroatom, heterocycles containing both an oxygen atom and a sulfur atom as heteroatoms, heterocycles containing both an oxygen atom and a nitrogen atom as heteroatoms, and heterocycles containing both a sulfur atom and a nitrogen atom as heteroatoms.

[0110] Examples of heterocycles containing an oxygen atom as the heteroatom include five-membered rings such as furan, tetrahydrofuran, and γ-butyrolactone rings; six-membered rings such as 4-oxo-4H-pyran and tetrahydropyran; condensed rings such as benzofuran, isobenzofuran, 4-oxo-4H-chromene, chroman ring, and isochroman ring; and 3-oxatricyclo[4.3.1.1 4,8 ]Undecane-2-one ring, 3-oxatricyclo[4.2.1.0 4,8 Examples include bridge rings such as nonan-2-on rings.

[0111] Examples of heterocycles containing a sulfur atom as the heteroatom include five-membered rings such as thiophene rings; six-membered rings such as 4-oxo-4H-thiopyran rings; and fused rings such as benzothiophene rings.

[0112] Examples of heterocyclic rings containing a nitrogen atom as the heteroatom include five-membered rings such as pyrrole rings, pyrrolidine rings, pyrazole rings, imidazole rings, and triazole rings; six-membered rings such as pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, piperidine rings, and piperazine rings; and condensed rings such as indole rings, indoline rings, quinoline rings, isoquinoline rings, acridine rings, naphthyridine rings, quinazoline rings, and purine rings.

[0113] Examples of heterocycles containing oxygen and sulfur atoms as heteroatoms include five-membered rings such as oxathiolane rings; six-membered rings such as oxathiane rings; and fused rings such as benzoxathiane rings.

[0114] Examples of heterocycles containing oxygen and nitrogen atoms as heteroatoms include five-membered rings such as oxazoles and isoxazoles, and six-membered rings such as morpholine rings.

[0115] Examples of heterocyclic rings containing sulfur and nitrogen atoms as heteroatoms include five-membered rings such as thiazole rings, isothiazole rings, and thiadiazole rings.

[0116] In addition to substituents that the hydrocarbon group may have, the above heterocyclic group may also have alkyl groups (for example, methyl, ethyl, etc.). 1-4It may have substituents such as alkyl groups, cycloalkyl groups, and aryl groups (e.g., phenyl groups, naphthyl groups).

[0117] R 1 and R 2 These elements may bond to each other to form a heterocycle with the sulfur atom shown in formula (1). Examples of such heterocycles include 3 to 15-membered (particularly 5 to 8-membered) sulfur-containing non-aromatic heterocycles such as thiirane rings, thietan rings, thiolane rings, thiane rings, thiepane rings, and thiokane rings.

[0118] R 3 and R 4 R 1 and R 2 It is similar to that.

[0119] R 5 Examples of divalent hydrocarbon groups that may have substituents represented by include divalent aliphatic hydrocarbon groups, divalent alicyclic hydrocarbon groups, divalent aromatic hydrocarbon groups, and divalent groups formed by the bonding of two or more of these groups. 5 A substituent in the divalent hydrocarbon group represented by is R 1 and R 2 Examples include substituents similar to those of the hydrocarbon group in the above-mentioned example.

[0120] Examples of the divalent aliphatic hydrocarbon group include alkylene groups having 1 to 20 carbon atoms (preferably 1 to 10); alkenylene groups having 2 to 20 carbon atoms (preferably 2 to 10), such as vinylene, propynylene, butenylene, and pentenylene groups; and alkylylene groups having 2 to 20 carbon atoms (preferably 2 to 10), such as ethynylene, propynylene, butynylene, and pentynylene groups. The aliphatic hydrocarbon group may be linear or branched.

[0121] Examples of the divalent alicyclic hydrocarbon group include cycloalkylene groups with 3 to 20 members (preferably 3 to 15 members, more preferably 5 to 8 members), such as 1,2-cyclopentylene group, 1,3-cyclopentylene group, cyclopentylidene group, 1,2-cyclohexylene group, 1,3-cyclohexylene group, 1,4-cyclohexylene group, and cyclohexylidene group; cycloalkenylene groups with 3 to 20 members (preferably 3 to 15 members, more preferably 5 to 8 members), such as cyclopentenylene group and cyclohexenylene group; and bridged cyclic hydrocarbon groups such as norbornylene group and adamantylene group.

[0122] Examples of the divalent aromatic hydrocarbon group include aromatic hydrocarbon groups having 6 to 14 carbon atoms (preferably 6 to 10), such as o-,m-,p-phenylene groups and naphthylene groups (1,2-naphthylene, 1,3-naphthylene, 1,4-naphthylene, 1,5-naphthylene, 1,6-naphthylene, 1,7-naphthylene, and 1,8-naphthylene). In this specification, R 5 If the hydrocarbon group in a given molecule has an aromatic ring, it is included in the category of aromatic hydrocarbon groups.

[0123] The divalent hydrocarbon group formed by bonding a divalent aliphatic hydrocarbon group and a divalent alicyclic hydrocarbon group may include, for example, cycloalkylene-alkylene groups such as cyclopentylenemethylene group, cyclohexylenemethylene group, and 2-cyclohexyleneethylene group (for example, C 3~12 Cycloalkylene group - C 1~4 Examples include alkylene groups, etc.

[0124] The divalent hydrocarbon group formed by bonding the divalent aliphatic hydrocarbon group and the divalent aromatic hydrocarbon group may contain an aralkylene group (arylenealkylene group) (for example, C 7~18 Aralkylene groups, etc.), alkylene-substituted arylene groups (for example, 1 to 4 carbon atoms) 1~4 (Phenylene group or naphthylene group substituted with an alkylene group, etc.), arylene-substituted C 2~10 Examples include alkenyl groups (for example, 2-phenylvinyl group).

[0125] In the present invention, the sulfoxide compounds used as substrates include, for example, aliphatic sulfoxide compounds such as dimethyl sulfoxide, ethyl methyl sulfoxide, methyl propyl sulfoxide, dipropyl sulfoxide, dibutyl sulfoxide, dodecyl methyl sulfoxide, and dibutyl sulfoxide; diphenyl sulfoxide, methyl phenyl sulfoxide, methyl (4-methylphenyl) sulfoxide, 4-acetylphenyl (phenyl) sulfoxide, ethyl phenyl sulfoxide, phenyl vinyl sulfoxide, benzyl phenyl sulfoxide, dibenzyl sulfoxide, methoxycarbonyl methyl phenyl sulfoxide, cyanomethyl phenyl sulfoxide, (2-propynyl) phenyl sulfoxide, (4-acetylphenyl) methyl sulfoxide, and bis(4-methylphenyl) Examples include aromatic sulfoxide compounds such as phenyl sulfoxide, 4-methoxybenzylmethyl sulfoxide, 4-(acetyl)phenyl(methyl) sulfoxide, 2-bromophenyl(methyl) sulfoxide, 3-bromophenyl(methyl) sulfoxide, 4-bromophenyl(methyl) sulfoxide, 2,4,6-tribromophenyl(methyl) sulfoxide, methyl 4-methoxyphenyl sulfoxide, bis(4-chlorophenyl) sulfoxide, and sulindac (also known as (Z)-5-fluoro-2-methyl-1-[p-(methylsulfinyl)benzylidene]-1H-indene-3-acetic acid); heterocyclic sulfoxide compounds such as tetramethylene sulfoxide; and sulfoxide compounds containing a sulfinyl group and a sulfide group such as methyl(methylsulfinyl)methyl sulfide.

[0126] In the present invention, examples of sulfide compounds obtained as products include compounds having one sulfide group, compounds having two sulfide groups, and so on. Examples of compounds having one sulfide group include aliphatic sulfide compounds such as dimethyl sulfide, ethyl methyl sulfide, methyl propyl sulfide, dipropyl sulfide, dibutyl sulfide, dodecyl methyl sulfide, and dibutyl sulfide; diphenyl sulfide, methylphenyl sulfide (thioanisole), methyl (4-methylphenyl) sulfide (also known as 4-(methylthio)toluene), 4-acetylphenylphenyl sulfide, ethylphenyl sulfide, phenyl vinyl sulfide, benzylphenyl sulfide, dibenzyl sulfide, methoxycarbonylmethylphenyl sulfide, and cyanomethyl sulfide. Aromatic sulfide compounds having one or more benzene rings, such as phenyl sulfide, (2-propynyl)phenyl sulfide, (4-acetylphenyl)methyl sulfide, bis(4-methylphenyl) sulfide, methyl 4-methoxybenzyl sulfide, 4'-(methylthio)acetophenone (also known as 4-(acetyl)thioanisole), 2-bromothioanisole, 3-bromothioanisole, 4-bromothioanisole, 2,4,6-tribromothioanisole, 4-methoxythioanisole, bis(4-chlorophenyl) sulfide, and slindax sulfide; heterocyclic sulfide compounds such as tetrahydrothiophene. Compounds having two sulfide groups include methylenebis(methyl sulfide).

[0127] The amount of deoxygenation catalyst used is preferably 0.1 to 15 mol%, more preferably 0.15 to 12 mol%, and even more preferably 0.2 to 10 mol%, in terms of the amount of Fe, relative to 100 mol% of the sulfoxide compound, in order to have sufficient catalytic activity. Within this range, the deoxygenation reaction proceeds sufficiently. The deoxygenation catalyst of the present invention functions as a catalyst even in very small amounts and exhibits excellent catalytic activity.

[0128] The method for producing sulfide compounds is preferably carried out by heating. The heating temperature is not particularly limited, but is preferably 80 to 350°C, more preferably 90 to 280°C, and even more preferably 100 to 250°C. If the reaction is carried out under more moderate conditions, the temperature may be less than 200°C or less than 180°C. One embodiment is a method for producing sulfide compounds in which the sulfoxide compound is heated during the reaction, and the heating temperature is less than 200°C. Even if the heating temperature is less than 200°C, the catalytic activity of the deoxygenation catalyst is excellent, so sulfide compounds can be obtained with high production efficiency.

[0129] The reaction time is not particularly limited and may range from 5 minutes to 60 hours, 10 minutes to 30 hours, or 20 minutes to 15 hours. Depending on the purpose, it may also be set to 8 hours or less.

[0130] In the method for producing sulfide compounds, hydrogen molecules (hydrogen gas) are used as a reducing agent. Therefore, the method for producing sulfide compounds is carried out under a hydrogen atmosphere.

[0131] One embodiment of this method involves deoxygenating a sulfoxide compound in a hydrogen atmosphere at a hydrogen pressure of 8 MPa or less in order to produce a sulfide compound.

[0132] In the method for producing sulfide compounds, the hydrogen pressure is 8 MPa or less, but under milder conditions, it may be 5 MPa or less, 4.5 MPa or less, 3.0 MPa or less, or 2.9 MPa or less. The hydrogen pressure may also be, for example, 0.4 MPa or more, or 0.5 MPa or more. As long as the hydrogen pressure adjusted using hydrogen gas is within the above range, the deoxygenation reaction will proceed sufficiently.

[0133] In the manufacturing method of the present invention, the type of solvent can be selected according to the type of substrate, etc. On the other hand, one embodiment is a method for producing sulfide compounds in which a sulfoxide compound is reacted in the presence of a solvent.

[0134] As solvents, for example, those exemplified as organic solvents used in the method for producing the complex can be used, and alcohol solvents such as methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, and t-butanol are preferred; ketone solvents such as acetone and methyl ethyl ketone are preferred; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide are preferred; and ether solvents such as 1,2-dimethoxyethane and diethylene glycol dimethyl ether are preferred, with alcohol solvents being more preferred.

[0135] In a method for producing sulfide compounds, the deoxygenation reaction may be carried out in the presence of a base.

[0136] Examples of bases include, but are not limited to, organic bases ((a) tertiary amines, (b) nitrogen-containing aromatic heterocyclic compounds, (c) compounds having an imine skeleton (-C=N-C-) (in this specification, these compounds are also referred to as "imine bases")), (d) inorganic bases, and (e) tetraalkylammonium hydroxide. A single base may be used alone, or two or more bases may be used in combination.

[0137] (a) Examples of tertiary amines include trimethylamine, triethylamine, N-ethyldiisopropylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, trioctylamine, tridecylamine, triphenylamine, trimenzylamine, tris(2-ethylhexyl)amine, N,N-diisopropylethylamine, N,N-dimethyldecylamine, N-benzyldimethylamine, N-butyldimethylamine, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylethylenediamine, N,N-dimethylaniline, N,N-diethylaniline, 1,4-diazabicyclo[2.2.2]octane, N-methyl Examples include lupyrrolidine, N-methylpiperidine, N-methylmorpholine, N-ethylmorpholine, N,N'-dimethylpiperazine, N-methylpyrrolidone, N-vinylpyrrolidone, bis(2-dimethylaminoethyl) ether, N,N,N,N',N''-pentamethyldiethylenetriamine, triethanolamine, trippropanolamine, dimethylethanolamine, dimethylaminoethoxyethanol, N,N-dimethylaminopropylamine, N,N,N',N',N''-pentamethyldipropylenetriamine, tris(3-dimethylaminopropyl)amine, tetramethyliminobis(propylamine), and N-diethylethanolamine.

[0138] (b) Examples of nitrogen-containing aromatic heterocyclic compounds include pyridine, 2,4,6-trimethylpyridine, 4-dimethylaminopyridine, lutidine, pyrimidine, pyridazine, pyrazine, oxazole, isoxazole, thiazole, isothiazole, imidazole, 1,2-dimethylimidazole, 3-(dimethylamino)propylimidazole, pyrazole, furazan, quinoline, isoquinoline, purine, 1H-indazole, quinazoline, cinnoline, quinoxaline, phthalazine, Examples include pteridine, phenanthridine, 2,6-di-t-butylpyridine, 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridyl, 5,5'-dimethyl-2,2'-bipyridyl, 6,6'-t-butyl-2,2'-dipyridyl, 4,4'-diphenyl-2,2'-bipyridyl, 1,10-phenanthroline, 2,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, and 4,7-diphenyl-1,10-phenanthroline.

[0139] (c) Examples of imine bases include 1,8-diazabicyclo[5.4.0]undeca-7-ene (diazabicycloundecene), 1,5-diazabicyclo[4.3.0]non-5-ene, etc.

[0140] (d) Examples of inorganic bases include alkali metal or alkaline earth metal hydrides (sodium hydride, potassium hydride, lithium hydride, calcium hydride, etc.), alkali metal or alkaline earth metal hydroxides (sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, etc.), alkali metal or alkaline earth metal carbonates (sodium carbonate, potassium carbonate, lithium carbonate, calcium carbonate, etc.), alkali metal bicarbonates (sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, etc.), alkali metal or alkaline earth metal oxides (lithium oxide, sodium oxide, potassium oxide, Examples include calcium oxide, magnesium oxide), alkali metals, or alkaline earth metal halides (lithium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, magnesium fluoride, calcium fluoride, cesium chloride, etc.), alkali metal alkoxides (lithium methoxide, sodium methoxide, potassium methoxide, lithium ethoxide, sodium ethoxide, potassium ethoxide, lithium isopropoxide, sodium isopropoxide, potassium isopropoxide, lithium tert-butoxide, sodium tert-butoxide, and potassium tert-butoxide).

[0141] (e) Examples of tetraalkylammonium hydroxides include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, and tetra-n-butylammonium hydroxide.

[0142] The amount of base used is preferably 0.01 to 10 mol, more preferably 0.02 to 8 mol, and even more preferably 0.05 to 4 mol per mol of sulfoxide compound. Within these ranges, the deoxygenation reaction proceeds sufficiently.

[0143] When the compound represented by general formula (1) is used as the sulfoxide compound, a sulfide compound represented by general formula (3) below (a sulfide compound corresponding to the compound represented by general formula (1)) is obtained. 1 -S-R 2 (3) (wherein, R 1 and R2 (This has the same meaning as above.)

[0144] The present invention includes embodiments that combine the above configurations in various ways, within the scope of the technical idea of ​​the present invention, as long as they achieve the effects of the present invention.

[0145] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples, and many modifications can be made within the scope of the technical idea of ​​the present invention by those with ordinary skill in the art.

[0146] [Example 1: Nano-iron phosphate particles] <Example 1-1> Nano-iron phosphate particles were produced by the following method. First, 10 equivalents (molar equivalents) of triphenyl phosphite and 10 equivalents of hexadecylamine and Fe3(CO) were placed in a Schlenk tube. 12 The mixture was then stirred under vacuum conditions at 120°C for 30 minutes. Furthermore, the temperature was increased to 320°C at a rate of 50°C / min under an argon atmosphere, and the mixture was reacted at 320°C for 4 hours to obtain the mixed solution.

[0147] The mixture was cooled to room temperature, and the product was isolated as nano-ferrous phosphide particles by precipitation in acetone. The obtained nano-ferrous phosphide particles (nano-Fe2P) were evaluated by the following method.

[0148] <Electron Microscope Observation of Nano Iron Phosphate Particles> The nano iron phosphate particles obtained in Example 1-1 were observed using a field emission transmission electron microscope (product name "Tecnai® G2 20ST", acceleration voltage: 200 kV, manufactured by FEI (now Thermo Fisher Scientific (US))). The results are shown in Figure 1. From Figure 1, it was confirmed that nanoparticles were formed.

[0149] <Powder X-ray Diffraction Measurement of Nano Iron Phosphate Particles> The nano iron phosphate particles obtained in Example 1-1 were subjected to X-ray diffraction measurement under atmospheric conditions using a fully automated multi-purpose X-ray diffractometer (product name "Philips X'PERT MPD diffractometer", manufactured by Philips Japan, Ltd.) with CuKα rays (λ: 1.5418 Å). Approximately 40 mg of the sample was placed on a glass sample plate, and X-ray diffraction measurement was performed under the following conditions without any pretreatment. The results are shown in Figure 2. [Measurement Conditions] Tube voltage: 45 kV Tube current: 40 mA Measurement temperature: Room temperature Measurement angle range: 30.00 to 60.00° Sampling interval: 0.013° Scan rate: 0.42° / min

[0150] As shown in Figure 2, in powder X-ray diffraction measurements using CuKα radiation under oxygen-containing conditions, the intensity of the peak corresponding to the (111) plane of Fe2P (diffraction angle (2θ): 40.1°) was observed as the maximum intensity for the nano-iron phosphide particles obtained in Example 1-1. Therefore, it was confirmed that the nano-iron phosphide particles obtained in Example 1-1 are Fe2P.

[0151] [Example 2: Composite] <Example 2-1: Composite of nano-iron phosphide particles and TiO2> A composite was prepared using the nano-iron phosphide particles produced in Example 1-1 and TiO2 as a carrier. Specifically, the powder of nano-iron phosphide particles produced in Example 1-1 was dissolved in chloroform. TiO2 with an average particle size in the range of 0.01 μm to 1 μm was added to the solution so that the mass ratio of nano-iron phosphide particles:TiO2 = 1:25, and the mixture was stirred at 25°C for 12 hours to disperse the nano-iron phosphide particles and obtain a composite of nano-iron phosphide particles and TiO2. The average particle size of TiO2 can be calculated by laser diffraction scattering. Specifically, for example, it can be measured by volume using a laser diffraction particle size distribution analyzer (SALD-2300: manufactured by Shimadzu Corporation) with a 0.2% sodium hexametaphosphate aqueous solution as the dispersion medium.

[0152] <Example 2-2: Composite of Nano-Iron Phosphate Particles and ZrO2> A composite was prepared using the nano-iron phosphate particles produced in Example 1-1 and ZrO2 as a support. Specifically, the composite was prepared in the same manner as in Example 2-1, except that ZrO2 was used as the support instead of TiO2, including the average particle diameter of the support and the mass ratio of the support to the nano-iron phosphate particles. The method for measuring the average particle diameter of ZrO2 was the same as the method for measuring the average particle diameter of TiO2.

[0153] <Example 2-3: Composite of Nano-Phosphate Iron Particles and MgO> A composite was prepared using the nano-phosphate iron particles produced in Example 1-1 and MgO as a support. Specifically, the composite of nano-phosphate iron particles and MgO as a support was prepared in the same manner as in Example 2-1, except that MgO was used as the support instead of TiO2, including the average particle diameter of the support and the mass ratio of the support to the nano-phosphate iron particles. The method for measuring the average particle diameter of MgO was the same as the method for measuring the average particle diameter of TiO2.

[0154] <Example 2-4: Composite of Nano-Phosphate Iron Particles and Al2O3> A composite was prepared using the nano-phosphate iron particles produced in Example 1-1 and Al2O3 as a support. Specifically, the composite was prepared using nano-phosphate iron particles and Al2O3 as a support in the same manner as in Example 2-1, except that Al2O3 was used as the support instead of TiO2, including the average particle diameter of the support and the mass ratio of the support to the nano-phosphate iron particles. The method for measuring the average particle diameter of Al2O3 was the same as the method for measuring the average particle diameter of TiO2.

[0155] <Example 2-5: Composite of Nano-Iron Phosphate Particles and SiO2> A composite was prepared using the nano-iron phosphate particles produced in Example 1-1 and SiO2 as a support. Specifically, the composite was prepared in the same manner as in Example 2-1, including the average particle size of the support and the mass ratio of the support to the nano-iron phosphate particles, except that SiO2 was used as the support instead of TiO2. The method for measuring the average particle size of SiO2 was the same as the method for measuring the average particle size of TiO2.

[0156] [Example 3: Production of Diphenyl Sulfide] <Example 3-1> Diphenyl sulfide was produced by deoxygenating diphenyl sulfoxide using the nano-ferric phosphide particles of Example 1-1 as a catalyst. Specifically, 1.4 mg of nano-ferric phosphide particles of Example 1-1 (amount of Fe 0.019 mmol (3.8 mol%) of Fe relative to 100 mol% of diphenyl sulfoxide)), 3 ml of methanol, 0.5 mmol of diphenyl sulfoxide, and hydrogen gas were placed in an autoclave under pressure to H2 = 2.99 MPa, heated to 150°C, and the reaction was carried out for 1 hour. The results are shown in Table 1 below.

[0157] <Examples 3-2 to 3-7> Diphenyl sulfide was produced in the same manner as in Example 3-1, except that the type of catalyst used was changed to the composite produced in Examples 2-1 to 2-5, and the reaction conditions were changed as shown in Table 1 below. The results are shown in Table 1 below.

[0158] <Comparative Examples 3-1 to 3-2> Diphenyl sulfide was produced in the same manner as in Example 3-1, except that the type of catalyst used was changed as shown in Table 1 below. The results are shown in Table 1 below. The Fe / TiO2 used in Comparative Example 3-1 was produced by the following method. TiO2 (1 g) was added to a 10 mM Fe(NO3)3 aqueous solution (50 mL) to obtain iron nitrate Fe(NO3)3・9H2O (0.525 mmol), and the mixture was stirred at room temperature for 1 hour. After that, the water was removed by evaporation, and the obtained powder was dried overnight in an air atmosphere at 110°C. The dried powder was calcined in an air atmosphere at 500°C for 3 hours (heating rate to 500°C was 10°C / min). Fe / TiO2 was obtained by reducing the calcined powder at 800°C for 1 hour under a hydrogen flow (H2: 100 mL / min). The iron nitrate Fe(NO3)3·9H2O used was manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. The TiO2 used was JRC-TIO-17, a reference catalyst of the Catalysis Society of Japan. The bulk Fe2P used in Comparative Example 3-2 was a commercially available product (product name "Iron Phosphate (Fe2P)", Mitsuwa Chemical Co., Ltd.).

[0159]

[0160] As shown in Table 1, the nano-iron phosphide particles and composites of the present invention exhibited remarkably excellent catalytic activity as deoxygenation catalysts. Unlike conventional iron nanoparticles with shielded surfaces, the nano-iron phosphide particles of the present invention are thought to possess catalytic activity because they have atmospheric stability and can maintain a low valence state even on the particle surface. Furthermore, the ability to produce composites of nano-iron phosphide particles with various carriers (preferably TiO2) at 25°C, and the fact that these composites exhibited catalytic activity, confirmed that the nano-iron phosphide particles have excellent atmospheric stability.

[0161] [Example 4: Production of Sulfide Compounds] <Example 4-1> Using the composite (nano-Fe2P / TiO2) produced in Example 2-1 as a catalyst, sulfide compounds were produced by deoxygenating sulfoxide compounds. Specifically, 0.05 g of the composite (nano-Fe2P / TiO2) from Example 2-1 (amount of Fe 0.019 mmol (3.8 mol% of Fe relative to 100 mol% of diphenyl sulfoxide)), 3 ml of ethanol, 0.5 mmol of diphenyl sulfoxide, and hydrogen gas were placed in an autoclave under pressure to H2 = 2.99 MPa, heated to 150°C, and the reaction was carried out for 3 hours. The yield was >99%. Yield measurements were performed using gas chromatography (GC) with an internal standard using a gas chromatograph (gas chromatograph-mass spectrometer, product name "GCMS-QP2010 SE") manufactured by Shimadzu Corporation, equipped with a capillary column (product name "SH-Rtx-200MS", length: 30 m, inner diameter: 0.25 mm, film thickness: 0.25 μm).

[0162] <Examples 4-2 to 4-16> Sulfide compounds were produced in the same manner as in Example 4-1, except that the type of substrate compound used was changed to the sulfoxide compound listed in Table 2 below, the amount of the complex used in Example 2-1 was changed to 10 mol% Fe relative to 100 mol% diphenyl sulfoxide in Examples 4-7 and 4-16, the amount of the substrate compound used was changed to 0.25 mmol, ethanol was changed to 2-propanol, and the reaction time for each example was changed to the time indicated in parentheses for the product compound listed in Table 2. The method for measuring the yield was the same as in Example 4-1. The correspondence between the example number and the obtained sulfide compound (sulfide compound in Table 4) is shown in Table 3. The obtained sulfide compounds and their yields are shown in Table 4 below.

[0163]

[0164]

[0165] In addition, the high-performance liquid chromatograph (HPLC) used in the yield evaluation in Table 1 above was used for the deoxygenation reaction of diphenyl sulfoxide in Example 4-1, and the yield for the deoxygenation reaction of sulindac in Example 4-16 refers to the yield obtained by the isolation yield after concentrating and isolating the product by a known method.

[0166] From the above results, it was confirmed that the deoxygenation catalyst of the present invention, in particular as a deoxygenation catalyst for sulfoxide compounds, exhibits broad catalytic activity for many substrate compounds and also shows excellent substrate selectivity.

[0167] The nano-phosphate iron particles and composites of the present invention are useful as deoxygenation catalysts in deoxygenation reactions. In particular, they are useful as deoxygenation catalysts in the production of sulfide compounds.

Claims

1. A deoxygenation catalyst containing nano-iron phosphide particles.

2. The deoxygenation catalyst according to claim 1, wherein the nano-iron phosphide particles are rod-shaped particles, and the maximum length in the longitudinal direction of the rod-shaped particles is less than 100 nm.

3. The deoxygenation catalyst according to claim 1 or 2, which is a deoxygenation catalyst for sulfoxide compounds.

4. The deoxygenation catalyst according to claim 1 or 2, further comprising a carrier, comprising a composite composed of the nano-iron phosphide particles and the carrier, wherein the carrier is at least one selected from the group consisting of polymers, chalcogen compounds, metal compounds, metals and solid carbon materials.

5. The deoxygenation catalyst according to claim 4, wherein the carrier contains TiO2.

6. The deoxygenation catalyst according to claim 1 or 2, wherein the nano-iron phosphide particles are Fe2P.

7. A method for producing a sulfide compound, comprising deoxygenating a sulfoxide compound in a hydrogen atmosphere in the presence of the deoxygenation catalyst described in claim 1 or 2 to obtain a sulfide compound.

8. A method for producing a sulfide compound according to claim 7, wherein the sulfoxide compound is heated during the reaction.

9. The method for producing a sulfide compound according to claim 8, wherein the heating temperature is less than 200°C.

10. A method for producing a sulfide compound according to claim 7, wherein the reaction is carried out in the presence of a solvent.

Images