Hydrogenation catalyst, flow-type organic synthesis system using the same, and method for producing hydrogenated organic compounds

Abstract

To provide a technique that, in hydrogenating an aromatic halonitro compound, improves the yield of a halogenated aromatic amine as the target product without requiring a dehalogenation inhibitor, while suppressing the formation of a nitroso compound.SOLUTION: A hydrogenation catalyst to be used for hydrogenating an aromatic halonitro compound, comprises a carrier containing at least one of silica, titania and alumina and at least one metal that is supported on the carrier and selected from the group 10 elements of the periodic table.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hydrogenation catalyst used for the hydrogenation reaction of aromatic halonitro compounds, a flow-type organic synthesis system using the same, and a method for producing a hydrogenated organic compound.

Background Art

[0002] In the hydrogenation of adding hydrogen to the unsaturated bond of an aromatic halonitro compound, a dehalogenation reaction (release of halogen) easily occurs, so that the yield and quality of the target product, halogenated aromatic amine, are reduced.

[0003] Therefore, conventionally, as a technique for suppressing the dehalogenation reaction in the hydrogenation of an aromatic halonitro compound, for example, a method of performing hydrogen reduction of a halonitroaromatic compound in the presence of an acidic phosphorus compound is known (see Patent Document 1). Further, a method of performing hydrogen addition to an aromatic halonitro compound using an organic nitrogen base (alkylamines, alicyclic amines, or guanidine) is known (see Patent Document 2). Further, a method of producing halogenated anilines from halogenated nitrobenzenes by catalytic reduction in the coexistence of halogenated benzenes is known (see Patent Document 3). Further, a method of hydrogenating an aromatic halonitro compound with a hydrogenation catalyst in the presence of carbon dioxide is known (see Patent Document 4).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

[0005] When additives or gases (hereinafter referred to as dehalogenation inhibitors) are used to suppress the dehalogenation reaction, as in the prior art described in Patent Documents 1-4 above, a recovery process for the dehalogenation inhibitors is required, which complicates the manufacturing process of the product (target product), and there is also a risk of these being mixed into the product. Furthermore, in the prior art described in Patent Document 4 above, the burden of safety management in the manufacturing process that handles carbon dioxide and product quality control becomes significant.

[0006] Furthermore, in the hydrogenation of aromatic halonitro compounds (e.g., halonitrobenzene), nitroso compounds (e.g., nitrosobenzene), which are harmful to humans and aquatic organisms and can burn explosively, may be produced as by-products. Therefore, it is particularly important to suppress their formation.

[0007] This invention was devised in view of the problems of the prior art, and its main objective is to provide a hydrogenation catalyst that improves the yield of halogenated aromatic amines, the target product, without requiring a dehalogenation inhibitor, while suppressing the formation of nitroso compounds in the hydrogenation of aromatic halonitro compounds, as well as a flow-type organic synthesis system using the same and a method for producing hydrogenated organic compounds. [Means for solving the problem]

[0008] In a first aspect of the present invention, a hydrogenation catalyst used for the hydrogenation of aromatic halonitro compounds comprises a carrier containing at least one of silica, titania, and alumina, and at least one metal supported on the carrier and selected from Group 10 elements of the periodic table.

[0009] According to this method, in the hydrogenation of aromatic halonitro compounds, the formation of nitroso compounds can be suppressed, and the yield of the target halogenated aromatic amine can be improved without the need for a dehalogenation inhibitor.

[0010] In a second aspect of the present invention, the metal is palladium.

[0011] According to this method, in the hydrogenation of aromatic halonitro compounds, the formation of nitroso compounds can be effectively suppressed while effectively improving the yield of the target product, the halogenated aromatic amine.

[0012] In a third aspect of the present invention, the carrier is a composite carrier made of alumina and titania, and the composite carrier includes a substrate made of alumina coated with titania.

[0013] According to this method, in the hydrogenation of aromatic halonitro compounds, the formation of nitroso compounds can be effectively suppressed while effectively improving the yield of the target product, the halogenated aromatic amine.

[0014] In a fourth aspect of the present invention, the support containing titania is configured to contain titania with an anatase-type crystalline structure of 38% or more.

[0015] According to this, when using a hydrogenation catalyst with a support containing titania in the hydrogenation of aromatic halonitro compounds, the formation of nitroso compounds can be effectively suppressed while effectively improving the yield of the target product, the halogenated aromatic amine.

[0016] In a fifth aspect of the present invention, the support containing titania has a crystalline structure that does not include the rutile type.

[0017] According to this, when using a hydrogenation catalyst with a support containing titania in the hydrogenation of aromatic halonitro compounds, the formation of nitroso compounds can be more effectively suppressed while more effectively improving the yield of the target product, the halogenated aromatic amine.

[0018] In a sixth aspect of the present invention, the average pore diameter of the carrier containing the titania is set to be 78 times or less the longitudinal molecular length of the aromatic halonitro compound.

[0019] According to this, in the hydrogenation of the aromatic halonitro compound, it is possible to effectively suppress the formation of the nitroso compound and effectively improve the yield of the halogenated aromatic amine as the target product.

[0020] In a seventh aspect of the present invention, the average pore diameter of the carrier is set to be about 50 nm or less.

[0021] According to this, in the hydrogenation of the aromatic halonitro compound, it is possible to effectively suppress the formation of the nitroso compound and effectively improve the yield of the halogenated aromatic amine as the target product.

[0022] An eighth aspect of the present invention is solid a flow-type organic synthesis system that performs a gas-liquid-solid three-phase reaction using any one of the hydrogenation catalysts according to the first to seventh aspects as a catalyst, hydrogen as a gas raw material, and an aromatic halonitro compound as a liquid raw material.

[0023] According to this, compared with the batch method, more precise temperature control of the reaction becomes possible. Therefore, while suppressing the formation of the nitroso compound, it is possible to improve the yield of the halogenated aromatic amine as the target product without requiring a dehalogenation inhibitor. Further, there is an advantage that the step of recovering the hydrogenation catalyst after the reaction as in the batch method is unnecessary, and scale-up is easier compared with the batch method.

[0024] A ninth aspect of the present invention is a method for producing a hydrogenated organic compound, which hydrogenates the aromatic halonitro compound using any one of the hydrogenation catalysts according to the first to seventh aspects.

[0025] According to this method, in the hydrogenation of aromatic halonitro compounds, the formation of nitroso compounds can be suppressed, and the yield of the target halogenated aromatic amine can be improved without the need for a dehalogenation inhibitor. [Effects of the Invention]

[0026] Thus, according to the present invention, in the hydrogenation of aromatic halonitro compounds, it is possible to suppress the formation of nitroso compounds while improving the yield of the target halogenated aromatic amine without requiring a dehalogenation inhibitor. [Brief explanation of the drawing]

[0027] [Figure 1] Overall diagram of the flow-type organic synthesis system used for the hydrogenation of aromatic halonitro compounds according to this embodiment. [Figure 2] Graph showing the relationship between the conversion rate of 4-ClNB and the selectivity of the nitroso isomer in the hydrogenation reaction (Catalyst A, Catalyst C, Catalyst F, Catalyst G) [Figure 3] Graph showing the relationship between the conversion rate of 4-ClNB and the selectivity of 4-ClAN in the hydrogenation reaction (Catalyst A, Catalyst C, Catalyst F, Catalyst G) [Figure 4] Graph showing the relationship between the conversion rate of 4-ClNB and the selectivity of the nitroso isomer in the hydrogenation reaction (catalyst D) [Figure 5] Graph showing the relationship between the conversion rate of 4-ClNB and the selectivity of 4-ClAN in the hydrogenation reaction (Catalyst D) [Figure 6] Graph showing the X-ray diffraction pattern based on X-ray diffraction (XRD) (Catalyst D) [Figure 7] Graph showing the effect of the average pore size of the support on the action of catalysts using titania-containing supports (Catalyst C, Catalyst D, Catalyst E) [Figure 8] Graph showing the effect of the average pore size of the support on the action of catalysts using titania-containing supports (Catalyst C, Catalyst D, Catalyst E) [Figure 9] Graph showing the effect of the average pore size of the support on the action of a catalyst using a silica-containing support (Catalyst B) [Figure 10] Graph showing the effect of the average pore size of the support on the action of a catalyst using a silica-containing support (Catalyst B) [Modes for carrying out the invention]

[0028] Hereinafter, with reference to the drawings, a hydrogenation catalyst according to an embodiment, a flow-type organic synthesis system using the same, and a method for producing hydrogenated organic compounds will be described.

[0029] (Hydrogenation catalyst) The hydrogenation catalyst according to this embodiment has at least one metal selected from the Group 10 elements of the periodic table (hereinafter referred to as the catalyst metal) supported on a support containing at least one of silica (SiO2), titania (TiO2), and alumina (Al2O3).

[0030] This hydrogenation catalyst exhibits unique effects not found in conventional catalysts used for the hydrogenation of aromatic halonitro compounds, particularly when used in the hydrogenation of aromatic halonitro compounds. More specifically, in the hydrogenation of aromatic halonitro compounds, the hydrogenation catalyst can suppress the formation of nitroso by-products while improving the yield of the target product, halogenated aromatic amine (hydrogenated organic compound), without the need for a dehalogenation inhibitor.

[0031] As the catalytic metal, elements belonging to Group 10 of the periodic table, such as nickel (Ni), palladium (Pd), and platinum (Pt), can be used, but palladium is particularly preferred. For example, the palladium precursor is not particularly limited, and palladium compounds such as nitrates, sulfates, chlorides, and acetylacetone complexes can be used. The catalytic metal is dispersed and supported on the outer surface of the support or on the inner surface of the pores of the support.

[0032] The shape and size (average particle size, etc.) of the substrates such as silica, titania, and alumina contained in the support are not particularly limited, and various shapes and sizes can be used depending on the specifications of the reactor used in the hydrogenation reaction of aromatic halonitro compounds and the reaction conditions. Commercially available catalyst support substrates can be used as the substrate consisting of at least one of silica, titania, and alumina. Examples of commercially available silica for catalyst support include the CARiACT Q series manufactured by Fuji Silysia Chemical Co., Ltd. Examples of commercially available titania for catalyst support include the CS-300S-12 series and CS-950-12 series manufactured by Sakai Chemical Industry Co., Ltd. Examples of commercially available alumina for catalyst support include the NeoBead GB series manufactured by Mizusawa Chemical Industry Co., Ltd.

[0033] Furthermore, a porous inorganic oxide can also be used as a substrate consisting of at least one of silica, titania, and alumina, synthesized by pH swinging, in which a hydrosol or hydrogel of a hydrated metal oxide is alternately swung multiple times between its precipitation pH range and dissolution pH range.

[0034] Hydrated metal oxides are hydrated oxides of one or more metals selected from silicon (Si), titanium (Ti), and aluminum (Al). Examples of metal compounds used as raw materials for synthesizing hydrosols or hydrogels of hydrated metal oxides include salts such as chlorides, fluorides, bromides, iodides, nitrates, sulfates, carbonates, acetates, phosphates, borates, oxalates, fluorides, silicates, and iodates, as well as oxoates and alkoxides. These metal compounds can be used individually or as mixtures of two or more.

[0035] Examples of silicon compounds that can be used include colloidal silica (SiO2·XH2O), ultrafine particle anhydrous silica (SiO2), sodium silicate [Na2O·XSiO2·YH2O(X=1-4)], silicon tetrachloride (SiCl4), and silicate esters [Si(OCH3)4, Si(OC2H5)4].

[0036] Examples of titanium compounds include titanium tetrachloride (TiCl4), titanium sulfate [Ti2(SO4)3, Ti(SO4)2], titanium oxysulfate (TiOSO4), titanium trichloride (TiCl3), titanium bromide (TiBr4), titanium fluoride (TiF4, TiF3), titanium oxide (TiO2), orthotitanic acid (H4TiO4), metatitanic acid (H2TiO3), titanium methoxide [Ti(OCH3)4], titanium ethoxide [Ti(OC2H5)4], titanium propoxide [Ti(OC3H7)4], titanium isopropoxide {Ti[OCH(CH3)2]4}, titanium butoxide [Ti(OC4H9)4], and the like.

[0037] Examples of aluminum compounds include metallic aluminum (Al), aluminum chloride (AlCl3, AlCl3·6H2O), aluminum nitrate [Al(NO3)3·9H2O], aluminum sulfate [Al2(SO4)3, Al2(SO4)3·18H2O], polyaluminum chloride m ,

[0038] Cl 6-n ) m (1 < n < 5, m < 10)], ammonium alum [NH4Al(SO4)2·12H2O], sodium aluminate (NaAlO2), potassium aluminate (KAlO2), aluminum isopropoxide [Al[OCH(CH3)2]3], aluminum ethoxide [Al(OC2H5)3], aluminum-t-butoxide [Al[OC(CH3)3]3], aluminum hydroxide [Al(OH)3], and the like.

[0038] For details of the carrier synthesized by such pH swing and its manufacturing method, refer to, for example, the porous inorganic oxide and its manufacturing method disclosed in Japanese Patent No. 4119144. Regarding the disclosed content of the cited document, it shall form a part of this specification and detailed description thereof is omitted. According to the carrier synthesized by such pH swing, it is possible to control the pore diameter (average value and distribution) of the catalyst to a desired value by pH swing, and it is also possible to finely adjust the value of the pore diameter by adjusting the firing temperature during firing.

[0039] Furthermore, a composite support made of alumina and titania may be used as the support. The composite support includes a substrate made of alumina coated with titania. As for the shape of the composite support, for example, a skeletal structure can be adopted in which a large number of pores are formed by the three-dimensional entanglement of multiple needle-like or columnar bodies. Such a structure can increase the specific surface area (ratio of pore volume to pore diameter) of the hydrogenation catalyst and facilitate the control of the pore structure.

[0040] For details of such composite supports, please refer, for example, to the support and method for manufacturing the same disclosed in Japanese Patent No. 6456204. The disclosures of the referenced documents constitute part of this specification, and detailed explanations are omitted. This composite support makes it possible to realize a catalyst with excellent stability and suppression of side reactions using a relatively small amount of catalyst metal.

[0041] In a support containing titania, it is preferable that the crystalline phase (crystal structure) contains 38% or more of anatase-type titania. This effectively suppresses the formation of nitroso compounds while stably improving the yield of the target product, the halogenated aromatic amine. Furthermore, the support more preferably contains 96% or more of anatase-type titania as the crystalline phase, and even more preferably contains 100% anatase-type titania. The proportion of anatase-type titania in the crystalline phase can be changed by changing the calcination temperature of the support. In particular, in a support containing titania, it is preferable that the crystalline phase contains 38% or more anatase-type titania and does not contain rutile-type titania. The crystalline phase of the support can be confirmed by X-ray diffraction analysis using an X-ray diffractometer.

[0042] In a support containing at least one of silica and titania, the average pore diameter is preferably about 50 nm or less. This effectively suppresses the formation of nitroso compounds while stably improving the yield of the target product, the halogenated aromatic amine. In a support containing titania, the average pore diameter of the support is more preferably about 18 nm or less, and even more preferably about 7 nm or less.

[0043] Furthermore, in the case of a silica-containing support, the average pore diameter is preferably 75 times or less the longitudinal molecular length of the aromatic halonitro compound. This makes it possible to stably improve the yield of the target product, the halogenated aromatic amine, while effectively suppressing the formation of the nitroso compound. Furthermore, in the case of a titania-containing support, the average pore diameter is preferably 78 times or less the longitudinal molecular length of the aromatic halonitro compound. The average pore diameter of the titania-containing support is more preferably 28 times or less the longitudinal molecular length of the aromatic halonitro compound, and even more preferably 11 times or less.

[0044] The average pore size of the support material can be measured using a pore distribution analyzer (e.g., a mercury porosimeter). Furthermore, the longitudinal molecular length of the aromatic halonitro compound can be calculated using a quantum chemical calculation program.

[0045] For the production of a hydrogenation catalyst in which a catalytic metal is supported on a support as described above, the processes described in the aforementioned literature or known catalyst manufacturing processes (e.g., impregnation, drying, calcination, and reduction processes) can be appropriately adopted. Furthermore, the shape of the catalyst (or support) can be molded into any desired shape, such as spherical, cylindrical, or flat, depending on the intended use. The size (particle size, etc.) of the catalyst (or support) can also be appropriately set.

[0046] (Hydrogenation of aromatic halonitro compounds) Next, the hydrogenation reaction of aromatic halonitro compounds using the hydrogenation catalyst according to this embodiment will be described.

[0047] The hydrogenation of aromatic halonitro compounds is represented by the following general formula (1).

[0048] [ka]

[0049] In formula (1), X represents fluorine, chlorine, bromine, or iodine. R represents a hydrogen atom, a hydroxyl group, a carboxyl group, a sulfo group, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, an acyl group, an alloyl group, an alkoxy group, or an alkoxycarbonyl group.

[0050] In the following, the hydrogenation of aromatic halonitro compounds will be explained using the hydrogenation of 4-chloronitrobenzene as an example. In the hydrogenation of 4-chloronitrobenzene, as shown in the process of formula (2), hydrogen is added to 4-chloronitrobenzene as a starting material, and the target product 4-chloroaniline is produced via the intermediates 4-chloronitrosobenzene and 4-chlorophenylhydroxylamine. Finally, 4-chloroaniline is reduced to aniline. On the other hand, nitrobenzene can be produced by the dehalogenation of 4-chloronitrobenzene. By adding hydrogen to nitrobenzene, aniline is produced via the intermediates nitrosobenzene and hydroxylamine. However, in the hydrogenation reaction in this embodiment, only 4-chloronitrosobenzene was detected as an intermediate, and the detection of nitrosobenzene was negligible.

[0051] [ka]

[0052] The hydrogenation of 4-chloronitrobenzene can be carried out by batch, semi-batch, or flow (continuous) methods, but the hydrogenation catalyst according to this embodiment is particularly suitable as a flow reaction catalyst used in a flow reaction system that performs a gas-liquid-solid three-phase reaction.

[0053] Next, with reference to Figure 1, an example configuration of flow-type organic synthesis system (hydrogenation reaction system) 1 will be described.

[0054] The flow-type organic synthesis system 1 is equipped with a flow-type fixed-bed reactor 2 (hereinafter referred to as reactor 2) that carries out a gas-liquid-solid three-phase reaction using hydrogen as a gaseous raw material, 4-chloronitrobenzene as a liquid raw material, and a hydrogenation catalyst as a solid catalyst. Organic solvents inert to the reaction (such as alcohols, ethers, and other aromatic hydrocarbons) can be used as the liquid raw material. However, if the aromatic halonitro compound is in liquid form, the reaction can also be carried out without a solvent.

[0055] Reactor 2 is a known tubular reactor containing a catalyst layer 3 that includes a hydrogenation catalyst. Reactor 2 reacts by flowing gaseous and liquid raw materials, which are continuously supplied from the inlet line L1, through the catalyst layer 3. Reactor 2 is also equipped with a tubular electric furnace 4 consisting of two independent blocks, and the reaction temperature (in this case, the temperature of the catalyst layer 3) can be adjusted by supplying heat as needed. As reactor 2, for example, not only a downflow reactor that flows the raw materials in the same direction as gravity, but also an upflow reactor that flows the raw materials in the opposite direction of gravity can be used.

[0056] The gaseous raw material is continuously supplied to reactor 2 via the gaseous raw material supply line L2, which is connected to the inlet line L1. Additionally, a purge gas supply line L3, through which purge gas flows, is connected to the inlet line L1. In the flow-type organic synthesis system 1, purging operations of equipment and piping within the system can be performed by supplying purge gas to the purge gas supply line L3 during maintenance or other purposes.

[0057] The liquid raw material is stored in the liquid raw material tank 11. The liquid raw material is supplied to the reactor 2 along with the gaseous raw material by the liquid raw material pump 12, via the liquid raw material supply line L4 to the inlet line L1. A preheater / precooler 13 is also provided in the liquid raw material supply line L4. The temperature of the liquid raw material supplied to the reactor 2 is adjusted to a preset target range by heating or cooling it with the preheater / precooler 13.

[0058] Furthermore, in reactor 2, the reaction products are continuously discharged from outlet line L6. A heat exchanger 21 is provided at outlet line L6. The temperature of the reaction products discharged from reactor 2 is adjusted to a preset target range by heating or cooling with the heat exchanger 21.

[0059] The reaction products cooled by the heat exchanger 21 are supplied to the main drum (gas-liquid separator) 25, which is connected downstream of the outlet line L6. In the main drum 25, the reaction products are separated into off-gas (residual gas) containing unreacted gaseous raw materials, etc., and recovered liquid containing the reaction product.

[0060] The off-gas (gas phase components) separated in the main drum 25 is discharged via the off-gas transport line (the first line of the residual gas transport line) L7.

[0061] The recovered liquid from the main drum 25 is supplied to the product recovery drum 41 via the recovered liquid transport line (target product recovery line) L9. In the product recovery drum 41, any gases remaining in the recovered liquid are separated from the recovered liquid into gas and liquid form. This separated gas is discharged to the outside via the separation gas discharge line L10. The recovered liquid (target product) separated in the product recovery drum 41 is recovered via the product recovery line L11.

[0062] In the flow-type organic synthesis system 1, the operator can identify and quantify the target product by sampling the recovered liquid from the product recovery line L11 at predetermined timings and analyzing it using a liquid chromatograph or gas chromatograph. [Examples]

[0063] In a flow-type organic synthesis system 1 (see Figure 1), experiments were conducted to produce 4-chloroaniline (hereinafter referred to as 4-ClAN) as the target product by hydrogenating 4-chloronitrobenzene (hereinafter referred to as 4-ClNB) using the following catalysts A and G as hydrogenation catalysts. In this embodiment, a commercially available Pd / C (palladium-carbon) catalyst with a metal load of 5% (5% Palladium on Activated Carbon, Degussa type E 106 R / W 5%Pd (wetted with ca.55% water) manufactured by Wako Pure Chemical Industries, Ltd.) was used as a catalyst for comparison with the hydrogenation catalyst (hereinafter referred to as the Pd / C catalyst).

[0064] (Catalyst A) 5 g of commercially available silica gel for catalyst support (CARiACT Q-10, manufactured by Fuji Silysia Chemical Co., Ltd.) was calcined at 500°C for 3 hours, and this was impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] so that the Pd load was 2.0%. After drying, it was calcined at 500°C for 3 hours to obtain catalyst A (Pd-supported silica catalyst).

[0065] (Catalyst B) 5 g of commercially available silica gel for catalyst support (CARiACT Q-50, manufactured by Fuji Silysia Chemical Co., Ltd.) was calcined at 500°C for 3 hours, and this was impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] so that the Pd load was 2.0%. After drying, it was calcined at 500°C for 3 hours to obtain catalyst B (Pd-supported silica catalyst).

[0066] (Catalyst C) 5 g of a titania carrier prepared by pH swing was calcined at 500°C for 3 hours, and this was impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] to achieve a Pd load of 2.0%. After drying, it was calcined at 500°C for 3 hours to obtain catalyst C (Pd-supported titania catalyst). The titania carrier prepared by pH swing was manufactured by a known method similar to the method for producing a titania carrier disclosed in Japanese Patent No. 5599212 (see

[0123] ).

[0067] (Catalyst D) 5g of commercially available titania for catalyst support (CS-300S-12, manufactured by Sakai Chemical Industry Co., Ltd.) was weighed after being calcined at 500°C for 3 hours. This was then impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] to achieve a Pd load of 2.0%, dried, and then calcined at 500°C for 3 hours to obtain catalyst D (Pd-supported titania catalyst). Note that catalyst D includes catalysts using supports calcined not only at 500°C but also at other temperatures (600°C, 700°C, 800°C, 900°C, and 950°C).

[0068] (Catalyst E) 5 g of commercially available titania for catalyst support (CS-950-12, manufactured by Sakai Chemical Industry Co., Ltd.) was weighed after being calcined at 500°C for 3 hours. This was then impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] to achieve a Pd load of 2.0%, dried, and then calcined at 500°C for 3 hours to obtain catalyst E (Pd-supported titania catalyst).

[0069] (Catalyst F) 5 g of an alumina support prepared by pH swing was calcined at 500°C for 3 hours, and this was impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] to achieve a Pd load of 2.0%. After drying, it was calcined at 500°C for 3 hours to obtain catalyst F (Pd-supported alumina catalyst). The alumina support prepared by pH swing was manufactured by a known method similar to the method for manufacturing alumina support disclosed in Japanese Patent No. 5599212 (see AS-2).

[0070] (Catalyst G) 5 g of a titania-coated alumina support (HBT) prepared by pH swing was calcined at 500°C for 3 hours, and this was impregnated with a 0.42% palladium nitrate aqueous solution [Pd(NO3)aq] to achieve a Pd load of 2.0%. After drying, it was calcined at 500°C for 3 hours to obtain catalyst G (Pd-supported titania-coated alumina catalyst). The titania-coated alumina support (HBT) prepared by pH swing was manufactured by a known method similar to the method for manufacturing a titania-coated alumina support disclosed in Japanese Patent No. 5599212 (see AT-2).

[0071] In the hydrogenation reaction of 4-chloronitrobenzene using the flow-type organic synthesis system 1, 1.0 g of hydrogenation catalyst was packed into the stainless steel reaction tube in reactor 2, and the catalyst layer 3 was positioned so that its center was located on the second stage (upper) of the tubular electric furnace 4, which consisted of two independent blocks. The catalyst layer 3 was then heated to a central temperature of 40°C. Subsequently, the liquid raw material 4-ClNB / TOL-IPA (toluene, isopropyl alcohol solvent) was added at a flow rate of 0.2 ml / min using the liquid raw material pump 12, and the gaseous raw material hydrogen was added at a rate of 20 cm³. 3 Each reaction tube was supplied with a flow rate of / min. As the hydrogenation reaction (reduction reaction) of the liquid raw material began, the temperature of the hydrogenation catalyst rose due to the heat generated. Therefore, during the reaction, the temperature of each block in the electric furnace 4 was adjusted to control the temperature of the center of the catalyst layer 3 to 40°C. The reaction products were cooled and recovered, and analyzed by gas chromatography. The flow rate of the effluent gas after cooling was measured using a mass flow meter. From the results of the analysis and measurements, the conversion rate of 4-ClNB, the selectivity of 4-ClAN (the target product), and the selectivity of 4-chloronitrosobenzene (the nitroso form) were calculated. Such experiments on the hydrogenation reaction of 4-chloronitrobenzene were conducted for each hydrogenation catalyst (catalyst AG) and Pd / C catalyst.

[0072] Figure 2 is a graph showing the relationship between the conversion rate of the liquid raw material 4-ClNB and the selectivity of the nitroso isomer (in this case, 4-chloronitrosobenzene) in the hydrogenation reaction for catalysts A, C, F, G, and the Pd / C catalyst (comparative catalyst). Figure 3 is a graph showing the relationship between the conversion rate of the liquid raw material 4-ClNB and the selectivity of 4-ClAN in the hydrogenation reaction for the same catalysts as in Figure 2.

[0073] Figure 2 shows that the selectivity of nitroso compounds produced by catalysts A, C, F, and G is lower than that of nitroso compounds produced by Pd / C catalysts, provided that the conversion rate of 4-ClNB is similar. In particular, when catalyst C, which contains titania, is used, almost no nitroso compounds are produced.

[0074] Figure 3 shows that the selectivity of 4-ClNB by catalyst C is higher than that of 4-ClNB by the Pd / C catalyst, given similar conversion rates of 4-ClNB. Furthermore, while the selectivity of 4-ClAN by catalyst A is slightly lower than that of 4-ClAN by the Pd / C catalyst at some conversion rates of 4-ClNB (approximately 80%), it can be confirmed that it is generally equivalent to or higher than that of 4-ClAN by the Pd / C catalyst.

[0075] Figures 4 and 5 are graphs showing the effect of the support calcination temperature (500°C, 600°C, 700°C, 800°C, 900°C, 950°C) on the action (reaction characteristics) of catalysts using a titania-containing support. Figure 4 shows the relationship between the conversion rate of 4-ClNB, a liquid raw material, and the selectivity of the nitroso isomer (in this case, 4-chloronitrosobenzene) in the hydrogenation reaction for catalyst D at each support calcination temperature. Figure 5 shows the relationship between the conversion rate of 4-ClNB, a liquid raw material, and the selectivity of 4-ClAN in the hydrogenation reaction for catalyst D at the same support calcination temperatures as in Figure 4.

[0076] In Figure 4, when the support calcination temperature for catalyst D is 500°C, 600°C, and 700°C, almost no nitroso formation is observed (the selectivity for nitroso is approximately zero). On the other hand, when the support is calcined at a higher temperature (800°C or higher), nitroso formation is confirmed. In particular, when the support calcination temperature is 900°C and 950°C (900°C or higher), nitroso formation becomes more pronounced, and the selectivity for nitroso by catalyst D is equivalent to or higher than that of nitroso by the Pd / C catalyst.

[0077] Figure 5 shows that, for all carrier calcination temperatures, the selectivity of 4-ClAN by catalyst D tends to be higher than the selectivity of 4-ClAN by the Pd / C catalyst.

[0078] Figure 6 is a graph showing the X-ray diffraction patterns based on XRD for the catalyst D support at the same support calcination temperatures as in Figures 4 and 5. A fully automated multi-purpose horizontal X-ray analyzer (SmartLab X-RAY DIFFRACTOMETER) manufactured by Rigaku Corporation was used as the X-ray diffractometer. Quantitative analysis in the X-ray diffraction method was performed using the RIR (Reference Intensity Ratio) method.

[0079] In the X-ray diffraction pattern shown in Figure 6, a peak corresponding to the {10¹} plane of the anatase-type crystalline phase, indicating the presence of titania (appearing around a diffraction angle of 2θ = 25.3° when using CuKα as the X-ray source), was detected. On the other hand, at the carrier calcination temperatures in which nitroso isomers were formed (800°C, 900°C, and 950°C), in addition to the anatase-type peak, a peak corresponding to the {110} plane of the rutile-type crystalline phase (appearing around a diffraction angle of 2θ = 27.4° when using CuKα as the X-ray source) was detected. At carrier calcination temperatures of 900°C and 950°C, where nitroso isomer formation was significant, the anatase-type peak became smaller, while the peak intensity due to the rutile-type was remarkably high. This indicates a correlation between the abundance of the rutile-type crystalline phase and the formation behavior of nitroso isomers. In other words, with catalysts containing titania, it is possible to suppress the formation of nitroso compounds by increasing the proportion of the anatase-type crystalline phase as the crystalline phase.

[0080] Table 1 shows the proportion of each crystalline phase (anatase type, rutile type) calculated using the RIR method from X-ray diffraction data for each support calcination temperature (500°C, 600°C, 700°C, 800°C, 900°C, 950°C) of catalyst D.

[0081] [Table 1]

[0082] Regarding catalyst D, considering the selectivity of 4-ClAN and nitroso isomers shown in Figures 4 and 5, respectively, and the proportion of the anatase-type crystalline phase shown in Table 1, it can be seen that when the proportion of the anatase-type crystalline phase in the titania-containing support is 38% or more, the formation of nitroso isomers is suppressed while the yield of 4-ClAN (target product) is improved compared to the Pd / C catalyst. By setting the calcination temperature of the titania-containing support to 900°C or lower, the proportion of the anatase type can be set to 38% or more.

[0083] Figures 7 and 8 are graphs showing the effect of the average pore size of the support on the action of catalysts using a titania-containing support. Figure 7 shows the relationship between the conversion rate of 4-ClNB, a liquid raw material, and the selectivity of the nitroso isomer (in this case, 4-chloronitrosobenzene) in the hydrogenation reaction for catalysts C, D, E, and the Pd / C catalyst (comparative catalyst). Figure 8 shows the relationship between the conversion rate of 4-ClNB, a liquid raw material, and the selectivity of 4-ClAN in the hydrogenation reaction for the same catalysts as in Figure 7.

[0084] Table 2 shows the average pore diameters of the supports used in catalysts C, D, and E. Each average pore diameter was measured using the mercury intrusion method. A Shimadzu Micromeristics Autopore IV9500 automatic mercury porosimeter was used as the pore distribution analyzer.

[0085] [Table 2]

[0086] Figure 7 shows that the selectivity of nitroso compounds produced by catalysts C, D, and E is lower than that produced by Pd / C catalysts, provided that the conversion rate of 4-ClNB is similar. In particular, when catalysts C and D, which have smaller average pore sizes, are used, almost no nitroso compounds are produced.

[0087] Figure 8 shows that the selectivity of 4-ClAN by catalysts C, D, and E tends to be higher than that of 4-ClAN by the Pd / C catalyst, provided that the conversion rate of 4-ClNB is similar.

[0088] Regarding catalysts C, D, and E using a titania-containing support, considering the selectivity of 4-ClAN and nitroso isomers shown in Figures 7 and 8, respectively, and the average pore size of the support shown in Table 2, it can be seen that when the average pore size of the titania-containing support is approximately 50 nm or less, the formation of nitroso isomers is suppressed while the yield of 4-ClAN (target product) is improved compared to the Pd / C catalyst. Furthermore, it can be seen that setting the average pore size to approximately 18 nm or less, as in catalysts C and D, is more preferable from the viewpoint of suppressing the formation of nitroso isomers and improving the yield of 4-ClAN (target product). Moreover, it can be seen that setting the average pore size to approximately 7 nm or less, as in catalyst C, is even more preferable from the viewpoint of suppressing the formation of nitroso isomers and improving the yield of 4-ClAN (target product). In addition, as shown in Table 2, it is preferable that the average pore size of the titania-containing support is 78 times or less the molecular length (substrate length) in the longitudinal direction of 4-ClNB. This effectively suppresses the formation of nitroso compounds while stably improving the yield of the target product, 4-ClAN. Furthermore, the average pore diameter of the titania-containing support is more preferably 28 times or less the substrate length, and even more preferably 11 times or less.

[0089] Figures 9 and 10 are graphs showing the effect of the average pore size of the support on the action of catalysts using silica-containing supports. Figure 9 shows the relationship between the conversion rate of 4-ClNB, a liquid raw material, and the selectivity of the nitroso isomer (in this case, 4-chloronitrosobenzene) in the hydrogenation reaction for catalyst B and the Pd / C catalyst (comparative catalyst). Figure 10 shows the relationship between the conversion rate of 4-ClNB, a liquid raw material, and the selectivity of 4-ClAN in the hydrogenation reaction for the same catalysts as in Figure 9.

[0090] Similar to Table 2 above, the average pore diameter of the support in catalyst B, measured by the mercury intrusion method, is 48.8 nm. Furthermore, the average pore diameter of the support in catalyst B is 75 times the longitudinal molecular length (substrate length) of 4-ClNB (average pore diameter / substrate length = 75). The longitudinal molecular length of 4-ClNB was calculated using the general-purpose quantum chemical calculation program Gaussian. Therefore, for silica-containing supports, it is desirable that the average pore diameter be 75 times or less the longitudinal molecular length (substrate length) of 4-ClNB.

[0091] Figure 9 shows that, when the conversion rate of 4-ClNB is similar, the selectivity of the nitroso compound by catalyst B tends to be lower than that of the nitroso compound by the Pd / C catalyst.

[0092] Figure 10 shows that the selectivity of 4-ClAN by catalyst B tends to be higher than that of 4-ClAN by the Pd / C catalyst, given that the conversion rate of 4-ClNB is similar.

[0093] Regarding catalyst B using a silica-containing support, considering the selectivity of 4-ClAN and nitroso isomers shown in Figures 9 and 10 above, respectively, and the average pore diameter of the support, when the average pore diameter of the silica-containing support is approximately 50 nm or less, it is possible to improve the yield of 4-ClAN (target product) while suppressing the formation of nitroso isomers, similar to the catalyst using a titanium-containing support described above, compared to the Pd / C catalyst. Furthermore, if the ratio of the average pore diameter of the support in catalyst B to the longitudinal molecular length (substrate length) of 4-ClNB is 75 or less, it is possible to improve the yield of 4-ClAN (target product) while suppressing the formation of nitroso isomers, compared to the Pd / C catalyst.

[0094] Although the present invention has been described above based on specific embodiments, these embodiments are merely illustrative, and the present invention is not limited to these embodiments. Not all of the components of the hydrogenation catalyst and the method for producing hydrogenated organic compounds using the same shown in the above embodiments are necessarily essential, and at least those skilled in the art can appropriately select and omit them as long as they do not deviate from the scope of the present invention. [Explanation of symbols]

[0095] 1: Flow-type organic synthesis system 2: Flow-through fixed-bed reactor 3: Catalyst layer 4: Electric furnace 11: Liquid raw material tank 12: Pumps for liquid raw materials 13: Preheater / Precooler 21:Heat exchanger 25: Main Drum 41: Product collection drum

Claims

1. A hydrogenation catalyst used for the hydrogenation of an aromatic halonitro compound in a flow reaction that carries out a gas-liquid-solid three-phase reaction, A carrier containing titania and having an average pore size of 50 nm or less, Palladium supported on the aforementioned carrier, Includes, A hydrogenation catalyst wherein the average pore diameter is 78 times or less the molecular length in the longitudinal direction of the aromatic halonitro compound.

2. The hydrogenation catalyst described in claim 1 as a solid catalyst, Hydrogen as a gas raw material, A flow-type organic synthesis system that performs a gas-liquid-solid three-phase reaction using aromatic halonitro compounds as liquid raw materials.

3. A method for producing a hydrogenated organic compound, comprising hydrogenating the aromatic halonitro compound using the hydrogenation catalyst described in claim 1.

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