JP6481998B2 - Supported catalyst - Google Patents

Description

  The present invention relates to a supported catalyst free of a polymer protective material.

  Conventionally, in a chemical reaction catalyst or a fuel cell, a heterogeneous catalyst in which nanoparticles are supported on a carbon-based carrier has been used. In addition, in the purification of boilers or exhaust gases, heterogeneous catalysts in which nanoparticles are supported on a ceramic carrier are used. Pd—Ru alloy nanoparticles are disclosed as nanoparticles used for heterogeneous catalysts (see, for example, Patent Document 1 and Non-Patent Document 1). In Non-Patent Document 1, when Pd—Ru alloy nanoparticles were supported on a carrier and used as a heterogeneous catalyst, the nanoparticles were synthesized and purified using a polymer protective material such as polyvinylpyrrolidone. Nanoparticles are supported on a carrier.

WO2014 / 045570

J. et al. Am. Chem. Soc. , 2014, 136 (5), pp1864-1871

  However, if the polymer protective material used in the synthesis of the nanoparticles remains in the catalyst, the effect of the catalyst may not be sufficiently exhibited. If the purification of the nanoparticles is repeated for the purpose of removing the polymer protective material, the yield of nanoparticles obtained decreases as the number of purification increases.

  An object of the present invention is to provide a supported catalyst that can sufficiently exhibit the effect of the catalyst without using a polymer protective material that lowers the performance of the catalyst.

The supported catalyst according to the present invention is a supported catalyst in which Pd—Ru alloy particles are supported as a nanoparticle on a support. The Pd—Ru alloy particles form a solid solution, and a high concentration is formed on the outer surface of the supported catalyst. It is characterized by the absence of molecular protective material. Since the Pd—Ru alloy particles form a solid solution, the catalytic activity can be further increased.

  The supported catalyst according to the present invention preferably contains no polymer protective material. The catalytic activity can be further increased.

  In the supported catalyst according to the present invention, it is preferable that the polymer protective material is not interposed between the nanoparticles and the support. The catalytic activity can be further increased.

  In the supported catalyst according to the present invention, the support includes one or both of carbon and ceramics.

  In the supported catalyst according to the present invention, the support is alumina, silica, silica alumina, calcia, magnesia, titania, ceria, zirconia, ceria zirconia, lantana, lantana alumina, tin oxide, tungsten oxide, aluminosilicate, aluminophosphate, Includes one or more forms selected from borosilicate, phosphotungstic acid, hydroxyapatite, hydrotalcite, perovskite, cordierite, mullite, silicon carbide, activated carbon, carbon black, acetylene black, carbon nanotube and carbon nanohorn To do.

  The present invention can provide a supported catalyst that can sufficiently exhibit the effect of the catalyst without using a polymer protective material that lowers the performance of the catalyst.

It is a TEM image of Example 1B. It is an XRD pattern of Example 1B. It is the temperature rising XRD pattern of Example 1B. It is a STEM image of Example 1B. It is an EDS mapping of Example 1B.

  Next, although an embodiment is shown and explained in detail about the present invention, the present invention is limited to these descriptions and is not interpreted. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

  In the supported catalyst according to the present embodiment, in the supported catalyst in which Pd—Ru alloy particles are supported on the support as nanoparticles, the polymer protective material does not exist on the outer surface of the supported catalyst. Since the polymer protective material is not present on the outer surface of the supported catalyst, the function of the catalyst can be sufficiently exerted. The polymer protective material is, for example, polyvinyl pyrrolidone (PVP). In the supported catalyst according to this embodiment, the polymer protective material is preferably not attached to the outer surface of the nanoparticle, and the polymer protective material is not attached to the outer surface of the nanoparticle and the outer surface of the support. Is more preferable.

  In the supported catalyst according to the present embodiment, it is preferable that no polymer protective material is interposed between the nanoparticles and the support.

  The supported catalyst according to this embodiment preferably does not contain a polymer protective material. Whether or not the supported catalyst contains a polymer protective material can be confirmed by, for example, an X-ray diffraction pattern (XRD pattern). For example, when the polymer protective material is PVP, the supported catalyst does not contain the polymer protective material because the PVP-derived pattern is not confirmed at around 10 ° in the XRD pattern measured at room temperature under the measurement condition of λ = CuKα. I can confirm that.

  The supported catalyst according to the present embodiment is not a method in which nanoparticles synthesized in advance are supported on a support as in the conventional method for producing a supported catalyst, but the synthesis of nanoparticles and the support of nanoparticles on the support are simultaneously performed. It is preferable to manufacture by the method to perform. By simultaneously performing the synthesis of the nanoparticles and the loading of the nanoparticles on the carrier, the number of manufacturing steps can be reduced as compared with the conventional manufacturing method. In this specification, a nanoparticle means the fine particle whose average particle diameter is 100 nm or less. The average particle diameter of the nanoparticles is a value calculated by measuring the particle diameter of at least 100 particles from a particle image obtained by a transmission electron microscope (TEM) and obtaining the average. The observation magnification of TEM is preferably 120,000 times or 150,000 times, for example. Although the minimum of the average particle diameter of a nanoparticle is not specifically limited, It is preferable that it is 1 nm or more.

  The method for producing a supported catalyst according to the present embodiment includes the step 1 of synthesizing Pd—Ru alloy particles and supporting the Pd—Ru alloy particles on the support, and the step 1 includes the support and the organic solvent. Step 1a for heating a mixture containing and not containing a polymer protective material, Step 1b for producing a mixture containing Pd compound, Ru compound and pure water and containing no polymer protective material, and step It is preferable to have the process 1c which mixes the mixture of 1a, and the mixture of the process 1b.

  Next, each substance used in step 1 will be described.

(Compound that is a raw material for the synthesis of nanoparticles)
The compound that is a raw material for synthesizing Pd—Ru alloy particles is a Ru compound and a Pd compound. The Ru compound is, for example, Ru chloride or Ru nitride. The Pd compound is, for example, Pd chloride or Pd nitride. Of these, the Ru compound and the Pd compound are preferably Ru chloride and Pd chloride. A supported catalyst can be obtained more efficiently. Ru chloride is, for example, ruthenium (III) chloride n hydrate, ruthenium (IV) chloride n hydrate, or sodium ruthenate. Pd chloride is, for example, potassium tetrachloropalladate (II) or dinitrodiammine palladium (II).

(Carrier)
The support includes a form that is one or both of carbon and ceramics. Ceramics include, for example, alumina, silica, silica alumina, calcia, magnesia, titania, ceria, zirconia, ceria zirconia, lantana, lantana alumina, tin oxide, tungsten oxide, aluminosilicate, aluminophosphate, borosilicate, phosphotungstic acid, hydroxy Apatite, hydrotalcite, perovskite, cordierite, mullite or silicon carbide. The carbon is, for example, activated carbon, carbon black, acetylene black, carbon nanotube, or carbon nanohorn. In this embodiment, only 1 type may be used from these support bodies, or 2 or more types may be used together. When two or more types are used in combination, two or more types from ceramics may be used in combination, two or more types from carbon may be used in combination, or one or more types from ceramics and one or more types from carbon may be used in combination. . More preferably, at least one selected from alumina, silica, titania, ceria, zirconia, activated carbon and carbon black is used.

(Organic solvent)
The organic solvent preferably has 2 or more carbon atoms and has reducibility. More preferably, the organic solvent has 4 or more carbon atoms. The upper limit of the carbon number of the organic solvent is not particularly limited, but is preferably liquid at normal temperature.

  The boiling point of the organic solvent is preferably 100 ° C. or higher. Excellent handleability. In addition, the supported catalyst can be obtained more safely. The boiling point of the organic solvent is more preferably 160 ° C. or higher. Although the upper limit of the boiling point of the organic solvent is not particularly limited, it is preferably 300 ° C. or lower, more preferably 290 ° C. or lower, from the viewpoint that the solvent can be more easily removed from the supported catalyst.

  Organic solvents are polyhydric alcohol, butanol, isobutanol, ethoxyethanol, dimethylformamide, xylene, N-methylpyrrolidinone, dichlorobenzene, toluene, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethyl lactate, Diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, dipropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol butyl methyl ether, tripropylene glycol dimethyl Ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, reethylene glycol monomethyl ether, diethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, polyethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and polyethylene glycol monomethyl ether It is preferable that it is 1 or more types. The supported catalyst can be obtained more safely and more efficiently. Of these, polyhydric alcohols are more preferred.

  The polyhydric alcohol is preferably at least one selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and butylene glycol. Of these, triethylene glycol is more preferable. The supported catalyst can be obtained more safely and more efficiently.

  Next, step 1 will be described.

  In step 1a, first, a mixture containing a carrier and an organic solvent and not containing a polymer protective material is prepared. In preparing the mixture, it is preferable that the support is suspended in an organic solvent and then dispersed using, for example, an ultrasonic disperser.

  The mixture is then heated. The heating method is not particularly limited, and is, for example, an external heating method such as an oil bath, a mantle heater, a block heater or a heat medium circulation jacket, or a microwave irradiation method. The heating temperature is preferably 100 to 300 ° C, and more preferably 180 to 230 ° C.

  In step 1b, a mixture containing a Pd compound, a Ru compound and pure water and containing no polymer protective material is prepared. The mixture may be a solution in which the Pd compound and the Ru compound are dissolved in pure water, or a dispersion in which the Pd compound and the Ru compound are dispersed in pure water. Among these, the mixture is more preferably a solution in which a Pd compound and a Ru compound are dissolved in pure water. The ratio of the Pd compound and the Ru compound is adjusted so that the atomic ratio of Ru and Pd is within a predetermined range in the obtained Pd—Ru alloy particles. It is particularly preferable that Ru: Pd is in the range of 0.1: 0.9 to 0.9: 0.1 in atomic ratio. The atomic ratio of the alloy can be measured by, for example, high frequency inductively coupled plasma emission spectrometry or atomic absorption spectrophotometry.

  In step 1c, the mixture of step 1a and the mixture of step 1b are mixed while maintaining the mixture of step 1a at the heating temperature described above. The mixing method is not particularly limited, but is preferably a method in which the mixture of step 1b is sprayed onto the mixture of step 1a. In step 1c, it is preferable to maintain the heated state after mixing the mixture of step 1a and the mixture of step 1b. The time for maintaining the heated state after mixing the entire amount of the mixed solution is preferably 5 to 60 minutes, and more preferably 10 to 30 minutes.

  The ratio between the total amount of the Ru compound and Pd compound and the amount of the support is adjusted so that the supported amount of the Pd—Ru alloy particles in the supported catalyst falls within a predetermined range. The supported amount of Pd—Ru alloy particles in the supported catalyst is preferably 0.001 to 60% by mass. Here, the supported amount is the ratio of the mass of the nanoparticles to the mass of the supported catalyst in the dry state, and can be measured by, for example, high frequency inductively coupled plasma emission spectrometry or atomic absorption spectrophotometry.

  In step 1, the Ru compound and the Pd compound are reduced by an organic solvent, and nucleation and grain growth of Pd—Ru alloy particles occur on the surface of the support. And the supported catalyst by which the Pd-Ru alloy particle was carry | supported by the support body is obtained. In the melting method, when the Ru content in the Pd—Ru alloy particles is 10 to 90 atomic%, a solid solution of the Pd—Ru alloy is not formed, but in this embodiment, a solid solution of the Pd—Ru alloy can be formed. Since the Pd—Ru alloy particles form a solid solution, the catalytic activity is further increased. More preferably, the Pd—Ru alloy particles form a solid solution single phase. The state of the Pd—Ru alloy particles can be confirmed by elemental mapping of energy dispersive X-ray fluorescence analysis (EDS) using scanning transmission electron microscopy (STEM), for example. The average particle diameter of the Pd—Ru alloy particles is preferably 30 nm or less, and more preferably 20 nm or less. The lower limit of the average particle diameter of the Pd—Ru alloy particles is not particularly limited, but is preferably 1 nm or more.

  After step 1c, the supported catalyst is preferably separated and purified from the solvent. The method for separating and purifying the supported catalyst is not particularly limited. For example, the method is a method of filtering, washing and drying a mixture having a lowered temperature.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited to the examples.

(Example 1B)
50 mL of pure water was charged into the flask. Ruthenium (III) chloride n hydrate (hereinafter RuCl ₃ · nH ₂ O) 0.1177 g and potassium tetrachloropalladate (II) (hereinafter K ₂ PdCl ₄ ) 0.1635 g were weighed and the pure An aqueous solution dissolved in water was prepared. No polymer protective material was added to the aqueous solution. Further, 1.15 g of activated carbon (FAM-50, manufactured by Nippon Enviro Chemicals) was weighed and added to 100 mL of triethylene glycol (hereinafter, TEG), and dispersed with ultrasonic waves to prepare a mixed solution. The polymer protective material was not added to the mixed solution. This mixed solution was heated to 205 ° C., and the aqueous solution was added in the form of a mist under the condition that the temperature of the mixed solution was maintained at 200 ° C. or higher. The whole amount of the aqueous solution was kept heated for 15 minutes after the addition was completed, and then cooled. The mixed liquid after cooling was filtered under reduced pressure, and the solid component (filtered material) was sufficiently washed with H ₂ O and ethanol and then dried under reduced pressure to obtain a supported catalyst.

(Example 2B)
50 mL of pure water was charged into the flask. An aqueous solution in which 0.0582 g of RuCl ₃ · nH ₂ O and 0.0779 g of K ₂ PdCl ₄ were weighed and dissolved in the pure water was prepared. No polymer protective material was added to the aqueous solution. Further, 0.959 g of activated carbon (FAM-50) was weighed and added to 100 mL of TEG, and dispersed by ultrasonic waves to prepare a mixed solution. The polymer protective material was not added to the mixed solution. This mixed solution was heated to 205 ° C., and the aqueous solution was added in the form of a mist under the condition that the temperature of the mixed solution was maintained at 200 ° C. or higher. The whole amount of the aqueous solution was kept heated for 15 minutes after the addition was completed, and then cooled. The solid component is settled from the cooled mixed solution using centrifugal separation, the supernatant is removed, the solid component is thoroughly washed with H ₂ O and ethanol, and then dried under reduced pressure, and the target Pd-Ru supported catalyst is obtained. Got.

(Example 3B)
50 mL of pure water was charged into the flask. An aqueous solution in which 0.3535 g of RuCl ₃ .nH ₂ O and 0.4917 g of K ₂ PdCl ₄ were weighed and dissolved in the pure water was prepared. No polymer protective material was added to the aqueous solution. In addition, 0.7023 g of Ketjen Black (EC300J, manufactured by Lion Corporation) was weighed and added to 100 mL of TEG, and dispersed with ultrasonic waves to prepare a mixed solution. The polymer protective material was not added to the mixed solution. This mixed solution was heated to 205 ° C., and the aqueous solution was added in the form of a mist under the condition that the temperature of the mixed solution was maintained at 200 ° C. or higher. The whole amount of the aqueous solution was kept heated for 15 minutes after the addition was completed, and then cooled. The solid component is settled from the cooled mixed solution using centrifugal separation, the supernatant is removed, the solid component is thoroughly washed with H ₂ O and ethanol, and then dried under reduced pressure, and the target Pd-Ru supported catalyst is obtained. Got.

(Average particle diameter of Pd—Ru alloy particles)
The supported catalyst of Example 1B was observed with a TEM at a magnification of 150,000 times, the particle diameter of 100 particles was measured from the obtained particle image, the average was obtained, and the TEM image of Example 1B is shown in FIG. The average particle size of Example 1B was 6.71 nm. Further, from FIG. 1, the presence of aggregated particles was not confirmed.

(Alloy state)
The supported catalyst of Example 1B was subjected to XRD measurement and elevated temperature XRD measurement. The XRD measurement condition is λ = CuKα at room temperature. The temperature rise XRD measurement conditions are room temperature, 100 ° C., 200 ° C., 300 ° C., 400 ° C., 500 ° C., and λ = 0.58Å. FIG. 2 shows the XRD pattern of Example 1B. FIG. 3 shows the temperature rise XRD pattern of Example 1B. It was confirmed from FIGS. 2 and 3 that Pd—Ru alloy nanoparticles were synthesized. Further, STEM measurement was performed on the supported catalyst of Example 1B. FIG. 4 shows an STEM image of Example 1B, and FIG. 5 shows an EDS mapping of Example 1B. From FIG. 4, it was confirmed that Pd—Ru alloy particles were formed on the support. Further, FIG. 5 shows that particles in which Pd and Ru are mixed at a mixing ratio exceeding the solid solution limit of Pd and Ru are formed, and that the Pd—Ru alloy forms a solid solution. Was confirmed. FIG. 5 shows an image in which element mapping is processed to gray gradation, but element mapping is more accurately expressed by a color image before processing in gray tone.

Claims (5)

In a supported catalyst in which Pd—Ru alloy particles are supported on a support as nanoparticles,
The Pd—Ru alloy particles form a solid solution,
A supported catalyst characterized in that no polymer protective material is present on the outer surface of the supported catalyst.   The supported catalyst according to claim 1, which does not contain a polymer protective material.   The supported catalyst according to claim 1 or 2, wherein the polymer protective material is not interposed between the nanoparticles and the support.   The supported catalyst according to claim 1, wherein the support is one or both of carbon and ceramics.   The carrier is alumina, silica, silica alumina, calcia, magnesia, titania, ceria, zirconia, ceria zirconia, lantana, lantana alumina, tin oxide, tungsten oxide, aluminosilicate, aluminophosphate, borosilicate, phosphotungstic acid, hydroxy 5. One or more kinds selected from apatite, hydrotalcite, perovskite, cordierite, mullite, silicon carbide, activated carbon, carbon black, acetylene black, carbon nanotube, and carbon nanohorn. The supported catalyst according to any one of the above.