JP2013123696A - Porous oxide coated particle, supported catalyst, and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supported catalyst high in activity and maintaining the activity for a long period of time even if used.SOLUTION: The supported catalyst with hydrophilic porous oxide coated particles supported on the surface of a carrier includes metallic core particles, and a porous oxide layer attached to at least part of the surface of the metallic core particles. A main component of the porous oxide layer is a silica-based oxide, and the average pore diameter of pores in the porous oxide layer is more than 0.2 nm and less than 8 nm.

Description

  The present invention relates to porous oxide-coated particles, supported catalysts, and methods for producing them.

Conventionally, various catalysts have been proposed as catalysts used for purifying exhaust gas in which metal particles are supported on a carrier. For example, a material obtained by supporting various metal particles called active metals (for example, Pt (platinum), Pd (palladium), Cu (copper), etc.) on a support material (for example, alumina, zeolite, etc.) has been proposed.
Various methods for producing metal particle-supported catalysts by supporting metal particles on a carrier have been proposed. For example, a carrier material is introduced into a solution in which a metal to be supported is dissolved, and metal particles are precipitated on the carrier material, or a carrier material is introduced into a metal particle dispersion in which colloidal minute particles are dispersed. And a method of supporting metal particles.

  For example, in Patent Document 1, in a method of depositing fine metal particles having catalytic activity on the surface of fine carrier particles made of metal oxide or the like, it matches the absorption band of at least one raw material for synthesizing the carrier. An absorption band of the raw material is simultaneously applied to the step of irradiating the raw material with light including a wavelength to precipitate the carrier particles, and the raw material for depositing the precipitated carrier particles and the metal particles having catalytic activity. A method for producing a catalyst, comprising: a step of irradiating light having a wavelength matching the above and depositing the metal particles on the surface of the carrier particles; and a step of selectively collecting the deposited metal particles. Have been described.

  In Patent Document 2, metal particles and / or metal compound particles are adsorbed on a solid support together with an organic polymer compound having a number average molecular weight of 3,000 to 300,000 that protects the particles substantially individually and separately. And / or metal particles characterized in that at least one of the polymer compound and the solid support does not have a functional group capable of forming a covalent bond and forming a chemical bond therebetween. Alternatively, a metal compound particle-supported composite is described. In addition, the production method includes a dispersion medium, metal particles and / or metal compound particles, and an organic polymer compound having a number average molecular weight of 3,000 to 300,000 having a protective colloid particle action. A colloidal particle dispersion comprising: a colloidal particle dispersed therein to form a colloidal particle; and the polymer is adsorbed on the particle to protect the particle substantially individually and separately as a protective colloidal particle; The colloidal particle dispersion is brought into contact with the solid support, and at least one of the polymer compound and the solid support does not have a functional group that can act to form a covalent bond and form a chemical bond therebetween, thus Metal particles characterized by forming a particle-supported complex formed by adsorbing the particles protected by the polymer compound to the solid support, and isolating the obtained complex from the dispersion medium, and /or Method for producing a metal compound particles carrying complexes have been described.

  In Patent Document 3, propargyl alcohol is added to a solution containing a carrier on which metal-containing ions and metal particles generated by reduction of the metal-containing ions are supported, and a reaction product of the metal-containing ions and propargyl alcohol is added to the carrier. After being supported on the substrate, the support is heat-treated in a reducing gas containing hydrogen gas to reduce a reaction product of metal-containing ions and propargyl alcohol on the support to metal-containing colloidal particles. A method for producing a highly dispersed metal-containing colloidal particle supported catalyst is described.

  In Patent Document 4, in the presence of a solid substance serving as a carrier, a liquid having a reducing ability containing a metal compound or ions or a liquid in which a reducing substance is dissolved is irradiated with microwaves, or a metal compound or A metal-containing colloidal particle is attached to the surface, characterized by having a solid substance serving as a carrier after a microwave is irradiated to a liquid containing a reducing ability or containing a reducing substance containing ions. In addition, a method for producing a metal-containing colloidal particle adhesion carrier is described.

  Patent Document 5 contains at least one second element of Group 2B, Group 3B, Group 4B, Group 5B, Group 6B, and Group 8 of the Period 4 to Period 6 of the periodic table and gold. A metal particle carrier in which metal particles are supported on a carrier by a deposition support method is described. In addition, as a production method thereof, a production method is described in which a carrier containing at least one of gold and its compound and at least one of a second element and its compound is heat-treated.

  When such conventional metal particle-supported catalysts continue to be used, the metal particles cause fusion, aggregation, and particle growth, and as a result, there are problems in that the catalytic activity is reduced and the life is shortened. Such a problem becomes particularly noticeable when used at high temperatures.

On the other hand, a catalyst for a polymer electrolyte fuel cell (PEFC) electrode has been proposed. Patent Document 6 describes surface-modified metal nanoparticles characterized by having a porous material made of an inorganic oxide on the surface of nanoparticles containing platinum group metals. Nanoparticles are remarkably suppressed from aggregating with each other, and their activity is sustained, and it is possible to produce a catalyst using them to provide a polymer electrolyte fuel cell having excellent properties. Has been.
Patent Document 6 describes that there is no particular limitation on the pore size as long as the fuel can be diffused to the surface of the metal nanoparticles, but the specific size is not described at all. Absent.
In Patent Document 6, there is no particular limitation on the porous film thickness as long as the metal nanoparticles can be prevented from coming into contact with each other. However, it is caused by diffusion of the fuel to the metal nanoparticle surface or an oxidation reaction. It is described that it is preferable to have a thickness that does not inhibit the conduction of electrons to the carrier, specifically, an ultrathin silica layer of approximately 0.5 to 2 nm is described, As an example, it is only described that the porous film thickness was about 1 nm.

Japanese Patent Laid-Open No. 61-268359 JP-A-5-293383 JP-A-6-31181 JP 2003-13105 A JP 2003-053188 A JP 2005-276688 A

  Judging from the fact that the surface-modified nanoparticles described in Patent Document 6 are described as described above, it is assumed that these surface-modified nanoparticles are also used as a catalyst for polymer electrolyte fuel cell electrodes. The thickness of the porous layer needs to be so thin that the fuel diffuses to the surface of the metal nanoparticles and the electrons conduct, and conversely, the porous layer is so thin. The pores of the porous layer are not considered essential.

  In addition, as described above, since there is no specific description of the size of the porous pore diameter in Patent Document 6, the present inventor has disclosed the metal fine particles as described in Example 1 of Patent Document 6. Surface-modified metal nanoparticles in which the surface of metal fine particles was covered with silica were produced by a method of treating the surface with aminosilane and then with water glass, and the silica layer was observed. As a result, it was confirmed that the pore diameter was remarkably small (generally 1 nm or less) even with respect to the pore which may be slightly present, with few pores. Moreover, when the catalytic activity of the obtained surface-modified metal nanoparticles was measured, it was confirmed that it was extremely low.

Thus, the porous layer in the surface-modified metal nanoparticles described in Patent Document 6 had almost no pores and low catalytic activity. On the other hand, even though the catalysts as described in Patent Documents 1 to 5 have high activity, they have a short life because aggregation occurs due to use.
Thus, conventionally, there has been no catalyst that has a high activity and has a long life and can maintain its activity for a long period of time.

An object of the present invention is to solve the above problems.
That is, an object of the present invention is to provide a supported catalyst that has high activity and maintains its activity for a long period of time even when used, porous oxide-coated particles that can constitute a part thereof, and a method for producing them.

The inventor has intensively studied to solve the above-mentioned problems, and has completed the present invention.
The present invention includes the following (1) to (12).
(1) having metal core particles and a porous oxide layer attached to at least a part of the surface thereof,
The main component of the porous oxide layer is a silica-based oxide,
The average pore diameter of the pores of the porous oxide layer is more than 0.2 nm and less than 8 nm,
Porous oxide-coated particles having hydrophilicity.
(2) The porous oxide-coated particle according to (1), wherein the average thickness of the porous oxide layer is more than 2 nm.
(3) The porous oxide-coated particle according to (1) or (2), wherein the pore volume is 0.01 to 0.5 ml / g.
(4) The porous oxide-coated particles according to any one of (1) to (3), wherein the specific surface area is 10 to 1000 m ² / g.
(5) The porous oxide layer includes an element group ω that is at least one selected from the group consisting of elements in the third period to the sixth period, and the total molar amount of silicon (Si) and the element group ω The porous oxidation according to any one of the above (1) to (4), wherein the molar ratio of the element group ω to the element group (element group ω / (element group ω + Si) × 100) is 0.05 to 10% Coated particles.
(6) Said (1)-(5) whose said metal core particle has as a main component at least 1 chosen from the group which consists of a 4th period transition element, a 5th period transition element, platinum, gold | metal | money, osmium, and iridium. The porous oxide-coated particles according to any one of 1).
(7) A supported catalyst in which the porous oxide-coated particles according to any one of (1) to (6) are supported on the surface of a support.
(8) a colloid adjusting step for obtaining a colloid solution in which the metal core particles are dispersed;
A solution [α] containing silicon and a solution [β] containing an alkali-soluble inorganic substance that is an inorganic substance soluble in alkali are prepared, and the solution [α] and the solution [β] are added to the colloidal solution adjusted to be alkaline. A dispersion (X) in which untreated core-shell particles coated with a shell layer containing at least a part of the surface of the metal core particles and containing a component derived from silicon and the alkali-soluble inorganic material are dispersed. An adding step to obtain;
At least a part of the shell layer is obtained by adding an acid or an alkali to the dispersion (X) to separate at least a part of the component derived from the alkali-soluble inorganic substance contained in the shell layer from the shell layer. A dispersion (Y) in which porous oxide-coated particles in which pores are formed on the surface and a porous oxide layer mainly composed of a silica-based oxide is provided on at least a part of the surface of the metal core particles are dispersed A method for producing porous oxide-coated particles, comprising a pore-forming step of obtaining
(9) The addition step includes
Ratio of molar amount in terms of oxide of component derived from alkali-soluble inorganic substance added to molar amount in terms of SiO _{2 of} silicon to be added (molar amount in terms of oxide of component derived from alkali-soluble inorganic substance) The solution [α] and the solution [β] are added to the colloidal solution adjusted to be alkaline so that (mol) / mol amount of silicon in terms of SiO ₂ (mol) is 0.25 or less. The method for producing porous oxide-coated particles according to (8) above, which is a step of obtaining the dispersion (X).
(10) The alkali-soluble inorganic substance is an alkali metal salt, alkaline earth metal salt or ammonium salt of an oxo acid containing at least one element selected from the group consisting of elements of the third to sixth periods. The method for producing porous oxide-coated particles according to (8) or (9) above.
(11) The method for producing porous oxide-coated particles according to any one of (8) to (10), wherein the porous oxide-coated particles according to any one of (1) to (6) are obtained. .
(12) A method for producing a supported catalyst, wherein the production method according to any one of (8) to (11) further comprises a step of supporting the porous oxide-coated particles on the surface of a support.

  According to the present invention, it is possible to provide a supported catalyst that has high activity and that maintains its activity for a long period of time, porous oxide-coated particles that can constitute a part thereof, and a method for producing them.

The present invention will be described.
The present invention has a metal core particle and a porous oxide layer attached to at least a part of the surface thereof, the main component of the porous oxide layer is a silica-based oxide, and the porous oxide layer The porous oxide-coated particles have an average pore diameter of more than 0.2 nm and less than 0.8 nm.
Hereinafter, such porous oxide-coated particles are also referred to as “coated particles of the present invention”.

The present invention is also a supported catalyst in which the coated particles of the present invention are supported on the surface of a carrier.
Hereinafter, such a supported catalyst is also referred to as “the supported catalyst of the present invention”.
The supported catalyst of the present invention includes, for example, an HC (hydrocarbon) decomposition system (for example, a three-way catalyst for exhaust gas purification of automobiles, decomposition of volatile organic compounds (VOC)), a high-concentration nitric acid decomposition system (for example, nitric acid) Nitrogen is reduced to generate nitrogen), which is suitable as a catalyst used in a hydrogenation reaction system.

<Metal core particles>
First, the metal core particles in the coated particles of the present invention will be described.
The metal core particle in the coated particle of the present invention is not particularly limited as long as it is a metal having catalytic ability. The fourth period transition element, the fifth period transition element, platinum (Pt), gold (Au), osmium (Os) and Preferably, the main component is at least one selected from the group consisting of iridium (Ir), and at least one selected from the group consisting of Pt, Pd, Rh, Ru, Os, Ir, Cu, Au, and Ag. More preferably, the main component is one.
Here, the fourth period transition element means Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The fifth period transition element means Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd and Ag.

  The “main component” here means that the content is 70% by mass or more. That is, the fourth periodic transition element (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu), the fifth periodic transition element (Y, Zr, Nb, Mo, Tc, Ru, Rh) in the metal core particle. , Pd, Ag), platinum (Pt), gold (Au), osmium (Os), and iridium (Ir), the total content is preferably 70% by mass or more. The content is more preferably 80% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more, more preferably 99% by mass or more, and 100% by mass. In other words, the metal core particle is substantially selected from the group consisting of the fourth period transition element, the fifth period transition element, platinum (Pt), gold (Au), osmium (Os), and iridium (Ir). More preferably, it consists of at least one. Here, “becomes substantially” means that impurities inevitably contained from the raw materials and the production process can be contained, but other than that are not contained. Unless otherwise specified, in the description of the present invention, “main component” and “substantially become” are used in this sense.

  When the metal core particle includes two or more elements selected from the group consisting of a fourth periodic transition element, a fifth periodic transition element, platinum (Pt), gold (Au), osmium (Os), and iridium (Ir). It is preferable because the metal core particles tend to be chemically stabilized. The metal core particles include Pd—Pt (meaning that Pd and Pt are contained. The same applies hereinafter), Pd—Ag, Pd—Au, Pd—Cu, Pt—Ag, Pt—Au, Pt—Cu, Pt— A composition of Ru, Au—Ag, or Au—Ru is preferable. Further, Sn is preferably contained, and the composition is Ag—Pd—Sn or Pd—Cu—Sn.

  As a component that the metal core particle may contain in addition to the fourth periodic transition element, the fifth periodic transition element, platinum (Pt), gold (Au), osmium (Os), and iridium (Ir), Sn, La, Ce, Pr.

A method for measuring the component (composition) contained in the metal core particles in the present invention will be described.
The component (composition) contained in the metal core particle is obtained by calcining the metal core particle, the coated particle of the present invention or the supported catalyst of the present invention at 600 ° C., melting the residue with an alkali melting agent, and then adding 28% by mass hydrochloric acid or nitric acid. After dissolving with an aqueous solution and diluting the obtained solution with pure water, measurement is performed using an ICP inductively coupled plasma emission spectrometer (for example, SPS1200A, manufactured by Seiko Denshi Co., Ltd.). Further, when the same element is contained in the metal core particle and the porous oxide layer, the coated particle of the present invention or the supported catalyst of the present invention is subjected to surface analysis (element distribution analysis) by EDX, and the metal core particle and porous Obtain the abundance ratio of the element in the oxide layer, and calculate the content ratio of the components constituting the metal core particles from the obtained abundance ratio and the composition of each component using the ICP inductively coupled plasma emission spectrometer And ask for it.

  The average particle diameter of the primary particles of the metal core particles is not particularly limited, but is preferably 0.5 to 100 nm, more preferably 1 to 50 nm, more preferably 1 to 40 nm, and more preferably 1 to 20 nm. It is more preferable that it is 1-15 nm. In such a range, it can be easily produced, and the catalytic activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher than when the particle diameter is too large. Because it becomes.

  Here, the average particle diameter of the primary particles of the metal core particles means a value measured by an image analysis method. The image analysis method uses a scanning electron microscope to photograph metal core particles at a magnification of 300,000 times, arbitrarily select 100 metal core particles from the obtained photograph, and each projected area has an equivalent circle diameter. Is a method for obtaining a particle size distribution by measuring and then calculating an average particle size (median diameter) therefrom.

  The shape of the metal core particle is not particularly limited. For example, the shape may be spherical, tetrahedral (triangular pyramid), hexahedral (cubic or cuboid, hereinafter also referred to as “square”), octahedral, or indefinite. Can be mentioned.

  The metal core particles preferably form chain particles in which several (for example, 4 to 30) primary particles having an average particle diameter as described above are connected in a bead shape.

  The shape and form of the metal core particles are photographed at a magnification of 300,000 times using a scanning electron microscope, as in the case of measuring the average particle diameter of the primary particles of the metal core particles as described above. This can be confirmed.

<Porous oxide layer>
Next, the porous oxide layer in the coated particles of the present invention will be described.
The porous oxide layer in the coated particle of the present invention is attached to at least a part of the surface of the metal core particle. The coated particles of the present invention preferably have a porous oxide layer on the entire surface of the metal core particles, that is, a mode in which the metal core particles are covered with the porous oxide layer.

The porous oxide layer is mainly composed of a silica-based oxide. That is, the content of the silica-based oxide in the porous oxide layer is 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and 95% by mass or more. More preferably, it is 99% by mass or more, more preferably 100% by mass (the porous oxide layer is substantially composed of a silica-based oxide) (here, “substantially”). Is as described above).
Here, the silica-based oxide means a compound containing Si or a simple substance of Si. Examples of the silica-based oxide include SiO ₂ and Si, and composite oxides containing other elements (such as Al and Zr).

The content of silica (SiO ₂ ) in the porous oxide layer is preferably 85% by mass or more, preferably 90% by mass or more, preferably 95% by mass or more, and 99% by mass. More preferably, it is the above.
Here, the content of silica in the porous oxide layer is determined by measuring the content of silicon (Si) contained in the coated particles of the present invention by the method described below, and then the total amount of Si is SiO _2. It shall be calculated and determined as contained in the porous oxide layer.
The content of silicon (Si) contained in the porous oxide layer is determined by calcining the coated particles of the present invention at 600 ° C., melting the residue with an alkali melting agent, and then dissolving with 28% by mass hydrochloric acid or nitric acid aqueous solution. The obtained solution is diluted with pure water, and then measured using an ICP inductively coupled plasma emission spectrometer (for example, SPS1200A, manufactured by Seiko Electronics Co., Ltd.).

The porous oxide layer includes an element group ω that is at least one selected from the group consisting of elements in the third period to the sixth period, and the element with respect to the total molar amount of silicon (Si) and the element group ω The molar amount ratio of the group ω (element group ω / (element group ω + Si) × 100) is preferably 0.05 to 10%.
Here, the element group ω may be one element, and in this case, the element group ω means the one element. When the element group ω is two or more elements, the molar amount of the element group ω means the total molar amount of those elements. The element group ω does not contain Si.
The element group ω is at least one element selected from the group consisting of elements in the third period to the sixth period, and among them, alkali metals, alkaline earth elements, transition elements, group 12 elements (Zn, Cd and Hg ), Group 13 elements (Al, Ga, In and Tl), group 14 elements (Ge, Sn and Pb), and group 15 elements (P, As, Sb and Bi), preferably Al, Zr or Ti It is more preferable that

Thus, when the porous oxide layer is not composed only of silica but contains a small amount of a specific element (element group ω), the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on the carrier is high. The inventor has found that the activity is higher and the activity is maintained for a longer period of time. Further, the porous oxide layer includes an element group ω that is at least one selected from the group consisting of elements in the third period to the sixth period, and is based on the total molar amount of silicon (Si) and the element group ω. The molar ratio of the element group ω (element group ω / (element group ω + Si) × 100) is 0.05 to 10%, and the porous oxide layer is substantially composed of a silica-based oxide (composite oxidation). It is preferable that such an effect is further enhanced.
The upper limit of this ratio (element group ω / (element group ω + Si) × 100) is preferably 5%, more preferably 4%, still more preferably 3%, and the lower limit is 0.00. It is preferably 1%, more preferably 0.2%, and even more preferably 0.25%. This is because the above effect is further enhanced.

  Here, the molar amount of Si and element group ω in the porous oxide layer was 28 mass% after calcining the coated particles of the present invention or the supported catalyst of the present invention at 600 ° C. and melting the residue with an alkali melting agent. After dissolving with hydrochloric acid or nitric acid aqueous solution and diluting the obtained solution with pure water, the content rate is measured using an ICP inductively coupled plasma emission spectrometer (for example, SPS1200A, manufactured by Seiko Electronics Co., Ltd.). It is calculated and calculated. Further, when the same element is contained in the metal core particle and the porous oxide layer, the coated particle of the present invention or the supported catalyst of the present invention is subjected to surface analysis (element distribution analysis) by EDX, and the metal core particle and porous The content ratio of the component contained in the porous oxide layer is determined from the obtained abundance ratio and the composition of each component using the ICP inductively coupled plasma emission spectrometer described above. Is calculated and converted from that.

  The porous oxide layer has a structure in which silicon and atoms other than silicon are alternately bonded via oxygen, that is, oxygen atoms are bonded to four bonds of silicon atoms, and atoms other than silicon are bonded to the oxygen atoms. The present inventor presumes that the structure in which the is bonded is mainly used. Further, the present inventor presumes that a hydroxyl group (OH group) is present on the outermost surface portion of the porous oxide layer, which makes the coated particles of the present invention hydrophilic.

In the porous oxide layer, pores having an average pore diameter of more than 0.2 nm and less than 8 nm are formed. Within such a range, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is high, and the activity is maintained for a long time even when used. If the average pore diameter of the pores formed in the porous oxide layer is too large, the life of the supported catalyst of the present invention tends to be shortened. Conversely, if the average pore diameter is too small, the supported catalyst of the present invention Activity tends to be low.
The average pore diameter is preferably 0.4 to 5 nm, more preferably 0.8 to 2.0 nm, and still more preferably 0.8 to 1.0 nm.

Here, the average pore diameter (average pore diameter) of the porous oxide layer means a value obtained by measurement by the following nitrogen adsorption method [1].
The nitrogen adsorption method [1] will be described.
First, the dried measurement object (0.2 g) is placed in a measurement cell as a sample, degassed in a nitrogen gas stream at 250 ° C. for 40 minutes, and then the sample is treated with 30 vol% nitrogen and helium. A liquid nitrogen temperature is maintained in a 70% by volume mixed gas stream, and nitrogen is adsorbed on the sample to obtain a nitrogen adsorption / desorption isotherm. Then, using the obtained nitrogen adsorption / desorption isotherm, a BJH (Barret-Joyner-Halenda) method is used to obtain a pore size distribution curve of the sample, and the mesopores (pores on the particle surface) side appearing on the curve and Of the peaks on the macropore (interparticle pore) side, the pore diameter on the mesopore side is determined as the average pore diameter. Such a nitrogen adsorption method can be performed using, for example, a conventionally known pore distribution measuring apparatus (for example, BELSORP-mini (II) manufactured by Nippon Bell Co., Ltd.).
In the present invention, the average value of the pore diameter (average pore diameter) of the porous oxide layer means a value measured by the nitrogen adsorption method [1] shown here unless otherwise specified.

  The porous oxide layer preferably has a pore volume of 0.01 to 0.5 ml / g with respect to the unit mass of the coated particles of the present invention, preferably 0.05 to 0.4 ml / g. More preferably, it is 0.07 to 0.3 ml / g. Within such a range, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and even when used, the activity is maintained for a longer period, which is preferable. If the pore volume formed in the porous oxide layer is too large, the life of the supported catalyst of the present invention tends to be shortened. Conversely, if the pore volume is too small, the supported catalyst of the present invention The activity tends to be low.

Here, the pore volume of the porous oxide layer means a value obtained by measurement by the nitrogen adsorption method [2] shown below.
The nitrogen adsorption method [2] will be described.
First, the dried measurement object (0.2 g) is placed in a measurement cell as a sample, degassed in a nitrogen gas stream at 250 ° C. for 40 minutes, and then the sample is treated with 30 vol% nitrogen and helium. A liquid nitrogen temperature is maintained in a 70% by volume mixed gas stream, and nitrogen is adsorbed on the sample to obtain a nitrogen adsorption / desorption isotherm. Then, the integrated value of the mesopore side portion in the IV hysteresis curve defined by IUPAC, where the value of the relative pressure P / P _{0 in} the obtained nitrogen adsorption / desorption isotherm appears in the range of 0.4 to 1.0, And obtain this as the volume of the pores. Such a nitrogen adsorption method can be performed using, for example, a conventionally known pore distribution measuring apparatus (for example, BELSORP-mini (II) manufactured by Nippon Bell Co., Ltd.).
In the present invention, the pore volume of the porous oxide layer means a value measured by the nitrogen adsorption method [2] shown here unless otherwise specified.

  The thickness of the porous oxide layer is not particularly limited, but the average value is preferably more than 2 nm, more preferably 4 nm or more, and further preferably 5 nm or more. The average thickness of the porous oxide layer is preferably 50 nm or less, more preferably 40 nm or less, more preferably 30 nm or less, and even more preferably 25 nm or less. More preferably, it is 20 nm or less. Within such a range, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and even when used, the activity is maintained for a longer period, which is preferable. If the thickness of the porous oxide layer is too thick, the activity of the supported catalyst of the present invention tends to be low, and conversely if too thin, the life of the supported catalyst of the present invention tends to be short.

  Here, the thickness of the porous oxide layer is determined by taking a photograph of the coated particles of the present invention at a magnification of 300,000 times using a scanning electron microscope, and arbitrarily selecting 100 coated particles of the present invention from the obtained photographs. The thickness of the porous oxide layer in each of the coated particles of the present invention was measured several times and averaged to obtain the thickness of the porous oxide layer in the coated particle of the present invention. By simply averaging the data, the thickness of the porous oxide layer in the sample (group of coated particles of the present invention) is obtained.

The porous oxide layer has pores having the average diameter and volume as described above, and preferably has the thickness as described above. When the balance with the volume is appropriate, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and the activity is maintained for a longer period of time even when used. Found out.
Specifically, the average pore diameter of the pores of the porous oxide layer is 0.4 to 5 nm, the pore volume is 0.07 to 0.30 ml / g, and the porous oxide layer When the thickness of the layer is 4 to 30 nm, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and the activity is maintained for a longer period even when used.

<Coated particles of the present invention>
The coated particles of the present invention have hydrophilicity. Therefore, the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier can be preferably used as a catalyst for promoting a chemical reaction in water, for example.
Since the coated particles of the present invention are hydrophilic, the contact angle is small. Specifically, the contact angle in the coated particles of the present invention is about 1 to 30 degrees, preferably 1 to 25 degrees, and more preferably 1 to 20 degrees. The upper limit of the contact angle is preferably 16 degrees, more preferably 14 degrees, and further preferably 12 degrees. The lower limit of the contact angle is preferably 2 degrees, more preferably 3 degrees, and further preferably 5 degrees.
The contact angle was obtained by drying 1 g of the coated particles of the present invention at 200 ° C., and then putting it in a cell having a diameter of 1 cm and a height of 5 cm and pressing it with a load of 50 kgf to obtain a molded product. It shall mean the value obtained by measuring a drop of water on the surface of the object.

The specific surface area of the coated particles of the present invention is not particularly limited, is preferably 100~1000m ² / g, more preferably 130~900m ² / g, further to be 150~800m ² / g preferable. Within such a range, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and even when used, the activity is maintained for a longer period, which is preferable. If the specific surface area is too large, the activity of the supported catalyst of the present invention tends to be low. Conversely, if the specific surface area is too small, the life of the supported catalyst of the present invention tends to be short.
The specific surface area means a value obtained by measurement by the following nitrogen adsorption method [3] (BET method).
The nitrogen adsorption method [3] will be described.
First, a measurement object (here, coated particles of the present invention) dried (0.2 g) is placed in a measurement cell as a sample, degassed at 250 ° C. for 40 minutes in a nitrogen gas stream, The sample is kept at a liquid nitrogen temperature in a mixed gas stream of 30% by volume of nitrogen and 70% by volume of helium, and nitrogen is adsorbed on the sample by equilibrium. Next, the temperature of the sample is gradually raised to room temperature while flowing the above mixed gas, the amount of nitrogen desorbed during that time is detected, and the specific surface area of the sample is measured. The nitrogen adsorption method (BET method) can be performed using, for example, a conventionally known surface area measuring device.
In the present invention, the specific surface area means a value measured by the nitrogen adsorption method [3] (BET method) shown here unless otherwise specified.

The coated particles of the present invention are those in which the porous oxide layer is attached to at least a part of the surface of the metal core particles.
In the coated particles of the present invention, the mass ratio of the metal core particles and the porous oxide layer is not particularly limited, but the ratio of the mass of the porous oxide layer to the mass of the metal core particles (the mass of the porous oxide layer / the metal The mass of the core particles is preferably from 0.1 to 5000, more preferably from 0.5 to 3000, and even more preferably from 1 to 2000. Within such a range, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and even when used, the activity is maintained for a longer period, which is preferable.

  Here, the mass of the metal core particles and the porous oxide layer in the coated particles of the present invention is obtained by calcining the coated particles of the present invention or the supported catalyst of the present invention at 600 ° C. and melting the residue with an alkali melting agent. After dissolving with 28% by mass hydrochloric acid or nitric acid aqueous solution and diluting the obtained solution with pure water, the content rate is measured using an ICP inductively coupled plasma emission spectrometer (for example, SPS1200A, manufactured by Seiko Electronics Co., Ltd.). , And calculate from that. Further, when the same element is contained in the metal core particle and the porous oxide layer, the coated particle of the present invention or the supported catalyst of the present invention is subjected to surface analysis (element distribution analysis) by EDX, and the metal core particle and porous The content ratio of the component contained in the porous oxide layer is determined from the obtained abundance ratio and the composition of each component using the ICP inductively coupled plasma emission spectrometer described above. Is calculated from the above.

The average particle diameter (median diameter) of the coated particles of the present invention is not particularly limited, but is preferably 1 to 500 nm, more preferably 2 to 100 nm, and even more preferably 3 to 50 nm.
Here, the average particle diameter of the coated particles of the present invention is such that a measurement object (here, coated particles of the present invention) is added to a sodium hexametaphosphate aqueous solution and dispersed by ultrasonic dispersion and stirring, and the transmittance is 70 to 90. After adjusting to be%, it means a value calculated by measuring a particle size distribution using a conventionally known laser scattering method (for example, HORIBA LA-950V2).

Next, the supported catalyst of the present invention will be described.
The supported catalyst of the present invention is one in which the coated particles of the present invention are supported on the surface of a carrier.

The carrier is not particularly limited as long as it can carry the metal core particles, and for example, an inorganic carrier containing at least one selected from the group consisting of Si, Al, C, Ti, Zr, and Ce as a main component. Is mentioned.
Other components that the support may contain include alkali metals, alkaline earths, rare earths, transition metals (eg, Li, Na, K, Rb, Cs, Mg, Ca, Sr, La, Pr, Nd, Pm, Sm, Eu , Gd, Tb, Dy, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo).
The carrier may be amorphous or crystalline, and may be a synthetic substance or a natural mineral.
The inorganic carrier containing at least one selected from the group consisting of Si, Al, C, Ti, Zr and Ce is preferably made of an oxide of the element, and may be a complex oxide. As such an inorganic carrier, for example, silica particles (mesoporous silica, silicalite), silica-alumina particles, alumina particles (active alumina particles), carbon particles, activated carbon (coconut shell, phenol resin, basic, etc.), Zeolite particles (Y type, A type, mordenite type, ZSM-5 type, etc., which may be natural or synthetic), ceria (cerium oxide) particles, kaolin particles, smectite particles, vermiculite particles, mica flakes, titania and zirconia Can be mentioned.

  Further, the shape of the carrier is not particularly limited, and may be, for example, spherical or indefinite.

The average particle diameter (median diameter) of the carrier is not particularly limited, but is preferably 10 nm to 100 mm, more preferably 12 nm to 50 mm, more preferably 15 nm to 10 mm, and further preferably 20 nm to 5 mm.
Here, the average particle diameter of the carrier is adjusted so that the transmittance is 70 to 90% by adding the object to be measured (here, the carrier) to the sodium hexametaphosphate aqueous solution and dispersing by ultrasonic dispersion and stirring. In addition, it means a value calculated by measuring the particle size distribution using a conventionally known laser scattering method (for example, HORIBA LA-950V2).

Although the specific surface area of the support is not particularly limited, it is preferably 1~2000m ² / g, more preferably 5~1800m ² / g, more preferably from 10~1500m ² / g.
In addition, the specific surface area of a support | carrier here shall mean the value obtained by measuring by nitrogen adsorption method [3] (BET method) similarly to the specific surface area of the covering particle | grains of this invention mentioned above.

  The supported catalyst of the present invention is such that the coated particles of the present invention are supported on at least a part of the surface of such a carrier.

The amount of the metal core particles contained in the supported catalyst of the present invention is not particularly limited, but is preferably 0.01 to 100 parts by mass, and 0.1 to 50 parts by mass with respect to 100 parts by mass of the carrier. More preferably, it is 0.5-20 mass parts, More preferably, it is 1-10 mass parts. This is because if the amount of the metal core particles is too small relative to the support, the catalytic ability tends to be low, and conversely if too large, the catalytic ability tends not to be high for an increase in cost.
Here, the amount of the metal core particles contained in the supported catalyst of the present invention is such that the supported catalyst of the present invention is calcined at 600 ° C., the residue is melted with an alkaline melting agent, and then dissolved in 28% by mass hydrochloric acid or nitric acid aqueous solution. Then, after the obtained solution is diluted with pure water, the content of the components constituting the metal core particles is measured and obtained using an ICP inductively coupled plasma emission spectrometer (for example, SPS1200A, manufactured by Seiko Electronics Co., Ltd.). Shall. Further, when the same element is contained in the metal core particle and the porous oxide layer, the supported catalyst of the present invention is subjected to surface analysis (element distribution analysis) by EDX, and the element in the metal core particle and the porous oxide layer. The content ratio of the components constituting the metal core particles is calculated from the obtained content ratio and the composition of each component using the above ICP inductively coupled plasma emission spectrometer. .

Further, in the supported catalyst of the present invention, the coated particles of the present invention, a unit area of the carrier (1 m ²⁾ per preferably being ² carries 10 ² to 10 ¹⁷ / m, 10 ³ to 10 ¹⁵ atoms / More preferably, m ^{2 is} supported. This is because if the amount of the coated particles of the present invention is too small relative to the support, the catalytic ability tends to be low, and conversely if too large, the catalytic ability tends not to be high for an increase in cost.
Here, the number of the coated particles of the present invention supported on the carrier was photographed with a scanning electron microscope at a magnification of 300,000 times, and from the photograph obtained by the naked eye, or The number of carrying is measured using a reader.

Further, the specific surface area of the supported catalyst of the present invention is not particularly limited, is preferably 1~2000m ² / g, more preferably 5~1800m ² / g, a 10~1500m ² / g Is more preferable.
Here, the specific surface area of the supported catalyst of the present invention means a value obtained by measurement by the nitrogen adsorption method [3] (BET method) in the same manner as the specific surface area of the coated particles of the present invention described above. To do.

  As described above, since the coated particles of the present invention are hydrophilic, the surface of the supported catalyst of the present invention is likely to be hydrophilic.

The average particle diameter (median diameter) of the supported catalyst of the present invention is not particularly limited, but is preferably 10 nm to 100 mm, more preferably 12 nm to 50 mm, more preferably 15 nm to 10 mm, and further preferably 20 nm to 5 mm.
Here, when the average particle diameter of the supported catalyst of the present invention is less than 100 μm, an object to be measured (supported catalyst of the present invention) is added to an aqueous solution of sodium hexametaphosphate, and dispersed by ultrasonic dispersion and stirring. Is adjusted to 70 to 90%, and then a value obtained by measuring and calculating the particle size distribution using a conventionally known laser scattering method (for example, HORIBA LA-950V2) is meant. The average particle diameter of 100 μm or more means the value calculated from the obtained particle size distribution by placing the supported catalyst of the present invention on a glass plate, measuring the projected area equivalent circle diameter with respect to any 100 particles with a microscope. To do.

Next, the manufacturing method of the covering particle | grains of this invention is demonstrated.
Although the manufacturing method of the coated particle of this invention is not specifically limited, It is preferable to manufacture with the suitable manufacturing method of the coated particle of this invention demonstrated below.

  The preferred production method of the coated particles of the present invention includes a colloid preparation step for obtaining a colloidal solution in which metal core particles are dispersed, a solution containing silicon [α], and a solution containing an alkali-soluble inorganic substance that is soluble in alkali [β The solution [α] and the solution [β] are added to the colloidal solution adjusted to be alkaline, and at least a part of the surface of the metal core particle is derived from silicon and the alkali-soluble inorganic substance. An addition step of obtaining a dispersion (X) in which untreated core-shell type particles coated with a shell layer containing a component to be dispersed are dispersed, and an acid or an alkali is added to the dispersion (X), to the shell layer Separating at least a part of the component derived from the alkali-soluble inorganic substance contained from the shell layer, forming pores in at least a part of the shell layer, And a pore forming step for obtaining a dispersion (Y) in which porous oxide-coated particles having a porous oxide layer mainly composed of a silica-based oxide are attached to at least a part of the surface. It is a manufacturing method of quality oxide covering particles.

<Colloid adjustment process>
First, the colloid adjustment step in the preferred method for producing coated particles of the present invention will be described.
The colloid adjusting step is a step of obtaining a colloid solution in which the metal core particles are dispersed.
For example, a colloidal solution in which metal core particles are dispersed can be obtained by reducing specific metal ions in the solution. Moreover, as a method of reducing a specific metal ion in a solution, a method of bringing a specific metal ion and a reducing agent into contact with each other in a solution can be mentioned. Here, the specific metal ion can be obtained by dissolving a metal compound (metal salt or the like) constituting the metal core particle in a solvent.
Moreover, when making a specific metal ion and a reducing agent contact in a solution, it is preferable to add a complexing stabilizer together in a solution. This is because the particles obtained after the reduction can be made uniform and stable.

Examples of such metal compounds (metal salts and the like) include palladium chloride, palladium nitrate, palladium sulfate, palladium citrate, and palladium acetate. When such a compound is dissolved in a solvent, palladium ions are obtained as specific metal ions, and a colloidal solution in which metal core particles containing palladium are dispersed is obtained by bringing this ion into contact with a reducing agent.
In addition, chloroplatinic acid, potassium platinum (IV) chloride, sodium chloroplatinum (IV), potassium tetranitroplatinum (II), sodium hexahydroxoplatinum (IV) hydrate as metal compounds (metal salts, etc.) , Dinitrodiammine platinum nitrate, dinitrodiammine platinum ammonia, tetraamminedichloroplatinum hydrate. When such a compound is dissolved in a solvent, platinum ions are obtained as specific metal ions, and a colloidal solution in which metal core particles containing platinum are dispersed is obtained by bringing this ion into contact with a reducing agent.
Moreover, silver nitrate and silver sulfate are mentioned as a metal compound (metal salt etc.). When such a compound is dissolved in a solvent, silver ions are obtained as specific metal ions, and a colloidal solution in which metal core particles containing silver are dispersed is obtained by bringing this into contact with a reducing agent in a solution.
Examples of metal compounds (metal salts and the like) include chloroauric acid, sodium gold sulfite, potassium gold cyanide, and sodium gold cyanide. When such a compound is dissolved in a solvent, gold ions are obtained as specific metal ions, and a colloidal solution in which metal core particles containing gold are dispersed is obtained by bringing this into contact with a reducing agent.
Moreover, copper chloride, copper sulfate, copper nitrate is mentioned as a metal compound (metal salt etc.). When such a compound is dissolved in a solvent, copper ions are obtained as specific metal ions, and a colloidal solution in which metal core particles containing copper are dispersed is obtained by bringing this into contact with a reducing agent.
Furthermore, ferric sulfate and ferrous acetate are mentioned as a metal compound (metal salt etc.). When such a compound is dissolved in a solvent, iron ions are obtained as specific metal ions, and a colloidal solution in which metal core particles containing iron are dispersed is obtained by bringing this into contact with a reducing agent.

  In addition, the solvent used for dissolving the metal compound (metal salt or the like) constituting the metal core particle in order to obtain the metal ion is not particularly limited as long as it does not react with the compound. , Water, alcohols, ketones, amides, ethers, glycol ethers, glycol ether acetates, esters, aromatic hydrocarbons, aliphatic hydrocarbons, halogenated hydrocarbons, sulfoxides, pyrrolidones Etc.

  Examples of the reducing agent include alcohol, hydrazine, formic acid, formaldehyde, hydroquinone, perchloric acid, ferrous sulfate, sodium borohydride, hydrogen peroxide, and potassium permanganate.

By adding such a reducing agent to a solution containing metal ions, the metal ions and the reducing agent can be brought into contact with each other in the solution. Alternatively, the metal ion and the reducing agent can be brought into contact with each other in the solution by dissolving the reducing agent in a solvent in advance to form a solution and mixing the solution with a solution containing metal ions. The solvent in which the reducing agent is dissolved in advance may be the same as the solvent in which the metal compound (metal salt or the like) that constitutes the metal core particle is dissolved.
Metal ions are preferably reduced by adding a reducing agent to the solution while stirring the solution.

  In addition, the amount ratio of the metal ion to the reducing agent is not particularly limited, but the reducing agent is preferably 10 parts by mass to 500 parts by mass with respect to 100 parts by mass of the metal ion, and 50 to 300 parts by mass. More preferably.

  Moreover, it is preferable to add a dispersant or a surfactant (for example, polyvinyl pyrrolidone, aminosilane, polycarboxylic acid, organic acid, etc.) as necessary after contacting the metal ion with the reducing agent in the solution. . This is because the metal core particles hardly aggregate.

In addition, it is preferable to remove the unreacted metal ions and the reducing agent by bringing the metal ions and the reducing agent into contact with each other in the solution and then washing them using an ultrafilter or the like.
Further, it is preferable to contact a metal ion and a reducing agent in a solution, add an acid such as hydrochloric acid to dissolve excess salt, and then desalinate using an ion exchange resin or the like.

The colloid adjustment step may be, for example, a method of mixing a solution containing metal ions and a solvent. Also by such a method, a colloidal solution in which metal core particles are dispersed can be obtained.
Examples of the solvent include monoethylene glycol, methanol, ethanol, 2-propanol, 1-butanol, and water.
A solution containing metal ions is preferably added to a solvent as described above after adding a complexing stabilizer, and preferably stirred at 5 to 200 ° C. to obtain a colloidal solution in which metal core particles are dispersed. be able to. Here, polyvinyl pyrrolidone, aminosilane, polycarboxylic acid, organic acid, or the like can be used as the complexing stabilizer.

  The concentration of the solid content in the obtained colloidal solution is preferably 0.5 to 40% by mass, and more preferably 1.0 to 30% by mass.

<Addition process>
Next, the addition process in the suitable manufacturing method of the coated particle | grains of this invention is demonstrated.
In the addition step, first, a solution [α] containing silicon and a solution [β] containing an alkali-soluble inorganic substance that is an inorganic substance dissolved in an alkali are prepared.

Examples of the solution [α] containing silicon include an aqueous solution containing silicate and a silicate solution.
And as aqueous solution containing a silicate, alkali metal silicate, ammonium silicate, and silicate of an organic base are mentioned, For example, you may contain 2 or more of these.
Examples of the alkali metal silicate include sodium silicate (water glass) and potassium silicate. Examples of the ammonium silicate include quaternary ammonium salts (such as tetraethylammonium salt), specifically, quaternary ammonium hydroxide. Examples of the organic base silicate include compounds obtained by adding amines (monoethanolamine, diethanolamine, triethanolamine, etc.) to the silicic acid solution.
Moreover, as a silicic acid liquid, an acidic silicic acid liquid can be used. The acidic silicic acid solution can be obtained by removing the alkali, for example, by treating an aqueous alkali silicate solution with a cation exchange resin. The acidic silicic acid solution is preferably one having a pH of _{2 to} 4 and a SiO ₂ concentration of about 7% by mass or less.

  The solid content concentration in the solution [α] containing silicon is not particularly limited. However, when the solution [α] containing silicon is an aqueous solution or silicate solution containing silicate, the solid content concentration is 0.1 to 10% by mass. It is preferable that there is about 1% by mass.

In the addition step, such a solution [α] and a solution [β] containing an alkali-soluble inorganic substance are prepared. The alkali-soluble inorganic substance means an inorganic substance that is soluble in alkali.
Examples of the alkali-soluble inorganic substance include elements of the third to sixth periods (preferably alkali metals, alkaline earth elements, transition elements, group 12 elements (Zn, Cd and Hg), group 13 elements (Al, Ga, In And Tl), Group 14 elements (Ge, Sn and Pb), and Group 15 elements (P, As, Sb and Bi), more preferably Al, Zr, Ti, B, Sn, Ce, P, Sb, Mo, Alkali metal salts, alkaline earth metal salts or ammonium salts of oxo acids containing at least one element selected from the group consisting of Zn and W). Specific examples include sodium aluminate, sodium tetraborate, ammonium zirconium carbonate, potassium antimonate, potassium stannate, sodium aluminosilicate, sodium molybdate, cerium ammonium nitrate, and sodium phosphate.

  The solid content concentration in the solution [β] containing the alkali-soluble inorganic substance is not particularly limited, but the concentration of the alkali-soluble inorganic substance is preferably 0.1 to 10% by mass, and more preferably about 1% by mass. .

  In the addition step, after preparing a solution [α] containing silicon and a solution [β] containing an alkali-soluble inorganic substance as described above, these are added to the colloid solution adjusted to be alkaline. Specifically, before adding the solution [α] and the solution [β], the colloid solution is adjusted to be alkaline with a pH of 9 to 13, preferably 10 to 12, more preferably about 10.5.

Further, when the above-mentioned solution [α] containing silicon and the solution [β] containing alkali-soluble inorganic substance are added to the colloid solution adjusted to be alkaline, the mole of silicon added in terms of SiO ₂ is added. The ratio of the molar amount in terms of oxide of the component derived from the alkali-soluble inorganic substance added to the amount (the molar amount in terms of oxide of the component derived from the alkali-soluble inorganic substance (mol) / SiO ₂ equivalent of silicon) The solution [α] and the solution [β] are added to the colloidal solution so that the molar amount (mol) is 0.25 or less, preferably 0.20 or less, more preferably 0.17 or less. Is preferred.
Here, it is preferable that the solution [α] and the solution [β] are simultaneously added to the colloidal solution. It is also preferable to add the solution [α] and the solution [β] to the colloidal solution alternately little by little.

  Here, the component derived from the alkali-soluble inorganic material means a component that forms a shell layer contained in ions generated when the alkali-soluble inorganic material is dissolved in an alkali solution. For example, the alkali-soluble inorganic material is an oxoacid. In the case of the salt, it means an element constituting an oxoacid ion. More specifically, for example, when the alkali-soluble inorganic substance is sodium aluminate, it is dissolved in the alkaline solution to produce aluminate, and aluminum corresponds to the component that forms the shell layer. The component is aluminum.

Further, the molar amount of the component derived from the alkali-soluble inorganic substance in terms of oxide means that the component derived from the alkali-soluble inorganic substance is present alone and in its most common form of oxide. It means the molar amount converted on the assumption. For example, when the alkali-soluble inorganic substance is sodium aluminate, since the component derived therefrom is aluminum as described above, this is a single and the most common oxide form (Al ₂ O ₃ ) and the total amount is It means the calculated molar amount, assuming that it is present. When the solution [β] contains two or more components derived from the alkali-soluble inorganic material, it is assumed that each of them is present alone and in its most common oxide form. After conversion, the molar amount of each element in terms of oxide is added to obtain the molar amount in terms of oxide of the component derived from the alkali-soluble inorganic substance added to the colloidal solution contained in the solution [β]. .

When added to the colloidal solution at such a specific ratio, untreated core-shell type particles coated with a shell layer containing components derived from at least silicon and the alkali-soluble inorganic substance on the surface of the metal core particles are dispersed. A dispersion (X) is obtained.
Silica and alkali-soluble inorganic substances each have high solubility in an alkali solution, but when coexisting in an alkali solution, components derived from each (silicate ions and oxoacid ions (eg, aluminate ions)) The present inventor has found that both the oxides and the composite oxides containing both precipitate and grow on the surface of the metal core particles.

When adding the solution [α] and the solution [β] to the colloidal solution, a reaction solution in which at least a part of the solution [α] and / or the solution [β] is added to the colloidal solution and the colloidal container is preferable. Is kept at 60-100 ° C, more preferably about 90 ° C.
Further, it is preferable to add the solution [α] and the solution [β] while stirring the reaction solution.
The addition of the solution [α] and the solution [β] is preferably performed slowly over a period of about 1 to 10 hours, more preferably about 6 hours.

  The mixing ratio of the total amount of the solution [α] and the solution [β] and the colloid solution is not particularly limited, but the solution [α] and the solution to be mixed with respect to the mass of the solid content contained in the colloid solution to be mixed The ratio of the total solids contained in [β] (total mass of solids contained in solution [α] and solution [β] / mass of solids contained in colloidal solution) of 0.1 to 0.1 5000 is preferable, 0.5 to 3000 is more preferable, 1 to 2000 is more preferable, 1 to 1000 is more preferable, 1 to 500 is more preferable, and 1 More preferably, it is -100. Within such a range, the activity of the supported catalyst of the present invention in which the coated particles of the present invention are supported on a carrier is higher, and even when used, the activity is maintained for a longer period, which is preferable.

  As described above, a solution [α] containing silicon and a solution [β] containing an alkali-soluble inorganic substance were added to the colloidal solution to obtain a dispersion liquid (X) in which untreated core-shell particles were dispersed. Thereafter, it is preferable to remove unreacted silicic acid by washing with an ultrafilter or the like.

<Pore forming step>
Next, the pore formation step in the preferred method for producing coated particles of the present invention will be described.
In the pore formation step, acid or alkali is added to the dispersion (X) obtained in the addition step, and at least a part of the components derived from the alkali-soluble inorganic substance contained in the shell layer is removed from the shell layer. To separate.
Here, the acid or alkali is not particularly limited as long as it can be separated from the shell layer by dissolving at least a part of the component derived from the alkali-soluble inorganic substance contained in the shell layer.
Although depending on the type of component derived from the alkali-soluble inorganic substance to be dissolved, an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, or an organic acid can be used as the acid. Moreover, as an alkali, sodium hydroxide, potassium hydroxide, ammonia, tetramethylammonium can be used.

  The amount of acid or alkali added to the dispersion (X) is not particularly limited. Although depending on the type of the component derived from the alkali-soluble inorganic material to be dissolved, it is preferable to add the dispersion (X) so that the pH of the dispersion (X) is about 1.5 when an acid is added. .

  When the solution is stirred after adding the acid or alkali to the dispersion (X), at least a part of the components derived from the alkali-soluble inorganic substance contained in the shell layer is dissolved and easily separated from the shell layer. preferable.

  An acid or alkali is added to the dispersion (X), and at least a part of the alkali-soluble inorganic substance contained in the shell layer is separated from the shell layer. It is preferable to remove the excess silica component, the component derived from the alkali-soluble inorganic substance, and the like by washing with use.

  In this way, at least a part of the alkali-soluble inorganic substance contained in the shell layer is separated from the shell layer to form pores in at least a part of the shell layer, and at least the surface of the metal core particles A dispersion liquid (Y) in which porous oxide-coated particles having a porous oxide layer mainly composed of a silica-based oxide is dispersed can be obtained.

Next, the manufacturing method of the supported catalyst of this invention is demonstrated.
The production method of the supported catalyst of the present invention is not particularly limited, but the porous oxide-coated particles dispersed in the dispersion liquid (Y) are further added to the above-mentioned preferred production method of the coated particles of the present invention. It is preferable that it is a manufacturing method provided with the process made to carry | support on the surface.
In this step, first, the above-mentioned carrier is obtained by a conventionally known production method, and then the porous oxide-coated particles dispersed in the dispersion (Y) are supported on the surface of the carrier.
For example, the porous oxide-coated particles can be supported on the surface of the support using a conventionally known supporting method. For example, it can be obtained by mixing the dispersion in which the carrier is dispersed and the dispersion (Y), and then drying and baking. For example, specifically, the dispersion liquid (Y) is added to the dispersion liquid in which the carrier is dispersed, and the mixture is stirred and mixed. After that, using a conventionally known dryer, the temperature is 80 to 200 ° C. After drying for 50 hours, it can be obtained by firing for 0.5 to 10 hours at a temperature of 300 to 700 ° C. in air using a conventionally known firing furnace.

  Examples of the present invention will be described below. The present invention is not limited to these examples.

<Measurement method and evaluation method>
Various measurement methods and evaluation methods performed in Examples and Comparative Examples will be described.

[1] Method for measuring average particle diameter (median diameter) of metal core particles The average particle diameter was measured by an image analysis method. That is, using a scanning electron microscope (S-5500, manufactured by Hitachi, Ltd.), a sample (metal core particles, porous oxide-coated particles or supported catalyst) was photographed at a magnification of 300,000 times, and obtained. 100 metal core particles were arbitrarily selected from the photograph, each projected area equivalent circle diameter was measured to obtain a particle size distribution, and an average particle diameter (median diameter) was calculated therefrom.

[2] Method for measuring thickness of porous oxide layer Using a scanning electron microscope (S-5500, manufactured by Hitachi, Ltd.), a sample (porous oxide-coated particles) was photographed at a magnification of 300,000 times. Then, 100 porous oxide-coated particles are arbitrarily selected from the obtained photographs, and the thickness of the porous oxide layer in each porous oxide-coated particle is measured several times and averaged. The thickness of the porous oxide layer in the porous oxide-coated particles was taken as the thickness of the porous oxide layer in the sample (group of porous oxide-coated particles) by simply averaging the 100 data. .

[3] Method for analyzing composition of metal core particle, shell layer and porous oxide layer Sample (metal core particle, porous oxide-coated particle or untreated core-shell type particle) is fired at 600 ° C., and the residue is an alkali melting agent And then dissolved by 28% by mass hydrochloric acid or nitric acid aqueous solution. And after diluting the obtained solution with pure water, the composition was measured with an ICP inductively coupled plasma emission spectroscopic analyzer (SPS1200A, manufactured by Seiko Electronics Co., Ltd.).

[4] Method for measuring average value of pore diameter of porous oxide layer The fineness of the porous oxide layer is measured by the nitrogen adsorption method [1] using a pore distribution measuring device (BELSORP mini, manufactured by Bell Japan). The average value of pore diameter (average pore diameter) was measured.
The nitrogen adsorption method [1] is the following method.
First, the dried measurement object (0.2 g) is placed in a measurement cell as a sample, degassed in a nitrogen gas stream at 250 ° C. for 40 minutes, and then the sample is treated with 30 vol% nitrogen and helium. The liquid nitrogen temperature was maintained in a 70% by volume mixed gas stream, and nitrogen was adsorbed on the sample to obtain a nitrogen adsorption / desorption isotherm. Then, using the obtained nitrogen adsorption / desorption isotherm, a BJH (Barret-Joyner-Halenda) method is used to obtain a pore size distribution curve of the sample, and the mesopores (pores on the particle surface) side appearing on the curve and Of the peaks on the macropore (interparticle pore) side, the mesopore-side peak pore diameter was determined as the average pore diameter.

[5] Method for measuring pore volume of porous oxide layer The pores of the porous oxide layer are measured by the nitrogen adsorption method [2] using a pore distribution measuring device (BELSORP mini, manufactured by Nippon Bell Co., Ltd.). The volume of was measured.
The nitrogen adsorption method [2] is the following method.
First, the dried measurement object (0.2 g) is placed in a measurement cell as a sample, degassed in a nitrogen gas stream at 250 ° C. for 40 minutes, and then the sample is treated with 30 vol% nitrogen and helium. The liquid nitrogen temperature was maintained in a 70% by volume mixed gas stream, and nitrogen was adsorbed on the sample to obtain a nitrogen adsorption / desorption isotherm. Then, the integrated value of the mesopore side portion in the IV hysteresis curve defined by IUPAC, where the value of the relative pressure P / P _{0 in} the obtained nitrogen adsorption / desorption isotherm appears in the range of 0.4 to 1.0, This was obtained as the pore volume.

[6] Method for Measuring Specific Surface Area of Porous Oxide-Coated Particles Using a surface area measuring device (manufactured by Yuasa Ionics Co., Ltd., Multisorb 12 type), a porous oxide is obtained by nitrogen adsorption method [3] (BET method). The specific surface area of the coated particles was measured.
The nitrogen adsorption method [3] is the following method.
First, a dried measurement object (porous oxide-coated particles) (0.2 g) is placed in a measurement cell as a sample, and degassed at 250 ° C. for 40 minutes in a nitrogen gas stream. The sample was kept at a liquid nitrogen temperature in a mixed gas stream of 30% by volume of nitrogen and 70% by volume of helium, and nitrogen was adsorbed on the sample by equilibrium. Next, the sample temperature was gradually raised to room temperature while flowing the mixed gas, and the amount of nitrogen desorbed during that time was detected, and the specific surface area of the sample was measured.

[7] Method for measuring wettability (contact angle) of porous oxide-coated particles After drying 1 g of porous oxide-coated particles at 200 ° C., they are placed in a cell having a diameter of 1 cm and a height of 5 cm and a load of 50 kgf. Then, a molded product was obtained by pressing, and a drop of water was dropped on the surface of the obtained molded product, and the contact angle was measured.

[8] Catalyst performance evaluation method (measurement of catalyst activity and life)
A double-type glass reaction tube in which another glass tube with an inner diameter of 21 mm was inserted into a glass tube with an inner diameter of 30 mm was prepared, and the supported catalyst was filled in the inner glass tube so as to block a part of the flow path. . The mass of the supported catalyst filled here was such that the mass of the metal core particles contained therein was 0.002 g.
Warm water at 40 ° C. was circulated between the inner glass tube and the outer glass tube of such a double glass reaction tube to keep the temperature in the inner glass tube constant. Thereafter, the mixed gas was introduced into the inner glass reaction tube from one end at 422 ml / min. Then, after contact with the supported catalyst filled, the concentration of ethylene (C ₂ H ₄₎ and ethane (C ₂ H ₆₎ was measured by gas chromatography in the exhaust gas discharged from the other end. The measurement was carried out once per hour and for a maximum of 48 hours. The mixed gas introduced into the inner glass reaction tube is N ₂ : H ₂ : C ₂ H ₂ = 400: 10: 12 (volume ratio).
Then, to determine the production rate from the concentration of ethylene (C ₂ H ₄₎ and ethane in the exhaust gas was measured (C ₂ H _6). The production rate is obtained by the following equation, and the initial production rate obtained from this equation (the production rate measured when the composition of the exhaust gas is stabilized after a few minutes have passed since the introduction of the mixed gas) is defined as the catalyst activity. The time when the production rate decreased by 3% with respect to the catalyst activity was defined as the life.
Production rate = total amount of moles of ethylene and ethane in the exhaust gas per hour (mol / min) / mol amount of acetylene in the mixed gas per hour (mol / min) × 100

<Method for adjusting the carrier>
Next, a method for preparing a suspension in which a carrier is dispersed will be described.

[Synthesis Example A]
Preparation method of activated carbon suspension Activated carbon (manufactured by Ajinomoto Fine Techno Co., Ltd., trade name: CL-K, particle size: 0.5 mm to 1.7 mm, iodine adsorption amount 1,550 mg / g) is dispersed in pure water, and activated carbon An activated carbon suspension (A) having a concentration of 10% by mass was prepared.

[Synthesis Example B]
Preparation method of activated alumina suspension Activated alumina (manufactured by Wako Pure Chemical Industries, model number: 596-15865, specific surface area 250 m ² / g, particle size 50 μm) is dispersed in pure water, and activated alumina concentration is 10% by mass. An alumina suspension (B) was prepared.

<Method for adjusting metal core particles>
Next, a method for preparing a colloidal solution in which metal core particles are dispersed will be described.

[Synthesis Example 1]
Preparation Method of Pd Colloid Solution A solution was prepared by dissolving 122 g of ferrous sulfate as a reducing agent in 219 g of an aqueous citric acid solution (concentration: 30% by mass). Then, 341 g of this solution was added to 39 g of an aqueous palladium nitrate solution (concentration: 20% by mass) at room temperature and mixed well to obtain a dispersion in which Pd particles were dispersed. The obtained dispersion was washed (desalted, etc.) using an ultrafilter (manufactured by ADVANTEC, Ultrafilter Q0500) and concentrated to obtain a Pd dispersion having a Pd concentration of 3% by mass.
The obtained Pd dispersion was diluted about 1000 times, a part of the Pd particles were placed on a collodion film and dried, and the average particle diameter was obtained by taking a photograph using the above-mentioned method (scanning electron microscope). It was 2 nm when measured by the method obtained from the photograph). It was confirmed by observation with a scanning electron microscope that the Pd particles were spherical.
Next, 1 g of 1% by volume hydrochloric acid was added to 100 g of the obtained Pd dispersion, and after stirring for 1 hour, 10 g of an anion exchange resin (manufactured by Mitsubishi Chemical Corporation, SANUPC) was added for desalting. After desalting, coarse particles were cut using a centrifuge (G = 8000), and the Pd concentration was measured using an ICP inductively coupled plasma emission spectrometer SPS1200A (Seiko Electronics Co., Ltd.). And the Pd colloidal solution adjusted so that Pd density | concentration might be 2.5 mass% was obtained.
The physical properties and the like of the obtained colloid solution are shown in Table 1.

[Synthesis Example 2]
Preparation method of Pd-Pt colloid solution Palladium nitrate (II) hydrate 22.5 g (9 g in terms of palladium metal) and chloroplatinic acid hexahydrate 25 g (9 g in terms of platinum metal) were added to 16,000 g of pure water. To obtain an aqueous metal salt solution. Then, 1,660 g of 5.0 mass% trisodium citrate aqueous solution as a complexing stabilizer and 140 g of 0.1 mass% sodium borohydride aqueous solution as a reducing agent were added to the obtained metal salt aqueous solution, The mixture was stirred and mixed at 20 ° C. in a nitrogen atmosphere to obtain a dispersion in which Pd—Pt fine particles were dispersed in water. The obtained dispersion was washed (desalted, etc.) using an ultrafilter (manufactured by ADVANTEC, Ultrafilter Q0500), concentrated, and Pd-Pt concentration (Pd and Pt total concentration) was 3% by mass. Of Pd—Pt dispersion was obtained.
The obtained Pd—Pt dispersion is diluted about 1000 times, a part of the Pd—Pt particles are placed on a collodion film and dried, and the average particle diameter is determined by the method described above (photographing using a scanning electron microscope). Then, it was 2 nm when measured by the method obtained from the obtained photograph). In addition, it was confirmed by observation with a scanning electron microscope that the Pd—Pt particles were spherical.
Next, 5 g of 1% by volume hydrochloric acid was added to 100 g of the obtained Pd—Pt dispersion, and after stirring for 1 hour, 10 g of anion exchange resin (manufactured by Mitsubishi Chemical Corporation, SANUPC) was added for desalting. After desalting, coarse particles were cut using a centrifuge (G = 8000), and the Pd-Pt concentration was measured using an ICP inductively coupled plasma emission spectrometer SPS1200A (Seiko Electronics Co., Ltd.). And the Pd-Pt colloidal solution adjusted so that Pd-Pt density | concentration (Pd and Pt total density | concentration) might be 2.5 mass% was obtained.
The physical properties and the like of the obtained colloid solution are shown in Table 1.

[Synthesis Example 3]
Preparation Method of Chain Ag-Pd Colloid Solution A solution in which 122 g of ferrous sulfate as a reducing agent was dissolved in 219 g of an aqueous citric acid solution (concentration: 30% by mass) was prepared. Then, 341 g of this solution was added to 80 g of an aqueous silver nitrate solution (concentration 10% by mass) at room temperature, and then 421 g of the obtained solution was further added to 39 g of an aqueous palladium nitrate solution (concentration 20% by mass) at room temperature, followed by thorough mixing. As a result, a dispersion liquid in which Ag—Pd particles were dispersed was obtained. The obtained dispersion was washed (desalted, etc.) using an ultrafilter (ADVANTEC, Ultrafilter Q0500), concentrated, and Ag-Pd concentration (Ag and Pd total concentration) was 3% by mass. An Ag—Pd dispersion was obtained.
The obtained Ag—Pd dispersion is diluted about 1000 times, a part of the Ag—Pd particles is placed on a collodion film and dried, and the average particle size is measured by the above-mentioned method (photographing using a scanning electron microscope). Then, it was 4 nm when measured by a method obtained from the obtained photograph). The Ag—Pd particles were confirmed to be chain-like by observation with a scanning electron microscope.
Next, 0.5 g of 1% by volume hydrochloric acid was added to 100 g of the obtained Ag-Pd dispersion, and after stirring for 1 hour, 10 g of anion exchange resin (manufactured by Mitsubishi Chemical Corporation, SANUPC) was added to perform desalting. It was. After desalting, coarse particles were cut using a centrifuge (G = 8000), and the Ag-Pd concentration was measured using an ICP inductively coupled plasma emission spectrometer SPS1200A (manufactured by Seiko Denshi KK). And the Ag-Pd colloidal solution adjusted so that Ag-Pd density | concentration (Ag and Pd total density | concentration) might be 2.5 mass% was obtained.
The physical properties and the like of the obtained colloid solution are shown in Table 1.

[Synthesis Example 4]
Preparation method of prismatic Pd colloidal solution A metal salt aqueous solution obtained by dissolving 22.5 g of palladium (II) nitrate hydrate (9 g in terms of palladium metal) in 200 g of pure water has a concentration of 1.0 as a complexing stabilizer. 50 g of a mass% polyvinylpyrrolidone (molecular weight 550000) ethylene glycol solution was added and mixed. The obtained solution was added to 1800 g of monoethylene glycol as a solvent, and stirred and mixed at 150 ° C. for 6 hours in a nitrogen atmosphere to obtain a Pd dispersion in which Pd particles were dispersed.
The obtained Pd dispersion was diluted about 1000 times, a part of the Pd particles were placed on a collodion film and dried, and the average particle diameter was obtained by taking a photograph using the above-mentioned method (scanning electron microscope). It was 15 nm when measured by a method obtained from the photograph). In addition, it was confirmed by observation with a scanning electron microscope that the Pd particles are angular.
Next, after concentrating the obtained Pd dispersion using a rotary evaporator, coarse particles are cut using a centrifuge (G = 8000), and an ICP inductively coupled plasma emission spectrometer SPS1200A (Seiko Electronic Co., Ltd.) The Pd concentration was measured using And the square Pd colloidal solution adjusted so that Pd density | concentration might be 2.5 mass% was obtained.
The physical properties and the like of the obtained colloid solution are shown in Table 1.

[Synthesis Example 5]
Preparation Method of Pd—Au Colloid Solution 22.5 g of palladium nitrate (II) hydrate (9 g in terms of palladium metal) was dissolved in 100 g of pure water to obtain a solution. Further, 18.8 g (9 g in terms of gold metal) of gold chloride (III) acid tetrahydrate was dissolved in 100 g of pure water to obtain a solution. Then, 50 g of an aqueous solution of polyvinyl pyrrolidone (manufactured by Kanto Chemical Co., K-30, molecular weight 40000) having a concentration of 5.0% by mass as a complexing stabilizer was added to each solution and mixed. The two solutions were both added to 1800 g of monoethylene glycol as a solvent, and stirred and mixed at 100 ° C. for 6 hours under a nitrogen atmosphere to obtain a Pd—Au dispersion liquid in which Pd—Au particles were dispersed.
The obtained Pd—Au dispersion was diluted about 1000 times, a part of the Pd—Au particles were placed on a collodion film, dried, and the average particle size was determined by the method described above (photographing using a scanning electron microscope). Then, it was 10 nm when measured by the method obtained from the obtained photograph). Note that it was confirmed by observation with a scanning electron microscope that the Pd—Au particles were spherical.
Next, after concentrating the obtained Pd—Au dispersion using a rotary evaporator, the coarse particles are cut using a centrifuge (G = 8000), and an ICP inductively coupled plasma emission spectrometer SPS1200A (Seiko) The Pd concentration was measured using an electronic company). And the Pd-Au colloid solution adjusted so that Pd-Au density | concentration (total density | concentration of Pd and Au) might be 2.5 mass% was obtained.
The physical properties and the like of the obtained colloid solution are shown in Table 1.

[Synthesis Example 6]
Preparation Method of Pd-Cu Colloid Solution A solution was prepared by dissolving 122 g of ferrous sulfate as a reducing agent in 219 g of an aqueous citric acid solution (concentration: 30% by mass). Then, after adding 341 g of this solution to 39 g of an aqueous palladium nitrate solution (concentration 20% by mass) at room temperature, 10 g of an aqueous copper nitrate solution (concentration 20% by mass) was further added and mixed thoroughly, whereby Pd-Cu particles A dispersion liquid was obtained. The obtained dispersion was washed (desalted) using an ultrafilter (manufactured by ADVANTEC, Ultrafilter Q0500), concentrated, and Pd—Cu concentration (Pd and Cu total concentration) was 2.5. A mass% Pd—Cu dispersion was obtained.
The obtained Pd—Cu dispersion is diluted about 1000 times, a part of the Pd—Cu particles are placed on a collodion film, dried, and the average particle size is measured by the above-mentioned method (photographing using a scanning electron microscope). Then, it was 2 nm when measured by the method obtained from the obtained photograph). Note that it was confirmed by observation with a scanning electron microscope that the Pd—Cu particles were spherical.
Next, 0.5 g of 1% by volume hydrochloric acid was added to 100 g of the obtained Pd—Cu dispersion, and after stirring for 1 hour, 10 g of anion exchange resin (manufactured by Mitsubishi Chemical Corporation, SANUPC) was added to perform desalting. It was. After desalting, coarse particles were cut using a centrifuge (G = 8000), and the Pd—Cu concentration was measured using an ICP inductively coupled plasma emission spectrometer SPS1200A (manufactured by Seiko Electronics Co., Ltd.). And the Pd-Cu colloid solution adjusted so that Pd-Cu density | concentration (Pd and Cu total density | concentration) might be 2.5 mass% was obtained.
The physical properties and the like of the obtained colloid solution are shown in Table 1.

<Example 1>
1 kg of a 1% by weight solution obtained by diluting the Pd colloidal solution obtained in Synthesis Example 1 with pure water was obtained. Then, 1 g of polyvinyl pyrrolidone (PVP) (manufactured by Kanto Chemical Co., K-30, molecular weight 40000) is added to the resulting solution, and then stirred for 1 hour to obtain a stabilized Pd colloid solution (1-1). It was. By performing such treatment, aggregation of Pd particles can be suppressed.

Next, 1% by mass of NaOH was added to the stabilized Pd colloidal solution (1-1) to adjust the pH to 10.5 to obtain a stabilized Pd colloidal solution (1-2) with adjusted pH. .
Then, 36 kg of 1% by weight aqueous sodium silicate solution (360 g in terms of SiO ₂ ) and 4 kg of 1% by weight sodium aluminate aqueous solution (40 g in terms of Al ₂ O ₃ ) were prepared. And added to the stabilized Pd colloid solution (1-2) over 6 hours. Here, a solution obtained by adding at least a part of the two aqueous solutions to the stabilized Pd colloid solution (1-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. The pH of the reaction solution rose to 12.5 immediately after the addition of the two aqueous solutions, but hardly changed thereafter.
After the total amount of the two aqueous solutions was added, the resulting reaction solution was allowed to cool in the room to cool to room temperature, and then washed using an ultrafilter (ADVANTEC, Ultrafilter Q0500) to obtain a solid. A dispersion liquid (1-3) in which untreated core-shell particles having a partial concentration of 5% by mass were dispersed was obtained. Here, the untreated core-shell type particles have Pd as a metal core particle and a shell layer containing silicon and aluminum on the surface thereof.

Next, hydrochloric acid was added to the obtained dispersion (1-3) to adjust the pH to 1.5, and the mixture was sufficiently stirred. By performing such treatment, at least a part of aluminum is separated from the shell layer, and pores are formed in the shell layer. Thereafter, NaOH is added to adjust the pH to 7, and using an ultrafilter (manufactured by ADVANTEC, Ultrafilter Q0500), an excess silica component, an alumina component, a salt, and the like are separated to obtain a metal concentration (Pd concentration). ) Obtained a dispersion (1-4) containing 2.5% by mass of porous oxide-coated particles. The composition of the dispersion liquid (1-4) containing the obtained porous oxide-coated particles was measured using an ICP inductively coupled plasma optical emission spectrometer SPS1200A (manufactured by Seiko Electronics Co., Ltd.).
Then, the obtained dispersion (1-4) is diluted about 1000 times, and a part thereof is placed on a collodion membrane, dried, separated, and the porous oxide in the porous oxide-coated particles by the above-described method. The layer composition, thickness, average pore diameter average value (average pore diameter) and pore volume, specific surface area, contact angle, and average particle diameter of the metal core particles were measured.
The measurement results are shown in Table 1.

Next, 40 g of the dispersion (1-4) was added to 990 g of the 10% by mass activated carbon suspension (A) prepared in Synthesis Example A, and the mixture was stirred for 10 minutes. And the supported catalyst (1-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (1-5) is one in which porous oxide-coated particles are supported on activated carbon.
The average particle diameter of the metal core particles supported on the supported catalyst (1-5) thus obtained is determined by the above-described method (a method for obtaining a photograph using a scanning electron microscope and obtaining from the obtained photograph). Measured with
Moreover, based on the above-mentioned catalyst performance evaluation method, the performance of the obtained supported catalyst (1-5) was evaluated. Moreover, the performance was similarly evaluated about what baked the supported catalyst (1-5) at 500 degreeC for 3 hours. Furthermore, the average particle diameter of the metal core particles was measured for the supported catalyst (1-5) calcined at 500 ° C. for 3 hours.
The measurement results are shown in Table 1.

<Example 2>
In the same manner as in Example 1, a stabilized Pd colloid solution (1-2) with adjusted pH was obtained.
Then, 243 kg of a 1% by mass sodium silicate aqueous solution (2430 g in terms of SiO ₂ ) and 27 kg of a 1% by mass sodium aluminate aqueous solution (270 g in terms of Al ₂ O ₃ ) were prepared. And added to the stabilized Pd colloid solution (1-2) over 6 hours. Here, a solution obtained by adding at least a part of the two aqueous solutions to the stabilized Pd colloid solution (1-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. The pH of the reaction solution rose to 12.5 immediately after the addition of the two aqueous solutions, but hardly changed thereafter.
Thereafter, the same operation as in Example 1 was performed, and a dispersion liquid (2-3) in which untreated core-shell particles having a solid content concentration of 5% by mass were dispersed, and a dispersion liquid (2- 4) A supported catalyst (2-5) was obtained. And the measurement similar to Example 1 was performed.
The measurement results are shown in Table 1.

<Example 3>
In the same manner as in Example 1, a stabilized Pd colloid solution (1-2) with adjusted pH was obtained.
Then, 1710 kg of a 1% by mass aqueous sodium silicate solution (17100 g equivalent in terms of SiO ₂ ) and 190 kg of a 1% by mass aqueous sodium aluminate solution (1900 g equivalent in terms of Al ₂ O ₃ ) were prepared. And added to the stabilized Pd colloid solution (1-2) over 6 hours. Here, a solution obtained by adding at least a part of the two aqueous solutions to the stabilized Pd colloid solution (1-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. The pH of the reaction solution rose to 12.5 immediately after the addition of the two aqueous solutions, but hardly changed thereafter.
Thereafter, the same operation as in Example 1 was performed to obtain a dispersion (3-3) in which untreated core-shell particles having a solid content concentration of 5% by mass were dispersed, and a dispersion containing porous oxide-coated particles (3- 4) A supported catalyst (3-5) was obtained. And the measurement similar to Example 1 was performed.
The measurement results are shown in Table 1.

<Example 4>
1 kg of a solution in which the Pd—Pt colloidal solution obtained in Synthesis Example 2 was diluted with pure water to 1 mass% was obtained. Then, 0.1 g of polyaluminum chloride (PAC) (manufactured by Taki Chemical Co., Ltd .: Takibaine # 1000) is added to the obtained solution, and then stirred for 1 hour to stabilize the Pd—Pt colloidal solution (4-1 ) By performing such treatment, aggregation of Pd—Pt particles can be suppressed.

Next, 1% by mass of KOH is added to the stabilized Pd—Pt colloidal solution (4-1) to adjust the pH to 12.5, and the stabilized Pd—Pt colloidal solution (4-2) whose pH is adjusted. )
Then, 75 kg of 1 wt% silicic acid aqueous solution (750 g in terms of SiO ₂ ) and 25 kg of 1 wt% zirconium salt (Zircosol AC-7, manufactured by Daiichi Rare Element Co., Ltd.) (250 g in terms of ZrO ₂ ) Prepared and added to the stabilized Pd—Pt colloidal solution (4-2) in small portions over 6 hours at the same time. Here, a solution obtained by adding at least a part of the two aqueous solutions to the stabilized Pd—Pt colloidal solution (4-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. Note that the pH of the reaction solution hardly changed from 12.5 immediately after the addition of the two aqueous solutions and until the addition was completed.
Thereafter, the same operation as in Example 1 was performed to obtain a dispersion (4-3) in which untreated core-shell particles having a solid content concentration of 5% by mass were dispersed, and a dispersion containing porous oxide-coated particles (4- 4) was obtained. About these, the same measurement as Example 1 was performed.

Next, 120 g of the dispersion (4-4) was added to 970 g of the 10% by mass activated alumina suspension (B) prepared in Synthesis Example B, and the mixture was stirred for 10 minutes. And the supported catalyst (4-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (4-5) is one in which porous oxide-coated particles are supported on activated carbon.
And about the supported catalyst (4-5), the same measurement as Example 1 was performed.
The measurement results are shown in Table 1.

<Example 5>
1 kg of a solution in which the Pd—Pt colloidal solution obtained in Synthesis Example 2 was diluted with pure water to 1 mass% was obtained. Then, 0.1 g of a cationic surfactant (KHE-1000, manufactured by Senka Co., Ltd.) was added to the resulting solution, and then stirred for 1 hour to obtain a stabilized Pd—Pt colloidal solution (5-1). It was. By performing such treatment, aggregation of Pd—Pt particles can be suppressed.
Thereafter, the same operation as in Example 4 was performed, and a stabilized Pd—Pt colloidal solution (5-2) adjusted in pH and a dispersion liquid in which untreated core-shell type particles having a solid content concentration of 5 mass% were dispersed ( 5-3), a dispersion (5-4) containing porous oxide-coated particles, and a supported catalyst (5-5) were obtained. In the same manner as in Example 4, the same measurement as in Example 1 was performed.
As in Example 4, the pH of the reaction solution changed almost from 12.5 until immediately after the addition of the silicic acid aqueous solution and the zirconium salt aqueous solution to the stabilized Pd—Pt colloidal solution (5-2). I didn't.
The measurement results are shown in Table 1.

<Example 6>
1 kg of a solution in which the chain Ag-Pd colloidal solution obtained in Synthesis Example 3 was diluted with pure water to a concentration of 1% by mass was obtained. Then, 1 g of polyvinylpyrrolidone (PVP) (manufactured by Kanto Chemical Co., K-30, molecular weight 40000) was added to the resulting solution, and then stirred for 1 hour to stabilize the Ag-Pd colloidal solution (6-1). Got. By performing such treatment, aggregation of Ag—Pd particles can be suppressed.

Next, 1% by mass of NaOH is added to the stabilized Ag-Pd colloidal solution (6-1) to adjust the pH to 10.5, and the stabilized Ag-Pd colloidal solution (6-2) with adjusted pH. )
Then, 7.2 kg of 1 mass% sodium silicate aqueous solution (72 g in terms of SiO ₂ ) and 0.8 kg of 1 mass% sodium aluminate aqueous solution (8 g in terms of Al ₂ O ₃ ) were prepared. At the same time, it was added in small portions over 6 hours to the stabilized Ag-Pd colloidal solution (6-2). Here, a solution obtained by adding at least a part of the two aqueous solutions to the stabilized Ag-Pd colloidal solution (6-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. The pH of the reaction solution rose to 12.5 immediately after the addition of the two aqueous solutions, but hardly changed thereafter.
Thereafter, the same operation as in Example 1 was performed to obtain a dispersion liquid (6-3) in which untreated core-shell particles having a solid content concentration of 5 mass% were dispersed, and a dispersion liquid containing porous oxide-coated particles (6- 4) was obtained. About these, the same measurement as Example 1 was performed.

Next, 120 g of the dispersion (6-4) was added to 970 g of the 10% by mass activated alumina suspension (B) prepared in Synthesis Example B, and the mixture was stirred for 10 minutes. And the supported catalyst (6-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (6-5) is one in which porous oxide-coated particles are supported on activated carbon.
And about the supported catalyst (6-5), the same measurement as Example 1 was performed.
The measurement results are shown in Table 1.

<Example 7>
1 kg of a solution in which the square Pd colloidal solution obtained in Synthesis Example 4 was diluted to 1% by mass with pure water was obtained. Then, 0.3 g of polyvinyl pyrrolidone (PVP) (manufactured by Kanto Chemical Co., K-30, molecular weight 40000) was added to the resulting solution, and then stirred for 1 hour to stabilize the angular Pd colloid solution (7- 1) was obtained. By performing such treatment, aggregation of the square Pd particles can be suppressed.

Next, 1% by mass of NaOH is added to the stabilized prismatic Pd colloidal solution (7-1) to adjust the pH to 10.5, and the stabilized prismatic Pd colloidal solution (7-1) with adjusted pH. )
Then, 0.9 kg of 1 mass% sodium silicate aqueous solution (9 g in terms of SiO ₂ ) and 0.1 kg of 1 mass% sodium aluminate aqueous solution (1 g in terms of Al ₂ O ₃ ) were prepared. At the same time, it was added little by little to the stabilized angular Pd colloid solution (7-2) over 6 hours. Here, a solution obtained by adding at least a part of the two aqueous solutions to the stabilized rectangular Pd colloid solution (7-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. The pH of the reaction solution rose to 12.5 immediately after the addition of the two aqueous solutions, but hardly changed thereafter.
Thereafter, the same operation as in Example 6 was performed to obtain a dispersion (7-3) in which untreated core-shell particles having a solid content concentration of 5% by mass were dispersed, and a dispersion (7-) containing porous oxide-coated particles. 4) A supported catalyst (7-5) was obtained. In the same manner as in Example 6, the same measurement as in Example 1 was performed.
The measurement results are shown in Table 1.

<Example 8>
1 kg of a solution in which the Pd—Au colloid solution obtained in Synthesis Example 5 was diluted with pure water to 1 mass% was obtained. Then, 0.3 g of polyvinylpyrrolidone (PVP) (manufactured by Kanto Chemical Co., K-30, molecular weight 40000) was added to the resulting solution, and then stirred for 1 hour to stabilize the Pd—Au colloid solution (8- 1) was obtained. By performing such treatment, aggregation of Pd—Au particles can be suppressed.

Next, 1% by mass of NaOH is added to the stabilized Pd—Au colloidal solution (8-1) to adjust the pH to 10.5, and the stabilized Pd—Au colloidal solution (8-2) with adjusted pH. )
Then, the same operation as in Example 7 was performed to obtain a dispersion liquid (8-3) in which untreated core-shell particles having a solid content concentration of 5 mass% were dispersed, and a dispersion liquid containing porous oxide-coated particles ( 8-4) and a supported catalyst (8-5) were obtained. In the same manner as in Example 6, the same measurement as in Example 1 was performed.
The measurement results are shown in Table 1.

<Example 9>
1 kg of a solution in which the Pd—Cu colloidal solution obtained in Synthesis Example 6 was diluted with pure water to 1 mass% was obtained. Then, 1 g of polyvinylpyrrolidone (PVP) (manufactured by Kanto Chemical Co., K-30, molecular weight 40000) was added to the obtained solution, and then stirred for 1 hour to stabilize the Pd—Cu colloid solution (9-1). Got. By performing such a treatment, aggregation of Pd—Cu particles can be suppressed.

Next, 1% by mass of NaOH is added to the stabilized Pd—Cu colloidal solution (9-1) to adjust the pH to 10.5, and the stabilized Pd—Cu colloidal solution (9-1) having the adjusted pH. )
Then, the same operation as in Example 1 was performed, and a dispersion liquid (9-3) in which untreated core-shell particles having a solid content concentration of 5 mass% were dispersed, and a dispersion liquid containing porous oxide-coated particles ( 9-4) and a supported catalyst (9-5) were obtained. And the measurement similar to Example 1 was performed.
The measurement results are shown in Table 1.

<Example 10>
1 kg of a 1% by weight solution obtained by diluting the Pd colloidal solution obtained in Synthesis Example 1 with pure water was obtained. Then, 1 g of aminosilane (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the resulting solution, and then stirred for 1 hour to obtain a stabilized Pd colloid solution (10-1). By performing such treatment, aggregation of Pd particles can be suppressed.
Thereafter, the same operation as in Example 1 was performed, and a stabilized Pd colloidal solution (10-2) with adjusted pH, and a dispersion (10-) in which untreated core-shell particles having a solid content concentration of 5 mass% were dispersed. 3) A dispersion (10-4) containing porous oxide-coated particles and a supported catalyst (10-5) were obtained. And the measurement similar to Example 1 was performed.
As in Example 1, the pH of the reaction solution rose to 12.5 immediately after the addition of the sodium silicate aqueous solution and the sodium aluminate aqueous solution, but hardly changed thereafter.
The measurement results are shown in Table 1.

<Comparative Example 1>
In the same manner as in Example 1, a stabilized Pd colloid solution (1-1) was obtained.
Then, 100 g of the stabilized Pd colloid solution (1-1) was added to 990 g of the 10% by mass activated carbon suspension (A) prepared in Synthesis Example A, and stirred for 10 minutes. And the supported catalyst (RF1-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF1-5) is a metal core particle supported on activated carbon.
The supported catalyst (RF1-5) thus obtained was measured in the same manner as in Example 1.
The measurement results are shown in Table 1.

<Comparative example 2>
To 990 g of the 10% by mass activated carbon suspension (A) prepared in Synthesis Example A, 40 g of the Pd colloid solution obtained in Synthesis Example 1 was added and stirred for 10 minutes. And the supported catalyst (RF2-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF2-5) is a metal core particle supported on activated carbon.
The same measurement as in Example 1 was performed on the supported catalyst (RF2-5) thus obtained.
The measurement results are shown in Table 1.

<Comparative Example 3>
In the same manner as in Example 4, a stabilized Pd—Pt colloid solution (4-1) was obtained.
Then, 300 g of the stabilized Pd—Pt colloid solution (4-1) was added to 970 g of the 10% by mass activated alumina suspension (B) prepared in Synthesis Example B, and stirred for 10 minutes. And the supported catalyst (RF3-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF3-5) is one in which metal core particles are supported on activated alumina.
With respect to the supported catalyst (RF3-5) thus obtained, the same measurement as in Example 1 was performed.
The measurement results are shown in Table 1.

<Comparative example 4>
In the same manner as in Example 5, a stabilized Pd—Pt colloidal solution (5-1) was obtained.
Then, 300 g of the stabilized Pd—Pt colloid solution (5-1) was added to 970 g of the 10% by mass activated alumina suspension (B) prepared in Synthesis Example B, and stirred for 10 minutes. And the supported catalyst (RF4-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF4-5) is one in which metal core particles are supported on activated alumina.
For the supported catalyst (RF4-5) thus obtained, the same measurement as in Example 1 was performed.
The measurement results are shown in Table 1.

<Comparative Example 5>
In the same manner as in Example 6, a stabilized Ag-Pd colloidal solution (6-1) was obtained.
Then, 300 g of the stabilized Ag-Pd colloidal solution (6-1) was added to 970 g of the 10% by mass activated alumina suspension (B) prepared in Synthesis Example B, and stirred for 10 minutes. And the supported catalyst (RF5-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF5-5) is one in which metal core particles are supported on activated alumina.
For the supported catalyst (RF5-5) thus obtained, the same measurement as in Example 1 was performed.
The measurement results are shown in Table 1.

<Comparative Example 6>
In the same manner as in Example 7, a stabilized angular Pd colloid solution (7-1) was obtained.
Then, 300 g of the stabilized square Pd colloid solution (7-1) was added to 970 g of the 10% by mass activated alumina suspension (B) prepared in Synthesis Example B, and stirred for 10 minutes. And the supported catalyst (RF6-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF6-5) is one in which metal core particles are supported on activated alumina.
The supported catalyst (RF6-5) thus obtained was measured in the same manner as in Example 1.
The measurement results are shown in Table 1.

<Comparative Example 7>
1 kg of a 1% by weight solution obtained by diluting the Pd colloidal solution obtained in Synthesis Example 1 with methanol was obtained. Then, 1 g of aminosilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-903) was added to the resulting solution, followed by stirring for 1 hour to obtain a stabilized Pd colloid solution (RF7-1). By performing such treatment, aggregation of Pd particles can be suppressed.

Next, 1.43 kg of normal ethyl silicate in terms of SiO ₂ was added little by little to the stabilized Pd colloid solution (RF7-1) over 6 hours. Further, the stabilized Pd colloid solution (RF7-1) was kept at 40 ° C. during the addition of this solution.
After the total amount of the two aqueous solutions was added, the resulting reaction solution was allowed to cool indoors by cooling to room temperature, and then washed using an ultrafilter (ADVANTEC, Ultrafilter Q0500), and metal A dispersion (RF7-4) containing untreated core-shell particles having a concentration (Pd concentration) of 2.5 mass% was obtained.
Then, the Pd particles in the obtained dispersion (RF7-4) are diluted about 1000 times, and a part thereof is placed on a collodion film and dried to cover the shell layer (core Pd particles as cores) in the untreated core-shell type particles. Layer) composition, thickness, average pore diameter (average pore diameter) and pore volume, specific surface area, contact angle, and average particle diameter of the metal core particles.
The measurement results are shown in Table 1. In addition, in order to contrast with the Example, the measurement result here was shown in the column which shows the measurement result about the porous oxide fine particle of Table 1.

Next, 40 g of the dispersion (RF7-4) was added to 990 g of the 10% by mass activated carbon suspension (A) prepared in Synthesis Example A, and stirred for 10 minutes. And the supported catalyst (RF7-5) was obtained by drying the obtained liquid mixture at 105 degreeC for 24 hours. The supported catalyst (RF7-5) is an untreated core-shell type particle supported on activated carbon.
The same measurement as in Example 1 was performed for the supported catalyst (RF7-5) thus obtained.
The measurement results are shown in Table 1.

<Comparative Example 8>
1 kg of a 1% by weight solution obtained by diluting the Pd colloidal solution obtained in Synthesis Example 1 with pure water was obtained.
Next, 1 mass% NaOH was added to the Pd colloidal solution to adjust the pH to 10.5, thereby obtaining a Pd colloidal solution (RF8-2) with adjusted pH.
Then, 36 kg of 1% by weight aqueous sodium silicate solution (360 g in terms of SiO ₂ ) and 4 kg of 1% by weight sodium aluminate aqueous solution (40 g in terms of Al ₂ O ₃ ) were prepared. And added to the Pd colloid solution (RF8-2) over 6 hours. Here, a solution obtained by adding at least a part of the two aqueous solutions to the Pd colloid solution (RF8-2) is also referred to as a reaction solution. Moreover, the reaction liquid was kept at 90 ° C. during the addition of the two aqueous solutions. The pH of the reaction solution rose to 12.5 immediately after the addition of the two aqueous solutions, but hardly changed thereafter.
After the total amount of the two aqueous solutions was added, the resulting reaction solution was allowed to cool to room temperature by allowing it to cool in the room. As a result, particles aggregated in the solution, and subsequent processing was impossible.

From the catalyst performance evaluation in Table 1, it can be seen that the supported catalysts in all Examples have high activity and long life even after calcination at 500 ° C. Moreover, when the average particle diameter of the metal core particle before and behind 500 degreeC baking is contrasted, it turns out that there is no change.
On the other hand, the activity of the supported catalyst in the comparative example was somewhat low, although the activity before firing at 500 ° C. was somewhat high, but the activity after firing at 500 ° C. was extremely low. Further, the lifetime was short even before baking at 500 ° C., and extremely short after baking at 500 ° C. Moreover, in the case of Comparative Examples 1-6, the average particle diameter of the metal core particle after 500 degreeC baking became large about 100 times compared with before 500 degreeC baking. This is thought to be because the metal core particles aggregated because Comparative Examples 1 to 6 do not have the porous oxide layer included in the supported catalyst of the example.

  The difference between Example 1 and Comparative Example 1 is that the metal core particles of Example 1 are coated with a porous oxide layer, whereas the metal core particles of Comparative Example 1 are not coated. is there. When comparing the activity and life of the catalyst performance evaluation in Table 1, it can be seen that there is a great difference between Example 1 and Comparative Example 1. In the case of Example 1, the average particle size of the metal core particles is not changed before and after firing at 500 ° C., but in the case of Comparative Example 1, the average particle size is after firing at 500 ° C. compared with before firing at 500 ° C. It is extremely large and is considered to have aggregated.

The difference between Example 1 and Comparative Example 2 is that the metal core particles of Example 1 are coated with a porous oxide layer, whereas the metal core particles of Comparative Example 1 are not coated. In Comparative Example 1, polyvinylpyrrolidone (PVP) is not added to a solution obtained by diluting the Pd colloid solution obtained in Synthesis Example 1 with pure water. Therefore, in the case of Comparative Example 1, the Pd particles in the Pd colloid solution tend to aggregate.
Then, comparing the activity and life of the catalyst performance evaluation in Table 1 and the average particle size before and after firing at 500 ° C., it can be seen that there is a great difference as in the comparison result between Example 1 and Comparative Example 1.

The difference between Example 4 and Comparative Example 3, the difference between Example 5 and Comparative Example 4, the difference between Example 6 and Comparative Example 5, and the difference between Example 7 and Comparative Example 6 are as follows: The metal core particles of Examples 4, 5, 6 and 7 are coated with a porous oxide layer, whereas the metal core particles of Comparative Examples 3, 4, 5 and 6 are not coated. .
Then, comparing the activity and life of the catalyst performance evaluation in Table 1 and the average particle size before and after firing at 500 ° C., it can be seen that there is a great difference as in the comparison result between Example 1 and Comparative Example 1.

  Comparative Example 7 differs from the Example in that the surface of the metal core particles made of Pd is coated with silica, and no pores are formed in the coated layer. In this case, the life of the supported catalyst was almost the same as that of the example, but the activity was very low. In particular, the activity after baking at 500 ° C. was extremely low.

  In Comparative Example 8, the Pd colloid solution obtained in Synthesis Example 1 is not sufficiently dispersed, and a layer made of silica and alumina is formed on the surface of the Pd particles. In this case, it was found that the particles are aggregated and subsequent processing becomes difficult.

Claims (12)

Having a metal core particle and a porous oxide layer on at least part of its surface;
The main component of the porous oxide layer is a silica-based oxide,
The average pore diameter of the pores of the porous oxide layer is more than 0.2 nm and less than 8 nm,
Porous oxide-coated particles having hydrophilicity.   The porous oxide-coated particle according to claim 1, wherein an average value of the thickness of the porous oxide layer is more than 2 nm.   The porous oxide-coated particles according to claim 1 or 2, wherein the pore volume is 0.01 to 0.5 ml / g. The porous oxide-coated particles according to any one of claims 1 to 3, having a specific surface area of 100 to 1000 m ² / g.   The porous oxide layer includes an element group ω that is at least one selected from the group consisting of elements in the third period to the sixth period, and the element group with respect to the total molar amount of silicon (Si) and the element group ω 5. The porous oxide-coated particle according to claim 1, wherein a molar ratio (element group ω / (element group ω + Si) × 100) of ω is 0.05 to 10%.   The said metal core particle has as a main component at least 1 chosen from the group which consists of a 4th period transition element, a 5th period transition element, platinum, gold | metal | money, osmium, and iridium. Porous oxide coated particles.   A supported catalyst in which the porous oxide-coated particles according to claim 1 are supported on the surface of a support. A colloid preparation step for obtaining a colloidal solution in which metal core particles are dispersed;
A solution [α] containing silicon and a solution [β] containing an alkali-soluble inorganic substance that is an inorganic substance soluble in alkali are prepared, and the solution [α] and the solution [β] are added to the colloidal solution adjusted to be alkaline. A dispersion (X) in which untreated core-shell particles coated with a shell layer containing at least a part of the surface of the metal core particles and containing a component derived from silicon and the alkali-soluble inorganic material are dispersed. An adding step to obtain;
At least a part of the shell layer is obtained by adding an acid or an alkali to the dispersion (X) to separate at least a part of the component derived from the alkali-soluble inorganic substance contained in the shell layer from the shell layer. A dispersion (Y) in which porous oxide-coated particles in which pores are formed on the surface and a porous oxide layer mainly composed of a silica-based oxide is provided on at least a part of the surface of the metal core particles are dispersed A method for producing porous oxide-coated particles, comprising a pore-forming step of obtaining The adding step
Ratio of molar amount in terms of oxide of component derived from alkali-soluble inorganic substance added to molar amount in terms of SiO _{2 of} silicon to be added (molar amount in terms of oxide of component derived from alkali-soluble inorganic substance) The solution [α] and the solution [β] are added to the colloidal solution adjusted to be alkaline so that (mol) / mol amount of silicon in terms of SiO ₂ (mol) is 0.25 or less. The method for producing porous oxide-coated particles according to claim 8, wherein the dispersion (X) is obtained.   9. The alkali-soluble inorganic substance is an alkali metal salt, alkaline earth metal salt or ammonium salt of an oxo acid containing at least one element selected from the group consisting of elements of the third to sixth periods. Or the method for producing the porous oxide-coated particles according to 9.   The method for producing porous oxide-coated particles according to any one of claims 8 to 10, wherein the porous oxide-coated particles according to any one of claims 1 to 6 are obtained.   A method for producing a supported catalyst, further comprising the step of supporting the porous oxide-coated particles on the surface of a carrier in the production method according to any one of claims 8 to 11.