JP2011144420A - Precious-metal-based colloidal solution and method for producing the same - Google Patents

Abstract

The present invention provides a noble metal colloid solution having excellent storage stability in which uniform noble metal fine particles having a small particle diameter are uniformly dispersed.
SOLUTION: At least one kind of noble metal fine particles selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles, and a polyalkyleneimine having a weight average molecular weight of 3000 to 15000 are contained. A noble metal colloid solution,
The pH of the colloidal solution is 2.5-6.0,
Particulates dispersed in said colloidal solution is, the particle diameter _{D 90} of and cumulative mass is a particle diameter _{D 50} which cumulative mass in the particle size distribution is 50% 0.8~10.0nm is 90% the The noble metal-based fine particles having a particle diameter D ₅₀ of 2.5 or less.
A noble metal-based colloidal solution.
[Selection figure] None

Description

  The present invention relates to a noble metal colloid solution and a method for producing the same.

  Noble metal fine particles such as noble metal fine particles and noble metal alloy fine particles are usually carried on a carrier and used for various applications such as a catalyst. Such noble metal-based fine particles are conventionally obtained by mixing a noble metal complex, which is a raw material of noble metal-based fine particles, with a carrier that is an aggregated powder of several microns composed of an oxide or a composite oxide, or an oxide or a composite. After impregnating a noble metal complex with a carrier, which is an agglomerated powder of several microns composed of an oxide, particles were formed and supported on the carrier. However, in this method, the noble metal complex is adsorbed in the vicinity of the surface of the support formed by agglomeration of the primary particles, so that the formed noble metal fine particles are also arranged close to each other and the dispersibility becomes low. There was a problem that noble metal-based fine particles were likely to grow and the catalytic activity was lowered.

  In addition, as a method for supporting noble metal-based fine particles on a carrier, a method of adsorbing a colloidal solution containing noble metal-based fine particles on the carrier is disclosed. According to this method, since the colloidal solution containing the noble metal-based fine particles is supported on the support formed by agglomeration of the primary particles by heating with stirring, it is difficult to support the colloid solution sufficiently uniformly. On the other hand, a colloid solution containing a highly dispersible oxide or composite oxide in which an appropriate polymer dispersant is adsorbed and a colloid solution containing noble metal fine particles are uniformly mixed, and then the pH is adjusted to adjust the polymer. The noble metal fine particles can be supported on the carrier by a method of fixing the noble metal fine particles arranged uniformly by removing the dispersant. However, nanoparticles such as noble metal-based fine particles tend to aggregate in a solvent such as water, and it has not been easy to obtain a colloid solution in which noble metal-based fine particles are highly dispersed.

  For example, Japanese Patent Application Laid-Open No. 2004-261735 (Patent Document 1) discloses a noble metal colloid solution comprising a solvent such as water, cluster particles of noble metal, and a polymer dispersant such as polyethyleneimine. Although this noble metal colloid solution has good water solubility and does not cause rapid precipitation during use, the noble metal fine particles in the colloid solution are aggregated in the liquid. The monodispersibility was low.

  Japanese Patent Application Laid-Open No. 2006-183092 (Patent Document 2) discloses a reaction system in a liquid phase containing two or more kinds of metal ions in the presence of a polymer dispersant having a carboxyl group and a molecular weight of 4000 to 30000. Among them, a method is disclosed in which alloy fine particles are precipitated by being reduced by the action of a reducing agent. According to this method, alloy fine particles and a metal colloid solution containing the same can be efficiently obtained. However, even in the metal colloid solution obtained by this method, although the dispersibility of the noble metal fine particles in the liquid is improved as compared with the noble metal colloid solution described in Patent Document 1, it is still not sufficient.

  Furthermore, in JP 2009-144250 A (Patent Document 3), a thin film fluid is formed between processing surfaces which are disposed so as to be able to approach and separate from each other and at least one of which rotates relative to the other. Obtained by mixing the aqueous solution containing the polymer dispersant and the metal compound with the reducing agent aqueous solution in the above thin film and carrying out the reduction reaction while uniformly mixing in the thin film. Disclosed are metal fine particles and metal colloids containing the same. According to this method, a metal colloid solution containing metal fine particles having a uniform particle diameter can be obtained. However, even in this metal colloid solution, the metal fine particles are aggregated in the liquid, and the dispersibility in the liquid is not sufficient.

  As described above, in the conventional colloidal solution, the dispersibility of the noble metal fine particles in the liquid is not yet sufficient, and even when the noble metal colloidal solution is supported on the noble metal fine particle carrier, the noble metal-based fine particles are highly advanced. It was difficult to obtain a dispersed catalyst or the like.

  Japanese Patent Application Laid-Open No. 2005-133135 (Patent Document 4) discloses a method in which a reaction liquid is instantaneously mixed and a reaction is allowed to proceed in a pipe to form metal fine particles. It is disclosed that this is a method suitable for forming metal fine particles by a reverse micelle method using a surfactant. And in the said patent document 4, the high-speed stirring mixing system, the fine gap mixing system, and the high pressure mixing system are disclosed as a mixing method. However, in the mixing device used for the high-speed stirring and mixing method, the reaction liquid is mixed after being dropped into the reaction field, and is not directly introduced into the reaction field to which high shear force is applied and mixed. . In the mixing device used for the micro gap mixing method, the reaction liquid is supplied and mixed while applying a shearing force in a narrow reaction field, but the reaction liquid supply port is separated and instantaneous In terms of mixing, it was not sufficient. Furthermore, in Patent Document 4, Y-shaped and T-shaped mixing devices used for the high pressure mixing method are disclosed, but in these devices, the reaction liquid is collided in the pipe and mixed. Yes, it does not consider shear force. For this reason, it has been difficult for the method described in Patent Document 4 to obtain a noble metal colloid solution in which uniform noble metal fine particles having a small particle diameter are uniformly dispersed.

JP 2004-261735 A JP 2006-183092 A JP 2009-144250 A JP-A-2005-133135

  The present invention has been made in view of the above-mentioned problems of the prior art, and provides a noble metal colloid solution having excellent storage stability, in which uniform noble metal fine particles having a small particle diameter are uniformly dispersed, and a method for producing the same. The purpose is to provide.

  As a result of intensive research to achieve the above object, the present inventors have obtained two or more kinds of raw material solutions containing a precious metal ion and a polyalkylenimine having a predetermined molecular weight as raw materials for the precious metal-based fine particles. It has been found that by carrying out homogeneous mixing in a reaction field to which force is applied, a colloidal solution in which uniform noble metal fine particles having a small particle diameter are uniformly dispersed can be obtained, and the present invention has been completed.

That is, the noble metal colloid solution of the present invention has at least one noble metal fine particle selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles, and a weight average molecular weight of 3000 to 15000. A noble metal-based colloidal solution containing polyalkyleneimine, the pH of the colloidal solution is 2.5 to 6.0, and the fine particles dispersed in the colloidal solution have a cumulative mass in the particle size distribution of 50% become particle diameter _{D 50} is 0.8~10.0nm and cumulative mass is the noble metal-based fine particle size _{D 90} of at most 2.5 times the particle diameter _{D 50} which is 90%, and It is characterized by. Further, the noble metal colloid solution of the present invention is preferably one produced by the following method for producing a noble metal colloid solution of the present invention.

That is, the method for producing a noble metal-based colloidal solution of the present invention comprises at least one selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles by mixing two or more raw material solutions. A noble metal-based colloidal solution containing noble metal-based fine particles, wherein at least one of the two or more kinds of raw material solutions contains a noble metal ion that is a raw material of the noble metal-based fine particles, the 2 least one of or more of the raw material solution are those having a weight average molecular weight containing polyalkyleneimine 3000-15000, the the area marked 1100Sec ^-1 or 7500 sec ^-1 or less shear rate Introduce each raw material solution directly and mix homogeneously, and adjust the pH of the solution to 2.5-6.0 A method comprising Rukoto.

  In such a method for producing a noble metal colloid solution, at least one of the two or more kinds of raw material solutions contains the noble metal ion, and at least one of the remaining raw material solutions contains the polyalkylene. It is preferable that it contains imine, and it is more preferable that the raw material solution containing polyalkyleneimine further contains a reducing agent. The cation concentration of the raw material solution containing the noble metal ions is preferably 0.0001 to 0.5 mol / L.

The reason why a colloidal solution in which uniform noble metal-based fine particles having a small particle size are uniformly dispersed is obtained by the present invention is not necessarily clear, but the present inventors speculate as follows. That is, nanoparticles such as noble metal-based fine particles are likely to aggregate in an aqueous solution such as water, and usually a polymer dispersant is added and adsorbed to the nanoparticles to suppress aggregation. It is presumed that the polyalkyleneimine used in the present invention also adsorbs to the nanoparticles and suppresses aggregation. At this time, when a very high shearing force with a shear rate exceeding 7500 sec ⁻¹ is applied to the reaction field, aggregates having a large particle diameter tend to be formed. This is because the polyalkyleneimine is destroyed by excessive shearing force, so that even if the broken polyalkyleneimine is adsorbed to the nanoparticles, a sufficient repulsive force cannot be imparted in the liquid. It is inferred that the aggregates are aggregated.

  Further, when diethanolamine and polyethylene glycol are added, aggregates having a large particle size tend to be formed. This is because even when only polyethylene glycol is added, aggregates are formed in the liquid. However, when diethanolamine and polyethylene glycol are added, diethanolamine added to form noble metal-based fine particles is adsorbed to the generated noble metal-based fine particles. Since it inhibits the adsorption of polyethylene glycol, the effect of suppressing the aggregation by polyethylene glycol is further inferior, and even if diethanolamine is adsorbed to noble metal fine particles, sufficient steric hindrance is not exerted in the liquid, and the suppression of aggregation by diethanolamine It is presumed that the effect is not fully exhibited. In addition, the repulsive effect of polyethylene glycol is small and the amount of adsorption is small, so the repulsive effect is small, and the aggregates further agglomerate during storage of the noble metal-based colloid solution and the dispersibility in the liquid decreases. It is guessed.

  On the other hand, in the production method of the present invention, a polyalkyleneimine having a predetermined molecular weight is added and a shearing force is applied to the reaction field so that the shear rate becomes a predetermined value, so that the polyalkyleneimine is not destroyed. It is presumed that the noble metal fine particles are adsorbed on the noble metal fine particles and sufficient repulsive force is imparted to the noble metal fine particles in the liquid, and the noble metal fine particles are present in a uniformly dispersed state in the noble metal colloid solution. In addition, since polyalkyleneimine is stably present in a noble metal colloid solution, it is difficult to form aggregates having a large particle size, and the noble metal fine particles remain as they are or in a state of aggregates having a relatively small particle size. This is presumed to be stably dispersed in the colloidal solution.

  According to the present invention, it is possible to obtain a noble metal colloid solution having excellent storage stability in which uniform noble metal fine particles having a small particle diameter are uniformly dispersed.

It is a schematic longitudinal cross-sectional view which shows suitable one Embodiment of the manufacturing apparatus of the noble metal type colloid solution used for this invention. FIG. 2 is an enlarged longitudinal sectional view showing a tip portion (stirring portion) of the homogenizer 10 shown in FIG. 1. It is a side view of the inner side stator 13 shown in FIG. It is a cross-sectional view of the inner stator 13 shown in FIG. 2 is a high-resolution scanning transmission electron microscope photograph (high-resolution STEM photograph) showing a high-angle scattering dark field image (HAADF image) of the noble metal-based fine particles obtained in Example 1. FIG. 2 is a transmission electron micrograph (TEM photograph) showing an electron diffraction pattern of noble metal-based fine particles obtained in Example 1. FIG. 4 is a high-resolution scanning transmission electron microscope photograph (high-resolution STEM photograph) showing a high-angle scattering dark field image (HAADF image) of the noble metal-based fine particles obtained in Example 2. FIG. 3 is a transmission electron micrograph (TEM photograph) showing an electron diffraction pattern of noble metal-based fine particles obtained in Example 2. FIG. 6 is a high-resolution scanning transmission electron microscope photograph (high-resolution STEM photograph) showing a high-angle scattering dark field image (HAADF image) of the noble metal-based fine particles obtained in Example 3. FIG. 6 is a transmission electron micrograph (TEM photograph) showing an electron diffraction pattern of noble metal-based fine particles obtained in Example 3. FIG. 6 is a high-resolution scanning transmission electron micrograph (high-resolution STEM photograph) showing a high-angle scattering dark field image (HAADF image) of the noble metal-based fine particles obtained in Example 4. 6 is a transmission electron micrograph (TEM photograph) showing an electron diffraction pattern of noble metal-based fine particles obtained in Example 4. FIG. 6 is a high-resolution scanning transmission electron microscope photograph (high-resolution STEM photograph) showing a high-angle scattering dark field image (HAADF image) of the noble metal-based fine particles obtained in Example 5. FIG. 6 is a transmission electron micrograph (TEM photograph) showing an electron diffraction pattern of noble metal-based fine particles obtained in Example 5. FIG.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

First, the noble metal colloid solution of the present invention will be described. The noble metal colloid solution of the present invention includes at least one noble metal fine particle selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles, and a polyalkylene having a weight average molecular weight of 3000 to 15000. A noble metal-based colloidal solution containing imine, the pH of the colloidal solution is 2.5 to 6.0, and the fine particles dispersed in the colloidal solution have a cumulative mass of 50% in the particle size distribution and cumulative mass particle diameter _{D 50} is 0.8~10.0nm is the noble metal-based fine particle size _{D 90} of at most 2.5 times the particle diameter _{D 50} which is 90%, characterized in that It is what.

  The noble metal fine particles according to the present invention are at least one kind of fine particles selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles. Examples of the noble metal that forms such noble metal fine particles include gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), ruthenium (Ru), osmium ( Os). These noble metals may be used alone to form noble metal fine particles, or two or more may form noble metal alloy fine particles. Among these noble metal fine particles, fine particles made of gold, silver, platinum, palladium, rhodium, iridium, or alloys thereof are preferable from the viewpoint of exhibiting excellent catalytic activity.

  Moreover, in the noble metal colloid solution of the present invention, fine particles of a noble metal alloy of the noble metal and a metal other than the noble metal can be used as the noble metal fine particles. Examples of the metal other than the noble metal include iron, nickel, cobalt, copper, manganese, chromium, zinc, niobium, molybdenum, tantalum, and tungsten. These metals may be used alone or in combination of two or more.

  Further, the noble metal fine particles according to the present invention include fine particles of noble metal compounds such as oxides, hydroxides, salts, carbides, nitrides and sulfides of the noble metals; oxides, hydroxides and salts of the noble metal alloys. Fine particles of noble metal alloy compounds such as carbides, nitrides and sulfides can also be used. The noble metal alloy compound means a composite metal compound such as a composite metal oxide containing at least one kind of noble metal.

The noble metal-based colloid solution of the present invention is a dispersion of such noble metal-based fine particles. The particle size distribution of the fine particles in the noble metal-based colloid solution can be measured by, for example, a dynamic light scattering method. Particles in the colloidal solution of the present invention, the particle diameter _{D 50} which cumulative mass in measured particle size distribution in this way is 50 percent 0.8～10.0Nm (preferably 0.8～5.0Nm, More preferably 0.8 to 3.0 nm) and a particle diameter D ₉₀ with a cumulative mass of 90% is 2.5 times or less (preferably 2.0 times or less) of the particle diameter D _50. . Such noble metal fine particles having particle diameters D ₅₀ and D ₉₀ are uniformly dispersed in the colloidal solution. By using such a noble metal-based colloidal solution, uniform noble metal-based catalyst particles having a small particle diameter can be obtained, and when the noble metal-based catalyst particles are used as a catalyst, the particle growth is difficult and the catalytic activity is improved. It is possible to suppress the decrease. Further, when the noble metal-based fine particles are supported on the composite oxide aggregated particles having an alumina skeleton, the composite oxide aggregated particles (catalyst support) are changed by changing the pore diameter of the composite oxide aggregated particles having the alumina skeleton. It is possible to arbitrarily control the pore size distribution. Therefore, by using the noble metal colloidal solution of the present invention at the time of catalyst preparation, it becomes possible to design an ideally shaped catalyst according to the operating temperature range of the catalyst, for example, optimal for gas diffusivity. It is possible to obtain a highly heat-resistant catalyst having a pore size, in which noble metal-based fine particles are uniformly arranged in the pores of the catalyst carrier and having ideal catalytic activity in the diffusion-controlled region.

  The noble metal colloid solution of the present invention contains a polyalkyleneimine having a predetermined molecular weight. Due to the presence of such polyalkyleneimine in the colloidal solution, the noble metal-based fine particles have a positively charged surface, so that they are less likely to aggregate and are stably dispersed in the colloidal solution in a uniform state. Is possible. In addition, since the surface of the noble metal fine particles is positively charged, an electrostatic attractive force acts on the negatively charged carrier and a repulsive force acts on the positively charged carrier. It is possible to adsorb noble metal-based fine particles. For example, when a noble metal is adsorbed on a composite oxide support of alumina and ceria, in the conventional method, the surface of the noble metal adsorbed on the alumina tends to move, and therefore the catalytic activity tends to decrease due to the noble metal grain growth. When the noble metal colloid solution of the present invention is used, the surface of the noble metal fine particles is positively charged by the action of the polyalkyleneimine, so that the surface of the ceria fine particles is negatively charged and the surface of the alumina fine particles is positively charged. Thus, the noble metal-based fine particles can be selectively adsorbed on the ceria fine particles, the noble metal particle growth is less likely to occur, and the decrease in the catalytic activity is suppressed.

  The weight average molecular weight of such a polyalkyleneimine is 3000-15000. When the weight average molecular weight of the polyalkyleneimine is within the above range, the noble metal fine particles have a small particle size, are uniform, hardly aggregate, are uniformly dispersed, and obtain a noble metal colloid solution having excellent storage stability. Can do. On the other hand, when the weight average molecular weight of the polyalkyleneimine is less than the lower limit, even if the polyalkyleneimine is adsorbed to the noble metal fine particles, the repulsive force due to steric hindrance is not sufficiently expressed, and the noble metal fine particles are aggregated, while the upper limit is exceeded. If it exceeds, polyalkyleneimine forms a crosslinked structure, and the noble metal-based fine particles aggregate to form large aggregates. Therefore, from such a viewpoint, the weight average molecular weight of the polyalkyleneimine is preferably 8000 to 12000. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

In colloidal solution of the present invention, the content of the polyalkyleneimine is preferably 0.5 to 30 mg / ^{m 2} with respect to the unit surface area of the noble metal particles, and more preferably 2 to 20 mg / ^{m 2.} When the content of the polyalkyleneimine is within the above range, the noble metal-based fine particles have a small particle size, are uniform, hardly aggregate, are uniformly dispersed, and can provide a noble metal-based colloid solution with excellent storage stability. it can. On the other hand, when the content of the polyalkyleneimine is less than the lower limit, the surface of the noble metal fine particles cannot be sufficiently covered with the polyalkyleneimine, and the noble metal fine particles tend to aggregate to form larger aggregates. On the other hand, if the upper limit is exceeded, a large amount of free polyalkyleneimine is present in the noble metal colloid solution, so that the cross-linking reaction of the polyalkyleneimine proceeds remarkably, and the noble metal fine particles are aggregated and aggregated with a large particle size. There is a tendency for aggregates to form.

The colloidal solution of the present invention has a pH of 2.5 to 6.0. When the pH of the colloidal solution is in the above range, the polyalkyleneimine dissociates to form NH ₃ ⁺ groups, which are adsorbed on the negatively charged sites or neutral sites of the noble metal-based fine particles and impart a dispersion effect. As a result, the noble metal-based fine particles have a small particle size, are uniform, hardly aggregate, are uniformly dispersed, and a noble metal-based colloidal solution having excellent storage stability can be obtained. On the other hand, when the pH is lower than the lower limit, the reduction reaction rate decreases, and the polyalkyleneimine is adsorbed to the intermediate product in the middle of the reaction. On the other hand, when the above upper limit is exceeded, the degree of dissociation of the polyalkyleneimine is small, the amount of polyalkyleneimine adsorbed on the noble metal fine particles is reduced, and no sufficient repulsive force is expressed between the noble metal fine particles, causing the noble metal fine particles to aggregate. To do.

  Examples of the solvent used in the colloidal solution of the present invention include water, water-soluble organic solvents (methanol, ethanol, propanol, isopropanol, butanol, acetone, etc.), a mixed solvent of water and the water-soluble organic solvent, and the like. The polyalkyleneimine according to the present invention tends to exhibit an excellent dispersion effect when such a solvent is used.

Such a noble metal-based colloid solution is, for example, a reaction in which a shearing force is applied to a raw material solution containing the noble metal ion and a raw material solution containing the polyalkyleneimine so that a shear rate is 1100 sec ⁻¹ or more. It can be produced by in-situ mixing. The colloidal solution of the present invention is a method of mixing two or more kinds of raw material solutions, wherein at least one of the two or more kinds of raw material solutions contains the noble metal ion, and the two or more kinds are used. at least one as used those containing the polyalkyleneimine, homogeneous introduced directly into these independently raw material solution in an area that is the 1100Sec ^-1 or 7500 sec ^-1 or less shear rate of the raw material solution It can be produced by a mixing method. In particular, when making a colloidal solution in a relatively high range (1800 sec ^-1 or 7500 sec ^-1 or less) in the allowable shear rate, in a solvent in which the noble metal-based particles are likely to aggregate, such as water, to coagulate the noble metal particles Without being distributed uniformly.

  As an apparatus used for such a manufacturing method, for example, the apparatus shown in FIG. Hereinafter, a suitable apparatus for producing the noble metal colloid solution of the present invention will be described in detail with reference to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions may be omitted.

  The manufacturing apparatus shown in FIG. 1 includes a homogenizer 10 as a stirring device, and a front end portion (stirring portion) of the homogenizer 10 is disposed in the reaction vessel 20. As shown in FIG. 2, the front end of the homogenizer 10 includes a concave outer stator 12 disposed so that a predetermined gap region is formed between the concave rotor 11 and the outer periphery of the rotor 11, and the rotor. 11 and a convex inner stator 13 arranged so that a predetermined gap region is formed between the inner periphery of the inner stator 11 and the inner periphery. Further, the rotor 11 is connected to a motor 15 via a rotating shaft 14 and has a structure capable of rotating.

  In the manufacturing apparatus shown in FIG. 1, a plurality of nozzles, that is, a nozzle 16 </ b> A for introducing the raw material solution A and a nozzle 16 </ b> B for introducing the raw material solution B are opposed to the rotor 11 in the inner stator 13. It is provided on each surface. Further, a supply device (not shown) for the raw material solution A is connected to the nozzle 16A via a flow path 17A, and a supply device (not shown) for the raw material solution B is connected to the nozzle 16B via a flow path 17B. The raw material solution A and the raw material solution B can be directly and independently introduced into the region between the rotor 11 and the inner stator 13.

  Further, in the manufacturing apparatus shown in FIG. 1, as shown in FIGS. 3 and 4, the nozzle 16 </ b> A and the nozzle 16 </ b> B are orthogonal to the rotation axis X of the rotor 11 on the surface facing the rotor 11 in the inner stator 13. The predetermined surfaces Y are alternately provided in the outer peripheral direction.

  3 and 4, 12 nozzles 16A and 12 nozzles 16B are provided (24-hole type), but the number of nozzles 16A and nozzles 16B is not particularly limited. Therefore, it is only necessary to provide one nozzle 16A and one nozzle 16B (two-hole type), but the time from when the raw material solution A and the raw material solution B are introduced into the region until homogeneous mixing is further reduced. From the viewpoint of being able to do so, the number of nozzles 16A and nozzles 16B is preferably 10 or more, and more preferably 20 or more. On the other hand, the upper limit of the number of each of the nozzles 16A and 16B is not particularly limited and varies depending on the size of the apparatus. From the viewpoint of more reliably preventing nozzle clogging, the alternately arranged nozzles 16A It is preferable that the diameter of the opening of the nozzle 16B can be about 0.1 mm or more. As described above, the diameter of the opening of the nozzle is not particularly limited and varies depending on the size of the apparatus, but is preferably about 0.1 to 1 mm from the viewpoint of more reliably preventing nozzle clogging. .

  3 and 4, the nozzles 16A and the nozzles 16B are alternately provided in a row in the outer circumferential direction of one surface Y orthogonal to the rotation axis X of the rotor 11. It may be provided alternately in a plurality of rows in the outer circumferential direction.

In the manufacturing apparatus shown in FIG. 1 described above, regions where the raw material solution A and the raw material solution B are respectively introduced from the nozzle 16A and the nozzle 16B, that is, the inner periphery of the rotor 11 and the inner stator 13 in FIGS. in the region between the outer periphery of, preferably shear rate is 1100Sec ^-1 or more, and more preferably 1800 sec ^-1 or more. When the shear rate in this region is less than the lower limit, sufficient shearing force is not applied to the reaction field, aggregated noble metal-based fine particles are not separated, and large aggregates tend to be formed. Moreover, it is preferable that the shear rate of the said area | region is 7500 sec < ^-1 > or less, and it is more preferable that it is 6500 sec < ^-1 > or less. When the shear rate exceeds the upper limit, the polyalkyleneimine is destroyed and sufficient repulsive force cannot be applied to the noble metal-based fine particles, and a larger aggregate tends to be formed.

  Conditions for achieving such a range of shear rates are affected by the rotational speed of the rotor and the size of the gap between the rotor and the stator. Need to be set. The specific rotation speed of the rotor 11 is not particularly limited and varies depending on the size of the device. For example, the outer diameter of the inner stator 13 is 10 mm, the gap between the rotor 11 and the outer stator 12 is 0.2 mm, In the case of a gap of 0.2 mm between the rotor 11 and the inner stator 13, the shear speed can be achieved by setting the rotational speed of the rotor 11 to preferably 600 to 4000 rpm, more preferably 1000 to 3500 rpm. It becomes possible.

  Further, the size of the gap between the rotor 11 and the inner stator 13 is not particularly limited, and varies depending on the size of the device, but is preferably 0.2 to 1.0 mm, 0.5 to 1 More preferably, it is 0.0 mm. Further, the size of the gap between the rotor 11 and the outer stator 12 is not particularly limited, and varies depending on the size of the device, but is preferably 0.2 to 1.0 mm, 0.5 to 1 More preferably, it is 0.0 mm. By adjusting the rotational speed of the rotor 11 in response to the change in the size of the gap, it becomes possible to achieve the shear speed in the above range. When these gaps are less than the lower limit, clogging of the gaps tends to occur, and when the upper limit is exceeded, effective shearing force cannot be applied.

  Further, in the manufacturing apparatus shown in FIG. 1, the raw material solution A and the raw material solution B respectively supplied from the nozzle 16A and the nozzle 16B are introduced within 1 msec (particularly preferably within 0.5 msec) after being introduced into the region. It is preferable that the nozzle 16A and the nozzle 16B are arranged so as to be homogeneously mixed. Here, the time from when the raw material solution is introduced into the region until it is homogeneously mixed is the nozzle 16B adjacent to the raw material solution A (or raw material solution B) introduced from the nozzle 16A (or nozzle 16B). It means the time until the position of (or nozzle 16A) is reached and mixed with raw material solution B (or raw material solution A) introduced from nozzle 16B (or nozzle 16A).

  Although the apparatus suitably used for the production of the noble metal colloid solution of the present invention has been described above, the method for producing the colloid solution of the present invention is not limited to the method using the production apparatus shown in FIG. For example, the manufacturing apparatus shown in FIG. 1 is configured so that two kinds of raw material solutions can be introduced, but a nozzle, a raw material solution supply apparatus, or the like may be configured so that three or more kinds of raw material solutions can be introduced. Good.

  Further, in the manufacturing apparatus shown in FIG. 1, the nozzle 16 </ b> A and the nozzle 16 </ b> B are respectively provided on the surface facing the rotor 11 in the inner stator 13, but the nozzle 16 </ b> A and the nozzle 16 </ b> B are respectively rotors in the outer stator 12. 11 may be provided respectively on the surface facing 11. If comprised in that way, it will become possible to introduce the raw material solution A and the raw material solution B directly into the area | region between the rotor 11 and the outer side stator 12, respectively independently. Note that the shear rate in that region needs to be set so as to satisfy the above condition.

  Furthermore, as described above, if a shearing force that gives a predetermined shear rate to the reaction field can be applied to the reaction field, for example, two or more kinds of raw material solutions can be homogeneously mixed using a stirrer or the like. Good.

  Next, a preferred embodiment of the method for producing a noble metal colloid solution of the present invention will be described. In the method for producing a noble metal colloid solution of the present invention, it is preferable that the shear rate of the region into which the raw material solution is introduced is set in the above range, and each of the raw material solutions is directly and independently introduced into the region. For example, when the manufacturing apparatus shown in FIG. 1 is used, regions where the raw material solution A and the raw material solution B are respectively introduced from the nozzle 16A and the nozzle 16B, that is, the rotor 11 and the inner stator 13 in FIG. 1 and FIG. The rotor 11 is rotated so that the shear rate in the region between the above ranges is within the above range, and the raw material solution A and the raw material solution B are directly introduced into the region independently from the nozzle 16A and the nozzle 16B, respectively. Thus, each raw material solution directly introduced into the region where the shear rate is a predetermined value is homogeneously mixed in a very short time to complete the reaction, and the noble metal system derived from the raw material in the raw material solution Fine particles are obtained. The noble metal fine particles obtained by such a method have a smaller particle size and a narrower particle size distribution.

  Moreover, there is no restriction | limiting in particular as a liquid feeding rate of each raw material solution, However, 1.0-30 ml / min is preferable. When the feed rate of the raw material solution is less than the lower limit, the production efficiency of the noble metal-based fine particles tends to decrease, and when the upper limit is exceeded, the aggregate particle diameter of the noble metal-based fine particles in the liquid tends to increase.

In the method for producing a colloidal solution of the present invention, the pH of the noble metal-based colloidal solution is adjusted to 2.5 to 6.0. When the pH of the colloidal solution is within the above range, the polyalkyleneimine dissociates to form NH ₃ ⁺ groups, which are adsorbed on the negatively charged sites or neutral sites of the noble metal-based fine particles and impart a dispersion effect. As a result, the noble metal-based fine particles have a small particle size, are uniform, hardly aggregate, are uniformly dispersed, and a noble metal-based colloidal solution having excellent storage stability can be obtained. On the other hand, when the pH is lower than the lower limit, the reduction reaction rate decreases, and the polyalkyleneimine is adsorbed to the intermediate product in the middle of the reaction. On the other hand, when the above upper limit is exceeded, the degree of dissociation of the polyalkyleneimine is small, the amount of polyalkyleneimine adsorbed on the noble metal fine particles is reduced, and no sufficient repulsive force is expressed between the noble metal fine particles, causing the noble metal fine particles to aggregate. To do.

  When producing the noble metal-based colloidal solution of the present invention, the noble metal ion and the polyalkyleneimine may be contained in the same raw material solution, or may be contained in different raw material solutions. It is preferable that at least one of the plurality of raw material solutions contains the noble metal ion, and at least one of the remaining raw material solutions contains the polyalkyleneimine. Furthermore, reducing agents such as hydrazine and sodium borohydride are not included in the same raw material solution as the noble metal ions, but may be included in the same raw material solution as the polyalkyleneimine. For example, when the manufacturing apparatus shown in FIG. 1 is used, both the noble metal ion and the polyalkyleneimine may be contained in the raw material solution A, or the raw material solution A contains the noble metal ion and the raw material solution B. May contain the polyalkyleneimine, but the latter is preferred.

  The cation concentration of the raw material solution containing the noble metal ions (for example, the raw material solution A) is preferably 0.0001 to 0.5 mol / L, and more preferably 0.0001 to 0.2 mol / L. When the cation concentration is in the above-mentioned range, the noble metal-based fine particles have a small particle size, are uniform, hardly aggregate, are uniformly dispersed, and a noble metal-based colloid solution having excellent storage stability can be obtained. On the other hand, when the cation concentration is less than the lower limit, the yield of the noble metal-based fine particles tends to decrease. On the other hand, when the cation concentration exceeds the upper limit, the distance between the noble metal-based fine particles in the colloidal solution is shortened. It cannot be adsorbed to the noble metal fine particles in an effective form, and the noble metal fine particles tend to aggregate.

  The reaction system applicable to the production of such a noble metal colloidal solution of the present invention is not particularly limited, and examples thereof include hydrolysis reactions of alkoxides and precipitation reactions utilizing solubility changes using poor solvents. Even in a reaction with a very fast nucleation rate or reaction rate such as a summation reaction or oxidation-reduction reaction, the noble metal-based fine particles have a small particle size and are uniform according to the above-mentioned production method, and are excellent in dispersibility and storage stability. Since the solution is obtained, the production method of the present invention is particularly useful for such a reaction system having a very high nucleation rate and reaction rate.

A specific reaction system in such neutralization reaction, oxidation-reduction reaction, etc. is not particularly limited, but an oxidation-reduction reaction system is preferable. For example, when two kinds of raw material solutions are used, the following reaction system is used. A redox reaction system using raw material solutions A and B is more preferable.
Raw material solution A (precious metal ion-containing solution): A solution containing silver nitrate, palladium nitrate, chloroplatinic acid, rhodium nitrate, dinitrodiammine platinum nitrate (hereinafter referred to as “platinum nitrate”), and the like.
Raw material solution B (reducing agent): acetaldehyde solution, sodium borohydride solution, hydrazine, ethanol and the like.

  The polyalkyleneimine may be contained in at least one of the raw material solution A and the raw material solution B in any of the above reactions, but is preferably contained in the raw material solution B. For example, in the oxidation-reduction reaction, it is preferable to use a raw material solution A containing noble metal ions, which are raw materials of noble metal-based fine particles, and a raw material solution B containing a reducing agent and a polyalkyleneimine.

  The composition and combination of such raw material solutions can be appropriately set according to the type of the target noble metal colloid solution and the type of raw material used.

  The composition of the noble metal-based colloidal solution obtained by the method for producing a colloidal solution of the present invention is not particularly limited. By using various raw material solutions, noble metal-based noble metals, noble metal alloys, noble metal compounds, noble metal alloy compounds, and the like are used. A colloidal solution can be obtained.

  In addition, the noble metal colloid solution of the present invention is highly dispersible in the liquid, and the noble metal fine particles are supported on the catalyst carrier in a highly dispersed state by being homogeneously mixed with the highly dispersible catalyst carrier colloid solution. Can do. Furthermore, in the noble metal colloid solution of the present invention, the polyalkyleneimine can be instantaneously desorbed from the noble metal fine particles by adjusting the pH, so that the noble metal fine particles are easily supported evenly on the catalyst support. It becomes possible to make it. In addition, when the catalyst carrier is prepared using a metal oxide or composite metal oxide colloidal solution prepared in the same manner as the noble metal colloid solution of the present invention, the metal oxide particles or composite metal which is the catalyst carrier. Since the polyalkyleneimine can be instantaneously desorbed from the oxide particles, the noble metal-based fine particles can be supported in a more uniform state.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
First, ion-exchanged water is added to 4.85 g of a platinum nitrate solution having a Pt content of 4.565% by mass, and a noble metal ion-containing raw material aqueous solution (raw material solution A) having a cation (Pt ion) concentration of 0.0025 mol / L. ) 125 ml was prepared. Further, 0.95 g of hydrazine monohydrate and the following formula (1):

Ion-exchanged water was added to a mixture of polyethyleneimine 0.2 g having a weight average molecular weight of 10000 represented by the formula (1) and dissolved to prepare 125 ml of a polyethyleneimine aqueous solution (raw material solution B). A small amount of nitric acid was added to the polyethyleneimine aqueous solution so that the pH after mixing with the noble metal ion-containing raw material aqueous solution was 3.0.

  Next, a noble metal colloid solution was prepared using the manufacturing apparatus (super agitation reactor) shown in FIG. The stator 13 was a 48-hole type in which 24 nozzles 16A and 24 nozzles 16B were provided.

  As shown in FIG. 1, the tip of the homogenizer 10 is set so as to be immersed in a 100 ml beaker 20, and the raw material solution A and the raw material solution B are put together while rotating the rotor 11 in the homogenizer 10 at a rotational speed of 3200 rpm. Using a tube pump (not shown) at a supply rate of 2.5 ml / min, the solution is fed from the nozzle 16A and the nozzle 16B to the region between the rotor 11 and the inner stator 13 and mixed to obtain a noble metal colloid solution. Produced.

The outer diameter of the rotor 11 was 17.8 mm, the gap between the rotor 11 and the outer stator 12 was 0.5 mm, and the shear rate in the region between them was 6000 sec ⁻¹ . The outer diameter of the inner stator 13 was 12.2 mm, the gap between the rotor 11 and the inner stator 13 was 0.2 mm, and the shear rate in the region between them was 6000 sec ⁻¹ . Furthermore, the time from when the raw material solution A and the raw material solution B were introduced into the region until they were homogeneously mixed was 0.394 msec. Here, the time until homogeneous mixing is defined as the time until the raw material solution A or the raw material solution B discharged from the nozzle 16A or the nozzle 16B reaches the adjacent nozzle 16B or the nozzle 16A by the rotation of the rotor 11. It is what is done.

  The noble metal colloidal solution overflowing from the beaker 20 was received by setting a 1 L beaker (not shown) further below the beaker 20.

  The pH of the obtained noble metal colloid solution is shown in Table 1. In addition, several drops of the noble metal colloid solution were dropped on the carbon support film and observed with a high resolution scanning transmission electron microscope (high resolution STEM, “JEM2100F-Cs collector” manufactured by JEOL Ltd.). The result is shown in FIG. 5A. Moreover, the electron beam diffraction pattern was measured using the transmission electron microscope. FIG. 5B shows an electron diffraction image of the noble metal-based fine particles. When the measured value obtained from this electron beam diffraction image was compared with the theoretical value for the distance between hkl planes, it was confirmed that the fine particles contained in the noble metal colloid solution were platinum fine particles (see Table 2).

Next, the particle size distribution of the fine particles in this noble metal colloid solution was measured by a dynamic light scattering method (using “Nanotrac 250” manufactured by Nikkiso Co., Ltd.). The noble metal particle diameter D ₅₀ cumulative mass from the particle size distribution of the particles in the colloidal solution is 50% _(average particle diameter) and cumulative mass was determined particle diameter D ₉₀ which is 90%. Further, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal-based colloid solution that was allowed to stand for 30 days, and the particle size D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Example 2)
First, ion-exchanged water was added to 2.71 g of a palladium nitrate solution having a Pd content of 8.2% by mass to prepare 125 ml of a noble metal ion-containing raw material aqueous solution having a cation (Pd ion) concentration of 0.0025 mol / L. . Also, ion-exchanged water was added to a mixture of 0.95 g of sodium borohydride and 0.2 g of polyethyleneimine having a weight average molecular weight of 10000 represented by the above formula (1) to dissolve them to prepare 125 ml of a polyethyleneimine aqueous solution. did. A small amount of nitric acid was added to the polyethyleneimine aqueous solution so that the pH after mixing with the noble metal ion-containing raw material aqueous solution was 5.5.

  Next, a noble metal colloid solution was prepared using the manufacturing apparatus shown in FIG. 1 in the same manner as in Example 1 except that the noble metal ion-containing raw material aqueous solution and the polyethyleneimine aqueous solution were used as the raw material solutions A and B, respectively. .

  The pH of the obtained noble metal colloid solution is shown in Table 1. The fine particles in the noble metal colloid solution were observed with a high resolution STEM and identified with an electron diffraction pattern in the same manner as in Example 1. The results are shown in FIGS. When the measured value and the theoretical value of the hkl interplane distance were compared in the same manner as in Example 1, it was confirmed that the fine particles contained in the noble metal colloid solution were palladium fine particles (see Table 3).

Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution is measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass becomes 50% and the particle diameter at which the cumulative mass becomes 90%. D ₉₀ was determined. In addition, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal-based colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Example 3)
First, ion exchange water was added to 8.07 g of a rhodium nitrate solution having a Rh content of 2.75% by mass to prepare 125 ml of a noble metal ion-containing raw material aqueous solution having a cation (Rh ion) concentration of 0.0025 mol / L. . Also, ion-exchanged water was added to a mixture of 0.95 g of sodium borohydride and 0.2 g of polyethyleneimine having a weight average molecular weight of 10000 represented by the above formula (1) to dissolve them to prepare 125 ml of a polyethyleneimine aqueous solution. did. A small amount of nitric acid was added to the polyethyleneimine aqueous solution so that the pH after mixing with the noble metal ion-containing raw material aqueous solution was 5.5.

  Next, a noble metal colloid solution was prepared using the manufacturing apparatus shown in FIG. 1 in the same manner as in Example 1 except that the noble metal ion-containing raw material aqueous solution and the polyethyleneimine aqueous solution were used as the raw material solutions A and B, respectively. .

  The pH of the obtained noble metal colloid solution is shown in Table 1. The fine particles in the noble metal colloid solution were observed with a high resolution STEM and identified with an electron diffraction pattern in the same manner as in Example 1. The results are shown in FIGS. When the measured value and the theoretical value of the hkl interplane distance were compared in the same manner as in Example 1, it was confirmed that the fine particles contained in the noble metal colloid solution were rhodium fine particles (see Table 4).

Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution is measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass becomes 50% and the particle diameter at which the cumulative mass becomes 90%. D ₉₀ was determined. In addition, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal-based colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

Example 4
First, nitric acid and ion-exchanged water were added to 0.106 g of silver nitrate to prepare 125 ml of a noble metal ion-containing raw material aqueous solution having a cation (Ag ion) concentration of 0.0025 mol / L. Also, ion-exchanged water was added to a mixture of 0.95 g of sodium borohydride and 0.2 g of polyethyleneimine having a weight average molecular weight of 10000 represented by the above formula (1) to dissolve them to prepare 125 ml of a polyethyleneimine aqueous solution. did. A small amount of nitric acid was added to the polyethyleneimine aqueous solution so that the pH after mixing with the noble metal ion-containing raw material aqueous solution was 5.5.

  Next, a noble metal colloid solution was prepared using the manufacturing apparatus shown in FIG. 1 in the same manner as in Example 1 except that the noble metal ion-containing raw material aqueous solution and the polyethyleneimine aqueous solution were used as the raw material solutions A and B, respectively. .

  The pH of the obtained noble metal colloid solution is shown in Table 1. The fine particles in the noble metal colloid solution were observed with a high resolution STEM and identified with an electron diffraction pattern in the same manner as in Example 1. The results are shown in FIGS. When the measured value and the theoretical value of the hkl interplane distance were compared in the same manner as in Example 1, it was confirmed that the fine particles contained in the noble metal colloid solution were silver oxide fine particles (see Table 5).

Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution is measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass becomes 50% and the particle diameter at which the cumulative mass becomes 90%. D ₉₀ was determined. In addition, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal-based colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Example 5)
First, ion-exchanged water was added to a mixture of 4.86 g of a platinum nitrate solution having a Pt content of 4.565% by mass and 1.61 g of a rhodium nitrate solution having an Rh content of 2.75% by mass to obtain a cation (Pt Ion / Rh ion = 5: 1) 125 ml of a noble metal ion-containing raw material aqueous solution having a concentration of 0.0030 mol / L was prepared. Also, ion-exchanged water was added to a mixture of 0.95 g of sodium borohydride and 0.2 g of polyethyleneimine having a weight average molecular weight of 10000 represented by the above formula (1) to dissolve them to prepare 125 ml of a polyethyleneimine aqueous solution. did. A small amount of nitric acid was added to the polyethyleneimine aqueous solution so that the pH after mixing with the noble metal ion-containing raw material aqueous solution was 5.5.

  Next, a noble metal alloy colloid solution was prepared using the production apparatus shown in FIG. 1 in the same manner as in Example 1 except that the noble metal ion-containing raw material aqueous solution and the polyethyleneimine aqueous solution were used as the raw material solutions A and B, respectively. .

  Table 1 shows the pH of the obtained noble metal alloy colloid solution. Further, the fine particles in the noble metal alloy colloid solution were observed with a high resolution STEM and identified with an electron diffraction pattern in the same manner as in Example 1. The results are shown in FIGS. When the measured value and the theoretical value of the hkl interplane distance were compared in the same manner as in Example 1, it was confirmed that the fine particles contained in the noble metal alloy colloid solution were platinum / rhodium alloy fine particles (see Table 6).

Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal alloy colloid solution is measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass becomes 50% and the particle diameter at which the cumulative mass becomes 90%. D ₉₀ was determined. In addition, the particle size distribution of the fine particles of the noble metal alloy colloid solution that was allowed to stand for 30 days was measured in the same manner as described above, and the particle size D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

Example 6
A noble metal-based colloidal solution was prepared in the same manner as in Example 1 except that the rotation speed of the rotor 11 was changed to 600 rpm. In this case, the shear rate in the region between the rotor 11 and the outer stator 12 was 1100 sec ⁻¹ , and the shear rate in the region between the rotor 11 and the inner stator 13 was 1100 sec ⁻¹ . Further, the time from when the raw material solution A and the raw material solution B were introduced into the region until they were homogeneously mixed was 2.1 msec.

The pH of the obtained noble metal colloid solution is shown in Table 1. Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution was measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass was 50% and the particle diameter at which the cumulative mass was 90%. D ₉₀ was determined. Further, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Comparative Example 1)
4.85 g of platinum nitrate solution having a Pt content of 4.565% by mass, 0.95 g of hydrazine monohydrate, and 3.2 g of polyvinylpyrrolidone having a weight average molecular weight of 10,000 represented by the above formula (1) are ion-exchanged water. The mixture was added to 250 ml, and propeller stirring was performed at 300 rpm for 12 hours to prepare a noble metal colloid solution. The amount of platinum nitrate solution added is such that the cation (Pt ion) concentration before colloid formation is 0.0025 mol / L.

The pH of the obtained noble metal colloid solution is shown in Table 1. Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution was measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass was 50% and the particle diameter at which the cumulative mass was 90%. D ₉₀ was determined. Further, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Comparative Example 2)
A noble metal colloid solution was prepared in the same manner as in Comparative Example 1 except that polyvinylpyrrolidone was not used. The pH of the obtained noble metal colloid solution is shown in Table 1. Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution was measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass was 50% and the particle diameter at which the cumulative mass was 90%. D ₉₀ was determined. Further, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Comparative Example 3)
A noble metal colloid solution was prepared in the same manner as in Example 1 except that 0.2 g of polyethyleneimine having a weight average molecular weight of 1800 was used instead of polyethyleneimine having a weight average molecular weight of 10,000. The pH of the obtained noble metal colloid solution is shown in Table 1. Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution was measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass was 50% and the particle diameter at which the cumulative mass was 90%. D ₉₀ was determined. Further, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

(Comparative Example 4)
A noble metal-based colloidal solution was prepared in the same manner as in Example 1 except that the rotation speed of the rotor 11 was changed to 300 rpm. In this case, the shear rate in the region between the rotor 11 and the outer stator 12 was 550 sec ⁻¹ , and the shear rate in the region between the rotor 11 and the inner stator 13 was 550 sec ⁻¹ . Further, the time from when the raw material solution A and the raw material solution B were introduced into the region until they were homogeneously mixed was 4.2 msec.

The pH of the obtained noble metal colloid solution is shown in Table 1. Further, in the same manner as in Example 1, the particle size distribution of the fine particles in the noble metal colloid solution was measured, and the particle diameter D ₅₀ (average particle diameter) at which the cumulative mass was 50% and the particle diameter at which the cumulative mass was 90%. D ₉₀ was determined. Further, the particle size distribution of the fine particles was measured in the same manner as described above for the noble metal colloid solution that was allowed to stand for 30 days, and the particle diameter D _{50 at} which the cumulative mass was 50% was determined. These results are shown in Table 1.

And As is apparent from the results shown in Table 1, a weight average molecular weight is added polyalkyleneimine 3000-15000, direct a raw material solution separately in a region that is the 1100Sec ^-1 or 7500 sec ^-1 or less shear rate In the noble metal colloid solutions of the present invention obtained by introduction and homogeneous mixing (Examples 1 to 6), it was confirmed that noble metal fine particles having an average particle size of nano order and a narrow particle size distribution are dispersed. It was done. Further, this noble metal colloid solution was excellent in storability without any change in the average particle diameter of the noble metal fine particles even after being stored for 30 days.

  On the other hand, when a polyalkyleneimine having a weight average molecular weight of less than 3000 was added (Comparative Example 3), the average particle diameter was in the micron order. This is presumably because the noble metal-based fine particles have a high cohesive force in water, and thus easily aggregate, and a sufficient repulsive force did not act in the liquid.

Further, when the polyalkyleneimine according to the present invention is not added (Comparative Example 1), when polyvinylpyrrolidone is used instead of the polyalkyleneimine (Comparative Example 2), and the region where the shear rate is less than 1100 sec ⁻¹ In the case where the raw material solution was directly introduced independently and mixed homogeneously (Comparative Example 4), it was found that noble metal-based fine particles having a large average particle size but a wide particle size distribution were formed although the average particle size was nano-order. . Furthermore, when stored for 30 days, the average particle diameter of the noble metal-based fine particles was large, and the storage stability was poor. This is presumably because noble metal-based fine particles have a high cohesive force in water and thus easily aggregate, and in the case of Comparative Example 2, polyvinyl pyrrolidone is not adsorbed to such fine particles in an effective form. In the case of Comparative Example 4, it is presumed that sufficient mechanical and physical stress that aggregates after the reduction reaction and breaks the aggregates was not applied.

  As described above, according to the present invention, it is possible to obtain a noble metal-based colloid solution excellent in storage stability in which noble metal-based fine particles having a small particle size and a narrow particle size distribution are uniformly dispersed.

  Therefore, since the noble metal-based colloid solution of the present invention is a nano-sized highly dispersed noble metal-based fine particle, for example, by supporting the noble metal-based fine particle on the catalyst carrier using such a noble metal-based colloid solution. In addition, it is possible to obtain a noble metal catalyst supported in a state in which noble metal fine particles are highly dispersed. A catalyst in which such noble metal-based fine particles are highly dispersed is expected to exhibit a nano-size effect and is useful as a noble metal-based catalyst having excellent catalytic activity.

  DESCRIPTION OF SYMBOLS 10 ... Homogenizer, 11 ... Rotor, 12 ... Outer stator, 13 ... Inner stator, 14 ... Rotating shaft, 15 ... Motor, 16A, 16B ... Nozzle, 17A, 17B ... Flow path (supply pipe), 20 ... Reaction vessel, A , B ... reaction solution, X ... rotation axis, Y ... surface perpendicular to the rotation axis X.

Claims (9)

Noble metal colloid solution containing at least one kind of noble metal fine particles selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles, and a polyalkyleneimine having a weight average molecular weight of 3000 to 15000 And
The pH of the colloidal solution is 2.5-6.0,
Particulates dispersed in said colloidal solution is, the particle diameter _{D 90} of and cumulative mass is a particle diameter _{D 50} which cumulative mass in the particle size distribution is 50% 0.8~10.0nm is 90% the The noble metal-based fine particles having a particle diameter D ₅₀ of 2.5 or less.
A noble metal-based colloidal solution. A noble metal colloid solution containing the noble metal fine particles produced by mixing two or more kinds of raw material solutions;
At least one of the two or more raw material solutions contains a noble metal ion that is a raw material of the noble metal-based fine particles, and at least one of the two or more raw material solutions contains the polyalkyleneimine. Contains
2. The method according to claim ¹ , wherein each raw material solution is directly and independently introduced into a region where the shear rate is 1100 sec ⁻¹ or more and 7500 sec ⁻¹ or less and is homogeneously mixed. Precious metal colloid solution.   At least one of the two or more kinds of raw material solutions contains the noble metal ion, and at least one of the remaining raw material solutions contains the polyalkyleneimine. The noble metal colloid solution according to claim 2.   The noble metal colloid solution according to claim 3, wherein the raw material solution containing the polyalkyleneimine further contains a reducing agent.   The noble metal colloid solution according to any one of claims 2 to 4, wherein a cation concentration of the raw material solution containing the noble metal ions is 0.0001 to 0.5 mol / L. Two or more raw material solutions are mixed to produce a noble metal colloid solution containing at least one noble metal fine particle selected from the group consisting of noble metal fine particles, noble metal alloy fine particles, noble metal compound fine particles and noble metal alloy compound fine particles. A method,
At least one of the two or more raw material solutions contains a noble metal ion that is a raw material of the noble metal-based fine particles, and at least one of the two or more raw material solutions has a weight average molecular weight of 3000. Containing ~ 15000 polyalkyleneimines,
1100sec homogeneously mixed directly introduced the ^-1 7500 sec ^-1 in a region that is the following shear rate independently of each raw material solution, and characterized in adjusting the pH of the solution to 2.5 to 6.0 A method for producing a noble metal colloid solution.   At least one of the two or more kinds of raw material solutions contains the noble metal ion, and at least one of the remaining raw material solutions contains the polyalkyleneimine. The method for producing a noble metal-based colloidal solution according to claim 6.   The method for producing a noble metal colloid solution according to claim 7, wherein the raw material solution containing the polyalkyleneimine further contains a reducing agent.   The cation concentration of the raw material solution containing the noble metal ions is 0.0001 to 0.5 mol / L, The production of the noble metal-based colloid solution according to any one of claims 6 to 8 Method.