U.S. patent application number 11/806298 was filed with the patent office on 2007-11-01 for particle producing method and particle producing apparatus.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. Invention is credited to Isao Matsui.
Application Number | 20070252313 11/806298 |
Document ID | / |
Family ID | 32844442 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070252313 |
Kind Code |
A1 |
Matsui; Isao |
November 1, 2007 |
Particle producing method and particle producing apparatus
Abstract
A particle producing apparatus includes a reaction container, an
introduction portion for introducing a source gas and a reaction
inhibitor generating gas into the reaction container, an inert gas
introduction portion for introducing a carrier gas into the
reaction container, a heater provided on the reaction container,
and an exhaust portion. The growth of particles is controlled using
a particle producing reaction and a reverse reaction.
Inventors: |
Matsui; Isao; (Saitama,
JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
Kabushiki Kaisha Toshiba
Tokyo
JP
|
Family ID: |
32844442 |
Appl. No.: |
11/806298 |
Filed: |
May 31, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10695788 |
Oct 30, 2003 |
7247188 |
|
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11806298 |
May 31, 2007 |
|
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Current U.S.
Class: |
266/157 |
Current CPC
Class: |
B01J 2219/00094
20130101; B01J 23/755 20130101; B01J 6/008 20130101; B22F 9/305
20130101; B01J 23/75 20130101; B01J 37/086 20130101; B82Y 30/00
20130101; B01J 12/02 20130101; B01J 23/745 20130101; B01J 2219/0009
20130101 |
Class at
Publication: |
266/157 |
International
Class: |
C21B 7/22 20060101
C21B007/22 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 17, 2003 |
JP |
P2003-37587 |
Claims
1-17. (canceled)
18. A particle producing apparatus comprising: a reaction
container; an introduction portion provided at one end of the
reaction container, the introduction portion through which a source
gas, a reaction inhibitor generating gas, and a carrier gas are
introduced into the reaction container; a heater provided on an
outer wall of the reaction container; an exhaust portion configured
to exhaust the carrier gas and produced particles from the other
end of the reaction container; a cooler configured to cool the
produced particles exhausted from the exhaust portion; and a
storage portion configured to store the produced particles from the
cooler.
19. The particle producing apparatus according to claim 18, wherein
the reaction inhibitor generating gas includes hydrogen and carbon
dioxide.
Description
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No. 2003-37587
filed on Feb. 17, 2002; the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a particle producing method
and a particle producing apparatus, and more particularly to a
particle producing method and a particle producing apparatus for
preparing particles in a gas phase using the gas phase
reaction.
[0004] 2. Description of the Related Art
[0005] A particle of nanometer size has a large specific surface
area (surface area per unit volume) and has a function such as the
quantum size effect, which is not provided conventionally. The
particle of nanometer size is drawing attention as a substance of
new conformation in recent years. The particles of nanometer size
are applied to a catalyst, a battery electrode, a visible LED
element and a phosphor of display, depending on the kind of
particles.
[0006] A method for producing particles and a method for
controlling the particle size have been described in
JP-A-2001-261335.
[0007] JP-A-2001-261335 discloses a configuration in which a
reaction container has a source gas introduction portion and a
surface-adhesion introduction portion separately. Particles are
grown while a source gas and a carrier gas are flowed through the
reaction container, and produced particles are collected from the
opposite side to the source gas introduction portion.
[0008] The particles are grown while moving along with the carrier
gas within the reaction container.
[0009] As a method for producing the particles of desired size, the
collected particles may be sieved through a filter. Alternatively,
a surface adhesion maybe blown onto the particle surface to
compulsorily stop the growth. For this purpose, the
surface-adhesion introduction portion is provided on a side of the
reaction container.
[0010] In the conventional particle producing apparatus with the
above configuration, the particle size was controlled depending on
timing when the surface adhesion was introduced during growth of
particles. Therefore, to obtain particles of a predetermined size,
it was necessary to provide the surface-adhesion introduction
portion, which was different from the source gas introduction
portion (a source gas introduction port).
[0011] Moreover, to produce particles of different sizes, it was
required to move the surface-adhesion introduction portion (a
surface-adhesion introduction port). Alternatively, it was required
to provide a plurality of surface-adhesion introduction
portions.
[0012] Also, even if the surface-adhesion introduction port was
shifted, gases in the reaction container had different flow rates
and thus, it was difficult to obtain only particles of desired
size. To control the size of produced particles means to remove
particles of undesired size through the filter. This results in a
great influence on the production efficiency.
BRIEF SUMMARY OF THE INVENTION
[0013] A particle producing method according to embodiments of the
invention, includes introducing a carrier gas into a reaction
container, heating an inside of the reaction container, and
introducing a source gas and a reaction inhibitor generating gas
into the reaction container.
[0014] Also, another particle producing method according to the
embodiments of the invention, includes pyrolyzing a source gas to
produce particles, and producing an inhibition component, which
inhibits the pyrolyzing, from a reaction inhibitor generating gas
with the produced particles used as a catalyst.
[0015] A particle producing apparatus according to the embodiments
of the invention, includes a reaction container, an introduction
portion, a heater, an exhaust portion, a cooler, and a storage
portion. The introduction portion is provided at one end of the
reaction container. A source gas, a reaction inhibitor generating
gas, and a carrier gas are introduced into the reaction container
through the introduction portion. The heater is provided on an
outer wall of the reaction container. The exhaust portion is
configured to exhaust the carrier gas and produced particles from
the other end of the reaction container. The cooler is configured
to cool the produced particles exhausted from the exhaust portion.
The storage portion is configured to store the produced particles
from the cooler.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic view showing a particle producing
apparatus according to an embodiment of the invention.
[0017] FIG. 2 is a graphical representation showing a particle size
distribution of particles produced according to the embodiment of
the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Embodiments of the invention will be described below with
reference to the accompanying drawings.
Embodiment 1
[0019] FIG. 1 is a schematic view showing a first embodiment.
[0020] A particle producing apparatus includes a gas introduction
portion 2 for introducing gases at one end of a reaction container
1.
[0021] Here, the gases introduced into the reaction container 1
include a source gas 21, a reaction inhibitor generating gas 22 and
a carrier gas 4. FIG. 1 shows an example in which these gases are
mixed and introduced into the reaction container 1. Alternatively,
introduction ports for respective gases may be provided at one end
of the reaction container separately.
[0022] A heater 5, which serves as an excitation device, is
provided on an outside wall of the reaction container 1. The heater
5 heats and keeps the inside of the reaction container 1 at
temperatures at which a chemical reaction occurs. Preferably, the
heater 5 is only provided on an outside wall in the vicinity of a
central part of the reaction container 1. The heater 5 is not
provided on the upstream side of the central part. This is because
if the chemical reaction occurs near an entrance of the reaction
container 1, a reaction product sticks near the entrance of the gas
introduction portion 2 and might close the entrance thereof. Also,
the heater 5 is not provided on the downstream side of the center
part. This is because the produced particles are prevented from
growing to a size greater than necessary. Of course, the vicinity
of the central part does not mean just the center thereof, but is
set to be suitable for promoting the reaction.
[0023] An exhaust portion 6 is provided at an end of the reaction
container 1 opposite to the gas introduction portion 2.
[0024] Moreover, the produced particles exhausted and the carrier
gas, which are from the exhaust portion 6, are introduced into a
cooler 7, and stored in a storage portion 8. The storage portion 8
reserves a solvent such as water, ethanol or methanol in its inside
to prevent the stored particles from aggregating. The particles are
blown into this solvent.
[0025] Though not shown, a heater for removing liquid components
and surface adhesion from the solvent containing the particles
stored in the storage portion 8 may be added.
[0026] The carrier gas 4 is the inert gas such as nitrogen.
[0027] Herein, the source gas 21 and the reaction inhibitor
generating gas 22 are mixed before being introduced into the
reaction container 1. This mixture gas is further mixed with the
carrier gas and introduced into the reaction container 1.
Alternatively, the carrier gas maybe introduced into the reaction
container 1 through another introduction port different from the
gas introduction portion 2 through which the mixture gas of the
source gas 21 and the reaction inhibitor generating gas 22 is
introduced.
[0028] The source gas is Fe(CO).sub.5.
[0029] The reaction inhibitor generating gas includes hydrogen and
carbon dioxide.
[0030] The particle producing method will be described below.
[0031] (1) The carrier gas 4 is introduced into the reaction
container 1 to create a stable gas flow from the gas introduction
portion 2 to the exhaust portion 6. The air pressure in the
reaction container 1 is set to about 101.3 kPa (760 torr).
[0032] (2) The heater 5 heats the inside of the reaction container
1 so that the temperature of the reaction container 1 is about 600
to 700.degree. C. In the cooler 7, the temperature is set to
approximately room temperature and the air pressure is set to about
101.3 kPa (760 torr).
[0033] (3) The mixture gas of the source gas 21 and the reaction
inhibitor generating gas 22 is introduced through the gas
introduction portion 2 into the reaction container 1. Introducing
ports for the source gas 21 and the reaction inhibitor generating
gas 22 may be provided separately to introduce the reaction
inhibitor generating gas 22 almost at the same time of introducing
the source gas 21. Also, an introduction port for the carrier gas 4
may be provided separately from the introduction port for the
mixture gas.
[0034] (4) The following heat decomposition reaction (equation 1)
occurs within the reaction container 1. This chemical reaction
occurs in an area heated at about 600 to 700.degree. C. by the
heater 5 (hereinafter referred to as a reaction area).
Fe(CO).sub.5.fwdarw.Fe+5CO (equation 1)
[0035] Fe particles are produced from the source gas 21 by the
chemical reaction (equation 1). An average diameter of the Fe
particles is about several nm.
[0036] The reaction inhibitor generating gas 22 including hydrogen
and carbon dioxide is introduced. This reaction inhibitor
generating gas 22 causes a chemical reaction (equation 2).
H.sub.2+CO.sub.2.fwdarw.H.sub.2O+CO (equation 2)
[0037] This reaction produces CO. This is called a water gas shift
reaction, and is known to proceed with iron as a catalyst.
[0038] By the way, the chemical reaction (equation 1) has a reverse
reaction (equation 3). Fe+5CO.fwdarw.Fe(CO).sub.5 (equation 3)
[0039] Accordingly, if CO exists, the chemical reaction (equation
3) occurs at the same time. This reaction further proceeds as the
CO concentration is higher. Namely, the progress of the chemical
reaction (equation 1) is more inhibited, as the CO concentration is
higher.
[0040] That is, at the same time of producing Fe from the source
gas 21 by the reaction (equation 1), water and CO, which is a
heat-decomposition-reaction inhibiting component, are produced from
the reaction inhibitor generating gas 22 by the reaction (equation
2). If the reaction (equation 1) proceeds to produce Fe, the
produced Fe serves as a catalyst to cause the reaction (equation 3)
to proceed, and inhibits the proceeding of the reaction (equation
1).
[0041] In this manner, in the reaction container 1, the source gas
21, and the products such as Fe particles, CO and water are led
into the exhaust portion 6 along with the flow of the carrier gas
4.
[0042] (5) The carrier gas 4 containing Fe particles exhausted from
the reaction container 1, which is at the temperature of several
hundreds degrees, is introduced into the cooler 7 and cooled to the
room temperature.
[0043] (6) The carrier gas containing the cooled particles is
introduced into the solvent reserved in the storage portion 8.
Passing the solvent, Fe particles are mixed into the solvent, so
that only the carrier gas is exhausted from the storage portion 8
into the atmosphere.
[0044] (7) The Fe particles are preserved in a mixing state with
the solvent. Here, when the Fe particles are required, a desired
amount of solvent is taken from the storage portion 8, is heated by
a heater to evaporate the solvent components, and leave the Fe
particles alone as the solute.
[0045] FIG. 2 shows an example in which particles are produced in
this embodiment. Here, the axis of abscissas represents the
particle diameter of Fe particles and the axis of ordinates
represents the number of particles collected.
[0046] A composite particle distribution 31 is obtained under the
following condition:
[0047] the flow rate of Fe(CO).sub.5 (raw material) is 1 sccm;
[0048] the flow rate of hydrogen is 50 sccm;
[0049] the flow rate of carbon dioxide is 50 sccm; and
[0050] the flow rate of nitride (carrier gas) is 100 sccm. Also, a
particle distribution 32 is obtained under the following
condition:
[0051] the flow rate of Fe(CO).sub.5 (raw material) is 1 sccm;
[0052] the flow rate of hydrogen is 10 sccm;
[0053] the flow rate of carbon dioxide is 10 sccm; and
[0054] the flow rate of nitride (carrier gas) is 100 sccm.
On the other hand, a conventional example is obtained under the
following condition:
[0055] the flow rate of Fe(CO).sub.5 is 1 sccm;
[0056] the flow rate of hydrogen is 0 sccm;
[0057] the flow rate of carbon dioxide is 0 sccm; and
[0058] the flow rate of nitride is 100 sccm.
[0059] The production was performed with changing a ration of the
source gas 21 to the reaction inhibitor generating gas 22, which
were introduced into the reaction container 1. As a result, the
peak 31 and the peak 32 were obtained in the particle distribution
as shown in FIG. 2. The peak 31 involves a smaller particle
diameter, and the peak 32 involves a larger particle diameter. In
both the examples, the particle diameter distribution with quite
narrow width centered at a predetermined particle diameter is
represented. That is, it is indicated that the Fe particles
obtained are excellently uniform in the particle diameter.
[0060] Also, it is possible to control the particle diameter of the
obtained particles by changing the ratio of the source gas 21 to
the reaction inhibitor generating gas 22. That is, it is possible
to make the particle diameter be smaller by increasing the
concentration of the supplied reaction inhibitor generating gas,
and be larger by decreasing it.
[0061] With the conventional method (conventional example), the
particle diameter is distributed more widely.
[0062] As described above, in this embodiment, the reaction
inhibitor generating gas is introduced together with the source
gas. As a result, the particles of smaller diameter and narrow
distribution width can be produced. Also, since few particles are
discarded, the utilization efficiency of the source gas is
enhanced.
Embodiment 2
[0063] In this embodiment, a Co particle is produced.
[0064] Herein, a particle producing apparatus similar to that of
the first embodiment is employed.
[0065] The source gas is Co.sub.2(CO).sub.8.
[0066] The reaction inhibitor generating gas includes hydrogen and
carbon dioxide.
[0067] The carrier gas may be an inert gas. Nitrogen is employed
here.
[0068] The source gas is heated in a reaction furnace 1 to cause a
reaction, Co.sub.2(CO).sub.8.fwdarw.2Co+8CO (equation 4) As a
result, Co particles are produced. The average diameter of the Co
particles is as large as about several nm.
[0069] The reaction (equation 4) has a reverse reaction, which is
represented as 2Co+8CO.fwdarw.Co.sub.2(CO).sub.8 (equation 5) This
reaction further proceeds as the concentration of CO is higher.
Namely, the progress (equation 4) is more inhibited as the
concentration of CO is higher. As a result, the production of CO
particles is suppressed.
[0070] Here, through the reaction (equation 2), CO is produced from
the reaction inhibitor generating gas with Co as a catalyst.
Accordingly, if Co is produced by the reaction (equation 4), the Co
production reaction by the reaction (equation 2) proceeds so that
the growth inhibition reaction by the reaction (equation 5) takes
effect.
[0071] In this manner, the Co particles are produced with a narrow
particle diameter distribution width. Also, the control of the
particle diameter can be facilitated.
Embodiment 3
[0072] In this embodiment, Ni particles are produced.
[0073] Herein, a particle producing apparatus similar to that. of
the first embodiment is employed.
[0074] The source gas is Ni(CO).sub.4.
[0075] The reaction inhibitor generating gas includes hydrogen and
carbon dioxide.
[0076] The carrier gas is nitrogen here.
[0077] The source gas is heated in the reaction furnace 1 to cause
a reaction, Ni(CO).sub.4.fwdarw.Ni+4CO (equation 6) As a result, Ni
particles are obtained. The average diameter of the Ni particles is
as large as about several nm.
[0078] The reaction (equation 6) has a reverse reaction, which is
represented as Ni+4CO.fwdarw.Ni(CO).sub.4 (equation 7) This
reaction further proceeds as the CO concentration is higher.
Namely, the progress (equation 6) is more inhibited as the CO
concentration is higher, so that the production of Ni particles is
suppressed.
[0079] Herein, through the reaction (equation 2), CO is produced
with Ni as the catalyst. Accordingly, if Ni is produced by the
reaction (equation 6), the CO production reaction proceeds by the
reaction (equation 2), so that the growth inhibition reaction by
the reaction (equation 7) takes effect.
[0080] In this manner, the Ni particles a reproduced with a narrow
particle diameter distribution width. Also, the control of the
particle diameter can be facilitated.
[0081] As described above, according to the embodiments of the
invention, the particle diameter of the particles is controlled to
facilitate the production of the particles.
* * * * *