Description
Title of Invention: ADSORBING CARBON MATERIAL
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Japanese Priority Patent Application JP
2013-053042 filed March 15, 2013, the entire contents of which are incorporated
herein by reference.
Technical Field
[0002] The present disclosure relates to an adsorbing material.
Background Art
[0003] Activated carbon using coconut husks or petroleum pitch as a raw material in the
related art has been used as a material for various filters and has received attention as
an adsorbent adsorbing, particularly, volatile organic compounds (VOCs). In addition,
activated carbon has been used in order to remove unpleasant odors for improving
comfort in rooms or automobiles.
Citation List
Patent Literature
[0004] PTL 1: Japanese Unexamined Patent Application Publication No. 2008-104845
Summary
Technical Problem
[0005] However, for example, according to Japanese Unexamined Patent Application Pub
lication No. 2008-104845, activated carbon may not sufficiently adsorb a volatile
organic compound. Further, a smell component as a source of an unpleasant odor is
often attached to water vapor (water molecules) in the air. However, under the
condition that the activated carbon may not efficiently adsorb water vapor and such a
smell component is attached to water vapor (water molecules) in the air, it is difficult
to remove the smell component with the activated carbon.
[0006] Accordingly, it is desirable to provide an adsorbing material that can adsorb various
volatile organic compounds or water vapor with high efficiency.
Solution to Problem
[0007] According to a first embodiment of the present disclosure, there is provided an
adsorbing material for a filter for air purification, which is made of a porous carbon
material derived from a plant and in which a value of particle porosity epsilon p is 0.7 or
more. Further, in the adsorbing material according to the first embodiment of the
present disclosure, it is preferable that particle apparent density rhopbe 0.5 g/mL or
less. It is preferable that the particle porosity epsilon pbe defined as follows.
Particle porosity epsilon p= alpha*beta*rho p,
here,
rhO p is particle apparent density (unit: gram/milliliter) and calculated by l/(l/rho t +
alpha*beta).
rhot is particle true density (unit: gram/milliliter) and calculated by (sample mass/
sample volume).
alpha is water content (g-water/g-wet) per wet weight
beta is a conversion factor of dry weight (g-wet/g-dry).
[0008] According to a second embodiment of the present disclosure, there is provided an
adsorbing material for a filter for air purification, which is made of a granular porous
carbon material derived from a plant and in which a value of filling density rhob is 0.2
g/mL or less. It is preferable that the filling density rhobbe calculatedby obtaining a
volume V50oof 5.00 g of a dry porous carbon material having a particle diameter of
0.25 mm to 0.50 mm and by dividing the mass value of the dry porous carbon material
by the volume V50othereof. It is preferable that an aspect ratio of the granular porous
carbon material be 20 or less. The aspect ratio of the granular porous carbon material
can be obtained based on a method for measuring an aspect ratio of 10 grains of an
arbitrary particle by an SEM observation and setting the average value thereof as an
aspect ratio.
[0009] According to a third embodiment of the present disclosure, there is provided an
adsorbing material for a filter for air purification, which is made of a porous carbon
material derived from a plant and in which a volume of a fine pore having a diameter
of 20 nm or more is 1.0 mL/g or more based on a vapor adsorption method.
[0010] According to a fourth embodiment of the present disclosure, there is an adsorbing
material for a filter for air purification, which is made of a porous carbon material
derived from a plant and in which a volume of a fine pore having a diameter of 1 nm or
more is 0.6 mL/g or more based on a methanol method described in "Industrial
Chemistry Journal (Kogyo Kagaku Kaishi)" Vol. 73, No. 9, 1911 to 1915 (1970) or
"Surface (Hyomen)" Vol. 13, pp. 588 to 592, pp. 650 to 656, and pp. 738 to 745
(1975).
[001 1] According to a fifth embodiment of the present disclosure, there is provided an
adsorbing material adsorbing acetone, which is made of a porous carbon material
derived from a plant and in which an equilibrium adsorption amount of acetone in an
air atmosphere containing 3 vol of acetone is 0.29 mg/g or more.
[0012] According to a sixth embodiment of the present disclosure, there is provided an
adsorbing material adsorbing toluene, which is made of a porous carbon material
derived from a plant and in which an equilibrium adsorption amount of toluene in an
air atmosphere containing 1.5 vol of toluene is 0.5 mg/g or more.
[0013] According to a seventh embodiment of the present disclosure, there is provided an
adsorbing material adsorbing water vapor, which is made of a porous carbon material
derived from a plant and in which an equilibrium adsorption amount of water vapor in
an air atmosphere having a temperature of 40 degrees Celsius and a relative humidity
of 84% is 0.50 mg/g or more.
[0014] According to an eighth embodiment of the present disclosure, there is provided an
adsorbing material adsorbing ammonia, which is made of a porous carbon material
derived from a plant, in which when air containing 8 ppm of ammonia gas and having
a temperature of 20 degrees Celsius and a relative humidity of 50% is ventilated with a
space velocity of 5 x 102/hour, and a removal rate of accumulated ammonia gas until
one hour elapses from the start of ventilation is 0.3 micromol/g or more.
[0015] According to a ninth embodiment of the present disclosure, there is provided an
adsorbing material adsorbing acetaldehyde, which is made of a porous carbon material
derived from a plant, in which when air containing 0.14 ppm of acetaldehyde vapor
and having a temperature of 20 degrees Celsius and a relative humidity of 50% is
ventilated with a space velocity of 1.5 x 104/hour, and a removal rate of accumulated
acetaldehyde vapor until one hour elapses from the start of ventilation is 0.2 micromol/
g or more.
According to another embodiment of the present disclosure, there is provided an
adsorbing material comprising a porous carbon material derived from a raw material
including a plant derived material, wherein the porous carbon material comprises a
plurality of fine pores, and wherein the porous carbon material comprises at least one
of a particle apparent density (rhop) of 0.5 g/mL or less, and a particle porosity (epsilon
p) of 0.7 or more.
According to a further emdodiment of the present disclosure, there is provided a filter
comprising an adsorbing material, the adsorbing material comprising a porous carbon
material derived from a raw material including a plant derived material, wherein the
porous carbon material comprises a plurality of fine pores, and wherein the porous
carbon material comprises at least one of a particle apparent density (rhop) of 0.5 g/mL
or less, and a particle porosity (epsilonp) of 0.7 or more.
Advantageous Effects of Invention
[0016] An adsorbing material according to a first to ninth embodiments of the present
disclosure is made of a porous carbon material derived from a plant. Further, in an
adsorbing material of the first embodiment of the present disclosure, the value of
particle porosity epsilonpof the porous carbon material is defined. In an adsorbing
material of the second embodiment of the present disclosure, the value of filling
density rhob is defined. In an adsorbing material according to the third embodiment of
the present disclosure, the value of fine pore volume is defined based on a vapor adsorption
method. In an adsorbing material according to the fourth embodiment of the
present disclosure, the value of fine pore volume is defined based on a methanol
method, and therefore it is possible to provide an adsorbing material which can e f
fectively adsorb various volatile organic compounds or water vapor with high e f
ficiency. In addition, in an adsorbing material according to the fifth embodiment of the
present disclosure, the adsorbing material is specified by defining an equilibrium ad
sorption amount of acetone in a predetermined condition, and therefore it is possible to
provide an adsorbing material which can effectively adsorb acetone with high e f
ficiency. Further, in an adsorbing material according to the sixth embodiment of the
present disclosure, the adsorbing material is specified by defining an equilibrium
adsorbing amount of toluene in a predetermined condition, and therefore it is possible
to provide an adsorbing material which can effectively adsorb toluene with high e f
ficiency. Further, in an adsorbing material according to the seventh embodiment of the
present disclosure, the adsorbing material is specified by defining an equilibrium ad
sorption amount of water vapor in a predetermined condition, and therefore it is
possible to provide an adsorbing material which can effectively adsorb water vapor
with high efficiency. Further, in an adsorbing material according to the eighth em
bodiment of the present disclosure, the adsorbing material is specified by defining a
removal rate of accumulated ammonia gas in a predetermined condition, and therefore
it is possible to provide an adsorbing material which can effectively adsorb ammonia
with high efficiency. Furthermore, in an adsorbing material according to a ninth em
bodiment of the present disclosure, the adsorbing material is specified by defining a
removal rate of accumulated acetaldehyde vapor in a predetermined condition, and
therefore it is possible to provide an adsorbing material which can effectively adsorb
acetaldehyde with high efficiency.
Brief Description of Drawings
[fig.l]Fig. 1 is a schematic view illustrating a porous carbon material constituting an
adsorbing material in Example 1.
[fig.2]Fig. 2 is a graph illustrating calculation results of an equilibrium adsorption
amount of acetone of the adsorbing material in Example 1.
[fig.3]Fig. 3 is a graph illustrating calculation results of an equilibrium adsorption
amount of toluene of an adsorbing material in Example 2.
[fig.4]Fig. 4 is a graph illustrating calculation results of an equilibrium adsorption
amount of water vapor of an adsorbing material in Example 3.
[fig.5]Fig. 5 is a graph illustrating calculation results of a removal amount of ac
cumulated ammonia gas of an adsorbing material in Example 4.
[fig.6]Fig. 6 is a graph illustrating calculation results of a removal amount of accumulated
acetaldehyde vapor of an adsorbing material in Example 5.
Description of Embodiments
[0018] Hereinafter, the present disclosure will be described based on Examples with
reference to the accompanying drawings, but the present disclosure is not limited
thereto, and various numerical expressions and materials in Examples are merely
examples. In addition, the present disclosure will be described in the following order.
1. Description concerning the overall adsorbing material according to a first em
bodiment to a ninth embodiment of the present disclosure
2. Example 1 (the adsorbing material according to the first embodiment to the fifth
embodiment of the present disclosure)
3. Example 2 (the adsorbing material according to modification of Example 1 and the
sixth embodiment of the present disclosure)
4. Example 3 (the adsorbing material according to modification of Example 1 and the
seventh embodiment of the present disclosure)
5. Example 4 (the adsorbing material according to modification of Example 1 and the
eighth embodiment of the present disclosure)
6. Example 5 (the adsorbing material according to modification of Example 1 and the
ninth embodiment of the present disclosure) etc.
[0019]
In the adsorbing material according to the first embodiment to the ninth embodiment
of the present disclosure (hereinafter, also simply referred to as the "adsorbing material
of the present disclosure" collectively), the porous carbon material uses a material
derived from a plant as a raw material. Here, examples of the material derived from a
plant may include chaff such as rice chaff, barley, wheat, rye, barnyard millet, or
millet, straw, coffee beans, tea leaves (for example, leaves of green tea or tea),
sugarcanes (more specifically, strained lees of sugarcanes), mealies (more specifically,
the core of mealies), fruit skins (for example, skins of a citrus fruit such as skins of an
orange, skins of a grapefruit, or skins of a mandarin orange or skins of banana), a reed,
and a wakame seaweed stem. However, the material derived from a plant is not limited
to these, other examples of the material may include tracheophytes growing on the
ground, ferns, bryophytes, algae, and seaweeds. In addition, these materials can be
used alone or plural kinds thereof can be used as a mixture, as a raw material. Further,
the shape or the form of the material derived from a plant is not particularly limited,
for example, chaff or straw may be used as is or a drying-processed product thereof
may be used. Further, in the food or drink processing of beer, liquor, etc., ingredients
subjected to various treatments such as a fermentation treatment, a roasting treatment,
and an extraction treatment can be used as well. Particularly, it is preferable to use
processed straw or chaff processed by threshing, etc., from the viewpoint promoting
the recycling of industrial waste. This processed straw or chaff can be easily obtained
in large amounts from, for example, agricultural cooperatives, companies producing
alcoholic beverages, food companies, and food processing companies.
[0020] The adsorbing material of the present disclosure can be used for air purification,
widely, for gas purification. The adsorbing material of the present disclosure can be
made of a porous carbon material alone or a porous carbon material/polymer complex
including a porous carbon material and a polymer. Here, examples of a binder con
stituting the porous carbon material/polymer complex may include carboxy nitro
cellulose, a urea resin, a melamine resin, a phenol resin, an epoxy resin, a
polyurethane-based resin, a resorcin-based resin, a vinyl acetate resin, a polyvinyl
alcohol resin, a polyethylene resin, a polyester resin, a polystyrene resin, a
poly(meth)acrylic resin, a poly(meth)acrylic acid ester resin, a (meth)acrylic acidstyrene
copolymer resin, an ethylene- vinyl acetate copolymer resin, a vinyl acetate -
(meth) acrylic copolymer resin, and an ethylene-vinyl acetate- (meth) acrylic ternary
copolymer resin, and among these, a butadiene-based resin or a styrene-based resin,
which is hydrophilic and is barely hydrolyzed and swollen, such as an acrylonitrilebutadiene
resin (AB resin), a styrene-butadiene resin (SB resin), an acrylonitrilebutadiene-
styrene resin (ABS resin), an acrylic acid ester-styrene copolymer resin, or a
methacrylic acid ester-styrene copolymer resin is more preferable. In addition, two or
more binders thereof can be used together.
[0021] Further, a form of supporting (carrying) a porous carbon material or a porous carbon
material/polymer complex (hereinafter, also referred to as "a porous carbon material
and the like" collectively) by a supporting member can be exemplified. Examples of
the supporting member may include woven fabric, non- woven fabric (including wet
non-woven fabric), paper, and chemical fiber paper, and as a material constituting
woven fabric, non- woven fabric, or chemical fiber paper, cellulose, polypropylene,
polyester, or rayon can be exemplified. Examples of the supporting form may include a
form in which a porous carbon material or the like is interposed between supporting
members, a form in which a porous carbon material or the like is kneaded in a
supporting member, a form in which a porous carbon material or the like infilters into a
supporting member (for example, mixed paper), a form in which a porous carbon
material is attached to a supporting member, and a form in which a supporting member
is coated with a porous carbon material or the like.
[0022] Further, a use in powder, roughly pulverized, or granular shape, a use in sheet shape,
a use in a state of shaping into a desired shape using a binder (binding agent) or the
like, a use in a state of filling a column or a cartridge, or a use together with a
corrugated honeycomb, pleated, or honeycomb supporting member can be exemplified.
[0023] In addition, the adsorbing material can constitute, for example, a filter of an air p u
rification apparatus, a mask, protection gloves, protective shoes, or canister for a fuel
tank of various automobiles.
[0024] Examples of the adsorbing object of the adsorbing material according to the first em
bodiment to the fourth embodiment of the present disclosure may include: a totally
volatile organic compound (TVOC), specifically, a highly volatile organic compound
(VVOC) such as propane, butane, or methyl chloride; a volatile organic compound
(VOC) such as formaldehyde, acetaldehyde, d-limonene, triene, acetone, xylene,
ethanol, 2-propane, hexanol, ethylbenzene, styrene, para-dichlorobenzene, tetradecane,
chloropyrifos, phenol carp, phthalic acid di-n-butyl, phthalic acid di-2-ethylhexyl, or
diazinon; a semi-volatile organic compound (SVOC) such as an insecticide (DDT,
chlordane), a plasticizer (a phthalic acid compound), or a flame retardant; water vapor;
and a smell component accompanied with water vapor. Further, a suspended granular
substance, a particulate granular substance, an ultrafine particle, a fine particle of diesel
exhaust, an inhalational particle, inhalational dust, falling dust, and an aerosol particle
(suspended dust) can be also exemplified.
[0025] When a material derived from a plant containing silicon (Si) is used as a raw material
of the porous carbon material in the adsorbing material of the present disclosure,
specifically, but not limited thereto, it is preferable that the raw material of the porous
carbon material be a material derived from a plant in which the content of silicon (Si)
is 5% by mass or less, more preferably 3% by mass or less, and still more preferably
1% by mass or less.
[0026] The porous carbon material of the adsorbing material of the present disclosure can be
obtained by carbonizing a material derived from a plant at a temperature range of 400
degrees Celsius to 1400 degrees Celsius and treating the material with acid or alkali. In
a method for producing the porous carbon material of the adsorbing material of the
present disclosure (hereinafter, also simply referred to as a "method for producing the
porous carbon material"), the adsorbing material can be obtained by carbonizing a
material derived from a plant at a temperature range of 400 degrees Celsius to 1400
degrees Celsius and the material prior to the treatment with acid or alkali is called "a
porous carbon material precursor" or "a carbonaceous material."
[0027] In the method for producing the porous carbon material, a process which carries out
an activation treatment can be included subsequent to the treatment with acid or alkali
or the treatment with an acid or alkali may be performed subsequent to the activation
treatment. Further, the method for producing the porous carbon material including such
a preferable form depends on the material derived from a plant being used, but the
material derived from a plant can be subjected to a heat treatment (preliminary carbonization
process) in a state of cutting off oxygen at a lower temperature than the
temperature for carbonization (for example, 400 degrees Celsius to 700 degrees
Celsius) prior to carbonization of the material derived from a plant. By doing this
process, a tar component to be generated in the carbonization process can be extracted,
and as a result, the tar component to be generated in the carbonization process can be
reduced or removed. In addition, the state of cutting off oxygen can be achieved by
preparing, for example, an inert gas atmosphere such as nitrogen gas or argon gas, or
by preparing a vacuum atmosphere, or by putting the material derived from a plant in a
kind of a baking state. In addition, the method for producing the porous carbon
material depends on the material derived from a plant being used, but the material
derived from a plant can be immersed in alcohol (for example, methyl alcohol, ethyl
alcohol, or isopropyl alcohol) for reducing mineral components or moisture contained
in the material derived from a plant and for preventing an unpleasant odor from being
generated in the carbonization process. Further, the preliminary carbonization
treatment may be carried out thereafter in the method for producing the porous carbon
material. As a material for the heat treatment in an inert gas, for example, a plant
largely generating pyroligneous acid (tar or light oil content) can be exemplified.
Moreover, as a material preferable for a pretreatment using alcohol, seaweeds largely
containing iodine or various minerals can be exemplified.
In the method for producing the porous carbon material, the material derived from a
plant is carbonized at a temperature range of 400 degrees Celsius to 1400 degrees
Celsius, here, carbonization means that an organic substance (a material derived from a
plant in the porous carbon material of the adsorbing material of the present disclosure)
is subjected a heat treatment to be converted to a carbonaceous material (for example,
see JIS M0104-1984). In addition, as an atmosphere for carbonization, the atmosphere
for cutting off oxygen may be exemplified, and specific examples thereof may include
a vacuum atmosphere, an inert gas atmosphere such as nitrogen gas, or argon gas, and
an atmosphere in which the material derived from a plant is in a kind of a baking state.
The temperature raising rate up to the temperature for carbonization may be 1 degree/
min or more, preferable 3 degree/min or more, and more preferably 5 degree/min or
more in such an atmosphere, but not limited thereto. Further, the upper limit of the c ar
bonization time may be 10 hours, preferably 7 hours, and more preferably 5 hours, but
not limited thereto. The lower limit of the carbonization time may be the time that the
material derived from a plant can be reliably carbonized. In addition, the material
derived from a plant can be pulverized to be a desired particle size or classified as
necessary. The material derived from plant can be washed in advance or the obtained
porous carbon material precursor or the porous carbon material may be pulverized to
be a desired particle size or classified as necessary. Alternatively, the porous carbon
material after applying the activation treatment may be pulverized to be a desired
particle size or classified as necessary. Furthermore, the finally obtained porous carbon
material may be subjected to a germicidal treatment. The form, the configuration, or
the structure of a furnace to be used for carbonization is not limited, and a continuous
furnace or a batch furnace can be used.
[0029] In the method for producing the porous carbon material, as described above, it is
possible to increase a microfine pore having a diameter smaller than 2 nm when an ac
tivation treatment is carried out. Examples of the activation treatment method may
include a gas activation method and a chemical activation method. Here, the gas ac
tivation method is a method for using oxygen, water vapor, carbonic acid gas, or air as
an activator and developing a microstructure using a volatile component or a carbon
molecule in the porous carbon material by heating the porous carbon material at a tem
perature range of 700 degrees Celsius to 1400 degrees Celsius, preferably 700 degrees
Celsius to 1000 degrees Celsius, and more preferably 800 degrees Celsius to 1000
degrees Celsius for several tens of minutes to several hours in the gas atmosphere.
Further, more specifically, the heating temperature can be appropriately selected based
on the kind of the material derived from a plant, the kind of gas, or the concentration
thereof. The chemical activation method is a method for activating a material using
zinc chloride, iron chloride, calcium phosphate, calcium hydroxide, magnesium
carbonate, potassium carbonate, or sulfuric acid instead of oxygen or water vapor used
in the gas activation method, washing with hydrochloric acid, adjusting pH with an
alkaline aqueous solution, and then drying.
[0030] A chemical treatment or a molecular modification may be performed on the surface
of the porous carbon material of the adsorbing material of the present disclosure. As a
chemical treatment, a treatment of generating a carboxy group on the surface by
applying a nitric acid treatment can be exemplified. In addition, it is possible to
generate various functional groups such as a hydroxyl group, a carboxy group, a
ketone group, and an ester group on the surface of the porous carbon material by
applying the same treatment as the activation treatment using water vapor, oxygen, or
alkali. Further, in the molecular modification, it is possible to chemically react the
porous carbon material with chemical species or proteins having a hydroxyl group, a
carboxy group, and an amino group which can be reacted with the porous carbon
material.
[0031] In the method for producing the porous carbon material, a silicon component in the
material derived from a plant subsequent to the carbonization is removed by applying a
treatment with acid or alkali. Here, examples of the silicon component may include
silicon oxides such as silicon dioxide, silicon oxide, and silicon oxide salts. By
removing the silicon component in the material derived from a plant subsequent to the
carbonization in this way, it is possible to obtain a porous carbon material having a
high specific surface area. In some cases, the silicon component in the material derived
from a plant subsequent to the carbonization may be removed based on a dry etching
method.
[0032] The porous carbon material of the adsorbing material of the present disclosure may
include nonmetallic elements such as magnesium (Mg), potassium (K), calcium (Ca),
phosphrous (P), and sulfur (S), or metallic elements such as transition elements. The
content of magnesium (Mg) may be in the range of from 0.01% by mass to 3% by
mass, the content of potassium (K) may be in the range of from 0.01% by mass to 3%
by mass, the content of calcium (Ca) may be in the range of from 0.05% by mass to
3% by mass, the content of phosphorous (P) may be in the range of from 0.01% by
mass to 3% by mass, and the content of sulfur (S) may be in the range of from 0.01%
by mass to 3% by mass. Further, it is preferable that the content of these elements be
small from the viewpoint of increasing the value of a specific surface area. It is
needless to say that the porous carbon material may contain elements other than the
elements described above and the range of the content of various elements described
above can be changed.
[0033] In the porous carbon material of the adsorbing material of the present disclosure, the
analysis of the various elements can be performed by an energy dispersion X-ray spec
trometry (EDS) using an energy dispersive X-ray analysis device (for example, JED-
2200F, manufactured by JEOL Ltd.). Here, the measurement condition may be set to a
scanning voltage of 15 kV and an irradiation current of 10 microA.
[0034] The porous carbon material of the adsorbing material of the present disclosure has a
large amount of fine pores. Examples of the fine pore include a "mesofine pore" having
a pore diameter of 2 nm to 50 nm, a "macrofine pore" having a pore diameter of more
than 50 nm, and a "microfine pore" having a pore diameter of less than 2 nm.
Specifically, the porous carbon material has a large amount of fine pores having a pore
diameter of 20 nm or less and, particularly, fine pores having a pore diameter of 10 nm
or less as mesofine pores. In addition, fine pores having a pore diameter of about 1.9
nm, fine pores having a pore diameter of about 1.5 nm, and fine pores having a pore
diameter of about 0.8 nm to 1 nm are largely included as microfine pores. In the porous
carbon material of the adsorbing material of the present disclosure, it is desirable that
the volume of a fine pore be 0.1 cmVg or more, preferably 0.2 cmVg or more, more
preferably 0.3 cmVg or more, and even more preferably 0.5 cmVg or more based on a
Barrett- Joyner-Halenda (BJH) method. Further, it is desirable that the volume of a fine
pore be 0.1 cmVg or more, preferably 0.2 cmVg or more, more preferably 0.3 cmVg or
more, and even more preferably 0.5 cmVg or more based on an MP method.
[0035] In the porous carbon material of the adsorbing material of the present disclosure, it is
desirable that the value of the specific surface area (hereinafter, simply referred to as
"the value of the specific surface area" in some cases) using a nitrogen BET method be
preferably 50 m2/g or more, more preferably 100 m2/g or more, and even more
preferably 400 m2/g or more, in order to obtain more excellent functionality.
[0036] The nitrogen BET method is a method for measuring an adsorption isotherm by
allowing an adsorbent (here, the porous carbon material) to adsorb or desorb nitrogen
as an adsorbing molecule and analyzing the measured data based on the BET formula
represented by the formula (1), and it is possible to calculate the specific surface area
or fine pore volume based on this method. Specifically, when the value of the specific
surface area is calculated based on the nitrogen BET method, the adsorption isotherm
is obtained by allowing the porous carbon material to first adsorb or desorb nitrogen as
an adsorbing molecule. Further, an expression of [p/{V (p0-p)}] is calculated based on
the formula (1) or the formula (G) which is modified from the formula (1) from the
obtained adsorption isotherm and then plotted with respect to an equilibrium relative
pressure (p/po). Subsequently, this plot is regarded as a straight line and a slant s
(=[(C-l)/(C*V )]) and an intercept I (=[l/(C*V )]) are calculated based on a least
squares method. Further, V and C are calculated from the obtained slant s and
intercept I based on the formulae (2-1) and (2-2). Moreover, a specific surface area a
SBET I S calculated from V based on the formula (3) (see BELSORP-mini and pp. 62 to
66 of BELSORP analysis software manual, manufactured by BEL Japan, Inc.). In
addition, the nitrogen BET method is a measurement method in conformity with JIS R
1626-1996 "measuring methods for the specific surface area of fine ceramic powders
by gas adsorption using the BET method."
[0037] V0 = (Vm*C*p)/[(po- p){ l + (C - l)(p/po)}] (
[p/{V (p0 - p)}] = [(C-l)/(C*VJ](p/po)+[l/(C*VJ] (G)
V + l/(s + i) (2-1)
C = (s/i) + 1 (2-2)
asBET = (Vm*L*sigma)/22414 (3)
[0038] Provided,
V : adsorption amount;
V : adsorption amount of monomolecular layer;
p : pressure when nitrogen is equilibrated;
p0: saturated vapor pressure of nitrogen;
L: avogadro number; and
sigma: adsorption sectional area of nitrogen.
[0039] When a fine pore volume Vp is calculated using the nitrogen BET method, for
example, adsorbed data of the obtained adsorption isotherm is linearly interpolated and
an adsorption amount V is calculated with the relative pressure which is set by a fine
pore volume calculation relative pressure. The fine pore volume Vpcan be calculated
from the adsorption amount V based on the formula (4) (see BELSORP-mini and pp.
62 to 65 of BELSORP analysis software manual, manufactured by BEL Japan, Inc.). In
addition, hereinafter, the fine pore volume based on the nitrogen BET method is
simply called as a "fine pore volume" in some cases.
[0040] Vp = (V/22414) x (M /p ) (4)
[0041] Provided,
V: adsorption amount at the relative pressure;
Mg: molecular amount of nitrogen; and
Pg: density of nitrogen.
[0042] The pore diameter of a mesofine pore can be calculated in a form of distribution of
fine pores using the rate of change in fine pore volume with respect to the pore
diameter based on the BJH method. The BJH method is widely used as a method for
analyzing fine pore distribution. When the fine pore is analyzed based on the BJH
method, the adsorption isotherm is obtained by allowing the porous carbon material to
adsorb or desorb nitrogen as an adsorbing molecule. Subsequently, the thickness of the
adsorption layer when the adsorption molecule is gradually adsorbed or desorbed from
the state in which the fine pores are filled with the adsorption molecules (for example,
nitrogen) and the inner diameter (twice of the core radius) of the pore which is
generated during the process are calculated based on the obtained adsorption isotherm,
and the fine pore radius rp is calculated based on the formula (5), and then the fine pore
volume is calculated based on the formula (6). In addition, a fine pore distribution
curve is obtained by plotting the rate of change in fine pore volume (dVp/drp) with
respect to the fine pore diameter (2rp) from the fine pore radius and fine pore volume
(see BELSORP-mini and pp. 85 to 88 of BELSORP analysis software manual, manu
factured by BEL Japan, Inc.).
[0043] r = t + rk (5)
V = R *dV - R *dt *c*sigmaA J (6)
provided,
R = r 2/(rk - l+dt )2 (7)
[0044] Here,
rp: fine pore radius;
rk: core radius (inner diameter/2) when an adsorption layer having a thickness t is
adsorbed to the inner wall of the fine pore having fine pore radius rpdue to the
pressure;
Vp : fine pore volume when the n-th adsorption or desorption of nitrogen occurs;
dV : amount of change at the time;
dt : amount of change in thickness t of the adsorption layer when the n-th adsorption
or desorption of nitrogen occurs;
rk : core radius at the time;
c : fixed value; and
rp : fine pore radius when the n-th adsorption or desorption of nitrogen occurs. In
addition, sigmaApj represents an integrated value of the volume of a wall surface of a
fine pore from j = 1 to j = n-1.
[0045] The pore diameter of a microfine pore can be calculated in a form of distribution of
fine pores using the rate of change in fine pore volume with respect to the pore
diameter based on the MP method. When the fine pore distribution is analyzed based
on the MP method, the adsorption isotherm is obtained by allowing the porous carbon
material to adsorb nitrogen. Subsequently, the adsorption isotherm is converted to the
fine pore volume with respect to the thickness t of the adsorption layer (t plotting), and
then a fine pore distribution curve is obtained based on the curvature (amount of
change in fine pore volume with respect to the amount of change in the thickness t of
the adsorption layer) of the plot (see BELSORP-mini and pp. 72 and 73, pp. 82 of
BELSORP analysis software manual, manufactured by BEL Japan, Inc.).
[0046] The porous carbon material precursor is treated with acid or alkali, but specific
examples of the treatment method may include a method for immersing the porous
carbon material precursor in an acid or alkali aqueous solution and a method for
reacting the porous carbon material precursor with acid or alkali in vapor phase. More
specifically, when the porous carbon material is treated with acid, as the acid, a
fluorine compound which indicates acidity such as hydrogen fluoride, hydrofluoric
acid, ammonium fluoride, calcium fluoride, or sodium fluoride can be used. When the
fluorine compound is used, the amount of a fluorine element may be 4 times of a
silicon element in a silicon component included in the porous carbon material
precursor, and it is preferable that the concentration of an aqueous solution of a
fluorine compound be 10% by mass or more. When a silicon component (for example,
silicon dioxide) included in the porous carbon material precursor by hydrofluoric acid
is removed, the silicon dioxide is reacted with the fluorine dioxide as shown in the
chemical formula (A) or (B) and removed as hexafluorosilicic acid (H2SiF ) or silicon
tetrafluoride (SiF4), and the porous carbon material can be obtained. Subsequently,
washing and drying can be performed.
[0047] Si0 2 + 6HF -> H2SiF + 2H20 (A)
Si0 2 + 4HF -> SiF4 + 2H20 (B)
[0048] Further, the porous carbon material precursor is treated with alkali (base), and, for
example, sodium hydroxide can be exemplified. When an alkali aqueous solution is
used, the pH of the aqueous solution may be 11 or more. A silicon component (for
example, silicon dioxide) included in the porous carbon material precursor is removed
by an aqueous solution of sodium hydroxide, the silicon dioxide is reacted as shown in
the chemical formula (C), removed as sodium silicate (Na2Si0 3) by heating the
aqueous solution of the sodium hydroxide, thereby obtaining the porous carbon
material. In addition, when sodium hydroxide is treated by the reaction in vapor phase,
the sodium hydroxide is reacted as shown in the chemical formula (C) by heating the
solid thereof, and is removed as sodium silicate (Na2Si0 3), thereby obtaining the
porous carbon material. Subsequently, washing and drying can be performed.
[0049] Si0 2 + 2NaOH -> Na2Si0 3 + H20 (C)
[0050] Alternatively, as the porous carbon material of the adsorbing material in the present
disclosure, for example, a porous carbon material (a so-called porous carbon material
having a reverse opal structure) in which the holes disclosed in Japanese Unexamined
Patent Application Publication No. 2010-106007 have a three dimensional regularity,
specifically, a porous carbon material which includes three-dimensionally arranged
spherical holes having an average diameter of 1 x 10 m to 1 x 10 m, and has a
surface area of 3 x 102 m2/g or more, and preferably and macroscopically, a porous
carbon material in which holes are arranged in an arrangement state corresponding to a
crystalline structure or the holes are arranged macroscopically on the surface in an ar
rangement state corresponding to a face orientation of a face-centered cubic structure
(111) can be used.
Example 1
[0051] Example 1 relates to an adsorbing material according to the first to fourth em
bodiments of the present disclosure and an adsorbing material according to the fifth
embodiment of the present disclosure. That is, the adsorbing material of Example 1 is
an adsorbing material for a filter for air purification which is made of a porous carbon
material derived from a plant and in which the value of particle porosity epsilon pis 0.7
or more. Further, the adsorbing material is an adsorbing material for a filter for air p u
rification in which particle apparent density rhopis 0.5 g/mL or less, or an adsorbing
material for a filter for air purification in which a value of filling density rhob is 0.2 g/
mL or less, or an adsorbing material for a filter for air purification in which the volume
of a fine pore having a diameter of 20 nm or more is 1.0 mL/g or more based on a
vapor adsorption method, or an adsorbing material for a filter for air purification in
which the volume of a fine pore having a diameter of 1 nm or more is 0.6 mL/g or
more based on a methanol method described in the above-described literature. Fur
thermore, the adsorbing material of Example 1 is an adsorbing material adsorbing
acetone, which is made of a porous carbon material derived from a plant, in which an
equilibrium adsorption amount of acetone in an air atmosphere containing 3 vol of
acetone is 0.29 mg/g or more.
[0052] Here, as described above, the particle porosity epsilon p is defined as follows:
particle porosity epsilon p= alpha*beta*rho p, and
rhO p is particle apparent density (unit: gram/milliliter) and calculated by l/(l/rho t +
alpha*beta);
rhot is particle true density (unit: gram/milliliter) and calculated by (sample mass/
sample volume);
alpha is water content (g-water/g-wet) per wet weight; and
beta is a conversion factor of dry weight (g-wet/g-dry). Further, as described above,
the filling density rhob is calculatedby obtaining the volume V50oof 5.00 g of a dry
porous carbon material having a particle diameter of 0.25 mm to 0.50 mm and by
dividing the mass value of the dry porous carbon material by the volume V50othereof. It
is preferable that the aspect ratio of the granular porous carbon material be 20 or less.
[0053] In Example 1 or Examples 2 to 5 described below, porous carbon materials derived
from a plant described below were used. That is, as the material derived from a plant as
a raw material of the porous carbon material, rice chaff was used. In addition, the
porous carbon material carbonized the chaff as a raw material to be converted to a car
bonaceous material (porous carbon material precursor), and then could be achieved by
applying an acid treatment.
[0054] In the production of the adsorbing material, the material derived from a plant was
carbonized at a temperature range of 400 degrees Celsius to 1400 degrees Celsius and
then treated with acid or alkali, thereby obtaining a porous carbon material. In other
words, first, a heat treatment (preliminary carbonization treatment) was carried out on
the chaff in an inert gas. Specifically, the chaff was carbonized by heating at 500
degrees Celsius for 3 hours in a nitrogen gas stream, and then carbides were obtained.
Further, it is possible to reduce or remove a tar component to be generated during the
next carbonization by applying such a treatment. Subsequently, 10 g of the carbides
were put into an alumina crucible, the temperature therein was raised up to 800 degrees
Celsius with a temperature raising rate of 5 degree/min in a nitrogen gas stream (5 L/
min), and carbonization was carried out at 800 degrees Celsius for 1 hour, and thereby,
the resultant was converted to a carbonaceous material (porous carbon material
precursor) to be cooled to room temperature. In addition, the nitrogen gas was allowed
to continuously flow inside during the carbonization and the cooling process. Sub
sequently, the acid treatment was carried out by immersing the porous carbon material
precursor in an aqueous solution of hydrofluoric acid of 46 vol/% for one night, and
then the resultant was washed with water and ethyl alcohol until the pH thereof became
7. Next, the resultant was dried at 120 degrees Celsius, the temperature thereof was
raised up to 900 degrees Celsius in a nitrogen gas stream, and a porous carbon material
constituting an adsorbing material in Example 1 could be achieved by applying an activation
treatment of heating the resultant at 900 degrees Celsius for 3 hours in a water
vapor stream.
[0055] A commercially available coconut husk activated carbon (Comparative Examples 1A
and IB), a coal-based granular activated carbon (Comparative Example 1C), and a
petroleum fibrous activated carbon (Comparative Example ID) were used as Com
parative Examples. Particle size distributions obtained by classifying the used sample
material using a sieve (5 kinds of sieves with an aperture of 1.70 mm, 0.85 mm, 0.50
mm, 0.25 mm, and 0.106 mm) were listed in Table 1 below. In addition, the aspect
ratio of the porous carbon material in Example 1 was about 10.
[0056] Comparative Example 1A: Kuraray coal GG, manufactured by KURARAY Co., Ltd.
Comparative Example IB: Kuraray coal GW, manufactured by KURARAY Co., Ltd.
Comparative Example 1C: Calgon F400, manufactured by Calgon Carbon Japan KK.
Comparative Example ID: Adole A-l, manufactured by Unitika Ltd.
[0057] (Table 1)
0.10 mm to 0.25 mm, 0.25 mm to 0.50 mm, 0.50 mm to 0.84 mm, 0.84 mm to 1.68
mm
Example 1 18.3 38.9 39.0 3.7
Comparative Example 1A 28.0 72.0 - -
Comparative Example IB 21.0 79.0 - -
Comparative Example 1C 0.2 0.4 9.4 90.0
[0058] Further, the respective values of particle true density rhot (unit: gram/milliliter),
particle apparent density rhop (unit: gram/milliliter), particle porosity epsilon b
(dimensionless), filling porosity epsilon b (dimensionless), filling density rhob (unit:
gram/milliliter) of the used samples were listed in Table 2 below.
[0059] Here, the particle true density rhot, the particle true density rhop, and the particle
porosity epsilon p were calculated with the method described below. In other words,
pure water was added to the marked line of 25 milliliter of a measuring flask (mass: W0
) and a mass W3 was measured. Next, 2.0 g (W2) of wet-sieved samples were added to
the 25 milliliter of measuring flask, followed by adding about 15 milliliter of pure
water thereto, and then a mass W4 was measured by diluting with pure water after the
deaeration. Here, in a case in which the density of pure water is set to 1.000 g/cm3, the
volume of the measuring flask isW3 -W0. On the other hand, the volume of the pure
water isW4 -W0 -W2. The particle true density rhot is rhot= W2/volume of sample = W
2/(volume of measuring flask - volume of pure water). Accordingly, the particle true
density rhot can be obtained by the expression of rhot = W2/{(W3- W0) - (W4 -W0 -W2
) } = W2/(W3 + W2 - W4). Further, the particle apparent density rhop in which fine pores
of a sample was included in a particle was calculated by the expression of rhop =
l/(l/rho t + alpha*beta). In addition, the particle porosity epsilon p which is a fine pore
volume rate of a sample can be calculated by the expression of epsilon p= vp*rho p =
alpha*beta*rho p.
[0060] Moreover, the filling density rho b and the filling porosity epsilon b were calculated
with the method described below. That is, the volume V50o(unit: milliliter) of 5.00 g of
a dried sample having a particle diameter of 0.25 mm to 0.50 mm was calculated.
Further, the filling density rho b of the sample was calculated by the expression of rho b
= 5.O/V500. Further, the filling porosity epsilon b which is a volume rate other than the
particles during the filling was calculated by the expression of epsilon b = (l/rho b -
l/rho p)/(l/rho b) = ( 1 - rho b/rho p).
[0061] In addition, Fig. 1 is a schematic view illustrating a porous carbon material con
stituting an adsorbing material in Example 1. The circles in the figure schematically
indicate the porour carbon material, the black parts inside of the circles in the figure
schematically indicate the solid parts of the porous carbon material, the white parts
inside of the circles in the figure schematically indicate the fine pore parts in the
porous carbon material, the area between circles in the figure indicate the gap area (the
gap area in an aggregate of the porous carbon materials) between the porous carbon
materials. In addition, the particle true density rho t, the particle apparent density rho p,
the particle porosity epsilon p, the filling density rho b, and the filling porosity epsilon b
can be expressed as follows.
[0062] Particle true density rho t: (mass of solid parts of porous carbon material)/(volume of
solid parts of porous carbon material)
Particle apparent density rho p: (mass of solid parts of porous carbon
material)/( volume of solid parts of porous carbon material + volume of fine pore parts
in porous carbon material)
Particle porosity epsilon p: (volume of fine pore parts of porous carbon
material)/( volume of solid parts of porous carbon material + volume of fine pore parts
in porous carbon material)
Filling porosity epsilon b: (volume of gap area in porous carbon material
aggregate)/( volume of porous carbon material aggregate)
Filling density rho b: (volume of porous carbon material aggregate)/( volume of porous
carbon material aggregate).
[0063] Moreover, a volume value (VLi) of a fine pore having a diameter of 20 nm or more
based on the vapor adsorption method, a volume value (VL'i) of a fine pore having a
diameter of less than 20 nm based on the vapor adsorption method, and a volume value
(VL 2) of a fine pore having a diameter of 1 nm or more based on the methanol method
described in the above literature are listed in Table 3 below.
[0064] Here, in the water vapor adsorption method, equilibrium adsorption amounts having
a relative humidity of 84%, 64%, 50%, 40%, and 20% were calculated and the relation
between the relative humidity and the equilibrium adsorption amount was illustrated.
[0065] The volume of fine pores was measured by the following procedures based on the
methanol method. That is, the dried sample was added to a column with a stainless
steel net having a volume of 5 mL and the mass thereof was measured. Next, each
column was fixed to a gas adsorption device. In addition, gas having a relative pressure
P/Po of 0.98 was ventilated to the gas adsorption device at about 1.0 L/min by adjusting
methanol vapor flow rate and dry air flow rate to the columns. Subsequently, the gas
was ventilated until the mass of columns became constant and then the methanol
equilibrium adsorption amount in an air atmosphere containing methanol was
calculated. Similarly, the methanol equilibrium adsorption amount in an air atmosphere
containing methanol using gas having a relative pressure P/P 0 of 0.82, 0.60, 0.40, and
0.20 was calculated. Further, the equilibrium adsorption amount was calculated in
terms of liquid volume by dividing with liquid density of 0.772 (gram/milliliter) at 40
degrees Celsius of methanol. Next, accumulated volume distribution, differential
volume distribution, integrated specific surface area, and accumulated specific surface
area of a fine pore were calculated from a methanol adsorption isotherm which is an
approximate curve based on the plot of the methanol equilibrium adsorption amount of
each relative pressure (P/Po). Further, an inner surface area S of the porous material
according to the methanol method was calculated by integrating deltaS = 2deltaV/(r - r
+ l)/2 from a fine pore distribution and a volume change deltaV of fine pores of
radius change deltar(r; - r +1).
[0066] (Table 2)
rhot rhO p epsilonp epsilonb rhob
Example 1 1.99 0.38 0.81 0.60 0.15
Comparative Example 1A 1.93 0.78 0.60 0.50 0.36
Comparative Example IB 2.08 0.82 0.6 1 0.33 0.55
Comparative Example 1C 2.00 0.75 0.63 0.4 1 0.44
Comparative Example ID 2.02 0.74 0.64 0.80 0.15
(Table 3)
VL VL VL2
Example 1 1.31 0.79 0.79
Comparative Example 1A 0.39 0.40 0.40
Comparative Example IB 0.37 0.38 0.38
Comparative Example 1C 0.30 0.54 0..53
Comparative Example ID 0.43 0.43 0.42
[0068] It is understood that the value of the particle apparent density rhop of the porous
carbon material in Example 1 is smaller than those of Comparative Examples 1A to ID
and the value of the particle porosity epsilonp is higher than those of Comparative
Examples 1A to ID as listed in Table 2. Further, it is understood that the value of the
filling density rhob of the granular porous carbon material in Example 1 is smaller than
those of Comparative Examples 1A to 1C which describe granular samples.
[0069] It is understood that the volume value (VLi) of a fine pore having a diameter of 20
nm or more based on the water vapor adsorption method in Example 1 is equal to or
more than 0.8 cmVg compared to Comparative Examples 1A to ID as listed in Table 3.
Further, it is understood that the volume value (VL'i) of a fine pore having a diameter
of less than 20 nm based on the water vapor adsorption method in Example 1 is equal
to or more than 0.2 cmVg compared to Comparative Examples 1A to ID. Furthermore,
it is understood that the volume value (VL2) of a fine pore based on the methanol
method in Example 1 is equal to or more than 0.2 cmVg compared to Comparative
Examples 1A to ID.
[0070] The equilibrium adsorption amount of acetone vapor was measured by the following
procedures. That is, the dried sample was added to columns and the mass thereof was
measured. Next, each column was fixed to the gas adsorption device in a thermostatic
bath. In addition, gas of 3.0 vol (relative pressure P/P0 = 0.10) was ventilated to the
gas adsorption device at about 1.0 L/min (900 mL/min and acetone saturated vapor 100
mL/min for dilution) by adjusting acetone vapor flow rate and dry air flow rate to the
columns. Subsequently, the columns were taken off after 15 minutes, 30 minutes, and
45 minutes, and the mass thereof was measured, and then the gas was ventilated until
the mass of the columns became constant, thereby obtaining an acetone equilibrium
adsorption amount in an air atmosphere containing 3 vol of acetone. Similarly, the
acetone equilibrium adsorption amount in an air atmosphere containing 0.6 vol and
0.15 vol of acetone using gas of 0.61 vol (relative pressure P/P0 = 0.02) and gas of
0.15 vol (relative pressure P/P0 = 0.005) was calculated. The results are shown in
Fig. 2 and listed in Table 4 below. In addition, the curve "a" indicates the data of
Example 1 or Example 2, the curve "B" indicates the data of Comparative Example
IB, and the curve "D" indicates the data of Comparative Example ID in Fig. 2 and Fig.
3 described below.
[0071] (Table 4) Acetone equilibrium adsorption amount (unit: acetone milligram/ 1 gram of
sample)
Concentration of acetone (ppm) 1520 6080 30400
Example 1 150 225 300
Comparative Example IB 150 235 240
Comparative Example ID 160 210 275
[0072] In Example 1, since the adsorbing material is specified by defining the acetone
equilibrium adsorption amount in an air atmosphere containing 3 vol of acetone to
0.29 mg/g or more from the test results of the equilibrium adsorption amount of
acetone vapor, it is possible to provide an adsorbing material capable of effectively
adsorbing acetone with high efficiency.
Example 2
[0073] Example 2 is a modification of Example 1 and relates to the adsorbing material
according to the first to fourth embodiments of the present disclosure and further
relates to the adsorbing material according to the sixth embodiment of the present
disclosure. That is, the adsorbing material of Example 2 is an adsorbing material which
adsorbs toluene and is made of a porous carbon material derived from a plant and in
which a toluene equilibrium adsorption amount in an air atmosphere containing 1.5
vol of toluene is 0.5 mg/g or more. Further, the adsorbing material itself is the same
as the adsorbing material of Example 1.
[0074] The equilibrium adsorption amount of toluene vapor was measured by the following
procedures. That is, 0.20 g of the dried sample of Example 2 having a particle diameter
of 0.25 mm to 0.50 mm, 0.20 g of the dried sample of Comparative Example IB, and
0.20 g of the dried sample of Comparative Example ID were used. Subsequently, each
sample was added to the column with a stainless steel net and the mass thereof was
measured. Next, each column was fixed to the gas adsorption device in a thermostatic
bath. In addition, gas of 1.50 vol (relative pressure P/P0 = 0.40) was ventilated to the
gas adsorption device at about 1.0 L/min by adjusting toluene vapor flow rate and dry
air flow rate to the columns. Subsequently, the columns were taken off after 15
minutes, 30 minutes, and 45 minutes, and the mass thereof was measured, and then the
gas was ventilated until the mass of the columns became constant, and then the toluene
equilibrium adsorption amount in an air atmosphere containing 1.5 vol of toluene
was calculated. Similarly, the toluene equilibrium adsorption amount in an air at
mosphere containing 0.37 vol and 0.01 vol of toluene using gas of 0.37 vol
(relative pressure P/P0 = 0.10) and gas of 0.01 vol (relative pressure P/P0 = 0.0027)
was calculated. The results are shown in Fig. 3 and listed in Table 5 below.
[0075] (Table 5) Toluene equilibrium adsorption amount (unit: toluene milligram/1 gram of
sample)
Concentration of toluene (ppm) 100 3700 15000
Example 2 260 380 550
Comparative Example IB 225 305 350
Comparative Example ID 260 385 440
[0076] In Example 2, since the adsorbing material is specified by defining the toluene
equilibrium adsorption amount in an air atmosphere containing 1.5 vol of toluene to
0.5 mg/g or more from the test results of the equilibrium adsorption amount of toluene
vapor, it is possible to provide an adsorbing material capable of effectively adsorbing
toluene with high efficiency.
Example 3
[0077] Example 3 is a modification of Example 1 and relates to the adsorbing material
according to the first to fourth embodiments of the present disclosure and further
relates to the adsorbing material according to the seventh embodiment of the present
disclosure. That is, the adsorbing material of Example 3 is an adsorbing material
adsorbing water vapor, which is made of a porous carbon material derived from a plant
and in which a water vapor equilibrium adsorption amount in an air atmosphere at a
temperature of 40 degrees Celsius in a relative humidity of 84% is 0.50 mg/g or more.
Further, the adsorbing material itself is the same as the adsorbing material of Example
1.
[0078] The equilibrium adsorption amount of water vapor was measured by the following
procedures. That is, the dried sample was added to the column with a stainless steel net
having a volume of 5 ml and the mass thereof was measured. Next, each column was
fixed to the gas adsorption device with a cock provided in a thermostatic bath at 40
degrees Celsius. In addition, the water vapor was ventilated to the gas adsorption
device by adjusting water vapor flow rate and dry air flow rate to the columns and by
changing the flow rate of dry air for dilution and saturated water vapor such that the
relative humidity thereof becomes 98%, 84%, 64%, 50%, 40%, or 20%. Subsequently,
the vapor was ventilated until the mass of the columns became constant and the
equilibrium adsorption amount of water vapor was calculated. The results are shown in
Fig. 4 and listed in (Table 6) below. In addition, in Fig. 4, the curve "a" indicates the
data of Example 3, the curve "B" indicates the data of Comparative Example IB, the
curve "C" indicates the data of Comparative Example 1C, and the curve "D" indicates
the data of Comparative Example ID.
[0079] (Table 6) Water vapor equilibrium adsorption amount (unit: water vapor mg/1 g of
sample)
Relative humidity% of water vapor 20 40 50 64 84 98
Example 3 100 140 230 490 620 640
Comparative Example IB 10 110 250 230 240 250
Comparative Example 1C 40 200 310 370 450 480
Comparative Example ID 25 330 345 345 345 350
[0080] In Example 3, since the adsorbing material is specified by defining the water vapor
equilibrium adsorption amount in an air atmosphere at a temperature of 40 degrees
Celsius in a relative humidity of 84% to 0.50 mg/g or more from the test results of the
equilibrium adsorption amount of water vapor, it is possible to provide an adsorbing
material capable of effectively adsorbing water vapor with high efficiency. Further, as
a result, it is possible to effectively remove a smell component with the adsorbing
material of Example 3 even in a state in which the smell component is attached to
water vapor (water molecules) in the air.
Example 4
[0081] Example 4 is a modification of Example 1 and relates to the adsorbing material
according to the first to fourth embodiments of the present disclosure and further
relates to the adsorbing material according to the eighth embodiment of the present
disclosure. That is, the adsorbing material of Example 4 is an adsorbing material
adsorbing ammonia, which is made of a porous carbon material derived from a plant
and in which when air containing 8 ppm of ammonia gas and having a temperature of
20 degrees Celsius and a relative humidity of 50% is ventilated with a space velocity
of 5 x 102/hour, a removal rate of accumulated ammonia gas until one hour elapses
from the start of ventilation is 0.3 micromol/g or more. In addition, the adsorbing
material itself is the same as the adsorbing material of Example 1.
[0082] The removal rate of accumulated ammonia gas was measured by the following
procedures. That is, the dried sample was added to the column with a stainless steel net
(injection cylinder) having a volume of 30 ml and the mass thereof was measured.
Next, each column was fixed to the gas adsorption device. In addition, air having a
temperature of 20 degrees Celsius and a relative humidity of 50% was flown to the
columns with a rate of about 1.0 L/min for about one and a half hours. Subsequently,
wet air (temperature of 20 degrees Celsius and a relative humidity of 50%) containing
8 ppm of ammonia gas was flown downward with a rate of 250 mL/min (space
velocity 5 x 102/hour) to the column. Next, the concentration of the ammonia gas in the
inlet and the outlet of the column was calculated by a detector tube for ammonia gas in
a desired time interval. Similar test was performed in Comparative Example 1A. The
results are shown in Fig. 5. In addition, in Fig. 5, the curve "a" indicates the data of
Example 4 and the curve "A" indicates the data of Comparative Example 1A.
[0083] In Example 4, when air containing 8 ppm of ammonia gas and having a temperature
of 20 degrees Celsius and a relative humidity of 50% is ventilated with a space
velocity of 5 x 102/hour, since the adsorbing material is specified by defining the
removal rate of accumulated ammonia gas until one hour elapses from the start of ven
tilation to 0.3 micromol/g or more, it is possible to effectively adsorb ammonia with
high efficiency.
Example 5
[0084] Example 5 is a modification of Example 1 and relates to the adsorbing material
according to the first to fourth embodiments of the present disclosure and further
relates to the adsorbing material according to the ninth embodiment of the present
disclosure. That is, the adsorbing material of Example 5 is an adsorbing material
adsorbing acetaldehyde, which is made of a porous carbon material derived from a
plant and in which when air containing 0.14 ppm of acetaldehyde vapor and having a
temperature of 20 degrees Celsius and a relative humidity of 50% is ventilated with a
space velocity of 1.5 x 104/hour, a removal rate of accumulated acetaldehyde vapor
until one hour elapses from the start of ventilation is 0.2 micromol/g or more. Further,
the adsorbing material itself is the same as the adsorbing material of Example 1.
[0085] The removal rate of accumulated acetaldehyde vapor was measured by the following
procedures. That is, the dried sample was added to columns having a volume of 1ml
and the mass thereof was measured. Next, each column was fixed to the gas adsorption
device. In addition, air having a temperature of 20 degrees Celsius and a relative
humidity of 50% was flown to the columns until the mass of the columns became
constant. Subsequently, wet air (temperature of 20 degrees Celsius and a relative
humidity of 50%) containing 0.14 ppm of acetaldehyde vapor was downwardly flown
to the columns with a rate of 250 mL/min (space velocity 1.5 x 104/hour). Next, the
concentration of the acetaldehyde vapor in the inlet and the outlet of the column was
calculated by a detector tube for acetaldehyde vapor in a desired time interval. A
similar test was performed in Comparative Example 1A. The results are shown in Fig.
6. In addition, in Fig. 6, the curve "a" indicates the data of Example 5 and the curve
"A" indicates the data of Comparative Example 1A.
[0086] In Example 5, when air containing 0.14 ppm of acetaldehyde vapor and having a
temperature of 20 degrees Celsius and a relative humidity of 50% is ventilated with a
space velocity of 1.5 x 104/hour, since the adsorbing material is specified by defining
the removal rate of accumulated acetaldehyde vapor until one hour elapses from the
start of ventilation to 0.2 micromol/g or more, it is possible to effectively adsorb ac
etaldehyde with high efficiency.
[0087] Hereinbefore, the present disclosure is described with reference to the preferred
Examples, but the present disclosure is not limited thereto and various modifications
are possible. In Examples, the case where the chaff was used as the raw material of the
porous carbon material is described, but other plants may be used as a raw material.
Here, examples of other plants may include straw, reeds, wakame seaweed stems, tracheophytes
growing on the ground, ferns, bryophytes, algae, and seaweeds. In
addition, these materials may be used alone or plural kinds thereof may be used as a
mixture. Specifically, for example, rice straw (product of Kagoshima: Isehikari) is used
as a material derived from a plant as a raw material of a porous carbon material, and
the porous carbon material is converted to a carbonaceous material (porous carbon
material precursor) by carbonizing the straw as a raw material, which can be achieved
by applying an acid treatment. Alternatively, reeds of rice are used as a material
derived from a plant as a raw material of the porous carbon material and the porous
carbon material is converted to a carbonaceous material (porous carbon material
precursor) by carbonizing the reeds of rice as a raw material, which can be achieved by
applying an acid treatment. In addition, even in the porous carbon material obtained by
being treated in alkali (base) such as an aqueous solution of sodium hydroxide instead
of an aqueous solution of hydrofluoric acid, the same results were obtained.
[0088] Alternatively, wakame stems (product of Sanriku of Iwate-ken) are used as a material
derived from a plant as a raw material of a porous carbon material and the porous
carbon material is converted to a carbonaceous material (porous carbon material
precursor) by carbonizing the wakame stems as a raw material and can be achieved by
applying an acid treatment. Specifically, for example, the wakame stems are heated
with a temperature of about 500 degrees Celsius to be carbonized. In addition, the
wakame stems as a raw material may be treated with alcohol before heating. As a
specific treatment method, a method for immersing a material in ethyl alcohol or the
like, and by doing this, it is possible to reduce the moisture contained in a raw material
and elute mineral components or other elements other than carbon contained in the
finally obtained porous carbon material. Further, it is possible to prevent gas from
being generated during the carbonization by treating with alcohol. More specifically,
the wakame stems are immersed in ethyl alcohol for 48 hours. Moreover, it is
preferable that an ultrasonication treatment be performed in ethyl alcohol. Next, the
wakame stems are carbonized by being heated in a nitrogen gas stream at 500 degrees
Celsius for 5 hours, thereby obtaining carbides. Further, it is possible to reduce or
remove a tar component to be generated during the next carbonization by applying
such a preliminary carbonization treatment. Subsequently, 10 g of the carbides were
put into an alumina crucible, the temperature therein was raised up to 1000 degrees
Celsius with a temperature raising rate of 5 degree/min in a nitrogen gas stream (10 U
min), and carbonization was carried out at 1000 degrees Celsius for 5 hours, and the
resultant was converted to a carbonaceous material (porous carbon material precursor)
to be cooled to room temperature. In addition, the nitrogen gas was continuously flown
during the carbonization and the cooling. Subsequently, the acid treatment was carried
out by immersing the porous carbon material precursor in an aqueous solution of h y
drofluoric acid of 46 vol/% for one night, and then the resultant was washed with water
and ethyl alcohol until the pH thereof became 7 and then was dried, thereby obtaining
a porous carbon material.
[0089] Further, the present disclosure may have the following configurations.
(A01) (Adsorbing material: first embodiment)
An adsorbing material for a filter for air purification, which is made of a porous
carbon material derived from a plant and in which a value of particle porosity epsilonp
is 0.7 or more.
(A02) The adsorbing material for a filter for air purification according to (A01), in
which particle apparent density rhop is 0.5 g/mL or less.
(A03) The adsorbing material for a filter for air purification according to (A01) or
(A02), in which the particle porosity epsilonp is defined as follows:
particle porosity epsilonp= alpha*beta*rhop,
here,
rhOp is particle apparent density (unit: gram/milliliter) and calculated by l/(l/rho t +
alpha*beta).
rhot is particle true density (unit: gram/milliliter) and calculated by (sample mass/
sample volume).
alpha is water content (g-water/g-wet) per wet weight,
beta is a conversion factor of dry weight (g-wet/g-dry).
(A04) The adsorbing material for a filter for air purification according to any one of
(A01) to (A03), which adsorbs acetone.
(A05) The adsorbing material for a filter for air purification according to any one of
(A01) to (A03), which adsorbs toluene.
(A06) The adsorbing material for a filter for air purification according to any one of
(A01) to (A03), which adsorbs ammonia.
(A07) The adsorbing material for a filter for air purification according to any one of
(A01) to (A03), which adsorbs acetaldehyde.
(A08) The adsorbing material for a filter for air purification according to any one of
(A01) to (A03), which adsorbs water vapor.
(B01) (Adsorbing material: second embodiment)
An adsorbing material for a filter for air purification, which is made of a granular
porous carbon material derived from a plant, in which a value of filling density rhob is
0.2 g/mL or less.
(B02) The adsorbing material for a filter for air purification according to (B01), in
which the filling density rhob is calculated by obtaining the volume of 5.00 g of a dry
porous carbon material having a particle diameter of 0.25 mm to 0.50 mm and by
dividing the mass value of the dry porous carbon material by the volume value thereof.
(B03) The adsorbing material for a filter for air purification according to (B01) or
(B02), in which an aspect ratio of the granular porous carbon material is 20 or less.
(B04) The adsorbing material for a filter for air purification according to any one of
(B01) to (B03), which adsorbs acetone.
(B05) The adsorbing material for a filter for air purification according to any one of
(B01) to (B03), which adsorbs toluene.
(B06) The adsorbing material for a filter for air purification according to any one of
(B01) to (B03), which adsorbs ammonia.
(B07) The adsorbing material for a filter for air purification according to any one of
(B01) to (B03), which adsorbs acetaldehyde.
(B08) The adsorbing material for a filter for air purification according to any one of
(B01) to (B03), which adsorbs water vapor.
(C01) (Adsorbing material: third embodiment)
An adsorbing material for a filter for air purification, which is made of a porous carbon
material derived from a plant and in which a volume of a fine pore having a diameter
of 20 nm or more is 1.0 mL/g or more based on a water vapor adsorption method.
(C02) The adsorbing material for a filter for air purification according to (C01), which
adsorbs acetone.
(C03) The adsorbing material for a filter for air purification according to (C01), which
adsorbs toluene.
(C04) The adsorbing material for a filter for air purification according to (C01), which
adsorbs ammonia.
(C05) The adsorbing material for a filter for air purification according to (C01), which
adsorbs acetaldehyde.
(C06) The adsorbing material for a filter for air purification according to (C01), which
adsorbs water vapor.
(DOl) (Adsorbing material: fourth material)
An adsorbing material for a filter for air purification, which is made of a porous carbon
material derived from a plant and in which a volume of a fine pore having a diameter
of 1 nm or more is 0.6 mL/g or more based on a methanol method.
(D02) The adsorbing material for a filter for air purification according to (DOl), which
adsorbs acetone.
(D03) The adsorbing material for a filter for air purification according to (DOl), which
adsorbs toluene.
(D04) The adsorbing material for a filter for air purification according to (DOl), which
adsorbs ammonia.
(D05) The adsorbing material for a filter for air purification according to (DOl), which
adsorbs acetaldehyde.
(D06) The adsorbing material for a filter for air purification according to (DOl), which
adsorbs water vapor.
(E01) (Adsorbing material: fifth embodiment)
An adsorbing material adsorbing acetone, which is made of a porous carbon material
derived from a plant and in which an equilibrium adsorption amount of acetone in an
air atmosphere containing 3 vol of acetone is 0.29 mg/g or more.
(F01) (Adsorbing material: sixth embodiment)
An adsorbing material adsorbing toluene, which is made of a porous carbon material
derived from a plant and in which an equilibrium adsorption amount of toluene in an
air atmosphere containing 1.5 vol% of toluene is 0.5 mg/g or more.
(G01) (Adsorbing material: seventh embodiment)
An adsorbing material adsorbing water vapor, which is made of a porous carbon
material derived from a plant and in which an equilibrium adsorption amount of water
vapor in an air atmosphere having a temperature of 40 degrees Celsius and a relative
humidity of 84% is 0.50 mg/g or more.
(H01) (Adsorbing material: eighth embodiment)
An adsorbing material adsorbing ammonia, which is made of a porous carbon material
derived from a plant and in which when air containing 8 ppm of ammonia gas and
having a temperature of 20 degrees Celsius and a relative humidity of 50% is
ventilated with a space velocity of 5 x 102/hour, a removal rate of accumulated
ammonia gas until one hour elapses from the start of ventilation is 0.3 micromol/g or
more.
(J01) (Adsorbing material: ninth embodiment)
An adsorbing material adsorbing acetaldehyde, which is made of a porous carbon
material derived from a plant and in which when air containing 0.14 ppm of ac
etaldehyde vapor and having a temperature of 20 degrees Celsius and a relative
humidity of 50% is ventilated with a space velocity of 1.5 x 104/hour, a removal rate of
accumulated acetaldehyde vapor until one hour elapses from the start of ventilation is
0.2 micromol/g or more.
(Additional Embodiments)
(K) An adsorbing material comprising: a porous carbon material derived from a raw
material including a plant derived material, wherein the porous carbon material
comprises a plurality of fine pores, and wherein the porous carbon material comprises
at least one of a particle apparent density (rhop) of 0.5 g/mL or less, and a particle
porosity (epsilonp) of 0.7 or more.
(K01) The adsorbing material of (K), wherein the porous carbon material includes a
first pore volume having a first diameter greater than 20 nm, wherein the porous
carbon material includes a second pore volume having a second diameter less than 20
nm, and wherein the first pore volume is greater in number than the second pore
volume.
(K02) The adsorbing material of (K), wherein a fine pore volume of at least one of the
fine pores is 0.1 cm g or more.
(K03) The adsorbing material of (K), wherein the porous carbon material has a particle
true density (rhot) of 1.99 g/mL.
(K04) The adsorbing material of (K), wherein the fine pores include a mesofine pore
having a mesofine pore diameter ranging from 2nm to 50 nm, and at least one of a
macrofine pore having a macrofine pore diameter of more than 50nm and a mircofine
pore having a mircofine pore diameter of less than 2nm.
(K05) The adsorbing material of (K), wherein the adsorbing material is granular with
an aspect ratio of 20 or less.
(K06) The adsorbing material of (K), wherein the porous carbon material has a filling
porosity (epsilonb) of 0.6.
(K07) The adsorbing material of (K), wherein the porous carbon material has a filling
density (rhob) of 0.2 g/mL or less.
(K08) The adsorbing material of (K), wherein the plant derived material is selected
from the group consisting of chaff, rice chaff, barley, wheat, rye, barnyard millet,
millet, straw, coffee beans, tea leaves, sugarcanes, mealies, fruit skins, a reed, and a
wakame seaweed stem.
(K09) The adsorbing material of (K), wherein the porous carbon material is capable of
adsorbing at least one of acetone, toluene, water vapor, ammonia, and acetaldehyde.
(K10) The adsorbing material of (K), wherein the porous carbon material has a surface
that is treated by any one of a chemical treatment and a molecular modification.
(Kl 1) The adsorbing material of (K), further comprising a polymer wherein the porous
carbon material and the polymer form a complex material.
(K12) The adsorbing material of (K), further comprising a supporting member
configured to support the porous carbon material.
(L) A filter comprising an adsorbing material, the adsorbing material comprising a
porous carbon material derived from a raw material including a plant derived material,
wherein the porous carbon material comprises a plurality of fine pores, and wherein the
porous carbon material comprises at least one of a particle apparent density (rhop) of
0.5 g/mL or less, and a particle porosity (epsilonp) of 0.7 or more.
(L01) The filter of(L), wherein the porous carbon material includes a first pore volume
having a first diameter greater than 20 nm, wherein the porous carbon material
includes a second pore volume having a second diameter less than 20 nm, and wherein
the first pore volume is greater in number than the second pore volume.
(L02) The filter of (L), wherein the fine pores include a mesofine pore having a
mesofine pore diameter ranging from 2nm to 50 nm.
(L03) The filter of (L), wherein the porous carbon material has a filling density (rhob)
of 0.2 g/mL or less.
(L04) The filter of (L), wherein the plant derived material is selected from the group
consisting of chaff, rice chaff, barley, wheat, rye, barnyard millet, millet, straw, coffee
beans, tea leaves, sugarcanes, mealies, fruit skins, a reed, and a wakame seaweed stem.
(L05) The filter of (L), wherein the porous carbon material is capable of adsorbing at
least one of acetone, toluene, water vapor, ammonia, and acetaldehyde.
(L06) The filter of (L), wherein the porous carbon material has a surface that is treated
by any one of a chemical treatment and a molecular modification.
(L07) The filter of (L), further comprising a polymer wherein the porous carbon
material and the polymer form a complex material.
(L08) The filter of (L), further comprising a supporting member configured to support
the porous carbon material.
It should be understood by those skilled in the art that various modifications, com
binations, sub-combinations and alterations may occur depending on design re
quirements and other factors insofar as they are within the scope of the appended
claims or the equivalents thereof.

Claims
An adsorbing material comprising: a porous carbon material derived
from a raw material including a plant derived material, wherein the
porous carbon material comprises a plurality of fine pores, and wherein
the porous carbon material comprises at least one of a particle apparent
density (rhop) of 0.5 g/mL or less, and a particle porosity (epsilonp) of
0.7 or more.
The adsorbing material of claim 1, wherein the porous carbon material
includes a first pore volume having a first diameter greater than 20 nm,
wherein the porous carbon material includes a second pore volume
having a second diameter less than 20 nm, and wherein the first pore
volume is greater in number than the second pore volume.
The adsorbing material of claim 1, wherein a fine pore volume of at
least one of the fine pores is 0.1 cmVg or more.
The adsorbing material of claim 1, wherein the porous carbon material
has a particle true density (rhot) of 1.99 g/mL.
The adsorbing material of claim 1, wherein the fine pores include a
mesofine pore having a mesofine pore diameter ranging from 2nm to
50 nm, and at least one of a macrofine pore having a macrofine pore
diameter of more than 50nm and a mircofine pore having a mircofine
pore diameter of less than 2nm.
The adsorbing material of claim 1, wherein the adsorbing material is
granular with an aspect ratio of 20 or less.
The adsorbing material of claim 1, wherein the porous carbon material
has a filling porosity (epsilonb) of 0.6.
The adsorbing material of claim 1, wherein the porous carbon material
has a filling density (rhob) of 0.2 g/mL or less.
The adsorbing material of claim 1, wherein the plant derived material is
selected from the group consisting of chaff, rice chaff, barley, wheat,
rye, barnyard millet, millet, straw, coffee beans, tea leaves, sugarcanes,
mealies, fruit skins, a reed, and a wakame seaweed stem.
The adsorbing material of claim 1, wherein the porous carbon material
is capable of adsorbing at least one of acetone, toluene, water vapor,
ammonia, and acetaldehyde.
The adsorbing material of claim 1, wherein the porous carbon material
has a surface that is treated by any one of a chemical treatment and a
molecular modification.
WO 2014/141619 PCT/JP2014/001126
[Claim 12] The adsorbing material of claim 1, further comprising a polymer
wherein the porous carbon material and the polymer form a complex
material.
[Claim 13] The adsorbing material of claim 1, further comprising a supporting
member configured to support the porous carbon material.
[Claim 14] A filter comprising an adsorbing material, the adsorbing material
comprising a porous carbon material derived from a raw material
including a plant derived material, wherein the porous carbon material
comprises a plurality of fine pores, and wherein the porous carbon
material comprises at least one of a particle apparent density (rhop) of
0.5 g/mL or less, and a particle porosity (epsilon p) of 0.7 or more.
[Claim 15] The filter of claim 14, wherein the porous carbon material includes a
first pore volume having a first diameter greater than 20 nm, wherein
the porous carbon material includes a second pore volume having a
second diameter less than 20 nm, and wherein the first pore volume is
greater in number than the second pore volume.
[Claim 16] The filter of claim 14, wherein the fine pores include a mesofine pore
having a mesofine pore diameter ranging from 2nm to 50 nm.
[Claim 17] The filter of claim 14, wherein the porous carbon material has a filling
density (rhob) of 0.2 g/mL or less.
[Claim 18] The filter of claim 14, wherein the plant derived material is selected
from the group consisting of chaff, rice chaff, barley, wheat, rye,
barnyard millet, millet, straw, coffee beans, tea leaves, sugarcanes,
mealies, fruit skins, a reed, and a wakame seaweed stem.
[Claim 19] The filter of claim 14, wherein the porous carbon material is capable of
adsorbing at least one of acetone, toluene, water vapor, ammonia, and
acetaldehyde.
[Claim 20] The filter of claim 14, wherein the porous carbon material has a surface
that is treated by any one of a chemical treatment and a molecular mod
ification.
[Claim 21] The filter of claim 14, further comprising a polymer wherein the porous
carbon material and the polymer form a complex material.
[Claim 22] The filter of claim 14, further comprising a supporting member
configured to support the porous carbon material.