1. A deodorant made of silicicolous plant-derived biomass as a raw material, comprising: a composite with 50 to 100 wt. % amorphous silica and 0 to 50 wt. % carbon.

2. The deodorant according to claim 1, comprising acid sites on a surface of the amorphous silica.

3. The deodorant according to claim 1, comprising base sites on a surface of the amorphous silica.

4. A method for producing a deodorant made of silicicolous plant-derived biomass as a raw material, comprising: a gasification treatment step of gasifying the biomass to obtain a composite with 50 wt. % or more amorphous silica and less than 50 wt. % carbon.

5. The method for producing a deodorant according to claim 4, further comprising a pulverization treatment step of pulverizing the composite obtained in the gasification treatment step.

6. The method for producing a deodorant according to claim 4 or 5, further comprising an acid treatment step of bringing the composite obtained in the gasification treatment step into contact with an acid solution. 20

7. The method for producing a deodorant according to claim 4 or 5, further comprising an alkali treatment step of bringing the composite obtained in the gasification treatment step into contact with an alkali solution.

FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. DEODORANT AND METHOD FOR PRODUCING DEODORANT
2.
1. (A) KUBOTA CORPORATION
(B) Japan
(C) 1-2-47, Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka 5568601 Japan
The following specification particularly describes the invention and the manner in
which it is to be performed.
2
DESCRIPTION
Technical Field
[0001] The present invention relates to a deodorant made of silicicolous
plant-derived biomass, such as rice hulls, as a raw material and a method for
producing the same.
Background Art
[0002] Patent Literature 1 discloses an oil or gas adsorbent that is obtained by
continuously carbonizing plant- or animal-derived organic waste using a kiln
furnace. According to its disclosure, plant- or animal-derived organic materials
are used as raw materials to be carbonized. Specifically, coffee bean grounds,
plum seeds, bean curd refuse, cattle manure, pig manure, sludge, rice hulls,
paulownia thinnings, cedar thinnings, sawdust, and other organic materials are
used, and rice hulls, paulownia thinnings, and cedar thinnings are more preferred
among plant-derived organic materials.
Citation List
Patent Literature
[0003] Patent Literature 1: Japanese Patent No. 6431469
Summary of Invention
Technical Problem
[0004] In recent years, the global warming has been an urgent issue to be solved,
and countries around the world have been pushing for a shift to renewable energy
in an effort to contribute to decarbonization. Meanwhile, a resource-recycling
circular economy has been advocated as an economic model for sustainable
3
growth, and biomass switching of raw materials for various products has been
contemplated as an approach to realize it. Rice hulls, which are agricultural
biomass, are produced about 2 million tons per year in Japan and contain a high
concentration (20%) of silica as an inorganic component. So, effective
utilization of rice hulls can contribute to both decarbonization and resource
recycling.
[0005] The deodorant disclosed in Patent Literature 1 utilizes porous carbon,
which is obtained by carbonizing plant- or animal-derived organic waste, as a
material that exhibits deodorizing ability. Patent Literature 1 illustrates rice hulls
as an example raw material, but it merely discloses utilizing carbon components
obtained from the carbonization as a material that exhibits deodorizing ability.
[0006] It is an object of the present invention to provide a deodorant containing
silica with a deodorizing function and a method for producing the same, by using
silicicolous plant-derived biomass as a raw material.
Solution to Problem
[0007] To achieve the above object, a deodorant made of silicicolous
plant-derived biomass as a raw material is provided. As a first feature of the
deodorant, the deodorant includes a composite with 50 to 100 wt. % amorphous
silica and 0 to 50 wt. % carbon.
[0008] Amorphous silica adsorbs odor gas components, resulting in good
deodorizing ability of the deodorant. When the deodorant contains carbon, it can
combine the deodorizing ability of the porous carbon.
[0009] In addition to the first feature above, the deodorant has a second feature
that the deodorant includes acid sites on a surface of the amorphous silica.
[0010] Including acid sites on the surface of amorphous silica increases the
4
deodorizing ability for basic odor gases. The phrase “including acid sites on the
surface” means, for example, that a reactive group serving as an acid site is added
to one of the binders that the silica possesses.
[0011] In addition to the first feature above, the deodorant has a third feature that
the deodorant includes base sites on a surface of the amorphous silica.
[0012] Including base sites on the surface of amorphous silica increases the
deodorizing ability for acidic odor gases. The phrase “including base sites on the
surface” means, for example, that a reactive group serving as a base site is added
to one of the binders that the silica possesses.
[0013] A method for producing a deodorant made of silicicolous plant-derived
biomass as a raw material is also provided in accordance with the present
invention. As a first feature of the method, the method includes a gasification
treatment step of gasifying the biomass to obtain a composite with 50 wt. % or
more amorphous silica and less than 50 wt. % carbon.
[0014] Organic components are removed by the gasification treatment of
biomass, resulting in a composite of amorphous silica and residual carbon
exhibiting deodorizing ability.
[0015] In addition to the first feature above, the method has a second feature that
the method further includes a pulverization treatment step of pulverizing the
composite obtained in the gasification treatment step.
[0016] The exposed area of amorphous silica increases as the composite is
pulverized in the pulverization treatment step, thereby enhancing the deodorizing
ability.
[0017] In addition to the first or second feature above, the method has a third
feature that the method further includes an acid treatment step of bringing the
composite obtained in the gasification treatment step into contact with an acid
5
solution.
[0018] In addition to the first or second feature above, the method has a fourth
feature that the method further includes an alkali treatment step of bringing the
composite obtained in the gasification treatment step into contact with an alkali
solution.
Advantageous Effects of Invention
[0019] As described above, the present invention can provide a deodorant
containing silica with a deodorizing function and a method for producing the
same, by using silicicolous plant-derived biomass as a raw material.
Brief Description of Drawings
[0020] FIG. 1 illustrates an example deodorant production apparatus.
FIG. 2 illustrates a gasification furnace.
FIG. 3A illustrates the composition of rice hulls used as a sample, and
FIG. 3B illustrates conditions in a gasification treatment step.
FIG. 4A illustrates the properties of a synthesis gas produced by the
gasification treatment, and FIG. 4B illustrates the composition of a composite
obtained by the gasification treatment.
FIG. 5A illustrates relationship between the steam ratio, gasification rate,
and composite specific surface area, FIG. 5B illustrates the pore distribution of the
composite, and FIG. 5C illustrates the results of gas-phase adsorption testing for
odorants.
FIG. 6A illustrates the results of component analysis of each composite,
and FIG. 6B illustrates the pore volume distributions of each composite.
FIG. 7A illustrates a characteristic graph from the results of testing of the
6
deodorizing effect of each composite for multiple types of odor gas components,
and FIG. 7B illustrates the characteristic values of the results of the testing.
Description of Embodiments
[0021] An example deodorant and an example method for producing the same
according to the present invention are described below.
The present invention is applicable to agricultural waste that is biomass
derived from silicicolous plants, such as rice hulls, rice straw, wheat straw,
bamboo, corn, sugarcane, silver grass, and horsetail. For example, rice hulls
contain about 70% carbohydrates, such as cellulose, hemicellulose, and lignin, and
about 15-20% silica, with the balance being dominantly water and trace amounts
of alkali impurities. The present invention is suitable for recycling such
silica-containing biomass as a resource. The present invention is described
below, taking rice hulls as an example.
[0022] FIG. 1 illustrates an example deodorant production apparatus used to
implement a method for producing a deodorant made of rice hulls as a raw
material.
The deodorant production apparatus includes a gasification furnace 10 to
pyrolyze and gasify rice hulls as biomass, a separation mechanism 20 (e.g.,
centrifugal cyclone filter) to separate a biomass residue from a mixture of the
pyrolysis gas and the biomass residue discharged from the gasification furnace 10,
and a pulverizer 30 to pulverize the biomass residue separated by the separation
mechanism 20. The biomass residue separated by the separation mechanism 20
is to become a deodorant.
[0023] The pyrolysis gas separated by the separation mechanism 20 is induced
by an induced draft fan 28 along an exhaust gas path, and passes through a heat
7
exchanger 22 and is cooled in a gas cooling tower 24. The exhaust gas is
released to the atmosphere after having tar removed by a sawdust filter 26.
[0024] As shown in FIG. 2, the gasification furnace 10 is configured as a vertical
entrained bed furnace with a two-stage cylindrical structure in which the upper
section has a larger diameter than the lower section. The gasification furnace 10
is configured such that rice hulls as a raw material as well as steam and air serving
as gasification agents are supplied from the bottom of the furnace 10, and the rice
hulls are mixed at high speed inside the furnace 10 to be gasified while being
partially combusted, and once the particle size of the rice hulls becomes a certain
size or smaller as the reaction proceeds, they are discharged from the top of the
furnace 10 together with the synthesis gas.
[0025] The rice hulls stored in a rice hull hopper 11 are metered and fed into the
gasification furnace 10 via a screw feeding conveyor 12. The rice hulls are
mixed at high speed in the entrained bed, which is formed by superheated steam
generated by a boiler shown in FIG. 1 and air heated by the heat exchanger shown
in FIG. 1, both supplied from the bottom of the gasification furnace 10.
[0026] The rice hulls fed into the gasification furnace 10 are gasified under
ambient pressure at a high temperature from 550 to 800°C through a water gas
reaction and a water gas shift reaction, and discharged through the discharge port
at the top. The water gas reaction occurs mainly in a lower region R1 of the
gasification furnace 10, while the water gas shift reaction occurs mainly in an
upper region R2 located in the upper section of the gasification furnace 10.
[0027] The water gas reaction refers to an endothermic reaction in which carbon
monoxide CO and hydrogen H2 are generated from solid carbon C, which is
biomass, and steam H2O in a high temperature environment at or above 500°C, as
shown in the following formula. In addition to a steam supply unit, an oxygen
8
supply unit is provided to supply a small amount of oxygen gas or air to the
gasification furnace 10, and the necessary reaction heat is provided through
combustion of some of the biomass. In the present embodiment, the temperature
is adjusted to 550 to 650°C.
C + H2O → CO + H2
[0028] The water gas shift reaction refers to an exothermic reaction in which
carbon dioxide CO2 and hydrogen H2 are generated from carbon monoxide CO
and steam H2O, typically in a high temperature environment at about 800, as
shown in the following formula. In the present embodiment, the temperature is
adjusted to 700 to 800°C to ensure that the silica in the rice hulls remains in an
amorphous state.
CO + H2O → CO2 + H2
[0029] The synthesis gas generated from the biomass through the water gas
reaction occurring in the lower region R1, carbides, and ash containing silica
generated from the biomass through the water gas reaction rise to the upper region
R2 along the gas flow direction, accelerating the water gas shift reaction described
above. The steam required for the water gas shift reaction is supplied from the
steam supply unit, and the steam that was not used in the water gas reaction in the
lower region R1 is used.
[0030] The temperature at which the rice hulls are pyrolyzed in the gasification
furnace 10 is required to be at least in a temperature range lower than the phase
transition temperature range in which silica contained in the rice hulls crystallizes,
for example, in a temperature range at or below 800°C. This is because
crystallization of silica is disadvantageous for industrial use in terms of impact on
health.
[0031] In addition, the ratio of air (oxygen) supplied to the gasification furnace
9
10 can be adjusted to mainly accelerate the gasification reaction of the rice hulls or
mainly accelerate the combustion reaction of the rice hulls. This in turn allows
for adjusting the composition of the biomass residue that contains silica (ash) and
carbides (char) separated by the separation mechanism. When the gasification
reaction is accelerated, a composite with high carbon content in addition to the
silica content is obtained. When the combustion reaction is accelerated, a
composite with high silica content and very low carbon content is obtained.
[0032] In other words, a gasification treatment step of gasifying the biomass in
the gasification furnace 10 provides a deodorant production method that can yield
a composite with 50 wt. % or more amorphous silica and less than 50 wt% carbon.
In addition, a pulverization treatment step of pulverizing the composite obtained
in the gasification treatment step by the pulverizer 30 can enhance the deodorizing
ability. In general, carbon-based deodorants tend to have reduced deodorizing
ability when pulverized. However, deodorants made of a silica-containing
composite can have increased deodorizing ability when pulverized. This is
presumably because the pulverization exposes new surfaces of silica that exhibit
the adsorption performance.
[0033] As a resulting deodorant, the carbon content exhibits hydrophobicity
while the silica content exhibits hydrophilicity. Accordingly, when producing a
deodorant mixed with an aqueous composition, the more the hydrophilic silica
content, the more evenly the composite is distributed in the mixture, which results
in a deodorant with higher deodorizing ability. Conversely, it is difficult to
distribute the hydrophobic carbon content evenly in the mixture. Accordingly,
when producing such a deodorizer, it is preferred to carry out the gasification
treatment step in an environment that accelerates the combustion reaction.
[0034] In addition, carrying out an acid treatment step of bringing the composite
10
obtained in the gasification treatment step and/or the composite pulverized in the
pulverization treatment step into contact with an acid solution can yield a
deodorant with acid sites on the surface of the amorphous silica, which can
improve the deodorizing ability for basic odorants. For example, a powdered
deodorant with acid sites on the surface of the amorphous silica can be obtained
by immersing the composite in hydrochloric acid and stirring it with a stirrer or
other means for a predetermined period of time and then drying it.
[0035] In addition, carrying out an alkaline treatment step of bringing the
composite obtained in the gasification treatment step and/or the composite
pulverized in the pulverization treatment step into contact with an alkaline
solution can yield a deodorant with base sites on the surface of the amorphous
silica, which can improve the deodorizing ability for acidic odorants. For
example, a powdered deodorant with base sites on the surface of the amorphous
silica can be obtained by immersing the composite in a sodium hydroxide solution
and stirring it with a stirrer or other means for a predetermined period of time and
then drying it.
[0036] Acidic odorants are acidic gases that cause bad odors, specifically
including acetic acid, isovaleric acid, and butyric acid. Basic odorants are basic
gases that cause bad odors, specifically including ammonia and organic amines,
which are generated in large quantities in sewage treatment plants, night soil
treatment plants, garbage incinerators, etc.
EXAMPLES
[0037] Porous, amorphous deodorants were produced by activating rice hulls
through gasification treatment using a test plant that emulated the deodorant
production apparatus described above, and their adsorption performance for
11
odorous gases was evaluated.
[0038] FIG. 3A shows the composition of the rice hulls used as a sample. In
order to understand the differences in properties depending on where rice hulls
were produced, rice hulls of twelve varieties from eight prefectures were analyzed,
including those that were tested. There were no major differences found
depending on where the rice hulls were produced; they contain about 80%
combustible content (organic components) and about 20% ash (inorganic
components). About half of the combustible content is carbon. About 95% of
the ash is silica (SiO2), with K, Ca, P and other fertilizer components accounting
for the remaining few percent.
[0039] The deodorants were produced using the test plant with a capacity of 1
t/day (based on rice hull input). As described above, the gasification furnace 10
is of an entrained bed type with a two-stage cylindrical structure. Rice hulls as a
raw material as well as steam (boiler steam) and air as gasification agents are
supplied from the bottom of the furnace, and the rice hulls are mixed at high speed
inside the furnace to be gasified while being partially combusted, and once the
particle size of the rice hulls becomes a certain size or smaller as the reaction
proceeds, they are discharged from the top of the furnace together with the
synthesis gas. The silica-containing composite discharged from the gasification
furnace 10 is collected by the cyclone.
[0040] FIG. 3B shows the plant operation conditions. The furnace temperature
was adjusted to 550 to 650°C in the lower region R1 and to 700 to 800°C in the
upper region R2.
Under gasification acceleration conditions (RUN1), the air ratio (O2/C
ratio) was set to 0.3 and the steam ratio (H2O/C ratio) was varied from 0.8 to 1.8
based on 1.5, and the specific surface areas of the produced silica-containing
12
composites were evaluated in a comparative manner. The operation was also
conducted under combustion acceleration conditions (RUN2) where the air ratio
was increased to 1.4, and a silica-containing composite with a low carbon
concentration was evaluated.
[0041] FIG. 4A shows the average properties of the synthesis gases. Under the
gasification acceleration conditions (RUN1), reducing components, CO, H 2, and
CH4, were the major compositions, and under the combustion acceleration
conditions (RUN2), oxidizing components, O 2 and CO2, were the major
compositions. Under the gasification acceleration conditions (RUN1), the
processing of 1 kg of the rice hulls resulted in the discharge of 0.26 kg of the
silica-containing composite and 1.45 Nm3 (dry) of the synthesis gas, and the
conversion rate of C in the rice hulls into the synthesis gas (hereinafter referred to
as a “gasification rate”) was calculated to be 62.7%. Also, the calorific value of
the synthesis gas was calculated to be 3,232 kJ/Nm3 , and the cold gas efficiency
was calculated to be 30%.
[0042] FIG. 4B shows the properties of the silica-containing composites.
Under the gasification acceleration conditions (RUN1), about 40% of the
combustible content remained, resulting in a material in which silica was
complexed with carbon. Under the combustion acceleration conditions (RUN2),
in contrast, little combustible content remained, resulting in a high-purity silica
material with a high silica concentration of about 95%. The composite produced
under the gasification acceleration conditions (RUN1) had a high specific surface
area of 224 m2
/g. This is presumably because the carbon in the rice hulls was
activated by the steam during the gasification and thus made porous. By
adjusting the gasification acceleration conditions (RUN1) and combustion
acceleration conditions (RUN2), a deodorant made of a composite with 50 to 100
13
wt. % amorphous silica and 0 to 50 wt. % carbon can be obtained. With other
inorganic components taken into account, a deodorant made of a composite with
50 to 95 wt. % amorphous silica and 0 to 45 wt. % carbon can be obtained.
[0043] FIG. 5A shows the relationship between the steam ratio, gasification rate,
and composite specific surface area when the steam ratio is varied under the
gasification acceleration conditions (RUN1) shown in FIG. 4B. The higher the
steam ratio, the higher the composite specific surface area tended to be. This is
presumably because the higher the steam ratio, the higher the superficial velocity
in the furnace and the shorter the retention time became, resulting in a relative
decrease in the gasification rate and more porous carbon remaining, leading to the
increased specific surface area.
[0044] FIG. 5B shows the results of measurement of the pore distribution of the
composites obtained under the gasification acceleration conditions (RUN 1)
shown in FIG. 4B. The majority of the pores were micropores less than 1 nm.
The identification of crystals by an XRD analysis revealed that silica was
amorphous regardless of the conditions. This is presumably because the
gasification furnace was of an entrained bed type and the rice hulls were
constantly mixed in the furnace, and so there were no local high-temperature
zones in the furnace and the reaction time was also as short as a few tens of
seconds, thus causing no crystallization even at high temperatures.
[0045] The composites (pulverized products) produced under the gasification
acceleration conditions (RUN1) and the combustion acceleration conditions
(RUN2) were subjected to gas-phase adsorption testing for ten types of odorants
to evaluate their adsorption characteristics.
One corner of a 10L gas bag was cut, and a petri dish carrying 10 mg of
the composite was inserted into the bag, which was then closed. The odorant to
14
be adsorbed was injected with a syringe to a predetermined concentration (set
based on the odor threshold), followed by leaving the bag to stand at room
temperature for 1 hour. After that, a portion of the bag gas was collected, and the
concentration of the odorant was quantified using a detector tube or GC-MS to
calculate the adsorption removal rate based on the concentration reduction rate
relative to the blank conditions.
[0046] The test results are shown in FIG. 5C. The composite produced under
the gasification acceleration conditions exhibited a high adsorption removal rate
for a wide range of odorants, including fatty acids, aldehydes and ketones,
aromatics, and sulfurs. The composite produced under the combustion
acceleration conditions also exhibited adsorption ability for some substances.
The composite produced under the gasification acceleration conditions was able to
adsorb a wider range of substances than the composite produced under the
combustion acceleration conditions, presumably because the composite produced
under the gasification acceleration condition was a complex of polar (hydrophilic)
silica and nonpolar (hydrophobic) carbon and thus was able to perform adsorption
by multiple mechanisms, including chemical adsorption by polar functional
groups and physical adsorption by nonpolar portions. Another presumed reason
for the high adsorption rate is that the size of the majority of the pores, which was
less than 1 nm, was approximately the same as the molecules of the odorants.
[0047] Additionally, high-carbon gasification ash, which is a composite in which
silica is complexed with carbon under the gasification acceleration conditions, was
subjected to acid treatment/base treatment to see any change in its adsorption
performance.
[Table 1]
15
COMPOSITE
UNTREATED ACID-WASHED BASE-WAHSED
ACETIC ACID
(ACOH) 50% 21% 78%
ACETALDEHYDE
(A CH) 17% 33% 67%
PYRIDINE
(Py) 33% 83% 38%
[0048] Table 1 shows the adsorption properties for acetic acid, acetaldehyde, and
pyridine of an untreated composite (untreated composite), a composite
(acid-washed composite) dried after undergoing an acid treatment step in which it
was brought into contact with an acid solution (hydrochloric acid), and a
composite (base-washed composite) dried after undergoing an alkali treatment
step in which it was brought into contact with an alkali solution (sodium
hydroxide), each prepared using the composite obtained under the gasification
acceleration conditions shown in FIG. 4B. The alkali-treated, base-washed ash
had good results for acetic acid, which is an acid substance, and acetaldehyde.
The acid-treated, acid-washed ash had good results for pyridine, which is a basic
substance.
[0049] Table 2 shows the results of TPD testing conducted to investigate the
relationship between the adsorption results and the adsorption points of each
composite.
[Table 2]
COMPOSITE
REMARKSUNTREATE
D
ACID-WASH
ED
BASE-WASH
ED
CO2-TPD 100 9 391
INVESTIGATI
ON OF BASE
SITES
NH3-TPD
(WITHOUT 100 110 179 INVESTIGATI
ON OF ACID
16
STEAM
TREATMEN
T)
SITES
NH3-TPD
(WITH
STEAM
TREATMEN
T)
n.d detected n.d
INVESTIGATI
ON OF
STRONG ACID
SITES
*n.d. = not detected
[0050] From the above, the adsorption results for acidic substances (e.g., acetic
acid) are linked with the order of results of CO2-TPD, and thus it can be evaluated
that acidic substances are adsorbed mainly at base sites. The adsorption results
for non-ionic polar substances (e.g., aldehydes) are linked with the order of results
of NH3-TPD without steam treatment, and thus it can be evaluated that polar
substances are adsorbed mainly at acid sites, especially at weak acid sites.
Additionally, the adsorption results for basic substances (e.g., pyridine) are linked
with the order of results of NH3-TPD with steam treatment, and thus it can be
evaluated that basic substances are adsorbed mainly at strong acid sites.
[0051] As shown in FIG. 6A, a composite A obtained under the gasification
acceleration conditions (RUN1) of FIG. 4B, a composite B obtained by
pulverizing the composite A using a mill, a composite C obtained by
alkali-treating the composite A, and a composite D obtained by pulverizing a
composite obtained under the combustion acceleration conditions (RUN2) of FIG.
4B using a mill were prepared.
[0052] FIG. 6B shows the pore distributions of the composite A (raw ash) and
the alkali-treated composite C obtained from the composite A. Both micropore
and mesopore distributions were found to be increased by alkali washing.
[0053] FIGS. 7A and 7B show the results of testing to confirm the deodorizing
effect under blank conditions as well as of the composites A, B, C, and D as rice
17
hull biochar for odor gas components of hydrogen sulfide, sulfurs, ammonia,
amines, organic acids, aldehydes, esters, aromatics, and hydrocarbons, which are
generated from foods (horse mackerel, kimchi, pickled radish, grilled dumplings).
A 5L gas bag was filled with 10 g (sample) of each of the above
composites A, B, C, and D and with each food (odor source) and then sealed,
followed by being left to stand in a refrigerator (thermostatic chamber at 3°C).
Internal gases were sampled after 1 and 3 days and analyzed. The table shows
the results of analysis. While there was little difference under the blank
conditions, a certain deodorizing effect was confirmed for 10 g (sample) of each
of the composites A, B, C, and D. The odor strength was highest under the blank
conditions, followed by the cases of using the composite D, the composite A, the
composite B, and then the composite C.
[0054] From the above, it is clear that amorphous silica-containing deodorants
obtained by gasification of silicicolous plant-derived biomass as a raw material, in
particular amorphous silica-based deodorants produced under the gasification
acceleration conditions, have adsorption ability for a wide range of odorants and
have material properties as deodorants.
[0055] It will be appreciated that the description of the above embodiment is
given for purposes of illustration of some specific examples of the deodorant and
the method for producing the same according to the present invention. The
description does not limit the scope of the present invention, and the specific
composition of the composite can be set as appropriate within the numerical range
described above.
Reference Signs List
[0056] 10: Gasification furnace
18
20: Separation mechanism
22: Heat exchanger
24: Gas cooling tower
26: Sawdust filter
28: Induced draft fan
R1: Lower region
R2: Upper region
19
We Claim:
1. A deodorant made of silicicolous plant-derived biomass as a raw
material, comprising:
a composite with 50 to 100 wt. % amorphous silica and 0 to 50 wt. %
carbon.
2. The deodorant according to claim 1, comprising acid sites on a surface of
the amorphous silica.
3. The deodorant according to claim 1, comprising base sites on a surface of
the amorphous silica.
4. A method for producing a deodorant made of silicicolous plant-derived
biomass as a raw material, comprising:
a gasification treatment step of gasifying the biomass to obtain a
composite with 50 wt. % or more amorphous silica and less than 50 wt. % carbon.
5. The method for producing a deodorant according to claim 4, further
comprising a pulverization treatment step of pulverizing the composite obtained in
the gasification treatment step.
6. The method for producing a deodorant according to claim 4 or 5, further
comprising an acid treatment step of bringing the composite obtained in the
gasification treatment step into contact with an acid solution.
20
7. The method for producing a deodorant according to claim 4 or 5, further
comprising an alkali treatment step of bringing the composite obtained in the
gasification treatment step into contact with an alkali solution.