Note: Descriptions are shown in the official language in which they were submitted.
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Improved Materials
The present invention relates to a method for the transportation and/or
storage of carbon
dioxide.
Due to increased global industrialisation the emissions of carbon dioxide into
the atmosphere
from the burning of fossil fuels is causing significant environmental changes
throughout the
world. There exists therefore an urgent need to reduce the level of carbon
dioxide in the
atmosphere. Whilst reduction of emissions through the use of alternative
greener technologies
is being used to reduce emissions of carbon dioxide, significant levels are
still being released
through the burning of fossil fuels. There are various methods by which carbon
dioxide
produced from the combustion of fossil fuels can be "captured" and stored.
However such
methods are often complex and expensive and long term storage solutions are
problematic.
Current methods of transporting carbon dioxide long distances include via
pipelines or in
tankers. However pipelines are difficult and expensive to build and only
connect particular
points. Tankers such as those used to transport liquefied petroleum gas can
also be used.
However gases having a maximum pressure of about 15 bar can typically be
transported in
this way and thus tankers of this type are not practical for transporting very
large quantities of
carbon dioxide.
The present invention seeks to provide an improved method by which carbon
dioxide, and in
some cases sulfur dioxide can be stored and/or transported.
According to a first aspect of the present invention there is provided a
method of affixing
carbon dioxide onto the surface of a material, the method comprising the steps
of:
(a) contacting a cellulosic material with a composition comprising an amino
compound;
(b) contacting the cellulosic material with a composition comprising a
source of metal ions;
and
(c) contacting the cellulosic material with a composition comprising carbon
dioxide
The method of the present invention involves the treatment of a cellulosic
material.
The cellulosic material may be a natural material or it may be a synthetic
material, or it may be
a semi-synthetic material, for example a natural material processed into a
different form.
Suitable materials include a natural cellulosic material or a semi-synthetic,
processed,
cellulosic material, for example, rayon or lyocell. The cellulosic material
may comprise natural
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fibres and/or synthetic fibres and/or semi-synthetic fibres, for example
regenerated cellulose
products. Preferably the material comprises natural fibres.
The use of natural fibres may help improve the environmental profile of the
product obtained
by the method of the present invention.
Preferably the cellulosic material of the present invention is derived from
plant fibres, for
example vegetable fibres, or wood fibres.
Suitable natural fibres for use in the method of the present invention include
cotton, hemp, flax,
silk, jute, kenaf, ramie, sisal, kapok, agave, rattan, soy bean, vine, banana,
coir, stalk fibres,
wood fibres and mixtures thereof.
The cellulosic material is preferably in the form of small strands or fibres,
or in powdered or
particulate form. The size and shape of the particles or strands of cellulosic
material will
depend on the source from which it is derived. For example the cellulosic
material may
comprise fines from the processing of wood fibres.
In another embodiment the cellulosic material may be derived from the waste
products of
bioethanol production.
Suitably the cellulosic material is provided in the form of strands or
particles having an average
size of less than 5 cm, for example less than 3 cm or less than 1 cm. In some
emboiments the
cellulosic material is provided in the form of strands or particles having an
average size of less
than 5 mm, preferably less than 1 mm. A typical size may be from 1 to 100 pm,
preferably from
5 to 50 pm, preferably from 10 to 20 pm.
Step (a) comprises contacting the cellulosic material with a composition
comprising an amino
compound. The amino compound may be any compound containing an amino or
substituted
amino moiety for example ammonia, an aliphatic or aromatic amine, an amide or
urea.
Preferably the amino compound is selected from ammonia or an amine. Any
suitable amine
may be used including aromatic and aliphatic amines. Preferred amines are
aliphatic amines
for example alkyl amines, alkenyl amines or alkynyl amines. Such amines may be
substituted
or unsubstituted. Suitable substituted amines include amino acids and alcohol
amines
(alkanolamines), for example of formula R1R2R3N where R1 is a group of formula
HO-X- where
X represents a C14 alkylene group, preferably an ethylene group, R2 represents
a hydrogen
atom or a group of formula HO-X-, and R3 represents a hydrogen atom or a group
of formula
HO-X- (the groups X being the same or different). Monoalkanolamines and
dialkanlamines are
preferred, especially ethanolamine (diethanolamine and/or monoethanolomine).
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Especially preferred amines for use herein are alkyl amines, most preferably
unsubstituted
alkyl amines and alkanolamines.
The amino compound may be ammonia, a primary amine, a secondary amine or a
tertiary
amine. Preferred amines for use in step (a) of the present invention are
primary amines,
secondary amines, or mixtures thereof. Especially preferred amines for use
herein are primary
or secondary alkyl amines, especially alkyl amines having up to 12 carbon
atoms, preferably
up to 10 carbon atoms, suitably up to 8 carbon atoms, more preferably up to 6
carbon atoms,
for example up to 4 carbon atoms. Preferred amines for use herein are
methylamine,
dimethylanine, ethylamine, diethylamine, propylamine, dipropylamine,
butylamine,
dibutylamine and mixtures and isomers thereof. In an especially preferred
embodiment step
(a) comprises contacting the surface of the material with a composition
comprising ethylamine,
diethylamine or a mixture thereof.
The composition used in step (a) of the method of the present invention may
comprise neat
concentrated amino compound in gaseous or liquid form or it may comprise one
or more
further components including, for example, a diluent or carrier. Preferably
the composition
used in step (a) is a liquid composition. This may be applied by any suitable
technique such
as will be well known to the person skilled in the art. For example it may be
applied by
spraying, padding or, immersion. Suitably a solution of amine in a solvent may
be applied to
the material and then the material dried to effect evaporation of excess
solvent and/or amine.
Suitable solvents include water, organic solvents and mixtures thereof. In
some embodiments
the composition used in step (a) comprises an amino compound provided as a
vapour.
Suitably in such embodiments the material is placed in a sealed vessel and the
amino
compound vapour is then passed through the vessel.
In preferred embodiments step (a) comprises contacting the cellulosic material
with a
composition comprising at least 10 wt% amino compound, preferably at least 20
wt% amino
compound, suitably at least 40 wt%, at least 60 wt% or at least 70 wt%.
Suitably step (a)
comprises applying a composition comprising up to 100 wt% amino compound, for
example up
to 95 wt% or at least 90 wt%.
In preferred embodiments step (a) comprises contacting the cellulosic material
with a
composition comprising from 10 to 40 wt% amino compound.
Preferably the composition containing an amino compound contains at least 5
wt% water,
preferably at least 10 wt% water, for example about 20 wt% water. In some
embodiments the
composition may comprise up to 50 wt% water.
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Some preferred compositions for use in step (a) consist essentially of water
and the amino
compound. The amino compound is preferably in an amount as defined above and
the water
is the balance of the composition.
The skilled person will however appreciate that commercially available amines
often contain
mixtures and/or impurities.
In some preferred embodiments the composition comprises the amino compound as
a neat
liquid.
However, the presence of water in the composition containing the amino
compound is believed
to be beneficial and is preferred.
Step (a) may be carried out at any suitable temperature and pressure. Suitable
temperatures
include from 0 to 80 C, for example from 5 to 60 C, suitably from 10 to 40 C,
for example from
15 to 35 C. Suitably in step (a) the material is contacted with a composition
comprising an
amino compound at room temperature. Step (a) may be carried out under high
pressure.
However in preferred embodiments step (a) involves contacting the material
with an amino
compound under standard atmospheric pressure.
Preferably the contact time of the cellulosic material with the composition
comprising the amino
compound is from 0.1 to 500 minutes, preferably from 1 to 200 minutes, for
example from 2 to
minutes, suitably from 5 to 60 minutes.,preferably from 10 to 40 minutes.
Suitably in step (a) of the method of the present invention an interaction
occurs between the
surface of the cellulosic material and the amino compound. Any type of
interaction may occur
and depends on the particular amino compound. The surface of the material and
the amino
compound are believed to interact in a way which (though not at present fully
understood)
appears to promote the take-up of carbon dioxide in step (c).
Without being bound by theory, it is believed that hydrogen bonding occurs
between the amino
functionality and the surface of the cellulosic material.
The uptake of the amino compound by the cellulosic material is suitably at
least 5% omf,
preferably at least 10% omf, more preferably at least 15% omf, for example at
least 20 A omf.
The uptake of the amino compound on the cellulosic material may be up to 100%
omf,
preferably up to 80% omf, more preferably up to 70% omf, for example up to 60%
omf.
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By % omf (% on mass of fibre) we mean to refer to the mass of amino compound
as a
percentage of the mass of the fibres treated.
Step (b) of the method of the first aspect of the present involves contacting
the cellulosic
5 material with a source of metal ions.
Suitable metal ions include any monovalent, divalent and trivalent ions,
especially those
having low toxicity.
Preferred metal ions include alkali metal ions and alkaline earth metal ions.
Especially
preferred are alkali metal ions. Most preferred are sodium ions.
The metal ions are preferably provided in aqueous solution. They may be
provided in the form
of a salt.
Preferably the source of metal ions is an alkali metal hydroxide solution.
Most preferably it is a
solution of sodium hydroxide.
Suitably in step (b) the cellulosic material is contacted with a composition
comprising at least 5
wt% of an alkali metal hydroxide, preferably at least 10 wt%, more preferably
at least 15 wt%,
for example at least 20 wt% or at least 25 wt%.
Suitably in step (b) the cellulosic material is contacted with a composition
comprising up to 60
wt% of an alkali metal hydroxide, preferably up to 50 wt%, more preferably up
to 40 .wt%, for
example up to 35 wt%.
Step (b) may be carried out before step (a), after step (a), or at the same
time as step (b).
In some embodiments steps (a) and (b) are carried out simultaneously. Step (a)
may therefore
comprise contacting the cellulosic material with a composition comprising an
amino compound
and a source of metal ions. Such a composition may be prepared by admixing an
aqueous
composition comprising 10 to 50 wt%, preferably 20 to 40 wt% of an alkali
metal hydroxide
with a composition comprising 50 to 10 wt%, preferably 70 to 90 wt% of an
amino compound.
In such embodiments the cellulosic fibres may optionally be contacted with a
further source of
metal ions in a subsequent step.
Preferably step (b) is carried out after step (a).
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Preferably step (b) is carried out at a temperature of from 0 to 100 C,
suitably from 0 to 80 C,
for example from 10 to 50 C. Suitably step (b) is carried out at ambient
pressure. Preferably in
step (b) the cellulosic material is contacted with a composition comprising a
source of metal
ions for a period of between 0.1 and 500 minutes, preferably between 1 and 200
minutes,
more preferably between 2 and 100 minutes, suitably between 5 and 60 minutes,
for example
between 10 and 40 minutes.
The uptake of metal ions in step (b) is preferably at least 1% omf, preferably
at least 5% omf,
suitably at least 10% omf.
The uptake of metal ions on the cellulosic fibre may be up to 100% omf,
suitably up to 75%
omf, for example up to 50% omf or up to 30% omf.
In some embodiments the material obtained following step (b) may be dried
prior to step (c).
Suitable drying conditions will be known to the person skilled in the art.
Step (c) of the method of the present invention involves contacting the
cellulosic material with
a composition comprising carbon dioxide.
Steps (c) of the present invention may be carried out at the same time as
steps (a) and (b),
when these two steps are carried out together. However in preferred
embodiments step (c) is
carried out after step (a) and step (b) and thus step (c) preferably comprises
contacting the
surface of a cellulosic material which has been contacted with an amino
compound and a
source of metal ions with a composition comprising carbon dioxide. Thus step
(b) suitably
involves contacting a cellulosic material carrying an amino compound and a
metal ion with a
composition comprising carbon dioxide.
In the composition used in step (c) the carbon dioxide may be provided as
carbon dioxide gas,
as supercritical carbon dioxide or as solid carbon dioxide. In preferred
embodiments the
carbon dioxide is in gaseous form.
In some embodiments the composition contacted with the material in step (c)
may also
comprise sulfur dioxide.
When the composition used in step (c) comprises sulfur dioxide this is
preferably provided in
gaseous form.
In preferred embodiments the gas used in step (c) is provided by a gaseous
composition
comprising at least 1 wt% carbon dioxide. Preferably composition contacted
with the cellulosic
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material in step (c) is a gaseous composition comprising at least 5 wt% carbon
dioxide,
preferably at least 10 wt% carbon dioxide, preferably at least 20 wt% carbon
dioxide. In some
embodiments step (c) involves treating the cellulosic fibres with a
composition comprising at
least 50 wt% carbon dioxide, for example at least 75 wt%, at least 90 wt% or
at least 95 wt%.
Preferably the composition contacted with the cellulosic material in step (c)
of the method of
the present invention comprises carbon dioxide. In some embodiments the
composition used
in step (c) consists essentially of carbon dioxide.
In some embodiments the composition contacted with the cellulosic material
comprises sulfur
dioxide.
In some preferred embodiments the composition comprises a mixture of carbon
dioxide and
sulfur dioxide. It may comprise other components, suitably other gaseous
components, for
example nitrogen.
In some preferred embodiments the composition contacted with the cellulosic
material in step
(c) comprises or is derived from the exhaust gas of a combustion system. For
example the
composition may comprise the flue gases of a power station, for example a wood-
burning or
coal-burning power station.
In some embodiments such exhaust gases may be concentrated or otherwise
treated prior to
contact with the fibres of cellulosic material.
In especially preferred embodiments the carbon dioxide and/or sulfur dioxide
is provided by
the exhaust of a fossil fuel burning engine, boiler, furnace or turbine. Thus
the present
invention may involve a method of capturing carbon from the atmosphere.
The composition used in step (c) may comprise at least 0.1 wt% sulfur dioxide,
preferably at
least 0.5 wt%, for example at least 1 wt%. It may comprise up to 20 wt% sulfur
dioxide, for
example up to 10 wt% or up to 7 wt%.
In one embodiment the composition contacted with the cellulosic material is a
gaseous
composition comprising from 50 to 90 wt%, preferably 60 to 80 wt% nitrogen,
from 10 to 40
wt%, preferably 20 to 30 wt% carbon dioxide and up to 20 wt%, preferably up to
10 wt% sulfur
dioxide.
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In some embodiments in step (c) a gaseous composition may be pumped into a
vessel
containing the material. In some embodiments the cellulosic material may have
been dried
following steps (a) and (b). Alternatively the material may still be damp.
Step (c) may be carried out at atmospheric pressure or it may be carried out
at higher
pressures. The skilled person will appreciate that when elevated pressures are
used the
contact times needed are generally shorter than when lower pressures are used.
In some embodiments the composition contacted with the material in step (c)
may comprise
carbon dioxide, sulfur dioxide or a mixture thereof along with a diluent or
carrier. In some
embodiments the composition may comprise only carbon dioxide, sulfur dioxide
or a mixture
thereof.
In some preferred embodiments the composition contacted with the material in
step (c)
consists essentially of carbon dioxide, i.e. it is provided from a source of
carbon dioxide
without the addition of a diluent or carrier. Minor impurities may be present.
In embodiments in which the cellulosic material is contacted with neat carbon
dioxide gas this
may be provided at a pressure of up to 40,000kPa, preferably from 100 to 5000
kPa. In some
embodiments carbon dioxide may be delivered to the cellulosic material at
ambient pressure,
and preferably at ambient temperature. In preferred embodiments the carbon
dioxide gas is at
a supra-atmospheric pressure. In one embodiment a pressure of from 2000 to
4000 kPa, for
example about 3000 kPa is used.
Preferably in step (c) the cellulosic material is contacted with the
composition comprising
carbon dioxide for a period of 0.1 to 500 minutes, preferably to 200 minutes,
more preferably
to 100 minutes, suitably 5 to 60 minutes, for example 10 to 40 minutes.
The uptake of carbon dioxide on the cellulosic material is preferably at least
1% omf,
preferably at least 5% omf, more preferably at leas 10% omf, for example at
least 15% omf.
The uptake of carbon dioxide on the cellulosic material may be up to 100% omf,
suitably up to
80% omf, preferably up to 60% omf, for example up to 50% omf or up to 40% omf.
For the avoidance of doubt, the above amounts refer to the increase in weight
of the treated
cellulosic material, i.e. material that carries an amine and metal ions on the
surface thereof.
It is an advantage of the present invention that relatively short contact
times can be used in
steps (a), (b) and (c) to achieve sufficient retention of carbon dioxide and
optionally sulfur
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dioxide on the surface of the cellulosic material. For example contact times
of less than 1
hour, preferably less than 30 minutes can be used, in each of steps (a), (b)
and (c).
Without wishing to be bound by theory it is believed that the carbon dioxide
or sulfur dioxide
interacts with the amino compound which is carried by the surface of the
cellulosic fibres
following step (a). The nature of this interaction is not fully understood. It
is believed that
there may be a polar interaction, a hydrogen bond may form, or covalent
bonding may occur.
Following step (c) the method may provide a cellulosic material in which
carbon dioxide, and
optionally sulfur dioxide, are retained on the surface.
By retained on the surface it is meant that the carbon dioxide and sulfur
dioxide when present
is not labile, i.e. the molecules of carbon dioxide (and optionally sulfur
dioxide) are not merely
associated with the surface and simply present in the same general area.
Rather they are
fixed at the surface. They may be permanently or temporary fixed at the
surface. Suitably the
molecules of carbon dioxide and when present sulfur dioxide are not readily
displaced from the
surface of the cellulosic material without the application of an external
stimulus.
The carbon dioxide and when present sulfur dioxide may be retained on the
surface may
physical and/or by chemical means. For example the carbon dioxide and/or
sulfur dioxide may
be retained by Van der Waals forces, hydrogen bonding or ionic forces.
Preferably the carbon
dioxide and/or sulfur dioxide is retained on the surface by means of a
chemical bond, suitably
a covalent bond.
Following step (c) the carbon dioxide may be permanently retained or bonded or
it may be
retained in a manner such that it could be released later. Hence the carbon
dioxide and, when
present, sulfur dioxide may be fixed to the surface of the material in a
reversible or irreversible
manner.
In some especially preferred embodiments the carbon dioxide and, when present
sulfur
dioxide, retained on the surface is not readily released from the material
under normal storage
and transport conditions. Thus the treated cellulosic material is preferably
stable at all
humidities, at standard atmosphere pressure and at temperatures of between -30
C and 70 C,
for example between -20 C and 60 C, between -10 C and 50 C, or between 0 C and
40 C.
The treated cellulosic material is suitably weatherproof and carbon dioxide is
not released
under normal climatic extremes of heat or cold or in very wet, very dry, windy
or stormy
environments.
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Following step (c) the material may be dried. Suitable drying conditions will
be known to the
person skilled in the art.
In some embodiments the method of the first aspect of the present invention
may include a =
5 further step (d) of forming the material obtained following step (c).
Suitable forming steps will
be known to the person skilled in the art. In one embodiment the material is
formed into pellets
to facilitate transport and improve bulk density.
According to a second aspect of the present invention there is provided a
cellulosic material
10 which has been treated with an amino compound and a source of metal ions
and which has
carbon dioxide retained on the surface thereof.
The material of the second aspect is preferably prepared by the method of the
first aspect.
Preferred features of the second aspect are as defined in relation to the
first aspect.
The material of the second aspect is a material on the surface of which carbon
dioxide is
retained. Thus this material may be used as a means for storing and/or
transporting carbon
dioxide. In some embodiments sulfur dioxide may also be retained on the
surface of the
material.
Preferably the material of the second aspect comprises at least 5 wt% carbon
dioxide,
preferably at least 10 wt%, more preferably at least 15 wt%, for example at
least 20 wt%.
The material of the second aspect may comprise up to 50 wt% carbon dioxide,
for example up ,
to 40 wt%.
The material of the present invention is preferably stable at temperatures of
up to 50 C and
thus can be easily transported large distances, for example in container
ships.
The material of the second aspect may find utility in subsequent applications,
for example it
could be used as a fertiliser, as a strengthening aid in plastics or as a
filler in building
materials.
In some embodiments the material may be prepared at or delivered to a location
suitable for
long term storage, to avoid releasing the carbon dioxide into the atmosphere.
Suitable long
term storage locations preferably are not subjected to extremes of heat or
pressure.
However in preferred embodiments the material will be used directly in another
application or
will be coverted into or incorporated in a useful product.
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There may be instances in which it is desired to release carbon dioxide from
the surface of the
material, for example after a period of storage or following transport to a
particular location.
Release of carbon dioxide may be achieved by application of an external
stimulus, for example
by heating the material, contacting the material with a chemical reagent or
application of a
mechanical force.
Thus the present invention may enable waste carbon dioxide from a first
location to be
captured, stored and transported to a second location where it can be released
and used as
appropriate.
The inventors have found that when using cellulosic material that has been
contacted with a
source of metal ions as well as an amino compound the carbon dioxide is more
strongly
retained on the surface than when only an amino compound is used, for example
the treated
material has been found to be more stable to an increase in temperature.
In embodiments in which long term storage of the carbon dioxide is desired a
higher ratio of
metal ions to amino compound is preferably used (i.e. an excess of metal
ions).
If it is intended that the carbon dioxide is to be released from the material
following
transportation it is preferable to use a lower ratio of metal ions to amino
compound (i.e. an
excess of amino compound).
The material of the second aspect is a solid material based on organic matter
and which
comprises up to 50 wt%, typically 10 to 35 wt% carbon dioxide. This material
is a solid and is
stable under most normal atmospheric conditions. It can therefore be
transported by any
suitable means, in standard containers. It can be shipped and transported by
road or rail in
standard bulk containers which do not need to be adapted or handled in any
particular way. No
special precautions are necessary. Thus the material can be transported
cheaply and easily
from one location to another with no restrictions. This offers significant
advantages over the
prior art.
The invention will now be further defined with reference to the following non-
limiting examples.
Example
1 kg of wheat based bioethenol waste was mixed with 500m1 of a composition
comprising
monoethanolamine and 20 wt% water in a tumble mixer for 10 minutes at standard
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temperature and pressure. This mixture was then passed into a screw mixer
through which
pure CO2 at a pressure of 5 bar was passed. The material was contacted with
the the CO2 in
the screw mixer for 5 mins at stp. After 5 mins 200m1 of 50 wt% aqueous NaOH
was added to
the screw mixer with CO2 being continuously fed into the system for an
additional 5 minutes.
After the 5 minutes has elapsed the screw mixer was emptied via a cooled (<50
C) pelletising
dye. This material obtained is sufficiently stable for onward transportation.
