FIELD OF INVENTION
[0001]. The present invention relates to a method for production of carbon foam
from coal tar pitch, or more particularly formation of carbon foam where acetone
soaked polyurethane (PU) foam is dipped in the pitch slurry for better
impregnation.
BACKGROUND OF INVENTION:
[0002]. Carbon foams are materials of very high carbon content that have
appreciable void volume. Typically, swelling coals are heated at rates such that
the coal swells and produces a coke or a carbon foam. Cokes and carbon foams
have a high degree of porosity and are typically of low density. Carbon foams have
potential utility in a variety of applications because of their unique properties
such as temperature resistance, strength, and low density. For example, carbon
foams are typically fire resistant and may exhibit significant strength, even at
extreme temperatures, which makes these materials suitable for use as light
weight thermal barriers, wall panels, and as baffles for high intensity flames.
[0003]. Carbon foams have been produced from various materials including, but
not limited to, pitches, mesophase carbon materials, foamed synthetic plastics,
coals, and hydrogenated coal products. Coal is a relatively inexpensive and
relatively non-toxic starting material to produce carbon products. Such products
have included metallurgical cokes, activated carbons, and carbon foams.
Specifically, swelling bituminous coals are typically used in the production of
metallurgical cokes since these coals typically “swell” upon heating to produce a
porous carbon mass. This porous carbon mass is referred to as a coke. As
described above, the void volume within coke is not arranged in cells having the
regular size, shape, distribution, and orientation of the cells within carbon foam.
As a result, coke does not have the combination of beneficial properties exhibited
by carbon foams. Therefore, coke has limited, if any, utility in the applications to
which carbon foams may be directed (United States Patent 7,767,183 B2).
[0004]. The number of processes have been used to control the swelling behaviour
of the coal. For example, carbon foams have been produced from swelling

bituminous coals using processes where the coal is foamed under high process
atmospheric pressures. In other processes, the coal is oxidized or devolatilized
prior to foaming. In still other process, the coal is foamed in a high-strength mold
which, apparently, mechanically limits the maximum carbon foam volume. Many
processes have been developed to produce carbon foam. Such processes often
involve a template foaming, use of blowing agents and high-pressure conditions
to produce carbon foam (for example US patent no. 7,544,222 B2). Carbon foam
is also prepared from coal tar derived pitch and petroleum pitch.
PRIOR ARTS:
[0005]. United states patent no. US 6,833,012 provides a method to produce
petroleum or coal tar pitch-based cellular or porous products produced by the
controlled heating of mesophase carbon materials derived from coal tar or
petroleum pitch having a softening point in excess of about 300° and preferably
between about 300 and about 400°C. in a “mold” and under a non-oxidizing
atmosphere.
[0006]. United states patent no. US 6,033,506 describes a method in which the
process employs mesophase or isotropic pitch and a simplified process using a
single mold. The process does not need conventional oxidative stabilization
process.
[0007]. United states patent no. US 6,399,149 employs mesophase or isotropic
pitch and a Simplified process using a single mold. The foam is encased and filled
with a phase change material to provide a very efficient heat sink device.
[0008]. Stankiewicz (U.S. Pat. No. 6,103,149) prepares carbon foams with a
controlled aspect ratio of 0.6-1.2. The patentee points out that users often require
a completely isotropic foam for superior properties with an aspect ratio of 1.0
being ideal. An open-celled carbon foam is produced by impregnation of a
polyurethane foam with a carbonizing resin followed by thermal curing and
carbonization.

[0009]. US patent no. 5,789,338 prepares the foams, derived from the pyrolysis of
resorcinol-formaldehyde and related polymers, are high density (0.1 g/cc-1.0
g/cc) electrically conductive and have high surface areas (400 m/g-1000 m/g).
[00010]. Carbon foam is produced by template foaming. Polyurethane (PU) foam
is used as template material. The precursor such as phenolic resin, resorcinol-
formaldehyde, coal etc. are used as impregnating material. The precursor and
polymer is added in water to prepare the slurry and then PU foam is dipped in
the slurry to impregnate the same. The problem of the said method is less
impregnation of precursor in the PU foam because of less driving force as coal tar
pitch particles are hydrophobic in nature.
[00011]. To solve this problem, principle of like attract like is used. So, when a
pitch particle is dispersed in water and a drop of organic solvent is introduced on
top of it, pitch particle will readily come into the organic phase and will get
dissolved. The PU foam is first dipped in organic solvent so that it can attract
more amount of organic material. In this case, more amount of precursor and
polymer to go into PU foam, which provides better impregnation.
OBJECTS OF THE INVENTION
[00012]. It is therefore the principal object of the present invention to provide a
method of low bulk density carbon foam from coal tar pitch.
[00013]. Another object of the present invention is provide a method, where the
impregnating capacity of the PU foam has enhanced with the use of an organic
solvent.
[00014]. Yet another object of the present invention is provide a method, where
the carbonized foam has density as low as 0.18 g/cc and compressive strength
as high as 1.08 MPa.
[00015]. Further object of the present invention is provide a method, where the
polyurethane foam is taken as template.

[00016]. Yet another object of the present invention is provide a method, which
provides higher impregnation capacity of the foam where the core of the matrix is
fully covered with pitch particles.
[00017]. Another object of the present invention is provide a method, which is
simple yet rapid and environment friendly.
[00018]. These and other objects and advantages of the present invention will be
apparent to those skilled in the art after a consideration of the following detailed
description taken in conjunction with the accompanying drawings in which a
preferred form of the present invention is illustrated.
SUMMARY OF INVENTION
[00019]. One or more drawbacks of conventional systems and process for a
method producing a carbon foam by using coal tar pitch are overcome, and
additional advantages are provided through the method as claimed in the present
disclosure, Additional features and advantages are realized through the
technicalities of the present disclosure. Other embodiments and aspects of the
disclosure are described in detail herein and are considered to be part of the
claimed disclosure.
[00020]. A method of producing a carbon foam by using coal tar pitch comprises
soaking of polyurethane (PU) foam in an organic solvent; preparing a solution by
adding polyviny1 alcohol in water; addition of the carbon precursor such as coal
tar pitch to the solution to prepare a slurry; impregnation of soaked PU foam into
the slurry for suitable duration and dried; oxidizing the dried impregnation foam
in presence of air; taking the impregnated PU foam in a boat and placing in a
tube furnace followed by heating at 275°C- 325°C for a suitable duration of time
to obtain a green foam; heating the green foam in a two-step carbonization at two
different temperature; carbon foam is obtained which is subjected to various test
for evaluation of the compressive strength and bulk density of it; wherein the PU
foam is being soaked in the organic solvent to attract more amount of organic
solvent, the pitch particles readily absorbed to the foam matrix due to high affinity
in the organic solvent and the resultant foam provides better impregnation.

[00021]. Various objects, features, aspects, and advantages of the inventive
subject matter will more apparent from the following detailed of preferred
embodiments, alongwith the accompanying drawing figures in which like
numerals represent like components.
[00022]. It is to be understood that the aspects and embodiments of the disclosure
described c above may be used in any combination with each other. Several of
the aspects and may be combined to form a further embodiment of the
disclosure.
[00023]. The foregoing summary is illustrative only and is not intended to be in
any way limiting. In addition to the illustrative aspects, embodiments, and
features described above, further aspects, embodiments, and will become
apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[00024].The illustrated embodiments of the subject matter VGII be best understood
by reference to the drawings, wherein like parts are designated by like numerals
throughout. The following description is intended only by way of example, and
simply illustrates certain selected embodiments of devices, systems, and that are
consistent with the subject matter as claimed herein, wherein:
[00025].Figure 1 illustrates a process flow diagram for production of carbon foam
by template method
[00026]. Figure 2 illustrates Foam strip soaked in acetone
[00027]. Figure 3 illustrates Foam strip without acetone soaking
[00028]. Figure 4 illustrates Foam produced from 25% pitch and 1% PVA
concentration
[00029]. Figure 5 illustrates Foam produced from 25% pitch and 3% PVA
concentration
[00030].The figures depict embodiments of the disclosure for purposes of only. One
skilled in the art will readily from the following description that alternative

embodiments of the structures and methods illustrated herein may be
employed without departing from the principles of the disclosure described
herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[00031].While the embodiments of the disclosure are subject to various
modifications and alternative forms, specific embodiment thereof have been
shown by way of the figures and will be described below. It should be understood,
however, that it is not intended to limit the disclosure to the particular forms
disclosed, but on the contrary, the disclosure is to cover all modifications,
equivalents, and alternative falling within the scope of the disclosure.
[00032]. It is to be noted that a person skilled in the art would be motivated from
the present disclosure to arrive at a method of producing a carbon foam by using
coal tar pitch thereof. Such a method of producing a carbon foam by using coal
tar pitch may vary based on configuration of one or more workpieces. However,
such modifications should be construed within the scope of the disclosure.
Accordingly, the drawings illustrate only those specific details that are pertinent
to understand the embodiments of the present disclosure, so as not to obscure
the disclosure with details that will be clear to those of ordinary skill in the art
having benefit of the description herein.
[00033]. As used in the description herein and throughout the claims that follow,
the meaning of “a”, “an”, and “the” includes plural reference unless the context
clearly dictates otherwise. Also, as used in the description herein, the meaning of
“in” includes “in” and “on” unless the context clearly dictates otherwise.
[00034]. The terms “comprises”, “comprising”, or any other variations thereof
used in the disclosure, are intended to cover a non-exclusive inclusion, such that
a system, coal tar pitch, method, carbon foam, assembly that comprises a list of
components does not include only those components but may include other
components not expressly listed or inherent to such method. In other words, one
or more elements in a system or device proceeded by “comprises…..a” does not,

without more constraints, preclude the existence of other elements or additional
elements in the system, apparatus or device.
[00035]. The present subject matter relates to a method of producing the carbon
foam from coal tar pitch, where the absorption capacity of the foam has enhanced
significantly whereas the swelling behavior can be controlled. The carbon foam
can be used in light weight thermal barrier and wall panels.
[00036].The method of producing carbon foam comprised of mainly four steps:
[00037]. i) Dipping/Soaking (101)
[00038].ii) Impregnation (102)
[00039].iii) Oxidization (103)
[00040].iv) Carbonization (104)
[00041]. i) Dipping/Soaking (101): At first, the PU foam is dipped in an organic
solvent such as acetone, for a substantial amount of time.
[00042]. ii) Impregnation (102): In this step, a solution is prepared by taking
water in desired quantity in a vessel in which required quantity of polymer is
added. The mixture is stirred at 500 rpm using magnetic stirrer until the polymer
completely gets dissolved. Polymer and water solution is heated and is
continuously stirred for water insoluble polymer at room temperature. Then the
polymer solution is cooled to room temperature before addition of the precursor
and required amount of the precursor is added to the solution and is stirred using
magnetic stirrer with high rotation speed. After that the PU foam is impregnate
into the slurry and dried.
[00043]. iii) Oxidization (103): The impregnated PU foam is taken in tube furnace
and heated in desire temperature with flow of nitrogen to a dried temperature and
air is introduced for the oxidation.
[00044]. iv) Carbonization (104): At first, the sample is heated from room
temperature to 600 ˚C under nitrogen flow. Then it is kept at that temperature for
1 hour. After that, temperature is raised from 600°C to 1000°C under nitrogen

flow. It is kept at 1000˚C for 1 hour and then it is cooled down to room
temperature. The produced carbon foam is tested for compressive strength and
bulk density.
[00045]. In the present method, coal tar pitch (CTP) is used as precursor, which
has particle size of 0 to 500 micron, polyurethane (PU) foam as template and
polyviny1 alcohol is used as polymer.
[00046]. At first a PU foam is dipped in an organic solvent or more preferably in
acetone, so that it can soak the acetone substantially. The soaking time is 10
minutes
[00047]. A solution is prepared with the help of polymer or polyvinyl alcohol and
coal tar pitch in water
METHOD OF SOLUTION PREPARATION:
[00048]. i) Polyvinyl alcohol is added in water in 1% to 20% wt. % or more
preferably in 1% to 5% stirring alongwith constant stirring at 500rpm and heating
between 80°C to 100°C;
[00049]. ii) cooling of the solution to room temperature at 25°C to 30°C.
[00050]. The carbon precursor or coal tar pitch having particle size 0 to 500
micron is added into the slurry solution in 10% to 40% wt.% or more particularly
in 15 to 25 wt.% with constant stirring at 1000rpm for 5 to 20 min or more
preferably 10 minutes.
[00051]. The acetone soaked PU foam is then impregnated in a vessel with the
slurry for 2 to 25 minutes and then the PU foam is taken out and dried at 110°c
for 1 hour.
[00052]. This cycle of impregnation of the PU foam is repeated for 4 to 15 times
for increasing the amount of pitch absorbed in the matrix.
[00053]. Fig 1 provides a flow diagrams of the whole impregnation process of PU
foam.

[00054]. The impregnated PU foam is oxidized in presence of air so that PU foam
burnt off and precursor takes it shape. Impregnated PU foam is then placed in
an alumina boat and is put in a tube furnace (103). Sample is heated to 275˚C to
325°C in a slow heating rate of 0.5 to 5˚C/min, more preferably 1 to 2.5˚C/min
under nitrogen atmosphere. After reaching the desired temperature, nitrogen flow
is closed and air is introduced. This is carried out for 1-7 hours, more preferably
3-5 hours and temperature is kept constant at 300˚C.
[00055]. A green foam is produced after this oxidation process, which is placed in
the carbonization furnace (104) where two step carbonization takes paces.
[00056]. METHOD OF CARBONIZATION
i) heating of sample from room temperature to 600°C with flow of nitrogen
at a rate of 1°C to 5°C/min or more particularly 3°C/min and keeping the
temperature of 600°C for 1 hours;
ii) raising of temperature from 600°c to 1000°c at a rate of 3°C/min under
nitrogen flow of 2 LPM and the temperature of 100°C is kept for 1 hour.
iii) cooling of the sample to room temperature.
[00057].The resultant carbon foam is tested for different tests for evaluation of
compressive strength and bulk density.
[00058].In accordance with the present invention PU foam strip is taken as
template for producing of carbon foam carbon foam density depends on starting
PU foam density. Higher density PU foam will produce higher density carbon
foam. As per requirement of carbon foam, PU foam density is selected.
[00059]. Experiments:
EXAMPLE 1
[00060].Coal tar pitch particles are hydrophobic in nature. So, when a pitch
particle is dispersed in water and a drop of acetone or any organic solvent is
introduced on top of it, pitch particle will readily come into the organic phase and
will get dissolved.

[00061]. A slurry of PVA (3% w/w) & modified pitch (<75 micron size) is prepared
using water. Two PU foam strip of same dimension is taken. One of them is soaked
with acetone and another one is kept as it is. Both the strips are subjected to
same impregnation condition of 10 minutes. Then the foam is dried at 110˚C for
3.5 hours. Proximate and ultimate analysis of modified coal tar pitch is shown in
Table 1. Table 2 shows the impregnation result of PU foam strip with and without
acetone.

Proximate analysis, % Ultimate analysis, %
Ash VM IM FC C H N S O
00.89 21.74 0.38 77.87 89.66 3.42 2.21 0.32 4.39

Table 2: Impregnation result with and without acetone
Foam
strip Dimension
(cm*cm*cm) Volume
(cc) Initial
weight
of PU
foam
(gm) Weight
after
absorption
(gm) Pitch
absorbed
(gm) Volumetric
pitch
absorption
(gm/cc of
foam)
With
acetone 4.7*3.6*1.5 25.38 0.2792 7.5112 7.232 0.285
Without
acetone 4.6*3.5*1.6 25.76 0.2565 2.1465 1.890 0.073
[00062]. From the values of both tables such as table 1 and table 2, it can be
successfully concluded that the acetone soaked foam provides substantially
better impregnation compare to normal foam without organic solvent treated
foam strip. The pitch particles, which are dispersed in water slurry can penetrates
the foam matrix due to the affinity of the particles in organic solvent.

[00063]. Impregnation in normal foam strip is dominated only by diffusion of the
particles through the foam matrix. Hence, more members of particles are
deposited inside the matrix. Figure 2 and Figure 3 represents the core of the
matrix of both foam strips after impregnation. The foam strip without acetone
soaking shows that not much pitch is deposited in the core. For the acetone
soaked foam, core of the matrix is almost fully covered with pitch particles.
EXAMPLE 2
[00064]. In this case, polymer concentration is varied from 1 to 5% in slurry
making to see the effect of polymer concentration on foam with and without
acetone dipping. Carbonization of acetone soaked PU foam is carried out to
compare it with PU foam without soaking in acetone. Polymer (PVA) concentration
is varied from 1 to 5%. All other conditions were kept constant. Results are shown
in Table 3.
[00065]. A slurry of PVA (1-5% w/w) & modified pitch (< 75 micron) is prepared
using water as per above mentioned procedure. PVA is added in 1% to 5% (w/w)
concentration in water and heated to 90°C. Now, 25% of coal tar pitch (for 1%
PVA, 74 mL water and 25g pitch) is added in the solution and stirred for 10
minutes at 1000 rpm. Two PU foam strip of same dimension is taken. One of them
is soaked with acetone and another one is kept as it is. Both the strips are
subjected to same impregnation condition of 10 minutes separately. Then the
foam is dried at 110˚C for 3.5 hours. This is repeated at least for four times.
[00066]. Both types of PU foam (with and without acetone dipped) are
impregnated separately and then oxidized and carbonized to get the carbon foam.
The impregnated PU foam is oxidized in presence of air so that PU foam burnt off
and precursor takes it shape. Impregnated PU foam is then placed in an alumina
boat and is put in a tube furnace. Sample is heated to 300˚C in a slow heating
rate of 3˚C/min under nitrogen atmosphere and kept for 2 hours. Green foam
obtained after oxidation is placed inside a carbonization furnace. First, the
sample is heated from room temperature to 600˚C under nitrogen flow at a rate
of 3˚C/min and kept at that temperature for 1 hour. After that, temperature is

raised from 600˚C to 1000˚C at a rate of 5˚C/min under nitrogen flow of 2 LPM.
It is kept at 1000˚C for 1 hour and then it is cooled down to room temperature.
The produced carbon foam is tested for compressive strength and bulk density.
Results are presented in Table 3.
[00067]. It clearly shows that under the same conditions acetone soaked PU foam
give better impregnation scenario. Weight loss after carbonization is remaining
constant in the range of 28-33% with average weight loss of 31.91%.
[00068]. Acetone soaked PU foam absorbs more amount of pitch for all the three
concentrations. The acetone dipped PU foam absorbs 10-30% more pitch
compare to without acetone dipped PU foam. The bulk density increases for
acetone dipped PU foam in all the three cases. The maximum increase in bulk
density was for 3% PVA concentration (from 0.192 g/cc to 0.291 g/cc) and same
is for compressive strength. This is obvious that as bulk density increases,
compressive strength also increases.
[00069]. FIG 4 shows the SEM image of acetone soaked PU foams with 3% PVA
is shown in Figure 4. NAPVA-25-3 has pores in the size range of 400-500 micron
and thick ligaments of 250 micron. Windows are range of 1-4 micron and some
large pores of 8-10 micron. Increase in the ligament thickness is due to the higher
concentration of polymer as it holds more number of particles in the cell wall.
[00070]. Table 3 provides the difference values of the foam of the acetone soaking
at different PVA concentration.

Table 3
Sample Pitch Volumetric % Weight loss Bulk Compressive
absorbed pitch after density strength
(gm) absorption
(gm/cc of
foam) carbonization (g/cc) (MPa)
NAPVA-25-1 11.457 0.208 28.415 0.262 0.23

NAPVA-25-1 A 12.616 0.216 31.734 0.322 1.08
NAPVA-25-3 8.720 0.173 32.996 0.192 0.10
NAPVA-25-3 A 12.139 0.228 30.796 0.291 0.82
NAPVA-25-5 10.200 0.191 33.657 0.182 0.10
NAPVA-25-5 A 12.856 0.241 33.867 0.203 0.12
[00071]. Each of the appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the various
elements or limitations specified in the claims. Depending on the context, all
references below to the “invention” may in some cases refer to certain specific
embodiments only. In other cases, it will be recognized that references to the
“invention” will refer to subject matter recited in one or more, but not necessarily
all, of the claims.
[00072].Groupings of alternative elements or embodiments of the invention
disclosed herein are not to be construed as limitations. Each group member can
be referred to and claimed individually or in any combination with other members
of the group or other elements found herein. One or more members of a group
can be included in, or deleted from, a group for reasons of convenience and/or
patentability. When any such inclusion or deletion occurs, the specification is
herein deemed to contain the group as modified thus fulfilling the written
description of all groups used in the appended claims.
[00073].The present disclosure provides a method for producing a carbon foam
by using coal tar pitch.
Equivalents:
[00074]. With respect to the use of substantially any plural and/or singular terms
herein, those having skill in the art can translate from the plural to the singular
and/or from the singular to the plural as is appropriate to the context and/or

application. The various singular/plural permutations may be expressly set forth
herein for sake of clarity.
[00075]. It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended
claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to”, the term “having” should be
interpreted as “having at least”, the term “includes” should be interpreted as
“includes but is not limited to”, etc.). It will be further understood by those within
the art that if a specific number of an introduced claim recitation is intended,
such an intent will be explicitly recited in the claim, and in the absence of such
recitation no such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases “at
least one” and “one or more” to introduce claim recitations. However, the use of
such phrases should not be construed to imply that the introduction of a claim
recitation by the indefinite articles “a” or “an” limits any particular claim
containing such introduced claim recitation to inventions containing only one
such recitation, even when the same claim includes the introductory phrases “one
or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a”
and/or “an” should typically be interpreted to mean “at least one” or “one or
more”); the same holds true for the use of definite articles used to introduce claim
recitations. In addition, eve it a specific number of an introduced claim recitation
is explicitly recited, those skilled in the art will recognize that such recitation
should typically be interpreted to mean at least the recited number (e.g., the bare
recitation of “two recitations”, without other modifiers, typically means at least
two recitations, or two or more recitations).
[00076].The above description does not provide specific details of manufacture or
design of the various components. Those of skill in the art are familiar with such
details, and unless departures from those techniques are set out, techniques,
known, related art or later developed designs and materials should be employed.

Those in the art are capable of choosing suitable manufacturing and design
details.
[00077].The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the present disclosure. It
will be appreciated that several of the above-disclosed and other features and
functions, or alternatives thereof, may be combined into other systems or
applications. Various presently unforeseen or unanticipated alternatives,
modifications, variations, or improvements therein may subsequently be made by
those skilled in the art without departing from the scope of the present disclosure
as encompassed by the following claims.
[00078].The claims, as originally presented and as they may be amended,
encompass variations, alternatives, modifications, improvements, equivalents,
and substantial equivalents of the embodiments and teachings disclosed herein,
including those that are presently unforeseen or unappreciated, and that, for
example, may arise from applicants/patentees and others.
[00079].While various aspects and embodiments have been disclosed herein,
other aspects and embodiments will be apparent to those skilled in the art. The
various aspects and embodiments disclosed herein are for purposes of illustration
and are not intended to be limiting, with the true scope and spirit being indicated
by the following claims.

WE CLAIM:

1. A method of producing a carbon foam by using coal tar pitch comprises
soaking of polyurethane (PU) foam in an organic solvent;
preparing a solution by adding polyvinyl alcohol in water;
addition of the carbon precursor such as coal tar pitch to the solution to
prepare a slurry;
impregnation of soaked PU foam into the slurry for suitable duration and
dried;
oxidizing the dried impregnation foam in presence of air;
taking the impregnated PU foam in a boat and placing in a tube furnace
followed by heating at 275°C- 325°C for a suitable duration of time to obtain a
green foam;
heating the green foam in a two-step carbonization at two different
temperature;
carbon foam is obtained which is subjected to various test for evaluation
of the compressive strength and bulk density of it;
wherein the PU foam is being soaked in the organic solvent to attract more
amount of organic solvent, the pitch particles readily absorbed to the foam
matrix due to high affinity in the organic solvent and the resultant foam provides
better impregnation.
2. The method as claimed in claim 1, wherein the organic solvent is acetone.
3. The method as claimed in claim 1, wherein the PU foam is being soaked in the
organic solvent for 10 minutes.
4. The method as claimed in claim 1, wherein the solution is prepared by mixing
of polyvinyl alcohol into water in 1% to 20% or more particularly in 1% to 5% wt.
percentage.

5. The method as claimed in claim 1, wherein the solution is prepared with
constant stirring at 500rpm along with heating between 80°C to 100°C.
6. The method as claimed in claim 1, wherein the coal tar pitch has particle size
less than 500 micron .
7. The method as claimed in claim 1, wherein the coal tar pitch is added to the
solution in 10% to 40% wt. % or more particularly 15 to 25 wt.% with a stirring
rate of 1000rpm for 5 to 20 min or more preferably for 10 min;
8. The method as claimed in claim 1, wherein the PU foam impregnation in the
slurry for 2 to 25 minutes more preferably by 7 to 12 mins.
9. The method as claimed in claim 1, wherein the impregnated PU foam is dried
at temperature of 110°C for 1 hour
10. The method as claimed in claim 1, wherein the impregnated PU foam is
oxidized at a temperature of 300°C with a heating rate of 0.5° to 5°C /min or
more preferably 1° to 2.5°C /min in nitrogen atmosphere.
11. The method as claimed in claim 1, wherein the green foam is first heated at
a temperature of 600°C under nitrogen flow at a rate of 1 to 5°C /min or more
preferably 3°C/min for a duration of 1 hour.
12. The method as claimed in claim 1, wherein the green foam is further heated
from 600°C to 1000°C at a rate of 5°C/min with nitrogen flow of 2 LPM for 1
hour.