FIELD OF THE INVENTION
This invention relates to a process for preparing carbon nano materials from a novel catalyst
derived from waste iron/steel chips and fly ash obtained from coal combustion.
This process for preparing carbon nano materials from a novel catalyst derived from waste
iron/steel chips and fly ash obtained from coal combustion involves a chemical vapour
deposition process in which coal tar and spent wash oil obtained from coke by-product plant
is used as precursor for synthesis of carbon nano materials. The invention further relates to
the carbon nano materials including carbon nanotubes obtained from the process that utilizes
the novel catalyst derived from waste steel chips and fly ash.
BACKGROUND OF THE INVENTION AND RELATED ART
Carbon is a chemical element with symbol C and atomic number 6. It is a nonmetallic and
tetravalent- making four electrons available to form covalent chemical bonds. It belongs to
group 14 of periodic table. Carbon is the 15th most abundant element in the Earth's crust, and
the fourth most abundant element in the universe by mass after hydrogen, helium,
and oxygen. The atoms of carbon can bond together in different ways, termed allotropes of
carbon. The best known are graphite, diamond, and amorphous carbon. The physical
properties of carbon vary widely with the allotropic form. For example, graphite
is opaque and black while diamond is highly transparent. Graphite is a good electrical
conductor while diamond has a low electrical conductivity. Under normal conditions,
diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all
known materials. All carbon allotropes are solids under normal conditions, with graphite
being the most thermodynamically stable form. They are chemically resistant and require
high temperature to react even with oxygen. Fullerens generally have a structure formed from
as two-dimensional graphene sheet which, when rolled end-to-end, exists in the form of a
tube or other three dimensional structure. Carbon nanotube is described as single wall or
multi-walled structures. Single-walled nanotubes are generally tightly wrapped layers of
graphene forming tubes with a diameter of as little as one nanometer with an essentially
unlimited length. Carbon nanotubes have physical and chemical properties that are of great
interest in many fields of technology. Physical properties such as strength and stiffness are of
special interest in applications such as composites.

Steel plant converts coal into coke in coke oven batteries. The volatile matter of coal comes
out in the form of coke oven gas. This gas contains impurities which need to be cleaned
before using it as a fuel. The one such impurity in the gas is called coal tar. Wash oil is used
for removing the naphthalene from the coke oven gas. The wash oil is discarded after using it
repeatedly. This is called spent wash oil. At present coal tar and wash oil is not used and it is
sold in the market at very low price. These raw materials could be converted to carbon nano
materials.
Fly ash is one of the residues generated in combustion, and is formed from the fine particles
that rise with the flue gases. Fly ash is generally captured by electrostatic precipitators or
other particle separation equipment before the flue gases reach the chimneys of coal-fired
power plants. The major constitute of fly ash includes substantial amounts of silicon dioxide
(SiO2) and calcium oxide (CaO). Fly ash is typically seen as an environmental hazard and is
considered a waste product with little to no reclamation potential. Most of this fly ash is
treated as waste, and is disposed of at landfills. Due to the environmental hazards of
producing fly ash and disposal of fly ash as a common by-product of many industrial
processes, it would be desirable to provide a method for recycling the fly ash into useful
components, such as catalyst and its support. Due to the higher stability of its major
component, aluminosilicates, fly ash could be employed as catalyst support by impregnation
of other active components for variousreactions. Thus, a method of forming a novel catalyst
from fly ash solving the aforementioned problems is desired.
Application of fly ash as a catalyst for synthesis of carbon nanotube ribbons has been
described (see - Nath et al., Journal of Hazardous Materials, 192, 2011, 691-97). The use of
fly ash impregnated with ferric nitrate was not described. Irradiation effects on the leaching
behaviour and form of heavy metals in fly ash of municipal solid waste incinerator was
described by Nam et al. (Journal of Hazardous Materials, Volumes 199-200, 15 Jan 2012,
440-447). The method of forming carbon nanotubes from carbon-rich fly ash was described
in a patent (US 8609189 B2, 28th Sep 2011). They have selectively taken the carbon-rich fly
ash to use in the chemical vapour deposition (CVD) process. But fly ash impregnated with
iron was not described. In another invention multi walled carbon nanotubes was formed using
electron beam treated crude oil fly ash (US patent no. US 8865108 B2, Oct 21, 2014). They
used fly ash obtained from crude oil but use of waste steel chips to get ferric nitrate was not
described. Many waste products such as camphor oil, biodiesel waste glycerol, bitumen

waste, and waste engine oil etc were used for synthesis of carbon nanotubes. Use of coal tar
and wash oil (steel plant waste) along with fly ash derived catalyst was not described in the
literature available.
OBJECTS OF THE INVENTION
It is an object of the invention to provide a process for preparing carbon nano materials from
a novel catalyst derived from waste iron/steel chips and fly ash obtained from coal
combustion.
It is a further object of this invention to provide a method for preparing carbon nano materials
by chemical vapour deposition.
It is another object of this invention to provide a process for preparing carbon nano materials
from a novel catalyst by impregnating fly ash with ferric nitrate derived from steel chips and
nitric acid.
A further object of this invention is to provide a process for preparing carbon nano materials
by contacting coal tar or spent wash oil with fly ash derived catalyst.
A still further object of this invention is to provide a process for preparing carbon nano
materials which is simple and cost effective.
These and other objects and advantages of the invention will be apparent to a person skilled
in the art on reading the ensuing description in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
Coal tar and wash oil obtained from the coke oven plant are used as precursor to produce
carbon nano particles (called "CNPs") and carbon nanotubes (called "CNTs"). Steel chips are
treated with Nitric acid to get ferric nitrate. Fly ash obtained from coal fired power plant is
converted into catalyst by reacting with ferric nitrate (termed as "fly ash derived catalyst").
The spent wash oil is mixed with fly ash derived catalyst and put into glass bottle burner
having cotton wick to burn the oil. The oil is decomposed by thermal decomposition and
particles are deposited on the steel substrate and analysed by SEM, FTIR and Raman
spectroscopy. Next, chemical vapour deposition (CVD) is done by using tube furnace. The
fly ash derived catalyst is mixed with spent wash oil or coal tar and injected in to the tube
furnace and maintaining the temperature between 750-900°C in the presence of inert gas.
Once the process is completed, the tube is cooled down to room temperature and deposited
material is scratched and weighed and sent for analysis and characterization. The produced

CNPs are mixed with epoxy-hardener to make the composite and its strength is checked with
different percentage of CNPs.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: FESEM Image of thermal decomposition of wash oil and fly ash catalyst
Figure 2: EDS analysis of carbon nanomaterials obtained using fly-ash derived catalyst
Figure 3: RAMAN spectra of carbonaceous material from thermal decomposition
Figure 4: FESEM image of sample obtained after CVD of wash oil and fly ash derived
catalyst at 750°C
Figure 5: FESEM image of scratch obtained on the wall at 750°C
Figure 6: FESEM image of grown material on surface at 900°C
Figure 7: FESEM image of nanotubes grown on surface of fly ash derived catalyst
Figure 8: Mould prepared from carbon nano particles and epoxy-hardner
Figure 9: Flextural strength versus CNP percentage
Figure 10: Tensile strength versus CNP percentage
Figure 11: Schematic diagram of tube furnace
DETAILED DESCRIPTION OF THE INVENTION
Thus according to this invention is provided a process for preparing carbon nano materials
from a novel catalyst derived from waste iron/steel chips and fly ash obtained from coal
combustion. The process for preparing carbon nanomaterials, comprises providing a fly ash
derived catalyst powder in the boat inside a tube furnace to grow carbon nanoparticles on the
surface of the catalyst and tube wall, injecting a precursor into the tube furnace, maintaining
a predetermined temperature of the tube furnace during the addition, on completion of
addition, allowing the furnace to cool and collecting the nanomaterial deposited on the
catalyst and tube wall.
In accordance with this invention is provided a process of producing carbon nano particles
(CNPs) and carbon nanotubes using coal tar or wash oil as precursor and fly ash derived
catalyst by chemical vapour deposition and thermal decomposition. In the present invention,
coal tar and wash oil are obtained from coke by-product plant. Fly ash is obtained from coal

fired power plant. Standard lab grade nitric acid is used for the reaction. The properties of
coal tar, spent wash oil and fly ash are mentioned in Tables 1-3. Coal tar is a viscous material
but having high carbon content (> 92%). Spent wash oil has more than 83% carbon content.
The fly ash contains mostly silica and alumina and small amount of ferric oxide.


During CVD, a substrate is prepared with a layer of metal catalyst particles, most commonly
used catalyst are nickel, cobalt, and iron based. Ferrocene is used as catalyst for synthesis of
carbon nanotubes. But the ferrocene is costly catalyst. So, fly ash based novel catalyst is
developed and described in the invention.
Assuming 100% iron content of steel chips, expected reaction:
2Fe + 6HNO3 -> 2Fe(NO3)3 + 3H2|
5 g 6/2x63/56 242/56x5
= 16.875g = 21.60 g
= 17 mL of 70% HNO3
= 67 mL of 30% HNO3
In a solution, 17 mL of 70 wt.% HNO3 is taken and to it 50 ml of DM water is added to make
it 30 wt.% nitric acid. Next, H2O2 is added to the solution in ratio 1:5 (i.e. for every 5 parts
nitric acid, 1-part H2O2 is added). Hence, for about 60 ml 30 wt.% nitric acid 12 ml H2O2 is
added. The solution is mixed well and to it steel chips are added slowly. The colour of the
solution turned from colourless to reddish-brown. Thus, it is converted to ferric nitrate. Then
the excess liquid is boiled off in a heater and solid residue is collected and weighed. For 5 g
steel chips, a residue of 16 g is collected. Therefore, to collect 10.85 g ferric nitrate residue to
impregnate fly ash, about 3.5 g of steel chips are required. Thus, ferric nitrate is produced.
Ferric nitrate [Fe(NO3)3] synthesized above is used to impregnate the surface of the fly ash
particles. Amount of catalyst prepared= 50 g.
Molecular weight of Fe(NO3)3 =242 g atom.
In 100 g of catalyst amount of iron loading = 5 g
242
Fe(NO3)3 required for 100 g of catalyst= — x 5 = 21.6071 g
56
In 50 g of catalyst amount of Fe(NO3)3 required = 21.6071/2 = 10.8035 g
Amount of fly ash required = 50-10.8035 = 39.1964 g
In two different beakers, 50 mL of ethanol is taken and the measured amount of Fe(NO3)3 is
added into it. The solution turned reddish-brown. It is sonicated for another 15 min to obtain
a clear reddish-brown solution of Fe(NO3)3. Fly ash is added into each beaker. This is stirred
in a magnetic stirrer for about four hour at 40°C. It makes a paste like substance. This paste is
collected in a plain dish and dried for about an hour at 70°C. The dried powder is transferred

into a ceramic boat. It is then calcined in a tube furnace at 800°C with 2 hours dwell time at
the final temperature. Fine reddish powder is obtained at the final stage, which is called fly
ash derived catalyst. The produced catalyst is used for synthesis of carbon nano particles and
carbon nanotubes.
There are three main methods of carbon nanotube synthesis, (i) arc discharge, (ii) laser
ablation and (iii) chemical vapor deposition (CVD). In the arc discharge method, arc
discharge is generated to provide high temperature for vaporizing carbon anodic electrode by
applying DC (direct current) between two graphite electrodes under sub-atmospheric
chamber. In laser ablation method, high temperature is generated by laser beam to gasify the
carbon target which is mostly a graphite pellet with certain amounts of Co and Ni acting as
catalysts. In the CVD method, inert atmosphere is maintained and CNTs are produced from
hydrocarbons, such as methane, which initially adsorb on catalytic particle surface followed
by decomposing into carbon atoms. Carbon atoms then diffuse into catalyst substrate, once
achieving supersaturated state, precipitated carbon atoms will serve as seed points for CNTs
nucleation and growth. The arc discharge and laser ablation are costly method. Hence, CVD
method is used widely for synthesis of carbon nano materials.
Example 1
In case of thermal oxidation, spent wash oil (50 mL) and 7 wt% fly ash derived catalyst is
mixed in ultrasonicator for half an hour followed by heating in magnetic stirrer up to 100°C.
Rigorously mixed catalyst and wash oil solution is poured into make shift burner made from
glass bottle for ignition and the flame is lit using match stick and the stainless steel substrate
is placed carefully to take carbonaceous vapours of thermal decomposition of spent wash oil
and fly ash-derived catalyst mixture. The obtained material is scratched, weighed and further
analyzed using various characterization techniques like Fourier Transform Infrared
Spectroscopy and Raman Spectroscopy. The figure 1 shows the SEM image of carbon nano
particles produced from spent wash oil and fly ash derived catalyst by thermal decomposition
method. The particle size ranges from 72 to 96 nano meter, which is appropriate range of
nano particles. Figure 2 shows EDS analysis. This shows the presence of Al, Si and Fe in the
synthesized carbon nano particles. Figure 3 shows the Raman spectra. The graphitic band
peak is higher than the disorder band, which means particles are more of graphitic nature.

Example 2
In another example, spent wash oil (24 mL) is taken into plastic syringe to inject the material
into tube furnace. The quantity of precursor which is spent wash oil is varied depending on
the requirement of the product. The fly ash derived catalyst (3 g) is taken into the alumina
boat and placed at the centre of the tube. The tube furnace is designed in such a way that
liquid material can be injected through syringe and inert gas (N2) is passed from inlet side.
The known amount of catalyst is kept in the alumina boat and placed in the tube. Inert gas
(N2) flow is maintained at 60 L/h and heating rate is maintained at 3°C/min. Once the
temperature reaches 750°C, the spent wash oil is injected at the rate of 6 mL/h. Cooling starts
once all the material is injected into the tube. The tube is taken out when the temperature
reaches room temperature. The carbon nano particles are grown on the catalyst as well as on
the tube wall. These materials are collected carefully, weighed and characterized by different
techniques. The chemical vapor deposition set up is shown in Figure 11. The yield of carbon
materials is shown in Table 4.

Figure 4 and 5 shows the nano particles synthesized by using spent wash oil and fly ash
derived catalyst at 750°C by chemical vapor deposition. The particle range is in 40-100 nm.
Example 3
In another example, coal tar is taken as precursor. Since coal tar is a viscous material and
difficult to inject, hence, spent wash oil is mixed in coal tar in 5:1 ratio (5 part is coal tar and
1 part is spent wash oil) and stirred heating is done to homogenize the sample. Same fly ash
derived catalyst (3 g) is taken in an alumina boat and placed in the tube. The tube is heated at
3°C/min and inert gas (N2) is purged to maintain the inert atmosphere. The temperature is
raised to 900°C. Coal tar and spent wash oil mixed sample is injected through the syringe at 6
mL/h rate. After completion of the experiments, the setup is cooled to room temperature. The

tube is taken out and synthesized nano particles are collected, weighed and characterized by
different techniques. The yield is shown in the table 4. The yield is higher in case of coal tar
in comparison to spent wash oil. The SEM images are presented in the figure 6 and 7. Carbon
nanotubes along with carbon nano particles are visible. Carbon nanotube diameter is in the
range of 40-80 nm.
In order to see the strength of carbon nano particles, the composite is prepared by mixing
CNPs and epoxy-hardener. First, a mould is prepared on a wooden plank as base. On it a
rectangle of 63><75mm is marked. Over it a transparent plastic sheet is attached and taped on
both sides. Wooden pieces of 9 mm thick are attached along the rectangle drawn using nails
and hammer. This gives us a mould for casting the composite. Four such moulds are prepared
and labeled properly.
For composite material, epoxy-hardener material based composite is chosen. Araldite AW106
along with hardener HV953IN is taken for the experiments. The composites are prepared
from carbon nanoparticles wherein said nanoparticles are mixed with epoxy hardener in 0.5-
2 wt% of the epoxy -hardener.
In a disposable plastic cup, these epoxy and hardener are mixed in a ratio of 10:1 and then
carbon nanoparticles are added in different weight percentage for reinforcement. The epoxy-
hardener along with CNPs are taken in a disposable plastic glass and mixed thoroughly so
that all the material is dispersed. The mixed material is then poured into separate moulds and
the top of the mould is covered with plastic sheet. A load is then placed on the top of each
composite and this is allowed to set for 24 hrs.


After 24 hours, the setup is de-moulded and rectangular blocks are removed. These blocks are
filed on all edges and are made in to a perfect cuboid of dimension 63x75><9 mm3. These are
cut into four pieces having each cut of dimension 15x75x9 mm3. Two of which is directly
sent to flexural strength testing and another two are further shaped in a dog bone shaped for
tensile strength test. The prepared samples are tested for tensile strength and flexural strength
in Universal Testing Machine. The average of two results is obtained and they are plotted in a
graph to compare the increasing strength with CNP reinforcement. The mould, flextural
strength and tensile strength are shown in Figure 8-10. The strength is increases with
increasing amount of CNPs. This shows that CNPs can be produced from spent wash oil and
coal tar using low cost fly ash derived catalyst by chemical vapor deposition.

WE CLAIM;
1. A process for preparing carbon nano materials, comprising
providing a fly ash derived catalyst powder in the boat inside a tube furnace to grow
carbon nanoparticles on the surface of the catalyst and tube wall,
injecting a precursor into the tube furnace, maintaining a predetermined temperature
of the tube furnace during the addition,
on completion of addition, allowing the furnace to cool and collecting the
nanomaterial deposited on the catalyst and tube wall.
2. The process as claimed in claim 1, wherein said catalyst is a fly ash based catalyst loaded
with ferric nitrate.
3. The process as claimed in claim 2, wherein said ferric nitrate is produced by reacting steel
chips and nitric acid.
4. The process as claimed in claim 1, wherein said precursor is selected from coal tar, spent
wash oil and mixtures thereof.
5. The process as claimed in claim 4, wherein coal tar and spent wash oil are obtained from coke
by product plant.
6. The process as claimed in claim 1, wherein fly ash is obtained from coal fired power plant.
7. The process as claimed in claim 1, wherein fly ash derived catalyst comprises 5% of iron by
weight.
8. The process as claimed in claim 1, wherein the injection is carried out in a chemical vapour
deposition apparatus.
9. The process as claimed in claim 1, wherein thermal decomposition is used for synthesis of
carbon nanoparticles.
10. The process as claimed in claim 1, wherein temperature is maintained between 750-900°C
during chemical vapour deposition process.

11. Nanoparticles and nanotubes produced by the process as claimed in the preceding claims,
wherein the nanoparticles have a size in the range of 40 - 100nm and naontubes have a
diameter in the range of 40 - 80nm.
12. Composites prepared from carbon nanoparticles as claimed in claim 11, wherein said
nanoparticles are mixed with epoxy hardener in 0.5-2 wt% of the epoxy -hardener.
13. The composites as claimed in claim 12, wherein said epoxy and hardener are present in a ratio
of 10:1 by weight.