Novel Separation Processes Multiphase Reactor CHEMCON – 05 ...

CHEMCON – 05, New Delhi
Session: Novel Separation Processes
Multiphase Reactor
Selective Extraction of Cardanol and Phenols from Cashew Nut
Shell Liquid Obtained Through Pyrolysis of Cashew Nut Shells
Rajesh N. Patel a , Santanu Bandyopadhyay b , Anuradda Ganesh c*
a Energy Systems Engineering, Indian Institute of Technology Bombay, Powai, Mumbai- 400 076
and Nirma Institute of Technology, Ahmedabad- 382 481, India, E mail: rnp@me.iitb.ac.in
b Energy Systems Engineering, Indian Institute of Technology Bombay, Powai, Mumbai- 400 076,
India, E mail: santanu@me.iitb.ac.in
c Energy Systems Engineering, Indian Institute of Technology Bombay, Powai, Mumbai- 400 076,
India, E mail:aganesh@me.iitb.ac.in
Keywords: Cashew nut shell liquid, Phenol, and Supercritical fluid extraction.
ABSTRACT
The feasibility of extraction of phenol rich oil from the cashewnut shell liquid obtained
through pyrolysis of cashew nut shells has been studied. The oil samples obtained at various
operating parameters have been analysed by Gas Chromatograph Mass Spectroscopy (GC-
MS) and Fourier Transform Infra-Red Spectroscopy (FTIR). The operating parameters were
optimised for maximum concentration of phenol and cardanol. The kinetics of the extraction
of CNSL using CO 2 as a supercritical fluid has been studied. Higher yield of oil (50% by
weight) along with higher concentration of phenols and cardanol by present method is found
encouraging.
INTRODUCTION
Bio-oil, obtained through vacuum pyrolysis, is typically dark brown in colour with a
distinctive pungent smell. This liquid contains several chemicals in different proportions. The
applications of bio-oil are well reported in the literature (Bridgewater and Peacocke, 1995).
One such application is the recovery of chemicals such as phenols, resin, agri-chemicals,
fertilizers and emission control agents. On an average pyrolysis liquid obtained through
various biomass contains about 10 to 20% water, 15-30% lignin fragments, 10-20%
aldehydes, 10-15% carboxylic acids, 5 to 10% carbohydrates, 2-5% phenols and traces of
furfurals, alcohols and ketones (Radlein, 1999). This in-situ natural phenol can be used for
resin preparations. However, the presence of carboxylic acid puts a limit on direct use of biooils
for such applications. Cashewnut shells and sugarcane bagasse, upon pyrolysis, give
phenol rich oil along with other chemical components (Das, 2004). The selective separation
of phenols and substituted phenols has been demonstrated using SCFE in subsequent
sections.
The most significant products from phenol are phenolic resins, which are used as a raw
material for laminate industries and manufacturing of special chemicals. The annual demand
of phenol is more than 120000 tonnes in Indian context and it increases at the rate of 8% p.a.
(www.dsir.nic.in/reports/techreps/tsr120.pdf). The raw materials for phenol manufacturing
are benzene and propylene. There is likely to be a shortage of both benzene and propylene in
local market. Moreover, the chemical process of manufacturing phenol ends up with large

amount of waste-water containing significant amount of phenols which is of environment
concern. Hence, there is a strong requirement for an alternative, which can reduce the
consumption of petro-based phenols and also be environment friendly. Within ten years
DuPont hopes to derive 25% of its chemicals from renewable sources, and the prestigious US
National Research Council predicts 50% of US fuels and over 90% of US organic chemicals
will come from renewable sources by the end of century
(www.bioalberta.com/ims/client/upload.doc). Natural phenols can be extracted from the
Cashew nut shell liquid along with char as the by-product.
India is the largest producer, processor and exporter of cashew in the world. In India cashew
cultivation covers a total area of about 0.77 million hectares of land, with annual production
over 0.5 million metric tonnes of raw cashew nuts. Cashew nut shell liquid (CNSL) is the byproduct
of the cashew industry. Conventionally, CNSL is extracted by various methods such
as open pan roasting; drum roasting, hot oil roasting, cold extrusion, etc. A new method of
extraction using vacuum pyrolysis has been suggested by Das et al. (2004). This study
explores the use of SCFE for selective extraction of cardanol and phenols, in particular from
the CNSL, making this oil an attractive commercial product. This study illustrates the new
methodology for CNSL extraction by supercritical fluid extraction (SCFE) route. The CNSL
extracted through this method contains higher concentration of cardanol and significant
concentration of phenols.
Supercritical carbon dioxide (SC-CO 2 ) extraction of phenols eliminates the use of hazardous
solvents. SC-CO 2 is extremely 'green' solvents since by reducing the pressure it is returned to
their former gaseous state and can be readily separated from the product and recycled. The
residue leftover after phenol extraction can be used as a fuel.
METHODS AND MATERIAL
Cashew nut shells (CNS) were sun dried for few days immediately after harvest to have low
moisture content between 8 to 10%. Then, they are shelled and kernels are removed. These
shells were used as a feed material in the pyrolysis reactor.
EXPERIMENTAL PROGRAMME
Pyrolysis
The pyrolysis of the cashew nut shells was carried out in the pyrolysis reactor. About 150
gram of the sample was placed in a reactor. The pyrolysis of these samples was carried out at
a vacuum of 720 mm of Hg and at a temperature of 773 K as suggested by Subbarayudu
(2003). The volatiles were condensed in the condensing train consisting of five glass bottles.
The volatiles condensed in first two bottles of the condensing train were collected for the
further study. The rest of three bottles consisted of aqueous fraction.
Supercritical fluid extraction of Pyrolysis oil
The cashew nut shell liquid collected through pyrolysis reactor was used as a feed material.
About 100 gram of pyrolysis oil was kept in the extractor of SCFE experimental set-up with
all connections and fittings made of 316 stainless steel. Carbon dioxide from the cylinder
passes through a pre-cooler, a positive displacement pump, and a pre-heater before it enters
the bottom of the extraction vessel. (The extraction vessel is maintained at a predefined
temperature). The flow of carbon dioxide is controlled by a needle valve and is measured by

a gas flow meter with an accuracy of ±0.01 kg/h. A variable frequency drive pump controls
the pressure in the vessel to an accuracy of ± 0.1 bar. Extracted oil is recovered by
expansion of the loaded solvent stream to ambient pressure in a glass separator. Extract is
collected at a fixed time interval of 30 minutes (cumulatively) by closing the needle valve.
This extract is then weighed. The needle valve is then opened and extraction process
continues for the next interval. Runs have been carried out for six hours at pressure ranging
from 120-300 bar. The experimental procedure is explained in detail elsewhere (Patel et al.,
2005). The extract of each run is analysed by GC-MS and FTIR.
Chemical Characterisation
The fractions of CNSL obtained at different operating parameters of SCFE have been
analysed by GC/MS and FT-IR. The GC/MS analysis was done using a Hewlett Packard
5890 A. GC/MS system with a 30 m × 0.25 mm ID- capillary column coated with
polysiloxane. The initial oven temperature of GC was kept at 100 o C for two minutes and then
programmed to increase at a rate of 10 o C/min to 250 o C. Afterwards, it was increased at a rate
of 30 o C/min up to 280 o C. Helium was used as a carrier gas with a flow rate of 0.7 ml/min.
The ratio of mass to charge (m/z) was used to identify the most probable fragments of the
components elucidated. The percentage area of the peak identified by GC gave the relative
concentration of the components present in the given fractions.
Results and Discussion
Table 1 gives the comparison of the components present in CNSL extracted through SCFE
route from three different sources. Second column of Table 1 indicates components present in
super critically extracted CNSL (SC CNSL) obtained from ground cashew nut shells (CNS).
Here, CNS were ground to a uniform size and fed in to the extractor. SC-CNSL was obtained
at different operating parameters from CNS.
Third column of Table 1 gives the components found in SC CNSL extracted through SCFE
of cashew nut shell oil obtained by heating CNS in the heat exchanger. In this process, CNS
were placed in the heat exchanger where they were heated up to 180 0 C. At this temperature,
CNSL started oozing out from CNS and oil was collected. This CNSL was used as a feed in
SCFE. SC CNSL was then extracted at different operating parameters.
Last column of Table 1 indicates the components present in SC CNSL extracted from CNSL
obtained through pyrolysis route. It is observed from Table 1 that the SC CNSL directly
obtained from CNS contains traces of acids whereas the same obtained from CNSL through
heat exchanger mainly contains cardanol along with acids and alkanes. The interesting point
about the composition in SC CNSL extracted from CNSL obtained through pyrolysis of CNS
is that, along with cardanol, oil contains phenols and substituted phenols. These phenols were
not found in oil obtained through the other two sources. Moreover oil obtained by this
method was free from acids and alkanes. Therefore, for resin making the CNSL obtained
through pyrolysis route is the most suitable feed for extraction SC CNSL.
Table 2 shows the identified components in SC-CNSL from thermally obtained (through
pyrolysis process) CNSL at different operating parameters. It can be seen that the
concentration of lighter molecular weight components is higher at lower operating pressures,
while the concentration of higher molecular weight components increases with increase in
pressure. The solubility of SCF for cardanol increases with increase in pressure, and hence,
the area percentage for the cardanol peak indicated by GC increases from 26% at 145 bar to
84% at 300 bar. Removing other components at lower operating pressures and then

subsequently increasing the pressure to 300 bar can extract the cardanol rich oil. The
fractionasation of CNSL obtained through pyrolysis was studied by Das et al. (2004). They
reported that the CNSL consists of cardanol, cardol, Di-n-octyl phthalate, Bis-(2,ethylhexyl)-
Phthalate and Di-n-decyl phthalate as the major components with low concentrations of
substituted phenols. This study shows that the fractions consist of cardanol as a major
component along with lower concentrations of substituted phenols. The higher molecular
weight components like different groups of phthalates have not been extracted and they
remain in residue only. The cardanol and substituted phenols, so extracted, may be used as
natural phenols for making phenol-formaldehyde resins, which is a raw material for industrial
laminates. GC-MS analysis again shows that the concentration of natural phenols along with
cardanol is maximum in supercritically extracted CNSL obtained through pyrolysis route.
The FT-IR spectra for all the fractions show a broad absorbance peak of O-H stretching
between 3600 and 3050 cm -1 , indicating the presence of phenols in CNSL.
Extraction kinetics for CNSL at different operating pressure with operating temperature of
50 o C and mass flow rate of solvent 1.2 kg/h is shown in Figure 1. The batch time was taken
as 150 minutes. It can be observed that the rate of extraction varies significantly with
extraction pressure. The increase in yield of CNSL to the tune of 50% was observed with
increase in pressure from 225 to 300 bar, keeping other operating parameters constant. It was
also interesting to note from GC-MS results that the total concentration of phenols and
cardanol has also increased with increase in pressure.
60
50
Yield (%)
40
30
20
10
0
0 25 50 75 100 125 150
Time (min)
225 bar
250 bar
300 bar
Figure 1- Extraction of CNSL at different operating pressures

Table 1 Chemical characterisation of CNSL extracted by SCFE
Operating SC-CNSL from CNS
Parameter
(P bar/ T o C)
200/60 Hexadecanoic acid (0.71)
Oleic acid (0.62)
Cardanol-C13 (0.69)
Cardanol C15 (84.20)
Methyl Cardanol (2.83)
225/60 Hexadecanoic acid (0.56)
Oleic acid (0.84)
Cardanol-C13 (0.65)
Cardanol C15 (86.26)
Methyl Cardanol (3.11)
250/60 Diethyl Phthalate (12.34)
Hexadecanoic acid (0.58)
Cardanol-C13 (7.42)
Cardanol C15 (64.89)
Methyl Cardanol (3.03)
300/60 Hexadecanoic acid (0.80),
Oleic acid (0.67),
Cardanol-C 13(2.32),
Cardanol-C15 (61.34),
Cardanol -C17 (2.06),
Diethyl phthalate (13.35)
SC-CNSL from CNSL obtained
through Heat exchanger unit
Pentadecane (0.67)
Hexadecane (0.67)
Heptadecane (0.77)
2,6,10,14 tetramethyl pentadecane
(0.65)
8 methyl Heptadecane (0.70)
Hexadecanoic acid (0.61)
Eicosane (0.47)
Cardanol (62.31)
Cardanol diene (31.24)
Pentadecane (0.04)
Heptadecane (0.08)
tetradecenal (1.99)
Cardanol-C13 (0.1.62)
Hexadecanoic acid (1.27)
Cardanol (81.54)
2 Methyl Cardanol diene (5.28)
Hexadecanoic acid (1.01)
Oleic acid (0.98)
Cardanol diene (81.94)
2 Methyl Cardanol diene (2.97)
-
SC-CNSL from
pyrolysis CNSL
3 – ethyl phenol (7.64)
2- methyl benzaldehyde
(20.51)
3- butyl phenol (1.39)
Cardanol diene (48.61)
3- ethyl phenol (3.31)
Azulene (1.89)
Ethenyloxy Benzene
(11.21)
Acenaphthylene (7.12)
3- butyl phenol (2.28)
Cardanol (66.82)
4- ethyl phenol (5.01)
propyl Benzene (11.96)
Acenaphthylene (2.83)
3- Pentyl plenol (3.18)
3- butyl phenol (1.35)
Cardanol (64.90)
2- ethyl phenol (4.89)
2- methyl benzaldehyde
(8.73)
Cardanol (80.50)

Table 2. Identification of components in SC-CNSL obtained from pyrolysis CNSL at
different operating parameters using GC-MS
Operating Parameters Retention Time (GC-
(P bar/ T o C)
spectra)
145/40 3.46
3.75
4.96
5.79
6.41
16.04
16.15
175/40 3.41
3.74
3.77
6.41
16.03
16.35
200/40 3.40
3.77
6.39
7.51
8.74
16.02
16.35
225/40 3.45
3.82
6.42
7.61
8.76
16.03
16.35
250/40 3.40
3.78
6.40
6.47
7.52
7.61
16.01
16.35
300/40 3.41
3.78
6.40
16.01
16.35
Identified
Components
2-ethyl phenol
Azulene
2-methyl Naphthalene
Cyclododecene
Acenaphthylene
Cardanol (diene)
Cardanol (triene)
4-ethyl phenol
Naphthalene
Ethenyloxy-Benzene
Acenaphthylene
Cardanol (diene)
Cardanol (triene)
3-ethyl phenol
Ethenyloxy-Benzene
Acenaphthylene
3-butyl-Phenol
3-octyl-Phenol
Cardanol (diene)
Cardanol (triene)
3-ethyl phenol
Ethenyloxy-Benzene
Acenaphthylene
3-butyl-Phenol
3-octyl-Phenol
Cardanol (diene)
Cardanol (triene)
4-ethyl phenol
Ethenyloxy-Benzene
Acenaphthylene
3-pentyl-Phenol
3-butyl-Phenol
3-octyl-Phenol
Cardanol (diene)
Cardanol (triene)
2-ethyl phenol
Ethenyloxy-Benzene
Acenaphthylene
Cardanol (diene)
Cardanol (triene)
% Area of identified
peak in GC spectra
9.19
39.83
5.57
5.75
6.88
23.32
3.25
10.07
11.74
16.31
7.65
47.05
2.69
7.64
20.51
9.65
1.39
2.60
43.32
7.58
3.31
11.21
7.12
4.15
2.28
58.58
8.24
5.01
11.96
2.83
3.18
1.35
2.80
57.33
7.57
4.89
8.73
0.09
76.90
8.69

CONCLUSIONS
The present methodology optimises the operating parameters for the extraction of phenol rich
CNSL.The optimised pressure and temperature was 300 bar and 333 K respectively. The
present study explores the possibility of extraction of natural phenols, which reduces the
dependency of petro-based phenols. The oil obtained by this method was found more stable
and less viscous as compared to the same obtained through pyrolysis process.
REFERENCES
Bridgewater T., Peacocke C., 1995, Biomass fast pyrolysis. In Proceedings of Second
Biomass Conference of The Americas – Energy, Environment, Agriculture and Industry.,
Portland. 1037.
Das P., 2004, Studies on pyrolysis of sugarcane bagasse and cashew nut shell for liquid fuels,
Ph.D. Thesis, Indian Institute of Technology, Bombay, India.
Das, P., Ganesh, A., 2003, Bio-oil from pyrolysis of cashew nut shell—a near fuel, Biomass
and Bioenergy, 27(5), 113-117.
Das, P., Sreelatha, T., Ganesh, A., 2004, Bio oil from pyrolysis of cashew nut shellcharacterisation
and related properties, Biomass and Bioenergy, 27(5), 265-275.
Patel, R. N., Bandyopadhyay, S., Ganesh, A., 2005, Extraction of cashew (Anacardium
occidentale) nut shell liquid using supercritical carbon dioxide, Bioresource Technology, In
Press, Available online 6 June 2005
Radlein D., 1999, The production of chemicals from fast pyrolysis bio-oils, In: Bridgewater
A., Fast Pyrolysis of Biomass. CPL Press.
Subbarayudu, K., 2003, Thermochemical conversion for pyrolysis liquids. Ph.D. dissertation;
Indian Institute of Technology, Bombay, India.
www.bioalberta.com/ims/client/upload/developingbiobasedindustriesincanada.doc.
visited August 16, 2005.
Date
www.dsir.nic.in/reports/techreps/tsr120.pdf date visited August 16, 2005.