Plastics/Biomass copyrolysis in an auger reactor: Physico-Chemical analysisof the products
Y. C. Rotliwala1, J. A. Shah2, N. Dhingra3, D.B. Parekh4 and P. A. Parikh5,*
1,2,3,4Centre for Environmental Research, S. N. Patel Institute of Technology, Bardoli-394 345, India.
5Department of Chemical Engineering, S.V. National Institute of Technology, Surat-395 007, India.

* e-mail: pap@ched.svnit.ac.in ; phone +912612201642 ; fax +912612227334

Abstract
This work intended to study the recovery of two types of waste by the process of pyrolysis. We demonstrated experimentswith auger pyrolyser (2 kg/h) at 500oC in the presence of nitrogen under atmospheric pressure for copyrolysis of threeplastics, high density polyethylene (HDPE), polypropylene (PP) and polystyrene (PS), individually with deoiled cake ofjatropha (JC) in equal mass proportions to produce upgraded bio-oil. Detailed characterisation of bio-oil was analysed with alittle assessment of by-products, i.e., char and non-condensable gas. GC-MS analysis of bio-oil was observed to be quiteinteresting, which shows significant reduction of oxygenates by addition of plastics with biomass.

Keywords: Waste-plastics, Jatropha, Co-pyrolysis, Bio-oil

1. Introduction
Biomass derived bio-oil is a promising alternative sourceof energy. However, bio-oil is reported to be highly
oxygenated, complex and chemically unstable which
contribute to high water formation and lower heating
values (40–50% of diesel), high viscosity, and highspecific weight of bio-oil. These limit its application asfuel [1]. Thus, the bio-oil needs to be upgraded bylowering the oxygen content [2].
As referred to this issue, we had attempted co-pyrolysis
as in-situ hydrogenation tool. During co-pyrolysis ofbiomass with plastics, the hydrogen requirement is met
by the polymer (HDPE and PP contain 14 wt. % ofhydrogen, PS contains 8.0 wt. % of hydrogen) [3].
The aim of the present study was to produce upgradedbio-oil with lower oxygenates by auger copyrolysis ofplastics with biomass (deoiled cake of jatropha, JC)along with little assessment of by-products, i.e., char andnon-condensable gas.

Bio-oil characterization
Pyrolysis oil obtained from each run was determined by
Perkin Elmer Clarus 600 GC-MS using BP-1(30 m, 0.32mm) capillary column with 0.25 µm thick stationary phase(100 % methyl polysiloxane). Further, physical analysis
of each bio-oil was determined, which includes viscosity,water content and calorific value.

3. Results and Discussion
Gas chromatography/mass spectrometry (GC/MS)
study of the bio-oils
An analysis of liquid product by a hydrocarbon type isessential to establish their potential utilization as fuel.
GC/MS analysis was used to determine the proportionsof paraffins, olefins, aromatics, and oxygenates in thebio-oil generated from the pyrolysis of JC and its
copyrolysis mixture with various plastics (Table 1).
Table 1. GC-MS Integration of JC and its co-pyrolysis
mixture (1:1 wt %) at 500°C
Area%

2. Materials and Methods

Feedstock

Materials
Deoiled Jatropha cake (JC) was obtained from thebiodiesel manufacturer. It was cleared of physicalimpurities, ground and sieved. Commercial polyolefins(HDPE, PP and PS) were stored under dry condition.
Co-pyrolysis in an auger reactor
A 2 kg/h auger-fed pyrolysis reactor used in this work
comprised of a hopper, a rotary valve, an auger reactor,
a cyclone separator, a vertical condenser and a productreceiving tank. The auger reactor was electrically heated.
The feedstock (copyrolysis mixture) was fed throughrotary valve to the auger reactor, which was heated at arate of 20oC/min.

ParaffinOlefins

Aromatics

Oxygenates

JC

3.21

4.98

26.68

58.04

JC/HDPE

28.35

25.11

39.58

6.13

JC/PP

32.75

28.31

30.33

7.81

JC/PS

6.66

18.47

68.82

5.68

Pyrolysis of only plastics reported to be produced withsignificant amount of paraffin, olefins and free ofoxygenates while substantial amount of oxygenates wereobserved in JC pyrolysed bio-oil [4, 5]. Degradation of

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013

cellulose, hemicellulose and lignin may be responsible
for the formation of a higher proportion of acids andoxygenates in the oil produced by pyrolysis of JC. Liquid
product obtained from only HDPE and PP pyrolysis
reported to be free of cyclo-alkanes and aromatics.
Higher proportion of olefins was observed in the liquid
products specifically in the case of PP pyrolysis [6]. Dueto polycyclic nature of PS, it exhibits high proportions ofaromatics in contrast to HDPE and PP [7].
In contrast to bio-oil obtain from only JC pyrolysis, copyrolysis offers considerable improvement in the quantityof paraffins, olefins and aromatics (Table 1). Such animprovement may be attributed to conversion ofoxygenates to hydrocarbon from copyrolysis mixtures.
During co-pyrolysis of biomass with plastics, hydrogenrequirement is met by the plastics (HDPE and PP contain
14 wt% of the hydrogen, PS contains 8.0 wt% ofhydrogen) [3]. Addition of PS to JC causes significant
increase in the content of aromatics, specifically ethyl
benzene and styrene at the cost of oxygenates of the JC.
Styrene (C8) is the most abundant product along withtrace amount of ethyl benzene and α-methyl styrene
produced by the pyrolysis of only PS. Highest reductionin oxygenates was observed with the use of PS as asecond material (about 90 %).
Physical properties
Table 2 summarizes the viscosity, water content andcalorific value for each of the four pyrolysis oils. In
contrast to only JC pyrolysed bio-oil, co-pyrolysis withplastics produced bio-oils of very low viscosity (maximum
56 % reduction with PS). Water content of JC derived
bio-oil was 12%, resulting from the moisture content of
JC itself whereas co-pyrolysis offers reduction in watercontent due to equal mass proportion of biomass andplastics as a feedstock. In contrast to only JC derived
bio-oil, co-pyrolysis exhibited significant improvement in
the calorific value of the bio-oil due to contribution ofliquid fractions from plastics. Highest improvement incalorific value was observed in JC/HDPE derived bio-oil.

C2-C5 in lesser proportions which exhibited calorificvalues about 2550 kcal/kg while Plastics/JC produced amixture of gases with higher calorific value (about 7000kcal/kg). Similar improvement in calorific value wasobserved for the char resulting from copyrolysis
feedstocks.

4. Conclusion
Significant reduction of oxygenates and improvement incalorific value of copyrolysed bio-oil indicates the in-situ
mild hydrogenation during the pyrolysis reaction,
resulting from the degradation of plastics.
In contrast to JC derived bio-oil, copyrolysed bio-oil offers
significant improvement in paraffin’s, olefins andaromatics due to conversion of oxygenates tohydrocarbon under mild hydrogen medium. With the useof PS as a second material, highest reduction (90 %) ofoxygenates was observed. Copyrolysis produce bio-oil
exhibiting higher heating value and lower water contentand viscosity. Calorific value of non-condensable gases
and char incresed in copyrolysis feedstocks.

References[1] A. Bridgewater, S. Czernik, J. Diebold, D. Mekr andP. Radlein, Fast Pyrolysis of Biomass: a Handbook.
Newbury, UK, CPL Scientific Publishing ServicesLtd.(1999)103-104.
[2] W. T. Tsai, M. K. Lee and Y. M Chang., Bioresour.
Techn. 98 (2007) 22-28.
[3] L. Zhou, Y. Wang, Q. Huang and Cai., Fuel Proces.
Technol. 87, (2006) 963-969.
[4] Y. C. Rotliwala and P. A. Parikh, Waste Mana. Res.
29 (2011) 1251-1261.
[5] Y. C. Rotliwala and P. A. Parikh, Energy Sources,
Part A. 34 (2012) 1055-1066.
[6] N. Miskolczi, L. Bartha, G. Deak, B. Jover.,Petrol.
Coal. 45 (2003) 125-130.
[7] P. T. Williams, E. A. Williams, Energy Fuels. 13(1999) 188-196.

Table 2. Comparison of physical properties ofbiomass/plastic copyrolysis oil
Pyrolysate
liquidViscosity(cSt at50°C)

Water
(wt%)

Calorificvalue(MJ/kg)

JC

78.00

12.00

25.27

JC/HDPE

35.12

5.10

36.63

JC/PP

34.50

5.50

34.59

JC/ PS

33.56

6.50

37.11

Evolution of by-products
Non-condensable gases mixture obtained from JC
pyrolysis composed by CO, CO2, CH4 and fractions of
7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013