Synthesis and Characterization of Liquid Fuel from PP and PS waste via Catalytic Pyrolysis
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Date
2018-06
Authors
Journal Title
Journal ISSN
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Publisher
Addis Ababa University
Abstract
Catalytic Pyrolysis of polypropylene (PP) and Polystyrene (PS) into fuel like products using
silica alumina catalyst that extracted from rice husk was investigated over temperature range of
430-470°C.Burning rice husk at 700
By:-Tihitna Abebe
o
C for 2hrs give rice husk ash and washed and dry at 800
C
for 1 hour.Finally the dried silica mixed with aluminum oxide using dry-dry mixing and calcined
for 1 hour at 800
o
C.The prepared catalyst was used for catalytic pyrolysis.The output of catalytic
pyrolysis was liquid oil, solid residues (char) and gaseous fraction.The product yields as a
function of temperature, time and catalyst amount were studied.High conversion of liquid
(44.7%), gas (60.14%) and solid residue (43.4%) was achieved at 450°C with the use of 12.5gm
catalyst amount for liquid oil and 5gm catalyst for gas and 470
o
C with the use of 12.5gm of
catalyst for solid residues.The pyrolysis time for high yield conversion of liquid oil and gaseous
fraction were 30 minutes and 60 minutes pyrolysis time for solid residues in case of PP and
liquid; 48.8% at 430
o
C in the presence of 12.5gm catalyst amount, gas; 78.286%, and residue;
52.4% at 450
o
C and 470
o
C for gaseous and residue in the presence of 12.5gm catalyst for solid
residue and 5gm catalyst for gaseous fraction at 30 minutes pyrolysis time for liquid product and
gaseous fraction and 60 minutes for residue in case of PS.At higher catalyst amount and lower
degradation temperature for PS and moderate for PP with lower residence time the yield of the
liquid fuel was higher in both plastic type.The high yield of solid residues (char) and gaseous
product was mainly due small cross section of heating, inefficiency of the pyrolyzer and
insufficient condenser.Raw waste plastics were analyzed by FTIR.The FTIR spectrum indicates
there was a presence of Naphtalenes, Olefins, and Amine, Acid group in both plastic type and
Aromatics in PS.The catalyst silica alumina that was used for catalytic pyrolysis analyzed by
XRD.XRD graph shows both silica and alumina exist.In addition to this the graph show that the
catalyst had amorphous structure.The liquid fractions were analyzed by GC/MS.The results
showed that the waste plastics of polypropylene liquid oil consisted of a range of hydrocarbon
mainly in Gasoline range (C
5
-C
) and liquid oil from catalytic pyrolysis of polystyrene waste
consisted a wide range of hydrocarbons mainly distributed within the C
12
5
–C
that was in the
range of gasoline, diesel and heavy oil.The liquid product obtained in case of Polypropylene was
enriched in the naphtalenes hydrocarbons.Similarly,the liquid product obtained in case of
polystyrene was enriched in styrene hydrocarbons with prevalence in gasoline,diesel and heavy
oil range hydrocarbons.The liquid fraction that had high yield for both plastic type were also
analyzed for fuel properties.Conclusion from the study,liquid oil from PP waste had a lower
yield (44.7), density (0.827g/cm
3
27
), viscosity (2.06cSt) and a higher value of flash point (29
C)
and calorific value (25mJ/Kg) than liquid oil (0.955g/cm
3
, 2.2cSt, 29
o
C, 20mJ/Kg) from PS
waste.Generally the whole results indicated that the derived liquid fractions were fuel-like
meeting the fuel grade criteria.
Description
Keywords
Catalytic Pyrolysis, Polypropylene, Polystyrene, Rice Husk, Silica-Alumina, FTIR, XRD, GC/MS