Studies on process optimization for production of liquid fuels from waste plastics

By: Panda, Achyut KumarContributor(s): Singh, R K [Supervisor] | Mishra, D K [Supervisor] | Department of Chemical EngineeringMaterial type: TextTextLanguage: English Publisher: 2011Description: 241 pSubject(s): Engineering and Technology | Chemical Engineering | BiofuelOnline resources: Click here to access online Dissertation note: Thesis Ph.D/M.Tech (R) National Institute of Technology, Rourkela Summary: The present work involves the study of process opti mization for the production of liquid fuel by the catalytic pyrolysis of different plasti cs waste such as polypropylene, low density polyethylene and polystyrene using kaolin a nd acid treated kaolin as catalyst in a laboratory batch reactor. The effect of silica alum ina, which has been extensively studied by different investigators for the pyrolysis of dif ferent plastics was also studied and compared with that of the catalytic performance of kaolin. From the experimental results, it is found that kaolin is found to be suitable as a catalyst for the degradation of plastics waste to liquid fuel and valuable chemicals. Howeve r, silica alumina show superior performance compared to kaolin in terms of yield an d reaction time. From the optimization study it is found that, the m aximum oil yield in thermal pyrolysis of polypropylene, low density polyethylene and poly styrene waste was 82.5wt.%, 71.5wt.% and 93wt.% at optimum condition of tempera ture, which is improved to 87.5wt.%, 79.5wt.% and 94.5wt.% respectively in kao lin catalysed degradation under optimum condition of temperature and feed ratio. Th e rate of reaction, oil yield and quality of oil obtained in the catalytic pyrolysis are significantly improved compared to thermal pyrolysis. The catalytic activity of kaolin is further enhance d by treating it with sulphuric acid of different concentrations. Acid treatment increased the surface area, acidity and also altered the pore volume distribution of kaolin, whi ch support the cracking reaction. The maximum yield of oil in the acid treated kaolin cat alysed pyrolysis of polypropylene was 92% under optimum conditions. The composition of the oil was analyzed by FTIR and GC/MS or DHA. The oil obtained from the catalytic pyrolysis of waste polypropylene and low density polyethylene mostly contains aliphatic hydrocarbons where as that from waste polystyrene mostly aromatic hydrocarbons. The product distribution in kaolin an d acid treated kaolin catalysed pyrolysis oil is narrowed as compared to the oil ob tained in thermal pyrolysis of polypropylene. The presence of kaolin and silica al umina catalysts greatly alters the Abstract xv product distribution in polystyrene pyrolysis. The fuel properties of the oil obtained from the catalytic pyrolysis of polypropylene and low de nsity polyethylene are similar with that of petro-fuels. So they can directly be used a s an engine fuel after fractionation or as a feedstock to petroleum refineries. Similarly, the oil obtained from the pyrolysis of waste polystyrene can be used to recover styrene mo nomer as well as some other components like ethyl benzene, toluene etc as well as a feedstock to petroleum refineries. The diesel blended plastic oil obtained by the cata lytic pyrolysis of polypropylene has been tested for its performance and emission in a C I diesel engine. Engine was able to run with maximum 50% waste plastic oil- diesel blen ds. The engine vibrates at and above this blend. The brake thermal efficiency of the ble nd is found better compared to diesel up to 80% load. The brake specific fuel consumption is less compared to diesel. The NOx, CO, HC and smoke emissions are higher in case of blend. Thus the oil produced can be used after fractionation or some suitable mo dification in the engine design and engine conditions. Taguchi method is used to optimize the process para meters involved in decomposition of waste polypropylene. With this method we upgraded o ur existing knowledge about the influence of the different process parameters on th e yield of liquid fuel in a batch process and thus contributed to improving the process’s rel iability. The level of importance of the process’s parameters is determined by using ANOVA. Moreover, regression modeling has helped us generate an equation to describe the statistical relationship between the process’s parameters and the response variable (yie ld of liquid fuel) and to predict new observations.
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Thesis Ph.D/M.Tech (R) National Institute of Technology, Rourkela

The present work involves the study of process opti
mization for the production of liquid
fuel by the catalytic pyrolysis of different plasti
cs waste such as polypropylene, low
density polyethylene and polystyrene using kaolin a
nd acid treated kaolin as catalyst in a
laboratory batch reactor. The effect of silica alum
ina, which has been extensively studied
by different investigators for the pyrolysis of dif
ferent plastics was also studied and
compared with that of the catalytic performance of
kaolin. From the experimental results,
it is found that kaolin is found to be suitable as
a catalyst for the degradation of plastics
waste to liquid fuel and valuable chemicals. Howeve
r, silica alumina show superior
performance compared to kaolin in terms of yield an
d reaction time.
From the optimization study it is found that, the m
aximum oil yield in thermal pyrolysis
of polypropylene, low density polyethylene and poly
styrene waste was 82.5wt.%,
71.5wt.% and 93wt.% at optimum condition of tempera
ture, which is improved to
87.5wt.%, 79.5wt.% and 94.5wt.% respectively in kao
lin catalysed degradation under
optimum condition of temperature and feed ratio. Th
e rate of reaction, oil yield and
quality of oil obtained in the catalytic pyrolysis
are significantly improved compared to
thermal pyrolysis.
The catalytic activity of kaolin is further enhance
d by treating it with sulphuric acid of
different concentrations. Acid treatment increased
the surface area, acidity and also
altered the pore volume distribution of kaolin, whi
ch support the cracking reaction. The
maximum yield of oil in the acid treated kaolin cat
alysed pyrolysis of polypropylene was
92% under optimum conditions.
The composition of the oil was analyzed by FTIR and
GC/MS or DHA. The oil obtained
from the catalytic pyrolysis of waste polypropylene
and low density polyethylene mostly
contains aliphatic hydrocarbons where as that from
waste polystyrene mostly aromatic
hydrocarbons. The product distribution in kaolin an
d acid treated kaolin catalysed
pyrolysis oil is narrowed as compared to the oil ob
tained in thermal pyrolysis of
polypropylene. The presence of kaolin and silica al
umina catalysts greatly alters the
Abstract
xv
product distribution in polystyrene pyrolysis. The
fuel properties of the oil obtained from
the catalytic pyrolysis of polypropylene and low de
nsity polyethylene are similar with
that of petro-fuels. So they can directly be used a
s an engine fuel after fractionation or as
a feedstock to petroleum refineries. Similarly, the
oil obtained from the pyrolysis of
waste polystyrene can be used to recover styrene mo
nomer as well as some other
components like ethyl benzene, toluene etc as well
as a feedstock to petroleum refineries.
The diesel blended plastic oil obtained by the cata
lytic pyrolysis of polypropylene has
been tested for its performance and emission in a C
I diesel engine. Engine was able to
run with maximum 50% waste plastic oil- diesel blen
ds. The engine vibrates at and above
this blend. The brake thermal efficiency of the ble
nd is found better compared to diesel
up to 80% load. The brake specific fuel consumption
is less compared to diesel. The
NOx, CO, HC and smoke emissions are higher in case
of blend. Thus the oil produced
can be used after fractionation or some suitable mo
dification in the engine design and
engine conditions.
Taguchi method is used to optimize the process para
meters involved in decomposition of
waste polypropylene. With this method we upgraded o
ur existing knowledge about the
influence of the different process parameters on th
e yield of liquid fuel in a batch process
and thus contributed to improving the process’s rel
iability. The level of importance of the
process’s parameters is determined by using ANOVA.
Moreover, regression modeling
has helped us generate an equation to describe the
statistical relationship between the
process’s parameters and the response variable (yie
ld of liquid fuel) and to predict new
observations.

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