COMPLETE CATALYTIC CONVERSION OF HIGH DENSITY POLYETHYLENE INTO HYDROCARBONS WITHOUT WAX FORMATION USING FLY ASH AS CATALYST

COMPLETE CATALYTIC

CONVERSION OF HIGH DENSITY

POLYETHYLENE INTO

HYDROCARBONS WITHOUT WAX

FORMATION USING FLY ASH AS

CATALYST

P. Prem Kumar1, C.G. Saravanan1*, M. Gopalakrishnan2

1&1*

Department of Mechanical Engineering. Annamalai University Annamalainagar, India. 2

Department of Chemistry. Annamalai University Annamalainagar, India. Email: [email protected]; [email protected]

Abstract

Hydrocarbons have been obtained from waste plastic syringes, made of high density polyethylene (HDPE), by degradation using fly ash as catalyst. Complete degradation was observed with cat/pol ratio of 0.2 oil was obtained when the temperature inside the reactor was in the range 188-377C. This range is lower than those reported in other studies. The oil yield was 65.3%. No wax formation occurred suggesting that the yield of gaseous hydrocarbons was 34.7%. The oil obtained was fractionated into the following four fractions viz., fraction boiling below 100C fraction boiling in the range 100 - 150C fractions boiling in the range 150 - 200C and fraction boiling above 200 C. The physico-chemical properties of the fraction boiling in the range 100 - 150C and 150 - 200C can be used as a substance for diesel. Since fly ash is very cheaper hence fly ash seems to be better catalyst then those used previously for the degradation of HDPE.

Key words: catalytic conversion, catalyst, waste plastic, fly ash, plastic oil, hydrocarbons.

1. Introduction

Nowadays, management of waste plastic is a serious problem. Degradation of polymer waste into hydrocarbons has received greater attention [1-29]. Catalytic degradation has been found to be better than thermal degradation [4, 18, 1, 20, 22, 24, 27]. Polyethylene, a widely used thermoplastic, is a polymer of ethylene and is represented as PE. The chemical formula of PE is [CH2-CH2]n. The molecular weight and the physical properties of PE depend on the value of ‘n’. Based on the value of ‘n’, polyethylene is classified into two types viz., low density polyethylene (LDPE) and high density polyethylene (HDPE). LDPE is generally used for making flexible materials like bags and geo-membranes. HDPE is generally used for making containers including bottles. Plastic syringes made of HDPE are used for injections.

Since HDPE is widely used as a plastic material, several attempts have been made to degrade HDPE into hydrocarbons of low molecular weight. Acid zeolites have been widely used as catalyst [5-8, 9, 23, 25]. Basic catalysts MgCO3 [14], BaCO3 [19] and CaCO3 [22] also have been used. Metal supported activate carbon also has been used as catalyst [23].

Catalyst degradation has been carried out by heating at atmospheric pressure in suitable reactors or in autoclaves under hydrogen pressure. A temperature of 350-450 C has been used for the degradation. The cat/pol ratio has also been varied from 0 to 0.2. The reaction has been carried out for a period of about 2 h. In many cases more than 90% conversion has been reported. The products have been classified into waxy materials, oil and uncondensed gases.

Fly ash, obtained by burning coal, is a waste product of thermal power plants. Fly ash contains silica, alumina, iron and alkali metals [30]. Fly ash has been used as a catalyst in chemical reactions [31, 32]. In this study, we report the cracking of HDPE using fly ash as catalyst.

2. Exp

2.1 Mate

syringes with app moisture power pl

(

stainless using a th using AV

2.2 Physi

erimental

rials and meth

Plastic syring were crushed propriate amou

content. The ant at Neyveli

(a) Syringe Bef

The sketch o steel. Heatin hermocouple. VL Di gas 444

ical paramete hods

ges were obta d in to small p

unt of catalys e results and m i, which is 30

fore crusher

of the plant u ng was done The oil obta 4 analyzer.

ers study

ained from Ra pieces using c st wetted with material was su km away from

sed for cataly electrically an ained was col

Figure 2 Wa

aja Muthiah M crusher as sho

h water. The ubjected to de m our univers

Figure 1 Crusher

ytic conversio nd the temper llected in a m

aste plastic oil ex

Medical Colle own in figure

e blend obtain egradation. Fl sity.

r

on is shown i rature inside easuring jar.

traction plant

ge Hospital o 1. The crush ned was dried ly ash was obt

(b)

in Fig.2. The the reaction c The unconde

of our Univer hed material w

d in air to re tained from th

) Syringe After

e reactor was chamber was ensed gas was

rsity. The was blend emove the he thermal

r crusher

sulphur c determin

3. Resu

3.1 Effec

catalyst, collection ceased w in the rea given in t

reaction. of the pro

content, IP-13 ed as per

ults and discu

ct of catalyst

Degradation using 100gm n started and was also noted

actor after the table 1.

For the cataly These results oduct obtained

3&14 for carb IS-1448.

ussion

was carried o m catalyst and temperature . In each case e reaction. T

ytic processes s are shown in d are compare

bon residue an

out with 1 kg d 200 gm cat

at which the e the percent c The density of

the quantity o n fig. 3, 4 and ed with that of

Figure 3. Oil o

Figure 4 Oil o

and IS-1448-P

g of the polym talyst. In ea

oil ceased w conversion wa f the oil was

of hydrocarbo 5. The quanti f fly ash in fig

obtained Vs Hydr

obtained Vs Hydr

P40 for water

mer metal. T ach experimen were noted. T as calculated b

also determin

ons evolved w ities of oil for g. 7.

rocarbon (100 gm

rocarbon (150 gm

content. Gro

he degradatio nt the temper The time at w

by weighing t ned in each c

as measured d rmed are show

m catalyst)

m catalyst)

oss calorific v

on was studie rature at whic which the oil

the materials r case. All the r

during the cou wn in fig. 6. T

value was

ed without ch the oil formation remaining results are

A

c

a

The low temperatu b

obtained Amount

of catalyst

(gm) Nil 100 150 200 wer temperatu

ure at which o d by balance.

Reaction Temperaturea

(C)

250 – 420 250 – 402 227 – 392 188 – 377 ure is the temp

oil formation i

Figure 5. Oil o

Figure

Ta

Reaction time (min

180 150 130 100 perature at wh

is ceased

obtained Vs Hydr

re 6. Oil obtained

able 1. Results tab

n n)

Conver (%

51. 85. 94. 100 hich oil format

rocarbon (200 gm

Vs catalyst adde

bles

rsion )

O (%

6 42

2 60

4 62

0 65

tion commenc m catalyst)

d

Oil %)

Gasb (%)

2.7 8.9 0.1 25.1 2.3 32.1 5.3 34.7

ced and the hi

Density o the oil (kg/m3)

865 807 793 777 igher tempera

of

)

conversio degradati

on has been o ion of HDPE.

sico-chemical

Since comple in this case w ol in table 2.

Properti Specific g Kinemati Flash poi Fire poin Gross cal Pour poin Smoke po Sulphur % Carbon re Moisture Density @

e properties of ol.

ctional distilla

oil was fractio

fraction boilin

fraction boilin

fraction boilin

e fraction boili

observed) diff

F

l properties of

ete conversion were determin

es

gravity @ 15/ ic viscosity @ int C nt C

lorific value in nt C

oint C % esidue %

content @ 15 C

f the oil obtain

ation of oil

onated using f

ng within 100

ng between 10

ng between 15

ing above 200

ffers from that

Figure 7. Photogr

f the oil

n was observed ned by standar

Table 2 Properti

/15 C @ 40 C

n kJ/kg

ned are in betw

fractionating c

o

C was 23%

00 oC and 150

50 oC and 200

0 oC was 8%

at of fly ash.

raphic view of 10

d using 200 g rd methods. T

ties of plastic oil,

Plastic oil 0.776 1.63 68 74 44,122 10 Below 10 0.023 0.013 Nil 0.7769

ween those of

column shown

0 C was 33%

0 C was 36%

This shows

0 gm fly ash afte

catalyst the p These propertie

diesel and petrol

Diese 0.828 3.822 69 (5 86 44,78 15 B/W 0.035 0.01 Nil 0.825

f diesel and pe

n in fig. 7

that the cata

r degradation

hysico-chemi es are compar

el Pet 84 0.7 2 0.6

2-95) > 4 - 86 47, 3-15 100 5 0.0 Nil 5 0.7

etrol, it should

alyst is involv

ical properties red with those

trol 73722 6 Cp 45

,999

0 – 185 05

l 73722

d be a mixture

ved in the

s of the oil e of diesel

3.4 Use

The to 200 0C From tab

can be us

3.5 Com

Though observed and a rea obtained conversio formation is a very the most

4. Con

degradati occurs. T catalysts. potentiali

Referenc

of products as

physic-chemi C were evaluat ble 3 it is seen

Also the gas o sed as a dome

mparison with p

several works d so far. M R

action temper 97.8% conve on of 98.6% w n. We have us

cheap catalys suitable cataly

nclusion

This study sh ion of HDPE The degradati . Oil obtained ity of being us

ces

s fuel

ical properties ted using stan that both thes

obtained in th stic fuel.

previous study

s have been Jan et al [22] rature 385 to ersion with 6 with 54.5% oi sed a tempera st. Indeed it i yst for the deg

hows that fly a E. Complete d ion takes pla d has potential sed as a dome

s of the fractio dard methods se fractions ca

e process usin

dy

reported on t have reporte 468 0C. The 60.5% oil form

il formation a ature (188 – 37

s a waste pro gradation of H

ash, a waste p degradation o ace at a cons

lity of being u estic fuel.

Figure 8. Fractio  

on boiling in th s. These prope an be used as a

ng 200 g catal

the degradatio ed a conversio

e yield of oil mation at 435 at 440 C. We 77 C) lower duct of therm HDPE.

product of ther ccurs when t siderably low used as an alte

oned column

he range 100 o erties are comp alternating fue

yst burnt with

on of HDPE, on of 97.2% u was 52.33% 5 C. Jerzy e have observ than that used mal power plan

rmal power pl the cat/pol rat wer temperatu

ernative fuel f o

C to 150 0C a pared with tho els for diesel.

h the blue flam

complete co using calcium . Selahan Ka Walendziewsk ed 100% conv d earlier [22-2 nt. All these a

lant, can be us tio is 0.2. A re than those for diesel. Als

and in the rang ose of diesel in

me suggesting

onversion has carbonate as Karagoz et al ski [24] has o nversion with

24]. Moreov aspects make

sed as a cataly Also no wax

e reported us so the gas obt  

ge 150 oC n table 3.

that it not been a catalyst [23] have obtained a 65.3% oil er, fly ash fly ash as

yst for the formation sing other

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