Enginee ing and Technology Jou nal e-ISSN: 2456-3358
Volume 10 Issue 10 Oc obe -2025, Page No.-7265-7273
DOI: 10.47191/e j/ 10i10.06, I.F. – 8.482
© 2025, ETJ
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ETJ Volume 10 Issue 10 Oc obe 2025,
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Mohamad H. H. Dei alla
S aged Ca aly ic Co-Py olysis o Polyp opylene and High-Densi y
Polye hylene: Op imizing Liquid Fuel Yield and Composi ion
Mohamad H. H. Dei alla1, Yousi A. A.2*, Muhab Hassanien S. S.3, Ib ahim Y.I. Elgady4
1Chemical Enginee ing Depa men , Sudan Uni e si y o Science and Technology, Kha oum, Sudan.
2,3,4 Polyme Enginee ing Depa men , Sudan Uni e si y o Science and Technology, Kha oum, Sudan.
ABSTRACT: The escala ing global p oduc ion o plas ics and he deple ion o ossil uel ese es unde sco e he u gency o
sus ainable was e- o-ene gy s a egies. This s udy in es iga es he s aged ca aly ic py olysis o polyp opylene (PP), high-densi y
polye hylene (HDPE), and hei blends o he p oduc ion o liquid uels. Expe imen s we e conduc ed in a semi-ba ch eac o a
450 °C (S age A) and 500 °C (S age B), wi h ben oni e as ca alys . P oduc yields and composi ions we e quan i ied ia mass balance
and GC–FID analysis. Resul s e ealed s ong eeds ock-dependen beha io s: HDPE exhibi ed supe io liquid eco e y (81.96%
in S age A, 88.24% in S age B) wi h minimal cha , whe eas PP was p one o highe cha and gas o ma ion. Co-py olysis
demons a ed syne gis ic e ec s, wi h asymme ic mix u es ou pe o ming single-polyme sys ems. No ably, he 70% PP–30%
HDPE blend achie ed he highes liquid eco e y (95.07%) and lowes gas ac ion (4.92%) du ing seconda y c acking, while he
30% PP–70% HDPE blend enhanced diesel- and ke osene- ange ac ions. GC–FID analysis con i med ha PP a o ed gasoline-
ange hyd oca bons, while HDPE en iched middle dis illa es. The unabili y o hyd oca bon dis ibu ion h ough eed composi ion
highligh s s aged py olysis as a obus pa hway o ans o ming mixed plas ic was e in o a ge ed uel- ange hyd oca bons. These
indings p o ide ac ionable insigh s in o op imizing p oduc selec i i y and yield, ad ancing he in eg a ion o polyole in py olysis
in o ci cula economy and sus ainable ene gy amewo ks.
KEYWORDS: Ca aly ic; The mal Py olysis; Co-py olysis; Fuel; Polye hylene; High-Densi y Polye hylene; Ben oni e Ca alys .
INTRODUCTION
The ising global demand o ene gy, combined wi h he
g owing challenge o plas ic was e managemen , has
gene a ed s ong in e es in sus ainable s a egies o
con e ing disca ded plas ics in o aluable p oduc s,
pa icula ly liquid uels. Such an app oach ackles he dual
issues o plas ic accumula ion in he en i onmen and he
u gen need o al e na i e ene gy sou ces as ossil uel
ese es con inue o decline [1]. Globally, plas ic p oduc ion
has su ged om abou 1.5 million onnes in 1950 o nea ly
400 million onnes by 2020, ep esen ing an inc ease o
a ound 266% o e se en decades [2]. Among he p oposed
solu ions, py olysis has eme ged as a p omising he mo-
chemical p ocess, in which long-chain hyd oca bons a e
b oken down in o sho e molecules a ele a ed empe a u es
unde oxygen- ee condi ions, enabling he con e sion o
plas ics such as polyp opylene and high-densi y polye hylene
in o liquid uels [3, 4]. This me hod no only educes he
en i onmen al oo p in o plas ic was e bu also suppo s he
ci cula economy by u ning a pe sis en pollu an in o a
usable ene gy esou ce [5, 6]. In pa icula , polyp opylene
and high-densi y polye hylene, which a e among he mos
widely used plas ics, can unde go py olysis o p oduce liquid
hyd oca bons wi h uel cha ac e is ics simila o diesel and
gasoline [7, 8]. These liquid p oduc s a e ypically ich in
calo i ic alue, making hem sui able o bo h anspo a ion
uels and chemical eeds ocks [9]. The b oad u iliza ion o
hese plas ics u he enhances he po en ial o hei
con e sion in o uels, o e ing a p ac ical solu ion o was e
educ ion and ene gy eco e y [10, 11]. Mo eo e , he
lexibili y o py olysis allows o ine- uning o ope a ional
pa ame e s such as empe a u e and hea ing a e, which can
be op imized o imp o e p oduc dis ibu ion and maximize
yields o a ge ed uel ac ions [12].
The con e sion o polyme ic was e ma e ials, such as
polyp opylene and high-densi y polye hylene, in o aluable
liquid uels ia ca aly ic he mal py olysis has ga ne ed
signi ican a en ion as a sus ainable was e managemen
s a egy and a means o ci cula izing plas ic economies [13].
This he mochemical app oach e ec i ely mi iga es he
en i onmen al impac o plas ic accumula ion while
simul aneously add essing he g owing demand o
al e na i e ene gy sou ces [14]. Py olysis, he he mal
c acking o long hyd oca bon chains in o sho e ones a
ele a ed empe a u es (300–800 °C) in he absence o
oxygen, ep esen s a p omising pa hway o ans o ming
plas ic was e in o use ul p oduc s such as liquid uels and
high-calo i ic- alue gases [3]. The in oduc ion o ca alys s
in o he py olysis p ocess can signi ican ly enhance eac ion
a es, imp o e p oduc selec i i y, and lowe ac i a ion
“S aged Ca aly ic Co-Py olysis o Polyp opylene and High-Densi y Polye hylene: Op imizing Liquid Fuel Yield and
Composi ion”
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ene gies, leading o mo e economically iable solu ions o
la ge quan i ies o was e [15]. This ca aly ic app oach
acili a es he p oduc ion o gasoline and diesel-like uels,
o e ing a di ec pa hway o alo ize plas ic was e in o high-
alue ene gy ca ie s [3, 13]. Howe e , he economic
easibili y o py olysis is o en cons ained by high ene gy
consump ion, a challenge ha induc ion hea ing has shown
p omise in mi iga ing o biomass py olysis, hough i s
applica ion in plas ic py olysis emains less explo ed [16].
Despi e his, ca aly ic py olysis is conside ed an e icien
me hod o con e plas ic was e in o high- alue p oduc s like
hyd ogen and je uel, demons a ing signi ican po en ial o
was e eco e y and u iliza ion [17].
Recen s udies ha e demons a ed ha py olysis o PP and
HDPE a op imized empe a u es be ween 350°C and 650°C
e ec i ely b eaks polyme chains in o hyd oca bon liquids,
gases, and minimal cha esidues, wi h liquid oil yields
eaching up o 90 w % unde ce ain condi ions. The liquid
uels p oduced consis mainly o C5–C20 hyd oca bons,
including a oma ics, alkanes, and alkenes, making hem
po en ial al e na i es o diesel and gasoline subs i u es.
Fu he mo e, co-py olysis o PP and HDPE o blends wi h
o he biomass ma e ials can enhance liquid yield and uel
quali y h ough syne gis ic e ec s be ween di e en
eeds ocks [12, 18-23].
Howe e , ca alys -assis ed py olysis has been explo ed o
imp o e he selec i i y and p ope ies o he liquid uels,
s ee ing he p oduc dis ibu ion owa ds high- alue
chemicals such as benzene, oluene, and xylene (BTX) and
educing unwan ed by-p oduc s [24-26]. The in luence o
p ocess pa ame e s including empe a u e, eac ion ime,
eeds ock composi ion, and hea ing a e has been
sys ema ically e alua ed, showing ha a balance be ween
hese a iables is c ucial o maximize liquid uel p oduc ion
while minimizing gas and cha o ma ion.
Pa k and Lee [27] demons a ed ha he he mal deg ada ion
o polyp opylene (PP) is s ongly go e ned by molecula
weigh dis ibu ion, whe e lowe molecula weigh ac ions
a o uel- ange hyd oca bon o ma ion due o enhanced
chain scission. Simila ly, A emanda and Singh [28]
con i med ha non-ca aly ic py olysis o high-densi y
polye hylene (HDPE) a 450–600 °C yields diesel- ange
hyd oca bons sui able o blending wi hou ex ensi e
p e ea men . Tsang e al. [2] u he emphasized he
impo ance o eeds ock con ol, showing ha op imized PP
molecula weigh enhances selec i i y owa d liquid uels.
Ghodke e al. [29] epo ed ha py olysis o HDPE, LDPE,
PP, mixed plas ics, and municipal was e a 773 K p oduced
liquid yields o 62–68 w %, p edominan ly hyd oca bons in
he C8–C20 ange, wi h p ope ies compa able o
con en ional uels. Wang e al. [30] highligh ed ha PP
py olysis in a double- luidized-bed eac o can gene a e BTX
a oma ics wi hou ca alys s, unde sco ing empe a u e as a
c i ical pa ame e o p oduc dis ibu ion. Dhaniswa a e al.
[16] also showed ha in eg a ing py olysis wi h ac iona ion
enables empe a u e-d i en con ol o yield and composi ion,
wi h C1–C13 a oma ic ac ions exhibi ing calo i ic alues
simila o comme cial uels.
Addi ionally, simula ion so wa e such as Aspen HYSYS has
been widely u ilized o modeling chemical eac ions in
con inuous s i ed ank eac o s (CSTRs), o e ing eliable
p edic i e capabili ies o p ocess imp o emen [31].
In he p esen wo k, he ole o eeds ock composi ion in
s aged ca aly ic py olysis o PP, HDPE, and hei blends is
examined, wi h emphasis placed on maximizing liquid uel
yield, minimizing cha o ma ion, and elucida ing he
syne gis ic e ec s go e ning uel- ange hyd oca bon
dis ibu ion.
MATERIALS AND METHODS
Ma e ials:
The eeds ock employed in his s udy was was e plas ic
composed o polyp opylene (PP) and high-densi y
polye hylene (HDPE). These we e es ed bo h as indi idual
polyme s and as bina y blends wi h weigh p opo ions o
100% PP, 100% HDPE, 50:50 PP/HDPE, 30:70 PP/HDPE,
and 70:30 PP/HDPE.
Ben oni e Ca alys
Ben oni e powde was used as a ca alys , wi h a ixed mass o
5 g applied in he expe imen s.
Expe imen al se up
The py olysis ials we e pe o med using a labo a o y-scale
semi-ba ch eac o wi h a o al olume o 1.0 L. Ex e nal
hea ing was supplied by a Glas-Col man le capable o
eaching empe a u es up o 1000 °C. Reac o empe a u e
was measu ed and con olled wi h a he mocouple ( ange: 0–
1300 °C), p o iding p ecise he mal managemen du ing he
expe imen s. The gaseous p oduc s gene a ed we e passed
h ough a wa e -cooled condense , whe e he condensable
po ion was collec ed in a ecei ing lask, as illus a ed in
Figs. 1 and 2. A eci cula ing wa e pump was employed o
main ain a s eady coolan low, ensu ing e icien
condensa ion. All expe imen al p ocedu es we e ca ied ou
inside a ume hood o sa e y pu poses. Mass and ime
measu emen s we e aken using a high-accu acy analy ical
balance (AMPUT) and a digi al s opwa ch, espec i ely. A
schema ic diag am o he comple e expe imen al a angemen
is shown in Fig. 3.
The mal py olysis p ocess
In each expe imen al un, 50 g o plas ic eed was placed
inside he eac o and hea ed up o 450 °C. The apo s
gene a ed we e condensed o ob ain liquid oil, while he solid
esidue (cha ) emained wi hin he eac o . The amoun o
gaseous p oduc s was calcula ed h ough a mass balance
app oach. To assess he e ec o seconda y c acking, he wax
ac ion collec ed om s age A was ed back in o he eac o
“S aged Ca aly ic Co-Py olysis o Polyp opylene and High-Densi y Polye hylene: Op imizing Liquid Fuel Yield and
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and subjec ed o a highe empe a u e o 500 °C (s age B),
leading o he p oduc ion o addi ional liquid hyd oca bons.
Expe imen al Design
A o al o i e py olysis uns we e conduc ed using a ying
polyp opylene (PP) and high-densi y polye hylene (HDPE)
eed a ios: (i) pu e PP, (ii) pu e HDPE, (iii) equal mix u e o
PP and HDPE (50:50), (i ) 30% PP wi h 70% HDPE, and ( )
70% PP wi h 30% HDPE. Each un was ca ied ou in wo
consecu i e s ages.
• S age A (P ima y Py olysis): The polyme
eeds ocks we e he mally decomposed in an ine
a mosphe e o gene a e ola ile apo s, waxes, and
cha .
• S age B (Ca aly ic C acking): The hea y waxes and
long-chain hyd oca bons om S age A we e passed
h ough a seconda y ca aly ic eac o con aining
Ben oni e as he ca alys . Ben oni e, a na u ally
occu ing aluminosilica e, p o ides s ong acidic
si es and a laye ed s uc u e ha p omo e c acking,
deoxygena ion, and a oma iza ion eac ions. I s use
enhanced he yield o ligh e liquid hyd oca bons,
educed wax accumula ion, and imp o ed o e all
uel quali y.
Ben oni e was chosen due o i s low cos , na u al abundance,
he mal s abili y, and en i onmen ally benign na u e, making
i a p ac ical al e na i e o syn he ic zeoli es o ca aly ic
py olysis.
1.1. P oduc analysis
The composi ion o he liquid p oduc s ob ained om
py olysis was analyzed using gas ch oma og aphy equipped
wi h a lame ioniza ion de ec o (GC–FID, Agilen
Technologies). This echnique allowed e icien sepa a ion o
he hyd oca bon cons i uen s and enabled quan i a i e
e alua ion o uel-like ac ions, including hose
co esponding o gasoline, ke osene, diesel, and hea y oil
p esen in he py olysis oil.
Fig. 1. The co-py olysis p ocess.
(a)
(b)
(c)
(d)
Fig. 2. Expe imen al appa a us o he co-py olysis p ocess (a) ecei ing lask, (b) a hea ing man le, (c) an analy ical
balance, (d) a lask con aining PP and HDPE blend.
“S aged Ca aly ic Co-Py olysis o Polyp opylene and High-Densi y Polye hylene: Op imizing Liquid Fuel Yield and
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Fig.3. Schema ic wo k low o he co-py olysis s udy.
RESULTS AND DISCUSSION
The s aged ca aly ic py olysis o PP, HDPE, and hei blends
e ealed signi ican di e ences in deg ada ion beha io and
p oduc selec i i y as shown in Tables 1 and 2. In S age A
(450 °C), pu e PP gene a ed 26.14 g o liquid, accompanied
by ele a ed gas (6.76 g) and cha (9.92 g) o ma ion. Fig. 4
shows he inal p oduc s o PP, HDPE, and hei blends
ob ained om he co-py olysis p ocess. This p oduc
spec um e lec s he andom chain scission o e ia y
ca bons in PP, which p omo es adical ecombina ion, gas
e olu ion, and coke deposi ion. Inc easing he p opo ion o
PP in he eed was co ela ed wi h highe cha yields (up o
9.5 g o he 30% PP–70% HDPE blend) and educed eac ion
empe a u e equi emen s, consis en wi h he enhanced
c acking eac i i y o PP.
In con as , HDPE exhibi ed supe io pe o mance, p oducing
he highes liquid ac ion (40.98 g) wi h he lowes cha
esidue (5.13 g). This ou come is a ibu ed o HDPE’s linea
s uc u e, whe e β-scission domina es and a o s he
o ma ion o long-chain hyd oca bons and waxes wi h limi ed
seconda y condensa ion. Bina y mix u es yielded
in e media e alues, ye e idence o syne gism was appa en .
Fo example, he 70% PP–30% HDPE blend gene a ed 39.3
g o liquid and only 7.5 g o cha , demons a ing ha HDPE
pa ially supp esses PP’s endency o solid esidue
o ma ion. Simila ly, he 50:50 mix u e balanced he
cha ac e is ics o he wo polyme s, p oducing 38.7 g o
liquid wi h mode a e gas and cha ac ions.
S age B (500 °C) seconda y py olysis u he ans o med he
wax- ich in e media es in o liquid oils, wi h negligible cha
o ma ion ac oss all o mula ions. Fo PP, he liquid yield
inc eased o 27.4 g, accompanied by 9.1 g o gases,
con i ming ha seconda y c acking ola ilizes waxes and
educes solid esidues. HDPE main ained he highes o e all
pe o mance, gene a ing 28.0 g o liquid wi h minimal gas
(3.4 g), unde sco ing i s abili y o p oduce s able uel- ange
hyd oca bons unde se e e he mal condi ions. Bina y blends
e ealed complex in e ac ions. The 70% HDPE–30% PP
mix u e deli e ed 26.5 g o liquid wi h only 3.2 g o gas,
closely esembling pu e HDPE and con i ming he ole o
HDPE in s abilizing liquid p oduc ion. Con e sely, he 70%
PP–30% HDPE blend, hough ini ially mo e cha - and gas-
p one, p oduced 25.1 g o seconda y liquid, demons a ing
ha HDPE mode a es PP’s gasi ica ion pa hways du ing
seconda y c acking.
Taken oge he , hese esul s indica e ha HDPE- ich sys ems
maximize liquid eco e y wi h minimal cha and gas, while
PP- ich sys ems equi e seconda y p ocessing o enhance oil
yield. The syne gis ic e ec s obse ed in co-py olysis
highligh ha eeds ock composi ion p o ides a unable le e
o selec i e p oduc dis ibu ion. Among he es ed
o mula ions, he 70% HDPE–30% PP blend consis en ly
o e ed he mos a o able balance, high wax yield in S age
A and subs an ial oil eco e y in S age B, making i he mos
p omising candida e o liquid uel p oduc ion om mixed
plas ic was e.
Fig. 4. Final p oduc s o PP, HDPE, and hei blends om he co-py olysis p ocess.
“S aged Ca aly ic Co-Py olysis o Polyp opylene and High-Densi y Polye hylene: Op imizing Liquid Fuel Yield and
Composi ion”
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Table 1 Py olysis o PP, HDPE, and hei mix u es (S age A, 450 °C)
Run
Feed Composi ion (%)
Tempe a u e
(°C)
Reac ion
Time (min)
Final
Composi ion (g)
Gases
(g)
Cha (g)
1
100% PP
260
26.14
38.32
6.76
9.92
2
100% HDPE
376
25.00
40.98
8.72
5.13
3
50% PP-50% HDPE
238
24.02
38.70
7.70
8.60
4
30% PP-70% HDPE
364
28.27
37.00
8.50
9.50
5
70% PP-30% HDPE
280
27.00
39.30
8.20
7.50
Table 2 Expe imen al esul s o he mal py olysis o PP, HDPE, and hei blends (S age B, 500 °C).
Run
Feed Composi ion
(%)
Tempe a u e
(°C)
Ini ial
Amoun (g)
Reac ion Time
(min)
Final
Liquid (g)
Gases (g)
1
100% PP
175
36.50
14.23
27.40
9.10
2
100% HDPE
178
28.90
28.00
25.50
3.40
3
50% PP-50% HDPE
125
32.20
11.09
21.50
10.70
4
30% PP-70% HDPE
124
29.70
11.07
26.50
3.20
5
70% PP-30% HDPE
126
26.40
13.21
25.10
13.00
Fig. 5. GC–FID analysis o he co-py olysis p ocess a S age A.
Fig. 6. GC–FID analysis o he co-py olysis p ocess a S age B.
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In S age A (450 °C), he p ima y py olysis yielded liquid
p oduc s as he dominan ac ion ac oss all eeds ocks, wi h
alues anging om 74.0% o 81.96% as shown in Fig. 5.
HDPE exhibi ed he highes liquid eco e y (81.96%) wi h
minimal cha esidue (0.26%), consis en wi h i s linea
s uc u e ha p omo es β-scission and he gene a ion o long-
chain hyd oca bons while supp essing condensa ion o solids.
In con as , PP p oduced a lowe liquid yield (76.64%)
alongside he highes cha ac ion (9.8%), a e lec ion o i s
andom scission pa hway and he high eac i i y o e ia y
ca bons ha a o cycliza ion and coke o ma ion. Bina y
blends displayed in e media e beha io s. The 50% PP–50%
HDPE mix u e p oduced 77.4% liquid and 7.2% cha , while
he 70% PP–30% HDPE blend yielded 78.68% liquid wi h
educed cha (5.0%), indica ing pa ial mi iga ion o PP’s
cha endency by HDPE. Con e sely, he 30% PP–70%
HDPE mix u e deli e ed 74% liquid bu an ele a ed cha
ac ion (9.0%), esembling he PP- ich deg ada ion ou e.
These obse a ions highligh ha co-py olysis ou comes a e
no linea wi h espec o composi ion; a he , HDPE can
ei he supp ess o ampli y PP’s cha - o ming endency
depending on he ela i e blend a io.
In S age B (500 °C), seconda y py olysis o he wax ac ion
led o nea -comple e elimina ion o cha ac oss all eeds ocks,
wi h enhanced liquid eco e y as shown in Fig. 6. Pu e HDPE
achie ed he highes liquid ac ion (88.24%) wi h only
11.76% gases, con i ming i s p opensi y o p oduce uel-
ange hyd oca bons a ele a ed empe a u es wi h minimal
solid esidue. PP, by con as , yielded 75.06% liquid and
24.93% gases, signi ying i s g ea e endency owa d gas
e olu ion du ing seconda y c acking. Bina y blends exhibi ed
mo e complex and some imes non-linea p oduc
dis ibu ions. The 50% PP–50% HDPE mix u e gene a ed he
lowes liquid ac ion (66.77%) and he highes gas ac ion
(33.22%), implying an agonis ic in e ac ions be ween PP and
HDPE pa hways, whe e PP-d i en adical ecombina ion
enhances gas e olu ion while supp essing liquid s abili y. In
con as , asymme ic mix u es demons a ed clea syne gis ic
bene i s. The 30% PP–70% HDPE blend achie ed 89.32%
liquid yield wi h only 10.77% gases, ou pe o ming he
indi idual polyme s, while he 70% PP–30% HDPE blend
deli e ed he highes o e all liquid eco e y (95.07%) and he
lowes gas ac ion (4.92%). These esul s unde sco e ha
HDPE no only supp esses cha o ma ion bu , when
combined wi h PP, can enhance liquid selec i i y a beyond
he indi idual con ibu ions o each polyme .
O e all, he s aged he mal py olysis s a egy demons a es
dis inc oles o eeds ock composi ion in shaping p oduc
dis ibu ions. HDPE is in insically a o able o liquid
eco e y wi h minimal cha , while PP is mo e p one o
gasi ica ion and coke o ma ion. Howe e , co-py olysis
enables uning o p oduc yields, whe e asymme ic
PP/HDPE mix u es, pa icula ly PP- ich blends, exhibi
s ong syne gis ic e ec s ha maximize liquid oil eco e y
while i ually elimina ing cha . These insigh s emphasize
ha eeds ock blending and s aged ope a ion a e c i ical
le e s o op imizing py olysis owa d high liquid yields and
educed solid esidues, ad ancing he iabili y o was e
polyole ins as eeds ocks o sus ainable uel- ange
hyd oca bon p oduc ion.
Fig. 7. Fuel- ange hyd oca bon dis ibu ion o liquid p oduc s om he co-py olysis p ocess o PP, HDPE and hei blends
by GC–FID analysis.
The composi ional analysis o he liquid ac ions ob ained
om ca aly ic s aged py olysis o PP, HDPE, and hei
mix u es p o ides clea e idence o how eeds ock iden i y
go e ns he dis ibu ion o uel- ange hyd oca bons as shown
in Fig.7. Pu e PP p oduced he highes p opo ion o gasoline
(41.4%), consis en wi h i s andom chain scission
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mechanism ha a o s he o ma ion o ligh e hyd oca bons.
I s ke osene (24.8%) and diesel (26.4%) ac ions we e
compa a i ely lowe , while hea y oil was minimal (7.4%). In
con as , HDPE exhibi ed a ma kedly di e en p o ile, wi h
gasoline yield educed o 20.8% and hea ie ac ions
domina ing—diesel (37.2%) and ke osene (30.4%)—
e lec ing he in luence o i s linea s uc u e and β-scission
pa hway ha p omo e long-chain hyd oca bon o ma ion.
Co-py olysis o PP and HDPE yielded in e media e
dis ibu ions, highligh ing syne gis ic and compe i i e
in e ac ions be ween he wo deg ada ion mechanisms. The
50:50 PP–HDPE blend p oduced a balanced p o ile wi h
gasoline (31.6%), ke osene (27.8%), and diesel (31.8%),
sugges ing ha mu ual mode a ion o PP’s ligh p oduc
endency and HDPE’s hea y p oduc bias can yield a e sa ile
uel spec um. HDPE- ich mix u es (70% HDPE–30% PP)
gene a ed highe diesel con en (33.2%) and ke osene
(30.0%), whe eas PP- ich mix u es (70% PP–30% HDPE)
shi ed he spec um owa d gasoline (33.6%) a he expense
o hea ie ac ions.
O e all, hese esul s demons a e ha PP s ongly
con ibu es o gasoline- ange hyd oca bons, which a e o
high economic alue o spa k-igni ion engines, while HDPE
a o s ke osene and diesel ac ions sui able o comp ession-
igni ion engines and indus ial uel applica ions. Impo an ly,
blending he wo polyme s p o ides a p ac ical s a egy o
uning he hyd oca bon p o ile: HDPE- ich blends enhance
middle-dis illa e yields, while PP- ich blends inc ease ligh -
end uel selec i i y. Such unabili y unde sco es he
lexibili y o s aged py olysis as a pla o m o ailo ing uel-
ange p oduc s om mixed plas ic was e s eams.
CONCLUSION
This s udy demons a ed ha s aged he mal py olysis o
polyp opylene (PP), high-densi y polye hylene (HDPE), and
hei blends p o ides an e ec i e pa hway o alo izing
was e plas ics in o liquid uels wi h unable p oduc
dis ibu ions. HDPE consis en ly exhibi ed supe io
pe o mance, yielding he highes liquid ac ions wi h
minimal cha o ma ion due o i s linea s uc u e and β-
scission pa hway. By con as , PP was mo e p one o gas and
cha gene a ion, al hough seconda y c acking a ele a ed
empe a u es signi ican ly imp o ed i s liquid yield.
Impo an ly, co-py olysis e ealed s ong syne gis ic e ec s:
while symme ic blends such as 50:50 PP–HDPE exhibi ed
an agonis ic in e ac ions ha inc eased gas e olu ion,
asymme ic mix u es; pa icula ly 70% PP–30% HDPE and
30% PP–70% HDPE, maximized liquid oil eco e y while
i ually elimina ing cha .
Fuel- ange hyd oca bon analysis con i med ha PP- ich
sys ems a o gasoline-like ac ions, whe eas HDPE
en iches ke osene and diesel p oduc s, o e ing lexibili y in
ailo ing uels o spa k-igni ion and comp ession-igni ion
applica ions. Among all o mula ions, he 70% HDPE–30%
PP blend p o ided he mos balanced p o ile, combining high
liquid eco e y wi h a o able middle-dis illa e yields.
O e all, he indings highligh ha eeds ock composi ion
and s aged ope a ion a e c i ical le e s o op imizing
py olysis ou comes. The abili y o ine- une hyd oca bon
dis ibu ions h ough PP/HDPE blending ad ances he
po en ial o py olysis as a sus ainable was e managemen
s a egy and a con ibu o o ci cula plas ic economies.
Fu u e wo k should explo e ca alys -assis ed s aged py olysis
and p ocess in ensi ica ion s a egies, such as induc ion
hea ing and eac o design op imiza ion, o u he enhance
selec i i y, ene gy e iciency, and scalabili y owa d
indus ial implemen a ion.
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