Fuel 316 (2022) 123341
A ailable online 1 Feb ua y 2022
0016-2361/© 2022 The Au ho s. Published by Else ie L d. This is an open access a icle unde he CC BY-NC license (h p://c ea i ecommons.o g/licenses/by-
nc/4.0/).
Full Leng h A icle
C acking o plas ic py olysis oil o e FCC equilib ium ca alys s o p oduce
uels: Kine ic modeling
Robe o Palos
*
, Elena Rod íguez, Alazne Gu i´
e ez, Ja ie Bilbao, Jos´
e M. A andes
Depa men o Chemical Enginee ing, Uni e si y o he Basque Coun y UPV/EHU, PO Box 644, 48080 Bilbao, Spain
ARTICLE INFO
Keywo ds:
Ca aly ic c acking
Fuels
Plas ic py olysis oil
Kine ic model
Deac i a ion
Was e e ine y
ABSTRACT
The kine ics o he ca aly ic c acking o plas ic py olysis oil (PPO) o e h ee FCC ( luid ca aly ic c acking)
equilib ium comme cial ca alys s has been modeled. The PPO comes om he as py olysis o high-densi y
polye hylene (HDPE). The c acking uns ha e been ca ied ou in a labo a o y-scale eac o unde FCC condi-
ions: 500–560 ◦C; ca alys /oil weigh a io o 5 g
ca
g
PPO-1
; and con ac ime o 1.5–6 s. Fou di e en eac ion
schemes composed o six lumps ha e been compa ed and i has been ob ained by s a is ical means ha he
simples one is he mos app op ia e o desc ibing he p ocess. The di e ences in he kine ic pa ame e s ha e
been ela ed o he p ope ies o he ca alys s. Among hem, o al acidi y and mesopo ous s uc u e ha e a key
ole. The o me o p omo ing he c acking eac ions and he la e o limi ing he di usional es ic ions o
bo h he bulky compounds wi hin he PPO and he o med coke p ecu so s. This way, ECAT-3 ha is he mos
acid and mos mesopo ous ca alys , maximizes he yields o naph ha (33.6 w %) and lique ied pe oleum gases
(LPG) (18.9 w %). In con as , ECAT-1 and ECAT-2 should be chosen o p oducing ligh cycle oil (LCO). Fo
ECAT-3, he appa en ac i a ion ene gies o he con e sion o hea y cycle oil (HCO) in o ligh cycle oil (LCO),
LCO in o naph ha, and LCO in o LPG a e 60.5 42.5 and 58.3 kJ mol
-1
, espec i ely. In addi ion, hose o he
o ma ion o coke om HCO, LPG and d y gas a e 129.0, 4.4 and 40.7 kJ mol
-1
, espec i ely.
1. In oduc ion
The de elopmen and wellness o he humankind implies an inc ease
o global pollu ion. One o he consequences is he inc easing p esence o
was e plas ics in he municipal solid was es (MSW), which o e lows he
managemen capabili y o bo h public and p i a e en i ies. Conse-
quen ly, an unaccep able amoun o hese was es ends up land illed,
causing he con amina ion o he soils and he aqui e s [1]. In o de o
sol e hese p oblems, i is well es ablished he in e es on e ia y
ecycling by means o he mochemical p ocesses, i.e. py olysis and
gasi ica ion [2].
The as py olysis o plas ics is pe o med a low empe a u e, using
high hea ing a es and sho esidence ime o he ola iles. Mo eo e , i
can be ca ied ou in simple and e sa ile uni s equipped wi h di e en
ypes o eac o s ( o a y kilns, sc ew eac o s, luidized o spou ed beds,
e c.) en ailing a educed en i onmen al impac and wi h he possibili y
o uning he ope a ing condi ions o adap he p oduc ion o he ype o
plas ic ed [3,4]. The ideal goal o py olysis p ocesses is he monome
eco e y, which can be done wi h high yields in he py olysis o poly-
s y ene [5] and polyme hyl-me hac yla e [6]. On he o he hand, o
polyole inic plas ics, which cons i u e wo hi ds o he plas ic ac ion
ound in he MSW [7], is o g ea in e es he p oduc ion o plas ic py-
olysis oil (PPO) because o i s possibili ies o be used as an al e na i e
uel [8].
Based on i s p ope ies, he PPO has been conside ed as a po en ial
uel o diesel engines eeding i nea ly o blended wi h comme cial
diesel [9]. Ne e heless, he PPO does no mee he ough equi emen s
o comme cial uels and equi es o physicochemical ea men s o adap
i s composi ion [10]. This si ua ion has led o he p oposal o in eg a ing
he as py olysis o was e plas ics wi h he upg ading o he PPO in
e ine y uni s (Was e-Re ine y) [11]. The in e es o he p oposal lays on
he capaci y o e ine y uni s o alo izing he PPO, ei he in ad hoc
ca aly ic uni s o in al eady exis ing indus ial uni s. The luid ca aly ic
c acking (FCC) uni s a e he mos app op ia e ones in he sho e m,
gi en hei high capaci y and e sa ili y o manage uncon en ional
eeds, such as di e se seconda y e ine y s eams [12,13] o bio-oil [14].
Indeed, he chemical composi ion o he PPO (highly ole inic and ee o
a oma ics) makes i app op ia e o be ed o ca aly ic c acking uni s wi h
he aim o p oducing uels ee o sul u and ni ogen [15]. Fu he mo e,
wi hin he acili ies a ailable in he e ine ies, he e a e he equi ed
ac iona ion and condi ioning uni s o ob ain uels simila o
* Co esponding au ho .
E-mail add ess: [email p o ec ed] (R. Palos).
Con en s lis s a ailable a ScienceDi ec
Fuel
jou nal homepage: www.else ie .com/loca e/ uel
h ps://doi.o g/10.1016/j. uel.2022.123341
Recei ed 23 Sep embe 2021; Recei ed in e ised o m 10 Janua y 2022; Accep ed 16 Janua y 2022
Fuel 316 (2022) 123341
2
con en ional ones. Among he ad an ages ha he Was e–Re ine y
s a egy o e s, he ollowing ones mus be highligh ed: (i) he ecycling
o pe oleum-de i ed p oduc s wi h he subsequen sa ings o aw ma-
e ials; (ii) he emo al o economic ba ie s ha en ails he design and
cons uc ion o new uni s, which co espond o he high cos o he
equipmen and o he ma ke ing o non-con en ional uels ha would
compe e agains he con en ional uels; and, (iii) he a ional o gani-
za ion o he plas ics ecycling, ca ying ou he py olysis p ocess in a
delocalized way in uni s loca ed nea by o he was e plas ics collec ion
and seg ega ion poin s. The PPO would be a e wa ds anspo ed om
di e en geog aphical a eas o cen alized e ine ies o i s la ge-scale
alo iza ion. Feeding a liquid s eam, such as he PPO, in o a c acking
uni , en ails less echnical di icul ies ha he eeding o pu e poly-
ole ins, he c acking o which has been also s udied [16–18]. None he-
less, hese ini ia i es will equi e a igo ous con ol o he eeds, since
hei composi ion can be easily con amina ed by he p esence o
di e en plas ics and o addi i es and pollu an s in he was e plas ics.
In a p e ious wo k i has been s udied he e ec o he p ope ies o
di e en FCC equilib ium ca alys s on he p oduc ion o uel om PPO,
ope a ing a 500–560 ◦C and using a ise simula o eac o [19].
In e es ingly, he yields o naph ha (highly ole inic and wi h a high
oc ane a ing) and ligh ole ins we e supe io o 40 and 12 w %,
espec i ely. The p oposed ini ia i e is simila o ha o c acking wax
om Fische -T opsch p ocess wi h he aim o p oducing high oc ane
gasoline and ligh ole ins [20,21].
Bo h o he simula ion and op imiza ion o an ad hoc designed
eac o and o he eeding o he PPO o an indus ial FCC uni , i is
equi ed a kine ic model capable o quan i ying he p oduc s dis ibu-
ion. T adi ionally, he e o s in he kine ic modeling ha e been ocused
on he c acking o acuum gasoil (VGO). Mous a a and F omen [22]
we e pionee s in aking in o accoun he he e ogeneous composi ion o
he VGO and hey p oposed a kine ic model wi h a complex eac ion
scheme ha desc ibed he indi idual eac ions in ol ed and he o -
ma ion o coke by means o elemen a y s eps. This ype o molecula -
le el kine ic models has been also applied o he c acking o wax
om Fische -T opsch p ocess [21]. Ne e heless, mos o he wo ks ha e
es ablished lump-based kine ic models ha simpli y he compu ing and
hei pos e io use in he design o he eac o [23–25]. Apa om he
complexi y o he eac ion scheme, an addi ional di icul y o ob aining
kine ic models is he ex emely as deac i a ion o he ca alys caused
by coke deposi ion [26,27]. Kine ic models o he ca aly ic c acking o
VGO conside be ween 3 and 17 lumps and ha e been collec ed by
di e en au ho s [28,29]. These models assume ha kine ic pa ame e s
a e appa en alues as a consequence o he di usional es ic ions
caused by he componen s o he VGO (especially he hea ie ones) [30].
In his wo k, i has been es ablished a six-lump based kine ic model
o he c acking o PPO ob ained in he py olysis o high-densi y poly-
e hylene om he expe imen al da a ob ained in a p e ious wo k [19].
The aim o he wo k is o p o ide a ool o quan i ying he e ec s o he
ope a ing condi ions on he yields o p oduc s o in e es , such as uels
(gasoline and diesel) and commodi ies (ligh ole ins). In he modeling, i
has been aking in o accoun he ca alys deac i a ion by coke deposi-
ion, which is ex emely signi ican in c acking eac ions. Mo eo e , he
analysis o he kine ic pa ame e s ob ained o h ee di e en FCC
equilib ium ca alys s wi h di e en acidi y and po ous s uc u e allows
o assessing he e ec o hese p ope ies on he di e en ca aly ic s eps
and on he o ma ion o coke.
2. Ma e ial and me hods
2.1. Ma e ials
The plas ic py olysis oil (PPO) has been ob ained a 500 ◦C unde as
py olysis condi ions by eeding i gin high-densi y polye hylene (HDPE)
o a oun ain con ined conical spou ed bed eac o [31].
Th ee di e en comme cial equilib ium FCC ca alys s (ECAT-1,
ECAT-2 and ECAT-3) ha e been used in he wo k. The ca alys s ha e
been collec ed om he ca alys pu ge s eam o indus ial FCC uni s,
speci ically ECAT-1 om Pe ono Re ine y (Spain) and he o he ca a-
lys s om Pe ob as Re ine y (B azil). Consequen ly, hey a e equilib-
ium ca alys s, since hey ha e been submi ed o nume ous cycles
composed o eac ion, s ipping and egene a ion s eps in hei co e-
sponding FCC uni s [32].
Nomencla u e
Abb e ia ions
C/O ca alys o oil weigh a io
FBP inal boiling poin
FCC luid ca aly ic c acking
HCO hea y cycle oil
IBP ini ial boiling poin
LCO ligh cycle oil
LPG lique ied pe oleum gases
MSW municipal solid was e
PPO plas ic py olysis oil
SSE mean squa ed e o
VGO acuum gasoil
Symbols
A co ela ion coe icien
C mola concen a ion (mol cm
-3
)
E appa en ac i a ion ene gy (kJ mol
-1
)
i ce ain lump
j ce ain eac ion
k appa en kine ic pa ame e (m
6
kg
ca -1
kmol
-1
s
-1
/ m
3
kg
ca -
1
s
-1
)
k
d
ca alys deac i a ion kine ic pa ame e (s
-1
)
m eac ion o de
M
HCO
molecula weigh o HCO lump (g mol
-1
)
m
ca
mass o ca alys (g)
m
PPO
mass o PPO (g)
n
e
numbe o expe imen s
n
l
numbe o lumps
n
p
numbe o pa ame e s
p ce ain expe imen
eac ion a e
R ideal gas cons an (8.314 J mol
-1
K
-1
)
con ac ime (s)
T eac ion empe a u e (◦C)
T* e e ence empe a u e (◦C)
V olume o he eac o (cm
3
)
y weigh ac ion
G eek symbols
α
le el o signi icance
φ ac i i y e m
υ
s oichiome ic coe icien
ν
deg ees o eedom
R. Palos e al.
Fuel 316 (2022) 123341
3
2.2. Expe imen al se up
The ca aly ic c acking uns ha e been pe o med on a labo a o y
scale mic o- ise eac o , speci ically designed o mimic he condi ions
o he ise eac o o indus ial FCC uni s [33]. A schema ic ep esen-
a ion o he expe imen al uni oge he wi h an explana ion o he
expe imen al p ocedu e can be ound elsewhe e [34]. The ope a ing
condi ions o ise simula o eac o ha e been: empe a u e, 500, 530
and 560 ◦C; ca alys o oil weigh a io (C/O), 3–7 g
ca
g
PPO-1
; and
con ac ime, 1.5–6 s.
3. Kine ic model
3.1. Model desc ip ion
The ca aly ic c acking o he PPO has been desc ibed by means o a
six-lump eac ion ne wo k. The six lumps a e hea y cycle oil (HCO,
C
20+
), ligh cycle oil (LCO, C
13
-C
20
), naph ha (C
5
-C
12
), lique ied pe o-
leum gases (LPG, C
3
-C
4
), d y gas (C
1
-C
2
) and coke (ca bonaceous ma-
e ial deposi ed on he ca alys ). The eac ion ne wo k in Fig. 1a
co esponds o pa en eac ion ne wo k and i accoun s o six een ki-
ne ic pa ame e s, o which i mus be added a pa ame e o ca alys
deac i a ion.
3.2. Model equa ions and me hodology
The kine ic modeling me hodology used is based on he one de el-
oped by Toch e al. [35] o ca aly ic p ocesses wi h complex pa hways
and on ha p oposed by Co de o-Lanzac e al. [36,37], since hey
included he ca alys deac i a ion on i . Fu he mo e, he me hodology
has been adap ed o handling he expe imen al da a ob ained in a ba ch
eac o . Likewise, a mola balance o he mic o ise eac o has been
also equi ed in o de o p ope ly desc ibe he beha io o he di e en
lumps [38]. Acco ding o he eac ion ne wo k in Fig. 1a, he eac ion
a e equa ions ha desc ibe he e olu ion wi h con ac ime o he
di e en lumps a e lis ed below.
dyHCO
d = −
φ[( mPPO
MHCO V)(k1+k2+k3+k4+k5)y2
HCO ]mca
V(1)
dyLCO
d =
φ[( mPPO
MHCO V)(k1y2
HCO)− (k6+k7+k8+k9)yLCO ]mca
V(2)
dyNaph ha
d =
φ[( mPPO
MHCO V)(k2y2
HCO)+(k6yLCO)− (k10 +k11 +k12)yNaph ha ]mca
V
(3)
dyLPG
d =
φ[( mPPO
MHCO V)(k3y2
HCO)+(k7yLCO)+(k10 yNaph ha)− (k13 +k14)yLPG ]mca
V
(4)
Fig. 1. P oposed eac ion ne wo ks.
R. Palos e al.
Fuel 316 (2022) 123341
4
being y
i
he weigh ac ion o lump i, he con ac ime be ween he
eac an s and he ca alys in he eac o , M
HCO
he molecula weigh o
he lump HCO, V he olume o he eac o , k
j
he appa en a e cons an
o eac ion j, m
PPO
he mass o PPO ed and m
ca
he mass o ca alys
used.
One should obse e ha he ca aly ic c acking o he di e en lumps
has been desc ibed using i e e sible i s -o de eac ions, wi h he
excep ion o he c acking o HCO lump, which has been conside ed as an
i e e sible second-o de eac ion [28,39]. Addi ionally, i has been
assumed ha c acking eac ions a e non-selec i ely a ec ed by ca alys
deac i a ion and i has been quan i ied in Eqs. (1)-(6) by using he same
ac i i y e m (φ), which has been de ined as:
φ=(− j)
(− j)0
=exp ( − kd )(7)
whe e (−
j
) and (−
j
)
0
a e he eac ion a es o each s ep o he eac ion
ne wo k a ime and ze o ime, espec i ely, and k
d
is he deac i a ion
pa ame e .
The equa ion p oposed o explaining he deac i a ion kine ics co -
esponds o a i s -o de exponen ial unc ion, which is e ec i e o
desc ibing he ac i i y decay in he c acking eac ions whe e a no ably
deac i a ion occu s o sho con ac imes (<20 s) [40].
Fo compu ing he kine ic pa ame e s, hey ha e been exp essed as a
unc ion o empe a u e by means o he epa ame e ized A henius
equa ion in o de o a oid he eg ession issues de i ed om he s ong
co ela ion be ween he ac i a ion ene gy and he p e-exponen ial ac-
o .
kj=k∗
jexp [−Ej
R(1
T−1
T∗)] (8)
being k
j
* he kine ic eac ion a e o he j eac ion s ep a he e e -
ence empe a u e T* (500 ◦C), E
j
he co esponding appa en ac i a ion
ene gy and R he uni e sal gas cons an .
The sys em o di e en ial equa ions ha desc ibes he ca aly ic
c acking o PPO, Eqs. (1)-(6), has been sol ed using an in-house w i en
MATLAB code. The code es ima ed he equi ed kine ic a e cons an s
and ac i a ion ene gies o i he weigh ac ion o he di e en pa-
ame e s o hose expe imen ally ob ained. To ind he bes i ing
alues, a loss unc ion in which he mean squa ed e o is minimized has
been employed.
Loss Func ion =1
ne
⋅∑
nl
1∑
p
1(ycal
i,p−yexp
i,p)2(9)
whe e y
ip
is he weigh ac ion o lump i o expe imen p, n
l
is he o al
numbe o lumps and n
e
he o al numbe o expe imen s. Mo eo e ,
supe sc ip s “cal” and “exp” deno e he calcula ed and expe imen ally
de e mined weigh ac ions, espec i ely.
3.3. S a is ical signi icance
The disc imina ion be ween he di e en models p oposed has been
pe o med by means o a s a is ical signi icance es based on Fishe ’s
me hod. The p ocedu e is well explained in he li e a u e [41]. In b ie ,
o wo kine ic models wi h di e en deg ees o eedom (
ν
A
∕=
ν
B
) i
model B shows a smalle mean squa ed e o han model A (SSE
B
<
SSE
A
), he imp o emen o e ed by model B wi h espec o model A will
be s a is ically signi ican when he ollowing condi ion is ul illed:
FA−B=
SSEA−SSEB
SSEB
ν
A−
ν
B
ν
B
>F1−
α
(
ν
A−
ν
B,
ν
B)(10)
being F
1-
α
he c i ical alue o he Fische dis ibu ion unc ion o a
le el o signi icance o 95% (
α
=0.05). The deg ees o eedom ha e
been compu ed acco ding o he ollowing equa ion by aking in o ac-
coun he numbe o expe imen s (n
e
), numbe o lumps (n
l
) and numbe
o pa ame e s (n
p
):
ν
= (ne⋅nl) − np(11)
4. Resul s
4.1. Cha ac e iza ion
The main p ope ies o he PPO a e p o ided in Table 1. I consis s o
a mix u e o hyd oca bons wi h a b oad dis illa ion ange ha can be
di ided in o 82.0 w % o HCO (hea y cycle oil), 12.5 w % o LCO (ligh
cycle oil) and 5.5 w % o naph ha. These ac ions ha e been de ined
acco ding o he usual c i e ia ollowed by oil e ine s: naph ha
(C
5
–C
12
), LCO (C
13
–C
20
) and HCO (C
21+
) [42]. Addi ionally, he
chemical composi ion o he PPO ob ained by ch oma og aphic means
has been al eady epo ed in ou p e ious wo k [43]. B ie ly, hey a e
composed o 67.6 w % o ole ins and 32.4 w % o pa a ins.
E en hough a desc ip i e cha ac e iza ion o he ca alys s has been
al eady epo ed in a p e ious wo k [44], hei main p ope ies a e
shown in Table 2. In o de o compa e he p ope ies o hese indus ial
ca alys s i mus be aken in o accoun i s complex con igu a ion, which
is composed o an ul as able Y zeoli e (USY) embedded in a meso- and
mac opo ous ma ix (consis ing o a mix u e o clay, silica and alumina)
[45]. The highes con en o zeoli e o ECAT-2 (21 w %) is in conco -
dance wi h i s high mic opo e su ace a ea (139 m
2
g
-1
). ECAT-3, in u n,
has he highes ma ix/USY zeoli e a io, which u ns in o he highes
mesopo e su ace a ea and mesopo e olume (111 m
2
g
-1
and 172 cm
3
g
-
1
, espec i ely). This way, i s wide po ous s uc u e inc eases he
accessibili y o he NH
3
o he acid si es, making ECAT-3 he ca alys
wi h he highes o al acidi y (124
μ
mol
NH3
g
-1
), acid s eng h (130 kJ
mol
NH3-1
) and B øns ed/Lewis acid si es a io (1.56). Fu he mo e, he
high mesopo e olume o he ma ix will educe di usional cons ain s
Table 1
Cha ac e iza ion esul s o he PPO [43].
Physical p ope ies
Speci ic g a i y (◦API) 20.7
Viscosi y a 100 ◦C (cS ) 2.2
A e age molecula weigh (g mol
-1
) 1430
Simula ed dis illa ion (◦C)
IBP-FBP 157–618
T
50
-T
95
472–601
dyD y Gas
d =
φ[( mPPO
MHCO V)(k4y2
HCO)+ (k8yLCO) + (k11 yNaph ha)+ (k13 yLPG) − (k15 yD yGas)]mca
V(5)
dyCoke
d =
φ[( mPPO
MHCO V)(k5y2
HCO)+ (k9yLCO) + (k12 yNaph ha)+ (k14 yLPG) + (k15 yD yGas)]mca
V(6)
R. Palos e al.
Fuel 316 (2022) 123341
5
o he long chains o PPO, easing i s access o he ex e nal c ys al su ace
o zeoli es and, consequen ly, i s pos e io c acking on he channels o
he zeoli e.
I is also ema kable he p esence o a e ea hs in he ca alys s,
especially o ECAT-1 (2.50 w %), since hese elemen s inc ease he
selec i i y o naph ha lump [46]. The p esence o P
2
O
5
(wi h a
maximum alue o 0.62 w % o ECAT-1) aims he o ma ion o ligh
ole ins. Me als, such as V, Fe and Ni, a e i e e sibly deposi ed on FCC
ca alys s in he successi e eac ion- egene a ion cycles ac ing as poisons
and causing a educ ion in h oughpu by inc easing coke o ma ion
[47].
4.2. Model simpli ica ion
In o de o alida e he model p oposed, he esul s ob ained wi h
ECAT-1 o he pa en eac ion ne wo k (Fig. 1a) a e shown below. The
alues o he appa en kine ic a e cons an s and ac i a ion ene gies ha
ha e minimized he mean squa ed e o o he loss unc ion (Eq. (9))
ha e been collec ed in Table 3. The alues o he pa ame e s p o ide a
la ge amoun o in o ma ion abou he ele ancy o he di e en ca a-
ly ic s eps. This way, i can be seen ha he s eps ha go e n he ca a-
ly ic c acking o PPO a e hose in which he c acking o HCO ac ion is
in ol ed (s eps #1 o #5 in Fig. 1a). The highes c ackabili y o he
compounds wi hin he HCO ac ion is a common esul ob ained in he
ca aly ic c acking o hyd oca bon s eams and i is cohe en wi h he
highe c ackabili y o he high-molecula weigh ole ins [25,48]. How-
e e , he alues o some o he kine ic a e cons an s, in pa icula hose
co esponding o s eps #8 o #12, a e so small ha he con ibu ion o
hese kine ic s eps can be conside ed negligible.
The e o e, h ee al e na i e eac ion ne wo ks ha e been p oposed
(Fig. 1b, c and d) in which a ious simpli ica ions ha e been made based
on he esul s collec ed in Table 3. This way, in al e na i e ne wo k 2
(Fig. 1b) he naph ha ac ion has been conside ed as a inal p oduc , i.e.
s eps #10, #11 and #12 ha e been emo ed om he pa en ne wo k
(Fig. 1a). In al e na i e ne wo k 3 (Fig. 1c), in u n, he s eps emo ed
ha e been hose in which LCO ac ion is con e ed in o coke and in o
d y gas ac ions (s eps #8 and #9). Finally, al e na i e ne wo k 4,
which is he simples one om all he p oposed, igno es all he ou es
emo ed in al e na i e ne wo ks 2 and 3. Thus, in al e na i e ne wo k 4
(Fig. 1d) s eps #8 o #12 ha e been emo ed om he pa en one
(Fig. 1a).
Consequen ly, he i ing o he expe imen al da a ob ained o he
ca aly ic c acking o PPO wi h ECAT-1 has been also pe o med o he
al e na i e eac ion ne wo ks. O e all, good i ing esul s ha e been
ob ained o all o hem. Hence, in o de o pe o m an app op ia e
disc imina ion be ween he ou ne wo ks, he s a is ical signi icance
es based on Fishe ’s me hod desc ibed in Sec ion 3.3 has been applied.
The esul s ob ained ha e been abula ed in Table 4. A ending o he
s a is ical pa ame e s, i can be seen ha he numbe o expe imen s and
lumps is he same o all he ne wo ks, bu he numbe o pa ame e s
a ies ollowing he end: n
p,1
>n
p,3
>n
p,2
>n
p,4
. Consequen ly, he
deg ees o eedom o he di e en eac ion ne wo ks ollows jus he
opposi e o de . On he o he hand, he lowes alue o he sum o
squa ed e o s has been ob ained o scheme 3 (5.844 10
-3
), whe eas he
alues ob ained o he o he ne wo ks a e sligh ly highe and ollow he
end: SSE
2
<SSE
1
<SSE
4
. The e o e, since al e na i e eac ion ne wo k
4 is he simples one (less amoun o pa ame e s) and he wo s i ing
has been ob ained wi h i , his one has been aken as e e ence o he
s a is ical compa ison. Thus, i has been assessed i he addi ion o mo e
ca aly ic s eps is s a is ically signi ican . I has been ob ained ha F
4–1
<
F
1−
α
(0.841 <2.259), F
4–2
<F
1−
α
(1.569 <3.040) and F
4−3
<F
1−
α
(1.569 <2.649), meaning ha nei he pa en ne wo k no al e na i es 2
and 3 imp o ed in a s a is ically signi ican way he i ing o al e na i e
scheme 4.
4.3. Kine ic pa ame e s
Based on all he p e ious, he al e na i e eac ion ne wo k 4 has
been also used o he i ing o he da a ob ained wi h bo h ECAT-2 and
ECAT-3. The goodness o i has been e alua ed using pa i y plo s
Table 2
P ope ies o he comme cial FCC equilib ium ca alys s [44].
ECAT–1 ECAT–2 ECAT–3
USY zeoli e con en (w %) 13.8 21.0 11.8
Zeoli e UCS (Å) 24.26 24.23 24.27
Physical p ope ies
Appa en bulk densi y (g cm
-3
) 0.90 0.88 0.89
BET su ace a ea (m
2
g
-1
) 124 190 174
Mic opo e su ace a ea (m
2
g
-1
) 87 139 63
Mic opo e olume (cm
3
g
-1
) 0.04 0.06 0.03
Mesopo e su ace a ea (m
2
g
-1
) 37 50 111
Mesopo e olume (cm
3
g
-1
) 112 147 172
Acidic p ope ies
Acidi y (
μ
mol
NH3
g
-1
) 40 81 124
A e age acid s eng h (kJ mol
NH3-1
) 100 126 130
B øns ed/Lewis acid si es a io 0.66 0.91 1.56
Chemical composi ion
Al
2
O
3
(w %)
a
53.8 52.2 62.8
SiO
2
(w %) 38.5 44.0 35.1
SiO
2
/Al
2
O
3
a io 0.72 0.84 0.56
Cu (ppm) 24 66 10
Ni (ppm) 741 106 53
V (ppm) 3335 244 67
Fe (w %) 0.19 0.25 0.21
Na (w %) 0.29 0.26 0.19
P
2
O
5
(w %) 0.62 0.45 0.32
a e ea hs (w %) 2.50 0.86 1.35
a
Co esponding o he o al con en o alumina (in zeoli e and ma ix)
Table 3
Appa en kine ic pa ame e s a he e e ence empe a u e and ac i a ion en-
e gies o he eac ions in ol ed in he ca aly ic c acking o plas ic py olysis
waxes.
S ep Reac ion in ol ed k
j, 773 K
E
j d
– Deac i a ion, k
da
(3.2 ±0.2) 10
-2
136.0 ±7.1
1 HCO → LCO, k
1b
41.8 ±2.4 63.6 ±3.4
2 HCO → Naph ha, k
2b
14.4 ±0.8 86.6 ±4.1
3 HCO → LPG, k
3b
1.4 ±0.1 17.8 ±1.1
4 HCO → D y gas, k
4b
0.8 ±0.2 22.2 ±1.5
5 HCO → Coke, k
5b
2.4 ±0.1 112.9 ±5.4
6 LCO → Naph ha, k
6c
(3.5 ±0.2) 10
-4
96.2 ±4.8
7 LCO → LPG, k
7c
(3.8 ±0.8) 10
-3
63.2 ±3.3
8 LCO → D y gas, k
8c
(3.3 ±0.1) 10
-8
56.9 ±3.4
9 LCO → Coke, k
9c
(3.4 ±0.2) 10
-8
102.1 ±5.2
10 Naph ha → LPG, k
10c
(3.2 ±0.4) 10
-6
73.2 ±3.8
11 Naph ha → D y gas, k
11c
(2.6 ±0.4) 10
-6
49.8 ±2.5
12 Naph ha → Coke, k
12c
(2.8 ±0.6) 10
-9
140.6 ±7.7
13 LPG → D y gas, k
13c
(4.7 ±0.9) 10
-3
54.4 ±2.9
14 LPG → Coke, k
14c
(5.9 ±0.5) 10
-4
89.5 ±4.8
15 D y gas → Coke, k
15c
(1.6 ±0.1) 10
-2
130.1 ±6.4
The pa ame e s a e measu ed in:
a
s
-1
;
b
m
6
kg
ca -1
kmol
-1
s
-1
;
c
m
3
kg
ca -1
s
-1
;
d
kJ
mol
-1
Table 4
S a is ical compa ison o he ou kine ic ne wo ks.
S a is ical pa ame e Reac ion ne wo k
1 2 3 4
n
e
36 36 36 36
n
l
6 6 6 6
n
p
16 13 14 11
ν
200 203 202 205
SSE 5.851 10
-3
5.848 10
-3
5.844 10
-3
5.974 10
-3
F 0.841 (F
4–P
) 1.569 (F
4–2
) 1.569 (F
4–3
)
F
1-
α
2.259 3.040 2.649
R. Palos e al.
Fuel 316 (2022) 123341
6
(Fig. S1 in he Supplemen a y Ma e ial) by e alua ing he inal i o
calcula ed da a o he h ee ca alys s agains aw expe imen al da a. As
i can be seen, almos a pe ec i be ween he calcula ed and he
expe imen al weigh ac ion has been ob ained o all he ca alys s,
wi h he excep ion o he sca e ing o some poin s, especially o ECAT-
3. Ne e heless, hose de ia ions do no exceed he 5% as hey emain
inside he egion delimi ed by he dashed lines.
In Table 5 ha e been collec ed he alues compu ed o he appa en
kine ic pa ame e s and he ac i a ion ene gies o he kine ic s eps
in ol ed in he ca aly ic c acking o PPO by he h ee ca alys s. O e all,
small di e ences ha e been ob ained in he alues o he kine ic pa-
ame e s wi h all he ca alys s. These di e ences lie in he p ope ies o
he ca alys s, conside ing he e ec o he acidi y and po ous s uc u e
on he ac i i y, selec i i y and deac i a ion o he ca alys s [49]. This
way, ECAT-2 has he highes alue o he deac i a ion pa ame e
(0.030 s
-1
) because o i s mode a e mesopo e su ace a ea (50 m
2
g
-1
)
and mesopo e olume (147 cm
3
g
-1
), which a e no enough o easing he
di usion o coke p ecu so s owa ds he ex e nal su ace o ca alys
pa icles. Likewise, he con inemen o he p ecu so s will block he
mic opo es o he zeoli e esul ing in he ine ec i eness o i s high
con en o zeoli e [50]. I is well-es ablished he ole as coke p ecu so s
o ligh ole ins in c acking p ocesses, as hey unde go oligome iza ion,
a oma iza ion and condensa ion eac ions ha a e ca alyzed by s ong
acid si es [51,52]. In he same line, do s and ou he a e cons an s o he
eac ions ha o m coke om LPG and d y gas ac ions (2.8 10
-3
and 1.0
10
-4
m
3
kg
ca -1
s
-1
, espec i ely) using ECAT-2.
In con as , he lowe zeoli e/ma ix a io o ECAT-3 ha en ails a
highe mesopo e su ace a ea (111 m
2
g
-1
) and a highe mesopo e ol-
ume (172 cm
3
g
-1
), will imp o e he di usion o coke p ecu so s,
a enua ing hei con inemen and, consequen ly, he blockage o he
mic opo es. Mo eo e , he enhanced accessibili y and di usion o PPO
chains o he ac i e si es in ECAT-3 a e in conco dance wi h he high
alues o he kine ic pa ame e s o he eac ions ha con e he
componen s wi hin he HCO lump in o d y gases (1.16 m
6
kg
ca -1
kmol
-1
s
-1
) and he componen s wi hin he LCO lump in o naph ha (1.0 10
-3
m
3
kg
ca -1
s
-1
). The simila i ies among he es o he kine ic pa ame e s o
he di e en ca alys s lie in he syne gis ic and pa allel e ec s o he
po osi y and acidi y ha boos he ex en o he c acking eac ions.
The alues compu ed o he appa en ac i a ion ene gy o he
di e en ca aly ic s eps ha e been collec ed in Table 6. Unlike he ki-
ne ic pa ame e s (Table 5), signi ican di e ences a e obse ed be ween
he ac i a ion ene gy equi ed in some o he ca aly ic s eps o he
di e en ca alys s. Likewise, he ene gy ba ie ha mus be o e come
o he deac i a ion s ep is e y di e en depending on he ca alys used.
The lowe ac i a ion ene gy o he deac i a ion s age (79.2 kJ mol
-1
),
added o he high alue o he deac i a ion kine ic pa ame e ob ained
(3.0 10
-2
s
-1
in Table 5) expose he high endency o ECAT-2 o be
deac i a ed. Equally, he high amoun o acid si es on ECAT-3 explains
he low ac i a ion ene gy equi ed o he s eps o o ma ion o d y gas
om HCO and LPG lumps (17.1 and 40.0 kJ mol
-1
, espec i ely). In
addi ion, he high ma ix mesopo osi y o ECAT-3, which is he o he
key ea u e o he ca alys s, educes he ac i a ion ene gy o he s eps
limi ed by he di usi i y o he componen s. This way, his ca alys e-
duces he ene gy in ol ed in he s eps ha con e he HCO in LCO, LCO
in naph ha and LCO in LPG (60.5, 42.5 and 58.3 kJ mol
-1
, espec i ely),
as well as in he o ma ion o coke om LPG and d y gas (4.4 and 40.7
kJ mol
-1
, espec i ely).
4.4. Yields o p oduc s
The e olu ion o he yields o p oduc s wi h high comme cial in e es
as uels (LCO and naph ha) and wi h high con en o ole ins (LPG) has
been ob ained o he h ee ca alys s by compu ing he kine ic model
p e iously desc ibed and using he kine ic pa ame e s collec ed in Ta-
bles 5 and 6. One should no e ha he PPO ed o he eac o has a
con en o 12.5 w % o LCO and a 5.5 w % o naph ha, as i has been
p e iously de ailed in Sec ion 4.1. Those con en s ha e no been aken
in o accoun o depic ing he e olu ion o he yields, in o de o assess
he o ma ion o hese lumps in i s eal magni ude. On he o he hand, in
o de o ully unde s and he ob ained esul s, i should be aken in o
accoun ha con e sion has been de ined as he a io o mass o HCO
con e ed o ligh e p oduc s and o coke o he mass o HCO ed:
Con e sion =(mHCO)PPO − (mHCO)P oduc s
(mHCO)PPO
100 (12)
The yield o each i lump o p oduc s has been de ined as he mass o
lump i e e ed o he o al mass o lump HCO ed:
Yieldi=mi
mHCO
100 (13)
The e o e, Figs. 2-4 compa e he e olu ion wi h con e sion o he
yield o LCO, naph ha and LPG, espec i ely, ob ained wi h he h ee
ca alys s a di e en empe a u es. In a p e ious wo k [19] i has been
de ailed he composi ion o hese lumps, s essing ou he in e es o he
naph ha lump ( esea ch oc ane numbe up o 105) o being added o he
s eam o gasoline in e ine y. I is also ema kable he p opylene- ich
LPG lump p oduced.
The end o he cu es in Fig. 2 exposes he cha ac e o he LCO
lump as an in e media e in he eac ion ne wo k [53], as hey go
h ough a maximum a alues o con e sion o ca. 80 w %. Fu he mo e,
i can be seen ha high empe a u es p omo e he c acking eac ions
ha con e he molecules wi hin his lump in o ligh e molecules,
Table 5
Appa en kine ic pa ame e s a he e e ence empe a u e o he eac ions
in ol ed in he ca aly ic c acking o PPO o he h ee ca alys s.
S ep Reac ion k
i, 773 K
ECAT-1 ECAT-2 ECAT-3
– Deac i a ion, k
da
(2.4 ±0.2) 10
-
2
(3.0 ±0.2) 10
-
2
(2.3 ±0.2) 10
-
2
1 HCO → LCO, k
1b
41.1 ±1.4 42.8 ±1.8 41.5 ±1.0
2 HCO → Naph ha,
k
2b
14.3 ±1.1 14.7 ±1.5 14.7 ±1.7
3 HCO → LPG, k
3b
1.42 ±0.8 1.80 ±0.6 1.50 ±0.7
4 HCO → D y gas, k
4b
0.79 ±0.1 0.72 ±0.3 1.16 ±0.5
5 HCO → Coke, k
5b
2.08 ±0.1 2.10 ±0.2 2.02 ±0.2
6 LCO → Naph ha, k
6c
(2.4 ±0.4) 10
-
4
(4.5 ±0.3) 10
-
4
(1.0 ±0.1) 10
-
3
7 LCO → LPG, k
7c
(3.9 ±0.5) 10
-
3
(3.8 ±0.4) 10
-
3
(4.1 ±0.6) 10
-
3
13 LPG → D y gas, k
13c
(4.5 ±0.5) 10
-
3
(4.9 ±0.9) 10
-
3
(4.5 ±0.4) 10
-
3
14 LPG → Coke, k
14c
(1.7 ±0.2) 10
-
3
(2.8 ±0.7) 10
-
3
(1.1 ±0.3) 10
-
3
15 D y gas → Coke, k
15c
(1.9 ±0.1) 10
-
5
(1.2 ±0.3) 10
-
4
(4.7 ±0.6) 10
-
5
The pa ame e s a e measu ed in:
a
s
-1
;
b
m
6
kg
ca -1
kmol
-1
s
-1
;
c
m
3
kg
ca -1
s
-1
Table 6
Values o he appa en ac i a ion ene gy o he eac ions in ol ed in he ca a-
ly ic c acking o PPO o he h ee ca alys s.
S ep Reac ion E
i
(kJ mol
-1
)
ECAT-1 ECAT-2 ECAT-3
– Deac i a ion 163.2 ±8.0 79.2 ±3.8 120.3 ±5.9
1 HCO → LCO, E
1
65.3 ±3.4 72.8 ±3.4 60.5 ±2.7
2 HCO → Naph ha, E
2
97.3 ±4.8 96.2 ±4.0 89.4 ±4.1
3 HCO → LPG, E
3
17.7 ±1.0 18.4 ±2.0 16.6 ±1.3
4 HCO → D y gas, E
4
21.5 ±1.1 17.1 ±1.4 26.8 ±1.0
5 HCO → Coke, E
5
125.9 ±6.3 133.0 ±6.6 129.0 ±6.0
6 LCO → Naph ha, E
6
122.5 ±6.0 83.9 ±4.8 42.5 ±2.6
7 LCO → LPG, E
7
63.9 ±3.3 69.4 ±5.5 58.3 ±3.1
13 LPG → D y gas, E
13
57.4 ±2.9 40.0 ±3.5 72.9 ±4.0
14 LPG → Coke, E
14
31.8 ±1.4 27.3 ±1.4 4.4 ±0.5
15 D y gas → Coke, E
15
105.2 ±5.2 91.7 ±4.8 40.7 ±2.1
R. Palos e al.
Fuel 316 (2022) 123341
7
Fig. 2. Model p edic ion (lines) and expe imen al da a (symbols) o he e olu ion o he LCO yield wi h he le el o con e sion o he h ee ca alys s.
Fig. 3. Model p edic ion (lines) and expe imen al da a (symbols) o he e olu ion o he naph ha yield wi h he le el o con e sion o he h ee ca alys s.
Fig. 4. Model p edic ion (lines) and expe imen al da a (symbols) o he e olu ion o he LPG yield wi h he le el o con e sion o he h ee ca alys s.
R. Palos e al.
Fuel 316 (2022) 123341
8
esul ing in lowe yields o LCO. Compa ing he esul s ob ained wi h
he h ee ca alys s, simila i ies a e obse ed be ween he esul s ob-
ained. This way, wi h ECAT-1 and ECAT-2 highe alues han wi h
ECAT-3 a e ob ained, yielding up o 46.5 w % wi h he o me ca alys s
a 500 ◦C.
A ending o he e olu ion o he yields o naph ha and LPG lumps
(Figs. 3 and 4, espec i ely), bo h a e end-p oduc s in he eac ion
ne wo k since hei yield inc eases con inuously wi h he ex en o
con e sion. None heless, in spi e o he e olu ion ob ained o LPG lump
(Fig. 4), he molecules wi hin his lump a e c acked o d y gas and
condensed o coke as i has been p e iously ob ained in he eac ion
ne wo k (Fig. 1d). Wi h ega d o he e olu ion o he yield o naph ha
(Fig. 3), high empe a u es p omo e he p oduc ion o his lump, since
he c acking o molecules wi hin HCO and LCO lumps is boos ed.
Fu he mo e, highe yields o naph ha ha e been ob ained wi h ECAT-3,
yielding up o 33.6 w % a 560 ◦C. Howe e , he maximum alues ob-
ained wi h ECAT-2 and ECAT-1 ha e been sligh ly in e io s (31.1 and
29.6 w %, espec i ely).
The e olu ion o he di e en yields (Figs. 2-4) s ongly depends on
he p ope ies o he ca alys used (Table 2) and can be co ela ed wi h
he alues o he appa en kine ic pa ame e s epo ed on Table 5. This
way, ECAT-3 is by a he ca alys wi h he highes and s onges acidi y
(124
μ
mol
NH3
g
−1
and 130 kJ mol
NH3-1
, espec i ely), which u ns in o
he ca alys wi h he highes c acking ac i i y. Mo eo e , i is he ca a-
lys wi h he highes mesopo osi y ha eases he access o he bulky
molecules wi hin he HCO and LCO lumps o he acid si es loca ed in he
inside o he po ous s uc u e o he ca alys . The e o e, he highes
yields o naph ha and LPG, oge he wi h he lowes yield o LCO should
be expec ed using his ca alys .
E en hough ECAT-2 possesses a lowe amoun o acid si es a ailable
(81
μ
mol
NH3
g
−1
), hei s eng h is qui e ema kable (126 kJ mol
NH3-1
)
making a p io i his ca alys a se ious candida e o maximizing he yield
o naph ha and LPG lumps. Howe e , i s mic opo ous na u e and i s,
subsequen , sho ness in mesopo es a e unsui able o boos ing he ac-
cess o he hea y molecules o inne acid si es. Consequen ly, he
beha io o ECAT-2 is only compa able wi h ECAT-3 a 560 ◦C as an
inc ease in empe a u e inc eases he di usi i y [54]. None heless,
ECAT-2 p omo es he o ma ion o LPG ins ead o naph ha, which can be
a ibu ed o he o e c acking eac ion ha akes place wi hin he mi-
c opo es o he zeoli e as a consequence o he highe esidence ime o
he eac an s. I s low con en o a e ea hs will also p esumably
con ibu e o ob ain he a o emen ioned esul s [46]. Fu he mo e, he
na owe po ous s uc u e o ECAT-2 will lead o a as e ac i i y decay
o he ca alys .
Finally, he con igu a ion and composi ion o ECAT-1 a e he less
a o able ones o p omo e he c acking eac ions. Indeed, ECAT-1 has
he lowes supe icial a ea (124 m
2
g
−1
), he lowes acidi y (40
μ
mol
NH3
g
−1
) and he weakes acid s eng h (100 kJ mol
NH3-1
). In addi ion, he
high concen a ion o impu i y me als de ec ed on ECAT-1, especially o
anadium (3335 ppm), will also con ibu e o de e io a e he p ope ies
o he ca alys . Consequen ly, sligh ly lowe yields o bo h naph ha and
LPG lumps (Figs. 3 and 4) ha e been ob ained wi h ECAT-1.
4.5. Selec i i y o p oduc s
The selec i i y o each lump i has been de ined as he mass o lump i
o med espec o ha o all he p oduc s:
Selec i i yi=mi
mLCO +mNaph ha +mLPG +mD yGas +mCoke
100 (14)
Taking in o accoun ha naph ha and LPG lumps a e he ones wi h
he highes comme cial in e es , he e olu ion wi h con e sion o he
selec i i y o hem has been depic ed in Fig. 5. O e all, i can be seen
how di e en he selec i i y o each lump is. This way, he selec i i y o
naph ha lump is ba ely a ec ed by he ex en o con e sion. The end
ollowed by he selec i i y o naph ha cu es depends on he ca alys .
This way, i can be seen ha wi h ECAT-1, which is he less ac i e ca -
alys s, he selec i i y o naph ha emains almos s eady o alues o
con e sion below 80%, o inc ease exponen ially a highe alues. Fo
ECAT-3, in u n, he g ow h can be no iced o alues o con e sion
abo e 55%. Fu he mo e, he di e ences be ween he pe o mances o
he ca alys s a e mo e e iden a high empe a u es and high alues o
con e sion. This way, he selec i i y o naph ha has been maximized a
560 ◦C wi h ECAT-3 eaching a alue o 35.8 w %, whe eas unde he
same condi ions a selec i i y o 31.5 w % has been ob ained wi h ECAT-
1. ECAT-2, in u n, o e s an in e media e esul and a selec i i y o
naph ha o 32.8 w %.
In con as , selec i i y o LPG lump g ows exponen ially wi h con-
e sion since he e y beginning o he eac ion. The e ec o he em-
pe a u e is less ma ked bu he opposi e in he case o he LPG. Likewise,
an inc ease om 500 o 560 ◦C o a ixed alue o con e sion en ails jus
a educ ion o he selec i i y o LPG o ca. 2.5 w %. Focusing on he
pe o mance o he ca alys s, ECAT-2 o e s he highes selec i i y a
560 ◦C bu also he lowes a 530 and 500 ◦C. This esul is cha ac e is ic
o a pa ially deac i a ed ca alys , in which he mal c acking plays a
mo e impo an ole ha in he case o ECAT-1 and ECAT-3.
Fig. 5. Model p edic ion o he e olu ion o he selec i i y o naph ha (dashed lines) and o LPG (solid lines) lumps wi h he le el o con e sion o he
h ee ca alys s.
R. Palos e al.
Fuel 316 (2022) 123341
9
A ending o he esul s collec ed on Figs. 2-5, ope a ing unde he
condi ions ha allow o eaching con e sions le els wi hin he ange
60–80% would be he op imal conside ing he possibili y o a ying he
eac ion empe a u e be ween 500 and 560 ◦C. This way, he con e sion
o HCO would be p omo ed keeping unde con ol he o e c acking
eac ions ha would lead o ob ain oo much d y gas. Fu he mo e,
ECAT-3 should be he selec ed one o u ning he p oduc ion o LPG and
naph ha lumps, whe eas ECAT-1 and ECAT-2 would inc ease he yield o
LCO lump in de imen o he yield o naph ha.
4.6. Ca alys deac i a ion
Since ca alys deac i a ion has a no able impac on he esul s
collec ed in Sec ions 4.4 and 4.5 abou he yields and selec i i y, he
e olu ion o he ac i i y e m (φ) o he h ee ca alys s wi h con ac ime
a 500 ◦C has been plo ed on Fig. 6. One should no e ha hese cu es
ha e been ob ained by applying he p e iously p oposed deac i a ion
equa ion (Eq. (7)) and using he co esponding kine ic pa ame e s (Ta-
bles 5 and 6). I can be seen ha o a con ac ime o 6 s, all he ca alys s
main ain good ac i i y le els as hey a e abo e o he 83% o he ini ial
ac i i y. This esul is e y di e en o ha ob ained in he c acking o
VGO (benchma k eed in FCC) [55], whe e he ca alys was o ally
deac i a ed. This esul exposes he c ucial ole ha he composi ion o
he s eam ed o c acking eac o plays in ca alys deac i a ion and,
he e o e, in p oduc s yield and dis ibu ion. This way, he he e oge-
nei y o he VGO, wi h high con en s o a oma ics and he p esence o
polya oma ics, is mo e p one o he o ma ion o coke han he ole ins
ha p edomina e in he composi ion o he PPO [43]. This low deac i-
a ion is an in e es ing esul o adop ing di e en c acking s a egies
o he PPO, such as being co- ed wi h o he e ine y s eams ha
deac i a e he ca alys s in a la ge ex en .
Compa ing he e olu ion ollowed by he ca alys s, ECAT-1 and
ECAT-3 show almos iden ical cu es o ac i i y s. ime as a di e ence
o <1% o a con ac ime o 6 s (ca. 87%) has been ob ained. Howe e ,
ECAT-2 su e s om a highe and mo e se e e ac i i y decay since he
e y beginning o he eac ion. Indeed, he inal alue o ac i i y ob-
ained o his la e ca alys is o 83.5%. Undoub edly, he deac i a ion
su e ed by ECAT-2 lies in he po ous s uc u e o he ca alys , which is
by a mo e mic opo ous (Table 2) han he s uc u e o he o he ca -
alys s. Consequen ly, he coke o med du ing he eac ion will mo e
easily block he channels o he zeoli e educing he accessibili y o
hyd oca bon species o he ca alys inne mic opo e ne wo k [56].
To o e ano he pe spec i e o he deac i a ion esul s, Fig. 7 depic s
he e olu ion o he ac i i y o he h ee ca alys s wi h he con en o
coke deposi ed. Clea ly, he amoun o coke deposi ed on ECAT-2 is
highe han ha deposi ed on ECAT-1 o ECAT-3. Consequen ly, ECAT-2
su e s om a highe ac i i y decay han he o he ca alys s. In spi e o
ha , a ending o he accele a ed dec ease o he ac i i y ob ained o all
he ca alys s, i can be concluded ha he deac i a ion mechanism is
highly a ec ed by he mic opo e blocking caused by coke deposi ion.
This phenomenon will also es ic he access o he eac an s o he acid
si es loca ed in he inne c ys als o he zeoli e. This esul is in
conco dance wi h he hypo hesis o he key ole o he ma ix mesopo es
o a enua ing he ca alys deac i a ion by delaying he a o emen ioned
phenomenon.
5. Conclusions
A lumped kine ic modeling me hod has been applied o he expe i-
men al da a o he ca aly ic c acking o plas ic py olysis oil (PPO) o e
h ee comme cial FCC equilib ium ca alys s. By means o a s a is ical
da a analysis, i has been ob ained ha om he ou di e en eac ion
ne wo ks p oposed, he simples one was he mos app op ia e o
desc ibing he p ocess. F om he kine ic pa ame e s ob ained in he
i ing o he esul s, i has been ob ained ha bo h o al acidi y and acid
Fig. 6. Model p edic ion o he e olu ion o he ca alys s ac i i y wi h con ac
ime a 500
◦C.
Fig. 7. Model p edic ion o he e olu ion o he ca alys ac i i y wi h he con en o coke deposi ed on he h ee ca alys s.
R. Palos e al.
