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Volume 6 | Issue 2 | 118
Petro Chem Indus Intern, 2023
Citation: Raheem, A, B., Edeh, I. (2023). Process Simulation of Terephthalic Acid Using Neutral Hydrolysis of Polyethylene
Terephthalic Bottle Waste Method. Petro Chem Indus Intern, 6(2), 118-130.
Process Simulation of Terephthalic Acid Using Neutral Hydrolysis of Polyethylene
Terephthalate Bottle Waste Method
*Corresponding Author
Ademola Bolanle Raheem, Chemical Engineering Department, Faculty
of Engineering, University of Port Harcourt, P.M.B. 5323, Choba, Port
Harcourt, Rivers State, Nigeria.
Submitted: 18 Apr 2022; Accepted: 22 Apr 2023; Published: 30 Apr 2023
Petroleum and Chemical Industry International
Ademola Bolanle Raheem1* and Ifeanyichukwu Edeh2
1* Chemical Engineering Department, Faculty of Engineering,
University of Port Harcourt, P.M.B. 5323, Choba, Port
Harcourt, Rivers State, Nigeria.
2Department of Chemical Engineering, University of Port
Harcourt, Rivers State, Nigeria.
Research Article
Abstract
To mitigate the environment's unique challenges caused by polyethylene terephthalate [PET] bottle litter and to protect
the petroleum feedstock. The chemical recycling technology was used to transform PET into practical items with a siz-
able and successful industrial application. In order to model the chemical neutral hydrolysis depolymerization process
of PET plastic wastes utilizing a continuous stir tank reactor for the synthesis of pure terephthalic acid [TPA] and EG
for commercial use, this work used ASPEN PLUS V10. The data for the modeling came from an experimental chemical
recycling project employing the neutral hydrolysis process to depolymerize PET bottle trash. PET waste was degraded
using excess water [H2O] and zinc acetate [Zn [Ac]2] as the active catalyst. A mean PET particle size of 127.5 m, 1000
kg/h of PET depolymerized at an H2O: PET [w/w] ratio of 8:1, 513.15 K temperature, 32.0 bar pressure, and 0.5 h
residence time were the reaction's ideal working parameters. Regarding PET, it is a rst-order reaction. The reaction
yielded 782.72 kg/h of TPA, 292.43 kg/h of EG, and a depolymerization of PET of 90.54%. TPA and EG had selectivity of
0.7280 and 0.2720, respectively. Filtration, distillation, and crystallization techniques were used to separate the mixture
of components. The heat from the conveyance, reaction, and separation processes was obtained. This eort increased
the yield of TPA, the amount of water removed for reuse, the amount of EG generated, and the amount of processing heat
required. The procedures and their operating circumstances can be used to scale up commercial processes in the future.
ISSN: 2639-7536
Introduction
PET plastic is a cost-eective and long-lasting polymer that
is used in a variety of products, including packaging, bottles,
straws, bags, and much more, which keeps the plastic production
and disposal cycle going nonstop. Due to increased urbanization,
there is an increase in global population demand for extra PET
bottle plastic use. PET bottles for soft drinks and water have a
very short shelf life. They lack enough worth to be kept since
they are so cheap and because their disposal is done improperly.
They end up in landlls instead.
The production of PET packaging bottles has increased as a re-
sult of these products' attributes, which include good mechanical
properties, ease of manipulation to fabricate any shape or prod-
uct of interest, breadth of their products, and future promise in
research for more products, combined with daily new innovation
[1].
PET bottle trash is readily thrown out and is allowed to clog
gutters and drains and leave behind litter everywhere. Due to
its non-biodegradability and the potential for very slow disin-
tegration caused by photochemical reactions, electrolyte corro-
sion, hydrolysis, microbes, and other factors. It builds up over
time and becomes a signicant environmental issue globally
[2]. Since the emergence of various environmental campaigns
in recent years, the success of its industries in facilitating simple
access to their products for consumption and preventing dam-
age through the use of PET bottles with many superb functional
properties has become a liability or problem for the industries
to solve [3].
A signicant amount of garbage is produced with limited PET
recycling capabilities as a result of the expanding population,
together with advancements in technology and PET bottle deliv-
ery services. Media studies indicate that plastic bottles disinte-
grate between 70 and 450 years old, demonstrating that plastics
do not quickly biodegrade [4,5]. Another goal is to nd a way
to modernize, enhance, and develop PET bottle trash disposal
techniques. This is necessary to meet the vision and insight that
these practices must be environmentally sound and sustainable.
To address the diculties caused by plastics, particularly PET,
in the ocean and ecosystem, some researchers have acted. Ac-
cording to, just 9% of the 6,300 metric tons of plastic waste pro-
duced in 2015 was recycled, and 12% was burned. Instead, it
was disposed of in landlls or the environment. If production
Volume 6 | Issue 2 | 119
Petro Chem Indus Intern, 2023
and waste management trends continue, by 2050 there will be
around 12,000 metric tons of plastic waste in landlls or the en-
vironment [6]. The latest method used in managing PET bottle
waste is recycling. The method itself has many issues if the right
sub-method is not used and not handled properly [7].
The main issue with recycling is that it can only transform pure,
uncontaminated plastic trash of one type back into its original
shape during production. The issue of plastic trash at the dispos-
al location is thus not addressed [8]. Only monolayer plastics are
allowed for secondary [mechanical] recycling, which harms the
environment and physically damages products. Additionally, did
a study on the production of PET akes and the mechanical recy-
cling process [9]. The only byproducts of pyrolysis and gasica-
tion [tertiary recycling] that have undergone extensive research
are gas and liquid fuel. Applying LCA allowed for the pyrolysis
of PET bottle trash [10]. Enzymolysis [tertiary recycling by bio-
degradation] is a time-consuming process that can only partially
decompose PET bottle waste. Solvolysis, or tertiary recycling
via chemical depolymerization, is expensive, detrimental to the
environment, and dicult to separate the end product. Recycling
from the Quaternary recover’s energy along with CO2 emissions
and other priceless materials. Recovering PET monomers is not
covered by it [11].
There are several dierent types of hydrolysis for chemical re-
covery, including neutral, acid, and alkaline hydrolysis; alcohol-
ics; aminolysis; glycolysis; and ammonolysis [12-16]. The steps
of hydrolysis, alcoholics, and glycolysis convert PET bottle
trash into TPA. In order to discover strategies to make PET bot-
tle waste digestion into TPA innovative and industrially viable
at a reasonable low cost of production, PET bottle waste was
solvolyzed [chemically recycled] in this study. A straightforward
and eective separation technique was developed thanks to the
planning, modeling, and simulation of the process. The life cy-
cle inventory of recycling PET bottle waste into TPA was estab-
lished to be used later. Quantications of materials and energy
oer hope for future research on environmental and economic
implications. Through planning, modeling, and process simula-
tion, a simple and ecient separation technique was created. It
was designed to be utilized later to create a life cycle inventory
of the recycled PET bottle waste converted into TPA. Further
study of the eects on the environment and the economy can be
found in the quantication of materials and energy.
PET bottle waste-neutral hydrolysis design, modeling, and
simulation [DMS] using Aspen Plus with the Aspen Polymer
feature.
In a reaction vessel developed and modeled by CSTR, PET [the
reactant], H2O [the reactant and solvent], and Zinc Acetate [the
catalyst] ow into the reactor while the product[s] of the reac-
tion simultaneously exit the vessel. By allowing input and out-
put streams to ow continuously, it becomes an eective tool
for continuous chemical processing. It has a tank reactor, feed
and exit pipes, an embedded impeller, and is meant to handle an
extremely viscous PET material. To ensure that the reactants are
thoroughly mixed, enough room should be provided to create a
vortex. Given that PET is a solid material, it was chosen for its
well-known capacity for scaling up and excellence in robust sol-
id handling. Residence time distribution control is enhanced by
CSTR cascades' pseudo-plug ow characteristics, because they
have better heat transmission capabilities. It is a possible option
for PET and superheated water reactions, which need extremely
high temperatures. Additionally, they have greater resistance to
stronger reactions and higher reagent concentrations. They can
operate for extended periods of time and produce large volumes
of product per unit of time, making them ideal for reactions with
fast kinetics. They have greater conversion per unit mass of cata-
lyst than other catalytic reactors, as well as lower operating costs
and continuous operation. The amount of zinc acetate utilized
demonstrates this. It runs in a steady state with a constant ow
of reactants and products, and the feed adopts a uniform compo-
sition throughout the reactor. The exit stream also has the same
composition as the material in the tank. Heat may be removed
from the reaction mixture more quickly and eciently using
CSTRs than batch reactors because they have better heat transfer
characteristics. This can speed up reaction times and reduce the
chance of overheating. Continuous stirred-tank reactors are used
most frequently in homogeneous liquid-phase ow operations
in industrial processing where continuous agitation is required,
such as in the polymer [PET] industry. They can be utilized
alone, sequentially, or as a component of a battery. As the control
aim of CSTR, the temperature of the reacting mixture, T, should
remain constant at the appropriate value. The only variable that
can be altered is the coolant's temperature. Both the temperature
control system and the method used by CSTR are innovative
and logically constructed. They are favorable for energy savings
and consumption reduction because of their quick control speed,
high control precision, high heat exchange eciency, and low
heat-carrying agent consumption. They are very easy to utilize
and put into practice. It is used in the chemical industry to make
mixes with similar chemical compositions at the input and out-
put and to assure perfect mixing of materials that are continuous-
ly supplied into the reactor.
DMS of PET bottle waste neutral hydrolysis depolymeriza-
tion process
In its DMS processing, information from the PET bottle waste
neutral hydrolysis depolymerization experimental study was
employed. The Aspen Plus with Polymer feature's CSTR used
for the reaction component had all of its reaction modeling equa-
tions pre-built in the program. Due to the eectiveness of the
software, the component properties have a tolerance of 0.001.
Table 1 displays data from the PET neutral hydrolysis depolym-
erization experiment and CSTR.
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Petro Chem Indus Intern, 2023
Table 1: PET neutral hydrolysis and depolymerization reaction operating conditions
Operating conditions Values Units
H2O : PET 8:1
Temperature 513.15 K
Pressure 32.0 bar
Residence time 0.5 h
Catalyst /PET (w/w) ratio
[Zn(Ac)2 : PET]
1:67
Total reactor volume, Vt242.0525 m3
Total reactor actual volume, Va266.2578 m3
Order of reaction 1st order Based on PET
Reaction rate constant, k 23.0259 s-1 (or sec-1)
Activation energy (Ea) 80.94 kJ/mole
The simulation was done based on the computational ow diagram [CFD] shown in Figures 1[a-d] below:
Figure 1a: Process ow diagram of neutral hydrolysis of polyethylene terephthalate bottles waste chemical recycling into tereph-
thalic acid
Figure 1b: Process ow diagram of neutral hydrolysis of polyethylene terephthalate bottles waste chemical recycling into tereph-
thalic acid
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Petro Chem Indus Intern, 2023
Figure 1c: Process ow diagram of neutral hydrolysis of polyethylene terephthalate bottles waste chemical recycling into tereph-
thalic acid
Figure 1d: Process ow diagram of neutral hydrolysis of polyethylene terephthalate bottles waste chemical recycling into tereph-
thalic acid
PET neutral hydrolysis depolymerization chemical reaction
model
A kinetic Segment-based power law reaction model was used in
the simulation of PET neutral hydrolysis chemical recycling into
TPA, which is consistent with research on that simulated and
measure the recovery eciency of copper in leaching process of
copper oxide in H2SO4 solution CSTR in Aspen Plus. As stated
in the following equation (1), a power law representation of the
molarity concentration basis [Ci] was utilized [17].
5
solution CSTR in Aspen Plus. As stated in the following equation (1), a power law representation of the
molarity concentration basis (Ci) was utilized.
(1)
If the reference temperature To is not stated, the above equation (1) is appropriate. Otherwise, if a
reference temperature To is supplied, the equation (2) below is appropriate.
(2)
Where T is temperature in degrees K, To is reference temperature in degrees K, r is reaction rate, and n
is the exponential factor, Ea stands for activation energy, R for the universal gas law constant, C for molarity
(kg mol/m3), i for component index, and Π for the product operator. Relevant and suitable models can also be
developed for the work, as was done by Castillo Gonzalez et al., (2020), who developed mathematical models
for continuous biodiesel reactors that can be used for economic analysis of supply changes in continuous
processes of biodiesel.
It should be noted that the first order reaction involving the digestion of PET is the depolymerization of
PET utilizing H2O to generate TPA. PET conversion was 90.54%, TPA (monomer) yield was 90.54%, and
selectivity was 0.7280. The EG yield and selectivity were 90.54% and 0.27, respectively. In Eq. (3), the reaction
route is illustrated.
3. Chemical Recycling of PET Bottles Waste Using Neutral Hydrolysis Method: Process Design,
Modeling, and Simulation Procedure.
To model the chemical depolymerization of PET into TPA using the neutral hydrolysis method,
experimental data from the (Liu et al., 2012). PET bottle waste neutral hydrolysis digesting into TPA work was
used. The Aspen Plus v10 with polymer function was utilized for CSTR with agitation. Table 1 above displays
the data that was used.
3.1 Neutral Hydrolysis of PET Bottles Waste Process Description
This project's basis is a 1000 kg/h PET waste bottle. Simulation and modeling were done using Figures
1(a)–(d). In Feed 1, PET powder and water were mixed in a 1:1 mass ratio at 298.15 K and 1.01325 bar at
ambient operating conditions. The transport medium for PET was water. Pump 1 was operating at 33.00 bars,
and heater 1 was operating at 513.15 K to move it into reactor 1. 7000 kg/h of feedwater (feed 2) was carried
into reactor 1 by pump 2 running at 33.00 bars, through heater 2 (pre-heating), which heated the water to 513.15
K. In reactor 1, the mass proportion of water to PET was 8:1. Water was overly present to encourage PET's full
conversion to TPA and the TPA product's better selectivity over EG.
The input at Reactor 1 (the CSTR reactor) was a mixture of 1000 kg/h of PET and 8000 kg/h of water
at a temperature and pressure of 513.15 K and 33.00 bar, respectively. 266.257792 m3 was its volume, and it
operated at 513.15 K and 32.00 bar pressure. Data and operating parameters for reactor 1's depolymerisation of
PET into TPA were already displayed in Table 1 above. As previously noted, a kinetic segment-based power
law reaction model was employed, and it was based on Equations 1 and 2 for the power law expression of
molarity concentration basis (Ci) displayed in Equations 1 and 2. The findings of reactor 1's (CSTR)
degradation of PET bottle trash into TPA are displayed in Table 4 below.
.
Filter 1 received the reactor 1 product mixture at a higher pressure of 32.00 bar. Filter 1 filtered out
0.0263 kg/sec of solid, unreacted PET as filtrate while operating at 1.01325 bar and 513.15 K. Pump 3 sent it to
the purification or treatment area for additional purification before reuse (recycling) or sale while running at
2.0265 bar.
Pump 10, operating at 2.0265 bar through cooler 2, transferred the output of Filter 1's filtration stream
of 2.1751 kg/sec of water, 0.0812 kg/sec of EG, and 0.2174 kg/sec of TPA at 513.15 k and 1.01325 bar into
If the reference temperature To is not stated, the above equation (1) is appropriate. Otherwise, if a reference temperature To is sup-
plied, the equation (2) below is appropriate.
5
solution CSTR in Aspen Plus. As stated in the following equation (1), a power law representation of the
molarity concentration basis (Ci) was utilized.
(1)
If the reference temperature To is not stated, the above equation (1) is appropriate. Otherwise, if a
reference temperature To is supplied, the equation (2) below is appropriate.
(2)
Where T is temperature in degrees K, To is reference temperature in degrees K, r is reaction rate, and n
is the exponential factor, Ea stands for activation energy, R for the universal gas law constant, C for molarity
(kg mol/m3), i for component index, and Π for the product operator. Relevant and suitable models can also be
developed for the work, as was done by Castillo Gonzalez et al., (2020), who developed mathematical models
for continuous biodiesel reactors that can be used for economic analysis of supply changes in continuous
processes of biodiesel.
It should be noted that the first order reaction involving the digestion of PET is the depolymerization of
PET utilizing H2O to generate TPA. PET conversion was 90.54%, TPA (monomer) yield was 90.54%, and
selectivity was 0.7280. The EG yield and selectivity were 90.54% and 0.27, respectively. In Eq. (3), the reaction
route is illustrated.
3. Chemical Recycling of PET Bottles Waste Using Neutral Hydrolysis Method: Process Design,
Modeling, and Simulation Procedure.
To model the chemical depolymerization of PET into TPA using the neutral hydrolysis method,
experimental data from the (Liu et al., 2012). PET bottle waste neutral hydrolysis digesting into TPA work was
used. The Aspen Plus v10 with polymer function was utilized for CSTR with agitation. Table 1 above displays
the data that was used.
3.1 Neutral Hydrolysis of PET Bottles Waste Process Description
This project's basis is a 1000 kg/h PET waste bottle. Simulation and modeling were done using Figures
1(a)–(d). In Feed 1, PET powder and water were mixed in a 1:1 mass ratio at 298.15 K and 1.01325 bar at
ambient operating conditions. The transport medium for PET was water. Pump 1 was operating at 33.00 bars,
and heater 1 was operating at 513.15 K to move it into reactor 1. 7000 kg/h of feedwater (feed 2) was carried
into reactor 1 by pump 2 running at 33.00 bars, through heater 2 (pre-heating), which heated the water to 513.15
K. In reactor 1, the mass proportion of water to PET was 8:1. Water was overly present to encourage PET's full
conversion to TPA and the TPA product's better selectivity over EG.
The input at Reactor 1 (the CSTR reactor) was a mixture of 1000 kg/h of PET and 8000 kg/h of water
at a temperature and pressure of 513.15 K and 33.00 bar, respectively. 266.257792 m3 was its volume, and it
operated at 513.15 K and 32.00 bar pressure. Data and operating parameters for reactor 1's depolymerisation of
PET into TPA were already displayed in Table 1 above. As previously noted, a kinetic segment-based power
law reaction model was employed, and it was based on Equations 1 and 2 for the power law expression of
molarity concentration basis (Ci) displayed in Equations 1 and 2. The findings of reactor 1's (CSTR)
degradation of PET bottle trash into TPA are displayed in Table 4 below.
.
Filter 1 received the reactor 1 product mixture at a higher pressure of 32.00 bar. Filter 1 filtered out
0.0263 kg/sec of solid, unreacted PET as filtrate while operating at 1.01325 bar and 513.15 K. Pump 3 sent it to
the purification or treatment area for additional purification before reuse (recycling) or sale while running at
2.0265 bar.
Pump 10, operating at 2.0265 bar through cooler 2, transferred the output of Filter 1's filtration stream
of 2.1751 kg/sec of water, 0.0812 kg/sec of EG, and 0.2174 kg/sec of TPA at 513.15 k and 1.01325 bar into
Where T is temperature in degrees K, To is reference tempera-
ture in degrees K, r is reaction rate, and n is the exponential
factor, Ea stands for activation energy, R for the universal gas
law constant, C for molarity [kg mol/m3], i for component index,
and Π for the product operator. Relevant and suitable models can
also be developed for the work, as was done by, who developed
mathematical models for continuous biodiesel reactors that can
be used for economic analysis of supply changes in continuous
processes of biodiesel [18].
It should be noted that the rst order reaction involving the di-
gestion of PET is the depolymerization of PET utilizing H2O
to generate TPA. PET conversion was 90.54%, TPA [monomer]
yield was 90.54%, and selectivity was 0.7280. The EG yield and
selectivity were 90.54% and 0.27, respectively. In Eq. (3), the
reaction route is illustrated.
5
solution CSTR in Aspen Plus. As stated in the following equation (1), a power law representation of the
molarity concentration basis (Ci) was utilized.
(1)
If the reference temperature To is not stated, the above equation (1) is appropriate. Otherwise, if a
reference temperature To is supplied, the equation (2) below is appropriate.
(2)
Where T is temperature in degrees K, To is reference temperature in degrees K, r is reaction rate, and n
is the exponential factor, Ea stands for activation energy, R for the universal gas law constant, C for molarity
(kg mol/m3), i for component index, and Π for the product operator. Relevant and suitable models can also be
developed for the work, as was done by Castillo Gonzalez et al., (2020), who developed mathematical models
for continuous biodiesel reactors that can be used for economic analysis of supply changes in continuous
processes of biodiesel.
It should be noted that the first order reaction involving the digestion of PET is the depolymerization of
PET utilizing H2O to generate TPA. PET conversion was 90.54%, TPA (monomer) yield was 90.54%, and
selectivity was 0.7280. The EG yield and selectivity were 90.54% and 0.27, respectively. In Eq. (3), the reaction
route is illustrated.
3. Chemical Recycling of PET Bottles Waste Using Neutral Hydrolysis Method: Process Design,
Modeling, and Simulation Procedure.
To model the chemical depolymerization of PET into TPA using the neutral hydrolysis method,
experimental data from the (Liu et al., 2012). PET bottle waste neutral hydrolysis digesting into TPA work was
used. The Aspen Plus v10 with polymer function was utilized for CSTR with agitation. Table 1 above displays
the data that was used.
3.1 Neutral Hydrolysis of PET Bottles Waste Process Description
This project's basis is a 1000 kg/h PET waste bottle. Simulation and modeling were done using Figures
1(a)–(d). In Feed 1, PET powder and water were mixed in a 1:1 mass ratio at 298.15 K and 1.01325 bar at
ambient operating conditions. The transport medium for PET was water. Pump 1 was operating at 33.00 bars,
and heater 1 was operating at 513.15 K to move it into reactor 1. 7000 kg/h of feedwater (feed 2) was carried
into reactor 1 by pump 2 running at 33.00 bars, through heater 2 (pre-heating), which heated the water to 513.15
K. In reactor 1, the mass proportion of water to PET was 8:1. Water was overly present to encourage PET's full
conversion to TPA and the TPA product's better selectivity over EG.
The input at Reactor 1 (the CSTR reactor) was a mixture of 1000 kg/h of PET and 8000 kg/h of water
at a temperature and pressure of 513.15 K and 33.00 bar, respectively. 266.257792 m3 was its volume, and it
operated at 513.15 K and 32.00 bar pressure. Data and operating parameters for reactor 1's depolymerisation of
PET into TPA were already displayed in Table 1 above. As previously noted, a kinetic segment-based power
law reaction model was employed, and it was based on Equations 1 and 2 for the power law expression of
molarity concentration basis (Ci) displayed in Equations 1 and 2. The findings of reactor 1's (CSTR)
degradation of PET bottle trash into TPA are displayed in Table 4 below.
.
Filter 1 received the reactor 1 product mixture at a higher pressure of 32.00 bar. Filter 1 filtered out
0.0263 kg/sec of solid, unreacted PET as filtrate while operating at 1.01325 bar and 513.15 K. Pump 3 sent it to
the purification or treatment area for additional purification before reuse (recycling) or sale while running at
2.0265 bar.
Pump 10, operating at 2.0265 bar through cooler 2, transferred the output of Filter 1's filtration stream
of 2.1751 kg/sec of water, 0.0812 kg/sec of EG, and 0.2174 kg/sec of TPA at 513.15 k and 1.01325 bar into
Volume 6 | Issue 2 | 122
Petro Chem Indus Intern, 2023
Chemical Recycling of PET Bottles Waste Using Neutral Hy-
drolysis Method: Process Design, Modeling, and Simulation
Procedure.
To model the chemical depolymerization of PET into TPA using
the neutral hydrolysis method, experimental data from the [19].
PET bottle waste neutral hydrolysis digesting into TPA work
was used. The Aspen Plus v10 with polymer function was uti-
lized for CSTR with agitation. Table 1 above displays the data
that was used.
Neutral Hydrolysis of PET Bottles Waste Process Description
This project's basis is a 1000 kg/h PET waste bottle. Simulation
and modeling were done using Figures 1(a)–(d). In Feed 1, PET
powder and water were mixed in a 1:1 mass ratio at 298.15 K
and 1.01325 bar at ambient operating conditions. The transport
medium for PET was water. Pump 1 was operating at 33.00 bars,
and heater 1 was operating at 513.15 K to move it into reactor
1. 7000 kg/h of feedwater [feed 2] was carried into reactor 1 by
pump 2 running at 33.00 bars, through heater 2 (pre-heating),
which heated the water to 513.15 K. In reactor 1, the mass pro-
portion of water to PET was 8:1. Water was overly present to
encourage PET's full conversion to TPA and the TPA product's
better selectivity over EG.
The input at Reactor 1 [the CSTR reactor] was a mixture of 1000
kg/h of PET and 8000 kg/h of water at a temperature and pres-
sure of 513.15 K and 33.00 bar, respectively. 266.257792 m3
was its volume, and it operated at 513.15 K and 32.00 bar pres-
sure. Data and operating parameters for reactor 1's depolymeri-
sation of PET into TPA were already displayed in Table 1 above.
As previously noted, a kinetic segment-based power law reac-
tion model was employed, and it was based on Equations 1 and
2 for the power law expression of molarity concentration basis
(Ci) displayed in Equations 1 and 2. The ndings of reactor 1's
[CSTR] degradation of PET bottle trash into TPA are displayed
in Table 4 below.
Filter 1 received the reactor 1 product mixture at a higher pres-
sure of 32.00 bar. Filter 1 ltered out 0.0263 kg/sec of solid,
unreacted PET as ltrate while operating at 1.01325 bar and
513.15 K. Pump 3 sent it to the purication or treatment area
for additional purication before reuse [recycling] or sale while
running at 2.0265 bar.
Pump 10, operating at 2.0265 bar through cooler 2, transferred
the output of Filter 1's ltration stream of 2.1751 kg/sec of wa-
ter, 0.0812 kg/sec of EG, and 0.2174 kg/sec of TPA at 513.15 k
and 1.01325 bar into Radfrac distillation column 1. Before en-
tering distillation column 1, cooler 2 lowered the temperature to
373.15 K, which is the boiling point of water and the stream's
most volatile component. The distillation pressure was 1.01325
bars. Pump 11 delivered the cleaned water into cooler 2, which
cooled it to 333.15 K while working at 2.0265 bar. It was sent
to be reused or packaged for use in business. Table 2 below con-
tains the information needed to model distillation column 1.
Table 2: Radfrac distillation column 1 modelling data to recover H2O from its mixture with EG and TPA for the neutral
hydrolysis method of PET depolymerisation
Conguration
Setup options
Calculation type Equilibrium
Number of stages 7
Condenser Total
Reboiler Kettle
Valid-phases Vapour-Liquid
Convergence standard
Operating Specications
Distillate rate Mass 7830.2467 Kg/h
Reux ratio Mass 0.7393
Free water reux ratio Mass 0.0000
Feed Streams
Name Stage Convention
Feed (Cooler 2 product) 4 Above-stage
Product streams
Name Stage Phase
Distillation column 1 overhead product 1 Vapour
Distillation column 1 bottom product 7 Liquid
Pressure 1.01325 bar
Parameter Value
Volume 6 | Issue 2 | 123
Petro Chem Indus Intern, 2023
Relative volatility of H2O/( EG+TPA) (α) 96.5824
Rm1 at minimum driving force (DFmin) 0.1528
Rm2 at maximum driving force (DFmax) 0.6161
Ro1 at minimum driving force (DFmin) 0.1833
Ro2 at maximum driving force (DFmax) 0.7393
Radfrac distillation 1 bottom product was transported by pump
12 operating at 2.0265 bar as a ltered mixture of EG, TPA, and
a trace of H2O through cooler 4 that cooled it to 373.15 K before
entering crystallizer 1. This cooling was to bring the stream tem-
perature within 10 degrees of the crystallizer's operating tem-
perature. Depending on its operating temperature, a crystallizer
cooler, chiller, or refrigerator is eective with an input stream
and a crystallizer operating temperature dierence of no more
than 10 degrees. The crystallizer 1 employs a cooler to cool its
contents stream to 362.15 K at 1.0133 bar pressure. The follow-
ing requirements [rules] should be followed while selecting a
temperature: (1) Unless it is a trace component that may or may
not be soluble in other components with higher freezing points,
its operating temperature must be higher than the freezing points
of all other components in the crystallizing stream, excluding
the crystallizing component. (2) The operating temperature of
the crystallizing stream must be lower than the boiling point of
all its constituents. The freezing points of EG, TPA, and trace
H2O are 260.15 K for EG, 700.15 K [sublimes], and 273.15 K,
respectively. The freezing points of EG and H2O are higher than
362.15 K, whereas TPA is much lower. H2O's [in traces] boiling
points are 373.15 K, EG's are 470.45 K, and TPA's are 700.15 K,
respectively. The prerequisites were satised, which gave us the
chance to recover a very high TPA. Table 3 below contains the
data for the crystallizer 1 model.
Table 3: Crystallizer 1 solid component and its solubility, solvent composition, phases, and property method, manipulated
and parametric variables for the neutral hydrolysis method of PET depolymerisation at 363.15 K temperature and 1.0133
bar pressure
Solid component
Component Mass Unit
TPA 782.72 Kg/h
TPA solubility 0.0001 g of solute per 100 g of solvents
mixture
0.0001 g / 0.0899 L of sol-
vents mixture
0.0012 g / L
Solvents composition
Basis mass Kg/h
Component Flow (kg/h) Fraction 100 g of solvent Density (g/
cm3)
Solvent vol.
(cm3)
Solvent vol. (L)
EG 292.25 0.9994 99.94 1.1130 89.793 0.089793
H2O 0.18 0.0006 0.06 1.0000 0.062 0.000062
Total 292.43 1.0000 100.00 89.855 0.089855
Phases and property method
Valid phases Solubility phase Property method
Vapour - Liquid Liquid POLYNRTL
Manipulated and parametric variables
Parametric variable
Variable Value Unit
Pressure 1.01325 bar
Manipulated variable (Equidistant)
Variable - Tempera-
ture
Value Unit
Start point 273.15 K
Manipulated variable (Equidistant)
End point 373.15 K
Number of intervals 20
Increment 5
Volume 6 | Issue 2 | 124
Petro Chem Indus Intern, 2023
The ltration composition of lter 3 was a mass fraction mix-
ture of 0.9994 (0.0812 kg/sec) of EG, 0.0006 (5.0443E-05 kg/
sec) of water, and 9.7028E-07 [7.8816E-08 kg/sec] of aqueous
TPA. It is a waste designated as EG-W-1 at 362.31 K and 1.0133
bar pressure. It was transported by pump 14 operating at 2.0265
bar pressure through refrigerator 3 that refrigerated it to a room
temperature of 298.15 K. The waste euent from EG-W-1 was
discharged into the waste pond or treated to recover its compo-
nents. While the ltrate of lter 3 consisted of 0.2174 kg/sec
TPA crystal, it was sent by pump 15 operating at 2.0265 bar for
further purication.
Results and Discussion for the Neutral Hydrolysis Method of
PET Depolymerization into TPA
The overall material and energy balances for the chemical recy-
cling of a 1000 kg/h ow rate of PET bottle waste into TPA using
the neutral hydrolysis method were obtained using intermediate
products and recovered materials. The reaction and separation of
the recovered and product materials were covered under the in-
line processing scope of this work. The outcomes are displayed
below.
Reactor
Equation 3 above displays the reaction's stoichiometry equation.
For reactor 1, the activation energy, Ea, is 80.940406817 kJ/mol
and the reaction rate constant, k, is 23.02585093. Equation (3)
states that a reaction between one mole of PET and two moles
of water results in one mole of TPA and one mole of EG. The
depolymerization of PET bottle trash at a rate of 1000 kg/h using
neutral hydrolysis served as the foundation for this work, and the
projected outcome was based on the reaction equation [4.88].
Results from this study and those from are displayed in Table 4.
It is evident that the yields of 90.54% for TPA and EG, as well
as their corresponding selectivities, were in line with the results
obtained by Liu and colleagues in 2012. At the identical optimal
operating conditions of 513.15 K, 32.00 bar pressure, and 0.5 h
residence time, they barely dier from one another. Addition-
ally, the process's selectivity of 0.7280 for TPA and 0.2720 for
EG demonstrated its viability and demonstrated that it favors the
manufacture of TPA rather than EG [19].
Table 4: Validation of this work of neutral hydrolysis depolymerisation of PET bottle waste into TPA (reactor 1 products)
with that of [19]
Reactor 1 output
Component Quantity (kg) % Mass fraction Mole fraction % yield selectivity
PET conversion 905.39 90.54
Unreacted PET 94.61 9.46 0.0105 0.0011
Water conver-
sion
169.75 2.12
Unreacted +
excess water
7830.25 97.88 0.8700 0.9777
Expected TPA 864.51
Produced TPA 782.72 0.0870 0.0106 90.54 0.7280
Expected EG 322.99
Produced EG 292.43 0.0325 0.0106 90.54 0.2720
Property This work (Liu et al., 2012) Dierence
Value Unit Value Unit Value (Unit)
Temperature 513.5 K 513.15 K
Pressure 32.00 bar 32.00 bar
Residence time 0.5 h 0.5 h
(Mass ratio) H2O:PET 8:1 8:1
yield of TPA 90.54 % 90.50 % 0.05 (%)
yield of EG 90.54 % 90.50 % 0.05 (%)
Selectivity of TPA 0.7280 0.7280 Nil
Selectivity of EG 0.2720 0.2720 Nil
The data and ndings of this study were also validated by com-
parison with the earlier research of the writers listed below.
When employing the neutral hydrolysis process to turn PET bot-
tle trash into TPA, there are several variations in the operating
parameters. The study by that used supercritical water condi-
tions and had a 90.50% yield of TPA was 99.96% accurate in
comparison to this study's 90.54% yield of TPA. For both the
green-coloured PET bottle trash with an 85.00% yield of TPA
and the colorless PET bottle waste with a 90.00% yield of TPA
supercritical water conditions were utilized [12,19]. The two
outcomes are not far from the outcomes of this investigation.
Volume 6 | Issue 2 | 125
Petro Chem Indus Intern, 2023
Distillation column
Evaluations were made of the reux ratio, overall stage count,
feed entering stage, overhead product stage, and bottom prod-
uct stage. They were determined using Raoult's law and the
vapor-liquid equilibrium [VLE] relations of the mixture's con-
stituent parts. The vapor pressures of the components were de-
termined using the extended Antoine equation (4), a vapor pres-
sure model. Equation 5 was used to calculate relative volatility.
The mole fraction of the light key (water) in the saturated liquid
phase as well as the mole fraction in the saturated vapor phase
were derived using the predicted vapor pressures and mole frac-
tions of the mix components, with TPA and EG as the heavy
keys. Calculations were made for the light key's [water] distilla-
tion driving force as well as the light key's relative volatility to
the heavy key [TPA + EG].
9
yield of TPA
90.54
%
90.50
%
0.05 (%)
yield of EG
90.54
%
90.50
%
0.05 (%)
Selectivity of TPA
0.7280
0.7280
Nil
Selectivity of EG
0.2720
0.2720
Nil
The data and findings of this study were also validated by comparison with the earlier research of the
writers listed below. When employing the neutral hydrolysis process to turn PET bottle trash into TPA, there are
several variations in the operating parameters. The study by Liu et al., (2012) that used supercritical water
conditions and had a 90.50% yield of TPA was 99.96% accurate in comparison to this study's 90.54% yield of
TPA. For both the green-coloured PET bottle trash with an 85.00% yield of TPA and the colorless PET bottle
waste with a 90.00% yield of TPA (Čolnik et al., 2021), supercritical water conditions were utilized. The two
outcomes are not far from the outcomes of this investigation.
4.2 Distillation column
Evaluations were made of the reflux ratio, overall stage count, feed entering stage, overhead product
stage, and bottom product stage. They were determined using Raoult's law and the vapor-liquid equilibrium
(VLE) relations of the mixture's constituent parts. The vapor pressures of the components were determined
using the extended Antoine equation (4), a vapor pressure model. Equation 5 was used to calculate relative
volatility. The mole fraction of the light key (water) in the saturated liquid phase as well as the mole fraction in
the saturated vapor phase were derived using the predicted vapor pressures and mole fractions of the mix
components, with TPA and EG as the heavy keys. Calculations were made for the light key's (water) distillation
driving force as well as the light key's relative volatility to the heavy key (TPA + EG).
The pure component properties parameters of Aspen plus at PLXANT contain the expanded Antoine
equation presented in Equation (4) above. Since the DIPPR equation does not include those parameters, it is also
utilized for DIPPR vapor pressure data based on the equation above with two zeros (0's) (for C3i and C4i)
placed into the parameter list.
The fraction of the light key (water) component in the saturated liquid phase was obtained from the
distillation column feed stream and is denoted by x. The relative volatility of water with respect to TPA and EG
must be greater than one for distillation to separate water (lighter key) from TPA and EG (the heavier key).
While Equation (6) was used to calculate the mole fraction of the light key (water) component in the saturated
vapour phase, which is represented by the letter y. Using Equation (7), the driving force to distill the light key
component (water) was assessed. The driving force for light key distillation is plotted against the mole fraction
of light key (water) in the saturated liquid phase in Figure 2. For evaluating bubbles and dew points,
respectively, use equations (8) and (9), correspondingly. A saturated liquid will generate a bubble of vapor at a
bubble point when the temperature rises by a certain amount. The dew point is the temperature at which, after a
one-degree drop in temperature, a drop of liquid emerges from a saturated vapor.
The pure component properties parameters of Aspen plus at
PLXANT contain the expanded Antoine equation presented in
Equation (4) above. Since the DIPPR equation does not include
those parameters, it is also utilized for DIPPR vapor pressure
data based on the equation above with two zeros (0's) [for C3i
and C4i] placed into the parameter list.
9
yield of TPA
90.54
%
90.50
%
0.05 (%)
yield of EG
90.54
%
90.50
%
0.05 (%)
Selectivity of TPA
0.7280
0.7280
Nil
Selectivity of EG
0.2720
0.2720
Nil
The data and findings of this study were also validated by comparison with the earlier research of the
writers listed below. When employing the neutral hydrolysis process to turn PET bottle trash into TPA, there are
several variations in the operating parameters. The study by Liu et al., (2012) that used supercritical water
conditions and had a 90.50% yield of TPA was 99.96% accurate in comparison to this study's 90.54% yield of
TPA. For both the green-coloured PET bottle trash with an 85.00% yield of TPA and the colorless PET bottle
waste with a 90.00% yield of TPA (Čolnik et al., 2021), supercritical water conditions were utilized. The two
outcomes are not far from the outcomes of this investigation.
4.2 Distillation column
Evaluations were made of the reflux ratio, overall stage count, feed entering stage, overhead product
stage, and bottom product stage. They were determined using Raoult's law and the vapor-liquid equilibrium
(VLE) relations of the mixture's constituent parts. The vapor pressures of the components were determined
using the extended Antoine equation (4), a vapor pressure model. Equation 5 was used to calculate relative
volatility. The mole fraction of the light key (water) in the saturated liquid phase as well as the mole fraction in
the saturated vapor phase were derived using the predicted vapor pressures and mole fractions of the mix
components, with TPA and EG as the heavy keys. Calculations were made for the light key's (water) distillation
driving force as well as the light key's relative volatility to the heavy key (TPA + EG).
The pure component properties parameters of Aspen plus at PLXANT contain the expanded Antoine
equation presented in Equation (4) above. Since the DIPPR equation does not include those parameters, it is also
utilized for DIPPR vapor pressure data based on the equation above with two zeros (0's) (for C3i and C4i)
placed into the parameter list.
The fraction of the light key (water) component in the saturated liquid phase was obtained from the
distillation column feed stream and is denoted by x. The relative volatility of water with respect to TPA and EG
must be greater than one for distillation to separate water (lighter key) from TPA and EG (the heavier key).
While Equation (6) was used to calculate the mole fraction of the light key (water) component in the saturated
vapour phase, which is represented by the letter y. Using Equation (7), the driving force to distill the light key
component (water) was assessed. The driving force for light key distillation is plotted against the mole fraction
of light key (water) in the saturated liquid phase in Figure 2. For evaluating bubbles and dew points,
respectively, use equations (8) and (9), correspondingly. A saturated liquid will generate a bubble of vapor at a
bubble point when the temperature rises by a certain amount. The dew point is the temperature at which, after a
one-degree drop in temperature, a drop of liquid emerges from a saturated vapor.
The fraction of the light key (water) component in the saturat-
ed liquid phase was obtained from the distillation column feed
stream and is denoted by x. The relative volatility of water with
respect to TPA and EG must be greater than one for distillation
to separate water [lighter key] from TPA and EG (the heavier
key). While Equation (6) was used to calculate the mole frac-
tion of the light key (water) component in the saturated vapour
phase, which is represented by the letter y. Using Equation (7),
the driving force to distill the light key component [water] was
assessed. The driving force for light key distillation is plotted
against the mole fraction of light key [water] in the saturated
liquid phase in Figure 2. For evaluating bubbles and dew points,
respectively, use equations (8) and (9), correspondingly. A sat-
urated liquid will generate a bubble of vapor at a bubble point
when the temperature rises by a certain amount. The dew point
is the temperature at which, after a one-degree drop in tempera-
ture, a drop of liquid emerges from a saturated vapor.
9
yield of TPA
90.54
%
90.50
%
0.05 (%)
yield of EG
90.54
%
90.50
%
0.05 (%)
Selectivity of TPA
0.7280
0.7280
Nil
Selectivity of EG
0.2720
0.2720
Nil
The data and findings of this study were also validated by comparison with the earlier research of the
writers listed below. When employing the neutral hydrolysis process to turn PET bottle trash into TPA, there are
several variations in the operating parameters. The study by Liu et al., (2012) that used supercritical water
conditions and had a 90.50% yield of TPA was 99.96% accurate in comparison to this study's 90.54% yield of
TPA. For both the green-coloured PET bottle trash with an 85.00% yield of TPA and the colorless PET bottle
waste with a 90.00% yield of TPA (Čolnik et al., 2021), supercritical water conditions were utilized. The two
outcomes are not far from the outcomes of this investigation.
4.2 Distillation column
Evaluations were made of the reflux ratio, overall stage count, feed entering stage, overhead product
stage, and bottom product stage. They were determined using Raoult's law and the vapor-liquid equilibrium
(VLE) relations of the mixture's constituent parts. The vapor pressures of the components were determined
using the extended Antoine equation (4), a vapor pressure model. Equation 5 was used to calculate relative
volatility. The mole fraction of the light key (water) in the saturated liquid phase as well as the mole fraction in
the saturated vapor phase were derived using the predicted vapor pressures and mole fractions of the mix
components, with TPA and EG as the heavy keys. Calculations were made for the light key's (water) distillation
driving force as well as the light key's relative volatility to the heavy key (TPA + EG).
The pure component properties parameters of Aspen plus at PLXANT contain the expanded Antoine
equation presented in Equation (4) above. Since the DIPPR equation does not include those parameters, it is also
utilized for DIPPR vapor pressure data based on the equation above with two zeros (0's) (for C3i and C4i)
placed into the parameter list.
The fraction of the light key (water) component in the saturated liquid phase was obtained from the
distillation column feed stream and is denoted by x. The relative volatility of water with respect to TPA and EG
must be greater than one for distillation to separate water (lighter key) from TPA and EG (the heavier key).
While Equation (6) was used to calculate the mole fraction of the light key (water) component in the saturated
vapour phase, which is represented by the letter y. Using Equation (7), the driving force to distill the light key
component (water) was assessed. The driving force for light key distillation is plotted against the mole fraction
of light key (water) in the saturated liquid phase in Figure 2. For evaluating bubbles and dew points,
respectively, use equations (8) and (9), correspondingly. A saturated liquid will generate a bubble of vapor at a
bubble point when the temperature rises by a certain amount. The dew point is the temperature at which, after a
one-degree drop in temperature, a drop of liquid emerges from a saturated vapor.
Where ki is the physical equilibrium constant, xi is the mole frac-
tion of light key component specie i in the saturated liquid phase,
and yi is the mole fraction of light key component specie i in the
saturated vapor phase.
Figure 2 demonstrates that the mole fraction of the light key
[water] in the saturated liquid phase was 0.09, and the light key's
[water's] maximum driving force for distillation was 0.8152.
This matched the highest stage [stage 1] in the column, where
tray number 1 was located, the point at which overhead product
was withdrawn, and the point at which the reux ratio was com-
puted. It also matched the point at which the maximum light key
(water) component was achieved.
Volume 6 | Issue 2 | 126
Petro Chem Indus Intern, 2023
10
Where ki is the physical equilibrium constant, xi is the mole fraction of light key component specie i in
the saturated liquid phase, and yi is the mole fraction of light key component specie i in the saturated vapor
phase.
Figure 2 demonstrates that the mole fraction of the light key (water) in the saturated liquid phase was
0.09, and the light key's (water's) maximum driving force for distillation was 0.8152. This matched the highest
stage (stage 1) in the column, where tray number 1 was located, the point at which overhead product was
withdrawn, and the point at which the reflux ratio was computed. It also matched the point at which the
maximum light key (water) component was achieved.
Figure 2: Graph plot of the neutral hydrolysis method of PET depolymerisation Radfac distillation column 1:
light key (water) distillation driving force versus mole fraction of light key (water) in saturated liquid phase
The steps necessary for distillation column separation—feed entering, overhead product collection, and
bottom product collection—depend on the reflux ratio (R) that is applied. The distillation column with optimal
R (Ro) has the lowest annual operating cost. The ideal reflux ratio (R) is always in the range of 1.2 to 1.5 times
the minimal reflux ratio (Rm). To evaluate Ro, this work multiplied Rm by 1.2. The amount of phases (Nm) was
calculated using equation 10 below.
Where is the light key average relative volatility in respect to the heavy key. Nm is the minimum
number of distillation column required plate. Whereas and are Where is the light key's average
relative volatility with respect to the heavy key. Nm is the minimum number of distillation columns required per
plate. Whereas and represent the mole fractions of light and heavy key components in the saturated
liquid phase, with d and b representing distil (overhead) and bottom products, respectively. Equations (11), (12)
and (13) were used to calculate Rm and Ro, respectively, and to show the overhead product, feed stream, and
bottom product stage numbers. They were shown in Table 2 above.
0
0.2
0.4
0.6
0.8
1
1.2
0 0.2 0.4 0.6 0.8 1
((α)(x)/[1+(α-1)(x)] - x) Driving
force
Mole fraction of water in saturated liquid phase
Driving Force of Water-EG-TPA System
DF
Series2
Series3
Figure 2: Graph plot of the neutral hydrolysis method of PET depolymerisation Radfac distillation column 1: light key [water]
distillation driving force versus mole fraction of light key [water] in saturated liquid phase
The steps necessary for distillation column separation—feed en-
tering, overhead product collection, and bottom product collec-
tion—depend on the reux ratio [R] that is applied. The distilla-
tion column with optimal R (Ro) has the lowest annual operating
cost. The ideal reux ratio (R) is always in the range of 1.2 to 1.5
times the minimal reux ratio [Rm]. To evaluate Ro, this work
multiplied Rm by 1.2. The amount of phases [Nm] was calculat-
ed using equation 10 below.
10
Where ki is the physical equilibrium constant, xi is the mole fraction of light key component specie i in
the saturated liquid phase, and yi is the mole fraction of light key component specie i in the saturated vapor
phase.
Figure 2 demonstrates that the mole fraction of the light key (water) in the saturated liquid phase was
0.09, and the light key's (water's) maximum driving force for distillation was 0.8152. This matched the highest
stage (stage 1) in the column, where tray number 1 was located, the point at which overhead product was
withdrawn, and the point at which the reflux ratio was computed. It also matched the point at which the
maximum light key (water) component was achieved.
Figure 2: Graph plot of the neutral hydrolysis method of PET depolymerisation Radfac distillation column 1:
light key (water) distillation driving force versus mole fraction of light key (water) in saturated liquid phase
The steps necessary for distillation column separation—feed entering, overhead product collection, and
bottom product collection—depend on the reflux ratio (R) that is applied. The distillation column with optimal
R (Ro) has the lowest annual operating cost. The ideal reflux ratio (R) is always in the range of 1.2 to 1.5 times
the minimal reflux ratio (Rm). To evaluate Ro, this work multiplied Rm by 1.2. The amount of phases (Nm) was
calculated using equation 10 below.
Where is the light key average relative volatility in respect to the heavy key. Nm is the minimum
number of distillation column required plate. Whereas and are Where is the light key's average
relative volatility with respect to the heavy key. Nm is the minimum number of distillation columns required per
plate. Whereas and represent the mole fractions of light and heavy key components in the saturated
liquid phase, with d and b representing distil (overhead) and bottom products, respectively. Equations (11), (12)
and (13) were used to calculate Rm and Ro, respectively, and to show the overhead product, feed stream, and
bottom product stage numbers. They were shown in Table 2 above.
0
0.2
0.4
0.6
0.8
1
1.2
0 0.2 0.4 0.6 0.8 1
((α)(x)/[1+(α-1)(x)] - x) Driving
force
Mole fraction of water in saturated liquid phase
Driving Force of Water-EG-TPA System
DF
Series2
Series3
Where αLk is the light key average relative volatility in respect to
the heavy key. Nm is the minimum number of distillation column
required plate. Whereas xLk and xHk are Where αLk is the light
key's average relative volatility with respect to the heavy key.
Nm is the minimum number of distillation columns required per
plate. Whereas xLk and xHk represent the mole fractions of light
and heavy key components in the saturated liquid phase, with
d and b representing distil (overhead) and bottom products, re-
spectively. Equations (11), (12) and (13) were used to calculate
Rm and Ro, respectively, and to show the overhead product, feed
stream, and bottom product stage numbers. They were shown in
Table 2 above.
11
Where represents the root of the equation, is the concentration of component i in the distillation
column top at minimum reflux, and other parameters are as defined earlier.
7830.07 kg/h (99.9977 mass percent) H2O was recovered with very minor contaminants of 0.18 kg/h
(0.0023 mass percent) EG and 4.09E-11 kg/h (0.0000 mass percent) TPA. The recovered water purity was
100.00% and is highly recommended for consumption and all other uses. Recovered water, designated as W-R-
1, was transported, with the aid of pump 11, operating at 2.0265 bar, into Cooler 2, which cooled it to 333.15 K
and sent for re-use or packaging for commercial purposes.
4.3 Crystallizer
TPA was only 0.0001 percent soluble in the solvents and working conditions of the crystallizer. As
indicated in Table 3 and depicted in Figure 3, it means 0.0001 g of TPA in 100 g of the solvent mixture, or
0.0012 g of TPA/L of solvent mixture.
Figure 3: Graph plot of solubility of solute (TPA) in 0.9994 mass of EG and 0.0006 mass fraction of water at
363.15K temperature and 1.0133 bar pressure for neutral hydrolysis method of PET depolymerisation of
crystallizer 1
At 362.15 K temperature and 1.0133 bar pressure, the product stream from Crystallizer 1 contained
0.7280 (0.2174 kg/sec) mass fraction of TPA crystal, 2.6391 E-07 (7.8816E-08 kg/sec) mass fraction of aqueous
TPA, 0.2718 (0.0812 kg/sec) mass fraction of EG, and 0.0002 (5.0443E-05 kg/sec) mass fraction of water.
Pump 13 pushed the product stream from the crystallizer 1 into filter 3 at a pressure of 2.0265 bar. The filter 3
defines phase separation of fraction of liquid from fraction of solid and operates at 1.0133 bar pressure.
4.4 Overall material balance of the neutral hydrolysis method of chemical recycling of PET bottle
waste.
Table 5: Summary of the overall material balance of the waste system boundary of the neutral hydrolysis
method of chemical recycling of PET bottles in terms of feeds, wastes generated, and products (recovered
materials and purified products).
Where θ represents the root of the equation, xi,d is the concentration of component i in the distillation column top at minimum reux,
and other parameters are as dened earlier.
11
Where represents the root of the equation, is the concentration of component i in the distillation
column top at minimum reflux, and other parameters are as defined earlier.
7830.07 kg/h (99.9977 mass percent) H2O was recovered with very minor contaminants of 0.18 kg/h
(0.0023 mass percent) EG and 4.09E-11 kg/h (0.0000 mass percent) TPA. The recovered water purity was
100.00% and is highly recommended for consumption and all other uses. Recovered water, designated as W-R-
1, was transported, with the aid of pump 11, operating at 2.0265 bar, into Cooler 2, which cooled it to 333.15 K
and sent for re-use or packaging for commercial purposes.
4.3 Crystallizer
TPA was only 0.0001 percent soluble in the solvents and working conditions of the crystallizer. As
indicated in Table 3 and depicted in Figure 3, it means 0.0001 g of TPA in 100 g of the solvent mixture, or
0.0012 g of TPA/L of solvent mixture.
Figure 3: Graph plot of solubility of solute (TPA) in 0.9994 mass of EG and 0.0006 mass fraction of water at
363.15K temperature and 1.0133 bar pressure for neutral hydrolysis method of PET depolymerisation of
crystallizer 1
At 362.15 K temperature and 1.0133 bar pressure, the product stream from Crystallizer 1 contained
0.7280 (0.2174 kg/sec) mass fraction of TPA crystal, 2.6391 E-07 (7.8816E-08 kg/sec) mass fraction of aqueous
TPA, 0.2718 (0.0812 kg/sec) mass fraction of EG, and 0.0002 (5.0443E-05 kg/sec) mass fraction of water.
Pump 13 pushed the product stream from the crystallizer 1 into filter 3 at a pressure of 2.0265 bar. The filter 3
defines phase separation of fraction of liquid from fraction of solid and operates at 1.0133 bar pressure.
4.4 Overall material balance of the neutral hydrolysis method of chemical recycling of PET bottle
waste.
Table 5: Summary of the overall material balance of the waste system boundary of the neutral hydrolysis
method of chemical recycling of PET bottles in terms of feeds, wastes generated, and products (recovered
materials and purified products).
7830.07 kg/h (99.9977 mass percent) H2O was recovered with
very minor contaminants of 0.18 kg/h (0.0023 mass percent)
EG and 4.09E-11 kg/h [0.0000 mass percent] TPA. The recov-
ered water purity was 100.00% and is highly recommended for
consumption and all other uses. Recovered water, designated as
W-R-1, was transported, with the aid of pump 11, operating at
2.0265 bar, into Cooler 2, which cooled it to 333.15 K and sent
for re-use or packaging for commercial purposes.
Crystallizer
TPA was only 0.0001 percent soluble in the solvents and work-
ing conditions of the crystallizer. As indicated in Table 3 and
depicted in Figure 3, it means 0.0001 g of TPA in 100 g of the
solvent mixture, or 0.0012 g of TPA/L of solvent mixture.
Volume 6 | Issue 2 | 127
Petro Chem Indus Intern, 2023
11
Where represents the root of the equation, is the concentration of component i in the distillation
column top at minimum reflux, and other parameters are as defined earlier.
7830.07 kg/h (99.9977 mass percent) H2O was recovered with very minor contaminants of 0.18 kg/h
(0.0023 mass percent) EG and 4.09E-11 kg/h (0.0000 mass percent) TPA. The recovered water purity was
100.00% and is highly recommended for consumption and all other uses. Recovered water, designated as W-R-
1, was transported, with the aid of pump 11, operating at 2.0265 bar, into Cooler 2, which cooled it to 333.15 K
and sent for re-use or packaging for commercial purposes.
4.3 Crystallizer
TPA was only 0.0001 percent soluble in the solvents and working conditions of the crystallizer. As
indicated in Table 3 and depicted in Figure 3, it means 0.0001 g of TPA in 100 g of the solvent mixture, or
0.0012 g of TPA/L of solvent mixture.
Figure 3: Graph plot of solubility of solute (TPA) in 0.9994 mass of EG and 0.0006 mass fraction of water at
363.15K temperature and 1.0133 bar pressure for neutral hydrolysis method of PET depolymerisation of
crystallizer 1
At 362.15 K temperature and 1.0133 bar pressure, the product stream from Crystallizer 1 contained
0.7280 (0.2174 kg/sec) mass fraction of TPA crystal, 2.6391 E-07 (7.8816E-08 kg/sec) mass fraction of aqueous
TPA, 0.2718 (0.0812 kg/sec) mass fraction of EG, and 0.0002 (5.0443E-05 kg/sec) mass fraction of water.
Pump 13 pushed the product stream from the crystallizer 1 into filter 3 at a pressure of 2.0265 bar. The filter 3
defines phase separation of fraction of liquid from fraction of solid and operates at 1.0133 bar pressure.
4.4 Overall material balance of the neutral hydrolysis method of chemical recycling of PET bottle
waste.
Table 5: Summary of the overall material balance of the waste system boundary of the neutral hydrolysis
method of chemical recycling of PET bottles in terms of feeds, wastes generated, and products (recovered
materials and purified products).
Figure 3: Graph plot of solubility of solute [TPA] in 0.9994 mass of EG and 0.0006 mass fraction of water at 363.15K temperature
and 1.0133 bar pressure for neutral hydrolysis method of PET depolymerisation of crystallizer 1
At 362.15 K temperature and 1.0133 bar pressure, the product
stream from Crystallizer 1 contained 0.7280 [0.2174 kg/sec]
mass fraction of TPA crystal, 2.6391 E-07 [7.8816E-08 kg/sec]
mass fraction of aqueous TPA, 0.2718 [0.0812 kg/sec] mass
fraction of EG, and 0.0002 [5.0443E-05 kg/sec] mass fraction of
water. Pump 13 pushed the product stream from the crystallizer
1 into lter 3 at a pressure of 2.0265 bar. The lter 3 denes
phase separation of fraction of liquid from fraction of solid and
operates at 1.0133 bar pressure.
Overall material balance of the neutral hydrolysis method of chemical recycling of PET bottle waste.
Table 5: Summary of the overall material balance of the waste system boundary of the neutral hydrolysis method of chem-
ical recycling of PET bottles in terms of feeds, wastes generated, and products [recovered materials and puried products].
Operation⁄Component PET Water Zn(Ac)2
Feed 1 1000.00 1000.00
Feed 2 7000.00 15.00
Total (kg/h) 1000.00 8000.00 15.00
Feeds grand total (kg/h) 9015.00
Operation⁄Component PET Water TPA EG
Product 1 (PET-R-1) 94.61
Product 4 (W-R-2) 7830.07 0.18
Product 5 (TPA-PD-1) 782.72
Products Total (kg/h) 94.61 7830.07 782.72 0.18
Operation⁄Component PET Water Water Air
Products grand total (kg/h) 8707.58
Operation⁄Component EG Water Zn(Ac)2
Waste 3 (EG-W-1) 292.25 0.18 15.00
Wastes total (kg/h) 292.25 0.18 15.00
Wastes grand total (kg/h) 307.43
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Energy balance for cooling and refrigeration for the neutral hydrolysis method of chemical recycling of PET into TPA
Table 6: Energy Balances for Cooling for the Neutral Hydrolysis Method of Chemical Recycling of PET into TPA
Cooling Medium Cooling water Cooling water
Unit Cooling water (Tin = 293.15 K ; To = 298.15 K; ▲T
= 5 ) (kJ/h)
Cp1=4.182, T1=20 oC; Cp2=4.180, T2=25 oC. Cp(avg.)
dT = (4.180+4.182)/2*(25-20) = 4.181*5 = 20.905
kJ/kg Mass ow (kg/h)
Cooler 1 5788198.6796 276881.0658
Cooler 2 1363157.8705 65207.2648
Cooler 3 282705.4471 13523.3412
Crystallizer 1 145905.4728 6979.4534
RDC1 condenser 30763575.3963 1471589.3517
Total 38343542.8663 1834180.4769
Table 7: Refrigeration energy balances for Neutral hydrolysis method of chemical recycling of PET into TPA contin-
ues
Refrigeration Medium Refrigerant 1 Cooling - Propane Refrigerant 1 Cooling - Propane
Unit Refrigerant 1 (Ti = 248.15 K ; To = 249.15 K;
▲T = 1 ) (kJ/h)
Refrigerant 1: T = 248.15 K (-25 oC): Sensible heat =
Cp(av.)dT = 4.00 kJ/kg. Mass ow (kg/h)
Refrigerator 1 45493.4298 11373.3449
Total 45493.4298 11373.3449
Heating energy balances for the neutral hydrolysis method of chemical recycling of PET into TPA
Table 8: Heating energy balances for the neutral hydrolysis method of chemical recycling of PET into TPA continues
Heating medium High Pressure Steam (HPS) High Pressure Steam (HPS)
Unit HPS (Ti = 523.15 K ; To = 522.15 K; ▲T = 1 ) (kJ/h) P = 40.0 bar, Ti = 523.15 K and Lv = 1705.62 kJ/
kg (kg/h)
Heater 1 2819906.1870 1653.3027
Heater 2 19406523.2160 11377.9876
Reactor 1 17069750.7932 10007.9448
RDC1 reboiler 31046034.0463 18202.1986
Total 70342214.2425 41241.4337
Energy balances for pumps and compressors used in the neutral hydrolysis method of chemical recycling of PET into TPA
Table 9: Energy balances for pumps and compressors used in the neutral hydrolysis method of chemical recycling of PET
into TPA.
Unit Electricity (kWh) Unit Electricity (kWh)
Pump 1 7.46 Pump 6 0.19
Pump 2 22.38 Pump 7 0.09
Pump 3 0.09 Pump 8 0.09
Pump 4 0.75 Pump 9 0.09
Pump 5 0.75 Dist 1 reux pump 5.59
Total Pump energy (kWh) 37.48 Total electricity used (kWh) 37.48
The neutral hydrolysis approach needed 8000 kg/h and 15.00
kg/h ow rates of process water and zinc acetate (catalyst), re-
spectively, to depolymerize a 1000 kg/h ow rate of PET into
TPA. The raw materials utilized in it owed at a total rate of
9015 kg/h. The ow rates of TPA (the major product), PET, and
water with minimal EG contamination [0.18 kg/h] were 782.72
kg/h, 94.61 kg/h, and 7830.25 kg/h, respectively, for the main
products, recovered materials, and by-products. The overall ow
rate of the products was 8707.58 kg/h; EG-W-1, which stood for
ethylene glycol euent waste, had a ow rate of 292.25 kg/h;
and Zn(Ac)2-W-1, which stood for spent catalyst waste of zinc
acetate, had a ow rate of 15.00 kg/h. According to Table 5, the
total weight of the wastes for the neutral hydrolysis system was
307.43 kg/h. There was no dierence between the 9015.00 kg/h
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Petro Chem Indus Intern, 2023
of feeds and the 9015 kg/h of products [totaled 8707.58 kg/h +
wastes totaled 307.43 kg/h].
The utilities used for the 1000 kg/h depolymerisation of PET
using the neutral hydrolysis method were cooling water and
propane. As earlier described, the cooling water has an inlet
temperature (Ti) of 293.15 K [20 oC] and an outlet temperature
(To) of 298.15 K [25 oC]. It has specic heat capacities (Cp) of
4.183, 4.182, and 4.180 at pressures of 1, 5, and 10 bars, respec-
tively, with an average of 4.182 kJ/kg-K used for the compu-
tation, and is operational at the aforementioned pressure range
of 1 to 10 bar. The total mass ow rate of cooling water used
was 1834180.4769 kg/h. In this case, propane refrigerant was
used under one (1) condition designated by Aspen plus V10 as
refrigerant 1, with a Ti of 248.15 K [-25 oC], To of 249.15 K
(-24 oC), sensible heat Cp[avg.] dT of 4.00 kJ/kg, and a ow
rate of 11373.3449 kg/h of propane refrigerant. It should be re-
called that sensible heat was used because propane was used as
a secondary working uid that transmitted refrigeration from the
utilities-supplying industry over the window into other manu-
facturing industries. The energy required for the system cooling
[exothermic energy] from cooling water for the neutral hydroly-
sis method was 38343542.8663 kJ/h [38343.5429 MJ/h]. While
the refrigeration energy requirement was 45493.4298 kJ/h
[45.4934 MJ/h]. The cooling and refrigeration energy totalled
38389036.2961 kJ/h [38389.0363 MJ/h].
Aspen Plus v10 heating formats and their operating conditions
were used for this work, and they were designated as LPS, MPS,
HPS, HO, FH1, and FH2, respectively. This work spanned just
one (1) category of HPS that has a steam ow rate of 41241.4337
kg/h when operating at Ti of 523.15 K, To of 522.15 K, and P of
40.0 bar, with a latent heat of vaporization Lv of 1705.62 kJ/kg.
The energy required for high heating of the system for the neu-
tral hydrolysis method was 70342214.2425 kJ/h [70342.2142
MJ/h].
The total electricity consumed by the centrifugal pumps used in
this work was 37.48 kWh [134.928 MJ]. Tables 6, 7, 8, and 9
showed results for cooling, refrigeration, heating, and electricity
utility use, respectively.
Conclusions
Experimental PET depolymerisation into TPA was accomplished
using the neutral hydrolysis approach to chemical recycling.
With the help of CSTR, the data was used for design, model-
ling, and simulation in the Aspen plus V10 simulator to address
the issues with product mix separation specic to PET bottle
trash. The commercial manufacturing of TPA using PET bottle
trash is another goal. Increases in residence time, the H2O:PET
reactant ratio, and the catalyst:PET ratio increase TPA and EG
yields until reaction equilibrium is reached. The ideal working
parameters for this procedure were a 0.5-hour residence peri-
od, an H20:PET weight ratio of 8, and a Zn(Ac)2:PET ratio of
0.015. TPA and EG yields of 90.54 percent and 90.54 percent,
respectively, were achieved, with selectivity of 0.7280 for TPA
and 0.2720 for EG. In order to separate the combination of prod-
ucts, Aspen plus V10 software was used to simulate nine pumps:
a reux pump, a reboiler, a condenser, two lters, a distillation
column, a crystallizer, two heaters, coolers, and a refrigerator.
H2O [7830.2520 kg/h], EG [292.4273 kg/h], unreacted PET
[94.6109 kg/h], and TPA [782.7156 kg/h] were the reactor's out-
puts. Filter 1 completely eliminated unreacted PET. 100% pure
water was distilled in a distillation column. TPA was crystallized
from EG, and lter 2 separated the ltrate into 100% pure TPA
and 99.94% pure EG. A total of 1834180.4769 kg/h of cooling
water was used to produce 38343542.8663 kJ/h of cooling ener-
gy for the entire system. The energy required for refrigeration,
using 11373.3449 kg/h of propane, was 45493.4298 kJ/h. Run-
ning 41241.4337 kg/h of high-pressure steam provided the sys-
tem with the 70342214.2425 kJ/h of total heating energy needed.
A total of 37.48 kWh of power were consumed for pumping.
Higher yields, purer products, and recovered materials were pro-
duced as a result of this work. The necessary heating, cooling,
refrigeration, and power were realistic requirements. It serves
as a guide for the most eective creation of the desired items.
It oers guidance for simpler and more economical operations.
For actual industrial applications, it can be a useful processing
guide.
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