U.S. patent application number 16/062713 was filed with the patent office on 2018-12-20 for process for converting mixed waste plastic into liquid fuels and waxes by catalytic cracking.
The applicant listed for this patent is SOLVAY SA. Invention is credited to Celine BAUREGARD, Miriam CERRO-ALARCON, Avelino CORMA, Perrine GILLOT, Jes s MENGUAL, Marco PICCININI, Stephane STREIFF.
Application Number | 20180362857 16/062713 |
Document ID | / |
Family ID | 55068789 |
Filed Date | 2018-12-20 |
United States Patent
Application |
20180362857 |
Kind Code |
A1 |
STREIFF; Stephane ; et
al. |
December 20, 2018 |
PROCESS FOR CONVERTING MIXED WASTE PLASTIC INTO LIQUID FUELS AND
WAXES BY CATALYTIC CRACKING
Abstract
The present invention relates to a process for converting mixed
waste plastic into liquid fuels and waxes by catalytic cracking.
The process comprises the steps of introducing mixed waste plastic
and a catalyst comprising a zeolite-type catalyst within a reactor;
allowing at least a portion of the mixed waste plastic to be
converted to liquid fuels and waxes within the reactor; and
removing a product stream containing said liquid fuels and waxes
from the reactor.
Inventors: |
STREIFF; Stephane;
(Shanghai, CN) ; PICCININI; Marco; (Brussels,
BE) ; BAUREGARD; Celine; (Lyon, FR) ; GILLOT;
Perrine; (Lyon, FR) ; CORMA; Avelino;
(Valencia, ES) ; CERRO-ALARCON; Miriam; (Valencia,
ES) ; MENGUAL; Jes s; (Carcaixent, ES) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SOLVAY SA |
Brussels |
|
BE |
|
|
Family ID: |
55068789 |
Appl. No.: |
16/062713 |
Filed: |
December 15, 2016 |
PCT Filed: |
December 15, 2016 |
PCT NO: |
PCT/EP2016/081302 |
371 Date: |
June 15, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 1/08 20130101; C10G
11/05 20130101; C10G 1/10 20130101; C10G 2300/1003 20130101 |
International
Class: |
C10G 11/05 20060101
C10G011/05; C10G 1/10 20060101 C10G001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 18, 2015 |
EP |
15201127.6 |
Claims
1. A process for converting mixed waste plastic into liquid fuels
and waxes by catalytic cracking, the process comprising:
introducing mixed waste plastic and a catalyst comprising a
zeolite-type catalyst within a reactor; allowing at least a portion
of the mixed waste plastic to be converted to liquid fuels and
waxes within the reactor; and removing a product stream containing
said liquid fuels and waxes from the reactor, wherein the mixed
waste plastic contains from 2 to 50% by weight of polystyrene and
from 50 to 98% by weight of polyolefin, each based on the total
weight of polystyrene and polyolefin in the mixed waste plastic,
and wherein the weight ratio of catalyst to mixed waste plastic in
the reactor is above 1:10.
2. The process according to claim 1, wherein the mixed waste
plastic contains from 2 to 40% by weight of polystyrene, based on
the total weight of polystyrene and polyolefin in the mixed waste
plastic.
3. The process according to claim 1, wherein the weight ratio of
catalyst to mixed waste plastic in the reactor is above 1:8.
4. The process according to claim 1, wherein the weight ratio of
catalyst to mixed waste plastic in the reactor is below 10:1.
5. The process according to claim 1, wherein the catalyst
predominantly is a zeolite-type catalyst.
6. The process according to claim 1, wherein the catalyst consists
of zeolite-type catalyst.
7. The process according to claim 1, wherein the catalyst
additionally comprises an amorphous-type catalyst.
8. The process according to claim 7, wherein the amorphous-type
catalyst comprises silica, alumina, kaolin, or a mixture
thereof.
9. The process according to claim 1, wherein the catalyst is fresh
catalyst, equilibrated catalyst, or a mixture thereof.
10. The process according to claim 1, wherein the temperature at
which at least part of the mixed waste plastic is converted to
liquid fuels and waxes in the reactor is above 350.degree. C.
11. The process according to claim 1, wherein the mixed waste
plastic comprises more than 50% by weight of polystyrene and
polyolefin, based on the total weight of the mixed waste
plastic.
12. The process according to claim 1, which wherein the process is
conducted continuously.
13. The process according to claim 1, wherein the waste plastic is
selected from the group consisting of post consumer waste plastic,
off-spec plastic and industrial scrap plastic.
14. The process according to claim 1, wherein the waste plastic is
essentially free of thermosetting polymers.
15. The process according to claim 2, wherein the mixed waste
plastic contains from 2 to 30% by weight of polystyrene, based on
the total weight of polystyrene and polyolefin in the mixed waste
plastic.
16. The process according to claim 15, wherein the mixed waste
plastic contains from 2 to 20% by weight of polystyrene, based on
the total weight of polystyrene and polyolefin in the mixed waste
plastic.
17. The process according to claim 3, wherein the weight ratio of
catalyst to mixed waste plastic in the reactor is above 1:5.
18. The process according to claim 4, wherein the weight ratio of
catalyst to mixed waste plastic in the reactor is below 7:1.
19. The process according to claim 10, wherein the temperature at
which at least part of the mixed waste plastic is converted to
liquid fuels and waxes in the reactor is above 410.degree. C.
20. The process according to claim 19, wherein the temperature at
which at least part of the mixed waste plastic is converted to
liquid fuels and waxes in the reactor is in the range of above
410.degree. C. to 500.degree. C.
Description
[0001] This application claims priority to European application No.
15201127.6--filed on Dec. 18, 2015--, the whole content of this
application being incorporated herein by reference for all
purposes.
[0002] The present invention relates to a process for converting
mixed waste plastic into liquid fuels and waxes by catalytic
cracking. The process comprises the steps of introducing mixed
waste plastic and a catalyst comprising a zeolite-type catalyst
within a reactor; allowing at least a portion of the mixed waste
plastic to be converted to liquid fuels and waxes within the
reactor; and removing a product stream containing said liquid fuels
and waxes from the reactor.
[0003] In view of the increasing importance of polymers as
substitutes for conventional materials of construction, such as
glass, metal, paper, and wood, the perceived need to save
non-renewable resources such as petroleum and dwindling amounts of
landfill capacity available for the disposal of waste products,
considerable attention has been devoted in recent years to the
problem of recovering, reclaiming, recycling or in some way reusing
waste plastic.
[0004] It has been proposed to pyrolize or catalytically crack the
waste plastic so as to convert high molecular weight polymers into
volatile compounds having a much lower molecular weight. The
volatile compounds, depending on the process employed, can be
either relatively high boiling liquid hydrocarbons useful as fuel
oils or fuel oil supplements or light to medium boiling
hydrocarbons useful as gasoline-type fuels or as other
chemicals.
[0005] Catalytic cracking of mixed waste plastic is a process well
known to the person skilled in the art. For example, U.S. Pat. No.
5,216,149 discloses a method for controlling the pyrolysis of a
complex waste stream of plastics to convert such stream into useful
high-value monomers or other chemicals, by identifying catalyst and
temperature conditions that permit decomposition of a given polymer
in the presence of others, without substantial decomposition of the
other polymers.
[0006] K.-H. Lee, et al. disclose in Polymer Degradation and
Stability 84 (2004) 123-127 the liquid-phase catalytic degradation
of mixtures of waste high-density polyethylene and polystyrene over
spent FCC catalyst. The effect of the mixing proportions of
polyethylene to polystyrene was studied and the authors found that
an increase of polystyrene content in the reactants showed an
increase of gasoline fraction and a decrease in kerosene, diesel
and wax fractions in the obtained product. However, at the same
time, the fraction of aromatic components in the liquid product
dramatically increased to 70% and more even at a polystyrene
content of only about 40%. This finding is confirmed in the
publication of K.-H. Lee in Polymer Degradation and Stability 93
(2008) 1284-1289 where at a polystyrene content of 40% even 90%
aromatics were obtained. The experiments reported by K.-H. Lee were
conducted using 20 g of catalyst per 200 g of plastic.
[0007] While for certain applications increasing the fraction of
gasoline obtained from the catalytic cracking of waste plastic can
be of advantage, a high fraction of aromatic compounds can be
undesired, for example due to the toxicity of such compounds.
Furthermore, for other applications it is of advantage to increase
the fractions of diesel and waxes, for example in case of an
increasing demand for diesel in the market. It would therefore be
desirable to provide a process for catalytic cracking of waste
plastic wherein the ratio of gasoline to diesel fractions obtained
can be tailored without undesirably increasing the fraction of
aromatic compounds obtained.
[0008] The present inventors found that this and other problems as
described below can surprisingly by solved by selecting a certain
ratio of polystyrene to polyolefin in the mixed waste plastic and
increasing the ratio of catalyst comprising a zeolite-type catalyst
to waste plastic in the reactor.
[0009] The present invention therefore relates to a process for
converting mixed waste plastic into liquid fuels and waxes by
catalytic cracking, the process comprising: [0010] introducing
mixed waste plastic and a catalyst comprising a zeolite-type
catalyst within a reactor; [0011] allowing at least a portion of
the mixed waste plastic to be converted to liquid fuels and waxes
within the reactor; and [0012] removing a product stream containing
said liquid fuels and waxes from the reactor, characterized in that
the mixed waste plastic contains from 2 to 50% by weight of
polystyrene and from 50 to 98% by weight of polyolefin, each based
on the total weight of polystyrene and polyolefin in the mixed
waste plastic, and in that the weight ratio of catalyst to mixed
waste plastic in the reactor is above 1:10.
[0013] In the catalytic cracking of plastic several fractions of
chemical compounds are obtained. Usually, there is a gas fraction
containing light weight chemical compounds with less than 5 carbon
atoms. The gasoline fraction contains compounds having a low
boiling point of for example below 216.degree. C. This fraction
includes compounds having 5 to 11 carbon atoms. The kerosene and
diesel fraction has a higher boiling point of for example
216.degree. C. to 359.degree. C. This fraction generally contains
compounds having 12 to 21 carbon atoms. The even higher boiling
fraction is generally designated as wax (Heavy Cycle Oil or HCO).
In all the fractions, the compounds are hydrocarbons which
optionally comprise heteroatoms, such as N, O, etc. "Liquid fuels"
in the sense of the present invention therefore are fuels like
gasoline and diesel but may also be used as other valuable
chemicals or solvents. "Waxes" designate such hydrocarbons which
are solid at room temperature (23.degree. C.) and have a softening
point of generally above 45.degree. C.
[0014] A plastic is mostly constituted of a particular polymer and
the plastic is generally named by this particular polymer.
Preferably, a plastic contains more than 25% by weight of its total
weight of the particular polymer, preferably more than 40% by
weight and more preferably more than 50% by weight. Other
components in plastic are for example additives, such as fillers,
reinforcers, processing aids, plasticizers, pigments, light
stabilizers, lubricants, impact modifiers, antistatic agents, inks,
antioxidants, etc. Generally, a plastic comprises more than one
additive.
[0015] Plastics used in the process of the present invention are
polyolefins and polystyrene, such as high density polyethylene
(HDPE), low density polyethylene (LDPE), polypropylene (PP) and
polystyrene (PS). Mixed plastics mostly constituted of polyolefin
and polystyrene are preferred. In this context "mostly constituted"
is to be understood such that the concentration of the polyolefin
and the polystyrene in the mixed plastic is above 50% by weight,
more preferably above 75% by weight, each based on the total weight
of the dry mixed plastic. The mixed plastic may be constituted of
polyolefin and polystyrene. Preferably, the mixed plastic contains
less than 99.5% by weight, more preferably less than 99% by weight
of polyolefin and polystyrene, based on the total weight of the dry
mixed plastic.
[0016] Other plastics, such as polyvinylchloride, polyvinylidene
chloride, polyethylene terephthalate, polyurethane (PU),
acrylonitrile-butadiene-styrene (ABS), nylon and fluorinated
polymers are less desirable. If present in the waste plastic, they
are preferably present in a minor amount of less than 50% by
weight, preferably less than 30% by weight, more preferably less
than 20% by weight, even more preferably less than 10% by weight of
the total weight of the dry waste plastic. Preferably, the
individual content of any less desirable plastic is less than 5% by
weight, more preferably less than 2% by weight based on the total
weight of the dry waste plastic.
[0017] Preferably, the plastics waste starting material comprises
one or more thermoplastic polymers and is essentially free of
thermosetting polymers. Essentially free in this regard is intended
to denote a content of thermosetting polymers of less than 15,
preferably less than 10 and even more preferably less than 5 wt %
of the composition.
[0018] Usually, waste plastic contains other non-desired
components, namely foreign material, such as paper, glass, stone,
metal, etc.
[0019] In the context of the present invention whenever it is
referred to the weight of the waste plastic or the weight of the
polystyrene and polyolefin in the mixed waste plastic, this weight
relates to the weight of the dry plastic without any foreign
material being admixed with the plastic. However, the weight
includes any components in the plastic, such as the above described
additives.
[0020] The present inventors found that when using a catalyst
comprising a zeolite-type catalyst, at a weight ratio of catalyst
to mixed waste plastic in the reactor of above 1:10, the addition
of polystyrene to polyolefin plastic surprisingly has a significant
impact on product distribution. Contrary to what was reported by
K.-H. Lee (see above cited references), the inventors found that
higher ratios of polystyrene in the mixed waste plastic lead to
higher contents of diesel and waxes in the product stream obtained
from the reactor. Thus, the process of the present invention allows
modifying the selectivity of the product with respect to higher
selectivity to diesel and waxes and lower selectivity to gases and
gasoline. It was for example found that wax production even doubles
when 15% of polystyrene is present in the mixed waste plastic.
[0021] It was furthermore found that in the process of the present
invention the diesel quality is improved with respect to an
increased concentration of saturated compounds and a decreased
concentration of unsaturated compounds, in particular aromatic
compounds. This finding is particularly unexpected as the addition
of polystyrene (an aromatic based polymer) should lead to a higher
content of unsaturated and in particular aromatic compounds. At the
same time, the also obtained gasoline fraction maintains its high
level of quality with respect to Research Octane Number (RON) and
Motor Octane Number (MON).
[0022] It was found that the above advantages are achieved if the
mixed waste plastic contains from 2 to 50% by weight of
polystyrene, preferably from 2 to 40% by weight, more preferably
from 2 to 30% by weight and even more preferably from 2 to 20% by
weight of polystyrene, based on the total weight of polystyrene and
polyolefin in the mixed waste plastic. Most preferably, the mixed
waste plastic contains from 2 to 15% by weight, such as from 5 to
15% by weight of polystyrene based on the total weight of
polystyrene and polyolefin in the mixed waste plastic.
[0023] The process of the present invention is also characterized
in that the weight ratio of catalyst to mixed waste plastic in the
reactor is above 1:10. Preferably, the weight ratio of catalyst to
mixed waste plastic in the reactor is above 1:9, more preferably
above 1:8, more preferably above 1:7, more preferably above 1:6,
more preferably above 1:5, more preferably above 1:4 and even more
preferably above 1:3, such as above 1:2. A particularly preferred
weight ratio of catalyst to mixed waste plastic in the reactor is
about 1:1.5.
[0024] The weight ratio of catalyst to mixed waste plastic in the
reactor can be below 10:1, preferably below 7:1. Thus, the weight
ratio of catalyst to mixed waste plastic in the reactor can be for
example in the range of from 1:9 to 10:1, preferably from 1:8 to
10:1, preferably from 1:7 to 10:1, preferably from 1:6 to 10:1,
preferably from 1:5 to 10:1, preferably from 1:4 to 10:1,
preferably from 1:3 to 10:1 and even more preferably from 1:2 to
10:1 or from 1:2 to 7:1.
[0025] The catalyst used in the process of the present invention
comprises a zeolite-type catalyst. In one embodiment, the catalyst
predominantly is a zeolite-type catalyst. In a further embodiment,
the catalyst consists of a zeolite-type catalyst. In a third
embodiment, the catalyst additionally comprises a further catalyst,
in particular an amorphous-type catalyst.
[0026] The embodiment in which the catalyst predominantly is a
zeolite-type catalyst is preferred. In this context, the term
"predominantly" defines a catalyst which is a mixture of a
zeolite-type catalyst and a non-zeolite-type catalyst, such as an
amorphous catalyst, but wherein the catalyst comprises more than
50% by weight of the zeolite-type catalyst based on the total
weight of the catalyst. Preferably, the catalyst comprises more
than 60%, more preferably more than 70%, even more preferably more
than 80% and most preferably more than 90% of the zeolite-type
catalyst. The catalyst can comprise a single zeolite-type catalyst
or a mixture of two or more zeolite-type catalysts.
[0027] As catalyst all types of FCC catalysts may be used. FCC
catalysts are well known to the person skilled in the art. For
example, the zeolite-type catalyst may be selected from crystalline
microporous zeolites which are known to the person skilled in the
art and which are commercially available. Preferred examples for
zeolite-type catalysts are described in WO 2010/135273, the content
of which is incorporated herein by reference. Specific examples for
suitable zeolite-type catalysts include but are not limited to
ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-50, TS-1, TS-2,
SSZ-46, MCM-22, MCM-49, FU-9, PSH-3, ITQ-1, EU-1, NU-10,
silicalite-1, silicalite-2, boralite-C, boralite-D, BCA, and
mixtures thereof.
[0028] If the catalyst additionally comprises an amorphous-type
catalyst, this may comprise silica, alumina, kaolin, or a mixture
thereof. Silica, in particular in the form of sand, is a well known
for FCC catalytic applications. Preferred amorphous-type catalysts
comprise at least 60% by weight, preferably at least 70% by weight
and even more preferably at least 80% by weight of
silica-equivalent of an oxidic compound based on silicon like
silica (SiO.sub.2), kaolin, etc.
[0029] The catalyst can be fresh catalyst, equilibrated catalyst
(such as spent catalyst), or a mixture thereof.
[0030] The mixed waste plastic and the catalyst comprising the
zeolite-type catalyst can be introduced within the reactor
simultaneously or subsequently. Furthermore, the mixed waste
plastic and the catalyst comprising the zeolite-type catalyst can
be introduced within the reactor batchwise or continuously.
[0031] The skilled person is aware of suitable apparatus and
equipment for carrying out the process in accordance with the
present invention and will select the suitable system based on his
professional experience, so that no further extensive details need
to be given here. However, without willing to be bound to theory,
some examples of reactor technologies that can be effectively used
to carry out the invention comprise the stirred reactor, the rotary
kiln, the bubbling fluidized bed reactor and the circulating
fluidized bed reactor riser or downer. The rotary kiln is a
cylindrical vessel, inclined slightly to the horizontal, which is
rotated slowly about its axis. The material to be processed is fed
into the upper end of the cylinder. As the kiln rotates, material
gradually moves down towards the lower end, and may undergo a
certain amount of stirring and mixing. In a bubbling fluidized bed
reactor a fluid (gas or liquid) is passed through the catalyst
particles at high enough velocities to suspend the catalyst and
cause it to behave as though it were a fluid. In a circulating
fluidized bed, also called transport reactor, the catalyst and the
fluid flow co-currently at high speed. Generally a cyclone system
is used to separate the fluid, which can undergo downstream
processing, from the solid, which is recirculated to the reactor.
These reactors can be either upflow for risers, or downflow for
downers.
[0032] Preferably, they are introduced continuously. In one
embodiment, the whole process is conducted continuously.
[0033] In the reactor, in presence of the catalyst, at least a
portion of the mixed waste plastic is converted to liquid fuels and
waxes. This conversion preferably takes place at an elevated
temperature of for example above 350.degree. C., preferably above
400.degree. C., more preferably above 410.degree. C. Suitably, the
conversion tales place at a temperature in the range of above
410.degree. C. to 500.degree. C., more preferably in the range of
from 420.degree. C. to 450.degree. C., such as about 425.degree.
C.
[0034] The effect of the polystyrene content in the mixed waste
plastic at a high weight ratio of catalyst to mixed waste plastic
in the reactor is now explained in more detail with reference to
the following examples and the attached figures which show in
[0035] FIG. 1 the effect of polystyrene loading on selectivity,
[0036] FIG. 2 the effect of polystyrene loading on the quality of
the diesel fraction, and
[0037] FIG. 3 the effect of polystyrene loading on the quality of
the gasoline fraction.
[0038] The examples below were conducted according to the following
general experimental procedure:
[0039] In each catalytic run in semibatch mode, 30 g of plastic
(high density polyethylene (HDPE) and variable amounts of
polystyrene (PS)) and a defined amount of the catalyst were loaded
inside the reactor. The reactor was closed and heated from room
temperature to 200.degree. C. during 20 minutes, while
simultaneously purging with a 150 mL/min nitrogen flow. When the
internal temperature reached the melting point of the plastic,
stirring was started and was slowly increased until 690 rpm. The
temperature was held at 200.degree. C. for 25-30 minutes. During
this heating process, nitrogen coming out from the reactor was not
collected.
[0040] After this first pretreatment step, the temperature was
increased to the reaction temperature at a heating rate of
10.degree. C./min, and the collection of gases and nitrogen in the
corresponding gas sampling bag was started. When the internal
temperature reached the reaction temperature, the circulation of
the gaseous products was commuted to another pair of glass traps
and corresponding gas sampling bag. This was considered as the zero
reaction time.
[0041] During selected time periods, liquid and gaseous products
were collected in a pair of glass traps and their associated gas
sampling bag, respectively. At the end of the experiment the
reactor was cooled to room temperature. During this cooling step,
liquids and gases were also collected.
[0042] The reaction products were classified into 3 groups: i)
gases, ii) liquid hydrocarbons and iii) residue (waxy compounds,
ashes and coke accumulated on the catalyst). Quantification of the
gases was done by gas chromatography (GC) using nitrogen as the
internal standard, while quantification of liquids and residue was
done by weight.
[0043] The simulated distillation (SIM-DIS) GC method allowed the
determination of the different fractions in the liquid samples
(according to the selected cuts); the detailed hydrocarbon analysis
(DHA) GC method allowed the determination of the PIONA (paraffins,
iso-paraffins, olefins, napthenes, aromatics) components in the
gasoline fraction of the last withdrawn sample (C5-C11: Boiling
point<216.1.degree. C.; what includes C5-C6 in the gas sample
and C5-C11 in the liquid samples), and GC.times.GC allowed the
determination of saturates (everything that is not aromatic),
mono-, di- and tri-aromatics in the diesel fraction of the last
withdrawn liquid samples (C12-C21; 216.1<BP<359.degree.
C.).
[0044] Should the disclosure of any patents, patent applications,
and publications which are incorporated herein by reference
conflict with the description of the present application to the
extent that it may render a term unclear, the present description
shall take precedence.
EXAMPLE 1
[0045] The experiment was carried out following the general
procedure described above. In this example, the raw material was
pure HDPE (labelled 100HDPE). Reaction temperature was set at
425.degree. C. In this example, 20 g of zeolite-type catalyst were
used (catalyst: spent FCC catalyst provided by FCC Equilibrium
Catalyst, Inc.). Catalyst to plastic weight ratio was equal to
20/30.
EXAMPLE 2
[0046] The experiment was carried out following the general
procedure described above. In this example, the raw material is a
mixture containing 95 wt. % HDPE and 5 wt. % PS (labelled
95HDPE-5PS). Reaction temperature was set at 425.degree. C. In this
example, 20 g of zeolite-type catalyst have been used (catalyst:
spent FCC catalyst provided by FCC Equilibrium Catalyst, Inc.).
Catalyst to plastic weight ratio was equal to 20/30.
EXAMPLE 3
[0047] The experiment was carried out following the general
procedure described above. In this example, the raw material was a
mixture containing 90 wt. % HDPE and 10 wt. % PS (labelled
90HDPE-10PS). Reaction temperature was set at 425.degree. C. In
this example, 20 g of zeolite-type catalyst were used (catalyst:
spent FCC catalyst provided by FCC Equilibrium Catalyst, Inc.).
Catalyst to plastic weight ratio was equal to 20/30.
EXAMPLE 4
[0048] The experiment was carried out following the general
procedure described above. In this example, the raw material was a
mixture containing 85 wt. % HDPE and 15 wt. % PS (labelled
85HDPE-15PS). Reaction temperature was set at 425.degree. C. In
this example, 20 g of zeolite-type catalyst were used (catalyst:
spent FCC catalyst provided by FCC Equilibrium Catalyst, Inc.).
Catalyst to plastic weight ratio was equal to 20/30.
[0049] The effect of polystyrene loading on the selectivity of the
process is shown in FIG. 1. It is evident that the selectivity for
gases and gasoline decreases with increasing polystyrene loading
while the selectivity for diesel and waxes increases.
[0050] However, contrary to the expectation of the skilled person
and contrary to what is described in the prior art, the process of
the present invention provides a diesel fraction which in
particular at low polystyrene loading comprises an even decreased
amount of aromatic compounds. This effect is shown in FIG. 2, which
provides the amounts of saturated (S), monoaromatic (MA),
diaromatic (DA), triaromatic (TA) and polyaromatic (PA) compounds
in the obtained diesel fractions depending on the polystyrene
loading.
[0051] FIG. 3 shows the effect of the polystyrene loading on the
quality of the gasoline fraction (P: paraffins, I: iso-paraffins,
O: olefins, N: naphthenes, A: aromatics, U: unidentified). FIG. 3
additionally shows the RON and MON of the gasoline fractions
obtained with different polystyrene loadings.
[0052] FIGS. 1, 2 and 3 additionally provide the conversion (X) of
the mixed waste plastic in each run.
* * * * *