Note: Descriptions are shown in the official language in which they were submitted.
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PROCESSING OF STABILISED COMPOSITIONS COMPRISING OLEFINS
Field of the invention
The present invention relates to the processing of stabilised compositions
comprising hydrocarbon stream resulting from the liquefaction of plastic
wastes by
pyrolysis or hydrothermal treatment. In particular, the present invention
pertains to novel
compositions for inhibiting polymerization in industrial plant of hydrocarbon
streams
obtained from liquefaction of plastic waste, which contain reactive
hydrocarbons and
potentially oxygenates, thereby preventing fouling in processing equipment.
Background of the invention
Common industrial methods for recycling hydrocarbons from plastic include
liquefaction by pyrolysis or hydrothermal treatment of waste plastic that
otherwise could
have ended in landfill or incinerator, followed by purification including
hydrotreatment
and contaminant removal using a variety of purification processes such as
distillation.
Pyrolysis or hydrothermal treatment transforms plastics, and most of their
additives and contaminants, into gaseous chemicals while most of the non-
volatile
contaminants or additives end up in the solid by-product; chars or ashes. In
principle,
any kind of plastic waste can be converted, although some pre-sorting of non-
organic
waste is desired and purification of the output material is necessary as
several hetero-
elements (i.e. presently referred to as elements different of carbon, hydrogen
or oxygen)
may be volatilized.
Plastic waste is a complex and heterogeneous material, due to several factors.
First, plastic as material refers to numerous different polymers with
different chemical
properties that need to be separated from each other prior to recycling. The
main
polymers found in plastic from municipal solid waste are polyethylene
terephthalate
(PET), polyethylene (PE), polypropylene (PP) and polystyrene (PS). Other
polymers
essentially include polyurethanes, polyam ides (PA), polycarbonates,
polyethers and
polyesters other than PET. Second, many different additives are introduced
during the
production phase to adjust or improve the properties of the plastic or to
fulfil specific
requirements. These include additives such as functional additives
(stabilizers, antistatic
agents, flame retardants, plasticizers, lubricants, slipping agents, curing
agents, foaming
agents, biocides, antioxidants etc.), dyes and pigments, fillers (e.g. glass
fibers, talcum,
carbon fibers, carbon nanotubes), commonly used in plastic packaging as well
as
additives such as flame retardants, frequently used in plastic for
electronics. In addition,
several metal compounds are purposely added during plastic production (often
as
oxides, carbonates, acids, etc.). Beside additives containing hetero elements
other than
metals are used in making plastics, for instance halogens such as bromine in
flame
retardants, plasticizers, stabilizers etc.
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Silicone polymers, which are silicon containing organic materials, are often
used
in plastic formulations. Thanks to their surface characteristics, applications
for silicones
range from silicone rubbers, used as sealants for joints, to silicone
surfactants for
cosmetic products while they are increasingly used in the plastics sector, as
process
enhancing additives (processing aids), and for the modification of polymers.
On top of these hetero-elements, the used plastic waste can have been
contaminated during lifespan by remains of liquids with which they were in
contact
(beverages, personal-care products, etc.) and of food that can also introduce
contamination of the plastic. Last, some plastic waste may be present in the
form of
partially decomposed waste, such as partly burnt plastic.
Finally, as plastics are contaminated by oxygenates, pyrolysis or hydrothermal
liquefaction plastic oils may also contain oxygenates such as aldehydes or
ketones.
Pyrolysis or hydrothermal liquefaction of plastic waste allows producing
naphtha,
ethylene, propylene and aromatics but, as previously mentioned, those products
are
polluted by many hetero elements originating from the waste plastic itself. In
particular,
significant concentration of silicon and of organic silicon can be found in
pyrolysis or
hydrothermal liquefaction plastic oils. Although many prior art processes were
focused
on the removal of chlorine compounds, other impurities in the pyrolysis or
hydrothermal
liquefaction plastic oil simply forbid the direct use of pyrolysis or
hydrothermal
liquefaction plastic oil in other processes such as steam cracking. Indeed,
steam
crackers are very sensitive to the presence of olefins or dienes in the feed
and to the
presence of silicon or of organic silicon compounds. Moreover, oxygenates
present in
pyrolysis or hydrothermal liquefaction plastic oil are capable to be converted
to peroxides
and so enhance polymer and gums formation. In particular, the presence of
olefins and
oxygenates may result in undesirable polymerisation during storage, transport
from the
production place to further treatment place as well as during purification and
further
processing treatments.
In particular, purification operations are often carried out at elevated
temperatures which can increase the rate of undesired polymerization.
Polymerization,
such as thermal polymerization, during hydrocarbon processing treatments,
results not
only in product loss, but also in loss of production efficiency caused by the
formation of
fouling deposits and their deposition on process equipment, particularly on
the heat
transfer surfaces of the processing equipment. More specifically the
processing may
include, for example, preheating, hydrogenation, fractionation, extraction,
hydrocracking,
vapocracking, fluid catalytic cracking, and the like of hydrocarbon streams to
remove,
concentrate, or have added thereto the unsaturated hydrocarbons prior to
storage or
use. These deposits decrease the thermal efficiency of the equipment and
decrease the
separation efficiency of the distillation towers. In addition, operating
modifications to
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reduce the rate of fouling can result in reduced production capacity. The
excessive build-
up of such deposits can cause plugging in tower plates, transfer tubes, and
process lines,
which could result in unplanned shutdowns.
Undesirable polymerization may also cause operational problems such as
increase in fluid viscosity, temperature, restricted flow in pipelines, and
blocking of filters.
In heat requiring operations, such deposition adversely affects heat transfer
efficiency.
The behaviour of compositions produced from pyrolysis or hydrothermal
liquefaction of waste plastic is difficult to forecast due to the complexity
of such
compositions. For example, analysis by gas chromatography of pyrolysis plastic
oil only
allows identification of 25 to 45wt% of the compounds containing oxygen and
azote.
Moreover, such undesirable polymerisation is generally monitored by measuring
the gum
content.
There is therefore a need for a stabilized composition comprising liquefaction
plastic oil obtained by pyrolysis or hydrothermal treatment.
Brief summary of the invention
The present invention is a composition stabilized against premature
polymerization comprising:
a) a hydrocarbon stream having a diene value of at least 0.5 g 12/100 g as
measured
according to UOP 326, a bromine number of at least 5 g Br2/ 100g as measured
according to ASTM D1159, and containing at least 1wt%, or at least 2 wt%, of
plastic
liquefied oil which is containing contaminants, wherein said contaminants
comprise
constituents which are not boiling below 700 C, preferably not below 600 C,
such as
gums in the form of plastic oligomers and residues of liquefaction of plastic,
optionally
metals and optionally solids, the remaining part of said hydrocarbon stream
being a
diluent,
b) at least one additive capable to reduce gums formation or buildup,
c) optionally at least one additive which is a dispersant agent.
In one embodiment, the plastic liquefied oil contained in the hydrocarbon
stream
is a plastic pyrolysis oil.
In a first embodiment of the invention, the stabilized composition comprises:
a) a hydrocarbon stream as defined above,
b) at least one additive capable to reduce gums formation or buildup
selected from hindered phenols including metal salts thereof, and
C) at least one additive which is a dispersant agent.
In the first embodiment, said at least one additive capable to reduce gums
formation or buildup may be selected from hindered phenols, advantageously
including
metal salts thereof, and said at least one dispersant agent may be selected
from
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alkylbenzene sulfonates in which the alkyl group contains 8-18 carbons, metal
sulfonates
and alkenyl succinimides.
In particular, the additive capable to reduce gums formation or buildup may be
a
hindered phenol and the dispersant agent may be a polyisobutylene succinimide.
More specifically, the additive capable to reduce gums formation or buildup
may
be selected from 4-tert butylcatechol (TBC); 2,6-di tertbutylphenol; butylated
hydroxyltoluene (BHT) and the at least one dispersant agent may be a
polyisobutylene
succinimide, in particular of CAS n 84605-20-9.
In a second embodiment of the invention, the stabilized composition comprises:
a) a hydrocarbon stream as defined above,
b) at least one additive capable to reduce gums formation or buildup which
is the product of tall oil fatty acids reacted with a polyamine,
c) optionally at least one additive which is a dispersant agent.
Preferably, component c) is not present.
In the second embodiment, the additive capable to reduce gums formation or
buildup is the product of tall oil fatty acids reacted with a polyalkylene
polyamine, such
as a polyethylene polyamine. The polyamine may optionally be selected from
diethylenetriamine, triethylenetetramine, or tetraethylenepentamine,
preferably
diethylenetriamine.
In any of the previous embodiments, optionally, the stabilized composition may
further comprise:
d) at least one other additive which is a metal passivator and/or a metal
chelating agent.
In any embodiment, other additives capable to reduce gums formation or buildup
and/or dispersant agent may optionally be present in the composition, as the
ones
disclosed in the present specification.
In one embodiment of the invention, at least one additive capable to reduce
gums
formation or buildup and at least one dispersant agent are present.
In one embodiment, the additive capable to reduce gums formation or buildup is
an antipolymerant such as a stable free radical or a precursor thereof, such
as
hydroxylamines. The antipolymerant can be a stable nitroxide free radical
and/or a
hydroxylamine substituted with at least one alkyl, aryl or alkylaryl group.
In one embodiment, the additive capable to reduce gums formation or buildup is
selected among the unhindered phenols, the hindered phenols, the aminophenols,
the
phenylenediamines and mixtures thereof.
In one embodiment, said at least one additive which is a dispersant agent is
selected from products of reaction between a phenol substituted with a C9-110
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hydrocarbon chain, an aldehyde and an amine or polyamine or ammonia, from
alkenyl
succinimides or mixtures thereof.
The present invention also concerns a process for preparing a composition
stabilized against premature polymerization, comprising:
5 (a) providing a hydrocarbon stream having a diene value of at least
0.5 g 12/100
g as measured according to UOP 326, a bromine number of at least 5 g Br2/ 100g
as
measured according to ASTM D1159, and containing at least 1wt%, or 2 wt%, of
plastic
liquefied oil which is containing contaminants, wherein said contaminants
comprise
constituents which are not boiling below 700 C, preferably not below 600 C,
such as
gums in the form of plastic oligomers and residues of liquefaction of plastic,
optionally
metals and optionally solids, the remaining part of said hydrocarbon stream
being a
diluent,
(b) adding to the hydrocarbon stream provided in step (a) at least one
additive
capable to reduce gums formation or buildup,
(c) optionally adding to the hydrocarbon stream provided in step (a) at least
one
additive which is a dispersant agent,
(d) optionally adding to the hydrocarbon stream provided in step (a) at least
one
other additive which is a metal passivator and/or a metal chelating agent.
In one embodiment, the plastic liquefied oil contained in the hydrocarbon
stream
provided in step (a) is a plastic pyrolysis oil.
In a first embodiment, the process comprises:
(a) providing a hydrocarbon stream as defined above,
(b) adding to the hydrocarbon stream provided in step (a) at least one
additive capable to reduce gums formation or buildup selected from hindered
phenols
including metal salts thereof and (c) adding at least one additive which is a
dispersant
agent,
In a second embodiment, the process comprises:
(a) providing a hydrocarbon stream as defined above,
(b) adding to the hydrocarbon stream provided in step (a) at least one
additive capable to reduce gums formation or buildup which is the product of
tall oil
fatty acids reacted with a polyamine, and optionally (c) adding to the
hydrocarbon
stream provided in step (a) at least one additive which is a dispersant agent.
In any of the above embodiments, the process may further comprise:
(d) adding to the hydrocarbon stream provided in step
(a) at least one other
additive which is a metal passivator and/or a metal chelating agent.
In any of the above embodiments, the additives are advantageously as
previously defined for the composition of the invention.
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The present invention also concerns a process for the processing of a
corn position stabilized against premature polymerization, comprising:
(a)
providing a composition stabilized against premature polymerization as
claimed in the present invention,
(b) optionally
submitting the composition provided in step (a) to an
evaporation step under operating conditions efficient to obtain a composition
containing
a reduced amount of additives,
(C)
the stabilized composition provided in step (a) or the composition
containing a reduced amount of additives provided in step (b) is (i) processed
in a
steamcracker, (ii) processed in a fluid catalytic cracker, (iii) processed in
a
hydroprocessing unit, (iv) processed in an -isomerisation unit and/or (v)
separated into
usable streams for the preparation of fuels such as LPG, naphtha, gas oil,
heavy fuel oil
and/or for the preparation of lubricants.
In an embodiment, prior to step (b) or prior to step (c), the stabilized
composition
provided in step (a) may be submitted to a purification step to trap silicon
and/or metals
and/or phosphorous and/or halogenates over at least one trap to obtain a
purified
stabilized composition.
In an embodiment, the hydroprocessing unit may include at least one guard bed
to trap solid particles.
In an embodiment, step (c) may be performed at temperatures of 200 C or more
or may include at least one treatment performed at a temperature of 200 C or
more.
Step (c) may include one or several of the following features:
(i) the processing in a steamcracker is performed at temperatures from 800 C
to 1200 C;
(ii) the processing in a fluid catalytic cracker is performed at temperatures
from 500 C to
550 C,
(iii) the processing in a hydroprocessing unit is performed at temperatures
from 100 C
to 500 C,
(iv) the processing in the isomerization unit is performed at temperatures
from 250 C to
400 C,
(v) the separation into usable streams is performed by distillation.
The use of these novel stabilized compositions prevents fouling of equipment
and
product during handling, processing, purification, and storage.
In particular, the composition is stabilized against premature polymerization
without being contacted with, and/or without any use of, a solid removal
material that
requires a further separation step. In particular, the present invention does
not require
the use/presence of solid material suitable for removing oxygen, metals,
phosphorous,
halogens and/or nitrogen contained in pyrolysis plastic oil or in liquefaction
hydrothermal
plastic oil, whatever the form of oxygen, metals, phosphorous, halogens and/or
nitrogen.
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Such solid removal materials include silica gel, alumina, promoted alumina,
inorganic
materials such as clay, pillared clay, apatite, hydroxyapatite, alkaline or
alkaline earth
metal oxide, calcined alumina, boehmite, bayerite, hydrotalcite, spine!, acid-
exchanged
clay, molecular sieves (which are alkaline or alkaline earth metal containing
alumino-
silicate sieves 3A, 4A, 5A or 13X).
Definitions
The terms "alkane" or "alkanes" as used herein describe acyclic branched or
unbranched hydrocarbons having the general formula CnH2n+2, and therefore
consisting
entirely of hydrogen atoms and saturated carbon atoms; see e.g. I UPAC.
Compendium
of Chemical Terminology, 2nd ed. (1997). The term "alkanes" accordingly
describes
unbranched alkanes ("normal-paraffins" or "n-paraffins" or "n-alkanes" or
"paraffins") and
branched alkanes ("iso-paraffins" or "iso-alkanes") but excludes naphthenes
(cycloalkanes). They are sometimes referred to by the symbol "HC-".
The terms "olefin", "olefins", "alkene" or "alkenes" as used herein relate to
an
unsaturated hydrocarbon compound containing at least one carbon-carbon double
bond.
They are sometimes referred to by the symbol "HC=".
The terms "alkyne" or "alkynes" as used herein relate to an unsaturated
hydrocarbon compound containing at least one carbon-carbon triple bond.
The term "hydrocarbon" or "hydrocarbons" refers to the alkanes (saturated
hydrocarbons), cycloalkanes, aromatics and unsaturated hydrocarbons alone or
in
combination.
As used herein, the terms "Ca alcohols", "Ca alkenes", or "Ca hydrocarbons",
wherein "a" is a positive integer, is meant to describe respectively all
alcohols, alkenes
or hydrocarbons having a carbon atoms. Moreover, the term "Ca+ alcohols", "Ca-
F
alkenes", or "Ca+ hydrocarbons", is meant to describe all alcohol molecules,
alkene
molecules or hydrocarbons molecules having a or more carbon atoms.
Accordingly, the
expression "C5+ alcohols" is meant to describe a mixture of alcohols having 5
or more
carbon atoms.
As used herein, the terms "silicon", "metals", "phosphorous", "halogens",
"nitrogen" and "oxygen" refer to their respective chemical elements contained
in the
stream to be purified.
Weight hourly space velocity (WHSV) is defined as the hourly weight of flow
per
unit weight of catalyst and liquid hourly space velocity (LHSV) is defined as
the hourly
volume of flow per unit of volume of catalyst.
The terms "comprising", and "comprises" as used herein are synonymous with
"including", "includes" or "containing", "contains", and are inclusive or open-
ended and
do not exclude additional, non-recited members, elements or method steps.
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The recitation of numerical ranges by endpoints includes all integer numbers
and,
where appropriate, fractions subsumed within that range (e.g. 1 to 5 can
include 1, 2, 3,
4 when referring to, for example, a number of elements, and can also include
1.5, 2, 2.75
and 3.80, when referring to, for example, measurements). The recitation of
endpoints
also includes the recited endpoint values themselves (e.g. from 1.0 to 5.0
includes both
1.0 and 5.0). Any numerical range recited herein is intended to include all
sub-ranges
subsumed therein.
The term "conversion" means the mole fraction (i.e., percent) of a reactant
converted to a product or products. The term "selectivity" refers to the
percent of
converted reactant that went to a specified product.
The terms "wt%", "vol%", or "molc)/0" refers to a weight, volume, or molar
percentage of a component, respectively, based on the total weight, the total
volume of
material, or total moles, that includes the component In a non-limiting
example, 10
grams of component within 100 grams of the material is 10 wt% of components.
Unless otherwise specified, "wtppm" or "ppm" each equally refer to "parts per
million" and are given based on weight. For instance, "100 ppm" shall mean 100
ppm by
weight. Similarly, the term "wtppb" or "ppb" refers to "parts per billion" and
are given
based on weight.
The term "naphtha" refers to the general definition used in the oil and gas
industry. Naphtha refers to a hydrocarbon originating from crude oil
distillation having a
boiling range from 15 to 250 C as measured by ASTM D2887. Naphtha contains
substantially no olefin as the hydrocarbons originates from crude oil. It is
generally
considered that a naphtha has carbon number between C3 and C11, although the
carbon
number can reach in some case C15. It is also generally admitted that the
density of
naphtha ranges from 0.65 to 0.77 g/mL.
The term "gas oil" refers to the general definition used in the oil and gas
industry.
It refers to a hydrocarbon originating from crude oil distillation having a
boiling range from
210 to 360 C as measured by ASTM D86. Gas oil contains substantially no olefin
as the
hydrocarbons originates from crude oil. It is generally considered that a gas
oil has
carbon number between C12 and C20, although the carbon number can reach in
some
case C25. It is also generally admitted that the density of gas oil ranges
from 0.82 to 0.86
g/mL, wherein commercial specification limits density to 0.86 g/mL according
to ASTM
D1298 (ISO 3675, IF 160).
The term "LPG" refers to the general definition used in the oil and gas
industry. It
refers to a hydrocarbon essentially comprised of 03 (propane) with some 04
isomers; n-
butane and isobutene.
The term "liquefaction plastic oil" or "plastic liquefied oil" or "liquefied
waste
plastic" refers to the liquid products resulting from the pyrolysis of plastic
and/or from the
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hydrothermal liquefaction of plastic, alone or in mixture and generally in the
form of
plastic waste, optionally in mixture with at least one other waste such as an
elastomer,
for example latex optionally vulcanized or tyre, and/or biomass, e.g. selected
from
lignocellulosic biomass, paper and board.
The biomass may be defined as a vegetal or animal organic product including
residues and organic waste. Biomass includes (i) the biomass produced by the
surplus
of agricultural land, not used for human or animal food: dedicated crops,
called energy
crops; (ii) the biomass produced by the deforestation (forest maintenance) or
the
cleaning of agricultural land; (iii) agricultural residues from cereal crops,
vineyards,
orchards, olive trees, fruits and vegetables, residues from the agri-food
industry,... (iv)
forestry residues from forestry and wood processing; (v) agricultural residues
from
livestock farming (manure, slurry, litter, droppings, etc.); (vi) organic
waste from
households (paper, cardboard, green waste, etc.); (vii) ordinary industrial
organic waste
(paper, cardboard, wood, putrescible waste, etc.). The liquefaction plastic
oil processed
by the invention can be derived from the liquefaction of waste containing at
least 1%m/m,
optionally 1-50%m/m, 2-30%m/m, or in a range defined by any two of these
limits, of one
or more of the aforementioned biomasses, residues and organic waste materials,
and
the remainder being waste plastics, optionally in admixture with elastomers.
Elastomers are linear or branched polymers transformed by vulcanization into
an
infusible and insoluble three-dimensional weakly cross-linked network. They
include
natural or synthetic rubbers. They can be part of tire waste or any other
household or
industrial waste containing elastomers, natural and/or synthetic rubber, mixed
or not with
other components, such as plastics, plasticizers, fillers, vulcanizing agents,
vulcanization
gas pedals, additives, etc. Examples of elastomeric polymers include ethylene-
propylene
copolymers, ethylene-propylene-diene terpolymer (EPDM), polyisoprene (natural
or
synthetic), polybutadiene, styrene-butadiene copolymers isobutene-based
polymers,
isobutylene-isoprene copolymers, chlorinated or brominated, acrylonitrile
butadiene
copolymers (NBR), and polychloroprenes (CR), polyurethanes, silicone
elastomers, etc.
The plastic liquefaction oil processed by the invention can be derived from
the
liquefaction of waste materials containing at least 1%m/m, optionally 1-
50%m/m, 2-
30 /0m/m or in a range defined by any two of these limits, of one or more of
the
aforementioned elastomers, especially in the form of waste materials, with the
remainder
being waste plastics, optionally in admixture with biomass, residues, and
organic waste
materials.
The term "pyrolysis plastic oil", "plastic pyrolysis oil" or "oil resulting
from
the pyrolysis of plastic" refers to the liquid products obtained once waste
plastic or
plastic waste have been thermally pyrolyzed. The pyrolysis process shall be
understood
as an unselective thermal cracking process.
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The term "hydrothermal plastic oil" or "oil resulting from the hydrothermal
liquefaction of plastic" refers to the liquid products obtained once waste
plastic or
plastic waste have been hydrothermally liquefied.
The plastic to be pyrolyzed or hydrothermally liquefied can be of any type.
For
5
instance, the plastic can be polyethylene, polypropylene, polystyrene,
polyester,
polyamide, polycarbonate, etc. These liquefaction plastic oils contain
paraffins, i-
paraffins (iso-paraffins), dienes, alkynes, olefins, naphthenes, and aromatic
components. Liquefied plastic oil may also contain impurities such as organic
chlorides,
oxygenated and/or silylated organic compounds, organic silicon compounds,
metals,
10
salts, phosphorous, sulfur and nitrogen compounds. The plastic used for
generating
liquefaction plastic oil is a waste plastic, irrespective of its origin or
nature. The
composition of the liquefaction plastic oil is dependent on the type of
plastic that is
liquefied. Liquefaction plastic oil is mainly (especially over 80wt%, most
often over
90wt%) constituted of hydrocarbons having from 1 to 150 carbon atoms and
impurities.
The term "Diene Value" (DV) or "Maleic Anhydride Value" (MAV) is a measure
of the conjugated double bonds (dienes) in the oil. For the Maleic Anhydride
Value
(MAV), one mole of Maleic anhydride corresponds to 1 mole of conjugated double
bond
and the result corresponds to the amount of maleic anhydride in milligrams
that will react
with 1 gram of oil. One known method to quantify dienes is the UOP 326-17:
Diene Value
by Maleic Anhydride Addition Reaction. The term "diene value" (DV) refers to a
similar
analytical method to quantify dienes by titration, which is expressed in g of
iodine per
100 g of sample. There is a correlation between the MAV = DV x 3,863 since 1
mole of
conjugated double bond is titrated by 1 mole of Maleic Anhydride or 1 mole of
Iodine.
The term "bromine number" corresponds to the amount of reacted bromine in
grams by 100 grams of sample. The number indicates the quantity of olefins in
a sample.
It is determined in grams of Br2 per 100 grams of sample (gBr2/100g) and can
be
measured according to ASTM D1159-07R17 method.
The term "boiling point" refers to boiling point generally used in the oil and
gas
industry. Boiling point is measured at atmospheric pressure. The initial
boiling point is
defined as the temperature value when the first bubble of vapor is formed. The
final
boiling point is the highest temperature that can be reached during a standard
distillation.
At this temperature, no more vapor can be driven over into the condensing
units. The
determination of the initial and final boiling points is known in the art.
Depending on the
boiling range of the mixture, various standardized methods can be used, such
as ASTM
D2887-19ae2 relating to the boiling range distribution of petroleum fractions
by gas
chromatography. For compositions containing heavier hydrocarbons ASTM D7169-05
may alternatively be used. Boiling range of distillates is advantageously
measured using
ASTM D7500, D86 or D1160.
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The concentration of metals in the matrix of hydrocarbon can be determined by
any method known in the art. Relevant characterization methods include XRF or
ICP-
AES or ICP-MS methods. Those skilled in the art know which method is the most
adapted
to each metal measurement and to which hydrocarbon matrix. Features,
structures,
characteristics or embodiments may be combined in any suitable manner, as
would be
apparent to a person skilled in the art from this disclosure, in one or more
embodiments.
Potential gums inform on the tendency of a fuel to form gum and deposits
under accelerated aging conditions. They give an indication on the stability
of a fuel
during its storage. Potential gums can be determined by means of method ASTM
D873-
12(2018).
Existing gums correspond to quantity of residue remaining after evaporation
of a fuel under specific conditions. They give an indication on the stability
of a fuel when
heated. Existing gums can be determined by means of method NF EN ISO 6246
(2018)
et ASTM D381-19.
"Induction period" corresponds to an initial low stage of a chemical reaction
in
the area of chemical kinetics. After the induction period, the reaction
accelerates. It may
be estimated by oxidation stability tests such as EN 16091:2022.
Detailed description of the invention
As regards the hydrocarbon stream, it has a diene value of at least 0.5 g
12/100
g, preferably at least 1 g 12/100 g, as measured according to UOP 326, a
bromine number
of at least 5 g Br2/ 100g as measured according to ASTM D1159.
The hydrocarbon stream contains at least 1wt%, or 2 wt%, of plastic liquefied
oil.
In a preferred embodiment, said hydrocarbon stream contains at least 5wt%,
preferably
at least 10wt%, more preferably at least 25 wt % of plastic liquefied oil,
most preferably
at least 50 wt% still more preferably 75 wt /0, even more preferably at least
90 wt % of
plastic liquefied oil. It is also possible to use pure plastic liquefied oil,
and this is the most
preferred embodiment. In the latter case, the hydrocarbon stream is only
consisting of
plastic liquefied oil.
Contaminants contained in plastic liquefied oil may comprise constituents
which
are not boiling below 700 C, preferably not below 600 C, such as gums in the
form of
plastic oligomers and residues of liquefactionof plastic, optionally metals
and optionally
solids.
Plastic liquefied oil typically comprises from 5 to 80 wt% of paraffins
(including
cyclo-paraffins), from 10 to 95 wt% w/w of unsaturated compounds (comprising
olefins,
dienes, acetylenes), from 5 to 70wt% of aromatics. These contents can be
determined
by gas chromatography.
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In particular, a plastic liquefied oil may comprise a Bromine Number of 20 to
130
g Br/100g and/or a Maleic Anhydride Index (U0P326-82) of 1 to 55 mg Maleic
Anhydride/1g .
Advantageously, the plastic liquefied oil is originating from the stream of
liquefied
waste plastic for which the Cl to C4 hydrocarbons have been removed and/or the
components having a boiling point higher than 350 C have been removed and/or
preferably further converted i a FCC, or a hydrocracking unit, a coker or a
visbreaker or
blended in crude oil or crude oil cut to be further refined.
The other component of said hydrocarbon stream may include any diluent or
hydrocarbon stream miscible with the plastic liquefied oil. Such diluent
preferably has a
diene value of at most 0.5 g 12/100 g as measured according to UOP 326-17, a
bromine
number of at most 5 g Br2/ 100g as measured according to ASTM D1159.
The diluent or hydrocarbon stream according to the invention is preferably
selected from a naphtha and/or a paraffinic solvent and/or a diesel or a
straight run
gasoil, containing at most 1 wt% of sulfur, preferably at most 0.1 wt% of
sulfur, and/or a
hydrocarbon stream having a boiling range between 50 C and 150 C or a boiling
range
between 150 C and 250 C or a boiling range between 200 C and 350 C, having
preferably a bromine number of at most 5 gBr2/100g, and/or a diene value of at
most 0.5
g12/100g or any combination thereof.
In any of the embodiments of the invention, the above-mentioned plastic
liquefied
oil my preferably be a pyrolysis plastic oil.
As regards the additives capable to reduce gums formation or buildup, one
can cite an antipolymerant such as a stable free radical or a precursor
thereof, such as
a hydroxylamine compound.
Any stable free radical (or precursor thereof under conditions which produce
the
stable free radical in situ) as defined may be used in the present invention.
The stable
free radicals suitable for use in this invention may be selected from, but are
not limited
to, the following groups of chemicals: nitroxides (e.g., di-tert
butylnitroxide), hindered
phenoxys (e.g., galvinoxyl), hydrazyls (e.g., diphenylpicrylhydrazyl), and
stabilized
hydrocarbon radicals (e.g., triphenylmethyl), as well as polyradicals,
preferably biradicals
of these types. In addition, certain precursors that produce stable free
radicals in situ
may be selected from the following groups: nitrones, nitrosos, thioketones,
benzoquinones, amines and hydroxylamines.
These stable free radicals exist over a wide range of temperatures up to about
260 C. A limiting factor in their use is the temperature of the processing
wherein they
are employed. Specifically, the present method applies to processing carried
on at
temperatures at which said stable free radical exists. Pressure has not been
seen to be
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13
significant to the present method, hence, atmospheric, sub or superatmospheric
conditions may be employed.
In an advantageous embodiment the stable free radical may be a stable
nitroxide
and may be substituted with at least one alkyl, aryl or alkylaryl group.
In an advantageous embodiment the hydroxylamine may be substituted with at
least one alkyl, aryl or alkylaryl group.
Preferably, the stable nitroxide free radical or the hydroxylamine may be
substituted with a straight or branched chain alkyl of 1 to 20 carbon atoms, a
straight or
branched chain alkyl of 1 to 20 carbon atoms which is substituted by one to
three aryl
groups, an aryl of 6 to 12 carbon atoms, or an aryl of 6 to 12 carbon atoms
which is
substituted by one to three alkyl groups of 1 to 6 carbon atoms.
Specific examples of such suitable hydroxylamines substituted with at least
one
alkyl, aryl or alkylaryl group as detailed above include, but are not
necessarily limited to
N-ethylhydroxylamine (EHA); N, N'-diethylhydroxylamine (DEHA); N-ethyl N-
methylhydroxylamine (EM HA); N-isopropylhydroxylamine
(I PHA); N,N'
dibutylhydroxylamine (DBHA); N-amylhydroxylamine (AHA); N-phenylhydroxylamine
(PHA); and the like and mixtures thereof.
A stable nitroxide free radical that can be used in this invention is a
nitroxide
having the formula (I) shown below or an amine precursor thereof.
R2 R3
R1¨C¨ N¨ C¨R4
R6 0. R5
(I)
wherein R1, R2, R3 and R4 are alkyl groups or heteroatom substituted alkyl
groups and no hydrogen is bound to the remaining valences on the carbon atoms
bound
to the nitrogen. The alkyl (or heteroatom substituted) groups R1-R4 may be the
same or
different, and preferably contain 1 to 15 carbon atoms. Preferably R1-R4 are
methyl,
ethyl, or propyl groups. In addition to hydrogen the heteroatom substituents
may include,
halogen, oxygen, sulfur, nitrogen and the like.
The remaining valences R5-R6 in the formula above may be satisfied by any
atom or group except hydrogen which can bond covalently to carbon, although
some
groups may reduce the stabilizing power of the nitroxide structure and are
undesirable.
Preferably R5 and R6 are halogen, cyano,--000R wherein R is alkyl or aryl, --
CONH2,
--S--C6H5, --S--COCH3, --000C2H5, carbonyl, alkenyl where the double bond is
not
conjugated with the nitroxide moiety or alkyl of 1 to 15 carbon atoms, R5 and
R6 may
also form a ring of 4 or 5 carbon atoms and up to two heteroatoms, such as 0,
N or S by
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R5 and R6 together. Examples of suitable compounds having the structure above
and
in which R5 and R6 form part of the ring are pyrrolidin-1-oxys, piperidiny1-1-
oxys, the
morpholines and piperazines. Particular examples wherein the R5 and R6 above
form
part of a ring are 4-hydroxy-2,2,6,6-tetramethyl-piperindino-1-oxy, 2,2,6,6-
tetramethyl-
piperidino-1-oxy, 4-oxo-2,2,6,6-tetramethyl-piperidino-1-oxy and pyrrolin-1-
oxyl.
Suitable R5 and R6 groups are methyl, ethyl, and propyl groups. A specific
example of
a suitable compound where R1-R6 are alkyl groups is di-tert-butylnitroxide.
The preferred
carbonyl containing nitroxides are those wherein the R5 and R6 form a ring
structure
with the nitrogen, preferably a six number ring, for example, 4-oxo-2,2,6,6-
tetramethylpiperidino-1-oxy. Examples of nitroxides that can be used in the
present
invention are the 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (also
referred as 4 OH
Tempo), the 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (also referred as 4
NH
Tempo), and 4 butoxy Tempo, or their amine precursors.
As regards the additives capable to reduce gums formation or buildup, one
can also cite as antioxidant the unhindered phenols, the hindered phenols and
a metal
salt of a hindered phenol, the aminophenols, the phenylenediamines, or
combinations
thereof, preferably the unhindered phenols, the hindered phenols and a metal
salt of a
hindered phenol, the aminophenols.
The aminophenol may be selected from the compounds given by the following
formula (II):
(II)
OH
NHR2
R1
Where R1 is selected from hydrogen, a C1-C20 alkyl group, C6-C12 aryl group,
or OR, with R being a H, an C1-C20 alkyl or a 06-C12 aryl group. R2 is
selected from
an C1-C20 alkyl, a phenyl group, or OR, with R' having the same meaning as
before.
Non-exclusive examples of such compounds are 2-aminophenol (2 AP), 3-
hydroxy-2-aminophenol, 2-amino-naphthalen-1-ol, 3-amino-naphthalen-2-ol, 1-
amino-
naphthalen-2-ol, 2-amino-tert-butyl-phenol, and 2-amino-4-methyl-phenol.
Suitable hindered or unhindered phenols may include, but are not necessarily
limited to, 4-tert butylcatechol (TBC); tert-butyl hydroquinone (TBHQ); 2,6-di-
tert-butyl-
4-methoxyphenol (DTBMP); 2,4 di-tert-butylphenol; 2,5-di-tert-butylphenol; 2,6-
di
tertbutylphenol; 2,4, tri-tert-butylphenol; butylated hydroxyltoluene (BHT,
also known as
2,6 di-tert-butyl-paracresol and 2,6 di-tert-butyl methylphenol); 2,6 di-tert-
buty1-4-
nonylphenol; 2,6-di-tert-butyl-4-sec-butylphenol; 2-butyl-4-methylphenol; 2-
tert-buty1-4-
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methoxyphenol (also known as butylated hydroxyanisole or BHA); 3-tert-buty1-4-
methoxyphenol ; 2-tert-butyl-4-heptylphenol; 2-tert-butyl-4-octylphenol; 2-
tert-buty1-4-
dodecylphenol; 2,6-di-tert-butyl-4-heptylphenol; 2,6-di-tert-butyl-4-
dodecylphenol; 2-
methy1-6-tert-buty1-4-heptylphenol; 2-methyl-6-tert-butyl-4-dodecyl phenol;
2,2'-bis(4-
5 hepty1-6-t-butyl-phenol); 2,2'-bis(4-octy1-6-t-butyl-phenol); 2,2'-bis(4-
dodecy1-6-t-butyl-
phenol); 4,4'-bis(2,6-di-t-butyl phenol), 4,4'-methylene-bis(2,6-di-t-butyl
phenol); 2,6-di-
alkyl-phenolic proprionic ester derivatives; propyl gallate; 2-(1,1-
dimethylethyl)-1,4-
benzenediol; 2-di-tert-butyl hydroquinone 15 (DTBHQ); tert-amyl hydroquinone;
2,5-di-
amyl hydroquinone; 3, di-tert-butylcatechol; hydroquinone; hydroquinone
monomethyl
10 ether; hydroquinone monoethyl ether; hydroquinone monobenzyl ether;
or 3,3,3',3'-
tetramethyl, 1,1-spirobis-indane-5,5',6,6 tetrol (Tetrol); topano10 AN
(mixture of BHT
and 2,4 Dimethy1-6-tert-butylphenol), tocopherols (C29H5002) including alpha-,
beta-,
gamma-, delta-tocopherol, 243,3-bis(3-tert-buty1-4-
hydroxyphenyl)butanoyloxy]ethyl
3,3-bis(3-tert-buty1-4-hydroxyphenyl)butanoate (C50H6608), and mixtures
thereof.
15 The phenylenediamines of this invention have at least one N-H group
and are
advantageously of the following formula (III):
R1
/H
/N
\ R3
R2
(111)
wherein R1, R2, and R3 are the same or different and are hydrogen, straight or
branched
chain alkyl of 1 to 20 carbon atoms, straight or branched chain alkyl of 1 to
20 carbon
atoms which is substituted by one to three aryl groups, aryl of 6 to 12 carbon
atoms, or
aryl of 6 to 12 carbon atoms which is substituted by one to three alkyl groups
of 1 to 6
carbon atoms.
Suitable examples of phenylenediamines include N-phenyl-N'-methy1-1,4-
phenylediamine, N-phenyl-N'-ethy1-1,4-phenylediamine, N-
phenyl-N'-n-propy1-1,4-
phenylediamine, N-phenyl-N'-isopropyl-1,4-phenylediamine (NIPP PPDA), N-phenyl-
H-
n-buty1-1,4-phenylediamine, N-phenyl-N'-iso-butyl-1,4-phenylediamine, N-phenyl-
N'-
sec-buty1-1,4-phenylediamine, N-phenyl-N'-t-butyl-1,4-phenylediamine, N-phenyl-
N'-n-
penty1-1,4-phenylediamine, N-phenyl-N'-n-hexy1-1,4-phenylediamine, N-phenyl-N'-
(1-
methylhexyl)-1,4-phenylediamine, N-phenyl-N'-(1,3-dimethylbutyI)-1,4-
phenylediamine,
N-phenyl-N'-(1,4-dimethylpentyI)-1,4-phenylediamine, N-phenyl-N',
N'-dimethy1-1,4-
phenylenediamine, N-phenyl-N',N'-diethy1-1,4-phenylenediamine, N-phenyl-N',N'-
di-n-
buty1-1,4-phenylenediamine, N-phenyl-N,N'-di-sec-buty1-1,4-phenylenediamine, N-
phenyl-N'-methyl-N'-ethy1-1,4-phenylenediamine, N,N'-dimethy1-1,4-
phenylenediamine,
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N, N'-di ethyl-1,4-phenylenediamine, N,N'-di-isopropy1-1,4-phenylenediamine,
N,N'-di-
iso-buty1-1,4-phenylenediamine, N,N.-di-sec-butyl-1,4-phenylenediamine (DSB
PPDA),
N,N'-bis(1,4-dimethylpenty1)-1,4-phenylenediamine,
N, N'-bis(1,3-dimethyl butyI)-1, 4-
phenylenediamine, N,N'-dipheny1-1,4-phenylenediamine,
N,N,N'-trimethy1-1,4-
phenylenediamine, and N,N,N'-triethy1-1,4-phenylenediamine and N-phenyl-p-
phenylenediamine (NP PPDA), and mixtures thereof.
In a preferred embodiment, the additive capable to reduce gums formation or
buildup is selected among the unhindered phenols, the hindered phenols, the
aminophenols, the phenylenediamines, and mixtures thereof.
In a most preferred embodiment, the additive capable to reduce gums formation
or buildup is selected among the unhindered phenols, the hindered phenols,
aminophenols and mixtures thereof. In another most preferred embodiment, the
additive
capable to reduce gums formation or buildup is selected among
phenylenediamines.
In a preferred embodiment, suitable additives include 4-tert butylcatechol
(TBC);
2,6-di tertbutylphenol; butylated hydroxyltoluene (BHT), tocopherols including
alpha-,
beta-, gamma-, delta-tocopherol, phenylenediamines, in particular those of the
above
list, and mixtures thereof.
As regards the additive which is a dispersant agent, such additive is a
dispersant/detergent capable to prevent the agglomeration of insoluble
compounds,
formed during oxidation reactions. Such additive does not reduce the gum
content.
The dispersant/detergent agent used in the present invention may be selected
from:
(i) substituted amines such as N-polyisobutene amine R1-NH2, N-polyisobutene-
ethylenediamine R1-N H¨R2-N
(ii) alkenyl succinimides, for example obtained by reacting an akenyl succinic
anhydride or acid with an amine or a polyamine, or their bissuccinimide,
succinnamic, succinamide structural equivalents, for example succinimides of
formula (IV):
0
(IV)
where R1 represents a C2-C120 or C2-C100 alkenyl group, for example a
polyisobutylene group of weight-average molecular weight between 140 and 5000
and
preferably between 500 and 2000 or preferably between 750 and 1250; and where
R2
represents at least one of the following segments ¨CH2¨CH2¨, CH2¨CH2¨CH2 , ¨
CH¨CH(CH3)¨ and x represents an integer between 1 and 6.
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(iii) the polyethylenamines. They are for example described in detail in the
reference
"Ethylene Amines," Encyclopedia of Chemical Technology, Kirk and Othmer, Vol.
5, pp.
898-905, Interscience Publishers, New York (1950).
(iv) the polyetheramines of formula (V):
R1 R2
/
0,C rl ) A
x.
(V)
where R is an alkyl or aryl group having from 1 to 30 carbon atoms; R1 and R2
are each
independently a hydrogen atom, an alkyl chain with 1 to 6 carbon atoms or
¨0¨CHR1-
CHR2-; A is an amine or N-alkylamine with 1 to 20 carbon atoms in the alkyl
chain, an
N,N-dialkylamine having from 1 to 20 carbon atoms in each alkyl group, or a
polyamine
with 2 to 12 nitrogen atoms and from 2 to 40 carbon atoms and xis in the range
from 5
to 30.
Such polyetheramines are marketed for example by the companies BASF, HU NSTMAN
or CHEVRON.
(v) the products of reaction between a phenol substituted with a hydrocarbon
chain,
an aldehyde and an amine or polyamine or ammonia. The alkyl group of the
alkylated
phenol can comprise from 9 to 110 carbon atoms. This alkyl group can be
obtained by
polymerization of olefinic monomer containing from 1 to 10 carbon atoms
(ethylene;
propylene; 1-butene, isobutylene and 1-decene). The polyolefins that are used
in
particular are polyisobutene and/or polypropylene. The polyolefins generally
have a
weight-average molecular weight Mw between 140 and 5000 and preferably between
500 and 2000 or preferably between 750 and 1250.
The alkyl phenols can be prepared by an alkylation reaction between a phenol
and an olefin or a polyolefin such as polyisobutylene or polypropylene. The
aldehyde
used can contain from 1 to 10 carbon atoms, generally formaldehyde or
paraformaldehyde.
The amine used can be an amine or a polyamine including the alkanolamines
having one or more hydroxyl groups. The amines used are generally selected
from
ethanolamine, diethanolamines, methylamine, dimethylamine, ethylenediamine,
dimethylaminopropylamine, diethylenetriamine,
triethylenetetramine,
tetraethylenepentamine and/or 2-(2-aminoethylamino)ethanol. This dispersant
can be
prepared by a Mannich reaction by reacting an alkylphenol, an aldehyde and an
amine
as described in patent U.S. Pat. No.5,697,988.
other dispersants, such as:
(vi) carboxylic dispersants such as those described in U.S. Pat. No.3,219,666;
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(vii)the amine dispersants resulting from reaction between halogenated
aliphatics of
high molecular weight with amines or polyamines, preferably polyalkylene
polyamines,
described for example in U.S. Pat. No.3,565,804;
(viii) polymeric dispersants obtained by polymerization of alkyl acrylates
or
alkyl methacrylates (C8 to C30 alkyl chains), aminoalkyl acrylates or
acrylamides and
acrylates substituted with poly(oxyethylene) groups. Examples of polymeric
dispersants
are described for example in U.S. Pat. No.3,329,658 and U.S. Pat.
No.3,702,300;
(ix) dispersants containing at least one aminotriazole group such as described
for
example in U.S. Patent Publication No. 2009/0282731 resulting from reaction of
a
dicarboyxlic acid or anhydride substituted with a hydrocarbyl and an amine
compound
or salt of the (amino)guanidine type;
(x) oligomers of polyisobutylsuccinic anhydride (PIBSA) and/or of
dodecylsuccinic
anhydride (DDSA) and of hydrazine monohydrate, such as those described in EP
1,887,074;
(xi) oligomers of ethoxylated naphthol and of PIBSA, such as those described
in EP
1,884,556;
(xii)quaternized ester, amide or imide derivatives of PIBSA, such as those
described
in W02010/132259;
(xiii) mixtures of Mannich bases such as substituted phenols/aldehydes/mono-
or polyamines, for example dodecylphenol/ethylenediamine/formaldehyde, and of
polyisobutylene succinimides (PIBSI), such as those described in W02010/097624
and
WO 2009/040582;
(xiv) quaternized terpolymers of ethylene, of alkenyl ester(s) and of
monomer(s) with at least one ethylenic unsaturation and containing an at least
partially
quaternized tertiary nitrogen, such as those described in W02011/134923;
(xv) polyisobutylene succinimides (PIBSAD), in particular represented by
the
formula (VI)
0
C
(X¨N)---X¨R2
CH2¨C A
0
(VI)
where R1 is a hydrocarbyl radical having from about 8 to 800 carbon atoms, X
is a
divalent alkylene or secondary hydroxy substituted alkylene radical having
from 2 to
3 carbon atoms, A is hydrogen or a hydroxyacyl radical selected from the group
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consisting of glycolyl, lactyl, 2-hydroxy-methyl propionyl and
',2'bishydroxymethyl
propionyl radicals and in which at least 30 percent of said radicals
represented by A
are said hydroxyacyl radicals, x is a number from 1 to 6, and R2 is a radical
selected
from the group consisting of -NH2-NHA or a hydrocarbyl substituted succinyl
radical
having the formula (VII)
0
II
R1¨ CH¨C
N¨
CH2¨C
0
(VII)
in which R1 is as defined above;
(xvi) products of the reaction of alkenyl succinic anhydride, an amine and
phosphorus pentasulfide such as those described in US 3 342 735, where the
formula
(VIII) of the alkenyl succinic anhydride is
0
\+.
/0
C=0 (VIII)
where R is a polyalkene derived radical of an average molecular weight between
about 300 and 5000 an' R is a member selected from the group consisting of
hydrogen and alkyl of from 1 to 6 carbon atoms, and
an amine selected from the group consisting of
016.====01r3
R"Nal, H2N (ANIL) sANHsti
Cat¨Cs (IX)
and
011s¨CIT2
IT4N¨A¨N/ \ 0
\0111¨(4
(X)
where R" is a C1-C20 alkyl group, A is a C1-C4 alkylene radical and x is a
whole
integer from 0 to 5;
(xvii) alkylbenzene sulfonates, such as alkali metal or ammonium salts of
alkylbenzenesulfonates, in which the alkyl group contains 8-18 carbons, for
example
sodium dodecylbenzenesulfonate;
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(xviii) Metal sulfonates, such as alkali metal sulfonates or
alkaline earth metal
sulfonates, for example calcium sulfonate, magnesium sulfonates.
In a preferred embodiment, the dispersant/detergent agent used in the present
invention may be selected from the above compounds (ii), (xv), (xvii)and
(xviii). Such
5 preferred dispersant/detergent agent(s) may be added to the above
described additive(s)
capable to reduce gums formation or buildup and more particularly to the
preferred
additive(s), especially to hindered phenols, more preferably to BHT.
As regards the tall oil fatty acids reacted with a polyamine that can be used
as additive capable to reduce gums formation or buildup the correspond to the
products
10 of a condensation reaction of tall oil fatty acids with a polyamine.
Typically, the reaction
products include tall oil fatty acid polyamides.
The tall oil fatty acids and polyamine are generally reacted in a molar ratio
1:1 at
temperatures between 250 and 290 C and usually a mixture of tall oil fatty
acid
polyamide and the corresponding tall oil fatty acid imidazoline is obtained.
The tall oil
15 fatty acids are typically obtained by distillation of a crude tall oil.
In a preferred embodiment, the polyamine is a polyalkylene polyamine, in
particular an ethylene polyamine, such as diethylenetriamine (DETA),
triethylenetetramine (TETA), or tetraethylenepentamine (TEPA), preferably
DETA.
A suitable additive includes the product registered with the CAS n 1226892-43-
20 8.
As regards other additives that may be used, metal passivators and metal
chelating agents may be added alone or in combination with any of the
preceding
additives.
Metal passivators can comprise triazoles, alkylated benzotriazoles and
alkylated
tolutriazoles, derivatives from 2,5-dimercapto-1,3,4-thiadiazole, in
particular bisulfides
derivatives.
Metal chelating agents can comprise dialkyl phosphonates, in which the alkyl
group contains 1-18 carbons.
As regards the stabilized composition, it is of use in industrial processes
for
plastic recycling in which hydrocarbon streams is handled or manipulated other
than the
intentional polymerization of the double bonds. Such processes include but are
not
limited to hydrocarbon cracking processes, preheating, distillation,
hydrogenation,
extraction, etc.
The proportion of b) with reference to a) can be up to 5000wppm,
advantageously
up to 3000 wppm, in particular from 50 to 5000 wppm, preferably from 50 to
3000 wppm,
most preferably from 100 to 1500 wtppm or from 300 to 1500wppm, or within any
of
these limits.
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The proportion of c) with reference to a) can be up to 5000wppm,
advantageously
up to 3000 wppm, in particular from 50 to 5000 wppm, preferably from 50 to
3000 wppm,
most preferably from 100 to 1500 wtppm or from 300 to 1500wppm, or within any
of
these limits.
The proportion of d) with reference to a) can be up to 5000wppm,
advantageously
up to 3000 wppm, in particular from 50 to 5000 wppm, preferably from 50 to
3000 wppm,
most preferably from 100 to 1500 wtppm or from 300 to 1500wppm, or within any
of
these limits.
The additives of this invention may also be used with other additives known to
prevent fouling such as metal deactivators, corrosion inhibitors and the like.
The
stabilizer combination of this invention may be applied at any point in an
industrial plant
stream or process where it is effective.
As regards the process for preparing a composition stabilized against
premature polymerization
Step (a) for providing a hydrocarbon stream as defined above may comprise:
(i) providing at least one plastic liquefaction oil by liquefaction of plastic
waste,
(ii) optionally providing a diluent,
(iii) preparing a hydrocarbon stream having a diene value of at least 0.5 g
12/100
g, preferably at least 1 g 12/100 g, as measured according to UOP 326, a
bromine number
of at least 5 g Br2/ 100g as measured according to ASTM D1159 by mixing said
at least
one plastic liquefied oil provided in step (i) with the diluent provided in
step (ii) when
present, said composition comprising at least 1wt%, or 2wt%, of plastic
liquefaction oil,
the remaining part of said hydrocarbon stream being a diluent.
Step (i) may include a step of liquefying waste containing plastics and
obtaining
a hydrocarbon product comprising a gaseous phase, a liquid phase and a solid
phase
followed by a step of separating the liquid phase of said product, said liquid
phase
forming a plastic liquefaction oil. The separation step removes the gaseous
phase,
essentially the C1-C4 hydrocarbons and the solid phase (typically char) to
recover only
the liquid organic phase forming a liquefaction oil.
Liquefaction step may comprise a pyrolysis step, typically carried out at a
temperature of 300 to 1000 C or 400 to 700 C, such pyrolysis being for example
fast
pyrolysis or flash pyrolysis or catalytic pyrolysis or hydropyrolysis.
Alternatively, or in
combination, liquefaction step may comprise a hydrothermal liquefaction step,
typically
performed at a temperature of 250-500 C and at pressures of 10-25-40 MPa.
The waste material processed in liquefaction step may be waste plastic
optionally
mixed with biomass and/or elastomer, as previously described.
In one embodiment, in step (b), said at least one additive capable to reduce
gums
formation or buildup is added to said at least one plastic liquefaction oil
provided by step
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(i), prior to step (iii). In an embodiment, the additives are added to the
liquefaction plastic
oil immediately after the liquefaction of the plastic waste.
In one embodiment, in step (c), said at least one additive is added to said at
least
one plastic liquefaction oil provided by step (i), prior to step (iii),
preferably immediately
after the liquefaction of the plastic waste.
In one embodiment, in step (d), said at least one other additive is added to
said
at least one plastic liquefaction oil provided by step (i), prior to step
(iii), preferably
immediately after the liquefaction of the plastic waste.ln one embodiment,
steps (b) and
(c), and optionally step (d), are performed simultaneously, preferably
immediately after
the liquefaction of the plastic waste.
Whatever the embodiment, the additives can be introduced as pure or as a
dilute
solution in a hydrocarbon or equivalent and/or they can be introduced
simultaneously or
separately. For example, the additives may be diluted in hydrocarbons, for
example C6-
020 aromatic hydrocarbons substituted or not, including toluene, benzene,
naphthalene,
substituted or not, and their mixtures, heavy aromatic naphtha, a middle
distillate (boiling
range 180-360 C) such as a jet fuel or a diesel, or in polar solvents, in
particular alcohols
such as glycols, ethanol, or water.
The stabilized composition described in the present invention or obtained by
the
process of the present invention may be used as such or further processed
alone or in
combination with another feedstock such as naphtha, gasoil or any crude oil
refining
product. It may for example be fractionated according to distillation
temperature ranges,
to feed a steam cracker, a FCC, a hydrocracker, a catalytic hydroprocessing
unit or a
pool of fuels or combustibles such as naphtha, gas oil, heavy fuel oil and/or
for the
preparation of lubricants.
As regards the optional purification step to trap silicon and/or metals and/or
phosphorous and/or halogenates over at least one trap to obtain a purified
stabilized
composition. In one embodiment, this purification step is performed before
processing
the stabilized composition, before or after the evaporation step when present.
With regards to traps for the silicon and/or metals and/or phosphorous and/or
halogenates, it consists in silica gel, clays, alkaline or alkaline earth
metal oxide, iron
oxide, ion exchange resins, active carbon, active aluminium oxide, molecular
sieves,
and/or porous supports containing lamellar double hydroxide modified or not
and silica
gel, or any mixture thereof used in the fixed bed techniques known in the art.
The trap is
able to capture silicon and/or metals and/or phosphorous and/or halogenates,
being
preferably chosen among Ca, Mg, Hg via absorption and/or adsorption or it can
also be
constituted of one or more active guard bed with an adapted porosity. It can
work with or
without hydrogen coverage. The trap can be constituted of an adsorbent mass
such as
for instance a hydrated alumina. Molecular sieves can also be used to trap
silicon. Other
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adsorbent can also be used such as silica gel for instance. The silicon trap
is preferably
able to trap organic silicon. Indeed, it is possible that the silicon present
in the streams
is in the form of organic silicon.
In a preferred embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with activated carbon. Activated carbon possesses
preferably
a high surface area (600-1600 m2/g) and is preferably porous and hydrophobic
in
nature. Those properties lead to a superior adsorption of non-polar molecules
or little
ionized molecules. Therefore, activated carbon can be used to reduce for
instance
siloxane from the liquid feed at temperature from 20 to 150 C, at pressures
from 1 to 100
bar or from vaporized feed from 150 to 400 C at pressure from 1 to 100 bar.
In a preferred embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with silica or silica gel. Silica gel is an amorphous
porous
material, the molecular formula usually as (SiO2)-nH20, and unlike activated
carbon,
silica gel possesses polarity, which is more conductive to the adsorption of
polar
molecules. Because of¨Si¨O¨ Si¨ bonds, siloxanes exhibit partial polar
character, which
can contribute to adsorb on silica gel surface.
In a preferred embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with molecular sieves. Molecular sieves are hydrous
aluminosilicate substance, with the chemical formula Na20-A1203- nSiO2-xH20,
which
possesses a structure of three-dimensional crystalline regular porous and
ionic
exchange ability. Compared with silica gel, molecular sieves favour adsorption
of high
polarity. The regeneration of exhausted absorbents can be achieved via heating
at high
temperature to remove siloxane. Often, the regeneration is less efficient as
the siloxanes
might react irreversibly with the molecular sieve. In a most preferred
embodiment, the
molecular sieves are ion-exchanged or impregnated with a basic element such as
Na.
Na2O impregnation levels range from 3-10% wt typically and the type of sieve
are
typically of the A or faujasite crystal structure.
In a preferred embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with activated aluminium oxide. Activated aluminium
oxide
possesses large surface area (100-600 m2/g), which shows high affinity for
siloxanes
but also for polar oxide, organic acids, alkaline salts, and water. It can be
an alkaline or
alkaline-earth or rare-earth containing promoted alumina, the total weight
content of
these doping elements being less than 20%wt, the doping elements being
preferably
selected from Na, K, Ca, Mg, La, or mixture thereof. It can also be a metal
promoted
alumina where the metal is selected from group VI-B metal with hydrogenating
activity
such as Mo, W and/or from group VIII metal, such as Ni, Fe, Co
In another embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with alkaline oxide Alkaline oxide for high
temperature
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treatment such as calcium oxide (CaO) has strong activity to breakdown
siloxanes and
can be used as non-regeneratable adsorbent at temperature between 150 and 400
C.
In another embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with porous supports containing lamellar double
hydroxides,
being preferably an hydrotalcite. The hydrotalcite can comprise one or more
metals with
hydrogenating capacity selected from group VIB or Group VIII, preferably Mo.
Those
metals can be supported on the surface of the hydrotalcite, or can have been
added to
the actual structure of the lamellar double hydroxide, in complete or partial
substitution;
as an example, but without limiting the scope of the present invention, the
divalent metal,
usually Mg, can be exchanged for Ni, or the trivalent metal, substituted by Fe
instead of
Al.
The above-mentioned solid adsorbents can be used alone or in any combination
in order to optimize the removal of silicon and/or metals and/or phosphorous
and/or
halogenates.
In another embodiment, silicon and/or metals and/or phosphorous and/or
halogenates are trapped with a multi layered guard bed comprising at least two
layers
wherein the layer on the top of the bed is selected from silica gel, clays,
alkaline or
alkaline earth metal oxide, iron oxide, ion exchange resins, active carbon,
active
aluminium oxide, molecular sieves and wherein the layer on the bottom of the
bed is
selected from silica gel, clays, alkaline or alkaline earth metal oxide, iron
oxide, ion
exchange resins, active carbon, active aluminium oxide, molecular sieves. More
preferably said layer on the top of the guard bed comprises silica gel and/or
active carbon
and said layer on the bottom of the guard bed comprises molecular sieves
and/or active
aluminium oxide.
In another embodiment, when the plastic liquefaction oil contains high
quantities
of HCI and/or Halogenated compounds (namely at least 500 ppm wt of HCI based
on the
total amount of plastic liquefaction oil), particular adsorbents can be used
such as silica,
clays - such as bentonite, hydrotalcite - alkaline or alkaline earth metal
oxide - such as
iron oxides, copper oxides, zinc oxide, sodium oxide, calcium oxide, magnesium
oxide-
alumina and alkaline or alkaline-earth promoted alumina-, iron oxide
(hematite,
magnetite, goethite), ion exchange resins or combination thereof. In a most
preferred
embodiment, silicon and/or metals and/or phosphorous and/or halogenates
containing
at least 500 ppm wt of HCI based on the total amount of plastic liquefaction
oil are trapped
with activated alumina. As HCI is a polar molecule, it interacts with polar
sites on the
alumina surface such as hydroxyl groups. The removal mechanism relies
predominantly
on physical adsorption and low temperature and the high alumina surface area
is
required to maximize the capacity for HCI removal. The HCI molecules remain
physically
adsorbed as a surface layer on the alumina and can be removed reversibly by
hot
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purging. Promoted aluminas are a hybrid in which a high alumina surface area
has been
impregnated with a basic metal oxide or similar salts, often of sodium or
calcium. The
alumina surface removes HCI through the mechanisms previously described,
however
the promoter chemically reacts with the HCI giving an additional chloride
removal
5 mechanism referred to as chemical absorption. Using sodium oxide as an
example of
the promoter, the HCI is captured by formation of sodium chloride. This
chemical reaction
is irreversible unlike physical adsorption and its rate is favoured by higher
temperature.
The promoted alumina chloride guards are very effective for liquid feeds due
to the
irreversible nature and high rate of the chemical reaction once the HCI
reaches the
10 reactive site.
Another class of chemical absorbents combines Na, Zn and Al oxides in which
the first two react with HCI to form complex chloride phases, for example
Na2ZnC14 and
the chemical reactions are irreversible. U.S. 4,639,259 and 4,762,537 relate
to the use
of alumina-based sorbents for removing HCI from gas streams. U.S. 5,505,926
and
15 5,316,998 disclose a promoted alumina sorbent for removing HCI from
liquid streams by
incorporating an alkali metal oxide such as sodium in excess of 5% by weight
on to an
activated alumina base. Other Zn-based products range from the mixed metal
oxide type
composed of ZnO and Na2O and/or CaO. The rate of reaction is improved with an
increase in reactor temperature for those basic (mixed) oxides.
20 As regards the process for the processing of a composition stabilized
against premature polymerization, it uses a stabilized composition as
described in the
present invention and in particular obtained by the process for preparing a
composition
stabilized against premature polymerization of the invention. The use of the
stabilized
composition of the invention allows performing the processing at temperatures
of 200 C
25 or higher, typically from 200 C to 1200 C or allows performing at least
one treatment of
step (c) in this temperature range without fouling.
In some embodiments, some or all of the additives contained in the stabilized
composition (additive(s) capable to reduce gums formation or buildup and/or
additive(s)
which is a dispersant agent, and optionally other additives) may present a too
high boiling
point to be used in a further processing step and/or may be detrimental to the
further
processing.
In such a case, it may be preferable to reduce, or completely remove, some or
all
of the additives by submitting the stabilized composition provided in step (a)
to an
evaporation step (b) under operating conditions efficient to obtain a
composition
containing a reduced amount of additives. Such evaporation may be performed at
temperatures and pressure efficient to obtain a gaseous hydrocarbon stream
having a
final boiling point of at most 650 C, preferably of at most 500 C, more
preferably of at
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most 38000, and optionally a residue. Such evaporation is optionally performed
in
presence of steam.
In one embodiment, in the evaporation step, the stabilized composition may be
heated using steam, at a temperature which is high enough to avoid
condensation of
steam when direct mixing is envisioned, since steam condensation could lead to
hammering issues. Non-vaporized products are removed in a separation section
to
produce the gaseous hydrocarbon stream. Alternatively, the stabilized
composition may
be heated using a hot oil, which is collected in admixture with the non-
vaporized products
and may be recycled.
The evaporation step may be performed using a flash drum, a kettle, a single
or
double wall thin film evaporator, a falling film evaporator or a combination
of at least two
of them.
Such evaporation step (b) may be particularly useful before processing the
stabilized composition in a steam cracker. It may be omitted for other
processing steps
such as hydroprocessing (including catalytic hydrogenation, hydrocracking,
etc), fluid
catalytic cracking and separation by distillation.
The gaseous hydrocarbon stream obtained from evaporation step (b) is then
submitted to the further processing step (c).
In the process for the processing of a stabilized composition according to the
invention, the stabilized composition provided in step (a) or the composition
containing
a reduced amount of additives provided in step (b) may, prior to step (c)
and/or (d), be
mixed with naphtha, gasoil or any crude oil refining product to have a
liquefied plastic oil
concentration ranging from 0.01 wt% to at most 90 wt%; preferably 0.1 wt% to
75 wt%
even more preferably 1 wt% to 50 wt% or within any of these limits.
The stabilized composition, either before or after the optional evaporation
step,
may be submitted to the optional purification step before the processing.
As regards the steamcracking processing step performed in a steamcracker,
this step is typically performed at a temperature higher than 200 C, to
produce olefins,
such as ethylene and propylene, and aromatics.
In a preferred embodiment, the stabilized composition is sent at least
partially
directly to a steam cracker without further dilution and preferably as the
only stream sent
at least partially to the steam cracker, to produce olefins, such as ethylene
and
propylene, and aromatics.
The steam cracker is known per se in the art. The feedstock of the steam
cracker
in addition to the stabilized composition can be ethane, liquefied petroleum
gas, naphtha
or gasoils or crude oil. Liquefied petroleum gas (LPG) consists essentially of
propane
and butanes. Gasoils have a boiling range from about 200 to 350 C, consisting
of C10
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to 022 hydrocarbons, including essentially linear and branched paraffins,
cyclic paraffins
and aromatics (including mono-, naphtho- and poly-aromatic).
In particular, the cracking products obtained at the exit of the steam cracker
may
include ethylene, propylene and benzene, and optionally hydrogen, toluene,
xylenes,
and 1,3-butadiene.
In a preferred embodiment, the outlet temperature of the steam cracker may
range from 800 to 1200 C, preferably from 820 to 1100 C, more preferably from
830 to
950 C, more preferably from 840 C to 920 C. The outlet temperature may
influence the
content of high value chemicals in the cracking products produced by the
present
process.
In a preferred embodiment, the residence time in the steam cracker, through
the
radiation section of the reactor where the temperature is between 650 and 1200
C, may
range from 0.005 to 0.5 seconds, preferably from 0.01 to 0.4 seconds
In a preferred embodiment, steam cracking is done in presence of steam in a
ratio of 0.1 to 1.0 kg steam per kg of hydrocarbon feedstock, preferably from
0.25 to 0.7
kg steam per kg of hydrocarbon feedstock in the steam cracker, preferably in a
ratio of
0.35 kg steam per kg of feedstock mixture, to obtain cracking products as
defined above.
In a preferred embodiment, the reactor outlet pressure may range from 500 to
1500 mbars, preferably from 700 to 1000 mbars, more preferably may be approx.
850
mbars. The residence time of the feed in the reactor and the temperature are
to be
considered together. A lower operating pressure results in easier light
olefins formation
and reduced coke formation. The lowest pressure possible is accomplished by
(i)
maintaining the output pressure of the reactor as close as possible to
atmospheric
pressure at the suction of the cracked gas compressor (ii) reducing the
pressure of the
hydrocarbons by dilution with steam (which has a substantial influence on
slowing down
coke formation). The steam/feedstock ratio may be maintained at a level
sufficient to limit
coke formation.
Effluent from the steam cracker contains unreacted feedstock, desired olefins
(mainly ethylene and propylene), hydrogen, methane, a mixture of C4's
(primarily
isobutylene and butadiene), pyrolysis gasoline (aromatics in the C6 to C8
range), ethane,
propane, di-olefins (acetylene, methyl acetylene, propadiene), and heavier
hydrocarbons
that boil in the temperature range of fuel oil (pyrolysis fuel oil). This
cracked gas is rapidly
quenched to 338-510 C to stop the pyrolysis reactions, minimize consecutive
reactions
and to recover the sensible heat in the gas by generating high-pressure steam
in parallel
transfer-line heat exchangers (TLE's). In gaseous feedstock-based plants, the
TLE-
quenched gas stream flows forward to a direct water quench tower, where the
gas is
cooled further with recirculating cold water. In liquid feedstock-based
plants, a
prefractionator precedes the water quench tower to condense and separate the
fuel oil
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fraction from the cracked gas. In both types of plants, the major portions of
the dilution
steam and heavy gasoline in the cracked gas are condensed in the water quench
tower
at 35-40 C. The water-quench gas is subsequently compressed to about 25-35
Bars in
4 or 5 stages. Between compression stages, the condensed water and light
gasoline are
removed, and the cracked gas is washed with a caustic solution or with a
regenerative
amine solution, followed by a caustic solution, to remove acid gases (002, H2S
and SO2).
The compressed cracked gas is dried with a desiccant and cooled with propylene
and
ethylene refrigerants to cryogenic temperatures for the subsequent product
fractionation:
front-end demethanization, front-end depropanization or front-end
deethanization.
As regards the fluid catalytic cracking processing step performed in a fluid
catalytic cracker unit, this step is typically performed at a temperature
higher than 200 C,
generally at temperatures of 500-550 C, in presence of well-known suitable
catalysts to
crack the heavy hydrocarbon molecules. The effluent is typically contacted
with a high
activity zeolite catalyst in a reactor at high temperature with a short
contact time of a few
minutes or less. The catalyst on which coked produced during reaction is
deposited is
then regenerated before being reinjected into the reactor at high temperature.
Non-limiting examples of a FCC catalyst include X- type zeolites, Y-type
and/or
USY-type zeolites, mordenite, faujasite, nano-crystalline zeolites, MCM
mesoporous
materials, SBA-15, a silico-alumino phosphate, a gallophosphate, a
titanophosphate,
spent or equilibrated catalyst from FCC units or any combinations thereof. In
some
aspects, the zeolites can be metal loaded zeolites. The FCC catalyst can be
present in
an active or inactive matrix with or without metal loading.
This process is widely used in the refining industry for conversion of
atmospheric
gas oil, vacuum gas oil, atmospheric residues and heavy stocks recovered from
other
refinery operations into high-octane gasoline, light fuel oil, heavy fuel oil,
olefin-rich light
gas (LPG) and coke A conventional FCC unit can be used.
As regards the hydroprocessing step performed in a hydroprocessing unit, this
step refers to processes or treatments that react a hydrocarbon-based material
with
hydrogen, typically under pressure and with a catalyst (hydroprocessing can be
non-
catalytic). Such processes include, but are not limited to, hydrodeoxygenation
(of
oxygenated species), hydrodesulfurization, hydrodenitrification,
hydrodemetallation,
hydrogenation, hydrocracking, hydroisomerization, and hydrodewaxing.
A hydroprocessing unit therefore includes one or several units or zones of (i)
hydrodeoxygenation, (ii) hydrodesulfurization, (iii) hydrodesulfurization,
(iv)
hydrodemetallation, (v) hydrogenation, (vi) hydrocracking, (vii)
hydroisomerization, (viii)
hydrodewaxing.
The terms "hydroprocessing" and "hydrotreating" are used interchangeably
herein.
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Hydroprocessing is typically performed at a temperature higher than 200 C, in
presence of hydrogen with well-known suitable catalysts to saturate the double
bonds,
to convert heteroatoms such as sulfur and nitrogen components into
respectively H2S
and NH3, to remove oxygen and other heteroatoms, such as metal, an/or to crack
the
heavier hydrocarbons. At the same time, aromatic compounds are saturated into
cyclic
compounds and some additional branching may be produced.
Depending on the composition of the stream entering this hydrotreating step,
it is
either performed in gas phase or the reactor operates in trickle bed mode.
This step can
have also a metal trap function, a cracking function, a de-aromatization
function
depending on the characteristic of the catalyst and the used operating
condition. This
step can be performed in one reactor with different layers of catalysts or
several reactors
in series depending on the function sought.
In a preferred embodiment, said hydrotreating step is performed in one or more
catalyst bed with preferably an overall temperature increase of at most 100 C
and/or a
temperature increase of at most 50 C over each catalyst bed, with preferably
intermediary quench between said catalyst beds, said quench being preferably
performed with H2 or with the stabilized composition.
In a preferred embodiment, the inlet temperature of said hydrotreating step is
of
at least 200 C, preferably 230 C, more preferably 250 C and at most 500 C.
Temperatures as low as 100 C or 140 C are possible when limited hydrogenation
is
sought.
In another preferred embodiment, said hydrotreating step is performed at a
LHSV
between 1 to 10h-1, preferably 2 to 4 h-1.
In another preferred embodiment, said hydrotreating step is performed at a
pressure ranging from 1 to 200 barg, preferably from 25 to 200 barg, in
presence of H2.
In another preferred embodiment, said hydrotreating step is performed with a
ratio H2/hydrocarbon ranging from 5 NUL to 2000 NUL, preferably in the
presence of at
least 0.005 wt %, preferably 0.05 wt % even more preferably 0.5 wt% of
sulphur, being
preferably H2S or organic sulfur compounds, in the feed stream.
In one embodiment, the hydroprocessing unit may include at least one guard bed
to strap solid particles, typically located on top of said hydroprocessing, to
remove the
solid particles remaining in the feed such as coke particles coming from
heating tubes,
iron scales from corrosion, dissolved impurities such as iron, arsenic,
calcium-containing
compounds, sodium chloride, silicon contained in upstream additives, etc. The
gard bed
may include one or several of the materials listed above to capture silicon
and/or metals
and/or phosphorous and/or halogenates. Grading materials which have high void
space
to accumulate and store these particulates are frequently used. Effective feed
filtration
to remove particulates in combination with high void grading provides a longer
mitigation
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of pressure drop buildup. In a preferred embodiment, said guard bed to trap
solid
particles has a continuously decreasing particle size including a region 25 to
150
centimeters of particles, having a fraction of 0.3 to 2.0 cm diameter range.
Since such
guard beds to trap solid particles are designed specifically to handle the
contaminants,
5 they help to prolong the life of the hydrotreating catalyst and require
fewer total catalyst
changeouts.
In particular, on the top of the said hydrotreatment a silicon trap may be
present
working at a temperature of at least 200 C, and/or a LHSV between 1 to 10h-1,
and/or a
pressure ranging from 10 to 90 barg in presence of H2; optionally with a metal
trap
10 working at a temperature of at least 200 C, a LHSV between 1 to 10h-1, a
pressure
ranging from 10 to 90 barg in presence of H2.
In another preferred embodiment, said hydrotreating step is performed in a
reactor preferably over a catalyst that comprises at least one metal of groups
8-10,
preferably selected from the group of Pt, Pd, Ni and/or mixture thereof on a
support such
15 as alumina, titania, silica, zirconia, magnesia, carbon and/or mixtures
thereof.
In another preferred embodiment, said hydrotreating step is performed over a
catalyst that comprises at least one metal of group 6 as for example Mo, W in
combination or not with a promotor selected from at least one metal of group 8-
10 as for
example Ni and/or Co, and/or mixture thereof, preferably these metals being
used in
20 sulfided form and supported on alumina, titania, zirconia, silica,
carbon and/or mixtures
thereof.
In another preferred embodiment, said hydrotreating step is performed over at
least one catalyst that presents both (i) an hydrotreating function, namely at
least one
metal of group 6 as for example Mo, W in combination or not with a promotor
selected
25 from at least one metal of group 8-10 as for example Ni and/or Co,
and/or mixture thereof,
preferably these metals being used in sulfided form and (ii) a trap function,
namely said
catalyst presents a BET surface area ranging from 150 m2/g to 400 m2/g.
In another preferred embodiment, the effluent obtained after said
hydrotreating
step may be further washed with water to remove inorganic compounds such as
30 hydrosulphide, hydrogenchloride, ammonia and ammonium salts, and
optionally further
treated in another processing unit including a hydrotreatment unit, a
hydrocraking unit,
an isomerization unit. Alternatively, the hydroprocessing unit may comprise a
hydrogenation zone, a hydrodemetallation zone, a hydrotreatment zone, a
hydrocracking
zone, a hydro isomerisation zone
In another preferred embodiment, the effluent obtained after said
hydrotreating
step, optionally washed, is preferably further hydrocracked at a temperature
of 350-
430 C, a pressure of 30 ¨ 180 barg, a LHSV of 0.5-4 h-1, and/or under a H2 to
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hydrocarbons ratio of 800-2000 NL : L to reduce the final boiling point of at
least 10%
prior to be sent at least partially to a steam cracker.
In a preferred embodiment, a guard bed to trap solid particles is located on
the
top of said hydrotreating step.
The effluent of the hydrotreating step can be sent, after a potential
separation
step typically by distillation, to a steamcracker, a FCC unit, a hydrocracking
unit, a
hydrogenation unit, or blended in crude oil or base oil or crude oil cut to be
further refined.
The hydrotreating unit outlet stream can be fed to a distillation column so as
to
obtain a flue gas stream which is used as a fuel, an ultra-low sulphur naphtha
stream in
the case of a naphtha hydrotreater, an ultra-low sulphur diesel stream in the
case of
gasoil hydrotreater and an ultra-low sulphur fuel oil in the case of heavy oil
hydrotreater.
As regards the hydrodemetallation processing step generally performed in a
hydrodemetallation unit or zone, this step is typically performed at a
temperature from
200 to 500 C, at a pressure from 1 to 180 barg in presence of hydrogen. The
conditions
are selected to perform the desired hydro-dennetallization conversion to
reduce or
eliminate the undesirable characteristics or components of the feed stream. In
accordance with the present invention, it is contemplated that the desired
hydro-
demetallation conversion includes, for example, dehalogenation,
desulfurization,
denitrification, olefin saturation and oxygenate conversion.
Liquid hourly space velocities are typically in the range from about 0.05 hrl
to
about 20 hrl and the hydrogen to feed ratio is generally from about 30 to
8500Nm3/m3,
Suitable catalysts contain a metallic component having hydro-demetallation
activity combined with a suitable refractory inorganic oxide carrier material
of either
synthetic or natural origin. Examples of carrier materials are alumina,
silica, and mixtures
thereof. Suitable metallic components having hydro-demetallization activity
are those
selected from the group comprising the metals of Groups 6 and 8-10. In
addition, any
catalyst employed commercially for hydrogenating reduced crude oil to remove
nitrogen,
metals and sulfur may function effectively. It is further contemplated that
hydro-
demetallization catalytic composites may comprise one or more of the following
components: cesium, francium, lithium, potassium, rubidium, sodium, copper,
gold,
silver, cadmium, mercury and zinc.
As regards the hydrogenation processing step generally performed in a
catalytic hydrogenation unit, this step is typically performed at a
temperature higher than
100 C, in presence of hydrogen and suitable hydrogenation catalyst to
hydrogenate the
aromatic and/or olefinic compounds contained in the feedstock to produce a
saturated
product, without significant cracking or isomerization. This step is thus a
selective
hydrogenation step of unsaturated compounds performed under hydrogenation
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conditions. The hydrogenation conditions may be any conditions suitable to
cause the
hydrogenable component to react with hydrogen.
The hydrocarbon stream may be contacted with hydrogen at an amount of 25 to
500 Nm3 hydrogen/m3 hydrocarbons of the feedstock, carried out at a
temperature from
100 to 370 C, preferably at 150 C to 300 C, at a LHSV from 0.2 to 10 1/h, and
at 1 to
350 barg, preferably at 20 to 250 barg hydrogen pressure. Among these standard
process controls LHSV refers to volumetric liquid hourly space velocity
indicating the
reactant liquid flow rate/reactor volume.
The hydrogenation step is performed over a hydrogenation catalyst that may be
any catalyst that can facilitate hydrogenation. A suitable catalyst typically
comprises at
least one metal of groups 6 to 10 such as palladium (Pd) and platinum (Pt).
The metal(s)
is/are preferably used in sulfided form and supported on alumina, titania,
zirconia, silica,
carbon and/or mixtures thereof.
As regards the hydrocracking processing step performed in a hydrocracking
unit, this step is typically performed at a temperature higher than 200 C,
generally at a
temperature 200-500 C and high pressure (30-200 barg) in a hydrogen-rich
atmosphere
in the presence of a suitable catalyst to produce lower-boiling hydrocarbon
compounds.
Typically hydrocracking is performed in a catalytic reactor with a dual
function under a
high hydrogen partial pressure and elevated temperatures such that large
hydrocarbon
molecules crack into smaller molecules while double bonds are saturated and
sulphur,
nitrogen, oxygen and other heteroatoms, such as metals, are removed by the
hydrogen
from the hydrocarbon chains. At the same time, aromatic compounds are
saturated into
cyclic compounds and some additional branching may be produced.
Optionally, the liquefied oil cracking operation may comprise a hybrid fluid
catalytic cracking of at least part of the heavy liquefied oil fraction. In
this way it is possible
to improve the diesel yield of the overall process by at least partially
reducing the average
molecular weight of the heavy liquefied oil fraction.
In one embodiment, the effluent is hydrocracked at a temperature of 350-430 C,
a pressure of 30 ¨ 180barg, a LHSV of 0,05-to 20 h-1 or of 0.5-4 h-1, and/or
under a H2
to hydrocarbons ratio of 800-2000 Nm3:m3 to reduce the final boiling point of
at least
10%.
The hydrocracking catalyst generally contains at least one metallic component
having hydrogenation activity combined with a suitable refractory inorganic
oxide carrier
material of either synthetic or natural origin. The carrier material may
contain amorphous
and/or zeolitic components. The preparation of hydrocracking catalysts is well
known to
those skilled in the art.
As regards the isomerization step, generally performed in an isomerization
unit, this step is typically carried out using an isomerization catalyst at a
temperature
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from 25000 to 40000, typically in the presence of hydrogen. The operating
pressure is
typically 10 to 140 barg, and more typically 10 barg to 70 barg. Hydrogen flow
rate is
typically 8 to 900 Nm3/m3.
Suitable isomerization catalysts can include, but are not limited to Pt or Pd
on a
support such as, but further not limited to, SAPO-11, SM-3, SSZ-32, ZSM-23,
ZSM-22;
and similar such supports. In some or other embodiments, the step of
isomerizing
comprises use of a Pt or Pd catalyst supported on an acidic support material
selected
from the group consisting of beta or zeolite Y molecular sieves, SiO2, A1203,
SiO2-A1203,
and combinations thereof.
Detailed description of the figures
Figure 1 shows a simplified overview of a possible process scheme according to
the
invention. Raw plastic (1) waste is introduced into a liquefaction unit (2)
under conditions
suitable to produce a plastic liquefied oil (5), gas (3) and char (4)_ The
plastic liquefied
oil (5) then enters a mixing unit (6) where the additives are mixed to the
plastic liquefied
oil (5) to obtain a stabilized composition (7). The stabilized composition (7)
then enters
hydrotreatment unit (8), optionally presenting a top guard bed to remove
solids and
impurities. The hydrotreated plastic liquefied oil (9) then enters an
evaporation section
(10) before being submitted to steamcracking in a steam cracker (11) to
produce light
olefins e.g. from C2 to C4 olefins and heavier products. Optionally, the
stabilized
composition (7) or the hydrotreated plastic liquefied oil (9) may be separated
into several
streams in a separation section (not represented), for example selected
according to
distillation ranges, for example to separate streams such as GPL, gasoline,
diesel, heavy
fuel, kerosene, which may be further treated in the steam cracker. It is then
possible to
treat in the hydrotreatment unit (8) or into the steam cracker (11) one or
several of the
separated streams selected as a function of the products sought.
Figure 2 shows a simplified overview of another possible process scheme
according to
the invention. This process scheme is the same as the one of figure 1 up to
the
hydrotreatment unit (8), and the same references design the same elements. The
hydrotreated plastic liquefied oil (9) here enters another (i) hydroprocessing
unit 12 such
as a hydrocracking unit, a catalytic hydrogenation unit, or any other
hydrotreatment unit,
and/or (ii) a FCC unit (13), and/or (iii) an isomerization unit (14) and/or
(iv) a separation
unit (15). Optionally, the stabilized composition (7) or the hydrotreated
plastic liquefied
oil (9) may be separated into several streams in a separation section (not
represented),
for example selected according to distillation ranges, for example to separate
streams
such as GPL, gasoline, diesel, heavy fuel, kerosene, which may be further
treated in
hydroprocessing unit (12) and/or the FCC unit (13) and/or the isomerization
unit (14). It
is then possible to treat in one or several of the units (12)-(14), one or
several of the
separated streams selected as a function of the products sought.
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Figure 3 is a graph representing the pressure variation across a reactor
during the
processing of a plastic liquefied oil without stabilization and with
stabilization.
Figures 4 to 6 are photos of the test tubes of example 4 for tests 1-3
respectively.
Examples
Example 1
An additive capable to reduce gums formation or buildup, here a phenolic
compound, BHT (butylated hydroxyltoluene), has been added to several pyrolysis
plastic
oils. Existing gums have been determined by means of NF EN ISO 6246 (2018),
potential
gums by ASTM D873-12(2018).
The characteristics of the pyrolysis plastic oils alone and with the additive
are
presented in table 1.
Table 1
Unit HPP1 HPP2 HPP3
bromine number g Brig 45 25
<1
diene value g12/g 1.2 2.4
0.8
MAV mg 4.6 9.3
3.1
anhydride
Oxygen content Wt% 0.12 0.06
0.1
Existing gums HPP mg/100mL 102 13 2
Reproducibility of the method 31 7 3
Existing gums HPP + 1000ppm BHT mg/100mL 62 12 3
Potential gums HPP mg/100mL 236 89
22
Reproducibility of the method 69 28 9
Potential gums HPP+ 1000ppm BHT mg/100mL 85 31
0.5
These results show a reduction of the formation of gums with the addition of
BHT,
particularly for potential gums.
Example 2
Tests were performed using a pyrolysis oil cut having a boiling point ranging
from 36 to
590 C, a nitrogen content of about 1500 wt ppm, a Si content of about 150 wt
ppm, a
chlorine content of about 500 wt ppm and a sulfur content of about 20 wt ppm.
The
pyrolysis oil was also characterized by a MAV at the inlet of about 7 g12/100g
and a
Bromine Number of about 60 gBr2/100g. A sulfided NiMo on alumina catalyst was
used
in dilution with silicon carbide at equal volumes.
The tests were performed in the operating conditions presented in table 2.
Table 2 ¨ test conditions
Pression (barg) 45
LHSV (h-1) 2
liquide flow rate (ml/h) 200
H2/HC (NI/I) 10
H2 flow rate (NI/h) 1.4
Inlet Temperature ( C) Start Of Run: 50
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300 wt ppm of BHT has been added to the pyrolysis oil cut before the test.
Since the
beginning of the pyrolysis oil feeding, a delta P in the reactor appears, as
shown in figure
3.
Then, the same pyrolysis oil with the 300 wt ppm of BHT and about 2000 ppm of
a
5 detergent containing sulfonate was processed and no delta P appears
during minimum
4 days (see figure 3).
Example 3
A pyrolysis oil cut HPP4 having the properties collected in table 3 has been
heated with
different additives.
Table 3 ¨ Properties of the pyrolysis oil HPP4
Unit HPP4
MAV mg anhydride 22,8
I Br g Br/g 52
diene value g12/g 5,9
Oxygen content Wt% 0,92
Existing gums mg/100mL 59
Potential gums mg/100mL 1073
The test proceeding is the following. 30m1 of pyrolysis oil cut HPP4 has been
introduced
in a test tube in glass and heated at 200 C during 2 hours in presence of a
piece of steel.
This test has been made with the HPP4 alone (Test 1), the HPP4 with 1000 wt
ppm of
BHT (Test 2), and the HPP4 with 1000 wt ppm of a mixture 50/50 of BHT and a
dispersant (Test 3). The dispersant used in test 3 is the commercial
dispersant Total
PIBSIO and contains reaction products between polyisobutylene succinic
anhydride and
tetraethylene pentaamine (CAS n'84605-20-9). At the end of the tests, the gum
quantity
in the HPP4 has been measured by the existing gum method NF EN ISO 6246 (2018)
with a lower sample quantity of pyrolysis oil cuts, and the quantity of gums
deposited on
the test tube and on the piece of steel have ween weighted, the gum contents
are
collected in table 4.
Table 4 ¨ Gum contents
Test 1 Test 2 Test 3
Gums in HPP4 153 mg/100 mL 272 mg/100 mL 225 mg/100
mL
Gums deposited
Not measured 66 mg/100 mL 37 mg/100
mL
on the test tube
Gums on the steel
Not measured 0 0
piece
Total 338 mg/100 mL 262 mg/100
mL
The photos of the tubes at the end of the tests are shown in figures 4-6. We
can
observe a difference in the colors of the deposits between the photos of the
tube with
the dispersant/BHT mixture (test 3-fig. 6) and without additive (test 1-
fig.4).
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On the other hand, the gum values are lower in the oil and on the test tube
with the
BHT/dispersant mixture (test 3) than with BHT alone (test 2). This additive
mixture
seems to be more effective than BHT alone when considering the deposits on the
test
tube only. In tests 2 and 3, no deposits were observed on the piece of steel.
These tests show a synergy of the dispersant + BHT additives for the
minimization of
deposits on the test tube compared to BHT alone. As the deposit of gums is
less
important for the BHT/dispersant mixture than with BHT, high temperatures
treatments
for a longer period can be envisaged.
Example 4
The pyrolysis oil cut HPP4 of example 3 has been tested with a tall oil
derivative as
additive which is the reaction product of tall oil fatty acid and
diethylenetriamine. The
CAS number of the tall oil derivative is 1226892-43-8.
Oxidation stability tests, such as induction period measurements, have been
performed
with and without the tall oil derivative, in presence of steel. The results
are collected in
table 5. It can be seen a net improvement of the oxidation stability in the
presence of
the additive.
Table 5 ¨ Results of Induction period Petrooxy EN 16091 :2022 measurements
0 ppm additive t 1000 ppm 0 ppm additive t 1000
ppm
= 0 additive t = 0 = 2 weeks additive
t = 2
weeks
HPP4 18,8 mn 52,1 mn 19,9 mn 35,8 mn
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