RU2805551C2 - Method for hydroconversion of polymer mixture - Google Patents

Abstract

FIELD: hydroconversion of a polymer mixture.

SUBSTANCE: invention is related to a method for hydroconversion of a polymer mixture and includes pre-treatment of the polymer mixture using methods selected from the group consisting of mechanical methods, chemical methods, thermal methods or combinations thereof, to obtain a pre-treated charge that is mixed or suspended in a hydrocarbon residue under vacuum distillation. The above-mentioned pre-treated charge is mixed with the hydrocarbon residue of vacuum distillation. A mixture of reagents in the suspension phase of an oil-soluble catalyst precursor containing molybdenum, said precursor being liquid, and a stream containing hydrogen are supplied to the hydroconversion section, and hydroconversion reactions are carried out to produce a waste reaction product. The effluent reaction product is separated in at least one high-pressure and high-temperature separator into a vapor phase and a suspension phase. The separated vapor phase is sent to a gas processing section with the function of separating the liquid fraction from the gas containing hydrogen and hydrocarbon gases containing from 1 to 4 carbon atoms; wherein said liquid fraction contains naphtha, atmospheric gas oil (AGO), and vacuum gas oil (VGO). The suspension phase is sent to the separation section, which has the function of separating the fractions of vacuum oil (VGO), heavy vacuum gas oil (HVGO), light vacuum gas oil (LVGO), atmospheric gas oil (AGO) from the stream of heavy organic products that contain asphaltenes, the unconverted feed, the catalyst and the solid formed during the hydroconversion reaction. A portion of said heavy organic products is recycled to the hydroconversion section or mixed with the pre-treated feed prior to being sent to the hydroconversion unit; wherein the remainder of said heavy organic products, which is not recycled to the hydroconversion section or mixed with the pre-treated feed before being supplied to the hydroconversion, forms a purge stream.

EFFECT: production of light hydrocarbon fractions as a result of the implementation of suspension hydroconversion technologies.

27 cl, 19 ex, 4 tbl, 2 dwg

Description

Cross reference to related applications

This patent application claims priority to Italian Patent Application No. 102018000020818, filed December 21, 2018, the full disclosure of which is incorporated herein by reference.

Field of technology to which the invention relates

The present invention falls within the field of chemical plastic recycling processes that function to add value to plastic materials otherwise destined for disposal in landfills or waste incineration for energy.

In particular, the present invention relates to a hydroconversion process using slurry technology that converts mixtures of polymers or plastics primarily into hydrocarbons having a boiling point ranging from 65°C to 170°C, also known as naphtha. naphtha fraction).

The present invention falls within the scope of methods for depolymerizing plastics, which may follow a molecular or chemical type approach.

In the molecular approach, polymers are processed to produce the monomers used initially. Instead, using a chemical approach, it is possible to obtain structural elements for the petrochemical industry from plastics.

The present invention corresponds to the chemical recycling approach, which is of the chemical type, precisely because it starts from polymeric or plastic materials to obtain as a product mainly naphtha, which is one of the main reagents for the production of plastics.

The proposed solution makes it possible to insert plastic materials into the circular economy loop, which would otherwise be destined for disposal in landfills or waste incineration for energy, which has a positive impact on reducing the consumption of raw materials of fossil origin (polymers). materials of petroleum origin) and plant origin (bio-based polymer materials). Thus, these materials are given value due to the production of light hydrocarbon fractions as a result of the implementation of suspension hydroconversion technologies, for example, the Eni suspension technology hydroconversion method (EST).

As used in this patent application, the term “polymer blends” is intended to mean a solid mixture of one or more polymers, possibly containing additives of organic or inorganic origin.

In this patent application, the term “suspension phase” is intended to mean a mixture of liquid and solid.

As used in this patent application, the term “purging” is intended to mean slurry phase organic streams that contain an amount of hydrocarbons having a boiling point greater than or equal to 540°C, greater than 65% by weight, an amount of asphaltenes greater than or equal to equal to 20% (wt.), and characterized by a solid content greater than or equal to 4% (wt.), the remainder being hydrocarbons having a boiling point between 350°C and 500°C. Purge solids contain carbonaceous residues and metal compounds, which may include transition metal sulfides such as, for example, molybdenum, iron, nickel and vanadium, and are submillimeter in size.

For the purposes of this discussion, the term “solid” is intended to designate the fraction insoluble in tetrahydrofuran, which is referred to herein by the acronym THF-i.

For the purposes of this discussion, the term "asphaltenes" is intended to designate the organic fraction that is soluble in tetrahydrofuran but insoluble in n-pentane.

Asphaltenes are classified according to their insolubility in n-paraffins (typically containing 5 to 7 (C5 - C7) carbon atoms). Such compounds are generally formed by cores of variously branched aromatic polycondensates and are connected to each other through linear chains. These compounds may contain heteroatoms (S, N), which give them their polar nature.

As used herein, the term "cake" is intended to mean a solid material at room temperature exhibiting glassy characteristics (i.e., the appearance of the cake exhibiting glassy characteristics) that make it easily crushable and therefore transportable even over long distances without thermostatic control. . This characteristic is maintained at temperatures in the range between 50°C and 60°C.

Cake is hard at room temperature, exhibiting a softening point ranging between 80°C and 100°C, and a penetration rate ranging from 2 dmm to 5 dmm (dmm indicates decimmimeters). The softening point is the temperature at which a hard cake becomes soft and indicates the temperature dependence of cake consistency. Penetration is measured in accordance with ASTM-D5-06 and expresses the penetration experienced by a material at room temperature under the influence of a needle of known weight, in decimillimeters.

Cake consistency is determined by the presence of solids (THFi) at a higher concentration than other streams and the presence of asphaltene compounds.

The cake contains solids that were previously defined in the text of this patent application.

The cake solid contains carbonaceous residues and metal compounds, which may include transition metal sulfides such as, for example, molybdenum, iron, nickel and vanadium, and are submillimeter in size.

In this patent application, the term “maltenes” is intended to designate a set of those compounds that are soluble in both tetrahydrofuran and n-pentane.

As used in this patent application, the term "styrene residue" is intended to mean an industrial by-product originating from the production of styrene and ethylbenzene and/or the production of styrene polymers/copolymers. In particular, it includes aromatic organic compounds such as, for example, benzene, ethylbenzene, styrene, toluene, xylenes, propylbenzenes, alpha-methylstyrene, polyethylbenzenes, styrene oligomers, SAN (styrene-acrylonitrile) copolymer oligomers, polycyclic aromatic hydrocarbon compounds (naphthalene , anthracene, fluoranthene and the like); both short-chain hydrocarbons, that is, with a carbon atom content less than or equal to 12, and long-chain hydrocarbons, that is, with a carbon atom content equal to or greater than 12, mineral oils containing carbon atoms in the amount contained in ranges between 10 and 40; other unsaturated compounds, such as, for example, acrylonitrile, and mixtures of the above components.

As used in this patent application, the term "phenolic residue" is intended to mean an industrial by-product derived from the production of phenol and its derivatives, such as cyclohexanone and cyclohexanol. In particular, the phenolic residue may contain aromatic organic compounds such as phenol, cresols, acetophenone, cumene, alpha-methylstyrene; both short-chain hydrocarbons, that is, with a carbon atom content less than or equal to 12, and long-chain hydrocarbons, that is, with a carbon atom content equal to or greater than 12, mineral oils containing carbon atoms in the amount contained in ranges between 10 and 40, and mixtures of the above components.

In this patent application, all operating conditions reported in the text are to be understood as preferred conditions, even if there is no clear statement to that effect.

For purposes of this discussion, the term “comprises” or “includes” also includes the term “consists of” or “essentially consisting of.”

For the purposes of this discussion, definitions of intervals always include boundary values unless otherwise noted.

Hydroconversion is usually carried out from heavy oil-containing products and can be achieved through the use of various technological schemes.

As used in this patent application, the term "heavy oil products" is intended to include crude oils, heavy crude oils, tar sands bitumen, distillation residues, heavy distillates, deasphalting residues, Fischer-Tropsch synthetic oils, vegetable oils, oils produced from coke and oil shale, oils obtained from the thermal decomposition of waste, polymers, biomass.

State of the art

A hydroconversion reactor can traditionally be of a fixed bed type, a fluidized bed type, or a slurry bed type. In a slurry reactor, the catalyst is dispersed in the reaction medium and distributed uniformly within the reactor itself.

A possible configuration of the heavy petroleum hydroconversion process consists of suspension technology from Eni, which is proprietary to Eni and is known by the acronym EST.

This configuration provides a hydroconversion section in which the reactors are charged with a molybdenum-based catalyst sized to be completely dispersed in the reaction medium to enable slurry phase operation. The reaction produces an overhead effluent that is subsequently sent to a separator section that includes at least one high pressure/high temperature (HP/HT) phase separator.

The vapor phase leaving the HP/LT separator is sent to a section from which, as a result of condensation, naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO) and a gas stream enriched in hydrogen, which contains C1 - C4 gas, are recovered, and which is recycled to the hydroconversion section except for a gas sample which may be introduced into the reaction effluent.

The bottom stream leaving the HP/LT separator is in suspension phase and is sent to a separation section, which typically includes a series of pressure and temperature reducing devices - such as a medium pressure separator, an atmospheric distillation column and a vacuum distillation column - in for the purpose of separating VGO from heavier products.

The heavy underflows contain the unconverted feed, the catalyst, and the solid formed during the reaction. A portion of said heavy products is recycled to the reaction section and the remainder is removed from the process as a purge stream. The purge stream may in turn be sent to a separation section to produce a dense stream called cake and a less dense stream called clarifier. This latter stream may be recycled to the reaction section, mixing section, or removed from the process.

The reaction products of the EST process can also be produced solely in the vapor phase, as is the case in the EST with vapor phase extraction (EST-VPO) process described in several patent applications corresponding to progressive technology development. Applicant briefly summarizes below patent applications that use EST-VPO technology.

Publication WO 2008/141830 describes a process for the hydroconversion of heavy oils, in which the reaction takes place in a bubble-type reactor capable of accumulating at least 50 kg/m ³ of solids, fueled by hydrogen or a mixture of hydrogen and sulfur. acid, in which hydrogen is characterized by a mass fraction relative to the load of at least 0.3. The concentration of molybdenum used as catalyst is at least 5 kg per 1 m ³ of loading.

Publication WO 2008/141831 describes a system for the hydroconversion of heavy oils, which consists of a solids accumulation reactor and a stripping section outside or inside the reactor. With an internal stripping section, the reactor may be completely or partially filled, and the stripping section may be located at the top of the reactor or downstream of a channel within the reactor. When the stripping section is located externally, the reactor, completely filled, ensures the presence of a circuit for the forced delivery of the liquid phase for recycling into the reactor itself. It is also possible to have a separator in the vapor-liquid system downstream of the reactor.

Publication WO 2016/103199 describes a system for the hydroconversion of heavy oils, including a reactor, a separator in the vapor-liquid system and a stripping section for the conversion products outside the reactor. Stripping gas is introduced directly into the reaction effluent through a stripping gas introduction channel located at a point in the connecting channel between the top of the reactor and the separator in the vapor-liquid system, said connecting channel being inclined at least from the injection point and extending from the bottom. upward at an inclination between 2% and 20% relative to the horizontal plane. The channel for introducing the stripping gas is inclined relative to the axis of the connecting channel between the top of the reactor and the separator in the vapor-liquid system at an angle between 20° and 65°. The flow of stripping gas, which is introduced into the connecting channel between the top of the reactor and the separator, is directed from top to bottom. After stripping, the effluent is sent to an HP/HT phase separator to separate the liquid phase, also containing a small amount of solid (reaction solids and dispersed catalyst), which is sent for recycling to the reactor, and the vapor phase containing the products reactions.

Publication WO 2018/078555 describes a process for the hydroconversion of heavy oil products which are reacted in a hydroconversion reactor, together with a reprocessing comprising hydrogenation gas, and in the presence of a suitable catalyst producing a two-phase waste product.

The reaction effluent is fed to a high-pressure, high-temperature stripping step, which is carried out at the reaction pressure, using a stream as a stripping gas having the same composition as the gas fed to the reactor; and thus producing a vapor phase flow and a suspension phase flow containing heavy products and solids. The suspension is partially sent for recycling to the hydroconversion section, and partially selected, continuously forming a flow of the purged substance. Several processes have been developed to treat the purge in order to recover components that can be added value, such as catalyst metals.

WO 2014/025561 describes a process for recovering hydrocracking catalyst from an off-product coming from a slurry hydrocracking zone. The mentioned method proposes separating the waste product into a first stream containing a solvent and a clarified substance (pitch), and a second stream containing pitch and a catalyst.

Separation may take place by centrifugation, filtration, decanting, or electrostatic separation. The second stream is subjected to acid leaching treatment to extract the catalyst to provide an aqueous solution and a residue. The aqueous solution is then treated with anions to produce an insoluble salt, a catalyst, and additional aqueous solution.

Publication US 2013/0247406 describes an integrated method that includes:

- a method of adding value to heavy crude oils by converting them into lighter products in the presence of a catalyst;

- an oil removal process in which heavy residues and heavier products resulting from the processing of heavy crude oils are separated under the influence of spent catalyst, which is subsequently recovered;

- catalyst synthesis zone.

Catalyst separation occurs as a result of treatment using membrane filtration technologies and a subsequent thermal devolatilization step.

WO 2009/070778 describes a process for recovering metals from spent slurry catalyst that adds value to heavy oils. According to WO 2009/070778, the phase containing the spent catalyst is pyrolyzed and the pyrolysis residue is contacted with an ammonia-containing leach solution and air to dissolve the Group VIB and VIII metals to form a slurry under pressure. Said suspension contains at least one soluble group VIB and VIII metal complex, ammonium sulfate and a solid residue containing at least one group VB metal complex and coke.

Subsequently, the solid residue containing ammonium metavanadate and coke from the compressed suspension is separated and removed. Some metals from group VIII are precipitated. Precipitation is carried out at a predetermined pH value to selectively precipitate a portion of the metal complexes from Groups VIB and VIII.

Publication US 2010/0122938 relates to a process for separating ultrafine solid hydrocracking catalysts from a liquid hydrocarbon slurry, said solids being present in an amount ranging between 5% and 40% by weight. The method includes the following steps:

- cooling the suspension stream containing hydrocarbons and solids, preferably at a temperature in the range from 55°C to 75°C;

- mixing said cooled stream with a solvent at a solvent/suspension weight ratio ranging from 3:1 to 1:3 to obtain a first mixture containing liquid hydrocarbons, a solvent and a stream containing a heavy hydrocarbon that encapsulates the catalyst solid;

- separating the first mixture in a first centrifuge to obtain a second mixture containing a small concentration of a heavy hydrocarbon that encapsulates the catalyst solid, and a third mixture containing a heavy hydrocarbon that encapsulates the catalyst solid;

- separating the second mixture in at least one second centrifuge to obtain a fourth mixture containing solvent and liquid hydrocarbons, and a fifth mixture containing a significant concentration of heavy hydrocarbon that encapsulates the catalyst solid;

- mixing the third mixture and the fifth mixture to obtain the final mixture;

- drying the final mixture to obtain a mixture of hydrocarbons with impurities in the vapor phase and a solid residue related to the type of coke;

- separation of impurities from hydrocarbons and extraction of solid residue.

US Publication No. 7,790,646 describes a process for converting fine catalysts present in amounts ranging between 5 and 40% by weight and contained in a slurry stream together with heavy oils in coke-type materials from which catalyst metals are recovered. The method includes the following stages:

- mixing a suspension containing heavy oils and spent catalyst containing metal sulphides from groups VIII and VI with a solvent, preferably at a volume ratio ranging between 0.5/1 and 5/1, preferably at a temperature in the range of 25° C to 80°C, which thus leads to the precipitation of asphaltenes;

- separation, preferably by decanting and/or centrifugation, of spent catalyst and precipitated asphaltenes from heavy oils and solvent;

- transformation of precipitated asphaltenes into coke-like material containing metals, which will be extracted as a result of thermal pyrolysis.

Publication EP 2440635 describes a process for recovering metals from a hydrocarbon-enriched stream and carbon residues, which includes the following steps:

- sending said stream to a primary treatment carried out in one or more stages, during which said stream is subjected to treatment in the presence of a diluting agent in a suitable apparatus at a temperature ranging from 80°C to 180°C and subjected to separation in a liquid/liquid system solid to produce a clarified substance consisting of liquids and cake;

optionally subjecting said separated cake to drying to remove the hydrocarbon component which exhibits a reduced boiling point at a temperature in the range of 300° C. to 350° C. from the cake;

- sending said cake, optionally dried, for secondary heat treatment, which includes:

○ flameless pyrolysis at a temperature between 400°C and 800°C;

○ oxidation of the pyrolysis residue, carried out under oxidizing conditions and at a temperature between 400°C and 800°C.

Patent application US 2010/0326887 describes the separation of non-tacky pitch from a hydrocarbon slurry through a distillation treatment that brings the vacuum gas oil (VGO) level of the final product to less than 14% by weight. The solids are concentrated in the bottom of the column to produce pitch.

Publication WO 2017/109728 describes a method for treating refinery plant blowdown streams, which includes the following steps:

• collecting a purge stream from a refinery plant containing a hydrocarbon component in suspension phase exhibiting a boiling point greater than or equal to 140°C, characterized by the presence of quantities of asphaltenes greater than or equal to 5% (wt.), and characterized by the presence of a solids content level, greater than or equal to 5% (wt.);

• mixing, at a temperature greater than or equal to 100°C, said purge substance with a mixture of hydrocarbons or diluent having a total aromatic content between 50% and 70% (w/w) and an initial boiling point of or greater compared to the temperature at which mixing is carried out, so as to obtain a suspension characterized by a level of greater than or equal to 10% (wt.), compounds exhibiting a boiling point T _bp less than or equal to 350°C;

• sending said suspension to a separation stage in a liquid-solid system that operates at a temperature greater than or equal to 100°C, separating the solid phase containing the residual organic component and the solid component - the cake - and the liquid phase containing the solid residues;

• cooling the solid phase thus obtained below 60°C and storing it by keeping it at a temperature less than or equal to 60°C.

In the mentioned method, the mass ratio between the blown substance and the diluent varies between 1:0.5 and 1:4, and the average residence time of the mixture during mixing and before separation in the liquid-solid system is less than or equal to 12 hours . As previously stated, the purge flow is a value ranging between 6% and 8% of the fresh charge, so that the total conversion that can be obtained under normal operating conditions would range from 92% to 94 %.

The literature documents the possibility of producing liquid fuels from waste from the processing of plastic materials. The methods used can be catalytic or thermal. Some of these documents are listed:

• Production of Liquid Fuels from Waste Plastics, THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, VOLUME 77, OCTOBER, 1999;

• Feedstock Recycling and Pyrolysis of Waste Plastics: Converting Waste Plastics into Diesel and Other Fuels Edited by J. Scheirs and W. Kaminsky 2006 John Wiley & Sons, Ltd ISBN: 0-470-02152-7;

• Chemical Recycling of Plastic Waste (PVC and other resins); TNO-report STB-99-55 Final; Tukker, de Groot, Simins, Wiegersma; December 1999 (ASSIGNOR: European Commission, DG II).

The purely thermal decomposition of polymer waste has been studied on both laboratory and semi-industrial scales.

For the class of polymers belonging to the styrene type, good yields of styrene (greater than or equal to 75%) can be obtained by fast pyrolysis (depolymerization using a molecular approach). In order to effectively implement this depolymerization method and obtain the original styrene monomer, only a polystyrene charge must be supplied to the method; the method is not effective when a mixture of polymers is used as a charge.

For polyethylenes, polypropylenes and polyvinyl chloride, monomer yields are small, and mainly high molecular weight hydrocarbons (oils) and gases characterized by high calorific value are produced. This suggests that polymers such as polyethylenes, polypropylenes and polyvinyl chloride cannot be depolymerized into monomers or into building blocks in the plastics production chain.

On the other hand, the mentioned classes of polymers, when processed in a mixture, form low-quality fuel oils that must be upgraded in order to add value based on their lower heating value. Therefore, low-efficiency recycling of plastics into energy is discussed here. In addition, the formation of coke as a by-product is also stimulated, which causes fouling of the corresponding installations and the impossibility of continuous operation. Due to these critical aspects, this method is not used on an industrial scale.

Catalytic plastic conversion processes vary in nature and typically involve thermal pre-treatment of the plastic material to produce a heavy hydrocarbon (heavy oil) that can be fed to a catalytic hydroconversion process to produce hydrocarbons, including naphtha.

Disclosure of the Invention

For this purpose, the applicant has discovered a method for hydroconversion of polymer mixtures, which includes the following stages:

• pre-treatment of the polymer mixture using methods selected from mechanical methods, chemical methods, thermal methods or combinations thereof to obtain a pre-treated load;

• mixing said pre-treated charge with a hydrocarbon vacuum residue, optionally pre-heated, to obtain a mixture of reactants;

• feeding into the hydroconversion section a mixture of reagents in the suspension phase, a catalyst precursor containing molybdenum, and a stream containing hydrogen, and conducting a hydroconversion reaction to produce a waste reaction product;

• separating the reaction product effluent in at least one high pressure/high temperature separator into a vapor phase and a suspension phase;

• after this, sending the separated vapor phase to the gas processing section, which has the function of separating the liquid fraction from the gas containing hydrogen and hydrocarbon gases containing from 1 to 4 carbon atoms; wherein said liquid fraction contains naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO);

• after this, sending the suspension phase to the separation section, which has the function of separating the fractions of vacuum oil (VGO), heavy vacuum gas oil (HVGO), light vacuum gas oil (LVGO), atmospheric gas oil (AGO) from the stream of heavy organic products, which contain asphaltenes, unconverted feed, catalyst and solid formed during the hydroconversion reaction;

• sending a portion of said heavy organics for recycling (recycling a portion of said heavy organics) to the hydroconversion section or mixing them with the pre-treated feed prior to hydroconversion and with the residue to produce a purge stream.

One further embodiment of the present invention is a solid phase polymer blend that contains:

- one or more polymers, preferably all polymers selected from:

○ ethylene polymers or copolymers, mixtures thereof; preferably selected from high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE), metallocene catalytic polyethylene (m-PE), polymers ethylene vinyl acetate (EVA) and mixtures thereof;

○ propylene polymers or copolymers, mixtures thereof; preferably selected from polypropylene (PP) or ethylene-propylene-diene monomer (EPDM) rubbers and mixtures thereof;

○ styrenic polymers or copolymers, mixtures thereof: preferably selected from polystyrene (PS), expanded polystyrene (EPS), high impact polystyrene (HIPS), acrylonitrile styrene butadiene polymers (ABS), styrene acrylonitrile copolymers (SAN), styrene block copolymer -butadiene-styrene (SBS), block copolymers of styrene-ethylene-butylene-styrene (SEBS) and mixtures thereof;

○ vinyl chloride polymers or copolymers or vinylidene dichloride copolymers, mixtures thereof, preferably selected from polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) and copolymers thereof and mixtures thereof;

○ polyesters, preferably selected from polycarbonate (PC), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid (PLA), poly(L-lactic acid) (PLLA), poly(D-lactic acid) ) (PDLA), poly(D,L-lactic acid) (PDLLA), polyhydroxyalkanoate (PHA) and mixtures thereof;

○ polyamides, preferably selected from nylon 6 (PA6), nylon 66 (PA66), nylon 46 (PA46), nylon 12 (PA12);

○ polymers containing urethane bonds and preferably selected from polyurethanes (PU) containing aliphatic or aromatic groups or ester or ether or urea groups, and mixtures thereof;

○ polymers derived from cellulose, preferably selected from cellulose nitrate, cellulose acetate, cellulose acetate butyrate, cellulose propionate, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, benzylcellulose and regenerated cellulose and mixtures thereof;

○ their mixtures,

- possibly additives of organic or inorganic origin, having, for example, the function of antioxidants, heat stabilizers, antacids, nucleating agents, UV stabilizers, anti-caking agents, friction-reducing agents, anti-slip agents, plasticizers, external lubricants, release agents, flame retardants, polymer processing additives, dyes (organic and inorganic), antistatic agents, cross-linking agents, cross-linking additives, extending oils, vulcanization accelerators, anti-ozone depleting agents and mixtures thereof.

In an advantageous case, when using the described and claimed method, it is possible to demonstrate the flexibility of loadings in the hydroconversion method and the possibility of chemical recycling of polymers, while naphtha is at the base of the petrochemical chain. In this way, it is possible to add value to a waste product by recycling plastics or polymers.

The described and claimed method makes it possible to increase the naphtha fraction due to the conversion of the polymer load.

In addition, it concentrates the inorganic components present in the original polymer mixture into solid residues without contaminating hydrocarbon products. The products obtained using the hydroconversion process of polymer mixtures lead to the production of monomers included in the synthetic chain of plastic materials suitable for use in each application.

One of the main disadvantages of producing products from mechanical recycling of plastic materials appears to be that it is not always possible to repurpose the product resulting from mechanical recycling for the same application from which the waste was generated. In fact, there are applications that are very sensitive to contaminants present in waste collection streams (eg "food" applications, i.e. food contact).

Instead, the process described produces naphtha, which can be used in the supply chain to synthesize polymers that can also be used in "food" applications (which generate the largest portion of post-consumer waste).

Hydroconversion technology, or EST, incorporates the inherent benefits of hydroconversion chemical recycling processes in all cases while avoiding one of the major critical aspects, which is catalyst deactivation due to impurities introduced when using a polymer feed.

In detail, as a result of hydroconversion of plastic materials when using hydroconversion or using EST technology, the following occurs:

- high yield of naphtha;

- narrow distribution of outgoing products;

- high quality of the product (high H/C ratio, low level of aromatic compounds);

- the possibility of using a heterogeneous mixture of polymer materials as a load.

Brief description of drawings

Additional objects and advantages of the present invention will become more clearly understood from the following description of the invention and the accompanying figures, given by way of non-limiting example only, which represent preferred embodiments of the present invention.

Fig. 1 shows one preferred embodiment of the method according to the present invention, in which a mixture of polymers (1) is fed to a pre-treatment section (G); the pretreated mixture is then mixed in (F) with the vacuum residue (14) and the catalyst precursors (2) together with the heavy product (12) and the clarified product (11) to thereby obtain a mixture of reactants ( 15).

After this, the mixture of reagents (15) is fed into the hydroconversion reactor (A) together with a stream containing hydrogen. The reaction product effluent is fed to a high pressure/high temperature separator (B), which forms a gas stream (5) and a slurry (7). The gas (5) is supplied to the processing section (C), where the gas stream containing hydrogen (4) is separated from the naphtha, atmospheric gas oil (AGO) and vacuum gas oil (VGO) (liquid fraction) specified in position 6. Part gas stream containing hydrogen is purged (16), while the remainder (4) is mixed with make-up hydrogen (3), and the resulting stream is fed into the hydroconversion reactor (A) with at least one saturation gas (13 ) are taken from gas reprocessing (gas recirculation) and fed to the bottom of the high pressure and high temperature separator (B).

The slurry (7) is fed to the separation section (D) to separate the vacuum gas oil (VGO) from the heavy product, which is partially recycled to the mixing section (12, F) and partially forms a purge stream (9). The purge is subjected to liquid-solid separation (E), where the heavy or dense phase (10) is separated from the light or clear phase (11), which is recycled to the mixing section (F).

Fig. 2 illustrates one preferred embodiment of the process according to the present invention, in which catalyst precursors (2) are supplied to the hydroconversion section (A); part of the heavy product is recycled into the hydroconversion reactor (A), the clarified substance product (11) is recycled into the hydroconversion reactor (A). The rest of the method is similar to that described in FIG. 1.

Best Mode for Carrying Out the Invention

The method for hydroconverting polymer mixtures, which is the object of the present patent application, will now be described in detail, also with reference to FIG. 1 and fig. 2.

The polymer mixture (1) is suitably pre-treated and then mixed with the vacuum distillation residue (14). The catalyst precursors (2) can be fed to a mixer (F) or to a hydroconversion reactor (A). The mixture (15) is then subjected to a hydroconversion reaction producing hydrocarbons having a lower boiling point than the original charge. In particular, the transformation of the mixture of polymers into hydrocarbon products having boiling points preferably in the range from 65°C to 170°C, which are also known as naphtha fraction, is observed.

As used in this patent application, the term “vacuum residue” is intended to refer to the residual stream of industrial origin that remains after vacuum distillation of a stock of crude oils entering a refinery.

For the purposes of the present invention, the mixture of polymers mixed with a vacuum distillation residue contains polymer waste originating, for example, from the sorting cycle of heterogeneous municipal solid plastic waste, from selection from unsorted municipal solid waste, from waste from industrial, craft, commercial and agricultural activities . The processed polymer mixtures are in the solid phase and contain:

- one or more polymers, preferably all polymers, selected from the following classes:

○ ethylene polymers or copolymers, mixtures thereof; preferably selected from high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE), metallocene catalytic polyethylene (m-PE), polymers ethylene vinyl acetate (EVA) and mixtures thereof;

○ propylene polymers or copolymers, mixtures thereof; preferably selected from polypropylene (PP) or ethylene-propylene-diene monomer (EPDM) rubbers and mixtures thereof;

○ styrenic polymers or copolymers, mixtures thereof: preferably selected from polystyrene (PS), expanded polystyrene (EPS), high impact polystyrene (HIPS), acrylonitrile styrene butadiene polymers (ABS), styrene acrylonitrile copolymers (SAN), styrene block copolymer -butadiene-styrene (SBS), block copolymers of styrene-ethylene-butylene-styrene (SEBS) and mixtures thereof;

○ vinyl chloride polymers or copolymers or vinylidene dichloride copolymers, mixtures thereof, preferably selected from polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) and copolymers thereof and mixtures thereof;

○ polyesters, preferably selected from polycarbonate (PC), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid (PLA), poly(L-lactic acid) (PLLA), poly(D-lactic acid) ) (PDLA), poly(D,L-lactic acid) (PDLLA), polyhydroxyalkanoate (PHA) and mixtures thereof;

○ polyamides, preferably selected from nylon 6 (PA6), nylon 66 (PA66), nylon 46 (PA46), nylon 12 (PA12);

○ polymers containing urethane bonds and preferably selected from polyurethanes (PU) containing aliphatic or aromatic groups or ester or ether or urea groups, and mixtures thereof;

○ polymers derived from cellulose, preferably selected from cellulose nitrate, cellulose acetate, cellulose acetate butyrate, cellulose propionate, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, benzylcellulose and regenerated cellulose and mixtures thereof;

○ their mixtures,

- possibly additives of organic or inorganic origin, having, for example, the function of antioxidants, heat stabilizers, antacids, nucleating agents, UV stabilizers, anti-caking agents, friction-reducing agents, anti-slip agents, plasticizers, external lubricants, release agents, flame retardants, polymer processing additives, dyes (organic and inorganic), antistatic agents, cross-linking agents, cross-linking additives, extending oils, vulcanization accelerators, anti-ozone depleting agents and mixtures thereof.

The inorganic component of the polymer mixture (consisting of ash) and the unconverted polymers are instead concentrated in a fraction designated THF-i (tetrahydrofuran insoluble).

One preferred blend contains 35 - 60% (wt) polyethylene (PE), 15 - 40% (wt) polypropylene (PP), 0 - 25% (wt) polystyrene (PS), 0 - 15% (wt) ) polyethylene terephthalate (PET), 0 – 5% (wt.) polyvinyl chloride (PVC), 0 – 15% (wt.) inorganic loads.

The polymer mixtures are mixed with the vacuum distillation residue, preferably at 5% by weight, more preferably at 20% by weight.

The method which is the object of the present patent application includes several steps, including a polymer mixture pre-treatment step (G), which aims to obtain a polymer mixture mixed or suspended in the vacuum distillation residue (vacuum distillation oil); and a stage of hydroconversion (A) of a mixture of reagents for the production of hydrocarbon products, preferably a fraction of naphtha. Naphtha is at the base of the petrochemical chain and thus makes it possible to add value to waste product from recycling plastics or polymers.

The polymer mixture (1) may be pre-treated using methods selected from mechanical methods, chemical methods, thermal methods or combinations thereof in a pre-treatment section (G) to obtain a pre-treated charge.

Preferred mechanical pre-treatments include grinding, also at low temperature, of the polymer mixture to reduce the average size of the D ₅₀ batch itself to less than or equal to 1 mm.

The particle size distribution of the ground polymer mixture was assessed using light scattering measurements carried out using a Mastersizer 2000 device (Malvern Instruments). Size (MT50 or D ₅₀ ) is measured using a laser granulometer and is the diameter corresponding to 50% by weight of particles having a smaller diameter and 50% by weight of particles having a larger diameter.

Preferred chemical pretreatments include options selected from:

- obtaining a polymer mixture in an acidic or basic atmosphere at room temperature, preferably selected from an aqueous solution of H ₂ SO ₄ at 10% (w/w), an aqueous solution of NaOH at 10% (w/w), an aqueous solution of Ca (OH) ₂ at 10% (w/w);

- preparing a polymer mixture with hydrocarbon compounds at low or high molecular weight at room temperature; preferably selected from "styrenic residues" and/or "phenolic residues".

Preferred thermal pretreatments include a method that involves heating the polymer mixture to a temperature T greater than or equal to 200° C. in an inert environment, possibly also using equipment such as extruders, thereby making it possible to achieve a homogeneous mixing of polymer components and the best subsequent mixing with vacuum distilled oil.

The pre-treatments may preferably be combined with each other in order to obtain the best stability of the final solution or suspension.

The pre-treatments can also be combined with each other, with preferred combinations being the following:

- the polymer mixture is crushed, also using low-temperature grinding, in order to reduce the average size for the load itself D ₅₀ to a value less than or equal to 1 mm; the ground polymer mixture is then added to acids or bases at room temperature, preferably selected from aqueous H ₂ SO ₄ at 10% (w/w), aqueous NaOH at 10% (w/w), aqueous solution Ca(OH) ₂ at 10% (w/w), styrene residues and/or phenolic residues; or

- the polymer mixture is crushed, also using low-temperature grinding, in order to reduce the average size for the load itself D ₅₀ to a value less than or equal to 1 mm; thereafter, the crushed polymer mixture is reheated to a temperature T greater than or equal to 200°C in an inert environment; or

- the polymer mixture is heated to a temperature greater than or equal to 200°C in an inert atmosphere, after which the heated polymer mixture is added to acids or bases at room temperature, preferably selected from an aqueous solution of H ₂ SO ₄ at 10% (wt./mass. ), aqueous NaOH solution at 10% (w/w), aqueous Ca(OH) ₂ solution at 10% (w/w), styrene residues and/or phenolic residues.

Immediately after pre-treatment of the charge, it can be mixed in the mixing section (F) with the hydrocarbon residue of the vacuum distillation, optionally preheated, to obtain a mixture of reactants, which can subsequently be fed to the hydroconversion section in suspension phase (A). A catalyst precursor containing molybdenum may also be added to this phase; otherwise, said precursor may be added to the reactor.

The mixture thus obtained, and optionally the precursors, is fed together with the hydrogen-containing stream to a hydroconversion reactor (A) to carry out a hydroconversion reaction producing a reaction effluent.

Preferably, the slurry phase hydroconversion reactor is a bubble column. One or more hydroconversion reactors arranged in parallel may be used; similarly, one or more high pressure and high temperature separators located in parallel can be used.

Preferably, a portion of the hydrogen-containing recycle gas (13) is supplied to the high-pressure-high-temperature separator.

The reaction effluent may be separated in at least one high pressure/high temperature separator (B) into a vapor phase and a slurry phase. The separated vapor phase can subsequently be sent to a vacuum processing section (C), which has the function of separating the liquid fraction from the hydrogen-containing gas.

The steam processing section operates at gradually decreasing pressure and temperature.

Said section may include heat exchangers interleaved by a wash column using VGO as a solvent, a high-pressure-medium-temperature separator, and a high-pressure-low-temperature separator.

From the steam processing section, naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO) and a hydrogen-enriched gas stream containing hydrocarbon gases containing 1 to 4 carbon atoms are recovered and sent for recycling to the hydroconversion section (4) except for the gas sample, which can be fed into the high pressure and high temperature separator (B).

The suspension phase can subsequently be sent to the separation section (D), which has the function of separating the fractions of vacuum gas oil (VGO), heavy vacuum gas oil (HVGO), light vacuum gas oil (LVGO), atmospheric gas oil (AGO) from the heavy stream organic products that contain asphaltenes, unconverted feed, catalyst and solids formed during the hydroconversion reaction.

Said liquid separation section (D) may preferably include a series of pressure and temperature reducing devices. In the first stage, the suspension is fed into a high temperature and low pressure separator, which acts as a storage tank; in the second stage, the separated vapor phase is fed to a pre-flash column, finally the bottoms current is fed to a stripper column to separate light oils, and finally in the third stage, the enriched stream leaving the stripper column is fed to a vacuum distillation column; alternatively, there is no stripper column and the bottom stream is fed to a vacuum distillation column. From the vacuum column, a vacuum gas oil (VGO) fraction, a light vacuum gas oil (LVGO) fraction, a heavy vacuum gas oil (HVGO) fraction, washing oil and a vacuum residue are recovered from the vacuum column. The vacuum distillation residue leaves the vacuum column bottom and is enriched in asphaltenes, solids, metals and catalysts and forms a heavy product stream.

One part of the heavy products (12, Fig. 1) is sent for recycling to the mixing section (F) or to the suspension phase hydroconversion section (12, Fig. 2), while the rest forms the purge stream (9).

The method described and claimed may include an additional purge treatment step which provides a liquid-solid separation treatment selected from sedimentation, filtration or centrifugation.

In the first separation method, the purge may be heated to a temperature greater than or equal to 185°C and no more than 220°C, preferably in the range between 200°C and 220°C.

Subsequently, the hot purge material can be cooled by a progressive and controlled reduction in temperature to a minimum temperature of 100°C, preferably between 100°C and 170°C, more preferably between 100°C and 160°C, without mixing the blown substance in such a way as to obtain a light phase (clarified substance) and a heavy phase (cake) depending on the density.

Controlled temperature reduction can occur in various ways:

• when using a properly sized and temperature-controlled container, such as a temperature-controlled hot oil tank, or

• as a result of mixing a decanted warm stream, for example, a heated blown substance, with a cold stream, for example, a clarified substance, which may have a temperature ranging from 200°C to 80°C, taking into account the proper thermal balance of the system to calculate their flow rates .

The controlled temperature reduction is in the range of 3°C per minute to 10°C per minute, preferably 5°C per minute to 10°C per minute, more preferably 10°C per minute.

The cooled blown substance may be subjected to sedimentation, for example, in a static sedimentation tank (E); During static sedimentation the temperature must be such as to render the asphaltenes insoluble and at the same time render the part in the form of clarified substance mobile, making it possible to extract it.

In the temperature range between 100°C and 160°C, separation of the dense phase (cake) is optimal.

During the sedimentation phase, the purged substance is not shaken. Sedimentation produces a light phase called clarified matter and a heavy phase called cake, depending on density.

The time required for the formation of the heavy phase or cake may preferably range from 15 minutes to 2 hours, more preferably it ranges from 20 minutes to 1 hour. The sedimentation rate is preferably between 85 mm/hour and 300 mm/hour.

The produced cake is "glassy" at room temperature, exhibiting a softening point that can range from 80°C to 100°C, and a penetration of 2 dmm.

Cake consistency is determined by the presence of solids (THFi) at a higher concentration than other streams and the presence of asphaltene compounds.

The clarified substance (11) thus obtained can preferably be recycled to a mixing section (F) or a hydroconversion section (A).

In one alternative separation method, the purge is mixed at a temperature greater than or equal to 100° C. with a mixture of hydrocarbons or breaker that has a total aromatic content ranging from 50% to 70% by weight and an initial temperature boiling point equal to or greater than the temperature at which mixing is carried out so as to obtain a suspension having a level greater than or equal to 10% (wt.) of compounds exhibiting a boiling point T _bp less than or equal to 350°C .

Thereafter, said suspension is subjected to a liquid-solid separation stage operating at a temperature greater than or equal to 100°C, which ensures the separation of the solid phase containing the residual organic component and the solid component - the cake and the liquid phase containing the solid residues .

Separation in a liquid-solid system is preferably accomplished by filtration or by using a centrifugal decanter that operates at temperature. The separation is followed by cooling the solid phase (cake) thus obtained below 60°C, including the upper limit, and maintaining it at a temperature less than or equal to 60°C.

The catalyst used during the hydroconversion reaction is formed "in situ" by the action of an oil-soluble precursor containing Mo, which can be fed into the hydroconversion reactor in the liquid phase directly with the charge or into the mixer together with the vacuum distillation residue. A commonly used precursor consists of a solution of a salt derived from Mo and 2-ethylhexanoic acid (2-ethylhexanoate) containing 15.5 wt% Mo.

The catalyst precursor is a liquid and reacts with the sulfide coming from the charge and the hydrogen present in the reactor to form MoS ₂ (solid molybdenite finely dispersed in the liquid phase) as lamellae.

Hydroconversion reactors can operate in a temperature range between 420°C and 440°C, at a pressure between 155 atm and 160 atm.

High pressure and high temperature separators operate under the same operating conditions as hydroconversion reactors, with the exception of head losses and heat losses along the line that connects the reactors to the separators.

Some examples of application of the present invention will now be described, which are for descriptive and non-limiting purposes only, and which represent preferred embodiments.

Examples

Description of polymer loading

The polymer charge used in the following examples, designated PLASMIX, is a mixture coming from the sorting of a separate collection of plastic packaging. These materials originate from industrial residues and/or waste materials.

In particular, the output product of the unselected fraction from the sorting process, consisting of a mixture of heterogeneous plastics, mostly polyolefins, was tested.

The mixture consists of flakes having dimensions D ₅₀ > 1 cm and has an apparent density of 200 kg/m ³ as measured according to ASTM D1895-96.

The described charge is insoluble in tetrahydrofuran.

In all examples, a mixture of polymers or plastics (polymer loading) contains 35 - 60% (wt.) polyethylene (PE), 15 - 40% (wt.) polypropylene (PP), 0 - 25% (wt.) polystyrene (PS) ), 0 – 15% (wt.) polyethylene terephthalate (PET), 0 – 5% (wt.) polyvinyl chloride (PVC), 0 – 15% (wt.) inorganic loads.

Mixtures of polymers or plastics are mixed with the vacuum residue, preferably at 5% (wt.) in relation to the vacuum residue.

Example 1: Mechanical pre-treatment due to comminution

For grinding, a Retsch Mill was used, having a rotor diameter of 130 mm and equipped with a 1.5 kW motor, under the following operating conditions:

- rpm = 1500

- grinding times = 10 minutes per 100 grams of product

- mesh “with a transmission limit” of 2.5 mm; a mesh with a transmission limit can have "holes" of different sizes depending on the resulting final granulometry. Fine-mesh meshes require longer times with the risk of overheating the material and “crushing” the entire mesh. 2.5 mm represents the compromise that applicants have identified for this type of initial production waste fines.

- grinding of the polymer load led to the production of a particle size distribution characterized by a D ₅₀ value < 1 mm.

Example 2: Mechanical pretreatment resulting from low temperature grinding

A Retsch Mill ZM200 equipped with an ultracentrifugal rotor with ring sieves was used for grinding, with a current consumption of 1300 W and a rotation speed ranging between 6000 and 18000 rpm. Working conditions:

- dosing of material through a Retsch DR100 sampler at a moving body speed of 5

- number of revolutions = 10000

- grinding time = 60 minutes based on 15 – 20 grams of product

- ring sieve 0.12 mm

- adding dry ice to the rotor for cooling

- collection tank of the aspiration cyclone

- grinding of the polymer load led to the production of a particle size distribution characterized by a D ₅₀ value < 0.2 mm.

Example 3 Chemical Pretreatment

100 ml of NaOH aqueous solution at 10% (w/w) is prepared at room temperature in a glass flask. The polymer loading is added to this solution at 5% (w/w). This means that out of 100 grams of a mixture of reagents, 5 grams are a polymer mixture, and 95 grams are a vacuum distillation residue. The system is initially stirred using a stirrer arm, and subsequently the resulting suspension is left at rest for 12 hours.

Example 4 Chemical Pretreatment

100 ml of aqueous solution of Ca(OH) ₂ at 10% (w/w) is prepared at room temperature in a glass flask. The polymer loading is added to this solution at 5% (w/w). The system is initially stirred using a stirrer arm, and subsequently the resulting suspension is left at rest for 12 hours.

Example 5 Chemical Pretreatment

100 ml of aqueous solution of H ₂ SO ₄ at 10% (w/w) is prepared at room temperature in a glass flask. The polymer loading is added to this solution at 5% (w/w). The system is initially stirred using a stirrer arm, and subsequently the resulting suspension is left at rest for 12 hours.

The pretreatments reported in Examples 2 – 3 – 4 were also repeated by adding 10% (w/w) and 20% (w/w) polymer loading to the various aqueous solutions.

Example 6 Chemical Pretreatment

100 ml of NaOH aqueous solution at 10% (w/w) is prepared at room temperature in a glass flask. The polymer loading is added to this solution at 5% (w/w). The system is initially stirred using a stirrer arm, and subsequently the resulting suspension is left at rest for 12 hours. The suspension is filtered to remove the aqueous phase; the solid phase remaining on the filter is dried in an oven at 120°C for one night.

The pre-treatment reported in Example 5 was also repeated using a solution of Ca(OH) ₂ and H ₂ SO ₄ .

Example 7 Chemical Pretreatment

45 grams of “styrene residue” are heated to 120°C, maintaining stirring for 2 hours, after which 15 grams of polymer loading are added. The mixture is kept at 120°C for 16 hours while stored in a nitrogen atmosphere.

Example 8 Chemical Pretreatment

11 tons of "styrene residue" are distilled, obtaining a fraction containing compounds exhibiting boiling points of more than 350°C. After this, this heavy fraction is heated to 200°C, mechanically mixed and 5% of the polymer load is added. Following this, the mixture is cooled and placed in an ultrasonic bath at 50°C for 2 hours.

Example 9 Chemical Pretreatment

11 tons of "styrene residue" are distilled to obtain a fraction containing compounds exhibiting boiling points of less than 350°C. After this, this heavy fraction is heated to 120°C, mechanically mixed and 5% of the polymer load is added. Following this, the mixture is cooled and placed in an ultrasonic bath at 50°C for 2 hours.

Example 10 Thermal Pretreatment

20 g of polymer loading is placed in an oven with nitrogen ventilation at 200°C for 16 hours.

Example 11 Thermal Pretreatment

20 g of polymer loading is placed in a nitrogen-ventilated oven at 250°C for 16 hours.

Example 12 Thermal Pretreatment

20 g of polymer loading is placed in a nitrogen-ventilated oven at 350°C for 16 hours.

Example 13 Thermal Pretreatment

2 kg of the polymer mixture is loaded into a twin-screw extruder with co-rotating worms, equipped with a die plate having cylindrical holes. All are extruded in operations at a constant temperature profile of 300° C., an upstream pressure above the die plate of 50 bar, a total flow rate of 10 kg/hour and a screw speed of 200 rpm. /min. The material is extruded into spaghetti form, cooled in a water bath, air dried and granulated using a cutting device.

Example 14 Thermal Pretreatment

2 kg of the polymer mixture is loaded into a twin-screw extruder with co-rotating worms, equipped with a die plate. All are extruded in operations at a constant temperature profile of 300° C., an upstream pressure above the die plate of 15 bar, a total flow rate of 10 kg/hour and a screw speed of 200 rpm. /min. The material melted using the extruder is added to the vacuum distillation residue.

Example 15: Combined Pretreatments

5 grams of pyrolyzed material are taken at 200° C. (Example 10) and mixed with 95 grams of acetone.

Example 16: Combined Pretreatments

5 grams of pyrolyzed material are taken at 250° C. (Example 11) and mixed with 95 grams of acetone.

Example 17: Combined Pretreatments

5 grams of heat-treated material was taken from extrusion (Example 13) and pretreated using a grinding process (Example 1).

Example 18. The claimed method

Preparing the mixture

Case 1: The polymer charge is processed in the same way as in example 1, that is, it is crushed. Take 5 grams of the pretreated polymer charge, available at room temperature, and add 95 grams of the vacuum distillation residue, preheated to 200°C. The mixture is kept warm at 200°C for 2 hours with mechanical stirring.

Case 2: The polymer charge is processed in the same way as in example 1, that is, it is crushed. Take 20 grams of the pre-treated polymer charge and add 80 grams of vacuum distillation residue preheated to 200°C. The mixture is kept warm at 200°C for 2 hours with mechanical stirring.

Case 3: The polymer charge is processed in the same way as in example 1, that is, it is crushed. Subsequently, 5 grams of the crushed polymer charge are removed and processed in the same manner as in Example 3, that is, chemically pretreated using a NaOH solution at 10% (w/w). The polymer charge thus pretreated is added to 95 grams of vacuum distillation residue preheated to 200°C. The mixture is heated to 200°C for 2 hours with mechanical stirring.

Case 4: The polymer charge is processed in the same way as in example 2, that is, it is crushed. Take 5 grams of the pretreated polymer charge, available at room temperature, and add 95 grams of the vacuum distillation residue, preheated to 200°C. The mixture is kept warm at 200°C for 2 hours with mechanical stirring.

Reaction

Several experiments were carried out using a 30cc microautoclave reactor.

Tests were carried out under the following operating conditions:

- 430°C;

- 160 bar hydrogen;

- 4 hours;

- 3000 ppm molybdenum

Mixtures tested on various occasions were characterized quantitatively by the precipitation of tetrahydrofuran insolubles (THF-i), n-pentane insolubles (Ins-C ₅ , a fraction generally considered to be the asphaltene fraction) and the resulting characteristics of the thus deasphalted fraction using the ASTM D2887 method. At the end of the test, the quantified and characterized reaction products are collected.

The gas phase is characterized using the ASTM D7833 Standard Refinery Gas Analysis method. In the liquid phase, THF insoluble matter (THF-i) and n-pentane insoluble material (Ins-C ₅ ) are quantified by precipitation and the deasphalted fraction is analyzed using method D2887. The tables show yields calculated according to the following formula:

m _{product(output)} : mass of outgoing product (g)

m _mixture(VX) : mass of loaded mixture (g)

The effluents considered are gaseous products containing from 1 to 4 carbon atoms (C1 - C4), gaseous products containing 5 carbon atoms, and liquid products exhibiting a boiling point between 65°C and 170°C (65°C). C (C ₅ ) – 170°C), considered as naphtha; liquid products exhibiting a boiling point in the range between 170°C and 350°C (170°C – 350°C); liquid products exhibiting a boiling point between 350°C and 500°C (350°C – 500°C); liquid products exhibiting a boiling point of more than 500°C (500+°C), products insoluble in n-pentane (Ins-C ₅ ) and products insoluble in tetrahydrofuran (THF-i).

Table 1

Base case EST Case 1 Case 2 Characteristics of the VX mixture. NTK – 350°C % (wt.) 1.8 2.8 1.4 350°C – 500°C % (wt.) 11.2 7.0 9.0 500°C+ % (wt.) 68.4 67.6 54.7 Ins-C ₅ % (wt.) 18.5 17.5 14.8 THFi % (wt.) 0.0 5.1 20.0 Output of ISH products. C ₁ – C ₄ wt./mass. _INNINGS 7.8% 8.3% 10.7% 65°C(C ₅ ) – 170°C wt./mass. _INNINGS 13.7% 17.0% 22.6% 170°C – 350°C wt./mass. _INNINGS 28.2% 29.3% 26.9% 350°C – 500°C wt./mass. _INNINGS 22.3% 21.4% 16.5% 500°C+ wt./mass. _INNINGS 16.7% 13.0% 6.9% Ins-C ₅ wt./mass. _INNINGS 8.4% 7.8% 11.0% THF-i wt./mass. _INNINGS 2.9% 3.3% 5.4% Conversion rate for PLASMIX product as estimated 90% 85%

The base case EST represents the reactivity of the vacuum distillation residue alone under hydroconversion conditions. The polymer charge is insoluble in tetrahydrofuran and constitutes the THF-i fraction present in the charge.

In case 1, the vacuum residue charge was treated and added to 5% of the mechanically pretreated polymer charge (see case 1 for mixture preparation), while in case 2 the amount of polymer charge added was increased from 5% to 20%. . Together with an increase in the processed load, an increase in fraction yields is observed at 65°C – 170°C.

THF-i also increases from the base case to case 1 to case 2. This fraction consists of the THF-i reaction products (see base case), the THF-i product originating from the organic fraction of the unconverted plastic material, accumulation in THF-i inorganic fraction (ash from polymer loading).

table 2

Case 1 Case 3 Characteristics of the VX mixture. NTK – 350°C % (wt.) 2.8 1.1 350°C – 500°C % (wt.) 7.0 5.8 500°C+ % (wt.) 67.6 65.1 Ins-C ₅ % (wt.) 17.5 22.7 THFi % (wt.) 5.1 5.4 Output of ISH products. C ₁ – C ₄ wt./mass. _INNINGS 8.3% 12.3% 65°C(C ₅ ) – 170°C wt./mass. _INNINGS 17.0% 16.0% 170°C – 350°C wt./mass. _INNINGS 29.3% 25.8% 350°C – 500°C wt./mass. _INNINGS 21.4% 14.2% 500°C+ wt./mass. _INNINGS 13.0% 6.9% Ins-C ₅ wt./mass. _INNINGS 7.8% 12.5% THFi wt./mass. _INNINGS 3.3% 12.3% Conversion rate for PLASMIX product as estimated 90%

Case 3 reports reactivity under the same operating conditions using a mixture of vacuum residue with 5% (w/w) Plasmix chemically pretreated with NaOH. As can be seen, although naphtha yield is maintained at 65°C - 170°C, the production of THF-i increases significantly, indicating how the presence of NaOH creates barriers to too high production of solid carbon compounds.

Table 3

Case 1 Case 4 Characteristics of the VX mixture. NTK – 350°C % (wt.) 2.8 2.4 350°C – 500°C % (wt.) 7.0 7.1 500°C+ % (wt.) 67.6 67.9 Ins-C ₅ % (wt.) 17.5 17.5 THFi % (wt.) 5.1 5.1 Output of ISH products. C ₁ – C ₄ wt./mass. _INNINGS 8.3% 9.8% 65°C(C ₅ ) – 170°C wt./mass. _INNINGS 17.0% 18.3% 170°C – 350°C wt./mass. _INNINGS 29.3% 29.5% 350°C – 500°C wt./mass. _INNINGS 21.4% 18.6% 500°C+ wt./mass. _INNINGS 13.0% 8.2% Ins-C ₅ wt./mass. _INNINGS 7.8% 11.6% THFi wt./mass. _INNINGS 3.3% 3.9%

Case 4 reports reactivity under the same operating conditions using a mixture of vacuum residue with 5% (w/w) milling pretreated Plasmix to produce Plasmix at D50 < 0.2 mm . As can be seen, the naphtha yield at 65 – 170°C is slightly increased compared to case 1, in which the Plasmix product was crushed more coarsely, as is the production of solids. Reducing the particle diameter of the polymer charge promotes both mixing and homogenization of the polymer charge with the vacuum distillation residue during the mixture preparation phase and, in addition, makes the material more accessible to reaction with respect to both naphtha and carbonaceous solids.

Example 19. Comparison

Preparing the mixture

Case 5: The polymer charge is processed in the same way as in example 1, that is, it is crushed. Take 5 grams of the pretreated polymer charge, available at room temperature, and add 95 grams of the vacuum distillation residue, preheated to 200°C. The mixture is kept warm at 200°C for 2 hours with mechanical stirring.

Case 6: The polymer charge is processed in the same way as in example 2, that is, it is crushed. Take 5 grams of the pretreated polymer charge, available at room temperature, and add 95 grams of the vacuum distillation residue, preheated to 200°C. The mixture is kept warm at 200°C for 2 hours with mechanical stirring.

Reaction

Several experiments were carried out using a 30cc microautoclave reactor.

Tests were carried out under the following operating conditions:

- 400°C;

- 1 hour;

- 20 bar nitrogen.

In accordance with the description of the invention in example 18, the mixtures subjected to tests in various cases, and the reaction products were characterized quantitatively as a result of the precipitation of the amount of insoluble substances in tetrahydrofuran (THFi), insoluble substances in n-pentane (Ins-C ₅ , the fraction usually considered as the asphaltene fraction) and resulting in the characterization of the thus deasphalted fraction using the ASTM D2887 method. The gas phase is characterized using the ASTM D7833 Standard Refinery Gas Analysis method.

In the base case reported in the table below and in cases 5 and 6, the reaction operating conditions were kept constant and represent the conditions of the heat treatment method.

Table 4

Thermal base case Case 5 Case 6 Characteristics of the VX mixture. NTK – 350°C % (wt.) 1.8 2.7 2.4 350°C – 500°C % (wt.) 11.2 7.0 7.1 500°C+ - Ins-C ₅ % (wt.) 86.9 85.3 85.4 THFi % (wt.) 0.0 5.0 5.1 Output of ISH products. C ₁ – C ₄ wt./mass. _INNINGS 4.5% 6.2% 3.6% 65°C(C ₅ ) – 170°C wt./mass. _INNINGS 3.0% 2.4% 0.9% 170°C – 350°C wt./mass. _INNINGS 9.9% 10.2% 10.2% 350°C – 500°C wt./mass. _INNINGS 17.3% 17.2% 16.9% 500°C+ - Ins-C ₅ wt./mass. _INNINGS 64.9% 61.4% 65.0% THFi wt./mass. _INNINGS 0.5% 2.6% 3.4%

The thermal base case represents the reactivity of the vacuum distillation residue alone under thermal transformation conditions. The polymer charge is insoluble in tetrahydrofuran and constitutes the THF-i fraction present in the charge.

In Case 1, the vacuum residue charge was treated and added to a 5% mechanically pretreated polymer charge (see Case 5 for mixture preparation), while in Case 6 a vacuum residue mixture was prepared and added to 5%. polymer load subjected to mechanical pre-treatment in such a way as to obtain particles with D50 < 0.2 mm. As can be observed from the comparison of the base case with cases in which a polymer charge is added, under the conditions of the thermal conversion process, the yield of naphtha is in any case less than in the base case. At the same time, there is evidence of a decrease in the conversion of the polymer load, since at the end of the test the amount of THF-i is much greater. As can be observed by considering THF-i at the end of the test as an unconverted polymer feed, the degree of conversion in case 5 is greater than in case 6. Based on the comparison of the two cases (5 and 6), an increase in gas yields can be observed ( C1 – C4) and naphtha in case 5, which indicates the conversion of the polymer charge into light products even in the thermal transformation method, but mainly with the formation of C1 – C4 gaseous compounds.

Claims (57)

1. A method for hydroconversion of a polymer mixture, which includes the following stages: • pre-treatment of the polymer mixture using methods selected from the group consisting of mechanical methods, chemical methods, thermal methods involving heating the polymer mixture at a temperature greater than or equal to 200°C in an inert environment, or combinations thereof, to obtain a pre-treated load , which is miscible or suspended in the hydrocarbon residue of vacuum distillation; • mixing said pre-treated charge with a hydrocarbon vacuum residue, optionally pre-heated, to obtain a mixture of reactants; • supplying the hydroconversion section with a mixture of reactants in suspension phase, an oil-soluble catalyst precursor containing molybdenum, said precursor being liquid, and a stream containing hydrogen, and conducting a hydroconversion reaction to produce a waste reaction product; • separating the reaction product effluent in at least one high pressure/high temperature separator into a vapor phase and a suspension phase; • then sending the separated vapor phase to the gas processing section with the function of separating the liquid fraction from the gas containing hydrogen and hydrocarbon gases containing from 1 to 4 carbon atoms; wherein said liquid fraction contains naphtha, atmospheric gas oil (AGO), vacuum gas oil (VGO); • then sending the suspension phase to the separation section, which has the function of separating the vacuum oil (VGO), heavy vacuum gas oil (HVGO), light vacuum gas oil (LVGO), atmospheric gas oil (AGO) fractions from the heavy organic product stream, which contain asphaltenes, unconverted feed, catalyst and solids formed during the hydroconversion reaction; • recycling a portion of said heavy organic products to the hydroconversion section or mixing them with the pre-treated feed prior to being sent to hydroconversion; wherein the remainder of said heavy organic products, which is not recycled to the hydroconversion section or mixed with the pre-treated feed before being supplied to the hydroconversion, forms a purge stream. 2. The method according to claim 1, where the mixture of polymers in the solid phase contains: - one or more polymers selected from: • ethylene polymers or copolymers and mixtures thereof; • propylene polymers or copolymers and their mixtures; • styrenic polymers or copolymers and their mixtures; • polymers or copolymers of vinyl chloride or copolymers of vinylidene dichloride and mixtures thereof; • polyesters; • polyamides; • polymers containing urethane bonds; • polymers made from cellulose; • their mixtures; - optionally additives from an organic or inorganic source. 3. The method of claim 2, wherein the ethylene polymers or copolymers are selected from high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), ultra low density polyethylene (ULDPE ), metallocene catalytic polyethylene (m-PE), ethylene vinyl acetate (EVA) polymers and mixtures thereof. 4. The method of claim 2, wherein the propylene polymers or copolymers are selected from polypropylene (PP) or ethylene-propylene-diene monomer (EPDM) rubbers and mixtures thereof. 5. The method of claim 2, wherein the styrenic polymers or copolymers are selected from polystyrene (PS), expanded polystyrene (EPS), high impact polystyrene (HIPS), acrylonitrile-styrene-butadiene (ABS) polymers, styrene-acrylonitrile (SAN) copolymers, styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butylene-styrene block copolymers (SEBS) and mixtures thereof. 6. The method according to claim 2, wherein the polymers or copolymers of vinyl chloride and vinylidene dichloride are selected from polyvinyl chloride (PVC), polyvinylidene chloride (PVDC) and copolymers thereof and mixtures thereof. 7. The method according to claim 2, where the polyesters are selected from polycarbonate (PC), polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polylactic acid (PLA), poly(L-lactic acid) (PLLA), poly(D-lactic acid) (PDLA), poly(D,L-lactic acid) (PDLLA), polyhydroxyalkanoate (PHA). 8. The method of claim 2, wherein the polyamides are selected from nylon 6 (PA6), nylon 66 (PA66), nylon 46 (PA46), nylon 12 (PA12) and mixtures thereof. 9. The method according to claim 2, wherein the polymers containing urethane bonds are selected from polyurethanes (PU) containing aliphatic or aromatic groups, or ester or ether or urea groups, and mixtures thereof. 10. The method of claim 2, wherein the polymers produced from cellulose are selected from cellulose nitrate, cellulose acetate, cellulose acetate butyrate, cellulose propionate, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, benzylcellulose and regenerated cellulose and mixtures thereof. 11. The method according to claim 1, where the hydroconversion reactor in the suspension phase is a bubble column. 12. The method according to claim 1, where the reaction takes place in one or more hydroconversion reactors located in parallel, and likewise the separation of the waste product occurs in one or more high pressure and high temperature separators located in parallel. 13. The method according to claim 1, where the gas processing section includes heat exchangers interspersed with a washing column, a high-pressure-medium-temperature separator, and a high-pressure-low-temperature separator. 14. The method according to claim 1, wherein said separation section includes a high temperature and low pressure separator, which acts as a storage tank; a pre-flash column, possibly a stripper column to separate the light components and finally a vacuum distillation column to recover the VGO fraction, LVGO fraction, HVGO fraction, wash oil and vacuum residue. 15. The method according to claim 1, wherein the mechanical pre-treatment is selected from grinding and low-temperature grinding. 16. The method according to claim 1, wherein the chemical pre-treatment is selected from: ○ obtaining a polymer mixture in an acidic or basic atmosphere at room temperature, preferably selected from an aqueous solution of H ₂ SO ₄ at 10% w/w, an aqueous solution of NaOH at 10% w/w, an aqueous solution of Ca(OH) ₂ at 10% w/w; ○ preparing a polymer mixture with hydrocarbon compounds at low or high molecular weight at room temperature; preferably selected from styrene residues and/or phenolic residues. 17. The method according to claim 1, where the thermal pre-treatment includes heating the polymer mixture at a temperature greater than or equal to 200°C in an inert atmosphere. 18. The method according to claim 1, where the pre-treatment is selected from the following methods: ▪ the polymer mixture is crushed, preferably using low-temperature grinding; then the crushed polymer mixture is added to acids or bases at room temperature, preferably selected from aqueous H ₂ SO ₄ at 10% w/w, aqueous NaOH at 10% w/w, aqueous Ca(OH) ₂ at 10% w/w, styrene residues and/or phenolic residues; or ▪ the polymer mixture is crushed, preferably using low-temperature grinding; then the crushed polymer mixture is heated to a temperature T greater than or equal to 200°C in an inert atmosphere; or ▪ the polymer mixture is heated to a temperature greater than or equal to 200°C in an inert atmosphere, then the heated polymer mixture is added to acids or bases at room temperature, preferably selected from an aqueous solution of H ₂ SO ₄ at 10% w/w, aqueous NaOH solution at 10% w/w, aqueous Ca(OH) ₂ solution at 10% w/w, styrene residues and/or phenolic residues. 19. The method according to claim 1, where the blown substance is subjected to treatment as follows: • heating to a temperature within the range of 185–220°C; • the hot blown substance is cooled as a result of a progressive and controlled decrease in temperature to a minimum temperature of 100°C without stirring the blown substance in such a way as to obtain a light phase or a clarified substance phase and a heavy phase or cake depending on the density. 20. The method according to claim 19, where the controlled progressive decrease in temperature can occur in various ways: • when using a properly sized and temperature controlled container, or • by mixing the heated purge with a cold stream, preferably a clarified phase, taking into account the proper heat balance of the process for flow calculations. 21. The method according to claim 19, wherein said heavy phase or cake is formed for a time which varies in the range from 15 minutes to 2 hours. 22. The method according to claim 19, wherein said heavy phase or cake is formed at a sedimentation rate ranging between 85 mm/h and 300 mm/h. 23. The method according to claim 19, wherein the light or clarified phase is mixed with the pre-treated feed or recycled to the hydroconversion section. 24. The method according to claim 1, where the blown substance is subjected to treatment as follows: • the purge is mixed at a temperature greater than or equal to 100°C with a mixture of hydrocarbons or diluent which has a total aromatic content between 50% and 70% by weight and an initial boiling point equal to or greater than a temperature at which mixing is carried out so as to obtain a suspension characterized by a content level greater than or equal to 10% by weight of compounds having a boiling point T _bp less than or equal to 350°C; • thereafter, said suspension is sent to a separation stage in a liquid-solid system, which operates at a temperature greater than or equal to 100°C, separating a solid phase containing the residual organic component and the solid component, and a liquid phase containing the solid residues; • cooling the solid phase thus obtained below 60°C, including the upper limit, and maintaining a temperature less than or equal to 60°C. 25. The method according to claim 24, where the separation in the liquid-solid system is carried out by filtration or by using a device for centrifugal decantation (centrifugation), which operates at a temperature. 26. The method according to claim 1, where the catalyst precursor is a solution of a salt obtained from Mo and 2-ethylhexanoic acid, containing 15.5 wt%. Mo. 27. The method according to claim 1, where the hydroconversion reactors and high-pressure and temperature separators operate in a temperature range between 420°C and 440°C, at a pressure between 155 atm and 160 atm.