Process for treating pyrolysis oil for use in steam cracking unit

Abstract

The present invention relates to a process for treating a feedstock comprising plastics and / or tyres and / or solid recycled fuel pyrolysis oils containing halogenated compounds, said process comprising: a) a hydrotreating step to obtain a partially hydrotreated effluent having a reduced halogenated compound content, b) a separation step to obtain a partially hydrotreated effluent having a reduced halogenated compound content, and c) a separation step to obtain a partially hydrotreated effluent having a reduced halogenated compound content. The present invention relates to a process for the steam cracking of a petroleum feedstock fed with a partially hydrotreated effluent from step a) and an aqueous solution to obtain a gaseous effluent, an aqueous effluent and a partially hydrotreated hydrocarbon effluent, c) a steam cracking step of a petroleum feedstock wherein at least a portion of the partially hydrotreated hydrocarbon effluent is introduced as a common feedstock, the mixture of the petroleum feedstock and the partially hydrotreated hydrocarbon effluent from step b) has a halogenated compound content of less than or equal to 3 ppm by weight without first undergoing a further hydrotreating step carried out at a higher temperature and / or pressure.

Description

Technical Field

[0001] The present invention relates to a process for treating pyrolysis oil from plastics and / or tires and / or solid recovered fuel (SRF) to obtain a partially hydrotreated pyrolysis oil which can be upgraded as a co-feedstock with petroleum feedstocks in a steam cracking unit. More specifically, the present invention relates to a process for treating pyrolysis oil in order to eliminate its halogenated compounds so that the oil can be easily upgraded in a steam cracking unit. Prior Art

[0002] Plastic waste is usually a mixture of several polymers, such as a mixture of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride or polystyrene. In addition, depending on the use, plastics may also contain other compounds in addition to polymers, such as plasticizers, pigments, dyes or polymerization catalyst residues. Plastic waste may also contain small amounts of biomass, which, for example, originates from household waste. On the one hand, the treatment of waste, in particular storage, mechanical treatment, sorting, pyrolysis, and on the other hand, the storage and transportation of pyrolysis oil, also cause corrosion.

[0003] As for tires, they mainly consist of rubber (due to their elastic properties (a mixture of crosslinked synthetic and natural rubber type elastomers, with additives such as silica, resins, sulfur, zinc oxide, carbon black, etc.)) and textile and metal fibers (due to their reinforcing properties).

[0004] Solid recovered fuel (SRF), also known as refuse-derived fuel (RDF), is solid non-hazardous waste prepared for energy upgrading, regardless of whether they originate from household and similar waste, from economic activity waste, or from demolition waste. SRF is usually a mixture of any combustible waste, such as old tires, food by-products (fats, animal feed, etc.), viscose and wood waste, light fractions produced from shredders (e.g., from second-hand vehicles, electrical and electronic equipment (WEEE)), household and commercial waste, residues recovered from various types of waste, including certain municipal waste, plastic waste, textiles or wood, etc. SRF usually contains plastic waste.

[0005] Plastics generated from collection and sorting channels or recycled tires or SRF can undergo a pyrolysis step to obtain, in particular, pyrolysis oil. These oils usually contain a large number of impurities, especially halogenated compounds, especially chlorine-based compounds, as well as dienes, olefins, metals, especially iron, silicon, or heteroelements such as sulfur, oxygen and nitrogen, and insoluble materials.

[0006] These plastics and / or tires and / or SRF pyrolysis oils are usually incinerated for power generation and / or used as fuel in industrial boilers or district heating boilers.

[0007] Another way to upgrade pyrolysis oil is to use this pyrolysis oil as a feedstock for a steam cracking unit to (re)produce olefins, which are the monomer components of certain polymers. However, plastic and / or tyre pyrolysis oil usually contains a high content of impurities that are incompatible with the steam cracking unit or units located downstream of the steam cracking unit, in particular polymerization processes and selective hydrogenation processes.

[0008] One way to remove these impurities contained in pyrolysis oil is to carry out hydrotreating in the presence of a catalyst. The steam cracking unit requires very high feedstock purity, especially low contents of chlorine, dienes, olefins, metals and sulfur. The specification of the chlorine content at the inlet of the steam cracking unit is usually at most 3 wt ppm, preferably at most 1 wt ppm.

[0009] Thus, the hydrotreating upstream of steam cracking is usually carried out in several steps and under very strict conditions (especially with respect to temperature and pressure) to achieve the required specifications. Such methods are described, for example, in WO2016 / 142808, WO2016 / 142809, WO2018 / 055555, WO2021 / 110395 or WO2021 / 165178.

[0010] The present invention provides a method for mild hydrotreating of plastic and / or tyre and / or SRF pyrolysis oil, which can significantly reduce the content of its halogenated compounds, especially the content of chlorine, to obtain pyrolysis oil with most of the halogenated compounds removed, which can then be fed as a co-feedstock with petroleum feedstock into a steam cracking unit.

[0011] Different from the hydrotreating methods described in the prior art, the method according to the present invention aims to carry out mild hydrotreating, especially hydrotreating at low pressure and moderate temperature. The mild operating conditions in hydrotreating, combined with a separation step including washing, can largely remove halogenated compounds.

[0012] The method according to the present invention mainly focuses on the removal of halogenated compounds to make the pyrolysis oil compatible as a feedstock in a steam cracking unit. The method according to the present invention does not necessarily aim to completely hydrotreat the oil. Other impurities (metals, silicon, nitrogen, etc.) contained in the pyrolysis oil are not necessarily completely removed during the method according to the present invention, although the operating conditions can remove at least a part of them. By diluting the oil with petroleum feedstock, the residual content of the impurities contained in the oil is made compatible with the specifications of the steam cracking unit.

[0013] The "mild" hydrotreating of the present invention is a hydrotreating carried out under carefully selected pressure, temperature, and space velocity conditions, which are generally milder compared to the conventional hydrotreating known in the prior art aimed at removing all impurities. The hydrotreating of the present invention can significantly remove most of the halogenated compounds.

[0014] Thus, the object of the present invention is to provide a method for treating plastic and / or pyrolysis oil of tires, which is inexpensive, easy to implement, and easily integrated into existing steam cracking units. The fact of using mild operating conditions can minimize hydrogen consumption, thereby minimizing the cost of such purification as well as the operating and investment costs, while removing as much chlorine content as possible.

[0015] In addition, the method according to the present invention can be carried out in a unit dedicated to pyrolysis oil, and thus can be carried out in a low-capacity unit to obtain pyrolysis oil with a partially hydrotreated halogenated compound content low enough to be directly fed into a steam cracking unit for co-processing. Summary of the Invention

[0017] More specifically, the present invention relates to a method for treating a "pyrolysis" feedstock comprising plastics and / or tires and / or pyrolysis oil of solid recovered fuels containing halogenated compounds, the method comprising:

[0018] a) A hydrotreating step carried out in a hydrotreating reaction section comprising at least one hydrotreating catalyst, the hydrotreating reaction section being fed at least with the pyrolysis feedstock and a gas stream containing hydrogen, the hydrotreating reaction section being used at an average temperature of 100°C to 220°C, a hydrogen partial pressure of 1.0 to 3.0 MPa absolute pressure, and a space velocity of 0.05 to 5 h -1 with a hydrogen coverage of 5 to 50 Nm 3 hydrogen / m 3 pyrolysis feedstock to obtain a partially hydrotreated effluent with reduced halogen content of hydrocarbon compounds,

[0019] b) A separation step, which is fed with the partially hydrotreated effluent from step a) and an aqueous solution to obtain at least a gaseous effluent, an aqueous effluent, and a partially hydrotreated hydrocarbon effluent,

[0020] c) A steam cracking step of a petroleum feedstock, in which at least a part of the partially hydrotreated hydrocarbon effluent from step b) is introduced as a co-feed, the partially hydrotreated hydrocarbon effluent from step b) being introduced without first undergoing another hydrotreating step at a temperature and / or pressure higher than the temperature and / or pressure of step a), and the mixture of the petroleum feedstock and the partially hydrotreated hydrocarbon effluent from step b) having a halogen content of less than or equal to 3 weight ppm.

[0021] According to one variant, the weight ratio of the flow rate of the partially hydrotreated hydrocarbon effluent from step b) introduced in step c) to the flow rate of the petroleum feedstock is less than 1.

[0022] According to one variant, the pyrolysis feedstock consists of plastic and / or tyre and / or pyrolysis oil of solid recovered fuel.

[0023] According to one variant, the content of halogenated compounds in the pyrolysis feedstock is 1 to 5000 weight ppm.

[0024] According to one variant, a stream containing a nitrogen-containing compound and / or a sulfur-containing compound is injected upstream of step a).

[0025] According to one variant, the hydrotreating catalyst in step a) comprises a support selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof, and a hydrodehydrogenation function containing at least one Group VIII element and at least one Group VIB element, or containing at least one Group VIII element.

[0026] According to one variant, the method includes at least one pretreatment step a0) of a pyrolysis feedstock containing plastic and / or tyre and / or pyrolysis oil of SRF, the pretreatment step being carried out upstream of step a) and including an adsorption step and / or a filtration step and / or a centrifugation step and / or a sedimentation step and / or an electrostatic separation step and / or a washing step with an aqueous solution and / or a stripping step.

[0027] According to one variant, the petroleum feedstock introduced into the steam cracking step c) is selected from naphtha, kerosene, gas oil or mixtures of these feedstocks.

[0028] According to one variant, the reaction section in step a) employs at least two reactors operating in a replaceable mode.

[0029] According to one variant, the steam cracking step c) is carried out in at least one pyrolysis furnace at a temperature of 700 to 900 °C and a pressure of 0.05 to 0.3 MPa relative pressure in the presence of steam.

[0030] According to one variant, in the steam cracking step c), the residence time of the hydrocarbon compounds is less than or equal to 1.0 second, and the amount of water introduced in the form of steam at the inlet of step c) is 0.3 to 3.0 kg water / kg hydrocarbon compound.

[0031] In the remainder of this text, unless otherwise specified, the term "pyrolysis oil" shall be understood to mean oil produced from the pyrolysis of plastic and / or tyre and / or SRF.

[0032] According to the present invention, unless otherwise stated, pressure is absolute pressure, also denoted as abs., and is given in MPa absolute pressure (or MPa abs.).

[0033] According to the present invention, the expressions “… to …” and “between … and …” are equivalent and mean that the limits of the interval are included within the described value range. If this is not the case and if the limits are not included within the described range, the present invention will give such a clarification.

[0034] For the purposes of the present invention, the various parameter ranges for a given step, such as a pressure range and a temperature range, can be used alone or in combination. For example, for the purposes of the present invention, a preferred range of pressure values can be combined with a more preferred range of temperature values.

[0035] Hereinafter, specific and / or preferred embodiments of the present invention may be described. They can be implemented alone or in combination, and there is no limitation on the combination when technically feasible.

[0036] Subsequently, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, edited by D.R. Lide, 81st edition, 2000 - 2001). For example, Group VIII (or Group VIIIB) according to the CAS classification corresponds to the metals in columns 8, 9, and 10 according to the new IUPAC classification.

[0037] The content of the metal is measured by X-ray fluorescence. DETAILED DESCRIPTION OF THE INVENTION

[0039] Pyrolysis Feedstock

[0040] According to the present invention, “plastic pyrolysis oil or tire pyrolysis oil or SRF pyrolysis oil” is an oil which is advantageously in liquid form at ambient temperature and is produced from the pyrolysis of plastics, preferably especially from the pyrolysis of plastic waste from collection and sorting channels, or from the pyrolysis of old tires, or from the pyrolysis of SRF. It particularly contains a mixture of hydrocarbon compounds, especially a mixture of alkanes, alkenes (mono-alkenes and / or di-alkenes), cycloalkanes, and aromatic hydrocarbons. At least 80% by weight of these hydrocarbon compounds preferably have a boiling point below 700 °C, preferably below 550 °C. In particular, depending on the source of the pyrolysis oil, the pyrolysis oil can contain up to 70% by weight of alkanes, up to 90% by weight of cycloalkanes, up to 90% of alkenes, and up to 90% by weight of aromatic hydrocarbons, it being understood that the sum of alkanes, cycloalkanes, alkenes, and aromatic hydrocarbons is equal to 100% by weight of the hydrocarbon compounds.

[0041] The pyrolysis oil may contain diolefins. The content of diolefins is usually determined indirectly as the maleic anhydride value (MAV). This method is based on the Diels - Alder addition reaction between conjugated diolefins and maleic anhydride. The method for determining MAV is described in C. L ópez Garc í a et al., Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil&Gas Science and Technology, Rev. IFP, Vol. 62 (2007), No. 1, pp. 57 - 68. The MAV is expressed in mg of maleic anhydride reacting with 1 g of the sample (mg / g). The MAV in the pyrolysis oil varies between 5 and 100 mg / g.

[0042] The density of the pyrolysis oil measured at 15 °C according to the ASTM D4052 method is usually between 0.75 g / cm 3 and 0.99 g / cm 3 , preferably between 0.75 g / cm 3 and 0.95 g / cm 3 .

[0043] The pyrolysis oil may also contain, and usually does contain, impurities such as metals, especially iron, silicon, or halogenated compounds, especially chlorinated compounds. These impurities may be present in the pyrolysis oil in high amounts, such as up to 500 weight ppm, or up to 700 weight ppm, or up to 1000 weight ppm, or even up to 5000 weight ppm of halogen elements (especially chlorine, but also bromine, fluorine, iodine or astatine) provided by the halogenated compounds, usually 1 to 1000 weight ppm, or 1 to 700 weight ppm, or 1 to 500 weight ppm of halogen elements. The pyrolysis oil may contain up to 500 weight ppm, or up to 700 weight ppm, or up to 1000 weight ppm, or even up to 5000 weight ppm of chlorine element provided by the chlorinated compounds, usually 1 to 1000 weight ppm, or 1 to 700 weight ppm, or 1 to 500 weight ppm of chlorine element.

[0044] The oil may contain up to 200 weight ppm, or up to 1500 weight ppm of metallic elements or metalloid elements, and typically 1 to 200 weight ppm, or 1 to 1500 weight ppm of metallic elements or metalloid elements. Alkali metals, alkaline earth metals, transition metals, post-transition metals, and metalloids can be grouped into the same category as contaminants with metallic properties, referred to as metals, or metallic elements or metalloid elements. In particular, the metal, or metallic element or metalloid element, includes silicon, iron, or both of these elements. The pyrolysis oil may especially contain up to 200 weight ppm, or up to 1000 weight ppm of silicon, and typically 1 to 200 weight ppm, or 1 to 1000 weight ppm, or 1 to 500 weight ppm of silicon. The pyrolysis oil may especially contain up to 50 weight ppm, or up to 100 weight ppm of iron, and typically 1 to 50 weight ppm, or 1 to 100 weight ppm of iron. The pyrolysis oil may also contain phosphorus, sodium, calcium, potassium, and magnesium.

[0045] The pyrolysis oil may also contain other impurities, such as heteroelements mainly provided by sulfur-containing compounds, oxygen-containing compounds, and / or nitrogen-containing compounds, with a content of heteroelements usually less than 40000 weight ppm, preferably less than 15500 weight ppm, and typically 1 to 40000 weight ppm, or 1 to 15500 weight ppm of heteroelements.

[0046] Sulfur-containing compounds are usually present in a content of less than 15000 weight ppm, preferably less than 10000 weight ppm, and typically 1 to 15000 weight ppm, or 1 to 10000 weight ppm of sulfur-containing compounds.

[0047] Oxygen-containing compounds are usually present in a content of less than 15000 weight ppm, preferably less than 10000 weight ppm, and typically 1 to 15000 weight ppm, or 1 to 10000 weight ppm of oxygen-containing compounds.

[0048] Nitrogen-containing compounds are usually present in a content of less than 10000 weight ppm, preferably less than 5000 weight ppm, and typically 1 to 10000 weight ppm, or 1 to 5000 weight ppm of nitrogen-containing compounds.

[0049] The content of sulfur-containing compounds, oxygen-containing compounds, and / or nitrogen-containing compounds usually depends on the source of the oil. Therefore, tire pyrolysis oil usually contains more heteroelements, especially sulfur-containing compounds, than plastic pyrolysis oil.

[0050] The pyrolysis oil may also contain other impurities, such as heavy metals, such as mercury, arsenic, zinc, and lead, such as up to 100 weight ppb, or up to 200 weight ppb of mercury or arsenic, and typically 1 to 200 weight ppb, or 1 to 100 weight ppb of heavy metals.

[0051] The pyrolysis feedstock according to the method of the present invention comprises at least one plastic and / or tyre and / or SRF pyrolysis oil. The feedstock may consist only of one or more pyrolysis oils. Preferably, relative to the total weight of the feedstock, the feedstock comprises at least 50% by weight, preferably 70% to 100% by weight, of pyrolysis oil, that is to say it comprises preferably 50% to 100% by weight, preferably 70% to 100% by weight, of plastic pyrolysis oil.

[0052] Particularly preferably, the pyrolysis feedstock according to the method of the present invention consists only of plastic pyrolysis oil and / or tyre pyrolysis oil and / or SRF pyrolysis oil.

[0053] In the case of a mixture of plastic pyrolysis oil, tyre pyrolysis oil and / or SRF pyrolysis oil, this mixture can be produced in any proportion.

[0054] According to another variant, in addition to one or more pyrolysis oils, the pyrolysis feedstock introduced in step a) of the method according to the present invention may also comprise a conventional petroleum feedstock or a feedstock produced by biomass conversion, which is then co-processed with the pyrolysis oil of the feedstock.

[0055] The conventional petroleum feedstock introduced in step a) may advantageously be a fraction or a mixture of fractions of the naphtha or gas oil type.

[0056] The feedstock produced by biomass conversion introduced in step a) may advantageously be selected from vegetable oils, oils from algae or algal oil, fish oil, waste cooking oil and fats of plant or animal origin, or mixtures of these feedstocks. The vegetable oil may advantageously be fully or partially crude or refined and is obtained from plants selected from rapeseed, sunflower, soybean, palm, olive, coconut, coconut kernel, castor oil plant, cotton plant, peanut, linseed and sea kale oil plants, and all oils obtained, for example, from genetically modified or hybrid sunflower or rapeseed, this list not being limiting. The animal fat is advantageously selected from blubber and fats consisting of residues from the food industry or fats obtained from the catering industry. Frying oils, various animal oils such as fish oil, tallow or lard may also be used. The feedstock produced by biomass conversion may also advantageously be selected from fatty acid methyl esters of plant and / or animal origin, or fatty acid methyl esters from waste edible vegetable oils.

[0057] The feedstock obtained from biomass conversion may also be selected from feedstocks derived from thermal or catalytic conversion processes of biomass, such as oils produced from biomass, in particular lignocellulosic biomass, by various liquefaction processes, such as hydrothermal liquefaction or pyrolysis. The term "biomass" refers to materials derived from recently living organisms, which includes plants, animals, and their by-products. The term "lignocellulosic biomass" refers to biomass derived from plants or their by-products. Lignocellulosic biomass consists of carbohydrate polymers (cellulose, hemicellulose) and aromatic polymers (lignin).

[0058] The feedstock produced from biomass conversion may also advantageously be selected from feedstocks produced from the paper industry.

[0059] Plastics and / or tires and / or SRF pyrolysis oil can be produced by thermal or catalytic pyrolysis treatment and can also be prepared by hydro-pyrolysis (pyrolysis in the presence of a catalyst and hydrogen).

[0060] Pretreatment (optional)

[0061] The pyrolysis feedstock comprising plastics and / or tires and / or SRF pyrolysis oil may advantageously be pretreated in at least one optional pretreatment step a0) before the hydrotreating step a) to obtain a pretreated feedstock for feeding into step a).

[0062] According to one variant, this optional pretreatment step a0) can reduce the amount of contaminants and solid particles that may be present in the feedstock containing pyrolysis oil, in particular the amount of iron and / or silicon and / or chlorine. This optional step a0) can significantly remove deposits formed due to the unstable nature of the pyrolysis oil and / or compatibility problems between two different feedstocks. Thus, particularly when the feedstock contains more than 10 weight ppm, especially more than 20 weight ppm, more particularly more than 50 weight ppm of metal elements and / or solid particles, and particularly when the feedstock contains more than 5 weight ppm of silicon, more particularly more than 10 weight ppm, in fact even more than 20 weight ppm of silicon, it is advantageous to perform the optional pretreatment step a0) on the feedstock containing pyrolysis oil. Similarly, particularly when the feedstock contains more than 10 weight ppm, especially more than 20 weight ppm, more particularly more than 50 weight ppm of chlorine, it is advantageous to perform the optional pretreatment step a0) on the feedstock containing pyrolysis oil.

[0063] The optional pretreatment step a0) can be carried out by any method known to those skilled in the art that can reduce the amount of contaminants. It may particularly include an adsorption step and / or a filtration step and / or a centrifugation step and / or a sedimentation step and / or an electrostatic separation step and / or a washing step with an aqueous solution and / or a stripping step.

[0064] The optional pretreatment step a0) is advantageously carried out at a temperature of 20 °C to 400 °C, preferably 40 °C to 350 °C and a pressure of 0.15 to 10.0 MPa absolute, preferably 0.2 to 7.0 MPa absolute.

[0065] According to a variant, the optional pretreatment step a0) is carried out in an adsorption section which operates in the presence of at least one adsorbent. The adsorbent may be selected from zeolites, activated carbon, clays, silica or alumina. Preferably, the adsorbent is alumina which has a specific surface area of greater than or equal to 100 m 2 / g, preferably greater than or equal to 200 m 2 / g. The specific surface area of the at least one adsorbent is advantageously less than or equal to 600 m g / g, in particular less than or equal to 400 m 2 / g. The specific surface area of the adsorbent is the surface area measured by the BET method, i.e. the specific surface area determined by the nitrogen adsorption method according to the standard ASTM D 3663-78 established by the Brunauer-Emmett-Teller method described in the journal The Journal of the American Chemical Society, 6Q, 309 (1938).

[0066] Advantageously, the adsorbent contains less than 1% by weight of metal elements and preferably contains no metal elements. The metal elements of the adsorbent are understood to mean the elements from Groups 6 to 10 of the Periodic Table (new IUPAC classification). The residence time of the feedstock in the adsorption section is generally from 1 to 180 minutes.

[0067] The adsorption section of the optional step a0) comprises at least one adsorption tower, preferably at least two adsorption towers, preferably two to four adsorption towers, which contain the adsorbent. When the adsorption section comprises two adsorption towers, one operating mode may be "swing" operation, where one tower is online, i.e. in operation, while the other tower is on standby. When the adsorbent in the online tower fails, the tower is isolated while the standby tower is brought online, i.e. into operation. Subsequently, the failed adsorbent can be regenerated in situ and / or replaced with fresh adsorbent so that once the other tower is isolated, the tower containing it can be put back online again.

[0068] Another operating mode is to operate at least two towers in series. When the adsorbent in the tower placed at the head fails, the first tower is isolated, and the failed adsorbent is regenerated in situ or replaced with fresh adsorbent. Subsequently, the tower is put back into the on-line state at the last position, and so on. This operation is called the permutable mode, or PRS, i.e., the Permutable Reactor System, or "lead and lag". The combination of at least two adsorption towers can overcome the possible and potentially rapid poisoning and / or clogging of the adsorbent due to the combined action of metal contaminants, diolefins, gums obtained from diolefins, and insoluble substances that may be present in the pyrolysis oil to be treated. This is because the presence of at least two adsorption towers advantageously facilitates the replacement and / or regeneration of the adsorbent without shutting down the pretreatment unit, in fact, even the process, thereby reducing the risk of clogging and thus being able to avoid the shutdown of the unit due to clogging, thereby controlling costs and limiting the consumption of the adsorbent.

[0069] According to another variant, the optional pretreatment step a0) is carried out in a washing section with an aqueous solution, such as water or an acidic or alkaline solution. The washing section may include items of equipment capable of bringing the feedstock into contact with the aqueous solution and separating multiple phases, so as to obtain, on the one hand, the pretreated feedstock and, on the other hand, the aqueous solution containing impurities. These items of equipment may include, for example, a stirred reactor, a decanter, a mixer-decanter, and / or a co-current or counter-current washing tower.

[0070] According to another variant, the optional pretreatment step a0) is carried out by filtration. The filtration step can remove the inorganic solids, sediments, and / or fine particles contained in the feedstock, especially metals, metal oxides, and metal chlorides. Filters with a pore size (e.g., diameter or equivalent diameter) less than 25 μm, preferably less than or equal to 10 μm, and even more preferably less than or greater than 5 μm are usually used. According to another variant, filters with a pore size less than 25 μm but greater than 5 μm can be used. A series of filters with different pore sizes can also be used, especially a series of filters with pore sizes gradually decreasing in the circulation direction of the feedstock. These filtration media are well-known for their industrial use. For example, cartridge filters or self-cleaning filters are suitable. The solid content can be measured, for example, by the heptane insolubles test, i.e., the ASTM D-3279 method. The content of insolubles in heptane must be reduced to less than 0.5 wt%, preferably less than 0.1 wt%.

[0071] According to a specific embodiment, the pretreatment step a0) carried out by filtration includes at least one filter with a pore size less than 10 μm, preferably greater than 5 μm, and subsequently an optional filtration system with a pore size less than 2 μm, preferably less than 1 μm.

[0072] According to another specific embodiment, the pre-treatment step a0) carried out by filtration comprises at least one filter with a pore size less than 10 μm, preferably greater than 5 μm, and a subsequent electrostatic precipitation system.

[0073] According to another specific embodiment, the pre-treatment step a0) carried out by filtration comprises at least one filter with a pore size less than 10 μm, preferably greater than 5 μm, and a subsequent system of one or more filters using a filter aid (such as sand or diatomaceous earth).

[0074] According to another variant, the optional pre-treatment step a0) is carried out by centrifugation. According to another variant, the pre-treatment step a0) comprises centrifugation and filtration.

[0075] According to another variant, the optional pre-treatment step a0) is carried out by sedimentation. According to another variant, the pre-treatment step a0) comprises sedimentation and filtration.

[0076] According to another variant, the optional pre-treatment step a0) is carried out by stripping to reduce the oxygen content in the feedstock. Gas extraction can remove the oxygen (O2) that may be dissolved in the feedstock, thereby reducing the likelihood of polymerization occurring in downstream steps due to the formation of free radicals. The method generally involves contacting the feedstock with an extraction gas (such as H2, N2 or a mixture thereof) so as to transfer at least a portion of the dissolved oxygen in the feedstock to the extraction gas, and then separating the extraction gas from the feedstock. The volume of the extraction gas relative to the volume of the feedstock (the two volumes measured under gas extraction conditions) is generally greater than 1, preferably at least 3. In a specific embodiment, the extraction gas may contain at least 60% (mole percentage) of H2. Because of the downstream hydrotreating, any dissolved H2 remaining in the feedstock after the gas extraction step is not a problem. Preferably, the gas extraction step is completed before any (pre)heating of the feedstock to minimize potential fouling.

[0077] The optional pre-treatment step a0) generally comprises one or more, preferably several, of the above-mentioned treatments. It may particularly comprise a series of washing steps and / or adsorption steps with an aqueous solution, followed by a stripping step, then a filtration step and / or a centrifugation step. All these steps are preferably carried out before any (pre)heating of the feedstock.

[0078] Thus, the optional pre-treatment step a0) can obtain a pre-treated feedstock, which is then fed to the mild hydrotreating step a).

[0079] Hydrotreating step a)

[0080] According to the present invention, the method comprises step a) carried out in a hydrotreating reaction section comprising at least one hydrotreating catalyst, said hydrotreating reaction section being fed at least with a pyrolysis feedstock and a gas stream comprising hydrogen, said hydrotreating reaction section being used at an average temperature of 100 °C to 220 °C, a hydrogen partial pressure of 1.0 to 3.0 MPa absolute pressure and a space velocity of 0.05 to 5 h -1 to obtain a partially hydrotreated effluent of hydrocarbon compounds with a reduced halogen content. 3 Hydrogen coverage is 5 to 50 Nm 3 Hydrogen / m

[0081] Step a) is carried out especially under mild hydrogen pressure and temperature conditions that can significantly remove halogens, especially chlorine, so that the pyrolysis oil is compatible as a co-feed in a steam cracking unit.

[0082] During the process according to the present invention, other impurities (metals, silicon, nitrogen, etc.) contained in the pyrolysis oil are not necessarily completely removed, although the operating conditions can remove at least a part of them. Therefore, step a) mainly involves the hydrogenation reaction of halogenated compounds and, to a lesser extent, also other hydrotreating reactions well known to those skilled in the art, especially hydrotreating reactions such as the hydrogenation of aromatics, hydrodesulfurization and hydrodenitrogenation, and the hydrogenation of olefins and diolefins.

[0083] The hydrotreating reaction section is advantageously used at an average hydrotreating temperature (or WABT as defined below) of 100 °C to 220 °C, preferably 120 °C to 200 °C, a hydrogen partial pressure of 1.0 to 3.0 MPa absolute pressure, preferably 1.0 to 2.4 MPa absolute pressure, more preferably 1.2 to 2.2 MPa absolute pressure, and a space velocity (HSV) of 0.1 to 5 h -1 preferably 0.1 to 2 h -1 preferably 0.1 to 1.0 h -1 The hydrogen coverage in step a) is advantageously 5 to 50 Nm 3 Hydrogen / m 3 Fresh feedstock, preferably 10 to 40 Nm 3 Hydrogen / m 3 Fresh feedstock, preferably 15 to 30 Nm 3 Of hydrogen / m 3 Fresh feedstock.

[0084] According to the present invention, the "average temperature" of the reaction section corresponds to the weighted average bed temperature (WABT) well known to those skilled in the art. The average temperature is advantageously determined according to the catalytic system used, the equipment items and their configuration. The average temperature (or WABT) is calculated as follows:

[0085] WABT = (T 入口 + T出口 ) / 2

[0086] where T 入口 : the temperature of the stream at the inlet of the reaction section, T 出口 : the temperature of the effluent at the outlet of the reaction section. Unless otherwise stated, the "average temperature" of the reaction section is given under the recycle start conditions.

[0087] The hourly space velocity (HSV) is defined herein as the ratio of the hourly volume flow rate of a feedstock containing pyrolysis oil that has been optionally pre-treated to the volume of one or more catalysts.

[0088] The hydrogen coverage is defined as the ratio of the volume flow rate of hydrogen gas obtained under standard temperature and pressure conditions to the volume flow rate of the "fresh" feedstock at 15 °C, i.e., to the volume flow rate of the feedstock to be treated that has been optionally pre-treated (excluding the recycle part) (expressed in standard m 3 (expressed as Nm 3 ) of H2 / m 3 feedstock).

[0089] The gas stream containing hydrogen fed to the hydrotreating reaction section may consist of a hydrogen supply and / or recycled hydrogen. Preferably, advantageously, an additional gas stream containing hydrogen is introduced at the inlet of each (especially those operating in series) reactor, and / or an additional gas stream containing hydrogen is introduced at the inlet of each catalyst bed starting from the second catalyst bed of the reaction section. These additional gas streams are also referred to as cooling streams. They can control the temperature in the reactors, where the reactions carried out are usually highly exothermic.

[0090] The gas stream containing hydrogen may be derived from a fossil source or a renewable source, such as derived from the gasification of plastic waste, or produced by electrolysis.

[0091] Advantageously, the gas stream containing hydrogen comes from a compressor in a refinery that supplies another hydrofining unit (such as a hydrocracking, hydrotreating or hydroconversion unit) that uses hydrogen. This has the advantage of eliminating the dedicated compressor for recycling the hydrogen from step b), thus saving investment costs.

[0092] Optionally, the reaction section of step a) may also be additionally fed by a portion of the partially hydrotreated hydrocarbon (recycle) effluent from step b) as described below.

[0093] Preferably, the method according to the invention comprises a hydrotreating step a) carried out in a hydrotreating reaction section using at least one fixed-bed reactor having n catalyst beds, where n is an integer greater than or equal to 1, preferably from 1 to 10, more preferably from 2 to 5, and each catalyst bed contains at least one hydrotreating catalyst.

[0094] The hydrotreating reaction section is fed at least with a pyrolysis feedstock optionally pretreated and a gas stream comprising hydrogen, advantageously at the first catalyst bed of the first reactor in operation. At least a portion of the pyrolysis feedstock and / or at least a portion of the hydrogen can also be injected between different catalyst beds.

[0095] The hydrotreating reaction section using at least one fixed bed reactor can be operated with the gas and liquid flowing downward or upward.

[0096] Advantageously, the reaction section of step a) comprises from 1 to 5 reactors, preferably from 2 to 5 reactors, and particularly preferably comprises two reactors. The advantage of a hydrotreating reaction section comprising several reactors lies in optimizing the treatment of the feedstock, while at the same time reducing the risk of clogging of one or more catalyst beds and thus avoiding the shutdown of the unit due to clogging.

[0097] According to this embodiment, the hydrotreating reaction section of step a) comprises two reactors operating in a replaceable mode, called PRS, i.e., a replaceable reactor system, or called "lead and lag". The combination of at least two reactors in PRS mode allows the reactors to be isolated without shutting down the process, discharging the spent catalyst, refilling the reactors with fresh catalyst and putting the reactors back into use. The PRS technique is described in particular in patent FR2681871.

[0098] According to another embodiment, the hydrotreating reaction section comprises a single fixed bed reactor containing n catalyst beds, where n is an integer greater than or equal to 1, preferably from 1 to 10, preferably from 2 to 5.

[0099] Advantageously, reactor internals, such as reactor internals of the filter plate type, can be used to prevent clogging of one or more reactors. Examples of filter plates are described in patent FR3051375.

[0100] Preferably, step a) can use at least one guard bed upstream of one or more hydrotreating catalysts, the guard bed containing adsorbents of the alumina, silica, silica-alumina, zeolite and / or activated carbon type, optionally containing Group VIB and / or Group VIII metals. A series of guard beds with different particle diameters can also be used, in particular a series of guard beds with diameters gradually decreasing in the direction of circulation of the feedstock (also called "graded").

[0101] Advantageously, the hydrotreating catalyst comprises a support, preferably an inorganic support, and a hydrodehydrogenation function.

[0102] According to one variant, the hydrodehydrogenation functionality particularly comprises at least one Group VIII element, preferably selected from nickel and cobalt, and at least one Group VIB element, preferably selected from molybdenum and tungsten. According to this variant, the total content of the Group VIB and Group VIII metal elements, expressed as oxides, is preferably from 1 wt% to 40 wt%, more preferably from 5 wt% to 30 wt% relative to the total weight of the catalyst. When the metal is cobalt or nickel, the metal content is expressed as CoO and NiO respectively. When the metal is molybdenum or tungsten, the metal content is expressed as MoO3 and WO3 respectively.

[0103] The weight ratio of one or more Group VIB metals to one or more Group VIII metals, expressed as metal oxides, is preferably from 1 to 20, more preferably from 2 to 10.

[0104] According to this variant, the reaction section of step a) comprises, for example, a hydrotreating catalyst comprising from 0.5 wt% to 12 wt% of nickel, preferably from 0.9 wt% to 10 wt% of nickel (expressed as nickel oxide NiO relative to the weight of the catalyst), and from 1 wt% to 30 wt% of molybdenum, preferably from 3 wt% to 20 wt% of molybdenum (expressed as molybdenum trioxide MoO3 relative to the weight of the catalyst) on a preferably inorganic support, preferably an alumina support.

[0105] According to another variant, the hydrodehydrogenation functionality comprises at least one Group VIII element, preferably nickel, and is preferably composed of the same. According to this variant, the content of nickel oxide is preferably from 1 wt% to 50 wt%, more preferably from 10 wt% to 30 wt% relative to the weight of the catalyst. Such catalysts are preferably used in their reduced form on a preferably inorganic support, preferably an alumina support.

[0106] The support of the hydrotreating catalyst is preferably selected from alumina, silica, silica-alumina, magnesia, clay and mixtures thereof. The support may comprise dopant compounds, in particular oxides selected from boron oxides, especially boron trioxide, zirconia, ceria, titania, phosphorus pentoxide and mixtures of these oxides. Preferably, the hydrotreating catalyst comprises an alumina support optionally doped with phosphorus and optionally doped with boron. When phosphorus pentoxide P2O5 is present, its concentration is less than 10 wt% relative to the weight of the alumina, and advantageously at least 0.001 wt% relative to the total weight of the alumina. When boron trioxide B2O3 is present, its concentration is less than 10 wt% relative to the weight of the alumina, and advantageously at least 0.001 wt% relative to the total weight of the alumina. The alumina used may be, for example, γ (gamma) or η (eta) alumina.

[0107] The hydrotreating catalyst is, for example, in the form of extrudates or beads.

[0108] Very preferably, in addition to one or more of the above hydrotreating catalysts, step a) may also use at least one hydrotreating catalyst used in step a), which contains less than 1% by weight of nickel expressed as nickel oxide NiO and at least 0.1% by weight of nickel, preferably 0.5% by weight of nickel, and less than 5% by weight of molybdenum expressed as molybdenum trioxide MoO3 and at least 0.1% by weight of molybdenum, preferably 0.5% by weight of molybdenum, relative to the weight of the catalyst. Such a non-high-loaded metal catalyst can preferably be placed upstream or downstream of one or more of the above hydrotreating catalysts, preferably upstream.

[0109] The preparation of the catalyst for hydrotreating step a) is known and generally includes steps of impregnating a Group VIII metal and a Group VIB metal (if present), and optionally phosphorus and / or boron, on a support, then drying, and then optionally calcining. The catalyst for step a) can also be a catalyst used in a reduced form, so a reduction step is involved in its preparation.

[0110] Before the steps of the method, the catalyst is usually sulfided to form active species. Depending on the content of sulfur-containing compounds in the initial feedstock to be treated, a stream containing a sulfiding agent can be injected upstream of an optional pretreatment step a0) or upstream of the hydrotreating step a), preferably upstream of the hydrotreating step a), to ensure that the amount of sulfur is sufficient to form the active species (sulfide form) of the catalyst. This activation or sulfiding step is carried out by methods well known to those skilled in the art and is advantageously carried out in a sulfur-reducing atmosphere in the presence of hydrogen and hydrogen sulfide. The sulfiding agent is preferably H2S gas, elemental sulfur, CS2, mercaptan, sulfide and / or polysulfide, a hydrocarbon fraction with a boiling point below 400 °C containing sulfur-containing compounds, or any other sulfur-containing compound used to activate a hydrocarbon feedstock to sulfide the catalyst. The sulfur-containing compound is advantageously selected from alkyl disulfides, such as dimethyl disulfide (DMDS), alkyl sulfides, such as dimethyl sulfide, mercaptans, such as n-butyl mercaptan (or 1-butyl mercaptan), and polysulfide compounds of the tert-nonyl polysulfide type. The catalyst can also be sulfided with the sulfur contained in the feedstock to be desulfurized. Preferably, the catalyst is sulfided in situ in the presence of a sulfiding agent and a hydrocarbon feedstock. Very preferably, the catalyst is sulfided in situ in the presence of a feedstock added with dimethyl disulfide. The sulfiding agent can be injected continuously.

[0111] The partially hydrotreated effluent obtained at the end of the hydrotreating step a) is sent, preferably directly, to the washing / separation step b).

[0112] Separation step b)

[0113] According to the present invention, the treatment method includes a separation step b), which is advantageously carried out in at least one washing / separation section fed at least with the effluent from the partial hydrotreatment of step a) and an aqueous solution, to obtain at least a gaseous effluent, an aqueous effluent and a partially hydrotreated hydrocarbon effluent.

[0114] The separation step b) can particularly remove halogens (chlorine) in the form of hydrogen halide (especially HCl), which is formed by the reaction of hydrogen ions with halogen ions released by the hydrogenation of halogenated compounds during step a) and is dissolved in the aqueous solution.

[0115] The separation step b) is advantageously carried out at a temperature of 20°C to 200°C, preferably 50°C to 180°C, more preferably 80°C to 150°C. Advantageously, the separation step b) is carried out at a pressure close to the pressure used in step a), preferably at a pressure of 1.0 to 2.0 MPa, so as to facilitate the recycling of hydrogen if necessary.

[0116] The separation step can be advantageously carried out by any method known to those skilled in the art. For example, a combination of one or more separators (tanks) and / or one or more stripping columns can be used, and a stripping gas, such as a hydrogen-rich gas stream, can optionally be fed to the separator or these separators (tanks) and / or columns. The washing / separation section of step c) can be at least partially formed from common or separate components of the washing and separation equipment.

[0117] Advantageously, the separation step b) includes injecting an aqueous solution, preferably water, into the effluent from the partial hydrotreatment of step a) upstream of the washing / separation section, so as to dissolve at least some, preferably all, of the hydrogen halide (especially HCl) and any salts present.

[0118] The aqueous solution can be water. It can also be an alkaline aqueous solution (for example, by adding NaOH). Using an alkaline solution can neutralize the hydrogen halide and any dissolved salts.

[0119] In an optional embodiment of the present invention, the separation step b) comprises injecting an aqueous solution into the partially hydrotreated effluent from step a), followed by a washing / separation section advantageously comprising a separation stage for obtaining at least one aqueous effluent carrying hydrogen halide (in particular HCl) and any dissolved salts present, the washed partially hydrotreated effluent, and the partially washed gaseous effluent. Then, the aqueous effluent and the washed partially hydrotreated effluent can be separated in a knockout drum to obtain the washed partially hydrotreated effluent and the aqueous effluent. The partially washed gaseous effluent can be introduced simultaneously into a washing tower in which the gaseous effluent is circulated countercurrently relative to an aqueous stream preferably having the same properties as the aqueous solution injected into the partially hydrotreated effluent, which can remove at least a part, preferably all, of the hydrochloric acid contained in the partially washed gaseous effluent, thereby obtaining the gaseous effluent preferably substantially comprising hydrogen and an acidic aqueous stream. The aqueous effluent resulting from the knockout drum can optionally be mixed with the acidic aqueous stream and can optionally be used as a mixture with the acidic aqueous stream for feeding into the water recirculation loop of separation step b), feeding together with the aqueous solution upstream of the washing / separation section and / or feeding together with the aqueous stream into the washing tower. The water recirculation loop can comprise a supply of water and / or a supply of an alkaline solution and / or a bleed for discharging impurities.

[0120] The hydrotreating step a) mainly relates to the hydrogenation reaction of halogenated compounds and, to a lesser extent, also to other hydrotreating reactions, such as hydrodenitrogenation, which produces NH3 by hydrogenation of nitrogen-containing compounds, and hydrodesulfurization, which produces H2S by hydrogenation of sulfur-containing compounds.

[0121] When NH3 is present in the partially hydrotreated effluent from step a), the separation step b) can also remove ammonium chloride salt by dissolving the ammonium chloride salt in an aqueous solution, which is formed by the reaction between chloride ions released particularly in the form of HCl by hydrogenation of halogenated compounds during step a) and ammonium ions produced in the form of NH3 by hydrogenation of nitrogen-containing compounds during step a).

[0122] When H2S is present in the partially hydrotreated effluent from step a), the separation step b) can also remove ammonium sulfide ((NH4)2S) salt by dissolving the ammonium sulfide salt in an aqueous solution, which is formed by the reaction between H2S produced by hydrodesulfurization of sulfur-containing compounds and NH3.

[0123] According to one embodiment, and depending on the content of chlorine-containing compounds in the initial or pretreated feedstock, a stream containing a nitrogen-containing compound, such as ammonia or an amine, for example monoethanolamine, diethanolamine, and / or mono- and diethanolamine, can be injected upstream of the hydrotreating step a) to ensure that a sufficient amount of ammonium ions combines with the chloride ions formed during the hydrotreating step in the form of ammonium chloride salt, thereby limiting the formation of hydrochloric acid and thus limiting the corrosion downstream of the separation section.

[0124] The gaseous effluent obtained at the end of step b) advantageously contains hydrogen, preferably at least 80% by volume, preferably at least 85% by volume of hydrogen. The gaseous effluent obtained at the end of step b) contains very little chlorine, usually with a chlorine content of less than 3 weight ppm, which enables it to be sent to a refining unit that requires hydrogen.

[0125] According to one embodiment, at least part of the gaseous effluent can be recycled to the hydrotreating step a), and the recycling system can include a purification section (for example, for adsorbing heavy metals such as mercury).

[0126] According to another preferred embodiment, at least part of the gaseous effluent can be recycled upstream of a hydrogen compressor that supplies a hydrorefining unit that uses hydrogen, such as a hydrocracking, hydrotreating, or hydroconversion unit in a refinery. This has the advantage of being able to eliminate a dedicated compressor for recycling the hydrogen from step b), thus saving investment costs.

[0127] For the partially hydrotreated hydrocarbon liquid effluent from step b), according to one variant, a part of the partially hydrotreated hydrocarbon effluent from step b) can be recycled upstream of step a). Recycling a part of the partially hydrotreated hydrocarbon effluent from step b) to step a) or upstream of step a) advantageously enables, on the one hand, diluting the impurities and, on the other hand, controlling the temperature in step a), where the reactions involved can be highly exothermic. Diluting the impurities can limit unwanted reactions, such as the polymerization of dienes (formation of gums) and / or the formation of coke.

[0128] Advantageously, the recycle amount of the partially hydrotreated hydrocarbon effluent from step b), i.e., the recycled portion of the obtained product, is adjusted such that the weight ratio of the recycle stream from step b) to the feedstock containing pyrolysis oil, i.e., the feedstock to be treated in the overall process, is less than or equal to 10, preferably less than or equal to 7, preferably greater than or equal to 0.001, preferably greater than or equal to 0.01, and preferably greater than or equal to 0.1. Preferably, the recycle amount of the partially hydrotreated hydrocarbon effluent from step b) is adjusted such that the weight ratio of the recycle stream to the feedstock containing pyrolysis oil is from 0.01 to 10, preferably from 0.1 to 7, and particularly preferably from 0.2 to 5. This recycle ratio can significantly control the temperature rise in step a). This is because when the recycle ratio is high, the dilution rate of the feedstock is high, and thus the temperature rise at the start of the reaction section in step a) can be controlled by the dilution effect. The injection of the partially hydrotreated hydrocarbon effluent from step b) can be carried out at the first catalyst bed of the reaction section in step a) or between different catalyst beds. When the hydrotreating reaction section in step a) comprises two reactors operating in a replaceable mode, at least a portion of the partially hydrotreated hydrocarbon effluent from step b) can be recycled between the two reactors.

[0129] According to another preferred embodiment, the partially hydrotreated hydrocarbon effluent from step b) is partially and preferably entirely sent directly to the inlet of the steam cracking unit as a co-feed with a petroleum feedstock. This has the advantage of not requiring a recycle compressor.

[0130] The partially hydrotreated hydrocarbon effluent from step b) obtained by treatment according to steps a) and b) of the process according to the invention has a composition compatible with being introduced as a co-feed into the steam cracking unit.

[0131] The partially hydrotreated hydrocarbon effluent from step b) is in particular an effluent with a reduced content of halogenated compounds, in particular a reduced chlorine content.

[0132] Preferably, at least 50%, more preferably at least 75%, of the halogenated compounds in the initial feedstock are removed during steps a) and b).

[0133] During steps a) and b) of the process according to the invention, other impurities (metals, silicon, nitrogen, etc.) contained in the pyrolysis oil are not necessarily completely removed, although the operating conditions can remove at least a part thereof. In fact, the pyrolysis oil (which is a partially hydrotreated hydrocarbon effluent) does not need to be completely hydrotreated in order to be able to introduce it as a co-feed into the steam cracking unit. In particular, it does not need to undergo another hydrotreating step at a temperature and / or pressure higher than the temperature and / or pressure of step a) before introducing it into the steam cracking unit. By diluting the oil with the petroleum feedstock injected in step c), the residual content of the impurities contained in the oil is made compatible with the specifications of the steam cracking unit.

[0134] Preferably, at least 50%, more preferably at least 75% of the metal elements of the initial feedstock are removed during steps a) and b).

[0135] Generally, at most 50%, more preferably at most 25% of the sulfur-containing compounds of the initial feedstock are removed during steps a) and b).

[0136] Preferably, at least 25%, more preferably at least 50% of the oxygen-containing compounds of the initial feedstock are removed during steps a) and b).

[0137] Generally, at most 30%, more preferably at most 15% of the nitrogen-containing compounds of the initial feedstock are removed during steps a) and b).

[0138] The content of heavy metals, such as mercury, arsenic, zinc and lead, remains substantially unchanged.

[0139] The content is given as a relative concentration by weight, weight percentage (%), parts per million by weight (ppm) or parts per billion by weight (ppb) relative to the total weight of the stream considered.

[0140] Steam cracking step c)

[0141] According to the invention, the process comprises a steam cracking step c) of a petroleum feedstock, in which at least a part of the partially hydrotreated hydrocarbon effluent from step b) is introduced as a co-feed, the partially hydrotreated hydrocarbon effluent from step b) being introduced without first undergoing another hydrotreating step at a temperature and / or pressure higher than the temperature and / or pressure of step a), the mixture of the petroleum feedstock and the partially hydrotreated hydrocarbon effluent from step b) having a halogen content of less than or equal to 3 weight ppm.

[0142] Since the hydrotreating step a) can release halogenated compounds (such as chlorine), especially hydrogen halides of the HCl type, mainly in gaseous form, followed by a washing / separation step b) where the hydrogen halide can be dissolved and removed, the partially hydrotreated hydrocarbon effluent from step b) has a sufficiently reduced halogenated compound content such that it can be injected as a co-feed into a steam cracking unit for petroleum feedstocks.

[0143] The partially hydrotreated hydrocarbon effluent from step b) is introduced into the unit for steam cracking of the petroleum feedstock in such an amount that the chlorine content in the mixture of the petroleum feedstock and the partially hydrotreated hydrocarbon effluent from step b) is less than or equal to 3 weight ppm, preferably less than or equal to 1 weight ppm.

[0144] Generally, in the process according to the invention, the weight ratio of the flow rate of the partially hydrotreated hydrocarbon effluent (pyrolysis oil) from step b) to the flow rate of the petroleum feedstock introduced into the unit of step c) is usually less than 1, preferably from 0.01 to 0.9, more preferably from 0.02 to 0.5.

[0145] When the content of halogenated compounds in the partially hydrotreated hydrocarbon effluent from step b) is greater than 3 weight ppm or even 1 weight ppm, a chlorine content of 3 ppm or even 1 ppm can be achieved by dilution with the petroleum feedstock at the unit inlet.

[0146] The petroleum feedstock used in the steam cracking unit is preferably selected from naphtha, kerosene, gas oil or mixtures of these feedstocks.

[0147] The steam cracking step c) is advantageously carried out in at least one pyrolysis furnace, at a temperature of 700 to 900 °C, preferably 750 to 850 °C and a pressure of 0.05 to 0.3 MPa relative pressure, in the presence of steam. The residence time of the hydrocarbon compounds is generally less than or equal to 1.0 second (denoted as s), preferably from 0.1 to 0.5 second. Advantageously, steam is introduced upstream of the steam cracking step c) and after separation (or fractionation). At the inlet of step c), the amount of water introduced in the form of steam is advantageously from 0.3 to 3.0 kg of water / kg of hydrocarbon compound. The steam cracking step c) can be carried out in a plurality of pyrolysis furnaces in parallel to adapt the operating conditions to the various streams fed to step c) and to manage the pipe decoking time. The furnace comprises one or more pipes arranged in parallel. The furnace can also represent a set of furnaces operating in parallel. For example, the furnace can be dedicated to cracking middle distillate fractions.

[0148] Effluents from various steam crackers are typically recombined before separation to form the effluent. It should be understood that the steam cracking step c) includes a steam cracker and sub-steps related to steam cracking well-known to those skilled in the art. These sub-steps may particularly include heat exchangers, towers, and catalytic reactors, as well as recycle to the furnace. The tower can generally fractionate the effluent to at least recover a light fraction containing hydrogen and compounds having 2 to 5 carbon atoms, a fraction containing pyrolysis gasoline, and optionally a heavier fraction. The tower can separate the various components of the fractionated light fraction to at least recover an ethylene-rich fraction (C2 fraction), a propylene-rich fraction (C3 fraction), and optionally a butene-rich fraction (C4 fraction). The catalytic reactor can particularly carry out the hydrogenation of the C2, C3, and in fact even C4 fractions and pyrolysis gasoline. Saturated compounds, particularly saturated compounds having 2 to 4 carbon atoms, are advantageously recycled to the steam cracker to increase the total yield of olefins.

[0149] The steam cracking step c) can obtain at least one effluent containing a satisfactory content of olefins having 2, 3, and / or 4 carbon atoms (i.e., C2 olefins, C3 olefins, and / or C4 olefins), particularly a total olefin content of 2, 3, and 4 carbon atoms greater than or equal to 30% by weight relative to the weight of the considered steam cracking effluent. The C2 olefins, C3 olefins, and C4 olefins can then be advantageously used as polyolefin monomers.

[0150] Analysis methods used

[0151] Analysis methods and / or standards for determining the characteristics of various streams, particularly the characteristics of the feedstock to be treated and the effluent, are known to those skilled in the art. They are particularly listed as information in Table 1 below. Other methods considered equivalent can also be used, particularly equivalent IP, EN, or ISO methods:

[0152] Table 1

[0153]

[0154] (1) The MAV method is described in the article: C. L ópez Garc í a et al., Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams, Oil & Gas Science and Technology - Rev. IFP, Vol. 62 (2007), No. 1, pp. 57 - 68 Description of the drawings

[0155] Regarding Figure 1The information on the elements mentioned can better understand the present invention, and the present invention is not limited to Figure 1 the specific embodiments shown in

[0156] Figure 1 A schematic diagram showing a general embodiment of the method of the present invention includes:

[0157] - Step a), hydrotreating the pyrolysis oil 1 in the presence of a hydrogen-rich gas 2 and an amine optionally provided by stream 3 and a sulfiding agent optionally provided by stream 4;

[0158] - Separation / washing step b), which is fed by a partially hydrotreated effluent 5 from the hydrotreating step a) and carried out in the presence of an aqueous solution 6 to obtain at least a gaseous effluent 7, an aqueous effluent 8 and a partially hydrotreated hydrocarbon effluent 9, and a part 9a of which can be recycled to step a);

[0159] - Steam cracking step c) of a petroleum feedstock 10, in which at least a part, preferably all, of the partially hydrotreated hydrocarbon effluent 9 from step b) is introduced as a co-feed, and the partially hydrotreated hydrocarbon effluent 9 from step b) is introduced without first undergoing another hydrotreating step at a higher temperature and / or pressure.

[0160] Only the main steps and main streams are shown in the figure for better understanding of the present invention. It can be clearly understood that all the equipment items (tanks, pumps, exchangers, furnaces, towers, etc.) required for the operation are present even if not shown. It should also be understood that, as described above, the hydrogen-rich gas stream (supply stream or recycle stream) can be injected at the inlet of each reactor or each catalyst bed or between two reactors or two catalyst beds. Examples

[0161] The pyrolysis feedstock treated in the method is a plastic pyrolysis oil having the characteristics shown in Table 2 (i.e., containing 100% by weight of the plastic pyrolysis oil).

[0162] Table 2: Characteristics of the pyrolysis feedstock

[0163]

[0164]

[0165] Under the different operating conditions shown in Table 3, the pyrolysis feedstock is subjected to the hydrotreating step a) in a fixed-bed reactor in the presence of hydrogen and a NiMo hydrotreating catalyst supported on alumina.

[0166] Table 3: Conditions for the hydrotreating step a)

[0167]

[0168] At the end of the hydrogenation step a), the conversion rates of chlorine, diolefins and olefins (= (initial concentration - final concentration) / initial concentration) are shown in Table 4.

[0169] Table 4: Conversion rates of each entity during the hydrotreating step a)

[0170]

[0171] A separation step b) is carried out on the effluent from the hydrotreating step a): a water stream is injected into the effluent from the hydrotreating step a); then the mixture is treated in an acid gas scrubber and a separation tank.

[0172] The yields of the various fractions obtained after separation are shown in Table 5 (the yield corresponds to the ratio of the weight of the various products obtained to the weight of the upstream feedstock in step a), expressed as a percentage, expressed as % w / w).

[0173] Table 5: Yields of the various products obtained after separation

[0174] <![CDATA[Gas fraction (NH3 + H2S + H2O + C1 - C4)]]> % w / w 2.42 Liquid fraction % w / w 99.31

[0175] The characteristics of the liquid fraction obtained after the separation step b) are shown in Table 6:

[0176] Table 6: Characteristics of the liquid fraction

[0177]

[0178]

[0179] Then the effluent from step b) is mixed with a petroleum feedstock (naphtha) having a chlorine content of 0 weight ppm for steam cracking in a weight ratio of 10% oil / 90% petroleum feedstock. A mixture having a chlorine content of less than 3 ppm is obtained (for all examples), which is introduced into a fluidized bed catalytic steam cracking unit.

[0180] According to Example 2 and Example 3, less energy (temperature of step a)) and less hydrogen (H2 consumption) are used.

[0181] Example 3 carried out under very mild temperature and pressure conditions shows that oil with sufficient chlorine removal can be obtained while using a pressure lower than that of Example 2 (and thus less energy).

Claims

1. A method for treating a pyrolysis feedstock, the pyrolysis feedstock comprising plastics and / or tires and / or solid recovered fuel pyrolysis oil containing halogenated compounds, the method comprising: a) A hydrotreating step carried out in a hydrotreating reaction section containing at least one hydrotreating catalyst, the hydrotreating reaction section being fed at least with a pyrolysis feedstock and a gas stream containing hydrogen, the hydrotreating reaction section being used at an average temperature of 100 °C to 220 °C, a hydrogen partial pressure of 1.0 to 3.0 MPa absolute pressure, and a space velocity of 0.05 to 5 h -1 and a hydrogen coverage of 5 to 50 Nm 3 of hydrogen / m 3 of the pyrolysis feedstock to obtain a partially hydrotreated effluent of hydrocarbon compounds with a reduced halogen content b) A separation step in which a partially hydrotreated effluent and an aqueous solution from step a) are fed to obtain at least a gaseous effluent, an aqueous effluent, and a partially hydrotreated hydrocarbon effluent. c) A steam cracking step of a petroleum feedstock, in which at least a part of the partially hydrotreated hydrocarbon effluent from step b) is introduced as a co-feed, the partially hydrotreated hydrocarbon effluent from step b) being introduced without first undergoing another hydrotreating step at a temperature and / or pressure higher than the temperature and / or pressure of step a), and the mixture of the petroleum feedstock and the partially hydrotreated hydrocarbon effluent from step b) having a halogen content of less than or equal to 3 weight ppm.

2. The method according to claim 1, wherein the weight ratio of the flow rate of the partially hydrotreated hydrocarbon effluent from step b) introduced into step c) to the flow rate of the petroleum feedstock is less than 1.

3. The method according to claim 1 or 2, wherein the pyrolysis feedstock consists of plastics and / or tires and / or solid recovered fuel pyrolysis oil.

4. The method according to any one of the preceding claims, wherein the content of halogenated compounds in the pyrolysis feedstock is 1 to 5000 weight ppm.

5. The method according to any one of the preceding claims, wherein a stream containing a nitrogen-containing compound and / or a sulfur-containing compound is injected upstream of step a).

6. The method according to any one of the preceding claims, wherein the hydrotreating catalyst in step a) comprises a support selected from alumina, silica, silica-alumina, magnesia, clay, and mixtures thereof, and a hydrodehydrogenation function containing at least one Group VIII element and at least one Group VIB element, or containing at least one Group VIII element.

7. The method according to any one of the preceding claims, which includes at least one pretreatment step a0) of a feedstock containing plastics and / or tires and / or SRF pyrolysis oil, the pretreatment step being carried out upstream of step a) and including an adsorption step and / or a filtration step and / or a centrifugation step and / or a sedimentation step and / or an electrostatic separation step and / or a washing step with an aqueous solution and / or a stripping step.

8. The method according to any one of the preceding claims, wherein the petroleum feedstock introduced into the steam cracking step c) is selected from naphtha, kerosene, gas oil, or a mixture of these feedstocks.

9. The method according to any one of the preceding claims, wherein the reaction section of step a) uses at least two reactors operating in a replaceable mode.

10. The method according to any one of the preceding claims, wherein the steam cracking step c) is carried out in at least one pyrolysis furnace at a temperature of 700 to 900 °C and a pressure of 0.05 to 0.3 MPa relative pressure in the presence of steam.

11. A method according to one of the preceding claims, wherein in the steam cracking step c), the residence time of the hydrocarbon compound is less than or equal to 1.0 second, and the amount of water introduced in the form of steam at the inlet of step c) is 0.3 to 3.0 kg of water / kg of hydrocarbon compound.

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