Method for processing a feedstock from a renewable source, for the production of bio-based olefins

Abstract

The present invention relates to a method for processing a feedstock from a renewable source comprising triglycerides and / or fatty acids and / or esters, said method comprising the steps of: a) a step of hydrotreating said feedstock in the presence of hydrogen and at least one hydrotreatment catalyst in a fixed bed, said step being performed at a temperature of between 280 and 410°C, a relative pressure of between 2.0 and 13.0 MPa, and a liquid hourly space velocity of between 0.3 and 5 h-1, and obtaining a hydrotreated effluent; b) a step of hydrocracking the hydrotreated effluent obtained in step a) in the presence of hydrogen and at least one hydrocracking catalyst in a fixed bed, at a temperature of between 280 and 410°C, said step being performed at a pressure of between 2.0 MPa and 13.0 MPa and at a liquid hourly space velocity of between 0.5 and 10 h-1, and obtaining a hydrocracked effluent; c) a step of separating the hydrocracked effluent obtained in step b), and obtaining at least one gaseous effluent comprising hydrogen and a liquid hydrocarbon effluent; d) a step of stripping the liquid hydrocarbon effluent obtained in step c), and obtaining at least one off-gas cut and a stripped liquid effluent; e) a step of fractionating the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut; f) a step of steam cracking at least some, preferably all, of the naphtha cut obtained in step e) and obtaining at least one bio-based gaseous effluent comprising ethylene and propylene.

Description

[0001] Process for treating a feedstock from a renewable source for the production of bio-sourced olefins

[0002] TECHNICAL FIELD

[0003] The present invention relates to a process for treating a feedstock from a renewable source comprising triglycerides and / or fatty acids and / or esters for the selective production of naphtha, capable of producing olefins such as ethylene, propylene and bio-sourced polymers for the chemical industry.

[0004] PRIOR TECHNIQUE

[0005] Many hydrotreatment processes for feedstocks from renewable sources including triglycerides and / or fatty acids and / or esters have been developed to increase the share of renewable fuel in fossil fuels.

[0006] FR2917424 discloses, for example, a method for treating a feedstock from a renewable source comprising a hydrotreatment step in the presence of at least one fixed-bed catalyst, said catalyst comprising a hydro-dehydrogenating function and an amorphous support, followed by separation from the hydrotreated effluent from step a) of hydrogen, gases and at least one liquid hydrocarbon effluent consisting of at least 50% linear n-paraffins, and steam cracking of at least part of the liquid hydrocarbon effluent from separation step b).

[0007] FR3104603 discloses a process for the isomerization of paraffinic feedstocks, preferably derived from hydrotreated vegetable and / or animal oils or from low-temperature Fischer-Trospch synthesis, said process using a bifunctional catalyst comprising at least one metal from group VIII of the periodic table of elements, at least one matrix and at least one IZM-2 zeolite. This process makes it possible to improve the selectivity towards the production of middle distillate bases by limiting the production of light cracked products which cannot be incorporated into a diesel and / or kerosene pool.

[0008] However, it is also necessary to increase the production of bio-sourced olefins obtained by steam cracking of feedstocks from renewable sources comprising triglycerides and / or fatty acids and / or esters in order to increase the quantity of sustainable polymers produced to replace polymers of fossil origin. US2014350314 discloses in particular a process comprising a step of hydrotreating a renewable feedstock to produce a hydrocarbon effluent, a step of hydrocracking said hydrocarbon effluent to produce a distribution of cracked hydrocarbons, a step of separating a heavy cut and a bio-sourced naphtha cut, and a step of obtaining a middle distillate fraction from the heavy fraction.

[0009] Surprisingly, the applicant has developed an improved process for producing a naphtha cut from a bio-sourced feedstock that can be co-processed in most liquid steam crackers with a minimal number of steps.

[0010] SUMMARY OF THE INVENTION

[0011] The present invention relates to a process for treating a feedstock from a renewable source comprising triglycerides and / or fatty acids and / or esters, said process comprising the steps of: a) a step of hydrotreating said feedstock in the presence of hydrogen and at least one hydrotreatment catalyst in a fixed bed, carried out at a temperature of between 280 and 410°C, and at a relative pressure of between 2.0 and 13.0 MPa, and at an hourly volumetric rate of between 0.3 and 5h~ 1, and obtaining a hydrotreated effluent; b) a step of hydrocracking the hydrotreated effluent obtained in step a) in the presence of hydrogen and at least one fixed-bed hydrocracking catalyst, at a temperature between 280 and 410°C, operated at a pressure between 2.0 MPa and 13.0 MPa, and at an hourly volumetric rate between 0.5 and 10 h 1, and obtaining a hydrocracked effluent; c) a step of separating the hydrocracked effluent obtained in step b), and obtaining at least one gaseous effluent comprising hydrogen and a hydrocarbon liquid effluent; d) a step of stripping the hydrocarbon liquid effluent obtained in step c), and obtaining at least one off-gas cut and one stripped liquid effluent; e) a step of fractionating the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut; f) a step of steam cracking at least a portion, preferably all of the naphtha cut obtained in step e) and obtaining at least one biosourced gaseous effluent comprising ethylene and propylene. The process according to the invention makes it possible to produce ethylene, propylene and, after polymerization, biosourced polymers.

[0012] Advantageously, this scheme makes it possible to produce only recoverable cuts in a liquid steam cracker accepting naphtha cuts and possibly LPG cuts.

[0013] Thus, the process according to the invention preferably does not produce a distillate cut.

[0014] Furthermore, the process is efficient because it does not require extensive separation of the hydrotreated effluent between step a) and step b), only a tank generating a hydrotreated liquid effluent which is partly sent to step a) to control the exotherm of the reaction.

[0015] In one embodiment, hydrotreatment step a) is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 Nm3 / Sm3.

[0016] In one embodiment, the at least one hydrotreatment catalyst comprises a support and an active phase, said active phase comprising at least one metal from group 6 and optionally one or more metals from group 9 or 10, preferably the active phase contains molybdenum only (Mo), or nickel and molybdenum (NiMo), or cobalt and molybdenum (CoMo), or nickel, cobalt and molybdenum (CoNiMo).

[0017] In one embodiment, the hydrotreatment step a) is followed by a separation step at high temperature between 150 and 410°C, and at high pressure between 2.0 and 13.0 MPa, of the hydrotreated effluent, and obtaining at least one gaseous effluent and one liquid effluent.

[0018] In one embodiment, a portion of the liquid effluent obtained in the high-temperature separation step is recycled to the hydrotreatment step a).

[0019] In one embodiment, hydrocracking step b) is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 Nm3 / Sm3.

[0020] In one embodiment, hydrocracking step b) is carried out at a minimum hydrogen partial pressure of 2.5 MPa.

[0021] In one embodiment, the at least one hydrocracking catalyst comprises a hydrogenating function and an acid function provided by supports with large surface areas having a surface acidity, such as halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and Y, Beta and ZSM-5 zeolites. In one embodiment, in step b) the conversion per pass into hydrocarbon compounds is between 20 and 100% by weight.

[0022] In one embodiment, separation step c) is followed by a step of purification and / or washing of the gaseous effluent comprising hydrogen obtained in step c) to remove contaminants, in particular H2S, CO and CO2, followed by recycling of the washed gaseous effluent in at least step a) of hydrotreatment and / or b) of hydrocracking.

[0023] In one embodiment, a portion of the liquid effluent obtained in step c) is recycled to step a) and / or step b), preferably to step a).

[0024] In one embodiment, the off-gas cut obtained in step d) is sent to a separation step in order to recover a depropanized off-gas gas cut low in propane and butane and an LPG cut.

[0025] In one embodiment, the LPG cut is sent to the steam cracking step f), separately or mixed with the naphtha cut obtained in step e), in one or more furnaces of the steam cracking step f).

[0026] In one embodiment, in step e) of fractionation of the stripped liquid effluent obtained in step d), a heavy cut is also obtained comprising hydrocarbon compounds having boiling points above 150°C, preferably above 175°C.

[0027] In one embodiment, the heavy cut obtained in step e) is wholly or partly recycled to step a) of hydrotreatment and / or b) of hydrocracking, preferably with a recycled feedstock / fresh feedstock ratio of between 0 and 4.

[0028] BRIEF DESCRIPTION OF THE FIGURES

[0029] Figure 1 illustrates the implementation of the method according to a first embodiment of the invention.

[0030] Figure 2 illustrates the implementation of the method according to a second embodiment of the invention.

[0031] DETAILED DESCRIPTION OF THE INVENTION

[0032] According to the present invention, the expression "between ... and ..." and "between .... and ..." are equivalent and mean that the limit values ​​of the interval are included in the range of values ​​described. If this is not the case and the limit values ​​are not included in the range described, such precision will be provided by the present invention.

[0033] For the purposes of the present invention, the different parameter ranges for a given step such as pressure ranges and temperature ranges may be used alone or in combination. For example, for the purposes of the present invention, a preferred pressure value range may be combined with a more preferred temperature value range.

[0034] In the following, particular embodiments of the invention may be described. They may be implemented separately or combined with each other, without limitation of combinations when technically feasible.

[0035] In this description, the term “Cx hydrocarbons” designates hydrocarbon compounds containing x carbon atoms. The term “Cx+ hydrocarbons” designates hydrocarbon compounds containing at least x carbon atoms. The term “Cx to Cy hydrocarbons” designates hydrocarbon compounds containing between x and y carbon atoms.

[0036] Throughout this text, groups of chemical elements are described according to the new IUPAC classification. For example, groups 9 or 10 correspond to the metals in columns 9 and 10 according to the IUPAC classification or to the last two columns of group VI 11 B according to the CAS classification (CRC Handbook of Chemistry and Physics, CRC editor press, editor-in-chief DR Lide, 81st edition, 2000-2001). Similarly, group 6 corresponds to the metals in column 6 according to the IUPAC classification or to the metals in columns VIB according to the CAS classification.

[0037] “Fresh feed” means the feed to be treated entering the process at step a) of hydrotreatment.

[0038] The term "naphtha cut" means a cut which can have boiling points ranging from that of hydrocarbon compounds having 5 carbon atoms per molecule up to 215°C.

[0039] The term "purge" means the cut comprising unconverted compounds produced continuously or discontinuously to avoid the accumulation of unwanted and uncrackable heavy molecules.

[0040] The term "off-gas cut" refers to the vapor cut resulting from the stripping step. The term "depropanized off-gas cut" refers to the vapor cut lean in propane and butane. Here, the term "lean in": comprising less than 2% by volume of propane and butane compounds, preferably less than 1% by volume.

[0041] The term "LPG" refers to the vapor fraction rich in propane and butane by analogy with the fossil Liquefied Petroleum Gas (LPG) fractions containing these compounds. Here, the term "rich in" refers to: comprising more than 95% by volume of propane and butane compounds.

[0042] The term "light naphtha" means a fraction which can have boiling points ranging from that of hydrocarbon compounds having 5 carbon atoms per molecule up to 110°C.

[0043] For the naphtha from step e), the term "paraffin-rich" means: comprising more than 90% by weight of desired compounds

[0044] The term "distillate" means the cut characterized by the distillation interval and having boiling points above 150°C and up to 560°C.

[0045] "Pyrolysis oil" means the cut recovered at the bottom of the primary fractionation tower of the steam cracking stage.

[0046] In this text, hydrotreatment includes impurity hydrotreatment reactions, including hydrodeoxygenation, hydrodesulfurization, hydrodenitrogenation, olefin hydrogenation, etc., using at least one catalyst in the presence of hydrogen to produce an effluent depleted in impurities.

[0047] In this text, "hydrocracking" includes processes aimed at reducing the number of carbons in molecules using at least one catalyst in the presence of hydrogen and producing products with a lower distillation point than that of the feedstock.

[0048] In this text, "stripping" encompasses physical separation processes in which one or more components are removed from a liquid stream by a steam stream or heat input. The "stripped" effluent is therefore the liquid effluent leaving the stripping stage. 1

[0049] Charge

[0050] The process according to the present invention consists of converting into paraffinic hydrocarbons a wide range of feedstocks of renewable origin, essentially composed of triglycerides and fatty acids.

[0051] By "essentially composed of triglycerides and fatty acids" is meant a filler comprising at least 70% by weight of triglycerides and fatty acids, preferably at least 80% by weight. Other specific elements may be present, but only those which do not materially affect the essential characteristics of the composition.

[0052] These fillers are generally characterized by a high molar mass (most often greater than 800 g / mol), and the fatty acid chains that compose them advantageously have a number of carbon atoms between 4 and 24, and a number of unsaturations per chain generally between 0 and 3, with higher values ​​that can be achieved on certain specific fillers. Among the fillers that can be converted by the process according to the present invention, there may be mentioned, this list not being exhaustive: vegetable oils such as rapeseed, jatropha, soybean, palm, sunflower, olive, copra, camelina oils, fish oils or heterotrophic or autotrophic algal oils, or animal fats such as beef tallow, or residues from the paper industry (such as "tall oil" according to Anglo-Saxon terminology), or mixtures of these various fillers.

[0053] Preferably, the fillers from renewable sources are chosen from oils and fats of vegetable or animal origin, or mixtures of such fillers, containing triglycerides and / or free fatty acids and / or esters.

[0054] All these feedstocks contain high oxygen contents, i.e. typically greater than 5% by weight, preferably greater than 8% by weight, as well as, at contents which vary greatly depending on the origin of the feedstocks, significant quantities of impurities which may contain at least one heteroatom other than oxygen and organic impurities which essentially comprise nitrogen. Said feedstocks may generally comprise a content of compounds containing heteroatoms other than oxygen of between 0.1 and 2500 ppm. The nitrogen and sulfur contents are generally less than 100 ppm by weight, and may reach up to 1% by weight in particular feedstocks.

[0055] Said fillers typically have an oxygen content of at most 20% by weight, preferably at most 15% by weight, preferably between 5 and 15% by weight, in particular between 8 and 15% by weight. Said fillers differ from Bio-oil type fillers which are immiscible.

[0056] The feedstocks from renewable sources used in the process according to the invention may advantageously be crude, or may have undergone at least one step of refining the oil for food purposes known to those skilled in the art, such as, for example, a degumming or dephosphatation step. Said feedstocks having undergone at least said refining step are said to be semi-refined and, at the end of this treatment, still contain up to 20 ppm of phosphorus, calcium, magnesium, iron and / or zinc, in the form of phospholipids.

[0057] In one embodiment, the presence of feedstocks of fossil origin is excluded in order to produce only cuts of renewable origin for the steam cracking step.

[0058] Advantageously, said fresh filler is chosen from vegetable oils such as rapeseed, jatropha, soybean, palm, sunflower, olive, copra, camelina oils, fish oils or heterotrophic or autotrophic algal oils, or animal fats such as beef tallow, or residues from the paper industry (such as "tall oil" according to Anglo-Saxon terminology), or mixtures of these various fillers.

[0059] Operating conditions and catalysts

[0060] The process according to the invention comprises a step a) of hydrotreatment of the feedstock in the presence of hydrogen and at least one fixed-bed hydrotreatment catalyst, carried out at a temperature of between 280 and 410°C, preferably between 290 and 320°C, and at a relative pressure of between 2.0 and 13.0 MPa, preferably between 2.5 and 9.0 MPa, and at an hourly volumetric rate (WH) of between 0.3 and 5 h' 1 , preferably between 0.7 and 3 h 1 , and obtaining a hydrotreated effluent.

[0061] In one embodiment, said hydrotreatment catalyst comprises a conventional hydrogenating function.

[0062] Advantageously, the hydrotreatment catalyst comprises a support and an active phase, said active phase comprising at least one metal from group 6 and optionally one or more metals from group 9 or 10, preferably the active phase contains molybdenum only (Mo), or nickel and molybdenum (NiMo), or cobalt and molybdenum (CoMo), or nickel, cobalt and molybdenum (CoNiMo). Advantageously, it is possible, for example, to use a catalyst comprising from 0.5 to 10% by weight of nickel (expressed as nickel oxide NiO) or from 1 to 30% by weight of molybdenum, preferably from 5 to 25% by weight of molybdenum (expressed as molybdenum oxide Mo03) on an alumina support. The total content of metal oxides from groups 6 and 9 or 10 in the catalyst is generally between 5 and 40% by weight and preferably between 7 and 35% by weight.Where applicable, the weight ratio (expressed on the basis of the metal oxides) of group 6 metal(s) to group 9 or 10 metal(s) is, in general, about 20 to about 1, and most often about 10 to about 2.

[0063] Advantageously, the various catalysts mentioned above can also be stacked in successive layers. A stack can be, for example, the sequence of a layer comprising nickel, cobalt and molybdenum (CoNiMo), followed by a layer comprising nickel and molybdenum (NiMo) or vice versa. Another stack can be, for example, the sequence of a layer comprising cobalt and molybdenum (CoMo) followed by a layer comprising nickel and molybdenum (NiMo) or vice versa.

[0064] Advantageously, the hydrotreatment catalyst is supported at least partially, or even entirely, on an alumina support.

[0065] In one embodiment, hydrotreatment step a) is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 Nm3 / Sm3, preferably between 150 and 1000 Nm3 / Sm3.

[0066] The hydrogen to hydrocarbon ratio is defined here as the ratio of the volume flow rate of hydrogen taken under normal temperature and pressure conditions to the volume flow rate of the feedstock which feeds stage a) (in normal m 3 , noted Nm 3 , of H2 by standard m 3 rated Sm 3 of charge entering step a).

[0067] In one embodiment, hydrotreatment step a) is operated at a minimum hydrogen partial pressure of 2.0 MPa, preferably at least 4.0 MPa.

[0068] This hydrotreatment step a) advantageously makes it possible to produce a hydrocarbon cut with reduced oxygen and nitrogen compound contents.

[0069] In one embodiment, hydrotreatment step a) is followed by an optional high-temperature separation step of between 280 and 410°C, preferably between 290 and 320°C, of ​​the hydrotreated effluent, and obtaining at least one gaseous effluent rich in hydrogen, oxygenated compounds and light hydrocarbons and a liquid effluent. Here, the term "hydrogen-rich" means a hydrogen content greater than 65% by volume. In one embodiment, a portion of the liquid effluent obtained in the optional high-temperature separation step is recycled to hydrotreatment step a). This recycling advantageously makes it possible to control the increase in temperature due to the hydrotreatment reaction.

[0070] The non-recycled part of the liquid effluent and the hydrogen-rich gaseous effluent from step a) are sent to the following hydrocracking step b).

[0071] In one embodiment, the portion of the liquid effluent obtained in the optional high-temperature separation step is recycled to the hydrotreatment step a) so that the mass ratio between said portion of the recycled effluent and the fresh feedstock introduced into the hydrotreatment step a) is less than 3, preferably less than 1.

[0072] Advantageously, the configuration of the reactor capable of carrying out the reactions according to the invention is composed of a number of suitable catalyst beds. Generally, the configuration has at least 2 catalyst beds and preferably more than 3, and in particular more than 4 beds but less than 20 beds, and preferably less than 15 beds and in particular less than 10 catalyst beds. The preferred configuration comprises between 3 and 19 beds, and in particular comprises between 4 and 9 catalyst beds.

[0073] The liquid effluent from step a) consists essentially of linear paraffins, i.e. the product has a composition of at least 90% by weight of linear paraffins.

[0074] The process according to the invention comprises a step b) of hydrocracking the hydrotreated effluent obtained in step a) in the presence of hydrogen and at least one fixed-bed hydrocracking catalyst, at a temperature of between 280 and 410°C, preferably between 290 and 320°C, carried out at a pressure of between 2.0 MPa and 13.0 MPa, preferably between 2.5 and 9.0 MPa, and at a WH of between 0.5 and 10 h 1 , preferably between 1 and 4 hours* 1 , and obtaining a hydrocracked effluent.

[0075] In the process according to the invention, the hydrocracking step is carried out immediately after the hydrotreatment step, with optionally an intermediate high-temperature and high-pressure separation step, so that the pressure and temperature loss is minimal with a minimal number of equipment items. High temperature means a temperature between 150°C and 410°C, preferably between 200 and 320°C. High pressure means a relative pressure between 2.0 and 13.0 MPa, preferably between 2.5 and 9.0 MPa, in particular at a pressure slightly lower than the pressure of step a) and slightly higher than that of step b) to take into account the pressure losses associated with the successive equipment items.

[0076] In the embodiment where hydrotreatment step a) is followed by a high-temperature separation step, it is the non-recycled part of the liquid effluent and the hydrogen-rich gaseous effluent which are hydrocracked in step b).

[0077] In one embodiment, hydrocracking step b) is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 Nm 3 / Sm 3 , preferably between 200 and 2000 Nm 3 / Sm 3 .

[0078] Advantageously, in step b) the conversion per pass into hydrocarbon compounds is between 20 and 100% by weight, preferably between 45 and 80% by weight, preferably between 50 and 70% per pass. The conversion per pass is calculated relative to the feed entering step b) using the following operation: (the flow rate by weight of the effluent entering step b) minus the flow rate of the optional bottom cut resulting from the fractionation of step e) by weight) divided by the flow rate by weight of effluent entering step b). Thus, the hydrocracking step b) advantageously produces naphtha and the quantity of LPG produced is minimal.

[0079] Advantageously, the overall conversion of the fresh feedstock into naphtha is between 80% and 100%, preferably between 95% and 100%, more preferably between 99% and 100%, especially 100%. The overall conversion is calculated relative to the feedstock entering step a) using the following operation: (the flow rate by weight of the fresh feedstock entering step a) minus the flow rate by weight of the purged portion of the heavy cut in step e), described below) divided by (the flow rate by weight of the fresh feedstock entering step a.

[0080] In one embodiment, hydrocracking step b) is carried out at a minimum hydrogen partial pressure of 2.5 MPa.

[0081] The operating conditions of the hydrocracking step b) are advantageously adjusted so as to maximize the production of naphtha, while ensuring good operability of the hydrocracking unit. The operating conditions used in the reaction zone(s) are generally expressed using the average temperature of the catalyst bed (WABT or "Weighted Average Bed Temperature" according to English terminology). The hydrocracking temperature is advantageously determined according to the catalytic systems, the equipment used, and their configuration. For example, the average temperature of the catalyst bed (or WABT) is calculated as follows: WABT = (Tinput + Toutput ) / 2 with Tinput: the inlet temperature of the catalyst bed of the hydrocracking reaction section, and T sor tie: the temperature of the effluent at the outlet of the hydrocracking reaction section catalyst bed.

[0082] The hourly volume flow rate (WH) is defined here as the ratio between the hourly volume flow rate of the hydrocarbon cut feeding step b) per volume of catalyst(s).

[0083] Advantageously, the hydrogen used in hydrocracking step b) may come from a hydrogen supplement and / or recycled hydrogen originating in particular from separation step c), preferably after purification, and / or from a hydrogen-rich gaseous effluent originating from step a).

[0084] The at least one hydrocracking catalyst must advantageously be a bifunctional catalyst, having a hydrogenating phase in order to be able to hydrogenate the impurities and achieve the balance between the saturated compounds and the corresponding olefins, and an acid phase which makes it possible to promote the hydroisomerization and hydrocracking reactions. The acid function is provided by supports with large surface areas (generally 100 to 800 m 2 .g~ 1) with surface acidity, such as halogenated aluminas (chlorinated or fluorinated in particular), combinations of boron and aluminum oxides, amorphous silica-aluminas and Y, Beta and ZSM-5 zeolites. The hydrogenating function is provided either by one or more metals from columns 9 and 10 of the periodic table of elements, such as cobalt, nickel, rhodium, palladium, iridium and platinum, or by a combination of at least one metal from column 6 of the periodic table of elements such as molybdenum and tungsten and at least one metal from columns 9 and 10. The applicant has also developed a range of catalysts that can be used in step b) of hydrocracking; these catalysts are described in particular in documents FR2819430, FR2846574, FR2875417, FR2863913, FR2795341, FR2795342 and FR2984760.

[0085] Advantageously, it is possible, for example, to use a catalyst comprising from 0.5 to 10% by weight of nickel (expressed as nickel oxide NiO) or from 1 to 30% by weight of molybdenum, preferably from 5 to 25% by weight of molybdenum (expressed as molybdenum oxide Mo03) or from 1 to 40% by weight of tungsten (expressed as tungsten oxide WO3) on the support in question. The total content of metal oxides from groups 6 and 9 or 10 in the catalyst is generally between 5 and 40% by weight and preferably between 7 and 35% by weight. Where applicable, the weight ratio (expressed on the basis of the metal oxides) of group 6 metal(s) to group 9 or 10 metal(s) is, in general, about 20 to about 1, and most often about 10 to about 2.

[0086] In one embodiment, commercial catalysts may be used, among others and depending on the characteristics of the feedstock and the desired performance, such as HDK776, HDK766, HYK732, HYK752, HYK762, HYK742, HYK 743 marketed by the company AXENS, for example.

[0087] In the case where said catalyst comprises a zeolite, the zeolite content in the hydrocracking catalyst(s) is advantageously between 0.1 and 80% by weight, preferably between 3 and 70% by weight, the percentages being expressed as a percentage of zeolite relative to the total weight of the catalyst.

[0088] A preferred catalyst comprises, and preferably consists of, at least one metal from column 6 and optionally at least one non-noble metal from columns 9 and 10, at least one promoter element, preferably phosphorus, at least one Y zeolite and at least one alumina binder.

[0089] An even more preferred catalyst comprises, and preferably consists of, nickel, molybdenum, phosphorus, a USY zeolite, and optionally also a beta zeolite, and alumina.

[0090] Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, alumina and silica-alumina.

[0091] Another preferred catalyst comprises, and preferably consists of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

[0092] In a particular embodiment, said hydrocracking catalyst is in extruded form.

[0093] According to another aspect of the invention, the hydrocracking catalyst as described above further comprises one or more organic compounds containing oxygen and / or nitrogen and / or sulfur. Such a catalyst is often referred to as an "additive catalyst". Generally, the organic compound is chosen from a compound comprising one or more chemical functions chosen from a carboxylic, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea and amide function or compounds including a furan ring or sugars. According to one embodiment, this hydrocracking step b) makes it possible to produce a naphtha-type cut which is advantageously very paraffinic, the paraffin content of which is typically greater than 90% by weight, preferably greater than 95% by weight.

[0094] Preferably, the naphtha produced in step b) consists of paraffinic compounds and any other non-paraffinic compounds contained in the feedstock.

[0095] Advantageously, the configuration of the reactor capable of carrying out the reactions according to the invention is composed of a number of suitable catalyst beds. Generally, the configuration comprises at least 2 catalyst beds and preferably more than 3 and in particular more than 5 beds, but less than 20 beds and preferably less than 15 beds and in particular less than 10 catalyst beds. The preferred configuration comprises between 2 and 19 beds and in particular between 3 and 9 catalyst beds.

[0096] The process according to the invention comprises a step c) of separating the hydrocracked effluent obtained in step b), and obtaining at least one gaseous effluent comprising hydrogen and a liquid hydrocarbon effluent.

[0097] In one embodiment, in step c) of separation of the hydrocracked effluent obtained in step b), contaminants, possible light hydrocarbons, and an aqueous liquid effluent are also obtained.

[0098] The separation section of step c) is advantageously carried out in separation equipment well known to those skilled in the art (separator tanks which can operate at different pressures and temperatures, pumps, heat exchangers, etc.).

[0099] In one embodiment, separation step c) is followed by a step of purification and / or washing of the gaseous effluent comprising hydrogen obtained in step c) to remove contaminants, in particular H2S, CO and CO2, followed by recycling of the washed gaseous effluent in at least step a) of hydrotreatment and / or b) of hydrocracking. The purpose of this step is to ensure hydrogen coverage and control of the exotherm in step a) and / or step b).

[0100] Typically, a small portion of the gaseous effluent may be purged to prevent the accumulation of oxygenated compounds and light compounds towards the fuel gas network or towards a hydrogen recovery unit.

[0101] In one embodiment, a portion of the liquid effluent obtained in step c) is recycled to step a) and / or step b), preferably to step a). Recycling to step a) allows the exotherm to be managed and the flow rate of the first recycling to be reduced in the embodiment where step a) is followed by a high-temperature separation step followed by recycling of a portion of the liquid effluent from this separation. Recycling to step b) allows the conversion in step b) and the overall conversion of the fresh feedstock to be controlled.

[0102] The process according to the invention comprises a step d) of stripping the liquid hydrocarbon effluent obtained in step c), and obtaining at least one off-gas cut, and a stripped liquid effluent.

[0103] Step d) makes it possible in particular to eliminate gases dissolved in the liquid hydrocarbon effluent, such as ammonia, hydrogen sulfide, CO2, CO and light hydrocarbons having 1 to 4 carbon atoms by producing an off-gas cut comprising these compounds.

[0104] In one embodiment, the off-gas cut is sent, after an optional washing step, in whole or in part to the steam cracking step f), separately or in a mixture with the naphtha cut obtained in step e), in one or more furnaces of the steam cracking step f), making it possible to upgrade this cut into biosourced olefins.

[0105] In one embodiment, the off-gas cut obtained in step d) is sent to a separation step in order to recover at least one depropanized off-gas gas cut low in propane and butane and one LPG cut. This separation step can advantageously be carried out in separation columns.

[0106] In one embodiment, the LPG cut is sent to the steam cracking step f), separately or mixed with the naphtha cut obtained in step e), in one or more furnaces of the steam cracking step f), making it possible to upgrade this cut into biosourced olefins.

[0107] In one embodiment, the depropanized off-gas gaseous cut low in propane and butane is sent to the steam cracking step f), after an optional washing step, separately or mixed with the naphtha cut obtained in step e), in one or more furnaces of the steam cracking step f), making it possible to upgrade this cut into biosourced olefins.

[0108] In another embodiment, the depropanized off-gas gaseous cut low in propane and butane and / or the LPG cut is sent to a steam reforming stage (“steam reformer” according to English terminology) to obtain biosourced hydrogen.

[0109] According to one embodiment, step d) can be carried out in a section advantageously comprising at least one stripping column equipped with a reflux circuit comprising a reflux drum. Said stripping column is advantageously supplied with the liquid effluent from step c) and with a stream of water vapor. Said column can also be reboiled by a furnace or an exchanger. The liquid effluent from step c) can optionally be reheated before entering the stripping column.

[0110] Thus, the lightest compounds are carried to the top of the column and into the reflux circuit comprising a reflux drum in which a gas / liquid separation takes place. The gaseous phase, which comprises the light hydrocarbons, is withdrawn from the reflux drum in a gaseous stream. The stripped liquid hydrocarbon effluent is advantageously stabilized and withdrawn at the bottom of the stripping column.

[0111] According to one embodiment, a liquid LPG cut can be recovered at the reflux drum and then stabilized in a stabilization column. The stabilized liquid LPG cut is sent to the LPG cut obtained in the off-gas cut separation step.

[0112] According to one embodiment, a light naphtha cut can be recovered from the reflux drum and then stabilized in a stabilization column. The stabilized light naphtha cut is sent to the naphtha cut obtained in fractionation step f).

[0113] According to one embodiment, stripping step d) can be carried out on a portion of the hydrocarbon liquid effluent obtained in step c), the other portion fed directly to fractionation step d), allowing at least one off-gas cut to be obtained, and a stripped liquid effluent which is sent to the fractionation step. In this embodiment, a portion of stripping step d) is carried out in the fractionation step.

[0114] According to another embodiment, stripping step d) is integrated into fractionation step e) and a person skilled in the art can, using the same fractionation section, comprising one or more columns, obtain the different flows described in these two steps.

[0115] Step e) of splitting

[0116] The process according to the invention comprises a step e) of fractionating the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut.

[0117] In one embodiment, in step e) of fractionation of the stripped liquid effluent obtained in step d), a heavy cut is also obtained comprising hydrocarbon compounds having boiling points above 150°C, preferably above 175°C.

[0118] In a particular embodiment, the heavy cut obtained comprises compounds having boiling points above 215°C, preferably above 200°C. This makes it possible to produce a heavy naphtha cut having a boiling point of up to 215°C. In one embodiment, the heavy cut is fully or partially recycled to the hydrotreatment and / or hydrocracking stage a) and / or b), preferably with a recycled feedstock / fresh feedstock ratio of between 0 and 4. This makes it possible to control the conversion rate in the hydrocracking reactor, and to achieve the overall conversion under optimal conditions in terms of investment and utility consumption.

[0119] Advantageously, a small portion of the heavy cut is purged, continuously or intermittently, before it is sent to step a) and / or b). A person skilled in the art adjusts the purged quantity to remove compounds that cannot be cracked and that have accumulated in the reaction loop.

[0120] Advantageously, the quantity of recycled heavy cut is adjusted so that the weight ratio between the recycled flow and the fresh feedstock feeding the overall process is less than or equal to 10, preferably less than or equal to 5, and preferably greater than or equal to 0.001, preferably greater than or equal to 0.01, and more preferably greater than or equal to 0.1. Very preferably, the quantity of recycled flow is adjusted so that the weight ratio between the recycled flow and the fresh feedstock is between 0.2 and 5, preferably between 0.3 and 2.0, even more preferably between 0.5 and 1.5.

[0121] Depending on the charges treated, this recycling advantageously makes it possible on the one hand to dilute the impurities and on the other hand to control the temperature in the reaction stage(s) a) and / or b), in which the reactions involved can be highly exothermic.

[0122] The fractionation step advantageously comprises at least one main fractionation column, making it possible to separate a head fraction and a heavy fraction, said fractions comprising the different products of the units.

[0123] Fractionation step e) is advantageously carried out at a pressure less than or equal to 1.0 MPa abs., preferably between 0.05 and 1.0 MPa abs.

[0124] In one embodiment, all of the cuts from the process are recovered as renewable products.

[0125] The naphtha cut is sent at least in part, preferably in full, to a steam cracking unit f), allowing this cut to be recovered into bio-sourced olefins.

[0126] Advantageously, the naphtha yield in the process according to the invention is greater than 50% by weight, in particular greater than 60% by weight, preferably greater than 70% by weight, preferably between 50% and 85% by weight. The naphtha yield is calculated relative to the fresh feed entering step a) using the following operation: (the flow rate by weight of naphtha produced in step e) divided by the flow rate by weight of the effluent entering step a))-

[0127] Step f) of steam cracking

[0128] The process according to the invention comprises a step f) of steam cracking at least a part, preferably all of the naphtha cut obtained in step e) and obtaining at least one biosourced gaseous effluent comprising ethylene and propylene.

[0129] In one embodiment, the off-gas cut obtained in step d) is also treated in step f) of steam cracking, separately from the naphtha cut or in co-treatment.

[0130] In one embodiment, the LPG cut obtained after an optional step of separation of the off-gas cut obtained in step d) is also treated in step f) of steam cracking, separately from the naphtha cut or in co-treatment.

[0131] In one embodiment, the depropanized off-gas gaseous cut lean in propane and butane obtained after an optional step of separation of the off-gas cut obtained in step d) is also treated in step f) of steam cracking, separately from the naphtha cut or in co-treatment.

[0132] The steam cracking step f) advantageously consists of the non-catalytic decomposition under the combined effect of high temperature and low pressure in the presence of water vapor, of saturated hydrocarbons from natural gas or naphtha in the presence of water vapor, in order to produce aliphatic or aromatic unsaturated hydrocarbon cuts. Said cuts are then used for the synthesis of a large number of products, for example polyethylene or propylene. In the case of the process according to the invention, the steam cracking step f) makes it possible to produce renewable aliphatic unsaturated hydrocarbons (of biosourced origin).

[0133] Advantageously, the steam cracking step f) treats the naphtha cut and / or the LPG cut in the suitable scheme and operating conditions known to those skilled in the art.

[0134] Advantageously, the steam cracking unit processes the naphtha and / or LPG cut in the optional presence of an external charge of naphtha and / or LPG.

[0135] Advantageously, the residence time in the steam cracking furnace is limited in order to limit the formation of heavy products. In addition, quenching of the effluent is implemented in order to freeze the composition of the effluent at the exit of the furnace. Advantageously, the temperature at which the steam cracking furnaces are operated depends on the nature of the feedstock. Preferably, the steam cracking furnaces are adapted to treat a naphtha-type feedstock.

[0136] In the various variants of the process according to the invention, the feeds in the steam cracking stage may comprise external feeds, corresponding to dedicated furnaces or common with the furnaces treating the feeds produced by the stages of the process according to the invention. Said external feeds may be varied and range from light saturated hydrocarbons such as ethane, propane or ethane-propane mixtures, to more or less heavy petroleum cuts such as petrochemical naphtha. The nature of the feeds treated will depend on the types of furnaces installed.

[0137] Advantageously, the steam cracking stage is implemented in a plant that consists of a number of furnaces, quenching boilers and a fractionation train. The hydrocarbon feedstock enters the hot section of the unit through the convection zone A of the furnace where it is preheated, then it is mixed with the water vapor also preheated in this same zone; the hydrocarbons and the water then pass through the actual radiation zone of the furnace where the rapid rise in temperature and the pyrolysis reactions take place. At the outlet of the furnace, the effluents are, in order to avoid any subsequent reaction, frozen in their kinetic possibilities of evolution by a sudden quench generally carried out in two stages: an initial indirect quench with water, followed by a direct quench using the heavy residue by-product of pyrolysis.The effluents are then transferred to a primary fractionation tower which separates at the bottom a heavy residue called "pyrolysis oil" and, by withdrawal, a fraction of the steam cracking gasoline and water, while the light pyrolysis products exit at the top in gaseous form.

[0138] After compression, washing with soda (intended to eliminate H2S and acid gases) and drying, these light effluents then enter the cold section of the unit which can be designed in various ways, but which ensures the separation of hydrogen, ethylene at 99.9% (by mass), propylene at 95% which can, in whole or in part, be brought to 99.5% (by mass), a C4 cut, the complementary fraction of steam cracking gasoline rich in aromatic hydrocarbons (more than 50% by weight of aromatic compounds). DESCRIPTION OF THE FIGURES

[0139] Figure 1: A vegetable oil feedstock 111 is fed into a hydrotreatment step a) in the presence of hydrogen 112 and at least one fixed-bed catalyst, said catalyst comprising a conventional NiMo hydrogenating function to obtain a hydrotreated vegetable oil effluent 113, which is then sent to a hydrocracking step b) in the presence of hydrogen 114 and in the presence of a USY NiMo zeolite catalyst to obtain a hydrocracked effluent 115. The hydrocracked effluent 115 is sent to a separation step c) to obtain a gaseous effluent 116 comprising hydrogen and a liquid effluent 117. The liquid effluent 117 is sent to a stripping step to recover an offgas cut 118 and a stripped liquid effluent 119. The stripped liquid effluent 119 is then sent to a fractionation step e) to recover at least one cut paraffin-rich naphtha 1 1 .The naphtha cut 121 is sent to a steam cracking step f) in order to produce the effluent 12 rich in ethylene, propylene and bio-sourced light olefins. In this embodiment, the process does not produce a heavy cut comprising compounds having boiling points above 150°C.

[0140] Figure 2: A vegetable oil feedstock 211 is fed into a hydrotreatment step a) in the presence of hydrogen 212 and at least one fixed-bed catalyst, said catalyst comprising a conventional NiMo hydrogenating function to obtain a hydrotreated vegetable oil effluent immediately followed by a high-temperature separation step to recover a liquid effluent and a gaseous effluent 223 rich in hydrogen, oxygenated compounds and light hydrocarbons. A portion of the liquid effluent 224 is recycled to the hydrotreatment step a) in order to control and reduce the exotherm in the reactor during this step.The non-recycled portion of the liquid effluent 213 is mixed with the gaseous effluent 223 and is then sent to a hydrocracking step b) in the presence of hydrogen included in the gaseous effluent 223 but also in the presence of a hydrogen-rich stream 214 and in the presence of a USY zeolite-type hydrocracking catalyst, to obtain a hydrocracked effluent 215. Said hydrocracked effluent 215 is sent to a separation step c) to obtain at least one gaseous effluent 216 comprising hydrogen and a liquid effluent. The gaseous effluent 216 is optionally sent to a washing step in order to remove contaminants and is recycled to the hydrotreatment step a) and / or to the hydrocracking step b). A portion of the liquid effluent 225 may optionally be recycled to the hydrotreatment and / or hydrocracking stage a) in order to control and reduce the exotherm in the reactor of these stages.The non-recycled portion of the liquid effluent 217 is sent to a stripping step to recover an off-gas cut 218 and a stripped liquid effluent 219. An LPG cut 226 is separated from the gaseous effluent 218 and can optionally be sent to the steam cracking step f). The stripped liquid effluent 219 is sent to a fractionation step e) to recover at least two liquid effluents, including 221 a paraffin-rich naphtha cut and 220 a heavy cut having a boiling point above 150°C which is recycled to the hydrotreatment and / or hydrocracking step a), preferably to the hydrocracking step a) to be converted again. The naphtha cut 221 is sent to a steam cracking step f) in order to produce the effluent 222 rich in bio-sourced ethylene, propylene and light olefins. EXAMPLES.

[0141] Example 1: Process for treating a load from a renewable source according to the invention

[0142] The characteristics of the rapeseed oil feedstock used are presented in the following table: Table 1 The operating conditions in the hydrotreatment section are presented in the following table:

[0143] Table 2 The operating conditions in the hydrocracking (HCK) stage are presented in the following table:

[0144] Table 3 The overall results of the process are presented in the following table:

[0145] Table 4

[0146] The properties of C5-175°C cutting point naphtha are as follows: - Paraffinic feedstock: paraffin content greater than 99% by weight

[0147] Density 677 kg / m3

[0148] - Sulfur <1 ppm weight

[0149] - Nitrogen <1 ppm weight

[0150] - Oxygen content < 0.1% by weight These properties make it a feedstock of choice for the production of ethylene and propylene because it is very rich in paraffins.

[0151] The resulting bio-sourced naphtha feedstock is sent to the steam cracker at a flow rate of 76 t / h. This paraffin-rich feedstock produces high yields of bio-sourced ethylene and propylene, with at least 65% of the feedstock entering the steam cracker. The LPG cut and / or the off-gas cut can also be sent to the steam cracker. The process according to the invention therefore makes it possible to produce almost exclusively naphtha and an LPG cut, unlike prior art processes. In addition, the process is implemented in a minimum number of equipment, since the hydrotreatment and hydrocracking steps are carried out one after the other without a separation step.

Claims

CLAIMS Process for treating a feedstock from a renewable source comprising triglycerides and / or fatty acids and / or esters, said process comprising the steps of: a) a step of hydrotreating said feedstock in the presence of hydrogen and at least one hydrotreatment catalyst in a fixed bed, carried out at a temperature of between 280 and 410°C, and at a relative pressure of between 2.0 and 13.0 MPa, and at an hourly volumetric rate of between 0.3 and 5 h 1 , and obtaining a hydrotreated effluent; b) a step of hydrocracking the hydrotreated effluent obtained in step a) in the presence of hydrogen and at least one fixed-bed hydrocracking catalyst, at a temperature between 280 and 410°C, operated at a pressure between 2.0 MPa and 13.0 MPa, and at an hourly volumetric rate between 0.5 and 10 h 1, and obtaining a hydrocracked effluent; c) a step of separating the hydrocracked effluent obtained in step b), and obtaining at least one gaseous effluent comprising hydrogen and a hydrocarbon liquid effluent; d) a step of stripping the hydrocarbon liquid effluent obtained in step c), and obtaining at least one off-gas cut and a stripped liquid effluent; e) a step of fractionating the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut; f) a step of steam cracking at least a portion, preferably all of the naphtha cut obtained in step e) and obtaining at least one biosourced gaseous effluent comprising ethylene and propylene. Process according to claim 1, in which step a) of hydrotreatment is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 Nm3 / Sm3.A process according to any preceding claim, wherein the at least one hydrotreatment catalyst comprises a support and an active phase, said active phase comprising at least one metal from group 6 and optionally one or more metals from group 9 or 10, preferably the active phase contains molybdenum only (Mo), or nickel and molybdenum (NiMo), or cobalt and molybdenum (CoMo), or nickel, cobalt and molybdenum (CoNiMo). Process according to any one of the preceding claims, in which the hydrotreatment step a) is followed by a separation step at high temperature between 280 and 410°C, and at high pressure between 2.0 and 13.0 MPa, of the hydrotreated effluent, and obtaining at least one gaseous effluent and one liquid effluent. Process according to claim 4, in which a portion of the liquid effluent obtained in the high temperature separation step is recycled to the hydrotreatment step a). Process according to any one of the preceding claims, in which the hydrocracking step b) is carried out with a hydrogen to hydrocarbon ratio between 100 and 5000 Nm 3 / Sm 3. Process according to any one of the preceding claims, in which the hydrocracking step b) is carried out at a minimum hydrogen partial pressure of 2.5 MPa. Process according to any one of the preceding claims, in which the at least one hydrocracking catalyst comprises a hydrogenating function and an acid function provided by supports with large surface areas having a surface acidity, such as halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and Y, Beta and ZSM zeolites. Process according to any one of the preceding claims, in which in step b) the conversion per pass into hydrocarbon compounds is between 20 and 100% by weight.A process according to any one of the preceding claims, wherein separation step c) is followed by a step of purification and / or washing of the gaseous effluent comprising hydrogen obtained in step c) to remove contaminants, in particular H2S, CO and CO2, followed by recycling of the washed gaseous effluent in at least step a) of hydrotreatment and / or b) of hydrocracking. A process according to any one of the preceding claims, wherein a portion of the liquid effluent obtained in step c) is recycled to step a) and / or step b), preferably to step a). A process according to any one of the preceding claims, wherein the off-gas cut obtained in step d) is sent to a separation step in order to recover a depropanized off-gas gaseous cut lean in propane and butane and an LPG cut. Process according to claim X, in which the LPG cut is sent to the steam cracking step f), separately or in a mixture with the naphtha cut obtained in step e), in one or more furnaces of the steam cracking step f). Process according to any one of the preceding claims, in which in step e) of fractionation of the stripped liquid effluent obtained in step d), a heavy cut is also obtained comprising hydrocarbon compounds having boiling points above 150°C, preferably above 175°C. Process according to claim 14, in which the heavy cut obtained in step e) is wholly or partly recycled to the hydrotreatment and / or hydrocracking step a), preferably with a recycled feedstock / fresh feedstock ratio of between 0 and 4.Process according to any one of the preceding claims, in which said filler is chosen from vegetable oils such as rapeseed, jatropha, soybean, palm, sunflower, olive, copra, camelina oils, fish oils or heterotrophic or autotrophic algal oils, animal fats, residues from the paper industry or mixtures of these various fillers.

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