Process for treating a feedstock from a renewable source for the production of bio-based olefins

Abstract

The present invention relates to a process for treating a feedstock from a renewable source, said process comprising the steps of: a) a hydrotreatment step, and obtaining a hydrotreated effluent; b) a hydrocracking step of the hydrotreated effluent obtained in step a), and obtaining a hydrocracking effluent; c) a separation step of the hydrocracking effluent obtained in step b), and obtaining at least one hydrocarbon liquid effluent; d) a stripping step of the hydrocarbon liquid effluent obtained in step c), and obtaining at least one stripped liquid effluent; e) a fractionation step of the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut; f) a steam cracking step of at least a portion of the naphtha cut obtained in step e), and obtaining at least one bio-based gaseous effluent comprising ethylene and propylene. Figure 1 to be published

Description

Title of the invention: Process for treating a feedstock from a renewable source for the production of bio-based olefins. Technical field

[0001] 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, suitable for producing olefins such as ethylene, propylene and bio-based polymers for the chemical industry. Previous technique

[0002] Many hydrotreating 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.

[0003] FR2917424 discloses, for example, a process for treating a feed from a renewable source comprising a hydrotreating 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 hydrocarbon liquid effluent consisting of at least 50% linear n-paraffins, and steam cracking of at least a portion of the hydrocarbon liquid effluent from the separation step b).

[0004] FR3104603 discloses a process for the isomerization of paraffinic fillers, of preferably derived from hydrotreated vegetable and / or animal oils or from low-temperature Fischer-Trospch synthesis, said process employing 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 improves selectivity towards production from middle distillates by limiting the production of light cracked products that cannot be incorporated into a diesel and / or kerosene pool.

[0005] However, it is also necessary to increase the production of bio-based olefins obtained by steam cracking of feedstocks from renewable sources including triglycerides and / or fatty acids and / or esters in order to increase the quantity of sustainable polymers produced to replace polymers of fossil origin.

[0006] US2014350314 discloses in particular a process comprising a step hydrotreating a renewable feedstock to produce a hydrocarbon effluent, a hydrocracking step of said hydrocarbon effluent to produce a distribution cracked hydrocarbons, a separation step of a heavy cut and a bio-based naphtha cut, and a step of obtaining a middle distillate fraction from the heavy fraction.

[0007] Surprisingly, the applicant has developed an improved process for producing a naphtha cut from a bio-based feedstock that can be co-processed in most liquid steam crackers comprising a minimal number of steps. Summary of the invention

[0008] 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:

[0009] a) a hydrotreating step in the presence of hydrogen and at least one fixed bed hydrotreating catalyst, operated at a temperature between 280 and 410°C, and at a relative pressure between 2.0 and 13.0 MPa, and at an hourly volumetric velocity between 0.3 and 5h', and obtaining a hydrotreated effluent;

[0010] b) a hydrocracking step of 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 velocity between 0.5 and 1001, and obtaining a hydrocraced effluent;

[0011] c) a step of separating the hydrocracked effluent obtained in step b), and obtaining of at least one gaseous effluent containing hydrogen and one hydrocarbon liquid effluent;

[0012] 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;

[0013] e) a step of fractionating the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut;

[0014] f) a steam cracking step of at least part, preferably all of the naphtha cut obtained in step e) and obtaining at least one bio-based gaseous effluent comprising ethylene and propylene.

[0015] The process according to the invention makes it possible to produce ethylene, propylene and after polymerization, bio-based polymers.

[0016] Advantageously, this scheme makes it possible to produce only valuable cuts in a liquid steam cracker accepting naphtha cuts and possibly LPG cuts.

[0017] Thus, the process according to the invention preferably does not produce distillate cut.

[0018] Furthermore, the process is efficient because it does not require extensive separation of the hydrotreated effluent between step a) and step b), only a vessel generating a hydrotreated liquid effluent which is sent in part to step a) to control the exotherm of the reaction.

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

[0020] In one embodiment, the at least one hydrotreating 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).

[0021] In one embodiment, step a) of hydrotreatment is followed by a high temperature separation step between 150 and 410°C, and high pressure step between 2.0 and 13.0 MPa, of the hydrotreated effluent, and obtaining at least one gaseous effluent and one liquid effluent.

[0022] In one embodiment, part of the liquid effluent obtained in the high-temperature separation step is recycled to step a) of hydrotreatment.

[0023] In one embodiment, step b) of hydrocracking is carried out with a hydrogen to hydrocarbon ratio between 100 and 5000 Nm3 / Sm3.

[0024] In one embodiment, step b) of hydrocracking is carried out at a minimum partial pressure of hydrogen of 2.5 MPa.

[0025] In one embodiment, at least one hydrocracking catalyst comprises a hydrogenating function and an acid function provided by large surface supports exhibiting surface acidity, such as halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and Y, Beta and ZSM-5 zeolites.

[0026] In one embodiment, in step b) the pass conversion into hydrocarbon compounds is between 20 and 100% by weight.

[0027] In one embodiment, step c) of separation is followed by a step of purification and / or washing of the gaseous effluent including 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 hydrotreating and / or b) of hydrocracking.

[0028] In one embodiment, part of the liquid effluent obtained in step c) is recycled to step a) and / or step b), preferably to step a).

[0029] 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 cut low in propane and butane and an LPG cut.

[0030] 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).

[0031] In one embodiment, in step e) of fractionation of the stripped liquid effluent obtained in step d), a heavy cut comprising hydrocarbon compounds having boiling points above 150°C, preferably above 175°C, is further obtained.

[0032] In one embodiment, the heavy cut obtained in step e) is recycled in whole or in part to step a) of hydrotreating and / or b) of hydrocracking, preferably with a recycled feed / fresh feed ratio between 0 and 4. LIST OF FIGURES

[0033] [Fig.1]

[0034] Fig. 1 illustrates the implementation of the process according to a first embodiment of the invention.

[0035] [Fig.2]

[0036] Figure [Fig.2] illustrates the implementation of the process according to a second embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] According to the present invention, the expressions "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 clarification will be provided by the present invention.

[0038] In the sense of the present invention, the different parameter ranges for a given step, such as pressure ranges and temperature ranges, can be used alone or in combination. For example, in the sense of the present invention, a preferred range of pressure values ​​can be combined with a more preferred range of temperature values.

[0039] In the following, particular embodiments of the invention may be described. They may be implemented separately or in combination with each other, without limitation of combinations where technically feasible.

[0040] In this description, the term "Cx hydrocarbons" refers to hydrocarbon compounds having x carbon atoms. The term "Cx+ hydrocarbons" refers to hydrocarbon compounds having at least x carbon atoms. The term "Cx to Cy hydrocarbons" refers to hydrocarbon compounds having between x and y carbon atoms.

[0041] Throughout this text, groups of chemical elements are described according to the new IUP AC classification. For example, groups 9 or 10 correspond to the metals in columns 9 and 10 according to the IUP AC classification or to the last two columns of group VIIIB 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 IUP AC classification or to the metals in columns VIB according to the CAS classification.

[0042] The term "fresh load" means the load to be treated entering the process at step a) of hydrotreating.

[0043] The term "naphtha cut" means a cut that can have boiling points between that of hydrocarbon compounds having 5 carbon atoms per molecule and 215°C.

[0044] The term "purge" means the cut comprising the unconverted compounds produced continuously or discontinuously to avoid the accumulation of unwanted and uncrackable heavy molecules.

[0045] The term "off-gas cut" refers to the vapor cut resulting from the stripping step.

[0046] The term “depropanized off-gas cut” means the propane-lean steam cut and butane. Here we mean "low in": containing less than 2% by volume of propane and butane compounds, preferably less than 1% by volume.

[0047] The term "LPG cut" refers to the vapor cut rich in propane and butane, by analogy with fossil LPG cuts containing these compounds. "Rich in" here means comprising more than 95% by volume of propane and butane.

[0048] The term “light naphtha” means a cut that can have boiling points between that of hydrocarbon compounds having 5 carbon atoms per molecule and 110°C.

[0049] For the naphtha in step e), "paraffin-rich" means: comprising more than 90% by weight of desired compounds

[0050] The term "distillate" means the cut characterized by the distillation interval and having boiling points greater than 150°C and up to 560°C.

[0051] The term “Pyrolysis oil” refers to the fraction recovered at the bottom of the primary fractionation tower of the steam cracking step.

[0052] In the present text, hydrotreatment includes hydrotreatment reactions of impurities, including hydrodeoxygenation, hydrodesulfurization, hydrodeazotation, hydrogenation of olefins, etc., using at least one catalyst in the presence of hydrogen to produce an effluent depleted of impurities.

[0053] In this text, “hydrocracking” encompasses 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 feed.

[0054] 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 exiting the stripping step.

[0055] Charge

[0056] The process according to the present invention consists of converting a wide range of renewable feedstocks, essentially composed of triglycerides and fatty acids, into paraffinic hydrocarbons. These feedstocks 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 for certain specific feedstocks.Among the feedstocks that can be converted by the process according to the present invention, the following 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 feedstocks.

[0057] 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.

[0058] All these feedstocks contain high levels of oxygen, as well as, in highly variable amounts depending on the origin of the feedstocks, significant quantities of impurities that may contain at least one heteroatom other than oxygen, and organic impurities consisting primarily of nitrogen. These feedstocks generally contain a content of non-oxygen heteroatom compounds ranging from 0.1 to 2500 ppm. The nitrogen and sulfur contents are generally less than 100 ppm by weight, but can reach up to 1% by weight in certain feedstocks.

[0059] The feedstocks from renewable sources used in the process according to the invention may advantageously be crude, or have undergone at least one oil refining step 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, after this treatment, still contain up to 20 ppm of phosphorus, calcium, magnesium, iron and / or zinc. in the form of phospholipids.

[0060] In one embodiment, the presence of fossil-based feedstocks is excluded in order to produce only renewable-based cuts for the steam cracking step. Operating conditions and catalysts

[0061] Hydrotreatment step a)

[0062] The process according to the invention comprises a step a) of hydrotreating in the presence of hydrogen and at least one fixed-bed hydrotreating catalyst, operated at a temperature between 280 and 410°C, preferably between 290 and 320°C, and at a relative pressure between 2.0 and 13.0 MPa, preferably between 2.5 and 9.0 MPa, and at a volumetric hourly (WH) rate between 0.3 and 5 h1, preferably between 0.7 and 3 h1, and obtaining a hydrotreated effluent.

[0063] In one embodiment, said hydrotreating catalyst includes a conventional hydrogenating function.

[0064] Advantageously, the hydrotreating 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).

[0065] Advantageously, a catalyst comprising, for example, 0.5 to 10 wt% nickel (expressed as nickel oxide NiO) or 1 to 30 wt% molybdenum, preferably 5 to 25 wt% molybdenum (expressed as molybdenum oxide MoO3) on an alumina support may be used. The total content of metal oxides from groups 6 and 9 or 10 in the catalyst is generally between 5 and 40 wt% and preferably between 7 and 35 wt%. Where applicable, the weight ratio (expressed on the basis of metal oxides) between group 6 metal(s) and group 9 or 10 metal(s) is generally about 20 to about 1, and most often about 10 to about 2.

[0066] Advantageously, the various catalysts mentioned above can also be stacked in successive layers. One stacking arrangement could be, for example, a layer comprising nickel, cobalt, and molybdenum (CoNiMo), followed by a layer comprising nickel and molybdenum (NiMo), or vice versa. Another stacking arrangement could be, for example, a layer comprising cobalt and molybdenum (CoMo) followed by a layer comprising nickel and molybdenum (NiMo), or vice versa.

[0067] Advantageously, the hydrotreating catalyst is supported at least partially, or even entirely, on an alumina support.

[0068] In one embodiment, step a) of hydrotreatment is carried out with a ratio hydrogen on hydrocarbon between 100 and 5000 Nm3 / Sm3, preferably between 150 and 1000 Nm3 / Sm3.

[0069] The hydrogen-to-hydrocarbon ratio is defined here as the ratio of the volumetric flow rate of hydrogen taken under normal temperature and pressure conditions to the volumetric flow rate of feed that feeds step a) (in normal m3, noted Nm3, of H2 per standard m3 noted Sm3 of feed entering step a).

[0070] In one embodiment, step a) of hydrotreating is carried out at a minimum partial pressure of hydrogen of 2.0 MPa, preferably at least 4.0 MPa.

[0071] This step a) of hydrotreating advantageously makes it possible to produce a hydrocarbon cut whose oxygen and nitrogen compound contents are reduced.

[0072] In one embodiment, step a) of hydrotreating is followed by an optional high-temperature separation step, between 280 and 410°C, preferably between 290 and 320°C, of ​​the hydrotreated effluent, obtaining at least one gaseous effluent rich in hydrogen, oxygenated compounds and light hydrocarbons, and one liquid effluent. "Rich in hydrogen" here means a hydrogen content greater than 65% by volume.

[0073] In one embodiment, a portion of the liquid effluent obtained in the optional high-temperature separation step is recycled to step a) of hydrotreatment. This recycling advantageously allows control of the temperature increase due to the hydrotreatment reaction.

[0074] The portion of the non-recycled liquid effluent and the hydrogen-rich gaseous effluent from step a) are sent to the next step b) of hydrocracking.

[0075] 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 recycled portion of the effluent and the fresh feed introduced into the hydrotreatment step a) is less than 3, preferably less than 1.

[0076] Advantageously, the reactor configuration capable of carrying out the reactions according to the invention comprises a suitable number of catalyst beds. Generally, the configuration includes at least 2 catalyst beds and preferably more than 3, and in particular more than 4 beds but fewer than 20 beds, and preferably fewer than 15 beds, and in particular fewer than 10 catalyst beds. The preferred configuration comprises between 3 and 19 beds, and in particular comprises between 4 and 9 catalyst beds.

[0077] Step b) of hydrocracking

[0078] 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 between 280 and 410°C, preferably between 290 and 320°C, operated at a pressure between 2.0 MPa and 13.0 MPa, preferably between 2.5 and 9.0 MPa, and at a WH between 0.5 and 1001, preferably between 1 and 4 h1, and obtaining a hydrocracked effluent.

[0079] In the process according to the invention, the hydrocracking step is carried out immediately after the hydrotreating step, optionally with an intermediate high-temperature, high-pressure separation step, so that the pressure and temperature loss is minimized with a minimal number of pieces of equipment. High temperature is understood to mean a temperature between 150°C and 410°C, preferably between 200°C and 320°C. High pressure is understood to mean 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 related to the successive pieces of equipment.

[0080] In the embodiment where step a) of hydrotreating is followed by a high temperature separation step, it is the non-recycled part of the liquid effluent and the hydrogen-rich gaseous effluent that are hydrocracked in step b).

[0081] In one embodiment, step b) of hydrocracking is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 NmVSm3, preferably between 200 and 2000 NmVSm3.

[0082] Advantageously, in step b), the conversion per pass to 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 with respect to the feed entering step b) using the following operation: (the flow rate by weight of the effluent entering step b) less the flow rate of the optional bottom cut from the fractionation in step e) by weight) divided by the flow rate by weight of the effluent entering step b). Thus, the hydrocracking step b) advantageously produces naphtha and the quantity of LPG produced is minimal.

[0083] Advantageously, the overall conversion of the fresh feed to naphtha is between 80% and 100%, preferably between 95% and 100%, more preferably between 99% and 100%, in particular 100%. The overall conversion is calculated with respect to the feed entering step b) using the following operation: (the weight flow rate of the effluent entering step b) less the weight flow rate of the purged portion of the heavy cut) divided by the weight flow rate of the effluent entering step b).

[0084] In one embodiment, step b) of hydrocracking is carried out at a minimum partial pressure of hydrogen of 2.5 MPa.

[0085] The operating conditions of the hydrocracking step b) are advantageously adjusted to maximize naphtha production 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 catalytic bed (WABT or "Weighted Average Bed Temperature" in English). The hydrocracking temperature is advantageously determined based on the catalytic systems, the equipment used, and their configuration. For example, the average temperature of the catalytic bed (or WABT) is calculated as follows:

[0086] WABT = (Input + Output) / 2

[0087] with Tinlet: the inlet temperature of the catalyst bed of the hydrocracking reaction section, and Toutlet: the effluent temperature at the outlet of the catalyst bed of the hydrocracking reaction section.

[0088] The hourly volumetric velocity (WH) is defined here as the ratio between the hourly volumetric flow rate of the hydrocarbon cut feeding step b) per volume of catalysts).

[0089] Advantageously, the hydrogen used in step b) of hydrocracking can come from a hydrogen boost and / or recycled hydrogen from in particular from step c) of separation, preferably after purification, and / or from a hydrogen-rich gaseous effluent from step a).

[0090] At least one hydrocracking catalyst should advantageously be a bifunctional catalyst, having a hydrogenating phase to hydrogenate impurities and achieve equilibrium between saturated compounds and the corresponding olefins, and an acidic phase to promote hydroisomerization and hydrocracking reactions. The acidic function is provided by large surface area supports (generally 100 to 800 m².g*) exhibiting surface acidity, such as halogenated aluminas (particularly chlorinated or fluorinated), 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 usable in step b) of hydrocracking, these catalysts are described in particular in documents FR2819430, FR2846574, FR2875417, FR2863913, FR2795341, FR2795342 and FR2984760.

[0091] Advantageously, a catalyst comprising 0.5 to 10 wt% nickel (expressed as nickel oxide NiO) or 1 to 30 wt% molybdenum, preferably 5 to 25 wt% molybdenum (expressed as molybdenum oxide MoO3) or 1 to 40 wt% tungsten (expressed as tungsten oxide WO3) on the support in question, may be used, for example. The total metal oxide content of the The concentration of group 6 and 9 or 10 metals in the catalyst is generally between 5 and 40 wt% and preferably between 7 and 35 wt%. Where applicable, the weight ratio (expressed on the basis of metal oxides) between group 6 metal(s) and group 9 or 10 metal(s) is generally about 20 to about 1, and most often about 10 to about 2.

[0092] In one embodiment, commercial catalysts can be used, among others and depending on the characteristics of the load and the desired performance, such as HDK776, HDK766, HYK732, HYK752, HYK762, HYK742, HYK743 marketed by the company AXENS, for example.

[0093] In the case where said catalyst includes 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.

[0094] A preferred catalyst comprises, and is preferably made up of, at least one metal from column 6 and optionally at least one metal from columns 9 and 10 non-noble, at least one promoting element, preferably phosphorus, at least one zeolite Y and at least one alumina binder.

[0095] An even more preferred catalyst comprises, and is preferably made up of, nickel, molybdenum, phosphorus, a USY zeolite, and possibly also a beta zeolite, and alumina.

[0096] Another preferred catalyst comprises, and is preferably made up of, nickel, tungsten, alumina and silica-alumina.

[0097] Another preferred catalyst comprises, and is preferably made up of, nickel, tungsten, USY zeolite, alumina and silica-alumina.

[0098] In a particular embodiment, said hydrocracking catalyst is in extruded form.

[0099] 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 "additized catalyst." Generally, the organic compound is chosen from among compounds having one or more chemical functionalities selected from among a carboxyl group, alcohol, thiol, thioether, sulfone, sulfoxide, ether, aldehyde, ketone, ester, carbonate, amine, nitrile, imide, oxime, urea, and amide, or compounds including a furan ring, or sugars.

[0100] According to one embodiment, this step b) of hydrocracking makes it possible to produce a naphtha-type cut advantageously very paraffinic, the paraffin content of which is typically greater than 90% by weight, preferably greater than 95% by weight.

[0101] Preferably, the naphtha produced in step b) consists of paraffinic compounds and any other non-paraffinic compounds contained in the filler

[0102] Advantageously, the reactor configuration capable of carrying out the reactions according to the invention comprises a suitable number of catalyst beds. Generally, the configuration includes at least 2 catalyst beds and preferably more than 3, and in particular more than 5 beds, but fewer than 20 beds and preferably fewer than 15 beds, and in particular fewer than 10 catalyst beds. The preferred configuration comprises between 2 and 19 beds, and in particular between 3 and 9 catalyst beds.

[0103] Step c) of separation

[0104] The process according to the invention includes a step c) of separating the hydrocracked effluent obtained in step b), and obtaining at least one gaseous effluent comprising hydrogen and a hydrocarbon liquid effluent.

[0105] 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 further obtained.

[0106] The separation section of step c) is advantageously carried out in separation equipment well known to those skilled in the art (separating vessels capable of operating at different pressures and temperatures, pumps, heat exchangers, etc.).

[0107] In one embodiment, the separation step c) is followed by a purification and / or washing step 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 the hydrotreating and / or hydrocracking step a) and / or the hydrocracking step b). This step is intended to ensure hydrogen coverage and exothermic control in step a) and / or step b).

[0108] Typically, a small part of the gaseous effluent may optionally be purged to prevent the accumulation of oxygenated compounds and light compounds towards the fuel gas network or towards a hydrogen recovery unit.

[0109] 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 for exothermic control and reduces the flow rate of the first recycling 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 for control of the conversion in step b) and the overall conversion of the fresh feed.

[0110] Step d) of stripping

[0111] The process according to the invention includes a step d) of stripping the hydrocarbon liquid effluent obtained in step c), and obtaining at least one off-gas cut, and a stripped liquid effluent.

[0112] Step d) makes it possible in particular to remove gases dissolved in the hydrocarbon liquid 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.

[0113] In one embodiment, the off-gas cut is sent, after an optional washing step, in whole or in part to step f) of steam cracking, separately or mixed with the naphtha cut obtained in step e), in one or more furnaces of step f) of steam cracking, allowing this cut to be valorized into bio-based olefins.

[0114] In one embodiment, the off-gas cut obtained in step d) is sent to a separation step in order to recover at least one depropane-depleted off-gas cut low in propane and butane and one LPG cut. This separation step can advantageously be carried out in separation columns.

[0115] In one embodiment, the LPG cut is sent to step f) of steam cracking, separately or mixed with the naphtha cut obtained in step e), in one or more furnaces of step f) of steam cracking, allowing this cut to be valorized into bio-based olefins.

[0116] In one embodiment, the depropanized off-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), allowing this cut to be valorized into bio-based olefins.

[0117] In another embodiment, the depropanized off-gas cut low in propane and butane and / or the LPG cut is sent to a steam reformer stage to obtain bio-based hydrogen.

[0118] 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 including a reflux flask. Said stripping column is advantageously fed by the liquid effluent from step c) and by a steam stream. Said column can also be reboiled by a furnace or a heat exchanger. The liquid effluent from step c) can optionally be preheated before entering the stripping column.

[0119] Thus, the lighter compounds are carried to the top of the column and into the reflux circuit, which includes a reflux flask in which gas / liquid separation takes place. The gaseous phase, which includes the light hydrocarbons, is withdrawn from the reflux flask as a gaseous stream. The stripped liquid hydrocarbon effluent is advantageously stabilized and withdrawn from the bottom of the stripping column.

[0120] According to one embodiment, a liquid LPG cut can be recovered at the level from the reflux flask and then stabilized in a stabilization column. The stabilized GLP liquid cut is sent to the GLP cut obtained in the off-gas cut separation step.

[0121] According to one embodiment, a light naphtha cut can be recovered from the reflux flask and then stabilized in a stabilization column. The stabilized light naphtha cut is sent to the naphtha cut obtained in the fractionation step f).

[0122] According to one embodiment, the stripping step (d) can be carried out on a portion of the hydrocarbon liquid effluent obtained in step (c), the other portion being fed directly to the fractionation step (d), thus obtaining at least one off-gas cut and a stripped liquid effluent which is sent to the fractionation step. In this embodiment, a portion of the stripping step (d) is carried out within the fractionation step.

[0123] According to another embodiment, the stripping step d) is integrated into the splitting step e) and the person skilled in the art can, using the same splitting section comprising one or more columns, obtain the different flows described in these two steps.

[0124] Step e) of splitting

[0125] The process according to the invention includes a step e) of fractionating the stripped liquid effluent obtained in step d), and obtaining at least one paraffin-rich naphtha cut.

[0126] In one embodiment, in step e) of fractionation of the stripped liquid effluent obtained in step d), a heavy cut comprising hydrocarbon compounds having boiling points above 150°C, preferably above 175°C, is further obtained.

[0127] In a particular embodiment, the resulting heavy cut 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.

[0128] In one embodiment, the heavy cut is recycled in whole or in part to the step a) of hydrotreating and / or b) of hydrocracking, preferably with a recycled feed / fresh feed ratio 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.

[0129] Advantageously, a small part of the heavy cut is purged, continuously or intermittently, before it is sent to step a) and / or b). The person skilled in the art adjusts the amount purged to remove the compounds that cannot be cracked and that have accumulated in the reaction loop.

[0130] Advantageously, the quantity of recycled heavy cutting material is adjusted so that the The weight ratio between the recycled stream and the fresh feedstock supplying 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 preferably greater than or equal to 0.1. Most preferably, the quantity of recycled stream is adjusted so that the weight ratio between the recycled stream and the fresh feedstock is between 0.2 and 5, preferably between 0.3 and 2.0, and even more preferably between 0.5 and 1.5.

[0131] Depending on the charges treated, this recycling advantageously allows on the one hand the dilution of impurities and on the other hand the control of the temperature in the reaction step(s) a) and / or b), in which reactions involved may be strongly exothermic.

[0132] The fractionation step advantageously includes at least one main fractionation column, allowing the separation of a head fraction and a heavy fraction, said fractions comprising the different products of the units.

[0133] Step e) of fractionation 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.

[0134] In one embodiment, all the cuts from the process are recovered as renewable products.

[0135] The naphtha cut is sent at least in part, preferably in whole, to a steam cracking unit f), allowing this cut to be valorized into bio-based olefins.

[0136] Step f) of steam cracking

[0137] The process according to the invention includes 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 bio-based gaseous effluent comprising ethylene and propylene.

[0138] In one embodiment, the off-gas cut obtained in step d) is also treated in step f) of steam cracking, either separately from the naphtha cut or in co-treatment.

[0139] In one embodiment, the LPG cut obtained after an optional separation step from the off-gas cut obtained in step d) is also treated in step f) of steam cracking, either separately from the naphtha cut or in co-treatment.

[0140] In one embodiment, the propane- and butane-poor depropanized off-gas cut obtained after an optional separation step from the off-gas cut obtained in step d) is also treated in step f) of steam cracking, either separately from the naphtha cut or in co-treatment.

[0141] 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 steam, of saturated hydrocarbons from natural gas or naphtha in the presence of steam, in order to produce unsaturated hydrocarbon fractions ali phatic or aromatic. These fractions 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, step f) of steam cracking makes it possible to produce renewable aliphatic unsaturated hydrocarbons (of bio-based origin).

[0142] Advantageously, the steam cracking step f) processes the naphtha cut and / or the LPG cut in the scheme and suitable operating conditions known to the person skilled in the art.

[0143] Advantageously, the steam cracking unit processes the naphtha and / or LPG cut in the optional presence of an external feed of naphtha and / or LPG.

[0144] Advantageously, the residence time in the steam cracking furnace is limited to minimize the formation of heavy products. Furthermore, a quenching process is implemented to stabilize the effluent composition upon exiting the furnace.

[0145] Advantageously, the temperature at which steam cracking furnaces are operated depends on the nature of the feedstock. Preferably, steam cracking furnaces are adapted to process a naphtha-type feedstock.

[0146] In the various embodiments of the process according to the invention, the feedstocks in the steam cracking stage may include external feedstocks, corresponding to dedicated furnaces or furnaces shared with the furnaces processing the feedstocks produced by the stages of the process according to the invention. These external feedstocks may vary and range from light saturated hydrocarbons such as ethane, propane, or ethane-propane mixtures, to heavier or lighter petroleum fractions such as petrochemical naphtha. The nature of the feedstocks processed will depend on the types of furnaces installed.

[0147] Advantageously, the steam cracking step is implemented in an installation comprising several 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 and then mixed with steam, also preheated in the same zone. The hydrocarbons and water then pass through the actual radiation zone of the furnace, where the rapid temperature rise and pyrolysis reactions take place. At the furnace outlet, to prevent any further reaction, the effluents are stopped from developing further by a rapid quenching process, generally carried out in two stages: first, an 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 withdrawals, a fraction of the steam cracking gasoline and water, while the light pyrolysis products exit at the top in gaseous form.

[0148] After compression, washing with caustic soda (intended to remove H2S and acid gases) and After 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 be brought up to 99.5% (by mass), a C4 cut, and the additional fraction of steam cracking gasoline rich in aromatic hydrocarbons (more than 50% by weight of aromatic compounds). DESCRIPTION OF THE FIGURES

[0149] [Fig. [1] A vegetable oil feedstock 111 is fed into a hydrotreating 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 a USY NiMo zeolite-type catalyst to obtain a hydrocraced effluent 115. The hydrocraced 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 off-gas 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 naphtha-rich cut in paraffins 121.The naphtha cut 121 is sent to a steam cracking step f) to produce the effluent 122 rich in ethylene, propylene and bio-based light olefins. In this embodiment, the process does not produce a heavy cut comprising compounds having boiling points above 150°C.

[0150] [Fig.2]: A charge of vegetable oil 211 is fed in a step hydrotreating 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 followed immediately 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 hydrotreating step a) to control and reduce the exothermic reaction in the reactor during this step. The non-recycled portion of the liquid effluent 213 is mixed with the gaseous effluent 223 and then sent to a hydrocracking step b) in the presence of hydrogen included in the gaseous effluent 223, as well as in the presence of a hydrogen-rich stream 214 and a USY-type zeolite hydrocracking catalyst, to obtain a hydrocraced effluent 215.The hydrocracked effluent 215 is sent to a separation step c) to obtain at least one gaseous effluent 216 comprising hydrogen and one liquid effluent. The gaseous effluent 216 is optionally sent to a step . The effluent is washed to remove contaminants and recycled to stage a) hydrotreating and / or stage b) hydrocracking. A portion of the liquid effluent 225 may optionally be recycled to stage a) hydrotreating and / or b) hydrocracking to control and reduce the exothermic reaction in the reactor of these stages. The non-recycled portion of the liquid effluent 217 is sent to a stripping stage 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 may optionally be sent to stage f) steam cracking.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 with a boiling point above 150°C, which is recycled to hydrotreating and / or hydrocracking steps a) and / or b) for further conversion. The naphtha cut 221 is sent to a steam cracking step f) to produce the effluent 222 rich in bio-based ethylene, propylene, and light olefins. EXAMPLES

[0151] Example 1: Process for treating a feedstock from a renewable source according to the invention

[0152] The characteristics of the rapeseed oil charge used are presented in the following table:

[0153] [Tables 1] Density at 15°C (kg / m³) 923.5 Oxygen (% by weight) 11 Hydrogen (% by weight) 11.4 Sulfur (ppm by weight) 3 Nitrogen (ppm by weight) 13 Phosphorus (ppm by weight) <1 Magnesium (ppm by weight) <1 Calcium (ppm by weight) <1 Sodium (ppm by weight) <1

[0154] The operating conditions in the hydrotreating section are presented in the following table:

[0155] [Tables2] Mass flow rate of the feedstock: 100 t / h; Pressure: 5.5 MPa; WH: 1 h1; Catalyst: NiMo; Temperature: 290 °C; Hydrogen-to-hydrocarbon ratio: 1000 NmVSm3; Mass ratio between the recycled effluent obtained after the high-temperature, high-pressure separation stage and the fresh feedstock: 0.7; Performance: Oxygenation rate of oxygenated material: 99.9%; Mass flow rate of hydrotreated oil: 89.5 t / h; Density of hydrotreated oil (kg / m3): 790

[0156] The operating conditions in the hydrocracking (HCK) step are presented in the following table:

[0157] [Tables3] Pressure 6.0 MPa WH 4 h1 Catalyst NiMo USY WABT 300 °C Hydrogen to hydrocarbon ratio 1000 Nm3 / Sm3 Conversion per pass 50% by weight Overall conversion (HCK reactor inlet-purge) / (HCK reactor inlet) 99.9% by weight Recycled heavy cutting flow rate / fresh feed flow rate (by weight) 1.1

[0158] The overall result of the process is presented in the following table:

[0159] [Tables4] t / h Charge 100.0 h2 4.3 Total 104.3 Products (t / h) Water 10.5 Offgas (C1, C2 and impurities) 0.2 LPG Cut 15.3 Naphtha 76.0 Purge 0.1 co-co2 2.2 Total 104.3

[0160] The properties of naphtha with a cutting point of C5-175°C are as follows:

[0161] - Paraffin filler: paraffin content greater than 99% by weight

[0162] - Density 677 kg / m3

[0163] - Sulfur <1 ppm by weight

[0164] - Nitrogen <1 ppm by weight

[0165] - Oxygen content <0.1% by weight

[0166] These properties make it a choice feedstock for the production of ethylene and propylene because it is very rich in paraffins.

[0167] The bio-based naphtha feed obtained is sent to the steam cracker at a flow rate of 76 t / h. This paraffin-rich feed produces high yields of bio-based ethylene and propylene, at least 65% of the feed entering the steam cracker.

[0168] The LPG cut and / or the off-gas cut can also be sent to the steam cracker.

[0169] The process according to the invention thus makes it possible to produce almost exclusively naphtha and an LPG fraction, unlike prior art processes. Furthermore, the process is implemented in a minimum number of pieces of equipment, since the hydrotreating and hydrocracking steps are carried out consecutively without a separation step.

Claims

Demands

1. Process for treating a feedstock from a renewable source essentially composed of triglycerides and fatty acids, said process comprising the steps of: a) a hydrotreating step in the presence of hydrogen and at least one fixed-bed hydrotreating catalyst, operated at a temperature between 280 and 410°C, and at a relative pressure between 2.0 and 13.0 MPa, and at an hourly volumetric velocity between 0.3 and 5 h', and obtaining a hydrotreated effluent; b) a hydrocracking step of 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 velocity between 0.5 and 1001, and obtaining a hydrocraced 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 part, preferably all, of the naphtha cut obtained in step e) and obtaining at least one bio-based gaseous effluent comprising ethylene and propylene.

2. A process according to claim 1, wherein step a) of hydrotreating is carried out with a hydrogen to hydrocarbon ratio between 100 and 5000 Nm3 / Sm3.

3. A process according to any one of the preceding claims, wherein at least one hydrotreating 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).

4. A process according to any one of the preceding claims, wherein the hydrotreating step a) is followed by a high-temperature separation step of between 280 and 410°C, and high-pressure separation step of between 2.0 and 13.0 MPa, of the hydrotreated effluent, and obtaining at least one gaseous effluent and one liquid effluent.

5. A process according to claim 4, wherein a portion of the liquid effluent obtained in the high-temperature separation step is recycled to step a) of hydrotreatment.

6. A process according to any one of the preceding claims, wherein the hydrocracking step b) is carried out with a hydrogen to hydrocarbon ratio of between 100 and 5000 NmVSm3.

7. A process according to any one of the preceding claims, wherein step b) of hydrocracking is carried out at a minimum partial pressure of hydrogen of 2.5 MPa.

8. A process according to any one of the preceding claims, wherein at least one hydrocracking catalyst comprises a hydrogenating function and an acid function provided by large surface supports exhibiting surface acidity, such as halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and Y, Beta and ZSM-5 zeolites.

9. A process according to any one of the preceding claims, wherein in step b) the per-pass conversion to hydrocarbon compounds is between 20 and 100% by weight.

10. A process according to any one of the preceding claims, wherein step c) of separation 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 hydrotreating and / or b) of hydrocracking.

11. 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).

12. 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 cut low in propane and butane and an LPG cut.

13. The method according to claim 12, wherein the LPG cut is sent to step f) of steam cracking, separately or mixed with the naphtha cut obtained in step e), in one or more furnaces of step f) of steam cracking.

14. A process according to any one of the preceding claims, wherein in step e) of fractionation of the stripped liquid effluent obtained in step d), a heavy cut comprising hydrocarbon compounds having boiling points above 150°C, preferably above 175°C, is further obtained.

15. A process according to claim 14, wherein the heavy cut obtained in step e) is wholly or partly recycled to step a) of hydrotreating and / or b) of hydrocracking, preferably with a recycled feed / fresh feed ratio between 0 and 4.

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