EP4334412A1 - Optimized process for the hydrotreating and hydroconversion of feedstocks derived from renewable sources - Google Patents

Abstract

The present invention describes a process for treatment of a feedstock derived from a renewable source, comprising a step a) of hydrotreating said feedstock, a step b) of separation into at least one light fraction and at least one hydrocarbon-based liquid effluent, a step c) of removal of at least one portion of the water from the hydrocarbon-based liquid effluent, a step d) of hydroconversion of at least one portion of the hydrocarbon-based liquid effluent, said hydroconversion step d) being characterized firstly by the use of a bifunctional catalyst comprising a molybdenum and/or tungsten sulfide phase promoted with nickel and/or cobalt, and secondly by a ratio between the partial pressure of hydrogen sulfide and of hydrogen at the inlet of the hydroconversion unit of less than 5x10-5 and a step e) of fractionation of the effluent from step d) to obtain at least one middle distillate fraction.

Description

OPTIMIZED PROCESS FOR HYDROTREATMENT AND HYDROCONVERSION OF CHARGES FROM RENEWABLE SOURCES

Field of the invention

The search for new sources of renewable energy for the production of fuels is a major challenge in order to both meet the demand for fuel and take into account concerns related to the environment.

In this respect, the recovery of feedstocks from renewable sources into fuels has experienced a very strong resurgence of interest in recent years. Among these fillers, mention may be made, for example, of vegetable oils, animal fats, raw or having undergone a prior treatment, as well as mixtures of such fillers. These fillers contain chemical structures of the triglyceride or ester or fatty acid type, the structure and the length of the hydrocarbon chain of the latter being compatible with the hydrocarbons present in gas oils and kerosene.

One possible route is the catalytic transformation of the charge from a renewable source into deoxygenated paraffinic fuel in the presence of hydrogen (hydrotreating). Many metal or sulphide catalysts are known to be active for this type of reaction.

These processes for hydrotreating feed from a renewable source are already well known and are described in numerous patents. Mention may be made, for example, of the patents: US 4,992,605, US 5,705,722, EP 1,681,337 and EP 1,741,768.

The use of solids based on transition metal sulphides allows the production of paraffins from ester-type molecules according to two reaction pathways:

- hydrodeoxygenation leading to the formation of water by consumption of hydrogen and the formation of hydrocarbons with a carbon number (C _n ) equal to that of the initial fatty acid chains,

- decarboxylation/decarbonylation leading to the formation of carbon oxides (carbon monoxide and dioxide: CO and CO2) and to the formation of hydrocarbons with one less carbon (C _n -i) compared to the acid chains bold initials.

The liquid effluent resulting from these hydrotreating processes, after separation, essentially consists of n-paraffins and is substantially free of sulfur, nitrogen and oxygen impurities. After hydrotreating and gas separation, the sulfur content is typically between 1 and 20 ppmw, the nitrogen content is typically between 0.2 and 30 ppmw, and the oxygen content is typically less than 2000 ppm weight. Paraffins have a number of carbon atoms typically between 9 and 25, which is mainly dependent on the composition of the charge to be hydrotreated.

However, this liquid effluent cannot generally be incorporated as such into the kerosene or diesel pool, in particular because of insufficient cold properties and/or too high boiling temperatures. Indeed, the paraffins present lead to high pour points and therefore to congealing phenomena for uses at low temperatures. For example, eicosane (linear paraffin with 20 carbon atoms, C20H42) has a boiling point of 340°C and a melting point of 37°C. The boiling point of eicosane is thus compatible with incorporation into a diesel pool, but its melting point can cause freezing problems and limit its use. By way of illustration, the filterability limit temperature for winter diesel is a maximum of -15°C. Moreover, the boiling point of eicosane means that it cannot be incorporated into the kerosene pool, for which the final temperature of the distillation curve must be less than 300°C.

Depending on the incorporation rate and the preferred fuel pool (diesel or kerosene) targeted, it may be necessary to carry out a hydroconversion step (hydroisomerization and/or hydrocracking reactions) to transform the linear paraffins of the hydrotreated liquid effluent. Hydroisomerization makes it possible to convert a linear paraffin into a branched paraffin with conservation of the number of carbon atoms in the molecule. This makes it possible to improve the cold properties of the effluent since branched paraffins have better cold properties than linear paraffins. For example nonadecane has a melting point of 32°C while one of its monobranched isomers, 7-methyl-octadecane has a melting point of -16°C. Hydrocracking makes it possible to convert a linear paraffin into linear or branched paraffins of lower molecular weight. This makes it possible to adjust the distillation curve of the effluent if necessary to make it compatible with the kerosene pool. By way of illustration, the hydrocracking of one molecule of eicosane can lead to the production of two molecules of 2-methylnonane. The boiling point of 2-methylnonane is 167°C, which is compatible with incorporation into the kerosene pool. The hydroconversion step is carried out on a bifunctional catalyst having both a hydro/dehydrogenating function and a Bronsted acid function. The operating conditions can be adapted to promote the hydroisomerization or hydrocracking reactions as required. In all cases, it is desirable to minimize the production of cracking products that are too light to be incorporated into the kerosene or gas oil pool. The appropriate choice of the acid phase makes it possible to promote the isomerization of long linear paraffins and to minimize cracking. Thus the shape selectivity of one-dimensional zeolites with medium pores (10 MR) such as ZSM-22, ZSM-23, NU-10, ZSM-48, ZBM-30 zeolites makes their use particularly suitable for obtaining catalysts that are selective towards isomerization. Other acid phases of the zeolitic or non-zeolitic type such as halogenated aluminas (chlorinated or fluorinated in particular), phosphorus-containing aluminas, silica-aluminas or even siliceous aluminas can also be used.

However, it is well known that factors other than the acid phase have an impact on the activity and selectivity of a bifunctional catalyst. The hydroisomerization and hydrocracking of normal paraffins have thus been the subject of many academic studies since the original work of the sixties by Weisz or Coonradt and Garwood. The most commonly accepted mechanism involves first of all that the n-paraffin is dehydrogenated into n-olefin on the hydro-dehydrogenating phase and then, after diffusion towards the acid phase, that it is protonated into the carbenium ion. After structural rearrangement and/or b-scission, the carbenium ions desorb from the acid phase in the form of olefins after deprotonation. Then, after diffusion to the hydro-dehydrogenating phase, the olefins are hydrogenated to form the final reaction products. It is then necessary to have a hydro/dehydrogenating function that is sufficiently active with respect to the acid function in order, on the one hand, to quickly supply the acid phase with olefins and, on the other hand, to quickly hydrogenate the olefinic intermediates after their reaction on the acid phase. This makes it possible on the one hand to maximize the activity of the catalyst and on the other hand to promote hydroisomerization compared to hydrocracking when the first reaction is desired, or to limit the production of too light cracking products when the reaction hydrocracking is desired. The use of a sufficiently active hydrogenating function is also desirable in order to limit the deactivation of the bifunctional catalyst by coking during the hydroconversion of n-paraffins (Alvarez et al., Journal of Catalysis, 162, 2, 179-189) for a range of fixed operating conditions.

Noble metals (Pt, Pd) or group VIA transition metals (Mo, W) combined with group VIII transition metals (Ni, Co) can play the role of hydrogenating function for the catalyst. Noble metals are used in their reduced form while transition metals are used in a sulphide form. For the latter, there is a known synergistic effect between Group VIA transition metals and Group VIII transition metals, generally attributed to decoration of Group VIA sulfide phases by Group VIII transition metals. We then speak of molybdenum or tungsten sulphide phase promoted by nickel or cobalt (“CoMoS”, “NiMoS”, “NiWS”). This effect synergy results in an increase in the catalytic activity of the promoted phase compared to an unpromoted phase.

The choice of the nature of the hydrogenating function, of the noble metal or sulphide type, depends on various criteria, of an economic nature (the price of the noble metals is significantly higher than that of the transition metals of groups VIA and VIII) or of chemical nature (impact of the presence of contaminants). Thus, the hydrogenating activity of noble metals is higher than that of transition metal sulphides when the partial pressure of hydrogen sulphide (H ₂ S) in the reaction medium is low or even zero. Conversely, the hydrogenating activity of transition metal sulfides is higher than that of noble metals when the partial pressure of H ₂ S in the reaction medium becomes high (C. Marcilly, Catalyse acido-basique, volume 2, 2003, editions Technip). Furthermore, it is reported that the use of transition metal sulphides requires the presence of H ₂ S in the reaction medium to ensure their stability, and in particular the maintenance of the promotion of the molybdenum or tungsten sulphide phases by nickel. or cobalt under reaction conditions. Maintaining the promotion is desirable in order to retain the synergistic effect and to have maximum activity of the sulphide phase. For example, in the toluene hydrogenation molecule test, a catalyst based on a nickel-promoted tungsten sulphide phase (“NiWS”) on silica-alumina exhibits an activity per tungsten atom 16 times greater than that of a catalyst based on non-nickel promoted tungsten sulfide (“WS”) on silica-alumina (M. Girleanu et al., ChemCatChem 2014, 6, 1594-1598). Maintaining the promotion depends on the operating conditions under which the catalyst works. Studies combining molecular modeling by DFT and thermodynamic model thus make it possible to propose diagrams of stability of the phases promoted according to a thermodynamic quantity called chemical potential in sulfur. The value of the chemical sulfur potential is itself calculated from the temperature of the medium and the ratio between the partial pressures of hydrogen sulphide (H ₂ S) and hydrogen (H ₂ ) and is available in the form of an abacus ( C. Arrouvel et al., Journal of Catalysis 2005, 232, 161-178). The chemical potential of sulfur decreases when the temperature increases, and when the ratio between the partial pressures of hydrogen sulphide and hydrogen decreases. It is thus possible to evaluate the thermodynamic stability of the promoted phases as a function of the operating conditions. Thus, it is reported that the NiWS phase is no longer thermodynamically stable (complete nickel segregation and loss of promotion) for sulfur chemical potential values below -1.27 eV.

In the field of the hydroconversion of long paraffins (waxes), resulting from the Fischer-Tropsch synthesis, on sulphide bifunctional catalysts of the NiMoS or NiWS type on silica-alumina, D. Leckel (Energy & Fuels 2009, 23, 5- 6, 2370-2375) reports that the H ₂ S content in the gas leaving the unit must be at least 100 ppm and preferably at least 200 ppm to maintain the catalyst in its sulfurized form. The composition of the exit gas is not specified. The values provided correspond to P(H2S)/P(H2) ratios at least greater than 1.10 ^-4 and preferably at least greater than 2.10 ^-4 in the case where it is assumed that the outlet gas consists only of 'hhS and hydrogen.

Patent application FR2940144 A1 claims a process for the hydrodeoxygenation of feedstocks derived from renewables. The effluent resulting from the hydrodeoxygenation is subjected to a stage of separation and preferably a stage of gas/liquid separation and of separation of the water and of at least one liquid hydrocarbon base. After a step for eliminating nitrogenous compounds, said liquid hydrocarbon base is hydroisomerized on a bifunctional hydroisomerization catalyst. It is taught that it is possible to add a certain amount of sulfur compounds such as, for example, dimethyldisulfide to maintain the catalyst in its sulfurized form if necessary. Advantageously, the quantity of sulfur is such that the H ₂ S content in the recycle gas which is sent to the hydroisomerization stage is at least 15 ppm by volume, preferably at least 0.1% by volume and preferably at least 0.2% volume. The composition of the recycle gas is not specified. The values provided correspond to P(H2S)/P(H2) ratios at least greater than 1.5.10 ^-5 , preferably at least greater than 1.10 ^-3 and preferably greater than 2.10 ^-3 in the case where it is assumed that the recycle gas consists only of h^S and hydrogen. No examples are provided.

Patent application WO2009/156452 A1 (SHELL) claims a process for the production of paraffinic hydrocarbons from a feed containing triglycerides, diglycerides, monoglycerides and/or fatty acids. Said process comprises (a) a step of hydrodeoxygenation in the presence of hydrogen and a catalyst in order to obtain an effluent comprising water and paraffins, (b) a step of separating the effluent from ( a) to obtain a liquid effluent rich in paraffins and (c) a step of hydroisomerization of said effluent rich in paraffins in the presence of hydrogen and a catalyst comprising nickel sulphide and tungsten and/or molybdenum sulphide as hydrogenating phases and a support comprising silica-alumina and/or a zeolite. It is taught that the use of sulphide phases instead of noble metals as hydrogenating phases makes it possible not to have to completely remove the impurities from the effluent resulting from step (a). It is also taught that to maintain the hydroisomerization catalyst in its sulphide form, it is necessary to add the make-up hydrogen with hydrogen sulphide (H ₂ S) or a precursor of hydrogen sulphide such as dimethyldisulfide. No minimum hydrogen sulfide content is taught. Step (c) of the example provided uses a hydroisomerization catalyst of the NiWS/silica-alumina type. In order to keep the catalyst under its sulphide form 5000 ppm of sulfur are added to the charge in the hydroisomerization stage in the form of di-ter-butyl-polysulphide. This corresponds to a ratio between the partial pressure of H ₂ S and the partial pressure of hydrogen of 2.2×10 ^-3 at the reactor inlet after decomposition of the di-ter-butyl-polysulphide.

Patent application U S2011/0219669 A1 claims a method for producing diesel fuel comprising mixing a feed of renewable origin and a fossil feed, said mixture then being transformed in contact with a dewaxing/isomerization catalyst putting a hydrogenating function and an acid function of the zeolite type are involved. It is taught that when the hydrogenating function of said catalyst is of the sulphide type, for example NiWS, the hydrocarbon feed must contain a minimum of sulfur to maintain the hydrogenating function in its sulphide form. The minimum recommended content of sulfur (present in sulfur molecules) in the feed is at least 50 ppm by weight, preferably at least 100 ppm by weight, more preferably at least 200 ppm by weight. The decomposition of these sulfur molecules in the deparaffinization/isomerization reactor makes it possible to generate a partial pressure of H ₂ S necessary for maintaining the hydrogenating phase in its sulfide form. Alternatively, the sulfur can be supplied directly in the form of H ₂ S, for example already present in the hydrogen-rich gas stream supplying the unit.

Indeed, the hydroconversion step can use hydrogen from different sources. Depending on the nature of the different sources, the hydrogen used in the process according to the invention may or may not contain impurities. For example, a catalytic reforming unit produces hydrogen during the dehydrogenation reactions of napthenes into aromatics and during the dehydrocyclization reactions. The hydrogen produced by a catalytic reforming unit is substantially free of CO and C0 ₂ . Hydrogen can also be produced by other methods such as, for example, by the steam reforming of light hydrocarbons or else by the partial oxidation of various hydrocarbons such as heavy residues. Steam reforming consists of transforming a light hydrocarbon charge into synthesis gas, that is to say into a mixture of hydrogen (H ₂ ), carbon monoxide (CO), carbon dioxide (C0 ₂ ) , and water (H ₂ 0) by reaction with steam over a nickel-based catalyst. In this case the production of hydrogen is also accompanied by the formation of carbon oxides which are substantially eliminated by the steam conversion of carbon monoxide (CO) to carbon dioxide (C0 ₂ ), then by elimination C0 ₂ by absorption for example by a solution of amines. There can also be elimination of residual carbon monoxide (CO) by a methanation step. Other sources of hydrogen can also be used such as hydrogen from catalytic cracking gases which contains significant amounts of CO and CO2. The hydrogen used can also come from the outlet gas of a hydrotreating unit, in this case this hydrogen can undergo more or less extensive purification steps to eliminate impurities such as ammonia (NH ₃ ) or hydrogen sulfur (H ₂ S).

By attempting to develop a method for treating feedstocks from renewable sources comprising at least one hydrotreatment step and one hydroconversion step characterized by the use of a bifunctional catalyst comprising a molybdenum and/or tungsten sulphide phase in combination with at least nickel and/or cobalt, the applicant has discovered, surprisingly, that the reduction in the ratio between the hydrogen sulphide partial pressure and the hydrogen partial pressure entering the hydroconversion unit below the values usually disclosed in the prior art makes it possible to improve the performance of said hydroconversion catalyst.

An advantage of the method according to the present invention is therefore to provide a method for treating a feedstock from a renewable source which undergoes hydrotreatment before being sent to a hydroconversion step using a bifunctional catalyst comprising a phase molybdenum and/or tungsten sulfide promoted by nickel and/or cobalt, said catalyst operating under operating conditions such that the ratio between the H2S partial pressure and the hydrogen partial pressure entering said hydroconversion step is lower at 5.10 ^-5 .

An advantage of the present invention is to provide a method making it possible to obtain a gain in activity and selectivity of the hydroconversion catalyst. The implementation of the operating conditions in accordance with the invention makes it possible, all other things being equal, to reduce the temperature necessary to obtain a cold property value targeted for the middle distillate cut (measured for example by a cloud point value ). The implementation of the operating conditions in accordance with the invention also makes it possible to improve the yield in the middle distillate cut for a targeted cold property value (measured for example by a cloud point value).

In a preferred mode, an advantage of the process according to the invention is also to allow better resistance of the hydroconversion catalyst to deactivation when the operating conditions of the hydroconversion step, in particular in terms of total pressure and hydrogen ratio on load, promote deactivation.

Another advantage of the process according to the invention is also to allow better resistance of the hydroconversion catalyst to the possible presence of oxygenated compounds. Finally, in accordance with the invention, temporary operation of the hydroconversion unit under operating conditions not in accordance with the invention is not excluded. It may thus happen that the ratio between the hydrogen sulphide partial pressure and the hydrogen partial pressure is not in accordance with the invention during certain periods. For example due to occasional malfunctioning of any tools for purifying the hydrogen sent to the hydroconversion unit and/or the liquid hydrocarbon effluent from step c). In this case, the repair of any tools for purifying the hydrogen and/or the hydrocarbon effluent resulting from c) makes it possible to find an operating mode of the process in accordance with the invention.

Object of the invention

More specifically, the present invention relates to a process for treating a feed from a renewable source comprising at least: a) a step of hydrotreating said feed in the presence of a fixed-bed catalyst, said catalyst comprising a function hydrogenating agent and an oxide support, at a temperature of between 200 and 450°C, at a pressure of between 1 MPa and 10 MPa, at an hourly space velocity of between 0.1 h ¹ and 10 h ^-1 and in the presence of a total quantity of hydrogen mixed with the charge such that the hydrogen/charge ratio is between 70 and 1000 Nm ³ of hydrogen/m ³ of charge, b) a stage of separation of at least part of the effluent from step a) into at least one light fraction and at least one liquid hydrocarbon effluent, c) a step of removing at least part of the water from the liquid hydrocarbon effluent from step b ), d) a step of hydroconversion of at least a portion of the liquid hydrocarbon effluent from step c) in the presence of a bifunctional fixed-bed hydroconversion catalyst, said catalyst comprising a molybdenum and/or tungsten sulphide phase in combination with at least nickel and/or cobalt, said hydroconversion step being carried out at a temperature between 250°C and 500°C, at a pressure between 1 MPa and 10 MPa, at an hourly space velocity between 0.1 and 10 h ¹ and in the presence of a total quantity of hydrogen mixed with the charge such that the hydrogen/charge ratio is between 70 and 1000 Nm ³ /m ³ of charge, in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and hydrogen at the inlet of said hydroconversion step is less than 5.10 ^-5 , preferably less than 4.10 ⁵ , very preferably less than 3.10 ^-5 , very preferably less than 2.10 ⁵ and even more preferably less than 1 ,5.10 ^-5 . e) a step of fractionating the effluent from step d) to obtain at least one middle distillate fraction.

Detailed description of the invention

Expenses

The present invention is particularly dedicated to the preparation of gas oil and/or kerosene fuel bases corresponding to the new environmental standards, from feedstocks originating from renewable sources.

The fillers from renewable sources used in the process according to the present invention are advantageously 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. The vegetable oils can advantageously be crude or refined, totally or partly, and derived from the following plants: rapeseed, sunflower, soya, palm, palm kernel, olive, coconut, jatropha, this list not being exhaustive. Seaweed or fish oils are also relevant. The animal fats are advantageously chosen from lard or fats composed of residues from the food industry or from catering industries.

These fillers essentially contain chemical structures of the triglyceride type that those skilled in the art also know under the name fatty acid triester as well as free fatty acids. A fatty acid triester is thus composed of three chains of fatty acids. These fatty acid chains in triester form or in free fatty acid form have a number of unsaturations per chain, also called the number of carbon-carbon double bonds per chain, generally between 0 and 3 but which can be higher in particular for oils derived from algae which generally have a number of unsaturations per chain of 5 to 6.

The molecules present in the fillers from renewable sources used in the present invention therefore have a number of unsaturations, expressed per molecule of triglyceride, advantageously between 0 and 18. In these fillers, the level of unsaturation, expressed as the number of unsaturation per hydrocarbon fatty chain is advantageously between 0 and 6.

The feeds from renewable sources generally also contain various impurities and in particular heteroatoms such as nitrogen. Nitrogen contents in vegetable oils are generally between 1 ppm and 100 ppm by weight approximately, depending on their nature. Process and catalysts

Advantageously, the charge may undergo, prior to step a) of the process according to the invention, a pre-treatment or pre-refining step so as to eliminate, by an appropriate treatment, contaminants such as metals, such as alkaline compounds eg on ion exchange resins, alkaline earths and phosphorus. Appropriate treatments can for example be thermal and/or chemical treatments well known to those skilled in the art.

In accordance with step a) of the process according to the invention, the charge, optionally pretreated, is brought into contact with a catalyst in a fixed bed at a temperature of between 200 and 450° C., preferably between 220 and 350° C. , preferably between 220 and 320°C, and even more preferably between 220 and 310°C. The pressure is between 1 MPa and 10 MPa, preferably between 1 MPa and 6 MPa and even more preferably between 1 MPa and 4 MPa. The hourly space velocity, ie the volume of charge per volume of catalyst and per hour is between 0.1 h ¹ and 10 h ¹ . The charge is brought into contact with the catalyst in the presence of hydrogen. The total quantity of hydrogen mixed with the charge is such that the hydrogen/charge ratio is between 70 and 1000 Nm ³ of hydrogen/m ³ of charge and preferably between 150 and 750 Nm ³ of hydrogen/m ³ load.

In step a) of the process according to the invention, the fixed-bed catalyst is advantageously a hydrotreating catalyst comprising a hydro-dehydrogenating function comprising at least one metal from group VIII and/or from group VI B, taken alone or as a mixture and a support chosen from the group formed by alumina, silica, silica-aluminas, magnesia, clays and mixtures of at least two of these minerals. This support can also advantageously contain other compounds and for example oxides chosen from the group formed by boron oxide, zirconia, titanium oxide, phosphoric anhydride. The preferred support is an alumina support and most preferably h, d or g alumina.

Said catalyst is advantageously a catalyst comprising metals from group VIII preferably chosen from nickel and cobalt, taken alone or as a mixture, preferably in combination with at least one metal from group VI B preferably chosen from molybdenum and tungsten. , taken alone or in combination.

The content of group VIII metal oxides and preferably of nickel oxide is advantageously between 0.5 and 10% by weight of nickel oxide (NiO) and preferably between 1 and 5% by weight of nickel oxide. nickel and the content of group VI B metal oxides and preferably of molybdenum trioxide is advantageously between 1 and 30% by weight of molybdenum oxide (MOO3), preferably from 5 to 25% by weight, the percentages being expressed in% by weight relative to the total mass of the catalyst.

The total content of metal oxides of groups VI B and VIII in the catalyst used in step a) is advantageously between 5 and 40% by weight and preferably between 6 and 30% by weight relative to the mass. total catalyst.

Said catalyst used in step a) of the process according to the invention must advantageously be characterized by a high hydrogenating power so as to direct the selectivity of the reaction as much as possible towards hydrogenation preserving the number of carbon atoms of the fatty chains. that is to say the hydrodeoxygenation route, in order to maximize the yield of hydrocarbons entering the field of distillation of kerosenes and/or gas oils. This is why it is preferred to operate at a relatively low temperature. Maximizing the hydrogenating function also makes it possible to limit the polymerization and/or condensation reactions leading to the formation of coke which would degrade the stability of the catalytic performances. Preferably, a catalyst of the Ni or NiMo type is used.

Said catalyst used in stage a) of hydrotreatment of the process according to the invention can also advantageously contain a doping element chosen from phosphorus and boron, taken alone or as a mixture. Said doping element can be introduced into the matrix or preferably be deposited on the support. It is also possible to deposit silicon on the support, alone or with phosphorus and/or boron and/or fluorine.

The content by weight of oxide of said doping element is advantageously less than 20% and preferably less than 10% and it is advantageously at least 0.001%.

Preferred catalysts are the catalysts described in patent application FR 2 943 071 describing catalysts having a high selectivity for hydrodeoxygenation reactions.

Other preferred catalysts are the catalysts described in patent application EP 2 210 663 describing supported or bulk catalysts comprising an active phase consisting of a sulphide element from group VI B, the element from group VI B being molybdenum.

The metals of the catalysts used in stage a) of hydrotreatment of the process according to the invention are sulphide metals or metallic phases and preferably sulphide metals.

It would not be departing from the scope of the present invention to use in step a) of the process according to the invention, simultaneously or successively, a single catalyst or several different catalysts. This step can be carried out industrially in one or more reactors with one or more catalytic beds and preferably with a downflow of liquid.

Said hydrotreatment step a) allows the hydrodeoxygenation, hydrodenitrogenation and hydrodesulphurization of said feed.

In accordance with stage b) of the process according to the invention, a stage of separation of at least part and preferably all of the effluent resulting from stage a) is implemented. Said step b) makes it possible to separate at least one light fraction, at least one liquid hydrocarbon effluent.

Said light fraction comprises at least one gaseous fraction which comprises the unconverted hydrogen and the gases containing at least one oxygen atom resulting from the decomposition of the oxygenated compounds during stage a) of hydrotreatment and the compounds C4, c ie the compounds C1 to C4 preferably exhibiting a final boiling point below 20°C. The purpose of this step is to separate the gases from the liquid, and in particular to recover the hydrogen-rich gases which may also contain gases such as CO and CO2 and at least one liquid hydrocarbon effluent. Said liquid hydrocarbon effluent preferably has a sulfur content of less than 10 ppm by weight, a nitrogen content of less than 2 ppm by weight.

Separation step b) can advantageously be implemented by any method known to those skilled in the art such as for example the combination of one or more high and/or low pressure separators, and/or distillation and /or high and/or low pressure stripping.

In accordance with step c) of the process according to the invention, at least a part and preferably all of the liquid hydrocarbon effluent resulting from step b) of separation undergoes a step of elimination of at least a part and preferably all of the water formed by the hydrodeoxygenation (HDO) reactions which take place during stage b) of hydrotreatment. The purpose of this water removal step is to separate the water from the liquid hydrocarbon effluent containing the paraffinic hydrocarbons.

Step c) of eliminating at least part of the water and preferably all of the water can advantageously be carried out by all the methods and techniques known to those skilled in the art. Preferably, said step c) is implemented by drying, by passing over a desiccant, by flash, by decantation or by a combination of at least two of these techniques. The atomic oxygen content of the liquid hydrocarbon effluent containing the paraffinic hydrocarbons resulting from step c) of the process according to the invention, expressed in part per million by weight (ppm) is preferably less than 500 ppm, more preferably less than 300 ppm, very preferably less than 100 ppm by weight. The content in ppm by weight of atomic oxygen in said liquid hydrocarbon effluent is measured by the infrared absorption technique such as for example the technique described in patent application US2009/0018374A1.

In accordance with step d) of the process according to the invention, at least part and preferably all of the liquid hydrocarbon effluent resulting from step c) of the process according to the invention is converted in the presence of a catalyst bifunctional fixed bed hydroconversion, said catalyst comprising a molybdenum and/or tungsten sulphide phase in combination with at least nickel and/or cobalt, said hydroconversion step being carried out at a temperature between 250 and 500°C , at a pressure of between 1 MPa and 10 MPa, at an hourly space velocity of between 0.1 and 10 h ¹ and in the presence of a total quantity of hydrogen mixed with the charge such that the hydrogen/charge ratio is comprised between 70 and 1000 Nm ³ /m ³ of charge, and in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and the partial pressure of hydrogen at the inlet of said hydroconversion stage is less than 5.10 ^-5 , preferably e less than 4.10 ^-5 , very preferably less than 3.10 ^-5 , very preferably less than 2.10 ^-5 and even more preferably less than 1.5.10 ^-5 .

The sulfur present may come from the hydrocarbon effluent from stage c) and/or from the hydrogen flow mixed with the feed from stage d). When the sulfur is provided by the hydrocarbon effluent, it is generally in the form of organic sulfur molecules, unconverted at the end of step a) of the process. When sulfur is supplied by hydrogen, it is generally in the form of hydrogen sulphide. Optionally, sulfur can be provided by adding sulfur molecules to the charge and/or hydrogen to maintain the hydroconversion catalyst in sulfur form.

Within the meaning of the invention, the ratio of the partial pressures of hydrogen sulphide and hydrogen is calculated by considering the quantity of hydrogen and sulfur introduced at the inlet of the hydroconversion unit, and that all the hydrogen introduced is in the gas phase (the hydrogen possibly dissolved in the charge is not considered), that all the sulfur is in the form of hydrogen sulphide (the sulphur-containing molecules, if present, are transformed into hydrogen sulphide), and that all of the hydrogen sulfide is in the gas phase.

If necessary, said hydrogen stream undergoes a purification step in the case where the hydrogen sulphide content in said hydrogen stream entering step d) is greater than 50 ppm by volume. The hydrogen sulfide content in said hydrogen stream can be measured by any method known to those skilled in the art such as, for example, by gas phase chromatography or by laser infrared spectrometry, for example proposed by the company AP2E (ProCeas® analyzer H2 purity).

The hydrogen content in said hydrogen flow can be measured by any method known to those skilled in the art such as for example measurement by thermal conductivity, for example proposed by the company WITT (Inline Gas Analyser).

The presence of oxygenated compounds can induce a loss of activity of the hydroconversion catalyst.

Preferably, said hydrogen stream undergoes a purification step if the atomic oxygen content in said hydrogen stream entering the hydroconversion unit is greater than 250 ppm by volume. Preferably, said hydrogen stream undergoes a purification step in the case where the atomic oxygen content in said hydrogen stream is greater than 50 ppm by volume.

Said hydrogen flow used in the process according to the invention and preferably in step d) of the process according to the invention is advantageously generated by the processes known to those skilled in the art such as for example a catalytic reforming process or catalytic cracking of gases.

Depending on the nature of the different sources, the hydrogen used in the process according to the invention may or may not contain impurities. The atomic oxygen content in said hydrogen flow can be measured by any method known to those skilled in the art such as for example by gas phase chromatography.

Preferably, said hydrogen stream can be fresh hydrogen or a mixture of fresh hydrogen and recycled hydrogen, that is to say hydrogen not converted during step d) of hydroconversion and/or not converted during stage a) of hydrotreatment and recycled in said stage d).

In the case where said hydrogen stream contains an atomic oxygen content greater than 500 ppm volume, preferably greater than 250 ppm volume and preferably greater than 50 ppm volume, said hydrogen stream undergoes a purification step to eliminate the oxygenated compounds before being introduced into said step d). If said hydrogen stream contains a hydrogen sulphide content greater than 50 volume ppm, said hydrogen stream undergoes a purification step to remove the hydrogen sulphide before being introduced into said step d). Said hydrogen flow purification step can advantageously be carried out according to any method known to those skilled in the art (see for example Z. Du et al., Catalysts, 2021, 11, 393).

Preferably, said purification step is advantageously implemented according to the methods of pressure swing adsorption or PSA "Pressure Swing Adsorption" according to the English terminology, or temperature swing adsorption or TSA "Temperature Swing Adsorption" according to Anglo-Saxon terminology, washing with amines, methanation, preferential oxidation, membrane processes, cryogenic distillation, used alone or in combination.

When the process implements a recycling of hydrogen, a purge of the recycled hydrogen can also advantageously be carried out in order to limit the accumulation of molecules containing at least one oxygen atom such as carbon monoxide CO or carbon dioxide CO2 and thus to limit the atomic oxygen content in said hydrogen flow.

Preferably, the atomic oxygen content in said hydrogen stream used in the process according to the invention and preferably in step d) of the process according to the invention, expressed in parts per million by volume (ppmv), must be less than 500 ppmv, preferably less than 250 ppmv and most preferably less than 50 ppmv. The atomic oxygen content in said hydrogen flow is calculated from the concentrations of molecules having at least one oxygen atom in said hydrogen flow, weighted by the number of oxygen atoms present in said oxygenated molecule. By way of example, considering a hydrogen flow containing CO or CO2, the atomic oxygen content contained in said hydrogen flow is then equal to: ppmv(O) = ppmv (CO) + 2 ^* ppmv (CO2 ) with: ppmv (O) atomic oxygen content in the hydrogen stream in parts per million by volume, ppmv (CO) carbon monoxide content in the hydrogen stream in parts per million by volume, ppmv (CO2) carbon dioxide content in the hydrogen stream in parts per million by volume.

In the case where said hydrogen stream contains an atomic oxygen content of less than 500 ppmv, preferably less than 250 ppmv and preferably less than 50 ppmv, no step for purifying said hydrogen stream is implemented before said stream is introduced into said step d).

The operating conditions of step d) of hydroconversion are adjusted to promote the hydroisomerization or hydrocracking reactions as required. Preferably, step d) of hydroconversion of the process according to the invention operates at a temperature of between 250° C. and 450° C., and very preferably, between 250 and 400° C., at a pressure of between 2 MPa and 10 MPa and very preferably between 1 MPa and 9 MPa, at an hourly volume rate advantageously between 0.2 and 7 h ¹ and very preferably between 0.5 and 5 h ^-1 , at a hydrogen flow rate such that the hydrogen/feed volume ratio is advantageously between 100 and 1000 normal m ³ of hydrogen per m ³ of feed and preferably between 150 and 1000 normal m ³ of hydrogen per m ³ of feed. Stage d) of hydroconversion of the process according to the invention operates with a ratio between the partial pressure of hydrogen sulphide and hydrogen of less than 5.10 ^-5 , preferably less than 4.10 ⁵ , very preferably less than 3.10 ⁵ , very preferably less than 2.10 ⁵ and even more preferably less than 1.5.10 ⁵

According to the invention, the hydroconversion catalyst comprises at least tungsten and/or molybdenum in combination with at least nickel and/or cobalt.

The tungsten and/or molybdenum content is advantageously comprised in oxide equivalent between 5 and 50% by weight relative to the finished catalyst, preferably between 10 and 40% by weight and very preferably between 15 and 35% by weight and the nickel and/or cobalt content of said catalyst is advantageously comprised in oxide equivalent between 0.5 and 10% by weight relative to the finished catalyst, preferably between 1 and 8% by weight and very preferably between 1.5 and 6% by weight. Said catalyst is used in its sulfurized form.

Preferably the catalyst comprises tungsten in combination with nickel.

The metals are advantageously introduced into the catalyst by any method known to those skilled in the art, such as for example comixing, dry impregnation or impregnation by exchange.

The hydroconversion catalyst also advantageously comprises at least one acidic solid and optionally a binder.

Preferably, the acidic solid is a Bronsted acid preferably chosen from silica alumina, zeolite Y, SAPO-11, SAPO-41, ZSM-22, ferrierite, ZSM-23, ZSM-48 , ZBM-30, IΊZM-1, COK-7. Preferably, the acidic solid is silica alumina. Optionally, a binder can advantageously also be used during the support shaping step. A binder is preferably used when zeolite is used.

Said binder is advantageously chosen from silica (S1O ₂ ), alumina (Al ₂ O ₃ ), clays, titanium oxide (T1O ₂ ), boron oxide (B ₂ O ₃ ) and zirconia (ZrC>2) taken alone or in a mixture. Preferably, said binder is chosen from silica and alumina and even more preferably, said binder is alumina in all its forms known to those skilled in the art, such as for example gamma alumina.

A preferred catalyst used in the process according to the invention comprises a silica-alumina and at least tungsten and/or molybdenum and at least nickel and/or cobalt, said catalyst being sulfurized. The tungsten and/or molybdenum content is advantageously comprised, in oxide equivalent, between 5 and 50% by weight relative to the finished catalyst, preferably between 10 and 40% by weight and very preferably between 15 and 35% by weight. weight and the nickel and/or cobalt content of said catalyst is advantageously comprised, in oxide equivalent, between 0.5 and 10% by weight relative to the finished catalyst, preferably between 1 and 8% by weight and very preferably between 1.5 and 6% by weight. The element content is perfectly measured using X-ray fluorescence.

A preferred catalyst used in the process according to the invention comprises a particular silica-alumina, said silica-alumina having:

- alumina and silica with a mass content of silica (S1O2) greater than 5% by weight and less than or equal to 95% by weight, preferably between 10 and 80% by weight, preferably a higher silica content at 20% by weight and less than 80% by weight and even more preferably greater than 25% by weight and less than 75% by weight, the silica content is advantageously between 10 and 50% by weight

- a BET specific surface of 100 to 500 m ² /g, preferably between 200 m ² /g and 450 m ² /g and very preferably between 200 m ² /g and 300 m ² /g,

- an average diameter of the mesopores measured by mercury porosimetry between 3 and 12 nm, preferably between 3 nm and 11 nm and very preferably between 4 nm and 10.5 nm,

- a total pore volume measured by mercury porosimetry of between 0.4 and 1.2 ml/g, preferably between 0.4 and 1.0 ml/g and very preferably between 0.4 and 0.8 ml /g,

- a volume of the macropores, the diameter of which is greater than 50 nm, less than 0.002 ml/g.

The mean diameter of the mesopores is defined as being the diameter corresponding to the cancellation of the curve derived from the mercury intrusion volume obtained from the mercury porosity curve for pore diameters between 2 and 50 µm. Preferably, the metal distribution coefficient of said preferred catalyst is greater than 0.1, preferably greater than 0.2 and very preferably greater than 0.4. The distribution coefficient represents the distribution of the metal inside the catalyst grain. The partition coefficient of metals can be measured by Castaing microprobe.

In accordance with step e) of the process according to the invention, the effluent from step d) undergoes a fractionation step, preferably in a distillation train which integrates atmospheric distillation and optionally vacuum distillation, to obtain at least a middle distillate fraction.

The purpose of said step e) is to separate the gases from the liquid, and in particular to recover the hydrogen-rich gases which may also contain light substances such as the Ci - C4 cut and at least one diesel cut, at least one kerosene cut and at least one minus a naphtha cup. Upgrading the naphtha cut is not the subject of the present invention, but this cut can advantageously be sent to a steam cracking or catalytic reforming unit.

Description of figures

Figure 1 represents the evolution of the cloud point of the liquid effluent as a function of time during the hydroconversion in Example 4.

Figure 2 represents the evolution of the cloud point of the liquid effluent as a function of time during the hydroconversion in example 7.

Figure 3 represents the evolution of the cloud point of the liquid effluent as a function of time during the hydroconversion in example 8.

Figure 4 represents the evolution of the cloud point of the liquid effluent as a function of time during the hydroconversion in Example 9.

EXAMPLES

Example 1: preparation of a hydrotreating catalyst (C1)

The catalyst is an industrial catalyst based on nickel, molybdenum and phosphorus on alumina with contents of molybdenum oxide M0O3 of 22% by weight, nickel oxide NiO of 4% by weight and phosphorus oxide P2O5 of 5% by weight relative to to the total weight of the finished catalyst, supplied by the company AXENS.

Example 2: Preparation of a hydroconversion catalyst in accordance with the invention (C2) The silica-alumina powder is prepared according to the synthesis protocol described in patent EP1 415 712A. The amounts of orthosilicic acid and aluminum hydrate are chosen so as to have a composition of 70% by weight of alumina Al ₂ O ₃ and 30% by weight of silica S1O ₂ in the final solid.

This mixture is rapidly homogenized in a commercial colloid mill in the presence of nitric acid so that the nitric acid content of the suspension leaving the mill is 8% relative to the mixed silica-alumina solid. Then the suspension is conventionally dried in an atomizer in a conventional manner at 300°C to 60°C. The powder thus prepared is shaped in a Z arm in the presence of 8% nitric acid relative to the anhydrous product. Extrusion is carried out by passing the paste through a die fitted with 1.4 mm diameter holes. The extrudates thus obtained are dried in an oven at 140°C then calcined under a flow of dry air at 550°C then calcined at 850°C in the presence of steam.

The characteristics of the support thus prepared are as follows:

- an average diameter of the mesopores measured by mercury porosimetry of 7.7 nm,

- a total pore volume of 0.49 ml/g,

- a mesoporous volume of 0.47 ml/g,

- a volume of macropores, whose diameter is greater than 50 nm, less than 0.01 ml/g,

- a BET surface of 240 m ² /g.

The silica-alumina extrudates are then subjected to a dry impregnation step with an aqueous solution of ammonium metatungstate and nickel nitrate, left to mature in a water soaker for 24 hours at room temperature and then calcined for two hours under dry air in bed traversed at 450°C (temperature rise ramp of 5°C/min). The content by weight of tungsten oxide WO ₃ of the finished catalyst after calcination is 27%, the content of nickel oxide NiO is 3.5%. The metal distribution coefficient measured by Castaing microprobe is equal to 0.93.

Example 3: hydrotreatment of a feed from a renewable source according to a process in accordance with the invention

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed charged with 190 ml of hydrotreating catalyst C1, the catalyst being previously sulfurized, the hydrotreating of pre-refined rapeseed oil with a density of 920 is carried out. kg/m ³ having an oxygen content of 11% by weight. The cetane number is 35 and the fatty acid distribution of rapeseed oil is detailed in table 1. the hydrotreatment step, said charge is added with dimethyldisulphide in order to adjust its sulfur content to 50 ppm by weight.

Fatty acid composition

14:0 0.1

16:0 5.0

16:1 0.3

17:0 0.1

17:1 0.1

18:0 1.5

18:1 trans <0.1 18:1 cis 60.1 18:2 trans <0.1 18:2 cis 20.4 18:3 trans <0.1 18:3 cis 9.6 20:0 0.5 20 :1 1.2 22:0 0.3 22:1 0.2 24:0 0.1 24:1 0.2

Table 1: Characteristics of the rapeseed oil used as a feedstock for the hydrotreatment Before hydrotreating the feedstock, the catalyst is sulfurized in-situ in the unit, with a distillation gas oil containing 2% by weight of dimethyldisulphide , under a total pressure of 5.1 MPa, a hydrogen/gas oil ratio with additives of 700 Nm ³ per m ³ . The volume of diesel fuel added per volume of catalyst and per hour is set at 1 h ¹ . The sulfurization is carried out for 12 hours at 350° C., with a temperature rise ramp of 10° C. per hour. After sulfurization, the operating conditions of the unit are adjusted in order to carry out the hydrotreatment of the charge:

- WH (volume of charge / volume of catalyst / hour): 1 h ¹ _,

- total working pressure: 5.1 MPa,

- hydrogen/charge ratio: 700 Nm ³ of hydrogen / m ³ of charge, - temperature: 310°C.

The hydrogen used is supplied by Air Product and has a purity greater than 99.999% by volume.

Step b) and c): separation of the effluent from step a) All of the hydrotreated effluent from step a) is separated using a gas/liquid separator so as to recover a light fraction containing mainly hydrogen, propane, water in vapor form, carbon oxides (CO and CO2) and ammonia and a liquid hydrocarbon effluent mainly consisting of linear hydrocarbons. The water present in the liquid hydrocarbon effluent is removed by settling. The liquid hydrocarbon effluent thus obtained contains an atomic oxygen content of less than 80 ppm by weight, said atomic oxygen content being measured by the infrared adsorption technique described in patent application US2009/0018374, and a sulfur content of 2 ppm by weight and a nitrogen content of less than 1 ppm by weight, said nitrogen and sulfur contents being measured respectively by chemiluminescence and by UV fluorescence. Said liquid hydrocarbon effluent has a density of 791 kg/m ³ . The liquid hydrocarbon effluent is composed of paraffins; its composition, measured by gas chromatography, is provided in Table 2.

Table 2: composition of the liquid hydrocarbon effluent used as feedstock for hydroconversion

Example 4: Hydroconversion of the liquid hydrocarbon effluent from Example 3 according to a process not in accordance with the invention

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed loaded with 50 ml of hydroconversion catalyst C2, the catalyst being previously sulfurized, the hydroconversion of the liquid hydrocarbon effluent from example 3. Sulfur is introduced beforehand in the form of dimethyldisulphide into said liquid hydrocarbon effluent, so as to obtain a total sulfur content of 500 ppm by weight in said liquid hydrocarbon effluent.

Catalyst C2 undergoes an in-situ sulfurization step in the unit, with isane to which 2% by weight of dimethyldisulfide has been added, under a total pressure of 5.1 MPa, a hydrogen ratio / isane with additive of 350 Nm ³ per m ³ . The volume of isane added per volume of catalyst and per hour is set at 1 h ¹ . The sulfurization is carried out for 12 hours at 350° C., with a temperature rise ramp of 10° C. per hour.

After sulfurization, the operating conditions of the unit are adjusted in order to carry out the hydroconversion of the liquid hydrocarbon effluent containing 500 ppm by weight of sulfur:

- WH (volume of charge / volume of catalyst / hour) = 1 h ¹ _,

- total working pressure: 5.1 MPa,

- hydrogen/charge ratio: 700 Nm ³ of hydrogen/m ³ of charge.

The hydrogen stream used and entering the hydroconversion stage is provided by Air Product, it has a purity greater than 99.999%, it is free of hydrogen sulphide. The ratio between the partial pressure of hydrogen sulphide and the partial pressure of hydrogen is then equal to 4.10 ^-4 .

Temperature stages at 333 and 343°C are carried out in order to vary the severity of the hydroconversion. The measurement (typically daily) of the cloud point (by the ASTM D5773 method) of the liquid effluent makes it possible to follow the evolution of the performance of the catalyst at each temperature level. For each temperature, the test duration is extended until a stable cloud point is obtained. Once cloud point stability is achieved, the liquid effluent is accumulated for 24 hours. Under the chosen operating conditions, no deactivation of the catalyst is observed (see Figure 1).

On leaving the unit, an online analysis by gas phase chromatography and a gas meter make it possible to calculate the mass of light hydrocarbons produced (essentially hydrocarbons with 1 to 5 carbon atoms) and present in the hydrogen flow. Said liquid effluent is then weighed then fractionated by distillation in order to determine the average distillate yield (cut 130° C. ⁺ , corresponding to hydrocarbons whose boiling point is more than 130° C.).

The average distillate yield is calculated as follows:

Yield (middle distillate) = [(mass liquid effluent* %cut 130 100) / (mass liquid effluent + mass of light hydrocarbons)] * 100

Furthermore, the cloud point and the motor cetane number of the middle distillate cut are respectively determined by the ASTM D5773 method, and by the CFR method by ASTM D613. The main characteristics of the effluents produced and the associated operating conditions are shown in Table 3.

Example 5: Hydroconversion of the liquid hydrocarbon effluent from Example 3 according to a process in accordance with the invention

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed loaded with 50 ml of hydroconversion catalyst C2, the catalyst being previously sulfurized, the hydroconversion of the liquid hydrocarbon effluent from example 3. Sulfur is introduced beforehand in the form of dimethyldisulphide into said liquid hydrocarbon effluent, so as to obtain a total sulfur content of 50 ppm by weight in said liquid hydrocarbon effluent.

Catalyst C2 undergoes a sulfurization step identical to that reported in Example 4.

After sulfurization, the operating conditions of the unit are adjusted in order to carry out the hydroconversion of the liquid hydrocarbon effluent containing 50 ppm by weight of sulfur:

- WH (volume of charge / volume of catalyst / hour) = 1 h ¹ _,

- total working pressure: 5.1 MPa,

- hydrogen/charge ratio: 700 Nm ³ of hydrogen/m ³ of charge.

The operating conditions are therefore the same as those of Example 4, only the sulfur content in the liquid hydrocarbon effluent is different.

The hydrogen stream used and entering the hydroconversion stage is supplied by Air Product, it has a purity greater than 99.999% by volume, it is free of hydrogen sulphide. The ratio between the partial pressure of hydrogen sulphide and the partial pressure of hydrogen is then equal to 4.10 ^-5 .

The temperature stages are adjusted in order to obtain cloud points of the middle distillate comparable to those obtained in example 4. The measurement (typically daily) of the cloud point of the liquid effluent makes it possible to follow the evolution of the performances catalyst at each temperature level. For each temperature, the test duration is extended until a stable cloud point is obtained. Once cloud point stability is achieved, the liquid effluent is accumulated for 24 hours. Under the chosen operating conditions, no deactivation of the catalyst is observed.

Said liquid effluent is then weighed and then fractionated by distillation in order to determine the average distillate yield in the manner reported in Example 4. The main characteristics of the effluents produced and the associated operating conditions are shown in Table 3. It can be seen that compared to non-compliant Example 4, the reduction in the P(H2S)/P(H2) ratio makes it possible to improve the activity of the catalyst. Indeed, the temperature required to reach a comparable cloud point value is 2 to 3 degrees lower. In addition, the reduction in the P(H2S)/P(H2) ratio also makes it possible to improve the selectivity of the catalyst since for a comparable cloud point value, the yield of middle distillate increases by 5 points.

Example 6: Hydroconversion of the liquid hydrocarbon effluent resulting from example 3 according to a method in accordance with the invention

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed loaded with 50 ml of hydroconversion catalyst C2, the catalyst being previously sulfurized, the hydroconversion of the liquid hydrocarbon effluent from example 3. Sulfur is introduced beforehand in the form of dimethyldisulphide into said liquid hydrocarbon effluent, so as to obtain a total sulfur content of 15 ppm by weight in said liquid hydrocarbon effluent.

Catalyst C2 undergoes a sulfurization step identical to that reported in Example 4.

After sulfurization, the operating conditions of the unit are adjusted in order to carry out the hydroconversion of the liquid hydrocarbon effluent containing 50 ppm by weight of sulfur:

- WH (volume of charge / volume of catalyst / hour) = 1 h ¹ _,

- total working pressure: 5.1 MPa,

- hydrogen/charge ratio: 700 Nm ³ of hydrogen/m ³ of charge.

The operating conditions are therefore the same as those of Example 4, only the sulfur content in the liquid hydrocarbon effluent is different.

The hydrogen stream used and entering the hydroconversion stage is supplied by Air Product, it has a purity greater than 99.999% by volume, it is free of hydrogen sulphide. The ratio between the partial pressure of hydrogen sulphide and the partial pressure of hydrogen is then equal to 1.2.10 ^-5 .

The temperature stages are adjusted in order to obtain cloud points of the middle distillate comparable to those obtained in example 4. The measurement (typically daily) of the cloud point of the liquid effluent makes it possible to follow the evolution of the performances catalyst at each temperature level. For each temperature, the test duration is extended until a stable cloud point is obtained. Once the stability of the cloud point is reached, we accumulates liquid effluent for 24 hours. Under the operating conditions chosen, no deactivation of the catalyst is observed.

Said liquid effluent is then weighed and then fractionated by distillation in order to determine the average distillate yield in the manner reported in Example 4. The main characteristics of the effluents produced and the associated operating conditions are reported in Table 3. It is noted that compared to Example 4 not conforming, the reduction of the P(H ₂ S)/P(H2) ratio makes it possible to improve the activity of the catalyst. Indeed, the temperature required to reach a comparable cloud point value is 5 to 6 degrees lower. In addition, the reduction in the P(H ₂ S)/P(H2) ratio also makes it possible to improve the selectivity of the catalyst since for a comparable cloud point value, the yield of middle distillate increases by 6 points.

Table 3: Main characteristics of the effluents produced by hydroconversion and associated operating conditions Example 7: Hydroconversion of the liquid hydrocarbon effluent from Example 3 according to a process not in accordance with the invention

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed loaded with 50 ml of hydroconversion catalyst C2, the catalyst being previously sulfurized, the hydroconversion of the liquid hydrocarbon effluent from example 3. Sulfur is introduced beforehand in the form of dimethyldisulphide into said liquid hydrocarbon effluent, so as to obtain a total sulfur content of 50 ppm by weight in said liquid hydrocarbon effluent.

Catalyst C2 undergoes an in-situ sulphidation step in the unit, with isane to which 2% by weight of dimethyl disulphide has been added, under a total pressure of 5.1 MPa, a hydrogen/gasoil ratio with additive of 700 Nm ³ per m ³ . The volume of isane added per volume of catalyst and per hour is set at 1 h ¹ . The sulfurization is carried out for 12 hours at 350° C., with a temperature rise ramp of 10° C. per hour.

After sulfurization, the operating conditions of the unit are adjusted in order to carry out the hydroconversion of the liquid hydrocarbon effluent containing 50 ppm by weight of sulfur:

- WH (volume of charge / volume of catalyst / hour) = 0.6 h ¹ _,

- total working pressure: 2.8 MPa,

- hydrogen/charge ratio: 470 Nm ³ of hydrogen/m ³ of charge.

The hydrogen stream used in the hydroconversion step is supplied by Air Product, it has a purity greater than 99.999% by volume, it is free of hydrogen sulphide. The ratio between the partial pressure of hydrogen sulphide and the partial pressure of hydrogen is then equal to 6.10 ^-5 .

Compared to Examples 4 and 5, the operating conditions chosen are more demanding with respect to the stability of the catalyst. Without wishing to be bound by any theory, the Applicant believes that the reduction in the total working pressure as well as in the hydrogen/charge ratio can promote deactivation by coking of the catalyst.

Temperature stages at 326 then 336°C are carried out in order to vary the severity of the hydroconversion, and a return point is carried out at 326°C to evaluate the deactivation of the catalyst. The regular measurement (typically daily) of the cloud point of the liquid effluent makes it possible to follow the evolution of the performance of the catalyst at each temperature level. For each temperature, the test duration is extended until a stable cloud point is obtained. Once cloud point stability is achieved, the liquid effluent is accumulated for 24 hours. Said liquid effluent is then weighed and then fractionated by distillation in order to determine the average distillate yield in the manner reported in Example 4.

Figure 2 represents the evolution of the daily measurement of the liquid effluent during the test. Under the chosen operating conditions, the catalyst undergoes deactivation at each temperature of the test as evidenced by the increase in the value of the cloud point between the start and the end of each temperature level. For example at the first point at 326°C, the cloud point increases from -19°C (after 36 hours) to -10°C at 252 hours, at which point catalyst activity stabilizes. A deactivation is also observed at the second point (temperature plateau at 336° C.). Finally, the return point carried out at 326°C confirms the deactivation of the catalyst: the cloud point stabilizes at 1°C, against -10°C as a stabilized value at the end of the first point. The increase in cloud point between the first measured value and the last measured value is used to assess catalyst deactivation:

Catalyst deactivation = final cloud point (°C) - initial cloud point (°C)

The deactivation of the catalyst as well as the main characteristics of the effluents produced and the operating conditions associated with point No. 1 and point No. 2 are reported in Table 4.

Example 8: Hydroconversion of the liquid hydrocarbon effluent resulting from example 3 according to a method in accordance with the invention

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed loaded with 50 ml of hydroconversion catalyst C2, the catalyst being previously sulfurized, the hydroconversion of the liquid hydrocarbon effluent from example 3. Sulfur is introduced beforehand in the form of dimethyldisulphide into said liquid hydrocarbon effluent, so as to obtain a total sulfur content of 10 ppm by weight in said liquid hydrocarbon effluent.

Catalyst C2 undergoes a sulfurization step identical to that reported in Example 6.

After sulfurization, the operating conditions of the unit are adjusted in order to carry out the hydroconversion of the liquid hydrocarbon effluent containing 11 ppm by weight of sulfur:

- WH (volume of charge / volume of catalyst / hour) = 0.6 h ¹ _,

- total working pressure: 2.8 MPa,

- hydrogen/charge ratio: 470 Nm ³ of hydrogen/m ³ of charge.

The operating conditions are therefore the same as those of Example 6, only the sulfur content in the liquid hydrocarbon effluent is different.

The hydrogen stream used in the hydroconversion step is supplied by Air Product, it has a purity greater than 99.999% by volume, it is free of hydrogen sulphide. The ratio between the partial pressure of hydrogen sulphide and the partial pressure of hydrogen is then equal to 1.2 10 ⁵ . Temperature stages at 326 then 336° C. are carried out in order to vary the severity of the hydroconversion, and a return point is carried out at 326° C. to evaluate the deactivation of the catalyst. The regular measurement (typically daily) of the cloud point of the liquid effluent makes it possible to follow the evolution of the performance of the catalyst at each temperature level. For each temperature, the test duration is extended until a stable cloud point is obtained. Once cloud point stability has been achieved, the liquid effluent is accumulated for 24 hours. Said liquid effluent is then weighed and then fractionated by distillation in order to determine the average distillate yield in the manner reported in Example 4.

Figure 3 represents the evolution of the daily measurement of the liquid effluent during the test. Under the chosen operating conditions, the catalyst undergoes deactivation at each temperature of the test, just as is observed in Example 7, which is non-compliant. On the other hand, the deactivation is less pronounced than in example 7. For example at the first point at 326° C., the cloud point increases from -20° C. (after 24 hours) to -15° C. at 288 hours, value at which the activity of the catalyst stabilizes. A deactivation is also observed at the second point (temperature plateau at 336° C.). The less deactivation of the catalyst makes it possible to reach stabilized values of cloud point lower than in example 6: -15°C at the end of point 1 (compared to -10°C in example 6), -22 °C at the end of point 2 (against - 16°C in example 6). Finally, the stabilized value of the cloud point at point 3 (return point) confirms the slightest deactivation: -4°C against +1°C in example 6.

The deactivation of the catalyst and the main characteristics of the effluents produced and the associated operating conditions are shown in Table 4. all other things being equal, multiple gains when the operating conditions cause catalyst deactivation. On the one hand, compared to non-compliant example 6, the deactivation is less. On the other hand, for a given reaction temperature, the reduction in the P(H2S)/P(H2) ratio makes it possible both to improve the yield of middle distillate as well as the cold properties of said middle distillate.

Table 4: Main characteristics of effluents produced by hydroconversion and associated operating conditions

Example 9: Hydroconversion of the liquid hydrocarbon effluent resulting from example 3 according to a method in accordance with the invention

When using the catalyst in the industrial hydroconversion unit, it may happen that the P(H ₂ S)/P(H2) ratio is not in accordance with the invention during certain periods. For example due to occasional malfunctioning of any tools for purifying the hydrogen sent to the unit and/or the liquid hydrocarbon effluent from step c). The readjustment of the P(H ₂ S)/P(H2) ratio in a range in accordance with the invention, after operation under non-compliant conditions, also makes it possible to improve the performance of the catalyst as illustrated below.

In a temperature-regulated reactor so as to ensure isothermal operation and with a fixed bed loaded with 50 ml of hydroconversion catalyst C2, the catalyst being previously sulfurized, the hydroconversion of the liquid hydrocarbon effluent from example 3.

Catalyst C2 undergoes a sulfurization step identical to that reported in Example 6.

After sulfurization, the step of hydroconversion of the liquid hydrocarbon effluent from Example 3 is carried out under different operating conditions, some of which simulate temporary operation of the unit not in accordance with the invention during certain periods. the Table 5 shows the different operating conditions implemented. Throughout the test, the temperature, the total pressure, the hydrogen/charge ratio and the WH are kept constant. Points 1 and 4 are not in accordance with the invention because of their too high P(H2S)/P(H2) ratio (additivation of dimethyldisulphide in the charge), whereas points 2 and 3 are in conformity. For points 2 and 4 oxygenated impurities are also present in the hydrogen flow. This is done by using a standard mixture containing hydrogen, carbon monoxide and carbon dioxide supplied by Air Product. The atomic O content contained in the hydrogen flow is then 4200 ppm by volume. The regular measurement (typically daily) of the cloud point of the liquid effluent makes it possible to follow the evolution of the performance of the catalyst at each temperature level. For each temperature, the test duration is extended until a stable cloud point is obtained. Once cloud point stability has been achieved, the liquid effluent is accumulated for 24 hours. Said liquid effluent is then weighed and then fractionated by distillation in order to determine the average distillate yield in the manner reported in Example 4.

Figure 4 represents the evolution of the daily measurement of the liquid effluent during the test. Under the operating conditions chosen, the catalyst undergoes deactivation at the first point of the test (non-compliant), just as is observed in examples 7 and 8. It is observed that the cloud point stabilizes at a value of -6° vs. All other things being equal, adjusting the P(H2S)/P(H2) ratio to a value in accordance with the invention, at point 2, allows the catalyst to regain activity. At point 2 the cloud point stabilizes at -8°C. At point 3, the addition of oxygenated compounds in the hydrogen induces a loss of activity of the catalyst, the cloud point then stabilizing at -5°C. At point 4, all other things being equal, the adjustment of the P(H2S)/P(H2) ratio to a value not in accordance with the invention still induces a loss of activity of the catalyst, the cloud point then stabilizing at 0°C. Whether in the presence or absence of oxygenated compounds, it therefore appears advantageous to work in a range of P(H2)/P(H2S) ratios in accordance with the invention.

Finally, Table 5 shows the main characteristics of the effluents produced at each operating point, when the unit is stabilized. Here again the mode of operation according to the invention is advantageous. All other things being equal, adjusting the P(H ₂ S)/P(H2) ratio to values in accordance with the invention makes it possible both to gain in middle distillate yield but also to improve the cold properties of said middle distillate (comparison point 1 and point 2 and comparison point 3 and point 4).

Table 5: Main characteristics of the effluents produced by hydroconversion and associated operating conditions for Example 9

Claims

1. Process for treating a filler from a renewable source 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 , comprising at least: a) a step of hydrotreating said charge in the presence of a catalyst in a fixed bed, said catalyst comprising a hydrogenating function and an oxide support, at a temperature between 200 and 450°C, at a pressure between 1 MPa and 10 MPa, at an hourly space velocity between 0.1 h ¹ and 10 h ^-1 and in the presence of a total quantity of hydrogen mixed with the charge such that the hydrogen/charge ratio is between 70 and 1000 Nm ³ of hydrogen/m ³ of charge, b) a step of separating at least part of the effluent from step a) into at least one light fraction and at least one liquid hydrocarbon effluent , c) a step of removing at least part of the water from the liquid effluent hydrocarbon resulting from stage b), d) a stage of hydroconversion of at least part of the liquid hydrocarbon effluent resulting from stage c) in the presence of a bifunctional fixed-bed hydroconversion catalyst, said catalyst comprising a molybdenum and/or tungsten sulphide phase in combination with at least nickel and/or cobalt, said hydroconversion step being carried out at a temperature of between 250°C and 500°C, at a pressure of between 1 MPa and 10 MPa, at an hourly space velocity of between 0.1 and 10 h ¹ and in the presence of a total quantity of hydrogen mixed with the charge such that the hydrogen/charge ratio is between 70 and 1000 Nm ³ /m ³ of charge, in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and hydrogen at the inlet of said hydroconversion stage is less than 5.10 ^-5 , e) a stage for fractionating the effluent from step d) to obtain at least one fraction ction middle distillate. 2. Process according to claim 1, in which in stage a), the charge is brought into contact with a catalyst in a fixed bed at a temperature of between 220 and 350° C., at a pressure of between 1 MPa and 6 MPa, at an hourly space velocity between 0.1 h ^-1 and 10 h ¹ . The charge is brought into contact with the catalyst in the presence of hydrogen and in the presence of a total quantity of hydrogen mixed with the charge such that the hydrogen/charge ratio is between 150 and 750 Nm ³ of hydrogen/m ³ of charge. 3. Method according to one of claims 1 or 2 wherein step b) of separation is implemented by the combination of one or more high and / or low pressure separators, and / or distillation steps and / or high and/or low pressure stripping. 4. Method according to one of claims 1 to 3 wherein said step c) is implemented by drying, by passing over a desiccant, by flash, by decantation or by a combination of at least two of these techniques. 5. Method according to one of claims 1 to 4 wherein step d) is carried out in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and hydrogen at the inlet of said hydroconversion stage is less than 4.10 ^-5 . 6. Process according to claim 5, in which stage d) is carried out in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and hydrogen at the inlet of said hydroconversion stage is less than 3.10 ^-5 . 7. Process according to claim 6, in which stage d) is carried out in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and hydrogen at the inlet of said hydroconversion stage is less than 2.10 ^-5 . 8. Process according to claim 7, in which stage d) is carried out in the presence of a total quantity of sulfur such that the ratio between the partial pressure of hydrogen sulphide and hydrogen at the inlet of said hydroconversion stage is less than 1.5.10 ^-5 . 9. Method according to one of claims 1 to 8 wherein said hydrogen flow undergoes a purification step in the case where the atomic oxygen content in said hydrogen flow at the inlet of step d) is greater than 250 ppm by volume. 10. Method according to one of claims 1 to 9 wherein said hydrogen flow undergoes a purification step in the case where the atomic oxygen content in said hydrogen flow at the inlet of step d) is greater than 50 ppm by volume. 11. Method according to one of claims 9 to 10 wherein said purification step is implemented according to the methods of pressure swing adsorption or PSA "Pressure Swing Adsorption" according to the English terminology, or adsorption modulated in temperature or TSA "Temperature Swing Adsorption" according to the Anglo-Saxon terminology, washing with amines, methanation, preferential oxidation, membrane processes, used alone or combined.