FR2958656A1 - METHOD FOR HYDROCONVERSION OF PETROLEUM LOADS VIA SLURRY TECHNOLOGY FOR RECOVERING METALS FROM THE CATALYST AND THE LOAD USING AN EXTRACTION STEP - Google Patents

Abstract

A method of hydroconversion of heavy petroleum feedstocks comprising a step of hydroconversion of the feedstock in at least one reactor containing a slurry catalyst and allowing the recovery of the metals in the unconverted residual fraction, in particular those used as catalysts. The method comprises a hydroconversion step, a gas / liquid separation step, at least one liquid / liquid extraction step, a combustion step, a metal extraction step, and a catalytic solution preparation step that are recycled in the hydroconversion stage.

Description

The invention relates to a process for the hydroconversion of heavy petroleum feedstocks into lighter products, recoverable as fuels and / or raw materials for petrochemicals. More particularly, the invention relates to a process for hydroconversion of heavy petroleum feeds comprising a step of hydroconversion of the feedstock in at least one reactor containing a slurry catalyst and allowing the recovery of the metals in the unconverted residual fraction, in particular those used as catalysts, in order to valorize them in catalytic solutions and to recycle them upstream of the slurry conversion process. The method comprises a hydroconversion step, a gas / liquid separation step, at least one liquid-liquid extraction step, a combustion step, a metal extraction step, and a solution preparation step (s). catalytic (s) that is / are recycled (s) in the hydroconversion stage.

The conversion of heavy oil loads into liquid products can be done by heat treatments or by hydrogenation treatments, also called hydroconversion. Current research is mainly focused on hydroconversion because heat treatments generally produce poor quality products and a significant amount of coke. The hydroconversion of heavy feeds involves the conversion of the feedstock in the presence of hydrogen and a catalyst. The commercial processes use depending on the load, fixed bed technology, bubbling bed technology or slurry technology. The hydroconversion of heavy charges in fixed bed or bubbling bed is by supported catalysts comprising one or more transition metals (Mo, W, Ni, Co, Ru) on supports of silica / alumina or equivalent type. For the conversion of heavy charges particularly charged to heteroatoms, metals and asphaltenes, the fixed bed technology is generally limited because the contaminants cause a rapid deactivation of the catalyst thus requiring a frequency of renewal of the catalytic bed too high and therefore too expensive . In order to be able to treat this type of charges, ebullated bed processes have been developed. However, the conversion level of ebullated bed technologies is generally limited to levels below 80% due to the catalytic system employed and the design of the unit. Hydroconversion technologies operating with slurry technology provide an attractive solution to the disadvantages encountered in the use of the fixed bed or bubbling bed. Indeed, the slurry technology makes it possible to treat heavy loads heavily contaminated with metals, asphaltenes and heteroatoms, while having conversion rates generally greater than 85%. Slurry residue hydroconversion technologies use a dispersed catalyst in the form of very small particles, the size of which is less than 1 mm and preferably of a few tens of microns or less (generally 0.001 to 100 μm). Due to this small size of the catalysts, the hydrogenation reactions are facilitated by a uniform distribution throughout the reaction zone and the coke formation is greatly reduced. The catalysts, or their precursors, are injected with the feed to be converted at the inlet of the reactors. The catalysts pass through the reactors with the feedstocks and the products being converted, and then are driven with the reaction products out of the reactors. They are found after separation into the heavy residual fraction, such as, for example, the unconverted vacuum residue. The catalysts used in slurry are generally sulfurized catalysts preferably containing at least one member selected from the group consisting of Mo, Fe, Ni, W, Co, V and / or Ru. Generally, molybdenum and tungsten show much more satisfactory performance than nickel, cobalt or ruthenium and even more than vanadium and iron (N. Panariti et al., Applied Catalysis A: General 204 (2000), 203). -213). The hydroconversion technologies of commercialized heavy slurries are known. Examples include EST technology licensed by ENI, Chevron-Lummus-Global licensed VRSH technology, Intevep-licensed HDH and HDHPLUS technologies, UOP-licensed SRC-Uniflex technology, Headwaters licensed technology (HC) 3, etc. ...

Although the small size of the slurry catalysts makes it possible to obtain very high conversion rates, this size is problematic as regards the separation and recovery of the catalyst (s) after the hydroconversion reaction. The catalysts are found after separation in the heavy residual fraction, such as unconverted vacuum residue. In some processes, a portion of the vacuum residue containing the unconverted fraction and the catalysts is recycled directly to the hydroconversion reactor to increase conversion efficiency. However, these recycled catalysts generally have no activity or much reduced activity compared to fresh catalyst. In addition, the vacuum residue is traditionally used as fuel for the production of heat, electricity and ash. These ashes contain metals and are generally dumped. In this case, the metals are not recovered. In addition, the deactivation of the catalysts requires regular replacement thus creating a demand for fresh catalysts. The heavy loads treated contain a high concentration of metals, mainly vanadium and nickel. These metals are largely removed from the charge by settling on the catalysts during the reaction. They are washed away by the catalyst particles leaving the reactor. Similarly, the deactivation of the catalysts is accentuated by the formation of coke, in particular from the high concentration of asphaltenes contained in these feeds.

The continuous renewal of the catalytic phase finely dispersed in the reaction zone allows the contact of the hydrogen dissolved in the liquid phase to hydrogenate and hydrotrate the injected heavy load. In order to ensure a high level of conversion and a maximum hydrotreatment of the feedstock, the amount of catalytic solution to be injected is quite high which represents relatively high industrial operating costs. Thus, slurry hydroconversion processes are generally consuming a large amount of catalysts, in particular molybdenum, which has the most active catalyst, but also the most expensive. The costs of fresh catalysts, catalyst separation and metal recovery have a major impact on the profitability of such processes. The selective recovery of molybdenum and its recycling as a catalyst are two essential elements for the industrial valorization of slurry processes. This recovery is also accompanied by those of other metals such as nickel (the one injected and the one recovered in the charge) and the vanadium recovered in the charge whose contents are comparable to that of molybdenum and which can be resold for metallurgical applications. Apart from these economic aspects, the recovery of metals is also necessary for environmental reasons. In fact, ashes from the combustion of the residual fraction have been classified in many countries as hazardous waste because the metals contained in the ashes disposed of in dump sites present a danger for the water table. There is therefore a real need for recovery and recycling of metals from the catalysts and the heavy load of slurry hydroconversion process. PRIOR ART The processes for recovering metals from slurry processes are known in the state of the art. Thus, patent application US2008 / 0156700 describes a process for separating catalysts in the form of ultrafine particles resulting from a slurry hydroconversion process comprising a step of precipitation or flocculation of a heavy fraction including metal parts by means of Heptane solvents, a step of separating the heavy fraction of the light fraction by centrifugation and a coking step between 350 ° and 550 ° C under an inert atmosphere to obtain coke containing the catalyst. This coke can be subjected to a metal extraction step. US Pat. No. 4,592,827 discloses a heavy duty slurry hydroconversion process in the presence of a soluble metal compound and water comprising, after the hydroconversion reaction, a separation step, a step of deasphalting the residue fraction. under vacuum by C5 to C8 hydrocarbons and a step of gasification of asphaltenes producing hydrogen and ash containing the catalyst. This catalyst is then subjected to metal extraction steps, the metals are recycled in the process.

US Pat. No. 4,548,700 discloses a heavy-duty slurry hydroconversion process comprising, after the hydroconversion reaction, a step of separation of the gaseous fraction, a distillation step, a washing of the atmospheric residue (650 ° F + = 343 ° C + ) toluene at atmospheric pressure and ambient temperature and a step of combustion or gasification of the solid fraction at temperatures between 427-1093 ° C (800-2000 ° F) to obtain ash containing the metals. The metals V and Mo are recovered by an extraction step with oxalic acid and then recycled in the process. US Pat. No. 6,511,937 describes a heavy-duty slurry hydroconversion process comprising, after the hydroconversion reaction, a separation step in a high-pressure, low-temperature separator making it possible to separate a very light fraction, a deasphalting step of the entire residual fraction using paraffinic C3 to C5 solvents at room temperature, a coking step (427-649 ° C, without air) and / or a combustion step below 649 ° C to produce ash containing the catalyst . This catalyst may subsequently be subjected to metal extraction steps and recycled to the process. OBJECT OF THE INVENTION The specificity of slurry processes being to have a finely dispersed and unsupported catalyst on a mineral phase makes the recovery of metals much more complex than those of traditionally supported supported refining catalysts. The challenge for industrial development of hydroconversion processes using slurry technology is the need to recover and recycle metals from catalysts. The present invention aims to improve the methods of hydroconversion of heavy loads by slurry technology known by allowing the valuation of a residual unconverted fraction resulting from the conversion to slurry fraction highly concentrated in metals and heteroelements and ultimately including the recovery of said metals in said unconverted fraction and the production of catalytic precursors for recycling upstream of the conversion process in slurry mode.

The method comprises a hydroconversion step, a gas / liquid separation step, a liquid / liquid extraction step, a combustion step, a metal extraction step, and a catalytic solution (s) preparation step ( s) which is / are recycled in the hydroconversion stage. The research work carried out by the applicant on the hydroconversion of heavy loads led him to discover that, surprisingly, this process comprises a separation making it possible to maximize the light fraction resulting from the hydroconversion reactor and to minimize the residual fraction. , coupled with a liquid / liquid extraction step with aromatic and / or naphthenoaromatic and / or polar solvents at high temperature and a moderate combustion step avoiding the sublimation of metals, made it possible to prepare the extraction of the metals contained in the ashes of d in such a way that very good recovery rates of recyclable metals in the process are possible. Indeed, the critical stages of this recovery are first the concentration of the metals on the carbon matrix (via the extraction) then the formation of a mineral phase (via the moderate combustion) containing the metallic elements coming from the catalyst (Mo and Ni ) but also the charge (Ni, V and Fe) devoid of carbon. An advantage of the method according to the invention is the recovery of an unconverted residual fraction highly concentrated in metals and heteroelements for the recovery of said metals and the production of catalytic precursors for recycling upstream of the conversion process in slurry mode. Another advantage is the optimization of the hydroconversion conversion by a gas / liquid separation after the hydroconversion operating under operating conditions close to those of the reactor and allowing the effective separation in a single step of a light fraction comprising the future fuel bases (gases, naphtha, light gas oil or even heavy diesel) of the unconverted residual fraction containing solids such as metals. The yield of the light fraction is thus maximized at the same time that the unconverted residual fraction is minimized thereby facilitating the reduced concentration of the metals thereafter. Maintaining the operating conditions during the separation also allows the economical integration of a subsequent treatment of hydrotreating and / or hydrocracking of the light fraction without the need for additional compressors.

Another interest is the liquid / liquid extraction with aromatic solvents and / or naphtheno-aromatic and / or polar of the unconverted fraction and containing the metals at high temperatures allowing an extraction of insoluble (and therefore a concentration of metals) effective .

Another advantage of the process is the combustion at moderate temperature to separate the organic phase of the inorganic phase containing the metals to facilitate the subsequent extraction of metals from the inorganic phase while avoiding vaporization and / or sublimation (and therefore loss) of metals during combustion.

The method according to the invention therefore makes it possible to optimize the conversion of heavy charges into fuel base while allowing the recovery of metals with very good recovery rates.

DETAILED DESCRIPTION The invention relates to a process for hydroconversion of heavy petroleum slurry feeds for the recovery and recycling of metals in the unconverted residual fraction, especially those used as catalysts. More particularly, the invention relates to a process for hydroconversion of heavy metal-containing petroleum feedstocks comprising: a) a step of hydroconversion of the feedstock in at least one reactor containing a slurry catalyst containing at least one metal, and optionally a solid additive, b) a step of separating the hydroconversion effluent without decompression into a so-called light fraction containing the compounds boiling at at most 500 ° C and in a residual fraction, b ') optionally a fractionation step comprising a separation under vacuum of said residual fraction as obtained in step b), and there is obtained a vacuum residue concentrated in metals, c) a liquid / liquid extraction step of said residual fraction as obtained at step b) and / or said vacuum residue as obtained in step b ') at a temperature between 50 and 350 ° C by an aromatic solvent and / or naphtheno-aromatic and / or polar element making it possible to obtain a concentrated metal extract and a raffinate; d) a step of combusting said extract at a temperature of between 200 and 700 ° C making it possible to obtain concentrated ash of metals; e) a step of extracting the ash metals obtained in the combustion step, f) a step of preparing a metallic solution (s) containing at least the metal of the catalyst which is / are recycled as a catalyst in the step hydroconversion.

Hydroconversion The process according to the invention comprises a step of hydroconversion of the feedstock in at least one reactor containing a slurry catalyst and optionally a solid additive. Hydroconversion is understood to mean hydrogenation, hydrotreatment, hydrodesulfurization, hydrodenitrogenation, hydrodemetallization and hydrocracking reactions. The heavy loads concerned are petroleum hydrocarbon feedstocks such as petroleum residues, crude oils, crude heading oils, deasphalted oils, asphalts or deasphalting pitches, derivatives of petroleum conversion processes (for example: HCO, FCC slurry, GO heavy / VGO coking, visbreaking residue or similar thermal process, etc.), oil sands or their derivatives, oil shales or their derivatives, or mixtures of such fillers. More generally, herein will be grouped under the term "heavy load" hydrocarbon feeds containing at least 50 wt% of product distilling above 250 ° C and at least 25 wt% distilling above 350 ° C. The heavy charges concerned according to the invention contain metals, essentially V and / or Ni, at a rate of generally at least 50 ppm by weight and most often 100-2000 ppm by weight, at least 0.5% by weight of sulfur, and at least 1 wt.% of asphaltenes (asphaltenes to heptane), often more than 2 wt.% or 5 wt.%, levels of 25 wt.% or more of asphaltenes that can be reached also contain condensed aromatic structures may contain heteroelements refractory to conversion. Preferably, the heavy feedstocks concerned are unconventional oils of the heavy crude type (API ° between 18 and 25 and a viscosity of between 10 and 100 cP), the extra heavy mills (API ° between 7 and 20 and viscosity between 100 and 10,000 cP) and oil sands (API ° 7 to 12 ° API and a viscosity of less than 10,000 cP) present in large quantities in the Athabasca region of Canada and the Orinoco Venezuela where reserves are estimated at 1700 Gb and 1300 Gb respectively.

These unconventional oils are also characterized by high levels of residues under vacuum, asphaltenes and heteroelements (sulfur, nitrogen, oxygen, vanadium, nickel, etc.) which require conversion steps to commercial gasoline type products. specific diesel or heavy fuel oil.

The heavy charge is mixed with a hydrogen stream and a catalyst as dispersed as possible to obtain a hydrogenating activity as uniformly distributed as possible in the hydroconversion reaction zone. Preferably, a solid additive promoting the hydrodynamics of the reactor is also added. This mixture feeds the catalytic hydroconversion section into slurry. This section consists of a preheating furnace for the charge and hydrogen and a reaction section consisting of one or more reactors arranged in series and / or in parallel, according to the required capacity. In the case of series reactors, one or more separators may be present on the effluent at the head of each of the reactors. In the reaction section, hydrogen can feed one, several or all of the reactors in equal or different proportions. In the reaction section, the catalyst can feed one, several or all the reactors in equal or different proportions. The catalyst is kept in suspension in the reactor, flows from the bottom to the top of the reactor with the gas and the feedstock, and is evacuated with the effluent. Preferably, at least one (and preferably all) of the reactors is provided with an internal recirculation pump. The operating conditions of the slurry catalytic hydroconversion section are in general a pressure of 2 to 35 MPa, preferably 10 to 25 MPa, a hydrogen partial pressure ranging from 2 to 35 MPa and preferably from 10 to 25 MPa. , a temperature of between 300 ° C. and 500 ° C., preferably 420 ° C. to 480 ° C., a contact time of 0.1 h to 10 h with a preferred duration of 0.5 h to 5 h. These operating conditions coupled to the catalytic activity make it possible to obtain conversion rates per pass of the vacuum residue 500 ° C. + which can range from 20 to 95%, preferably from 70 to 95%. The conversion rate mentioned above is defined as the mass fraction of organic compounds having a boiling point greater than 500 ° C at the inlet of the reaction section minus the mass fraction of organic compounds having a boiling point. greater than 500 ° C at the outlet of the reaction section, all divided by the mass fraction of organic compounds having a boiling point greater than 500 ° C at the inlet of the reaction section. The slurry catalyst is in dispersed form in the reaction medium. It can be formed in situ but it is preferable to prepare it outside the reactor and inject it, usually continuously, with the charge. The catalyst promotes the hydrogenation of radicals from thermal cracking and reduces coke formation. When coke is formed, it is removed by the catalyst. The slurry catalyst is a sulfurized catalyst preferably containing at least one member selected from the group consisting of Mo, Fe, Ni, W, Co, V, Ru. These catalysts are generally monometallic or bimetallic (by combining, for example, a non-noble group VIIIB element (Co, Ni, Fe) and a group VIB element (Mo, W)). NiMo, Mo or Fe catalysts are preferably used. The catalysts used can be heterogeneous solid powders (such as natural ores, iron sulphate, etc.), dispersed catalysts derived from soluble precursors in the form of catalysts. water ("water soluble dispersed catalyst") such as phosphomolybdic acid, ammonium molybdate, or a mixture of Mo or Ni oxide with aqueous ammonia. Preferably, the catalysts used are derived from soluble precursors in an organic phase ("oil soluble dispersed catalyst"). The precursors are organometallic compounds such as the naphthenates of Mo, Co, Fe, or Ni or such as multi-carbonyl compounds of these metals, for example 2-ethyl hexanoates of Mo or Ni, acetylacetonates of Mo or Ni , C7-C12 fatty acid salts of Mo or W, etc. They can be used in the presence of a surfactant to improve the dispersion of metals, when the catalyst is bimetallic. The catalysts are in the form of dispersed particles, colloidal or otherwise depending on the nature of the catalyst. Such precursors and catalysts that can be used in the process according to the invention are widely described in the literature.

In general, the catalysts are prepared before being injected into the feed. The preparation process is adapted according to the state in which the precursor is and of its nature. In all cases, the precursor is sulfided (ex-situ or in-situ) to form the catalyst dispersed in the feedstock. For the preferred case of so-called oil-soluble catalysts, in a typical process, the precursor is mixed with a petroleum feedstock (which may be part of the feedstock to be treated, an external feedstock, a recycled feedstock, etc.). the mixture is optionally dried at least in part, then or simultaneously sulphurized by addition of a sulfur compound (H 2 S preferred) and heated. The preparations of these catalysts are described in the prior art.

The preferred solid additives are inorganic oxides such as alumina, silica, mixed Al / Si oxides, supported spent catalysts (for example, on alumina and / or silica) containing at least one group VIII element (such as Ni, Co) and / or at least one group VIB element (such as Mo, W). For example, the catalysts described in the application US2008 / 177124. Carbonaceous solids with a low hydrogen content (for example 4% hydrogen), possibly pretreated, can also be used. Mixtures of such additives can also be used. Their particle sizes are preferably less than 1 mm. The content of any solid additive present at the inlet of the reaction zone of the slurry hydroconversion process is between 0 and 10% by weight and preferably between 1 and 3% by weight, and the content of the catalytic solutions is between 0 and 10% by weight. % wt, preferably between 0 and 10/0 wt.

The known slurry technology heavy charge hydroconversion processes are EST of ENI operating at temperatures of the order of 400-420 ° C, under pressures of 10-16 MPa with a particular catalyst (molybdenite); (HC) 3 of Headwaters operating at temperatures of the order of 400-450 ° C, at pressures of 10-15 MPa with Fe pentacarbonyl or Mo 2-ethyl hexanoate, the catalyst being dispersed in the form of HDI and HDHPLUS colloidal particles licensed by Intevep / PDVSA operating at temperatures of the order of 420-480 ° C, at pressures of 7-20 MPa, using a dispersed metal catalyst; Chevron CASH using a Mo or W sulfide catalyst prepared by aqueous means; SRC-Uniflex UOP operating at temperatures of the order of 430-480 ° C, under pressures of 10-15 MPa; VCC developed by Veba and belonging to BP operating at temperatures of the order of 400-480 ° C, at pressures of 15-30 MPa, using an iron-based catalyst; Microcat of Exxonmobil; etc ...

All these slurry processes can be used in the process according to the invention. Separation All the effluent resulting from the hydroconversion is directed to a separation section, generally in a high pressure and high temperature separator (HPHT), which makes it possible to separate a fraction converted into the gaseous state, called the light fraction, and a liquid unconverted fraction containing solids, said residual fraction. This separation section is preferably carried out under operating conditions close to those of the reactor, which are in general a pressure of 2 to 35 MPa with a preferred pressure of 10 to 25 MPa, a hydrogen partial pressure ranging from 2 to 35 MPa. and preferably from 10 to 25 MPa and a temperature of between 300 ° C and 500 ° C, preferably 380 ° C to 460 ° C. The residence time of the effluent in this separation section is 0.5 to 60 minutes and preferably 1 to 5 minutes. The light fraction contains, for the most part, the compounds boiling at at most 300 ° C., or even at most 400 ° C. or 500 ° C .; they correspond to the compounds present in gases, naphtha, light diesel or even heavy diesel. It is indicated that the cut contains very predominantly these compounds, because the separation is not made according to a precise cutting point, it is more like a flash. If we had to speak in terms of cutting point, we could say that it is between 200 ° and 400 ° or 450 ° C.

The valorization of the light fraction is not the subject of the present invention and these methods are well known to those skilled in the art. The light fraction obtained after the separation can undergo at least one hydrotreatment and / or hydrocracking step, the objective being to bring the different cuts to the specifications (sulfur content, smoke point, cetane, aromatic content, etc ...). The light fraction may also be mixed with another feed before being directed to a hydrotreatment and / or hydrocracking section. An external cut generally coming from another process existing in the refinery or possibly outside the refinery can be brought before the hydrotreatment and / or the hydrocracking, advantageously the external cut is for example the VGO resulting from the fractionation of the crude oil ( VGO straight-run), VGO from a conversion, a LCO (light cycle garlic) or a HCO (heavy cycle oil) from FCC. In general, hydrotreatment and / or hydrocracking after hydroconversion can be done conventionally via a conventional intermediate separation section (with decompression) using, for example, after the high-pressure high-temperature separator, a high separator. low temperature pressure and / or atmospheric distillation and / or vacuum distillation. Preferably, the hydrotreatment and / or hydrocracking section is directly integrated into the hydroconversion section without intermediate decompression. In this case, the light fraction is sent directly, without additional separation and decompression steps to the hydrotreatment and / or hydrocracking section. This last embodiment makes it possible to optimize pressure and temperature conditions, avoids additional compressors and thus minimizes the costs of additional equipment. The residual fraction resulting from the separation (for example via the HPHT separator) and containing the metals and a fraction of solid particles used as a possible additive and / or formed during the reaction can be directed to a fractionation step. This fractionation is optional and comprises a vacuum separation, for example one or more flash flasks and / or, preferably, a vacuum distillation, making it possible to concentrate a metal-rich vacuum residue at the bottom of the flask or column. recover at the head of the column one or more effluents. Preferably, the residual fraction resulting from the decompression-free separation step is fractionated by vacuum distillation into at least one vacuum distillate fraction and a vacuum residue fraction, at least a portion and preferably all of said fraction residue under vacuum being sent to the liquid-liquid extraction step, at least a portion and preferably all of said vacuum distillate fraction being preferably subjected to at least one hydrotreatment and / or hydrocracking step. The liquid effluent (s) of the vacuum distillate fraction thus produced is (are) usually directed for a small portion to the slurry hydroconversion unit where they can be directly recycled. in the reaction zone or then it (s) can (wind) be used for the preparation of catalytic precursors before injection into the load. Another part of the effluent (s) is directed towards the hydrotreating and / or hydrocracking section, optionally mixed with other fillers, for example the light fraction derived from the HPHT separator or a vacuum distillate originating from of another unit, in equal or different proportions depending on the quality of the products obtained. The objective of the vacuum distillation is to increase the efficiency of the liquid effluents for a subsequent treatment of hydrotreatment and / or hydrocracking and thus to increase the yield of fuel bases. At the same time, the amount of the residual fraction containing the metals is reduced, thus facilitating the concentration of the metals.

Liquid-liquid extraction The residual fraction resulting from the no-decompression separation (via the HPHT separator, for example) and / or the vacuum residue fraction of the vacuum separation (for example, withdrawn at the bottom of the vacuum distillation column) are then directed to a extraction stage of the liquid / liquid type. This step has the objective of concentrating the metals in the effluent to be subsequently treated by combustion, by reducing its quantity, and to maximize the liquid effluent yield for the hydrotreatment and / or hydrocracking treatment. The extraction is carried out at high temperature and with the aid of an aromatic and / or naphtheno-aromatic and / or polar solvent, mixed or not in equal or different proportions, said solvents preferably having high temperatures. boiling. The liquid / liquid extraction can be done in a mixer-settler or in an extraction column. This extraction is distinguished from the deasphalting known from the prior art by the use of aromatic solvents and / or naphtheno-aromatic and / or polar allowing a better separation of insoluble (containing the metals) compared to paraffinic solvents and also by a temperature higher extraction rate as necessary to maintain the fraction in the liquid phase. The extraction step can be carried out in one step or, preferably, in two steps. According to the embodiment of a liquid / liquid extraction in one step, the operating conditions are in general a solvent / charge ratio of 0.5 / 1 to 20/1, preferably of 1/1 to 5/1, a temperature profile. between 50 ° C and 350 ° C, preferably between 150 ° C and 300 ° C. The solvent used in the case of a one-step extraction is preferably aromatic and / or naphthenoaromatic and / or polar. As an aromatic solvent, toluene, xylene, a BTX mixture, phenol, cresols or their methyl derivatives, or a mixture of these solvents, or a diaromatic solvent such as alpha-methyl napthalene, but also rich cuts can be used. in aromatics such as LCO, HCO, aromatic extracts or heavy GO or GO cuts, mixed or not in equal or different proportions. It can directly come from the process or any other refining process, such as fluidized catalytic cracking (solvent type LCO / HCO) or aromatic extraction units of lubricating base production lines. As a naphtheno-aromatic solvent, it is possible to use tetralin, indane, indene or a mixture of these solvents, as well as heavy GO or GO cuts resulting from the process or from any other refining process, whether or not mixed in equal or different proportions. As polar solvent can be used furfural, NMP (N-methyl-2-pyrrolidone), sulfolane, DMF (dimethylformamide), quinoline, THF (tetrahydrofuran), or a mixture of these solvents in equal proportions or different. The solvent must be chosen having a sufficiently high boiling point in order to be able to fluidize the residual fraction from the HPHT separator and / or the residue under vacuum without vaporizing, the residual fraction and / or the residue under vacuum being typically conveyed to temperatures between 200 and 300 ° C. After contact of the solvent with the residual fraction and / or the residue under vacuum, two phases are formed, the extract consisting of the parts of the non-soluble residue in the solvent (and concentrated in metals) and the raffinate consisting of the solvent and the solvents. parts of the soluble residue. The solvent is distilled off from the soluble parts and recycled internally to the liquid / liquid extraction process; the management of the solvent being known to those skilled in the art. At least a part of the soluble fraction after distillation of the solvent, and preferably all, is advantageously mixed with the heavy hydrocarbon feedstock upstream of the slurry hydroconversion section. A smaller portion may also be mixed with the light fraction of the HPHT separator for subsequent hydrotreatment and / or hydrocracking treatment. According to the embodiment of a two-stage liquid / liquid extraction, a first extraction step is carried out with an aromatic and / or naphtheno-aromatic and / or polar solvent, followed by a second extraction step. with a paraffinic type solvent. In the case of two-stage liquid / liquid extraction, the first extraction step is strictly identical to that described above for the one-step extraction. After contact of the aromatic solvent and / or naphtheno-aromatic and / or polar with the residual fraction and / or the residue under vacuum, two phases are formed, the extract consisting of the parts of the residue not soluble in the solvent (and concentrated in metals) and the raffinate is the solvent and parts of the soluble residue. This soluble phase, after distillation of the solvent, is sent to the second liquid-liquid extraction step. This extraction is carried out with a paraffinic type solvent, such as propane, butane, pentane, hexane, heptane, light naphtha resulting from the process (after the hydrotreatment and / or hydrocracking treatment, for example) or from any other refining process, whether or not mixed in equal or different proportions. The operating conditions are in general a solvent / filler ratio of 1/1 to 10/1 preferably of 2/1 to 7/1, a temperature profile of between 50 ° C. and 300 ° C., preferably between 120 ° C. and 250 ° C. ° C according to the solvent in question. After contact with the paraffinic solvent, two phases are formed. The extract consists of non-soluble solvent-containing portions of the resin containing highly polar resins and asphaltenes and the raffinate contains soluble portions containing no or very few asphaltenes. Due to its low concentration of asphaltene, at least a portion of the raffinate, and preferably all, can be mixed after separation of the solvent with the light fraction of the HPHT separator for a hydrotreatment and / or hydrocracking treatment.

At least a portion of the fraction, and preferably all of the extract containing highly polar resins and asphaltenes is preferably recycled upstream of the slurry hydroconversion section. The liquid / liquid extraction in two stages thus makes it possible, thanks to the choices of different solvents, to separate the raffinate from the first extraction step into a fraction containing less asphaltenes and thus adapted to a direct treatment of hydrotreatment and / or or hydrocracking (thus to an optimization of the process at the level of fuel bases) and a fraction containing more asphaltenes preferably requiring recycling to the slurry reactor.

Combustion The extract from liquid-liquid extraction in one stage or from the first two-stage extraction stage is highly concentrated in metals. This extract is directed to a moderate temperature combustion step. Indeed, before metals can be recovered by conventional metal mining methods, a preliminary step is necessary to separate the organic phase from the inorganic phase containing the metals. Thus, the objective of the combustion step is to obtain ash containing easily recoverable metals in the subsequent metal recovery units, by burning the organic phase or carbon phase of the extract at a temperature and a pressure which limit the vaporization and / or sublimation of metals, especially that of molybdenum (sublimation temperature of about 700 ° C. for MoO3). Thus, the step of reducing the organic phase consists of a combustion at moderate temperature in order to concentrate the metals, without significant loss by vaporization and / or sublimation towards the fumes, in a mineral phase which may contain a proportion of organic phase ranging from 0 to 100 wt%, preferably 0 wt% to 40 wt%. The operating conditions of this combustion are generally a pressure of 0.1 to 1 MPa, preferably of 0.1 to 0.5 MPa, a temperature of 200 to 700 ° C., preferably of 400 to 550 ° C. The combustion is done in the presence of air. The gaseous effluent resulting from the combustion requires purification steps in order to reduce the emission of sulfur and nitrogen compounds into the atmosphere. The processes conventionally used by those skilled in the field of air treatment are carried out under the operating conditions necessary to meet the standards in force in the country of operation of such a hydrocarbon feedstock treatment. . The solid resulting from the combustion is a mineral phase containing in whole, or almost all, the metal elements contained in the extract, in the form of ash. The direct treatment of the extract of the liquid / liquid extraction by a method of metal extraction as described below without combustion shows an insufficient metal recovery rate. Metal Recovery Ashes from combustion are sent to a metal extraction step in which the metals are separated from one another in one or more substeps. This metal recovery is necessary because the simple ash recycle in the hydroconversion step shows very low catalytic activity. In general, the metal extraction step makes it possible to obtain several effluents, each effluent containing a specific metal, for example Mo, Ni or V, generally in salt or oxide form. Each catalyst metal-containing effluent is directed to a step of preparing an aqueous or organic metal-based solution identical to the catalyst or precursor thereof used in the hydroconversion step. The effluent containing a metal from the feed being non-recoverable as a catalyst (such as vanadium for example) can be recovered outside the process. The operating conditions, fluids and / or extraction methods used for the various metals are considered to be known to those skilled in the art and already used industrially, as for example described in Marafi et al., Resources, Conservation and Recycling 53 (2008) 1-26, US4432949, US4514369, US4544533, US4670229 or US2007 / 0025899. The various known metal extraction routes generally include leaching by acidic and / or basic solutions, ammonia or ammonia salts, bioleaching by microorganisms, low temperature heat treatment ( roasting) by sodium or potassium salts, chlorination or the recovery of metals electrolytically. The acid leaching may be by inorganic acids (HCl, H 2 SO 4, HNO 3) or organic acids (oxalic acid, lactic acid, citric acid, glycolic acid, phthalic acid, malonic acid, succinic acid, salicylic acid, tartaric acid. ..). For basic leaching, ammonia, salts of ammonia, sodium hydroxide or Na2CO3 are generally used. In both cases, oxidizing agents (H2O2, Fe (NO3) 3, Al (NO3) 3 ...) may be present to facilitate extraction. Once the metals in solution, they can be isolated by selective precipitation (at different pH and / or with different agents) and / or by extraction agents (oximes, beta-diketone ...).

Preferably, the metal extraction step according to the invention comprises leaching with at least one acidic and / or basic solution.

Preparation of Catalytic Solution (s) The metals recovered after the extraction step are generally in salt or oxide form. The preparation of the catalytic solutions for producing the organic or aqueous solutions is known to those skilled in the art and has been described in the hydroconversion part. The preparation of catalytic solutions concerns especially molybdenum and nickel metals, vanadium being generally valorized as vanadium pentoxide, or in combination with iron, for the production of ferrovanadium, outside the process. The recovered metal recovery rate as a catalyst for the hydroconversion process in slurry or for vanadium is at least 50 wt%, preferably at least 65 wt% and more generally 70 wt%. Description of the Figures The following figures show advantageous embodiments according to the invention. The installation and the method according to the invention are essentially described. We will not repeat the operating conditions described above.

Figure 1 shows a process of hydroconversion of heavy oil loads incorporating a slurry technology without recovery of metals. FIG. 2 describes a method of hydroconversion of heavy petroleum feedstocks according to the invention integrating a liquid / liquid extraction in a single step. FIG. 3 describes a method of hydroconversion of heavy petroleum feedstocks according to the invention, incorporating a liquid / liquid extraction in two stages.

In FIG. 1, charge 1 feeds the catalytic hydroconversion section in slurry A. This slurry catalytic hydroconversion section consists of a preheating furnace for charge 1 and hydrogen 2 and a reaction section. consisting of one or more reactors arranged in series and / or in parallel, according to the required capacity. The catalyst 4 or its precursor is also injected, as well as the optional additive 3. The catalyst 4 is kept in suspension in the reactor, flows from the bottom to the top of the reactor with the feedstock, and is evacuated with the effluent. The effluent 5 resulting from the hydroconversion is directed to a high-pressure and high-temperature separation section B which makes it possible to separate a fraction converted into the gaseous state 6, called the light fraction, and a residual unconverted liquid / solid fraction. 8. The light fraction 6 can be directed to a hydrotreatment and / or hydrocracking section C. An external cut 7 generally coming from another process existing in the refinery or possibly outside the refinery can be brought before the hydrotreatment and / or hydrocracking. The unconverted residual fraction 8 containing the catalyst and a solid particle fraction optionally used as an additive and / or formed during the reaction is directed to a fractionation step D. Fractionation step D is preferably vacuum distillation. making it possible to concentrate at the bottom of the column the metal-rich vacuum residue and to recover at the top of the column one or more effluents 9. In this scheme for upgrading a heavy load by a hydroconversion process in slurry used traditionally, the residue The metal-rich vacuum is used as a very high-viscosity fuel or as a solid fuel after pelleting, for example to produce heat and electricity on site or outside or as fuel in a cement plant. Metals are, a priori, not recovered. The effluent (s) 9 thus produced will (are) usually be directed via line 24 to a small extent to the A slurry hydroconversion unit where they can be directly recycled to the reaction zone or it (s) can (wind) be used for the preparation of catalytic precursors before injection in the feedstock 1 and for the other part to the hydrotreating and / or hydrocracking unit C via the line 25 mixed with the effluents 6 and or 7 in equal or different proportions depending on the quality of the products obtained. In FIG. 2, the steps (and reference marks) for hydroconversion, HPHT separation, hydrotreatment and / or hydrocracking and vacuum distillation are identical to FIG. vacuum distillation D is directed to a liquid / liquid E extraction step to concentrate effluent 10. This extraction step E is carried out in one step and is carried out using a solvent 11 of aromatic and / or naphtheno-aromatic and / or polar type. The raffinate 12 leaving the extraction unit, after evaporation of the solvent, is preferably mixed via line 27 with the hydrocarbon feedstock 1 upstream of the hydroconversion section in slurry A, or mixed via line 28 with the effluent 6 and / or 7 upstream of the hydrotreating and / or hydrocracking section C. The highly concentrated metal extract 13 is directed to a step of reducing the organic phase by a moderate temperature combustion F to very strongly concentrate the metals, without significant loss by vaporization and / or sublimation towards the fumes. The gaseous effluent from combustion 14 requires purification steps (not shown) to reduce the emission of sulfur and nitrogen compounds into the atmosphere. The product 15 resulting from the combustion F is a mineral phase containing all, or almost all, the metal elements contained in the extract 13, in the form of ash. The product described below is sent to a metal extraction step G in which the metals are separated from one another in one or more sub-steps. The effluent 16 from the extraction G is composed of a molybdenum type metal in the form of salt or oxide. This effluent 16 is then directed to a preparation step H of an organic or aqueous solution based on molybdenum 18 identical to the catalyst 4 or its precursor recycled partially or wholly in the hydroconversion step in slurry A via the line 40. The effluent 17 from the extraction G is composed of a nickel-type metal in the form of salt or oxide. This effluent 17 is then directed to a preparation step I of an organic or aqueous nickel-based solution 19 identical to the catalyst 4 or its precursor recycled partially or wholly in the hydroconversion step in slurry A via the line 41. The effluent 20 from the extraction G is composed of a vanadium type metal in salt or oxide form. This effluent can be recovered for example as vanadium pentoxide, or in combination with iron, for the production of ferrovanadium. In FIG. 3 the steps (and reference marks) of hydroconversion, HPHT separation, hydrotreatment and / or hydrocracking and vacuum distillation are identical to FIG. 1. The vacuum residue 10 withdrawn at the bottom of Vacuum distillation D is directed to a liquid-liquid extraction step E1 to concentrate the residue under vacuum 10. According to this embodiment, the extraction step is carried out in two steps E1 and E2. The first step E1 is carried out using a preferentially aromatic solvent 11 and / or naphtheno-aromatic and / or polar. The raffinate 12 is sent to the second liquid-liquid extraction step E2. Step E2 is carried out with a solvent 21 of paraffinic type. The raffinate 22 leaving the second extraction stage, which does not contain asphaltenes, can then be mixed via the line 30 with the effluent 6 and / or 7 upstream of the hydrotreatment section and / or hydrocracking C whereas the extract 23 containing very polar resins and asphaltenes is recycled via line 32 to the hydroconversion section in slurry A, mixed with the feedstock 1. The extract 13 from the first step of El liquid-liquid extraction and highly concentrated in metals is directed to a step of reducing the organic phase by a low temperature combustion F to very strongly concentrate the metals, without significant loss by vaporization and / or sublimation to the fumes. The gaseous effluent 14 resulting from the combustion requires purification steps in order to reduce the emission of sulfur and nitrogen compounds into the atmosphere (not shown). The product 15 resulting from the combustion F is a mineral phase containing all, or almost all, the metal elements contained in the extract 13, in the form of ash. The product described below is sent to a metal extraction step G in which the metals are separated from one another in one or more sub-steps. The effluent 16 from the extraction G is composed of a molybdenum type metal in the form of salt or oxide. This effluent 16 is then directed to a preparation step H of an organic or aqueous solution based on molybdenum 18 identical to the catalyst 4 or its precursor recycled partially or wholly in the hydroconversion step in slurry A via the line 40. The effluent 17 from the extraction G is composed of a nickel-type metal in the form of salt or oxide. This effluent 17 is then directed to a preparation step I of an organic or aqueous nickel-based solution 19 identical to the catalyst 4 or its precursor recycled partially or wholly in the hydroconversion step in slurry A via the line 41. The effluent 20 from the extraction G is composed of a vanadium type metal in salt or oxide form.

In the preferred case of a slurry hydroconversion using molybdenum and nickel-based catalyst, the hydroconversion uses a finely dispersed catalyst of the nickel and molybdenum type with a concentration of 160 ppm by weight and 600 ppm by weight, respectively. 'hydrogen. Considering that the industrial unit has a capacity of 50,000 barrels per day and a utilization rate of 90% per year, the quantity of nickel and molybdenum consumed per year is therefore 0.4 and 1.6 kt / year respectively . Considering a cost of nickel of $ 25k / t and molybdenum of $ 60k / t, representative of the average costs observed on the metal market over the last 5 years, the operating cost is $ 100 million per year. The process according to the invention makes it possible to recover a large part of the metals, nickel and molybdenum, present in the unconverted fraction of the effluent resulting from hydroconversion into slurry. The recovered metal recovery rate as a catalyst for the slurry hydroconversion process is at least 50 wt%, preferably at least 65 wt%, and more generally 70 wt%. This recycling of metals can therefore reduce the operating cost from $ 100 million a year to $ 30 million a year. The saving thus achieved is 70 million dollars makes it possible initially to pay the additional investments necessary for the recovery of these metals. On the other hand, the vanadium present in the heavy load at 400 ppm wt can be valorized as ferrovanadium. Considering a recovery rate of at least 50 wt.%, Preferably at least 65 wt., And more generally 70 wt.%, The sale of vanadium is estimated, considering an observed average cost of $ 40k / t on the market. metals over the past 5 years, at $ 12 million a year. This sale will also make it possible in the first time to pay the additional investments necessary for the recovery of these metals. The recovery of these metals in the unconverted residual fraction reduces the overall quantity of nickel and molybdenum used and thus reduces the environmental impact of the slurry hydroconversion process. Considering a recovery of 70% by weight of the metals present at the inlet of the reaction zone, the amount of additional catalyst is reduced to 0.1 t / year for nickel and 0.5 t / year for molybdenum compared to 0.4 t / year and 1.6 t / year without recycle. 25 30

Claims (14)

REVENDICATIONS1. A method of hydroconversion of heavy petroleum feedstocks containing metals comprising: a) a step of hydroconversion of the feedstock in at least one reactor containing a slurry catalyst containing at least one metal, and optionally a solid additive, b) a step of separation of the hydroconversion effluent without decompression into a so-called light fraction containing the compounds boiling at at most 500 ° C and a residual fraction, b ') optionally a fractionation step comprising a vacuum separation of said residual fraction such that obtained in step b), and a metal-concentrated vacuum residue is obtained; c) a liquid / liquid extraction step of said residual fraction as obtained in step b) and / or said residue; under vacuum as obtained in step b ') at a temperature between 50 and 350 ° C by an aromatic solvent and / or naphtheno-aromatic and / or polar to obtain a concentrated extract metal and a raffinate, d) a step of combustion of said extract at a temperature between 200 and 700 ° C to obtain concentrated ash metal, e) a metal extraction step of the ash obtained in step f) a step of preparing metal solution (s) containing at least the metal of the catalyst which is / are recycled as a catalyst in the hydroconversion stage. 2. Method according to claim 1 wherein the liquid / liquid extraction step is carried out at a temperature between 150 ° and 350 ° C. 3. Method according to one of the preceding claims wherein the liquid / liquid extraction step is carried out with a solvent / charge ratio of 0.5 / 1 to 20/1, preferably 1/1 to 5/1. 4. Method according to one of the preceding claims wherein the raffinate from the liquid / liquid extraction step is subjected to a second liquid / liquid extraction step at a temperature between 50 and 300 ° C by a solvent paraffinic. 5. Method according to the preceding claim wherein the second liquid / liquid extraction step is carried out with a solvent / filler ratio of 1/1 to 10/1 preferably of 2/1 to 7/1, and at a temperature between 50 and 300 ° C, preferably between 120 and 250 ° C. 6. Method according to one of the preceding claims wherein said so-called light fraction from the step of separation without decompression is subjected to at least one hydrotreatment step and / or hydrocracking. 7. Method according to one of the preceding claims wherein said residual fraction from the decompression-free separation step is fractionated by vacuum distillation into at least one vacuum distillate fraction and a vacuum residue fraction, at least a portion and preferably all of said vacuum residue fraction being sent to the liquid / liquid extraction step, at least a portion and preferably all of said vacuum distillate fraction being subjected to at least one hydrotreating step and / or or hydrocracking. 8. Method according to one of the preceding claims wherein the combustion step operates at a pressure of 0.1 to 1 MPa, preferably 0.1 to 0.5 MPa and a temperature of 200 to 700 ° C, preferably 400 to at 550 ° C in the presence of air. 9. Method according to one of the preceding claims wherein the metal extraction step comprises leaching with at least one acidic solution and / or basic. 10. Method according to one of the preceding claims wherein the heavy oil load is a hydrocarbon feed containing at least 50% by weight of product distilling above 250 ° C and at least 25% by weight distilling above 350 ° C and contains at least 50 ppmw of metals, at least 0.5 wt% of sulfur and at least 1 wt% of asphaltenes (asphaltenes to heptane). 11. Method according to one of the preceding claims wherein the heavy oil load is selected from petroleum residues, crude oils, crude head oils, deasphalted oils, deasphalting asphalts, derivatives of petroleum conversion processes, oil sands or their derivatives, oil shales or their derivatives, or mixtures of such fillers. 12. Method according to one of the preceding claims wherein the hydroconversion step operates at a pressure of 2 to 35 MPa, preferably 10 to 25 MPa, a hydrogen partial pressure of 2 to 35 MPa, preferably 10 to 25 MPa, a temperature of between 300 ° C and 500 ° C, preferably 420 ° C to 480 ° C and a contact time of 0.lh to 10 h, preferably 0.5h to 5 h. 13. Method according to one of the preceding claims wherein the slurry catalyst is a sulfurized catalyst containing at least one element selected from the group consisting of Mo, Fe, Ni, W, Co, V, Ru. 14. Method according to one of the preceding claims wherein the additive is selected from the group consisting of inorganic oxides, supported spent catalysts containing at least one element of group VIII and / or at least one element of group VIB, the carbonaceous solids having a low hydrogen content or mixtures of such additives, said additive having a particle size of less than 1 mm.