FR3116828A1 - Process for capturing organometallic impurities using a capture mass based on cobalt and molybdenum and containing carbon - Google Patents

Abstract

The invention relates to a method for capturing organometallic impurities in a gasoline-type hydrocarbon feed containing sulfur compounds and olefins, in which a capture mass is brought into contact with the feed to be treated and a flow of hydrogen at a temperature between 200 and 400°C, a pressure between 0.2 and 5 MPa and a ratio of the hydrogen flow rate to the hydrocarbon feed flow rate of between 50 and 800 Nm3/m3, said capture mass comprises an active phase consisting of cobalt and molybdenum, carbon, and a porous support chosen from the group consisting of aluminas, silica, alumina silicas, or titanium or magnesium oxides used alone or mixed with alumina or silica alumina.

Description

Process for capturing organometallic impurities using a capture mass based on cobalt and molybdenum and containing carbon

Field of invention

The present invention relates to a process for capturing organometallic impurities contained in a gasoline-type hydrocarbon charge containing sulfur compounds and olefins using a capture mass based on cobalt and molybdenum and containing carbon.

State of the art

The present invention relates to the field of hydrotreating gasoline cuts, in particular gasoline cuts from fluidized bed catalytic cracking units. More particularly, the present invention relates to a process for capturing organometallic impurities such as organometallic impurities of heavy metals, silicon or phosphorus, and more particularly arsenic in hydrocarbon fractions of gasoline type rich in olefins and sulfur , implementing a capture mass.

The invention applies most particularly to the treatment of gasoline cuts containing olefins and sulfur, such as gasolines resulting from catalytic cracking, for which it is sought to extract the arsenic, without hydrogenating the olefins and the aromatics.

The specifications for automotive fuels provide for a sharp reduction in the sulfur content in these fuels, and in particular in gasolines. This reduction is intended to limit, in particular, the sulfur and nitrogen oxide content in automobile exhaust gases. The specifications currently in force in Europe since 2009 for gasoline fuels set a maximum sulfur content of 10 ppm by weight (parts per million). Such specifications are also in force in other countries such as the United States and China, for example, where the same maximum sulfur content has been required since January 2017. To achieve these specifications, it is necessary to treat gasoline with desulfurization processes.

The main sources of sulfur in gasoline bases are so-called cracked gasolines, and mainly the gasoline fraction resulting from a catalytic cracking process of a residue from the atmospheric or vacuum distillation of a crude oil. The fraction of gasoline resulting from catalytic cracking, which represents on average 40% of the gasoline bases, in fact contributes for more than 90% to the contribution of sulfur in gasolines. Consequently, the production of low-sulphur gasolines requires a stage of desulphurization of catalytic cracking gasolines. Other sources of gasoline that may contain sulfur include gasoline from coking, visbreaking (coker or visbreaker according to Anglo-Saxon terminology) or, to a lesser extent, gasoline from atmospheric distillation or gasoline from steam cracking.

The elimination of sulfur in gasoline cuts consists of specifically treating these sulfur-rich gasolines by desulfurization processes in the presence of hydrogen. This is referred to as hydrodesulphurization (HDS) processes. However, these gasoline cuts and more particularly the gasolines resulting from catalytic cracking contain a significant proportion of unsaturated compounds in the form of mono-olefins (approximately 20 to 50% by weight) which contribute to a good octane number, diolefins (0, 5 to 5% by weight) and aromatics. These unsaturated compounds are unstable and react during the hydrodesulfurization treatment. Diolefins form gums by polymerization during hydrodesulfurization treatments. This formation of gums leads to progressive deactivation of the hydrodesulphurization catalysts or progressive clogging of the reactor. Consequently, the diolefins must be eliminated by hydrogenation before any treatment of these gasolines. Traditional treatment processes desulphurize gasoline in a non-selective manner by hydrogenating a large part of the mono-olefins, which leads to a high loss in octane number and high hydrogen consumption. The most recent hydrodesulphurization processes make it possible to desulphurize cracked gasolines rich in mono-olefins, while limiting the hydrogenation of mono-olefins and consequently the loss of octane. Such methods are for example described in the documents EP-A-1077247 and EP-A-1174485.

The hydrodesulfurization processes are operated continuously over periods of at least 3 to 5 years. The catalysts used to carry out the hydrodesulfurization of sulfur-containing gasolines must therefore have good activity, good selectivity and good stability over time in order to be operated continuously for several years. However, the presence of heavy metals such as mercury or arsenic, or of contaminants such as phosphorus and silicon in the form of organometallics in the hydrocarbon feedstocks to be desulphurized leads to rapid deactivation of the hydrotreating catalysts. It is therefore necessary to remove these contaminants from the charge before bringing it into contact with these hydrodesulphurization catalysts.

State of the art

Different solutions are proposed in the literature for extracting these compounds and more particularly arsenic in hydrocarbon fractions. In general, a capture mass or adsorbent is placed either in a reactor located upstream of the hydrodesulphurization unit or in the hydrodesulphurization reactor, upstream of the catalytic bed containing the hydrodesulphurization catalyst. These capture masses are used in the presence of hydrogen, which presents a drawback when the gasolines to be treated comprise unsaturated compounds. This results in a decrease in octane number.

There is thus still a need to have more efficient capture masses for the selective extraction of heavy metals such as arsenic, in the presence of olefins, with the aim of limiting the hydrogenation reactions responsible in this context for a decrease in the octane number of the gasolines concerned.

Numerous patents describe arsenic capture masses using different active phases based on transition metals, generally partially in sulphide form.

Thus, US patent 4046674 describes a process for eliminating arsenic using a capture mass containing at least one nickel compound in sulphide form in an amount of between 30% and 70% by weight (relative to the NiO form), and at least one molybdenum compound, also in sulphide form, in an amount of between 2% and 20% by weight (relative to the MoO ₃ form). Patent CN107011939A also describes a process for eliminating arsenic using a capture mass comprising nickel and molybdenum but in an amount respectively between 2% and 20% by weight of NiO and between 2% and 10% by weight of MoO ₃ .

Patent FR 2617497 describes a process for removing arsenic from hydrocarbon cuts by contacting them with a capture mass containing nickel, of which at least 50% by weight is in metal form. A person skilled in the art is well aware of the hydrogenating properties of Ni and therefore expects that the direct application of such a capture mass will lead to a more or less significant hydrogenation of a large part of the olefins present in the cut. hydrocarbon to be treated, which does not answer the problem that the present invention seeks to solve.

Patent EP 0 611 182 describes a process for removing arsenic using a capture mass containing at least one metal from the nickel, cobalt, molybdenum, tungsten, chromium and palladium group, 5 to 50% by weight of said metals being in sulphide form.

Patent FR2876113 describes a process for eliminating arsenic using a capture mass comprising at least one metallic element chosen from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), lead (Pb) or zinc (Zn) deposited on a porous support chosen from the group consisting of aluminas, silica, silica aluminas, or titanium or magnesium oxides used alone or in a mixture with alumina or silica alumina, the metallic element being in sulphide form with a sulphidation rate at least equal to 60%, and preferably greater than 70%.

US patent 5024683 describes a process for at least partial elimination of trialkyl-arsines contained in a charge containing them comprising the step of bringing this charge into contact with a solid collection mass comprising at least one copper sulphide and a material of inorganic support.

US patent 6,759,364 and patent application US2016008795 describe catalysts suitable for capturing arsenic in hydrocarbon cuts containing nickel, molybdenum and phosphorus.

Patent application CN105562000 describes an arsenic capture agent based on copper and nickel, the metals being in oxide form.

Finally, patent FR3004969 describes a catalytic adsorbent comprising at least cobalt and molybdenum deposited on a porous support in which the cobalt content, expressed as CoO oxide, is between 11 and 30% by weight relative to the total weight of said adsorbent and the molybdenum content, expressed as oxide MoO3, is between 3 and 30% by weight relative to the total weight of said adsorbent.

In addition to the active phase, several patents also specify the type of support used for the arsenic capture mass. Thus applications CN106833731 and CN106807420 describe NiMoW type capture mass on a support composed of alumina and zinc oxide. Patent FR2650759 describes a NiO type capture mass on aluminate of at least one selected metal Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu and Zn. Patent application JP60202190 claims a capture mass for capturing the arsenic contained in a hydrocarbon charge, the capture mass consisting of nickel oxide and molybdenum oxide supported on a composite support prepared by mixing oxides selected from zirconia, magnesium oxide and barium oxide with alumina. The patent application describes an arsenic capture agent based on copper and nickel on an alumina support having a bimodal porous distribution.

Finally, patents relate to specific processes for capturing arsenic.

Patent FR3007415 describes a process for removing arsenic from a hydrocarbon charge comprising bringing this charge into contact with two capture masses comprising for the first mass at least one metal M1 from group VIB and at least two metals M2 and M3 of group VIII, and for the second mass of nickel in sulphide form, the contact with the two masses being able to be made either successively or simultaneously.

Patent FR2923837 describes a fixed bed process for capturing arsenic and desulfurization of a hydrocarbon fraction comprising olefins, sulfur and arsenic, the first step of which consists of bringing it into contact in the presence of hydrogen a capture mass with said hydrocarbon fraction, said capture mass comprising molybdenum and nickel in sulphide form.

Patent JP5171161 claims a process for removing arsenic from a liquid hydrocarbon charge consisting of bringing the charge into contact, in the absence of hydrogen, with a capture mass containing molybdenum sulphide and optionally cobalt and nickel.

Finally, patents CN109251764 and CN106925214 describe arsenic masses on mixed alumina/carbon supports. Patent CN109251764 claims an arsenic removal agent comprising a carrier and an active phase supported on the carrier, characterized in that the carrier is a mixture of activated carbon and alumina, and the active phase is a system quadrimetallic Ni-Cu-Mo-Co. CN106925214 describes a method for preparing an arsenic removal agent for FCC gasolines, based on copper and nickel, prepared by co-mixing a carbon support precursor and an alumina precursor , then adding copper and nickel salts to the mixer.

Objects of the invention

The present invention relates to a process for capturing organometallic impurities such as organometallic impurities of heavy metals, silicon or phosphorus, and more particularly arsenic in a gasoline-type hydrocarbon charge containing sulfur compounds and olefins, in which a capture mass is brought into contact with the charge to be treated and a hydrogen flow at a temperature between 200 and 400°C, a pressure between 0.2 and 5 MPa and a ratio of the hydrogen flow to the hydrocarbon feed rate of between 50 and 800 Nm³/m³, said capture mass comprises an active phase consisting of cobalt and molybdenum, carbon, and a porous support chosen from the group consisting of aluminas, silica, silica aluminas, or titanium or magnesium oxides used alone or mixed with the alumina or silica alumina.

It has indeed been surprisingly discovered that the implementation of this capture mass makes it possible to effectively capture organometallic impurities, and in particular the arsenic contained in a gasoline containing olefins and sulfur, while limiting the rate of hydrogenation of the olefins at values generally below 30%, preferably below 20%, and even more preferably below 10%.

Without being bound by any theory, it seems that the presence of carbon in the capture mass containing a porous support and an active phase consisting of cobalt and molybdenum makes it possible to very effectively capture organometallic impurities, and in particular organometallic arsenic impurities. contained in gasoline containing olefins and sulphur. It is proposed that the carbon placed in the capture mass makes it possible to accumulate hydrogen inside the pores of the carbon and promotes the hydrogenolysis reactions of the carbon-arsenic bonds. The presence of carbon in the capture mass can also promote the stacking of molybdenum sulphide sheets and the promotion of the latter by cobalt, thus favoring the CoMoS type II active phase favorable to hydrogenolysis reactions of carbon-heteroelement bonds. with respect to hydrogenation reactions.

According to a variant, the molybdenum content is between 5 and 40% by weight, expressed as molybdenum oxide relative to the total weight of the capture mass.

According to a variant, the cobalt content is between 1 and 10% by weight, expressed as cobalt oxide relative to the total weight of the capture mass.

According to a variant, the cobalt to molybdenum molar ratio is between 0.1 and 0.8.

According to a variant, the carbon content, expressed as carbon element, is between 0.5 and 80% by weight relative to the total weight of the capture mass.

According to a variant, the capture mass also contains sulfur, the sulfur content of the capture mass, expressed as sulfur element, is between 1 and 8% by weight relative to the total mass of the capture mass.

According to a variant, the active phase of the capture mass is sulfurized in situ.

According to a variant, the feed to be treated is a gasoline from catalytic cracking containing between 5% and 60% by weight of olefins, 50 ppm to 6000 ppm by weight of sulfur, as well as traces of arsenic in contents of between 1 ppb and 1000 ppb weight.

According to a variant, the organometallic impurities are chosen from heavy metals, silicon, phosphorus and arsenic.

According to a variant, said capture mass is placed in a reactor located upstream of a hydrodesulfurization unit containing a hydrodesulfurization catalyst and/or of a selective hydrogenation unit containing a catalyst for the selective hydrogenation of said charge .

According to another variant, said capture mass is placed inside a reactor for the hydrodesulphurization and/or selective hydrogenation of said charge, at the head of said reactor.

According to these two variants, the volume ratio of said capture mass relative to the volume of said hydrodesulfurization and/or selective hydrogenation catalyst is between 1 and 99%, preferably between 2 and 70% and preferably between 4 and 50%.

Definitions

In the following, the groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor-in-chief DR Lide, ^81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

By specific surface area is meant the BET specific surface area (S _BET in m ² /g) determined by nitrogen adsorption in accordance with the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT-TELLER method described in the periodical " The Journal of American Society ", 1938, 60, 309.

By total pore volume of the capture mass or of the support used for the preparation of the capture mass according to the invention is meant the volume measured by intrusion with a mercury porosimeter according to the ASTM D4284-83 standard at a maximum pressure of 4000 bar. (400 MPa), using a surface tension of 484 dyne/cm and a contact angle of 140°. The wetting angle was taken as equal to 140° by following the recommendations of the work “Engineering techniques, treatise on analysis and characterization”, pages 1050-1055, written by Jean Charpin and Bernard Rasneur. In order to obtain better precision, the value of the total pore volume corresponds to the value of the total pore volume measured by intrusion with a mercury porosimeter measured on the sample minus the value of the total pore volume measured by intrusion with a mercury porosimeter measured on the same sample for a pressure corresponding to 30 psi (about 0.2 MPa).

The cobalt and molybdenum contents are measured by X-ray fluorescence.

The cobalt and molybdenum and phosphorus contents when present in the capture mass are expressed in oxides after correction of the loss on ignition of the capture mass sample at 550°C for two hours in a muffle furnace . Loss on ignition is due to moisture loss. It is determined according to ASTM D7348.

Detailed description of the invention

The present invention relates to a process for capturing organometallic impurities such as organometallic impurities of heavy metals, silicon or phosphorus, and more particularly arsenic in a gasoline-type hydrocarbon charge containing sulfur compounds and olefins, in which a capture mass is brought into contact with the charge to be treated and a flow of hydrogen at a temperature of between 200 and 400°C, a pressure of between 0.2 and 5 MPa and a ratio of the flow of hydrogen to the hydrocarbon feed rate of between 50 and 800 Nm³/m³, said capture mass comprises an active phase consisting of cobalt and molybdenum, carbon, and a porous support chosen from the group consisting of aluminas, silica, silica aluminas, or titanium or magnesium oxides used alone or mixed with the alumina or silica alumina.

Within the meaning of the present invention, the capture process according to the invention is a process for at least partial capture of arsenic and optionally of silicon from the hydrocarbon feedstock in the presence of hydrogen to produce an effluent with a heavy metal content. and especially reduced arsenic, with limited loss of octane rating. The capture process according to the invention makes it possible to eliminate the arsenic and also to limit the rate of hydrogenation of the mono-olefins. The degree of hydrogenation of the olefins is advantageously less than 50%, preferably less than 30%, and even more preferably less than 20% and particularly more preferably less than 10%.

The process according to the invention makes it possible to treat any type of gasoline cut containing sulfur compounds and olefins, such as for example a cut from a coking unit (coking according to the Anglo-Saxon terminology), visbreaking (visbreaking according to Anglo-Saxon terminology), steam cracking (steam cracking according to Anglo-Saxon terminology) or catalytic cracking (FCC, Fluid Catalytic Cracking according to Anglo-Saxon terminology). This gasoline may optionally be composed of a significant fraction of gasoline from other production processes such as atmospheric distillation (gasoline from direct distillation (or straight run gasoline according to Anglo-Saxon terminology) or from conversion (gasoline from coking or steam cracking) Said feed preferably consists of a gasoline cut from a catalytic cracking unit.

The feed is advantageously a gasoline cut containing sulfur compounds and olefins and has a boiling point of between 30 and less than 250°C, preferably between 35°C and 240°C, and preferably between 40°C and 220°C.

Preferably, the hydrocarbon feedstock to be treated is a catalytic cracking gasoline comprising between 5% and 60% by weight of mono-olefins, between 50 ppm and 6000 ppm by weight of sulfur compounds and between 1 and 1000 ppb by weight of arsenic.

The sulfur compounds contained in the hydrocarbon feedstock to be treated can be organic sulfur compounds such as, for example, mercaptans, thiophenic, benzothiophenic compounds and other aromatic sulfur compounds, disulphide compounds, etc. The arsenic compounds contained in the hydrocarbon feedstock to be treated can be organic arsenic compounds such as, for example, trimethylarsine or triethylarsine. Mono-olefins designate hydrocarbon molecules having a single carbon-carbon double bond and diolefins are hydrocarbon molecules comprising at least two carbon-carbon double bonds. Mono-olefins and diolefins can be linear, branched and/or cyclic hydrocarbon molecules.

The capture mass is advantageously implemented under operating conditions such that the rate of capture of arsenic is maximized, while limiting the rate of hydrogenation of the olefins. The contacting is generally carried out at a temperature between 200 and 400° C., at a pressure between 0.2 and 5 MPa and with a ratio of the hydrogen flow rate to the hydrocarbon feed flow rate of between 50 and 800 Nm ³ /m ³ . The hydrogen used can come from any source of hydrogen. Preferably, fresh hydrogen from the refinery and/or hydrogen recycled from a hydrodesulfurization unit, preferably from the hydrodesulfurization unit of the hydrocarbon cut to be purified, is used.

Several reactor technologies can be envisaged for carrying out the capture of arsenic from a hydrocarbon charge in the presence of the capture mass according to the invention, the most classic and most widespread technology being the fixed bed technology. In this case, a reactor is charged with the capture mass according to the invention and a hydrodesulphurization catalyst, operating in adsorption of arsenic and in hydrodesulphurization, in principle until the appearance of arsenic in the effluent output (phenomenon known to those skilled in the art as drilling). In some cases the total amount of poisoned catchment mass can be replaced by an equivalent amount of fresh catchment mass. The choice of a technology for replacing the capture mass according to the invention is not considered within the scope of the present invention as a limiting element. The capture mass can be implemented in a moving bed reactor, that is to say that the used capture mass is continuously withdrawn and replaced by fresh capture mass. This type of technology makes it possible to maintain the capture of arsenic by the capture mass and to avoid the penetration of the latter in the effluents produced. Among other solutions, let us mention the implementation of expanded bed reactors which also allows continuous withdrawal and make-up of the capture mass in order to maintain the hydrodesulphurization activity of the capture mass.

Said capture mass of the process according to the invention comprises an active phase consisting of cobalt and molybdenum, carbon, and a porous support chosen from the group consisting of aluminas, silica, silica aluminas, or titanium or magnesium oxides used alone or as a mixture with alumina or silica alumina. It may additionally comprise phosphorus and/or sulfur.

The Applicant has found, surprisingly, that a capture mass which comprises cobalt and molybdenum as the active phase, as well as carbon and a porous support, not only has a good arsenic adsorption capacity but also a hydrodesulfurization activity and a selectivity in favor of hydrodesulfurization relative to the hydrogenation of olefins which are stable over time. The implementation of the adsorbent according to the invention makes it possible to simultaneously eliminate arsenic and sulfur from a hydrocarbon feedstock also comprising mono-olefins, for a long period of use, while selectively limiting the hydrogenation mono-olefins contained in said charge.

The active phase of the capture mass consists of cobalt and molybdenum. In particular, it does not include nickel or tungsten.

The total molybdenum and cobalt content (sum of the contents of these two metals) is advantageously greater than 6% by weight expressed as oxide (MoO ₃ and CoO) relative to the total weight of the capture mass.

The molybdenum content is between 5 and 40% by weight, preferably between 8 and 35% by weight, and more preferably between 10 and 30% by weight expressed as molybdenum oxide (MoO ₃ ) relative to the total weight of the mass of capture.

The cobalt content is between 1 and 10% by weight, preferably between 1.5 and 9% by weight, and more preferably between 2 and 8% by weight expressed as cobalt oxide (CoO) relative to the total weight of the capture mass.

The cobalt to molybdenum molar ratio (Co/Mo ratio) in the capture mass is preferably between 0.1 and 0.8, preferably between 0.15 and 0.6 and even more preferably between 0. 15 and 0.45.

The capture mass includes carbon. The carbon can be in and/or on the oxide support.

The carbon content, expressed as carbon element, is between 0.5 and 80% by weight, preferably between 5 and 50% by weight, preferably between 7 and 18% by weight and very preferably between 9 and 15% by weight. relative to the total weight of the capture mass. The carbon content is determined according to the ASTM D5373 method.

The carbon can come from the carbonization of one or more hydrocarbon compounds. The carbon can also be coke formed on the capture mass when used in a pre-capture process. It will be noted that the term "carbon" in the present application means a hydrocarbon-based substance deposited on the surface of the capture mass during its use, strongly cyclized and condensed and having an appearance similar to graphite.

It is important to emphasize that carbon is not in the form of an organic molecule.

The carbon content refers to the capture mass at the start of the capture process. As the process progresses, the carbon content may increase due to coke deposition.

The capture mass of the process according to the invention can also comprise phosphorus as a dopant. The dopant is an added element which in itself has no catalytic character but which increases the catalytic activity of the active phase.

The phosphorus content in said capture mass is preferably between 0.1 and 20% by weight expressed as P ₂ O ₅ relative to the total weight of capture mass, preferably between 0.2 and 15% by weight, and very preferably between 0.3 and 6% by weight.

The capture mass of the process according to the invention can also comprise sulphur.

The sulfur content in said capture mass is preferably between 1 and 8% by weight expressed as sulfur element, relative to the total weight of the capture mass, preferably between 1 and 6%, and very preferably between 2 and 5% by weight. Sulfur content is measured by elemental analysis according to ASTM D5373. The sulfur content of the capture mass refers to the total sulfur content of the capture mass possibly introduced during carbonization or already contained in a spent catalyst, taking into account the sulfur introduced by a possible activation (sulfidation ).

The capture mass of the process according to the invention has a total pore volume greater than or equal to 0.15 mL/g, preferably greater than or equal to 0.18 mL/g, and particularly preferably between 0.2 and 0.5mL/g.

The capture mass of the process according to the invention is characterized by a specific surface of between 20 and 200 m²/g, preferably between 30 and 180 m²/g, preferably between 40 and 160 m²/g, very preferably between 50 and 150 m²/g.

The capture mass of the process according to the invention is in the form of grains having an average diameter of between 0.5 and 10 mm. The grains can have any shape known to those skilled in the art, for example the shape of beads (preferably having a diameter of between 1 and 6 mm), extrudates, tablets, hollow cylinders. Preferably, the capture mass (and the support used for the preparation of the capture mass) are either in the form of extrudates with an average diameter of between 0.5 and 10 mm, preferably between 0.8 and 3.2 mm and with an average length of between 0.5 and 20 mm, or in the form of beads with an average diameter of between 0.5 and 10 mm, preferably between 1.4 and 4 mm. The term "average diameter" of the extrudates means the average diameter of the circle circumscribed to the cross section of these extrudates. The capture mass can advantageously be presented in the form of cylindrical, multi-lobed, tri-lobed or quadri-lobed extrudates. Preferably, its shape will be trilobed or quadrilobed. The shape of the lobes can be adjusted according to all known methods of the prior art.

The porous support of the capture mass according to the invention is a mineral support selected from the group consisting of aluminas, silica, silica-aluminas, titanium oxides alone or mixed with alumina or silica alumina , magnesium oxides alone or mixed with alumina or silica alumina. Preferably, the support is selected from the group consisting of aluminas, silica and silica-aluminas. Very preferably, the support consists essentially of at least one alumina, that is to say it comprises at least 51% by weight, preferably at least 60% by weight, very preferably at least 80% by weight , or even at least 90% by weight of alumina relative to the total weight of said support. Preferably, said support has an alumina content greater than or equal to 90% by weight relative to the total weight of said support, optionally supplemented by silica and/or phosphorus at a total content of at most 10% by weight in equivalent SiO ₂ and/or P ₂ O ₅ , preferably less than 5% by weight, and very preferably less than 2% by weight relative to the total weight of the support. The silica and/or the phosphorus can be introduced by any technique known to those skilled in the art, during the synthesis of the alumina gel or by impregnation of the support used for the preparation of the capture mass according to the invention.

Even more preferably, the support consists of alumina. Preferably, the alumina present in said support is a transition alumina such as a gamma, delta, theta, chi, rho or eta alumina, alone or as a mixture. More preferably, the alumina is a gamma, delta or theta transition alumina, alone or as a mixture.

The following characteristics of the support correspond to the characteristics of the support used for the preparation of the capture mass according to the invention before impregnation of the active phase and the introduction of carbon.

The support used for the preparation of the capture mass according to the invention generally has a total pore volume of between 0.1 and 1.5 mL/g, preferably between 0.4 and 1.1 mL/g, and particularly preferably between 0.70 and 1.0 mL/g.

The support used for the preparation of the capture mass according to the invention has a BET specific surface area of at least 40 m ² /g, preferably of at least 50 m²/g, and even more preferably of between 60 and 300 m ² /g, and preferably between 80 and 280 m ² /g.

The carbon contained in the capture mass can form with the support a composite oxide-carbon support with the support, in particular alumina-activated carbon. The support can also be at least partially covered with carbon (also called “carbon coated alumina” according to the Anglo-Saxon terminology).

The support may also contain at least a part of the cobalt and molybdenum, and/or at least a part of the phosphorus and/or at least a part of the sulfur which have been introduced outside of the impregnations (introduced for example during the preparation of the medium).

Process for preparing the capture mass

The capture mass of the process according to the invention can be prepared according to any mode of preparation of a capture mass known to those skilled in the art.

The capture mass of the process according to the invention can be prepared according to a preparation process comprising the following steps:

a) at least one hydrocarbon and one sulfur compound are brought into contact with said oxide support, making it possible to form carbon in or on the oxide support,

b) then a compound comprising a group VIB metal and a compound comprising a group VIII metal, and optionally phosphorus, are brought into contact with said oxide support containing carbon, so as to obtain a capture mass precursor,

c) said precursor is dried at a temperature below 200° C. without subsequent calcination, so as to obtain a dried capture mass,

d) the dried capture mass is optionally activated in the presence of a sulfurizing agent.

Step a) of bringing at least one hydrocarbon and one sulfur compound into contact with said oxide support making it possible to form said carbon can be carried out according to different variants. The preparation of the oxide support containing the carbon can be carried out by carbonization of an oxide support by bringing said oxide support into contact with at least one hydrocarbon chosen from olefins, dienes, mono- and polyaromatics and a sulfur compound, generally in the presence of a gas stream containing a gas chosen from nitrogen or hydrogen. Preferably, said hydrocarbon does not contain oxygen.

According to a first variant of carbonization, said carbon is formed by the method of chemical vapor deposition of olefinic and/or diene compounds.

According to this first variant, the carbon used in the process according to the invention is prepared by a process comprising a step of bringing into contact a gas comprising nitrogen or hydrogen, a sulfur compound, and a or more olefinic and/or diene hydrocarbons, with the oxide support at a temperature comprised between 500 and 900° C., a pressure comprised between 0.05 and 10 MPa and for a duration comprised between 0.25 and 12 hours. Said sulfur compound can be H ₂ S or a compound capable of decomposing into H ₂ S, such as for example dimethyldisulphide. Said olefinic and/or diene hydrocarbon is a molecule containing one or more unsaturations, advantageously of the olefin (ethylene, propylene, butene) or diene (isoprene, butadiene) type.

According to a second variant of carbonization, said carbon is formed by reaction of one or more hydrocarbons chosen from mono- or polyaromatic compounds. According to this second variant, the carbon used in the process according to the invention is prepared by a process comprising a step of bringing into contact a gas comprising nitrogen or hydrogen, a sulfur compound, and a or more hydrocarbons containing at least one aromatic nucleus, with the oxide support at a temperature of between 300 and 600° C., a pressure of between 0.05 and 10 MPa and for a duration of between 0.25 and 12 hours. Said sulfur compound can be H ₂ S or a compound capable of decomposing into H ₂ S, such as for example dimethyldisulphide. Said hydrocarbon is a molecule containing one or more aromatic nuclei, advantageously of the monoaromatic (benzene, toluene, ortho-xylene, meta-xylene, para-xylene, tetraline) or diaromatic type.

According to a third variant of carbonization, said carbon is formed by reaction of a hydrocarbon cut having at least 90% of the compounds whose boiling point is between 250°C and 400°C at atmospheric pressure.

This cut generally contains a mixture of several mono- or polyaromatic, olefinic and diene hydrocarbons. According to this third variant, the carbon used in the process according to the invention is prepared by a process comprising a step of bringing into contact a gas comprising nitrogen or hydrogen, at least one compound sulfur and a hydrocarbon cut having at least 90% of the compounds whose boiling point is between 250°C and 400°C at atmospheric pressure, with the oxide support at a temperature between 300 and 600°C , a pressure of between 0.05 and 15 MPa and a duration of between 0.25 and 12 hours. Said sulfur compound can be H ₂ S or a compound capable of decomposing into H ₂ S, such as dimethyl disulphide, or any other compound containing sulfur such as thiophene, alkyl thiophenes, benzothiophene, alkyl benzothiophenes , dibenzothiophene or alkyl dibenzothiophenes. Preferably, said cut does not contain oxygen.

According to step b) of the method for preparing the capture mass used according to the method of the invention, a compound comprising molybdenum and a compound comprising cobalt, and optionally phosphorus, are brought into contact with said porous support containing the carbon.

Bringing at least one compound comprising molybdenum and a compound comprising cobalt into contact with said porous support containing carbon can advantageously be carried out by any technique known to those skilled in the art, such as for example ion exchange, dry impregnation, excess impregnation, vapor deposition, etc. The bringing into contact can take place in one step or in several successive steps. According to a preferred embodiment, said contacting step(s) is (are) carried out by the so-called "dry" impregnation method well known to those skilled in the art by bringing into contact an impregnation solution containing a compound comprising molybdenum and a compound comprising cobalt with said porous support containing the carbon.

The metals can be deposited in co-impregnation or by successive addition.

According to a first embodiment, the metals cobalt and molybdenum are deposited on the support in a single step, by dry impregnation of said support by means of a solution containing the desired quantity of cobalt and molybdenum.

Alternatively, according to a second embodiment, in a first step, the cobalt and then the molybdenum are deposited by impregnation or, conversely, the molybdenum and then the cobalt. According to a third embodiment, a first step of impregnation of cobalt and molybdenum metals is carried out on the support. A second impregnation of cobalt or molybdenum alone is then carried out, in order to adjust the Co/Mo molar ratio.

In this second or third embodiment, before the second impregnation, the impregnated support is preferably dried.

The bringing into contact advantageously involves a precursor of said metals.

By way of example, among the sources of molybdenum, use may be made of oxides and hydroxides, molybdic acids and their salts, in particular ammonium salts such as ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid (H ₃ PMo ₁₂ O ₄₀ ), and their salts, and optionally silicomolybdic acid (H ₄ SiMo ₁₂ O ₄₀ ) and its salts. The sources of molybdenum can also be any heteropolycompound of Keggin, lacunary Keggin, substituted Keggin, Dawson, Anderson, Strandberg type, for example. Preferably, molybdenum trioxide and the heteropolycompounds of Keggin, lacunary Keggin, substituted Keggin and Strandberg type are used.

The cobalt precursors which can be used are advantageously chosen from oxides, hydroxides, hydroxycarbonates, carbonates and nitrates, for example. Cobalt hydroxide and cobalt carbonate are preferably used.

Any impregnation solution described in the present invention can comprise any polar protic solvent known to those skilled in the art. Preferably, a polar protic solvent is used, for example chosen from the group formed by methanol, ethanol and water. Preferably, the impregnation solution comprises a water-ethanol or water-methanol mixture as solvents in order to facilitate the impregnation of the compound containing a metal from group VIB and of the compound containing a metal from group VIII (and optionally the phosphorus and/or an organic compound as described below) on the oxide support containing the graphitic material and which is therefore partly hydrophobic. Preferably, the solvent used in the impregnation solution consists of a water-ethanol or water-methanol mixture.

According to another variant, the contacting step b) can also comprise bringing the porous support containing the carbon into contact with an impregnating solution containing phosphorus, in addition to the compound comprising molybdenum and the compound comprising cobalt .

In this case, the molar ratio of phosphorus added per molybdenum metal is between 0.1 and 2.5 mol/mol, preferably between 0.1 and 2.0 mol/mol, and even more preferably between between 0.1 and 1.0 mol/mol.

The preferred phosphorus precursor is orthophosphoric acid H ₃ PO ₄ , but its salts and esters such as ammonium phosphates are also suitable. The phosphorus can also be introduced at the same time as the element(s) of group VIB in the form of heteropolyanions of Keggin, lacunary Keggin, substituted Keggin or of the Strandberg type.

Advantageously, after each impregnation step, the impregnated support is allowed to mature. Curing allows the impregnation solution to disperse evenly within the support.

Any maturation step described in the present invention is advantageously carried out at atmospheric pressure, in an atmosphere saturated with water and at a temperature between 17° C. and 50° C., and preferably at ambient temperature. Generally, a maturation period of between ten minutes and forty-eight hours, and preferably between thirty minutes and six hours, is sufficient.

After step b), a capture mass precursor is thus obtained which comprises the porous support, the carbon and the active phase consisting of cobalt and molybdenum, and optionally phosphorus.

According to step c) of the method for preparing the capture mass used according to the method of the invention, said precursor is dried at a temperature below 200° C., advantageously between 50° C. and 180° C., preferably between 70°C and 150°C, very preferably between 75°C and 130°C, without subsequent calcination, so as to obtain a dried capture mass.

The drying step is preferably carried out under an inert atmosphere, typically under a nitrogen atmosphere.

The drying step can be carried out by any technique known to those skilled in the art. It is advantageously carried out at atmospheric pressure or at reduced pressure. Preferably, this step is carried out at atmospheric pressure. It is advantageously carried out in a traversed bed using any hot inert gas. Preferably, when the drying is carried out in a fixed bed, the gas used is argon or nitrogen. Very preferably, the drying is carried out in a traversed bed in the presence of nitrogen. Preferably, the drying step lasts between 5 minutes and 15 hours, preferably between 30 minutes and 12 hours.

It is important to emphasize that the capture mass during its preparation process does not undergo calcination in order to preserve the carbon.

Here, calcination means a heat treatment under a gas containing air or oxygen at a temperature greater than or equal to 200°C.

At the end of the drying step, a dried capture mass is then obtained, which will be subjected to an optional activation step (sulfidation) for its subsequent implementation in a capture process.

Thus, according to step d) of the process for preparing the capture mass used according to the process of the invention, the dried capture mass is optionally activated in the presence of a sulfurizing agent.

The sulfurization is preferably carried out in a sulphur-reducing medium, that is to say in the presence of H ₂ S and hydrogen. Sulfurization is carried out by injecting onto the capture mass a flow containing H ₂ S and hydrogen, or else a sulfur compound capable of decomposing into H ₂ S in the presence of the capture mass and the hydrogen. Polysulfides such as dimethyldisulfide (DMDS) are H ₂ S precursors commonly used to sulfur capture masses. The temperature is adjusted so that the H ₂ S reacts with the dried capture mass to form metal sulphides such as, for example, MoS ₂ and Co ₉ S ₈ . This sulfurization can be carried out in situ or ex situ (inside or outside the reactor) of the reactor of the process according to the invention at temperatures between 200 and 600°C and more preferably between 300 and 500°C.

According to another variant of the invention, the capture mass of the process according to the invention does not undergo a sulfurization step, that is to say the capture mass is not brought into contact with an agent sulfurizing agent, before injection of the charge. In this case, the capture mass is sulfurized by the sulfur contained in the charge.

To be active, metals must be substantially sulfurized. An element is considered to be substantially sulfurized when the molar ratio between the sulfur (S) present on the capture mass and the said element is at least equal to 50% of the theoretical molar ratio corresponding to the total sulfurization of the element considered:

with :

- (S/element) _{capture mass} molar ratio between the sulfur (S) and the element present on the capture mass.

- (S/element) _theoretical molar ratio between sulfur and the element corresponding to the total sulphidation of the element in sulphide.

This theoretical molar ratio varies according to the element considered:

- (S/Co) _theoretical = 8/9

- (S/Mo) _theoretical =2/1

The molar ratio between the sulfur present on the capture mass and all the elements is preferably at least equal to 50% of the theoretical molar ratio corresponding to the total sulphidation of each sulphide element, the calculation being carried out in proportion to the fractions relative molars of each element. Very preferably, the sulfurization rate of the metals will be greater than 70%.

According to a completely different variant, the capture mass of the process according to the invention can be an at least partially spent catalyst. By an at least partially spent catalyst is meant a catalyst which comes out of a hydrotreating process. The at least partially spent catalyst can come from a hydrotreatment of any petroleum cut, such as a naphtha, kerosene, gas oil, vacuum distillate or residue cut. By hydrotreating we mean reactions including in particular hydrodesulphurization (HDS), hydrodenitrogenation (HDN) and the hydrogenation of aromatics (HDA). It can also come from hydrotreating biomass or bio-oils. Preferably, the at least partially spent catalyst comes from a hydrodesulfurization process of an olefinic gasoline cut containing sulfur carried out under the conditions as described below.

Advantageously, the at least partially spent catalyst does not undergo regeneration, that is to say a heat treatment under a gas containing air or oxygen at a temperature above 200° C. generally making it possible to burn the majority of the coke formed during the hydrotreating process in which it was previously used. It may have undergone a de-oiling step before its use in the gasoline hydrodesulfurization process of the present invention. The de-oiling step generally comprises contacting the at least partially spent catalyst with a stream of inert gas (that is to say substantially free of oxygen), for example in a nitrogen atmosphere or the like, at a temperature between 300°C and 400°C, preferably between 300°C and 350°C. The inert gas flow rate in terms of flow rate per unit volume of the catalyst is 5 to 150 NL.L ^-1 .h ^-1 for 3 to 7 hours. As a variant, the de-oiling stage can be carried out by light hydrocarbons, by steam treatment or any other similar process.

The de-oiling stage makes it possible to eliminate the soluble hydrocarbons and therefore to release the porosity of the at least partially spent catalyst necessary for the hydrodesulphurization.

This at least partially spent catalyst comprises said porous support, sulfur, the active phase, optionally phosphorus, and said carbon in the form of coke.

The contents of metals, sulphur, carbon and phosphorus of the at least partially spent catalyst are those indicated above. They are determined according to the same methods described above.

Optionally, the at least partially spent catalyst may also have a low content of contaminants from the treated feed such as silicon, arsenic or chlorine.

Preferably, the silicon content (in addition to that possibly present on the catalyst) is less than 2% by weight and very preferably less than 1% by weight relative to the total weight of the at least partially spent catalyst.

Preferably, the arsenic content is less than 2000 ppm by weight and very preferably less than 500 ppm by weight relative to the total weight of the at least partially spent catalyst.

Preferably, the chlorine content is less than 2000 ppm by weight and very preferably less than 500 ppm by weight relative to the total weight of the at least partially spent catalyst.

Optional hydrodesulfurization/selective hydrogenation steps

The capture process according to the invention is preferably coupled with at least one additional catalytic hydrodesulphurization or selective hydrogenation stage which is carried out on the effluent resulting from the contact with the capture mass. Thus the stage of treatment of the hydrocarbon charge by the capture mass is considered as a pre-treatment which makes it possible in particular to preserve the catalytic activity of the catalyst used in the subsequent hydrodesulphurization or selective hydrogenation stage. Thus, the capture process according to the invention comprises one or more other complementary stages of hydrodesulphurization or selective hydrogenation in which the effluent resulting from the contacting of the charge hydrocarbon with the capture mass according to the invention, with at least one other catalyst for hydrodesulphurization or selective hydrogenation of the diolefins present in the olefin feed. Said complementary hydrodesulfurization step(s) makes it possible to eliminate the residual sulfur compounds contained in the effluent depleted in arsenic and with a lower sulfur content. Some of these residual sulfur compounds may result from the addition of H ₂ S to the olefins present in the charge. The H ₂ S can form during the contacting of the hydrocarbon charge with the capture mass, that is to say, during the capture of the arsenic. Said complementary hydrodesulphurization stage(s) is (are) implemented when the effluent resulting from the contacting of the hydrocarbon charge with the capture mass generally has a sulfur content greater than 10 ppm and that it is necessary to produce gasolines with low sulfur content meeting the current specifications which are in many countries lower than 10 ppm. The effluent freed from arsenic and from a part of the sulfur compounds is then treated in at least one of said complementary stages of selective hydrodesulphurization. In said step(s), said effluent is brought into contact with at least one other hydrodesulphurization catalyst under operating conditions which may be identical to or different from those for bringing the hydrocarbon feedstock into contact with the mass. of capture. The catalyst(s) used in the said additional hydrodesulphurization stage(s) is (are) protected from deactivation by the arsenic present in the charge thanks to the capture mass according to the invention. Thus very selective hydrodesulphurization catalysts which are sensitive to the presence of arsenic can be used in said complementary hydrodesulphurization step(s). Any hydrodesulphurization catalyst can be used in said complementary hydrodesulphurization step(s). Preferably, catalysts are used which exhibit a high selectivity with respect to hydrodesulfurization reactions relative to the hydrogenation reactions of olefins. Such catalysts comprise at least one amorphous and porous mineral support, a group VIB metal, a group VIII metal. The group VIB metal is preferably molybdenum or tungsten and the group VIII metal is preferably nickel or cobalt. The support is generally selected from the group consisting of aluminas, silica, silica-aluminas, silicon carbide, titanium oxides alone or mixed with alumina or silica alumina, magnesium oxides alone or as a mixture with alumina or silica alumina. Preferably, the support is selected from the group consisting of aluminas, silica and silica-aluminas. Preferably, the hydrodesulphurization catalyst used in the additional hydrodesulphurization stage or stages has the following characteristics:

- the content of group VIB elements is between 1 and 20% by weight of oxides of group VIB elements;

- the content of group VIII elements is between 0.1 and 20% by weight of oxides of group VIII elements;

- the molar ratio (group VIII elements/group VIB elements) is between 0.1 and 0.8.

A very preferred hydrodesulfurization catalyst comprises cobalt and molybdenum and has the characteristics mentioned above. Furthermore, the hydrodesulphurization catalyst may comprise phosphorus. In this case, the phosphorus content is preferably between 0.1 and 10% by weight of P ₂ O ₅ relative to the total weight of catalyst and the phosphorus to group VIB elements molar ratio is greater than or equal to 0.25 , preferably greater than or equal to 0.27. In the said additional hydrodesulphurization step(s), the arsenic-depleted effluent resulting from the contacting of the hydrocarbon charge with the capture mass is brought into contact with at least one another selective hydrodesulfurization catalyst under the following operating conditions:

- a temperature between about 210°C and about 410°C, preferably between 240 and 360°C;

- a total pressure between 0.2 and 5 MPa and more preferably between 0.5 and about 3 MPa;

- a volume ratio of hydrogen per volume of hydrocarbon charge, between 50 and 800 Nm ³ /m ³ and more preferably between 60 and 600 Nm ³ /m ³ .

In a variant of the process according to the invention, the operating conditions for bringing the hydrocarbon feedstock into contact with the capture mass according to the invention are identical to those implemented in the said step(s). ) additional hydrodesulphurization(s).

According to another embodiment, the step of hydrotreating the effluent from the capture step by means of the capture mass is a selective hydrogenation which allows the hydrogenation of the diolefins into olefins and optionally unsaturated sulfur compounds but also the transformation (heaviness) of light sulfur compounds (i.e. having a temperature lower than that of thiophene) into sulfur compounds whose temperature is higher than that of thiophene, for example by adding mercaptans to olefins. This hydrogenation step is carried out in the presence of hydrogen and a catalyst containing at least one metal from group VIB and at least one non-noble metal from group VIII deposited on a porous support. Preferably, a catalyst is used of which:

- the content by weight of oxide of the element of group VIB is between 6 and 18% by weight relative to the weight of the catalyst;

- the content by weight of oxide of the element of group VIII is between 4 and 12% by weight relative to the weight of the catalyst;

- the specific surface of the catalyst is between 200 and 270 m²/g;

- the density of the element of group VIB, expressed as being the ratio between the said content by weight of oxide of the element of group VIB and the specific surface of the catalyst, is between 4 and 6.10-4 g/m²;

- the molar ratio between the group VIII metal and the group VIB metal is between 0.6 and 3 mol/mol.

The group VIB metal is preferably chosen from molybdenum and tungsten, very preferably the group VIB metal is molybdenum. The Group VIII metal is preferably nickel and/or cobalt, very preferably nickel. The hydrogen is generally introduced in slight excess, up to 5 moles per mole, relative to the stoichiometry necessary to hydrogenate the diolefins (one mole of hydrogen per mole of diolefin). The mixture consisting of gasoline and hydrogen is brought into contact with the catalyst under a pressure of between 0.5 and 5 MPa, a temperature of between 80 and 220°C, with a liquid space velocity (LHSV) of between 1 and 10 h ^-1 , the liquid space velocity being expressed in liter of charge per liter of catalyst and per hour (L/Lh). In a variant of the process according to the invention, the capture mass can be placed in the guard bed position of one or more reactor(s) containing the catalyst(s) used in said (es) additional step(s) of hydrodesulphurization and/or selective hydrogenation. In another variant of the method according to the invention, the capture mass is placed in a so-called capture reactor. This reactor is separate and is placed upstream of the reactor(s) containing the catalyst(s) used in said complementary hydrodesulphurization step(s) and / or selective hydrogenation. In all the variants of the process according to the invention, implementing at least one additional step of hydrodesulphurization and/or selective hydrogenation, the volume ratio of the capture mass according to the invention relative to the volume of (of ) catalyst(s) used in said additional hydrodesulphurization and/or selective hydrogenation step(s) is advantageously between 4 and 50%, preferably between 5 and 40 %, more preferably between 5 and 35%.

The invention is illustrated by the examples which follow.

Examples

Example 1: Mass prepared by carbonization of an alumina support then impregnation (according to the invention)

In this example, 2 g of phenol and 15 g of alumina are mixed with 50 ml of water and 50 ml of ethanol in an autoclave. The system is sealed and then brought to 200° C. with a ramp of 8° C./min. The temperature is maintained for 10 h and the solid is filtered off. After washing with distilled water, the solid is dried in an oven at 100°C for 10 h and then pyrolyzed at 300°C for 1 h in a tube furnace in a traversed bed under a nitrogen flow of 10 ml/min /g with a temperature ramp of 6°C/min. The sample is then recovered and the process is repeated 4 consecutive times to obtain the support S.

Support S has a water uptake volume of 0.75 mL/g. The impregnation solution is prepared by dissolving ammonium heptamolybdate (2.63 g) and cobalt nitrate (0.69 g) in 7.4 mL of water. After dry impregnation of 10 grams of carbonized support, the solid is left to mature for 2 hours then dried in a vacuum oven at 90° C. for 12 hours, then heat-treated at 300° C. for 6 hours under a flow of nitrogen.

The contents of Co, Mo and C, expressed in % weight of oxide CoO, MoO ₃ and % carbon weight are as follows: MoO ₃ = 20.0 +/- 0.2 % weight, CoO = 4.0 + /- 0.1% by weight and C = 9.2 +/- 0.2% by weight.

Example 2: Evaluation of Catalytic Performance and Capture of Arsenic

The solid prepared in Example 1 is evaluated for the capture of arsenic. A gasoline from the FCC (cut 50-245°C) containing 563 ppm by weight of sulfur is doped with an arsenic compound (triphenyl arsine) so as to reach a concentration of 3 ppm by weight of arsenic. To carry out these tests, a pilot unit equipped with a tubular reactor with a traversed fixed bed is used. 20 ml of the solid prepared in Example 1 is introduced into the reactor and sulfurized in situ at 350° C. under a gas mixture (H ₂ /H ₂ S) at (85/15)% vol./vol. The FCC gasoline with added triphenyl arsine is then treated in the presence of H ₂ (H ₂ /charge ratio = 300 NL/L) at a temperature of 220° C., under a total pressure of 2 MPa and at a VVH ( hourly volume velocity) of 20 h ^-1 .

The efficiency of arsenic capture is measured by the quantity of arsenic captured per gram of solid when the arsenic content in the effluent is greater than or equal to 5% of the arsenic content in the load (C/ _C0 ≥ 5%m/m).

For the solid prepared in Example 1, this value was measured at 1.6 g/100g, a particularly high value making it possible to envisage very long-term use for fillers very generally containing between 1 and 100 ppb of arsenic.

Claims (12)

Process for capturing organometallic impurities in a gasoline-type hydrocarbon feed containing sulfur compounds and olefins, in which a capture mass is brought into contact with the feed to be treated and a flow of hydrogen at a temperature between 200 and 400°C, a pressure of between 0.2 and 5 MPa and a ratio of the hydrogen flow rate to the hydrocarbon feed flow rate of between 50 and 800 Nm³/m³, said capture mass comprises an active phase consisting of cobalt and molybdenum, carbon, and a porous support chosen from the group consisting of aluminas, silica, silica aluminas, or titanium or magnesium oxides used alone or mixed with the alumina or silica alumina. Capture process according to Claim 1, in which the molybdenum content is between 5 and 40% by weight, expressed as molybdenum oxide relative to the total weight of the capture mass. Capture method according to one of the preceding claims, in which the cobalt content is between 1 and 10% by weight, expressed as cobalt oxide relative to the total weight of the capture mass. Capture process according to one of the preceding claims, in which the cobalt to molybdenum molar ratio is between 0.1 and 0.8. Capture method according to one of the preceding claims, in which the carbon content, expressed as carbon element, is between 0.5 and 80% by weight relative to the total weight of the capture mass. Capture method according to one of the preceding claims, in which the capture mass also contains sulphur, the sulfur content of the capture mass, expressed as sulfur element, is between 1 and 8% by weight relative to the mass total capture mass. Capture process according to one of the preceding claims, in which the active phase of the capture mass is sulfurized in situ. Capture process according to one of the preceding claims, in which the feed to be treated is a gasoline from catalytic cracking containing between 5% and 60% by weight of olefins, 50 ppm to 6000 ppm by weight of sulfur, as well as traces of arsenic in contents between 1 ppb and 1000 ppb by weight. Capture process according to one of the preceding claims, in which the organometallic impurities are chosen from heavy metals, silicon, phosphorus and arsenic. Capture process according to one of the preceding claims, in which the said capture mass is placed in a reactor located upstream of a hydrodesulfurization unit containing a hydrodesulfurization catalyst and/or of a selective hydrogenation unit containing a catalyst for the selective hydrogenation of said charge. Capture process according to claims 1 to 9, in which said capture mass is placed inside a reactor for the hydrodesulphurization and/or selective hydrogenation of said charge, at the head of said reactor. Capture process according to Claims 10 and 11, in which the ratio of the volume of the said capture mass relative to the volume of the said hydrodesulphurization and/or selective hydrogenation catalyst is between 1 and 99%.