Mercaptan recovery process with specific Ni / NiO ratio and temperature selection

Abstract

A process for capturing mercaptans contained in a sulfur-containing hydrocarbon feedstock, the process being carried out at a temperature of 170°C to 220°C, a pressure of 0.2MPa to 5MPa, and an hourly space velocity, defined as the volumetric flow rate of the feedstock at the inlet per volume of the capture mass, of 0.1 h -1 ~50h -1 in the presence of a capture mass comprising a nickel-based active phase in which the weight ratio of nickel present in said capture mass in reduced form to nickel present in said capture mass in oxide form is between 0.25 and 4, and an inorganic support selected from the group consisting of alumina, silica, silica-alumina, and clay.

Description

[Technical field]

[0001] The present invention relates to the field of hydrotreating gasoline fractions, in particular gasoline fractions coming from fluidized bed catalytic crackers. More particularly, the present invention relates to a process for capturing mercaptan-type compounds contained in a hydrocarbon feedstock in the presence of specific trapping masses. [Background technology]

[0002] Automotive fuel standards require a significant reduction in the sulfur content of these fuels, especially gasoline. This reduction is aimed at limiting the content of sulfur and nitrogen oxides in motor vehicle exhaust gases in particular. Gasoline fuel standards, in force since 2009 in Europe, set a maximum sulfur content of 10 parts per million (ppm) by weight. Such standards are also in force in other countries, e.g. the United States and China, which have required the same sulfur content limits since January 2017. To achieve these standards, gasoline must be treated through a desulfurization process.

[0003] The main source of sulfur in the gasoline base is "cracked" gasoline, which is the gasoline fraction obtained mainly from the catalytic cracking process of atmospheric or vacuum residues of crude oil. The catalytic cracking fraction constitutes on average 40% of the gasoline base and actually accounts for more than 90% of the sulfur content in gasoline. Therefore, a desulfurization step of the catalytic cracked gasoline is necessary to produce low-sulfur gasoline. Other sources of gasoline that may contain sulfur include coker gasoline, visbreaker gasoline, and, to a lesser extent, gasoline obtained from atmospheric distillation or steam cracking.

[0004] To remove sulfur from gasoline fractions, gasoline with high sulfur content must be specially treated by desulfurization in the presence of hydrogen. These are called hydrodesulfurization (HDS) processes. However, these gasoline fractions, more specifically catalytic cracking (FCC) gasoline, contain a lot of unsaturated compounds in the form of monoolefins (about 20% to 50% by weight), diolefins (0.5% to 5% by weight) and aromatics, which contribute to a good octane number. These unsaturated compounds are unstable and react during hydrodesulfurization. Diolefins polymerize during hydrodesulfurization to form gums. This gum formation gradually deactivates the hydrodesulfurization catalyst or gradually clogs the reactor. As a result, diolefins must be removed by hydrotreating before these gasolines can be subjected to any processing. Conventional processing processes non-selectively desulfurize gasoline by hydrogenating most of the monoolefins, which results in high octane number losses and high hydrogen consumption. Modern hydrodesulfurization processes make it possible to desulfurize cracked gasolines rich in monoolefins while limiting the hydrogenation of the monoolefins and thus the loss of the octane number, as described, for example, in EP-A-1 077 247 and EP-A-1 174 485.

[0005] However, if the desulfurization of cracked gasoline needs to be very thorough, some of the olefins present in the cracked gasoline are hydrogenated on the one hand and recombine with H2S to form mercaptans on the other hand. This group of compounds, represented by the chemical formula R-SH, where R is an alkyl group, is generally called recombined mercaptans and accounts for 20% to 80% by weight of the residual sulfur in desulfurized gasoline. A reduction in the content of recombined mercaptans may be achieved by catalytic hydrodesulfurization, but this leads to hydrogenation of most of the monoolefins present in the gasoline, which greatly reduces the octane number of the gasoline and also leads to excessive consumption of hydrogen. Moreover, it is known that the lower the target sulfur content, i.e., the more thoroughly one tries to remove the sulfur compounds present in the feedstock, the greater the proportional reduction in octane number due to hydrogenation of monoolefins in the hydrodesulfurization step.

[0006] For these reasons, it is desirable to treat this partially hydrodesulfurized gasoline by means of a carefully selected adsorption technique capable of simultaneously removing the unconverted sulfur compounds and recombined mercaptans originally present in the cracked gasoline, without hydrogenating the monoolefins present, in order to maintain the octane number.

[0007] Various solutions have been proposed in the literature to extract these mercaptans from hydrocarbon fractions, either using adsorption-type processes or combining hydrodesulfurization or adsorption steps, but there is still a need for more efficient trapping masses for mercaptan extraction to suppress the hydrogenation reactions that cause the reduction of the octane number of the target gasoline.

[0008] For example, US Patent Application 2003 / 0188992 describes a process for desulfurizing olefinic gasoline by treating the gasoline in an initial hydrodesulfurization step, followed by removal of mercaptan-type sulfur compounds in a polishing step, which consists mainly of solvent extraction of mercaptans by washing.

[0009] US Pat. No. 5,866,749 proposes a solution for the removal of elemental sulfur and mercaptans contained in olefinic fractions by passing the mixture to be treated over reducing metals selected from groups IB, IIB and IIIA of the periodic table, at temperatures below 37° C.

[0010] US Pat. No. 6,579,444 discloses a process for removing sulfur from gasoline, or the sulfur remaining in partially desulfurized gasoline, using solids containing cobalt and a Group VIB metal.

[0011] US Patent Application 2003 / 0226786 describes a process for desulfurizing gasoline by adsorption and several methods for regenerating the adsorbent. The adsorbents envisaged are hydrotreating catalysts, more specifically based on group VIII metals, alone or mixed with group VI metals, containing between 2% and 20% by weight of group VIII metal relative to the total weight of the catalyst.

[0012] French Patent No. 2908781 discloses a process for capturing sulfur compounds from a partially desulfurized hydrocarbon feedstock in the presence of an adsorbent containing at least one metal of group VIII, IB, IIB or IVA, the adsorbent being used in reduced form in the absence of hydrogen and at temperatures above 40°C.

[0013] The applicant has surprisingly discovered that by using a capture mass comprising a nickel-based active layer having a specific weight ratio of nickel present in the capture mass in reduced form (i.e. elemental Ni°) and nickel present in the capture mass in oxide form (NiO) in the exact temperature range in which the mercaptan retention capacity can be maximized, it is possible to dramatically improve the performance of the mercaptan capture process while limiting, on the one hand, the product losses and, on the other hand, the energy consumption per amount of captured sulfur. Without wishing to be bound by any theory, the synergy between the specific Ni° / NiO ratio of the capture mass and the choice of the temperature range for carrying out the capture process makes it possible to avoid cracking reactions while maximizing the proportion and availability of active sites present on the capture mass to capture mercaptans. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] European Patent Application Publication No. 1077247 [Patent Document 2] European Patent Application Publication No. 1174485 [Patent Document 3] U.S. Patent Application No. 2003 / 0188992 [Patent Document 4] U.S. Pat. No. 5,866,749 [Patent Document 5] U.S. Patent No. 6,579,444 [Patent Document 6] US Patent Application No. 2003 / 0226786 [Patent Document 7] French Patent No. 2908781 Summary of the Invention [Means for solving the problem]

[0015] The present invention relates to a process for capturing mercaptans contained in an optionally partially desulfurized sulfur-containing hydrocarbon feed resulting from a catalytic hydrodesulfurization step, the process being carried out at a temperature between 170°C and 220°C, at a pressure between 0.2 MPa and 5 MPa, and with an hourly space velocity, defined as the volumetric flow rate of the feed at the inlet per volume of the capture mass, of 0.1 h -1 ~50h -1 in the presence of a capture mass comprising a nickel-based active phase in which the weight ratio of nickel present in said capture mass in reduced form (i.e., Ni° in elemental form) to nickel present in said capture mass in oxide form (NiO) is between 0.25 and 4, and an inorganic support selected from the group consisting of alumina, silica, silica-alumina, and clay.

[0016] According to one or more embodiments, the weight ratio of nickel present in the capture mass in reduced form to nickel present in the capture mass in oxide form is between 0.4 and 3.

[0017] According to one or more embodiments, the weight ratio of nickel present in the capture mass in reduced form to nickel present in the capture mass in oxide form is between 0.5 and 2.5.

[0018] According to one or more embodiments, the process is carried out at a temperature between 180°C and 210°C.

[0019] According to one or more embodiments, the nickel content is between 20% and 70% by weight of elemental nickel based on the total weight of the capture mass.

[0020] According to one or more embodiments, the capture mass is 150 m 2 / g~250m 2 / g.

[0021] According to one or more embodiments, the capture agglomerate has a total pore volume of between 0.20 ml / g and 0.70 ml / g as measured by mercury porosimetry.

[0022] According to one or more embodiments, the content of elemental aluminum and / or elemental silicon in the capture mass is between 5% and 45% by weight based on the total weight of the capture mass.

[0023] According to one or more embodiments, the support is alumina.

[0024] According to one or more embodiments, the hydrocarbon feedstock is a feedstock that has been partially desulfurized by a catalytic hydrodesulfurization process.

[0025] According to one or more embodiments, the hydrocarbon feedstock being treated is a partially desulfurized catalytically cracked gasoline having a boiling point below 350° C., containing 5% to 60% by weight of olefins and less than 100 ppm by weight of sulfur, based on the total weight of the feedstock. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Below, the groups of chemical elements are indicated according to the CAS classification (CRC Handbook of Chemistry and Physics, published by CRC Press, editor in chief DR Lide, 81st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals in columns 8, 9 and 10 according to the new IUPAC classification.

[0027] The BET specific surface area is measured by nitrogen physisorption according to standard ASTM D3663-03, the method described in "Adsorption by Powders & Porous Solids: Principles, Methodology and Applications" by Rouquerol F., Rouquerol J. and Singh K., Academic Press, 1999.

[0028] In the following description of the invention, the "total pore volume" (TPV) of the capture mass or support is understood to mean the volume measured by mercury intrusion porosimetry according to standard ASTM D4284-83, at a maximum pressure of 4000 bar (400 MPa), with a surface tension of 484 dynes / cm and a contact angle of 140°. The wetting angle was taken to be 140° according to the recommendation of Jean Charpin and Bernard Rasneur, Techniques of the Engineer, Analysis and Characterization Treatise, pages 1050-5.

[0029] For better accuracy, the values ​​of total pore volume in ml / g given in the following text correspond to the value of the total mercury volume in ml / g measured on a sample (total pore volume measured by mercury porosimetry) minus the value of the mercury volume in ml / g measured on the same sample for a pressure equivalent to 30 psi (approximately 0.2 MPa).

[0030] Nickel content is measured by X-ray fluorescence.

[0031] The weight ratio of nickel in reduced form (Ni°) to nickel in oxide form (NiO) is α1The diffractogram of the captured mass is measured by X-ray diffraction using a diffractometer using conventional powder techniques with radiation (λ=1.5406 Å). The diffractogram of the captured mass may therefore have, in addition to the characteristic lines of the support, the characteristic lines of nickel in metallic or oxidic form. The skilled person can determine the position of these lines by referring to tables of the ICDD (International Centre for Diffraction Data). For example, the positions of the lines of nickel oxide (NiO) are reported in table 00-047-1049 and the positions of the lines of nickel (Ni°) are reported in table 00-004-0850.

[0032] To determine the Ni° / NiO weight ratio, the diffractogram of the captured mass is subtracted from the diffractogram of the support used, and the ratio of the areas under the principal lines of Ni° (51.8° 2θ) and NiO (43.3° 2θ) is taken as the Ni° / NiO ratio.

[0033] Mercaptan trapping The present invention relates to a process for capturing mercaptans contained in a sulfur-containing hydrocarbon feedstock, said feedstock having been advantageously partially desulfurized by a catalytic hydrodesulfurization step in the presence of a capture mass.

[0034] The mercaptan capture step is carried out at a temperature of 170° C. to 220° C., preferably 180° C. to 210° C. If the temperature exceeds 170° C., extraction of metal thiolate can be prevented. If the temperature is less than 220° C., vaporization of the raw material to be treated can be prevented.

[0035] The process generally lasts for 0.1 h. -1 ~50h -1 , preferably 0.5h -1 ~20h -1 , preferably 0.5h -1 ~10h -1 The process is carried out at an hourly space velocity (defined as the volumetric flow rate of the feed at the inlet per volume of the captured mass).

[0036] The mercaptan capture process is generally carried out in the absence of hydrogen. The feed should preferably remain liquid, which requires sufficient pressure above the vaporization pressure of the feed. The mercaptan capture process is generally carried out at a pressure of 0.2 MPa to 5 MPa, preferably 0.2 MPa to 2 MPa.

[0037] Advantageously, the reaction section of the capture process comprises 2 to 5 reactors, referred to by the term PRS for Replaceable Reactor System or "Lead & Lag", which are operated in a replaceable mode.

[0038] The sulfur-containing hydrocarbon feedstock, which is optionally partially desulfurized, is preferably a gasoline containing olefinic compounds, preferably a gasoline fraction obtained from a catalytic cracking process. The treated hydrocarbon feedstock generally has a boiling point below 350° C., preferably below 300° C., very preferably below 250° C. Preferably, the feedstock contains 5% to 60% by weight of olefins, based on the total weight of said feedstock. Preferably, the hydrocarbon feedstock contains less than 100 ppm by weight of sulfur, preferably less than 50 ppm by weight of sulfur, especially in the form of mercaptans, based on the total weight of said feedstock. Preferably, the partially desulfurized hydrocarbon feedstock contains less than 50 ppm by weight of sulfur, preferably less than 30 ppm by weight of sulfur, based on the total weight of the feedstock, in the form of mercaptans.

[0039] Preferably, the feedstock to be treated is subjected to a partial desulfurization treatment prior to the mercaptan capture process, which step consists of contacting the sulfur-containing feedstock fraction with hydrogen in one or more hydrodesulfurization reactors arranged in series, which contain one or more catalysts suitable for carrying out hydrodesulfurization. Preferably, the operating pressure of this step is generally between 0.5 MPa and 5 MPa, very preferably between 1 MPa and 3 MPa, and the temperature is generally between 200°C and 400°C, very preferably between 220°C and 380°C. Preferably, the amount of catalyst used in each reactor is generally greater than m3 per hour under standard conditions. 3 The flow rate of gasoline to be processed is expressed as 1 m 3The ratio of catalyst to the number of catalysts is 0.5h. -1 ~20h -1 , very preferably 1h -1 ~10h -1 Preferably, the hydrogen flow rate is generally in the range of 100 to 2000 m3 per hour under standard conditions. 3 Hydrogen flow rate (Nm 3 / h) and m per hour 3 The ratio of the flow rate of the raw material to be treated, expressed as 50 Nm 3 / m 3 ~1000Nm 3 / m 3 , very preferably 70Nm 3 / m 3 ~800Nm 3 / m 3 Preferably, this step is carried out selectively, i.e. with the aim of hydrodesulfurization, i.e. with a degree of hydrogenation of the monoolefins of less than 80% by weight, preferably less than 70% by weight, very preferably less than 60% by weight.

[0040] The degree of desulfurization achieved in this hydrodesulfurization step is generally greater than 50%, preferably greater than 70%, so that the hydrocarbon fraction used in the mercaptan capture step contains less than 100 ppm by weight of sulfur, preferably less than 50 ppm by weight of sulfur.

[0041] In the preliminary hydrodesulfurization step, any hydrodesulfurization catalyst can be used. Preferably, a catalyst is used that has a high selectivity for hydrodesulfurization reactions compared to olefin hydrogenation reactions. Such a catalyst comprises at least one porous inorganic support, a group VIB metal, a group VIII metal. The group VIB metal is preferentially molybdenum or tungsten, and the group VIII metal is preferentially nickel or cobalt. The support is generally selected from the group constituted by alumina, silica, silica-alumina, silicon carbide, titanium oxide, alone or mixed with alumina or silica-alumina, and magnesium oxide, alone or mixed with alumina or silica-alumina. Preferably, the support is selected from the group constituted by alumina, silica and silica-alumina. Preferably, the hydrodesulfurization catalyst used in the additional hydrodesulfurization step has the following characteristics: The content of the Group VIB element is 1% by weight to 20% by weight of the oxide of the Group VIB element based on the weight of the catalyst. The content of the Group VIII element is 0.1% by weight to 20% by weight of the oxide of the Group VIII element based on the weight of the catalyst. The molar ratio of (Group VIII element / Group VIB element) is 0.1 to 0.8.

[0042] If the metal is cobalt or nickel, the metal content is expressed as CoО and NiО, respectively, if the metal is molybdenum or tungsten, the metal content is expressed as MoО3 and WО3, respectively.

[0043] A highly preferred hydrodesulfurization catalyst comprises cobalt and molybdenum and has the above-mentioned characteristics. In addition, the hydrodesulfurization catalyst may contain phosphorus, in which case the phosphorus content is preferably 0.1% to 10% by weight of P2O5, based on the total weight of the catalyst, and the molar ratio of phosphorus to group VIB element is 0.25 or more, preferably 0.27 or more.

[0044] Preferably, the feedstock to be treated is subjected to a complementary polishing hydrodesulfurization step after the partial desulfurization step and before the mercaptan capture process. The polishing hydrodesulfurization step is performed mainly to at least partially decompose the recombined mercaptans produced during the partial desulfurization step into olefins and H2S, but also makes it possible to hydrodesulfurize the more refractory sulfur compounds, whereas the first hydrodesulfurization step is performed mainly to convert the majority of the sulfur compounds into H2S. The remaining sulfur compounds are essentially the refractory sulfur compounds and the recombined mercaptans resulting from the addition of the produced H2S.

[0045] The polishing hydrodesulfurization step is generally carried out at a temperature between 280° C. and 400° C., preferably between 300° C. and 380° C., preferably between 310° C. and 370° C. The temperature of this polishing step is generally at least 5° C. higher, preferably at least 10° C. higher, very preferably at least 20° C. higher than the temperature of the first hydrodesulfurization step. This step is generally carried out for 0.5 h. -1 ~20h -1 , preferably for 1 h -1 ~10h -1 The process is generally carried out at an hourly space velocity (defined as the volumetric flow rate of the feed at the inlet per volume of catalyst) of 10 ... 3 Hydrogen flow rate (Nm 3 / h) and m per hour 3 The ratio of the flow rate of the raw material to the flow rate of the processed material is 10 Nm 3 / m 3 ~1000Nm 3 / m 3 , preferably 20 Nm 3 / m 3 ~800Nm 3 / m 3 The hydrogen flow rate is set so that

[0046] The process is generally carried out at a pressure between 0.5 MPa and 5 MPa, preferably between 1 MPa and 3 MPa.

[0047] In the polishing hydrodesulfurization step, any hydrodesulfurization catalyst can be used. Preferably, the catalyst comprises at least one porous inorganic support and a group VIII metal. The group VIII metal is preferentially nickel. The support is generally selected from the group constituted by alumina, silica, silica-alumina, silicon carbide, titanium oxide, alone or mixed with alumina or silica-alumina, and magnesium oxide, alone or mixed with alumina or silica-alumina. Preferably, the support is selected from the group constituted by alumina, silica and silica-alumina. Preferably, the hydrodesulfurization catalyst used in the polishing hydrodesulfurization step has the following characteristics: The content of the Group VIII element is 0.1% by weight to 30% by weight of the oxide of the Group VIII element based on the weight of the catalyst. · The support used is an alumina-based support.

[0048] Preferably, the hydrocarbon feedstock after polishing hydrodesulfurization treatment contains less than 100 ppm by weight of sulfur derived from organic compounds, preferably less than 50 ppm by weight of sulfur derived from organic compounds, especially in the form of mercaptans and sparingly soluble sulfur compounds.

[0049] At the end of the hydrodesulfurization step, the effluent is subjected to a step of separating hydrogen and H2S by any method known to the person skilled in the art (desorber, stabilization column, etc.) so as to recover a liquid effluent in which the dissolved H2S represents at most 30% by weight, even at most 20% by weight, even at most 10% by weight of the total sulfur present in the hydrocarbon fraction to be treated downstream by a mercaptan capture process.

[0050] captured mass The capture mass used in the context of the process according to the invention consists of a nickel-based active phase in which the weight ratio of nickel present in the capture mass in reduced form (Ni°) to nickel present in the capture mass in oxidic form (NiO) is between 0.25 and 4, preferably between 0.4 and 3, more preferentially between 0.5 and 2.5.

[0051] The nickel content is preferably between 10% and 80% by weight, preferably between 20% and 70% by weight, and very preferably between 30% and 70% by weight of elemental nickel based on the total weight of the capture mass. The "wt%" values ​​are based on the elemental form of nickel.

[0052] The catch mass used according to the invention is advantageously 120 mm 2 / g~350m 2 / g, preferably 150m 2 / g~250m 2 / g, more preferentially 155m 2 / g~220m 2 / g.

[0053] The capture mass used according to the present invention preferably has a total pore volume, measured by mercury porosimetry, of between 0.20 ml / g and 0.70 ml / g, preferably between 0.30 ml / g and 0.60 ml / g.

[0054] The capture mass also includes an inorganic support selected from the group consisting of alumina, silica, silica-alumina, and clay.

[0055] According to an alternative embodiment of the invention, the content of elemental aluminum and / or elemental silicon in the capture mass is preferably between 5% and 45% by weight, highly preferably between 5% and 30% by weight, relative to the total weight of the capture mass.

[0056] According to an alternative embodiment of the invention, the inorganic support is alumina.

[0057] According to one variant, the capture mass used according to the invention may contain at least one group IA or IIA element, preferably sodium or calcium. If the capture mass contains at least one group IA or IIA element, its content is preferably between 0.01% and 5% by weight, very preferably between 0.02% and 2% by weight, relative to the total weight of the capture mass.

[0058] The capture mass used according to the invention is advantageously in the form of grains having an average diameter between 0.5 and 10 mm. The grains may have any shape known to the person skilled in the art, for example, beads (preferably having a diameter between 1 and 6 mm), extrudates, tablets or hollow cylinders. Preferably, the capture mass is in the form of extrudates having an average diameter between 0.5 mm and 10 mm, preferably between 0.8 mm and 3.2 mm, or in the form of beads having an average diameter between 0.5 mm and 10 mm, preferably between 1.4 mm and 4 mm. The term "average diameter" of the extrudates is understood to mean the average diameter of the circle circumscribing the cross section of these extrudates.

[0059] The capture mass used in the context of the process according to the invention can be prepared according to any method known to the skilled artisan, by way of example only, dry impregnation of a shaped porous inorganic support with the active phase precursor, or by kneading the active phase precursor with the structuring phase precursor and then shaping. Before being activated, the capture mass is dried and optionally calcined to obtain the active nickel phase, at least in part in oxide form (NiO).

[0060] The capture mass undergoes an activation step so that at least part of the nickel element is in reduced form, with a weight ratio of Ni° / NiO between 0.25 and 4, preferably between 0.4 and 3, and more preferentially between 0.5 and 2.5. Preferably, the reducing agent is a gas, and very preferably, the reducing agent is hydrogen. Hydrogen may be used pure or in a mixture, for example a mixture of hydrogen / nitrogen, hydrogen / argon or hydrogen / methane. If hydrogen is used in a mixture, any ratio may be assumed. The reduction treatment is preferentially carried out at a temperature between 200°C and 500°C, preferably between 300°C and 450°C. The duration of the reduction treatment is generally between 1 hour and 40 hours, preferably between 1 hour and 24 hours. The heating up to the desired reduction temperature is generally slow, for example set between 0.1°C / min and 10°C / min, preferably between 0.3°C / min and 7°C / min. If the step of activating the capture mass is carried out ex situ, i.e. outside the reactor of the mercaptan capture process according to the invention, it is advantageous to carry out a passivation step to protect the capture mass. This passivation step can be carried out in the presence of an oxidizing gas according to any method known to the skilled artisan. After the passivation step, the final activation step is advantageously carried out in situ, i.e. in the reactor of the mercaptan capture process according to the invention, under a stream of a reducing gas such as hydrogen or under the stream of the raw material to be treated, at a temperature between 100°C and 300°C, preferably between 100°C and 250°C.

[0061] The invention is illustrated by the following examples, without limiting its scope. EXAMPLES

[0062] Example 1: Capture mass The alumina support has a diameter of 1.6 mm and a specific surface area of ​​213 m 2 It is provided in the form of an extrudate (sold by Axens®) with a pore volume of 0.53 ml / g and a pore size of 0.53 ml / g.

[0063] A nickel nitrate solution containing 14% Ni by weight (Parchem®) is also provided.

[0064] The capture mass is prepared by dry impregnation of 50 g of alumina support with 21.9 ml of aqueous nickel nitrate solution, followed by drying in air at 120° C. for 12 hours, and then calcination at 450° C. for 6 hours. The operation of dry impregnation and subsequent heat treatment is repeated six times on the recovered solid.

[0065] The captured mass contains 35.1% nickel by weight based on the total weight of the solids. 2 / g.

[0066] Example 2: Activation of Capture Mass 10 ml of the capture mass are subjected to an activation treatment under a pure hydrogen flow of 10 l / h for 2 h at various temperatures with a gradient of 1° C. per minute. Table 1 below shows the various Ni° / NiO ratios from X-ray diffraction measurements obtained depending on the activation temperature.

[0067] [Table 1]

[0068] Example 3: Evaluation of the performance of capture masses for the capture of mercaptans The performance of the entrapment mass is evaluated by monitoring the dynamic entrapment performance of hexanethiol in a hydrocarbon matrix.

[0069] A test column with a diameter of 1 cm is pre-introduced with 10 ml of solid pre-activated in the presence of hydrogen under an inert atmosphere. A hydrocarbon matrix, called feedstock, is pre-prepared by mixing heptane, 1-hexene and 1-hexanethiol so as to obtain a matrix containing 2000 ppm by weight of sulfur and 10% by weight of olefins. The column containing the solid is then heated at 200 °C, 1.7 MPa pressure, under a heptane flow, with an hourly space velocity of 8 h -1 The experiment was carried out at various temperatures, under a pressure of 1.7 MPa, and with a space velocity of 8 h per hour. -1The column is started when the feed stream is replaced with 100% sulfur. The effluent leaving the column is analyzed to determine the sulfur concentration of the treated matrix, and the yield loss is determined by weighing the liquid effluent relative to the feed input.

[0070] The dynamic capacity of a solid corresponds to the amount of sulfur that the solid will retain when the sulfur concentration in the effluent corresponds to one-tenth of the feed concentration.

[0071] The energy efficiency of the capture of sulfur compounds is expressed as the amount of energy required to be supplied to the system, starting from an ambient temperature of 20°C, as follows: E=mC P It is measured using ΔT, where "E" is the amount of energy supplied to the system (in kJ), "m" is the mass of the treated feedstock (in kg) when the sulfur concentration in the effluent corresponds to one-tenth of the feedstock concentration, "Cp" is the specific heat capacity of the feedstock (in kJ / kg / K, taken as 2.7), and "ΔT" is the difference between the test temperature and the ambient temperature (taken as 20°C). Then, by dividing the value of "E" by the sulfur loading, it is possible to express the energy efficiency as the amount of energy supplied to the system per sulfur loading (kJ / gS).

[0072] The results are summarized in Table 2 below.

[0073] [Table 2]

[0074] From these examples it becomes clear that only when carried out according to the invention at temperatures between 170°C and 220°C and Ni° / NiO weight ratios between 0.25 and 4, high performances in the capture of hexanethiol mercaptan can be achieved while minimizing yield losses and optimizing the energy efficiency of the process.

Claims

1. 1. A process for capturing mercaptans contained in a sulfur-containing hydrocarbon feedstock, the process being carried out in the presence of a capture mass comprising a nickel-based active phase, the weight ratio of nickel present in said capture mass in reduced form to nickel present in said capture mass in oxide form being between 0.25 and 4, at a temperature of between 170°C and 220°C, a pressure of between 0.2 MPa and 5 MPa, and an hourly space velocity, defined as the volumetric flow rate of the feedstock at the inlet per volume of capture mass, of between 0.1 h-1 and 50 h-1, and an inorganic support selected from the group consisting of alumina, silica, silica-alumina, and clay.

2. 2. The process of claim 1, wherein the weight ratio of nickel present in the capture mass in reduced form to nickel present in the capture mass in oxide form is from 0.4 to 3.

3. 3. The process of claim 1 or 2, wherein the weight ratio of nickel present in the capture mass in reduced form to nickel present in the capture mass in oxide form is from 0.5 to 2.

5.

4. The process of claim 1, wherein the process is carried out at a temperature of from 180°C to 210°C.

5. 2. The process of claim 1, wherein the nickel content is 20% to 70% by weight of elemental nickel based on the total weight of the capture mass.

6. 10. The process of claim 1, wherein the capture mass has a specific surface area of ​​150 m2 / g to 250 m2 / g.

7. 10. The process of claim 1, wherein the capture agglomerate has a total pore volume of from 0.20 ml / g to 0.70 ml / g as measured by mercury porosimetry.

8. 2. The process of claim 1, wherein the content of elemental aluminum and / or elemental silicon in the capture mass is 5% to 45% by weight relative to the total weight of the capture mass.

9. 10. The process of claim 1, wherein the support is alumina.

10. 10. The process of claim 1, wherein the hydrocarbon feedstock is a feedstock that has been partially desulfurized by a catalytic hydrodesulfurization process.

11. 11. The process of claim 10, wherein the hydrocarbon feedstock to be treated is a partially desulfurized catalytically cracked gasoline having a boiling point below 350°C, containing 5% to 60% by weight of olefins based on the total weight of the feedstock, and containing less than 100 ppm by weight of sulfur.