Mercaptan removal process using CO2 inactivated capture mass

Abstract

The present invention relates to a process for capturing mercaptans contained in a sulfur-containing hydrocarbon feedstock, the process being carried out at a temperature between 40°C and 250°C, a pressure 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 the capture mass, of 0.1 h -1 ~50h -1 in the presence of a capture mass comprising an active phase containing at least one Group VIII, IB or IIB metal and a porous oxide or porous oxide mixture, the active metal having previously been activated by reduction and then passivated for loading by carbon dioxide treatment.

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 trapping 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 sulfur and nitrogen oxide content in particular in vehicle exhaust gases. 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, resulting 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 through adsorption-type processes or by combining hydrodesulfurization or adsorption steps, but more efficient trapping masses for mercaptan extraction are still needed to suppress the hydrogenation reactions that cause the reduction of the octane number of the target gasoline.

[0008] For example, US Patent Application No. 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 group VIII, IB, IIB or IVA metal, the adsorbent being used in reduced form in the absence of hydrogen and at temperatures above 40°C.

[0013] Generally, when used in capture and desulfurization processes, the abovementioned solids use active metals in the reduced state, i.e. in the zero-valent state. During production, the metals of the active phase of the solids are produced in oxide form. A reduction activation step is then required to convert these oxides, even partially, into reduced metals. Industrially, the reduction of these solids in industrial adsorption units is often of little advantage due to operating time constraints and the technical impossibility of reaching the temperatures required for the activation step. The activation step is therefore carried out externally, for example in another reduction reactor. To be able to transport the reduced solids to the industrial reactor, the latter must be deactivated. This deactivation treatment consists of carrying out a surface treatment of the reduced metals to reduce their reactivity towards air. The deactivation treatment must be properly controlled. In the event of insufficient deactivation, there is an industrial hazard with uncontrolled heat generation during handling, storage or loading of the solid material in the adsorption unit. This heat generation is associated with oxidation at the surface of the zero-valent metal or in the center of the zero-valent metal particles. If the passivation treatment is too strong, there is a risk that the solid will be damaged and lose all or part of its ability to capture sulfur-containing molecules. These passivation methods are based on the surface protection of the zero-valent metal particles formed in the reduction step. This surface passivation is usually carried out by mild oxidation with oxygen, but can also be carried out by weak adsorption of molecules such as carbon dioxide on the surface. These operations are strictly controlled to avoid uncontrolled heat generation.

[0014] Applicants have surprisingly discovered that certain passivation operating conditions applied to the capture mass can improve the performance of the mercaptan capture process and avoid the formation of soluble sulfur-containing organometallic compounds when used with said capture mass. Without wishing to be bound by any theory, the use of a passivation step for the capture mass in the presence of carbon dioxide can avoid the formation of metal hydroxythiolates, preventing leaching of the capture mass and the formation of off-spec hydrocarbon feedstocks. [Prior art documents] [Patent documents]

[0015] [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]

[0016] The present invention relates to a process for capturing mercaptans contained in a sulfur-containing hydrocarbon feedstock, the process being carried out at a temperature of 40°C to 250°C, a pressure of 0.2 MPa to 5 MPa, 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 an active phase comprising at least one Group VIII, Group IB or Group IIB metal and an inorganic support selected from the group consisting of alumina, silica, silica-alumina and clay, said capture mass comprising at least a) carrying out a step of contacting said inorganic support with at least one precursor of said active phase to obtain a capture mass precursor; b) drying the capture mass precursor obtained at the end of step a) at least once at a temperature below 250° C. to obtain a dry capture mass; c) optionally, heat treating the dried capture mass obtained at the end of step b) at least once at a temperature between 250° C. and 1000° C. to obtain a calcined capture mass; d) carrying out a step of reducing the dried capture agglomerate obtained at the end of step b) or the calcined capture agglomerate obtained at the end of step c) by contacting the capture agglomerate precursor with a reducing gas at a temperature between 100° C. and 500° C. to obtain a capture agglomerate at least partially in reduced form; e) carrying out a step of inactivating the capture mass, at least partially in reduced form, obtained at the end of step d) in the presence of carbon dioxide in order to obtain the capture mass; The present invention relates to a process for preparing a process for preparing a compound comprising the steps of:

[0017] According to one or more embodiments, steps a) to e) of the process for preparing the capture mass are performed outside the reaction section of the capture process.

[0018] According to one or more embodiments, the process for preparing the capture mass further comprises a step f) of activating the capture mass obtained at the end of step e), said step f) being carried out at a temperature between 100°C and 300°C under a flow of reducing gas or under a flow of the raw material to be treated.

[0019] According to one or more embodiments, step f) of the process for preparing the capture mass is carried out in the reaction section of the capture process.

[0020] According to one or more embodiments, the reaction section of the capture process includes between 2 and 5 reactors.

[0021] According to one or more embodiments, step e) of the process for preparing the capture mass is carried out with a concentration pulse of dilute carbon dioxide at a temperature between 0°C and 90°C.

[0022] According to one or more embodiments, step d) of the process for preparing the capture mass is carried out in the presence of hydrogen as reducing gas.

[0023] According to one or more embodiments, the content of the group VIII, IB or IIB element is between 10% and 80% by weight based on the total weight of the capture mass.

[0024] According to one or more embodiments, the Group VIII, IB or IIB metal is selected from nickel, copper or zinc.

[0025] According to one or more embodiments, the metal of the active phase of the capture mass is nickel.

[0026] 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.

[0027] According to one or more embodiments, the capture mass is 150 m 2 / g~250m 2 / g.

[0028] 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.

[0029] According to one or more embodiments, the hydrocarbon feedstock is a feedstock that has been partially desulfurized by a catalytic hydrodesulfurization process.

[0030] 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

[0031] 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.

[0032] 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.

[0033] In this specification, following the IUPAC convention, "micropores" are understood to mean pores with a diameter of less than 2 nm, i.e. less than 0.002 μm, "mesopores" to mean pores with a diameter of more than 2 nm, i.e. more than 0.002 μm and less than 50 nm, i.e. less than 0.05 μm, and "macropores" to mean pores with a diameter of 50 nm or more, i.e. more than 0.05 μm.

[0034] 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.

[0035] For better accuracy, the values ​​of total pore volume in ml / g reported 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 intrusion 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).

[0036] The content of metallic elements (group VIII, IB or IIB metals) is measured by X-ray fluorescence.

[0037] (Mercaptan capture) 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.

[0038] The mercaptan capture step is generally carried out at a temperature of 40°C to 250°C, preferably 100°C to 250°C, and more preferably 130°C to 240°C.

[0039] The process generally lasts for 0.1 h. -1 ~50h -1 , preferably 0.5h -1 ~20h -1 , preferably 0.5h -1 ~10h -1The 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).

[0040] The mercaptan capture process is generally carried out in the absence of hydrogen. The feedstock should preferably remain liquid, which requires sufficient pressure above the vaporization pressure of the feedstock. 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.

[0041] 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.

[0042] 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.

[0043] 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 3 The 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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

[0050] The process is generally carried out at a pressure between 0.5 MPa and 5 MPa, preferably between 1 MPa and 3 MPa.

[0051] 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.

[0052] 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.

[0053] 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 (desorbers, stabilization columns, 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.

[0054] (captured mass) The capture mass used in the context of the process according to the invention comprises at least one Group VIII, IB or IIB metal-based active phase and an inorganic support selected from the group consisting of alumina, silica, silica-alumina and clay.

[0055] The content of group VIII, IB or IIB elements is preferably between 10% and 80% by weight, preferably between 20% and 70% by weight, very preferably between 30% and 70% by weight, relative to the total weight of the capture mass.

[0056] Preferably, said Group VIII, IB or IIB metal is selected from nickel, copper or zinc. Highly preferably, said metal is nickel.

[0057] 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.

[0058] 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.

[0059] Preferably, the content of elemental aluminum and / or elemental silicon in said capture mass is preferably between 5% and 45% by weight, very preferably between 5% and 30% by weight, relative to the total weight of the capture mass.

[0060] Preferably, the inorganic support is alumina.

[0061] 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.

[0062] 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.

[0063] (Preparation process of captured mass) According to the invention, the capture mass is obtained according to a preparation process having the following steps: a) carrying out a step of contacting the inorganic support with at least one precursor of the active phase to obtain a capture mass precursor. b) drying the capture mass precursor obtained at the end of step a) at least once at a temperature below 250° C. to obtain a dry capture mass. c) optionally carrying out at least one heat treatment of the dried capture mass obtained at the end of step b) at a temperature between 250° C. and 1000° C. in order to obtain a calcined capture mass. d) carrying out a step of reducing the dried capture agglomerates obtained at the end of step b) or the calcined capture agglomerates obtained at the end of step c) by contacting the capture agglomerate precursor with a reducing gas at a temperature between 100°C and 500°C in order to obtain capture agglomerates at least partially in reduced form. e) carrying out a step of inactivating the capture mass, at least partially in reduced form, obtained at the end of step d) in the presence of carbon dioxide.

[0064] Steps a) to e) of the capture mass preparation process are described below.

[0065] Steps a) to e) are typically carried out outside the reaction section of the capture process.

[0066] Process a) Advantageously, the step of contacting the inorganic support with at least one precursor of an active phase based on at least one of group VIII, IB or IIB metals can be carried out by dry impregnation or excess impregnation, or by deposition-precipitation or by other methods known to those skilled in the art. By way of example, mention can be made of a method in which a shaped porous inorganic support is dry impregnated with the active phase precursor, or a method in which the precursors of the active phase and the structured phase are kneaded together and then shaped.

[0067] A capture mass precursor is obtained.

[0068] Step b) According to step b), the capture mass precursor obtained in step a) is dried at a temperature below 250°C, advantageously at a temperature between 50°C and 180°C, preferably at a temperature between 70°C and 150°C, very preferably at a temperature between 75°C and 130°C.

[0069] The drying step is preferentially carried out for a period between 1 hour and 16 hours, preferably between 4 hours and 14 hours, preferentially under an inert atmosphere or an oxygen-containing atmosphere.

[0070] The drying step may be carried out in any manner known by a person skilled in the art. It is advantageously carried out at atmospheric pressure or under reduced pressure. Preferably, this step is carried out at atmospheric pressure. It is advantageously carried out using hot air or other hot gases. Preferably, the gas used is either air or an inert gas such as argon or nitrogen. Very preferably, drying is carried out in the presence of nitrogen and / or air.

[0071] A dry captured mass is obtained.

[0072] Step c) (Optional step) According to the optional step c), the dried capture mass obtained at the end of step b) is preferentially subjected to a calcination treatment at a temperature between 250° C. and 1000° C., preferably between 250° C. and 650° C., very preferably between 300° C. and 500° C., under an inert atmosphere (for example nitrogen) or under an oxygen-containing atmosphere (for example air). The duration of this heat treatment is generally less than 16 hours, preferably between 1 hour and 10 hours, and more preferentially between 2 hours and 8 hours. The calcination step may be carried out in any manner known by the person skilled in the art. It is advantageously carried out in a transverse bed or in a fluidized bed using hot air or other hot gases.

[0073] A fired capture mass is obtained.

[0074] Step d) According to step d), at least one reduction treatment step is carried out in the presence of a reducing gas after step b) and optionally after step c) in order to obtain a capture mass containing at least one group VIII, IB or IIB metal, at least partially in metallic form. This treatment makes it possible to form metal particles at least partially in the zero-valent state. The reducing gas is preferably 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.

[0075] The reduction treatment is preferentially carried out at temperatures between 100° 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 rate of temperature rise to the desired reduction temperature is generally small, preferably set at 0.1° C. / min to 10° C. / min, preferably 0.3° C. / min to 7° C. / min.

[0076] The step of activating the capture mass is generally carried out ex situ, i.e., outside the reactor of the mercaptan capture process according to the present invention.

[0077] A captured mass is obtained that is at least partially in reduced form.

[0078] Process e) The captured mass, at least partially in reduced form, is then subjected to a passivation step to protect the captured mass.

[0079] The inerting step can be carried out in a variety of ways, generally in the gas phase. The exotherm can be controlled by using a gas diluted with a gas inert to the solid, or by intermittent inerting gas or gas pulses, or by a combination of various methods. The inerting step is carried out in the presence of carbon dioxide according to any method known by a person skilled in the art.

[0080] This inactivation treatment is preferentially carried out at temperatures between 0°C and 90°C, preferably between 5°C and 50°C, and more preferably between 15°C and 30°C, by means of a concentration pulse of dilute carbon dioxide.

[0081] A captured mass is obtained.

[0082] Step f) (optional) After the deactivation 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 feedstock to be treated, at a temperature between 100° C. and 300° C., preferably between 100° C. and 250° C.

[0083] The invention is illustrated by the following examples, without limiting its scope. EXAMPLES

[0084] Example 1: Capture mass precursor The alumina support has a diameter of 1.4 mm to 4 mm and a specific surface area of ​​205 m 2 It is provided in the form of beads (sold by Axens®) with 1.0 g / g and a total pore volume of 0.75 ml / g. An aqueous nickel nitrate solution containing 14 wt% Ni (Parchem®) is also provided.

[0085] The capture mass precursor is prepared by dry impregnation of 50 g of alumina support with 30.7 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 four times on the recovered solid.

[0086] The capture mass precursor contains 34.9% nickel and 26.8% aluminum by weight based on the total weight of the solids. 2 / g.

[0087] Example 2: Capture mass A (not according to the invention) The capture mass precursor of Example 1 is introduced into a reduction reactor. The solid is activated in situ at 400° C. for 2 hours under a hydrogen flow of 1 L per hour and per gram of solid. The solid is then cooled. When the temperature is below 25° C., the solid is recovered without any additional measures. An exotherm is observed upon contact with air. The solid is then introduced into a test column with a diameter of 1 cm. The solid is reactivated in situ at 200° C. for 2 hours under a hydrogen flow of 1 L per hour and per gram of solid.

[0088] Example 3: Capture mass B (not according to the invention) The capture mass precursor of Example 1 is introduced into a reduction reactor.

[0089] The solid is activated in situ at 400° C. for 2 hours under a hydrogen flow of 1 L per hour and per gram of solid.

[0090] The solid is then cooled under a nitrogen flow of 1 L per hour and per gram of solid.

[0091] Once the temperature reaches 25° C., a pulse inerting program is started with a flow rate of 1 L per hour and per gram of solids. The solids are exposed to a stream of air diluted with nitrogen to give an oxygen concentration of 1% by volume.

[0092] If the temperature rise exceeds 2°C, the airflow is replaced by a pure nitrogen flow.

[0093] When the temperature reaches 25°C again, repeat the procedure.

[0094] A series of pulses of diluted 1% oxygen followed by a pulse of nitrogen are repeated until the reaction does not exotherm by more than 2°C.

[0095] In this case, the solid is exposed to 1% diluted oxygen for 1 hour, followed by a second pulse sequence under a flow of 5% diluted oxygen. The series of 5% diluted oxygen pulses, followed by nitrogen pulses, are repeated until the reaction no longer exotherms by more than 2°C.

[0096] In this case, the solid is exposed to 5% diluted air for 1 hour, followed by a second pulse sequence under a stream of 20% diluted oxygen. When the reaction does not exotherm by more than 2°C, the solid is collected and then introduced into a test column with a diameter of 1 cm.

[0097] The solid is reactivated in situ at 200° C. for 2 hours under a hydrogen flow of 1 L per hour and per gram of solid.

[0098] Example 4: Capture mass C (according to the present invention) The capture mass of Example 1 was introduced into the reduction reactor.

[0099] The solid is activated in situ at 400° C. for 2 hours under a hydrogen flow of 1 L per hour and per gram of solid.

[0100] The solid is then cooled under a nitrogen flow of 1 L per hour and per gram of solid.

[0101] Once the temperature reaches 25° C., a pulse inactivation program is initiated at a flow rate of 1 L per hour and per gram of solids.

[0102] The solid is exposed to a flow of carbon dioxide diluted with nitrogen to give a carbon dioxide concentration of 1% by volume.

[0103] If the temperature rise exceeds 2°C, the airflow is replaced by a pure nitrogen flow.

[0104] Once the temperature has dropped to 25°C, repeat the procedure.

[0105] A series of pulses of 1% diluted carbon dioxide followed by a nitrogen pulse are repeated until the reaction does not exotherm by more than 2°C.

[0106] In this case, the solid is exposed to 1% diluted carbon dioxide for 1 hour, followed by a second pulse sequence under a flow of 5% diluted carbon dioxide.

[0107] A series of pulses of 5% diluted carbon dioxide followed by a nitrogen pulse are repeated until the reaction does not exotherm by more than 2°C.

[0108] In this case, the solid is exposed to 5% carbon dioxide for 1 hour, followed by a second pulse sequence under a stream of carbon dioxide diluted to 20%.

[0109] When the reaction exotherm does not exceed 2°C, the solid is collected and introduced into a 1 cm diameter test column.

[0110] The solid is reactivated in situ at 200° C. for 2 hours under a hydrogen flow of 1 L per hour and per gram of solid.

[0111] Example 5: Evaluation of the performance of capture masses for the capture of mercaptans The performance evaluation of masses A, B, and C is carried out by monitoring their dynamic trapping performance of hexanethiol in a hydrocarbon matrix.

[0112] The tests are carried out in a test column in which the solids have been previously introduced and reactivated in situ as described in the examples. A hydrocarbon matrix, called feed, is previously prepared by mixing heptane, 1-hexene and 1-hexanethiol to obtain a matrix containing 2000 ppm by weight of sulfur and 10% by weight of olefins. The column containing the solids is then heated at 150 °C, 1.7 MPa pressure, under a stream of heptane with an hourly space velocity of 8 h -1 The experiment was carried out at 150°C, 1.7 MPa pressure, and 8 h hourly space velocity with heptane flow. -1 The start of the process is 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.

[0113] The dynamic performance of the solids corresponds to the amount of sulfur retained per gram of solids introduced when the sulfur concentration in the effluent corresponds to one tenth of the feed concentration. The test is continued as long as the sulfur concentration in the effluent is less than half the feed concentration, i.e. less than 1000 ppm by weight. The performance at the end of the test corresponds to the amount of sulfur retained per gram of solids when the test is stopped. The results are summarized in Table 1 below.

[0114] [Table 1]

[0115] Capture mass A, prepared according to Example 2, shows poor performance. From the beginning of the test, colored effluent containing sulfur-containing organometallic species is observed. At the end of the test, the performance is poor, probably due to excessive uncontrolled deactivation and degradation of the active phase. Reactivation does not restore the performance.

[0116] Capture mass B, prepared according to Example 3, shows poor performance. Right from the start of the test, colored effluent containing sulfur-containing organometallic species is observed, resulting in insufficient purification of the hydrocarbon stream.

[0117] Capture mass C, prepared according to Example 4 and in accordance with the present invention, exhibits good performance: the dynamic capacity of the solid is maintained even when the solid is subjected to external reduction and passivation steps.

Claims

1. A process for capturing mercaptans contained in a sulfur-containing hydrocarbon feedstock, carried out at a temperature of 40°C to 250°C, a pressure of 0.2 MPa to 5 MPa, and 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 to 50 h-1, in the presence of a capture mass comprising an active phase containing at least one Group VIII, IB or IIB metal, and an inorganic support selected from the group consisting of alumina, silica, silica-alumina, and clay, said capture mass comprising at least a) carrying out a step of contacting said inorganic support with at least one precursor of said active phase to obtain a capture mass precursor; b) drying the capture mass precursor obtained at the end of step a) at least once at a temperature below 250°C to obtain a dry capture mass; c) optionally, heat treating the dried capture mass obtained at the end of step b) at least once at a temperature between 250°C and 1000°C to obtain a calcined capture mass; d) carrying out a step of reducing the dried capture mass obtained at the end of step b) or the calcined capture mass obtained at the end of step c) by contacting the capture mass precursor with a reducing gas at a temperature between 100°C and 500°C to obtain a capture mass in at least partially reduced form; e) carrying out a step of inactivating the capture mass, at least partially in reduced form, obtained at the end of step d) in the presence of carbon dioxide, to obtain the capture mass; The process is obtained by a preparation process comprising:

2. 2. The process of claim 1, wherein steps a) to e) of the process for preparing the capture mass are performed outside the reaction section of the capture process.

3. 3. The process according to claim 1 or 2, characterized in that the process for preparing the capture mass further comprises a step f) of activating the capture mass obtained at the end of step e), said step f) being carried out at a temperature between 100°C and 300°C under a stream of reducing gas or under a stream of raw material to be treated.

4. 4. The process according to claim 3, characterized in that step f) of the process for preparing the capture mass is carried out in the reaction section of the capture process.

5. 10. The process of claim 1, wherein the reaction section of the capture process comprises 2 to 5 reactors.

6. 10. The process of claim 1, wherein step e) of the process for preparing the capture mass is carried out by a concentration pulse of dilute carbon dioxide at a temperature between 0°C and 90°C.

7. 10. The process of claim 1, wherein step d) of the process for preparing the capture mass is carried out in the presence of hydrogen as a reducing gas.

8. 2. The process of claim 1, wherein the content of the Group VIII, IB or IIB element is 10% to 80% by weight based on the total weight of the capture mass.

9. 2. The process of claim 1, wherein the Group VIII, IB, or IIB metal is selected from nickel, copper, or zinc.

10. 10. The process of claim 9, wherein the metal of the active phase of the capture mass is nickel.

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

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

13. 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.

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

15. 15. The process of claim 14, 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.