Method for regenerating trapping mass for trapping heavy metals

Abstract

The present invention relates to a method of regenerating a capture mass for capturing heavy metals, the capture mass being loaded with heavy metals and placed in contact with a sulfiding stream; a regenerated capture mass having a heavy metal content of 0.1% to 45% by weight relative to the total weight of the regenerated capture mass; and a method of capturing heavy metals from a gaseous or liquid feedstock, the method comprising placing the feedstock in contact with the regenerated capture mass.

Description

[Technical field]

[0001] The present invention relates to a method for treating heavy metals (5 g / cm 3 The invention is in the field of the treatment of liquid or gaseous effluents, in particular effluents of petroleum origin and their derivatives, for example gases of industrial origin such as synthesis gas, natural gas and liquid hydrocarbons, containing heavy metals (metals exhibiting a density exceeding 1000 mg / kg / day). More precisely, the invention relates to the capture of heavy metals, in particular mercury, present in gaseous or liquid effluents. [Background technology]

[0002] It is known that certain natural feedstocks, such as natural gas condensates, crude oil or fractions resulting from its distillation, and natural gas, may contain a number of metals. In particular, mercury is a metallic contaminant found in gaseous or liquid hydrocarbons occurring in many parts of the world, such as the Gulf of Niger, South America, North Africa or the Asia-Pacific region.

[0003] Removal of mercury from hydrocarbons is desirable at an industrial level for several reasons. On the one hand, mercury is toxic, and its presence in hydrocarbons poses a risk to workers working in contact with these products. Mercury in elemental form is volatile and poses a serious risk of neurotoxicity via inhalation. In organic form, mercury poses a similar risk of neurotoxicity via dermal contact.

[0004] On the other hand, the presence of mercury in hydrocarbons adversely affects the conventional processing operations used to upgrade these hydrocarbons. Conventionally, the hydrocarbons are subjected to catalytic reactions, for example the selective hydrogenation of olefins produced by steam cracking or catalytic cracking of liquid hydrocarbons. In fact, the catalysts used generally contain noble metals, for example platinum and palladium, and can be deactivated by mercury, since mercury induces the deactivation of the catalysts by amalgamation with nanoparticles of noble metals. The reduction of the exposed surface area of ​​the active phase of the catalysts or the change of their electronic state leads to a very large loss of their catalytic activity.

[0005] Finally, the presence of mercury in the gases sent to the cryogenic distillation can lead to the risk of industrial accidents. Cryogenic exchangers are usually made from elemental aluminium. Under certain conditions, mercury can amalgamate with the aluminium and cause embrittlement of the material, leading in the most severe cases to the explosion of the aluminium parts.

[0006] For these reasons, among others, it is desirable to remove mercury from, or at least reduce the concentration of mercury in, gaseous or liquid hydrocarbon effluents.

[0007] Industrially, the removal of mercury from gaseous or liquid effluents is carried out by passing the effluent to be treated through a guard bed packed with an adsorbent material, also known as a capture mass. The impurity to be removed, in this case mercury, is irreversibly retained, preferably by chemical adsorption, in or on the surface of the capture mass. The effluent discharged from the capture mass is then purified.

[0008] The capture of mercury can be carried out by reacting it with an active phase based on elemental sulfur in the capture mass. This is because elemental sulfur S(s) reacts irreversibly with elemental mercury Hg(g / liquid) to form mercury(II) sulfide HgS(s). The term "Hg(g / liquid)" is understood to mean that the mercury is dissolved in a gaseous (gas) or liquid (liquid) mobile phase. In contrast, "(s)" denotes the solid phase formed by the active phase of the capture mass and the products of the reaction.

[0009] The reaction between elemental sulfur and elemental mercury is spontaneous and exhibits a negative free energy ΔG (kJ / mol) over a wide temperature range, typically from 0°C to 150°C. The product formed (HgS), called cinnabar or black cinnabar, is a mineral phase that is chemically inert and solid over a very large temperature range. Mercury is thus captured in a capture mass and the effluent to be treated is purified.

[0010] Conventionally, capture masses based on elemental sulfur are obtained by the method of impregnation of elemental sulfur on a support of activated carbon type.

[0011] However, capture masses based on elemental sulfur deposited on activated carbon often have stability problems when the effluent to be treated is liquid or when the effluent to be treated is gaseous and wet, since the active phase can be entrained by water or another liquid. This phenomenon causes a significant reduction in the lifetime of the capture mass, which is associated with weak energetic interactions between the active phase and the surface of the activated carbon, oxidation of the active phase or the solubility of sulfur in these media.

[0012] To overcome these drawbacks, it is possible to use capture masses based on metal sulfides. Copper sulfide is used, in particular due to its stability and its low production costs. WO 02 / 04333 describes the fact that elemental mercury (Hg(gas / liquid)) irreversibly reduces copper(II) sulfide, CuS(solid), to form copper(I) sulfide (Cu2S(solid)) and mercury(II) sulfide (HgS(solid)). It is a gas / solid or liquid / solid reaction, which is even more favorable from a kinetic point of view, because of the large specific surface area of ​​the active phase (CuS in this case).

[0013] Metal sulfides can be used in bulk or supported form. In this second option, the role of the support is to disperse the active phase. Solids known as bulk solids are described, for example, in US Pat. No. 5,399,663. Patents such as US Pat. Nos. 5,493,621, 5,496,713 and 5,521,722 describe the use of capture masses of the CuS type deposited on supports essentially based on alumina.

[0014] Capture masses are generally used in a non-regenerative manner because, once captured, the mercury is converted to HgS, which is itself deposited at the surface of the solid. In fact, HgS is a very thermally stable solid, which decomposes only above 737°C under oxygen. In fact, to regenerate these masses, it would be necessary to process them at temperatures above 737°C, which would be energetically very expensive. Moreover, this requires specific equipment and in most cases would not be performed at the industrial site where the heavy metal capture masses are used.

[0015] Moreover, the copper phase available for reaction with Hg is mainly the CuS phase. In fact, the thermodynamically stable phase at high temperatures is the CuS phase. Studies carried out at 278°C to 354°C notably show that prolonged sulfidation of CuO under H2S / N2 leads to CuS and then to Cu7S4 (Non-Patent Document 1).

[0016] Therefore, in view of the prior art, activity recovery of heavy metal capture masses has been little studied.Moreover, more generally, spent masses for capturing elements that are chemisorbed or reacted with the active phase are not regenerated because elements captured by chemisorption or chemical reaction, e.g., mercury, are irreversibly captured. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] U.S. Patent No. 7,645,306 [Patent Document 2] European Patent No. 0480603 [Patent Document 3] French Patent No. 2980722 [Patent Document 4] French Patent Invention No. 2764214 [Patent Document 5] U.S. Patent No. 7,560,413 [Non-patent literature]

[0018] [Non-Patent Document 1] Yasyerli, S., Dogu, G., Ar, I. and Dogu, T., Industrial & Engineering Chemistry Research, 2001, 40(23), p. 5206-5214 Summary of the Invention [Means for solving the problem]

[0019] (Objective of the Invention) In the above context, a first objective of the present description is to overcome the problems of the prior art and to provide a method for rejuvenation of agglomerates for the capture of heavy metals. Advantageously, the rejuvenation method allows to restore the heavy metal capture capacity to a capture agglomerate loaded with heavy metals. Thus, the used capture agglomerates can be reused instead of being removed to be replaced.

[0020] In particular, the Applicant Company has discovered in a surprising manner that reactivation of metal-containing capture masses by sulfurization makes it possible for said masses to regain their ability to capture heavy metals, without the release of mercury, by the restoration of all or part of the active phase, for example copper in its CuS form.

[0021] Advantageously, upon completion of the activity recovery by sulfidation according to the invention, the capture mass for heavy metals has an improved ability to capture heavy metals compared to the capture mass before treatment. The invention also relates to a method for using these capture masses in the removal of heavy metals, such as mercury, from gaseous or liquid hydrocarbon feedstocks.

[0022] Advantageously, the reactivation by sulfurization according to the present invention thus makes it possible to extend the life of the capture mass and, as a result, to free up space for the loading and unloading of the capture mass, thereby simplifying the operation and reducing the operating costs.

[0023] According to a first aspect, the above objects, as well as other advantages, are obtained by a method for reactivating a heavy metal capture mass containing heavy metals, the capture mass being contacted with a sulfiding stream.

[0024] According to one or more embodiments, the heavy metal is selected from the group consisting of mercury, arsenic and lead.

[0025] According to one or more embodiments, the heavy metal is mercury.

[0026] According to one or more embodiments, the sulfurizing stream is selected from the group consisting of hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, methanethiol, or any other sulfur-containing molecule that can be decomposed under the process conditions to give hydrogen sulfide or can be decomposed in the presence of a metal sulfide, e.g., copper or iron sulfide, to give a sulfurizing molecule.

[0027] According to one or more embodiments, the sulfurization stream is delivered at a gas hourly space velocity (GHSV) of 10 h -1 ~5000h -1 It is.

[0028] According to one or more embodiments, the sulfurization stream is fed at a liquid hourly space velocity (LHSV) of 0.1 h -1 ~50h -1 It is.

[0029] According to one or more embodiments, the sulfiding stream is delivered at a pressure between 0.1 MPa and 15 MPa and / or a temperature between 0°C and 600°C.

[0030] According to one or more embodiments, the heavy metal-laden capture mass is a bulk solid or a supported solid comprising a refractory oxide-based porous support.

[0031] According to one or more embodiments, the heavy metal laden capture mass exhibits at least one of the following characteristics: - the pore volume is at least 0.1 mL / g; - The specific surface area must be at least 10 m 2 / g, the form is in the form of beads or extrudates of the type cylindrical, multilobed, wheel or hollow cylinder; - at least one metal M is present, said metal M being at least partially M x S yIt is present in the form of a sulfide, and said metal M is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt.

[0032] According to one or more embodiments, the heavy metal content of the heavy metal-laden capture mass is between 0.1% and 50% by weight based on the total weight of the heavy metal-laden capture mass.

[0033] According to a second aspect, the above mentioned objectives, and also other advantages, are obtained by a capture mass obtainable by the method according to the first aspect, i.e. an active recovered capture mass having a heavy metal content of 0.1% by weight to 45% by weight relative to the total weight of the active recovered capture mass.

[0034] According to one or more embodiments, the active recuperated capture mass is provided in the form of a bulk solid or supported solid comprising a refractory oxide-based porous carrier.

[0035] According to one or more embodiments, the active recovered capture mass exhibits at least one of the following characteristics: - the pore volume is at least 0.1 mL / g; - The specific surface area must be at least 10 m 2 / g, the form is in the form of beads or extrudates of the type cylindrical, multilobed, wheel or hollow cylinder; - at least one metal M is present, said metal M being at least partially x S y The metal M is present in the form of a sulfide and is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt.

[0036] According to one or more embodiments, the heavy metal is selected from the group consisting of mercury, arsenic and lead.

[0037] According to one or more embodiments, the heavy metal is mercury.

[0038] According to a third aspect, the above mentioned objects, and also other advantages, are obtained by a method for capturing heavy metals in a gaseous or liquid feedstock, comprising the step of contacting the feedstock with an active recovered capture mass obtainable by the method according to the first aspect or with an active recovered capture mass according to the second aspect.

[0039] Embodiments according to the above mentioned aspects, as well as other features and advantages, will become apparent on reading the following description, which is given purely by way of example and not of limitation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Detailed Description of the Invention The embodiments of the present invention will now be described in detail. In the following detailed description, numerous specific details are presented to provide a deeper understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without these specific details. In other cases, well-known features have not been described in detail to avoid unnecessarily complicating the present description.

[0041] (definition) The textural and structural properties of the captured mass are determined by characterization methods known to those skilled in the art.

[0042] In the following description of the invention, specific surface area is understood to mean the BET specific surface area determined by nitrogen adsorption according to standard ASTM D 3663-78, which is derived from the Brunauer-Emmett-Teller method described in the journal "The Journal of the American Chemical Society", 60, 309 (1938).

[0043] The pore volume, granule density, average size (or average diameter) of the pores and the pore distribution are determined by mercury porosimetry (see Rouquerol F., Rouquerol J. and Sing K., “Adsorption by Powders and Porous Solids: Principles, Methodology and Applications”, Academic Press, 1999). More specifically, the pore volume is measured by mercury porosimetry with a wetting angle of 140° according to standard ASTM D4284-92, for example with a Micromeritics® brand Autopore III® model instrument.

[0044] In the mercury porosimetry technique, Kelvin's law is applied, which gives the relationship between pressure, the diameter of the smallest pore through which mercury will penetrate at said pressure, the wetting angle, and the surface tension according to the following formula, where φ represents the pore diameter (nm), t represents the surface tension (48.5 Pa), θ represents the contact angle (θ=140 degrees), and P represents the pressure (MPa): φ=(4tcosθ)·10 / P.

[0045] In this patent application, the term "to comprise" is synonymous with "to include" and "to contain" (meaning the same thing), is inclusive or open, and does not exclude other elements not described. The term "to comprise" is understood to include the exclusive closed term "to consist of". The term "based on" is synonymous with "comprises at least 80% by weight of". By default, the percentages given are weight %. Furthermore, in this description, the term "essentially" or "substantially" corresponds to an approximation of ±5%, preferably ±1%, highly preferably ±0.5%, e.g. ±0.1%. For example, an effluent that essentially comprises or consists of compound A corresponds to an effluent that contains at least 95% by weight of compound A.

[0046] (Embodiment) According to a first aspect, the invention relates to a method for the recovery of activity of agglomerates for trapping heavy metals, which makes it possible to restore the ability to trap heavy metals to spent trapping agglomerates, i.e. agglomerates containing heavy metals that are intended to be removed and replaced. Advantageously, the method comprises a stage of recovery of activity of the trapping agglomerates containing heavy metals by sulphurization. At the end of the treatment according to the invention, the recovered trapping agglomerates have an improved ability to trap heavy metals compared to the spent trapping agglomerates before the treatment. The recovered trapping agglomerates obtained from the treatment according to the invention will not be the same as the original ones again, since the amount of heavy metals captured during their use is not removed by sulphurization. Moreover, the trapping capacity of the recovered trapping agglomerates obtained from this treatment is still substantially inferior to that of fresh agglomerates. This is why the method is a method of recovery of activity and not a method of regeneration.

[0047] According to the invention, the capture mass containing heavy metals ("recoverable" or "spent" capture mass) is subjected to a step a) of sulfurization with a sulfurization stream.

[0048] In step a) according to the invention, the sulfur feed to the sulfurization stream can be any precursor known to the person skilled in the art, such as hydrogen sulfide or organic sulfur compounds, such as dimethyl sulfide, dimethyl disulfide, methanethiol, or any other sulfur-containing molecule that can be decomposed under the process conditions to give hydrogen sulfide or in the presence of a transition metal sulfide to give another sulfurized molecule. According to one or more embodiments, the content in molar % of sulfur in the sulfurization stream is between 0.01% and 100%, preferably between 0.05% and 50%, even more preferably between 0.1% and 20%.

[0049] The sulfurization stream can be in gaseous or liquid form. Preferably, the sulfurization stream is in gaseous form.

[0050] According to one or more embodiments, the sulfurization stream includes a liquid or gaseous diluent, for example, nitrogen.

[0051] According to one or more embodiments, the contact temperature between the sulfide stream and the active recoverable capture mass is between 0° C. and 600° C., preferably between 20° C. and 400° C., and even more preferably between 30° C. and 350° C. Advantageously, temperatures below 250° C. promote the formation of CuS.

[0052] According to one or more embodiments, the pressure in the sulfurization stage is between 0.1 MPa and 15 MPa, preferably between 1 and 12.5 MPa, preferably between 1 MPa and 10 MPa.

[0053] According to one or more embodiments, the contact of the active recoverable capture mass with the sulfurizing stream is carried out at a gas hourly space velocity (GHSV) of 10 h -1 ~5000h -1 , preferably 50h -1 ~2000h -1 , with priority given to 100h -1 ~1100h -1The term "GHSV" is understood to mean the gas hourly space velocity of the sulfurization stream relative to the volume of the capture mass, i.e., the volume of the sulfurization stream divided by the reactor volume per hour. The reactor volume includes the volume of the capture mass and the "empty" volume between the granules.

[0054] According to one or more embodiments, the contact of the active recoverable capture mass with the liquid sulfide stream is carried out at a liquid hourly space velocity (LHSV) of 0.1 h -1 ~50h -1 , preferably 0.5h -1 ~20h -1 , with priority given to 1h -1 ~11h -1 The term "LHSV" is understood to mean the liquid hourly space velocity of the sulfurization stream relative to the volume of the capture mass, i.e., the volume of the sulfurization stream divided by the reactor volume per hour, the latter including the volume of the capture mass and the "empty" volume between the granules.

[0055] According to one or more embodiments, a sulfurized stream containing sulfur in an amount between 0.1% and 50% by weight based on the total weight of the active rejuvenable capture mass is passed through the active rejuvenable capture mass.

[0056] Advantageously, the activity recovery method according to the invention has no effect on the HgS formed: the mercury content in the sulfide stream at the outlet of step a) of the preparation method according to the invention is zero.

[0057] The process according to the invention can be carried out in situ or ex situ. Preferably, the process according to the invention is carried out in situ.

[0058] The process according to the invention can be carried out according to any method known to those skilled in the art. Preferably, the sulfurization is carried out in a reactor containing the active recoverable capture mass in the form of a fixed bed.

[0059] According to one or more embodiments, the capture mass for heavy metals is used in at least two reactors (e.g. fixed beds), arranged in series or in parallel. Advantageously, the activity recovery method can be carried out without stopping the capture of heavy metals. This is because, when the capture mass for heavy metals is exhausted and requires activity recovery, the reactor in which it is used can be disconnected from the feedstock to be refined containing heavy metals and connected to the sulfurization stream. At the same time, the feedstock to be refined is connected to one or more other reactors containing a capture mass for heavy metals (e.g. fresh or activity-recovered capture mass) that retains the ability to capture heavy metals.

[0060] The Applicant Company has also demonstrated that this activity regeneration operation could advantageously be carried out several times.

[0061] An activity-recoverable capture mass according to the present invention is any type of spent capture mass for heavy metals (ie, containing a heavy metal, such as mercury) known to those skilled in the art.

[0062] According to one or more embodiments, the atomic content of heavy metals (e.g., mercury) in the active recoverable capture mass is between 0.1% and 50% by weight, preferably between 0.5% and 30% by weight, and even more preferably between 1.0% and 20% by weight, for example between 5% and 15% by weight, based on the total weight of the active recoverable capture mass.

[0063] According to the present invention, the density of the heavy metal is 5 g / cm 3 According to one or more embodiments, the heavy metal is selected from the group consisting of mercury, arsenic and lead. According to one or more embodiments, the heavy metal is mercury.

[0064] According to one or more embodiments, the active recoverable capture mass is a capture mass that contains: at least one metal M; at least partially present in sulfide form (sulfides, disulfides); said metal M is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt, preferably copper, iron, nickel and cobalt, highly preferably copper and iron, - at least one heavy metal in the form of a sulfide.

[0065] According to one or more embodiments, the active recoverable capture mass comprises at least 0.1 wt. %, preferably at least 1 wt. %, and highly preferably at least 10 wt. % of metal M (in elemental form) based on the total weight of the active recoverable capture mass. According to one or more embodiments, the active recoverable capture mass comprises 0.1 wt. %-60 wt. %, preferably 1 wt. %-40 wt. %, and highly preferably 10 wt. %-20 wt. % of metal M (in elemental form) based on the total weight of the active recoverable capture mass.

[0066] Advantageously, the sulfurization treatment makes it possible to convert (for example oxidize) the heavy metal sulfides (HgS) and the metal sulfides (Cu2S) formed at the same time to give entities that are reactive towards heavy metals. For example, this treatment makes it possible to reconvert Cu2S to give CuS and / or FeS to give Fe2S3 and / or FeS2.

[0067] According to one or more embodiments, the active recoverable capture mass is spent CuS-based capture mass containing heavy metals such as mercury.

[0068] According to one or more embodiments, the active regenerable capture mass includes copper(I) sulfide (CuS(solid)). According to one or more embodiments, the active regenerable capture mass includes copper(I) sulfide (CuS(solid)) and mercury(II) sulfide (HgS(solid)).

[0069] According to one or more embodiments, the active recoverable capture mass is a spent FeS2- and / or FeS2-based capture mass containing heavy metals, e.g., mercury. According to one or more embodiments, the active recoverable capture mass is a spent FeS2-based capture mass containing heavy metals, e.g., mercury.

[0070] According to one or more embodiments, the active retrieval capture mass includes iron (III) sulfide (Fe2S3(sq)), and / or iron (IV) disulfide (FeS2(sq)). According to one or more embodiments, the active retrieval capture mass includes iron (II) sulfide (FeS(sq)), and iron (IV) disulfide (FeS2(sq)), and / or iron (III) sulfide (Fe2S3(sq)).

[0071] The active recovery capture mass according to the present invention and the starting capture mass for the preparation of said active recovery capture mass can be a "bulk" solid, a supported solid or a combination thereof. A "bulk" solid is understood to mean a solid prepared by molding one or more precursors (e.g. copper or iron precursors) with one or more binders. A supported solid is understood to mean a solid prepared by deposition of an active phase (e.g. based on copper or other active metals) on a porous support. This porous support can be any type of porous support based on a refractory oxide, such as silica, alumina, silica-alumina, activated carbon or a combination thereof.

[0072] According to one or more embodiments, the activity-restorable capture mass according to the present invention, and also the starting capture mass for the preparation of said activity-restorable capture mass, is provided in the form of beads or extrudates of the type of cylinder, multi-lobe, wheel or hollow cylinder or any other geometric shape used by those skilled in the art.

[0073] According to one or more embodiments, the active regenerable capture mass according to the invention, and also the starting capture mass for the preparation of said active regenerable capture mass, comprises at least one metal M, which is at least partially M x S y Present in the form of a sulfide, said metal M is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt, preferably copper, iron, nickel and cobalt. Highly preferably, the metal M is copper.

[0074] According to one or more embodiments, the pore volume of the activity-recoverable capture mass according to the present invention, and also of the starting capture mass for the preparation of said activity-recoverable capture mass, is at least 0.1 mL / g.

[0075] According to one or more embodiments, the specific surface area of ​​the active recoverable capture mass according to the invention, and also of the starting capture mass for the preparation of said active recoverable capture mass, is at least 10 m 2 / g.

[0076] The starting capture mass can be prepared by any means known to one of skill in the art. For example, according to one or more embodiments, the starting capture mass is prepared by the following steps: - impregnating the support (e.g. under dry conditions) with a metal M precursor (e.g. in solution); - allowing the product obtained in the preceding step to age (for example for 30 minutes to 12 hours, for example at ambient temperature), - drying the material obtained in the previous step (for example for 30 minutes to 12 hours at a temperature of, for example, 60 to 150°C), - calcining the material obtained in the previous step (for example for a period of 15 minutes to 6 hours, at a temperature of, for example, 200°C to 600°C); - sulfurizing the product obtained in the preceding step (for example at atmospheric pressure, at a temperature of, for example, 150°C to 350°C, for example under a gas stream containing a sulfur precursor, for example 1 to 10 mol% H2S, for example under nitrogen).

[0077] The preparation of the activity-restorable capture mass can be carried out by a step of capturing heavy metals in a gaseous or liquid feedstock, which step comprises contacting the feedstock to be treated with the starting capture mass, which can preferably be carried out by injecting the feedstock to be treated into a reactor containing the activity-restorable capture mass in the form of a fixed bed.

[0078] The gaseous or liquid effluent to be treated may contain heavy metals, such as mercury, arsenic or lead, in various forms. For example, mercury may be present in the form of "Hg°" corresponding to elemental or atomic mercury, in molecular form and / or in ionic form, e.g. Hg 2+ and their complexes. The concentration of heavy metals in the gaseous or liquid effluent to be treated can be variable. The gaseous effluent to be treated is preferentially concentrated in the gas volume (Sm 3 ), the liquid effluent to be treated is preferentially treated in the 3 ) by weight. In addition, the gaseous or liquid effluents being treated may contain arsenic and / or lead in various forms. The lead content of the effluent is expressed as 1 ppt (parts per million, or 10 -12 ) to 100 ppm by weight (parts per million, i.e. 10 -6 ), and the arsenic content can be 100 parts per billion (ppt) to 100 ppb (ppb) by weight. -9). As these heavy metals are harmful for reasons of safety and for reasons of the effectiveness of the treatment of these effluents, they can advantageously be removed or at least their content can be reduced. Finally, the effluents to be treated can contain other elements in various forms, such as sulfur and nitrogen. In particular, sulfur can be present in the form of organic sulfur, for example in the form of thiols or also in the form of thiophenes. The sulfur content of the effluents can be between 1 ppt and 1000 ppm by weight, and the nitrogen content can be between 1 ppt and 100 ppm by weight. Advantageously, neither the nitrogen nor the sulfur that may be present in the effluents to be treated cause any loss in the performance of the method according to the invention.

[0079] The contact of the feedstock to be treated with the starting capture mass can be carried out at a temperature between −50° C. and 150° C., preferentially between 0° C. and 110° C., very preferentially between 20° C. and 100° C. Furthermore, the contact of the feedstock to be treated with the capture mass can be carried out at an absolute pressure between 0.01 MPa and 20 MPa, preferentially between 0.1 MPa and 15 MPa, very preferentially between 0.1 MPa and 12 MPa.

[0080] The step of contacting the feedstock to be treated with the starting capture mass lasts for 0.1 h. -1 ~50h -1 , preferably 0.5h -1 ~20h -1 , with priority given to 1h -1 ~11h -1 The process can be carried out at a liquid hourly space velocity (LHSV) of 10 ...

[0081] The step of contacting the feedstock to be treated with the starting capture mass lasts for 10 h. -1 ~5000h -1 , preferably 50h -1 ~2000h -1, with priority given to 100h -1 ~1100h -1 The gas hourly space velocity (GHSV) can be 1000 sq. m. The term "GHSV" is understood to mean the gas hourly space velocity of the feed relative to the volume of the capture mass, i.e., the volume of the gaseous feed divided by the reactor volume per hour. The reactor volume includes the volume of the capture mass and the "empty" volume between the particles.

[0082] According to a second aspect, it also relates to a (activity-recovered) capture mass for heavy metals present in a gaseous or liquid hydrocarbon feedstock, which is obtainable by the method for activity recovery of a capture mass for heavy metals according to the first aspect.

[0083] The active recovered capture mass according to the present invention comprises at least one heavy metal (e.g., mercury) and at least one metal M, the metal M being at least partially M x S y Present in the form of a sulfide, said metal M is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt, preferably copper, iron, nickel and cobalt. Highly preferably, the metal M is copper.

[0084] According to one or more embodiments, the heavy metal (e.g., mercury) content of the active recovered capture mass is between 0.1% and 45% by weight, preferably between 0.5% and 30% by weight, and even more preferably between 1.0% and 20% by weight, for example between 5% and 15% by weight, based on the total weight of the active recovered capture mass.

[0085] The activity restored capture mass according to the present invention preferentially has at least 50% (mol / mol), preferably at least 70% (mol / mol), for example at least 90% (mol / mol) M x S y Metal M sulfurized in the form of, highly preferably, at least 95% (mol / mol) of M x S y The metal M is sulfurized in the form of the active phase, M x S yThe proportion of metal contained in the form of sulfides is preferably determined such that x≦2, more preferably x≦1, and most preferably x=1±0.2 or ±0.1. x S y The proportion of sulfur contained in the form of sulfide is preferably determined such that y≦2. When the metal is copper, M x S y The proportion of sulfur contained in the form of sulfides is preferably ascertained such that y≦2, more preferably y≦1, and highly preferably y=1±0.2 or ±0.1. More advantageously, when the metal is copper, the capture mass according to the invention is such that the proportion of copper and the proportion of sulfur, in the form of sulfides, obey the identities x=1±0.1 and y=1±0.1.

[0086] The presence of sulfurized metal M (e.g., CuS) and heavy metal sulfides (e.g., HgS) is readily demonstrated by X-ray diffraction. According to one or more embodiments, the X-ray diffractogram of the active recovered capture mass according to the invention exhibits at least diffraction lines characteristic of heavy metal sulfides, e.g., HgS, in the form of cinnabar or black cinnabar, preferably in the form of cinnabar, and / or diffraction lines characteristic of sulfurized metal M, e.g., covellite-type CuS.

[0087] According to one or more embodiments, the active recovered capture mass is provided in the form of beads, or extrudates of the type cylinder, multi-lobe, wheel or hollow cylinder, or any other geometric shape used by those skilled in the art.

[0088] According to one or more embodiments, the pore volume of the active recovered capture mass is at least 0.1 mL / g.

[0089] According to one or more embodiments, the active recovered capture mass has a specific surface area of ​​at least 10 m 2 / g.

[0090] According to a third aspect, the present invention also relates to a method for the use of a capture mass according to the second aspect in the removal of heavy metals, in particular mercury, from a gaseous or liquid hydrocarbon feedstock.

[0091] The active recovered capture mass makes it possible to treat both liquid and gaseous effluents. Moreover, the effluent can be a gas containing moist gas or vapours of coagulable compounds, without this significantly shortening the life of the capture mass. The relative humidity of the gaseous effluent, defined as the ratio of the partial pressure of water to the saturated water vapour pressure at a given temperature, can be between 0% and 100%, preferentially between 1% and 95%, more preferentially between 2% and 90%.

[0092] The use of the active recovered capture mass is particularly suitable for the treatment of liquid or gaseous effluents of petroleum origin and their derivatives. Such effluents generally contain heavy metals. The gaseous or liquid effluents to be treated in the process according to the invention can advantageously be selected from the group consisting of flue gas, biogas, synthesis gas, natural gas, natural gas condensate, oil, liquid or gaseous petroleum fractions, petrochemical intermediates and mixtures thereof. Preferably, the gaseous or liquid effluents to be treated in the process according to the invention are advantageously selected from the group consisting of flue gas, synthesis gas, natural gas, natural gas condensate, crude oil and liquid hydrocarbon fractions from refineries or petrochemical plants.

[0093] According to one or more embodiments, the flue gas is produced by the combustion of hydrocarbons, biogas and coal in a boiler or by a combustion gas turbine, e.g., for the purpose of generating electricity. According to one or more embodiments, the temperature of the flue gas is typically between 20°C and 60°C, and the pressure is typically between 0.1 MPa (1 bar) and 0.5 MPa (5 bar). According to one or more embodiments, the flue gas contains, by volume, 50% to 80% nitrogen, 5% to 40% carbon dioxide, 1% to 20% oxygen, as well as potential impurities such as SO x and NO xwould contain such impurities if they had not been removed upstream by deoxidation processes.

[0094] According to one or more embodiments, biogas is a gas produced by methanation or otherwise fermentation of animal or plant organic matter in anoxic conditions. It can be produced naturally, for example in landfills containing organic waste, or artificially in methanizers or digesters fed with animal manure, organic or agricultural waste, or sludge from water treatment plants. Biogas consists mainly (i.e., at least 50% by weight) of methane and CO2, the proportions of which vary depending on the origin of the starting material used.

[0095] According to one or more embodiments, the synthesis gas is a gas containing carbon monoxide CO, hydrogen H2, water vapor (typically saturated) and carbon dioxide CO2. According to one or more embodiments, the H2 / CO molar ratio of the synthesis gas is substantially equal to 2. According to one or more embodiments, the carbon dioxide CO2 content is approximately 10% by volume of the synthesis gas. The pressure of synthesis gas most frequently encountered in industry is typically between 2 MPa (20 bar) and 3 MPa (30 bar), but it can reach 7 MPa (70 bar). The synthesis gas may further contain sulfur-containing impurities (H2S, COS, etc.), nitrogen-containing impurities (NH3, HCN, etc.) and halogenated impurities.

[0096] According to one or more embodiments, natural gas consists mainly of gaseous hydrocarbons. According to one or more embodiments, natural gas contains at least one of the following acidic compounds: carbon dioxide CO2, hydrogen sulfide H2S, thiols, carbonyl sulfide COS and carbon disulfide CS2. The content of natural gas in these acidic compounds is highly variable and can range up to 40% by volume for CO2 and H2S. The temperature of natural gas most frequently encountered in industry can be between 20°C and 100°C, and its pressure can be between 1 MPa (10 bar) and 20 MPa (200 bar).

[0097] According to one or more embodiments, natural gas condensate consists of liquid hydrocarbons, the production of which is associated with the production of natural gas. These complex liquid mixtures are very similar to crude oil.

[0098] According to one or more embodiments, liquid hydrocarbons from the refinery include LPG (C3-C4 fraction), naphtha (C5-C8 fraction), kerosene and diesel.

[0099] According to one or more embodiments, liquid hydrocarbons from petrochemical plants include LPG (C3-C4 fraction) and cracked gasoline (or "pyrolysis gasoline", also known as "PyGas").

[0100] According to one or more embodiments, the contacting of the gaseous or liquid effluent to be treated with the capture mass in the method according to the invention can be carried out at a temperature between −50° C. and 150° C., preferentially between 0° C. and 110° C., more preferentially between 20° C. and 100° C. According to one or more embodiments, the contacting of the gaseous or liquid effluent to be treated with the capture mass in the method according to the invention can be carried out at an absolute pressure between 0.01 MPa (0.1 bar) and 20 MPa (200 bar), preferentially between 0.1 MPa (1 bar) and 15 MPa (150 bar), very preferentially between 0.1 MPa (1 bar) and 12 MPa (120 bar).

[0101] The step of contacting the feedstock to be treated with the active recovered capture mass lasts for 0.1 h. -1 ~50h -1 , preferably 0.5h -1 ~20h -1 , with priority given to 1h -1 ~11h -1 The process can be carried out at a liquid hourly space velocity (LHSV) of 10 ...

[0102] The step of contacting the feedstock to be treated with the activated recovered capture mass lasts for 10 h. -1 ~5000h -1 , preferably 50h -1 ~2000h -1 , with priority given to 100h -1 ~1100h -1 The gas hourly space velocity (GHSV) can be 1000 sq. m. The term "GHSV" is understood to mean the gas hourly space velocity of the feed relative to the volume of the capture mass, i.e., the volume of the gaseous feed divided by the reactor volume per hour. The reactor volume includes the volume of the capture mass and the "empty" volume between the particles.

[0103] Before contacting the liquid or gaseous effluent to be treated with the (starting or activity-recovered) capture mass, said gaseous or liquid effluent can be pretreated. This pretreatment can consist of heating or cooling, compression or expansion, and / or purification treatments that make it possible to remove the effluent or reduce its content of compounds considered undesirable. For example, pretreatment can include a step of reducing the relative humidity of the gaseous effluent. The reduction of the relative humidity of the gaseous effluent can be achieved by any means known to the person skilled in the art, in particular by using a water capture mass, for example a zeolite-based molecular sieve, for example the glycol process as described in document WO 2005 / 047438, a step of heating the effluent in a heat exchanger that makes it possible to increase the temperature of the effluent, for example from 3° C. to 10° C., or a step of cooling the effluent.

[0104] Contact with the (starting or activity-restored) capture mass advantageously makes it possible to capture the heavy metals contained in the effluent to be treated, as well as to obtain an effluent with a reduced content of heavy metals compared to that in the starting effluent, and even to completely remove the heavy metals from the effluent.

[0105] (Example) A capture mass for heavy metals M1 is prepared. This is carried out by impregnation of support S1, essentially based on alumina, with a Cu(NO3)2·3H2O solution followed by sulfurization. The pore volume of support S1, measured by mercury porosimetry (see Rouquerol F., Rouquerol J. and Sing K., "Adsorption by Powders and Porous Solids: Principles, Methodology and Applications", Academic Press, 1999), is 0.98 mL / g. The protocol to be followed is the following: - preparing the impregnation solution; this is carried out by dissolving Cu(NO3)2·3H2O in a volume of water that allows obtaining the volume necessary to fill the entire pore volume of the alumina support (concentration of the solution: 2.04×10 -6 mol / Cu 2+ L); - impregnating the porous support with said solution prepared in the preceding step by slow spraying; - allowing the product obtained in the preceding step to age in a closed vessel at ambient temperature for 3 hours; - drying the material obtained in the preceding step at 90°C for 3 hours; - calcining the material obtained in the preceding step in a tubular furnace at 450°C in a moist atmosphere for 45 minutes; The product obtained in the preceding step is sulphurized at atmospheric pressure under a nitrogen stream containing 5% by mole of H2S diluted in nitrogen at a temperature of 250°C.

[0106] The trap mass for the heavy metal M1 is saturated with mercury. The saturation is performed at 3500 μg / Sm in N2. 3 In the gas phase, at 50°C, 2MPa (20bar), 0.3Sm 3 / Under the flow of time, 1000h -1 This is done by contacting mercury with GHSV of 1000 to obtain an activity-recoverable capture mass M1_sat.

[0107] The active recoverable trap mass M1_sat was subjected to 1000h -1 GHSV of 0.3Sm 3 / hr flow of H2S diluted to a level of 2% by volume in nitrogen to obtain an active recovered capture mass M1_sat_sulf.

[0108] The thus obtained activity-restored captured mass M1_sat_sulf was again subjected to a gas phase (3500 μg / Sm in N2 3 ) at 50°C, 2MPa (20bar), 0.3Sm 3 / Under the flow of time, GHSV is 1000h -1 , and is saturated by trapping mercury to obtain a spent, active, rejuvenated trap mass M1_sat_sulf_sat.

[0109] The copper and mercury contents of all the masses are determined by X-ray fluorescence on an Axios mAX instrument from PANanalytical. The measurements of the sulfur content were carried out with a CHNS / O Flash 2000 analyzer from ThermoFisherScientific. In order to be able to be compared with each other, the sulfur contents were all returned to the starting weight before the first saturation with mercury. For this, the following formula is applied: %X_starting weight=%X_final weight / (100-%Hg_final weight)×100. As Hg is captured according to the reaction Hg+2CuS=HgS+Cu2S, it is possible to calculate the amount that is theoretically possible to capture: %Hg_theo=%S_starting weight / (2×M S )×M Hg ;In the formula, M S is the molar mass of sulfur, M Hg is the molar mass of mercury. The "demercuration" rate (DeHgR) is obtained by taking the ratio of the amount of Hg trapped (%Hg_starting weight) to the amount that can theoretically be trapped (%Hg_theo) and multiplying this ratio by 100: DeHgR = %Hg_starting weight / %Hg_theo x 100. The values ​​obtained are given in Table 1 (values ​​are expressed as weight % of the element).

[0110] [Table 1]

[0111] The mass M1_sat_sulf contains more sulfur than the mass M1. The sulfurization treatment thus allows the mass to be partially resulfurized, which thus allows the recovery of the capture capacity. Furthermore, the mass M1_sat_sulf_sat contains more Hg than the mass M1_sat. If reference is made to the theoretical maximum capacity of the initial mass M1 of 15.7% by weight Hg, the fact of reaching 17.4% by weight Hg corresponds to reaching a demercuration rate of 111%, i.e. a demercuration rate of more than 100%. The copper content does not change. Likewise, the amount of Hg does not change due to the sulfurization of the mass M1_sat (same Hg content for M1_sat and M1_sat_sulf). The sulfurization does not lead to the desorption of mercury.

[0112] All the masses obtained were also characterized by X-ray diffraction. The diagrams obtained (not shown) show that initially the trapped masses show lines characteristic of CuS. After trapping of Hg, these lines disappear and the lines of HgS appear. Then, after resulfurization, the lines of CuS appear again and the lines of HgS are still present. This shows that sulfurization makes it possible to regenerate CuS without losing HgS.

Claims

1. A method for restoring the activity of a heavy metal capture mass containing heavy metals, the method comprising contacting the capture mass with a sulfiding stream.

2. 2. The method for restoring activity according to claim 1, wherein the heavy metal is selected from the group consisting of mercury, arsenic and lead.

3. 2. The method for restoring activity according to claim 1, wherein the heavy metal is mercury.

4. 2. The activity recovery method of claim 1, wherein the sulfide stream is selected from the group consisting of hydrogen sulfide, dimethyl sulfide, dimethyl disulfide, and methanethiol.

5. The sulfide flow was －１ ~50h －１ Liquid hourly space velocity LHSV or 10h －１ ~5000h －１ 2. The method for recovering activity according to claim 1, wherein the gas is fed at a gas hourly space velocity GHSV of 1000 MPa or more.

6. 2. The method for regenerating activity according to claim 1, wherein the sulfiding stream is delivered at a pressure of 0.1 MPa to 15 MPa and / or a temperature of 0°C to 600°C.

7. 2. The method of claim 1, wherein the heavy metal-containing capture mass is a bulk solid or a supported solid comprising a porous support based on a refractory oxide.

8. 10. The method for restoring activity according to claim 1, wherein the heavy metal-containing capture mass exhibits at least one of the following characteristics: - the pore volume is at least 0.1 mL / g; - specific surface area of ​​at least 10 m ２ / g, - the form is in the form of beads or extrudates of the cylindrical, multilobal, wheel or hollow cylinder type; - at least one metal M is present, said metal M being at least partly M ｘ S ｙ The metal M is present in the form of a sulfide and is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt.

9. 2. The method for restoring activity according to claim 1, wherein the heavy metal content of the heavy metal-containing trapping mass is 0.1% by weight to 50% by weight based on the total weight of the heavy metal-containing trapping mass.

10. An active restored capture mass having a heavy metal content of 0.1% to 45% by weight based on the total weight of the active restored capture mass.

11. 11. The active recovered capture mass of claim 10 provided in the form of a bulk solid or a supported solid comprising a porous support based on a refractory oxide.

12. 11. The active recovered capture mass of claim 10, exhibiting at least one of the following characteristics: - the pore volume is at least 0.1 mL / g; - specific surface area of ​​at least 10 m ２ / g, - the form is in the form of beads or extrudates of the cylindrical, multilobal, wheel or hollow cylinder type; - at least one metal M is present, said metal M being at least partly M ｘ S ｙ The metal M is present in the form of a sulfide and is selected from the group consisting of copper, molybdenum, tungsten, iron, nickel and cobalt.

13. 11. The active recovered capture mass of claim 10, wherein the heavy metal is selected from the group consisting of mercury, arsenic, and lead.

14. 11. The active recovered capture mass of claim 10, wherein the heavy metal is mercury.

15. 15. A method for the capture of heavy metals in a gaseous or liquid feedstock, comprising contacting the feedstock with a capture mass selected from the active recovered capture mass obtainable by the method of any one of claims 1 to 9 and the active recovered capture mass of any one of claims 10 to 14.