Method for preparing catalyst-adsorbent

Abstract

FIELD: oil refining; oil field chemistry.SUBSTANCE: invention relates to methods for preparing desulfurization catalysts and adsorbents for hydrogen sulphide and sulphur-comprising compounds comprised in hydrocarbon media. A method is proposed for preparing a catalyst-adsorbent for desulfurization of natural gas, which includes the stages of preliminary dry mixing of powders that are sources of zinc oxide and aluminium oxide, and a powder comprising Co and Mo compounds, with the addition of a plasticizing agent as a peptizer, stirring until a paste is obtained, followed by granulation, drying and calcination of the granules. Sources of zinc oxide, aluminium oxide, Co and Mo compounds are taken in quantities that ensure the production of a catalyst-adsorbent, which comprises, in terms of oxides, wt.%: ZnO not less than 50, Al2O3 not more than 45, total Co and Mo compounds in the range of 0.5-10, so the molar ratio of Co:Mo is 0.1-1.EFFECT: obtaining a catalyst-adsorbent for desulfurization of natural gas, increasing its catalytic activity and forming a layered spatial structure of the catalyst-adsorbent.8 cl, 1 dwg, 1 tbl, 10 ex

Description

[0001] The invention relates to the field of oilfield chemistry, oil and gas refining, in particular to methods for preparing catalysts-adsorbents of hydrogen sulfide and sulfur-containing compounds in hydrocarbon gas environments, and can also be used in the oil producing industry.

[0002] Natural gas (NG) is a mixture of a wide range of hydrocarbons, nitrogen, carbon dioxide, hydrogen, rare gases, and many other impurities. It is a feedstock for processes aimed at producing petrochemical products or fuels. Efficient use of NG requires pre-treatment to reduce the amount of sulfur-containing compounds (hydrogen sulfide, mercaptans, sulfides), the presence of which leads to the deactivation of noble metal-based post-process catalysts. For example, to effectively process NG in the Fischer-Tropsch process, it is necessary to reduce the sulfur content to less than 5 ppb.

[0003] Technology Level

[0004] Solid adsorbents containing oxides of various metals are used for desulfurization of natural gas. A known sorbent for purification of petroleum gases from hydrogen sulfide is [RU 2541081 C1, B01J 20 / 06, 10.02.2015], containing iron and manganese oxides obtained from waste from water treatment plants during water purification from iron, and burnt rocks of the coal basin, wt.%: SiO2 - 68.7; Al2O3 - 21.5; Fe2O3 - 4.7; MgO, MnO - the rest. Iron and manganese oxohydroxides, deposited on the burner at water treatment plants during iron removal, are used as a sorbent for hydrogen sulfide removal from gas. These oxohydroxides are dispersed on the burner surface and dried at a temperature of 25-100°C. Sorbent sulfur capacity tests are carried out at room temperature in the range from 18 to 24°C and with an adsorbent sample volume of 30.0 cm 3 The sorption capacity ranges from 213 to 245 mg S / g of adsorbent.

[0005] It is known that zinc oxide-based adsorbents are the most promising for hydrogen sulfide adsorption due to the high equilibrium constant of the hydrogen sulfide absorption reaction (ZnO+H2S→ZnS+H2O) and the high thermal stability of the adsorbents and their sulfides [Garces, HF, Galindo, HM, Garces, LJ, Hunt, J., Morey, A., Suib, SL Low temperature H2S dry-desulfurization with zinc oxide. Microporous and Mesoporous Materials. 2010. 127(3). P. 190-197. DOI:10.1016 / j.micromeso.2009.07.022.; Samokhvalov, A., Tatarchuk, B.J. Characterization of active sites, determination of mechanisms of H2S, COS and CS2sorption and regeneration of ZnO low-temperature sorbents: Past, current and prospects. Physical Chemistry Chemical Physics. 2011. 13(8). P. 3197-3209. DOI:10.1039 / c0cp01227k]. It is also known that aluminum oxide is added to the zinc-containing adsorbent to increase the mechanical strength of granules and improve textural characteristics [Denisova KO et al.Properties of zinc oxide adsorbent for adsorbing hydrogen sulfide / / Russian Journal of Applied Chemistry. - 2022. - Vol. 95. - No. 1. - Pp. 113-117.]. In addition to aluminum oxide, various promoters can be added to the absorber composition. Thus, in industry they use absorbers based on zinc oxide with the addition of copper oxide, for example, the company OOO NIAP-katalizator (Russia, Novomoskovsk https: / / niap-kt.ru / produktsiya / po-khimicheskomu-protsessu / katalizatory-seroochistki / ), or closely related compounds, for example, AO EKAT (Russia, Perm https: / / ekokataliz.ru / equipment / sorbenty / ), Haldor Topsoe (Sweden https: / / www.topsoe.com / solutions / catalysts / htz-31).

[0006] One of the methods for NG purification is a combined adsorption-catalytic method [Lazarev V.I. Methods of natural gas purification from hydrogen sulfide using solid sorbents / / Review of information. Scientific and technical aspects of environmental protection / VINITI. 1999. No. 4. pp. 84-113]. The known method is implemented using separate purification units at a temperature of 350-400°C and a pressure of 35-40 atm, into which two systems are sequentially loaded: a catalyst for hydrodesulfurization (hydrogenolysis) of organosulfur compounds and a separate adsorbent.

[0007] At the first stage, when passing through a block containing a catalyst, hydrodesulfurization (hydrogenolysis) of organosulfur compounds occurs with the participation of hydrogen with the formation of hydrogen sulfide and the corresponding hydrocarbon, which enter the next block:

[0008] • Mercaptans

[0009]

[0010] • Sulfides

[0011]

[0012] • Disulfides

[0013]

[0014] The hydrogen sulfide released as a result of hydrodesulfurization reactions and present in the natural gas is absorbed in the following blocks by an adsorbent, resulting in desulfurized natural gas at the outlet (second stage):

[0015]

[0016] A method for implementing the adsorption-catalytic method is known, when the hydrogenation catalyst and the adsorbent are loaded layer by layer into one apparatus.

[0017] Previously used catalysts-chemisorbents zinc-chromium-copper KS-4 and zinc-aluminum GIAP-943N without promoters or with small additives of nickel and molybdenum are known [Afanasyev et al. J. Neftegaz. 2018. No. 10. pp. 88-95]. NIAP-Katalizator LLC offers a bifunctional catalyst for the hydrogenation of organosulfur compounds and the absorption of hydrogen sulfide NIAP-02-11 [Afanasyev et al. J. Neftegaz. 2024. No. 5. pp. 15-20] in the form of cylindrical extrudates, the composition of which is not specified. Information related to the synthesis method and study of such combined systems is usually the "know-how" of the manufacturing companies.

[0018] A known method for preparing a granular adsorbent [RU 2709689 C1 B01J 20 / 04, 19.12.2019] for purifying gas and liquid, the composition of which includes 40-90 wt.% finely dispersed zinc oxide, 10-55 wt.% finely dispersed aluminum oxide monohydrate of the pseudoboehmite modification and 0-5 wt.% modified starch. The adsorbent is prepared by obtaining a mixture of the specified powders, forming granules by extrusion, drying and calcining the granular adsorbent at temperatures of 400-500 °C. It should be noted that the known adsorbent has been studied in the removal of chlorine-containing components in the composition of gaseous hydrocarbon feedstock, while the parameters of the purification process are not specified.

[0019] The most common method for synthesizing hydrogen sulfide adsorbents involves preliminary dry mixing of powders containing at least one metal oxide powder and at least one binder, stirring the resulting paste with the addition of a peptizing agent, granulating the paste, drying and calcining the granules in a stream of gas containing oxygen.

[0020] The patent [RU 2311226 C2, B01J 20 / 06, 21.11.2007] proposes sorbents for purifying gases from sulfur compounds, containing zinc oxide (or its source) in an amount of 85-97 wt.% and aluminum oxide (or its source) in an amount of 0.2-6.2 wt.% as the main components, and may also contain copper oxide, graphite, kaolin. The method for producing the known sorbent includes forming active zinc oxide with a filler or binder or high-molecular colloid, wherein before forming, zinc oxide absorber, spent in the sulfur removal process, with a particle size of no more than 0.1 mm, containing no more than 8 wt.% sulfur, or a mixture thereof with promoting additives, is added to the active zinc oxide raw material.

[0021] A method for preparing a solid granular sorbent based on zinc and aluminum oxides is described in [RU 2526987 C2, B01D 53 / 00, 27.08.2014]. The method includes pre-mixing powders containing at least one ZnO powder and at least one binder, bringing said mixture into contact with a solution containing a peptizing agent, which results in the formation of a paste, stirring the paste, granulating the paste, drying the granules, and calcining the dried granules. In this case, the binder is aluminum oxide or boehmite. The known method makes it possible to obtain solid ZnO-based materials that can be used for desulfurization and / or removal of halogenated compounds from gaseous and liquid feedstocks. It is indicated that solid materials obtained according to the said method have increased mechanical strength characteristics, even in the case of solid materials in which the ZnO content is higher than 85 wt.%.

[0022] The authors of the patent [RU 2857589 C2, B01J 29 / 14, B01J 29 / 76, B01J 23 / 06, B01J 21 / 04, B01J 21 / 06, B01J 37 / 02, B01J 37 / 04, C10G 45 / 12, C10G 45 / 06, 20,10.2022] proposed a catalyst for modifying oil, containing, by weight: 65-85 carrier, 8-15 primary active component, 2-5 secondary active component and 5-15 binder, based on the total amount of catalyst; wherein the carrier contains 65-85 zinc oxide, 8-22 aluminum oxide, 0-5 titanium oxide, 0-5 zirconium dioxide and 4-10 modified molecular sieve, based on the total amount of the carrier.A method for producing a catalyst for modifying oil comprises: introducing a modifying element (lanthanum and / or palladium) into a molecular sieve to produce a powder of a modified molecular sieve (USY and / or Beta); resonantly mixing a support precursor (zinc oxide powder, pseudoboehmite, possibly powders of titanium oxide, zirconium dioxide and a modified molecular sieve) and a pore-forming agent to produce mixture I; adding a precursor of a primary active component (a soluble compound containing nickel and / or copper) to mixture I to produce mixture II; mixing the precursor of a binder and mixture II, and then performing granulation molding and a first calcination to produce solid particles; impregnating the solid particles with a precursor of a secondary active component (one or more selected from soluble compounds of potassium, cobalt, molybdenum and iron) and performing a second calcination to produce a catalyst for modifying oil.It is also indicated that soluble cobalt and molybdenum compounds added at the last stage are used as promoters in the composition of the oil modification catalyst.

[0023] All ZnO-based materials obtained in the listed patents are sorbents of sulfur-containing components present in the composition of gaseous or liquid hydrocarbon feedstock.

[0024] Catalytic methods for hydrodesulfurization of hydrocarbon feedstock are separately known from the prior art. Metal sulfides are used as a component active in the reactions of hydrogenolysis of organosulfur compounds (mercaptans, mono- and disulfide derivatives of hydrocarbons, etc.) into hydrogen sulfide and hydrocarbons, with a combination of metals, for example, CoMo, NiMo, NiW, leading to the formation of the most active phase. It has been established that the catalyst component active in the reaction of hydrogenolysis of organosulfur compounds has the composition CoMoS, NiMoS, or NiWS, respectively. For hydrodesulfurization processes carried out at low pressures, it is preferable to use the CoMo component. To obtain the active components of Co and Mo sulfides, a preliminary synthesis of Co and Mo compounds is carried out to obtain cobalt and molybdenum oxides, as well as the CoMoO4 phase, which are then activated in a sulfurizing agent medium - hydrogen sulfide or dimethyl disulfide.

[0025] For the preparation of hydrodesulfurization catalysts, a method of impregnation of a carrier, usually based on aluminum oxide, with solutions of compounds of the indicated transition metals is often used.

[0026] The patent [RU 2626398 C1 IPC B01J 23 / 00, B01J 23 / 882 B01J 32 / 00, B01J 21 / 02, B01J 21 / 04, C10G 45 / 08, 27.07.2017] describes the preparation of a catalyst for the production of petroleum distillates with a low sulfur content by impregnating an aluminum oxide-based carrier. The impregnation solution is obtained by dissolving ammonium paramolybdate (NH4)6Mo7O in water. 24 ⋅4H2O, cobalt (II) basic carbonate CoCO3⋅mCo(OH)2⋅nH2O, citric acid monohydrate, so that the finished catalyst contains the bimetallic complex [Co(H2O)2(C6H5O7)]2[Mo4O 11(C6H5O7)2] in the range of 33-43 wt.%, while the carrier necessarily contains aluminum borate Al3BO6 with a norbergite structure of 5-25 wt.%, which provides the required level of acidity of the carrier. A similar method of preparation is described in the patent [RU 2313392 C1 B01J 37 / 02, B01J 21 / 02, B01J 21 / 04, B01J 23 / 88, B01J 23 / 882, B01J 31 / 04, C10G 45 / 08, 27.12.2007] with the difference that at the stage of solution preparation in addition to citric acid, ammonium paramolybdate, and a cobalt compound, a boron compound is added.

[0027] An alternative to sequential loading of two systems (hydrogenolysis catalyst and adsorbent) is the use of a bifunctional catalyst-adsorbent. The catalyst-adsorbent is a granular multicomponent system that includes a hydrodesulfurization component, which provides activity in the hydrogenolysis reaction of organosulfur compounds to form hydrogen sulfide and hydrocarbons, an adsorbent, which absorbs hydrogen sulfide, and a binder, which imparts texture and strength to the composition.

[0028] To effectively carry out the hydrodesulfurization process of NG containing both hydrogen sulfide and organosulfur compounds, it is desirable that the hydrogenating (Ni, Mo, CoMo, NiMo, NiW, etc.) and adsorbing (e.g. ZnO) active components are located close to each other in space, thereby ensuring efficient transfer of sulfur from the hydrogenation center to the adsorption center.

[0029] A granulated catalyst-adsorbent is known for purifying liquid hydrocarbons - catalytic cracking gasoline and diesel fuel, the composition of which includes, by weight: 10-90 finely dispersed zinc oxide, 5-85 silicon dioxide, 5-30 finely dispersed aluminum oxide monohydrate of pseudoboehmite modification and nickel in an amount of 5-50 by weight [CA 2370627C, C10G25 / 003, B01J20 / 0225, B01J20 / 0244, B01J20 / 06, B01J20 / 08, B01J20 / 103, B01J20 / 30, B01J20 / 3078, B01J20 / 3204, B01J20 / 3236, [B01J2220 / 42, C10G2400 / 02, C10G2400 / 04, 01.03.2001]. The catalyst-adsorbent is prepared by mixing zinc oxide, silicon dioxide, and aluminum oxide to form a mixture; granulating the mixture, drying and calcining the particles (granules), and then impregnating the calcined granulated sorbent carrier with a solution containing nickel or a nickel compound. After impregnation, the granules are again dried and calcined, and then the calcined extrudates are reduced using hydrogen.Nickel compounds are added to provide desulfurization of liquid streams without hydrogenation of aromatic compounds.

[0030] The disadvantages of the known method include the double drying and calcination steps, as well as the impregnation and reduction stages, which require additional steps and costs: solution preparation, creation of a reducing environment, and high hydrogen consumption. Furthermore, the zinc-containing component is re-dissolved during the impregnation stage, leading to the destruction of the existing granules and a reduction in their mechanical strength. Another drawback is the inclusion of silicon oxide, which has poor plastic properties and is not a sorbent for sulfur-containing compounds, thus creating a non-working volume within the sorbent-catalyst. Furthermore, the presence of nickel compounds (active in the hydrogenolysis of organosulfur compounds) requires mandatory passivation of the finished catalytic composition.

[0031] It should be noted that the use of the method of impregnating a zinc oxide-based carrier with solutions of metal compounds commonly used for hydrodesulfurization is of little use, since ZnO granules are destroyed in an acidic environment.

[0032] Thus, there is a task of creating a method for preparing a bifunctional composition for removing sulfur-containing compounds from hydrocarbon gases, in which a close spatial arrangement of the hydrogenating and adsorbing components is achieved, which, as a result, could ensure the effective desulfurization of natural gas under significantly milder conditions (temperature up to 350°C, pressure no more than 30 atm) than the processes currently implemented industrially.

[0033] The proposed invention solves the problem of creating a method for preparing an effective catalyst-adsorbent for sulfur-containing compounds from natural gas.

[0034] Disclosure of the essence of the invention

[0035] The problem is solved by a preparation method that involves preliminary dry mixing of powders serving as sources of zinc oxide and aluminum oxide, and a powder containing cobalt and molybdenum compounds. The mixture is then prepared into a paste by adding a plasticizing agent as a peptizer and mixing. The paste is then granulated, and the granules are dried and calcined. This method yields a bifunctional system comprising a CoMo component, which provides the hydrogenolysis function for organosulfur compounds, and ZnO, which acts as an adsorbent for hydrogen sulfide, which is naturally present in natural gas, and hydrogen sulfide released during the conversion (hydrogenolysis) of organosulfur compounds.

[0036] In the proposed technical solution, the CoMo component responsible for hydrogenating sulfur-containing compounds is introduced into the adsorbent during the dry mixing stage, as this preparation method ensures uniform distribution of the hydrogenating component throughout the granule and is technologically simple. After drying and calcination, all compounds in the bifunctional system are in oxide form. This method results in the creation of spatial structures in which the hydrogenating CoMo component (primarily in the form of the CoMoO4 phase) is dispersedly localized on the binder particles (aluminum oxide), which, in turn, directly interacts with the zinc oxide particles, thereby creating a partial or complete coating of these particles.

[0037] Thus, the proposed preparation method results in the formation of a bifunctional catalyst-adsorbent, which combines zinc oxide, which provides a high sorption capacity for sulfur and, accordingly, a long service life, a CoMo component, which has high activity in the hydrogenolysis reaction of the CS bond, and a binding component, which ensures a close spatial arrangement of the hydrogenating and adsorbing components.

[0038] In this case, the hydrogen sulfide present in the PG, when in contact with the CoMo component in the bifunctional catalyst-adsorbent, will sulfidize the CoMoO4 phase, thereby forming the CoMoS phase, which is active in the conversion of organosulfur compounds.

[0039] The result of the preparation method is the formation of a catalyst-adsorbent, in which the components, taken in a specific quantity, are interconnected and arranged in such a way that they operate effectively under a single temperature regime in a single reaction space. Moreover, the operating temperature of this system is lower (approximately 50-100°C) than with sequential loading of the individual system components. Using the bifunctional system obtained by the proposed method at currently available process capacities in the case of two reactors connected in series will allow for an increase in the sorption volume if the hydrotreating (hydrodesulfurization) catalyst in the first reactor is replaced with a bifunctional catalyst-adsorbent, which will increase the proportion of zinc oxide in both reactor units.

[0040] The absence of nickel as a hydrogenating component allows to avoid an additional passivation stage and provides storage conditions for the catalyst-adsorbent suitable for industrial use.

[0041] The positive effect is achieved due to the close arrangement of the hydrogenating and sorbing components in the proposed bifunctional system. The method for preparing a catalyst-adsorbent, which includes zinc oxide, aluminum oxide, cobalt and molybdenum compounds, the amount of which, calculated as metal oxides, is, by weight: ZnO - not less than 50%, Co and Mo compounds in total - 0.5-10, Al2O3 - no more than 45, allows for the achievement of specific textural and structural characteristics. A distinctive feature of the resulting structures is the spatial arrangement of the active components of the sorption-catalytic system: zinc oxide particles are partially or completely coated with aluminum oxide, on which the CoMo component is located, which leads to an increase in sorption capacity and activity in the reaction of hydrogenolysis of organosulfur compounds compared to known systems.In this case, aluminum oxide in the finished catalyst-adsorbent is a binding component in the composition of the granules and additionally functions as a carrier for the hydrogenating CoMo component.

[0042] A zinc-containing precursor powder serves as a source of zinc oxide in the finished catalyst adsorbent. This powder is produced using methods such as sol-gel, hydrothermal synthesis, or precipitation, but is not limited to these methods. Commercial zinc oxide powder is also used. In embodiments, the zinc-containing precursor powder is obtained using the precipitation method. After drying and calcining the formed granules, zinc oxide is formed from this precursor powder.

[0043] The CoMo component refers to cobalt and molybdenum compounds that, upon calcination, transform into oxide compounds, preferably yielding the CoMoO4 phase, which is a precursor to the active CoMoS phase. CoMo powder can be produced by calcining a mixture of individual Co and Mo compounds (e.g., hydrated salts, hydroxides, complex oxides, and paramolybdic acid salts) or by spray drying a bimetallic CoMo complex, such as Co and Mo chelates, but is not limited to the methods listed above. Citric acid, nitrilotriacetic acid, EDTA, etc. can be used as chelating agents. In examples of the method, the CoMo component is obtained by spray drying a homogeneous solution of chelated cobalt and molybdenum compounds, which is prepared by dissolving ammonium paramolybdate, cobalt hydroxide and citric acid in water, followed by heat treatment.

[0044] The composition of the CoMo component significantly affects the activity in the hydrogenation reaction of sulfur-containing compounds and the sulfur sorption capacity. Therefore, with a total amount of Co and Mo compounds calculated as oxides of 0.5-10 wt.%, the Co:Mo molar ratio is a significant feature and varies in the range of 0.1-1. Deviating from this ratio does not lead to an increase in catalyst activity.

[0045] The aluminum-containing precursor powder is a source of aluminum oxide. This powder may be aluminum hydroxide obtained using methods such as sol-gel, precipitation, or hydrothermal synthesis, but is not limited to these methods. The aluminum-containing powder may be a commercial source of aluminum oxide, such as pseudoboehmite or boehmite, or commercial Al2O3 powder.

[0046] Adding aluminum-containing powders to zinc-containing powder and powder containing Co and Mo compounds produces a flexible molding paste and subsequently granules with optimal shape and strength. The aluminum-containing compound is a precursor to the aluminum oxide phase in the finished catalyst. Pseudoboehmite is used as the aluminum oxide source in the method implementation examples.

[0047] An aqueous solution of ammonia, a solution of nitric acid, water, etc. are usually used as a plasticizing agent for preparing a paste from dry powders. In examples of the method, an aqueous solution of ammonia is used.

[0048] For ease of industrial use, the catalyst-adsorbent must be granulated. Granulation is the process of converting a paste (obtained by mixing dry powders and a plasticizing agent until homogeneous) into granules of the required size, shape, and strength (grains, tablets, extrudates, etc.). Granulation can be accomplished by the following methods: tableting, rolling, extrusion, etc. Examples of this method use extrusion: the paste is forced through a round die opening to produce granules, for example, in the form of a cylinder with a diameter of 1.0-4.5 mm and a length of 3-5 mm.

[0049] For industrial use, it is advisable to dry the granules in a temperature range of 100-150°C. Calcination is typically carried out in a flow of oxygen-containing gas at temperatures of 400-550°C. In embodiments, drying and calcination are carried out at temperatures of (110±10) and (500±10)°C, respectively.

[0050] The preparation method results in the formation of a layered spatial structure in the catalyst-adsorbent, which ensures the close proximity of the CoMo component, binder, and zinc oxide. The zinc oxide particles are coated entirely or partially with aluminum oxide particles, and the cobalt and molybdenum compounds preferentially form the CoMoO4 phase located on the aluminum oxide. This leads to high dispersion of the CoMoO4 phase and, accordingly, its higher activity in the conversion reactions of organosulfur compounds, as well as to the close proximity of the CoMoO4 phase to ZnO, which facilitates the transfer of sulfur into the ZnO particles. When a sulfur-containing mixture is fed, the CoMoO4 phase is sulfided to form the CoMoS phase, which is highly active in the hydrogenolysis reaction of sulfur-containing compounds.Thus, the close location of the CoMo component and zinc oxide leads to free diffusion of sulfur deep into the volume of the catalyst-adsorbent and, consequently, to an increase in the operating time in the process of desulfurization of natural gas.

[0051] As for the aluminum oxide particles that can partially or completely cover the zinc oxide, according to the X-ray photoelectron spectroscopy (XPS) data of the catalyst-adsorbent samples prepared in the described manner, the surface molar ratio of Al:Zn varies in the range of 0.5-0.9.

[0052] The technical result consists of the following components:

[0053] 1. Preliminary dry mixing of powders, which are sources of zinc oxide and aluminum oxide, and a powder containing cobalt and molybdenum compounds, plasticization of the powder mixture to obtain a plastic molding paste, granulation, drying and heat treatment of the granules ensure the formation of a layered spatial structure of the components of the bifunctional catalyst-adsorbent and a uniform distribution of the components in the volume of the catalyst, while the catalyst-adsorbent contains, by weight %: ZnO - not less than 50, Al2O3 - not more than 45, a total of Co and Mo compounds in terms of oxides in the range of 0.5-10.

[0054] 2. Calcination in a flow of oxygen-containing gas decomposes the aluminum oxide and zinc oxide sources, forming aluminum and zinc oxides, respectively. After calcination, the Co and Mo compounds are converted into oxide compounds. The resulting catalyst-adsorbent consists of spatial structures consisting of zinc oxide particles partially or completely coated with aluminum oxide, which in turn contains a CoMo component, preferably the CoMoO4 phase.

[0055] 3. The inventive method, which results in the addition of a zinc compound in the form of ZnO in an amount of at least 50% by weight to the adsorbent catalyst, ensures activity in the hydrogen sulfide adsorption reaction and, consequently, high sorption capacity. The Zn-containing precursor powder can be obtained using suitable methods.

[0056] 4. The implementation of the claimed method results in the production of cobalt and molybdenum oxide compounds localized on aluminum oxide as part of the adsorbent catalyst. The sulfidation of these compounds by sulfur-containing compounds present in the natural gas leads to the formation of the most active component—the CoMoS phase in the form of particles optimal for catalyzing the hydrogenolysis reaction of the CS bond of organosulfur compounds present in the natural gas. Moreover, the total amount of cobalt and molybdenum compounds, calculated as metal oxides, is 0.5-10 wt.%, and the Co:Mo molar ratio is in the range of 0.1-1.

[0057] 5. Obtaining, as a result of implementing the claimed method, aluminum oxide Al2O3 as a binder between the active components responsible for bifunctionality (adsorption of hydrogen sulfide and the hydrogenolysis reaction of the CS bond), as well as for the formation of a developed porous structure of the catalyst-adsorbent, ensuring access of all sulfur-containing molecules of the raw material to be converted to the CoMo and ZnO components.

[0058] Brief description of drawings

[0059] The figure shows the results of HRTEM analysis of the catalyst-adsorbent sample from Example 3 after desulfurization of the model mixture. The micrograph shows the relative positions of zinc oxide, aluminum oxide, and MoS2 particles, which form sandwich-like structures.

[0060] Implementation of the invention

[0061] A zinc-containing precursor powder is prepared as a source of zinc oxide. This study utilizes a zinc salt precipitation method using sodium hydroxide, ammonium bicarbonate, and / or ammonia as precipitants.

[0062] Solutions of zinc nitrate and precipitant are prepared: weighed portions of the required compounds are dissolved in a specified volume of water. The precipitant solution is then added dropwise to the initial zinc nitrate solution in a reaction vessel, maintaining a constant pH and temperature. A chemical reaction occurs within the solution, accompanied by the formation of nanosized particles of an insoluble zinc compound. After the addition of the precipitant solution is complete, the resulting suspension is aged for several hours.

[0063] The suspension is then filtered to obtain a zinc-containing precursor powder on the filter. The resulting precipitate is washed to remove anions by wash filtration with the required amount of water. The precipitate is then air-dried at 110±10°C. During the drying process, adsorbed water is removed and the metal hydroxide is dehydrated.

[0064] Prepare a powder of the CoMo component, which contains cobalt and molybdenum compounds. For this, weighed portions of ammonium paramolybdate, cobalt hydroxide, and citric acid are selected. Dissolve the measured portions in a volume of water with continuous stirring at a temperature of 60°C to form a solution of chelated cobalt and molybdenum compounds with the formula [Co(H2O)2(C6H5O7)]2[Mo4O 11(C6H5O7)2]. Drying is then carried out in a spray dryer at an inlet air temperature no higher than 350°C and continuous stirring of the repulped solution. The finished CoMo precursor powder is unloaded from the receiving tank (cup) of the spray dryer's cyclone dust collector. The resulting precursor is then heat-treated in a muffle furnace at a temperature of (350±10)°C for 4 hours to obtain the CoMo component. The Co:Mo molar ratio in this powder depends on the measured weights of the metal compounds and ranges from 0.1 to 1.

[0065] Take a sample of pseudoboehmite (PB) that meets the following requirements:

[0066] - mass fraction of aluminum oxide, wt.% not less than 70;

[0067] - mass fraction of sodium, wt.% no more than 0.03;

[0068] - mass fraction of mass loss on ignition at (500±10)°C, wt.% 25-30;

[0069] - specific surface area, m 2 / g not less than 150.

[0070] Instead of PB powder, it is possible to use boehmite with similar characteristics.

[0071] Next, a plastic mass is prepared by mixing and peptizing the Zn-containing precursor powder, the CoMo component, and pseudoboehmite in a Z-blade mixer in the presence of an aqueous ammonia solution. Other plasticizing agents may be used to ensure the formation of the plastic mass.

[0072] The finished plastic mass is transferred from the mixer into the extruder and pressed through the die opening at a pressure of no more than 5.0 MPa to obtain extrudates of the finished catalyst-adsorbent with a cross-section in the form of a circle with a diameter of 1.0-4.5 mm.

[0073] The extrudates are then subjected to heat treatment, which includes a preliminary drying stage. The extrudates are kept in a drying oven at a temperature of (110 ± 10) °C for 5 hours. After drying, the resulting extrudates are broken into granules 3-5 mm long. Heat treatment is carried out in a muffle furnace with dry air supplied to the furnace chamber. The extrudates are placed in a porcelain cup and calcined at a temperature of (500 ± 10) °C for 4 hours.

[0074] The finished catalyst-adsorbent contains, by weight: Al2O3 - no more than 45, zinc oxide - not less than 50, Co and Mo compounds in total calculated as oxides 0.5-10 with a Co:Mo molar ratio in the range of 0.1-1. The content of elements in the catalyst-adsorbent samples is determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst ensures a close arrangement of the CoMo component, binder and zinc oxide, where the zinc oxide particles are completely or partially covered with aluminum oxide particles, and the cobalt and molybdenum compounds preferably form a CoMoO4 phase located on aluminum oxide, which, during the process of sulfur removal from APG, passes to the CoMoS phase. The HRTEM photograph (Fig.) shows the relative positions of zinc oxide, aluminum oxide, and MoS2 particles. Co particles, also part of the CoMoS2 phase, are not visualized by this method.

[0075] The calcined extrudates are characterized by XPS results with a surface Al:Zn molar ratio in the range of 0.5-0.9. According to the results of low-temperature nitrogen desorption, the samples have a specific surface area of ​​15-90 m 2 / g, pore volume 0.05-0.5 cm 3 / g, which are typical for hydrocarbon gas desulfurization processes. Extrudates are cylindrical granules with a diameter of 1.0-4.5 mm and a length of 3-5 mm.

[0076] The efficiency of using the proposed adsorbent catalyst in the process of hydrodesulfurization of a model mixture in a fixed-bed flow tubular reactor is estimated by the breakthrough time of 10 ppm for ethyl mercaptan EtSH and by the breakthrough time of 10 ppm for hydrogen sulfide H2S.

[0077] The model mixture has the following composition, vol.%: 0.235 - H2S, 0.015 - EtSH, the rest is CH4. Before the catalytic experiment, the catalyst-adsorbent layer is purged with helium at a temperature of 140 ° C, the mass feed rate is 50 ml / min. Then, the catalytic experiment is carried out under the following conditions: P = 3.0 MPa, T = 340 ± 5 ° C, H2 feed rate - 10 ml / min, the volumetric feed rate of the model feedstock is 2000 h -1 Gas samples are taken every 20 minutes and the reaction products are analyzed using a Crystal 2000M chromatograph. The experimentally determined breakthrough times are presented in the table.

[0078] The essence of the invention is illustrated by the following examples:

[0079] Example 1 comparative

[0080] The industrial adsorbent Katalco-32-4 (Johnson Matthey PLC) is based on zinc oxide and a binder in the form of spherical granules with a diameter of 2.0-4.8 mm. The adsorbent is tested in a fixed-bed tubular flow reactor using a model mixture under the conditions described above.

[0081] Example 2

[0082] The adsorbent catalyst is prepared as follows.

[0083] Take 221.5 g of zinc nitrate crystalline hydrate powder and dissolve it in 1500 ml of water. Prepare a 2 M precipitant solution by dissolving 80 g of sodium hydroxide in 1000 ml of water. Next, add the precipitant to the zinc nitrate with constant stirring at a rate of 5 ml / min and a precipitation temperature of 20°C. When pH 7 is reached, stop adding the precipitant. When pH 8-9 is reached, begin the aging stage, which lasts 4 hours at a temperature of 40°C while maintaining the pH.

[0084] The resulting suspension is filtered under vacuum using a large Nutsche filter, a fabric filter, and a Blue Ribbon paper filter and washed three times with 1 L of distilled water until the residual sodium content, calculated on a dry solid basis, is 0.03 wt%. The resulting precipitate is dried in a drying oven at a temperature of (110±10)°C for 6 hours. This produces a Zn-containing precursor powder.

[0085] The CoMo component is prepared as follows. 4.4 g of cobalt hydroxide, 88 g of ammonium paramolybdate, and 13.7 g of citric acid are dissolved in 1250 ml of water with constant stirring until a homogeneous solution without sediment is formed. Thus, the Co:Mo molar ratio in the solution and the subsequent CoMo component is 0.1. The resulting homogeneous solution is sprayed in a spray dryer at a coolant temperature at the separator inlet no higher than 350°C until a dry powdered CoMo component precursor is obtained. The resulting precursor is then held in a muffle furnace at (350±10)°C for 4 hours to obtain CoMo powder.

[0086] A 129 g sample of Zn-containing precursor powder, 0.14 g of pseudoboehmite, and 0.5 g of the CoMo component are placed in a mixer trough with Z-shaped blades, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5 MPa through a die, producing particles with a circular cross-section and a diameter of 1 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0087] The result is a catalyst-adsorbent containing, wt.%: Al2O3 - 0.1; ZnO - 99.4, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 0.1. The sample has a surface molar ratio of Al:Zn equal to 0.51, a specific surface area of ​​15 m 2 / g, pore volume 0.05 cm 3 / g, and is a cylindrical granule with a diameter of 1.0 mm and a length of 3-5 mm.

[0088] Example 3

[0089] The catalyst-adsorbent is prepared as follows. Take 147.7 g of powdered zinc nitrate crystalline hydrate and dissolve it in 1000 ml of water. Prepare a 2M precipitant solution by dissolving 124.5 g of ammonium bicarbonate in 780 ml of water. Prepare a 15 wt.% ammonia solution by diluting 280 ml of a 25 wt.% aqueous ammonia solution to 450 ml. Next, add the precipitant to the zinc nitrate at a rate of 10 ml / min with constant stirring and a precipitation temperature of 60°C. Then add the ammonia solution at a rate of 20 ml / min to achieve the required pH of the solution. Upon reaching pH = 7, stop feeding the precipitant. Upon reaching pH = 8-9, begin the aging stage, which lasts 5 hours at a temperature of 60°C and while maintaining the pH value.

[0090] The resulting suspension is vacuum filtered using a large Nutsche filter, a fabric filter, and a Blue Ribbon paper filter and washed three times with 1 L of distilled water until the residual sodium content, calculated as dry solids, is 0.03 wt%. The resulting precipitate is dried in a drying oven at 110°C for 6 hours. This produces a Zn-containing precursor powder.

[0091] The CoMo component is prepared as follows. 44 g of cobalt hydroxide, 88 g of ammonium paramolybdate, and 137 g of citric acid are dissolved in 1250 ml of water with constant stirring until a homogeneous solution without sediment is formed. Thus, the Co:Mo molar ratio in the solution and the subsequent CoMo component is 1. The resulting homogeneous solution is sprayed in a spray dryer at a coolant temperature at the separator inlet no higher than 350°C until a dry powdered CoMo component precursor is obtained. The resulting precursor is then held in a muffle furnace at (350±10)°C for 4 hours to obtain CoMo powder.

[0092] A sample of 111.1 g of Zn-containing precursor powder, 98.6 g of pseudoboehmite, and 8 g of Co-Mo powder are placed in the trough of a mixer with Z-shaped blades, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 1.4 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0093] As a result, a catalyst-adsorbent is obtained containing, by weight %: Al2O3 - 45; ZnO - 50, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 1. The sample has a surface molar ratio of Al:Zn equal to 0.90, a specific surface area of ​​90 m 2 / g, pore volume 0.5 cm 3 / g, and is a cylindrical granule with a diameter of 1.4 mm and a length of 3-5 mm.

[0094] Example 4

[0095] The catalyst-adsorbent is prepared as follows. Take 147.7 g of powdered zinc nitrate crystalline hydrate and dissolve it in 1000 ml of water. Prepare a 2M precipitant solution by dissolving 159.6 g of ammonium bicarbonate in 1000 ml of water. Also prepare a 3M ammonia solution by diluting 225 ml of concentrated 25 wt.% aqueous ammonia solution to 1000 ml. Next, add the precipitant to the zinc nitrate at a rate of 5 ml / min with constant stirring and a precipitation temperature of 60°C. Then add the ammonia solution at a rate of 5 ml / min to achieve the required pH of the solution. Upon reaching pH = 7, stop feeding the precipitant. Upon reaching pH = 8-9, begin the aging stage, which lasts 5 hours at a temperature of 60°C and while maintaining the pH value.

[0096] The resulting suspension is vacuum filtered using a large Nutsche filter, a fabric filter, and a Blue Ribbon paper filter and washed three times with 1 L of distilled water until the residual sodium content, calculated as dry solids, is 0.03 wt%. The resulting precipitate is dried in an oven at 110°C for 6 hours. This produces a Zn-containing precursor powder.

[0097] The CoMo component is prepared as follows. 30 g of cobalt hydroxide, 88 g of ammonium paramolybdate, and 93 g of citric acid are dissolved in 1250 ml of water with constant stirring until a homogeneous solution without sediment is formed. Thus, the Co:Mo molar ratio in the solution and the subsequent CoMo component is 0.68. The resulting homogeneous solution is sprayed in a spray dryer at a coolant temperature at the separator inlet no higher than 350°C until a dry powdered CoMo component precursor is obtained. The resulting precursor is then held in a muffle furnace at (350±10)°C for 4 hours to obtain CoMo powder.

[0098] A 100 g sample of Zn-containing precursor powder, 11.7 g of pseudoboehmite, and 10.7 g of CoMo powder are placed in the trough of a Z-blade mixer, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 3.5 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0099] The result is a catalyst-adsorbent containing, wt.%: Al2O3 - 9; ZnO - 81, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 0.68. The sample has a surface molar ratio of Al:Zn equal to 0.64, a specific surface area of ​​68 m 2 / g, pore volume 0.3 cm 3 / g, and is a cylindrical granule with a diameter of 3.5 mm and a length of 3-5 mm.

[0100] Example 5

[0101] Prepare zinc-containing powder similar to example 1 and a CoMo component similar to example 2.

[0102] A sample of 103 g of Zn-containing precursor powder, 13.7 g of pseudoboehmite, and 10 g of CoMo powder are placed in the trough of a mixer with Z-shaped blades, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 2.2 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0103] As a result, a catalyst-adsorbent is obtained containing, by weight %: Al2O3 - 10; ZnO - 80, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 1. The sample has a surface molar ratio of Al:Zn equal to 0.53, a specific surface area of ​​20 m 2 / g, pore volume 0.08 cm 3 / g, and is a cylindrical granule with a diameter of 2.2 mm and a length of 3-5 mm.

[0104] Example 6

[0105] Prepare zinc-containing powder similar to example 1 and a CoMo component similar to example 3.

[0106] A sample of 103.9 g of Zn-containing precursor powder, 12.3 g of pseudoboehmite, and 11.0 g of CoMo powder are placed in the trough of a mixer with Z-shaped blades, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 3.5 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0107] The result is a catalyst-adsorbent containing, wt.%: Al2O3 - 9; ZnO - 81, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 0.68. The sample has a surface molar ratio of Al:Zn equal to 0.88, a specific surface area of ​​25 m 2 / g, pore volume 0.09 cm 3 / g, and is a cylindrical granule with a diameter of 3.5 mm and a length of 3-5 mm.

[0108] Example 7

[0109] Prepare zinc-containing powder similar to example 2 and a CoMo component similar to example 1.

[0110] A sample of 111.1 g of Zn-containing precursor powder, 26.7 g of pseudoboehmite, and 0.5 g of CoMo powder are placed in the trough of a Z-blade mixer, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 4.5 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0111] The result is a catalyst-adsorbent containing, wt.%: Al2O3 - 19.5; ZnO - 80, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 0.1. The sample has a surface molar ratio of Al:Zn equal to 0.78, a specific surface area of ​​48 m 2 / g, pore volume 0.17 cm 3 / g, and is a cylindrical granule with a diameter of 4.5 mm and a length of 3-5 mm.

[0112] Example 8

[0113] Prepare zinc-containing powder similar to example 2 and a CoMo component similar to example 3.

[0114] A sample of 111.1 g of Zn-containing precursor powder, 12.3 g of pseudoboehmite, and 11 g of CoMo powder are placed in the trough of a Z-blade mixer, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 3.5 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0115] The result is a catalyst-adsorbent containing, wt.%: Al2O3 - 9; ZnO - 81, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 0.68. The sample has a surface molar ratio of Al:Zn equal to 0.67, a specific surface area of ​​55 m 2 / g, pore volume 0.22 cm 3 / g, and is a cylindrical granule with a diameter of 3.5 mm and a length of 3-5 mm.

[0116] Example 9

[0117] Prepare zinc-containing powder similar to example 3 and a CoMo component similar to example 1.

[0118] A sample of 111.1 g of Zn-containing precursor powder, 26.7 g of pseudoboehmite, and 0.5 g of CoMo powder are placed in the trough of a Z-blade mixer, peptized with a 2.5% wt. aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 4.1 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0119] As a result, a catalyst-adsorbent is obtained containing, by weight %: Al2O3 - 19.5; ZnO - 80, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 1. The sample has a surface molar ratio of Al:Zn equal to 0.85, a specific surface area of ​​52 m 2 / g, pore volume 0.2 cm 3 / g, and is a cylindrical granule with a diameter of 4.1 mm and a length of 3-5 mm.

[0120] Example 10

[0121] Prepare zinc-containing powder similar to example 3 and a CoMo component similar to example 2.

[0122] A sample of 111.1 g of Zn-containing precursor powder, 26.7 g of pseudoboehmite, and 0.5 g of CoMo powder are placed in the trough of a mixer with Z-shaped blades, peptized with a 2.5 wt% aqueous ammonia solution, and then extruded at a pressure of no more than 5.0 MPa through a die, producing particles with a circular cross-section and a diameter of 1.0 mm. The formed granules are dried, broken to an extrudate length of 3-5 mm, and calcined.

[0123] As a result, a catalyst-adsorbent is obtained containing, by weight %: Al2O3 - 19.5; ZnO - 80, Co and Mo compounds - the rest, with a molar ratio of Co:Mo = 1. The sample has a surface molar ratio of Al:Zn equal to 0.83, a specific surface area of ​​58 m 2 / g, pore volume 0.3 cm 3 / g, and is a cylindrical granule with a diameter of 1.0 mm and a length of 3-5 mm.

[0124] The results of testing catalyst-adsorbents for examples in the desulfurization of a model mixture are given in the table, where the breakthrough time is related to the mass of the catalyst-adsorbent sample.

[0125] Table

[0126] Catalyst from the example 1 2 3 4 5 6 7 8 9 10 Hydrogen sulfide breakthrough time, min / g 90 120 215 504 259 244 498 510 335 390 Breakthrough time at 10 ppm for ethyl mercaptan, min / g 45 57 204 505 255 156 68 294 124 286

[0127] Thus, as can be seen from the examples provided, the proposed preparation method results in the formation of a catalyst-adsorbent, which, with a certain ratio of its active components and binder, ensures the formation of spatial layered structures that enhance catalytic activity in organosulfur compound hydrogenolysis reactions and improve sulfur transport to zinc oxide. The resulting catalyst-adsorbent exhibits high activity in the hydrogenolysis reaction of CS bonds and an extended service life under desulfurization conditions for the model mixture.

Claims

1. A method for preparing a granulated catalyst-adsorbent for desulfurization of natural gas, including the stages of preliminary dry mixing of powders, which are sources of zinc oxide and aluminum oxide, with the addition of a plasticizing agent as a peptizer, stirring until a paste is obtained, followed by granulation, drying and calcination of the granules, characterized in that at the stage of mixing dry powders, a powder containing cobalt and molybdenum compounds is additionally added, wherein the sources of zinc oxide, aluminum oxide, cobalt and molybdenum compounds are taken in quantities that ensure the production of a catalyst-adsorbent, which contains, by weight: ZnO - not less than 50, Al2O3 - not more than 45, a total of Co and Mo compounds in terms of oxides - in the range of 0.5-10, while the molar ratio of Co:Mo is 0.1-1.

2. The method according to paragraph 1, characterized in that zinc-containing powder is used as a source of zinc oxide, which, upon thermal decomposition, yields zinc oxide as a product.

3. The method according to paragraph 1, characterized in that aluminum hydroxide is used as the source of aluminum oxide.

4. The method according to paragraph 3, characterized in that boehmite or pseudoboehmite is used as the aluminum hydroxide.

5. The method according to claim 1, characterized in that the powder containing Co and Mo compounds is a powder of chelated cobalt and molybdenum compounds obtained by spray drying an aqueous solution containing ammonium paramolybdate, cobalt hydroxide and citric acid, followed by heat treatment.

6. The method according to paragraph 1, characterized in that an ammonia solution is used as a plasticizing agent.

7. The method according to paragraph 1, characterized in that granulation is carried out by extrusion of the finished paste.

8. The method according to paragraph 7, characterized in that the extrusion of the paste is carried out at a pressure of no more than 5.0 MPa, the subsequent drying of the granules is at a temperature of (110±10) °C, and calcination in a flow of gas containing oxygen is at a temperature of (500±10) °C.

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