Macroporous alumina shaped supports and selective hydrogenation catalysts, methods of making and use thereof

Abstract

The present application relates to the technical field of catalyst, and discloses a macroporous alumina formed carrier and a selective hydrogenation catalyst as well as a preparation method and application thereof.The carrier preparation process is simple, has higher pore volume, pore diameter and lower bulk density, so that the catalyst prepared by using the carrier has the advantages of high activity, good selectivity, strong water resistance, less green oil generation, low temperature rise in the reaction process, long catalyst service life and the like, can effectively convert acetylene components in C4 fraction into olefins, and improve the utilization rate of acetylene components in C4 fraction and enterprise benefits.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a macroporous alumina molded support and a selective hydrogenation catalyst, as well as their preparation method and application. Background Technology

[0002] Naphtha steam cracking is widely used in the production of ethylene and propylene. During cracking, a mixture containing four carbon atoms, including alkanes, alkenes, dienes, and alkynes, is produced as a byproduct. This mixture accounts for approximately 10-15% of the total feedstock mass and is called the C4 fraction. In this fraction, the content of 1,3-butadiene is as high as 40-60%, and the alkyne content is 0.5-2.0%. Butadiene is one of the most important components of the C4 fraction and a major raw material for synthetic rubber. Because there are strict limits on the alkyne content in polymer-grade butadiene, extractive distillation is commonly used in industry to obtain high-purity butadiene. However, the extraction of butadiene generates a large amount of tail gas rich in alkynes such as ethylacetylene and vinylacetylene. Due to the risk of fire and explosion from tail gas with high alkyne content, it is usually diluted with a large amount of C4 raffinate before being used as fuel gas or directly discharged into a flare system. These operations not only waste a large amount of C4 resources but also generate significant amounts of greenhouse gases, polluting the environment. Therefore, converting alkynes into olefins through hydrogenation technology has become an effective method to increase the utilization rate of alkyne components in C4 fractions and improve enterprise efficiency.

[0003] CN106622245A discloses a catalyst for selective hydrogenation of alkynes in C4 fractions and its application. This catalyst uses carbon-coated alumina as a support, with Cu and Ni loaded as active components. The activity of the hydrogenation catalyst is improved by modifying the support through carbon coating, thereby altering its pore structure.

[0004] CN105727951A discloses a selective hydrogenation catalyst and its preparation method. The catalyst uses an alumina-niobium oxide composite support, with palladium as the active component and lead as a co-active component. The addition of lead enhances its interaction with palladium, effectively solving the problem of palladium loss. Furthermore, the addition of niobium oxide improves the acidity and thermal stability of the catalyst support, stabilizes the low-valence reactive centers, and gives the catalyst better hydrogenation activity and selectivity.

[0005] CN109701552A discloses a C4 fraction selective hydrogenation catalyst. By preparing Pdx / Cu sub-nano particles, the size of the active Pd sites is reduced, the dispersion is improved, and the utilization rate of precious metals is increased, thereby reducing the catalyst cost. The geometric and electronic effects exhibited by the sub-nano Pd sites improve the hydrogenation catalytic activity per unit mass of Pd and the butene selectivity. Furthermore, due to the high dispersion of the active component and the reduced number of polymerization sites, the catalyst stability is also improved.

[0006] CN109759060A discloses a C4 component selective hydrogenation catalyst and its preparation method. The catalyst uses palladium and manganese as active components, and a mixture of γ-Al₂O₃, CeO₂-ZrO₂, and attapulgite as a support. Through the interaction between the active component palladium and the co-active component manganese, the catalyst effectively balances activity and selectivity, enhances the removal depth of alkynes, and improves the yield of monobutene. Furthermore, this catalyst is not easily pulverized, has high mechanical strength, and offers advantages such as ease of use and long service life.

[0007] The invention has made optimizations and improvements in terms of the active components of the support or loaded catalyst, but there is still much room for improvement in the catalyst's resistance to water and carbon buildup. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of insufficient water resistance and carbon deposition resistance in existing C4 fraction hydrogenation catalysts, and to provide a macroporous alumina molded support, a selective hydrogenation catalyst, its preparation method, and its application. The catalyst provided by this invention has advantages such as high activity, good selectivity, strong water resistance, low green oil formation, low temperature rise during the reaction, long catalyst lifetime, and simple preparation process.

[0009] To achieve the above objectives, the present invention provides a macroporous alumina forming carrier, wherein the bulk density of the carrier is not more than 1 g / mL and the pore volume is not less than 0.4 mL / g.

[0010] A second aspect of the present invention provides a method for preparing a macroporous alumina molded catalyst support, the method comprising mixing boehmite with α-Al2O3 and molding the resulting mixture, wherein the α-Al2O3 accounts for 5-25% by weight of the total weight of the powder used.

[0011] A third aspect of the present invention provides a selective hydrogenation catalyst, the catalyst comprising a support and an active component, wherein the support is the macroporous alumina molded support described in the first aspect or the support prepared by the method described in the second aspect, and the active component is Pd.

[0012] A fourth aspect of the present invention provides a method for preparing a selective hydrogenation catalyst, the method comprising loading an active component onto a support, wherein the support is the macroporous alumina molded support described in the first aspect or the support prepared by the method described in the second aspect, and the active component is Pd.

[0013] The fifth aspect of the present invention provides the application of the macroporous alumina molded support as described above, the support prepared by the method as described above, the selective hydrogenation catalyst as described above, or the selective hydrogenation catalyst prepared by the method as described above in the hydrogenation and removal of alkynes from C4 fractions.

[0014] The sixth aspect of the present invention provides a method for hydrogenating a C4 fraction, the method comprising: introducing a mixture of a C4 fraction feedstock and a solvent with H2 into a reactor for selective hydrogenation reaction in the presence of the catalyst described in the third aspect;

[0015] Alternatively, the catalyst can be prepared according to the method described in the fourth aspect, and then, in the presence of the obtained catalyst, a mixture of C4 fraction feedstock and solvent and H2 can be introduced into a reactor for selective hydrogenation.

[0016] Through the above technical solution, the present invention can achieve the following beneficial effects:

[0017] (1) The macroporous alumina forming carrier provided by the present invention has higher pore volume, pore size and lower bulk density by adding α-Al2O3 during the forming process, thereby improving the performance of the catalyst prepared by the carrier.

[0018] (2) The preferred shaped catalyst provided by the present invention has silane groups grafted onto it, which further effectively improves the water resistance and carbon deposition resistance of the catalyst prepared using this support, and extends the service life of the catalyst.

[0019] (3) The preparation method of the macroporous alumina forming support and selective hydrogenation catalyst provided by the present invention is simple, the raw materials are readily available, and it is suitable for large-scale industrial production and promotion.

[0020] (4) The selective hydrogenation catalyst provided by the present invention has the advantages of high activity, good (butadiene) selectivity, strong water resistance, low green oil production, low temperature rise during the reaction, long catalyst life and simple preparation process. It can effectively convert the alkyne components in C4 fraction into olefins, improve the utilization rate of alkyne components in C4 fraction and improve enterprise benefits. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The inventors of this invention ingeniously discovered during their research that when boehmite and α-Al₂O₃ are mixed and kneaded to form a shaped catalyst support, the boehmite powder crystals gradually dehydrate during high-temperature calcination, forming more crystalline grains that act as a binder to hold the grains together. During high-temperature calcination, the particle size and volume of the two crystal particles, boehmite and α-Al₂O₃, do not change synchronously. The α-Al₂O₃ powder grains support and disperse the boehmite grains, resulting in a shaped catalyst support with increased pore size and volume, and decreased bulk density. Further research revealed that using this catalyst support to prepare a catalyst for the hydrogenation and deacetylation of C4 fractions, and grafting silane groups onto the catalyst surface, effectively improves the catalyst's water resistance and anti-carbon deposition properties, thereby enhancing its catalytic efficiency and lifespan.

[0023] In one aspect, the present invention provides a macroporous alumina forming carrier, wherein the bulk density of the carrier is not more than 1 g / mL and the pore volume is not less than 0.4 mL / g.

[0024] Preferably, the bulk density of the carrier does not exceed 0.95 g / mL.

[0025] More preferably, the bulk density of the carrier is 0.30-0.95 g / mL and the pore volume is 0.4-0.9 mL / g.

[0026] More preferably, the bulk density of the carrier is 0.4-0.9 g / mL and the pore volume is 0.55-0.85 mL / g.

[0027] More preferably, the specific surface area of ​​the carrier is 5-120 m². 2 / g, with most probable pore size of 0.12-0.25μm, pore size distribution of 40-280nm, and water absorption rate of 45-68%.

[0028] Preferably, for the carrier with a particle size of φ4-6mm, its strength is not less than 30Nm / particle. More preferably, it is 30-200Nm / particle.

[0029] In this invention, there are no particular limitations on the shape of the provided molded catalyst support; it can be made into any shape existing in the art. For example, it can be a conventional regular shape such as a sphere or cylinder, or an irregular shape commonly found in the art such as a clover shape. When the molded catalyst support is a regular sphere, its particle size refers to its diameter; when the catalyst shape is not a regular sphere, the catalyst size refers to its equivalent diameter. The equivalent diameter refers to the diameter of an irregularly shaped particle when it is converted into a sphere using an equivalent method. In production applications, to facilitate the determination of the particle size of the molded catalyst support, a mesh sieve can be used to detect or select supports that meet the particle size requirements. For example, a molded catalyst support with a particle size of φ4-6mm is a support that can pass through a 3-mesh sieve but cannot pass through a 5-mesh sieve.

[0030] To further control parameters such as strength, specific surface area, and pore volume of the molded support, making it more suitable for industrial catalyst preparation and improving the performance of catalysts made using this molded support (especially the performance of C4 fraction selective hydrogenation catalysts made using this support), preferably, the support also contains a cofactor. Preferably, the cofactor is selected from at least one of halogens, La, Ce, Pr, K, F, Mg, and Si.

[0031] More preferably, based on the total weight of the carrier, the content of the auxiliary component does not exceed 2% by weight. Preferably, it is 0.05-1.5% by weight.

[0032] A second aspect of the present invention provides a method for preparing a macroporous alumina molded carrier, the method comprising mixing boehmite with α-Al2O3 and molding the resulting mixture, wherein the α-Al2O3 accounts for 5-25% by weight of the total weight of the powder used. "Total weight of powder used" refers to the total weight of the mixed boehmite and α-Al2O3, hereinafter the same.

[0033] Preferably, the specific surface area of ​​the pseudoboehmite is 200-300 m². 2 / g, pore volume is 0.5-1.1mL / g, and bulk density does not exceed 0.5g / mL.

[0034] According to a preferred embodiment of the present invention, the α-Al2O3 is selected from α-Al2O3 powder with a particle size not exceeding 120 μm.

[0035] Preferably, the particle size (distribution range) of the α-Al2O3 powder is 2-110 μm, wherein the content of α-Al2O3 is not less than 95% by weight, preferably 97-100% by weight.

[0036] This invention can use any α-Al₂O₃ powder with the above-mentioned characteristics from the art for the preparation of the molded catalyst support. It can be a commercially available product or a related product prepared according to existing technology. Due to limitations in the preparation process and method, the α-Al₂O₃ powder may contain a certain amount of impurities (impurities), such as Na, Fe, Si, etc. Preferably, the total content of Na, Fe, and Si in the α-Al₂O₃ powder, by elemental calculation, does not exceed 0.1% by weight. Preferably, the α-Al₂O₃ powder accounts for 5-20% by weight of the total weight of the powder used.

[0037] In order to achieve the purpose of powder forming, according to a preferred embodiment of the present invention, the mixture is prepared by mixing an acidic aqueous solution with boehmite and α-Al2O3 powder.

[0038] Preferably, the mass percentage concentration of acid in the acidic aqueous solution is 0.1-15%, more preferably 0.1-10%.

[0039] Preferably, the weight ratio of the acidic aqueous solution to the total weight of the powder used is 0.5-5:1, more preferably 0.6-2.5:1. The amount of acidic aqueous solution can be adjusted according to the physical properties of the carrier after molding, such as specific surface area, bulk density, and strength.

[0040] More preferably, the acidic aqueous solution is selected from at least one aqueous solution of hydrochloric acid, nitric acid, sulfuric acid, acetic acid, oxalic acid, citric acid, phosphoric acid, and ammonium dihydrogen phosphate. Preferably, it is an aqueous solution of at least one of nitric acid, acetic acid, oxalic acid, and citric acid.

[0041] To facilitate carrier molding, according to a preferred embodiment of the present invention, the mixture further contains molding auxiliaries. These molding auxiliaries refer to pore-expanding agents, extrusion aids, etc., used during molding, and may be, for example, at least one of the following: guar gum powder, starch, polyethylene glycol, carboxymethyl cellulose, polystyrene, urea, polyacrylate, acrylic acid, methylamine, ethylenediamine, ammonium carbonate, and ammonium bicarbonate.

[0042] According to a preferred embodiment of the present invention, the molding operation includes the steps of kneading, shaping, drying and firing the mixture in sequence.

[0043] In this invention, the purpose of the kneading step is to ensure that the pseudoboehmite and α-Al2O3 powder are fully bonded together. Any kneading method and conditions that can achieve this purpose are applicable to the method provided by this invention.

[0044] In this invention, the purpose of the shaping step is to form a molded carrier of a specified shape from the thoroughly mixed mixture after kneading. Any shaping method and conditions that can achieve this purpose are applicable to this invention. For example, the mixture can be extruded and then pressed into shape (i.e., pressed into a specific shape).

[0045] In this invention, there are no particular limitations on the specific shape of the molding carrier; it can be any existing shape in the art. For example, it can be a conventional shape such as granular, spherical, flake-like, toothed spherical, or strip-like, or it can be an irregular strip shape such as clover-shaped. According to a preferred embodiment of the invention, the particle size of the molding carrier does not exceed 10 mm, for example, it can be 1-6 mm. Preferably, it is 4-6 mm.

[0046] In this invention, the purpose of the drying step is to remove excess moisture from the carrier. Any drying method and conditions that can achieve this purpose are applicable to this invention. Preferably, the drying conditions may include: a temperature of 70-150°C and a time of 4-24 hours.

[0047] In this invention, the boehmite in the mixture is transformed during the roasting step to form alumina with a certain strength. Preferably, the roasting conditions include: a temperature of 1100-1200℃ and a time of 4-24h.

[0048] To further obtain suitable support properties such as strength, specific surface area, and pore volume, thereby improving the performance of the catalyst prepared using this support, according to a preferred embodiment of the present invention, the method further includes a step of adding a co-component precursor during the molding process.

[0049] Preferably, the auxiliary component precursor is a water-soluble salt of the auxiliary component. More preferably, the auxiliary component is selected from at least one of halogens, La, Ce, Pr, K, F, Mg, and Si.

[0050] A third aspect of the present invention provides a selective hydrogenation catalyst, the catalyst comprising a support and an active component, wherein the support is the macroporous alumina molded support described in the first aspect or the support prepared by the method described in the second aspect, and the active component is Pd.

[0051] According to a preferred embodiment of the present invention, the content of the active component (in terms of elements) is 0.01-0.5% by weight, based on the total weight of the carrier.

[0052] To further improve the hydrogenation effect of the catalyst, preferably, the catalyst may also include a co-activating component.

[0053] Preferably, the active ingredient is selected from at least one of Ag, Au, Ga, As, Bi, Pb, Sn, Cr, rare earth elements, alkali metals and alkaline earth metals.

[0054] More preferably, the content of the active ingredient is 0-10% by weight, based on the total weight of the carrier.

[0055] To improve the water resistance of the catalyst, the catalyst may preferably further include silane groups grafted onto its surface. Preferably, the content of the silane groups is 1-20% by weight of the total weight of the catalyst. More preferably, it is 1-15% by weight. More preferably, it is 1-10% by weight.

[0056] More preferably, the silyl group is provided by a silylating agent. Preferably, the silylating agent is selected from at least one of methyldiethoxysilane, trimethyldiethoxysilane, ethyltriethoxysilane, diethyldiethoxysilane, triethylethoxysilane, ethyltrimethoxysilane, butyltriethoxysilane, dimethyl-ethylmethoxysilane, dimethyl-phenylethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, dimethyl-propylchlorosilane, dimethylisopropylchlorosilane, tributylchlorosilane, hexamethyldisilazane, heptamethyldisilazane, and tetramethyldisilazane.

[0057] The fourth aspect of the present invention provides a method for preparing a selective hydrogenation catalyst, the method comprising loading an active component onto a support, wherein the support is the macroporous alumina molded support described in the first aspect or the support prepared by the method described in the second aspect, and the active component is Pd.

[0058] In this invention, any existing method for preparing supported catalysts can be used to load the active component onto the support. According to a preferred embodiment of the invention, the loading method includes loading the active component precursor onto the support using a spraying method and / or an impregnation method.

[0059] Preferably, the method further includes loading the co-active component onto the carrier.

[0060] Preferably, the method further includes sequentially drying and calcining a catalyst semi-finished product loaded with an active component, or loaded with an active component and a co-active component, to obtain the catalyst.

[0061] More preferably, the drying conditions include a temperature of 70-150°C and a time of 3-48 hours.

[0062] More preferably, the calcination conditions include a temperature of 350-600°C and a time of 2-10 hours.

[0063] To improve the water resistance of the catalyst and further enhance its resistance to carbon deposition, according to a preferred embodiment of the present invention, the method further includes a step of grafting silane groups onto the surface of the calcined catalyst.

[0064] Preferably, the grafting method for the silane group is selected from liquid-phase and / or gas-phase methods.

[0065] More preferably, the silane group is provided by a silylating agent. The characteristics of the preferred silylating agent in this invention are as described above and will not be repeated here.

[0066] According to a preferred embodiment of the present invention, the liquid-phase method may include mixing a silylating agent with an organic solvent to obtain a silyl solvent. The silyl solvent is then contacted with a catalyst, thereby grafting silyl groups thereon onto the catalyst surface via the liquid-phase method.

[0067] Preferably, the organic solvent can be one of ketones, ethers, hydrocarbons, and esters, with ethers and hydrocarbons being more preferred. More preferably, it is at least one of toluene, benzene, xylene, cyclohexane, n-hexane, heptane, diethyl ether, phenethyl ether, tetrahydrofuran, liquid paraffin, and hydrogenated saturated gasoline.

[0068] More preferably, the amount of the silylating agent is such that the weight of the silyl groups grafted onto the catalyst surface accounts for 0.01-15% of the total weight of the catalyst.

[0069] More preferably, the conditions for the liquid-phase method may include a reaction temperature of 30-200°C and a time of 20-120 min. To better control the reaction temperature and maintain a constant temperature during the silane group grafting process, heating can be performed using methods such as an oil bath during the liquid-phase reaction.

[0070] The fifth aspect of this invention provides the application of the macroporous alumina molding support described in the first aspect, the support prepared by the method described in the second aspect, the selective hydrogenation catalyst described in the third aspect, or the selective hydrogenation catalyst prepared by the method described in the fourth aspect in the hydrogenation and removal of alkynes from C4 fractions. The "hydrogenation and removal of alkynes from C4 fractions" refers to the process of selectively hydrogenating alkynes in C4 fractions to obtain olefins.

[0071] Based on the above findings, the sixth aspect of the present invention provides a method for hydrogenating C4 fraction, the method comprising: introducing a mixture of C4 fraction feedstock and solvent with H2 into a reactor for selective hydrogenation reaction in the presence of the catalyst described in the third aspect;

[0072] Alternatively, the catalyst can be prepared according to the method described in the fourth aspect, and then, in the presence of the obtained catalyst, a mixture of C4 fraction feedstock and solvent and H2 can be introduced into a reactor for selective hydrogenation.

[0073] In this invention, the solvent is an organic solvent capable of dissolving C4 fraction feedstock; any organic solvent capable of achieving the above-mentioned objective is suitable for this invention. According to a preferred embodiment of the invention, the solvent is selected from aqueous solutions of N-methylpyrrolidone and / or aqueous solutions of acetonitrile.

[0074] Preferably, the water content in the solvent does not exceed 10% by weight of the total weight of the solvent. More preferably, it is 5-10% by weight.

[0075] According to a preferred embodiment of the present invention, the weight ratio of the solvent to the C4 fraction feedstock is 0.1-0.5:1, preferably 0.1-0.3:1.

[0076] According to a preferred embodiment of the present invention, the molar ratio of H2 entering the reactor to alkynes in the mixture of C4 fraction feedstock and solvent is 0.5-1:1, preferably 0.8-1:1.

[0077] According to a preferred embodiment of the present invention, the conditions for the selective hydrogenation reaction include: reactor inlet temperature of 40-45°C, reactor pressure of 0.08-1.2 MPa, and liquid feed space velocity based on C4 fraction feedstock of 30-50 h⁻¹. -1 .

[0078] In this invention, the C4 fraction can be a mixture of pyrolysis C4 or C4 raffinate or C4 high-acetylene tail gas or a mixture thereof produced by a hydrocarbon steam cracking unit. Preferably, the 1,3-butadiene content is 3-60 wt%, the vinylacetylene content is 0.5-30 wt%, and the ethylacetylene content is 0.1-10 wt%.

[0079] To further control the reaction temperature rise, in this invention, the C4 fraction hydrogenation reactor can employ a single-stage or multi-stage reactor for the hydrogenation reaction. The alkyne conversion rate in each stage is controlled to manage the bed temperature rise, and a cooler is used between stages to remove reaction heat. Alternatively, the hydrogenation product after the reactor can be returned to the reactor inlet via a circulation pipeline to dilute the alkyne concentration at the reactor inlet and reduce the reactor temperature rise. This invention does not impose any particular limitations on the specific method of temperature rise control through the reaction process; it can be selected and adjusted according to actual conditions.

[0080] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0081] The pseudoboehmite used in the following examples has a specific surface area of ​​256.3 m². 2 / g, pore volume 0.936mL / g, bulk density 0.35g / mL, α-Al2O3 powder was obtained by calcining this pseudoboehmite at 1500℃, wherein the α-Al2O3 content is 99.5%, and the total content of Na, Fe, and Si is less than 0.1% by weight. Unless otherwise specified, all other reagents used were commercially available products from regular chemical suppliers and were of analytical grade.

[0082] In the following embodiments, the methods for detecting the carrier bulk density, strength, water absorption rate, pore volume, and most probable pore size are as follows:

[0083] Specific surface area was measured using the nitrogen physical adsorption BET method;

[0084] The bulk density was calculated by measuring the mass of 100 mL of alumina carrier, and the average value was taken after measuring each sample three times.

[0085] The pore volume and most probable pore size were measured by mercury porosimetry.

[0086] The strength was measured using a general particle strength measuring instrument. Twenty carrier particles were measured for each embodiment, and the average value of the measurement results was recorded.

[0087] The water absorption rate is calculated by taking 20g of the prepared molded carrier, immersing it in water for 10 minutes, taking it out and draining the surface water, and measuring the weight increase. That is, water absorption rate = weight difference before and after immersion / weight before immersion × 100%.

[0088] Example 1

[0089] 1. Preparation of the molding carrier

[0090] Weigh out 360g of boehmite powder, 40g of α-Al₂O₃ powder, 18g of guar gum powder, and 20g of starch, mix them evenly, and then put them into a kneader. Weigh out 4g of concentrated nitric acid (70%), 4g of acetic acid (36%), and 2.393g of lanthanum nitrate, add them to 400g of deionized water and stir evenly, then add them to the kneader. After kneading thoroughly, extrude, granulate, and shape to obtain toothed spherical particles with a particle size of φ4-6mm (which can pass through a 3-mesh sieve but not a 5-mesh sieve, the same applies below). Dry at 120℃ for 12h and then calcine in a muffle furnace at 1175℃ for 6h to obtain the shaped carrier S1. The molded carrier S1 was tested and found to have a bulk density of 0.574 g / mL, a strength of 54.2 Nm / particle, a pore volume of 0.71 mL / g, a most probable pore size of 0.165 μm, a pore size distribution of 50-276 nm, and a water absorption rate of 63.55%. The elemental content of La was 0.35% by weight.

[0091] 2. Preparation of selective hydrogenation catalysts

[0092] 0.12 g of silver nitrate was weighed and added to 3 mL of palladium nitrate solution (Pd content 50 mg / mL), diluted with deionized water to 28 mL, and sprayed onto 50 g of molded support S1. The sprayed sample was dried in an oven at 120 °C for 6 h, and then calcined at 450 °C for 8 h to obtain catalyst C1, with a Pd loading (i.e., the Pd content based on the weight of the support, hereinafter the same) of 0.3 wt% and an Ag loading of 0.15 wt%.

[0093] 25g of catalyst C1 was placed in a three-necked flask and placed in an oil bath at 110℃. One neck of the flask was connected to a cooling coil, one neck to a thermometer, and one neck to the feed inlet. First, 150mL of tetrahydrofuran solution was added, and after heating to 120℃, 5mL of trimethylchlorosilane was added. The reaction was carried out at a constant temperature for 120min, then cooled, removed, and dried to obtain C1-Si. The Si content was analyzed using an ICP-AES elemental analyzer, and the Si content in C1-Si was found to be 0.6wt%. Simultaneously, the organic carbon content was determined to be 0.85wt% using an organic carbon / elemental carbon (OC / EC) analyzer. Based on this, the silane content on catalyst C1-Si was approximately 1.90wt%.

[0094] Example 2

[0095] 1. Preparation of the molding carrier

[0096] Weigh out 320g of boehmite powder, 80g of α-Al₂O₃ powder, 18g of guar gum powder, and 20g of starch, mix them evenly, and then put them into a kneader. Weigh out 3g of concentrated nitric acid (70%), 4g of acetic acid (36%), and 3.728g of cerium nitrate, add them to 380g of deionized water and stir evenly, then add them to the kneader. After kneading thoroughly, the mixture is extruded, granulated, and shaped to obtain toothed spherical particles with a particle size of φ4-6mm. After drying at 120℃ for 12h, the particles are calcined in a muffle furnace at 1170℃ for 6h to obtain the shaped carrier S2. The molded carrier S2 was tested and found to have a bulk density of 0.551 g / mL, a strength of 49.6 Nm / particle, a pore volume of 0.74 ml / g, a most probable pore size of 0.168 μm, a pore size distribution of 45-270 nm, and a water absorption rate of 65.08%. The Ce content was 0.4 wt%.

[0097] 2. Preparation of selective hydrogenation catalysts

[0098] 0.12 g of lead nitrate and 0.19 g of bismuth nitrate were weighed and added to 3 mL of palladium nitrate solution (Pd content 50 mg / mL). The solution was diluted to 30 mL with deionized water and sprayed onto 50 g of alumina support S2. The sprayed sample was dried in an oven at 120 °C for 6 h and then calcined at 450 °C for 8 h to obtain catalyst C2, with a Pd loading of 0.3 wt%, a Pb loading of 0.15 wt%, and a Bi loading of 0.2 wt%.

[0099] 25g of catalyst C2 was placed in a three-necked flask and then placed in an oil bath at 110℃. One neck of the flask was connected to a cooling coil, one neck to a thermometer, and one neck to the feed inlet. After heating to 120℃, 100mL of p-xylene containing 1wt% trimethylchlorosilane was added. The mixture was reacted at a constant temperature for 120min, then cooled and dried to obtain C2-Si. The Si content was analyzed using an ICP-AES elemental analyzer, and the Si content in C2-Si was found to be 0.7wt%. Simultaneously, the organic carbon content was determined to be 1wt% using an organic carbon / elemental carbon (OC / EC) analyzer. Therefore, the silane content on catalyst C2-Si was approximately 2.25wt%.

[0100] Example 3

[0101] 1. Preparation of the molding carrier

[0102] 380g of boehmite powder, 20g of α-Al₂O₃ powder, 18g of guar gum powder, and 20g of starch were weighed and mixed evenly before being placed into a kneader. 4g of concentrated nitric acid (70%), 5g of acetic acid (36%), and 0.741g of potassium nitrate were weighed and added to 415g of deionized water, stirred evenly, and then added to the kneader. After thorough kneading, the mixture was extruded, pelletized, and shaped to obtain toothed spherical particles with a particle size of φ4-6mm. After drying at 120℃ for 12h, the particles were calcined in a muffle furnace at 1183℃ for 6h to obtain the molded carrier S3. The molded carrier S3 was tested and found to have a bulk density of 0.614g / mL, a strength of 59.4Nm / particle, a pore volume of 0.66ml / g, a most probable pore size of 0.156μm, a pore size distribution of 43-273nm, and a water absorption rate of 60.2%. The K content was 0.1% by weight.

[0103] 2. Preparation of selective hydrogenation catalysts

[0104] The catalyst preparation steps and operations were the same as in Example 1, and catalyst C3 was obtained.

[0105] 25g of catalyst C3 was placed in a three-necked flask and placed in an oil bath at 110℃. One neck of the flask was connected to a cooling coil, one neck to a thermometer, and one neck to the feed inlet. First, 150mL of p-xylene solution was added, and after heating to 120℃, 8mL of trimethylchlorosilane was added. The reaction was carried out at a constant temperature for 120min, then cooled and dried to obtain C3-Si. The Si content was analyzed using an ICP-AES elemental analyzer, and the Si content in C3-Si was found to be 0.7wt%. Simultaneously, the organic carbon content was determined to be 1wt% using an organic carbon / elemental carbon (OC / EC) analyzer. Therefore, the silane content on catalyst C3-Si was approximately 2.55wt%.

[0106] Example 4

[0107] The selective hydrogenation catalyst was prepared using the method described in Example 1, except that lanthanum nitrate was not added during the preparation of the molded support (i.e., the support did not contain La), resulting in molded support S4. The molded support S4 was tested and found to have a bulk density of 0.578 g / mL, a strength of 54.9 Nm / particle, a pore volume of 0.69 ml / g, a most probable pore size of 0.16 μm, a pore size distribution of 40-264 nm, and a water absorption rate of 63.28%.

[0108] All other steps and operations were the same as in Example 1, yielding catalysts C4 and C4-Si. The mass percentage of silanes on catalyst C4-Si was determined to be approximately 1.91 wt%.

[0109] Example 5

[0110] 1. Preparation of the molding carrier

[0111] Weigh out 280g of boehmite powder, 120g of α-Al₂O₃ powder, 18g of guar gum powder, and 20g of starch, mix them evenly, and then put them into a kneader. Weigh out 3g of concentrated nitric acid (70%), 3g of acetic acid (36%), and 2.586g of lanthanum nitrate, add them to 365g of deionized water and stir evenly, then add them to the kneader. After kneading thoroughly, the mixture is extruded, granulated, and shaped to obtain toothed spherical particles with a particle size of 4-6mm. After drying at 120℃ for 12h, the particles are calcined in a muffle furnace at 1166℃ for 6h to obtain the shaped carrier S5. The molded carrier S5 was tested and found to have a bulk density of 0.574 g / mL, a strength of 54.2 Nm / particle, a pore volume of 0.75 ml / g, a most probable pore size of 0.169 μm, a pore size distribution of 43-257 nm, and a water absorption rate of 63.55%. The content of La, calculated by element, was 0.35% by weight.

[0112] All other steps and operations were the same as in Example 1, yielding catalysts C5 and C5-Si. The mass percentage of silanes on catalyst C5-Si was determined to be approximately 1.90 wt%.

[0113] Example 6

[0114] The selective hydrogenation catalyst was prepared using the method described in Example 1, except that silver nitrate was not added to the palladium nitrate solution (i.e., the catalyst did not contain the co-active component Ag). All other steps and operations were the same as in Example 1, yielding catalysts C6 and C6-Si. The mass percentage of silanes on catalyst C6-Si was determined to be approximately 1.90 wt%.

[0115] Example 7

[0116] The selective hydrogenation catalyst was prepared using the method described in Example 1, except that silane groups were grafted onto the surface of catalyst C1 using the following method: 25g of catalyst C1 was placed in a three-necked flask and immersed in an oil bath at 110°C. One neck of the flask was connected to a cooling coil, one neck to a thermometer, and one neck to the feed inlet. After heating to 120°C, 100ml of p-xylene containing 9wt% trimethylchlorosilane was added. The mixture was reacted at a constant temperature for 120min, then cooled and dried to obtain C1-Si2. The Si content was analyzed using an ICP-AES elemental analyzer, and the Si content in C1-Si2 was found to be 6.3wt%. Simultaneously, the organic carbon content was determined to be 9wt% using an organic carbon / elemental carbon (OC / EC) analyzer. Based on this, the silane group mass percentage on the catalyst was approximately 20.25wt%. All other steps and operations were the same as in Example 1.

[0117] Comparative Example 1

[0118] 1. Preparation of the molding carrier

[0119] The method described in Example 1 was used, except that the raw materials added to the kneader were: 400g of boehmite powder, 18g of guar gum powder, and 4g of cellulose; 4g of concentrated nitric acid (70%), 4g of acetic acid (36%), and 2.393g of lanthanum nitrate were added to 400g of deionized water and stirred until a homogeneous solution was obtained. The remaining steps and operations were the same as in Example 1, resulting in molded carrier S6. The molded carrier S6 was tested and found to have a bulk density of 0.704g / mL, a strength of 80.6 Nm / particle, a pore volume of 0.52mL / g, a most probable pore size of 0.105μm, a pore size distribution of 45-262nm, and a La loading of 0.35%.

[0120] Selective hydrogenation catalysts were prepared using support S6, following the same steps and operations as in Example 1, yielding catalysts D1 and D1-Si. The silane content on catalyst D1-Si was determined to be approximately 1.90 wt%.

[0121] Comparative Example 2

[0122] The method described in Example 1 was used, except that 360g of boehmite powder and 40g of α-Al₂O₃ powder were replaced with 400g of α-Al₂O₃ powder. All other operations and conditions remained the same as in Example 1. During kneading, it was found that the materials still could not stick together after the addition of the acid solution, resulting in kneading failure and the inability to achieve the desired molding.

[0123] Test Example 1

[0124] 50 ml of the catalyst from the above examples and comparative examples were added to an adiabatic fixed-bed reactor, and evaluated under the following conditions. The evaluation results are shown in Table 1.

[0125] Among them, gas chromatography was used to detect the component content of C4 fraction feedstock and materials after selective hydrogenation using various catalysts, and butadiene selectivity was calculated according to the following formula.

[0126] Butadiene selectivity = (butadiene) out -Butadiene in ) / (Vinylacetylene in -Vinylacetylene out )×100%

[0127] The evaluation conditions were as follows: A mixture of NMP and water containing 7% water (NMP aqueous solution) was mixed with C4 fraction feed and fed into the selective hydrotreating reactor from top to bottom. The weight ratio of NMP aqueous solution to C4 fraction feed stream was 0.2:1, the reactor inlet temperature was 42°C, the pressure was 1.0 MPa, the molar ratio of hydrogen to alkyne content in the mixture stream at the inlet was 0.87:1, the vinylacetylene content at the reactor inlet was 2.76 wt%, and the liquid hourly space velocity (LHSV) calculated based on the C4 fraction feed rate was 40 h⁻¹. -1 .

[0128] Table 1 Catalyst Evaluation Results

[0129] Catalyst number 1,3-Butadiene / wt% Vinylacetylene / wt% Ethylacetylene / wt% Butadiene selectivity / % C4 fraction feedstock 13.02 2.76 0.82 / C1 13.86 1.09 0.66 50.3 C1-Si 13.94 1.02 0.62 52.87 C2 13.83 1.12 0.69 49.39 C2-Si 13.93 0.98 0.65 51.12 C3 13.84 1.11 0.68 49.60 C3-Si 13.95 0.96 0.64 51.83 C4 13.81 1.15 0.7 49.04 C4-Si 13.85 1.1 0.67 50.18 C5 13.72 1.29 0.69 47.90 C5-Si 13.77 1.2 0.72 48.30 C6 13.69 1.34 0.74 47.05 C6-Si 13.70 1.32 0.73 47.24 C1-Si2 13.41 1.84 0.76 42.30 D1 13.81 1.13 0.69 48.64 D1-Si 13.82 1.12 0.68 48.88

[0130] Table 1 shows the weight percentages of alkynes and olefins in the hydrogenated products after deducting the contents of NMP aqueous solution and hydrogen. Results of selective hydrogenation of the C4 fraction using the above catalysts with NMP aqueous solution as solvent indicate that catalysts C1-Si, C2-Si, and C3-Si, using macroporous alumina with added α-Al2O3 as a support and undergoing alkylation treatment, exhibit better selectivity and activity. The presence of water does not reduce or deactivate the catalyst activity, nor does it decrease the amount of 1,3-butadiene; instead, it washes away excess precipitates, significantly reducing surface coking and extending service life. Furthermore, the reduced alkyne concentration after dilution of the C4 fraction with NMP aqueous solution significantly lowers the temperature rise during hydrogenation, inhibiting over-hydrogenation and improving the selectivity of the hydrogenation catalyst.

[0131] The preparation method of the C4 fraction selective hydrogenation catalyst provided by the present invention is simple. It involves two steps: adding α-Al2O3 to obtain a macroporous support during the molding process and alkylating the catalyst to give the catalyst good activity, selectivity and water resistance.

[0132] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A selective hydrogenation catalyst, characterized in that, The catalyst comprises a support, an active component, and a co-active component, wherein the support is a macroporous alumina molded support, the bulk density of the support is 0.4-0.9 g / mL, and the pore volume is 0.66-0.71 mL / g; The most probable pore size of the carrier is 0.12-0.25 μm; The carrier also contains an auxiliary component, which is selected from one of La, Ce and K; The active component is Pd, and the co-active component is Ag; Based on the total weight of the carrier, the content of the active ingredient is 0.15-10% by weight. The catalyst also includes silane groups grafted onto its surface.

2. The selective hydrogenation catalyst according to claim 1, wherein, For the carrier with a particle size of φ4-6mm, its strength is not less than 30Nm / particle.

3. The selective hydrogenation catalyst according to claim 2, wherein, For the carrier with a particle size of φ4-6mm, its strength is 30-200Nm / particle; And / or, the specific surface area of ​​the carrier is 5-120 m². 2 / g, pore size distribution is 40-280nm, water absorption rate is 45-68%; And / or, based on the total weight of the carrier, the content of the auxiliary component is no more than 2% by weight.

4. The selective hydrogenation catalyst according to claim 3, wherein, Based on the total weight of the carrier, the content of the auxiliary component is 0.05-1.5% by weight.

5. The selective hydrogenation catalyst according to claim 1, wherein, Based on the total weight of the carrier, the content of the active component is 0.01-0.5% by weight.

6. The selective hydrogenation catalyst according to claim 1, wherein, The silane group accounts for 1-20% by weight of the total weight of the catalyst. And / or, the silyl group is provided by a silylating agent.

7. The selective hydrogenation catalyst according to claim 6, wherein, The silylating agent is selected from at least one of methyldiethoxysilane, trimethyldiethoxysilane, ethyltriethoxysilane, diethyldiethoxysilane, triethylethoxysilane, ethyltrimethoxysilane, butyltriethoxysilane, dimethyl-ethylmethoxysilane, dimethyl-phenylethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, dimethyl-propylchlorosilane, dimethylisopropylchlorosilane, tributylchlorosilane, hexamethyldisilazane, heptamethyldisilazane, and tetramethyldisilazane.

8. The selective hydrogenation catalyst according to any one of claims 1-7, wherein, The method for preparing the macroporous alumina molding carrier includes mixing boehmite with α-Al2O3 and molding the resulting mixture, wherein the α-Al2O3 accounts for 5-25% by weight of the total weight of the powder used. The method further includes the step of adding auxiliary component precursors during the molding process; The auxiliary component is selected from one of La, Ce and K.

9. The selective hydrogenation catalyst according to claim 8, wherein, The specific surface area of ​​the pseudoboehmite is 200-300 m². 2 / g, pore volume is 0.5-1.1mL / g, and bulk density does not exceed 0.5g / mL; And / or, the α-Al2O3 is selected from α-Al2O3 powder with a particle size not exceeding 120 μm.

10. The selective hydrogenation catalyst according to claim 9, wherein, The α-Al2O3 accounts for 5-20% of the total weight of the powder used. And / or, the pore volume of the pseudoboehmite is 0.85-0.95 mL / g; And / or, the α-Al2O3 powder has a particle size of 2-110 μm, wherein the content of α-Al2O3 is not less than 95% by weight.

11. The selective hydrogenation catalyst according to claim 10, wherein, In the α-Al2O3 powder, the total content of Na, Fe and Si, calculated by element, does not exceed 0.1% by weight.

12. The selective hydrogenation catalyst according to claim 8, wherein, The forming operation includes kneading, shaping, drying and roasting the mixture in sequence.

13. The selective hydrogenation catalyst according to claim 12, wherein, The drying conditions include: temperature 70-150℃, time 4-24h.

14. The selective hydrogenation catalyst according to claim 12, wherein, The roasting conditions include: temperature 1100-1200℃, time 4-24h.

15. A method for preparing a selective hydrogenation catalyst, characterized in that, The method includes loading an active component and a co-active component onto a support, wherein the support is a macroporous alumina molded support according to any one of claims 1-7 or a support prepared by any one of claims 8-14, wherein the active component is Pd and the co-active component is Ag; The selective hydrogenation catalyst prepared by the method also includes silane groups grafted onto its surface.

16. The method according to claim 15, wherein, The loading method includes loading the active component precursor onto the carrier using spraying and / or impregnation methods.

17. The method according to claim 15, wherein, The method further includes sequentially drying and calcining the catalyst semi-finished product loaded with active and co-active components.

18. The method according to claim 15, wherein, The method further includes the step of grafting silane groups onto the surface of the calcined catalyst.

19. The method according to claim 18, wherein, The grafting of silane groups is selected from gas-phase and / or liquid-phase methods.

20. The method of claim 17, wherein, The drying conditions include a temperature of 70-150℃ and a time of 3-48 hours; And / or, the calcination conditions include a temperature of 350-600°C and a time of 2-10 hours.

21. The method according to claim 18, wherein, The silane group is provided by a silylating agent.

22. The method according to claim 21, wherein, The silylating agent is selected from at least one of methyldiethoxysilane, trimethyldiethoxysilane, ethyltriethoxysilane, diethyldiethoxysilane, triethylethoxysilane, ethyltrimethoxysilane, butyltriethoxysilane, dimethyl-ethylmethoxysilane, dimethyl-phenylethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, dimethyl-propylchlorosilane, dimethylisopropylchlorosilane, tributylchlorosilane, hexamethyldisilazane, heptamethyldisilazane, and tetramethyldisilazane.

23. The application of the selective hydrogenation catalyst according to any one of claims 1-14 or the selective hydrogenation catalyst prepared by the method according to any one of claims 15-22 in the hydrogenation and removal of alkynes from C4 fractions.

24. A method for hydrogenating a C4 fraction, characterized in that, The method comprises: introducing a mixture of C4 fraction feedstock and solvent with H2 into a reactor for selective hydrogenation in the presence of the catalyst described in any one of claims 1-7; Alternatively, the catalyst may be prepared according to any one of claims 15-22, and then, in the presence of the obtained catalyst, a mixture of C4 fraction feedstock and solvent and H2 may be introduced into a reactor for selective hydrogenation.

25. The method according to claim 24, wherein, The solvent is selected from aqueous solutions of N-methylpyrrolidone and / or aqueous solutions of acetonitrile; And / or, the weight ratio of the solvent to the C4 fraction feedstock is 0.1-0.5:1; And / or, the molar ratio of H2 entering the reactor to alkynes in the mixture of C4 fraction feedstock and solvent is 0.5-1:1; And / or, the conditions for the selective hydrogenation reaction include: reactor inlet temperature 40-45°C, reactor pressure 0.08-1.2 MPa, and liquid feed space velocity based on C4 fraction feedstock of 30-50 h⁻¹. -1 .

26. The method of claim 25, wherein, The water content in the solvent does not exceed 10% of the total weight of the solvent.