A C4-alkyne selective hydrogenation catalyst and preparation method thereof

Abstract

The present invention discloses a C4 alkyne selective hydrogenation catalyst and a preparation method thereof. The C4 alkyne selective hydrogenation catalyst comprises: based on the total weight of the catalyst as 100%, 0.1-0.5wt% palladium, 0.1-3.0wt% silver, 0-3wt% cerium and / or lanthanum, and the balance a carrier; the carrier being alumina with a blade-like aggregate structure. The C4 alkyne selective hydrogenation catalyst of the present invention contains active components of palladium and silver, and uses the blade-like aggregate structure of alumina as a carrier. The prepared C4 alkyne selective hydrogenation catalyst has the characteristics of high active metal dispersion, high selectivity, and good stability. It can be used to effectively reduce the alkyne content in the C4 fraction and is suitable for the pre-hydrogenation process of the C4 alkyne selective hydrogenation.

Description

Technical Field

[0001] The present invention relates to a C4 alkyne selective hydrogenation catalyst and a preparation method thereof, and in particular to a catalyst for selective hydrogenation and alkyne removal of cracked mixed C4 fractions and a preparation method thereof. Background Art

[0002] Butadiene is an important petrochemical raw material and plays a crucial role among petrochemical olefin feedstocks. Butadiene can be copolymerized with a variety of compounds to produce synthetic rubbers and synthetic resins, such as cis-1,4-butadiene rubber (BUR), styrene-butadiene rubber (SBR), ABS engineering plastics, styrene-butadiene thermoplastic elastomers (SBCs), acrylonitrile-butadiene rubber (NBR), chloroprene rubber, and adiponitrile, the raw material for nylon 6,6. Currently, the primary process for butadiene production is the extraction of the C4 fraction, a by-product of hydrocarbon cracking to produce ethylene. This extraction process produces a large amount of C4 alkyne tail gas rich in ethylacetylene, vinylacetylene, and propyne. This high alkyne content in tail gas is prone to fire and explosion, posing a safety hazard. Using large amounts of butene and butane to dilute the alkynes to a safe level, which is then flared or sold at a low price, results in significant economic losses and environmental pollution. Hydrogenation technology, which can convert alkyne-containing feedstock into butadiene, butenes, and butane, is a key way to increase the added value of butadiene plants. Among these, the economic benefits of selective hydrogenation of C4 alkynes to butadiene are even more substantial, and this technology will become a major future research direction in the field. With the increasing depth of ethylene cracking in my country, the content of alkynes in the cracked C4 mixture has increased significantly. This increase in alkyne content, coupled with the increasing demand for butadiene purity in downstream processes, has significantly increased the operating difficulty and energy consumption of the secondary extraction system in butadiene extraction units, and also increased butadiene losses.

[0003] The selective hydrogenation of C4 alkynes to recover butadiene includes three process routes: pre-hydrogenation, post-hydrogenation, and mixed hydrogenation. Pre-hydrogenation involves adding an alkyne hydrogenation process prior to the traditional butadiene extraction process, hydrogenating the alkynes in the mixed C4 to meet the alkyne content requirements for the butadiene product. This pre-hydrogenation process eliminates the need for a secondary extraction and distillation system, simplifying the production process and reducing energy consumption. However, butadiene losses typically exceed 2%, placing higher demands on catalyst selectivity.

[0004] Chinese patent CN102249838A discloses a method and supported palladium catalyst for the selective hydrogenation of alkynes in a C4 hydrocarbon stream. The method utilizes ionizing radiation and the addition of a free radical cleaning agent during catalyst preparation to control the crystallographic state of the palladium sites, thereby enhancing alkyne selectivity. The selectivity can reach as high as 74.11%. However, the invention does not provide detailed information on the catalyst's long-term operational stability.

[0005] Chinese patent CN102886262A relates to a catalyst for the selective hydrogenation of C4 alkynes. This catalyst uses a Ni-Cu bimetallic active component, with a Ni content of 10-20% and a Cu content of 3-10%, supported by alumina. The catalyst achieves selectivities of 90% for EA (butyne) and 84.1% for VA (vinyl acetylene). However, the hydrogenation process results in high butadiene losses, with the butadiene content decreasing by 67.5% over the entire reaction, limiting its industrial application.

[0006] Chinese patent CN106552647B discloses a catalyst preparation method involving mixing a copper-aluminum alloy with a solution containing caustic alkali to produce a Raney copper catalyst; the Raney copper catalyst is then contacted with a solution containing silver ions to produce a silver-modified Raney copper catalyst. This catalyst exhibits high selectivity and catalytic efficiency, and significantly increases the reaction space velocity during selective hydrogenation of C4 fractions to remove alkynes. However, the catalyst preparation process is complex, and the catalyst activity is somewhat limited.

[0007] Chinese patent CN103418378B relates to a catalyst for selective hydrogenation and removal of acetylenes from C4 fractions and its preparation method. The catalyst is supported by alumina and contains Pd as the primary active component, with Fe, Ni, and La as co-active components. The catalyst is simple to prepare, exhibits high hydrogenation and removal of acetylenes activity, a high reaction volumetric space velocity, and a long regeneration cycle. However, the catalyst suffers from suboptimal selectivity and a high butadiene loss rate during the hydrogenation process.

[0008] Chinese patent CN102463117B relates to a catalyst for the selective hydrogenation of alkynes and its preparation method. The catalyst uses a titanium oxide-alumina composite oxide support, with Cu as the primary active component and Co, a lanthanide metal, Ni, and Zn as co-active components. While the catalyst exhibits excellent selectivity and strong resistance to poisoning, its long-term operational stability needs improvement, making it difficult to meet the needs of industrial applications.

[0009] Chinese patent CN103170349B discloses a copper catalyst and preparation method for the selective hydrogenation of mixed C4 alkynes. The catalyst uses alumina as a carrier, and an organic amine is added during the catalyst preparation process to complex the metal components, improving the uniformity and dispersibility of the alloy formed on the catalyst surface. While the catalyst exhibits good selectivity for the mixed C4 hydrogenation of alkynes, copper-based catalysts still suffer from a relatively short single-cycle cycle, and the organic amine added during the catalyst preparation process may cause some environmental pollution.

[0010] Chinese patent CN201911000611.5 discloses a catalyst and preparation method for the selective hydrogenation of C4 alkynes to butadiene. The catalyst uses a ZrO2 / CdO / Bi2O3 composite carrier, with Pd as the main active component and Group VIIB metals and La as auxiliary active components. The catalyst has good selectivity and stability, but the catalyst carrier preparation process is complex and the catalyst preparation cycle is long, which limits its industrial application.

[0011] The micromorphology and surface properties of alumina significantly influence the performance of supported catalysts, and therefore the controllable synthesis of alumina morphology and size has attracted considerable research interest. Currently, researchers have used various methods to prepare alumina morphologies, primarily in the form of flakes, rods, and spheres. Nano-flake alumina possesses a large surface area and high surface energy, resulting in high dispersibility of the active metals in the catalyst. It also exhibits a high diffusion rate for reactants, significantly reducing diffusion resistance. Therefore, its use as a support can significantly enhance catalyst activity and carbon deposition resistance, demonstrating superior performance compared to traditional alumina. Currently, research on flake alumina primarily focuses on the synthesis of micron-sized flakes, primarily for the preparation of flake alumina ceramics. The synthesis of nano-flake alumina, often developed using surfactants as templates, is costly and prone to agglomeration during high-temperature calcination, limiting its industrialization.

[0012] Chinese patent CN201710944136.1 discloses a method for preparing a nano-alumina carrier with a surface rich in defect sites: the steps are as follows: (1) dissolving an inorganic aluminum salt and a precipitant in a water-ethylene glycol mixed solvent at a molar ratio of 1:5 to 1:9, stirring to obtain a transparent solution, and transferring the solution to a hydrothermal reactor; the hydrothermal reaction temperature is 100 to 200°C, and the reaction time is 12 to 48 hours; (2) after the reaction is completed, the reaction material is filtered, washed, dried, and calcined to obtain a nano-alumina carrier rich in surface defects, whose specific surface area is 150 to 400 m 2 / g, pore volume is 0.34~0.62cm 3 However, the ethylene glycol in the mixed solvent is easily hydrothermally oxidized to generate toxic oxalic acid, so it cannot be widely used as a solvent, which is not conducive to promotion.

[0013] Chinese patent CN201210427889.2 discloses a method for preparing an alumina carrier, comprising the following steps: measuring an appropriate amount of an aluminum salt solution with a concentration of 0.5-2.5 mol / L, adding an appropriate amount of urea to the aluminum salt solution and stirring to completely dissolve it, wherein the amount of urea added is the ratio of urea to Al 3+The molar ratio of the alumina support is 2-10:1; the solution is placed in a sealed reaction vessel, reacted at 140°C-200°C for 2-12 hours, and then directly calcined to produce the alumina support. Although the support prepared by this method has a high specific surface area and a large pore size, the material obtained after the reaction is not filtered or washed, but directly dried and calcined to produce the alumina support. This results in a high content of amorphous alumina and a dispersed pore distribution in the alumina support, limiting its further application.

[0014] Chinese patent CN201110351132.5 provides a method for preparing porous alumina ultrafine powder by an improved hydrothermal method. Aluminum inorganic salt is used as raw material and urea is used as a coprecipitant. A precursor is generated under hydrothermal conditions, and then centrifuged, washed, dried, and calcined to obtain porous alumina ultrafine powder with high purity, narrow particle size distribution, and high porosity.

[0015] Chinese patent CN107540007A discloses a method for preparing nano-flaky mesoporous alumina: using inorganic aluminum salt as an aluminum source, triethanolamine as an additive, and ethylenediamine as a precipitant, a hydrothermal aging treatment is performed to obtain nano-flaky mesoporous alumina. The nano-flaky alumina sheet has a thickness of 1-10 nm and a width of 0.1-0.5 μm.

[0016] Chinese patent CN107777713A discloses a hexagonal γ-alumina nanosheet material and its preparation method. The nanosheets are 50-500 nm in size and 5-10 nm thick. The invention uses aluminum alkoxide as a raw material, controls the two-dimensional growth of the intermediate aluminum oxyhydroxide with an organic amine, and employs chemical precipitation and hydrothermal methods to produce the γ-alumina hexagonal nanosheets.

[0017] Chinese patent CN104961146A discloses a nano-flaky aluminum hydroxide colloid and a preparation method thereof, wherein anhydrous ethanol and anhydrous aluminum chloride are directly hydrothermally heated at 220-300°C to obtain a nano-flaky gel with a thickness of 3-20 nm.

[0018] Chinese patent CN106276992A discloses a method for preparing leaf-shaped nano-γ-alumina. Inorganic aluminum salt and urea are dissolved in water to obtain a transparent solution, the solution is transferred to an autoclave, and then hydrogen is introduced into the autoclave to maintain a certain pressure and temperature for reaction to obtain leaf-shaped nano-γ-alumina. However, the leaflets are in a dispersed state and have no accumulation. They are prone to agglomeration during high-temperature calcination. When used as a catalyst support to load active metals, this will reduce the dispersion of the active metals on the support surface. In addition, the use of relatively dangerous hydrogen in the preparation process is not conducive to production safety.

[0019] Li Jinlin et al.'s article "Controllable Synthesis and Characterization of γ-Al2O3 Nanocrystals with Specific Morphology, Journal of South-Central University for Nationalities (Natural Science Edition), 2016, 35: 1-4" used acetic acid and isopropanol as raw materials and hydrothermally prepared aluminum oxide with a sheet length of 60-100 nanometers at 200℃, whose main exposed crystal face is (110) crystal face. Yuguo Xia et al.'s article "Synthesis of AlOOHnanocrystals with different morphologies due to the effect of sulfate ionsand thecorresponding formation mechanism study, Phys.Chem.Chem.Phys., 2013, 15, 18290" used nano-AlOOH as raw material, added sodium sulfate and sulfuric acid, and hydrothermally treated at 200℃ for 24 hours to obtain nano-sheet aluminum oxide with a size of 60 to 100 nm. The aluminum oxide prepared by this method has a small specific surface area (<100m 2 / g), and dilute acid is used in the preparation process. The high-temperature hydrothermal process has high requirements on the kettle material, which is not conducive to large-scale production. Summary of the Invention

[0020] The present invention aims to provide a C4 alkyne selective hydrogenation catalyst and a preparation method thereof. The C4 alkyne selective hydrogenation catalyst contains active components of palladium and silver and uses a blade-shaped aggregate structured alumina as a carrier. The prepared C4 alkyne selective hydrogenation catalyst has the characteristics of high active metal dispersion, high selectivity, and good stability. It can be used to effectively reduce the alkyne content in a C4 fraction and is suitable for a pre-hydrogenation process for the selective hydrogenation of C4 alkynes.

[0021] To achieve the above-mentioned object, the present invention provides a C4 alkyne selective hydrogenation catalyst, wherein the C4 alkyne selective hydrogenation catalyst has a carrier alumina having a blade-shaped aggregate structure, comprising: based on the total weight of the catalyst as 100%, 0.1-0.5wt% of palladium, 0.1-3.0wt% of silver, 0-3.0wt% of cerium and / or lanthanum, and the balance being the alumina carrier; the specific surface area of ​​the catalyst is 50-150m 2 / g, and a pore volume of 0.3-0.6 mL / g; the carrier alumina is prepared by a hydrothermal synthesis method.

[0022] The carbon tetraacetylene selective hydrogenation catalyst of the present invention, wherein the carrier is prepared by the following method:

[0023] Step (1): adding a compound that can be decomposed into NH3 and CO2 in the subsequent hydrothermal treatment in step (2) to an inorganic aluminum salt aqueous solution, stirring until completely dissolved to form a mixed solution;

[0024] Step (2): CO2 gas at a pressure of 0.1 to 2.0 MPa is introduced into the mixed solution, followed by hydrothermal treatment. The obtained product is filtered to separate the solid and liquid, and the obtained solid is washed, dried and calcined to obtain alumina with a leaf-like aggregate structure.

[0025] The selective hydrogenation catalyst for carbon tetraacetylene of the present invention is as follows: in step (2), the mixed solution is introduced into a hydrothermal kettle or an autoclave with a pressure of 0.2 to 1.0 MPa of CO2 gas, and then subjected to hydrothermal treatment.

[0026] In the selective hydrogenation catalyst for carbon tetraacetylene of the present invention, the compound that can be decomposed into CO2 and NH3 in the subsequent hydrothermal treatment in step (1) is one or more selected from ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

[0027] The selective hydrogenation catalyst for carbon tetraacetylene of the present invention comprises the following steps: in step (1), the amount of the compound that can be decomposed into CO2 and NH3 in the subsequent hydrothermal treatment is added; and the molar ratio of the aluminum ion of the inorganic aluminum salt to the compound is 0.1 to 4.0, preferably 0.5 to 3.0.

[0028] In the selective hydrogenation catalyst for carbon tetraacetylene of the present invention, the inorganic aluminum salt in step (1) can be one or more of aluminum sulfate, aluminum nitrate and aluminum chloride.

[0029] In the present invention, the hydrothermal treatment of the carbon tetraacetylene selective hydrogenation catalyst in step (2) can adopt conventional process conditions in the art. The process conditions recommended by the present invention are: hydrothermal temperature of 100-300°C, hydrothermal treatment of 2-48 hours; preferably, the hydrothermal temperature is 120-200°C, the hydrothermal time is 4-24 hours, the roasting temperature is 620-1050°C, the roasting time is 3-10 hours, and preferably, the roasting temperature is 700-1000°C, and the roasting time is 4-6 hours.

[0030] Before forming the carrier of the present invention, one or more of a peptizing agent, an extrusion aid, and alumina dry glue powder can be added as needed. The specific substances used and the amounts added can be determined according to existing knowledge in the art. For example, the peptizing agent can be one or more of nitric acid, phosphoric acid, hydrochloric acid, and sulfuric acid, and the amount added is 3-10 wt% of the total weight of the sample to be formed. The extrusion aid can be sesbania powder, etc., and the amount used is generally 2-6 wt% of the total weight of the sample to be formed. The alumina dry glue powder is prepared using conventional methods, but the amount added is preferably less than 10 wt% of the total mass of the carrier to be formed.

[0031] The calcination method and conditions are commonly used for calcining catalyst supports. Vertical furnaces, converters, and mesh belt kilns can be used for calcination. The shaped support is calcined at a temperature of 620-1050°C for 3-10 hours, preferably 700-1000°C for 4-6 hours. The intermediate transition calcination temperature is 300-600°C for 3-10 hours, and the catalyst calcination temperature is 300-550°C for 3-8 hours. The calcination temperature of the support is the temperature used before impregnation with the active components Pd and Ag to ensure the specific surface area and pore volume required by the catalyst. Prior to calcination at this temperature, the support may be prepared by low-temperature calcination, but these steps are all intermediate transition calcination steps.

[0032] The selective hydrogenation catalyst for carbon tetraacetylene of the present invention contains, based on the total weight of the catalyst as 100%, preferably 0.2 to 0.4 wt% of palladium, preferably 0.3 to 2.5 wt% of silver, and preferably 0.1 to 1.5 wt% of cerium and / or lanthanum; the specific surface area of ​​the catalyst is 50 to 150 m 2 / g, and the pore volume is 0.3~0.6mL / g.

[0033] In the selective hydrogenation catalyst for carbon tetraacetylene of the present invention, the palladium, silver, cerium, and / or lanthanum are added in the form of soluble compounds. The soluble palladium compound is selected from at least one of palladium chloride, palladium nitrate, and palladium acetate, and the soluble silver compound is preferably silver nitrate. In the present invention, the cerium and / or lanthanum are preferably added in the form of soluble nitrates. The addition of cerium and / or lanthanum can inhibit grain growth of the catalyst support during high-temperature calcination, improve the dispersion of the active components, and enhance the hydrogenation selectivity and stability of the catalyst.

[0034] The rare earth elements cerium and / or lanthanum can be added during the support forming process; can also be added to the support after the support is formed and before the active component is impregnated; can also be added simultaneously with the active component impregnation solution when the active component is impregnated; can also be added after the active component is impregnated.

[0035] The carbon tetraacetylene selective hydrogenation catalyst of the present invention is preferably reduced with hydrogen at 300-450° C. for 6-16 hours before use.

[0036] The present invention also provides a method for preparing the above-mentioned C4 alkyne selective hydrogenation catalyst, but the preparation method of the present invention is not limited thereto. The preparation method of the present invention preferably comprises the following steps:

[0037] After adjusting the pH of a solution containing soluble compounds of palladium and silver to 1.0-5.0, the catalyst is impregnated with a carrier in one or more steps, dried, and calcined at 300-600° C. for 3-8 hours to obtain a C4-acetylene selective hydrogenation catalyst; the carrier is aluminum oxide with a blade-like aggregate structure.

[0038] The alumina used in the catalyst of the present invention has a blade-like aggregate structure, characterized by a regular morphology, uniform particles, high crystallinity and thermal stability. Its blade-like aggregate structure overcomes the shortcomings of conventional nano-flaky alumina products, which are difficult to separate and easily agglomerate at high temperatures. The alumina with the blade-like aggregate structure of the present invention is simple to separate, does not agglomerate upon high-temperature calcination, and can continue to maintain its nano-flaky morphology, making it suitable for use as an excellent catalyst carrier in catalytic hydrogenation reactions. The present invention introduces CO2 gas during the preparation process, which effectively neutralizes the number of surface hydroxyl groups on the alumina blades during the alumina crystallization process. This reduces the curling of the alumina blades caused by hydroxyl condensation during the crystallization process and effectively controls the width of the alumina blades. Furthermore, it reduces the saturation of the coordination between hydroxyl groups and aluminum ions, making the flaky alumina more conducive to chelating and coordinating with active metals. Furthermore, the present invention utilizes a relatively high molar ratio of aluminum ions to compounds. This high molar ratio is beneficial for increasing the yield per kettle, effectively reducing production costs.

[0039] The inventors of the present invention have discovered that by regulating the microstructure of the active phases palladium and silver, and their interaction with the blade-like aggregate structure of the alumina support, it is possible to achieve differentiated regulation of the adsorption capacity of C4 alkynes and butadiene, balancing the activity and selectivity of the catalyst, making it suitable for pre-hydrogenation processes for the selective hydrogenation of C4 alkynes. Furthermore, by adding a suitable co-active component, a synergistic effect is formed with the main active component palladium, improving the catalyst's selectivity while reducing the interaction between the acetylenic bond and the palladium atom, thereby reducing the loss of the active component palladium, improving the catalyst's stability, and extending its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is an SEM image of the aluminum oxide with blade-like aggregate structure obtained in Example 1 of the present invention.

[0041] Figure 2 This is the SEM image of the aluminum oxide of Comparative Example 1. DETAILED DESCRIPTION

[0042] The present invention is described in detail below through examples. The examples are only used to further illustrate the present invention and should not be understood as limiting the scope of protection of the present invention. Personnel in this field can make corresponding non-essential improvements and adjustments based on the above content of the present invention.

[0043] Example 1

[0044] (1) Vector preparation

[0045] Aluminum sulfate and ammonium carbonate (a molar ratio of aluminum ion to ammonium carbonate of 2.5) were added to deionized water, stirred to dissolve, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 1.5 MPa and reacted in the reactor at 160°C for 10 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was extruded into strips, dried at 120°C for 4 hours, and calcined at 900°C for 4 hours to obtain an alumina support with a blade-like aggregate structure.

[0046] (2) Catalyst preparation

[0047] Weigh 100 g of the support prepared in (1), accurately weigh palladium chloride, silver nitrate, and lanthanum nitrate in amounts such that the final catalyst contains 0.2% palladium, 1.0% silver, and 0.2% lanthanum. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 2.5 with sodium carbonate. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 400°C for 3 hours to obtain Catalyst C1.

[0048] Example 2

[0049] (1) Vector preparation

[0050] Aluminum nitrate and urea (a molar ratio of aluminum ion to urea of ​​1.5) were added to deionized water, stirred to dissolve, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 1.8 MPa and reacted in the reactor at 200°C for 6 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was then extruded into strips, dried at 120°C for 4 hours, and calcined at 850°C for 6 hours to obtain an alumina support with a blade-like aggregate structure.

[0051] (2) Catalyst preparation

[0052] Weigh 100 g of the support prepared in (1), accurately weigh palladium nitrate, silver nitrate, and cerium nitrate in amounts such that the final catalyst contains 0.1% palladium, 0.5% silver, and 0.1% cerium. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 3.0 with ammonia water. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 350°C for 5 hours to obtain Catalyst C2.

[0053] Example 3

[0054] (1) Vector preparation

[0055] Aluminum sulfate and ammonium bicarbonate (a molar ratio of aluminum ion to ammonium bicarbonate of 2.0) were added to deionized water, stirred to dissolve, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 1.0 MPa and reacted at 180°C for 8 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was extruded into strips, dried at 120°C for 4 hours, and calcined at 880°C for 5 hours to obtain an alumina support with a blade-like aggregate structure.

[0056] (2) Catalyst preparation

[0057] Weigh 100 g of the support prepared in (1), accurately weigh palladium chloride, silver nitrate, and lanthanum nitrate in amounts such that the final catalyst contains 0.4% palladium, 1.2% silver, and 0.8% lanthanum. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 2.0 with sodium bicarbonate. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 450°C for 4 hours to obtain Catalyst C3.

[0058] Example 4

[0059] (1) Vector preparation

[0060] Aluminum chloride and ammonium oxalate (a molar ratio of aluminum ion to ammonium oxalate of 3.5) were added to deionized water, stirred to dissolve, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 0.5 MPa and reacted in the reactor at 120°C for 4 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was extruded into strips, dried at 120°C for 4 hours, and calcined at 790°C for 8 hours to obtain an alumina support with a blade-like aggregate structure.

[0061] (2) Catalyst preparation

[0062] Weigh 100 g of the support prepared in (1), accurately weigh palladium acetate, silver nitrate, and lanthanum nitrate in amounts such that the final catalyst contains 0.2% palladium, 2.0% silver, and 1.0% lanthanum. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 1.5 with sodium bicarbonate. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 500°C for 6 hours to obtain catalyst C4.

[0063] Example 5

[0064] (1) Vector preparation

[0065] Aluminum nitrate and ammonium carbonate (a molar ratio of aluminum ion to ammonium carbonate of 4.0) were added to deionized water, stirred to dissolve, and then transferred to a hydrothermal reactor. CO₂ gas was introduced to 0.2 MPa and reacted in the reactor at 240°C for 24 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was extruded into strips, dried at 120°C for 4 hours, and calcined at 950°C for 9 hours to obtain an alumina support with a blade-like aggregate structure.

[0066] (2) Catalyst preparation

[0067] Weigh 100 g of the support prepared in (1), accurately weigh palladium nitrate, silver nitrate, and cerium nitrate in amounts such that the final catalyst contains 0.3% palladium, 3.0% silver, and 1.5% cerium. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 4.0 with ammonia water. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 600°C for 8 hours to obtain Catalyst C5.

[0068] Example 6

[0069] (1) Vector preparation

[0070] Aluminum chloride and urea (aluminum ion:urea molar ratio of 0.1) were added to deionized water, stirred and dissolved, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 2.0 MPa and reacted in the hydrothermal reactor at 300°C for 30 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and a lanthanum nitrate aqueous solution (the amount of lanthanum nitrate was such that the final catalyst contained 2.5% lanthanum) and kneaded into a plastic. The mixture was then extruded into strips, dried at 120°C for 4 hours, and calcined at 1020°C for 3 hours to obtain a lanthanum-containing alumina carrier with a blade-like aggregate structure.

[0071] (2) Catalyst preparation

[0072] Weigh 100 g of the support prepared in (1), accurately weigh palladium chloride, silver nitrate, and lanthanum nitrate in amounts such that the final catalyst contains 0.5% palladium, 0.1% silver, and 2.5% lanthanum. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 5.0 with sodium carbonate. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 300°C for 5 hours to obtain Catalyst C6.

[0073] Example 7

[0074] (1) Vector preparation

[0075] Aluminum sulfate and ammonium oxalate (a molar ratio of aluminum ion to ammonium carbonate of 3.0) were added to deionized water, stirred to dissolve, and then transferred to a hydrothermal reactor. CO₂ gas was introduced to 1.2 MPa. The reaction was carried out at 220°C for 42 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was then extruded into strips, dried at 120°C for 4 hours, and calcined at 1000°C for 7 hours to obtain an alumina support with a blade-like aggregate structure.

[0076] (2) Catalyst preparation

[0077] Weigh 100 g of the support prepared in (1), accurately weigh palladium acetate and silver nitrate in amounts such that the final catalyst contains 0.3% palladium and 2.5% silver, and dissolve in deionized water until the volume of the resulting impregnation solution is equal to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 1.0 with aqueous ammonia. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 550°C for 7 hours to obtain a semi-finished catalyst.

[0078] Accurately weigh lanthanum nitrate and cerium nitrate in amounts such that the final catalyst contains 2.0% lanthanum and 1.0% cerium. Add deionized water to dissolve the resulting impregnation solution so that the volume reaches the saturated water absorption capacity of the semi-finished catalyst. Use the equal volume impregnation method to impregnate the semi-finished catalyst, dry at 120°C, and calcine at 550°C for 4 hours to obtain catalyst C7.

[0079] Example 8

[0080] (1) Vector preparation

[0081] Aluminum nitrate, aluminum sulfate (aluminum nitrate to aluminum sulfate molar ratio of 1.5), and ammonium bicarbonate (aluminum ion to ammonium bicarbonate molar ratio of 0.5) were added to deionized water, stirred and dissolved, and then transferred to a hydrothermal kettle. CO2 gas was introduced to 0.1 MPa and reacted in the kettle at 100°C for 48 hours. After cooling to room temperature, the precipitate was filtered, separated, washed, and dried. The resulting product was mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product was extruded into strips, dried at 120°C for 4 hours, and calcined at 980°C for 5 hours to obtain an alumina support with a blade-like aggregate structure.

[0082] (2) Catalyst preparation

[0083] Weigh 100 g of the support prepared in (1), accurately weigh palladium nitrate and silver nitrate in amounts such that the final catalyst contains 0.1% palladium and 1.8% silver. Add deionized water to dissolve the resulting impregnation solution to the saturated water absorption capacity of the alumina support. Adjust the pH of the impregnation solution to 3.5 with sodium carbonate. Impregnate the catalyst support using the equal volume impregnation method, dry at 120°C, and calcine at 320°C for 4 hours to obtain Catalyst C8.

[0084] Example 9

[0085] (1) Vector preparation

[0086] Aluminum chloride, ammonium carbonate, and urea (the molar ratio of aluminum ion to ammonium carbonate and urea is 1.0, and the molar ratio of ammonium carbonate to urea is 2.0) are added to deionized water, stirred and dissolved, and then transferred to a hydrothermal reactor. CO2 gas is introduced to 0.8 MPa and the reaction is carried out at 280°C for 2 hours. After cooling to room temperature, the precipitate is filtered, separated, washed, and dried. The resulting product is mixed with nitric acid, phosphoric acid, sesbania powder, and water to form a plastic. The product is then extruded into strips, dried at 120°C for 4 hours, and calcined at 920°C for 10 hours to obtain an alumina support with a leaf-like aggregate structure.

[0087] (2) Catalyst preparation

[0088] Weigh 100 g of the carrier prepared in (1), accurately weigh lanthanum nitrate and cerium nitrate in amounts such that the final catalyst contains 0.5% lanthanum and 1.0% cerium, add deionized water to dissolve the resulting impregnation solution so that the volume is the saturated water absorption capacity of the alumina carrier, and impregnate the catalyst carrier using the equal volume impregnation method. Dry at 120°C and calcine at 580°C for 4 hours to obtain a carrier containing lanthanum and cerium.

[0089] Accurately weigh palladium acetate and silver nitrate to achieve a final catalyst content of 0.4% palladium and 2.8% silver. Dissolve in deionized water until the resulting impregnation solution reaches the saturated water absorption capacity of the lanthanum- and cerium-containing alumina support. Adjust the pH of the impregnation solution to 4.5 with sodium bicarbonate. Impregnate the lanthanum- and cerium-containing catalyst support using an equal volume impregnation method. Dry at 120°C and calcine at 580°C for 6 hours to produce Catalyst C9.

[0090] Comparative Example 1

[0091] (1) Vector preparation

[0092] The industrial pseudo-boehmite prepared by commercial carbonization method was mixed with nitric acid, phosphoric acid, sesbania powder and water to form a plastic body, extruded into strips, and then dried at 120℃ for 4h and calcined at 900℃ for 4h to obtain an alumina carrier. The structure of the alumina carrier is as follows: Figure 2 As shown, the alumina support does not have a blade-like aggregate structure.

[0093] (2) Catalyst preparation

[0094] 100 g of the carrier prepared in (1) was weighed and the catalyst D1 was prepared using the same preparation method as in Example 1.

[0095] Comparative Example 2

[0096] (1) Vector preparation

[0097] Industrial pseudo-boehmite prepared by the commercial nitric acid method is mixed with nitric acid, phosphoric acid, sesbania powder and water to form a plastic body, extruded into strips, and then dried at 120°C for 4 hours and calcined at 850°C for 6 hours to obtain an alumina carrier that does not have a blade-like aggregate structure.

[0098] (2) Catalyst preparation

[0099] 100 g of the carrier prepared in (1) was weighed and the catalyst D2 was prepared using the same preparation method as in Example 2.

[0100] Comparative Example 3

[0101] (1) Vector preparation

[0102] Industrial pseudo-boehmite prepared by the commercial aluminum sulfate method is mixed with nitric acid, phosphoric acid, sesbania powder and water to form a plastic body, extruded into strips, and then dried at 120°C for 4 hours and calcined at 880°C for 5 hours to obtain an alumina carrier, which does not have a leaf-like aggregate structure.

[0103] (2) Catalyst preparation

[0104] 100 g of the carrier prepared in (1) was weighed and the catalyst D3 was prepared using the same preparation method as in Example 3.

[0105] Table 1 Physical properties and compositions of catalysts in Examples and Comparative Examples

[0106] Sample number <![CDATA[Specific surface area m 2 / g]]> Pore ​​volume mL / g Palladium wt% Silver wt% Lanthanum wt% Cerium wt% C1 103 0.41 0.2 1 0.2 0 C2 122 0.46 0.1 0.5 0 0.1 C3 110 0.42 0.4 1.2 0.8 0 C4 143 0.53 0.2 2.0 1.0 0 C5 82 0.38 0.3 3.0 0 1.5 C6 53 0.35 0.5 0.1 2.5 0 C7 65 0.36 0.3 2.5 2.0 1.0 C8 72 0.36 0.1 1.8 0 0 C9 91 0.39 0.4 2.8 0.5 1.0 D1 97 0.40 0.2 1.0 0.2 0 D2 113 0.45 0.1 0.5 0 0.1 D3 102 0.39 0.4 1.2 0.8 0

[0107] Example 10

[0108] Characterization of catalyst active metal dispersion:

[0109] The dispersion of the active metal components in the catalyst was determined by hydrogen-oxygen titration using a Micromeritics Autochem 2920 chemisorption instrument. Accurately weigh 0.5 g of catalyst sample and place it in the sample tube of the chemisorption instrument. Catalyst pretreatment: Set the instrument temperature, introduce high-purity argon, heat the sample to 200°C, purge the pipeline and sample tube for 60 minutes, and then cool to 30°C. Catalyst reduction: Introduce 5% H2-Ar at 5°C / min, raise the temperature to 400°C, maintain for 60 minutes, and then cool to 30°C. Purge: Introduce argon at 30°C for 60 minutes to fully purge any hydrogen physically adsorbed on the catalyst. Oxygen adsorption: Introduce 5% O2-Ar for 60 minutes. Hydrogen titration: Titrate 5% H2-Ar using a LOOP (5 mL volume) injection method. Once the peak height stabilizes, detect using a TCD detector. The metal dispersion determination results are shown in Table 2.

[0110] Table 2 Metal dispersion of Example catalyst and Comparative Example catalyst

[0111] catalyst Metal dispersion C1 27.3％ C2 29.1％ C3 28.6％ C4 27.2％ C5 25.4％ C6 26.9％ C7 25.1％ C8 28.4％ C9 26.0％ D1 22.9％ D2 24.5％ D3 22.3％

[0112] Example 11

[0113] Catalytic performance of catalyst:

[0114] Catalyst evaluation conditions: A fixed-bed reactor was used, operating isothermally, with a catalyst loading volume of 50 mL. The catalyst was reduced at 130°C for 6 h under a H2 atmosphere. The reaction temperature was 50°C, the reaction pressure was 1.0 MPa, the molar ratio of hydrogen to alkyne in the feed was 3, and the liquid space velocity of the feed was 4 h. -1 The composition of the hydrogenated product was analyzed by gas chromatography. The composition of the C4 feedstock used for catalyst evaluation is shown in Table 3, and the activity and selectivity evaluation results of each catalyst are shown in Table 4.

[0115] Raw materials and product composition: The composition of industrial cracked carbon four was determined using SH-T 1141 analysis.

[0116]

[0117]

[0118] Table 3 Composition of C4 raw materials

[0119] Components Mass fraction / % Isobutane 0.51 n-butane 1.62 trans-2-butene 5.25 1-Butene 21.31 Isobutylene 14.23 cis-2-butene 4.02 1,2-Butadiene 0.12 1,3-Butadiene 51.32 Vinyl acetylene (VA) 0.81 Ethylacetylene (EA) 0.17

[0120] Table 4 Catalyst evaluation results

[0121]

[0122] From the above results, it can be seen that the C4 alkyne selective hydrogenation catalyst prepared by the present invention contains active components palladium and silver and uses blade-shaped aggregate structure alumina as a carrier. Compared with the comparative example, it is refined and has the characteristics of higher active metal dispersion, high selectivity and good stability. It can be used to effectively reduce the alkyne content in the C4 fraction and is suitable for the hydrogenation process before the selective hydrogenation of C4 alkynes.

[0123] Of course, the present invention may have many other embodiments and variations thereof. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and variations based on the present invention, but these corresponding changes and variations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A catalyst for selective hydrogenation of carbon tetraalkynes, characterized in that: The carrier alumina has a blade-like aggregate structure and contains 0.1-0.5wt% palladium, 0.1-3.0wt% silver, 0-3.0wt% cerium and / or lanthanum, and the remainder is the carrier alumina. The specific surface area of ​​the catalyst is 50-150m 2 / g, pore volume is 0.3~0.6mL / g; The carrier alumina is prepared by a hydrothermal synthesis method, and the carrier alumina is prepared by the following method: Step (1): adding a compound that can be decomposed into NH3 and CO2 in the subsequent hydrothermal treatment in step (2) to an inorganic aluminum salt aqueous solution, stirring until completely dissolved to form a mixed solution; Step (2): CO2 gas at a pressure of 0.1 to 2.0 MPa is introduced into the mixed solution, followed by hydrothermal treatment. The obtained product is filtered for solid-liquid separation, and the obtained solid is washed, dried and calcined to obtain alumina with a leaf-like aggregate structure.

2. The selective hydrogenation catalyst for carbon tetraalkynes according to claim 1, wherein In step (2), the mixed solution is introduced into a CO2 gas at a pressure of 0.2 to 1.0 MPa in an autoclave, and then subjected to a hydrothermal treatment.

3. The selective hydrogenation catalyst for carbon tetraalkynes according to claim 1, wherein In step (1), the compound that can be decomposed into CO2 and NH3 in the subsequent hydrothermal treatment is one or more selected from ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate; in step (1), for the amount of compound added that can be decomposed into CO2 and NH3 in the subsequent hydrothermal treatment, the molar ratio of aluminum ions of the inorganic aluminum salt to the compound is 0.1 to 4.0; in step (1), the inorganic aluminum salt is one or more of aluminum sulfate, aluminum nitrate and aluminum chloride.

4. The selective hydrogenation catalyst for carbon tetraalkynes according to claim 3, characterized in that In step (1), for the amount of compound added that can be decomposed into CO2 and NH3 in the subsequent hydrothermal treatment, the molar ratio of the aluminum ion of the inorganic aluminum salt to the compound is 0.5 to 3.

0.

5. The C4 alkyne selective hydrogenation catalyst according to claim 1, characterized in that In step (2), the hydrothermal temperature of the hydrothermal treatment is 100-300° C., and the hydrothermal treatment is performed for 2-48 hours; the roasting temperature is 620-1050° C., and the roasting time is 3-10 hours.

6. The C4 alkyne selective hydrogenation catalyst according to claim 1, characterized in that In step (2), one or more of a peptizing agent, an extrusion aid and alumina dry glue powder need to be added; the amount of the peptizing agent added is 3-10 wt% of the weight of the carrier alumina; the amount of the extrusion aid added is 2-6 wt% of the weight of the carrier alumina; and the amount of the alumina dry glue powder added is 10 wt% of the weight of the carrier alumina.

7. The catalyst for selective hydrogenation of C4 alkynes according to claim 1, wherein Based on 100% of the total weight of the catalyst, the catalyst contains 0.2-0.4wt% of palladium, 0.3-2.5wt% of silver, and 0.1-1.5wt% of cerium and / or lanthanum.

8. The C4 alkyne selective hydrogenation catalyst according to claim 1, characterized in that The palladium and silver are added in the form of soluble compounds, the soluble compound of palladium is selected from at least one of palladium chloride, palladium nitrate and palladium acetate, and the soluble compound of silver is silver nitrate; the cerium and / or lanthanum are added in the form of soluble nitrates.

9. The C4 alkyne selective hydrogenation catalyst according to claim 1, characterized in that The catalyst was reduced with hydrogen at 300-450° C. for 6-16 hours before use.

10. A method for preparing the C4 alkyne selective hydrogenation catalyst according to any one of claims 1 to 9, characterized in that: The following steps are involved: After adjusting the pH of a solution containing soluble compounds of palladium and silver to 1.0-5.0, the catalyst is impregnated with a carrier in one or more steps, dried, and calcined at 300-600°C for 3-8 hours to obtain a C4-acetylene selective hydrogenation catalyst; the carrier is aluminum oxide with a blade-like aggregate structure.

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