Process for the selective hydrodephenylation of the c8 cut

Abstract

This invention discloses a method for selective hydrogenation of C8 fractions to remove phenylacetylene. The method includes: using a hydrocarbon fraction containing phenylacetylene as feedstock, and reacting it at a reaction temperature of 10-90°C and a feed volume hourly space velocity of 0.1-20 h⁻¹. ‑1 Under reaction pressures of 0.1–5 MPa and a hydrogen / phenylacetylene molar ratio of 1–30:1, the feedstock contacts the catalyst, and phenylacetylene in the effluent is hydrogenated to styrene. The catalyst, supported on a foliated aggregate structure of alumina, contains, by weight (100%), 10–25 wt% nickel oxide, 0.01–4 wt% copper oxide, 0–3 wt% cerium oxide and / or lanthanum oxide, 0–5 wt% alkali metal and / or alkaline earth metal oxides, with the balance being alumina. The catalyst used in the selective hydrogenation method for removing phenylacetylene from the C8 fraction of this invention exhibits better reactivity, selectivity, and resistance to coking.

Description

Technical Field

[0001] This invention relates to a method for selective hydrogenation of C8 fractions to remove phenylacetylene, and particularly to a method for removing phenylacetylene from C8 hydrocarbon fractions containing phenylacetylene. Background Technology

[0002] Styrene is an important monomer for the production of polystyrene, ABS resin, styrene-butadiene rubber, etc. The ethylbenzene dehydrogenation method is the main preparation method, but it has the disadvantage of high production cost. Extracting styrene from the C8 fraction, a by-product of ethylene cracking, has become a very attractive new route to increase styrene production.

[0003] Cracked gasoline is a byproduct of the ethylene industry, accounting for approximately 50% to 80% of ethylene production capacity. Styrene can be recovered by extracting its C8 fraction. A 1000 kt / a ethylene unit can produce approximately 20 to 40 kt / a of styrene, while also recovering mixed xylene. This upgrades the C8 fraction from fuel value to chemical value, and its production cost is about half that of traditional ethylbenzene dehydrogenation to styrene, giving it strong market competitiveness. Furthermore, the separation of the C8 fraction reduces the load on subsequent hydrogenation units of cracked gasoline, reduces hydrogen consumption, and avoids poisoning of the hydrogenation catalyst caused by styrene polymerization.

[0004] The current method for recovering styrene from cracked gasoline is extractive distillation, but the C8 fraction contains 4000–15000 μg·g⁻¹. -1 Phenylacetylene (PA) is present in styrene, while stearic acid (ST) and PA have similar chemical structures and similar interactions with extractive distillation solvents. Therefore, existing extractive distillation processes cannot effectively separate ST and PA. The presence of these phenylacetylenes not only increases catalyst consumption during SM anionic polymerization and affects chain length and polymerization rate, but also impacts the color, odor, and overall properties of the polymerized product. Therefore, before extracting styrene from C8 fractions of ethylene cracking, selective hydrogenation of phenylacetylene is necessary. Since the C8 fraction contains 30–50% styrene, styrene loss during hydrogenation should be minimized. Therefore, developing a method for the selective hydrogenation removal of phenylacetylene from C8 fractions of cracked ethylene is crucial for this technology.

[0005] Patent CN101475438A uses hydrocarbon fractions containing phenylacetylene as raw materials, and the reaction is carried out at a temperature of 15-100℃ and a weight hourly space velocity of 0.01-100h. -1 The reaction was carried out at a hydrogen to phenylacetylene molar ratio of 1-30:1 and a reaction pressure of 0.08-5.0 MPa, achieving high efficiency. Nickel or palladium-based catalysts were used, and pre-coking of the catalyst with styrene at a high temperature before the reaction was proposed to improve selectivity.

[0006] Patent CN101475439A describes a composite bed process using hydrocarbon fractions containing phenylacetylene as feedstock, with a reaction temperature of 15-100℃ and a weight hourly space velocity of 0.01-100 h⁻¹. -1 With a hydrogen to phenylacetylene molar ratio of 1-30:1 and a reaction pressure of 0.08-5.0 MPa, the raw materials are passed through a composite bed reactor containing nickel-based catalyst A and palladium-based or copper-based catalyst B. The phenylacetylene conversion rate is up to 100%, and there is no loss of styrene.

[0007] Patent CN1852877A discloses a method for reducing phenylacetylene in the presence of styrene. The catalyst is a copper compound supported on θ-Al2O3. The hydrogenation reactor is operated at a temperature of 60°C and a pressure of 0.2 MPa. The hydrogenation gas is a mixture of nitrogen and hydrogen. This technology has a high reaction temperature, a low phenylacetylene hydrogenation rate (about 70%), and a high styrene loss rate (about 3%).

[0008] Patent CN1087892A discloses a method for removing phenylacetylene impurities from hydrogenated styrene materials. It uses ethylbenzene dehydrogenation exhaust gas to provide hydrogen, and adds nitrogen to dilute the hydrogen. This patent uses a Pd-based catalyst and can only remove acetylene from hydrocarbons with a phenylacetylene content of 300 μg / g. The phenylacetylene hydrogenation rate is only 95%, and the styrene loss rate is about 0.2%.

[0009] Alumina, as an excellent catalyst support and adsorbent material, has wide applications in industry. The microstructure and surface properties of alumina significantly influence the performance of supported catalysts; therefore, the controllable synthesis of alumina morphology and size has attracted considerable research interest. Currently, researchers have prepared alumina morphologies including flakes, rods, and spherical shapes using various methods. Nanosheet alumina possesses a large specific surface area and high surface energy, exhibiting high dispersibility of active metals in catalysts and a high diffusion rate for reactants, significantly reducing diffusion resistance. Therefore, as a support, it can greatly improve catalyst activity and anti-coking properties, demonstrating superior performance compared to traditional alumina.

[0010] Currently, the synthesis of sheet-like alumina mainly focuses on micron-sized sheet-like alumina, primarily used for preparing sheet-like alumina ceramics. The synthesis routes for nano-sheet-like alumina are mostly developed based on surfactants as templates, which are costly and prone to agglomeration during high-temperature calcination, thus limiting their industrialization.

[0011] 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) Inorganic aluminum salt and precipitant are dissolved in a water-ethylene glycol mixed solvent at a molar ratio of 1:5 to 1:9, and stirred to obtain a transparent solution. The solution is then transferred 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 reactants are filtered, washed, dried, and calcined to obtain a nano-alumina carrier rich in surface defects with a specific surface area of ​​150 to 400 m². 2 / g, pore volume is 0.34~0.62cm³ 3 / g. However, ethylene glycol in the mixed solvent is easily oxidized by hydrothermal metabolism to produce toxic oxalic acid, thus it cannot be widely used as a solvent and is not conducive to promotion.

[0012] Patent CN201210427889.2 discloses a method for preparing an alumina support, comprising the following steps: measuring an appropriate amount of 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 until completely dissolved, wherein the amount of urea added is equal to the ratio of urea to Al. 3+ The molar ratio is 2-10:1; the above solution is placed in a sealed reaction vessel and reacted at 140℃-200℃ for 2-12 hours, followed by direct calcination to prepare the alumina support. Although the support prepared by this method has a high specific surface area and large pore size, the alumina support is obtained by directly drying and calcining the material after the reaction without filtration and washing, resulting in a high content of amorphous alumina and a dispersed pore distribution, which limits its further application.

[0013] Patent CN201110351132.5 provides an improved hydrothermal method for preparing porous alumina ultrafine powder. Using aluminum inorganic salt as raw material and urea as co-precipitant, a precursor is generated under hydrothermal conditions. The precursor is then centrifuged, washed, dried, and calcined to obtain porous alumina ultrafine powder with high purity, narrow particle size distribution, and high porosity.

[0014] Patent CN107540007A discloses a method for preparing nanosheet mesoporous alumina: using inorganic aluminum salt as the aluminum source, triethanolamine as the additive, and ethylenediamine as the precipitant, nanosheet mesoporous alumina is obtained by hydrothermal aging treatment. The thickness of the nanosheet alumina sheets is 1-10 nm and the width is 0.1-0.5 μm.

[0015] Patent CN107777713A discloses a γ-alumina hexagonal nanosheet material and its preparation method, with a size of 50-500 nm and a thickness of 5-10 nm. This invention uses aluminum alkoxides as raw materials, controls the two-dimensional growth of its intermediate alumina hydroxide through organic amines, and prepares γ-alumina hexagonal nanosheets using chemical precipitation and hydrothermal methods.

[0016] Patent CN104961146A discloses a nanosheet aluminum hydroxide colloid and its preparation method, which involves directly hydrothermally heating anhydrous ethanol and anhydrous aluminum chloride at 220-300℃ to obtain a nanosheet gel with a thickness of 3-20 nm.

[0017] 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 then transferred to a high-pressure reactor, and hydrogen gas is introduced into the reactor to maintain a certain pressure and temperature for reaction to obtain leaf-shaped nano-γ-alumina. However, the leaf-shaped nano-γ-alumina is in a dispersed state and does not accumulate. It is prone to agglomeration during high-temperature calcination. When used as a catalyst support to load active metals, it will reduce the dispersion of active metals on the surface of the support. Moreover, the preparation process uses relatively dangerous hydrogen gas, which is not conducive to production safety.

[0018] The article by Li Jinlin et al., “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,” prepared alumina nanosheets with a length of 60-100 nm using acetic acid and isopropanol as raw materials and hydrothermally at 200℃. The main exposed crystal plane was the (110) crystal plane. The article by Yuguo Xia et al., “Synthesis of AlOOH nanocrystals with different morphologies due to the effect of sulfate ions and the corresponding 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 alumina nanosheets with a size of 60-100 nm. The alumina prepared by this method has a small specific surface area (<100 nm). 2 Moreover, the preparation process uses dilute acid, and the high-temperature hydrothermal process places high demands on the reactor material, which is not conducive to large-scale production.

[0019] Existing patents and literature report synthetic routes for regularly morphologically regular alumina, which are either based on surfactant template methods, use expensive aluminum alkoxides as raw materials, or involve harsh synthesis conditions. Moreover, the prepared alumina morphology is all dispersed nanosheets. Dispersed nanosheets have disadvantages such as difficulty in product separation and easy agglomeration during high-temperature calcination (e.g., above 900°C), making it difficult to maintain the nanosheet morphology. Thus, as a catalyst support, it loses the advantage of a sheet-like morphology.

[0020] In existing technologies, selective hydrogenation of C8 fractions for the removal of phenylacetylene often utilizes supported metal catalysts, with palladium, a precious metal, commonly used as the main active component. Due to the high price and scarce reserves of palladium, developing a non-precious metal catalyst is of significant strategic importance. Furthermore, nanosheet-like alumina supports possess a large specific surface area and high surface energy, exhibiting high dispersibility of the active metal in the catalyst and a high diffusion rate for reactants, significantly reducing diffusion resistance. Therefore, as a support, it can greatly improve catalyst activity and anti-coking performance, demonstrating superior performance compared to traditional alumina. Summary of the Invention

[0021] The technical problem to be solved by this invention is the low hydrogenation rate of phenylacetylene and the high loss rate of styrene in the prior art. This invention provides a method for selective hydrogenation of C8 fraction to remove phenylacetylene. The catalyst used in this method has better reactivity, selectivity and anti-coking properties during the hydrogenation process.

[0022] To achieve the above objectives, the present invention provides a method for selective hydrogenation of C8 fractions to remove phenylacetylene. The method comprises: using a hydrocarbon fraction containing phenylacetylene as feedstock, and reacting the fraction at a reaction temperature of 10-90°C and a feed volume hourly space velocity of 0.1-20 h⁻¹. -1 Under the conditions of reaction pressure of 0.1-5 MPa and hydrogen / phenylacetylene molar ratio of 1-30:1, the raw materials are in contact with the catalyst, and phenylacetylene in the reaction effluent is hydrogenated to styrene; wherein, the catalyst is supported by alumina with a leaf-like aggregate structure, and contains, by weight 100% of the total catalyst, 10-25 wt% nickel oxide, 0.01-4 wt% copper oxide, 0-3 wt% cerium oxide and / or lanthanum oxide, 0-5 wt% alkali metal and / or alkaline earth metal oxides, and the balance alumina.

[0023] Preferably, in the method of the present invention, the reaction temperature is 20–50°C and the feed volume hourly space velocity is 0.5–3.0 h⁻¹. -1 The reaction pressure is 0.1-0.8 MPa, the hydrogen / phenylacetylene molar ratio is 1-20:1, and the raw material is a cracked C8 fraction with a styrene content of 30-45 wt% and a phenylacetylene content of 0.2-2 wt%.

[0024] In the method of the present invention, based on the total weight of the catalyst (100%), nickel oxide is preferably 13-18 wt%, copper oxide is preferably 0.1-2.5 wt%, cerium oxide and / or lanthanum oxide is preferably 0.1-1.5 wt%, and alkali metal and / or alkaline earth metal oxides are preferably 0.3-3 wt%; the specific surface area of ​​the catalyst is 40-200 m². 2 / g, pore volume is 0.30~0.60ml / g, bulk density is 0.5~1.2g / cm³ 3 .

[0025] In the method of the present invention, the active components nickel and copper are added in the form of soluble salts. The soluble salt of nickel is selected from at least one of nickel nitrate, nickel acetate, nickel chloride, and nickel sulfate, preferably nickel nitrate or nickel acetate. The soluble salt of copper is selected from at least one of copper nitrate and basic copper carbonate.

[0026] The present invention does not particularly limit the preparation method of the catalyst. For example, but not limited to, the catalyst can be prepared by the equal volume impregnation method, in which an aqueous solution of soluble salts containing nickel and copper is impregnated on the support, dried, and then calcined at 300-500°C for 3-8 hours to obtain the catalyst.

[0027] In the method of this invention, the content of cerium oxide and / or lanthanum oxide is preferably 0.1–1.5 wt%. The addition of cerium and / or lanthanum can suppress the growth of catalyst support grains during high-temperature calcination, improve the dispersion of the active component nickel, and enhance the hydrogenation selectivity and stability of the catalyst. In this invention, cerium and / or lanthanum are preferably added in the form of soluble nitrates.

[0028] In the method of this invention, the content of alkali metals and / or alkaline earth metals (existing in oxide form) is preferably 0.3–3 wt%. The alkali metals and / or alkaline earth metals are at least one selected from Li, Na, K, Ca, Mg, Sr, and Be, preferably one or two selected from Li and Mg. When the catalyst is used for selective hydrogenation of C8 fractions, olefins and dienes in the oil easily polymerize to form gums and become deactivated. By adding alkali metals and / or alkaline earth metals, the acidity or alkalinity of the catalyst support surface can be adjusted. Adjusting the acidity or alkalinity of the catalyst surface can improve hydrogenation activity and stability, which is beneficial for reducing the deposition of carbonaceous and gum substances during hydrogenation, thereby extending the catalyst's service life. In this invention, the alkali metals and / or alkaline earth metals are preferably added in the form of soluble nitrates, acetates, or citrates.

[0029] In the method of the present invention, rare earth elements cerium and / or lanthanum, as well as alkali metals and / or alkaline earth metals, can be added during the carrier molding process; they can also be added to the carrier after the carrier is molded and before impregnating the active component; or they can be added simultaneously with the active component impregnation solution during the impregnation of the active component.

[0030] The method of this invention uses alumina with a regular morphology of leaf-like aggregates. This alumina is prepared by a hydrothermal synthesis method, specifically including the following steps:

[0031] Step (1): Add the compound that can decompose into NH3 and CO2 in the subsequent hydrothermal treatment in step (2) to the inorganic aluminum salt aqueous solution, and stir until completely dissolved to form a mixed solution;

[0032] Step (2): CO2 gas at a pressure of 0.1-2 MPa is introduced into the mixed solution, and then hydrothermal treatment is performed. The obtained product is filtered to separate solid and liquid. The obtained solid is washed, dried and calcined to obtain alumina with a leaf-like aggregate structure.

[0033] In the method of the present invention, in step (2) of the alumina preparation method, the mixed solution is introduced into a hydrothermal reactor or a high-pressure reactor with CO2 gas at a pressure of 0.2 to 1 MPa, and then subjected to hydrothermal treatment.

[0034] In the method of the present invention, the compound that can decompose into CO2 and NH3 in the subsequent hydrothermal treatment of the alumina preparation method in step (1) is selected from one or more of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

[0035] In the method of the present invention, the amount of compound added in step (1) of the alumina preparation method that can decompose into CO2 and NH3 in the subsequent hydrothermal treatment is such that the molar ratio of aluminum ions of inorganic aluminum salt to compound is 0.1 to 4.0, preferably 0.5 to 3.

[0036] In the method of the present invention, the inorganic aluminum salt in step (1) of the alumina preparation method can be one or more of aluminum sulfate, aluminum nitrate and aluminum chloride.

[0037] In the method of this invention, the hydrothermal treatment in step (2) of the alumina preparation method can adopt conventional process conditions in the art. The process conditions recommended by this invention are: hydrothermal temperature of 120-200℃ and hydrothermal time of 4-24h.

[0038] The method of this invention provides an alumina with a specific surface area of ​​60–300 m². 2 / g, pore volume 0.25~0.72cm 3 / g, with an average pore size of 7–25 nm.

[0039] Before molding, the alumina with the leaf-like aggregate structure of the present invention can be supplemented with one or more of the following: a binder, an extrusion aid, and alumina dry adhesive powder. The binder includes, but is not limited to, one or more of nitric acid, phosphoric acid, hydrochloric acid, and sulfuric acid, and is added in an amount of 3-10 wt% of the total weight of the sample to be molded. The extrusion aid includes, but is not limited to, guar gum powder, and is generally used in an amount of 2-6 wt% of the total weight of the sample to be molded. The alumina dry adhesive powder is prepared using conventional methods, but the amount added is preferably less than 10 wt% of the total mass of nickel-containing boehmite.

[0040] The calcination method and conditions described are commonly used for catalyst support calcination. Vertical furnaces, converters, and mesh belt kilns can be used. The preferred calcination conditions for the support are: 800–1000℃ for 4–10 hours. This calcination temperature is the same as the calcination temperature of the support before impregnation with the active components Ni and Cu, to ensure the required specific surface area and pore volume of the catalyst, and to ultimately obtain a support with a specific nickel and aluminum mixed crystal structure. Prior to this calcination temperature, the support may be prepared through low-temperature calcination, but these are all intermediate transitional calcination steps.

[0041] In the method of the present invention, the catalyst is preferably reduced with hydrogen at 380–450°C for 6–16 hours before use.

[0042] The catalyst used in the method of the present invention has the characteristics of high selectivity and good stability. The method of the present invention can be used to effectively remove phenylacetylene from the C8 fraction by selective hydrogenation.

[0043] The alumina used in the catalyst of this invention has a leaf-like aggregate structure, characterized by regular morphology, uniform particle size, high crystallinity, and high thermal stability. This leaf-like aggregate structure overcomes the shortcomings of conventional nano-sheet alumina products, which are difficult to separate and prone to agglomeration at high temperatures. The leaf-like aggregate structure of this invention allows for simple separation, and it does not agglomerate during high-temperature calcination, maintaining its nano-sheet morphology. Therefore, it can serve as an excellent catalyst support for the selective hydrogenation of C8 fractions. During the preparation process, CO2 gas is introduced, which effectively neutralizes the number of surface hydroxyl groups on the alumina leaves during crystallization. This reduces leaf curling caused by hydroxyl condensation during crystallization and effectively controls the width of the alumina leaves. Furthermore, it reduces the saturation of hydroxyl groups with aluminum ions, making the sheet-like alumina more conducive to chelation coordination with active metals. In addition, this invention uses a high molar ratio of aluminum ions to compounds, which improves the yield per batch and effectively reduces production costs. The catalyst of this invention exhibits high active metal dispersion and excellent hydrogenation activity and selectivity.

[0044] The method of this invention uses a foliated aggregate structure of alumina with inexpensive aluminum source as raw material and does not add template agent. Hydrothermal treatment yields foliated aggregate alumina with a regular morphology. The alumina preparation method of this invention has advantages such as low cost, simple operation, and simple synthesis conditions. Furthermore, the alumina prepared by this invention has a foliated aggregate structure, which is easy to separate and does not agglomerate during high-temperature calcination, maintaining its nanosheet morphology. Therefore, it can serve as an excellent catalyst support for catalytic hydrogenation reactions.

[0045] This invention, through research, has discovered that a catalyst prepared using alumina with a lamellar aggregate structure as a support, with Ni as the main active component and Cu as the secondary active component, exhibits not only high selectivity but also good stability, thus resolving the problem of mutual constraints among activity, selectivity, and stability. The catalyst of this invention exhibits high selectivity; that is, during the hydrogenation reaction of phenylacetylene, styrene does not undergo hydrogenation or only undergoes a very small portion of hydrogenation. This is likely due to the high dispersion of Ni and Cu on the lamellar alumina support, fully utilizing their synergistic effect. Furthermore, when the support is treated with alkali metals or alkaline earth metals or mixtures thereof, this invention can effectively control the acidity of the support surface, which is beneficial for inhibiting the polymerization reaction of styrene and reducing styrene loss.

[0046] The method of the present invention, when used for selective hydrogenation of C8 fraction to remove phenylacetylene, achieves better technical results by lowering the phenylacetylene content and styrene loss rate in the hydrogenated product at a lower temperature. Attached Figure Description

[0047] Figure 1 This is a SEM image of the leaf-shaped aggregate structure of alumina obtained in Example 1 of the present invention.

[0048] Figure 2 The image shows the SEM image of alumina in Comparative Example 1. Detailed Implementation

[0049] The present invention will be specifically described below through embodiments. It should be noted that these embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above description of the present invention.

[0050] Example 1

[0051] (1) Carrier preparation

[0052] 26.7 g of aluminum sulfate and 4.2 g of ammonium bicarbonate (molar ratio of aluminum ions to ammonium bicarbonate was 1.5) were added to 70 ml of deionized water, stirred and dissolved, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 1 MPa, and the reaction was carried out at 180 °C for 8 h. After cooling to room temperature, the product was filtered to separate the solid and liquid. The obtained solid was washed, dried, shaped, and calcined at 850 °C for 4 h to obtain a leaf-shaped aggregate alumina support precursor. An aqueous solution of lanthanum nitrate (3 wt%), lithium carbonate (0.3 wt%), and citric acid was prepared and impregnated onto the leaf-shaped aggregate alumina support precursor by an equal-volume impregnation method. The mixture was dried at 120 °C for 4 h and calcined at 920 °C for 4 h to obtain a support containing lanthanum and lithium.

[0053] (2) Catalyst preparation

[0054] The catalyst was prepared by a two-step impregnation method. In the first step, nickel acetate (25 wt%) and copper nitrate (4 wt%) were dissolved in water to prepare an impregnation solution, which was then impregnated onto 10 g of the support prepared in step (1) using an equal-volume impregnation method, impregnating 35% of the total nickel nitrate content. The solution was dried at 120 °C and calcined at 350 °C for 4 h. In the second step, 65% of the total nickel nitrate content was impregnated using the same method, dried at 120 °C, and calcined at 430 °C for 4 h to obtain catalyst C1. The content of each component in the obtained catalyst C1 is shown in Table 1.

[0055] (3) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0056] Catalyst C1 was placed in a fixed-bed reactor before use and reduced at 380°C for 8 hours using a N2:H2 mixture with a molar ratio of N2:H2 = 1:1. The feedstock was cracked C8 fraction containing 30% styrene and 0.2% phenylacetylene, and the reactor inlet temperature was 15°C with a feed hourly space velocity (VHSV) of 0.1 h⁻¹. -1 Under reaction pressure of 0.1 MPa and a hydrogen / phenylacetylene molar ratio of 30:1, the hydrogenation product contains 28 μg / g of phenylacetylene, and the styrene loss rate is ≤0.8%.

[0057] Example 2

[0058] (1) Carrier preparation

[0059] 60g of aluminum nitrate and 3.2g of urea (molar ratio of aluminum ions to urea is 3) were added to 70ml of deionized water, stirred and dissolved, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 2MPa, and the reaction was carried out at 220℃ for 4h. After cooling to room temperature, the product was filtered to separate the solid and liquid phases. The obtained solid was washed, dried, shaped, and calcined at 650℃ for 5h to obtain a leaf-shaped aggregate alumina support precursor. Aqueous solutions of cerium nitrate (3wt%), magnesium carbonate (0.3wt%), and citric acid were prepared and impregnated onto the leaf-shaped aggregate alumina support precursor using an equal-volume impregnation method. The mixture was dried at 120℃ for 4h and calcined at 920℃ for 4h to obtain a support containing cerium and magnesium.

[0060] (2) Catalyst preparation

[0061] The catalyst was prepared by a two-step impregnation method. In the first step, nickel sulfate (20 wt%) and basic copper carbonate (0.4 wt%) were dissolved in water to prepare an impregnation solution, which was then impregnated onto 50 g of the support prepared in step (1) using an equal-volume impregnation method, impregnating 35% of the total nickel nitrate content. The solution was dried at 120 °C and calcined at 300 °C for 3 h. In the second step, 65% of the total nickel nitrate content was impregnated using the same method, dried at 120 °C, and calcined at 300 °C for 3 h to obtain catalyst C2. The content of each component in the obtained catalyst C2 is shown in Table 1.

[0062] (3) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0063] Catalyst C2 was placed in a fixed-bed reactor before use and reduced at 390°C for 8 hours using a N2:H2 mixture with a molar ratio of N2:H2 = 1:1. The feedstock was cracked C8 fraction containing 35% styrene and 0.8% phenylacetylene, and the reactor inlet temperature was 20°C with a feed hourly space velocity (VHSV) of 0.2 h⁻¹. -1 Under reaction pressure of 0.2 MPa and a hydrogen / phenylacetylene molar ratio of 20:1, the hydrogenation product contains 16 μg / g of phenylacetylene, and the styrene loss rate is ≤0.6%.

[0064] Example 3

[0065] (1) Carrier preparation

[0066] 10.3 g of aluminum chloride and 5.1 g of ammonium carbonate (molar ratio of aluminum ions to ammonium carbonate of 0.8) were added to 70 ml of deionized water, stirred and dissolved, and then transferred to a hydrothermal reactor. CO2 gas was introduced to 0.1 MPa, and the reaction was carried out at 100 °C for 48 h. After cooling to room temperature, the product was filtered to separate the solid and liquid phases. The obtained solid was washed, dried, shaped, and calcined at 1000 °C for 4 h to obtain a leaf-shaped aggregate alumina support precursor. Aqueous solutions of cerium nitrate (2 wt%), magnesium carbonate (1 wt%), and citric acid were prepared and impregnated onto the leaf-shaped aggregate alumina support precursor using an equal-volume impregnation method. The mixture was dried at 120 °C for 4 h and calcined at 920 °C for 4 h to obtain a support containing cerium and magnesium.

[0067] (2) Catalyst preparation

[0068] The catalyst was prepared by a two-step impregnation method. In the first step, nickel chloride (20 wt%) and copper nitrate (0.8 wt%) were dissolved in water to prepare an impregnation solution, which was then impregnated onto 10 g of the support prepared in step (1) using an equal-volume impregnation method, impregnating 35% of the total nickel nitrate content. The solution was dried at 120 °C and calcined at 400 °C for 5 h. In the second step, 65% of the total nickel nitrate content was impregnated using the same method, dried at 120 °C, and calcined at 400 °C for 5 h to obtain catalyst C3. The content of each component in the obtained catalyst C3 is shown in Table 1.

[0069] (3) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0070] Catalyst C3 was placed in a fixed-bed reactor before use and reduced at 400°C for 8 hours using a N2:H2 mixture with a molar ratio of N2:H2 = 1:1. The feedstock was cracked C8 fraction containing 35% styrene and 0.8% phenylacetylene, and the reactor inlet temperature was 20°C with a feed hourly space velocity (VHSV) of 0.2 h⁻¹. -1 Under reaction pressure of 0.3 MPa and a hydrogen / phenylacetylene molar ratio of 20:1, the phenylacetylene content in the hydrogenation product is 14 μg / g, and the styrene loss rate is ≤0.5%.

[0071] Example 4

[0072] (1) Carrier preparation

[0073] 56.9 g of aluminum sulfate, 16 g of aluminum nitrate, and 6.6 g of ammonium oxalate (molar ratio of aluminum ions to ammonium oxalate was 4) were added to 70 ml of deionized water and stirred until dissolved. The mixture was then transferred to a hydrothermal reactor, and CO2 gas was introduced to a pressure of 0.5 MPa. The reactor was reacted at 160 °C for 10 h. After cooling to room temperature, the product was filtered to separate the solid and liquid phases. The resulting solid was washed, dried, shaped, and calcined at 750 °C for 5 h to obtain a leaf-shaped aggregate alumina support precursor. An aqueous solution of lanthanum nitrate (3 wt%), lithium carbonate (5 wt%), and citric acid was prepared and impregnated onto the leaf-shaped aggregate alumina support precursor using an equal-volume impregnation method. The mixture was dried at 120 °C for 4 h and calcined at 920 °C for 4 h to obtain a support containing lanthanum and lithium.

[0074] (2) Catalyst preparation

[0075] The catalyst was prepared by a two-step impregnation method. In the first step, nickel nitrate (15 wt%) and basic copper carbonate (0.8 wt%) were dissolved in water to prepare an impregnation solution, which was then impregnated onto 50 g of the support prepared in step (1) using an equal-volume impregnation method, impregnating 35% of the total nickel nitrate content. The solution was dried at 120°C and calcined at 500°C for 8 h. In the second step, 65% of the total nickel nitrate content was impregnated using the same method, dried at 120°C, and calcined at 500°C for 8 h to obtain catalyst C4. The content of each component in the obtained catalyst C4 is shown in Table 1.

[0076] (3) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0077] Catalyst C4 was placed in a fixed-bed reactor before use and reduced at 400°C for 8 hours using a N2:H2 mixture with a molar ratio of N2:H2 = 1:1. The feedstock was cracked C8 fraction containing 40% styrene and 1.2% phenylacetylene. The reactor inlet temperature was 30°C, and the feed volume hourly space velocity (VHSV) was 0.2 h⁻¹. -1 Under reaction pressure of 0.2 MPa and a hydrogen / phenylacetylene molar ratio of 20:1, the hydrogenation product contains 17 μg / g of phenylacetylene, and the styrene loss rate is ≤0.5%.

[0078] Example 5

[0079] 17.8 g of aluminum sulfate, 1.6 g of urea, and 3.3 g of ammonium oxalate (molar ratio of aluminum ions to urea and ammonium oxalate was 1) were added to 70 ml of deionized water and stirred until dissolved. The solution was then transferred to a hydrothermal reactor, and CO2 gas was introduced to 0.3 MPa. The reactor was reacted at 140 °C for 24 h. After cooling to room temperature, the product was filtered to separate the solid and liquid phases. The resulting solid was washed, dried, shaped, and calcined at 800 °C for 6 h to obtain a leaf-shaped aggregate alumina support precursor. An aqueous solution of lithium carbonate (3 wt%) and citric acid was prepared and impregnated onto the leaf-shaped aggregate alumina support precursor using an equal-volume impregnation method. The mixture was dried at 120 °C for 4 h and calcined at 920 °C for 4 h to obtain a support containing lanthanum and lithium.

[0080] (2) Catalyst preparation

[0081] The catalyst was prepared by a two-step impregnation method. In the first step, nickel acetate (10 wt%) and copper nitrate (2 wt%) were dissolved in water to prepare an impregnation solution, which was then impregnated onto 50 g of the support prepared in step (1) using an equal-volume impregnation method, impregnating 35% of the total nickel nitrate content. The solution was then dried at 120°C and calcined at 500°C for 5 h. In the second step, 65% of the total nickel nitrate content was impregnated using the same method, dried at 120°C, and calcined at 500°C for 5 h to obtain catalyst C5. The content of each component in the obtained catalyst C5 is shown in Table 1.

[0082] (3) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0083] Catalyst C5 was placed in a fixed-bed reactor before use and reduced at 450°C for 8 hours using a N2:H2 mixture with a molar ratio of N2:H2 = 1:1. The feedstock was cracked C8 fraction containing 40% styrene and 1.6% phenylacetylene. The reactor inlet temperature was 90°C, and the feed volume hourly space velocity was 10 h⁻¹. -1 Under the conditions of a reaction pressure of 5 MPa and a hydrogen / phenylacetylene molar ratio of 10:1, the phenylacetylene content of the hydrogenation product is 12 μg / g, and the styrene loss rate is ≤0.6%.

[0084] Example 6

[0085] 0.6 g aluminum sulfate, 0.4 g aluminum chloride, 0.7 g aluminum nitrate, 1.6 g urea, and 2.6 g ammonium carbonate (molar ratio of aluminum ions to urea and ammonium carbonate is 0.1) were added to 70 ml of deionized water. After stirring and dissolving, the mixture was transferred to a hydrothermal reactor, and CO2 gas was introduced to 0.8 MPa. The reaction was carried out at 300 °C for 4 h. After cooling to room temperature, the product was filtered to separate the solid and liquid phases. The obtained solid was washed, dried, shaped, and calcined at 950 °C for 4 h to obtain a leaf-shaped aggregate alumina support precursor. A magnesium carbonate (3 wt%) and citric acid aqueous solution was prepared and impregnated onto the leaf-shaped aggregate alumina support precursor using an equal-volume impregnation method. The mixture was dried at 120 °C for 4 h and calcined at 920 °C for 4 h to obtain a support containing lanthanum and lithium.

[0086] (2) Catalyst preparation

[0087] The catalyst was prepared by a two-step impregnation method. In the first step, nickel acetate (18 wt%) and copper nitrate (0.01 wt%) were dissolved in water to prepare an impregnation solution, which was then impregnated onto 50 g of the support prepared in step (1) using an equal-volume impregnation method, impregnating 35% of the total nickel nitrate content. The solution was dried at 120 °C and calcined at 500 °C for 8 h. In the second step, 65% of the total nickel nitrate content was impregnated using the same method, dried at 120 °C, and calcined at 500 °C for 8 h to obtain catalyst C6. The content of each component in the obtained catalyst C6 is shown in Table 1.

[0088] (3) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0089] Before use, catalyst C6 was placed in a fixed-bed reactor and reduced at 400°C for 8 hours using a N2:H2 mixture with a molar ratio of N2:H2 = 1:1. The feedstock was a cracked C8 fraction containing 45% styrene and 2% phenylacetylene, and the reactor inlet temperature was 50°C, with a feed volume hourly space velocity (VHSV) of 20 h⁻¹. -1 Under the conditions of reaction pressure of 3 MPa and hydrogen / phenylacetylene molar ratio of 30:1, the hydrogenation product contains 9 μg / g of phenylacetylene, and the styrene loss rate is ≤1%.

[0090] Comparative Example 1

[0091] (1) Carrier preparation

[0092] Industrial-grade boehmite prepared by commercial carbonization method was mixed with nitric acid, phosphoric acid, guar gum powder and water to form a plastic body, which was then extruded into strips, dried at 120℃ for 4 hours and calcined at 920℃ for 4 hours to obtain an alumina carrier.

[0093] (2) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0094] 100g of the support prepared in (1) was weighed and catalyst D1 was prepared using the same preparation method as in Example 1. The content of each component in the obtained catalyst D1 is shown in Table 1. The same activation method and evaluation conditions were used to remove phenylacetylene. The phenylacetylene content of the hydrogenation product was 87μg / g, and the styrene loss rate was ≤2.2%.

[0095] Comparative Example 2

[0096] (1) Carrier preparation

[0097] Commercially available gibbsite prepared using the nitric acid method was mixed with nitric acid, phosphoric acid, guar gum powder, and water to form a plastic mass, which was then extruded into strips and dried at 120°C for 4 hours and calcined at 850°C for 6 hours to obtain an alumina support. An aqueous solution of cerium nitrate (3 wt%), magnesium carbonate (0.3 wt%), and citric acid was prepared and impregnated onto the alumina support using an equal-volume impregnation method. The mixture was then dried at 120°C for 4 hours and calcined at 920°C for 4 hours to obtain a cerium- and magnesium-containing support.

[0098] (2) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0099] 100g of the support prepared in (1) was weighed and catalyst D2 was prepared using the same preparation method as in Example 2. The content of each component in the obtained catalyst D2 is shown in Table 1. The same activation method and evaluation conditions were used to remove phenylacetylene. The phenylacetylene content of the hydrogenation product was 45 μg / g, and the styrene loss rate was ≤2.1%.

[0100] Comparative Example 3

[0101] (1) Carrier preparation

[0102] Industrial-grade boehmite prepared using the commercially available aluminum sulfate method was mixed with nitric acid, phosphoric acid, guar gum powder, and water to form a plastic body, which was then extruded into strips, dried at 120°C for 4 hours, and calcined at 720°C for 5 hours to obtain an alumina carrier.

[0103] (2) Selective hydrogenation method for removing phenylacetylene from C8 fraction

[0104] 100g of the support prepared in (1) was weighed and catalyst D3 was prepared using the same preparation method as in Example 3. The content of each component in the obtained catalyst D3 is shown in Table 1. The same activation method and evaluation conditions were used to remove phenylacetylene. The phenylacetylene content of the hydrogenation product was 57 μg / g, and the styrene loss rate was ≤2.5%.

[0105] Table 1. Components and contents of catalysts obtained in the examples and comparative examples.

[0106]

[0107]

[0108] Characterization of active metal dispersion in catalysts:

[0109] The dispersion of the metal active component in the catalyst was determined by CO pulse titration using a Micromeritics Autochem 2920 chemisorption analyzer. 0.1 g of catalyst samples from Examples 1-6 and Comparative Examples 1-3 were weighed, reduced at 800 °C for 2 hours, cooled to 40 °C, and purged with helium for 60 min.

[0110] CO pulse titration: 2% CO-He was titrated using a loop injection method, pulsed until adsorption, and detected using a TCD detector. The results of the metal dispersion determination are shown in Table 2.

[0111] Table 2. Metal dispersion of catalysts in the examples and comparative catalysts.

[0112] catalyst Metal Dispersion C1 15.4％ C2 17.8％ C3 16.3％ C4 19.7％ C5 21.4％ C6 18.3％ D1 10.9％ D2 11.3％ D3 11.1％

[0113] The results from the examples and comparative examples show that the catalyst of the method of the present invention, after using a leaf-shaped aggregate alumina support, exhibits high active metal dispersion and high hydrogenation activity and selectivity. When used for selective hydrogenation of C8 fractions to remove phenylacetylene, the method of the present invention achieves better technical results by resulting in lower phenylacetylene content and styrene loss in the hydrogenation product at lower temperatures.

[0114] Of course, the present invention may have other embodiments and variations. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and variations according to the present invention, but these corresponding changes and variations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for selective hydrogenation of C8 fractions to remove phenylacetylene, characterized in that, The method includes: using hydrocarbon fractions containing phenylacetylene as raw materials, reacting at a reaction temperature of 10-90℃ and a feed volume hourly space velocity of 0.1-20 h⁻¹. -1 Under the conditions of reaction pressure of 0.1~5MPa and hydrogen / phenylacetylene molar ratio of 1~30:1, the raw material is in contact with the catalyst, and the phenylacetylene in the reaction effluent is hydrogenated to styrene; wherein, the catalyst is supported by alumina with a leaf-like aggregate structure, and contains, by weight of 100% of the total catalyst, 10~25wt% nickel oxide, 0.01~4wt% copper oxide, 0~3wt% cerium oxide and / or lanthanum oxide, 0~5wt% alkali metal and / or alkaline earth metal oxides, and the balance alumina; The alumina is prepared by a hydrothermal synthesis method, specifically including the following steps: Step (1): Add the compound that can decompose into NH3 and CO2 in the subsequent hydrothermal treatment in step (2) to the inorganic aluminum salt aqueous solution, and stir until completely dissolved to form a mixed solution; Step (2): Introduce CO2 gas at 0.1-2 MPa into the mixed solution, then perform hydrothermal treatment, filter the obtained product to separate solid and liquid, wash, dry and calcine the obtained solid to obtain alumina with a leaf-like aggregate structure.

2. The method according to claim 1, characterized in that, The reaction temperature is 20~50℃, and the feed volume hourly space velocity is 0.5~3.0 h⁻¹. -1 The reaction pressure is 0.1~0.8MPa, the hydrogen / phenylacetylene molar ratio is 1~20:1, and the raw material is a cracked C8 fraction with a styrene content of 30~45wt% and a phenylacetylene content of 0.2~2wt%.

3. The method according to claim 1, characterized in that, Based on the total weight of the catalyst (100%), the content of nickel oxide is 13–18 wt%, the content of copper oxide is 0.1–2.5 wt%, the content of cerium oxide and / or lanthanum oxide is 0.1–1.5 wt%, and the content of alkali metal and / or alkaline earth metal oxides is 0.3–3 wt%; the specific surface area of ​​the catalyst is 40–200 m². 2 / g, pore volume is 0.30~0.60ml / g, bulk density is 0.5~1.2g / cm³ 3 .

4. The method according to claim 1, characterized in that, The nickel and copper are added in the form of soluble salts, wherein the soluble salt of nickel is selected from at least one of nickel nitrate, nickel acetate, nickel chloride, and nickel sulfate; and the soluble salt of copper is selected from at least one of copper nitrate and basic copper carbonate.

5. The method according to claim 1, characterized in that, The alkali metal and / or alkaline earth metal is at least one of Li, Na, K, Ca, Mg, Sr and Be.

6. The method according to claim 1, characterized in that, In step (1), the compound that can decompose into CO2 and NH3 in the subsequent hydrothermal treatment is one or more selected from ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

7. The method according to claim 1, characterized in that, In step (1), the molar ratio of aluminum ions in the inorganic aluminum salt to compounds that can decompose into NH3 and CO2 is 0.1 to 4.

0.

8. The method according to claim 7, characterized in that, In step (1), the molar ratio of aluminum ions in the inorganic aluminum salt to compounds that can decompose into NH3 and CO2 is 0.5 to 3.

9. The method according to claim 1, characterized in that, In step (1), the inorganic aluminum salt is one or more of aluminum sulfate, aluminum nitrate and aluminum chloride.

10. The method according to claim 1, characterized in that, The specific surface area of ​​the alumina is 60–300 m². 2 / g, pore volume of 0.25~0.72 cm³ 3 / g, with an average pore size of 7~25nm.

11. The method according to claim 1, characterized in that, Before use, the catalyst is reduced with hydrogen at 380~450℃ for 6~16h.

Images