Catalyst support, catalyst for selective hydrogenation of alkyne, and preparation method and application thereof

Abstract

The present application relates to the field of hydrofining technology, and discloses a catalyst carrier, an alkyne selective hydrogenation catalyst and a preparation method and application thereof. The present application innovatively uses Ag and Re as a doped component in the catalyst carrier, and the synergistic effect of the two greatly improves the dispersity of Ag. The alkyne selective hydrogenation catalyst prepared by using the carrier provided by the present application has greatly improved olefin selectivity and long-period running capability. The present application further provides a method for ethylene stream hydrofining under high CO and high H2 conditions, which can efficiently remove the high concentration of acetylene contained in the ethylene stream. In combination with the catalyst provided by the present application, extremely high ethylene selectivity can be obtained under high space velocity conditions, and long-term stable operation can be achieved, catalyst regeneration is reduced, and the method is very suitable for industrial popularization and application.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrofining, and specifically, to a catalyst support, an alkyne selective hydrogenation catalyst, and their preparation methods and applications. Background Art

[0002] Petroleum cracking is currently the main method for ethylene production, and ethylene produced by this technology accounts for more than 98% of the total world ethylene production. The sequential separation technology is one of the main cryogenic separation technologies supporting the petroleum cracking ethylene preparation technology. However, the ethylene stream obtained by using the sequential separation technology usually contains 0.5 - 2 mol% of acetylene, and sometimes the acetylene content can even reach more than 3 mol%. The presence of acetylene not only has an adverse effect on the performance of polyethylene products, but also is harmful to the control of the polymerization process.

[0003] Catalytic selective hydrogenation is a simple and economical way to remove acetylene, and it can also increase the production of ethylene. For the sequential separation technology, the carbon two post-hydrogenation process is generally used to remove acetylene, that is, after separating light components such as hydrogen and methane in the cracked gas, acetylene is removed through a carbon two hydrogenation reactor.

[0004] In the current research on selective hydrogenation catalysts for the carbon two post-hydrogenation process, supported catalysts using Ag as an auxiliary agent and Pd as the main active component are generally used. However, due to the fact that Ag is very easy to agglomerate, covering the Pd particles, resulting in problems such as loss of hydrogenation activity of the catalyst. Moreover, the current alkyne selective hydrogenation catalysts also have defects such as insufficient olefin selectivity and short regeneration cycle. Therefore, there is an urgent need to develop selective hydrogenation catalysts with good reaction activity, high olefin selectivity, and capable of operating stably for a long time. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of unsatisfactory reaction activity, olefin selectivity, and regeneration cycle of the alkyne selective hydrogenation catalyst existing in the prior art, and to provide a catalyst support, an alkyne selective hydrogenation catalyst, and their preparation methods and applications. In the catalyst support provided by the present invention, Ag and Re are innovatively used as doping components, and by using their synergistic effect, the dispersion of Ag is effectively improved. When using this support to prepare a selective hydrogenation catalyst, especially when preparing a selective hydrogenation catalyst with Pd as the main active component, Ag and Re can also jointly form a synergistic effect with Pd, effectively improving the olefin selectivity of the catalyst.

[0006] To achieve the above purpose, on the one hand, the present invention provides a catalyst support, the support includes Al2O3 and a doping component, the doping component includes Re oxide and Ag, wherein, in the support, calculated by metal elements, the weight ratio of Ag to Re is 1:1 - 5.

[0007] A second aspect of the present invention provides a method for preparing a catalyst support, the method comprising:

[0008] Step 1: The carrier raw material is first contacted with an acidic aqueous solution and kneaded to form a molding precursor. The carrier raw material contains Ag and Re. The amount of carrier raw material used is such that the weight ratio of Ag to Re in the carrier, calculated as metal elements, is 1:1-5.

[0009] Step 2: The shaped precursor is subjected to a first drying and a first calcination in sequence.

[0010] The third aspect of the present invention provides a catalyst support prepared by the method described in the second aspect.

[0011] A fourth aspect of the present invention provides a selective hydrogenation catalyst for alkynes, the catalyst comprising a support and a main active component and a co-active component supported on the support, wherein the main active component is Pd, and the support is the catalyst support described in the first or third aspect.

[0012] The fifth aspect of the present invention provides a method for preparing a selective hydrogenation catalyst for alkynes, the method comprising loading a main active component and a co-active component onto a support, wherein the main active component is Pd, and the support is the support described in the first aspect or the third aspect.

[0013] The sixth aspect of the present invention provides an alkyne selective hydrogenation catalyst prepared according to the method described in the fifth aspect.

[0014] The seventh aspect of this invention provides the use of the support described in the first or third aspect, and / or the catalyst described in the fifth or sixth aspect, in the selective hydrogenation of alkynes. In particular, its use in the selective hydrogenation of alkynes to prepare olefins.

[0015] The eighth aspect of the present invention provides a method for hydrogenating and refining ethylene stream in a sequential separation process, the method comprising: bringing a reaction gas into a second contact with a catalyst and reacting it under selective hydrogenation conditions, such that acetylene therein is selectively hydrogenated to generate ethylene;

[0016] The reaction gas is obtained by adding H2 and CO to the ethylene stream, wherein the amount of CO used is such that, based on the total amount of the reaction gas, the CO content is 0.002-0.02 mol%.

[0017] The ethylene stream originates from a sequential separation process, wherein the acetylene content is not less than 0.9 mol%; the catalyst is the catalyst described in claim 5 or 6.

[0018] Through the above technical solution, the present invention can achieve at least the following beneficial effects:

[0019] (1) Innovatively, this invention dops Re oxide and Ag in the catalyst support. By utilizing the synergistic effect of the two, the dispersion of Ag is improved on the one hand, and the synergistic effect of Re and Ag with Pd on the other hand, the hydrogenation activity and olefin selectivity of the alkyne selective hydrogenation catalyst prepared by this support are greatly improved.

[0020] (2) The catalyst provided by the present invention can effectively remove high content of acetylene in ethylene stream by selective hydrogenation, and can prevent excessive hydrogenation at high temperature, thereby improving the selectivity of ethylene.

[0021] (3) The ethylene stream hydrogenation refining method provided by the present invention introduces H2 and CO in high concentrations into the ethylene stream. Combined with the catalyst provided by the present invention, it can reduce the temperature rise of the reactor under high acetylene concentration conditions and has ultra-high ethylene selectivity. At the same time, it can also achieve long-term operation, which is very suitable for industrial promotion and application. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the reaction apparatus used in Example 1.

[0023] Explanation of reference numerals in the attached figures

[0024] I. Deethaner column; II. First-stage fixed isothermal bed hydrogenation reactor; III. Second-stage fixed isothermal bed hydrogenation reactor; IV. Third-stage fixed adiabatic bed hydrogenation reactor; V. Ethylene distillation column; VI. Heat exchanger; 1. C2 fraction stream collected from the top of the deethaner column; 2. Hydrogen-rich stream I; 3. Hydrogen-rich stream II. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] In this field, alkyne selective hydrogenation catalysts are typically supported catalysts using the noble metal Pd as the active component and adding effective promoters. Current research on C2 selective hydrogenation catalysts commonly employs Ag as a promoter, enabling Pd-Ag coordination, weakening the adsorption capacity of Pd atoms for ethylene, inhibiting excessive hydrogenation of ethylene, and thus improving ethylene selectivity. However, the inventors have discovered through long-term research that existing catalysts using Pd as the active component and Ag as a promoter suffer from poor Ag dispersion. This results in Ag being distributed in an agglomerated, plate-like pattern on the support surface, easily covering the Pd particle surface. Consequently, these catalysts often exhibit reduced hydrogenation activity, insufficient ethylene selectivity, and the need to improve stable operating cycles.

[0027] Therefore, to further improve the hydrogenation activity and ethylene selectivity of the C2 selective hydrogenation catalyst, it is necessary to improve the distribution state of Ag in the catalyst. However, the inventors found in numerous experiments that, due to its inherent characteristics, Ag is very prone to agglomeration and is difficult to disperse when used as a supported component.

[0028] To address the aforementioned problems, the inventors, through long-term research, ingeniously discovered that Re and Ag have a strong synergistic effect. When Re and Ag are used together in a catalyst, the dispersibility of Ag can be significantly improved. Further research unexpectedly revealed that when Re and Ag are co-incorporated into the support as dopants, it not only prevents the decline in catalyst hydrogenation activity caused by excessive Ag agglomeration and covering of Pd particle surfaces, but also increases the valence of Ag and weakens the degree of Pd-Ag electron transfer, thereby increasing the selectivity of ethylene. In addition, the addition of Re reduces the amount of Ag used in the catalyst, lowering the catalyst cost.

[0029] Based at least on the above findings, a first aspect of the present invention provides a catalyst support comprising Al2O3 and a dopant, wherein the dopant comprises Re oxide and Ag (in this invention, the dopant Ag and Re oxide may be referred to simply as Ag-Re). x O y In the supported material, the weight ratio of Ag to Re, calculated by metal element, is 1:1-5. When the Ag and Re oxides doped in the supported material have the above-mentioned ratio, a C2 selective hydrogenation catalyst with better catalytic activity and catalytic effect can be obtained.

[0030] According to a preferred embodiment of the present invention, the Al2O3 crystal form includes at least one of θ phase, γ phase and α phase, preferably the proportion of θ phase crystal form of Al2O3 is not less than 60%, the proportion of γ phase crystal form is not more than 40%, and the proportion of α phase crystal form is not more than 10%.

[0031] Preferably, the θ phase of the Al2O3 accounts for 65-80%, the γ phase accounts for 10-35%, and the α phase accounts for 1-10%.

[0032] According to a preferred embodiment of the present invention, in the carrier, the weight ratio of Ag to Re, based on metal elements, is 1:1-3.

[0033] Preferably, based on the total weight of the carrier, the content of Ag is 0.2-5% by weight, preferably 1-3% by weight; and the content of Re is 0.2-8% by weight, preferably 1.5-5% by weight.

[0034] In this invention, there are no particular restrictions on the specific type of Re oxide doped in the support, as long as it can provide Re elements to the support and form a synergistic effect with the Ag doped therein. According to a preferred embodiment of the invention, the support comprises at least one Re oxide.

[0035] Preferably, the Re oxide is in the form of Re x O y It represents that x is 1 or 2, and y is any integer from 1 to 7.

[0036] A second aspect of the present invention provides a method for preparing a catalyst support, the method comprising:

[0037] Step 1: The carrier raw material is first contacted with an acidic aqueous solution and kneaded to form a molding precursor. The carrier raw material contains Ag and Re. The amount of carrier raw material used is such that the weight ratio of Ag to Re in the carrier, calculated as metal elements, is 1:1-5.

[0038] Step 2: The shaped precursor is subjected to a first drying and a first calcination in sequence.

[0039] In the above method, step 1 is the process of mixing the raw materials and preparing a molding precursor. The second contact (i.e., the process of mixing the carrier material and the acidic aqueous solution) can be completed before kneading and molding, or it can be carried out during the kneading and molding process. For example, the carrier material and the acidic aqueous solution can be mixed first and then placed in a kneading device for kneading, or the carrier material can be placed directly into the kneading device, and the acidic aqueous solution can be added during the kneading process. After kneading is completed, a molding precursor of the desired shape is prepared.

[0040] According to a preferred embodiment of the present invention, in step 1, the carrier material includes Ag, a Re source, alumina, and an optional molding pore-forming agent. "Optional" means that the molding pore-forming agent is not a necessary component of the carrier material and can be selectively added according to actual conditions.

[0041] Ag and Re sources refer to Ag-Re, which provides doping components to the carrier.x O y The substance is typically a compound containing Ag and / or Re, such as an Ag-containing compound, a Re-containing compound, or a compound containing both Ag and Re. Preferably, the Ag and Re sources are selected from silver perrhenate and / or a mixture of rhenium oxide and silver oxide. That is, the Ag and Re sources can be: (a) silver perrhenate; or, (b) a mixture of rhenium oxide and silver oxide; or (c) a mixture of silver perrhenate and rhenium oxide and / or silver oxide. The rhenium oxide can be a rhenium oxide of any valence state, or a mixture of rhenium oxides of multiple valence states. Preferably, the rhenium oxide is selected from at least one of ReO4, ReO7, ReO3, Re2O5, ReO2, Re2O3, ReO, and Re2O, more preferably from at least one of Re2O7, ReO3, and ReO2.

[0042] In the method provided by the present invention, the amount of Ag and Re source used results in the Ag and Re content and their weight ratio in the carrier as described above, and will not be repeated here.

[0043] According to a preferred embodiment of the present invention, the alumina comprises boehmite and optionally alumina powder. Preferably, the alumina powder is obtained by calcining boehmite at 800-900°C.

[0044] Preferably, the content of alumina powder is 0-20% by weight, based on the total weight of the alumina.

[0045] Forming and pore-forming agents refer to a class of additives used in the preparation of shaped catalysts (supports) to facilitate the shaping of the support raw materials. Any forming and pore-forming agent suitable for use in selective hydrogenation catalysts is applicable to this invention. According to a preferred embodiment of the invention, the forming and pore-forming agent in the support raw materials is selected from at least one of guar gum powder, starch, cellulose and / or cellulose derivatives, urea, ethylenediamine, and high molecular weight polymers. Preferably, the amount of the forming and pore-forming agent is 0-10% by weight based on the total weight of the alumina.

[0046] Preferably, the cellulose derivative is selected from at least one of methylcellulose, hydroxymethylcellulose, and hydroxypropyl methylcellulose and their salts.

[0047] Preferably, the polymer is selected from at least one of polyethylene (e.g., polyethylene microspheres), polystyrene, polyethylene glycol, polyvinyl alcohol, and polyethylene glycol.

[0048] According to a preferred embodiment of the present invention, in step 1, the acidic aqueous solution includes perrhenic acid and other acids, wherein the other acids include at least one of nitric acid, acetic acid, oxalic acid and citric acid.

[0049] Preferably, in the acidic aqueous solution, the weight ratio of perrhenic acid to other acids is 0.2-10:1, more preferably 0.2-3:1. For example, it can be 0.2:1, 0.5:1, 0.8:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 3:1, or any intermediate ratio within the range formed by any two of the above ratios.

[0050] Preferably, the weight ratio of the acidic aqueous solution to the carrier raw material is 0.4-2:1, more preferably 1-2:1. For example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, or any intermediate ratio within the range formed by any two of the above ratios.

[0051] Preferably, the particle size of the shaped precursor is 1-10 mm. In this invention, any shape commonly used in the art for shaping selective hydrogenation catalysts can be used to prepare the shaped precursor, such as sheet-like, (quasi-)spherical, cylindrical, cubic, toothed spherical, or clover-shaped irregular shapes.

[0052] In this invention, when silver perrhenate is used as the Ag and Re source in step 1 to prepare the carrier used in this invention, the finished silver perrhenate product obtained directly through commercial purchase or customization can be used, or the silver perrhenate product prepared by ourselves can be used.

[0053] According to a preferred embodiment of the present invention, the silver perrhenate can be prepared by a method comprising the following steps:

[0054] (a) Under stirring conditions, an aqueous solution containing Ag was brought into a third contact with an aqueous solution containing perrhenate to obtain a (white) precipitate;

[0055] (b) The (white) precipitate is separated and dried.

[0056] Preferably, in step (a), the Ag-containing aqueous solution can be an aqueous solution of any water-soluble Ag salt, preferably a silver nitrate solution. The present invention does not impose any particular limitation on the concentration of the Ag-containing aqueous solution, as long as it facilitates a third contact with the perrhenate-containing aqueous solution to produce a precipitate (i.e., silver perrhenate).

[0057] Preferably, in step (a), the aqueous solution containing perrhenate can be a mixed solution of perrhenic acid or its salt and other acids, or it can be an ammonium perrhenate solution. The other acids are preferably nitric acid.

[0058] More preferably, in step (a), the Ag provided by the Ag-containing aqueous solution + ReO4 provided by aqueous solutions containing perrhenate - The molar ratio is 0.8-1.2:1.

[0059] Preferably, in step (a), the third contact is carried out under heating conditions, preferably heating the reaction system to a temperature of 30-50°C.

[0060] Preferably, in step (a), the third contact method includes: adding an aqueous solution containing Ag dropwise to an aqueous solution containing perrhenate.

[0061] More preferably, in step (a), the third contact further includes: stopping stirring after all the Ag-containing aqueous solution has been added, and allowing the reaction system to stand under heating conditions for 20-60 minutes before stopping heating (preferably the heating conditions during the standing process are such that the temperature difference between the reaction system and the temperature during the dropping process does not exceed 3°C), and then allowing it to stand and cool to room temperature (25±5°C).

[0062] In the above method, the (white) precipitate obtained in step (a) is silver perrhenate precipitate. Step (b) is the process of obtaining silver perrhenate from the reaction system. To avoid other compounds in the reaction system adhering to the silver perrhenate and affecting the performance of the support or catalyst, the separated silver perrhenate precipitate can be washed before drying. Typically, the washing can be performed using an organic solvent, such as diethyl ether.

[0063] In step (b), the separation can be performed using any solid-liquid separation method commonly used in the art. For example, it can be performed using filtration, vacuum filtration, centrifugation, etc.

[0064] In step (b), the drying method can be any commonly used drying method in the art, as long as the conditions do not destroy the existing form of silver perrhenate (e.g., do not cause it to undergo oxidation, decomposition, or other reactions to form other compounds). For example, vacuum drying can be carried out at 50-100°C.

[0065] In this invention, there are no particular restrictions on the specific operation methods and conditions in step 2, as long as they enable the obtained carrier to have the aforementioned characteristics.

[0066] According to a preferred embodiment of the present invention, in step 2, the conditions for the first drying include: a temperature of 60-120°C and a time of 8-24 hours.

[0067] Preferably, the conditions for the first drying include: a temperature of 100-120°C and a time of 8-20 hours.

[0068] And / or, the first calcination method includes calcination in an atmosphere with an oxygen content not exceeding 40% by weight, preferably in an atmosphere with an oxygen content of 15-25% by weight, preferably said atmosphere is provided by a gas including at least one of an inert gas, nitrogen, and oxygen. For example, said atmosphere may be provided by a mixture of oxygen and an inert gas and / or nitrogen, or it may be provided by air, as long as the oxygen content therein meets the above requirements.

[0069] Preferably, the pressure of the first calcination is 2-5 MPa, and more preferably 3-4 MPa.

[0070] Preferably, the first roasting temperature is 500-900℃, and more preferably 550-800℃. For example, it can be 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, or any intermediate value within the range of any two of the above values.

[0071] Preferably, the first roasting time is 4-20 hours, and more preferably 6-10 hours.

[0072] A third aspect of the present invention provides a catalyst support prepared according to the method described in the second aspect.

[0073] A fourth aspect of the present invention provides a selective hydrogenation catalyst for alkynes, the catalyst comprising a support and a main active component and a co-active component supported on the support, wherein the main active component is Pd, and the support is the catalyst support described in the first or third aspect.

[0074] In the catalyst provided by this invention, there is no particular limitation on the loading amount of the active component Pd, as long as the hydrogenation activity of the catalyst can reach a relatively ideal level. Due to the synergistic effect between the Ag and Re oxides doped in the support provided by this invention and Pd, the catalytic activity of Pd can be effectively improved. Therefore, in the catalyst provided by this invention, Pd can be present in a relatively low loading amount.

[0075] According to some preferred embodiments of the present invention, the Pd content, based on the total weight of the carrier, is 0.002-0.2 wt%, preferably 0.01-0.15 wt%, more preferably 0.05-0.15 wt%. For example, it can be 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, or any intermediate value within the range of any two of the above values.

[0076] Preferably, the weight ratio of Pd to Ag, based on elemental composition, is 1:10-60, more preferably 1:20-45. For example, it can be 1:20, 1:22, 1:25, 1:28, 1:30, 1:32, 1:35, 1:38, 1:40, 1:42, or any intermediate ratio within the range formed by any two of the above ratios.

[0077] Preferably, the weight ratio of Pd to the total weight of Ag and Re in the carrier, based on elemental composition, is 1:50-100, more preferably 1:70-100. For example, it can be 1:70, 1:72, 1:75, 1:78, 1:80, 1:82, 1:85, 1:88, 1:90, 1:92, 1:95, 1:98, 1:100, or any intermediate ratio within the range formed by any two of the above ratios.

[0078] In the selective hydrogenation catalyst provided by the present invention, the co-activating component can be any element that can further improve the catalytic activity (e.g., conversion rate, ethylene selectivity, etc.) of the Pd-supported C2 selective hydrogenation catalyst.

[0079] According to some preferred embodiments of the present invention, the co-active component is selected from at least one of Group VIII elements, alkali metal elements, alkaline earth metal elements, Group IIIA elements, Group IB elements, Group IIB elements, Group VA elements, rare earth elements, and halogen elements, which are different from Pd.

[0080] Preferably, the auxiliary active component is selected from at least one of Ga, In, La, Ni, Zn, Fe, Bi, Sn, Y and Mn.

[0081] In this invention, there are no particular restrictions on the loading amount of the co-active component, which can be selected and adjusted according to specific circumstances (such as the selection of the co-active component, the required reactivity and effect, etc.).

[0082] Preferably, the content of the active ingredient, based on the total weight of the carrier, is 0-5% by weight, preferably 0.01-1% by weight. For example, it can be 0.01% by weight, 0.05% by weight, 0.1% by weight, 0.15% by weight, 0.2% by weight, 0.25% by weight, 0.3% by weight, 0.35% by weight, 0.4% by weight, 0.45% by weight, 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, 0.9% by weight, 1% by weight, or any intermediate value within the range of any two of the above values.

[0083] To improve the catalytic activity and ethylene selectivity of the catalyst, preferably, the weight ratio of the co-active component to Pd is 0.5-1.5:1 (elementally). For example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, or any intermediate ratio within the range formed by any two of the above ratios.

[0084] The fifth aspect of the present invention provides a method for preparing a selective hydrogenation catalyst for alkynes, the method comprising loading a main active component and a co-active component onto a support, wherein the main active component is Pd, and the support is the support described in the first aspect or the third aspect.

[0085] In the method provided by this invention, the specific amounts of the main active component Pd and the co-active components, the preferred proportions of different components in the catalyst, and the specific selection of the co-active components are as described above and will not be repeated here.

[0086] According to a preferred embodiment of the present invention, the loading method includes loading the active component precursor and the co-active component precursor onto the carrier by spraying or impregnation, followed by a second drying and a second calcination.

[0087] The active component precursor is a compound that can provide the active component Pd to the catalyst. Preferably, the active component precursor is selected from at least one of water-soluble inorganic salts of palladium (e.g., palladium nitrate), palladium oxides, and organometallic compounds of palladium (e.g., palladium acetate).

[0088] The precursor of the co-active component is a compound that can provide the aforementioned co-active component to the catalyst. Preferably, the precursor of the co-active component is selected from at least one of the following: a water-soluble inorganic salt of the co-active component (e.g., a sulfate, nitrate, carbonate, halide, ammonium compound of the co-active component), a hydroxide of the co-active component, and an organometallic compound of the co-active component (e.g., an acetate of the co-active component).

[0089] In the above method, the amount of the active component precursor and the co-active component precursor is such that the content and ratio of the active component and the co-active component in the obtained catalyst meet the aforementioned requirements, which will not be repeated here.

[0090] According to a preferred embodiment of the present invention, the conditions for the second drying include a temperature of 60-160°C.

[0091] According to a preferred embodiment of the present invention, the conditions for the second calcination include a temperature of 300-600°C. Preferably, the second calcination is carried out in an atmosphere containing at least one of an inert gas and nitrogen. For example, the second calcination can be carried out in an air atmosphere.

[0092] The sixth aspect of the present invention provides a selective hydrogenation catalyst for alkynes prepared according to the method of the fifth aspect of the invention.

[0093] The seventh aspect of this invention provides the use of the support described in the first or third aspect, and / or the catalyst described in the fourth or sixth aspect, in the selective hydrogenation of alkynes. In particular, it is used in the selective hydrogenation of alkynes to prepare olefins (e.g., the selective hydrogenation of acetylene to prepare ethylene).

[0094] Through long-term research, the inventors of this invention have discovered that the ethylene selectivity of post-C2 hydrogenation reactors in current industrial plants is generally below 50%. Improving catalyst performance and optimizing the process can both enhance the ethylene selectivity of post-C2 hydrogenation reactors to a certain extent.

[0095] Currently, in sequential process technologies, besides the main methods of hydrogen and temperature control, a low concentration of CO (approximately 0.1-2 ppm) is introduced into the C2 fraction feedstock via the addition of crude gas to improve ethylene selectivity. However, this method requires increasing the reactor inlet temperature for hydrogenation activity compensation, and to prevent catalyst deactivation, the maximum CO concentration in the C2 hydrogenation reactor cannot exceed 5 ppm. This means that post-hydrogenation processes that use CO to improve ethylene selectivity require strict control and management of the CO concentration, and also increase energy consumption, making them unsuitable for industrial application.

[0096] Through extensive research, the inventors of this invention have innovatively discovered that the catalyst in the C2 post-hydrogenation reactor can be used for hydrogenation at higher CO concentrations under high hydrogen conditions. Based on this, they developed a high CO post-hydrogenation process, which achieves good acetylene removal capability and superior ethylene selectivity.

[0097] Building upon this foundation, the inventors of this invention, through extensive experimentation, have discovered that the selective hydrogenation catalyst provided by this invention, combined with a specific high-CO post-hydrogenation process, can achieve highly efficient and selective hydrogenation of acetylene under high space velocity conditions, while obtaining extremely high ethylene selectivity. This not only achieves good acetylene removal and ethylene selectivity but also improves the overall production efficiency of the post-C2 hydrogenation process and the petroleum cracking process for ethylene production. This approach of using a specific process with a specific catalyst significantly improves the performance of the C2 post-hydrogenation process compared to simply adjusting the catalyst or optimizing the process. Furthermore, the catalyst provided by this invention not only exhibits excellent catalytic performance under these process conditions but also operates stably for a longer period, reducing the cost and environmental pressure associated with frequent catalyst regeneration, thus better aligning with the needs of green and sustainable development.

[0098] In this invention, the "high-CO C2 post-hydrogenation process (also abbreviated as "high-CO post-hydrogenation process" or "high-CO process") refers to a post-hydrogenation process in which a higher concentration of CO is introduced into the reactor, which can significantly improve the selectivity of ethylene obtained by the selective hydrogenation reaction of acetylene.

[0099] The eighth aspect of the present invention provides a method for hydrogenating and refining ethylene stream in a sequential separation process, the method comprising: bringing a reaction gas into a second contact with a catalyst and reacting it under selective hydrogenation conditions, such that acetylene therein is selectively hydrogenated to generate ethylene;

[0100] The reaction gas is obtained by adding H2 and CO to the ethylene stream, wherein the amount of CO used is such that, based on the total amount of the reaction gas, the CO content is 0.002-0.02 mol%.

[0101] The ethylene stream originates from a sequential separation process, wherein the acetylene content is not less than 0.9 mol%; the catalyst is the catalyst described in claim 4 or 6.

[0102] The inventors of this invention also discovered in their research that when selectively hydrogenating acetylene in C2 fractions using the above method, a better hydrogenation effect can be obtained when the CO content in the reaction gas is relatively stable (i.e., the CO content in the reaction gas fluctuates less).

[0103] According to a preferred embodiment of the present invention, the CO content in the reaction gas fluctuates by no more than 20%, preferably no more than 10%, and more preferably no more than 5%. For example, a CO content fluctuation of 20% means that the actual CO content in the reaction gas is a set value ± 20%. The actual CO content in the reaction gas can be obtained by installing a gas component detection device (such as a gas chromatograph) at the reactor inlet and detecting the components of the introduced reaction gas during the reaction process (such as real-time monitoring or periodic / irregular sampling).

[0104] The inventors of this invention also discovered during their research that the method provided by this invention can achieve better reaction results when operating with a specific reactor.

[0105] According to a preferred embodiment of the present invention, the second contact is carried out in a combined hydrogenation reactor comprising an isothermal bed and an adiabatic bed. Preferably, the combined hydrogenation reactor comprises at least one isothermal bed hydrogenation reactor and an adiabatic bed hydrogenation reactor connected in series. In the method of the present invention, the number of isothermal bed reactors is typically determined by the acetylene content in the reaction gas; the higher the acetylene content, the more isothermal bed reactors are required to ensure that the acetylene removal rate reaches an ideal level. That is, the combined hydrogenation reactor may include, in series: a first isothermal bed hydrogenation reactor, a second isothermal bed hydrogenation reactor, ..., an Nth isothermal bed hydrogenation reactor, and an adiabatic bed hydrogenation reactor. Preferably, the at least one isothermal bed hydrogenation reactor comprises 1-5 single-stage isothermal bed hydrogenation reactors.

[0106] Preferably, in an isothermal bed reactor, the temperature rise from the inlet to the outlet does not exceed 15°C. When a multi-stage isothermal bed reactor is used, the temperature rise from the inlet to the outlet refers to the temperature rise from the inlet to the outlet of each isothermal bed stage.

[0107] In the method provided by the present invention, pure H2 and / or CO can be directly incorporated into the ethylene stream according to the aforementioned requirements to form the reaction gas, or a stream containing H2 and / or CO and other gases can be incorporated into the ethylene stream to provide H2 and / or CO, wherein the other gases refer to gaseous components that will not react with the various components in the ethylene stream.

[0108] According to a preferred embodiment of the present invention, wherein, and / or, the H2 and / or CO may be provided by a hydrogen-rich gas stream I, preferably the hydrogen-rich gas stream I contains CO, H2, CH4 and optionally C2H4.

[0109] Preferably, in the hydrogen-rich gas stream I, the H2 content is not less than 85 mol%, preferably not less than 90 mol%, and more preferably not less than 94 mol%. For example, it can be 94 mol%, 95 mol%, 96 mol%, 97 mol%, 98 mol%, 99 mol%, 99.5 mol%, 99.6 mol%, 99.7 mol%, 99.8 mol%, or 99.9 mol%, or any intermediate value within the range of any two of the above values.

[0110] Preferably, in the hydrogen-rich gas stream I, the CO content is 0.1-5 mol%, more preferably 0.2-3 mol%, and even more preferably 0.25-2 mol%. For example, it can be 0.25 mol%, 0.5 mol%, 0.75 mol%, 1 mol%, 1.25 mol%, 1.5 mol%, 1.75 mol%, 2 mol%, or any intermediate value within the range of any two of the above values.

[0111] More preferably, the hydrogen-rich gas stream I originates from an external hydrogen production unit and / or a separation system preceding a stationary adiabatic hydrogenation reactor. For example, pure hydrogen can be produced by an external hydrogen production unit and then mixed with a CO-containing gas stream obtained from a separation system in a sequential separation process, so that the H2 and CO contents meet the aforementioned requirements, thus obtaining the hydrogen-rich gas stream I.

[0112] In this invention, the reactant gas introduced into the adiabatic bed hydrogenation reactor mainly comes from the C2 fraction stream from the top of the ethane column in the sequential separation process. This stream typically contains ethane, ethylene, and a small amount of acetylene. In addition, it may also contain small amounts of methane, propane, propylene, etc. The method provided by this invention does not impose any particular limitation on the specific content of each component in the C2 stream. According to a preferred embodiment of the invention, the acetylene content, based on the total amount of the ethylene stream, does not exceed 5 mol%.

[0113] Preferably, based on the total amount of the ethylene stream, the ethylene content is 70-97 mol%, the ethane content is 2-30 mol%, the acetylene content is 1-3.5 mol%, the methane content is 0-0.5 mol%, the propane content is 0-1 mol%, and the propylene content is 0-2 mol%. In the C2 fraction stream, the acetylene content can be 1 mol%, 1.2 mol%, 1.5 mol%, 1.8 mol%, 2 mol%, 2.2 mol%, 2.5 mol%, 2.8 mol%, 3 mol%, 3.2 mol%, or 3.5 mol%, or any intermediate value within the range of any two of the above values.

[0114] According to a preferred embodiment of the present invention, the selective hydrogenation conditions include: a pressure of 1-4 MPa and a space velocity of 9000-25000 m / s in the ethylene stream of the isothermal bed hydrogenation reactor. 3 ·(m 3 ) -1 ·h -1 The space velocity of the ethylene stream in the adiabatic bed hydrogenation reactor is 3000-15000 m / s. 3 ·(m 3 ) -1 ·h -1 .

[0115] Preferably, the temperature of the selective hydrogenation is such that the acetylene content in the outlet stream of the adiabatic bed hydrogenation reactor does not exceed 10 ppm, more preferably not more than 5 ppm, and even more preferably not more than 1 ppm.

[0116] More preferably, the selective hydrogenation temperature is 20-80°C. In this invention, the selective hydrogenation temperature changes dynamically during the reaction process to ensure that the acetylene content in the reactor outlet stream meets the aforementioned requirements. Therefore, the "selective hydrogenation temperature" in this invention refers to the range of temperature variation at the reactor inlet for each section (including the adiabatic bed and the isothermal bed) during the reaction process (e.g., during the reaction cycle).

[0117] The inventors also discovered in their research that, in the high-CO process of this invention, maintaining a certain level of H2 content in the reaction gas introduced into the inlet of each hydrogenation reactor (including the adiabatic bed and the isothermal bed) is necessary to achieve better hydrogenation results and higher ethylene selectivity. Therefore, a certain amount of H2 can be added before the reaction gas is introduced into each reactor stage to ensure that the H2 content in the gas stream introduced into each reactor stage reaches a (basically) the same level.

[0118] Preferably, the method further includes: introducing an optional hydrogen-rich gas stream II into each stage of the hydrogenation reactor, such that the hydrogen content in the inlet stream of each stage of the hydrogenation reactor is 2-10 mol%, preferably 2-8 mol%, more preferably 4-6 mol%. Typically, when using a multi-stage series isothermal bed reactor, the above-mentioned method of introducing hydrogen-rich gas stream II can be used in the isothermal and adiabatic beds after the second stage. When using a single-stage isothermal bed series adiabatic bed reactor, the composition of hydrogen-rich gas stream I can be directly adjusted to achieve the aforementioned requirements for the H2 and CO content in the reaction gas introduced into the isothermal bed. Alternatively, hydrogen-rich gas stream I can be incorporated into the C2 fraction stream, and then hydrogen-rich gas stream II can be introduced before the isothermal bed inlet to adjust the composition of the reaction gas entering the isothermal bed.

[0119] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0120] Unless otherwise specified, the reagents used in the following examples are all commercially available products purchased from legitimate chemical suppliers and are of analytical purity.

[0121] In the following examples, the acetylene content at the reactor outlet was measured using a gas chromatograph (Agilent 7890); the reactor bed temperature was measured using a thermocouple.

[0122] Unless otherwise specified, the silver perrhenate used in the following examples was prepared by the following method:

[0123] (a) Weigh 10g of silver nitrate powder and dissolve it in 20mL of deionized water to obtain an aqueous solution of silver nitrate; weigh 15g of ammonium perrhenate and dissolve it in 50mL of deionized water to obtain an aqueous solution of ammonium perrhenate.

[0124] At 40°C, under stirring, an aqueous solution of silver nitrate was added dropwise to an aqueous solution of ammonium perrhenate, producing a white precipitate. After all the silver nitrate solution had been added, stirring was stopped, and the mixture was allowed to stand at 40°C for 30 minutes. Heating was then stopped, and the mixture was allowed to cool naturally to room temperature.

[0125] (b) The product of step (a) was filtered to obtain a white precipitate, which was washed three times with ether and then dried under vacuum at 80°C to obtain silver perrhenate.

[0126] In the following examples, all pressures are gauge pressures. Unless otherwise specified, all operating pressures are atmospheric pressure, and all temperatures are room temperature (25±5℃). The oxygen content of the air atmosphere is 21±1% by weight. 1 ppm = 0.0001 mol%.

[0127] Preparation Example 1

[0128] Preparation of carriers:

[0129] Step 1: Weigh 200g of boehmite powder, 13.3g of silver perrhenate, 4g of guar gum powder, 4g of methylcellulose, and 4g of polyethylene microspheres respectively, and mix them in a mixer to obtain a uniform powdered raw material.

[0130] Weigh out 1.5g of concentrated nitric acid and 2g of 75% perrhenic acid, add them to 200g of deionized water, and prepare an acidic aqueous solution.

[0131] The uniform powdered raw material is transferred into a kneader, and an acidic aqueous solution is slowly added. After kneading for 1 hour, it is extruded and granulated to obtain a toothed spherical molding precursor (particle size 4-5 mm).

[0132] Step 2: The molding precursor obtained in Step 1 is subjected to a first drying (110℃, 16h), followed by a first calcination in air (3MPa, 680℃, 4h) to obtain Al2O3-Ag-Re. x O y The support, denoted as support A1, was analyzed by XPS. It was found that Ag existed in elemental form, and Re was a mixture of oxides in various valence states (mainly including: ReO2, 8.1 mol%; ReO3, 7.6 mol%; Re2O7, 84.3 mol%). Preparation of selective hydrogenation catalyst:

[0133] Pd(NO3)2 and Ga(NO3)3 were weighed separately and dissolved in deionized water to prepare an aqueous solution containing 0.15 g Pd and 0.15 g Ga as the impregnation solution. The support A1 was impregnated in 100 mL of this impregnation solution (52 °C, 15 min). The impregnated support A1 was then removed, subjected to a second drying process (140 °C, 8 h), and then subjected to a second calcination in air (320 °C, 12 h) to obtain Pd-Ga / Al2O3-Ag-Re. x O y Catalyst, denoted as TM-1.

[0134] Preparation Example 2

[0135] Preparation of carriers:

[0136] Step 1: Weigh 200g of boehmite powder, 6.9g of silver oxide, 4.7g of rhenium dioxide, 5g of guar gum powder, 7g of hydroxypropyl methylcellulose, and 2g of polyvinyl alcohol, respectively, and mix them in a mixer to obtain a uniform powdered raw material.

[0137] Weigh out 3g of citric acid and 3.7g of 75% perrhenic acid, add them to 180g of deionized water to prepare an acidic aqueous solution;

[0138] The uniform powdered raw material is transferred into a kneader, and an acidic aqueous solution is slowly added. After kneading for 2 hours, it is extruded and granulated to obtain a cylindrical molding precursor (particle size 3-4 mm).

[0139] Step 2: The molding precursor obtained in Step 1 is subjected to a first drying (120℃, 8h), followed by a first calcination in air (3MPa, 780℃, 6h) to obtain Al2O3-Ag-Re. x O y The support, denoted as support A2, was found by XPS analysis to contain Ag in elemental form and Re as a mixture of oxides in various valence states (mainly including ReO2, 61.4 mol%; ReO3, 11.5 mol%; Re2O7, 27.1 mol%).

[0140] Preparation of selective hydrogenation catalysts:

[0141] Pd(Cl)₂ and ZnCl₂ were weighed separately and dissolved in deionized water to prepare an aqueous solution containing 0.15 g Pd and 0.15 g Zn as the impregnation solution. The carrier A6 was impregnated in 100 mL of this impregnation solution (32℃, 25 min). The impregnated carrier A6 was then removed, subjected to a second drying (120℃, 8 h), and then subjected to a second calcination in air (380℃, 12 h) to obtain Pd-Zn / Al₂O₃-Ag-Re. x O yThe catalyst is designated TM-2.

[0142] Comparative Preparation Example 1

[0143] Preparation of carriers:

[0144] Step 1: Weigh 200g of boehmite powder, 10g of guar gum powder, and 5g of starch separately, and put them into a mixer to mix them to obtain a uniform powdered raw material;

[0145] Weigh out 2g of concentrated nitric acid and 2g of citric acid, add them to 150g of deionized water, and prepare an acidic aqueous solution.

[0146] The uniform powdered raw material is transferred into a kneader, and an acidic aqueous solution is slowly added. After kneading for 2 hours, it is extruded and granulated to obtain a cylindrical molding precursor (particle size 4-5 mm).

[0147] Step 2: The molding precursor obtained in Step 1 is subjected to a first drying (120℃, 8h), and then subjected to a first calcination in air atmosphere (atmospheric pressure, 1000℃, 6h) to obtain an Al2O3 support, denoted as support D1.

[0148] Preparation of selective hydrogenation catalysts:

[0149] Pd(NO3)2 and AgNO3 were weighed separately and dissolved in deionized water to prepare an aqueous solution containing 0.15 g Pd and 1 g Ag as the impregnation solution. Support D1 was impregnated in 100 mL of this impregnation solution (25 °C, 5 min). The impregnated support D1 was then removed and subjected to a second drying process (120 °C, 8 h), followed by a second calcination in air (320 °C, 12 h) to obtain the Pd-Ag / Al2O3 catalyst, denoted as QM.

[0150] Test Example 1

[0151] XRD analysis was used to determine the crystal form and proportion of alumina in the catalyst supports obtained in the above preparation examples. The contents of Ag and Re dopants in the catalyst supports obtained in the above preparation examples were calculated based on the amount of raw materials used in the supports. The contents of the supported components of the selective hydrogenation catalysts obtained in the above preparation examples were calculated based on the contents of the active components and co-active components in the impregnation solution. The contents of Ag, Re, and the catalyst supported components (Pd and co-active components) are all calculated as elements, based on the total weight of the supports. The results are detailed in Table 1.

[0152] Table 1

[0153]

[0154] Example 1

[0155] This embodiment is used to illustrate the effect of the ethylene stream hydrogenation refining method provided by the present invention.

[0156] In this embodiment, the ethylene stream originates from the ethylene stream drawn from the top of the deethaner column, while both hydrogen-rich stream I and hydrogen-rich stream II originate from actual materials in the industrial plant. The composition of these streams is shown in Table 2.

[0157] Table 2

[0158]

[0159] The structure adopted is as follows Figure 1 The reaction apparatus shown was used to test the hydrorefining effect of the method provided by this invention under different process conditions. (Reference) Figure 1 As can be seen, the process route in this embodiment mainly includes: the ethylene stream (1) collected from the top of the deethaner (I) is mixed with hydrogen-rich stream I (2) and hydrogen-rich stream II (3) and then enters a first-stage fixed isothermal bed hydrogenation reactor (II). The first-stage fixed isothermal bed hydrogenation reactor (II) is connected in series with the second-stage fixed isothermal bed hydrogenation reactor (III) and the third-stage fixed adiabatic bed hydrogenation reactor (IV). A heat exchanger (VI) is also installed between adjacent reactors. Hydrogen-rich stream II (3) is introduced into the inlet of each reactor to ensure that the hydrogen content in the reaction gas introduced into the inlet of each reactor reaches the set value. Finally, the outlet stream of the third-stage fixed adiabatic bed hydrogenation reactor (IV) enters the ethylene distillation tower (V). The specific hydrogenation refining process conditions are as follows:

[0160] In each reactor section, the catalyst loading was 50 ml, and the ethylene stream space velocity in the isothermal bed was 15000 m / s at a pressure of 2.1 MPa. 3 ·(m 3 ) -1 ·h -1 The space velocity of the ethylene stream in the adiabatic bed is 7000 m / s. 3 ·(m 3 ) -1 ·h -1 Under certain conditions, hydrogen-rich gas stream I was injected into the ethylene stream to obtain the reaction gas. The amount of hydrogen-rich gas stream I was used to ensure that the CO content in the reaction gas introduced into the inlet of one reactor section was 20 ppm, 50 ppm, 100 ppm, and 200 ppm, respectively. Hydrogen-rich gas stream II was quantitatively injected before the inlet of each reactor section to maintain the H2 content in the reaction gas introduced into the inlet of each reactor section at the same set value level, which was 2 mol%, 5 mol%, and 8 mol%, respectively.

[0161] During the side-stream evaluation, the temperature of each reactor section was controlled via heat exchangers (dynamically controlled within the reactor temperature range of 20-80℃ during the reaction). The temperature rise in each reactor section is shown in Table 5 (temperature rise = reactor outlet stream temperature - reactor inlet stream temperature). The acetylene content at the inlet and outlet (calculated based on the hydrocarbon composition of the material) was ensured as shown in Table 3. The performance of catalysts TM-1, TM-2, and QM was compared under various operating conditions; the results are detailed in Table 4.

[0162] Table 3

[0163] reactor A section Second section Three sections Inlet acetylene (mol%) 2.05 1 0.25 Exported acetylene (mol%) 1 0.25 <1ppm

[0164] Table 4

[0165]

[0166] Table 5

[0167]

[0168] *When the temperature rise of the first and second stage reactors reaches 15°C and the temperature rise of the third stage reactor reaches 18°C, the reactor temperature rise will no longer be increased. Since QM still cannot make the acetylene content in the gas stream at the outlet of the final stage reactor qualified (below 1ppm) under such temperature rise conditions, it indicates that the catalyst is not suitable for use in the high CO process of this invention.

[0169] Comparative Example 1

[0170] The method described in Example 1 was adopted, except that hydrogen-rich gas stream II was used instead of hydrogen-rich gas stream I in the C2 fraction stream and introduced into the inlet of the first isothermal bed. The temperature of each reactor section was controlled by heat exchangers (see Table 7 for specific temperature rise in the reactors) to ensure that the acetylene content (calculated based on the hydrocarbon composition of the material) at the inlet and outlet of each reactor section was consistent with that in Example 1. The performance of catalysts TM-1, TM-2, and QM under this condition was compared, and the results are detailed in Table 6.

[0171] Table 6

[0172]

[0173] Table 7

[0174]

[0175] Example 2

[0176] This embodiment is used to illustrate the effect of the ethylene stream hydrogenation refining method provided by the present invention.

[0177] In this embodiment, the ethylene stream comes from the top of the deethanizer tower, and its composition is shown in Table 8. The compositions of the hydrogen-rich streams I and II are shown in Table 2.

[0178] Table 8

[0179]

[0180] The side-stream reactor employs a two-stage bed reactor design, with one stage being an isothermal bed and the second stage an adiabatic bed. Each stage is loaded with 50 ml of catalyst, and the pressure is 2.1 MPa, with an ethylene stream space velocity of 18000 m⁻¹ in the isothermal bed. 3 ·(m 3 ) -1 ·h -1 The space velocity of the ethylene stream in the adiabatic bed is 7000 m / s. 3 ·(m 3 ) -1 ·h -1 Under certain conditions, hydrogen-rich gas stream I was injected into the ethylene stream to obtain the reaction gas. The amount of hydrogen-rich gas stream I was used so that the CO content in the reaction gas was 50 ppm, 100 ppm, and 150 ppm, respectively. Hydrogen-rich gas stream II was quantitatively injected before the inlet of each reactor section so that the H2 content in the reaction gas introduced into each reactor section was 3 mol% and 5 mol%, respectively.

[0181] During the side-stream evaluation, the reactor temperature was controlled via heat exchanger (dynamically controlled within the range of 20-80℃ during the reaction; see Table 11 for the temperature rise in the reactor) to ensure the outlet acetylene content (calculated based on the hydrocarbon composition of the material) as shown in Table 9. The performance of catalysts TM-1, TM-2, and QM under various operating conditions was compared, and the results are detailed in Table 10.

[0182] Table 9

[0183] reactor A section Second section Inlet acetylene (mol%) 1.24 0.3 Exported acetylene (mol%) 0.3 <1ppm

[0184] Table 10

[0185]

[0186] Table 11

[0187]

[0188] *When the temperature rise of the first and second stage reactors reaches 15°C, the reactor temperature rise will not be increased further. Since QM still cannot make the acetylene content in the gas stream at the outlet of the final stage reactor qualified (below 1ppm) under such temperature rise conditions, it indicates that the catalyst is not suitable for use in the high CO process of this invention.

[0189] Comparative Example 2

[0190] The method described in Example 2 was used, except that hydrogen-rich gas stream II was injected into the C2 fraction stream instead of hydrogen-rich gas stream I and introduced into the inlet of the isothermal bed reactor. The reactor temperature was controlled by a heat exchanger (see Table 13 for reactor temperature rise) to ensure that the acetylene content at the reactor inlet and outlet was consistent with that in Example 2. The performance of catalysts TM-1, TM-2, and QM under this condition was compared, and the results are detailed in Table 12.

[0191] Table 12

[0192]

[0193] Table 13

[0194]

[0195] The results of the above examples and comparative examples show that the selective hydrogenation catalyst prepared using the catalyst support provided by the present invention can be well adapted to the high CO post-hydrogenation process of the present invention, and can effectively improve ethylene selectivity. Through the combination of this specific catalyst and specific selective hydrogenation method, it can also have ultra-high ethylene selectivity and long cycle operation capability under high space velocity conditions. It not only effectively improves production efficiency, but also reduces the economic cost and environmental pressure caused by frequent catalyst regeneration, and can meet the requirements of green and sustainable industrial production, thus having extremely high industrial application potential and application value.

[0196] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst support, characterized in that, The support comprises Al2O3 and dopant, the dopant comprising Re oxide and Ag, wherein, based on metal elements, the weight ratio of Ag to Re in the support is 1:1-5; The Ag content is 1-3% by weight based on the total weight of the carrier. The Al2O3 crystal forms include θ phase, γ phase and α phase, with the α phase accounting for no more than 10%, the θ phase accounting for no less than 60% and the γ phase accounting for no more than 40%.

2. The carrier according to claim 1, wherein, In the carrier, the weight ratio of Ag to Re, calculated by metal elements, is 1:1-3.

3. The carrier according to claim 1, wherein, The Re oxide is Re x O y It represents that x is 1 or 2, and y is any integer from 1 to 7.

4. The carrier according to claim 1, wherein, The Re content is 1.5-5% by weight based on the total weight of the carrier.

5. A method for preparing a catalyst support, characterized in that, The method includes: Step 1: The carrier raw material is first contacted with an acidic aqueous solution and kneaded to form a molding precursor. The carrier raw material contains Ag and Re. The amount of carrier raw material used is such that, in terms of metal elements, the weight ratio of Ag to Re in the carrier is 1:1-5, and the content of Ag in the total weight of the carrier is 1-3% by weight. Step 2: The molding precursor is subjected to a first drying and a first calcination in sequence. The temperature of the first roasting is 500-780℃, and the pressure of the first roasting is 2-5MPa; The support comprises Al2O3 and doping components, wherein the doping components include Re oxide and Ag; The Al2O3 crystal forms include θ phase, γ phase and α phase, with the α phase accounting for no more than 10%, the θ phase accounting for no less than 60% and the γ phase accounting for no more than 40%.

6. The method according to claim 5, wherein, In step 1, the carrier material includes Ag, Re source, alumina, and optional molding and pore-forming agent, wherein the alumina includes boehmite and optional alumina powder. And / or, the acidic aqueous solution includes perrhenic acid and other acids, wherein the other acids include at least one of nitric acid, acetic acid, oxalic acid and citric acid.

7. The method according to claim 6, wherein, The Ag and Re sources are selected from silver perrhenate and / or a mixture of rhenium oxide and silver oxide; And / or, the molding pore-forming agent is selected from at least one of guar gum powder, starch, cellulose and / or cellulose derivatives, urea, ethylenediamine, polyethylene, polystyrene, polyethylene glycol, and polyvinyl alcohol; And / or, in the acidic aqueous solution, the weight ratio of perrhenic acid to other acids is 0.2-10:1; And / or, the weight ratio of the acidic aqueous solution to the carrier raw material is 0.4-2:1; And / or, the particle size of the molding precursor is 1-10 mm.

8. The method according to claim 7, wherein, The alumina powder is obtained by calcining boehmite at 800-900℃; And / or, based on the total weight of the alumina, the amount of the forming pore-forming agent is 0-10% by weight. And / or, the cellulose derivative is selected from at least one of methylcellulose, hydroxymethylcellulose, and hydroxypropyl methylcellulose and their salts; And / or, in the acidic aqueous solution, the weight ratio of perrhenic acid to other acids is 0.2-3:1; And / or, the weight ratio of the acidic aqueous solution to the carrier raw material is 1-2:

1.

9. The method according to claim 8, wherein, The amount of Ag and Re source used is such that, in terms of metal elements, the weight ratio of Ag to Re in the carrier is 1:1-3. And / or, the amount of Ag and Re source used is such that the Re content in the carrier is 1.5-5% by weight, based on the total weight of the carrier.

10. The method according to claim 5, wherein, In step 2, the conditions for the first drying include: temperature 60-120℃, time 8-24h; And / or, the first calcination method includes calcination in an atmosphere with an oxygen content not exceeding 40% by weight.

11. The method according to claim 10, wherein, The conditions for the first drying process include: a temperature of 100-120℃ and a time of 8-20 hours. And / or, the first calcination method includes: calcination in an atmosphere with an oxygen content of 15-25% by weight; And / or, the first calcination time is 4-20 hours.

12. The method according to claim 11, wherein, The roasting atmosphere is provided by an atmosphere including inert gases; And / or, the pressure of the first calcination is 3-4 MPa; And / or, the first calcination time is 6-10 hours.

13. The catalyst support prepared by the method according to any one of claims 5-12.

14. A catalyst for selective hydrogenation of alkynes, characterized in that, The catalyst comprises a support and a main active component and a co-active component supported on the support, wherein the main active component is Pd, and the support is the catalyst support according to any one of claims 1-4 and 13.

15. The catalyst according to claim 14, wherein, The Pd content, based on the total weight of the carrier, is 0.002-0.2% by weight. And / or, the co-active component is selected from at least one of Group VIII elements, alkali metal elements, alkaline earth metal elements, Group IIIA elements, Group IB elements, Group IIB elements, Group VA elements, rare earth elements, and halogen elements, other than Pd.

16. The catalyst according to claim 14 or 15, wherein, The Pd content, based on the total weight of the carrier, is 0.01-0.15% by weight. And / or, on an elemental basis, the weight ratio of Pd to Ag is 1:10-60; And / or, in terms of elements, the weight ratio of Pd to the total weight of Ag and Re in the carrier is 1:50-100; And / or, the co-active component is selected from at least one of Ga, In, La, Ni, Zn, Fe, Bi, and Y; And / or, based on the total weight of the carrier, the content of the active ingredient is 0-5% by weight.

17. The catalyst according to claim 16, wherein, The Pd content is 0.05-0.15% by weight based on the total weight of the carrier. And / or, on an elemental basis, the weight ratio of Pd to Ag is 1:20-45; And / or, in terms of elements, the weight ratio of Pd to the total weight of Ag and Re in the carrier is 1:70-100; And / or, based on elemental composition, the weight ratio of the active ingredient to Pd is 0.5-1.5:1; And / or, based on the total weight of the carrier, the content of the active ingredient is 0.01-1 by weight.

18. A method for preparing a selective hydrogenation catalyst for alkynes, the method comprising loading a main active component and a co-active component onto a support, characterized in that, The main active component is Pd, and the carrier is the carrier described in any one of claims 1-4 and 13.

19. The method according to claim 18, wherein, The active ingredient is selected from at least one of the following: Group VIII elements, alkali metal elements, alkaline earth metal elements, Group IIIA elements, Group IB elements, Group VA elements, rare earth elements, and halogen elements, which are different from Pd. And / or, the loading method includes loading the active component precursor and the co-active component precursor onto the carrier by spraying or impregnation, followed by a second drying and a second calcination.

20. The method according to claim 19, wherein, The active ingredient is selected from at least one of Ga, In, La, Ni, Zn, Fe, Bi, and Y; And / or, the active component precursor is selected from at least one of water-soluble inorganic salts of palladium, oxides of palladium, and organometallic compounds of palladium; And / or, the precursor of the co-active component is selected from at least one of the following: a water-soluble inorganic salt of the co-active component, a hydroxide of the co-active component, and an organometallic compound of the co-active component; And / or, the conditions for the second drying include: a temperature of 60-160°C; And / or, the conditions for the second calcination include: a temperature of 300-600°C.

21. The method according to claim 20, wherein, The weight ratio of the active ingredient to Pd, calculated by element, is 0.5-1.5:

1. And / or, the amount of the active component precursor is such that the Pd content in the catalyst, based on the total weight of the support, is 0.002-0.2% by weight. And / or, the amount of the co-active component precursor is such that, based on the total weight of the support, the content of the co-active component in the catalyst is 0.002-0.2% by weight. And / or, the second calcination is carried out in an atmosphere containing an inert gas.

22. The method according to claim 21, wherein, The amount of the active component precursor and the co-active component precursor is such that, in terms of elemental composition, the weight ratio of the co-active component to Pd in ​​the catalyst is 0.5-1.5:

1. And / or, the amount of the active component precursor used is such that the Pd content in the catalyst, based on the total weight of the support, is 0.01-0.15% by weight. And / or, the amount of the co-active component precursor is such that the content of the co-active component in the catalyst, based on the total weight of the support, is 0.01-0.1 by weight.

23. The method according to claim 22, wherein, The amount of the active component precursor is such that the Pd content in the catalyst, based on the total weight of the support, is 0.01-0.1% by weight.

24. The use of the support according to any one of claims 1-4 and 13 or the catalyst according to any one of claims 14-17 in the selective hydrogenation of alkynes.

25. The application according to claim 24, characterized in that, The application is the use of the catalyst described above in the selective hydrogenation of alkynes to prepare olefins.

26. A method for hydrogenating and refining ethylene stream in a sequential separation process, characterized in that, The method includes: bringing the reaction gas into a second contact with a catalyst and reacting it under selective hydrogenation conditions, so that the acetylene therein is selectively hydrogenated to produce ethylene; The reaction gas is obtained by adding H2 and CO to the ethylene stream, wherein the amount of CO used is such that, based on the total amount of the reaction gas, the CO content is 0.002-0.02 mol% The ethylene stream originates from a sequential separation process, wherein the acetylene content is not less than 0.9 mol% based on the total amount of the ethylene stream; the catalyst is the catalyst described in any one of claims 14-17.

27. The method according to claim 26, wherein, The CO content in the reaction gas does not fluctuate by more than 20%. And / or, the second contact is carried out in a combined hydrogenation reactor comprising an isothermal bed and an adiabatic bed; And / or, the H2 and / or CO are provided by hydrogen-rich gas stream I; And / or, based on the total amount of the ethylene stream, the acetylene content does not exceed 5 moles.

28. The method according to claim 27, wherein, The CO content in the reaction gas does not fluctuate by more than 10%. And / or, in an isothermal bed reactor, the temperature rise from inlet to outlet does not exceed 15°C; And / or, in the hydrogen-rich gas stream I, the H2 content is not less than 90 mol%; And / or, in the hydrogen-rich gas stream I, the CO content is 0.2-3 mol%.

29. The method according to claim 28, wherein, The CO content in the reaction gas does not fluctuate by more than 5%; And / or, in the hydrogen-rich gas stream I, the H2 content is not less than 94 mol%; And / or, in the hydrogen-rich gas stream I, the CO content is 0.25-2 mol%; And / or, the hydrogen-rich gas stream I originates from an external hydrogen production unit and / or a separation system preceding a stationary adiabatic hydrogenation reactor.

30. The method according to any one of claims 26-29, wherein, The selective hydrogenation conditions include: a pressure of 1-4 MPa and a space velocity of 9000-25000 m / s in the ethylene stream of the isothermal bed hydrogenation reactor. 3 ·(m 3 ) -1 ·h -1 The space velocity of the ethylene stream in the adiabatic bed hydrogenation reactor is 3000-15000 m. 3 ·(m 3 ) -1 ·h -1 .

31. The method according to claim 30, wherein, The temperature of selective hydrogenation ensures that the acetylene content in the outlet stream of the adiabatic bed hydrogenation reactor does not exceed 10 ppm. And / or, the method further includes: introducing an optional hydrogen-rich gas stream II into each section of the hydrogenation reactor, such that the hydrogen content in the inlet stream of each section of the hydrogenation reactor is 2-10 mol.

32. The method according to claim 31, wherein, The temperature of selective hydrogenation ensures that the acetylene content in the outlet stream of the adiabatic bed hydrogenation reactor does not exceed 5 ppm. And / or, the selective hydrogenation temperature is 20-80°C; And / or, the method further includes: introducing an optional hydrogen-rich gas stream II into each section of the hydrogenation reactor, such that the hydrogen content in the inlet stream of each section of the hydrogenation reactor is 2-8 moles.

33. The method according to claim 32, wherein, The temperature of selective hydrogenation ensures that the acetylene content in the outlet stream of the adiabatic bed hydrogenation reactor does not exceed 1 ppm. And / or, the method further includes: introducing an optional hydrogen-rich gas stream II into each section of the hydrogenation reactor, such that the hydrogen content in the inlet stream of each section of the hydrogenation reactor is 4-6 moles.

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