Method for removing alkyne and / or alkadiene in pyrolysis gas and application thereof

Abstract

The invention relates to the technical field of selective hydrogenation, and discloses a method for removing alkyne and / or alkadiene in pyrolysis gas and application of the method. According to the method provided by the invention, a better acetylene removal effect can be obtained, meanwhile, a higher MAPD conversion rate and extremely high ethylene and propylene selectivity can be achieved, in addition, the method can also realize long-term stable operation, and the method is more suitable for green industrial production and application.

Description

Technical Field

[0001] The invention relates to the technical field of selective hydrogenation, and in particular to a method for removing acetylenes and / or dienes from cracked gas and application thereof. Background Art

[0002] The technology of preparing olefins by cracking petroleum is one of the mainstream technologies for olefin production at present. The pre-depropanization pre-hydrogenation technology is one of the cryogenic separation technologies that matches the technology of preparing olefins by cracking petroleum. In the pre-depropanization pre-hydrogenation separation process, the cracked gas is directly hydrogenated to remove acetylenes and dienes without separation and distillation treatment.

[0003] Since ethylene and acetylene are difficult to separate clearly by distillation, in order to obtain polymerization-grade ethylene, the acetylene content in the nitrogen source outlet stream of the pre-depropanization pre-hydrogenation reactor must be below 1ppm. Although methylacetylene (MA) and propadiene (PD) can be removed in subsequent treatment, in order to increase the yield of propylene, it is expected to obtain the highest possible MAPD conversion rate and propylene selectivity in the pre-depropanization pre-hydrogenation process.

[0004] The selective hydrogenation treatment method for removing acetylenes and dienes from cracked gas has the advantages of simple process and low energy consumption, and can also increase the production of target olefin products such as ethylene and propylene. It is one of the most commonly used methods to ensure that the content of acetylene, MAPD, propylene and other components in the product obtained by the pre-depropanization pre-hydrogenation process meets the above-mentioned requirements.

[0005] However, the existing selective hydrogenation catalysts and methods for the pre-depropanization pre-hydrogenation process usually tend to focus on the removal effect of acetylene and MAPD, but it is difficult to take into account the selectivity of ethylene and propylene. In addition, the existing catalysts for the pre-depropanization pre-hydrogenation process are also difficult to achieve long-term stable operation. Due to the environmental pressure and cost issues caused by the frequent regeneration of the catalyst, it is difficult to meet the requirements of green and sustainable industrial production. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for removing alkynes and / or dienes in cracking gas and its application, which method can achieve better acetylene and MAPD removal effects while also having a higher MAPD conversion rate and extremely high ethylene and propylene selectivity, and can achieve long-term stable operation.

[0007] In order to achieve the above object, the present invention provides a method for removing acetylenes and / or dienes from cracked gas, the method comprising: first contacting the reaction gas with a catalyst, and reacting under conditions of selective hydrogenation of acetylenes and / or dienes;

[0008] The reaction gas comprises a cracked gas stream from the top of a front depropanizer, wherein the H2 content is 6-20 mol%, the CO content is 0.02-0.2 mol%, the acetylene content is 0.01-1 mol%, the methylacetylene content is 0.05-0.8 mol%, and the propadiene content is 0.05-0.8 mol%;

[0009] The catalyst comprises a carrier, an active component and a co-active component, the active component is Pd, and the carrier comprises single substance Ag, Re oxide and Al2O3.

[0010] The second aspect of the present invention provides the vector defined in the first aspect.

[0011] The third aspect of the present invention provides the catalyst defined in the first aspect.

[0012] The fourth aspect of the present invention provides the use of the method described in the first aspect, the carrier described in the second aspect, and the catalyst described in the third aspect in improving the removal rate of acetylenes and / or dienes in cracked gas, and / or in improving the olefin selectivity in the selective hydrogenation of cracked gas.

[0013] Through the above technical solution, the present invention can at least achieve the following beneficial effects:

[0014] (1) The method provided by the present invention has excellent acetylene removal ability (acetylene can be removed to below 0.1 ppm) and ultra-high ethylene selectivity, and can increase the ethylene production while achieving the acetylene removal target of the pre-depropanization pre-hydrogenation process.

[0015] (2) The method provided by the present invention can also remove most of the MAPD (MAPD conversion rate can reach more than 65%), has extremely high propylene selectivity and C 4+ The amount generated is very small, which can not only prevent the polymerization and coking of alkynes and dienes and improve the stable operation cycle, but also increase the output of high-value products such as ethylene and propylene.

[0016] (3) The method provided by the present invention can achieve efficient removal of acetylene and MAPD for cracked gases with different acetylene contents by selecting the number of reactors connected in series, thereby making it more applicable and more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the X-ray photoelectron spectrum of Re in carrier A1 prepared in Example 1.

[0018] Figure 2 This is the X-ray photoelectron spectrum of Ag in carrier A1 prepared in Example 1. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] In the present invention, unless otherwise specified, "MA" is an abbreviation of "methylacetylene", and the two have the same meaning and can be used interchangeably. "PD" is an abbreviation of propadiene, and the two have the same meaning and can be used interchangeably. "MAPD" generally refers to a mixture of methylacetylene and propadiene, and can also be used as a collective term for the two, that is, to refer to methylacetylene and propadiene in the material.

[0021] In the present invention, unless otherwise specified, the operation number (such as the "first" in "first contact") is only used to facilitate the distinction of similar operations in different methods or steps in the description, and has no limiting effect on the specific operating method, conditions and sequence, etc.

[0022] In the art, the catalyst used for selective hydrogenation of alkynes is usually a supported catalyst with a noble metal Pd as an active component and an effective auxiliary agent added. In the current research on carbon two selective hydrogenation catalysts, Ag is generally used as an auxiliary agent, so that Pd-Ag forms a coordination, weakens the adsorption capacity of Pd atoms for ethylene, inhibits excessive hydrogenation of ethylene, and thus improves ethylene selectivity. However, the inventors have found in long-term research that the ethylene selectivity of the existing catalyst with Pd as an active component and Ag as an auxiliary agent is still insufficient, and its stable operation cycle also needs to be improved.

[0023] In the existing C2 selective hydrogenation catalyst, the role of using Ag as an additive is to improve the hydrogenation environment and electron cloud distribution of Pd, thereby inhibiting the occurrence of over-hydrogenation. The main principle is that the energy of the 5s orbital of Ag atom is close to that of the 4d orbital of Pd atom. After Pd-Ag forms a coordination, the 5s electron of Ag atom will fill the empty 4d electron orbital of Pd atom, increasing the electron cloud density of the d orbital of Pd atom. Ethylene mainly combines with Pd in ​​the form of σ-Л feedback bond. The empty 4d orbital of Pd atom is the key to the formation of σ-Л feedback bond. The addition of Ag reduces the empty 4d electron orbital of Pd, thereby weakening the adsorption capacity of Pd atom to ethylene and inhibiting the over-hydrogenation of ethylene.

[0024] However, the inventors of the present invention have found in their research that when Ag is loaded on the surface of a carrier by a conventional impregnation or spraying process, it is usually distributed in agglomerated flakes, which easily covers the surface of Pd particles, causing the catalyst to lose hydrogenation activity and correspondingly reduce ethylene selectivity. Therefore, if the hydrogenation activity and ethylene selectivity of the catalyst are to be further improved, the distribution state of Ag in the catalyst needs to be improved. However, the inventors have found in a large number of experiments that Ag as a loading component is very easy to agglomerate and difficult to disperse.

[0025] In view of the above problems, the inventors have cleverly discovered after long-term research that Re and Ag have a good synergistic effect. When they are co-doped into the carrier of the selective hydrogenation catalyst, the dispersibility of Ag is greatly improved. Moreover, the addition of Re can not only prevent the problem of excessive agglomeration of Ag and the decrease in catalyst hydrogenation activity caused by covering the surface of Pd particles, but also increase the valence of Ag, weaken the degree of Pd-Ag electron transfer, and thus increase ethylene selectivity. In addition, the addition of Re also reduces the amount of Ag in the catalyst and reduces the catalyst cost.

[0026] After further research, the inventors unexpectedly discovered that when the doping components Re and Ag and the amount of the loading components in the above catalyst are adjusted to a specific level and combined with a specific selective hydrogenation method, there is a synergistic effect on the hydrogenation capacity of the active component Pd. For example, under the conditions of high CO and extremely high hydrogen composition of the cracked gas, the prepared new catalyst can achieve an excellent selective hydrogenation effect on acetylene and MAPD, while ensuring the removal of acetylene, achieving the maximum hydrogenation conversion of MAPD and extremely high ethylene and propylene selectivity.

[0027] Based on the above findings, the first aspect of the present invention provides a method for removing alkynes and / or diolefins from cracked gas, the method comprising: first contacting the reaction gas with a catalyst, and reacting under conditions of selective hydrogenation of alkynes and / or diolefins;

[0028] The reaction gas comprises a cracked gas stream from the top of a front depropanizer, wherein the H2 content is 6-20 mol%, the CO content is 0.02-0.2 mol%, the acetylene content is 0.01-1 mol%, the methylacetylene content is 0.05-0.8 mol%, and the propadiene content is 0.05-0.8 mol%;

[0029] The catalyst comprises a carrier, an active component and a co-active component, the active component is Pd, and the carrier comprises single substance Ag, Re oxide and Al2O3.

[0030] The method provided by the present invention can directly treat the front depropanizer tower overhead stream as a reaction gas. According to a preferred embodiment of the present invention, the reaction gas (in addition to CO, H2 and acetylene) also contains methane, a carbon 2 fraction, a carbon 3 fraction and a carbon 4 fraction.

[0031] Preferably, in the reaction gas, the content of H2 is 6-20 mol%, the content of CO is 0.02-0.2 mol%, the content of acetylene is 0.01-1 mol%, the content of ethylene is 5-70 mol%, the content of methylacetylene is 0.05-0.5 mol%, the content of propadiene is 0.05-0.5 mol%, and the content of propylene is 5-40 mol%.

[0032] According to a preferred embodiment of the present invention, the first contacting is carried out in an adiabatic bed hydrogenation reactor (hereinafter referred to as "adiabatic bed reactor" or "adiabatic bed" for short). Preferably, the adiabatic bed hydrogenation reactor is a single-stage adiabatic bed hydrogenation reactor or a multi-stage adiabatic bed hydrogenation reactor connected in series. More preferably, the multi-stage adiabatic bed hydrogenation reactor is connected in series with 2-5 single-stage adiabatic bed hydrogenation reactors.

[0033] In the method of the present invention, the number of adiabatic bed reactors is usually determined by the acetylene content in the reaction gas. The higher the acetylene content, the more adiabatic bed reactors are used to ensure that the acetylene removal rate can reach an ideal level. For example, when the acetylene content in the reaction gas is less than or equal to 0.15 mol%, a single-stage adiabatic bed reactor can be used; when the acetylene content in the reaction gas is in the range of greater than 0.15 to less than or equal to 0.45 mol%, a two-stage adiabatic bed reactor in series can be used; when the acetylene content in the reaction gas is in the range of greater than 0.45 to less than or equal to 1 mol%, a three-stage adiabatic bed reactor in series can be used.

[0034] In the method provided by the present invention, there is no particular limitation on the specific selective hydrogenation conditions, and the acetylene and / or MAPD selective hydrogenation conditions commonly used in the pre-depropanization pre-hydrogenation process in the art can be applied to the present invention.

[0035] According to a preferred embodiment of the present invention, the selective hydrogenation conditions of alkynes and / or dienes include: a pressure of 1-4 MPa; a reaction gas space velocity of 5000-30000 m / s; 3 ·(m 3 ) -1 ·h -1 .

[0036] Preferably, the selective hydrogenation conditions of alkynes and / or dienes include: pressure 1.5-3.3 MPa; space velocity of reaction gas 12000-20000 m / s; 3 ·(m 3 ) -1·h -1 .

[0037] Preferably, the temperature of the selective hydrogenation is such that the acetylene content in the outlet stream of the adiabatic bed hydrogenation reactor is no more than 5 ppm, preferably no more than 1 ppm, more preferably no more than 0.1 ppm; the total conversion rate of methylacetylene and propylene is no less than 55%, preferably no less than 65%. It should be noted that when multiple adiabatic beds are connected in series for reaction, "the outlet stream of the adiabatic bed hydrogenation reactor" refers to the outlet stream of the last adiabatic bed.

[0038] More preferably, the temperature of the selective hydrogenation is 0-120° C., preferably 20-60° C. In the present invention, the temperature of the selective hydrogenation is dynamically changed during the reaction process to ensure that the acetylene content in the reactor outlet stream meets the above requirements. Therefore, the "selective hydrogenation temperature" in the present invention refers to the range of change of the inlet temperature of each reactor during the reaction process (e.g., during the reaction operation cycle).

[0039] In order to obtain a better reaction effect, according to a preferred embodiment of the present invention, in the catalyst, the specific surface area of ​​the carrier is 5-500m 2 / g, preferably 80-300m 2 / g, more preferably 90-200m 2 / g.

[0040] In the present invention, the Al2O3 in the carrier can be any Al2O3 that can be used for the preparation of a selective hydrogenation catalyst. The inventors found in further research that when the Al2O3 in the carrier has a specific crystal form, better performance effects can be obtained.

[0041] According to a preferred embodiment of the present invention, the crystal form of the Al2O3 includes at least one of the θ phase, the γ phase and the α phase. Preferably, the θ phase crystal form of the Al2O3 accounts for no less than 60%, the γ phase crystal form accounts for no more than 20%, and the α phase crystal form accounts for no more than 30%.

[0042] In order to further improve the catalyst performance (such as acetylene conversion rate, ethylene selectivity, etc.), according to a preferred embodiment of the present invention, in the carrier, the weight ratio of Ag to Re, calculated as metal elements, is 1:0.1-5, preferably 1:0.5-3. For example, it can be 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, or any intermediate ratio within the range formed by any two of the above ratios.

[0043] Preferably, based on the total weight of the carrier, the content of Ag is 0.2-5% by weight, preferably 0.5-1.5% by weight, and the content of Re is 0.2-5% by weight, preferably 0.2-2% by weight, calculated as metal elements. For example, the Ag content in the carrier can be 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, 0.9% by weight, 1% by weight, 1.1% by weight, 1.2% by weight, 1.3% by weight, 1.4% by weight, 1.5% by weight, or any intermediate value in the range formed by any two of the above values. For another example, the Re content in the carrier can be 0.2% by weight, 0.4% by weight, 0.6% by weight, 0.8% by weight, 1% by weight, 1.2% by weight, 1.4% by weight, 1.6% by weight, 1.8% by weight, 2% by weight, or any intermediate value in the range formed by any two of the above values.

[0044] According to a preferred embodiment of the present invention, the support comprises at least one Re oxide.

[0045] Preferably, the Re oxide is Re x O y Represents, where x is 1 or 2, and y is any integer from 1 to 7.

[0046] In the present invention, the carrier used for the above catalyst can be obtained by any method for preparing a catalyst carrier in the art, as long as it has the above characteristics.

[0047] According to a preferred embodiment of the present invention, the carrier is prepared by a method comprising the following steps:

[0048] Step 1, bringing the carrier raw material into second contact with the acidic aqueous solution, kneading and molding, and obtaining a molded precursor;

[0049] Step 2: subjecting the molded precursor to a first drying and a first calcination in sequence.

[0050] In the above method, step 1 is the process of mixing the raw materials and preparing a molding precursor, wherein the second contact (i.e., the process of mixing the carrier raw material and the acidic aqueous solution) can be completed before kneading molding, or can be performed during the kneading molding process. For example, the carrier raw material and the acidic aqueous solution can be mixed first and then placed in a kneading device for kneading, or the carrier raw material can be directly placed in a kneading device, and the acidic aqueous solution can be added during the kneading process, and a molding precursor of a desired shape can be prepared after the kneading is completed.

[0051] According to a preferred embodiment of the present invention, in step 1, the carrier raw material includes Ag and Re sources, alumina and an optional shaping pore-forming agent.

[0052] Ag and Re sources provide doping components Ag-Re for the carrier x O y The substance is usually 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. According to some preferred embodiments of the present invention, the Ag and Re sources are silver perrhenate, and / or the Ag and Re sources are 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, and more preferably selected from at least one of Re2O7, ReO3 and ReO2.

[0053] According to a preferred embodiment of the present invention, the alumina comprises pseudo-boehmite and optionally alumina powder, and preferably the alumina powder is obtained by calcining the pseudo-boehmite at 800-900°C.

[0054] Preferably, the content of the alumina powder is 0-20 wt % based on the total weight of the alumina.

[0055] A shaping pore-forming agent refers to a type of additive used in the process of preparing a shaped catalyst (carrier) to make the carrier raw material easier to shape. Any shaping pore-forming agent that can be used in a selective hydrogenation catalyst can be applied to the present invention. According to a preferred embodiment of the present invention, in the carrier raw material, the shaping pore-forming agent is selected from at least one of sesbania powder, starch, cellulose and / or cellulose derivatives, urea, ethylenediamine and high molecular polymers, and preferably, the amount of the shaping pore-forming agent is 0-10% by weight based on the total weight of the alumina.

[0056] Preferably, the cellulose derivative is selected from at least one of methyl cellulose, hydroxymethyl cellulose and hydroxypropyl methyl cellulose and salts thereof.

[0057] Preferably, the high molecular polymer is at least one selected from polyethylene, polystyrene, polyethylene glycol, polyvinyl alcohol and polyethylene glycol.

[0058] According to a preferred embodiment of the present invention, in step 1, the acidic aqueous solution includes perrhenic acid and / or other acids, wherein the other acids include at least one of nitric acid, acetic acid, oxalic acid and citric acid.

[0059] Preferably, in the acidic aqueous solution, the weight ratio of perrhenic acid to other acids is 0.2-10:1, preferably 5-10:1.

[0060] Preferably, the weight ratio of the acidic aqueous solution to the carrier raw material is 0.4-2:1, preferably 0.5-1.3:1.

[0061] Preferably, the particle size of the molded precursor is 1-10 mm. In the present invention, the molded precursor can be prepared in any shape commonly used in the art for molding selective hydrogenation catalysts, for example, it can be a sheet, (quasi) sphere, cylinder, cube, toothed sphere, etc., or it can be a clover-shaped or other special shape.

[0062] In the present invention, when silver perrhenate is used as the Ag and Re sources to prepare the carrier used in the present invention in step 1, a finished silver perrhenate product directly obtained through commercial purchase or customization can be used, or a silver perrhenate product prepared by oneself can be used.

[0063] According to a preferred embodiment of the present invention, the silver perrhenate can be prepared by a method comprising the following steps:

[0064] (a) contacting the aqueous solution containing Ag with the aqueous solution containing perrhenate under stirring conditions for a third time to obtain a (white) precipitate;

[0065] (b) The (white) precipitate was isolated and dried.

[0066] 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 has no particular limitation on the concentration of the Ag-containing aqueous solution, as long as it can be easily contacted with the aqueous solution containing perrhenate to produce a precipitate (i.e., silver perrhenate).

[0067] Preferably, in step (a), the aqueous solution containing perrhenate may be a mixed solution of perrhenic acid or its salt and other acids, or may be an ammonium perrhenate solution, wherein the other acid is preferably nitric acid.

[0068] More preferably, in step (a), the Ag provided by the Ag-containing aqueous solution is + and ReO4 provided by an aqueous solution containing perrhenate - The molar ratio is 0.8-1.2:1.

[0069] Preferably, in step (a), the third contacting is carried out under heating conditions, preferably heating so that the temperature of the reaction system is 30-50°C.

[0070] Preferably, in step (a), the third contacting method comprises: dropping the aqueous solution containing Ag into the aqueous solution containing perrhenate.

[0071] More preferably, in step (a), the third contact further comprises: stopping stirring after all the Ag-containing aqueous solution has been added dropwise, and allowing the reaction system to stand for 20-60 minutes under heating conditions 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 standing to cool to room temperature (25±5°C).

[0072] In the above method, the (white) precipitate obtained in step (a) is the silver perrhenate precipitate. Step (b) is the process of obtaining silver perrhenate from the reaction system. In order to prevent other compounds in the reaction system from adhering to the silver perrhenate and affecting the performance of the carrier or catalyst, the separated silver perrhenate precipitate can be washed before drying. Generally, the washing can be carried out using an organic solvent, such as ether.

[0073] In step (b), the separation can be performed by any solid-liquid separation method commonly used in the art, such as filtration, suction filtration, centrifugation, etc.

[0074] 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 (for example, it does not cause oxidation, decomposition, etc. to form other compounds). For example, vacuum drying can be performed at 50-100°C.

[0075] In the present invention, there is no particular limitation on the specific operation method and conditions in step 2, as long as the obtained carrier can have the aforementioned characteristics.

[0076] According to a preferred embodiment of the present invention, in step 2, the conditions for the first drying include: temperature 100-150° C., time 2-20 h.

[0077] Preferably, the first drying conditions include: temperature 100-120° C., time 8-20 h.

[0078] According to a preferred embodiment of the present invention, in step 2, the first calcination method includes: calcining in an atmosphere with an oxygen content of no more than 40% by weight, preferably calcining in an atmosphere with an oxygen content of 15-40% by weight (for example, 15%, 20%, 25%, 30%, 35%, 40%, or any intermediate value within the range of any two of the above values), preferably, the atmosphere is provided by a gas including at least one of an inert gas, nitrogen and oxygen. For example, the atmosphere can be provided by a mixed gas of oxygen and an inert gas and / or nitrogen, or by air, as long as the oxygen content therein meets the above requirements.

[0079] Preferably, the first calcination pressure is 2-6 MPa, preferably 2.5-4.5 MPa, for example, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, or any intermediate value within the range of any two of the above values.

[0080] Preferably, the temperature of the first calcination is 600-900° C., preferably 600-800° C. For example, it may be 550° C., 600° C., 650° C., 700° C., 750° C., 800° C., or any intermediate value within the range of any two of the above values.

[0081] Preferably, the first calcination time is 2-15 h, preferably 3-10 h.

[0082] According to a preferred embodiment of the present invention, the specific surface area of ​​the catalyst is 5-500m 2 / g, preferably 80-300m 2 / g, more preferably 90-200m 2 / g. For example, it can be 90m 2 / g、100m 2 / g, 110m 2 / g, 120m 2 / g, 130m 2 / g, 140m 2 / g, 150m 2 / g, 160m 2 / g, 170m 2 / g, 180m 2 / g, 190m 2 / g, 200m 2 / g, or any intermediate value within the range formed by any two of the above values. Affected by factors such as the specific selection of the supporting active component and the loading amount of the supporting active component and Pd, the specific surface area of ​​the selective hydrogenation catalyst provided by the present invention may differ from the specific surface area of ​​the support thereof. Usually, the specific surface area of ​​the catalyst is slightly smaller than that of the support.

[0083] In the selective hydrogenation catalyst provided by the present invention, there is no particular restriction on the loading amount of the active component Pd, as long as the hydrogenation activity of the catalyst can reach a relatively ideal level. Since the combined effect of Ag and Re oxides doped in the carrier used in the present invention can effectively improve the catalytic activity of Pd, Pd can be present in the catalyst provided by the present invention at a relatively low loading amount.

[0084] According to some preferred embodiments of the present invention, in the catalyst, based on the total weight of the carrier, the content of Pd is 0.002-0.2 wt%, preferably 0.01-0.15 wt%, more preferably 0.02-0.1 wt%. For example, it can be 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, or any intermediate value within the range formed by any two of the above values.

[0085] Preferably, the weight ratio of Pd to Ag is 1:1-30, preferably 1:1-20, calculated as the elements. For example, it can be 1:1, 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:14, 1:16, 1:18, 1:20, or any intermediate ratio within the range of the ratio formed by any two of the above ratios.

[0086] Preferably, the weight ratio of Pd to the total weight of Ag and Re in the carrier is 1:5-80, preferably 1:5-50, calculated as the element. For example, it can be 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, or any intermediate ratio within the range of ratios formed by any two of the above ratios.

[0087] In the selective hydrogenation catalyst provided by the present invention, the co-active component may be any element that can further improve the catalytic activity (eg, conversion rate, ethylene selectivity, etc.) of the Pd-supported selective hydrogenation catalyst.

[0088] According to some preferred embodiments of the present invention, the co-active component is selected from at least one of Group VIII elements other than Pd, alkali metal elements, alkaline earth metal elements, Group IIIA elements, Group IB elements, Group VA elements, rare earth elements and halogen elements.

[0089] Preferably, the co-active component is selected from at least one of Ga, In, La, Ni, Zn, Fe, Bi, Sn, Y and Mn.

[0090] In the present invention, there is no particular limitation 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 reaction activity and effect, etc.).

[0091] According to some preferred embodiments of the present invention, in the catalyst, the content of the auxiliary active component is 0-5% by weight, preferably 0.01-2% by weight, and more preferably 0.01-1% by weight, based on the total weight of the carrier. For example, it can be 0.01% by weight, 0.03% by weight, 0.05% by weight, 0.07% by weight, 0.09% 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 formed by any two of the above values.

[0092] In order to make the above catalyst have better catalytic activity and higher selectivity for ethylene and / or propylene, more preferably, the weight ratio of the co-activating component to Pd is 0.1-3:1, preferably 0.2-2:1, calculated as the element. For example, it can be 0.2:1, 0.4:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, or any intermediate ratio within the ratio range formed by any two of the above ratios.

[0093] According to some preferred embodiments of the present invention, the catalyst is prepared by a method comprising the following steps: loading the active component and the co-active component on a carrier. In the method provided by the present invention, the active component and the co-active component can be loaded on a carrier by any existing method for preparing a supported catalyst to obtain the above catalyst.

[0094] According to some preferred embodiments of the present invention, the loading method includes loading the active component precursor and the co-active component precursor on the carrier by spraying or dipping, and then performing a second drying and a second calcination in sequence.

[0095] Preferably, the second drying conditions include: a temperature of 100-180° C. Preferably, the second drying time is 2-12 hours.

[0096] Preferably, the second calcination conditions include: a temperature of 310-600° C., and preferably the second calcination is performed in an atmosphere containing at least one of an inert gas, oxygen and nitrogen. For example, the second calcination can be performed in an air atmosphere.

[0097] The active component precursor is a compound that can provide the active component Pd for the catalyst. Preferably, the active component precursor is selected from at least one of water-soluble inorganic salts of palladium (such as palladium nitrate, etc.), palladium oxides and metal organic compounds of palladium (such as palladium acetate, etc.).

[0098] 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 a water-soluble inorganic salt of the co-active component (for example, a sulfate, nitrate, carbonate, halide, ammonium compound, etc. of the co-active component), a hydroxide of the co-active component, and a metal organic compound of the co-active component (for example, an acetate of the co-active component, etc.).

[0099] In the above method, the amounts of the active component precursor and the co-active component precursor are such that the contents and proportions of the active component and the co-active component in the obtained catalyst meet the above requirements, which will not be elaborated here.

[0100] The second aspect of the present invention provides the vector defined in the first aspect. The characteristics of the vector and the preparation method thereof are as described above and will not be described in detail here.

[0101] The third aspect of the present invention provides a catalyst as defined in . The characteristics of the catalyst and its preparation method are as described above and will not be repeated here.

[0102] The fourth aspect of the present invention provides the use of the method described in the first aspect, the carrier described in the second aspect, and the catalyst described in the third aspect in improving the removal rate of acetylenes and / or dienes in cracked gas, and / or in improving the olefin selectivity in the selective hydrogenation of cracked gas.

[0103] The present invention will be described in detail below by way of examples. It should be understood that the following examples 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.

[0104] In the following examples, pseudo-boehmite powder was purchased from Sinopec Catalyst (Beijing) Co., Ltd., with a specific surface area of ​​about 250 m 2 / g. Unless otherwise specified, all reagents used were commercial products purchased from regular chemical suppliers and were analytically pure.

[0105] In the following examples, the acetylene content at the reactor outlet was measured by a gas chromatograph, model Agilent 7890; the reactor bed temperature was measured by a thermocouple.

[0106] In the following examples, all pressures are gauge pressures. Unless otherwise specified, all operating pressures are atmospheric pressure, all temperatures are room temperature (25±5° C.), and the oxygen content of the air atmosphere is 21±1% by weight, 1ppm=0.0001mol%.

[0107] Example 1

[0108] Preparation of silver perrhenate:

[0109] (a) weighing 10 g of silver nitrate powder and dissolving it in 20 mL of deionized water to obtain a silver nitrate aqueous solution; weighing 15 g of ammonium perrhenate and dissolving it in 50 mL of deionized water to obtain an ammonium perrhenate aqueous solution;

[0110] At 40°C, under stirring, add the silver nitrate aqueous solution to the ammonium perrhenate aqueous solution to produce a white precipitate. Stop stirring after the silver nitrate aqueous solution has been added, and keep it at 40°C for 30 minutes. Then stop heating and let it stand and cool naturally to room temperature;

[0111] (b) filtering the product of step (a) to obtain a white precipitate, washing it three times with ether, and then drying it in vacuo at 80° C. to obtain silver perrhenate.

[0112] Preparation of vector:

[0113] Step 1, respectively weighing 200g of pseudo-boehmite powder, 3.4g of silver perrhenate, 4g of sesbania powder, 4g of methyl cellulose, and 4g of polyethylene microspheres, and putting them into a mixer to mix to obtain a uniform powdery raw material;

[0114] Weigh 2 g of concentrated nitric acid and 0.5 g of 75% perrhenic acid respectively, add them into 200 g of deionized water to prepare an acidic aqueous solution;

[0115] The uniform powdered raw material is transferred to a kneader, and the acidic aqueous solution is slowly added. After kneading for 1 hour, the mixture is extruded and granulated to obtain a toothed ball-shaped precursor (particle size 4-5 mm);

[0116] Step 2: The molded precursor obtained in step 1 is first dried (110°C, 16h), and then first calcined in an air atmosphere (3MPa, 680°C, 4h) to obtain Al2O3-Ag-Re x O yThe carrier is referred to as carrier A1. XPS detection shows that in the carrier, Ag exists in the form of a single substance, and Re is a mixture of oxides of various valence states (mainly including: ReO2, 21.05 mol%; Re2O7, 78.95 mol%). Figure 1 and Figure 2 The Re and Ag XPS spectra of the support are shown in FIG.

[0117] Preparation of Selective Hydrogenation Catalysts:

[0118] Weigh Pd(NO3)2 and Ga(NO3)3 respectively, dissolve them in deionized water, and prepare 150mL of aqueous solution containing 0.1g Pd and 0.15g Ga as the impregnation solution. Immerse the carrier A1 in the impregnation solution (54°C, 20min). Then take out the impregnated carrier A1, perform a second drying (140°C, 8h), and then perform a second calcination in an air atmosphere (350°C, 12h) to obtain Pd-Ga / Al2O3-Ag-Re x O y Catalyst, denoted as GM-1.

[0119] Example 2

[0120] The method in Example 1 was used, except that Pd(NO3)2 and Fe(NO3)3 were weighed and dissolved in deionized water to prepare 180 mL of an aqueous solution containing 0.06 g Pd and 0.04 g Fe as an impregnation solution. The carrier A1 was impregnated in the impregnation solution (35°C, 15 min). The impregnated carrier A1 was then taken out, dried for a second time (140°C, 8 h), and then calcined for a second time in an air atmosphere (300°C, 5 h) to obtain Pd-Fe / Al2O3-Ag-Re x O y The catalyst is denoted as GM-2.

[0121] Example 3

[0122] Preparation of silver perrhenate:

[0123] (a) weighing 10 g of silver nitrate and dissolving it in 20 mL of deionized water to obtain a silver nitrate aqueous solution;

[0124] At 40°C, under stirring, add the silver nitrate aqueous solution to 55g of 25% perrhenic acid aqueous solution to produce a white precipitate. Stop stirring after the silver nitrate aqueous solution has been added, and keep it at 40°C for 30 minutes. Then stop heating and let it stand and cool naturally to room temperature;

[0125] (b) filtering the product of step (a) to obtain a white precipitate, washing it three times with acetone, and then drying it in vacuo at 80° C. to obtain silver perrhenate.

[0126] Preparation of vector:

[0127] Step 1, weighing 200g of pseudo-boehmite powder, 2g of silver perrhenate, 0.7g of rhenium dioxide, 8g of sesbania powder, 3g of sodium hydroxymethyl cellulose, and 10g of polystyrene respectively, putting them into a mixer and mixing them to obtain a uniform powdery raw material;

[0128] Weigh 4 g of concentrated nitric acid and add it to 200 g of deionized water to prepare an acidic aqueous solution;

[0129] The uniform powdered raw material was transferred to a kneader, and the acidic aqueous solution was slowly added. After kneading for 1 hour, the mixture was extruded and pelletized to obtain a spherical precursor (particle size 4-5 mm).

[0130] Step 2: The formed precursor obtained in step 1 is first dried (120°C, 8h), and then first calcined (2.56MPa, 710°C, 3h) in a nitrogen and oxygen mixed atmosphere (oxygen content 35%) to obtain Al2O3-Ag-Re x O y The carrier is recorded as carrier A2. XPS detection shows that in the carrier, Ag exists in the form of a single substance, and Re is a mixture of oxides of various valence states (mainly including: ReO2, 20.53 mol%; ReO3, 11.05 mol%; Re2O7, 68.42 mol%).

[0131] Preparation of Selective Hydrogenation Catalysts:

[0132] Weigh Pd(NO3)2 and Cu(NO3)2 respectively, dissolve them in deionized water, and prepare 200mL of aqueous solution containing 0.14g Pd and 0.04g Cu as impregnation solution. Impregnate carrier A2 in the impregnation solution (41°C, 10min). Then take out the impregnated carrier A2, perform a second drying (100°C, 4h), and perform a second calcination in air atmosphere (550°C, 4h) to obtain Pd-Cu / Al2O3-Ag-Re x O y The catalyst is denoted as GM-3.

[0133] Example 4

[0134] The method in Example 3 was used, except that Pd(Ac)2 was weighed and dissolved in deionized water, Cs(Ac) was weighed and dissolved in ether, and the obtained Pd(Ac)2 and Cs(Ac) solutions were mixed to obtain 250 mL of ether solution containing 0.3 g Pd and 0.28 g Cs as an impregnation solution. Carrier A2 was impregnated in the impregnation solution (28°C, 30 min). The impregnated carrier A2 was then taken out, dried for a second time (160°C, 2 h), and then calcined for a second time in an air atmosphere (280°C, 12 h) to obtain Pd-Cs / Al2O3-Ag-Re x O y The catalyst is denoted as GM-4.

[0135] Example 5

[0136] Preparation of vector:

[0137] Step 1, respectively weighing 200g of pseudo-boehmite powder, 2.3g of silver oxide, 0.6g of rhenium dioxide, 5g of sesbania powder, 7g of hydroxypropyl methylcellulose, and 2g of polyvinyl alcohol, and putting them into a mixer to mix to obtain a uniform powdery raw material;

[0138] Weigh 4 g of citric acid and 0.9 g of 75% perrhenic acid respectively, add them into 180 g of deionized water to prepare an acidic aqueous solution;

[0139] The uniform powdered raw material was transferred to a kneader, and the acidic aqueous solution was slowly added. After kneading for 2 hours, the mixture was extruded and pelletized to obtain a cylindrical precursor (particle size 3-4 mm);

[0140] Step 2: The formed precursor obtained in step 1 is first dried (120°C, 8h), and then first calcined (3MPa, 780°C, 6h) in a nitrogen and oxygen mixed atmosphere (oxygen content 15%) to obtain Al2O3-Ag-Re x O y The carrier is recorded as carrier A3. XPS detection shows that in the carrier, Ag exists in the form of a single substance, and Re is a mixture of oxides in various valence states (mainly including: ReO2, 38.42 mol%; ReO3, 19.47 mol%; Re2O7, 42.11 mol%).

[0141] Preparation of Selective Hydrogenation Catalysts:

[0142] Weigh Pd(Cl)2 and ZnCl2 respectively, dissolve them in deionized water, and prepare 300mL of aqueous solution containing 0.1g Pd and 0.1g Zn as the impregnation solution. Impregnate the carrier A3 in the impregnation solution (25℃, 8min). Then take out the impregnated carrier A3, perform a second drying (120℃, 8h), and perform a second calcination in air atmosphere (380℃, 12h) to obtain Pd-Zn / Al2O3-Ag-Re x O y The catalyst is denoted as GM-5.

[0143] Example 6

[0144] Preparation of vector:

[0145] Step 1, weigh 200g of pseudo-boehmite powder, 2.3g of silver oxide, 0.25g of rhenium trioxide, 8g of starch, 2g of methyl cellulose, and 8g of polyethylene microspheres respectively, put them into a mixer and mix them to obtain a uniform powdery raw material;

[0146] Weigh 10 g of oxalic acid and 1.5 g of 75% perrhenic acid respectively, add them into 230 g of deionized water to prepare an acidic aqueous solution;

[0147] The uniform powdered raw material was transferred to a kneader, and an acidic aqueous solution was slowly added. After kneading for 10 hours, the mixture was extruded and pelletized to obtain a toothed ball-shaped precursor (particle size 3-4 mm);

[0148] Step 2: The molded precursor obtained in step 1 is first dried (105°C, 4h), and then first calcined in an air atmosphere (3MPa, 680°C, 6h) to obtain Al2O3-Ag-Re x O y The carrier is recorded as carrier A4. XPS detection shows that in the carrier, Ag exists in the form of a single substance, and Re is a mixture of oxides of various valence states (mainly including: ReO2, 26.32 mol%; ReO3, 37.89 mol%; Re2O7, 35.79 mol%).

[0149] Preparation of Selective Hydrogenation Catalysts:

[0150] Weigh Pd(NO3)2 and KNO3 respectively, dissolve them in deionized water, and prepare 300mL of aqueous solution containing 0.2g Pd and 0.3g K as impregnation solution. Impregnate carrier A4 in the impregnation solution (22℃, 25min). Then take out the impregnated carrier A4, perform a second drying (120℃, 8h), and perform a second calcination in air atmosphere (380℃, 12h) to obtain Pd-K / Al2O3-Ag-Re x O yCatalyst, denoted as GM-6.

[0151] Example 7

[0152] Preparation of vector:

[0153] Step 1, respectively weighing 200g of pseudo-boehmite powder, 2.3g of silver oxide, 0.59g of rhenium dioxide, 0.563g of rhenium trioxide, 8g of urea, 4g of hydroxypropyl methylcellulose, and 4g of polyethylene microspheres, and putting them into a mixer to mix to obtain a uniform powdery raw material;

[0154] Weigh 10 g of acetic acid and add it to 230 g of deionized water to prepare an acidic aqueous solution;

[0155] The uniform powdered raw material was transferred to a kneader, and an acidic aqueous solution was slowly added. After kneading for 10 hours, the mixture was extruded and pelletized to obtain a toothed ball-shaped precursor (particle size 3-4 mm);

[0156] Step 2: The molded precursor obtained in step 1 is first dried (150°C, 2h), and then first calcined in an air atmosphere (4MPa, 750°C, 3h) to obtain Al2O3-Ag-Re x O y The carrier is recorded as carrier A5. XPS detection shows that in the carrier, Ag exists in the form of a single substance, and Re is a mixture of oxides of various valence states (mainly including: ReO2, 42.11 mol%; ReO3, 28.95 mol%; Re2O7, 28.95 mol%).

[0157] Preparation of Selective Hydrogenation Catalysts:

[0158] Weigh PdCl2 and HAuCl4 respectively, dissolve them in deionized water, and prepare 350mL of aqueous solution containing 0.08g Pd and 0.06g Au as impregnation solution. Impregnate carrier A5 in the impregnation solution (60℃, 12min). Then take out the impregnated carrier A5, perform a second drying (120℃, 8h), and perform a second calcination in air atmosphere (420℃, 7h) to obtain Pd-Au / Al2O3-Ag-Re x O y Catalyst, denoted as GM-7.

[0159] Comparative Example 1

[0160] Preparation of vector:

[0161] Step 1, weigh 200g of pseudo-boehmite powder, 10g of sesbania powder, and 5g of starch respectively, put them into a mixer and mix them to obtain a uniform powdery raw material;

[0162] Weigh 2 g of concentrated nitric acid and 2 g of citric acid respectively, add them to 150 g of deionized water to prepare an acidic aqueous solution;

[0163] The uniform powdered raw material was transferred to a kneader, and an acidic aqueous solution was slowly added. After kneading for 2 hours, the mixture was extruded and pelletized to obtain a cylindrical precursor (particle size 4-5 mm);

[0164] Step 2: subject the formed precursor obtained in step 1 to a first drying (120°C, 8h), and then to a first calcination in an air atmosphere (normal pressure, 1000°C, 6h) to obtain an Al2O3 carrier, which is recorded as carrier D1.

[0165] Preparation of Selective Hydrogenation Catalysts:

[0166] Weigh Pd(NO3)2 and AgNO3 respectively, dissolve them in deionized water, and prepare 100mL of an aqueous solution containing 0.1g Pd and 0.5g Ag as an impregnation solution. Impregnate the carrier D1 in the impregnation solution (25°C, 5min). Then take out the impregnated carrier D1, perform a second drying (120°C, 8h), and then perform a second calcination (320°C, 12h) in an air atmosphere to obtain a Pd-Ag / Al2O3 catalyst, which is recorded as SM.

[0167] Test Example 1

[0168] The crystal form and proportion of alumina in the catalyst carrier obtained in the above preparation example were detected by XRD analysis, the specific surface area of ​​the catalyst was detected by BET method, the content of Ag and Re in the catalyst carrier obtained in the above preparation example was calculated according to the amount of carrier raw material, and the content of the loading component of the selective hydrogenation catalyst obtained in the above preparation example was calculated according to the content of the active component and the auxiliary active component in the impregnation solution, wherein the content of Ag, Re and the catalyst loading component (Pd and auxiliary active component) were all calculated as elements and calculated based on the total weight of the carrier. The results are shown in Table 1.

[0169] Table 1

[0170]

[0171] Test Example 2

[0172] This test example is used to illustrate the effect evaluation of hydrogenation of cracked gas stream.

[0173] The process of hydrogenating and removing acetylene from cracked gas streams uses three sections of adiabatic fixed bed reactors connected in series for hydrogenation, with heat exchangers between the sections to control the temperature of each section of the reactor. The conditions for the hydrogenation reaction include: reaction gas space velocity 18000h -1, reaction pressure 2.8MPa. The reaction gas is the cracked gas stream from the top of the front depropanizer, and its composition includes: hydrogen 13.5mol%, CO 805ppm, methane 13mol%, ethylene 36mol%, acetylene 0.9mol%, propylene 18mol%, MA 0.4mol%, PD 0.4mol%. The inlet temperature of each stage reactor is 45-50℃, and the outlet temperature is 55-62℃. During the reaction, the temperature of the reactor is dynamically controlled within the above range to control the acetylene content in the outlet stream of the three-stage adiabatic bed reactor to meet the requirements (<1ppm).

[0174] The performance effects of the catalysts obtained in the above embodiments and comparative examples were observed, and the results are shown in Table 2. Among them, the commercially available catalyst is the hydrogenation catalyst BC-H-33 purchased from Sinopec Catalyst Branch; the ethylene and propylene selectivities and the MAPD conversion rate are calculated according to the following formulas; the operation cycle refers to the continuous operation time of the system when the acetylene content at the outlet of the three-stage reactor is controlled below 0.1 ppm.

[0175]

[0176]

[0177]

[0178] C 4+ The generated amount is the sum of the contents of C4 and above components in the component analysis at the outlet of the third stage reactor.

[0179] Table 2

[0180]

[0181] It can be clearly seen from the results in Table 2 that the catalysts prepared in Examples 1-7 have longer operating time, higher MAPD conversion, better selectivity for ethylene and propylene, and C 4+ The amount of generated is lower. This indicates that the Ag-Re x O y , has an excellent synergistic effect on the active component Pd, can effectively improve the selective hydrogenation ability of the catalyst, increase the yield of ethylene and propylene, and effectively reduce the oligomer C 4+ production and extend the service life of the catalyst.

[0182] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for removing alkynes and / or dienes from cracked gas, characterized in that: The method comprises: first contacting the reaction gas with the catalyst, and reacting under the selective hydrogenation conditions of acetylenes and / or dienes; The reaction gas comprises a cracked gas stream from the top of a front depropanizer, wherein the H2 content is 6-20 mol%, the CO content is 0.02-0.2 mol%, the acetylene content is 0.01-1 mol%, the methylacetylene content is 0.05-0.8 mol%, and the propadiene content is 0.05-0.8 mol%; The catalyst comprises a carrier, an active component and a co-active component, the active component is Pd, and the carrier comprises single substance Ag, Re oxide and Al2O3.

2. The method according to claim 1, wherein: The reaction gas also contains methane, carbon 2 fraction, carbon 3 fraction and carbon 4 fraction; Preferably, in the reaction gas, the content of H2 is 6-20 mol%, the content of CO is 0.02-0.2 mol%, the content of acetylene is 0.01-1 mol%, the content of ethylene is 5-70 mol%, the content of methylacetylene is 0.05-0.5 mol%, the content of propadiene is 0.05-0.5 mol%, and the content of propylene is 5-40 mol%; And / or, the first contacting is carried out in an adiabatic bed hydrogenation reactor, preferably the adiabatic bed hydrogenation reactor is a single-stage adiabatic bed hydrogenation reactor or a multi-stage adiabatic bed hydrogenation reactor connected in series, more preferably the multi-stage adiabatic bed hydrogenation reactor has 2-5 single-stage adiabatic bed hydrogenation reactors connected in series.

3. The method according to claim 1, wherein: The selective hydrogenation conditions of alkynes and / or dienes include: pressure of 1-4 MPa, preferably 1.5-3.3 MPa; space velocity of reaction gas of 5000-30000 m / s; 3 ·(m 3 ) -1 ·h -1 , preferably 12000-20000m 3 ·(m 3 ) -1 ·h -1 ; 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 5 ppm, preferably does not exceed 1 ppm, more preferably does not exceed 0.1 ppm; and the total conversion rate of methylacetylene and propylene is not less than 55%; More preferably, the temperature of the selective hydrogenation is 0-120°C, preferably 20-60°C.

4. The method according to claim 1, wherein: In the catalyst, the specific surface area of ​​the carrier is 5-500m 2 / g, preferably 80-300m 2 / g, more preferably 90-200m 2 / g; And / or, the crystal form of the Al2O3 includes at least one of the θ phase, the γ phase and the α phase, preferably, the θ phase crystal form of the Al2O3 accounts for no less than 60%, the γ phase crystal form accounts for no more than 20%, and the α phase crystal form accounts for no more than 30%; And / or, in the carrier, the weight ratio of Ag to Re, calculated as metal elements, is 1:0.1-5, preferably 1:0.5-3; Preferably, based on the total weight of the carrier, as metal elements, the content of Ag is 0.2-5% by weight, preferably 0.5-1.5% by weight; the content of Re is 0.2-5% by weight, preferably 0.2-2% by weight; and / or, the support comprises at least one Re oxide; Preferably, the Re oxide is Re x O y Represents, where x is 1 or 2, and y is any integer from 1 to 7.

5. The method according to claim 4, wherein: The carrier is prepared by a method comprising the following steps: Step 1, bringing the carrier raw material into second contact with the acidic aqueous solution, kneading and molding, and obtaining a molded precursor; Step 2: subjecting the molded precursor to a first drying and a first calcination in sequence.

6. The method according to claim 5, wherein: In step 1, the carrier raw material includes Ag and Re sources, alumina and an optional shaping pore-forming agent; Preferably, the Ag and Re sources are silver perrhenate, and / or, the Ag and Re sources are a mixture of rhenium oxide and silver oxide; Preferably, the alumina comprises pseudo-boehmite and optional alumina powder, preferably the alumina powder is obtained by calcining the pseudo-boehmite at 800-900° C., more preferably, the content of the alumina powder is 0-20% by weight based on the total weight of the alumina; Preferably, the shaping pore-forming agent is selected from at least one of sesbania powder, starch, cellulose and / or cellulose derivatives, urea, ethylenediamine and high molecular polymers, and preferably, the amount of the shaping pore-forming agent is 0-10 wt % based on the total weight of the alumina; More preferably, the cellulose derivative is selected from at least one of methylcellulose, hydroxymethylcellulose and hydroxypropylmethylcellulose and salts thereof; More preferably, the high molecular polymer is selected from at least one of polyethylene, polystyrene, polyethylene glycol, polyvinyl alcohol and polyethylene glycol; and / or, the acidic aqueous solution comprises perrhenic acid and / or other acids, wherein the other acids comprise at least one of nitric acid, acetic acid, oxalic acid and citric acid; Preferably, in the acidic aqueous solution, the weight ratio of perrhenic acid to other acids is 0.2-10:1, preferably 5-10:1; Preferably, the weight ratio of the acidic aqueous solution to the carrier raw material is 0.4-2:1, preferably 0.5-1.3:1; Preferably, the particle size of the molding precursor is 1-10 mm.

7. The method according to claim 5, wherein: In step 2, the first drying conditions include: temperature 100-150° C., time 2-20 h; Preferably, the first drying conditions include: temperature 100-120°C, time 8-20h; And / or, the first calcination method comprises: calcining in an atmosphere with an oxygen content of no more than 40 wt %, preferably calcining in an atmosphere with an oxygen content of 15-40 wt %, preferably the atmosphere is provided by a gas including at least one of an inert gas, nitrogen and oxygen; Preferably, the pressure of the first calcination is 2-6 MPa, preferably 2.5-4.5 MPa; Preferably, the temperature of the first calcination is 600-900°C, preferably 600-800°C; Preferably, the first calcination time is 2-15 h, preferably 3-10 h.

8. The method according to claim 1, wherein: In the catalyst, the content of Pd is 0.002-0.2 wt %, preferably 0.01-0.15 wt %, more preferably 0.02-0.1 wt %, based on the total weight of the carrier; Preferably, the weight ratio of Pd to Ag, calculated as elements, is 1:1-30, preferably 1:1-20; Preferably, the weight ratio of Pd to the total weight of Ag and Re in the carrier is 1:5-80, preferably 1:5-50, calculated as the element; and / or, the co-active component is selected from at least one of Group VIII elements other than Pd, alkali metal elements, alkaline earth metal elements, Group IIIA elements, Group IB elements, Group VA elements, rare earth elements and halogen elements; Preferably, the auxiliary active component is selected from at least one of Ga, In, La, Ni, Zn, Fe, Bi, Sn, Y and Mn; Preferably, in the catalyst, the content of the co-active component is 0-5% by weight, preferably 0.01-2% by weight, more preferably 0.01-1% by weight, based on the total weight of the carrier; More preferably, the weight ratio of the co-active component to Pd is 0.1-3:1, preferably 0.2-2:1, calculated as the element.

9. The method according to any one of claims 1 to 8, wherein: The catalyst is prepared by a method comprising the following steps: loading the active component and the co-active component on a carrier; Preferably, the loading method includes loading the active component precursor and the co-active component precursor on the carrier by spraying or dipping, and then performing a second drying and a second calcination in sequence; Preferably, the second drying conditions include: temperature 100-180°C; preferably drying for 2-12h; Preferably, the conditions of the second calcination include: a temperature of 310-600° C., and preferably the second calcination is performed in an atmosphere containing at least one of an inert gas, oxygen and nitrogen.

10. The method according to claim 9, wherein: The active component precursor is selected from at least one of a water-soluble inorganic salt of palladium, an oxide of palladium and an organometallic compound of palladium; And / or, the co-active component precursor is selected from at least one of a water-soluble inorganic salt of the co-active component, a hydroxide of the co-active component and a metal organic compound of the co-active component.

11. A vector as defined in any one of claims 4 to 7.

12. A catalyst as defined in any one of claims 4 to 10.

13. Use of the method according to any one of claims 1 to 10, the carrier according to claim 11, and the catalyst according to claim 12 in improving the removal rate of acetylenes and / or dienes in cracked gas, and / or in improving the olefin selectivity in the selective hydrogenation of cracked gas.

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