A carbon dioxide fraction selective hydrogenation process

Abstract

The application discloses a carbon fraction selective hydrogenation method, and the carbon fraction is introduced into a reactor to remove acetylene by gas phase hydrogenation reaction, the inlet temperature of the reactor is 30-100 DEG C, the pressure of the reactor is 1.5-3.0 MPa, the gas volume space velocity is 1500-12000 h ‑1 -1; the catalyst used in the gas phase hydrogenation reaction for removing acetylene comprises a carrier and active components, the carrier comprises Al2O3, the carrier has a bimodal pore size distribution, the pore sizes are 15-50 nm and 60-500 nm respectively, and the active components at least comprise Pd, Ni, Cu, Pt, Ce and Ag; the catalyst contains 0.02-0.04% of Pd, 1-5% of Ni, 0.2-1% of Cu, 0.1-0.5% of Ce, 0.001-0.01% of Pt and 0.06-0.2% of Ag, wherein the loadings of Ni and Cu adopt a microemulsion mode, the particle size of the microemulsion is 50-500 nm, and the loadings of Pd, Pt, Ce and Ag adopt a solution mode. The method can reduce the coking amount of the catalyst and prolong the service life of the catalyst.

Description

Technical Field

[0001] This invention relates to a selective hydrogenation method for C2 fractions, and more particularly to a selective hydrogenation method for a post-C2 hydrogenation process. Background Technology

[0002] Ethylene is one of the most important basic raw materials in the petrochemical industry. As a monomer for synthesizing various polymers, ethylene is mostly produced by steam cracking of petroleum hydrocarbons (such as ethane, propane, butane, naphtha, and light diesel oil). The C2 fraction obtained by this method, which is mainly composed of ethylene, contains 0.5% to 2.3% (mole fraction) acetylene. The presence of a high amount of acetylene in ethylene complicates the polymerization process, deteriorates polymer properties, reduces the activity of the polymerization catalyst, and increases catalyst consumption. Therefore, the acetylene content in ethylene must be reduced to a certain level before it can be used as a monomer for synthesizing polymers.

[0003] Currently, selective hydrogenation is commonly used in industry to remove acetylene from ethylene, with catalysts primarily consisting of noble metals such as Pd, Pt, and Au as active components. To ensure that the ethylene produced by acetylene hydrogenation and the original ethylene in the feedstock are not further hydrogenated to ethane, thus preventing ethylene loss, a high hydrogenation selectivity of the catalyst is essential to improve the economic efficiency of the plant.

[0004] Therefore, C2 hydrogenation is an extremely important process in the petrochemical industry, as it directly affects the stability of the entire ethylene plant operation.

[0005] Based on the hydrogenation materials and conditions, C2 hydrogenation processes are mainly divided into two types: pre-C2 hydrogenation and post-C2 hydrogenation. Since the location of the reactor determines the composition of the reactants, pre-hydrogenation and post-hydrogenation refer to the position of the acetylene hydrogenation reactor relative to the demethanizer. Pre-hydrogenation occurs when the hydrogenation reactor is located before the demethanizer, and post-hydrogenation occurs when the hydrogenation reactor is located after the demethanizer.

[0006] The number of stages in the hydrogenation reactor is determined by the acetylene content at the reactor inlet. Generally, a single-stage hydrogenation process can be used when the acetylene content is below 0.8%; a two-stage hydrogenation process is generally used when the acetylene content is between 0.8% and 1.4%; and a three-stage hydrogenation process is generally required when the acetylene content is above 1.4%.

[0007] In the post-hydrogenation reaction of C2, acetylene undergoes hydrogenation dimerization, generating a series of oligomers with different molecular weights. Because these oligomers cannot flow with the gaseous material or have very low migration rates, they adhere to the catalyst surface or enter the pores for a prolonged period, causing pore blockage. Due to their slow migration rate, they gradually accumulate. These oligomers themselves contain a large number of unsaturated bonds and can further polymerize, eventually forming coke, which significantly reduces the selectivity of the catalyst activity.

[0008] The amount of hydrogenated dimerization product is closely related to the hydrogenation conditions. Under low hydrogen / acetylene conditions, the hydrogenation dimerization reaction of acetylene is very vigorous due to insufficient hydrogen, and the catalyst coking rate will be very rapid.

[0009] For the traditional three-stage hydrogenation process, the total acetylene conversion rate in the first-stage reactor is 50-90%, with a hydrogen / acetylene ratio of 1.0-1.4. The total acetylene conversion rate in the second-stage reactor is 40-20%, with a hydrogen / acetylene ratio of 1.4-2.0. The residual acetylene is completely converted in the third-stage reactor, with a hydrogen / acetylene ratio of 2.5-4.0. The acetylene content at the outlet of the third-stage reactor is generally below 1 ppm.

[0010] During the reaction, the first-stage reactor has the highest alkyne removal load and produces the largest amount of green oil. The hydrogenation dimerization reaction is most vigorous at the inlet of the first-stage reactor, where some of the green oil polymerizes, causing a rapid decrease in catalyst activity in that area. Another point of activity is the outlet of the first-stage reactor. This is because as the hydrogenation reaction proceeds, the hydrogen / alkyne ratio decreases, further increasing the hydrogenation dimerization rate. Furthermore, the increased temperature intensifies the polymerization of the green oil.

[0011] Some C2 post-hydrogenation units employ a two-stage hydrogenation process. Some of the green oil generated in the first-stage reactor enters the second-stage reactor and accumulates at the inlet of the second-stage reactor, forming coke. This rapidly deteriorates the hydrogenation effect of the second-stage reactor, and the acetylene content at the reactor outlet quickly rises to over 1 ppm. Therefore, in principle, the two-stage hydrogenation process requires better catalyst performance, especially better anti-coking properties.

[0012] Some ethylene plants, such as those using diesel, heavy naphtha, or hydrotreated tail oil as feedstock, have higher requirements for catalyst stability due to the low acetylene content in the cracking products and the use of single-stage hydrogenation for the C2 fraction. Generally, after three months of operation, the acetylene content at the reactor outlet increases due to the influence of green oil, failing to meet the requirement of ≤1ppm, necessitating an increase in hydrogen supply, which leads to significant ethylene losses.

[0013] In some three-stage hydrogenation units, the amount of hydrogen supplied is sometimes artificially reduced in order to adjust the hydrogenation load of each reactor, so that the hydrogen / acetylene ratio at the inlet of a certain reactor is even lower than 1. This will greatly accelerate catalyst coking. Although the load of each reactor is adjusted, the catalyst operating cycle is significantly shortened.

[0014] Once the amount of coking reaches more than 10% of the mass of the C2 hydrogenation catalyst, the performance decline is obvious. The formation of green oil has such a serious impact on the performance of the C2 post-hydrogenation catalyst, but hydrogenation dimerization is unavoidable. Therefore, how to reduce the formation of green oil and delay coking has become one of the eternal issues in catalyst design.

[0015] US5856262 reports a method for preparing a low-acid palladium catalyst using potassium hydroxide (or hydroxides of barium, strontium, rubidium, etc.) modified silica as a support, at a space velocity of 3000 h⁻¹. -1 Under the conditions of an inlet temperature of 35℃, an inlet acetylene molar fraction of 0.71%, and a hydrogen-acetylene molar ratio of 1.43, the outlet acetylene molar fraction is less than 1×10⁻⁶. -7 The ethylene selectivity reached 56%.

[0016] CN200810114744.0 discloses a selective hydrogenation catalyst for unsaturated hydrocarbons, its preparation method, and its application method. This catalyst uses alumina as a support and palladium as the active component. The catalyst's resistance to impurities and coking is improved by adding rare earth and alkaline earth metals and fluorine; however, the catalyst selectivity is not ideal.

[0017] CN200810119385.8 discloses a non-precious metal supported selective hydrogenation catalyst, its preparation method, and its application. The catalyst includes a support and a main active component and a co-active component supported on the support. The main active component is Ni, and the co-active component is selected from at least one of Mo, La, Ag, Bi, Cu, Nd, Cs, Ce, Zn, and Zr. Both the main active component and the co-active component exist in amorphous form with an average particle size <10 nm. The support is a non-oxidizing porous material. The catalyst is prepared using a microemulsion method.

[0018] The catalysts prepared by the above methods all use catalysts with a single pore size distribution, which are subject to poor selectivity due to the influence of internal diffusion. Supports with a bimodal pore distribution, while ensuring high catalyst activity, can reduce the influence of internal diffusion and improve catalyst selectivity due to the presence of large pores.

[0019] ZL971187339 discloses a hydrogenation catalyst supported by a honeycomb support, which is a large-pore support and effectively improves the selectivity of the catalyst.

[0020] CN1129606A discloses a hydrocarbon conversion catalyst and its preparation method. The supported catalyst includes alumina, nickel oxide, and iron oxide, and contains two types of pores: one to improve the catalytic reaction surface and the other to facilitate diffusion. CN101433842A discloses a hydrogenation catalyst with a bimodal pore distribution. The most probable radius of the micropores is 2–50 nm, and the most probable radius of the macropores is 100–400 nm. Due to the bimodal pore distribution, the catalyst exhibits both good hydrogenation activity and good selectivity, resulting in a large increase in ethylene production.

[0021] Patent 201310114070.5 discloses a method for selecting C2 fractions. This hydrogenation method employs a catalyst in which the active components Pd and Ag are supported using an aqueous solution impregnation method, while Ni is supported using a W / O microemulsion impregnation method. Using this method, Pd / Ag and Ni are located in channels of different pore sizes, allowing the generated green oil to undergo saturated hydrogenation in the macropores, thus reducing catalyst coking.

[0022] Before a catalyst can be put into operation, it needs to be reduced. Generally, noble metal catalysts have a low reduction temperature, but the reduction temperature of Ni often reaches about 500℃. At this temperature, the reduced Pd atoms are very easy to aggregate, which reduces the catalyst activity by more than 30%. It is necessary to increase the amount of active component by an equal amount to compensate for the loss of activity, but this will cause a decrease in selectivity.

[0023] Patent 201910988247.1 discloses a selective hydrogenation method for C2 fractions. This method uses a catalyst support with a bimodal pore distribution. During catalyst preparation, active components are loaded via two methods: solution and microemulsion. In the solution method, a portion of Pd is loaded into the pores as the active component for the main reaction. Additionally, a W / O type microemulsion with a particle size larger than the support pores is prepared. This microemulsion contains nickel and copper salts, distributing these components within the macropores of the support, forming Ni-Cu active centers.

[0024] The catalyst prepared by this method allows the selective hydrogenation reaction to mainly occur in the micropores, while the green oil generated by the reaction enters the macropores and undergoes saturated hydrogenation at the Ni-Cu active centers, thus reducing the amount of coking on the catalyst.

[0025] However, the reduction temperature of Ni-Cu often reaches around 350℃. At this temperature, reduced Pd atoms easily aggregate, significantly reducing catalyst activity. To lower the reduction temperature of the Ni-Cu active center, a small amount of palladium is loaded onto the outer surface of the Ni-Cu active center using an emulsion method to form a Ni-Cu-Pd active center, which can reduce the reduction temperature to 150℃. The catalyst prepared using this method allows the selective hydrogenation reaction to mainly occur in the micropores, while the green oil generated by the reaction enters the macropores and undergoes saturated hydrogenation in the Ni-Cu active center, reducing catalyst coking. However, since palladium is secondary loaded, some of the palladium loaded in the macropores does not contribute to the hydrogenation of acetylene. Therefore, the palladium content in this catalyst is higher than that of commonly used catalysts, by up to 50% or more, significantly increasing the catalyst cost and making the catalyst preparation process more complex. Summary of the Invention

[0026] The main objective of this invention is to provide a selective hydrogenation method for C2 fractions, overcoming the shortcomings of existing technologies such as complex preparation processes for C2 fraction selective hydrogenation catalysts and easy carbon deposition in the catalysts during the selective hydrogenation process of C2 fractions.

[0027] To achieve the above objectives, this invention provides a selective hydrogenation method for C2 fractions. The C2 fraction enters a reactor for gas-phase hydrogenation to remove acetylene. The reactor inlet temperature is 30–100°C, the reactor pressure is 1.5–3.0 MPa, and the gas hourly space velocity (GHSV) is 1500–12000 h⁻¹. -1 The catalyst used in the gas-phase hydrogenation deacetylene reaction includes a support and an active component. The support comprises Al2O3 with a bimodal pore size distribution, with pore sizes ranging from 15 to 50 nm and 60 to 500 nm, respectively. The active component comprises Pd, Ni, Cu, Pt, Ce, and Ag. Based on 100% of the catalyst mass, the catalyst contains 0.02 to 0.04% Pd, 1 to 5% Ni, 0.2 to 1% Cu, 0.1 to 0.5% Ce, 0.001 to 0.01% Pt, and 0.06 to 0.2% Ag. Ni and Cu are supported using a microemulsion method with a particle size of 50 to 500 nm, while Pd, Pt, Ce, and Ag are supported using a solution method.

[0028] The selective hydrogenation method for C2 fraction of the present invention, wherein the C2 fraction is the C2 fraction from the top of the pre-ethane stripper, and the reactor is a fixed-bed reactor.

[0029] The selective hydrogenation method for C2 fraction of the present invention, wherein the volume content of ethylene in the C2 fraction is 65-93%, the volume content of acetylene is 0.1-2.5%, and the volume content of C3 is 0.01-0.8%.

[0030] The selective hydrogenation method for C2 fractions described in this invention, wherein the Al2O3 has a crystal form of θ, α, or a mixture thereof.

[0031] The selective hydrogenation method for C2 fraction of the present invention includes a single-stage reactor with an inlet hydrogen / acetylene molar ratio of 1.5 to 2.5; or a two-stage reactor with an inlet hydrogen / acetylene molar ratio of 1.1 to 1.4 for the first stage reactor and 1.5 to 2.5 for the second stage reactor; or a three-stage reactor with an inlet hydrogen / acetylene molar ratio of 0.8 to 1.5 for the first stage reactor, 1.0 to 2.0 for the second stage reactor, and 1.5 to 2.5 for the third stage reactor.

[0032] The selective hydrogenation method for C2 fractions of the present invention includes the simultaneous loading of Pt and Ce, and the loading of Ag is carried out after Pd loading and calcination; the loading of Ag is carried out after Pd loading and calcination.

[0033] The selective hydrogenation method for C2 fractions described in this invention includes a solution loading method, which refers to preparing a precursor of the active component into a solution and then loading the precursor of the active component onto a carrier by impregnation; and a microemulsion loading method, which refers to preparing a precursor of the active component into a microemulsion and then loading the precursor of the active component onto a carrier by impregnation.

[0034] The selective hydrogenation method for C2 fractions of the present invention includes the following method for preparing the microemulsion: Ni and Cu precursors are dissolved in water, an oil phase, a surfactant, and a co-surfactant are added, and the mixture is stirred thoroughly to form a microemulsion; wherein the weight ratio of the surfactant to the co-surfactant is 1 to 1.2, the weight ratio of the aqueous phase to the oil phase is 2.0 to 3.0, and the weight ratio of the surfactant to the oil phase is 0.15 to 0.6.

[0035] The selective hydrogenation method for C2 fractions of the present invention, wherein the catalyst preparation method comprises:

[0036] (1) Ni and Cu precursor salts are dissolved in water, and an oil phase, surfactant, and co-surfactant are added. The mixture is stirred thoroughly to form a microemulsion. The conditions for preparing the microemulsion provided in this invention are: the weight ratio of the water phase to the oil phase is 2-3, the weight ratio of the surfactant to the oil phase is 0.15-0.6, the weight ratio of the surfactant to the co-surfactant is 1-1.2, and the particle size of the formed microemulsion is greater than 50 nm and less than 500 nm. The support is added to the prepared microemulsion and impregnated for 0.5-4 hours, and the remaining liquid is filtered off. After drying, the mixture is calcined at 400-600°C to obtain a semi-finished catalyst A.

[0037] (2) Dissolve the precursor salt of Pd in ​​water and adjust the pH to 1.5-3.0, preferably 1.5-2.5. Then add the semi-finished catalyst A into the Pd salt solution, impregnate and adsorb for 0.5-4 hours, dry and calcine at 300-550℃, preferably 420-520℃, to obtain the semi-finished catalyst B.

[0038] (3) Dissolve the precursor salts of Pt and Ce in deionized water, adjust the pH to 1.0-5.0, preferably 1.0-3.0, and then add the semi-finished catalyst B to the prepared solution. After the solution is completely absorbed, dry it and calcine it at 400-600℃ to obtain the semi-finished catalyst C.

[0039] (4) The precursor salt of Ag is dissolved in deionized water. The semi-finished catalyst C prepared above is immersed in the salt solution of Ag, dried and then calcined at 400-600℃ to obtain the desired catalyst.

[0040] According to a specific embodiment of the present invention, steps (1) and (2) can be interchanged, step (3) is after step (2), and step (4) is after step (2).

[0041] The beneficial effects of this invention are:

[0042] The present invention has a low loading of palladium, and solves the problem of palladium aggregation during activation by loading Ce and Pt through solution method. This results in a catalyst with high catalyst activity and selectivity, and the catalyst regeneration times are increased, extending the catalyst life. At the same time, the catalyst preparation method of the present invention is simple and easy to industrialize.

[0043] The loading of silver can change the electronic structure of the active center palladium atoms. The silver atoms spatially separate the palladium atoms, which on the one hand improves the selectivity of the catalyst, and on the other hand prevents the formation of strongly adsorbed species of acetylene, reduces the probability of acetylene hydrogenation dimerization, reduces the amount of green oil generated, and extends the catalyst's operating life. Detailed Implementation

[0044] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0045] This invention provides a selective hydrogenation method for C2 fractions. The C2 fractions enter a reactor for gas-phase hydrogenation to remove acetylene. The reactor inlet temperature is 30–100°C, the reactor pressure is 1.5–3.0 MPa, and the gas hourly space velocity (GHSV) is 1500–12000 h⁻¹. -1 For example, 2000-11000h -1 The catalyst used in the gas-phase hydrogenation deacetylene reaction includes a support and an active component. The support is Al2O3 with a bimodal pore size distribution, with pore sizes of 15–50 nm and 60–500 nm, respectively. The active component includes at least Pd, Ni, Cu, Pt, Ce, and Ag. Based on 100% of the catalyst mass, the catalyst contains 0.02–0.04% Pd, 1–5% Ni, 0.2–1% Cu, 0.1–0.5% Ce, 0.001–0.01% Pt, and 0.06–0.2% Ag. Ni and Cu are supported using a microemulsion method with a microemulsion particle size of 50–500 nm, while Pd, Pt, Ce, and Ag are supported using a solution method.

[0046] The C2 fraction of this invention is mainly composed of ethylene, with a small amount of acetylene. In one embodiment, the C2 fraction of this invention is the C2 fraction from the top of the pre-ethane stripper; in another embodiment, the volume content of ethylene in the C2 fraction of this invention is 65-93%, and the volume content of acetylene is 0.1-2.5%, with the above contents calculated based on the total volume of the C2 fraction as 100%.

[0047] In this invention, the active component Ni-Cu is supported in a microemulsion and mainly distributed in the macropores of the support, while the active components Pd, Pt, Ce, and Ag are supported in a solution and mainly distributed in the micropores of the support. This allows the selective hydrogenation of acetylene to occur primarily under the catalysis of Pd in ​​the micropores, producing ethylene. The larger molecular size byproducts generated in the reaction, mainly C4 to C6 fractions, more easily enter the macropores and undergo saturation hydrogenation at the Ni-Cu active centers. Because these larger molecular size byproducts are hydrogenated to saturation, their molecular chains no longer grow, making them easier to carry out of the reactor, thus reducing catalyst coking. Furthermore, the reduction temperature of Ni-Cu often reaches around 350°C, at which temperature reduced Pd atoms easily aggregate. This invention, through the solution loading of Pt and Ce, can significantly alleviate Pd atom aggregation even at a reduction temperature of 350°C, extending the catalyst's lifespan.

[0048] In detail, when Pt and Ce are impregnated as metal salts, Pt exists, for example, in anionic form, more specifically in the form of chloroplatinic acid, and Ce exists, for example, in cation form, such as the formation of cerium chloride or cerium nitrate. This results in the formation of cerium chloroplatinate ion pairs, and a small amount of platinum will necessarily react with Ce. 4+ Together, during the roasting and activation process, cerium first transforms into cerium oxide, which covers the surface of alumina, while platinum forms platinum oxide. The bonding force between the two is much stronger than that between platinum oxide and alumina, thus forming a strong bond. This bond essentially exists in the form of single platinum atoms, acting like a "fence" around palladium atoms, preventing palladium atom migration, and thus alleviating the aggregation of Pd atoms.

[0049] The catalyst of the present invention comprises a support and an active component, wherein the active component is supported on the support. In one embodiment, the support of the present invention is Al2O3 or mainly Al2O3, wherein the Al2O3 crystal form is preferably θ, α, or a mixture thereof. In another embodiment, the catalyst support of the present invention further includes titanium oxide, for example, the titanium oxide content is 10% by mass. In yet another embodiment, the support of the present invention is spherical, cylindrical, clover-shaped, four-leaf clover-shaped, etc., but the present invention is not limited thereto.

[0050] The present invention does not specifically limit the ratio of macropore volume to micropore volume in the bimodal pore size of the carrier, and can be appropriately adjusted according to the loading content of the active component.

[0051] The catalyst active components of this invention include at least Pd, Ni, Cu, Pt, Ce, and Ag. Ni and Cu are supported in a microemulsion with a particle size of 50–500 nm. Pd, Pt, Ce, and Ag are supported in a solution. This results in the active components Pd, Pt, Ce, and Ag being mainly distributed in small pores of 20–50 nm, and the active components Ni and Cu being mainly distributed in large pores of 90–500 nm.

[0052] Among them, solution loading refers to preparing the precursor of the active component into a solution and then loading the active component precursor onto the carrier by impregnation; microemulsion loading refers to preparing the precursor of the active component into a microemulsion and then loading the active component precursor onto the carrier by impregnation.

[0053] In this invention, Pd, Pt, Ce, and Ag are loaded using a solution method, that is, Pd precursor, Pt precursor, Ce precursor, and Ag precursor are prepared into a solution, and then added to a support for impregnation. In this invention, Ni and Cu are loaded using a microemulsion method, that is, Ni precursor and Cu precursor are prepared into a microemulsion, and then added to a support for loading.

[0054] The present invention does not particularly limit the method of preparing the microemulsion. For example, the method of preparing the microemulsion is as follows: Ni and Cu precursors are dissolved in water, an oil phase, a surfactant and a co-surfactant are added, and the mixture is stirred thoroughly to form a microemulsion; wherein the weight ratio of the surfactant and the co-surfactant is 1 to 1.2, the weight ratio of the aqueous phase to the oil phase is 2.0 to 3.0, and the weight ratio of the surfactant to the oil phase is 0.15 to 0.6.

[0055] In this invention, Pt and Ce are simultaneously loaded, and this must be done after Pd loading and calcination; Ag is loaded alone or simultaneously with Pt and Ce, also after Pd loading and calcination. This invention does not particularly limit the order of Ni / Cu microemulsion loading and Pd solution loading, nor does it limit the order of Ni / Cu microemulsion loading and Pt / Ce / Ag solution loading.

[0056] For example, in one embodiment, the order in which the carrier loads the active components is: (1) Ni and Cu microemulsion loading, (2) Pd solution loading, (3) Pt and Ce solution loading, (4) Ag solution loading; in another embodiment, the order in which the carrier loads the active components is: (1) Ni and Cu microemulsion loading, (2) Pd solution loading, (3) Ag solution loading, (4) Pt and Ce solution loading; in yet another embodiment, the order in which the carrier loads the active components is: (1) Pd solution loading, (2) Pt and Ce solution loading, (3) Ag solution loading, (4) Ni and Cu microemulsion loading; In another embodiment, the order in which the active components are loaded on the carrier is: (1) Pd solution loading, (2) Ag solution loading, (3) Pt and Ce solution loading, (4) Ni and Cu microemulsion loading; in yet another embodiment, the order in which the active components are loaded on the carrier is: (1) Pd solution loading, (2) Ni and Cu microemulsion loading, (3) Ag solution loading, (4) Pt and Ce solution loading; in yet another embodiment, the order in which the active components are loaded on the carrier is: (1) Pd solution loading, (2) Ni and Cu microemulsion loading, (3) Pt and Ce solution loading, (4) Ag solution loading.

[0057] In one embodiment, the loading of Pd and Ag in this invention is achieved using a saturated spray method.

[0058] In one embodiment, the reactor for selective hydrogenation according to the present invention is a fixed-bed reactor, such as an adiabatic or isothermal fixed-bed reactor, and the reactor is packed with at least one catalyst of the present invention, for example, two layers of the present invention catalyst. In another embodiment, the reactor of the present invention is a single-stage reactor, wherein the hydrogen / acetylene molar ratio (i.e., the molar ratio of hydrogen to alkynes in the hydrogenation feedstock) at the reactor inlet is 1.5 to 2.5, and the acetylene volume content at the reactor inlet is 0.1 to 0.9%. In yet another embodiment, the reactor of the present invention is a two-stage reactor, wherein the hydrogen / acetylene molar ratio at the inlet of the first stage reactor is 1.1 to 1.4, the hydrogen / acetylene molar ratio at the inlet of the second stage reactor is 1.5 to 2.5, and the acetylene volume content at the reactor inlet is 0.7 to 2.2%. In yet another embodiment, the reactor of the present invention is a three-stage reactor, wherein the hydrogen / acetylene molar ratio at the inlet of the first stage reactor is 0.8 to 1.5, the hydrogen / acetylene molar ratio at the inlet of the second stage reactor is 1.0 to 2.0, the hydrogen / acetylene molar ratio at the inlet of the third stage reactor is 1.5 to 2.5, and the acetylene volume content at the reactor inlet is 1.0 to 2.5%.

[0059] The selective hydrogenation method for the C2 fraction of this invention can reduce the acetylene content in the reactor outlet product to less than 1 ppm.

[0060] In addition, the catalyst of the present invention has a very slow coking rate during use; even if the catalyst is reduced at 350°C or higher, the performance of the catalyst remains basically unchanged after 5 regenerations, and the initial activity selectivity is very good, indicating that several high-temperature reduction processes do not have a significant impact on the aggregation state of the main active components of the catalyst, and the catalyst has a long service life.

[0061] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0062] Equipment: Dynamic light scattering particle size analyzer (M286572) was used to analyze the particle size distribution of Ni / Cu alloy microemulsions; fully automated mercury porosimetry (MMP) was used to analyze the pore volume, specific surface area, and pore size distribution of the support. The contents of Pd, Ag, Ni, Cu, Ce, and Pt in the catalyst were determined using an A240FS atomic absorption spectrometer.

[0063] Raw materials: Nickel nitrate, copper nitrate, palladium chloride, chloroplatinic acid, silver nitrate, analytical grade, Shanghai Sinopharm Group Co., Ltd.; alumina carrier, Shandong Aluminum Group Co., Ltd.

[0064] Example 1:

[0065] Ⅰ # Catalyst preparation

[0066] Carrier: A commercially available bimodal spherical carrier with an alumina content of 90 wt% and a titanium oxide content of 10 wt% was weighed, with a spherical diameter of 4 mm. After calcination at 1140℃ for 4 hours, the pore size distribution ranges were 25–50 nm and 320–500 nm, respectively, with a water absorption rate of 50% and a specific surface area of ​​20.25 m². 2 / g, weigh out 100g of the carrier.

[0067] (1) Weigh 0.0333g of palladium chloride salt and dissolve it in 140mL of deionized water. Adjust the pH to 1.5. Then add the support to the Pd salt solution, impregnate and adsorb for 50min, dry at 110℃, and calcine at 400℃ for 5h to obtain the desired semi-finished catalyst A.

[0068] (2) Weigh 3.11 g of anhydrous nickel nitrate and 0.59 g of copper nitrate hexahydrate, dissolve them in 72 mL of deionized water, add 36 g of n-hexane, 21.6 g of CATB, and 21.50 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst A to the prepared microemulsion and impregnate for 80 min. Filter out the residual liquid and wash with deionized water until neutral. Dry at 80 °C and calcine at 400 °C for 5 hours to obtain the semi-finished catalyst B.

[0069] (3) Weigh 0.176g of cerium chloride and 0.0021g of chloroplatinic acid and dissolve them in 50mL of deionized water. Adjust the pH to 1.0. Then, immerse the obtained semi-finished catalyst B into the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 400℃ for 5 hours to obtain semi-finished catalyst C.

[0070] (4) Take 50 mL of deionized water, add 0.236 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst C in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 550 °C for 5 hours to obtain the desired catalyst.

[0071] The particle size of the microemulsion prepared in step (2) was determined to be 51.24 nm by dynamic light scattering method.

[0072] The elemental content was determined by atomic absorption spectrometry, resulting in Example 1Ⅰ. # The catalyst contains 0.02% Pd, 1% Ni, 0.2% Cu, 0.1% Ce, 0.001% Pt, and 0.15% Ag.

[0073] II # Catalyst preparation

[0074] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was weighed. After calcination at 1092℃ for 4 hours, the pore size distribution ranges were 20–46 nm and 85–350 nm, respectively, with a water absorption rate of 58% and a specific surface area of ​​39.58 m². 2 / g, weigh out 100g of the carrier.

[0075] (1) Weigh 0.0666g of palladium chloride salt and dissolve it in 140mL of deionized water. Adjust the pH to 2.5. Then add the support to the salt solution of Pd, impregnate and adsorb for 50min, dry at 110℃, and calcine at 400℃ for 5h to obtain the desired semi-finished catalyst D.

[0076] (2) Weigh 3.11 g of anhydrous nickel nitrate and 0.59 g of copper nitrate hexahydrate, dissolve them in 72 mL of deionized water, add 36 g of n-hexane, 21.6 g of CATB, and 21.50 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst D to the prepared microemulsion and impregnate for 80 min. Filter off the excess liquid and wash with deionized water until neutral. Dry at 80 °C and calcine at 400 °C for 5 hours to obtain the semi-finished catalyst E.

[0077] (3) Weigh 0.176g of cerium chloride and 0.0021g of chloroplatinic acid and dissolve them in 60mL of deionized water. Adjust the pH to 3.0. Then, immerse the obtained semi-finished catalyst E in the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 400℃ for 5 hours to obtain semi-finished catalyst Y.

[0078] (4) Take 58 mL of deionized water, add 0.095 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst F in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 550 °C for 5 hours to obtain the desired catalyst.

[0079] The particle size of the microemulsion prepared in step (2) was determined to be 51.24 nm by dynamic light scattering method.

[0080] The elemental content was determined by atomic absorption spectrometry, yielding Example 1II. # The catalyst contains 0.04% Pd, 1% Ni, 0.2% Cu, 0.1% Ce, 0.001% Pt, and 0.06% Ag.

[0081] Comparative Example 1

[0082] Ⅰ # 01 Catalyst Preparation (I) # 01 (without Ni load)

[0083] Carrier: A commercially available bimodal spherical carrier with a pore size distribution of 90% alumina and 10% titanium oxide was weighed, with a diameter of 4 mm. After calcination at 1140℃ for 4 hours, the pore size distribution ranges were 25–50 nm and 320–500 nm, respectively, with a water absorption rate of 50% and a specific surface area of ​​20.25 m². 2 / g, weigh out 100g of the carrier.

[0084] (1) Weigh 0.0333g of palladium chloride salt and dissolve it in 140mL of deionized water. Adjust the pH to 1.5. Then add the support to the Pd salt solution, impregnate and adsorb for 50min, dry at 110℃, and calcine at 400℃ for 5h to obtain the desired semi-finished catalyst A1.

[0085] (2) Weigh 0.59 g of copper nitrate hexahydrate, dissolve it in 72 mL of deionized water, add 36 g of n-hexane, 21.6 g of CATB, and 21.50 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst A1 to the prepared microemulsion and impregnate for 80 min. Filter out the residual liquid and wash with deionized water until neutral. Dry at 80 °C and calcine at 400 °C for 5 hours to obtain the semi-finished catalyst B1.

[0086] (3) Weigh 0.176g of cerium chloride and 0.0021g of chloroplatinic acid and dissolve them in 60mL of deionized water. Adjust the pH to 1.0. Then, immerse the obtained semi-finished catalyst B1 in the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 400℃ for 5 hours to obtain semi-finished catalyst C1.

[0087] (4) Take 49.5 mL of deionized water, add 0.236 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst C1 in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 550 °C for 5 hours to obtain the desired catalyst.

[0088] The particle size of the microemulsion prepared in step (2) was determined to be 51.24 nm by dynamic light scattering method.

[0089] The elemental content was determined by atomic absorption spectrometry, and comparative example I was obtained. # In the preparation of catalyst 01, the Pd content was 0.02%, the Cu content was 0.2%, the Ce content was 0.1%, the Pt content was 0.001%, and the Ag content was 0.15%.

[0090] II # 01 Catalyst Preparation (II) # 01 (without Ni load)

[0091] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was weighed. After calcination at 1092℃ for 4 hours, the pore size distribution ranges were 20–46 nm and 85–350 nm, respectively, with a water absorption rate of 58% and a specific surface area of ​​39.58 m². 2 / g, weigh out 100g of the carrier.

[0092] (1) Weigh 0.0666g of palladium chloride salt and dissolve it in 140mL of deionized water. Adjust the pH to 2.5. Then add the support to the Pd salt solution, impregnate and adsorb for 50min, dry at 110℃, and calcine at 400℃ for 5h to obtain the desired semi-finished catalyst D1.

[0093] (2) Weigh 0.59 g of copper nitrate hexahydrate, dissolve it in 72 mL of deionized water, add 36 g of n-hexane, 21.6 g of CATB, and 21.50 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst D1 to the prepared microemulsion and impregnate for 80 min. Filter out the residual liquid and wash with deionized water until neutral. Dry at 80 °C and calcine at 400 °C for 5 hours to obtain the semi-finished catalyst E1.

[0094] (3) Weigh 0.176g of cerium chloride and 0.0021g of chloroplatinic acid and dissolve them in 60mL of deionized water. Adjust the pH to 3.0. Then, immerse the obtained semi-finished catalyst E1 in the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 400℃ for 5 hours to obtain semi-finished catalyst Y1.

[0095] (4) Take 58 mL of deionized water, add 0.095 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst F in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 550 °C for 5 hours to obtain the desired catalyst.

[0096] The particle size of the microemulsion prepared in step (2) was determined to be 51.24 nm by dynamic light scattering method.

[0097] The elemental content was determined by atomic absorption spectrometry, resulting in Comparative Example 1II. # The catalyst 01 contains 0.04% Pd, 0.2% Cu, 0.1% Ce, 0.001% Pt, and 0.06% Ag.

[0098] Catalyst evaluation

[0099] Operating Condition 1

[0100] Catalyst reduction: Reducing gas: hydrogen; Reduction space velocity: 100 h⁻¹ -1 At a temperature of 350℃, maintain for 4 hours.

[0101] Process conditions: Single-stage hydrogenation, material space velocity 4000 / h, operating pressure 1.5MPa, reactor inlet temperature 100℃, catalyst loading 200mL. Hydrogen / acetylene molar ratio: 2.0 for the first 500 hours; 2.5 from 500 to 1500 hours.

[0102] Composition of C2 fraction:

[0103] Acetylene 0.1% (v / v), ethylene 65% (v / v), C3 0.5% (v / v), the remainder being ethane.

[0104] In Example 1, Ⅰ # Catalyst and II # Each catalyst was loaded with 100 mL. Ⅰ # Filled in the upper part of the reactor, II # It is filled in the lower part of the reactor.

[0105] In Comparative Example 1, I # 01 catalyst and II # 01. 100 mL of each catalyst was loaded. Ⅰ # 01 is filled into the upper part of the reactor, II# 01 is filled in the lower part of the reactor.

[0106] The reaction results are shown in Table 1.

[0107] Table 1. Catalyst evaluation results under operating condition 1

[0108]

[0109] As shown in Table 1, the acetylene content at the reactor inlet was low. After 24 hours, the acetylene content at the reactor outlet in Example 1 and Comparative Example 1 was not significantly different, and both were within acceptable limits. After 500 hours, the acetylene content at the reactor outlet in Comparative Example 1 was close to being unacceptable. After 1500 hours, the difference in acetylene content at the reactor outlet between Example 1 and Comparative Example 1 became significant, and the acetylene content at the reactor outlet in Comparative Example 1 was no longer within acceptable limits. Furthermore, Comparative Example 1Ⅱ01... # The amount of catalyst coking is higher than in Example 1II # More than twice the amount of coking on the catalyst.

[0110] Operating Condition 2

[0111] Catalyst reduction: Reducing gas: hydrogen; Reduction space velocity: 50 h⁻¹ -1 Temperature 400℃, maintain for 4 hours.

[0112] Process conditions: material space velocity 4000 / h, operating pressure 2.0MPa, reactor inlet temperature 50℃, catalyst loading 200mL, hydrogen / acetylene molar ratio 1.5.

[0113] Composition of C2 fraction:

[0114] Acetylene 0.9% (v / v), ethylene 65% (v / v), C3 0.5% (v / v), the remainder being ethane.

[0115] In Example 1, Ⅰ # Catalyst and II # Each catalyst was loaded with 100 mL. Ⅰ # Filled in the upper part of the reactor, II # It is filled in the lower part of the reactor.

[0116] In Comparative Example 1, I # 01 catalyst and II # 01. 100 mL of each catalyst was loaded. Ⅰ # 01 is filled into the upper part of the reactor, II # 01 is filled in the lower part of the reactor.

[0117] The reaction results are shown in Table 2.

[0118] Table 2 Catalyst Evaluation Results under Operating Condition 2

[0119]

[0120] As shown in Table 2, under the evaluation condition of operating condition 2, the acetylene content at the reactor inlet increases. In Example 1, the acetylene content at the reactor outlet remains very low after 200 and 500 hours. In Comparative Example 1, the catalyst is already unqualified after 200 hours, and the acetylene content at the reactor outlet after 500 hours far exceeds the required value, indicating significant catalyst coking.

[0121] Example 2

[0122] III # Catalyst preparation:

[0123] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was weighed. After calcination at 1115℃ for 4 hours, the pore size distribution ranges were 27–46 nm and 260–440 nm, respectively, with a water absorption rate of 55% and a specific surface area of ​​25 m². 2 / g, weigh out 100g of the carrier.

[0124] (1) Weigh 6.629 g of anhydrous nickel chloride and 1.059 g of copper chloride and dissolve them in 80 mL of deionized water. Add 36.7 g of cyclohexane, 20.55 g of Triton X-100, and 20.34 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 4 hours. Filter out the excess liquid, dry at 80 °C, and calcine at 400 °C for 4 hours to obtain the desired semi-finished catalyst F.

[0125] (2) Weigh 0.065g of palladium nitrate and dissolve it in 120mL of deionized water. Adjust the pH to 2.2. Then add the semi-finished catalyst F to the salt solution of Pd. After soaking and adsorption for 1 hour, dry at 120℃ and calcine at 500℃ for 4 hours to obtain the finished catalyst G.

[0126] (3) Weigh 0.93g of cerium nitrate and 0.0063g of chloroplatinic acid and dissolve them in 60mL of deionized water. Adjust the pH to 2.5. Then, immerse the obtained semi-finished catalyst G into the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 500℃ for 5 hours to obtain the semi-finished catalyst H.

[0127] (4) Take 50 mL of deionized water, add 0.315 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst H in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 600 °C for 5 hours to obtain the desired catalyst.

[0128] The particle size of the microemulsion prepared in step (1) was determined to be 66.41 nm by dynamic light scattering (laser light scattering).

[0129] The elemental content was determined by atomic absorption spectrometry, as shown in Example 2Ⅲ. # The catalyst contains 0.03% Pd, 3% Ni, 0.5% Cu, 0.3% Ce, 0.003% Pt, and 0.2% Ag.

[0130] IV # Catalyst preparation

[0131] Carrier: Weigh out commercially available bimodal spherical alumina carrier with a diameter of 4 mm. After calcination at 1090℃ for 4 hours, the pore size distribution ranges are 15-30 nm and 80-180 nm, respectively. The water absorption rate is 60%, and the specific surface area is 45 m² / g. Weigh out 100 g of this carrier.

[0132] (1) Weigh 6.629 g of anhydrous nickel chloride and 1.059 g of copper chloride and dissolve them in 80 mL of deionized water. Add 36.7 g of cyclohexane, 20.55 g of Triton X-100, and 20.34 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 4 hours. Filter out the excess liquid, dry at 80 °C, and calcine at 400 °C for 4 hours to obtain the desired semi-finished catalyst I.

[0133] (2) Weigh 0.0666g of palladium chloride salt and dissolve it in 120mL of deionized water. Adjust the pH to 2.2. Then add the semi-finished catalyst I to the salt solution of Pd. After impregnation and adsorption for 1 hour, dry at 120℃ and calcine at 500℃ for 4 hours to obtain the finished catalyst J.

[0134] (3) Weigh 0.93g of cerium nitrate and 0.0063g of chloroplatinic acid and dissolve them in 60mL of deionized water. Adjust the pH to 2.5. Then, immerse the obtained semi-finished catalyst J in the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 500℃ for 5 hours to obtain the semi-finished catalyst K.

[0135] (4) Take 60 mL of deionized water, add 0.315 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst K in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 600 °C for 5 hours to obtain the desired catalyst.

[0136] The particle size of the microemulsion prepared in step (1) was determined to be 66.41 nm by dynamic light scattering (laser light scattering).

[0137] The elemental content was determined by atomic absorption spectrometry, as shown in Example 2Ⅲ. #The catalyst contains 0.04% Pd, 3% Ni, 0.5% Cu, 0.3% Ce, 0.003% Pt, and 0.2% Ag.

[0138] Comparative Example 2

[0139] III # 01 Catalyst Preparation: (Without Ce Support)

[0140] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was weighed. After calcination at 1115℃ for 4 hours, the pore size distribution ranges were 27–46 nm and 260–440 nm, respectively, with a water absorption rate of 55% and a specific surface area of ​​25 m². 2 / g, weigh out 100g of the carrier.

[0141] (1) Weigh 6.629 g of anhydrous nickel chloride and 1.059 g of copper chloride and dissolve them in 80 mL of deionized water. Add 36.7 g of cyclohexane, 20.55 g of Triton X-100, and 20.34 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 4 hours. Filter out the excess liquid, dry at 80 °C, and calcine at 400 °C for 4 hours to obtain the desired semi-finished catalyst F1.

[0142] (2) Weigh 0.065g of palladium nitrate and dissolve it in 120mL of deionized water. Adjust the pH to 2.2. Then add the semi-finished catalyst F1 to the salt solution of Pd. After soaking and adsorption for 1 hour, dry at 120℃ and calcine at 500℃ for 4 hours to obtain the finished catalyst G1.

[0143] (3) Weigh 0.0063g of chloroplatinic acid and dissolve it in 60mL of deionized water. Adjust the pH to 2.5. Then, immerse the resulting semi-finished catalyst G1 in the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 500℃ for 5 hours to obtain the semi-finished catalyst H1.

[0144] (4) Take 50 mL of deionized water, add 0.315 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst H1 in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 600 °C for 5 hours to obtain the desired catalyst.

[0145] The particle size of the microemulsion prepared in step (1) was determined to be 66.41 nm by dynamic light scattering (laser light scattering).

[0146] The elemental content was determined by atomic absorption spectrometry, as shown in Example 2Ⅲ. #The catalyst contains 0.03% Pd, 3% Ni, 0.5% Cu, 0.003% Pt, and 0.2% Ag.

[0147] IV # 01 Catalyst Preparation (without Ce loading)

[0148] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was weighed. After calcination at 1090℃ for 4 hours, the pore size distribution ranges were 15–30 nm and 80–180 nm, respectively, with a water absorption rate of 60% and a specific surface area of ​​45 m². 2 / g, weigh out 100g of the carrier.

[0149] (1) Weigh 6.629 g of anhydrous nickel chloride and 1.059 g of copper chloride and dissolve them in 80 mL of deionized water. Add 36.7 g of cyclohexane, 20.55 g of Triton X-100, and 20.34 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 4 hours. Filter out the excess liquid, dry at 80 °C, and calcine at 400 °C for 4 hours to obtain the desired semi-finished catalyst I1.

[0150] (2) Weigh 0.0666g of palladium chloride salt and dissolve it in 120mL of deionized water. Adjust the pH to 2.2. Then add the semi-finished catalyst I1 to the salt solution of Pd. After soaking and adsorption for 1 hour, dry at 120℃ and calcine at 500℃ for 4 hours to obtain the finished catalyst J1.

[0151] (3) Weigh 0.0063g of chloroplatinic acid and dissolve it in 60mL of deionized water. Adjust the pH to 2.5. Then, immerse the resulting semi-finished catalyst J1 in the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 500℃ for 5 hours to obtain the semi-finished catalyst K1.

[0152] (4) Take 60 mL of deionized water, add 0.315 g of silver nitrate to dissolve it completely, immerse the semi-finished catalyst K1 in the prepared solution, shake for 10 min, dry at 100 °C, and calcine at 600 °C for 5 hours to obtain the desired catalyst.

[0153] The particle size of the microemulsion prepared in step (1) was determined to be 66.41 nm by dynamic light scattering (laser light scattering).

[0154] The elemental content was determined by atomic absorption spectrometry, as shown in Example 2Ⅲ. # The catalyst contains 0.04% Pd, 3% Ni, 0.5% Cu, 0.003% Pt, and 0.2% Ag.

[0155] Catalyst evaluation

[0156] Catalyst reduction: Reducing gas: hydrogen; Reduction space velocity: 100 h⁻¹ -1 Temperature 400℃, maintain for 4 hours.

[0157] Process conditions: Single-stage hydrogenation, material space velocity 3500 h, operating pressure 1.5 MPa, reactor inlet temperature 50 °C, catalyst loading 200 mL. Hydrogen / acetylene molar ratio: 1.5 for the first 200 hours; 2.0 after 200 hours.

[0158] Composition of C2 fraction hydrogenation feedstock:

[0159] Acetylene 0.6% (v / v), ethylene 85% (v / v), C3 0.5% (v / v), the remainder being ethane.

[0160] In Example 2, Ⅲ # Catalyst and IV # Each catalyst was filled to 100 ml, of which IV # The catalyst is packed in the lower part of the reactor, III # The catalyst is packed in the upper part of the reactor;

[0161] In Comparative Example 2, III # 01 Catalyst and IV # 01 Each catalyst is filled with 100ml, of which IV # 01 The catalyst is packed in the lower part of the reactor, III # 01 The catalyst is loaded into the upper part of the reactor.

[0162] The reaction results are shown in Table 3.

[0163] Table 3 Catalyst Evaluation Results

[0164]

[0165] As shown in Table 3, in the initial stage of the reaction, the acetylene content at the reactor outlet of Comparative Example 2 was higher than that of Example 2. This difference widened with increasing reaction time, and by 400 hours, the acetylene content at the reactor outlet of Comparative Example 2 was already substandard. After five regenerations, the catalyst of Comparative Example 2 failed to meet the requirements in the initial stage of the reaction. The reason may be that, without Ce loading, reduction at 400℃ already adversely affected the catalyst performance. Without Ce loading, after five regenerations, the aggregation of Pd active centers was severe, leading to a decrease in catalyst selectivity. Therefore, after five regenerations, the catalyst of Comparative Example 2 could not completely convert acetylene in the initial stage of the reaction.

[0166] Example 3

[0167] Catalyst preparation:

[0168] A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After calcination at 1200℃ for 4 hours, the pore size distribution ranges were 40–50 nm and 350–500 nm, respectively, with a water absorption rate of 50% and a specific surface area of ​​19.97 m². 2 / g, weigh out 100g of the carrier.

[0169] (1) Weigh 9.34 g of anhydrous nickel nitrate and 1.48 g of copper nitrate and dissolve them in 84 mL of deionized water. Add 28 g of cyclohexane, 4.2 g of Triton X-100, and 3.5 g of n-pentanol, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 30 min. Filter out the excess liquid, dry at 40 °C, and calcine at 600 °C for 6 h to obtain the semi-finished catalyst M.

[0170] (2) Weigh 0.058g of palladium chloride and dissolve it in 120mL of deionized water. Adjust the pH to 1.7. Then add the semi-finished catalyst M to the salt solution of Pd. After soaking and adsorption for 30min, dry at 100℃ and calcine at 600℃ for 6h to obtain the semi-finished catalyst N.

[0171] (3) Take 0.62g of 0.93 cerium nitrate and 0.011g of chloroplatinic acid and dissolve them in 50mL of deionized water. Adjust the pH to 2.2. Then, immerse the obtained semi-finished catalyst N into the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 500℃ for 5 hours to obtain the semi-finished catalyst O.

[0172] (4) Weigh 0.095g of silver nitrate salt and dissolve it in 50mL of deionized water. Add the semi-finished catalyst I1 to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 120℃, and calcine at 500℃ for 4 hours to obtain the finished catalyst.

[0173] The particle size of the microemulsion prepared in step (1) was determined to be 499.12 nm by dynamic light scattering method.

[0174] The elemental content was determined by atomic absorption spectrometry, and the catalyst prepared in Example 3 contained 0.035% Pd, 3% Ni, 0.5% Cu, 0.2% Ce, 0.005% Pt, and 0.06% Ag.

[0175] Comparative Example 3: (Unloaded Pt)

[0176] Catalyst preparation:

[0177] A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After calcination at 1200℃ for 4 hours, the pore size distribution ranges were 40–50 nm and 350–500 nm, respectively, with a water absorption rate of 50% and a specific surface area of ​​19.97 m².2 / g, weigh out 100g of the carrier.

[0178] (1) Weigh 9.34 g of anhydrous nickel nitrate and 1.48 g of copper nitrate, dissolve them in 84 mL of deionized water, add 28 g of cyclohexane, 4.2 g of Triton X-100, and 3.5 g of n-pentanol in water, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 30 min, filter out the excess liquid, dry at 40 °C, and calcine at 600 °C for 6 h to obtain the semi-finished catalyst M1.

[0179] (2) Weigh 0.058g of palladium chloride and dissolve it in 120mL of deionized water. Adjust the pH to 1.7. Then add the semi-finished catalyst M1 to the salt solution of Pd. After soaking and adsorption for 30min, dry at 100℃ and calcine at 600℃ for 6h to obtain the semi-finished catalyst N1.

[0180] (3) Take 0.62 g of 0.93 cerium nitrate, dissolve it in 50 mL of deionized water, adjust the pH to 2.2, and then immerse the resulting semi-finished catalyst N1 into the prepared solution. After the solution is completely absorbed, dry it at 120 °C for 5 hours and calcine it at 500 °C for 5 hours to obtain the semi-finished catalyst O1.

[0181] (4) Weigh 0.095g of silver nitrate salt and dissolve it in 50mL of deionized water. Add the semi-finished catalyst O1 to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 120℃, and calcine at 500℃ for 4 hours to obtain the finished catalyst.

[0182] The particle size of the microemulsion prepared in step (1) was determined to be 499.12 nm by dynamic light scattering method.

[0183] The elemental contents were determined by atomic absorption spectrometry, and the catalyst prepared in Comparative Example 3 contained 0.035% Pd, 3% Ni, 0.5% Cu, 0.2% Ce, and 0.06% Ag.

[0184] Catalyst evaluation

[0185] Catalyst reduction: Reducing gas: hydrogen; Reduction space velocity: 100 h⁻¹ -1 At a temperature of 380℃, maintain for 4 hours.

[0186] hydrogenation reaction conditions

[0187] The process involves a two-stage reactor with a material space velocity of 1500 h, an operating pressure of 2.6 MPa, and a catalyst loading of 200 mL.

[0188] Evaluation time: 500 hours

[0189] Material composition: Acetylene at the inlet of the two-stage reactor: 0.7% (v / v), ethylene: 80% (v / v), C3: 0.2%, with the remainder being ethane.

[0190] The process parameters are shown in Table 4, and the catalyst evaluation results are shown in Table 5.

[0191] Table 4 Process Parameters

[0192] A section Second section hydrogen / acetylene molar ratio 1.4 1.5 Inlet temperature ℃ 30 60

[0193] Table 5 Catalyst Evaluation Results

[0194]

[0195] As shown in Table 5, within the first 24 hours of the catalyst cycle, there was a difference in the acetylene conversion rate at the first stage outlet between Example 3 and Comparative Example 3, but no difference in the acetylene conversion rate at the second stage outlet. After 500 hours, there was a difference in the acetylene conversion rate at the second stage outlet between Example 3 and Comparative Example 3. After five catalyst regenerations, the acetylene conversion rate at the second stage outlet of Comparative Example 3 was already unacceptable after 24 hours. The reason is that without Pt loading, the active components agglomerated during reduction at high temperatures, leading to a decrease in catalyst activity selectivity. The more times the catalyst was regenerated, the greater the decline in the performance of the unloaded Pt catalyst in Comparative Example 3, and the greater the difference from Example 3.

[0196] Example 4

[0197] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 3 mm was used. After calcination at 1050℃ for 4 hours, the bimodal pore size distribution ranged from 15 to 30 nm and 60 to 130 nm, with a water absorption rate of 57% and a specific surface area of ​​49.82 m². 2 / g, weigh out 100g of the carrier.

[0198] Catalyst preparation:

[0199] (1) Weigh 15.57g of anhydrous nickel nitrate and 2.95g of anhydrous copper nitrate, dissolve them in 65mL of deionized water, add 30.23g of n-hexane, 17g of CTAB and 17g of n-butanol, stir thoroughly to form a microemulsion, immerse 100g of the high-temperature calcined carrier into the prepared microemulsion, shake for 90min, filter out the residual liquid, dry at 60℃, and calcine at 450℃ for 6h to obtain the semi-finished catalyst P.

[0200] (2) Weigh 0.058 g of palladium chloride, dissolve it in 100 mL of deionized water, adjust the pH to 2.0, then immerse the semi-finished catalyst P in the prepared Pd salt solution, immerse for 60 min, dry at 100 °C, and calcine at 450 °C for 6 hours to obtain the semi-finished catalyst Q.

[0201] (3) Take 1.55g of 0.93 cerium nitrate and 0.021g of platinum nitrate and dissolve them in 52mL of deionized water. Adjust the pH to 1.7. Then, immerse the obtained semi-finished catalyst Q into the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 450℃ for 5 hours to obtain the semi-finished catalyst R.

[0202] (4) Weigh 0.252 g of silver nitrate and dissolve it in 57 mL of deionized water. Dissolve the semi-finished catalyst R prepared in step (3) in the prepared silver nitrate solution, shake, and after the solution is completely absorbed, dry at 140 °C and calcine at 550 °C for 6 hours to obtain the desired catalyst.

[0203] The particle size of the microemulsion prepared in step (1) of the dynamic light scattering measurement is 60.36 nm.

[0204] The catalyst prepared by atomic absorption spectrometry, in Example 4, had a Pd content of 0.035%, a Ni content of 5%, a Cu content of 1%, a Ce content of 0.2%, a Pt content of 0.005%, and an Ag content of 0.16%.

[0205] Comparative Example 4

[0206] The same carrier and preparation conditions as in Example 4 were used, the difference being that no copper was loaded.

[0207] (1) Weigh 15.57g of anhydrous nickel nitrate, dissolve it in 65mL of deionized water, add 30.23g of n-hexane, 17g of CTAB, and 17g of n-butanol, stir thoroughly to form a microemulsion, immerse 100g of the high-temperature calcined carrier into the prepared microemulsion, shake for 90min, filter out the residual liquid, dry at 60℃, and calcine at 450℃ for 6h to obtain the semi-finished catalyst P.

[0208] (2) Weigh 0.058 g of palladium chloride, dissolve it in 100 mL of deionized water, adjust the pH to 2.0, then immerse the semi-finished catalyst P in the prepared Pd salt solution, immerse for 60 min, dry at 100 °C, and calcine at 450 °C for 6 hours to obtain the semi-finished catalyst Q.

[0209] (3) Take 1.55g of 0.93 cerium nitrate and 0.021g of platinum nitrate and dissolve them in 52mL of deionized water. Adjust the pH to 1.7. Then, immerse the obtained semi-finished catalyst Q into the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 450℃ for 5 hours to obtain the semi-finished catalyst R.

[0210] (4) Weigh 0.252 g of silver nitrate and dissolve it in 57 mL of deionized water. Dissolve the semi-finished catalyst R prepared in step (3) in the prepared silver nitrate solution, shake, and after the solution is completely absorbed, dry at 140 °C and calcine at 550 °C for 6 hours to obtain the desired catalyst.

[0211] The particle size of the microemulsion prepared in step (1) of the dynamic light scattering measurement is 60.36 nm.

[0212] The catalyst prepared by atomic absorption spectrometry, in Comparative Example 4, had a Pd content of 0.035%, a Ni content of 5%, a Ce content of 0.2%, a Pt content of 0.005%, and an Ag content of 0.16%.

[0213] Catalyst evaluation

[0214] Catalyst reduction: Reducing gas: hydrogen; Reduction space velocity: 100 h⁻¹ -1 At a temperature of 380℃, maintain for 4 hours.

[0215] hydrogenation reaction conditions

[0216] Operating Condition 1

[0217] The process involves a two-stage reactor with a material space velocity of 4000 h, an operating pressure of 1.5 MPa, and a catalyst loading of 100 mL.

[0218] Evaluation time: 500 hours

[0219] The composition of the hydrogenation feedstock is as follows: 2.2% (v / v) acetylene, 93% (v / v) ethylene, 0.15% C3, and the remainder is ethane at the inlet of the two-stage reactor. The process parameters are shown in Table 6, and the catalyst evaluation results are shown in Table 7.

[0220] Table 6 Process parameters of each reactor section

[0221] A section Second section hydrogen / acetylene molar ratio 1.1 2.5 Inlet temperature ℃ 30 65

[0222] Table 7 Catalyst Evaluation Results

[0223]

[0224] As shown in Table 7, under operating condition 1, there was no difference in acetylene content between Example 4 and Comparative Example 4 during the first 24 hours of the first cycle. After 500 hours, the acetylene content at the first-stage outlet of Comparative Example 4 was significantly higher than that of Example 4, and the acetylene content at the second-stage outlet of Comparative Example 4 far exceeded the standard. In terms of coking amount after 500 hours, the coking amount of the first-stage catalyst of Comparative Example 4 exceeded 15%, far higher than that of the catalyst in Example 4. The coking amount of the second-stage catalyst of Comparative Example 4 was also more than twice that of the second-stage catalyst in Example 4, indicating that the presence of copper plays a very important role in inhibiting catalyst coking. The reason may be that the catalyst of Comparative Example 4 was not loaded with copper, and the active component nickel could not be reduced at 400°C, thus failing to saturate the hydrogenation of the green oil, leading to the gradual formation of coke on the catalyst. After five catalyst regenerations, the acetylene content at the second-stage outlet of Comparative Example 4 was slightly higher than that at the second-stage outlet of Example 4. The reason may be that the catalyst of Comparative Example 4 had more severe coking, and the high bed temperature during the roasting process affected the structure of the second-stage catalyst; the more regenerations, the greater the impact.

[0225] Operating Condition 2

[0226] The process involves a two-stage reactor with a material space velocity of 6000 h, an operating pressure of 1.5 MPa, and a catalyst loading of 100 mL.

[0227] Evaluation time: 500 hours

[0228] Material composition: Acetylene at the inlet of the two-stage reactor: 1.8% (v / v), ethylene: 85% (v / v), C3: 0.2%, with the remainder being ethane.

[0229] The process parameters are shown in Table 8, and the catalyst evaluation results are shown in Table 9.

[0230] Table 8 Process parameters of each reactor section

[0231] A section Second section hydrogen / acetylene molar ratio 1.25 2.2 Inlet temperature ℃ 35 50

[0232] Table 9 Catalyst Evaluation Results

[0233]

[0234] Under operating condition 2, the catalyst performance of Comparative Example 4 and Example 4 was no different after the first cycle of 24 hours. After the first cycle of 500 hours, the acetylene content at the second-stage outlet of Comparative Example 4 was already substandard. This was mainly because, at 500 hours, both the first and second-stage catalysts of Comparative Example 4 showed severe coking. After five regenerations, the activity selectivity of the catalyst in Comparative Example 4 was slightly lower than that of the catalyst in Example 4, indicating that the absence of either Ce or Pt significantly affects the regeneration performance of the catalyst, and both are indispensable.

[0235] Example 5

[0236] The carrier is a commercially available bimodal spherical alumina-magnesium oxide carrier with a magnesium oxide content of 3% and a diameter of 3 mm. After calcination at 1095℃ for 4 hours, the bimodal pore size distribution ranges from 25 to 40 nm and 110 to 260 nm, with a water absorption rate of 58% and a specific surface area of ​​35.41 m². 2 / g. Weigh 100g of the carrier.

[0237] Catalyst preparation:

[0238] (1) Weigh 11.05 g of nickel chloride and 2.95 g of copper nitrate, dissolve them in 80 mL of deionized water, add 36.00 g of n-hexane, 20.88 g of Triton X-100 and 19.60 g of n-hexanol, stir thoroughly to form a microemulsion, immerse the calcined support in the prepared microemulsion, shake for 180 min, filter out the residual liquid, dry at 70 °C, and calcine at 500 °C for 4 h to obtain the semi-finished catalyst S.

[0239] (2) Weigh 0.087 g of palladium nitrate, dissolve it in 80 mL of deionized water, adjust the pH to 2.3, then immerse the semi-finished catalyst S in the prepared Pd salt solution, immerse for 120 min, dry at 130 °C, and calcine at 500 °C for 4 hours to obtain the semi-finished catalyst T.

[0240] (3) Weigh 0.88g of cerium chloride and 0.0021g of chloroplatinic acid and dissolve them in 55mL of deionized water. Then, immerse the resulting semi-finished catalyst T in the prepared solution. After the solution is completely absorbed, dry it at 120℃ for 5 hours and calcine it at 500℃ for 5 hours. This is called the semi-finished catalyst U.

[0241] (2) Weigh 0.32g of silver nitrate and dissolve it in 58mL of deionized water. Dissolve the semi-finished catalyst U prepared in step (3) in the prepared silver nitrate solution, shake, and after the solution is completely absorbed, dry at 100℃ and calcine at 500℃ for 4 hours to obtain the desired catalyst.

[0242] The steps for preparing dynamic light scattering measurement are as follows: (1) The microemulsion has a particle size of 65.0 nm.

[0243] The elemental content of the catalyst prepared was determined by atomic absorption spectrometry. In the catalyst of Example 5, the Pd content was 0.040%, the Ni content was 5%, the Cu content was 1%, the Ce content was 0.5%, the Pt content was 0.01%, and the Ag content was 0.20%.

[0244] Comparative Example 5

[0245] The catalyst support and preparation conditions were the same as in Example 5, except that the palladium loading was carried out after the platinum and cerium loading.

[0246] (1) Weigh 11.05 g of nickel chloride and 2.95 g of copper nitrate, dissolve them in 80 mL of deionized water, add 36.00 g of n-hexane, 20.88 g of Triton X-100 and 19.60 g of n-hexanol, stir thoroughly to form a microemulsion, immerse the calcined support in the prepared microemulsion, shake for 180 min, filter out the residual liquid, dry at 70 °C, and calcine at 500 °C for 4 h to obtain the semi-finished catalyst S.

[0247] (2) Weigh 0.88g of cerium chloride and 0.0021g of chloroplatinic acid and dissolve them in 55mL of deionized water. Adjust the pH to 2.5. Then, immerse the resulting semi-finished catalyst T in the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 500℃ for 5 hours to obtain the semi-finished catalyst T.

[0248] (3) Weigh 0.087 g of palladium nitrate, dissolve it in 80 mL of deionized water, adjust the pH to 2.3, then immerse the semi-finished catalyst S in the prepared Pd salt solution, immerse for 120 min, dry at 130 °C, and calcine at 400 °C for 4 hours to obtain the semi-finished catalyst U.

[0249] (4) Weigh 0.32g of silver nitrate and dissolve it in 58mL of deionized water. Dissolve the semi-finished catalyst U prepared in step (3) in the prepared silver nitrate solution, shake, and after the solution is completely absorbed, dry at 100℃ and calcine at 500℃ for 4 hours to obtain the desired catalyst.

[0250] The steps for preparing dynamic light scattering measurement are as follows: (1) The microemulsion has a particle size of 65.0 nm.

[0251] The elemental content of the prepared catalyst was determined by atomic absorption spectrometry. In Comparative Example 5, the catalyst contained 0.040% Pd, 5% Ni, 1% Cu, 0.5% Ce, 0.01% Pt, and 0.20% Ag.

[0252] Catalyst evaluation

[0253] Catalyst reduction: Before use, the catalyst is placed in a fixed-bed reactor and reduced at 370°C for 8 hours using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0254] hydrogenation reaction conditions

[0255] Three-stage reactor process: Each stage is an adiabatic reactor, with a material space velocity of 6000 / h, an operating pressure of 2.6 MPa, and a catalyst loading of 100 mL. The reactor conditions are shown in Table 10, and the catalyst evaluation results are shown in Table 11.

[0256] Hydrogenation feedstock composition: Acetylene at the inlet of the first reactor: 2.5% (v / v), ethylene: 93% (v / v), C3: 0.01% (v / v), with the remainder being ethane.

[0257] Table 10 Reactor Conditions for Each Section

[0258]

[0259] Table 11 Catalyst Evaluation Results

[0260]

[0261]

[0262] As shown in Table 11, after 24 hours, the acetylene content at the first-stage outlet of Comparative Example 5 was 0.3%, which was significantly higher than the 0.1% acetylene content at the first-stage outlet of Example 5. This is because Ce-Pt was pre-loaded, which prevented the aggregation of Pd during initial calcination, resulting in excessively small active center particles, and some active center Pd had insufficient activity under this temperature condition. After 500 hours, as the hydrogen / acetylene ratio at the first-stage inlet decreased, the catalyst activity of Comparative Example 5 was more significantly affected. The acetylene content at the outlets of the first-stage and second-stage reactors both significantly exceeded that of Example 5, and the acetylene content at the outlet of the third-stage reactor was already unqualified.

[0263] After 1000 hours, the amount of coking in each reactor section of Comparative Example 5 was significantly greater.

[0264] Example 6

[0265] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 3 mm was used. After calcination at 1150℃ for 4 hours, the bimodal pore size distribution ranged from 32 to 50 nm and 220 to 500 nm, with a water absorption rate of 51% and a specific surface area of ​​20.04 m². 2 / g. Weigh 100g of the carrier.

[0266] Catalyst preparation:

[0267] (1) Weigh 0.05 g of palladium chloride, dissolve it in 80 mL of deionized water, adjust the pH to 1.7, then immerse 100 g of the prepared support in the prepared Pd salt solution, immerse for 120 min, dry at 130 °C for 3 hours, and calcine at 400 °C for 5 hours to obtain the semi-finished catalyst V.

[0268] (2) Weigh 12.00g of nickel nitrate and 2.36g of copper nitrate, dissolve them in 80mL of deionized water, add 40.00g of cyclohexane, 24.00g of Triton X-100 and 24.0g of n-pentanol, stir thoroughly to form a microemulsion, add the semi-finished catalyst V to the prepared microemulsion, shake for 180min, filter out the remaining liquid, dry at 70℃ for 6 hours, and calcine at 500℃ for 5h to obtain the semi-finished catalyst W.

[0269] (3) Weigh 0.189 g of silver nitrate and dissolve it in 50 mL of deionized water. Dissolve the semi-finished catalyst W from step (2) in the prepared silver nitrate solution, shake, and after the solution is completely absorbed, dry at 100 °C for 4 hours and calcine at 500 °C for 5 hours to obtain the semi-finished catalyst X.

[0270] (4) Weigh 0.528g of cerium chloride and 0.0126g of chloroplatinic acid and dissolve them in 50mL of deionized water. Adjust the pH to 1.9. Then, immerse the semi-finished catalyst X in the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 550℃ for 4 hours to obtain the required catalyst.

[0271] The particle size of the microemulsion prepared by dynamic light scattering was 49.88 nm.

[0272] The catalyst prepared by atomic absorption spectrometry, in Example 6, had a Pd content of 0.03%, a Ni content of 4%, a Cu content of 0.8%, a Pt content of 0.006%, a Ce content of 0.3%, and an Ag content of 0.12%.

[0273] Comparative Example 6

[0274] The carrier of Comparative Example 6 is similar to that of Example 6, except that the microemulsion prepared has a particle size smaller than the pore size.

[0275] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 3 mm was used. After calcination at 1150℃ for 4 hours, the bimodal pore size distribution ranged from 32 to 50 nm and 220 to 500 nm, with a water absorption rate of 51% and a specific surface area of ​​20.04 m². 2 / g. Weigh 100g of the carrier.

[0276] Catalyst preparation:

[0277] (1) Weigh 0.05 g of palladium chloride, dissolve it in 80 mL of deionized water, adjust the pH to 1.7, then immerse 100 g of the prepared support in the prepared Pd salt solution, immerse for 120 min, dry at 130 °C for 3 hours, and calcine at 400 °C for 5 hours to obtain the semi-finished catalyst V1.

[0278] (2) Weigh 12.00g of nickel nitrate and 2.36g of copper nitrate, dissolve them in 80mL of deionized water, add 53.00g of cyclohexane, 42.00g of Triton X-100 and 42.0g of n-pentanol, stir thoroughly to form a microemulsion, add the semi-finished catalyst V1 to the prepared microemulsion, shake for 180min, filter out the remaining liquid, dry at 70℃ for 6 hours, and calcine at 500℃ for 5h to obtain the semi-finished catalyst W1.

[0279] (3) Weigh 0.189 g of silver nitrate and dissolve it in 50 mL of deionized water. Dissolve the semi-finished catalyst W1 from step (2) in the prepared silver nitrate solution, shake, and after the solution is completely absorbed, dry at 100 °C for 4 hours and calcine at 500 °C for 5 hours to obtain the semi-finished catalyst X1.

[0280] (4) Weigh 0.528g of cerium chloride and 0.0126g of chloroplatinic acid and dissolve them in 50mL of deionized water. Adjust the pH to 1.9. Then, immerse the semi-finished catalyst X1 in the prepared solution. After the solution is completely absorbed, dry at 120℃ for 5 hours and calcine at 550℃ for 4 hours to obtain the required catalyst.

[0281] The particle size of the microemulsion prepared by dynamic light scattering was 26.23 nm.

[0282] The catalyst prepared by atomic absorption spectrometry, in Comparative Example 6, had a Pd content of 0.03%, a Ni content of 4%, a Cu content of 0.8%, a Pt content of 0.006%, a Ce content of 0.3%, and an Ag content of 0.12%.

[0283] Catalyst evaluation

[0284] Catalyst reduction: Before use, the catalyst is placed in a fixed-bed reactor and reduced at 380°C for 8 hours using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0285] hydrogenation reaction conditions

[0286] The three-stage reactor process consists of two adiabatic stages and one isothermal stage. The material space velocity (HSV) is 8000 h / h in stages one and two, and 12000 h / h in stage three. The operating pressure is 3.0 MPa, and the catalyst loading is 100 mL. The reactor conditions are shown in Table 12, and the catalyst evaluation results are shown in Table 13.

[0287] Material composition: Acetylene at the inlet of the first reactor: 1.7% (v / v), ethylene: 93% (v / v), C3: 0.4%, with the remainder being ethane.

[0288] Table 12 Reactor Conditions for Each Section

[0289]

[0290] Table 13 Catalyst Evaluation Results

[0291]

[0292] As shown in Table 13, the catalysts of Comparative Example 6 and Example 6 exhibited different activities in the initial stage of the reaction. The reason is that the particle size of the microemulsion during the preparation of the catalyst of Comparative Example 6 was smaller than the maximum pore size of the carrier pores, which caused the loaded Pd active centers to be covered by the post-loaded Ni-Cu. Since the Ni-Cu active centers had insufficient activity under the test conditions, the acetylene content at the outlet of the first reactor of Comparative Example 6 increased.

[0293] Meanwhile, due to the Ni-Cu active centers, the selectivity in the selective hydrogenation reaction of acetylene is also poor. Although the difference in catalyst coking amount is not significant, the acetylene content at the outlet of the three-stage reactor in Comparative Example 6 exceeded the standard after 500 hours. Therefore, the particle size of the microemulsion plays a crucial role in the loading of the active component.

[0294] Therefore, the catalyst prepared by the method of the present invention can reduce the loading of the noble metal component palladium and solve the problem of aggregation of active components during high-temperature reduction of the catalyst, thereby extending the catalyst's operating cycle and service life.

[0295] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for selective hydrogenation of C2 fractions, characterized in that, The C2 fraction enters a reactor for gas-phase hydrogenation to remove acetylene. The reactor inlet temperature is 30–100°C, the reactor pressure is 1.5–3.0 MPa, and the gas hourly space velocity (GHSV) is 1500–12000 h⁻¹. -1 The catalyst used in the gas-phase hydrogenation deacetylene reaction includes a support and an active component. The support comprises Al2O3 with a bimodal pore size distribution, with pore sizes ranging from 15 to 50 nm and 60 to 500 nm, respectively. The active component comprises Pd, Ni, Cu, Pt, Ce, and Ag. Based on 100% of the catalyst mass, the catalyst contains 0.02 to 0.04% Pd, 1 to 5% Ni, 0.2 to 1% Cu, 0.1 to 0.5% Ce, 0.001 to 0.01% Pt, and 0.06 to 0.2% Ag. Ni and Cu are supported using a microemulsion method with a particle size of 50 to 500 nm, while Pd, Pt, Ce, and Ag are supported using a solution method.

2. The selective hydrogenation method for C2 fraction according to claim 1, characterized in that, The C2 fraction is the C2 fraction from the top of the pre-ethane stripper, and the reactor is a fixed-bed reactor.

3. The selective hydrogenation method for C2 fraction according to claim 1, characterized in that, The C2 fraction contains 65-93% ethylene by volume, 0.1-2.5% acetylene by volume, and 0.01-0.8% C3 by volume.

4. The selective hydrogenation method for C2 fraction according to claim 1, characterized in that, The Al2O3 has the crystal form of θ, α or a mixture thereof.

5. The selective hydrogenation method for C2 fraction according to claim 2, characterized in that, The reactor is a single-stage reactor with an inlet hydrogen / acetylene molar ratio of 1.5–2.5; or, the reactor is a two-stage reactor with an inlet hydrogen / acetylene molar ratio of 1.1–1.4 for the first stage reactor and 1.5–2.5 for the second stage reactor; or, the reactor is a three-stage reactor with an inlet hydrogen / acetylene molar ratio of 0.8–1.5 for the first stage reactor, 1.0–2.0 for the second stage reactor, and 1.5–2.5 for the third stage reactor.

6. The selective hydrogenation method for C2 fraction according to claim 1, characterized in that, The Pt and Ce are loaded simultaneously, and the loading is carried out after the Pd is loaded and calcined; the Ag loading is carried out after the Pd is loaded and calcined.

7. The selective hydrogenation method for C2 fraction according to claim 1, characterized in that, Solution loading refers to preparing the precursor of the active component into a solution and then loading the precursor of the active component onto the carrier by impregnation; microemulsion loading refers to preparing the precursor of the active component into a microemulsion and then loading the precursor of the active component onto the carrier by impregnation.

8. The selective hydrogenation method for C2 fraction according to claim 7, characterized in that, The microemulsion is prepared by dissolving Ni and Cu precursors in water, adding an oil phase, a surfactant, and a co-surfactant, and stirring thoroughly to form a microemulsion; wherein the weight ratio of surfactant to co-surfactant is 1 to 1.2, the weight ratio of aqueous phase to oil phase is 2.0 to 3.0, and the weight ratio of surfactant to oil phase is 0.15 to 0.

6.

9. The selective hydrogenation method for C2 fraction according to claim 1, characterized in that, The method for preparing the catalyst includes: (1) Dissolve the precursor salts of Ni and Cu in water, add oil phase, surfactant and co-surfactant, stir thoroughly to form microemulsion, add the carrier into the microemulsion and impregnate for 0.5 to 4 hours, filter out the residual liquid, dry and calcine at 400 to 600°C to obtain semi-finished catalyst A; (2) Dissolve the precursor salt of Pd in ​​water, adjust the pH to 1.5-3.0, add the semi-finished catalyst A into the salt solution of Pd, impregnate and adsorb for 0.5-4h, dry and calcine at 300-550℃ to obtain the semi-finished catalyst B. (3) Dissolve the precursor salts of Pt and Ce in deionized water, adjust the pH to 1.0-5.0, add the semi-finished catalyst B to the prepared solution, and after the solution is completely absorbed, dry and calcine at 400-600℃ to obtain the semi-finished catalyst C. (4) The precursor salt of Ag is dissolved in deionized water, and the semi-finished catalyst C prepared above is immersed in the salt solution of Ag, and then dried and calcined to obtain the desired catalyst.

10. The selective hydrogenation method for C2 fraction according to claim 9, characterized in that... , Step (1) and step (2) can be interchanged, step (3) is after step (2), and step (4) is after step (2).

11. The selective hydrogenation method for C2 fraction according to claim 9, characterized in that, In step (2), the pH is adjusted to 1.5 to 2.5 and the calcination temperature is 420 to 520℃.

12. The selective hydrogenation method for C2 fraction according to claim 9, characterized in that, In step (3), the pH is adjusted to 1.0 to 3.0.

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